WO2020147143A1

WO2020147143A1 - Lithium ferrite-based negative electrode material of lithium battery, preparation method therefor and use thereof

Info

Publication number: WO2020147143A1
Application number: PCT/CN2019/072905
Authority: WO
Inventors: 卡马里阿里-雷扎; 孙蔷; 谢开钰
Original assignee: 东北大学
Priority date: 2019-01-17
Filing date: 2019-01-24
Publication date: 2020-07-23
Also published as: CN109755471A; CN109755471B

Abstract

Disclosed are a lithium ferrite-based negative electrode material of a lithium battery, a preparation method therefor and the use thereof, wherein same belong to the field of the preparation and use of electrode materials of lithium-ion batteries. The lithium ferrite-based negative electrode material of a lithium battery comprises lithium ferrite, the lithium ferrite having a chemical formula of Li2Fe3O5, and the morphology thereof being particles with an octahedral structure, with a particle size of 0.2-10 µm, and also comprises conductive carbon, a binder, and a solvent. The preparation method therefor comprises: mixing various materials, and stirring same to obtain the negative electrode material. The negative electrode material can be used to prepare a lithium battery. The lithium ion negative electrode material prepared by the invention on the basis of a lithium ferrite material with an octahedral structure not only improves the electrical conductivity, but also alleviates the huge volume change that occurs during intercalation and deintercalation of lithium ions, improves the electrochemical stability of the lithium ion negative electrode material, can greatly improve the lower theoretical specific capacity of graphite as a conventional negative electrode material of a lithium-ion battery, and solves the development barrier of a lower specific capacity of a lithium-ion battery.

Description

Specification Title of invention: Lithium ferrite-based negative electrode material for lithium battery and its preparation method and application Technical field

[0001] The present invention belongs to the field of preparation and application of lithium ion battery electrode materials, and in particular relates to a lithium ferrite-based negative electrode material for lithium batteries and a preparation method and application thereof.

Background technique

[0002] Lithium batteries are used as a common energy storage device with broad market prospects and rapid development due to their higher working voltage and specific energy, fast charge and discharge, and higher safety performance. They are used in daily life production. Has a very wide range of applications. How to improve the capacity and stability of lithium batteries is an important issue to be solved urgently.

[0003] The negative electrode material as the acceptor of lithium ions must maintain a good structure, good chemical stability, high electronic conductivity and lithium ion conductivity during the lithium extraction process, and the negative electrode material should have low cost And environmentally friendly features. Currently, almost all anode materials in commercial applications are carbon-based materials. However, such carbon-based materials still have many shortcomings and shortcomings. Therefore, some new non-carbon anode materials have attracted more and more attention from researchers. Non-carbon anode materials are mainly concentrated in some electrochemically active metals and metal oxides, such as tin (Sn), silicon (Si), Sn0 ₂ , Co ₃ 0 ₄ , Fe ₂ 0 ₃ and Fe ₃ 0 ₄ . Among them, the capacity of transition metal oxide materials is doubled compared with that of carbon-based materials, which is more conducive to the development of high specific capacity lithium ion batteries in the future. 7] C/solvothermal method, sol-gel method, metal precursor pyrolysis method, mechanical ball milling and other common physical or chemical methods can be used to obtain special morphologies (nano hollow structure, mesoporous structure and three-dimensional nano structure) The transition metal oxide anode material. These negative electrode materials with special microscopic morphology exhibit good cycle stability and high reversible capacity, which can reduce the volume change and particle agglomeration problems of transition metal oxide negative electrode materials during the lithium insertion and desorption cycle to a certain extent. At the same time, another type of transition metal oxide composite negative electrode material has also received extensive attention and development, mainly including metal oxide/carbon composite nanomaterials, metal oxide/graphene composite materials, composite films, etc.

[0004] Fe ₃ 0 ₄ is one of considerable development potential negative electrode material having a high specific capacity (926mAh / g), good electron conductivity ^{(a = 2xl0 4 S / m} ), readily available and inexpensive, rich in resources, non-toxic It is superior to other transition metal oxides and is environmentally friendly. Researches on nano-ferric oxide with various morphologies have been reported successively. However, Fe ₃ 0 ₄ as a negative electrode material will undergo significant volume changes and severe particle agglomeration and particle pulverization during the process of lithium insertion and removal, resulting in poor charge and Li ⁺ transport and diffusion performance, poor cycle stability, and poor rate performance. High, and the first coulomb efficiency is low. How to find a new anode material for lithium-ion battery, and its preparation method needs to be a green preparation process with simple steps and low cost, so that it can overcome the above-mentioned problems and difficulties, so that the anode material of lithium-ion battery has a macroscopic structure Stability and excellent microscopic electrochemical performance are the key issues to be solved at present.

