CN105118983B - Method for preparing lithium nickel manganese oxide anode material - Google Patents

Abstract

The invention discloses a preparation method of lithium nickel manganese oxide cathode material. The steps are: A, mixing and grinding divalent nickel salt, divalent manganese salt and Li ⁺ lithium compound evenly to obtain a mixture of nickel, manganese and lithium; B, mixing molar weight of divalent nickel salt and divalent manganese salt Sulphate is mixed and ground with the mixture of step A to obtain a reaction mixture; C, transfer the reaction mixture of step B to a polytetrafluoroethylene reactor, add water, add a cover, add a stainless steel reactor jacket to seal, control the reaction temperature, keep warm, and obtain D, take out the reactant in step C, wash with water until no sulfate is detected, and filter with suction to obtain a brown or black solid; E, transfer the brown or black solid to a crucible, and roast in the atmosphere , cooled naturally to obtain lithium nickel manganese oxide cathode material. Abundant raw materials, low price, no environmental pollution, relatively simple, easy to control conditions, relatively simple equipment, a new solid-liquid membrane phase reaction method.

Description

A kind of preparation method of lithium nickel manganese oxide cathode material

technical field

The invention relates to the technical field of battery materials, in particular to a preparation method of lithium nickel manganese oxide positive electrode material.

Background technique

In the most widely used lithium-ion secondary batteries, most of the positive electrode active materials are compounds such as LiCoO ₂ , LiMn ₂ O ₄ , LiNiO ₂ , or compounds based on the three compounds that are inter-doped and modified, the so-called Binary materials (such as LiNi _x Mn _2-x O ₄ , LiCo _x Mn _2-x O ₄ , LiNi _x Co _1-x O _{2 ,} LiNi _0.5 Mn _1.5 O ₄ , etc.) or ternary materials (such as LiNi _x Co _y Mn _{2-x- y} O ₄ , LiNi _1/3 Co _1/3 Mn _1/3 O ₂ , etc.) are positive electrode active materials for lithium ion batteries; or LiFePO ₄ is used as positive electrode active materials. Various compounds have their own advantages and disadvantages as cathode materials for lithium-ion batteries. The methods for synthesizing these materials mainly include liquid phase reaction method and solid phase reaction method. The liquid phase method includes co-precipitation method, sol-gel method, microemulsion method, hydrothermal (or hydrothermal) method and rheological phase synthesis technology, etc. The solid-phase reaction method is to generate corresponding active materials through solid reactants under high temperature conditions (such as literature: Lithium-ion positive electrode material lithium manganate doping modification research [J], Inorganic Salt Industry, 2012, 44( 6): 61-62). High reaction temperature in solid phase reaction (usually between 500-900°C, even as high as 1000°C (for example: Novel synthesis and electrochemical behavior of layered LiNi _0.5 Mn _0.5 O ₂ [J], J. Alloys and Compounds, 2008, 449 : 296–299. Combustion-synthesized LiNi _0.6 Mn _0.2 Co _0.2 O ₂ as cathode material for lithium ion batteries[J], J.Alloys and Compounds, 2014, 609: 143–149), long reaction time (usually 24～36h and The above is even longer than several days (such as literature: Research on the influence of roasting temperature on the structure and electrochemical performance of lithium manganate [J], Inorganic Salt Industry, 2012, 44(7): 31-46). The so-called co-precipitation method, Generally, the precursor of the active material is synthesized by the co-precipitation method, and then the precursor is used as a raw material to synthesize the positive electrode active material of the battery through a solid-state reaction (such as the literature: New composite co-precipitation method for preparing high-energy/high-power lithium-ion secondary batteries _{A high-powered concentration-gradient Li(Ni 0.85 Co 0.12 Mn 0.03 ) O 2} cathode material forlithium ion batteries[J]，J.Power Sources,2014，263：203-208.Co-precipitationsynthesis of Ni _0.6 Co _0.2 Mn _0.2 (OH) ₂ precursor and characterization ofLiNi _0.6 Co _0.2 Mn _0.2 O ₂ cathode material for secondary lithium batteries[J], Electrochimica Acta.2014,130:82-89. Synthesis of lithium-rich and aluminum-doped spinel lithium manganese oxide by wet chemical method and its electrical properties improvement[J], Journal of Inorganic Materials, 2013 , 28(3):337-340), and then the precursor obtained by the co-precipitation method is subjected to a solid-phase reaction to obtain the final product. Obviously, this type of method not only has a complicated synthesis process, but also has the common defects of the solid-phase reaction. Although the sol-gel method can synthesize tiny particles Nano-level positive electrode materials, but also can only synthesize precursors first, and then roast the precursors synthesized by sol-gel method through high-temperature solid-state reaction, and may need follow-up treatment, and finally the target product can be obtained. The process flow of the sol-gel method is not only very complicated, but also the process parameters are very difficult to be strictly controlled (for example, literature: Preparation of Li _1.2 Mn _0.54 Co _0.13 Ni _0.13 O ₂ @V ₂ O ₅ core-shell composites and their electrochemical properties[ J], Journal of Inorganic Materials, 2014, 29(3): 257-263; Research progress of Li(Ni, Co, Mn)O ₂ as cathode material for lithium-ion batteries [J], New Chemical Materials, 2014, 42(7) : 21-23), it is also more difficult to realize the industrialized production of lithium-ion cathode materials. The microemulsion method is a co-precipitation method that uses organic matter as a solvent and mixes with water to form a microemulsion. Obviously, many organic compounds are used in the synthesis process of this method, including organic solvents, organic surfactants, organic additives, etc., and can only be synthesized The precursor of lithium-ion positive electrode material or negative electrode material (such as literature: A new form of manganese carbonate for the negative electrode of lithium-ion batteries [J], J.Power Sources, 2011, 196: 2863-2866; Surfactant-assisted microemulsion approach of chrysanthemum-likeCo ₃ O ₄ microspheres and their application in lithium-ion battery[J], Solid State Ionics, 2013, 231:63–68.); literature "LiNi _1/3 Co _1/3 Mn _1/3 O ₂ - Graphene Composite as a Promising Cathode Lithium-Ion Batteries[J]”(ACS Appl.Mater.Interfaces,2011,3:2966–2972) introduced a microemulsion method to prepare LiNi _1/3 Co _1/3 Mn _1/3 O ₂ and LiNi _1/3 Co _1/3 Mn _1/3 O ₂ -graphene cathode materials, the preparation process may cause adverse effects on the environment, the preparation process is also relatively complicated, and it is difficult to realize the large-scale industrialization of materials Production. The traditional hydrothermal method or hydrothermal method usually uses a certain concentration of the reactant solution in a sealed state in the reactor, and reacts for a certain period of time (usually 12h) under a certain temperature condition (usually 50-200°C). Or more than 24h or even several days), prepare the precursor. The document "Nanostructured Hybrid Layered-Spinel Cathode Material Synthesized by Hydrothermal Method for Lithium-Ion Batteries[J]" (ACS Appl. Mater. Interfaces, 2014, 6: 8363-8368) introduced a hydrothermal method to synthesize layered-spine Li 2 MnO 3 -LiNi 0.5 Mn 1.5 O 2 , LiNi 0.5 Mn 1.5 O 4 , Li ₂ MnO ₃ -LiNi _0.5 Mn _1.5 O ₂ , LiNi _0.5 Mn _1.5 O ₄ . The specific method is: dissolve 2.685g of solid LiOH·H ₂ O in 25mL of deionized water to make a solution, and then slowly add dropwise to the solution containing 1.01g of MnSO ₄ ·H ₂ O and 0.525g of NiSO _{4.6H 2} O and 1.36g (NH ₄ ) ₂ S ₂ O ₈ aqueous solution, then transferred to a sealed reaction kettle, reacted at 180°C for 1 to 24 hours, then dried by vigorous stirring, and finally It is obtained by roasting at 800°C for 8h. The literature "One-step hydrothermal method synthesis of core–shellLiNi _0.5 Mn _1.5 O ₄ spine cathodes for Li-ion batteries[J]" (J.Power Sources, 2014, 256(15): 66-70) also introduced a A method for preparing LiNi _0.5 Mn _1.5 O ₄ cathode materials with a core-shell structure and powder packaging by a hydrothermal method. The typical method is: 12.5 mmol (mmol, the same below) of NiSO ₄ ·6H ₂ O, 37.5 mmol of MnSO ₄ ·H ₂ O and 0.1 mol of urea are dissolved in 25 mL of deionized water to form a solution, and then transfer Put it into a polytetrafluoroethylene reactor, seal it, keep it warm at 180°C for 12 hours, and cool it down to room temperature naturally. After a series of treatments, the precursor of Ni _0.5 Mn _1.5 CO ₃ is obtained, and then washed with deionized water several times to remove impurities, and then passed through 500°C After pretreatment for 3 hours, it was mixed with LiOH·H ₂ O of corresponding stoichiometric quality, and then calcined at 850°C, that is, solid-state reaction synthesis to prepare the target cathode material LiNi _0.5 Mn _1.5 O ₄ . The literature "Preparation of LiNi _0.5 Mn _1.5 O ₄ by hydrothermal method and its electrochemical properties[J]" (Journal of Jilin Institute of Chemical Technology, 2014, 31(1):95-100) introduced a LiNi _0.5 Mn _1.5 O ₄ Methods for the hydrothermal preparation of materials. The specific method and process are as follows: prepare 15 mL of LiOH solutions with concentrations of 0.159, 0.162, 0.165, and 0.169 g·mL ^-1 each, and add the solutions dropwise to a solution containing 0.0075 moles of MnSO ₄ ·H ₂ O and 0.0025 moles of NiSO ₄ · H ₂ O, 0.0075 moles (NH ₄ ) ₂ S ₂ O ₈ in the lining of the reaction kettle, then put it in the blast drying oven at 180°C for 24 hours, then filter with suction, and put the obtained precipitate in the blast drying oven at 120°C The sample was obtained at a constant temperature for 24 hours, and then the obtained sample was placed in a tube furnace under an air atmosphere and heat-treated at a constant temperature of 850° C. for 24 hours to obtain a positive electrode material. The literature "Effect of reduced hydrazine hydrate on the structure and properties of LiNi _0.5 Mn _1.5 O ₄ [J]" (Functional Materials, 2013, 44(11): 1535-1542) also introduced a hydrothermal method to prepare LiNi _0.5 Mn _1.5 O ₄ The technology of positive electrode materials, specifically: under 50°C and stirring conditions, add NiSO ₄ and MnSO ₄ with a molar ratio of 1:3 to the solution of NaOH solution containing a certain amount of hydrazine hydrate to react to synthesize a solid precursor, and then make the precursor The material was mixed with LiOH·H ₂ O, and LiNi _0.5 Mn _1.5 O ₄ material was obtained by solid-state reaction (calcination at 600°C and 850°C for 24h).

