CN114520328B

CN114520328B - Lithium ion battery negative electrode material, preparation method thereof, negative electrode and battery

Info

Publication number: CN114520328B
Application number: CN202011312113.7A
Authority: CN
Inventors: 刘涛; 李先锋; 张华民; 国海鹏; 赵晓伟
Original assignee: Dalian Institute of Chemical Physics of CAS; Fengfan Co Ltd
Current assignee: Dalian Institute of Chemical Physics of CAS; Fengfan Co Ltd
Priority date: 2020-11-20
Filing date: 2020-11-20
Publication date: 2023-10-10
Anticipated expiration: 2040-11-20
Also published as: CN114520328A

Abstract

The lithium ion battery negative electrode material is prepared by pre-carbonizing biomass raw materials, removing impurities, coating asphalt and carbonizing, and forms a structure with larger internal disordered layer spacing and graphite-like characteristics on the outside. The negative electrode material can meet the requirement of rapid charge and discharge in the electrode, and realizes the high-rate performance of the negative electrode material; but also can reduce irreversible capacity loss caused by excessive formation of solid electrolyte interface films, and has higher initial cycle coulombic efficiency.

Description

Lithium ion battery negative electrode material, preparation method thereof, negative electrode and battery

Technical Field

The invention belongs to the field of lithium ion batteries, and particularly relates to a negative electrode material for a high specific power lithium ion battery and a preparation method thereof.

Background

As a currently mainstream secondary battery technology, lithium ion batteries are widely used in industries such as consumer electronics, electric automobiles, and large-scale energy storage, and greatly improve human life. Along with the change of application environment, lithium ion batteries are increasingly required to have rapid charge and discharge capability, such as starting and stopping batteries for automobiles, high-speed rails and subways, unmanned aerial vehicle model batteries and the like.

The rapid charge and discharge performance requires that the lithium ion battery complete an electrochemical reaction in a very short time. Therefore, the requirement on electron and ion transmission is very high, and in particular, the transmission speed of lithium ions at and near the negative electrode is a key factor for limiting the high specific power of the lithium ions. The currently marketed negative electrode materials include graphite, amorphous carbon material, lithium titanate, and the like. The specific capacity of graphite can reach more than 300 mA.h/g, the initial cycle coulomb efficiency can reach more than 90%, but the graphite material has the problems of poor structural stability and poor compatibility with electrolyte, and is easy to generate co-intercalation reaction with propylene carbonate organic solvent in the electrolyte in the process of charging and discharging to cause structural damage, thereby influencing the cycle stability and the charging and discharging efficiency of the battery. And due to the anisotropic structure characteristic of graphite, free diffusion of lithium ions in a graphite structure is limited, and the interlayer spacing is small, so that the rate performance of the graphite anode material is influenced. The amorphous carbon material mainly comprises hard carbon and soft carbon, compared with graphite, the amorphous carbon material has low crystallinity, micropores exist, the lamellar structure is not orderly like graphite, the repeated graphite lamellar structure is generally lower than 2-3 layers, the mutually staggered lamellar structure enables Li+ to be inserted and extracted from various angles of the material, the interlayer spacing is large, and the rapid diffusion of lithium ions is facilitated, so that the rapid charge and discharge of the material can be realized. Because the solvent co-intercalation and obvious lattice expansion and shrinkage phenomena which are easy to occur to the graphite materials do not occur, the hard carbon and soft carbon materials have the advantage of good cycle performance. In addition, the cost of the method is obviously lower than that of graphite anode materials because graphitization treatment is not needed in the processing process. However, the first cycle efficiency of this class of materials is low (40-60%). How to realize high specific power discharge and high first efficiency at the same time is the key of high-rate charge-discharge battery.

