Negative electrode material, preparation method and application thereof, and negative electrode slurry

Abstract

The invention discloses a negative electrode material, a preparation method of the negative electrode material and application of the negative electrode material in a lithium ion battery, relates to the technical field of lithium ion battery preparation, and aims at solving the problems that an existing lithium ion battery negative electrode material is serious in volume expansion and poor in low-temperature performance. The molecular formula of the fluorescent powder is (Ba1-x-ySrxLay) (Co1-a-b-cFeaZnbYc) O3-delta, and x < lt > is greater than or equal to 0; 1, 0 < = y < lt >; 1, 0 < = alt; 1, 0 < = blt; 1, 0 < = clt; delta represents the number of oxygen vacancies, and the negative electrode material has a complete single perovskite phase without any impurity, and has excellent conductivity, good cycle stability, large specific capacity and high chemical stability as the negative electrode material of the secondary battery. The invention also provides a negative electrode slurry. The negative electrode slurry comprises the negative electrode material prepared by the preparation method of the negative electrode material.

Description

Technical Field

[0001] The present invention relates to the technical field of lithium-ion battery preparation, and more specifically, to a perovskite-type lithium-ion battery anode material, a preparation method thereof, an application thereof in a lithium-ion battery, and an anode slurry. Background Art

[0002] Perovskite materials have certain advantages in battery materials due to their structural stability, conductivity, and large specific surface area. In the ABO3-type perovskite structure, the A site is usually a larger cation (such as calcium, magnesium, etc.), while the B site is a smaller transition metal ion (such as cobalt, manganese, iron, etc.). The properties of these materials can be adjusted by changing the elements at the A and B sites.

[0003] Existing graphite anode materials have several obvious disadvantages compared with ABO3 perovskite materials. First, graphite anodes are prone to volume expansion and contraction during charge and discharge, especially during high-rate charge and discharge, resulting in capacity fade and mechanical fatigue of the material, affecting the cycle stability of the battery. Perovskite materials, on the other hand, have good structural stability and are not prone to significant volume changes even during charge and discharge, thus providing a longer cycle life. Second, the theoretical specific capacity of graphite anodes is relatively low, about 372 mAh / g, which limits the energy density of the battery and cannot meet the demand for higher capacities. In contrast, some perovskite materials, such as perovskite-type lithium titanate oxides (Li3xLa2 / 3-xTiO3, La 0.7 Sr 0.3MnO3) has a relatively high specific capacity, which can provide greater energy storage and improve the overall performance of the battery. The graphite anode also has a relatively high internal resistance during high-rate charge and discharge, resulting in a slow charging speed and limited power output, especially performing poorly in high-power applications. Due to its good electronic and ionic conductivity, perovskite materials can achieve fast charge and discharge at a relatively high rate, meeting high-power requirements. In addition to performance deficiencies, the graphite anode is also prone to capacity fade after multiple charge and discharges. Especially in high-capacity or high-rate applications, its cycling performance is poor and it is difficult to maintain stable electrochemical performance for a long time. Perovskite materials, on the other hand, have better cycling stability, can maintain the capacity and performance of the battery, and extend the service life of the battery. In addition, the graphite anode performs poorly in a low-temperature environment, and the charge and discharge efficiency drops significantly at low temperatures, which limits its application in severe cold conditions. Perovskite materials, however, can better adapt to low-temperature environments, maintain good performance, and improve the usage efficiency of the battery under different temperature conditions. Finally, the raw material sources of graphite materials mostly rely on natural resources and require a complex purification process, increasing costs and resource pressure. The raw materials of perovskite materials are relatively abundant, the production process is relatively simple, the cost is relatively low, and it has better resource sustainability and economy. In summary, although the graphite anode is widely used in lithium-ion batteries, compared with ABO3 perovskite materials, it has certain disadvantages in terms of capacity, cycling stability, charge and discharge speed, low-temperature performance, and resource sustainability. Perovskite materials, with their excellent comprehensive performance, provide a more promising alternative for improving the performance of lithium-ion batteries and promoting their development.

