Battery, preparation method thereof and electric equipment

Abstract

The invention provides a battery, a preparation method thereof and electric equipment. The battery provided by the invention comprises a positive plate and a negative plate, the positive plate comprises a positive active material and a lithium supplement agent; the negative plate comprises a negative active material; and the battery meets the condition that Aanode.CLi is greater than or equal to 0.00005. S and less than or equal to 0.03. S. When meeting the conditions, the battery disclosed by the invention has relatively good quick charge performance and relatively long cycle life.

Description

Technical Field

[0001] This invention relates to the field of battery technology, and in particular to a battery, its preparation method, and an electrical device thereof. Background Technology

[0002] Lithium-ion batteries are widely used in electric vehicles, consumer electronics, and energy storage systems due to their high energy density, long cycle life, and environmental friendliness. With the increasing frequency of lithium-ion battery use, the development of fast-charging technology has received widespread attention.

[0003] However, several issues hinder the development of fast-charging technology in lithium-ion batteries during current manufacturing processes. After fast charging, traditional lithium batteries experience lithium plating, which further reduces the lithium source in the battery system, affecting cycle performance. Furthermore, the continuous construction of the solid electrolyte interphase (SEI) film also consumes lithium ions, exacerbating the lithium deficiency state. Lithium replenishment technology can alleviate these problems, but due to the complexity of the battery system, the amount of positive electrode lithium replenisher is often difficult to precisely control. Insufficient positive electrode lithium replenisher fails to effectively solve the lithium deficiency problem; excessive lithium replenishment leads to excessively high internal lithium content, causing battery structural instability and safety issues.

[0004] Therefore, there is an urgent need for a battery that can achieve precise lithium replenishment while ensuring safe use, and can balance good fast charging performance, high cycle life and safety performance. Summary of the Invention

[0005] This invention provides a battery that can achieve precise lithium replenishment while also having good fast charging performance, high cycle life, and safety performance.

[0006] This invention provides a method for preparing a battery, which can produce a battery with good fast-charging performance, high cycle life and safety performance.

[0007] This invention provides an electrical device that enables rapid charging and has a long service life and high safety.

[0008] The present invention provides a battery comprising a positive electrode and a negative electrode; the positive electrode comprises a positive electrode active material and a lithium replenishing agent;

[0009] The negative electrode sheet includes a negative electrode active material;

[0010] The battery satisfies:

[0011] 0.00005·S≤A anode ·C Li ≤0.03·S Formula I

[0012] Among them, A anode The electrochemical active area of ​​the negative electrode active material is expressed in meters (m²). 2 / g calculation;

[0013] C Li The mass ratio of the lithium replenishing agent to the positive electrode active material;

[0014] S is the specific surface area of ​​the negative electrode active material, in m². 2 / g calculation.

[0015] The battery described above, wherein the battery satisfies:

[0016] 0.0005·S≤A anode ·C Li ≤0.015·S

[0017] The battery as described above, wherein A anode ≤2m 2 / g;

[0018] And / or, C Li The percentage is 0.01% to 5%.

[0019] And / or, S≤3m 2 / g.

[0020] The battery as described above, wherein A anode The range is 0.5 to 1.5 m. 2 / g;

[0021] And / or, C Li It ranges from 0.05% to 0.2%.

[0022] And / or, S is 0.5–1.5m 2 / g.

[0023] In the battery described above, the positive electrode active material includes one or more of lithium cobalt oxide, lithium manganese oxide, lithium iron phosphate, and ternary positive electrode materials;

[0024] And / or, the lithium supplement includes one or more of lithium carbonate, lithium hydroxide, lithium oxalate, lithium fluoride, lithium acetate, lithium ferrite, and lithium nickelate.

[0025] In the battery described above, the negative electrode active material includes a coating layer and a core, wherein the coating layer covers at least a portion of the core.

[0026] The coating layer includes one or more of metal oxides, carbon-based materials, polymers, and lithium salts;

[0027] The core comprises one or more of graphite, lithium titanate, and silicon-carbon composite materials.

[0028] In the battery described above, the negative electrode active material comprises one or more of the following: graphite oxide material obtained through oxidation treatment, lithium titanate material, and silicon-carbon oxide composite material. In the battery described above, the negative electrode active material is prepared by a method comprising the following steps:

[0029] The negative electrode material is oxidized using an oxidizing agent to obtain the negative electrode active material;

[0030] The oxidizing agent includes one or more of oxygen, nitric acid, sulfuric acid, and potassium permanganate;

[0031] The negative electrode material includes one or more of graphite, lithium titanate, and silicon-carbon composite materials.

