CN102881880B - Method for preparing monovalent ion-doped lithium-rich solid solution cathode material by partial dissolution method - Google Patents

Abstract

The invention relates to a method for preparing a lithium-rich solid solution positive electrode material doped with monovalent ions by a partial dissolution method, characterized in that: the molar ratio of lithium ions, nickel ions, manganese ions, cobalt ions, and M ions is (1.1+0.90 x ): (1-x) y: (x+zx z): (1-x) k: (1-x) q were weighed lithium, nickel, manganese, cobalt compound and M compound. Mix the weighed nickel, manganese, cobalt compound and M compound, add wet milling medium and organic weak acid, wet mill and mix, then add lithium compound, wet mill and mix to obtain precursor 1; dry precursor 1 and place In air, oxygen-enriched gas or pure oxygen atmosphere, a lithium-rich solid solution cathode material is prepared by a two-stage sintering method or a two-stage sintering method. The electrode material prepared by the invention has uniform composition and excellent discharge performance, especially good discharge cycle performance under high current conditions.

Description

Method for preparing lithium-rich solid solution cathode material doped with monovalent ions by partial dissolution method

technical field

The invention belongs to the technical field of battery electrode material preparation, and in particular relates to a method for preparing a doped lithium-rich solid solution positive electrode material that can be used for lithium batteries, lithium ion batteries, polymer batteries and supercapacitors.

technical background

Spinel-type LiMn ₂ O ₄ has the characteristics of high working voltage, low price, and environmental friendliness, but the reversible capacity of the positive electrode material is low, and the discharge point capacity is only 90-100mAh/g when charging and discharging at 1C rate; The discharge capacity of the positive electrode material will decay rapidly with the progress of charge and discharge cycles.

The lithium-rich solid solution cathode material Li ₂ MnO ₃ ·Li[Ni _1/3 Co _1/3 Mn _1/3 ]O ₂ exhibits the advantages of high specific capacity, good thermal stability, and good cycle performance, which has attracted domestic and foreign experts of high interest to scholars. The methods currently used to prepare lithium-rich solid solution cathode materials include co-precipitation methods, sol methods, and solid-phase sintering methods. In these several preparation methods, in order to further improve the electrochemical performance of the prepared samples, such as improving the current efficiency of the first cycle, improving the discharge performance of different rate currents, etc., there are also some research reports on doping preparation methods.

In the co-precipitation preparation method, it is divided into hydroxide co-precipitation method and carbonate co-precipitation method according to the different precipitates generated.

In the hydroxide co-precipitation method, according to the different precipitants used, it can be divided into lithium hydroxide co-precipitation method, sodium hydroxide (potassium) and ammonia water co-precipitation method, which are discussed separately below:

The lithium hydroxide co-precipitation method is to use LiOH as a precipitating agent, and add the LiOH solution to the solution of manganese salt, nickel salt and cobalt salt to prepare a composite of hydroxide precipitation of manganese, nickel and cobalt. Wash and dry the hydroxide precipitated composite, mix with excess LiOH, and sinter in one or two stages or twice to obtain lithium-rich lithium manganese oxide material [Guo X. et al. J. Power Sources, 2008, 184 : 414–419.; Denis Y. et al, J. Electrochem. Soc., 2010, 157: A1177-A1182.; Li J., et al, J. Power Sources, 2011, 196: 4821–4825.].

In order to improve the rate discharge performance of samples prepared by lithium hydroxide co-precipitation method, Wu Xiaobiao et al. treated Li[Li _0.2 Mn _0.54 Ni _0.13 Co _0.13 ]O ₂ prepared by lithium hydroxide co-precipitation method with carbon coating; Shi et al. Li _1.048 Mn _0.381 Ni _0.286 Co _0.286 O ₂ was subjected to magnetron sputtering treatment to prepare carbon-coated cathode materials. The results show that the carbon-coated material has high-rate discharge performance (5C, 145 mAh/g) [Wu Xiaobiao et al., Xiamen University Journal (Natural Science Edition), 2008, 47: 224-227; Shi SJ et al, Electrochim. Acta, 2012, 63: 112–117].

In order to improve the rate discharge performance of samples prepared by lithium hydroxide _co -precipitation method, Croy et al _. enriched the _{prepared Li 2} MnO ₃ precursor or _{Li 1.2} Mn _0.54 Co _0.13 Ni _0.13 O ₂ Lithium solid solution materials treated with acids or acid salts to improve properties [Croy JR et al, Electrochem. Commun., 2011, 13: 1063–1066.; Denis Y. et al, J. Electrochem. Soc., 2010, 157 : A1177-A1182.]. The research shows that the materials treated with (NH ₄ ) ₂ SO ₄ have higher capacity and good rate discharge performance.