[0004] Currently, the application research of perovskite materials in the anode of lithium-ion batteries mainly focuses on the optimization of materials and the improvement of synthesis technology. Researchers enhance the performance of perovskite materials through different doping strategies (such as doping with manganese, cobalt, iron, etc.). For example, La 0.7 Sr 0.3 MnO3-type perovskite materials exhibit relatively high specific capacity and good cycling stability. In addition, through the design of composite materials, their electrochemical performance is further improved. Although the application of perovskite materials in the anode of lithium-ion batteries is still in the research stage, their unique advantages make them have broad application prospects. In the future, with the further optimization of the performance of perovskite materials, especially the improvement of specific capacity and conductivity, it may become an efficient and low-cost anode material. In addition, perovskite materials also show potential in other energy storage fields (such as sodium-ion batteries, solid-state batteries, etc.) and may become key materials in the next generation of energy storage devices. Summary of the Invention

[0005] Aiming at the defects of existing lithium-ion battery anode materials, such as serious volume expansion, poor cycle life, and limited low-temperature performance, one of the purposes of the present invention is to provide a perovskite-type lithium-ion battery anode material. This anode material is prepared by sol-gel method with co-doping of Sr, La and Fe, Zn, Y at the A and B sites of BaCoO 3-δ , and a series of single perovskite structure oxides (Ba 1-x-y Sr x La y )(Co 1-a-b-c Fe a Zn b Y c )O 3-δ are prepared by this method. And the X-ray (XRD) results prove that the samples after high-temperature calcination have a complete single perovskite phase and no any impurities.

[0006] To solve the above technical problems, the present invention provides the following technical solutions:

[0007] A negative electrode material, which is a high-purity cubic perovskite material synthesized by sol-gel method, and its composition molecular formula is (Ba 1-x-y Sr x La y )(Co 1-a-b-c Fe a Zn b Y c )O 3-δ , where 0≤x<1, 0≤y<1, 0≤a<1, 0≤b<1, 0≤c<1, and δ represents the number of oxygen vacancies.

[0008] Another purpose of the present invention is to provide a preparation method of the above negative electrode material, including the following steps:

[0009] (1) According to the molecular formula (Ba 1-x-y Sr x La y )(Co 1-a-b-c Fe a Zn b Y c )O 3-δ , weigh barium source, strontium source, lanthanum source, cobalt source, iron source, zinc source and yttrium source respectively according to the stoichiometric ratio and dissolve them in deionized water or pure water to obtain a mixed solution I;

[0010] (2) Dissolve the complexing agent in an alkaline solution, adjust the pH to obtain a mixed solution II;

[0011] (3) Mix the mixed solution I and the mixed solution II evenly, then add the complexing agent, mix well, and then add the alkaline solution to adjust the pH to obtain solution III;

[0012] (4) Heat and stir Solution III to obtain a gel;

[0013] (5) Dry the gel and calcine it to obtain (Ba 1-x-y Sr x La y )(Co 1-a-b-c Fe a Zn b Y c )O 3-δ negative electrode material.

[0014] Preferably, the barium source includes, but is not limited to, one or more of barium nitrate, barium chloride, and barium acetate;

[0015] The strontium source includes, but is not limited to, one or more of strontium nitrate, strontium chloride, and strontium acetate;

[0016] The lanthanum source includes, but is not limited to, one or more of lanthanum nitrate, lanthanum chloride, and lanthanum acetate;

[0017] The cobalt source includes, but is not limited to, one or more of cobalt nitrate, cobalt chloride, cobalt acetate, and cobalt sulfate;

[0018] The iron source includes, but is not limited to, one or more of iron nitrate, iron chloride, iron acetate, and ferrous oxalate;

[0019] The zinc source includes, but is not limited to, one or more of zinc nitrate, zinc chloride, zinc acetate, and zinc sulfate;

[0020] The yttrium source includes, but is not limited to, one or more of yttrium nitrate, yttrium chloride, and yttrium acetate.

[0021] Preferably, in step (1), the total concentration of the barium source, strontium source, lanthanum source, cobalt source, iron source, zinc source, and yttrium source in the mixed Solution I is 0.25 - 0.5 mol / L.

[0022] Preferably, step (2) is specifically: dissolve the complexing agent in an alkali solution according to the molar ratio of the complexing agent to the total metal ions in the mixed Solution I being 1:1, adjust the pH to 7 - 10 to obtain a mixed Solution II.

[0023] Preferably, step (3) is specifically: mix the mixed Solution I and the mixed Solution II evenly, then, according to the molar ratio of the complexing agent to the total metal ions in the mixed Solution I being 1.5 - 2:1, add the complexing agent thereto again, mix well, and then add an alkali solution to adjust the pH to 7 - 10 to obtain Solution III.

[0024] Preferably, in steps (2) and (3), the complexing agent is one or more of ethylenediaminetetraacetic acid, citric acid, oxalic acid, tartaric acid, sodium gluconate, and triethylenetetramine; the alkali solution is one of ammonia water, ethanolamine, and triethanolamine, and the concentration of the alkali solution is 11-15 mol / L; the molar volume ratio of the complexing agent to the alkali solution is 0.05 mol:50-80 mL.

[0025] Preferably, step (4) is specifically: stirring the solution III under the conditions of water bath or oil bath heating to obtain a gel; wherein, the heating temperature is 80-100 °C, and the stirring speed is 300-400 r / min.