Due to the simple preparation process, green and environmental protection, and fine and uniform product particles, the rheological phase synthesis technology has many related specific technical disclosures. The specific method of the rheological phase synthesis method is: mechanically mix two or more solid reactants and grind them uniformly, then add an appropriate amount of water or other solvents to adjust them into a rheological state. In the rheological state, the solid mixture and the solvent are fully contacted to form Non-stratified rheological system. Put the system under appropriate conditions for reaction (heating or heating and stirring to dry, or direct drying) to obtain a reaction precursor, and then thermally decompose the precursor to obtain a sample (see the literature "LiNi _0.5 Mn _1.5 O ₄ / Preparation and electrochemical performance of Ag composites [J]", Chinese Journal of Nonferrous Metals, 2010, 20(4):801-806, etc.). Preparation and electrochemical performance of LiNi _0.5 Mn _1.5 O ₄ /Ag composite material [J]” (Chinese Journal of Nonferrous Metals, 2010, 20(4):801-806) reported the preparation of LiNi _0.5 Mn _1.5 O by rheological phase method ₄ /Ag The specific steps are: fully grind CH ₃ COOLi·2H ₂ O (analytically pure) 3.00g, Ni(NO ₃ ) ₂ (analytical pure) 2.68g and MnCO ₃ (analytical pure) 5.07g, add a certain amount ethanol+water (volume ratio 1:1) solution, the mixture was adjusted to a paste, then 10mL of 30% ammonia water was added, fully ground and dried in an oven at 150°C to obtain a precursor, and then the precursor was heated at 400 ℃ in air atmosphere for 4h to decompose acetate, heated at 850℃ for 6h, and finally heated at 600℃ for 12h (re-oxidation), cooled to obtain LiNi _0.5 Mn _1.5 O ₄ . After adding AgNO ₃ through a series of treatments, LiNi _0.5 Mn _1.5 O ₄ /Ag composite material is finally obtained. Literature "Rheological phase synthesis and electrochemical performance of lithium-ion battery cathode material (LiNi _1/3 Co _1/3 Mn _1/3 O ₂ ) [J]" (Synthetic Chemistry, 2015, 23(3): 191- 193) introduced a LiNi _1/3 Co _{1/ 3} Mn _1/3 O ₂ positive electrode material synthesis method, specifically: in 50mL deionized water, adding Li, Ni, Co, Mn molar ratio is 1.04: Lithium carbonate, nickel nitrate, cobalt trioxide and manganese dioxide at a ratio of 1:1:1, stirred at room temperature for 4 hours to the rheological phase, at 90°C until the water is completely evaporated, and ground to obtain the precursor powder, which is placed in a muffle furnace Calcined at 750°C for 8 hours in atmospheric atmosphere, cooled to room temperature, and ground to obtain gray powder. The literature "Synthesis of ZnO-coated spinel LiNi _0.5 Mn _1.5 O ₄ by rheological phase method [J]" (Battery, 2010, 40(4):205-206), also reported a rheological phase method for the synthesis of LiNi _0.5 Mn _1.5 O ₄ material technology, specifically: according to the stoichiometric ratio of LiNi _0.5 Mn _1.5 O ₄ , mix CH ₃ COOLi, Ni(CH ₃ COO) ₂ , Mn(CH ₃ COO) ₂ , add ethanol-distilled water ( Volume ratio V/V=1:1) to make a paste, add 30% NH ₃ ·H ₂ O to rheological state, dry at 150°C for 6h to obtain a precursor, and place the precursor in a muffle furnace at 400°C Treated for 4 hours, then heated at 850°C for 6 hours, and finally annealed at 600°C for 8 hours, and cooled with the furnace to obtain LiNi _0.5 Mn _1.5 O ₄ . Literature "Preparation and Characterization of 5V Cathode Material LiNi _0.5 Mn _1.5 O _4-x F _x (x=0.01) by Rheological Phase Method [J]" (Fine Chemical Industry, 2010, 2:112-116), Literature "Ethylene Glycol Solvent Research on the synthesis of LiNi _0.5 Mn _1.5 O ₄ cathode material by rheological phase method" (Journal of Xinyu University, 2013, 18(5): 110-112), literature "Synthesis of layered LiMnO ₂ by soft chemical method and research on electrochemical properties "(Journal of Wuhan University (Natural Science Edition), 2004, 50(2):165-168), literature "Synthesis of spinel-type Li _x Mn ₂ O ₄ and its electrochemical properties by rheological phase method" (Journal of Central South University, 2002 , 33(3):250-253), the literature "Structure and properties of one-step synthesis of orthorhombic LiMnO ₂ by rheological phase method [J]" (Journal of Materials Science and Engineering, 2008, 26(1):35-38), etc., LiNi _0.5 Mn _1.5 O _4-x F _x (x＝0.01), LiNi _0.5 Mn _1.5 O ₄ , layered LiMnO ₂ , spinel Li _x Mn ₂ O ₄ and orthorhombic LiMnO ₂ were synthesized by rheological phase method respectively. etc., the specific method is similar to the above-mentioned literature method. In addition, the literature "Structure and electrochemical behaviors of spherical Li _1+x Ni _0.5 Mn _0.5 O _2+δ synthesized by rheological phase reaction method[J]" (Electrochimica Acta,2014,150:89-98) introduced a Li ₁ Rheological phase synthesis technology of _+x Ni _0.5 Mn _0.5 O _2+δ cathode materials. The document "LiNi _0.5 Mn _1.5 O ₄ spinel cathode using room temperature ionic liquid aselectrolyte[J]" (Electrochimica Acta, 2013, 101:151-157.) discloses a spinel cathode material LiNi _0.5 Mn _1.5 O ₄ method, the specific method of this document is: LiOH, Ni(CH ₃ COO) ₂ 4H ₂ O, Mn(CH ₃ COO) ₂ 4H ₂ O and citric acid are mixed according to the molar ratio = 1:0.5:1.5:3.6 Proportionally mixed, adding an appropriate amount of water to adjust the rheological phase, heating at 90°C for 12h to obtain the precursor, heating the precursor at 500°C for 5h in the atmosphere, and then heating up to 680°C, 750°C and 820°C for 8h to obtain the target product. Document "Electrochemical properties of LiNi _0.5 Mn _1.3 Ti _0.2 O ₄ /Li ₄ Ti ₅ O ₁₂ cells[J]" (International Journal of Minerals, Metallurgy and Materials, 2012, 199(5): 457-460), document "Preparation and Electrochemical Properties of LiMn ₂ O ₄ by a Rheological-Phase-Assisted MicrowaveSynthesis Method[J]”(Inorganic Materials,2008,44(5):542–548), literature “RheologicalPhase Synthesis and Electrochemical Properties of Mg-DopedLiNi _0.8 Co _0.2 O ₂ Cathode Materials for Lithium-Ion Battery[J])” (Journal of The Electrochemical Society, 2008, 155(7): A520-A525) and the literature “Synthesis of layered-structure LiMn _1-x Cr _x O ₂ for lithium-ion batteries by the rheological phase method[J]”(Materials Letters,2004,58:1620-1624), etc., introduced rheological phase synthesis technology to synthesize LiNi _0.5 Mn _1.3 Ti _0.2 O ₄ /Li ₄ Ti ₅ O ₁₂ , LiMn ₂ Technology of O ₄ , Mg-doped LiNi _0.8 Co _0.2 O ₂ , and LiMn _1-x Cr _x O ₂ cathode materials for lithium-ion batteries. Obviously, in addition to the complicated technical steps, the rheological phase synthesis technology may also be affected by many uncertain factors, so the rheological phase is relatively random, and the consistency of the comprehensive electrochemical properties of the synthesized materials may be lacking. Therefore, the steps of rheological phase synthesis technology are complicated, the synthesis cost may be high, the consistency of the product may be poor, and it is difficult to achieve effective large-scale industrial production.