In order to further improve the rate discharge performance of samples prepared by lithium hydroxide co-precipitation method, Rodrigues et al. added urea during preparation, and used urea decomposition products to further promote the occurrence of co-precipitation. Rodrigues et al [Rodrigues I., Solid State Electrochem., 2012, 16: 1121–1132.] first prepared Co(NO ₃ ) ₂ 6H ₂ O, Ni(NO ₃ ) ₂ 6H ₂ O, Mn(NO ₃ ) ₂ ·6H ₂ O, NH ₂ CONH ₂ and LiOH·H ₂ O mixed solution, adding NH ₂ CONH ₂ solution, hydrothermal method, microwave hydrothermal synthesis method or 100℃ heating method to determine the optimal temperature of urea decomposition. Studies have shown that with the increase of the pH value of the reaction solution, the precipitate precipitates out of the solution. After drying in an air atmosphere, the dry hydroxide and an excess of 3% LiOH were synthesized as LiNi _x Mn _x Co _{(1 – 2x) O} precursors. After the precursor is granulated, it is sintered at 500°C and 900°C respectively in an air atmosphere, and finally quenched and cooled.

The co-precipitation method of sodium hydroxide (potassium) and ammonia water is to use the mixed solution of ammonia water and NaOH or KOH solution as a precipitant, and add ammonia water and NaOH solution or ammonia water and KOH solution to manganese salt, nickel salt and cobalt salt solution to obtain Precipitation of hydroxides of manganese, nickel and cobalt. After washing and drying the precipitated hydroxide, it is mixed with LiOH or Li ₂ CO ₃ in a slight excess of stoichiometry, and undergoes two-stage sintering to obtain a lithium-rich layered cathode material. [Zhong Shengwen et al., Power Technology, 2012, 36:59-62.; Cui Lifeng et al. Patent ZL200910264411.0]

In order to further improve the performance of samples prepared by the co-precipitation method of sodium (potassium) hydroxide and ammonia water, Arunkumar et al. chemically delithiated the prepared lithium-rich solid solution material with an acetonitrile solution of oxidant NO ₂ BF ₄ . [Arunkumar TA et al, Chem. Mater. 2007, 19, 3067-3073.; Wu Y. et al, J. Power Sources, 2008, 183: 749–754.]

In order to improve the performance of samples prepared by co-precipitation of sodium (potassium) hydroxide and ammonia water, Wu et al. prepared coated or doped lithium-rich solid solution materials. _The uncoated sample was first prepared by the co _- precipitation _{method ,} and _then ^{the lithium-} _rich solid solution material (1- z) Li[Li _1/3 Mn _2/3 ]O ₂ •(z) Li[Mn _{0.5 − y} Ni _{0.5 − y} Co _2y ]O ₂ [Wu Y., Manthiram A., Solid State Ionics, 2009, 180 : 50–56.].

The carbonate co-precipitation method is to first prepare the carbonate precipitation of nickel, cobalt, and manganese, and then mix it with lithium carbonate or lithium hydroxide. After two-stage sintering method or one-stage sintering method or step-by-step preparation method, lithium-rich Cathode material. For example, in an argon atmosphere, Liun et al. added NH ₄ HCO ₃ , (NH ₄ ) ₂ CO ₃ or Na ₂ CO ₃ solution to a mixed solution of NiSO ₄ , CoSO ₄ and MnSO ₄ , filtered, washed and dried Ni _0.2 Co _0.1 Mn _0.533 (CO ₃ ) _x precursor was obtained. The precursor was sintered at 500°C and then mixed with Li ₂ CO ₃ , and sintered at 900°C in an air atmosphere to obtain spherical powder Li _1.167 Ni _0.2 Co _0.1 Mn _0.533 O ₂ . The discharge capacity can reach 340mAh/g in the voltage range of 2.0–4.8 V. [Liun X. et al., Materials International, 2012, 22:126–129.; Wang J. et al, Electrochim. Acta, 2012, 66: 61–66.; Patent ZL201110300604.4].