[0026] Preferably, in step (5), the drying temperature is 300-350 °C, which can promote the rapid evaporation of water, the fluffiness of the precursor is better, which can create convenient conditions for subsequent calcination, and it is extremely easy to form a pure phase, and the drying time is 5-10 h.

[0027] Preferably, in step (5), the calcination method is specifically: calcining at 1000-1150 °C for 10-15 h, and the obtained precursor needs to be ground before calcination. During calcination, nitrogen, nitrogen-air mixed gas or direct calcination in air is required. When using nitrogen-air mixed gas as the calcination atmosphere, the volume fraction of nitrogen-air should be between 3:7 and 1:1.

[0028] The third object of the present invention is to provide an application of the negative electrode material prepared by the above-mentioned method for preparing a negative electrode material in the preparation of a lithium-ion battery.

[0029] The fourth object of the present invention is to provide a negative electrode paste, and the raw materials of the negative electrode paste include the negative electrode material (Ba[[ID= sixteen]] 1-x-y Sr x La y )(Co 1-a-b-c Fe a Zn b Y c )O 3-δ prepared by the above-mentioned method for preparing a negative electrode material.

[0030] Furthermore, the preparation method of the negative electrode paste includes the following steps:

[0031] (a) Adding a CMC negative electrode dispersant to deionized water and stirring evenly to obtain a glue solution A; wherein, the solid content of the glue solution A is 1.2-2.5%;

[0032] (b) Adding an SBR negative electrode binder to deionized water and stirring evenly to obtain a glue solution B; wherein, the solid content of the glue solution B is 35-50%;

[0033] (c) Mix the adhesive solution A and the adhesive solution B and stir evenly to form solution C;

[0034] (d) Add the conductive agent to the adhesive solution C and stir evenly to form solution D;

[0035] (e) Add the negative electrode material to solution D in 3 - 4 times. After each addition, disperse it at a high speed at a rate of 3000 ± 50 / rpm for 15 - 20 min, and control the total dispersion time within 60 min; 1-x-y Sr x La y )(Co 1-a-b-c Fe a Zn b Y c )O 3-δ The negative electrode material is added to solution D in 3 - 4 times. After each addition, disperse it at a high speed at a rate of 3000 ± 50 / rpm for 15 - 20 min, and control the total dispersion time within 60 min;

[0036] (f) After step (e) is completed, place the solution under a vacuum condition of -85 kPa and carry out high-speed stirring and dispersion treatment for 4 h, and finally add deionized water to adjust to form a negative electrode slurry with a viscosity adjusted to 4000 - 8000 mPa·s and a solid content adjusted to 40 - 50%.

[0037] Furthermore, in step (a), the dispersion rate is 2000 ± 50 / rpm to 2500 ± 50 / rpm, the stirring rate is 20 ± 2 / rpm to 50 ± 2 / rpm, and the stirring time is 3 - 5 h; in step (b), the dispersion rate is 1500 ± 50 / rpm to 2500 ± 50 / rpm, the stirring rate is 20 ± 2 / rpm to 50 ± 2 / rpm; in step (c), the dispersion rate is 2000 ± 50 / rpm to 2500 ± 50 / rpm, the stirring rate is 20 ± 2 / rpm to 50 ± 2 / rpm, the stirring time is 1 - 3 h, and the vacuum degree is -75 to -100 kPa; in step (d), the dispersion rate is 2000 ± 50 / rpm to 2500 ± 50 / rpm, the stirring rate is 20 ± 2 / rpm to 50 ± 2 / rpm, the stirring time is 1 - 3 h, and the vacuum degree is -75 to -100 kPa; in step (e), the dispersion rate is 2000 ± 50 / rpm to 25OO ± 50 / rpm, the stirring rate is 20 ± 2 / rpm to 50 ± 2 / rpm, the stirring time is 4 - 8 h, and the stirring temperature is 25 °C. In step (f), the dispersion rate is 2000 ± 50 / rpm to 2500 ± 50 / rpm, the stirring rate is 20 ± 2 / rpm to 50 ± 2 / rpm, the stirring time is 4 - 8 h, and the stirring temperature is 25 °C.

[0038] Furthermore, the conductive agent includes single-walled carbon nanotube slurry, multi-walled carbon nanotube slurry or carbon black. The solid content of the conductive agent is 0.3% - 0.�%, and the addition amount is 0.05 - 1.5% of the adhesive solution C.