U.S. Patent No. 8,431,108 discloses a nano-LiMn ₂ O ₄ , nano-LiNi _0.5 Mn _1.5 O ₄ and nano-LiNi _0.5 Mn _1.5 O _4-δ positive electrode material and a liquid phase preparation method for these materials, specifically a sol- Gel method (ie Sol-gel method) preparation technology. U.S. Patent No. 9,054,379 discloses the liquid phase of AlPO ₄ -LiCoO ₂ , AlPO ₄ -LiNi _0.5 Mn _1.5 O ₄ , AlPO ₄ -LiNi _1/3 Co _1/3 Mn _1/3 O ₄ , etc. Preparation. U.S. Patent No. 8,980,140 discloses Li ₄ Ti ₅ O ₁₂ as the basis, with alkali metals or alkaline earth metals or rare earth metals or lanthanides or actinides, etc. doping modified lithium ion battery composite positive electrode material Li _{(4-g )} A liquid-phase preparation method of A _g Ti ₅ O ₁₂ , Li ₄ A _h Ti _(5-h) O ₁₂ and the like. U.S. Patent No. 8,968,669 discloses a ternary material LiNi _{x Mny} Co _z O ₂ based on K, Na, Cs, Rb, V, Cu, Al, Mg, Fe, Ti, Cr, Zr or C, etc. A liquid-phase preparation method of modified lithium-ion battery composite cathode materials Li _a ( _{Nix Mny Co z ) MeO b} and the like.

Chinese patent application Nos. 201410838921.5 and 201510045813.7 respectively disclose a hydrothermal synthesis method for the synthesis of a LiMn ₂ O ₄ /carbon nanotube composite material and a hollow spherical lithium manganate cathode material by high-temperature solid-state reaction. The specific method of the hydrothermal method of the 201510045813.7 patent is: first mix the potassium sulfate aqueous solution and the potassium persulfate aqueous solution, and then add concentrated sulfuric acid for hydrothermal reaction to obtain hollow manganese dioxide balls, and then mix with soluble lithium salt, ultrasonic treatment, It is obtained by drying and calcining (see abstract and instructions for details). Chinese patent application number 201410843002.7 discloses a coprecipitation method to synthesize Li _1+x Mn _2-xy A _y Q _z O ₄ (A=Al, and or Mg, and or Co; Q=Mg, and or Co, and Or Nb, and or Cr, etc.) material method. Chinese patent application number 201510012421.0 discloses a method for synthesizing nanometer high-purity lithium manganese oxide material by hydrothermal synthesis technology. Its concrete method (see the embodiment 1～embodiment 5 of specification for details) is: configuration reaction solution is in the reaction kettle with 40mL, and reaction solution contains a certain amount of potassium permanganate, ascorbic acid, lithium hydroxide, 160～200 ℃ The reaction was carried out for 5-8 hours, separated and dried to obtain nanometer lithium manganese oxide. Chinese Patent Application No. 201510026386.8 discloses a method for synthesizing lithium nickel manganate LiNi _0.5 Mn _1.5 O ₄ material by co-precipitation combined with solvothermal technology (similar to hydrothermal method). The specific method is: using cetyltrimethylammonium bromide (CTAB) and polyvinylpyrrolidone (PVP) as templates, and urea as precipitant, first synthesize Ni _0.25 Mn _0.75 CO ₃ precursor by solvothermal technique, A method for synthesizing lithium nickel manganese oxide LiNi _0.5 Mn _1.5 O ₄ material through solid phase reaction. Chinese patent application number 201510026729.0 discloses a method for preparing a modified lithium nickel manganese oxide LiNi _0.5 Mn _1.5 O ₄ cathode material. Chinese patent application number 201510043316.3 patent discloses a method of liquid phase reaction combined with heat treatment solid phase reaction, doping and coating with Al ₂ O ₃ and ZrO ₂ to prepare modified lithium manganate LiMn ₂ O ₄ and lithium nickel manganese oxide LiNi _0.5 Mn _1.5 O ₄ method for cathode material. Chinese patent application number 201510067722.3 patent discloses a common lithium cobaltate, lithium nickelate, lithium manganese oxide, lithium nickel manganese oxide, lithium iron phosphate, lithium manganese phosphate, lithium iron silicate, lithium iron fluoride sulfate, etc. Based on the solid state reaction, and then coated with the corresponding coating layer similar or identical to the composition of the matrix, the method of preparing the coating modified lithium ion battery positive electrode material. Chinese patent application number 201510071425.6 patent discloses a liquid phase sol-gel (Sol-gel) method combined with heat treatment (self-propagating combustion method) solid-phase reaction to prepare high-potential lithium-ion battery cathode material lithium nickel manganese oxide LiNi _0.5 Mn _1.5 O ₄ method. Chinese Patent Application No. 201510071733.9 discloses a method for preparing strontium-doped lithium-ion battery cathode material lithium nickel manganese oxide by solid-state reaction.

Comprehensively analyze the existing solid-phase reaction and liquid-phase reaction of LiCoO ₂ , LiMn ₂ O ₄ , LiNiO ₂ , LiFePO ₄ , LiNi _0.5 Mn _1.5 O ₄ and other types of lithium-ion cathode materials disclosed in the above literature reports and related patents. Synthesis and rheological phase methods and other synthetic technologies mainly have obvious defects or deficiencies in the following aspects:

First, the solid-phase reaction synthesis of LiNi _0.5 Mn _1.5 O ₄ and other lithium-ion battery positive electrode materials has poor uniformity, the consistency of the synthesized materials is not good, and impurities are easily mixed in, the reaction speed is slow, the reaction time is too long, the energy consumption is high, and the reaction products It is difficult to control the shape, particle size, etc., and the types of raw materials are severely limited (usually only easily decomposed compounds, oxides, hydroxides, nitrates, acetates, etc. that do not produce impurities), and the synthesis cost is relatively high. High, although large-scale production can be achieved, it is difficult to achieve wide application.

Second, the synthesis of lithium-ion battery cathode materials such as LiNi _0.5 Mn _1.5 O ₄ by microemulsion method uses a large amount of organic solvents and organic surfactants, which have a certain impact on the environment; the formation of microemulsions requires harsh conditions , there are many steps in the synthesis process, the cost of material manufacturing is high, and it is difficult to achieve large-scale and efficient production due to the limitation of the method itself.

Third, LiNi _0.5 Mn _1.5 O ₄ and other lithium-ion battery positive electrode materials by hydrothermal or hydrothermal methods, although there are no solid-phase reaction synthesis technology and microemulsion synthesis technology, etc., have the disadvantages of uneven reaction, long reaction time, serious pollution, and high cost. Or defects, but there are also defects such as high energy consumption, strict control of process conditions, and high technical requirements for equipment. At the same time, the reaction is carried out in a solution state. Due to the limitation of the concentration, the amount of synthetic products is very limited. If the concentration of the solution is greatly increased or increased The volume of the reactor will greatly increase the technical difficulty of synthesis, and the uncertainty of product performance such as structure, morphology, particle size, and electrochemical performance of LiNi _0.5 Mn _1.5 O ₄ will also increase greatly. Hydrothermal synthesis of LiNi _0.5 Mn _1.5 O ₄ and other cathode materials for lithium-ion batteries is also difficult to achieve high-efficiency industrial scale production.

Contents of the invention

In order to solve the deficiencies in the above-mentioned prior art, the purpose of the present invention is to provide a preparation method of lithium nickel manganese oxide cathode material. The method adopts raw materials with abundant raw materials, low price, no or low environmental pollution, and a new solid-liquid membrane phase reaction method with relatively simple conditions, easy control and relatively simple equipment to prepare lithium nickel manganese oxide cathode materials.

In order to achieve the above object, the present invention adopts the following technical solutions:

A preparation method of lithium nickel manganese oxide positive electrode material, comprising the following steps and process conditions:

In the first step, 0.02 to 0.33 mol (mole, the same below) of divalent nickel salt, 0.06 to 1.0 mol of divalent manganese salt, and a lithium compound with a molar number of Li ⁺ of 0.65 to 12.5 mol are mixed and ground evenly to obtain nickel , manganese, lithium mixture;

In the second step, the persulfate whose molar mass is 1.05 to 1.20 times the total molar mass of divalent nickel salt and divalent manganese salt is mixed with the mixture described in the first step to obtain a reaction mixture;

The third step is to transfer the reaction mixture described in the second step into a polytetrafluoroethylene reactor, add 1-50mL of water, cover it, and seal it with a stainless steel reactor jacket, control the reaction temperature at 60-200°C, and keep it warm for 4-36 hours , the resulting reactant;

The fourth step takes out the reactant obtained in the third step, washes with water until no sulfate is detected (add dropwise to the eluate with saturated barium chloride, no turbidity or precipitation, the same below, omitted), suction filtration, to obtain brown or black solid;

The fifth step is to transfer the above-mentioned brown or black solid into a crucible, bake it in an atmosphere of 650-950° C. for 4-12 hours, and cool it down to room temperature naturally to obtain lithium nickel manganese oxide cathode material.

The lithium nickel manganese oxide positive electrode material is prepared by the above method.