In order to further improve the Coulombic efficiency and discharge performance of the samples prepared by the carbonate co-precipitation method, a doping modification study was carried out. For example, Deng et al synthesized the carbonate precursor (Ni _0.1875 Co _0.125 Mn _0.6875 )CO ₃ from nickel sulfate, cobalt sulfate, manganese sulfate solution and sodium carbonate solution. Suspend the precursor in Al(NO ₃ ) ₃ 9H ₂ O aqueous solution, add NH ₄ F suspension dropwise, stir, filter, dry at 100°C, and sinter at 400°C to prepare 2wt% AlF ₃ packs Coated Li _1.1 Ni _0.15 Co _0.1 Mn _0.55 O _1.95 . The material has a reversible capacity of 304 mAh/g at 55 °C and a Coulombic efficiency of 84% in the first cycle. [Belharouak Deng H. et al, J. Electrochem. Soc., 2010, 157: A1035-A1039.]

In order to further improve the discharge performance of the samples prepared by the carbonate co-precipitation method, a step-by-step preparation study was carried out. Shin et al. reacted cobalt sulfate, manganese sulfate and ammonium bicarbonate solution to prepare the Co _0.5 Mn _0.5 CO ₃ precursor. The precursor was dried _and mechanically mixed with _Li2CO3 . In the air atmosphere, the precursors of 0.5Li ₂ MnO ₃ ·0.5LiCoO ₂ were prepared by sintering at 550℃ and 850℃ respectively. Mix the precursor with ammonium dihydrogen phosphate, glycolic acid, nickel nitrate, and lithium nitrate, dry in the air atmosphere, and then sinter at 550°C to obtain 0.5Li ₂ MnO ₃ ·0.5LiNi _0.44 Co _0.25 Mn _0.31 O ₂ [Shin, C. et al, J. Electrochem. Soc., 2012, 159: A121-A127.].

When preparing by the co-precipitation method, regardless of the co-precipitation of the hydroxide or the co-precipitation of the carbonate, the preparation must go through a process of precipitation, washing, precipitation and drying. The preparation process has many preparation steps, and a large amount of washing water needs to be used in the preparation process, which increases water pollution. When carbonate precipitation is prepared by co-precipitation method, the precipitation solubility product of nickel, manganese and cobalt ions is relatively large; when hydroxide precipitation is prepared by co-precipitation method, part of the precipitation dissolves, resulting in incomplete precipitation of nickel, manganese and cobalt ions (The hydroxide precipitate is easy to form a complex with ^OH- or ammonia to increase the solubility of the hydroxide), which causes the stoichiometric ratio of the final product to be difficult to accurately control, resulting in the electrochemical performance and large current of the sample. Instability of Discharge Performance (Edited by Wuhan University, Analytical Chemistry (2nd Edition), Higher Education Press, October 1982, Beijing: Page 14 to Page 17). Since the high-current discharge performance of currently prepared lithium-rich solid solution cathode materials is not ideal, the present invention attempts to further improve the high-current discharge performance by adding dopants during the preparation process.

Contents of the invention

The energy-consuming and water-consuming preparation steps such as filtration and washing to be experienced during preparation by coprecipitation method, in addition, when preparing by coprecipitation method, due to the hydroxide or carbonate of manganese ion, cobalt ion, nickel ion will Incomplete precipitation makes it difficult to control the stoichiometric ratio of the prepared product. The conventional solid-state sintering method has problems such as inhomogeneous mixing of reactants and poor consistency of electrochemical properties of reaction products when preparing samples by simple ball milling and sintering of reaction products. The present invention can avoid the above-mentioned disadvantages. In order to achieve the above object, the technical solution adopted in the present invention is that the preparation process consists of the following steps:

(1) According to the molar ratio of lithium ion, nickel ion, manganese ion, cobalt ion, M ion is (1.1+0.90 x): (1-x)·y : (x+z-x·z) : (1-x)·k : (1-x) ·q Weigh lithium compound, nickel compound, manganese compound, cobalt compound and M compound respectively. Measure the organic weak acid according to the following molar ratio relationship: (x+z-x z)≤mol number of organic weak acid≤x+(1-x)(z+y+k+q); x, y, z, q, k The value range satisfies the following relationship at the same time: 0.25≤x≤0.55, 0.05≤y≤0.50, 0.2127≤z≤0.55, 0.02≤q≤0.15, 0.05≤k≤0.30, 2·y+4·z+3·k+ q-2.9=0.