[0039] Further, when the conductive agent is a single-walled carbon nanotube slurry, its addition amount is 0.06% of the adhesive C, the solid content is 0.5%, the dispersion rate is 2600 ± 50 / rpm, the stirring rate is 25 ± 2 / rpm, the stirring time is 1 h, and the vacuum degree is -85 kPa; when the conductive agent is a multi-walled carbon nanotube slurry, its addition amount is 0.08% of the adhesive C, the solid content is 0.7%, the dispersion rate is 2300 ± 50 / rpm, the stirring rate is 40 ± 2 / rpm, the stirring time is 1.5 h, and the vacuum degree is -85 kPa; when the conductive agent is carbon black, its addition amount is 0.5% of the adhesive C, the dispersion rate is 2700 ± 50 / rpm, the stirring rate is 50 ± 2 / rpm, the stirring time is 3 h, and the vacuum degree is -90 kPa.

[0040] Furthermore, in step (a), the stirring rate is 25 ± 2 / rpm, the dispersion rate is 2400 ± 50 / rpm, the stirring time is 3 h, and the solid content of the adhesive A is 1.5%.

[0041] Furthermore, in step (b), the stirring rate is 20 ± 2 / rpm, the dispersion rate is 2200 ± 50 / rpm, the stirring time is 3 h, and the solid content of the adhesive B is preferably 40%.

[0042] Furthermore, in step (c), the stirring rate is 30 ± 2 / rpm, the dispersion rate is 2500 ± 50 / rpm, the stirring time is 1.5 h, and the vacuum degree is -85 kPa.

[0043] Furthermore, in step (f), deionized water is added to adjust the viscosity of the formed negative electrode slurry to 6000 mPa·s and the solid content to 45%.

[0044] The obtained final slurry is successively subjected to coating, pole piece baking, sheet making, rolling, slitting, winding, top and side sealing, baking, liquid injection, sealing, formation, secondary sealing, and grading to form a soft-pack lithium-ion battery.

[0045] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0046] 1. The present invention uses the sol-gel method to perform co-doping of Sr, La and Fe, Zn, Y on the A and B sites of BaCoO 3-δ respectively, and a series of single perovskite structure oxides (Ba 1-x-y Sr x La y )(Co 1-a-b-c Fe a Zn b Y c )O 3-δ, and the X-ray diffraction (XRD) results prove that the sample after high-temperature calcination has a complete single perovskite phase and no impurities, and it has excellent electrical conductivity, good cycle stability, large specific capacity and high chemical stability as the anode material of lithium-ion batteries.

[0047] 2. The present invention uses (Ba 1-x-y Sr x La y )(Co 1-a-b-c Fe a Zn b Y c )O 3-δ as the anode material of lithium-ion batteries. The electrochemical test results of the lithium-ion batteries show that (Ba 1-x-y Sr x La y )(Co 1-a-b-c Fe a Zn b Y c )O 3-δ After long-term cycling, the phase structure of the material is intact and there is no obvious swelling, indicating that the anode material has good thermodynamic stability and safety performance and can maintain good electrochemical performance at 20-80 °C; at the same time, the electrochemical rate performance and long-term cycle stability test results show that the perovskite-type anode material has considerable capacity and good long-term electrochemical stability performance, meeting the requirements as the anode material of lithium-ion batteries. Description of the Drawings

[0048] Figure 1 is the scanning electron microscope (SEM) image of the perovskite-type anode material of lithium-ion batteries prepared in Example 1 of the present invention;

[0049] Figure 2 is the X-ray (XRD) image of the perovskite-type anode material of lithium-ion batteries prepared in Example 1 of the present invention;

[0050] Figure 3 is the rate performance test result image of the button cell prepared in Example 2 of the present invention;

[0051] Figure 4 is the long-term stability performance test result image of the button cell prepared in Example 2 of the present invention. Detailed Embodiments

[0052] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be described clearly and completely below. Obviously, the described embodiments are some, but not all, of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts fall within the scope of protection of the present invention.

[0053] For the test materials, reagents, etc. used in the following embodiments, unless otherwise specified, they can all be obtained through commercial channels. For those not specified with specific techniques or conditions in the embodiments, they can all be carried out according to the techniques or conditions described in the literature in this field or according to the product specifications.