Disclosure of Invention

Aiming at the problem of low initial cycle coulomb efficiency of the existing hard carbon material taking biomass as a raw material, the invention provides a cathode material for a high specific power lithium ion battery, which is a carbon material and has a core-shell structure, wherein the inner core particle diameter is 3-8 mu m, and the 002 crystal face layer spacing is 0.37-0.41nm; the outer shell thickness is 10-1000nm, and 002 crystal plane layer spacing is 0.34-0.36nm. The solid electrolyte interface film can not only meet the requirements of rapid charge and discharge in the electrode, but also realize compact solid electrolyte interface film outside the cathode. The battery cathode material is particles with micron-scale particle size, wherein the particles are formed by tightly combining the inside and the outside. The invention also provides a preparation method of the anode material, which is as follows, but is not limited to the following:

1) Drying and crushing biomass raw materials, and performing pre-carbonization treatment for 1-3 hours at 500-800 ℃ in inert atmosphere to obtain a product A;

2) Sequentially placing the product A into NaOH solution and acid solution for soaking, stirring and cleaning (the cleaning purpose is to remove impurities except carbon (the impurities comprise silicon, metal elements and the like) in the raw materials), filtering, washing to be neutral, drying, and crushing by a jet mill to obtain carbon powder B with the particle size of 3-8 mu m;

3) The method comprises the specific steps of firstly soaking carbon powder B into a solvent (enabling the carbon powder to be completely soaked by the solvent), taking out the carbon powder adsorbed with the solvent, heating asphalt to 210-350 ℃, adding the solvent, stirring to prepare a mixed solution, adding the carbon powder adsorbed with the solvent into the asphalt solution while stirring, drying, and carbonizing at 1100-1300 ℃ for 1-3h in an inert atmosphere to obtain the anode material.

Wherein, the liquid crystal display device comprises a liquid crystal display device,

the biomass raw material is one or more than two of coconut shells, peach shells, apricot shells and walnut shells.

The inert atmosphere in the steps 1) and 3) is nitrogen atmosphere and/or argon atmosphere respectively;

the concentration of the NaOH solution in the step 2) is 1-5mol/L, and the acid solution is hydrochloric acid solution, sulfuric acid solution or nitric acid solution, and the concentration is 1-5mol/L; the dipping and stirring time is 1-100h, preferably 25-50h; the temperature during stirring is in the range of 25-70 degrees, preferably 50-70 degrees.

The asphalt is petroleum asphalt, and the softening point is 200-250 ℃. Heating asphalt to a temperature 10-50 ℃ higher than the softening point of the asphalt, adding a solvent, and stirring to prepare a mixed solution, wherein the mass fraction of the asphalt solution is 30-50%.

The solvent is one or more of N-methyl pyrrolidone, dimethylacetamide, hexamethyl phosphonyl triamine, hexaethyl phosphonyl triamine and diphenyl ether.

The mass ratio of the carbon powder B to the asphalt is 6/4-8/2.

The invention also provides a lithium ion battery anode, and the active material of the anode is the material.

The invention also provides a lithium ion battery, and the negative electrode of the lithium ion battery is the negative electrode.

The invention has the following advantages:

(1) The anode material provided by the invention has a hard carbon structure inside, has large interlayer spacing, is favorable for the diffusion of lithium ions therein, can meet the requirements of rapid charge and discharge inside an electrode, and realizes the high rate performance of the anode material.

(2) The external surface of the negative electrode material provided by the invention has graphite-like characteristics, has good conductivity, can reduce the resistance of the negative electrode, and is beneficial to realizing the high rate performance of the negative electrode material.

(3) The negative electrode material provided by the invention has a lower specific surface area than a hard carbon material, can reduce irreversible capacity loss caused by excessive formation of a solid electrolyte interface film, and has higher initial cycle coulombic efficiency.

Detailed Description

The invention is illustrated by the following specific examples.

The prepared negative electrode material is used for testing the button cell, and the battery testing methods in the examples and the comparative examples are the same and specifically comprise the following steps: the prepared cathode material, a conductive agent and polyvinylidene fluoride are prepared according to the following proportion of 90:2:8 mass ratio, and uniformly dispersing the mixture into N-methyl pyrrolidone. Is coated on the surface of the copper foil to form the electrode plate containing 3+/-0.3 mg of negative electrode material per square centimeter of the copper foil. After the electrode slice is punched into a wafer, a battery structure with a sandwich structure is formed by the electrode slice, a diaphragm and metal lithium, electrolyte (the concentration of lithium hexafluorophosphate is 1mol/L, and the solvent is ethylene carbonate, dimethyl carbonate and diethyl carbonate (volume ratio is 1:1:1) and contains 2% of ethylene carbonate). The battery performance test uses CCCV charge and discharge method, i.e., 0.1C current is charged to 0V, then constant voltage is charged to 0.02C, then 0.1C discharge is charged to 1.5V as one cycle, the first cycle coulomb efficiency of the negative electrode material is obtained by using the discharge capacity to charge capacity and recorded in table 1, then charging and discharging are performed at 1C, 2C and 5C currents, the cut-off voltage is 0V to 1.5V, and 5 cycles are run at each current, and the average value is recorded in table 1.