In order to better realize the present invention, the divalent nickel salt includes: nickel acetate (NiAc ₂ .4H ₂ O, wherein Ac=acetate, namely CH ₃ COO ^- , the same below), nickel nitrate [Ni(NO ₃ ) ₂ 6H ₂ O], nickel chloride (NiCl ₂ 6H ₂ O) or nickel sulfate (NiSO ₄ 6H ₂ O) or a mixture of two to four in equimolar ratio;

The divalent manganese salts include: manganese acetate (MnAc ₂ .4H ₂ O), manganese nitrate [Mn(NO ₃ ) ₂ .6H ₂ O], manganese chloride (MnCl ₂ .4H ₂ O), manganese sulfate ( MnSO ₄ ·H ₂ O); the lithium compound includes: lithium oxide (Li ₂ O), lithium hydroxide (LiOH·H ₂ O) or a mixture of two to four in equimolar ratio;

The persulfate includes: one of ammonium persulfate [(NH ₄ ) ₂ S ₂ O ₈ ], potassium persulfate (K ₂ S ₂ O ₈ ), sodium persulfate (Na ₂ S ₂ O ₈ ), etc. kind;

The water includes: one of distilled water, purified water, deionized water and the like.

The present invention is a brand-new technical route for synthesizing positive electrode materials of lithium-ion batteries, and its reaction principle is expressed as follows by chemical reaction and solid-liquid film phase diagram:

xNi ²⁺ +yMn ²⁺ +(x+y)S ₂ O ₈ ^2- +nH ₂ O→Ni _x Mn _y O ₂ ·nH ₂ O(s)+(x+y)SO ₄ ^2-

(intermediate or active intermediate, black)

Li ⁺ +Ni _x Mn _y O ₂ ·nH ₂ O(s)→LiNi _x Mn _y O ₄ (s)+nH ₂ O

(brown or black)

Where: x represents the number of moles of Ni, and y represents the number of moles of Mn.

As can be seen from the above reaction formula and Figure 13, because the reactant raw materials are all soluble solid reagents, due to the small amount of water added, only part of the substance on the surface of the solid reactant can be dissolved, and a saturated solution film is formed on the surface of the reaction raw materials , that is, the solid-liquid film phase is formed, and the chemical reaction is carried out at the interface between the reactant and the solution, and because the reaction product active intermediate product Ni _x Mn _y O ₂ ·nH ₂ O and the final product formed by the rapid reaction of the active intermediate product and LiOH LiNi _x Mn _y O ₄ is solid, the product crystallizes from the solution phase and forms a precipitate, and the reactant in the liquid phase decreases and the product also decreases continuously. In addition, the reaction is carried out at an appropriate high temperature (80-200°C) and in a closed environment (the amount of water is basically Keep constant) conditions, the reactants decrease and the crystallization and precipitation of the products accelerate the dissolution of the solid reactants, thereby accelerating the formation of the products, so the chemical reactions of the precipitation of the reactants proceed continuously and rapidly, and the entire "solid-liquid "Membrane phase" synthesis reaction can be completed in a relatively short time.

With scanning electron microscope (SEM, hereinafter the same) observed respectively the morphology of the cathode material of the lithium nickel manganese oxide synthesized by the technology of the present invention, counted its particle size range, its morphology is an approximate regular octahedral shape, the particle size range It is about 0.25-5.0 μm, and the average particle size is about 1.0-3.5 μm; the Ni:Mn molar ratio, nickel and manganese molar ratio of the synthesized samples were analyzed by EDS (Energy Dispersive Spectrometer, that is, X-ray energy spectrum, the same below) technology The average ratio is between 1:2.998～1:3.002 (see below for details: Table 1 of the application specification "Ni:Mn molar ratio (EDS measurement result) of the typical lithium nickel manganese oxide sample of the embodiment"); use XRD to determine the synthesis The crystal structure of the lithium nickel manganese oxide cathode material, the results show that the lithium nickel manganese oxide material is a spinel crystal; The graphite negative electrode used in the battery, 0.5-2.0M LiPF ₆ /EC:DEC:EMC=1:1:1 (EC:DEC:EMC=volume ratio, wherein: EC is ethylene carbonate, DEC is dimethyl carbonate, EMC is ethyl methyl carbonate, hereinafter the same) solution is the electrolyte, the manufactured lithium-ion battery is measured, the open circuit voltage of the battery is 4.75-5.0 volts, the average discharge voltage exceeds 4.5 volts, and its 0.25C charging, 0.5 C discharge rate (charging cut-off voltage 5.0V, discharge cut-off voltage 4.0 volts) discharge the first discharge specific capacity of 109 ~ 159mAh/g, the highest discharge specific capacity of the material is 234mAh/g.

Table 1 Ni:Mn molar ratio (EDS test result) of the typical lithium nickel manganese oxide sample of the embodiment

Explanation of Table 1: 1) EDS test has 3 to 6 test points for each sample; 2) Nickel and manganese atomic percentages (columns 2 and 5) and molar ratios of nickel and manganese (columns 3 and 6) in the table ) are the average of 3 to 6 test results.

Compared with the prior art, the present invention has the following advantages and beneficial effects:

1. LiNi _0.5 Mn _1.5 O ₄ prepared by the present invention is a lithium ion battery positive electrode manufactured by a typical representative lithium nickel manganese oxide positive electrode active material (hereinafter referred to as: lithium nickel manganese oxide positive electrode material or lithium nickel manganese oxide positive electrode active material), It has a higher discharge voltage than the charged lithium ion battery manufactured by the graphite electrode of the existing lithium ion battery as the negative electrode, its average discharge voltage exceeds 4.5 volts, and the highest open circuit voltage reaches 5.0 volts. Therefore, LiNi prepared by the present invention _0.5 Mn _1.5 O ₄ is a typical representative lithium nickel manganese oxide positive electrode active material, and the lithium-ion battery has higher specific energy and higher specific power than the existing lithium-ion battery.

2. The lithium nickel manganese oxide positive electrode active material prepared by the present invention has a higher oxidation state of nickel and manganese metal elements, and its average oxidation number is 3.65 according to the discharge capacity calculation, the highest oxidation number reaches 4.0, and the high oxidation state The presence of nickel and manganese metal ions is conducive to the increase of lithium ion intercalation in the charging process and improves the specific discharge capacity of the battery. Initial discharge specific capacity, the highest initial discharge specific capacity is 159mAh/g, the lowest initial discharge specific capacity is 138mAh/g, the average initial discharge specific capacity is 147.1mAh/g, and the charge-discharge efficiency exceeds 93% after 300 charge-discharge cycles (see Accompanying drawing 10, accompanying drawing 11), the capacity retention rate of 300 charge-discharge cycles exceeds 85% (see embodiment 7 for details). The highest discharge specific capacity is 234mAh/g, reaching the theoretical specific capacity of lithium nickel manganese oxide (the theoretical specific capacity is 250mAh/g (also 276mAh/g), see the literature for details: Enhancement of the highpotential specific charge in layered electrode materials for lithium -ionbatteries[J].J.Mater.Chem.A,2014,2,8589-8598.) 93.6%, the positive electrode made of the synthesized lithium nickel manganese oxide positive electrode material has a good capacity matching relationship with the graphite negative electrode, thus The utilization efficiency of the battery material is effectively improved, and the manufacturing cost of the lithium-ion battery is reduced.

3. The crystal structure of the lithium nickel manganese oxide cathode active material prepared by the present invention is a spinel structure, and the lithium nickel manganese oxide with a spinel structure has a three-dimensional lithium ion intercalation/extraction channel in the charge and discharge process (For details, see the literature "Preparing LiNi _0.5 Mn _1.5 O ₄ nano-plates with superior properties in lithium-ion batteries using bimetal-organic coordination-polymers as precursors[J].J.Mater.Chem.A.2014,2:9322- 9330", document "Facile synthesis of aluminum-dopedLiNi _0.5 Mn _1.5 O ₄ hollow microspheres and their electrochemical performance for high-voltage Li-ion batteries[J].J.Alloys&Compounds.2014,609:54-59", document "Silicon/ graphene based nano-composite anode: large-scale production and stable high capacity for lithium ion batteries [J]. J. Mater. Chem. A, 2014, 2: 9118-9125" and the literature "Size and shape control of LiFePO ₄ nano- crystals for betterlithium ion battery cathode materials[J].Nano Research.2013,6(7):469-477”), the presence of better lithium ion intercalation channels, the good electrical conductivity of the material, greatly improved by its The conductivity of the manufactured electrode reduces the internal resistance of the manufactured lithium-ion battery, and greatly improves the discharge efficiency and discharge specific capacity of the lithium-ion battery. The highest discharge specific capacity of the synthesized positive electrode material is 234mAh/g.

4. The lithium nickel manganese oxide positive electrode active material prepared by the present invention not only has a spinel crystal structure, but also has a material particle size in the range of 0.25 to 5.0 μm. Lithium nickel manganese oxide in this particle size range In the manufacturing process of lithium-ion batteries, the positive electrode material has better processing performance compared with single particle size nanomaterials or single particle size micron materials. Larger particles form positive electrode coatings, and small particle materials It is filled between the gaps of the large particle skeleton, which greatly improves the filling property of the electrode, increases the compaction density of the electrode, and then improves the volume specific capacity and volume specific power of the lithium-ion battery and the volume specific energy of the battery.