[0054] Example 1

[0055] (Ba 0.9 Sr 0.05 La 0.05 )(Co 0.4 Fe 0.4 Zn 0.1 Y 0.1 )O 3-δ The synthesis method includes the following steps:

[0056] (1) According to the chemical formula (Ba 0.9 Sr 0.05 La 0.05 )(Co 0.4 Fe 0.4 Zn 0.1 Y 0.1 )O 3-δ , weigh barium nitrate, strontium nitrate, lanthanum nitrate, cobalt nitrate, iron nitrate, zinc nitrate, and yttrium nitrate according to the stoichiometric ratio and dissolve them in 200 mL of deionized water, stir evenly to obtain mixed solution I; the total concentration of barium nitrate, strontium nitrate, lanthanum nitrate, cobalt nitrate, iron nitrate, zinc nitrate, and yttrium nitrate in the solution is 0.25 mol / L;

[0057] (2) Weigh ethylenediaminetetraacetic acid according to the molar ratio of 1:1 of ethylenediaminetetraacetic acid to metal ions (barium, strontium, lanthanum, cobalt, iron, zinc, and yttrium ions), dissolve it in 50 mL of ammonia water (concentration 13 mol / L), and stir evenly to obtain solution II;

[0058] (3) After stirring mixed solution I and solution II evenly, add citric acid according to the total molar ratio of citric acid to metal ions of 1.5:1 and continue stirring, and adjust the pH value to 7 with ammonia water to prepare a sol;

[0059] (4) Place the sol in an oil bath pot, stir at 95 °C (until the water has completely evaporated) to make it into a gel;

[0060] (5) Dry the gel at 300 °C for 10 h to obtain a fluffy precursor powder. Grind the precursor powder in a mortar, and then calcine the ground product in air at 1000 °C for 5 h to obtain the perovskite-type anode material for lithium-ion batteries (Ba 0.9 Sr 0.5 La 0.5 )(Co 0.4 Fe 0.4 Zn 0.1 Y 0.1 )O 3-δ . The scanning electron microscope (SEM) image of this anode material is as shown in Figure 1 .

[0061] Perform X-ray (XRD) phase analysis on (Ba 0.9 Sr 0.5 La 0.5 )(Co 0.4 Fe 0.4 Zn 0.1 Y 0.1 )O 3-δ . The test results show that the sample is a pure single perovskite material, and the XRD results are as shown in Figure 2 .

[0062] Example 2

[0063] Prepare a (LiCoO2 / (EC+PC+EMC+LiPF6) / (Ba 1-x-y Sr x La y )(Co 1-a-b-c Fe a Zn b Y c )O 3-δ lithium-ion battery.

[0064] Positive electrode sheet: Use a commercial positive electrode sheet, which contains one of lithium cobalt oxide (LCO), lithium iron phosphate, nickel cobalt manganese ternary (NCM), and nickel cobalt aluminum ternary (NCA);

[0065] Negative electrode sheet: Use the (Ba 0.9 Sr 0.05 La 0.05 )(Co 0.4 Fe 0.4 Zn 0.1 Y 0.1 )O 3-δThe negative electrode material was directly cut into electrode sheets with a diameter of 12 mm. Celgard 2400 was used as the separator. Lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) with a concentration of 1 mol L-1 dissolved in a mixed solvent of 1,3-dioxolane (DOL) and dimethoxyethane (DME) with a volume ratio of 1:1 was used, and 2% of LiNO3 additive was added as the electrolyte. The amount of the electrolyte was 60 μL. A CR-2032 coin cell was assembled in a glove box filled with argon with the oxygen and moisture content less than 0.01 ppm. Subsequently, it was cycled 5 times at a current density of 0.05 mA cm-2 between 0.01 - 3 V to remove the contaminants on the electrode surface and form a stable solid electrolyte interface (SEI). Then, metallic lithium was deposited at a current density of 0.5 mA cm-2 to form a Li@MnOx@LIG-a lithium negative electrode. After that, the coin cell was disassembled, the lithium negative electrode was taken out, washed with dimethoxyethane (DME) and dried for standby;

[0066] Battery assembly steps: The (Ba 0.9 Sr 0.05 La 0.05 )(Co 0.4 Fe 0.4 Zn 0.1 Y 0.1 )O 3-δ The negative electrode sheet of the sample was paired with a commercial positive electrode sheet. Glass Microfiber Filters (with a diameter of 19 mm) was used as the separator. LiPF6 with a concentration of 1 mol L-1 dissolved in a mixed solvent of ethylene carbonate (EC) and diethyl carbonate (DEC) with a volume ratio of 1:1 was used as the electrolyte. The amount of the electrolyte was 60 μL. A CR-2032 coin cell was assembled in a glove box filled with argon with the oxygen and moisture content less than 0.01 ppm.

[0067] The rate performance test results of the CR-2032 coin cell are as Figure 3 shown.

[0068] The long-term stability performance test results of the CR-2032 coin cell are as Figure 4 shown.