[0032] The battery manufacturing method described above includes the following steps:

[0033] A positive electrode sheet is obtained by coating a positive electrode slurry, including a positive electrode active material and a lithium supplement, onto a positive electrode current collector.

[0034] A negative electrode sheet is obtained by coating a negative electrode slurry containing a negative electrode active material onto a negative electrode current collector.

[0035] The battery is obtained by assembling the positive electrode, negative electrode, and separator.

[0036] The present invention also provides an electrical device, wherein the device includes the battery as described above.

[0037] The battery provided in this invention achieves precise control of the amount of lithium replenishing agent based on the electrochemical active area and specific surface area of ​​the negative electrode active material in the negative electrode sheet. This not only effectively replenishes lithium in the battery and optimizes the lithium ion insertion / extraction kinetics inside the battery, but also avoids the risk of lithium plating. Therefore, the battery can have better fast charging performance, longer cycle life, and higher safety performance. Attached Figure Description

[0038] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with the invention and, together with the description, serve to explain the principles of the invention.

[0039] Figure 1 A schematic diagram of a pouch battery provided in an embodiment of the present invention;

[0040] Figure 2 This is a schematic diagram of the fast charging performance (SOC-thickness curve) of the battery provided in Embodiment 3 and Comparative Example 1 of the present invention.

[0041] Explanation of reference numerals in the attached figures:

[0042] 1: Positive electrode;

[0043] 2: Negative electrode.

[0044] The accompanying drawings have illustrated specific embodiments of the invention, which will be described in more detail below. These drawings and descriptions are not intended to limit the scope of the invention in any way, but rather to illustrate the concept of the invention to those skilled in the art through reference to particular embodiments. Detailed Implementation

[0045] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions in the embodiments of this invention will be clearly and completely described below in conjunction with the embodiments of this invention. Obviously, the described embodiments are only some embodiments of this invention, not all embodiments. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0046] Lithium-ion batteries are characterized by high energy density, long cycle life, and environmental friendliness. However, current traditional lithium-ion battery systems struggle to meet the demands of fast-charging technology. Fast charging can lead to uneven lithium-ion deposition on the negative electrode surface, forming lithium dendrites. This reduces the internal lithium source, thereby decreasing the battery's cycle life. While lithium replenishment agents can mitigate these issues to some extent, their dosage is difficult to control precisely, potentially resulting in insufficient or excessive lithium replenishment, which in turn affects the battery's cycle life and safety performance.

[0047] Through long-term research, the inventors discovered that the electrochemical active area and specific surface area of ​​the negative electrode active material in lithium-ion batteries are closely related to the lithium-ion insertion / extraction kinetics, thus having a more direct impact on the battery's fast-charging performance and cycle performance. Therefore, using the electrochemical active area and specific surface area as evaluation parameters to more objectively and meticulously consider the actual amount of lithium replenishment agent missing in current batteries is beneficial for precisely controlling the amount of lithium replenishment agent used in the lithium-ion battery manufacturing process, thereby balancing the battery's fast-charging performance, cycle life, and safety performance.

[0048] Based on this, the present invention provides a battery, including a positive electrode and a negative electrode; the positive electrode includes a positive electrode active material and a lithium replenishing agent;

[0049] The negative electrode sheet includes the negative electrode active material;

[0050] The battery meets the following requirements:

[0051] 0.00005·S≤A anode ·C Li ≤0.03·S Formula I

[0052] Among them, Aanode The electrochemical active area of ​​the negative electrode active material is expressed in meters (m²). 2 / g calculation;

[0053] C Li This refers to the mass ratio of lithium supplement to positive electrode active material.

[0054] S is the specific surface area of ​​the negative electrode active material, in m². 2 / g calculation.

[0055] Figure 1 This is a schematic diagram of a soft-pack battery provided in an embodiment of the present invention. The positive electrode tab 1 is connected to the positive electrode plate inside the battery, and the negative electrode tab 2 is connected to the negative electrode plate inside the battery.

[0056] Specifically, the electrochemical active area of ​​the negative electrode active material refers to the surface area of ​​the negative electrode active material that actually participates in the electrochemical reaction. It is one of the important parameters for evaluating the electrochemical performance of the negative electrode active material and directly affects the battery cycle life. It should be clarified that the battery in this embodiment of the invention satisfies A. anode ≤S, meaning the electrochemical active area of ​​the negative electrode active material of the battery is less than or equal to the specific surface area of ​​the negative electrode active material of the battery.