5. The synthesis process flow of the lithium nickel manganese oxide positive electrode material of the present invention is relatively simple and easy, the yield is high, and the product preparation cost is relatively low. The content of lithium nickel manganese element of the material (Li:Ni:Mn molar ratio=1:2.999～ 1:3.002) and the particle size of synthetic materials are easier to control. The lithium nickel manganese oxide positive electrode material prepared by the present invention has suitable particle size distribution, uniform distribution of larger and smaller particles, large specific surface area, high thermal stability, and good performance in the existing commonly used lithium ion battery electrolyte medium. Stability, high initial discharge specific capacity, long cycle life and other characteristics, without changing the production process of the original lithium-ion battery, the original production equipment of lithium-ion battery can be used to manufacture high-quality lithium battery with excellent production performance ion secondary battery.

6. The lithium nickel manganese oxide positive electrode material prepared by the present invention can be called "environmentally friendly material", because any solvent or additive harmful to the environment is used in the manufacturing process of the material, and all raw materials used are also pollution-free or polluted to the environment Therefore, there is no or very low environmental pollution in the manufacture and use of lithium-ion battery electrodes and lithium-ion batteries, and the cost of recycling and utilization of waste batteries or harmless treatment is relatively low.

7. The manufacturing process of the lithium nickel manganese oxide positive electrode material prepared by the present invention is simple, the equipment has no special requirements, the synthesis process time is short, the synthesis cycle is short, the energy consumption is low, and almost no pollutants and harmful and toxic by-products are produced. It is conducive to the realization of intensive large-scale industrial production, and has good economic and environmental benefits.

Description of drawings

Fig. 1 is a kind of SEM photograph (illustration: in the SEM photograph, the magnification of embodiment 1 sample is respectively 10000 and 5000 times; the magnification of embodiment 2 sample is respectively 5000 and 7500 times.)

Fig. 2 is the SEM photo of a kind of embodiment 3, 4 synthetic lithium nickel manganese oxide cathode material (illustration: in the SEM photo, the magnification of embodiment 3 sample is 5000 times; The magnification of embodiment 4 sample is respectively 10000 and 5000 times.)

Fig. 3 is the SEM photo of a kind of embodiment 5, 6 synthetic lithium nickel manganese oxide cathode material (illustration: in the SEM photo, the magnification of embodiment 5 sample is 10000 times; The magnification of embodiment 6 sample is respectively 7500 and 5000 times.)

Fig. 4 is the SEM photo of a kind of embodiment 7,8 synthetic lithium nickel manganese oxide cathode material (illustration: in the SEM photo, the magnification of embodiment 7 sample is respectively 7500 and 5000 times; The magnification of embodiment 8 sample is respectively 10000 and 5000 times.)

Fig. 5 is the SEM photograph of a kind of embodiment 9, 10 synthetic lithium nickel manganese oxide cathode material (illustration: in the SEM photograph, the magnification of embodiment 9 sample is respectively 10000 and 5000 times; the magnification of embodiment 10 sample is 5000 times.)

Fig. 6 is the SEM photograph of a kind of embodiment 11,12 synthetic lithium nickel manganese oxide cathode material (illustration: in the SEM photograph, the magnification of embodiment 11 sample is 5000 times; The magnification of embodiment 12 sample is respectively 10000 and 5000 times.)

Figure 7 is an XRD pattern of a lithium nickel manganese oxide positive electrode material synthesized in a typical example of synthesis (illustration: in the XRD pattern, the test condition is a Cu target, and the diffraction angle 2θ: 10-80 degrees; 12 diffraction lines from bottom to top The curves are respectively the XRD diffraction curves of the samples from Example 1 to Example 12.)

Fig. 8 is a charge-discharge curve of a typical synthesized lithium nickel manganese oxide positive electrode material (illustration: the main figure in the figure is the discharge curve of the first charge and discharge cycle of the lithium nickel manganese oxide positive electrode material of Examples 1 to 6; The figure in the upper right corner is the charge-discharge cycle curve corresponding to the first charge-discharge cycle.)

Fig. 9 is a charge-discharge curve of a typical synthesized lithium nickel manganese oxide positive electrode material (illustration: the main figure in the figure is the discharge curve of the first charge and discharge cycle of the lithium nickel manganese oxide positive electrode material of Examples 7 to 12; The figure in the upper right corner is the charge-discharge cycle curve corresponding to the first charge-discharge cycle.)

Figure 10 is a charge-discharge capacity diagram of a typical synthesized lithium nickel manganese oxide positive electrode material (illustration: the figure is a change diagram of the charge-discharge capacity of the typical lithium nickel manganese oxide positive electrode material of Example 7 for 300 charge-discharge cycles.)

Fig. 11 is a 300-cycle discharge efficiency diagram of a synthesized lithium nickel manganese oxide positive electrode material (illustration: the figure is a discharge efficiency change trend diagram of 300 charge-discharge cycles of the typical lithium nickel manganese oxide positive electrode material of embodiment 7, discharge Efficiency = charge capacity / discharge capacity.)

Fig. 12 is a 300-cycle discharge capacity retention efficiency figure of a synthesized lithium nickel manganese oxide positive electrode material (illustration: the figure is a discharge capacity retention rate figure of 300 charge-discharge cycles of the typical lithium nickel manganese oxide positive electrode material of embodiment 7 .)

Figure 13 is a schematic diagram of a solid-liquid film phase.

The rightward arrow indicates that the solid reactant is continuously dissolved, or the product is continuously formed and crystallized and precipitated.

detailed description

The present invention will be further described in detail below in conjunction with the embodiments and the accompanying drawings.

Example 1:

A preparation method of lithium nickel manganese oxide positive electrode material, the steps are:

The first step mixes and grinds 0.02mol of nickel nitrate, 0.06mol of manganese nitrate and 0.65mol of lithium acetate to obtain a mixture of nickel, manganese and lithium;

In the second step, the potassium persulfate of 0.084mol (1.05 times of the total molar amount of nickel salt and manganese salt in the first step) is mixed and ground with the mixture described in the first step to obtain a reaction mixture;

The third step is to transfer the reaction mixture described in the second step into a polytetrafluoroethylene reactor, add 1mL of distilled water, cover and seal with a stainless steel reactor jacket, control the reaction temperature at 60°C, and keep it warm for 36 hours to obtain the reactant;

The fourth step is to take out the reactant obtained in the third step, wash with distilled water until no sulfate is detected, and filter with suction to obtain a brown or black solid;

The fifth step is to transfer the above-mentioned brown or black solid into a crucible, bake it for 4 hours in an atmosphere at 650° C., and cool it down to room temperature naturally to obtain a lithium nickel manganese oxide cathode material.

The morphology of the lithium nickel manganese oxide material was observed by SEM, and the particle size range was counted. Its shape is an approximate regular octahedral shape, the particle size range is 0.4-5 μm, and the average particle size is about 2.5 μm (see Accompanying drawing 1); Measured the Ni:Mn mol ratio of lithium nickel manganese oxide material with EDS, the Ni of test: Mn mol ratio average value is: 1:3.001 (see: table 1); Determine the crystal of product with XRD structure, the results show that the lithium nickel manganese oxide material is a spinel crystal (see Figure 7 for details); the electrochemical performance of the lithium nickel manganese oxide material adopts the lithium nickel manganese oxide material as the positive electrode active material to make the positive electrode to manufacture lithium-ion batteries The graphite negative electrode used, the solution of 0.5-2.0M LiPF ₆ /EC:DEC:EMC=1:1:1 is the electrolyte, and the manufactured lithium-ion battery is measured. The open-circuit voltage of the battery is 4.75-5.0 volts, the average The discharge voltage was 4.5 volts, and the measured first discharge specific capacity was 141mAh/g when charged at 0.25C and discharged at a rate of 0.5C (charge cut-off voltage 5.0V, discharge cut-off voltage 4.0 volts) (see Figure 8 for details).

Example 2:

A preparation method of lithium nickel manganese oxide positive electrode material, the steps are:

The first step is the nickel chloride (0.021mol), nickel nitrate (0.021mol) that the equimolar ratio mixing of nickel molar total amount is 0.042mol, the manganese chloride (0.12mol equimolar ratio mixing with manganese molar total amount) 0.05mol), manganese nitrate (0.05mol), lithium hydroxide of 1.125mol are mixed and ground evenly, obtain nickel, manganese, lithium mixture;

In the second step, the ammonium persulfate of 0.168mol (1.05 times the total molar amount of nickel salt and manganese salt in the first step) is mixed and ground with the mixture described in the first step to obtain a reaction mixture;

The third step is to transfer the reaction mixture described in the second step into a polytetrafluoroethylene reactor, add 2 mL of deionized water, cover and seal with a stainless steel reactor jacket, control the reaction temperature at 80 ° C, and keep it warm for 32 hours. The obtained reaction thing;

The fourth step is to take out the reactant obtained in the third step, wash with deionized water until no sulfate is detected, and filter with suction to obtain a brown or black solid;

The fifth step is to transfer the above-mentioned brown or black solid into a crucible, bake it for 4 hours in an atmosphere of 750° C., and cool it down to room temperature naturally to obtain a lithium nickel manganese oxide cathode material.