Example 1

Drying 1kg of coconut shell in a vacuum drying oven at 110 ℃ for 8 hours, crushing by a crusher, and carrying out pre-carbonization treatment in an argon atmosphere at 500 ℃ for 2 hours; then placing the powder into a 1M NaOH solution for ultrasonic cleaning for 2 hours, then placing the powder into a 2M hydrochloric acid solution for ultrasonic cleaning for 2 hours, filtering, washing the powder with deionized water until the pH value is 7, drying the powder at 110 ℃, and then adopting an air flow pulverizer to perform pulverizing treatment to obtain carbon powder with the particle size of 3-8 mu M; adding 100g of carbon powder into N-methyl pyrrolidone, soaking for 5 hours, and taking out; and heating 25g of petroleum asphalt with a softening point of 200 ℃ to 220 ℃, adding 50ml of N-methyl pyrrolidone, stirring to prepare a mixed solution, adding carbon powder adsorbed with the N-methyl pyrrolidone into the asphalt solution while stirring, carbonizing at 1100 ℃ for 2 hours in an argon atmosphere after drying, cooling to room temperature, crushing and sieving to obtain the cathode material with a core-shell structure, wherein the particle size of the core is 3-8 mu m, the interlayer spacing of 002 crystal faces is 0.38nm, the thickness of the shell is 100-500nm, and the interlayer spacing of 002 crystal faces is 0.35nm.

The negative electrode material is made into a button cell, the battery performance of the button cell is detected, the reversible capacity of the battery in charge and discharge is 382mAh/g, the initial cycle coulomb efficiency is 80.6%, and the reversible capacity at the rate performance of 5C/the reversible capacity at the rate performance of 0.1C is 69.9%.

Comparative example 1

Drying 1kg of coconut shell in a vacuum drying oven at 110 ℃ for 8 hours, crushing by a crusher, and carrying out pre-carbonization treatment in an argon atmosphere at 500 ℃ for 2 hours; then placing the powder into a 1M NaOH solution for ultrasonic cleaning for 2 hours, then placing the powder into a 2M hydrochloric acid solution for ultrasonic cleaning for 2 hours, filtering, washing the powder with deionized water until the pH value is 7, drying the powder at 110 ℃, and then adopting an air flow pulverizer to perform pulverizing treatment to obtain carbon powder with the particle size of 3-8 mu M; then carbonizing the material in argon atmosphere at 1100 deg.c for 2 hr, cooling to room temperature, crushing and sieving to obtain negative electrode material with grain size of 3-8 microns and 002 crystal plane interval of 0.38 nm. The performance of the resulting battery was as shown in Table 1.

Comparative example 2

Drying 1kg of coconut shell in a vacuum drying oven at 110 ℃ for 8 hours, crushing by a crusher, and carrying out pre-carbonization treatment in an argon atmosphere at 500 ℃ for 2 hours; then adopting an air flow pulverizer to perform pulverizing treatment to obtain carbon powder with the particle size of 3-8 mu m; then carbonizing the material in argon atmosphere at 1100 deg.c for 2 hr, cooling to room temperature, crushing and sieving to obtain negative electrode material with grain size of 3-8 microns and 002 crystal plane interval of 0.38 nm. The performance of the resulting battery was as shown in Table 1.

Comparative example 3

Drying 1kg of petroleum asphalt with a softening point of 200 ℃ in a vacuum drying oven at 110 ℃ for 8 hours, then carrying out pre-carbonization treatment in an argon atmosphere, wherein the temperature of the heat treatment is 500 ℃ and the time is 2 hours, and then carrying out crushing treatment by adopting a jet mill to obtain carbon powder with a particle size of 3-8 mu m; then carbonizing the material in argon atmosphere at 1100 deg.c for 2 hr, cooling to room temperature, crushing and sieving to obtain negative electrode material with grain size of 3-8 microns and 002 crystal plane interval of 0.35nm. The performance of the resulting battery was as shown in Table 1.