[0069] The (Ba 0.9 Sr 0.5 La 0.5 )(Co 0.4 Fe 0.4 Zn 0.1 Y 0.1 )O 3-δPerovskite materials have a certain lithium-ion intercalation / deintercalation capacity, which is very close to that of traditional graphite anode materials. After optimization, they can be used as anode materials for lithium-ion batteries. Compared with other anode materials, (Ba 0.9 Sr 0.5 La 0.5 )(Co 0.4 Fe 0.4 Zn 0.1 Y 0.1 )O 3-δ exhibits good cycle stability and can maintain a stable capacity during long-term cyclic charge and discharge processes. This enables (Ba 0.9 Sr 0.5 La 0.5 )(Co 0.4 Fe 0.4 Zn 0.1 Y 0.1 )O 3-δ to have the potential to become a high-performance and long-life anode material. (Ba 0.9 Sr 0.5 La 0.5 )(Co 0.4 Fe 0.4 Zn 0.1 Y 0.1 )O 3-δ Perovskite materials have high thermodynamic thermal stability and can maintain good electrochemical performance at 20 - 80 °C, which makes this type of perovskite material suitable for high-temperature working scenarios of lithium-ion batteries.

[0070] Example 3

[0071] Taking the preparation of 10 kg of anode slurry as an example:

[0072] (a) Add 36 g of CMC anode dispersant to 3 kg of deionized water and stir evenly to obtain adhesive solution A; among them, the solid content of adhesive solution A is 1.2%, the stirring rate is 30 rpm / min, the dispersion rate is 2200 rpm / min, the stirring time is 3 h, the temperature is 25 °C, and the vacuum degree is maintained at -85 KPa;

[0073] (b) Add 1.2 kg of SBR anode binder to 3 kg of deionized water and stir evenly to obtain adhesive solution B; among them, the solid content of adhesive solution B is 40%, the stirring rate is 20 rpm / min, the dispersion rate is 1500 rpm / min, the stirring time is 3 h, the temperature is 25 °C, and the vacuum degree is maintained at -85 KPa;

[0074] (c) Mix glue solution A and glue solution B and stir evenly to form glue solution C. Among them, the solid content of glue solution C is 20.6%, the stirring rate is 20 rpm / min, the dispersion rate is 2000 rpm / min, the stirring time is 2 h, the temperature is 25 °C, and the vacuum degree is maintained at -85 KPa.

[0075] (d) Add 58 g of single-walled carbon nanotube conductive paste with a solid content of 0.5% to glue solution C and stir evenly to form solution D. Among them, the solid content of solution D is 20.41%, the stirring rate is 20 rpm / min, the dispersion rate is 2000 rpm / min, the stirring time is 1.5 h, the temperature is 25 °C, and the vacuum degree is maintained at -85 KPa.

[0076] (e) Add 3 kg of the negative electrode material prepared in Example 1 (Ba 0.9 Sr 0.5 La 0.5 )(Co 0.4 Fe 0.4 Zn 0.1 Y 0.1 )O 3-δ Add the negative electrode material to solution D in 3 times. Among them, for the first time, add 1 kg of negative electrode powder, and with a stirring rate of 20 rpm / min and a dispersion rate of 2600 rpm / min, make the slurry mix evenly. The mixing time is 20 min, the temperature is 25 °C, and the vacuum degree is maintained at -85 KPa. For the second time, add 1 kg of negative electrode powder, and with a stirring rate of 20 rpm / min and a dispersion rate of 2800 rpm / min, make the slurry mix evenly. The mixing time is 20 min, the temperature is 25 °C, and the vacuum degree is maintained at -8 5 KPa. For the third time, add 1 kg of negative electrode powder, and with a stirring rate of 20 rpm / min and a dispersion rate of 3000 rpm / min, make the slurry mix evenly. The mixing time is 20 min, the temperature is 25 °C, and the vacuum degree is maintained at -85 KPa. The total dispersion time is 60 min, and the solid content of the slurry at this time is 46.77%.

[0077] (f) After step (e) is completed, place the slurry under a vacuum condition of -75 kPa and carry out high-speed stirring and dispersion treatment for 6 h. The dispersion rate is 2200 rpm / min, and the stirring rate is 30 rpm / min. Finally, add 360 g of deionized water to adjust to form a negative electrode slurry with a viscosity adjusted to 6000 mPa·s and a solid content adjusted to 45%.

[0078] The obtained final slurry is successively subjected to coating, pole piece baking, sheet making, rolling, slitting, winding, top and side sealing, baking, liquid injection, sealing, formation, second sealing, and grading to form a soft-pack lithium-ion battery.

[0079] By comparing the capacity retention rates of the lithium cobalt oxide cathode of Sample 1, the electrolyte of Sample 2 (LiPF6 - 1.2 mol / L, EC - 25%, EMC - 45%, DMC - 30%, FEC - 2%, LiFSI - 0.2 mol / L), and the (Ba 0.9 Sr 0.5 La 0.5 )(Co 0.4 Fe 0.4 Zn 0.1 Y 0.1 )O 3-δ negative soft - pack lithium - ion battery (Sample 3) at different rates, the comparison results are shown in Table 1.