The morphology of lithium nickel manganese oxide material was observed by SEM, and its particle size range was counted. Its shape is an approximate regular octahedral shape, the particle size range is 1.0-3.0 μm, and the average particle size is about 2.0 μm (details See accompanying drawing 1); Measured Ni:Mn mol ratio of lithium nickel manganese oxide material with EDS, the Ni of test: Mn mol ratio average value is: 1:2.998 (seeing for details: table 1); Determined product's mol ratio with XRD The crystal structure shows that lithium nickel manganese oxide material is a spinel crystal (see accompanying drawing 7 for details); the electrochemical performance of lithium nickel manganese oxide material adopts lithium nickel manganese oxide material as positive electrode active material to make positive electrode, to manufacture lithium ion The graphite negative electrode used in the battery, the solution of 0.5-2.0M LiPF ₆ /EC:DEC:EMC=1:1:1 is the electrolyte, and the manufactured lithium-ion battery is measured, and the open-circuit voltage of the battery is 4.75-5.0 volts. The average discharge voltage is 4.5 volts, and the measured first discharge specific capacity is 150mAh/g when charged at 0.25C and discharged at a rate of 0.5C (charge cutoff voltage 5.0V, discharge cutoff voltage 4.0V) (see Figure 8 for details).

Embodiment 3:

A preparation method of lithium nickel manganese oxide positive electrode material, the steps are:

In the first step, 0.06mol of nickel sulfate, mixed with 0.18mol of manganese sulfate and 2.05mol of lithium hydroxide are uniformly ground to obtain a mixture of nickel, manganese and lithium;

In the second step, the ammonium persulfate of 0.264mol (1.1 times of the total molar amount of nickel salt and manganese salt in the first step) is mixed and ground with the mixture described in the first step to obtain a reaction mixture;

The third step is to transfer the reaction mixture described in the second step into a polytetrafluoroethylene reactor, add 5mL of pure water, cover and seal the stainless steel reactor jacket, control the reaction temperature at 100°C, and keep it warm for 28 hours. The obtained reactant ;

The fourth step is to take out the reactant obtained in the third step, wash it with pure water until no sulfate is detected, and filter it with suction to obtain a brown or black solid;

The fifth step is to transfer the above-mentioned brown or black solid into a crucible, bake it at 850°C for 6 hours, and cool it down to room temperature naturally to obtain the lithium nickel manganese oxide cathode material.

The morphology of lithium nickel manganese oxide material was observed by SEM, and its particle size range was counted. Its morphology is an approximate regular octahedral shape, the particle size range is 1.0-4.0 μm, and the average particle size is about 2.0 μm (details See accompanying drawing 2); Measured the Ni:Mn mol ratio of lithium nickel manganese oxide material with EDS, the Ni of test: Mn mol ratio average value is: 1:3.000 (see in detail: table 1); Determined product's mol ratio with XRD The crystal structure shows that lithium nickel manganese oxide material is a spinel crystal (see accompanying drawing 7 for details); the electrochemical performance of lithium nickel manganese oxide material adopts lithium nickel manganese oxide material as positive electrode active material to make positive electrode, to manufacture lithium ion The graphite negative electrode used in the battery, the solution of 0.5-2.0M LiPF ₆ /EC:DEC:EMC=1:1:1 is the electrolyte, and the manufactured lithium-ion battery is measured, and the open-circuit voltage of the battery is 4.75-5.0 volts, The average discharge voltage was 4.55 volts, and the first discharge specific capacity was measured to be 138mAh/g when charged at 0.25C and discharged at a rate of 0.5C (charge cut-off voltage 5.0V, discharge cut-off voltage 4.0 volts) (see Figure 8 for details).

Embodiment 4:

A preparation method of lithium nickel manganese oxide positive electrode material, the steps are:

In the first step, 0.08mol of nickel sulfate, mixed with 0.24 of manganese sulfate and 2.8mol of lithium hydroxide are uniformly ground to obtain a mixture of nickel, manganese and lithium;

In the second step, the ammonium persulfate of 0.368mol (1.15 times of the total molar amount of nickel salt and manganese salt in the first step) is mixed and ground with the mixture described in the first step to obtain a reaction mixture;

The third step is to transfer the reaction mixture described in the second step into a polytetrafluoroethylene reactor, add 10mL of distilled water, cover and seal with a stainless steel reactor jacket, control the reaction temperature at 120°C, and keep it warm for 24 hours to obtain the reactant;

The fourth step is to take out the reactant obtained in the third step, wash with distilled water until no sulfate is detected, and filter with suction to obtain a brown or black solid;

The fifth step is to transfer the above-mentioned brown or black solid into a crucible, bake it at 950°C for 8 hours, and cool it down to room temperature naturally to obtain the lithium nickel manganese oxide cathode material.

The morphology of lithium nickel manganese oxide material was observed by SEM, and its particle size range was counted. Its morphology is an approximate regular octahedral shape, the particle size range is 1.0-4.0 μm, and the average particle size is about 2.0 μm (details See accompanying drawing 2); Measured the Ni:Mn mol ratio of lithium nickel manganese oxide material with EDS, the Ni of test: Mn mol ratio average value is: 1:2.999 (seeing in detail: table 1); Determined product's mol ratio with XRD The crystal structure shows that lithium nickel manganese oxide material is a spinel crystal (see accompanying drawing 7 for details); the electrochemical performance of lithium nickel manganese oxide material adopts lithium nickel manganese oxide material as positive electrode active material to make positive electrode, to manufacture lithium ion The graphite negative electrode used in the battery, the solution of 0.5-2.0M LiPF ₆ /EC:DEC:EMC=1:1:1 is the electrolyte, and the manufactured lithium-ion battery is measured, and the open-circuit voltage of the battery is 4.75-5.0 volts, The average discharge voltage is 4.5 volts, and the measured first discharge specific capacity is 145mAh/g when it is charged at 0.25C and discharged at a rate of 0.5C (charging cut-off voltage 5.0V, discharge cut-off voltage 4.0 volts) (see Figure 8 for details).

Embodiment 5:

A preparation method of lithium nickel manganese oxide positive electrode material, the steps are:

In the first step, 0.12mol of nickel sulfate, mixed with 0.36mol of manganese sulfate and 4.55mol of lithium hydroxide are uniformly ground to obtain a mixture of nickel, manganese and lithium;

In the second step, the ammonium persulfate of 0.504mol (1.05 times the total molar amount of nickel salt and manganese salt in the first step) is mixed and ground with the mixture described in the first step to obtain a reaction mixture;

The third step is to transfer the reaction mixture described in the second step into a polytetrafluoroethylene reactor, add 15mL of pure water, cover and seal with a stainless steel reactor jacket, control the reaction temperature at 140°C, and keep it warm for 24 hours. The obtained reactant ;

The fourth step is to take out the reactant obtained in the third step, wash it with pure water until no sulfate is detected, and filter it with suction to obtain a brown or black solid;

The fifth step is to transfer the above-mentioned brown or black solid into a crucible, bake it at 850° C. for 12 hours, and cool it down to room temperature naturally to obtain lithium nickel manganese oxide cathode material.

The morphology of lithium nickel manganese oxide material was observed by SEM, and its particle size range was counted. Its shape is an approximate regular octahedral shape, the particle size range is 1.0-5.0 μm, and the average particle size is about 2.5 μm (details See accompanying drawing 3); Measured the Ni:Mn mol ratio of lithium nickel manganese oxide material with EDS, the Ni of test: Mn mol ratio average value is: 1:3.000 (see for details: table 1); Determined product's mol ratio with XRD The crystal structure shows that lithium nickel manganese oxide material is a spinel crystal (see accompanying drawing 7 for details); the electrochemical performance of lithium nickel manganese oxide material adopts lithium nickel manganese oxide material as positive electrode active material to make positive electrode, to manufacture lithium ion The graphite negative electrode used in the battery, the solution of 0.5-2.0M LiPF ₆ /EC:DEC:EMC=1:1:1 is the electrolyte, and the manufactured lithium-ion battery is measured, and the open-circuit voltage of the battery is 4.75-5.0 volts, The average discharge voltage is 4.5 volts, and the measured first discharge specific capacity is 149mAh/g when charged at 0.25C and discharged at a rate of 0.5C (charge cut-off voltage 5.0V, discharge cut-off voltage 4.0 volts) (see Figure 8 for details).

Embodiment 6:

A preparation method of lithium nickel manganese oxide positive electrode material, the steps are:

In the first step, 0.17mol of nickel sulfate, mixed with 0.50mol of manganese sulfate and 6.05mol of lithium hydroxide are uniformly ground to obtain a mixture of nickel, manganese and lithium;

In the second step, the ammonium persulfate of 0.723mol (equivalent to about 1.08 times of the total molar amount of nickel salt and manganese salt in the first step) is mixed and ground with the mixture described in the first step to obtain a reaction mixture;

The third step is to transfer the reaction mixture described in the second step into a polytetrafluoroethylene reactor, add 25mL of deionized water, cover and seal with a stainless steel reactor jacket, control the reaction temperature at 160°C, and keep it warm for 20 hours to obtain the reaction thing;

The fourth step is to take out the reactant obtained in the third step, wash with deionized water until no sulfate is detected, and filter with suction to obtain a brown or black solid;

The fifth step is to transfer the above-mentioned brown or black solid into a crucible, bake it for 4 hours in an atmosphere of 950° C., and cool it down to room temperature naturally to obtain a lithium nickel manganese oxide cathode material.