[0057] For negative electrode active materials, their electrochemical active area A anode Increasing the specific surface area (S) of the negative electrode active material can directly improve the lithium-ion insertion / extraction rate, reduce polarization effects, and lower the risk of lithium dendrite formation, thereby improving the battery's fast-charging performance. However, an excessively large electrochemical active area also means that there are more lithium-ion reaction sites in the negative electrode active material, which can lead to an increase in side reactions between the electrolyte and the negative electrode active material (such as electrolyte decomposition and excessive growth of the solid electrolyte interphase (SEI) film). This accelerates electrolyte consumption, degrades cycle and storage life, and can easily cause safety issues. In addition, an excessively large specific surface area (S) of the negative electrode active material increases the probability of side reactions inside the battery, affecting its safety performance; conversely, an excessively small specific surface area results in insufficient lithium-ion insertion sites on the surface of the negative electrode active material, leading to a decrease in the battery's fast-charging performance.

[0058] Although the positive electrode lithium supplement C LiThe addition of lithium ions ensures sufficient lithium-ion supply to the cathode material during fast charging, improves lithium dendrite formation, and replenishes active lithium lost due to side reactions, lithium dendrite formation, and SEI film formation, thereby extending cycle life. However, excessive lithium ions can cause internal heat generation, leading to increased internal battery temperature and accelerating battery wear and aging. Furthermore, excessive lithium ions can generate more gas, increasing internal battery pressure and potentially causing serious safety issues such as leakage or explosion. In this embodiment of the invention, by ensuring that the product of the electrochemical active area of ​​the negative electrode active material and the mass ratio of the lithium ion in the positive electrode active material and the lithium ion in the lithium ion satisfies the above conditions, not only can the fast charging performance of the battery be improved, but the battery can also have a longer cycle life and higher safety performance.

[0059] The inventors analyzed that the battery provided in the embodiments of the present invention has better fast-charging performance, cycle life, and safety performance under the above conditions because: First, the higher electrochemical active area and specific surface area provide more insertion / extraction sites and transport paths for lithium ions, thereby promoting the ion transport rate inside the battery, which is crucial for improving the battery's fast-charging performance. However, when the electrochemical active area is too high, it may also lead to an increase in side reactions between the electrolyte and electrode materials, which may accelerate the formation and decomposition of the SEI film, thus affecting the battery's safety performance and cycle life. Based on this, although appropriately adding a positive electrode lithium replenisher can meet the fast-charging requirements and effectively compensate for irreversible lithium loss during the first charging process and lithium source loss due to side reactions, improving the battery's cycle life, the electrochemical active area A of the negative electrode active material in the battery... anode The specific surface area S also determines the upper limit of lithium-ion sites. Excessive lithium replenishment can lead to lithium plating, causing battery safety issues. Based on the relationship shown in Formula I, this embodiment of the invention uses the electrochemical active area and specific surface area as a benchmark to determine the actual lithium requirement of the battery while ensuring fast charging, cycling, and safety performance. By introducing a precisely measured amount of lithium replenishment into the battery, the lithium-ion demand during fast charging and cycling is ensured, mitigating lithium-ion consumption, without introducing excessive lithium-ions and causing lithium plating. Therefore, the battery of this embodiment of the invention has good fast charging performance, long cycle life, and high safety.

[0060] In some embodiments, the battery includes a positive electrode, a negative electrode, an electrolyte, and a separator. The positive electrode includes a positive active material layer and a positive current collector. The positive active material layer is disposed on at least one side surface of the positive current collector. The positive active material layer includes a positive active material and a lithium replenishing agent.

[0061] The negative electrode sheet includes a negative electrode active material layer and a negative electrode current collector. The negative electrode active material layer is disposed on at least one side surface of the negative electrode current collector, and the negative electrode active material layer includes a negative electrode active material.

[0062] This invention does not impose any special limitations on the selection of electrolyte; it can be selected according to the actual situation.

[0063] The present invention does not impose any special restrictions on the selection of the diaphragm, which can be selected according to the actual situation.

[0064] Specifically, A anode The electrochemical active area of ​​the negative electrode active material is expressed in meters (m²). 2 / g calculation.

[0065] The electrochemical active area of ​​the negative electrode active material in the embodiments of the present invention can be tested using conventional testing methods, such as cyclic voltammetry, AC impedance spectroscopy, and potential step method.