(2) Mix the weighed nickel compound, manganese compound, cobalt compound and M compound, add 1/10 to 10 times the volume of the total solid volume of wet milling medium, add organic weak acid, wet mill and mix for 3 hours ~ 15 hours, then add lithium compound, wet milling and mixing for 3 hours ~ 15 hours to obtain precursor 1. Precursor 1 is vacuum-dried or spray-dried to prepare dry precursor 2. Precursor 2 is placed in air, oxygen-enriched gas or pure oxygen atmosphere, and the composition is prepared by two-stage sintering method or two-stage sintering method into xLi ₂ MnO ₃ •(1-x)Li[Li _0.10 Ni _y Mn _z Lithium-rich solid solution cathode materials for Co _k M _q ]O ₂ .

The two-stage sintering method is carried out as follows: the precursor 2 is placed in air, oxygen-enriched gas or pure oxygen atmosphere, sintered at any temperature in the temperature range of 300°C to 550°C for 3 hours to 15 hours, and cooled to The precursor pre-fired material was prepared at room temperature. After crushing and sieving the matrix pre-sintered material, place it again in air, oxygen-enriched gas or pure oxygen atmosphere, and sinter at any temperature in the temperature range of 800°C to 1050°C for 3 hours to 24 hours to prepare lithium-rich solid solution positive electrode materials .

The two-stage sintering method is carried out as follows: the precursor 2 is placed in air, oxygen-enriched gas or pure oxygen atmosphere, sintered at any temperature in the temperature range of 300 ° C to 550 ° C for 3 hours to 15 hours, and then placed in another A sintering furnace is sintered at any temperature in the temperature range of 800° C. to 1050° C. for 3 hours to 24 hours in air, oxygen-enriched gas or pure oxygen atmosphere to prepare lithium-rich solid solution cathode materials.

Described weak acid is oxalic acid, glycine, monochloroacetic acid, formic acid or acetic acid.

The nickel compound is nickel carbonate or basic nickel carbonate, or a mixture of nickel carbonate and basic nickel carbonate; the manganese compound is manganese carbonate or basic manganese carbonate, or manganese carbonate and basic Mixture of manganese carbonate in any proportion. The cobalt compound is cobalt carbonate, cobalt oxalate or basic cobalt carbonate, or a mixture of cobalt carbonate and basic cobalt carbonate in any ratio. The M compound is sodium oxide, silver oxide, sodium hydroxide or potassium hydroxide, or carbonate, chloride, nitrate or fluoride of sodium, potassium or silver.

The vacuum drying is to prepare the precursor 2 by drying the precursor 1 at any temperature in the temperature range of 80° C. to 280° C. under a vacuum with a pressure of 10 Pa to 10132 Pa. The spray drying is at any temperature in the temperature range of 120° C. to 280° C., and the dry precursor 2 is prepared by using a spray dryer.

The wet grinding medium is deionized water, distilled water, ethanol, acetone, methanol or formaldehyde; the oxygen-enriched gas is a gas with an oxygen volume content greater than 21% and less than 100%.

The wet grinding equipment includes ordinary ball mill, super energy ball mill or wet mill; the lithium compound is lithium carbonate, lithium hydroxide or basic lithium carbonate, or a mixture thereof in any proportion.

Compared with the preparation methods of other inventions, due to the lithium-site, manganese-site, nickel-site and cobalt-site ions in the lithium-rich solid solution structure are under different preparation conditions, or even only when the preparation process is different, ion mixing often occurs, which seriously affects Electrochemical performance of prepared samples. In order to prevent the lithium position in the lithium-rich solid solution structure from being replaced by other valence ions, causing the intercalation and extraction channels of lithium ions to be blocked during charging and discharging, the present invention dopes monovalent cations into the lithium-rich solid solution structure. When the lithium site in this structure is "missing", the doped monovalent cation may preferentially replenish the lithium site entering the lithium-rich solid solution structure, preventing the occurrence of other valence ion mixing, stabilizing the structure of the lithium-rich solid solution, and improving the preparation process. The cycle performance of the sample under the condition of high current charge and discharge.

The invention has low cost of raw materials, wide sources of raw materials, simple preparation process, less time-consuming, uniform composition of prepared electrode materials, excellent discharge performance, especially good discharge cycle performance under high current conditions, laying a solid foundation for industrialization. good foundation.

Description of drawings

Fig. 1 is the XRD diffraction pattern of the sample prepared in Example 1 of the present invention.

Fig. 2 is the discharge curve of the first cycle of the sample prepared in Example 1 of the present invention under the conditions of Example 1.