The morphology of lithium nickel manganese oxide material was observed by SEM, and its particle size range was counted. Its shape is an approximate regular octahedral shape, the particle size range is 0.5-3.5 μm, and the average particle size is about 1.5 μm (details See accompanying drawing 3); Measured the Ni:Mn mol ratio of lithium nickel manganese oxide material with EDS, the Ni of test: Mn mol ratio average value is: 1:3.000 (see for details: table 1); Determined product's mol ratio with XRD The crystal structure shows that lithium nickel manganese oxide material is a spinel crystal (see accompanying drawing 7 for details); the electrochemical performance of lithium nickel manganese oxide material adopts lithium nickel manganese oxide material as positive electrode active material to make positive electrode, to manufacture lithium ion The graphite negative electrode used in the battery, the solution of 0.5-2.0M LiPF ₆ /EC:DEC:EMC=1:1:1 is the electrolyte, and the manufactured lithium-ion battery is measured, and the open-circuit voltage of the battery is 4.75-5.0 volts, The average discharge voltage is 4.5 volts, and the measured first discharge specific capacity is 156mAh/g when it is charged at 0.25C and discharged at a rate of 0.5C (charge cutoff voltage 5.0V, discharge cutoff voltage 4.0V) (see Figure 8 for details).

Embodiment 7:

A preparation method of lithium nickel manganese oxide positive electrode material, the steps are:

In the first step, 0.20mol of nickel sulfate, mixed with 0.60mol of manganese sulfate and 8.20mol of lithium hydroxide are uniformly ground to obtain a mixture of nickel, manganese and lithium;

In the second step, the ammonium persulfate of 0.90mol (1.125 times of the total molar amount of nickel salt and manganese salt in the first step) is mixed and ground with the mixture described in the first step to obtain a reaction mixture;

The third step is to transfer the reaction mixture described in the second step into a polytetrafluoroethylene reactor, add 30mL of pure water, cover and seal with a stainless steel reactor jacket, control the reaction temperature at 180°C, and keep it warm for 16 hours. The obtained reactant ;

The fourth step is to take out the reactant obtained in the third step, wash it with pure water until no sulfate is detected, and filter it with suction to obtain a brown or black solid;

The fifth step is to transfer the above-mentioned brown or black solid into a crucible, bake it for 6 hours in an atmosphere of 950° C., and cool it down to room temperature naturally to obtain a lithium nickel manganese oxide cathode material.

The morphology of lithium nickel manganese oxide material was observed by SEM, and its particle size range was counted. Its shape is an approximate regular octahedral shape, the particle size range is 0.5-4.0 μm, and the average particle size is about 2.0 μm (details See accompanying drawing 4); Measured Ni:Mn mol ratio of lithium nickel manganese oxide material with EDS, the Ni of test: Mn mol ratio average value is: 1:3.000 (see for details: table 1); Determined product's mol ratio with XRD The crystal structure shows that lithium nickel manganese oxide material is a spinel crystal (see accompanying drawing 7 for details); the electrochemical performance of lithium nickel manganese oxide material adopts lithium nickel manganese oxide material as positive electrode active material to make positive electrode, to manufacture lithium ion The graphite negative electrode used in the battery, the solution of 0.5-2.0M LiPF ₆ /EC:DEC:EMC=1:1:1 is the electrolyte, and the manufactured lithium-ion battery is measured, and the open-circuit voltage of the battery is 4.75-5.0 volts, The average discharge voltage is 4.575 volts, and the measured first discharge specific capacity of its 0.25C charge and 0.5C discharge rate (charge cut-off voltage 5.0V, discharge end voltage 4.0 volts) is 159mAh/g (see Figure 9 for details), the highest The discharge specific capacity is 234mAh/g, the charge-discharge efficiency of 300 charge-discharge cycles exceeds 93% (see Figure 10 and Figure 11 for details), and the capacity retention rate of 300 charge-discharge cycles exceeds 85% (the minimum retention rate is 85.77% , that is, the attenuation is less than 15%, see Figure 12 for details).

Embodiment 8:

In the first step, 0.222mol of nickel sulfate, mixed with 0.66mol of manganese sulfate and 8.82mol of lithium hydroxide are uniformly ground to obtain a mixture of nickel, manganese and lithium;

In the second step, the ammonium persulfate of 1.014mol (1.15 times of the total molar amount of nickel salt and manganese salt in the first step) is mixed and ground with the mixture described in the first step to obtain a reaction mixture;

The third step is to transfer the reaction mixture described in the second step into a polytetrafluoroethylene reactor, add 35mL of distilled water, cover and seal with a stainless steel reactor jacket, control the reaction temperature at 190°C, and keep it warm for 12 hours to obtain the reactant;

The fourth step is to take out the reactant obtained in the third step, wash with distilled water until no sulfate is detected, and filter with suction to obtain a brown or black solid;

The fifth step is to transfer the above-mentioned brown or black solid into a crucible, bake it for 6 hours in an atmosphere at 900° C., and cool it down to room temperature naturally to obtain a lithium nickel manganese oxide cathode material.

The morphology of lithium nickel manganese oxide material was observed by SEM, and its particle size range was counted. Its shape is an approximate regular octahedral shape, the particle size range is about 0.25-2.0 μm, and the average particle size is about 1.0 μm ( See accompanying drawing 4) for details; Measure the Ni:Mn mol ratio of lithium nickel manganese oxide material with EDS, the Ni:Mn mol ratio average value of test is: 1:2.998 (see for details: table 1); Determine product with XRD The results show that the lithium nickel manganese oxide material is a spinel crystal (see accompanying drawing 7 for details); the electrochemical performance of the lithium nickel manganese oxide material adopts the lithium nickel manganese oxide material as the positive electrode active material to make the positive electrode to manufacture lithium The graphite negative electrode used in the ion battery, the solution of 0.5-2.0M LiPF ₆ /EC:DEC:EMC=1:1:1 is the electrolyte solution, and the manufactured lithium-ion battery is measured, and the open circuit voltage of the battery is 4.75-5.0 volts , the average discharge voltage is 4.5 volts, and the first discharge specific capacity of its 0.25C charge and 0.5C discharge rate (charge cut-off voltage 5.0V, discharge end voltage 4.0 volts) is measured to be 151mAh/g (see Figure 9 for details).

Embodiment 9:

A preparation method of lithium nickel manganese oxide positive electrode material, the steps are:

In the first step, 0.24mol of nickel sulfate, mixed with 0.72mol of manganese sulfate and 10.4mol of lithium hydroxide are uniformly ground to obtain a mixture of nickel, manganese and lithium;

In the second step, the ammonium persulfate of 1.056mol (1.10 times of the total molar amount of nickel salt and manganese salt in the first step) is mixed and ground with the mixture described in the first step to obtain a reaction mixture;

The third step is to transfer the reaction mixture described in the second step into a polytetrafluoroethylene reactor, add 40mL of pure water, cover and seal with a stainless steel reactor jacket, control the reaction temperature at 190°C, and keep it warm for 10 hours. The obtained reactant ;

The fourth step is to take out the reactant obtained in the third step, wash it with pure water until no sulfate is detected, and filter it with suction to obtain a brown or black solid;

The fifth step is to transfer the above-mentioned brown or black solid into a crucible, bake it for 10 hours in an atmosphere at 950°C, and cool it down to room temperature naturally to obtain a lithium nickel manganese oxide cathode material.

The morphology of lithium nickel manganese oxide material was observed by SEM, and its particle size range was counted. Its shape is an approximate regular octahedral shape, the particle size range is about 0.5-5.0 μm, and the average particle size is about 1.0 μm ( See accompanying drawing 5) for details; Measure the Ni:Mn molar ratio of lithium nickel manganese oxide material with EDS, the Ni:Mn molar ratio average value of test is: 1:3.002 (see for details: table 1); Determined product with XRD The results show that the lithium nickel manganese oxide material is a spinel crystal (see accompanying drawing 7 for details); the electrochemical performance of the lithium nickel manganese oxide material adopts the lithium nickel manganese oxide material as the positive electrode active material to make the positive electrode to manufacture lithium The graphite negative electrode used in the ion battery, the solution of 0.5-2.0M LiPF ₆ /EC:DEC:EMC=1:1:1 is the electrolyte solution, and the manufactured lithium-ion battery is measured, and the open circuit voltage of the battery is 4.75-5.0 volts , the average discharge voltage is 4.5 volts, and the measured first discharge specific capacity of its 0.25C charge and 0.5C discharge rate (charge cut-off voltage 5.0V, discharge end voltage 4.0 volts) is 148mAh/g (see Figure 9 for details).