Summary of the invention

technical problem

Solution to the problem

Technical solution

[0005] In view of the problems existing in the prior art, the present invention provides a lithium ferrite-based anode material for a lithium battery and a preparation method and application thereof. The lithium ferrite-based anode material for a lithium battery is based on an octahedral structure of lithium ferrite. Based on the material, after being compounded with carbon, it is applied to the anode material of lithium ion battery. The lithium ion anode material prepared on the basis of the octahedral lithium ferrite material not only improves the conductivity, but also alleviates the huge volume change during the insertion and extraction of lithium ions, and improves the performance of the lithium ion anode material. Electrochemical stability can greatly improve the lower theoretical specific capacity of graphite as a negative electrode material of traditional lithium ion batteries, and solve the development obstacle of lower specific capacity of lithium ion batteries. It is expected to provide technical support for the commercial application of anode materials for lithium-ion batteries with high specific capacity in the future.

[0006] A lithium ferrite-based negative electrode material for a lithium battery of the present invention includes lithium ferrite, the chemical formula of the lithium ferrite is Li ₂ Fe ₃ 0 ₅ , and its morphology is an octahedral structure particle with a particle size It is 0.2~l(Vm.

[0007] The lithium ferrite-based negative electrode material for a lithium battery further includes conductive carbon, a binder, and a solvent; wherein, in terms of mass ratio, lithium ferrite: conductive carbon=(8~2) _: 1, bonding The added mass of the agent accounts for 5-20% of the total mass of lithium ferrite + conductive carbon. According to the mass ratio, solvent: solid matter = (4~12) _: 1.

[0008] The solid material is lithium ferrite and conductive carbon.

[0009] The conductive carbon is one or a mixture of acetylene black, conductive graphite, nano graphite, furnace black, Ketjen carbon black, and carbon nanotubes.

[0010] The binder is one or a mixture of polyvinylidene fluoride, polytetrafluoroethylene, butyl rubber, sodium carboxymethyl cellulose, polyacrylic acid, and polyimide. [0011] The solvent is one or a mixture of N-methylpyrrolidone, dimethylformamide, tetrahydrofuran, carbon tetrachloride, water, and ethanol.

[0012] A method for preparing a lithium ferrite-based negative electrode material for a lithium battery of the present invention includes the following steps:

[0013] Step L

[0014] According to the ratio, weigh the lithium ferrite, the conductive carbon, and the binder, and mix and grind to obtain a mixture;

[0015] Step II:

[0016] A solvent is added to the mixture, and the mixture is stirred to form a paste to obtain a lithium ferrite-based negative electrode material for a lithium battery.

[0017] In the step 1, the preparation method of the lithium ferrite includes the following steps:

[0018] In a molten salt protective atmosphere containing water vapor, iron oxide powder or pressed and sintered iron oxide flakes are used as the working cathode, graphite is used as the working anode, and LiCl and its combination with alkali metal chloride and/or alkaline earth metal chloride As a Li molten salt electrolyte, electrolysis is performed at 300-1000°C and a constant voltage of 0.7-1V to obtain the product lithium ferrite; wherein, in the molten salt protective atmosphere, the volume percentage of water vapor is 0.1~10 OVol.%, the balance is argon;

[0019] In the preparation method of lithium ferrite, the Li molten salt electrolyte is one of LiCl, or LiCl and NaCl, KCl, R bCl, CsCl, CaCl ₂ , SrCl ₂ , BaCl ₂ , ZnCl ₂ or A mixture of several.

[0020] In the preparation method of lithium ferrite, the electrolysis time is 10-120 min.

[0021] In the step II, the stirring is uniform, and the stirring time is 10 hours.

[0022] An application of a lithium ferrite-based negative electrode material for a lithium battery. The lithium ferrite-based negative electrode material for a lithium battery can be applied to the negative electrode material of a lithium ion battery.

[0023] An electrode pole piece comprising the above-mentioned lithium ferrite-based lithium battery negative electrode material.