Detailed ways

The present invention will be further described below in conjunction with examples. Examples are only further supplements and descriptions of the present invention, rather than limitations to the invention.

Example 1

Weigh lithium carbonate, nickel carbonate, manganese carbonate, cobalt carbonate, _Na2O and formic acid.

Mix the weighed nickel carbonate, manganese carbonate, cobalt carbonate and _Na2O , add 10 times the volume of the total solid volume of deionized water, add formic acid, and wet-mill with an ordinary ball mill for 15 hours, then add lithium carbonate, wet-mill Precursor 1 was prepared by mixing for 15 hours; Precursor 1 was dried at 80° C. under a vacuum condition of 10 Pa to prepare Precursor 2 . Precursor 2 was placed in air atmosphere, sintered at 550°C for 15 hours, and cooled to room to obtain matrix pre-sintered material; the matrix pre-sintered material was crushed and passed through a 200-mesh sieve, and then placed in air atmosphere, at 1050°C After sintering for 24 hours, a lithium-rich solid solution cathode material with a composition of 0.25 Li ₂ MnO ₃ •0.75 Li[Li _0.10 Ni _0.05 Mn _0.55 Co _0.193 Na _0.02 ]O ₂ was prepared. The XRD diffraction patterns of the prepared samples are shown in Figure 1. When the prepared sample is charged and discharged at 58°C, in the voltage range from 4.6 to 2.5V, under the current of 1C, the discharge capacity of the first cycle is 190mAh/g, and the discharge curve of the sample in the first cycle under this charge and discharge condition is shown in the figure 2.

Compared with other inventive methods, the present invention has lower cost of raw materials, wide sources of raw materials, simple preparation process, less time-consuming, uniform composition of prepared electrode materials, and excellent discharge performance, especially in the cycle of discharge under high current conditions. Good performance, laying a good foundation for industrialization.

Example 2

According to the molar ratio of lithium ion, nickel ion, manganese ion, cobalt ion, potassium ion, oxalic acid is 1.595 : 0.225 : 0.745 : 0.0225:0.009:0.992 Weigh basic lithium carbonate, basic nickel carbonate, basic manganese carbonate, basic cobalt carbonate, KOH and oxalic acid respectively.

Mix the weighed basic nickel carbonate, basic manganese carbonate, basic cobalt carbonate and KOH, add ethanol that is 1/10 times the volume of the total solid volume, add oxalic acid, and use a super energy ball mill to mix for 3 hours, then add Lithium carbonate basic was mixed with a super energy ball mill for 3 hours to obtain precursor 1; Precursor 1 was prepared with a spray dryer at 120°C to dry precursor 2. Precursor 2 was placed in an oxygen-enriched air gas atmosphere with an oxygen volume content of 22%, sintered at 300°C for 3 hours, and then placed in another air atmosphere sintering furnace at 1050°C for 3 hours, and the prepared composition was 0.55 Li ₂ MnO ₃ •0.45 Li[Li _0.1 Ni _0.50 Mn _0.4325 Co _0.05 K _0.02 ]O ₂ lithium-rich solid solution cathode material. When the prepared sample is charged and discharged at 58°C, in the voltage range of 4.6 to 2.5V, and at a current of 1C, the discharge capacity of the first cycle is 220mAh/g.

Compared with other inventive methods, the present invention has lower cost of raw materials, wide sources of raw materials, simple preparation process, less time-consuming, uniform composition of prepared electrode materials, and excellent discharge performance, especially in the cycle of discharge under high current conditions. Good performance, laying a good foundation for industrialization.

Example 3

Weigh lithium hydroxide, nickel carbonate, manganese carbonate, basic cobalt carbonate, Ag ₂ O, formic acid.

Mix the weighed nickel carbonate, manganese carbonate, basic cobalt carbonate and Ag ₂ O, add acetone 10 times the volume of the total solid volume, add formic acid, wet grind and mix for 3 hours with a wet mill, and then add lithium hydroxide, Precursor 1 was obtained by wet grinding and mixing with a wet mill for 3 hours; Precursor 2 was prepared by drying at 280° C. in a vacuum at a pressure of 10132 Pa. Precursor 2 was placed in a pure oxygen atmosphere, sintered at 550 °C for 15 hours, and then placed in another sintering furnace with a pure oxygen atmosphere at 800 °C for 24 hours to prepare a composition of 0.35 Li ₂ MnO ₃ •0.65 Li Lithium-rich solid solution cathode materials of [Li _0.10 Ni _0.05 Mn _0.55 Co _0.15 Ag _0.15 ]O ₂ . When the prepared sample is charged and discharged at 58°C, in the voltage range of 4.6 to 2.5V, and at a current of 1C, the discharge capacity of the first cycle is 270mAh/g.