[0066] In some embodiments, the electrochemical active area of ​​the negative electrode active material is tested by the following method: A negative electrode sheet made of the negative electrode active material is cut into 63×74mm pieces and assembled into a symmetrical battery. After a conventional liquid injection and aging process, it is placed in a constant temperature chamber at 25°C for at least 30 minutes. After removal, an AC impedance test is performed using a Bio-Logic VMP300 electrochemical workstation in a constant temperature chamber at 298K. The test method is potentiostatic, with a test frequency range of 200kHz to 10mHz and an excitation voltage of 5mV. Ten data points are collected every ten times the frequency to obtain the Nyquist curve. After fitting using Zview software, the desired parameters (T, P, R) are obtained. i R ct Substituting these values ​​into Formula 1 yields the double-layer capacitance value C. dl .

[0067]

[0068] Where T is a quantity related to the capacitance of the symmetrical battery, in Ω. -1 ·s n Calculate; P represents the degree of non-ideality of the symmetrical battery capacitance, ranging from 0 to 1, where 0 indicates a pure resistance and 1 indicates an ideal capacitance; R i R is the liquid phase diffusion impedance of a symmetrical cell; ct This represents the charge transfer impedance of a symmetrical cell.

[0069] The obtained C dl Substituting into Formula 2, we can obtain the electrochemical active area A of the negative electrode active material (i.e., A0). anode ).

[0070]

[0071] Where ε0 is the permittivity of vacuum, ε d denoted by , where is the dielectric constant of the electrolyte, and d is the thickness of the electric double layer. In this embodiment of the invention, the thickness of the electric double layer refers to the thickness between the two outermost electrode plates in a symmetrical battery, excluding the thickness of the electrode plates themselves.

[0072] C Li This refers to the mass ratio of lithium supplement to positive electrode active material.

[0073] S is the specific surface area of ​​the negative electrode active material, in m². 2 / g. The specific surface area of ​​the negative electrode active material in the embodiments of the present invention can be tested by conventional methods, such as gas adsorption, mercury porosimetry, liquid adsorption, gas permeation, dynamic light scattering, etc.

[0074] In this embodiment of the invention, the specific surface area of ​​the negative electrode active material was tested using a Tristar II 3020 specific surface area analyzer and the Brunauer-Emmett-Teller (BET) method. Specifically, the following method can be used: 3-5g of the negative electrode active material was weighed and heated to 105-110℃ in a vacuum environment to degas it, removing adsorbed moisture and impurities from the surface. Using nitrogen as the adsorbate, the negative electrode active material was placed in a liquid nitrogen environment, and nitrogen was gradually introduced within a relative pressure (P / P0) range of 0-1, recording the adsorption amount at different pressures, and plotting adsorption isotherms. Using the relative pressure P / P0 as the horizontal axis and the adsorption amount as the vertical axis, the BET equation was applied... Linear fitting is performed to calculate the monolayer adsorption capacity Vm, and then the specific surface area of ​​the negative electrode active material is obtained.

[0075] In Equation I, 0.00005 is the lower limit of the comprehensive empirical coefficient summarized by the inventors through long-term research, which can be called k1, and 0.03 is the upper limit of the comprehensive empirical coefficient, which can be called k2. The values ​​of k1 and k2 are related to the battery system. In addition to the positive and negative electrode materials themselves having a significant impact on k1 and k2, factors such as the conductivity and stability of the electrolyte, process parameters (coating surface density, compaction density), battery design (N / P ratio, electrode size, battery configuration), and the battery's required performance targets (fast charging performance, cycle life, energy density, etc.) all affect the different values ​​of k1 and k2. Considering the different combinations of positive electrode materials, negative electrode materials, electrolytes, and process parameters in the battery system, the inventors, through long-term research, have summarized the lower limit of the comprehensive empirical coefficient k1 in Equation I as 0.00005 and the upper limit of the comprehensive empirical coefficient k2 as 0.03.

[0076] To achieve both good fast-charging performance and long cycle life, the inventors, through long-term experimental verification, limited the value to 0.00005·S≤A. anode ·CLi ≤0.03·S. When a battery meets the above conditions, it can not only improve the fast charging performance of the battery, but also make the battery have a longer cycle life and higher safety performance.

[0077] The battery in this embodiment of the invention satisfies 0.0005·S≤A anode ·C Li When the value is ≤0.015·S, its fast charging performance, cycle life and safety performance can be further improved.