[0024] The method of the present invention for preparing an electrode pole piece by using the foregoing lithium ferrite-based lithium battery negative electrode material includes the following steps:

[0025] Step 1: Coating current collector

[0026] A lithium ferrite-based negative electrode material for a lithium battery is uniformly coated on the current collector, and vacuum-dried at 70 to 90° C. for 12 to 20 hours to obtain a pole piece; wherein, on the current collector, the active material per unit area The load is 0.8~5mg;

[0027] Step 2: Calendering

[0028] The pole pieces are rolled and cut to obtain electrode pole pieces.

[0029] In the step 1, the current collector is copper foil or carbon-coated copper foil. [0030] The electrode pole piece is prepared by the above method for preparing the electrode pole piece.

[0031] A lithium ion battery of the present invention uses the above-mentioned electrode pad as a working electrode.

[0032] The method of the present invention for preparing a lithium ion battery using the above-mentioned electrode pads includes the following steps:

[0033] In an argon atmosphere, the electrode sheet, the diaphragm, and the lithium sheet are assembled into a lithium ion battery.

[0034] The lithium ion battery of the present invention has a first discharge capacity of 900-1300 mAhg- ¹ at a rate of 200 mA/g, and a first reversible charge capacity of 750-950 mAhg- ¹ , so the first coulombic efficiency reaches 60-80%. The specific capacity of reversible discharge after 300 cycles is 500-800mAhg-^ Coulombic efficiency is 95-100%.

Beneficial effects of invention

Beneficial effect

[0035] Compared with the existing ferroferric oxide-based lithium ion battery negative electrode material, the lithium ferrite-based lithium battery negative electrode material and the preparation method and application thereof of the present invention have the following advantages and beneficial effects:

[0036] 1. The present invention makes full use of the good electrical and thermal conductivity of high-temperature molten salt and a wide electrochemical window, and can achieve the morphology and particle size of the electrolytic product lithium ferrite at a lower cathode polarization potential and electrolysis temperature The regulation and control, thus laying the foundation for the preparation of high specific capacity anode materials.

[0037] 2. The lithium ferrite-based lithium battery negative electrode material of the present invention has a special morphology and composition. The preparation method of the lithium ferrite is electrolysis in a high temperature molten salt in a humid atmosphere, which has lower energy consumption and relatively low energy consumption. The short process significantly improves production efficiency. In addition, the lithium ferrite of the present invention has a homogeneous phase, and its preparation method does not generate other by-products, which truly realizes a new short-flow process route of directly preparing a precursor of a lithium-ion battery negative electrode material.

[0038] 3. The high specific capacity lithium ferrite/carbon composite material used in the anode material of lithium ion battery prepared by the present invention

, Has excellent long-cycle stability and rate performance.

Brief description of the drawings

BRIEF DESCRIPTION

1 is an XRD pattern, where ⑻ is the XRD pattern of the raw material iron oxide (Fe ₂ O ₃ ) used; (b) is the XRD pattern of the electrolytic product lithium ferrite.

[0040] FIG. 2 is an SEM image of lithium ferrite in the lithium ferrite-based lithium battery negative electrode material of the present invention.

[0041] FIG. 3 is a graph showing the charge and discharge curves of a battery prepared based on lithium ferrite-based lithium battery anode materials.

[0042] FIG. 4 is a graph showing the cycle performance of a battery prepared based on lithium ferrite-based lithium battery anode materials. Invention embodiment

Embodiments of the invention

[0043] The present invention will be further described in detail below in conjunction with embodiments.

[0044] In the following embodiments, unless otherwise specified, the raw materials and equipment used are all commercially available, and the purity of the raw materials is analytically pure.

[0045] Embodiment 1

[0046] In a lithium ferrite-based negative electrode material for a lithium battery, the method for preparing the lithium ferrite is:

[0047] Iron oxide (Fe ₂ O ₃ ) powder (see Figure 1 (8) for XRD) was directly used as the working cathode, and graphite was used as the working anode. The electrolyte was LiCl, the electrolysis temperature was 660° C., the electrolysis voltage was IV, and the electrolysis The time is 60 min, the heating rate before electrolysis and the rate of cooling after electrolysis are both 3°C/min. During the electrolysis process, the flow rate of argon gas flowing into the electrolytic cell is 600 mL/min. The electrolytic cell is connected to the U-shaped quartz tube. The U-shaped quartz tube is filled with deionized water. After the argon gas flows through the U-shaped quartz tube, the humid argon gas flows in. In a sealed reactor, electrolysis is carried out under a protective atmosphere of molten salt containing water vapor. After the electrolysis experiment is over, the cathode is lifted from the molten salt, washed with a large amount of deionized water to remove the molten salt attached to the cathode, and dried to obtain the electrolytic product lithium ferrite.