Compared with other inventive methods, the present invention has lower cost of raw materials, wide sources of raw materials, simple preparation process, less time-consuming, uniform composition of prepared electrode materials, and excellent discharge performance, especially in the cycle of discharge under high current conditions. Good performance, laying a good foundation for industrialization.

Example 4

According to lithium ion, nickel ion, manganese ion, cobalt ion, silver ion, oxalic acid molar ratio is 1.37: 0.35: 0.4575: 0.21: 0.070:0.46 respectively weigh lithium carbonate, basic nickel carbonate and nickel carbonate weight ratio 1:1 Mixture, mixture of basic manganese carbonate and manganese carbonate with a weight ratio of 1:9, basic cobalt carbonate, Ag ₂ CO ₃ , oxalic acid.

The mixture of basic nickel carbonate and nickel carbonate weight ratio of 1:1, the mixture of basic manganese carbonate and manganese carbonate weight ratio of 1:9, basic cobalt carbonate and Ag ₂ CO ₃ are mixed, and the total volume of solid is added Add 3 times the volume of deionized water, add oxalic acid, wet mill and mix for 10 hours, then add lithium carbonate, and mix with a wet mill for 15 hours to obtain precursor 1; spray dry precursor 1 at 120°C to prepare dry precursor 2. Precursor 2 was placed in an air atmosphere, sintered at 300°C for 3 hours, and cooled to room temperature to obtain a pre-sintered matrix; the pre-sintered matrix was crushed and passed through a 100-mesh sieve, and then placed in an oxygen-enriched atmosphere with an oxygen volume content of 50% In an air gas atmosphere, sintering at 800°C for 3 hours, the preparation of lithium-rich solid solution cathode material with a composition of 0.30 Li ₂ MnO ₃ •0.70 Li[Li _0.10 Ni _0.50 Mn _0.225 Co _0.30 Ag _0.10 ]O ₂ . When the prepared sample is charged and discharged at 58°C, in the voltage range of 4.6 to 2.5V, and at a current of 1C, the discharge capacity of the first cycle is 279mAh/g.

Compared with other inventive methods, the present invention has lower cost of raw materials, wide sources of raw materials, simple preparation process, less time-consuming, uniform composition of prepared electrode materials, and excellent discharge performance, especially in the cycle of discharge under high current conditions. Good performance, laying a good foundation for industrialization.

Example 5

According to lithium ion, nickel ion, manganese ion, cobalt ion, silver ion, acetic acid molar ratio is 1.325: 0.038: 0.625: 0.195: 0.015: 0.856 respectively weigh lithium hydroxide, nickel carbonate, basic manganese carbonate, basic cobalt carbonate Mixture with cobalt carbonate weight ratio 1:9, AgNO ₃ , acetic acid.

Mix the weighed nickel carbonate, basic manganese carbonate, basic cobalt carbonate and a mixture of cobalt carbonate with a weight ratio of 1:9, and _AgNO3 , add distilled water 7 times the volume of the total solid volume, add acetic acid, and mix with a wet mill After 11 hours, lithium hydroxide was added and mixed for 12 hours with a common ball mill to obtain precursor 1; dry precursor 2 was prepared from precursor 1 at 280° C. with a spray dryer. Precursor 2 was placed in a pure oxygen atmosphere, sintered at 300°C for 3 hours, and cooled to room temperature to obtain a precursor calcined material; after the precursor calcined material was crushed and passed through an 80-mesh sieve, it was again placed in a pure oxygen atmosphere, After sintering at 800℃ for 3 hours, a lithium-rich solid solution cathode material with a composition of 0.25Li ₂ MnO ₃ •0.75 Li[Li _0.10 Ni _0.050 Mn _0.50 Co _0.26 Ag _0.02 ]O ₂ was prepared. When the prepared sample is charged and discharged at 58°C, in the voltage range of 4.6 to 2.5V, and at a current of 1C, the discharge capacity of the first cycle is 289mAh/g.

Compared with other inventive methods, the present invention has lower cost of raw materials, wide sources of raw materials, simple preparation process, less time-consuming, uniform composition of prepared electrode materials, and excellent discharge performance, especially in the cycle of discharge under high current conditions. Good performance, laying a good foundation for industrialization.