[0080] Table 1 Capacity retention rates at different rates

[0081]

[0082] The embodiments disclosed in the present invention are preferred embodiments, but not limited thereto. Those of ordinary skill in the art can easily understand the spirit of the present invention based on the above embodiments and make different extensions and changes. However, as long as they do not depart from the spirit of the present invention, they are within the protection scope of the present invention.

Claims

1. A negative electrode material, characterized in that: The negative electrode material is a high-purity cubic perovskite material synthesized by the sol-gel method, and its composition molecular formula is (Ba 1-x-y Sr x La y )(Co 1-a-b-c Fe a Zn b Y c )O 3-δ , where 0 ≤ x < 1, 0 ≤ y < 1, 0 ≤ a < 1, 0 ≤ b < 1, 0 ≤ c < 1, and δ represents the number of oxygen vacancies.

2. A method for preparing the negative electrode material according to claim 1, characterized in that, It includes the following steps: (1) According to the molecular formula (Ba 1-x-y Sr x La y )(Co 1-a-b-c Fe a Zn b Y c )O 3-δ , respectively weigh the barium source, strontium source, lanthanum source, cobalt source, iron source, zinc source and yttrium source according to the stoichiometric ratio and dissolve them in deionized water or pure water to obtain mixed solution I; (2) Dissolve the complexing agent in an alkaline solution, adjust the pH to obtain a mixed solution II; (3) Mix the mixed solution I and the mixed solution II evenly, then add the complexing agent, and after mixing evenly, add the alkaline solution to adjust the pH to obtain a solution III; (4) Heat and stir the solution III to obtain a gel; (5) Dry the gel and obtain (Ba 1-x-y Sr x La y )(Co 1-a-b-c Fe a Zn b Y c )O 3-δ Negative electrode material.

3. The preparation method of the negative electrode material according to claim 2, wherein: In step (1), the barium source includes but is not limited to one or more of barium nitrate, barium chloride, and barium acetate; the strontium source includes but is not limited to one or more of strontium nitrate, strontium chloride, and strontium acetate; the lanthanum source includes but is not limited to one or more of lanthanum nitrate, lanthanum chloride, and lanthanum acetate; the cobalt source includes but is not limited to one or more of cobalt nitrate, cobalt chloride, cobalt acetate, and cobalt sulfate; the iron source includes but is not limited to one or more of iron nitrate, iron chloride, iron acetate, and ferrous oxalate; the zinc source includes but is not limited to one or more of zinc nitrate, zinc chloride, zinc acetate, and zinc sulfate; the yttrium source includes but is not limited to one or more of yttrium nitrate, yttrium chloride, and yttrium acetate.

4. The method for preparing the negative electrode material according to claim 2, wherein: In step (1), the total concentration of the barium source, strontium source, lanthanum source, cobalt source, iron source, zinc source, and yttrium source in the mixed solution I is 0.25 - 0.5 mol / L.

5. The preparation method of the negative electrode material according to claim 2, wherein, Step (2) is specifically: dissolve the complexing agent in the alkaline solution according to the molar ratio of the complexing agent to the total metal ions in the mixed solution I being 1:1, and adjust the pH to 7 - 10 to obtain a mixed solution II.

6. The preparation method of the negative electrode material according to claim 5, characterized in that, Step (3) is specifically: mix the mixed solution I and the mixed solution II evenly, then add the complexing agent according to the molar ratio of the complexing agent to the total metal ions in the mixed solution I being 1.5 - 2:1, and after mixing evenly, add the alkaline solution to adjust the pH to 7 - 10 to obtain a solution III.

7. The method for preparing the negative electrode material according to claim 6, characterized in that: In steps (2) and (3), the complexing agent is one or more of ethylenediaminetetraacetic acid, citric acid, oxalic acid, tartaric acid, sodium gluconate, and triethylenetetramine; the alkaline solution is one of ammonia water, ethanolamine, and triethanolamine, and the concentration of the alkaline solution is 11 - 15 mol / L; the molar volume ratio of the complexing agent to the alkaline solution is 0.05 mol:50 - 80 mL.

8. The method for preparing the negative electrode material according to claim 2, wherein Step (4) is specifically: stir the solution III under the condition of water bath or oil bath heating to obtain a gel; wherein, the heating temperature is 80 - 100 °C and the stirring speed is 300 - 400 r / min.

9. The preparation method of the negative electrode material according to claim 2, characterized in that: In step (5), the drying temperature is 300 - 350 °C and the drying time is 5 - 10 h.