Comparative example 4

Drying 1kg of coconut shell in a vacuum drying oven at 110 ℃ for 8 hours, crushing by a crusher, and carrying out pre-carbonization treatment in an argon atmosphere at 500 ℃ for 2 hours; then placing the powder into a 1M NaOH solution for ultrasonic cleaning for 2 hours, then placing the powder into a 2M hydrochloric acid solution for ultrasonic cleaning for 2 hours, filtering, washing the powder with deionized water until the pH value is 7, drying the powder at 110 ℃, and then adopting an air flow pulverizer to perform pulverizing treatment to obtain carbon powder with the particle size of 3-8 mu M; then mixing the asphalt with petroleum asphalt with a softening point of 200 ℃ and dimethylbenzene according to a mass ratio of 80:20:50, adding the mixture into a reaction kettle for coating treatment, wherein the treatment temperature is 220 ℃ and the time is 2 hours; carbonizing the coated carbon powder in argon atmosphere at 1100 deg.c for 2 hr, cooling to room temperature, crushing and sieving to obtain the cathode material with core-shell structure, the core particle size of 3-8 microns, 002 crystal plane interval of 0.38nm, shell thickness of 100-500nm and 002 crystal plane interval of 0.35nm. The performance of the resulting battery was as shown in Table 1.

Example 2

Drying 1kg of coconut shell in a vacuum drying oven at 110 ℃ for 8 hours, crushing by a crusher, and carrying out pre-carbonization treatment in an argon atmosphere at 800 ℃ for 2 hours; then placing the powder into a 1M NaOH solution for ultrasonic cleaning for 2 hours, then placing the powder into a 2M hydrochloric acid solution for ultrasonic cleaning for 2 hours, filtering, washing the powder with deionized water until the pH value is 7, drying the powder at 110 ℃, and then adopting an air flow pulverizer to perform pulverizing treatment to obtain carbon powder with the particle size of 3-8 mu M; adding 100g of carbon powder into N-methyl pyrrolidone, soaking for 5 hours, heating 25g of petroleum asphalt with a softening point of 200 ℃ to 220 ℃, adding 50ml of N-methyl pyrrolidone, stirring to prepare a mixed solution, adding the carbon powder adsorbed with the N-methyl pyrrolidone into the asphalt solution while stirring, carbonizing for 2 hours at 1100 ℃ in an argon atmosphere after drying, cooling to room temperature, crushing and sieving to obtain the cathode material with a core-shell structure, wherein the particle size of the core is 3-8 mu m, the spacing between 002 crystal faces is 0.38nm, the thickness of the shell is 100-500nm, and the spacing between 002 crystal faces is 0.35nm. The negative electrode material was prepared into a button cell, and the performance thereof is shown in table 1.

Example 3

Drying 1kg of coconut shell in a vacuum drying oven at 110 ℃ for 8 hours, crushing by a crusher, and carrying out pre-carbonization treatment in an argon atmosphere at 500 ℃ for 2 hours; then placing the powder into a 1M NaOH solution for ultrasonic cleaning for 2 hours, then placing the powder into a 2M hydrochloric acid solution for ultrasonic cleaning for 2 hours, filtering, washing the powder with deionized water until the pH value is 7, drying the powder at 110 ℃, and then adopting an air flow pulverizer to perform pulverizing treatment to obtain carbon powder with the particle size of 3-8 mu M; adding 100g of carbon powder into N-methyl pyrrolidone, soaking for 5 hours, heating 25g of petroleum asphalt with a softening point of 200 ℃ to 220 ℃, adding 50ml of N-methyl pyrrolidone, stirring to prepare a mixed solution, adding the carbon powder adsorbed with the N-methyl pyrrolidone into the asphalt solution while stirring, carbonizing for 2 hours at 1200 ℃ in an argon atmosphere after drying, cooling to room temperature, crushing and sieving to obtain the cathode material with a core-shell structure, wherein the particle size of the core is 3-8 mu m, the spacing between 002 crystal faces is 0.376nm, the thickness of the shell is 100-500nm, and the spacing between 002 crystal faces is 0.35nm. The negative electrode material was prepared into a button cell, and the performance thereof is shown in table 1.