[0048] The prepared lithium ferrite was tested and analyzed by XRD and SEM. The XRD pattern is shown in Fig. 1(b). The lithium ferrite is used as the precursor of the negative electrode material of the lithium battery. The XRD pattern in Fig. 1 is analyzed, The chemical formula of the lithium ferrite prepared in this embodiment is Li ₂ Fe ₃ 0 ₅ .

[0049] The SEM image of the lithium ferrite prepared in this example is shown in Fig. 2. From Fig. 2, it can be seen that the morphology is octahedral structure particles and the average particle size is 2 pm.

[0050] A lithium ferrite-based negative electrode material for a lithium battery, comprising the lithium ferrite prepared above, as well as conductive carbon, a binder, and a solvent; wherein, by mass ratio, lithium ferrite: conductive carbon=2:1 , The added mass of the binder accounts for 11.1% of the total mass of lithium ferrite + conductive carbon. According to the mass ratio, solvent: solid matter = 9:1.

[0051] The conductive agent is acetylene black, the binder is polyvinylidene fluoride, and the solvent is N-methylpyrrolidone.

[0052] A method for preparing a lithium ferrite-based negative electrode material for a lithium battery includes the following steps:

[0053] Weigh 6g of lithium ferrite, 3g of conductive carbon and 1g of binder, mix and grind, add 80ml of N-methylpyrrolidone, and magnetically stir for 10 hours to form a paste to obtain a lithium ferrite-based lithium battery negative electrode material.

[0054] The process of assembling a button half-cell based on lithium ferrite-based negative electrode materials for lithium batteries is as follows: Lithium lithium battery negative electrode material is coated on copper foil and dried in vacuum at 80 ° C for 18h to form an electrode sheet, wherein, on the current collector, the loading amount of active material per unit area is 2mg;

[0055] After the electrode sheet is sliced and pressed, and the lithium sheet is used as the counter electrode, the CR2025 button battery is assembled in the glove box. Conduct constant current charge and discharge tests on the assembled CR2025 button battery to investigate its cycle stability and rate performance. The charge and discharge curve is shown in Figure 3. As can be seen from Figure 3, the first discharge curve in the figure has two obvious areas, the longer voltage plateau at 0.8V and the subsequent voltage drop to 0.01V, which is mainly due to the formation of the SEI film And Fe ³⁺ /Fe ²⁺ change to Fe °; the second and third discharge curves basically coincide.

[0056] In this embodiment, a battery prepared based on a lithium ferrite negative electrode material for a lithium battery was measured at room temperature for the first discharge capacity, first coulomb efficiency and reversible charge capacity of the button cell produced. The cycle performance diagram is shown in Figure 4. The results are as follows:

[0057] At a rate of 200mA/g, the first discharge capacity is 1102.7mAhg- ¹

, The first reversible charging capacity is 808.4mAhg- ⁱ , so the first coulombic efficiency reaches 73.32%, and the reversible discharge specific capacity after 220 cycles is 604mAhg-^ the coulombic efficiency is 100%.

[0058] Embodiment 2

[0059] In a lithium ferrite-based negative electrode material for a lithium battery, the method for preparing the lithium ferrite is the same as in Embodiment 1, with the difference:

[0060] (1) The iron oxide powder is pressed (20 MPa, pressure holding for 10 minutes), and then sintered at a constant temperature of 800° C. for 2 hours to obtain a flake cathode;

[0061] (2) The electrolysis voltage is 0.7V, the electrolysis time is 120min, and the electrolysis temperature is 450°C;

[0062] ⑶ electrolyte chemical composition is LiCl-KCl (wherein, LiCl is 59.2mol%, KC1 is 40.8mol%) _;

[0063] A lithium ferrite-based negative electrode material for a lithium battery, comprising the lithium ferrite prepared above, as well as conductive carbon, a binder, and a solvent; wherein, by mass ratio, lithium ferrite: conductive carbon=2:1 , The added mass of the binder accounts for 11.1% of the total mass of lithium ferrite + conductive carbon. According to the mass ratio, solvent: solid matter = 9:1.