10. The method for preparing the negative electrode material according to claim 2, characterized in that, In step (5), the calcination method is specifically: calcine at 1000 - 1150 °C for 10 - 15 h, and it is necessary to grind the obtained precursor before calcination, and nitrogen, nitrogen - air mixed gas or directly air can be introduced during calcination.

11. Application of a negative electrode material prepared by the preparation method of the negative electrode material according to any one of claims 2 - 10 in the preparation of a lithium - ion battery.

12. A negative electrode paste, characterized in that, The raw materials of the negative electrode paste include the negative electrode material prepared by the preparation method of the negative electrode material described in any one of 2-10 (Ba 1-x-y Sr x La y )(Co 1-a-b-c Fe a Zn b Y c )O 3-δ Negative electrode material.

13. The negative electrode paste according to claim 12, wherein The preparation method of the negative electrode slurry includes the following steps: (a) Add the CMC negative electrode dispersant to deionized water and stir evenly to obtain a glue solution A; wherein, the solid content of the glue solution A is 1.2 - 2.5%; (b) Add the SBR negative electrode binder to deionized water and stir evenly to obtain adhesive solution B; wherein, the solid content of adhesive solution B is 35 - 50%. (c) Mix adhesive solution A and adhesive solution B and stir evenly to form solution C. (d) Add the conductive agent to solution C and stir evenly to form solution D. (e) Add (Ba 1-x-y Sr x La y )(Co 1-a-b-c Fe a Zn b Y c )O 3-δ The negative electrode material is added to solution D in 3 - 4 portions. After each addition, it is dispersed at a high speed at a rate of 3000 ± 50 / rpm for 15 - 20 min, and the total dispersion time is controlled within 60 min; (f) After step (e) ends, place the solution under a vacuum condition of -85 kPa and perform high-speed stirring and dispersion treatment for 4 h, and finally add deionized water to adjust the viscosity to 4000 - 8000 mPa·s and the solid content to 40 - 50% to form the negative electrode slurry.

14. The negative electrode slurry according to claim 13, wherein: In step (a), the dispersion rate is 2000 ± 50 / rpm to 2500 ± 50 / rpm, the stirring rate is 20 ± 2 / rpm to 50 ± 2 / rpm, and the stirring time is 3 - 5 h. In step (b), the dispersion rate is 2000 ± 50 / rpm to 2500 ± 50 / rpm, the stirring rate is 20 ± 2 / rpm to 50 ± 2 / rpm. In step (c), the dispersion rate is 2000 ± 50 / rpm to 2500 ± 50 / rpm, the stirring rate is 20 ± 2 / rpm to 50 ± 2 / rpm, the stirring time is 1 - 3 h, and the vacuum degree is -75 to -100 kPa. In step (d), the dispersion rate is 2000 ± 50 / rpm to 2500 ± 50 / rpm, the stirring rate is 20 ± 2 / rpm to 50 ± 2 / rpm, the stirring time is 1 - 3 h, and the vacuum degree is -75 to -100 kPa. In step (e), the dispersion rate is 2000 ± 50 / rpm to 2500 ± 50 / rpm, the stirring rate is 20 ± 2 / rpm to 50 ± 2 / rpm, the stirring time is 4 - 8 h, and the stirring temperature is 25°C. In step (f), the dispersion rate is 2000 ± 50 / rpm to 2500 ± 50 / rpm, the stirring rate is 20 ± 2 / rpm to 50 ± 2 / rpm, the stirring time is 4 - 8 h, and the stirring temperature is 25°C.

15. The negative electrode paste according to claim 14, wherein: The conductive agent includes single-walled carbon nanotube slurry, multi-walled carbon nanotube slurry or carbon black, the solid content of the conductive agent is 0.3 - 0.8%, and the addition amount is 0.05 - 1.5% of solution C.

16. The negative electrode slurry according to claim 15, wherein: When the conductive agent is single-walled carbon nanotube slurry, its addition amount is 0.06% of solution C, the solid content is 0.5%, the dispersion rate is 2600 ± 50 / rpm, the stirring rate is 25 ± 2 / rpm, the stirring time is 1 h, and the vacuum degree is -85 kPa. When the conductive agent is multi-walled carbon nanotube slurry, its addition amount is 0.08% of solution C, the solid content is 0.7%, the dispersion rate is 2300 ± 50 / rpm, the stirring rate is 40 ± 2 / rpm, the stirring time is 1.5 h, and the vacuum degree is -85 kPa. When the conductive agent is carbon black, its addition amount is 0.5% of the adhesive C, the dispersion rate is 2700 ± 50 / rpm, the stirring rate is 50 ± 2 / rpm, the stirring time is 3 h, and the vacuum degree is -90 kpa.

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