Example 6

According to the molar ratio of lithium ion, nickel ion, manganese ion, cobalt ion, silver ion and acetic acid is 1.37 : 0.077 : 0.608 : 0.21: 0.014 : 0.80 Weigh lithium hydroxide, nickel carbonate, basic manganese carbonate, basic cobalt carbonate and cobalt carbonate mixture with a weight ratio of 9:1, AgF, and acetic acid.

Mix the mixture of nickel carbonate, basic manganese carbonate, basic cobalt carbonate and cobalt carbonate weight ratio of 9:1, and AgF that have been weighed, add acetone that is 6 times the volume of the total solid volume, add acetic acid, wet mill and mix for 15 hours, Lithium hydroxide was then added, wet milled and mixed for 3 hours to obtain precursor 1. Dry precursor 2 was prepared from precursor 1 with a spray dryer at 200 °C. Precursor 2 was placed in an oxygen-enriched air atmosphere with an oxygen volume content of 99%, sintered at 350°C for 24 hours, and cooled to room temperature to obtain a precursor pre-sintered material; after the precursor pre-calcined material was crushed and passed through an 80-mesh sieve, then Placed in an oxygen-enriched air gas atmosphere with an oxygen content of 59% by volume, and sintered at 980°C for 20 hours to prepare a composite with a composition of 0.30 Li ₂ MnO ₃ •0.70 Li[Li _0.10 Ni _0.11 Mn _0.44 Co _0.30 Ag _0.02 ]O ₂ Lithium-rich solid solution cathode material. When the prepared sample is charged and discharged at 58°C, in the voltage range of 4.6 to 2.5V, and at a current of 1C, the discharge capacity of the first cycle is 170mAh/g.

Compared with other inventive methods, the present invention has lower cost of raw materials, wide sources of raw materials, simple preparation process, less time-consuming, uniform composition of prepared electrode materials, and excellent discharge performance, especially in the cycle of discharge under high current conditions. Good performance, laying a good foundation for industrialization.

Example 7

According to the molar ratio of lithium ion, nickel ion, manganese ion, cobalt ion, silver ion and acetic acid is 1.37 : 0.077 : 0.608 : 0.21: 0.014 : 0.90 Weigh lithium hydroxide, nickel carbonate, basic manganese carbonate, basic cobalt carbonate and cobalt carbonate mixture with a weight ratio of 1:9, AgF, and acetic acid.

Mix the weighed nickel carbonate, basic manganese carbonate, basic cobalt carbonate and a mixture of cobalt carbonate weight ratio 1:9, AgF, add 6 times the volume of acetone of the total solid volume, add acetic acid, wet mill and mix for 15 hours, Lithium hydroxide was then added, wet milled and mixed for 3 hours to obtain precursor 1. Precursor 1 was heated and dried at 200° C. under normal pressure to prepare dry precursor 2 . Precursor 2 was placed in an air atmosphere, sintered at 350°C for 24 hours, and cooled to room temperature to obtain the matrix pre-sintered material; after the matrix pre-sintered material was crushed and passed through an 80-mesh sieve, it was placed in an oxygen-rich environment with a volume content of 51%. The lithium-rich solid solution cathode material with the composition of 0.30 Li2MnO3•0.70 Li[Li0.10Ni0.11Mn0.44Co0.30Ag0.02]O2 was prepared by sintering at 980℃for 20 hours in an oxygen-air atmosphere. When the prepared sample is charged and discharged at 55°C, in the voltage range of 4.6 to 2.5V, and at a current of 1C, the discharge capacity of the first cycle is 182mAh/g.

Compared with other inventive methods, the present invention has lower cost of raw materials, wide sources of raw materials, simple preparation process, less time-consuming, uniform composition of prepared electrode materials, and excellent discharge performance, especially in the cycle of discharge under high current conditions. Good performance, laying a good foundation for industrialization.