[0064] The conductive agent is conductive graphite, the binder is sodium carboxymethyl cellulose, the solvent is a mixture of water and ethanol, the volume percentage of ethanol is 95%, and the balance is water.

[0065] A method for preparing a negative electrode material for a lithium battery based on lithium ferrite includes the following steps:

[0066] Weigh 6g of the lithium ferrite prepared in this example, 3g of conductive carbon and 1g of binder, mix and grind, add 80mL of solution After mixing with 1J, magnetically stirred for 10 hours to form a paste to obtain a lithium ferrite-based negative electrode material for a lithium battery.

[0067] The process of assembling a button half-cell based on lithium ferrite-based lithium battery anode materials is: coating the adjusted lithium ferrite-based lithium battery anode materials on copper foil, and vacuum drying at 70° C. for 20 hours , The electrode sheet is made, in which, on the current collector, the load per unit area of the active material is 0.8 mg;

[0068] After being sliced and pressed, the electrode sheet is used as a counter electrode with a lithium sheet and assembled in a glove box to form a CR2025 button battery. The electrochemical performance test was performed on a constant current charge and discharge system at a rate of 200mA/g.

[0069] Embodiment 3

[0070] The method is the same as in Embodiment 1, and the difference is:

[0071] (1) The electrolysis voltage is 0.9V, the electrolysis time is 20min, and the electrolysis temperature is 590°C;

[0072] (2) The electrolyte chemical component is LiCl-SrCl ₂ (64.3:35.7 mol%);

[0073] (3) Weigh 6g of lithium ferrite prepared under the conditions, 3g of conductive carbon and 1g of binder, mix and grind, add 80mL

N-methylpyrrolidone, magnetic stirring for 10h. The adjusted slurry was coated on copper foil to make electrode sheets, which were sliced, pressed and used as counter electrodes with lithium sheets, and assembled into a CR2025 button battery in a glove box. The electrochemical performance test was performed on a constant current charging and discharging system at a rate of 200mA/g.

[0074] Embodiment 4

[0075] In a lithium ferrite-based negative electrode material for a lithium battery, the method for preparing the lithium ferrite is: the same as in embodiment 1, the difference is:

[0076] (1) The electrolysis voltage is 0.8V, the electrolysis time is 90min, and the electrolysis temperature is 400°C;

[0077] (2) The chemical composition of the electrolyte is a mixture of LiCl-KCl-CsCl; (wherein, LiCl: K

Cl: CsCl=57.5:24.6: 17.9mol%);

[0078] A lithium ferrite-based negative electrode material for a lithium battery, including the lithium ferrite prepared above, as well as conductive carbon, a binder, and a solvent; wherein, by mass ratio, lithium ferrite: conductive carbon=2:1 , The added mass of the binder accounts for 11.1% of the total mass of lithium ferrite + conductive carbon. According to the mass ratio, solvent: solid matter = 9:1.

[0079] The conductive agent is conductive graphite, the binder is sodium carboxymethyl cellulose, the solvent is a mixture of water and ethanol, the volume percentage of ethanol is 95%, and the balance is water.

[0080] A method for preparing a negative electrode material for a lithium battery based on lithium ferrite includes the following steps:

[0081] Weigh 6g of the lithium ferrite prepared in this embodiment, 3g of conductive carbon, and 1g of binder, mix and grind, add 80mL of solvent 1J, magnetically stir for 10h, and form a paste to obtain a lithium ferrite-based anode material for a lithium battery . [0082] The process of assembling the negative electrode material for lithium batteries based on lithium ferrite into a button half-cell is: coating the adjusted negative electrode material for lithium batteries based on lithium ferrite on copper foil, and vacuum drying at 90° C. for 12 hours , The electrode sheet is made, in which, on the current collector, the load per unit area of the active material is 5mg;

[0083] After being sliced and pressed, the electrode sheet is used as a counter electrode with the lithium sheet and assembled in a glove box to form a CR2025 button battery. The electrochemical performance test was performed on a constant current charge and discharge system at a rate of 200mA/g.