Example 4

Drying 1kg of coconut shell in a vacuum drying oven at 110 ℃ for 8 hours, crushing by a crusher, and carrying out pre-carbonization treatment in an argon atmosphere at 500 ℃ for 2 hours; then placing the powder into a 1M NaOH solution for ultrasonic cleaning for 2 hours, then placing the powder into a 2M hydrochloric acid solution for ultrasonic cleaning for 2 hours, filtering, washing the powder with deionized water until the pH value is 7, drying the powder at 110 ℃, and then adopting an air flow pulverizer to perform pulverizing treatment to obtain carbon powder with the particle size of 3-8 mu M; adding 100g of carbon powder into N-methyl pyrrolidone, soaking for 5 hours, heating 25g of petroleum asphalt with a softening point of 200 ℃ to 220 ℃, adding 150ml of N-methyl pyrrolidone, stirring to prepare a mixed solution, adding the carbon powder adsorbed with the N-methyl pyrrolidone into the asphalt solution while stirring, carbonizing at 1300 ℃ for 2 hours in an argon atmosphere after drying, cooling to room temperature, crushing and sieving to obtain the cathode material with a core-shell structure, wherein the particle size of the core is 3-8 mu m, the spacing between 002 crystal faces is 0.372nm, the thickness of the shell is 100-500nm, and the spacing between 002 crystal faces is 0.35nm. . The negative electrode material was prepared into a button cell, and the performance thereof is shown in table 1.

Example 5

Drying 1kg of apricot shells in a vacuum drying oven at 110 ℃ for 8 hours, crushing by a crusher, and carrying out pre-carbonization treatment under argon atmosphere, wherein the temperature of the heat treatment is 500 ℃ and the time is 2 hours; then placing the powder into a 1M NaOH solution for ultrasonic cleaning for 2 hours, then placing the powder into a 2M hydrochloric acid solution for ultrasonic cleaning for 2 hours, filtering, washing the powder with deionized water until the pH value is 7, drying the powder at 110 ℃, and then adopting an air flow pulverizer to perform pulverizing treatment to obtain carbon powder with the particle size of 3-8 mu M; adding 100g of carbon powder into dimethylacetamide, soaking for 5 hours, heating 25g of petroleum asphalt with a softening point of 200 ℃ to 220 ℃, adding 150ml of dimethylacetamide, stirring to prepare a mixed solution, adding carbon powder adsorbed with N-methylpyrrolidone into the asphalt solution while stirring, carbonizing for 2 hours at 1100 ℃ in an argon atmosphere after drying, cooling to room temperature, crushing and sieving to obtain the cathode material with a core-shell structure, wherein the particle size of the core is 3-8 mu m, the interlayer spacing of 002 crystal faces is 0.38nm, the thickness of the shell is 100-500nm, and the interlayer spacing of 002 crystal faces is 0.35nm. The negative electrode material was prepared into a button cell, and the performance thereof is shown in table 1.

Example 6

Drying 1kg of walnut shell in a vacuum drying oven at 110 ℃ for 8 hours, crushing by a crusher, and carrying out pre-carbonization treatment in an argon atmosphere at 500 ℃ for 2 hours; then placing the powder into a 1M NaOH solution for ultrasonic cleaning for 2 hours, then placing the powder into a 2M hydrochloric acid solution for ultrasonic cleaning for 2 hours, filtering, washing the powder with deionized water until the pH value is 7, drying the powder at 110 ℃, and then adopting an air flow pulverizer to perform pulverizing treatment to obtain carbon powder with the particle size of 3-8 mu M; adding 100g of carbon powder into dimethylacetamide, soaking for 5 hours, heating 25g of petroleum asphalt with a softening point of 200 ℃ to 220 ℃, adding 150ml of dimethylacetamide, stirring to prepare a mixed solution, adding carbon powder adsorbed with N-methylpyrrolidone into the asphalt solution while stirring, carbonizing for 2 hours at 1100 ℃ in an argon atmosphere after drying, cooling to room temperature, crushing and sieving to obtain the cathode material with a core-shell structure, wherein the particle size of the core is 3-8 mu m, the interlayer spacing of 002 crystal faces is 0.38nm, the thickness of the shell is 100-500nm, and the interlayer spacing of 002 crystal faces is 0.35nm. The negative electrode material was prepared into a button cell, and the performance thereof is shown in table 1.