Embodiment 10:

A preparation method of lithium nickel manganese oxide positive electrode material, the steps are:

In the first step, 0.25 mol of nickel sulfate, 0.75 mol of manganese sulfate and 11.0 mol of lithium hydroxide are mixed and ground evenly to obtain a mixture of nickel, manganese and lithium;

In the second step, the ammonium persulfate of 1.05mol (equivalent to about 1.05 times of the total molar amount of nickel salt and manganese salt in the first step) is mixed and ground with the mixture described in the first step to obtain a reaction mixture;

The third step is to transfer the reaction mixture described in the second step into a polytetrafluoroethylene reactor, add 45mL of pure water, cover and seal with a stainless steel reactor jacket, control the reaction temperature at 190°C, and keep it warm for 8 hours. The obtained reactant ;

The fourth step is to take out the reactant obtained in the third step, wash it with pure water until no sulfate is detected, and filter it with suction to obtain a brown or black solid;

The fifth step is to transfer the above-mentioned brown or black solid into a crucible, bake it at 850°C for 8 hours, and cool it down to room temperature naturally to obtain the lithium nickel manganese oxide cathode material.

The morphology of lithium nickel manganese oxide material was observed by SEM, and its particle size range was counted. Its shape is an approximate regular octahedral shape, the particle size range is about 1.0-5.0 μm, and the average particle size is about 1.5 μm ( See accompanying drawing 5) for details; Measure the Ni:Mn molar ratio of nickel manganese oxide lithium material with EDS, the Ni:Mn molar ratio average value of test is: 1:3.000 (see for details: table 1); Determined product with XRD The results show that the lithium nickel manganese oxide material is a spinel crystal (see accompanying drawing 7 for details); the electrochemical performance of the lithium nickel manganese oxide material adopts the lithium nickel manganese oxide material as the positive electrode active material to make the positive electrode to manufacture lithium The graphite negative electrode used in the ion battery, the solution of 0.5-2.0M LiPF ₆ /EC:DEC:EMC=1:1:1 is the electrolyte solution, and the manufactured lithium-ion battery is measured, and the open circuit voltage of the battery is 4.75-5.0 volts , the average discharge voltage is 4.5 volts, and the measured first discharge specific capacity of 0.25C charge and 0.5C discharge rate (charge cut-off voltage 5.0V, discharge stop voltage 4.0 volts) is 143mAh/g (see Figure 9 for details).

Embodiment 11:

A preparation method of lithium nickel manganese oxide positive electrode material, the steps are:

In the first step, the nickel nitrate (0.08mol), nickel sulfate (0.08mol), nickel chloride (0.08mol) mixed with an equimolar ratio of 0.24mol in a total nickel mole, and an equimolar mixture with a total molar amount of manganese of 0.72mol The mixture of mixed manganese nitrate (0.24mol), manganese sulfate (0.24mol), manganese chloride (0.24mol), and 11.2mol of lithium acetate are mixed and ground evenly to obtain a mixture of nickel, manganese and lithium;

In the second step, the ammonium persulfate of 1.155mol (1.05 times of the total molar amount of nickel salt and manganese salt in the first step) is mixed and ground with the mixture described in the first step to obtain a reaction mixture;

The third step is to transfer the reaction mixture described in the second step into a polytetrafluoroethylene reactor, add 45mL of distilled water, add a cover, add a stainless steel reactor jacket to seal, control the reaction temperature at 180 ° C, and keep it warm for 12 hours to obtain the reactant;

The fourth step is to take out the reactant obtained in the third step, wash with distilled water until no sulfate is detected, and filter with suction to obtain a brown or black solid;

The fifth step is to transfer the above-mentioned brown or black solid into a crucible, bake it at 950° C. for 12 hours, and cool it down to room temperature naturally to obtain the lithium nickel manganese oxide cathode material.

The morphology of lithium nickel manganese oxide material was observed by SEM, and its particle size range was counted. Its shape is an approximate regular octahedral shape, the particle size range is about 1.0-3.0 μm, and the average particle size is about 1.5 μm ( See accompanying drawing 6) for details; Measure the Ni:Mn molar ratio of lithium nickel manganese oxide material with EDS, the Ni:Mn molar ratio average value of test is: 1:3.000 (see for details: table 1); Determined product with XRD The results show that the lithium nickel manganese oxide material is a spinel crystal (see accompanying drawing 7 for details); the electrochemical performance of the lithium nickel manganese oxide material adopts the lithium nickel manganese oxide material as the positive electrode active material to make the positive electrode to manufacture lithium The graphite negative electrode used in the ion battery, the solution of 0.5-2.0M LiPF ₆ /EC:DEC:EMC=1:1:1 is the electrolyte solution, and the manufactured lithium-ion battery is measured, and the open circuit voltage of the battery is 4.75-5.0 volts , the average discharge voltage is 4.5 volts, and the first discharge specific capacity of its 0.25C charge and 0.5C discharge rate (charge cut-off voltage 5.0V, discharge end voltage 4.0 volts) discharge is measured to be 140mAh/g (see Figure 9 for details).

Embodiment 12:

A preparation method of lithium nickel manganese oxide positive electrode material, the steps are:

In the first step, the nickel chloride of 0.334mol, manganese acetate (0.25mol), manganese nitrate (0.25mol), manganese chloride (0.25mol), manganese sulfate ( 0.25mol) of the mixture, 6.25mol of lithium oxide (Li ₂ O wherein the amount of Li ⁺ is 12.5mol) mixed and ground evenly to obtain a mixture of nickel, manganese and lithium;

Second step with the sodium persulfate (1.2 times of nickel-manganese molar total amount in the first step) of 1.601mol (equivalent to 1.2 times of nickel salt, manganese salt molar total amount in the first step) and the first step Said mixture is mixed and ground to obtain a reaction mixture;

The third step is to transfer the reaction mixture described in the second step into a polytetrafluoroethylene reactor, add 50mL of deionized water, cover it, and seal it with a stainless steel reactor jacket, control the reaction temperature at 200°C, and keep it warm for 4 hours to obtain the reaction thing;

The fourth step is to take out the reaction deionized water obtained in the third step, wash with deionized water until no sulfate is detected, and filter with suction to obtain a brown or black solid;

The fifth step is to transfer the above-mentioned brown or black solid into a crucible, bake it for 12 hours in an atmosphere of 950° C., and cool it down to room temperature naturally to obtain a lithium nickel manganese oxide cathode material.

The morphology of lithium nickel manganese oxide material was observed by SEM, and its particle size range was counted. Its shape is an approximate regular octahedral shape, the particle size range is about 1.0-5.0 μm, and the average particle size is about 1.5 μm ( See accompanying drawing 6) for details; Measure the Ni:Mn molar ratio of lithium nickel manganese oxide material with EDS, the Ni:Mn molar ratio average value of test is: 1:3.001 (see for details: table 1); Determined product with XRD The results show that the lithium nickel manganese oxide material is a spinel crystal (see accompanying drawing 7 for details); the electrochemical performance of the lithium nickel manganese oxide material adopts the lithium nickel manganese oxide material as the positive electrode active material to make the positive electrode to manufacture lithium The graphite negative electrode used in the ion battery, the solution of 0.5-2.0M LiPF ₆ /EC:DEC:EMC=1:1:1 is the electrolyte solution, and the manufactured lithium-ion battery is measured, and the open circuit voltage of the battery is 4.75-5.0 volts , the average discharge voltage is 4.5 volts, and the first discharge specific capacity of its 0.25C charge and 0.5C discharge rate (charge cut-off voltage 5.0V, discharge end voltage 4.0 volts) is measured to be 145mAh/g (see Figure 9 for details).

Matters not covered in the present invention are known technologies.

Claims (6)

1. a preparation method of lithium nickel manganese oxide positive electrode material, the steps are: A, the divalent nickel salt of 0.02～0.25mol mole, and the divalent manganese salt of 0.06～1.0mol, the lithium compound that the molar number of Li ⁺ is 0.65～12.5mol are mixed and ground evenly, obtain nickel, manganese, lithium mixture; B, the persulfate that molar weight is divalent nickel salt and divalent manganese salt total molar weight 1.05～1.20 times and the mixture described in A step are mixed and ground, obtain reaction mixture; C. Transfer the reaction mixture described in step B into a polytetrafluoroethylene reactor, add 1 to 50 mL of water, cover, seal with a stainless steel reactor jacket, control the reaction temperature at 60 to 200 ° C, and keep it warm for 4 to 36 hours to obtain reactant; D, take out the reactant obtained in step C, wash with water until no sulfate is detected, and filter with suction to obtain a brown or black solid; E. Transfer the brown or black solid obtained in step D into a crucible, and bake it in an atmosphere of 650-950° C. for 4-12 hours, and cool naturally to room temperature to obtain a lithium nickel manganese oxide cathode material. 2. The preparation method of a lithium nickel manganese oxide cathode material according to claim 1, characterized in that: the divalent nickel salt comprises: one of nickel acetate, nickel nitrate, nickel chloride or nickel sulfate Or any mixture of two to four. 3. The preparation method of a lithium nickel manganese oxide positive electrode material according to claim 1, characterized in that: the divalent manganese salt comprises: one of manganese acetate, manganese nitrate, manganese chloride, and manganese sulfate Or any mixture of two to four. 4. The preparation method of a lithium nickel manganese oxide cathode material according to claim 1, characterized in that: the lithium compound comprises: one or a mixture of lithium oxide and lithium hydroxide. 5. The preparation method of a lithium nickel manganese oxide positive electrode material according to claim 1, wherein the persulfate is one of ammonium persulfate, potassium persulfate and sodium persulfate. 6. The preparation method of a lithium nickel manganese oxide cathode material according to claim 1, wherein the water is one of distilled water, purified water and deionized water.