[0078] In some embodiments, the electrochemical active area A of the negative electrode active material anode ≤2m 2 / g, for example, A anode For example, 0.01m 2 / g, 0.1, m 2 / g, 0.16m 2 / g, 0.3m 2 / g, 0.5m 2 / g, 0.079m 2 / g, 0.85m 2 / g, 0.91m 2 / g, 1.03m 2 / g, 1.2m 2 / g, 1.3m 2 / g, 1.43m 2 / g, 1.49m 2 / g, 1.8m 2 / g、2m 2 / g or a range consisting of any two of them. A anode When the above conditions are met, the deposition rate of lithium ions on the surface of the negative electrode can be further reduced, which can reduce the risk of lithium plating and thus better improve its safety performance; on the other hand, A anode A negative electrode that meets the above conditions provides more insertion / extraction sites for lithium ions, improving the lithium ion transport efficiency within the negative electrode and thus supporting higher charging currents to further enhance the battery's fast-charging performance. Therefore, A anode Batteries that meet the above conditions can not only better reduce electrode polarization and reduce energy loss during cycling, but also further disperse the lithium ion insertion / extraction stress, alleviate the deformation of the negative electrode active material, and thus reduce damage to the electrode structure. At the same time, the degree of side reactions in the electrolyte of the negative electrode in the battery is further reduced, which is conducive to improving the cycle life of the battery.

[0079] In one specific embodiment, the mass ratio C of the lithium supplementer to the positive electrode active material is... Li The ratio is 0.01% to 5%. For example, the mass ratio C of the lithium supplement to the positive electrode active material is...Li For example, the range could be 0.01%, 0.05%, 0.08%, 0.1%, 0.12%, 0.15%, 0.2%, 0.25%, 0.3%, 0.4%, 0.5%, 1.5%, 2.5%, 5%, or any combination thereof. When the mass ratio of the lithium supplement to the positive electrode active material meets the above range, the lithium supplement can better balance the lithium-ion content inside the battery, thereby further improving the lithium plating problem inside the battery and the problem of low battery cycle life.

[0080] In one specific embodiment, the specific surface area S of the negative electrode active material is ≤ 3m². 2 / g, the specific surface area S of the negative electrode active material is, for example, 0.01m². 2 / g, 0.1m 2 / g, 0.2m 2 / g, 0.5m 2 / g, 0.8m 2 / g, 1.2m 2 / g, 1.5m 2 / g、2m 2 / g, 2.5m 2 / g、3m 2 / g or any combination thereof. When the specific surface area S of the negative electrode active material meets the above conditions, it is beneficial for lithium ions to enter and exit the electrode material more quickly during charging and discharging, thereby accelerating the reaction rate and improving the electrochemical reaction efficiency, which in turn is beneficial for further improving the fast charging performance of the battery.

[0081] In some embodiments, the electrochemical active area A of the negative electrode active material anode The range is 0.5 to 1.5 m. 2 / g, for example, A anode For example, 0.5m 2 / g, 0.79m 2 / g, 0.9m 2 / g、1m 2 / g, 1.2m 2 / g, 1.3m 2 / g, 1.43m 2 / g, 1.5m 2 / g or a range consisting of any two of them. The inventors discovered that when the electrochemical active area A of the negative electrode active material... anode Within the aforementioned range, the probability of side reactions with the electrolyte can be further reduced and the lithium-ion insertion / extraction rate can be further improved, which is beneficial for the battery to have better fast charging performance and longer cycle life. At the same time, the material cost of battery preparation can be further taken into account, and the price of the battery can be further reduced, thus making the battery more competitive in the market.

[0082] In one specific embodiment, the mass ratio C of the lithium supplementer to the positive electrode active material is... Li The mass ratio of lithium supplement to positive electrode active material is 0.05%–0.2%, C. Li For example, a range of 0.05%, 0.1%, 0.15%, 0.2%, or any combination thereof. When the mass ratio C of the lithium supplement to the positive electrode active material... Li Within the aforementioned range, not only can the lithium plating problem inside the battery and the problem of low battery cycle life be improved, but the consumption cost of lithium replenishment agent can also be reduced, which is conducive to further enhancing its market competitiveness.

[0083] In one specific embodiment, the specific surface area S of the negative electrode active material is 0.5–1.5 m². 2 / g, the specific surface area S of the negative electrode active material is, for example, 0.5m². 2 / g, 0.8m 2 / g, 1.2m 2 / g, 1.5m 2 / g or any combination thereof. When the specific surface area S of the negative electrode active material is within the above range, the battery exhibits better fast-charging performance.