[0084] Embodiment 5

[0085] In a lithium ferrite-based negative electrode material for lithium batteries, the method for preparing lithium ferrite is the same as in Example 1.

[0086] A lithium ferrite-based negative electrode material for a lithium battery, including the lithium ferrite prepared above, and conductive carbon, a binder, and a solvent; wherein, in terms of mass ratio, lithium ferrite: conductive carbon=8:1 , The added mass of the binder accounts for 20% of the total mass of lithium ferrite + conductive carbon. According to the mass ratio, solvent: solid matter=4:1.

[0087] The conductive agent is a mixture of graphite nanotubes and carbon nanotubes (the mass ratio is 1: 1), and the binder is polyvinylidene fluoride and polytetrafluoroethylene (the mass ratio is 1: 1) , The solvent is tetrahydrofuran.

[0088] A method for preparing a negative electrode material for a lithium battery based on lithium ferrite includes the following steps:

[0089] Weigh 8g of the lithium ferrite prepared in this embodiment, 1g of conductive carbon and 1.8g of binder, mix and grind, add 32mL of tetrahydrofuran, and magnetically stir for 10h to form a paste to obtain a lithium ferrite-based anode material for a lithium battery.

[0090] The process of assembling the negative electrode material for lithium batteries based on lithium ferrite into a button half-cell is: coating the adjusted negative electrode material for lithium batteries based on lithium ferrite on copper foil, and vacuum drying at 70° C. for 20 hours , The electrode sheet is made, in which, on the current collector, the load per unit area of the active material is 0.8 mg;

[0091] After being sliced and pressed, the electrode sheet is used as a counter electrode with the lithium sheet and assembled in a glove box to form a CR2025 button battery. The electrochemical performance test was performed on a constant current charge and discharge system at a rate of 200mA/g.

[0092] Example 6

[0093] In a lithium ferrite-based negative electrode material for a lithium battery, the method for preparing the lithium ferrite is the same as in Example 1.

[0094] A lithium ferrite-based negative electrode material for a lithium battery, including the lithium ferrite prepared above, as well as conductive carbon, a binder, and a solvent; wherein, by mass ratio, lithium ferrite: conductive carbon=6:1 , The added mass of the binder accounts for 5% of the total mass of lithium ferrite + conductive carbon. According to the mass ratio, solvent: solid matter = 12:1.

[0095] The conductive agent is furnace black and Ketjen carbon black (mass ratio is 1:1), the binder is polyacrylic acid and polyimide (mass ratio is 1:1), the The solvent is N-methylpyrrolidone.

[0096] A method for preparing a lithium ferrite-based negative electrode material for a lithium battery includes the following steps: [0097] Weigh 6g of the lithium ferrite prepared in this embodiment, 3g of conductive carbon and 0.35g of binder, mix and grind, add 134mL of N-methylpyrrolidone, and magnetically stir for 8h to form a paste to obtain lithium ferrite-based lithium Battery anode material.

[0098] The process of assembling the negative electrode material for lithium batteries based on lithium ferrite into a button half-cell is: coating the adjusted negative electrode material for lithium batteries based on lithium ferrite on copper foil, and vacuum drying at 80° C. for 14 hours , The electrode sheet is made, wherein, on the current collector, the active material per unit area is 3mg;

[0099] After the electrode sheet is sliced and pressed, and the lithium sheet is used as the counter electrode, the CR2025 button battery is assembled in the glove box. The electrochemical performance test was performed on a constant current charge and discharge system at a rate of 200mA/g.

Claims

[Claim 1] A lithium ferrite-based anode material for a lithium battery, characterized in that the lithium ferrite-based anode material for a lithium battery includes lithium ferrite, and the chemical formula of the lithium ferrite is Li ₂ Fe ₃ 0 _5. Its morphology is an octahedral structure particle with a particle size of 0.2~10 [xm.

[Claim 2] The lithium ferrite-based lithium battery negative electrode material according to claim 1, wherein the lithium ferrite-based lithium battery negative electrode material further comprises conductive carbon, a binder, and a solvent; Among them, according to the mass ratio, lithium ferrite: conductive carbon = (8~2) _: 1. The added mass of the binder accounts for 5-20% of the total mass of lithium ferrite + conductive carbon. According to the mass ratio, the solvent: solid matter =(4~12)

: 1; The solid material is lithium ferrite and conductive carbon.