Table 1 battery performance of the anode materials prepared in each of examples and comparative examples

The results illustrate: the battery using the anode material of example 1 of the present invention had 29.8% improvement in the initial cycle coulombic efficiency and 9.4% improvement in the reversible capacity at 5C/reversible capacity at 0.1C, as compared with comparative examples 1 and 2. The charge-discharge reversible capacity was increased by 56.6% as compared with comparative example 3. Compared with comparative example 4, due to the improvement of the coating method, a compact high-order carbon layer can be coated on the surface of the hard carbon particles on the premise of not influencing the micropore structure in the hard carbon particles, so that the charge-discharge reversible capacity of the battery is improved by 30.4%, and the initial cycle coulomb efficiency is improved by 15.6%. In summary, with the negative electrode material of the present invention, high first cycle coulombic efficiency can be obtained while achieving high reversible capacity.

Claims

1. A lithium ion battery cathode material is characterized in that:

the material is a carbon material, has a core-shell structure, the particle size of the core is 3-8 mu m, and the interval between 002 crystal face layers is 0.37-0.41nm;

the thickness of the shell is 10-1000nm, and the (002) crystal plane layer spacing is 0.34-0.36nm.

2. The anode material according to claim 1, characterized in that: the battery cathode material is particles with micron-scale particle size, which are formed by tightly combining two materials of an inner core shell and an outer core shell, and the shell material is attached to the outer surface of the core.

3. A method for producing the anode material according to claim 1 or 2, characterized in that: the preparation method of the anode material is as follows,

1) Drying and crushing biomass raw materials, and performing pre-carbonization treatment for 1-3 hours at 500-800 ℃ in an inert atmosphere to obtain a product A;

2) Sequentially placing the product A into NaOH solution and acid solution for soaking, stirring and cleaning to remove silicon and metal element impurities in the raw materials, filtering, washing to be neutral, drying, and crushing by an air flow crusher to obtain carbon powder B with the particle size of 3-8 mu m;

3) And carrying out asphalt coating treatment on the carbon powder B, namely firstly soaking the carbon powder B into a solvent, taking out the carbon powder adsorbed with the solvent, heating asphalt to 210-350 ℃, adding the solvent, stirring to prepare a mixed solution, adding the carbon powder adsorbed with the solvent into the asphalt solution while stirring, drying, and carbonizing at 1100-1300 ℃ for 1-3h in an inert atmosphere to obtain the anode material.

4. A method of preparation according to claim 3, characterized in that: the biomass raw material is one or more than two of coconut shells, peach shells, apricot shells and walnut shells.

5. A method of preparation according to claim 3, characterized in that:

the concentration of the NaOH solution in the step 2) is 1-5mol/L, and the acid solution is hydrochloric acid solution, sulfuric acid solution or nitric acid solution, and the concentration is 1-5mol/L; the dipping and stirring time is 1-100h, preferably 25-50h; the temperature range during stirring is 25-70 ℃, preferably 50-70 ℃.

6. A method of preparation according to claim 3, characterized in that: the asphalt is petroleum asphalt, the softening point is 200-250 ℃, the asphalt is heated to a temperature 10-50 ℃ higher than the softening point, and the asphalt is stirred to prepare a mixed solution after adding a solvent, wherein the mass fraction of the asphalt solution is 30-50%.

7. A method of preparation according to claim 3, characterized in that: the solvent is one or more of N-methyl pyrrolidone, dimethylacetamide, hexamethyl phosphonyl triamine, hexaethyl phosphonyl triamine and diphenyl ether.

8. A method of preparation according to claim 3, characterized in that: the mass ratio of the carbon powder B to the asphalt is 6/4-8/2.

9. The utility model provides a lithium ion battery negative pole which characterized in that: the active material of the negative electrode is the negative electrode material of claim 1 or 2.

10. A lithium ion battery, characterized in that: the negative electrode of the lithium ion battery is the negative electrode of claim 9.