Claims (6)

1. the method that is partly dissolved the rich lithium solid solution cathode material of the standby doping of legal system monovalent ion, is characterized in that preparation process is comprised of following steps:

(1) according to the mol ratio of lithium ion, nickel ion, manganese ion, cobalt ions, M ion, be (1.1+0.90x): (1-x) y: (x+z-xz): (1-x) k: (1-x) q take respectively the compound of lithium, the compound of the compound of nickel, manganese, the compound of cobalt and M compound; According to following molar ratio relation, measure organic monoacid: (x+z-xz)≤organic monoacid molal quantity≤x+ (1-x) is (z+y+k+q); The span of x, y, z, q, k meets following relation simultaneously: 0.25≤x≤0.55,0.05≤y≤0.50,0.2127≤z≤0.55,0.02≤q≤0.15,0.05≤k≤0.30,2y+4z+3k+q-2.9=0;

The compound of described manganese is manganese carbonate or basic carbonate manganese, or the mixture of the arbitrary proportion of manganese carbonate and basic carbonate manganese; The compound of described cobalt is cobalt carbonate, cobalt oxalate or basic cobaltous carbonate, or the mixture of the arbitrary proportion of cobalt carbonate and basic cobaltous carbonate; The compound of described nickel is nickelous carbonate or basic nickel carbonate, or the mixture of the arbitrary proportion of nickelous carbonate and basic nickel carbonate;

(2) by the compound of the compound of the compound of the nickel taking, manganese, cobalt and M compound, the 1/10 times of wet grinding media to 10 times of volumes that adds total solid capacity, add organic monoacid, wet-milling mixes 3 hours～15 hours, the compound that adds again lithium, wet-milling mixing obtains predecessor 1 for 3 hours～15 hours; Predecessor 1 use vacuumize or spray-dired method are prepared to dry predecessor 2; Predecessor 2 is placed in to air, oxygen rich gas or pure oxygen atmosphere, adopts double sintering method or the preparation of double fragmentation sintering process to consist of xLi ₂mnO ₃(1-x) Li[Li _0.10ni _ymn _zco _km _q] O ₂rich lithium solid solution cathode material;

Described double fragmentation sintering process is carried out as follows: predecessor 2 is placed in to air, oxygen rich gas or pure oxygen atmosphere, arbitrary temperature sintering of 300 ℃～550 ℃ of temperature ranges 3 hours～15 hours, is cooled to room temperature and makes parent Preburning material; After parent Preburning material is pulverized and being sieved, be again placed in air, oxygen rich gas or pure oxygen, arbitrary temperature sintering of 800 ℃～1050 ℃ of temperature ranges 3 hours～24 hours, prepare rich lithium solid solution cathode material;

Described double sintering method is carried out as follows: predecessor 2 is placed in to air, oxygen rich gas or pure oxygen atmosphere, arbitrary temperature sintering of 300 ℃～550 ℃ of temperature ranges 3 hours～15 hours, then be placed in another sintering furnace at air, oxygen rich gas or pure oxygen atmosphere in arbitrary temperature sintering of 800 ℃～1050 ℃ of temperature ranges 3 hours～24 hours, prepare rich lithium solid solution cathode material;

Described M compound is sodium oxide molybdena, silver oxide, NaOH or potassium hydroxide, or carbonate, chloride, nitrate or the fluoride of sodium, potassium or silver.

2. the method that is partly dissolved the rich lithium solid solution cathode material of the standby doping of legal system monovalent ion according to claim 1, is characterized in that described weak acid is oxalic acid, amion acetic acid, chloroacetic acid, formic acid or acetic acid.

3. the legal system that is partly dissolved according to claim 1 is for the method for the rich lithium solid solution cathode material of doping monovalent ion, it is characterized in that described vacuumize is the arbitrary temperature 80 ℃～280 ℃ of temperature ranges by predecessor 1, the dry predecessor 2 of preparing under the vacuum between 10Pa～10132Pa pressure.

4. the legal system that is partly dissolved according to claim 1 is for the method for the rich lithium solid solution cathode material of doping monovalent ion, it is characterized in that it is the arbitrary temperature 120 ℃～280 ℃ of temperature ranges that described spraying is dried, and adopts spray dryer to prepare dry predecessor 2.

5. the method that is partly dissolved the rich lithium solid solution cathode material of the standby doping of legal system monovalent ion according to claim 1, is characterized in that described wet grinding media is deionized water, distilled water, ethanol, acetone, methyl alcohol or formaldehyde; Described oxygen rich gas is that oxygen volume content is greater than 21% and be less than the gas between 100%.

6. the method that is partly dissolved the rich lithium solid solution cathode material of the standby doping of legal system monovalent ion according to claim 1, is characterized in that described wet-milling mixes, and the equipment of employing comprises general milling machine, super ball mill or wet milk; The compound of described lithium is lithium carbonate, lithium hydroxide or Lithiagel, or the mixture of its arbitrary proportion.