[Claim 3] The lithium ferrite-based negative electrode material for lithium batteries according to claim 1 or 2, wherein the conductive carbon is ethylene black, conductive graphite, nano graphite, furnace black, Ketjen carbon black , One or several mixtures of carbon nanotubes.

[Claim 4] The lithium ferrite-based negative electrode material for lithium batteries of claim 1 or 2, wherein the binder is polyvinylidene fluoride, polytetrafluoroethylene, butyl rubber, carboxylate One or a mixture of sodium methylcellulose, polyacrylic acid, and polyimide.

[Claim 5] The negative electrode material for lithium batteries based on lithium ferrite according to claim 1 or 2, wherein the solvent is N-methylpyrrolidone, dimethylformamide, tetrahydrofuran, tetrachloride One or a mixture of carbon, water and ethanol.

[Claim 6] The method for preparing a lithium ferrite-based negative electrode material for a lithium battery according to any one of claims 1 to 5, characterized in that it comprises the following steps:

Step L

According to the proportion, weigh the lithium ferrite, the conductive carbon, and the binder, and mix and grind to obtain the mixture; step IL

The solvent is added to the mixture, and the mixture is stirred to form a paste to obtain a lithium ferrite-based negative electrode material for a lithium battery.

[Claim 7] The method for preparing a lithium ferrite-based negative electrode material for a lithium battery according to claim 6, characterized in that, in the step I, the lithium ferrite and the preparation method thereof include the following steps : In a molten salt protective atmosphere containing water vapor, iron oxide powder or pressed and sintered iron oxide flakes are used as the working cathode, graphite is used as the working anode, and LiCl and its mixture with alkali metal chlorides and/or alkaline earth metal chlorides As a Li molten salt electrolyte, electrolysis is performed at a constant voltage of 0.7-1V at 300-1000°C to obtain the product lithium ferrite; wherein, in the molten salt protective atmosphere, the volume percentage of water vapor is 0.1-100Vol .%, the balance is argon.

[Claim 8] The method for preparing a lithium ferrite-based negative electrode material for a lithium battery according to claim 7, wherein, in the method for preparing lithium ferrite, the Li molten salt electrolyte is LiCl, or Li Cl and one or a mixture of NaCl, KC1, RbCl, CsCl, CaCl ₂ , SrCl ₂ , BaCl ₂ , and ZnCl ₂ .

[Claim 9] The method for preparing a lithium ferrite-based negative electrode material for a lithium battery according to claim 7, characterized in that, in the method for preparing lithium ferrite, the electrolysis time is 10 to 120 minutes.

[Claim 10] An application of a lithium ferrite-based negative electrode material for a lithium battery, characterized in that the lithium ferrite-based negative electrode material for a lithium battery can be applied to a negative electrode material of a lithium ion battery.

[Claim 11] An electrode pole piece, characterized by comprising the lithium ferrite-based negative electrode material for lithium batteries according to any one of claims 1 to 5.

[Claim 12] A method for preparing electrode pole pieces using the lithium ferrite-based lithium battery negative electrode material of any one of claims 1 to 5, characterized in that it comprises the following steps: Step 1: Coating a current collector

Coat the negative electrode material of lithium battery based on lithium ferrite uniformly on the current collector and vacuum-dry it at 70~90°C for 12-20 hours to obtain the pole piece; wherein, on the current collector, the loading amount of the active material per unit area is 0.8 ~5mg;

Step 2: calendering

The pole pieces are rolled and cut to obtain electrode pole pieces.

[Claim 13] The method for preparing electrode pads as recited in claim 12, wherein the step

In 1, the current collector is copper foil or carbon-coated copper foil.

[Claim 14] A lithium ion battery, characterized in that the electrode pad of claim 11 is used as a working electrode.

[Claim 15] A method for preparing a lithium ion battery using the electrode pad of claim 11, characterized in It includes the following steps:

In an argon atmosphere, the electrode sheet, diaphragm, and lithium sheet are assembled into a lithium-ion battery.

[Claim 16] The lithium ion battery of claim 14, wherein the lithium ion battery is

At the rate of A/g, the first discharge capacity is 900-1300mAhg-^ The first reversible charge capacity is 750-950mAhg-^ So the first coulombic efficiency reaches 60-80%, and the reversible discharge specific capacity after 300 cycles is 500-800mAhg- ^ Coulomb efficiency is 95-100%.