[0084] In some embodiments, the positive electrode active material may include LiCoO2, LiNiO2, or LiCo. x Ni 1-x O2 (0≤x≤1), LiCo x Ni 1-x-y Al y O2(0≤x≤1,0≤y≤1), LiMn2O4, LiFe x Mn y M z O4 (M is one or more of Al, Mg, Ga, Cr, Co, Ni, Cu, Zn or Mo, 0≤x≤1, 0≤y≤1, 0≤z≤1, x+y+z=1), Li 1+x L 1－y－z M y N z O2 (L, M, N are one or more of Li, Co, Mn, Ni, Fe, Al, Mg, Ga, Ti, Cr, Cu, Zn, Mo, F, I, S, B, -0.1≤x≤0.2, 0≤y≤1, 0≤z≤1, 0≤y+z≤1), LiFePO4, Li3V2(PO4)3, Li3V3(PO4)3, LiVPO4F, Li2CuO2, Li5FeO4, and metal sulfides and oxides (such as TiS2, V2S3, FeS, FeS2, LiMS) x(M is at least one of the transition metal elements such as Ti, Fe, Ni, Cu, Mo, etc., 1≤x≤2.5), TiO2, Cr3O8, V2O5, MnO2, etc.

[0085] In the aforementioned batteries, the positive electrode active materials in some embodiments of the present invention include lithium cobalt oxide (LiCoO2), lithium manganese oxide (LiMn2O4), lithium iron phosphate (LiFePO4), and ternary cathode materials (LiCo). x Ni 1-x O2 (0≤x≤1), LiCo x Ni 1-x-y Al y Using one or more of O2 (0≤x≤1, 0≤y≤1) to prepare positive electrode active materials is beneficial to improving the energy density of the battery.

[0086] In one specific embodiment, the lithium replenishing agent includes one or more of lithium carbonate, lithium hydroxide, lithium oxalate, lithium fluoride, lithium acetate, lithium ferrite, and lithium nickelate. The above-mentioned lithium replenishing agents have better lithium replenishing performance, lower lithium ion release energy, and can better balance the lithium ion content inside the battery, thereby being more conducive to improving the lithium plating problem inside the battery and the problem of low battery cycle life.

[0087] In some embodiments, the negative electrode active material includes a coating layer and a core, with the coating layer covering at least a portion of the core; the coating layer includes one or more of metal oxides, carbon-based materials, polymers, and lithium salts; the core includes one or more of graphite, lithium titanate, and silicon-carbon composite materials. By providing a coating layer to the core, embodiments of the present invention allow for more flexible adjustment of the electrochemical active area of ​​the negative electrode active material.

[0088] In some embodiments, the metal oxides include, but are not limited to, one or more of aluminum oxide (Al2O3), titanium dioxide (TiO2), and zirconium dioxide (ZrO2); the carbon-based materials include, but are not limited to, at least one of graphene, carbon nanotubes, pitch, amorphous carbon, and glucose; the polymers include, but are not limited to, one or more of polypyrrole and polyaniline; the lithium salts include, but are not limited to, at least one of LiF and Li2CO3; and the anode materials include, or one or more of graphite, lithium titanate, and silicon-carbon composite materials. By using the above materials as a coating layer for the core of the anode active material, the embodiments of the present invention can more effectively adjust the electrochemical active area of ​​the anode active material, thereby better improving the fast-charging performance and cycle life of the battery.

[0089] To adjust the electrochemical active area of ​​the aforementioned negative electrode active material, this embodiment of the invention employs a coating treatment to modify the surface of the negative electrode material (including modifying its surface morphology and pore structure) to obtain the negative electrode active material. The coating treatment involves depositing a coating material such as a carbon source, metal oxide, polymer, or lithium salt onto the negative electrode material to obtain the negative electrode active material. The coating material can be used to form a coating layer. The carbon source includes, but is not limited to, at least one of graphene, carbon nanotubes, pitch, amorphous carbon, and glucose; the metal oxide includes, but is not limited to, one or more of alumina (Al₂O₃), titanium dioxide (TiO₂), and zirconium dioxide (ZrO₂); the polymer includes, but is not limited to, one or more of polypyrrole and polyaniline; the lithium salt includes, but is not limited to, at least one of LiF and Li₂CO₃; and the negative electrode material includes, or is not limited to, graphite, lithium titanate, and silicon-carbon composite materials.

[0090] The embodiments of this invention do not impose special limitations on the deposition process; conventional industrial methods can be used as long as the coating purpose can be achieved. Specifically, physical vapor deposition (such as evaporation deposition, sputtering deposition, etc.), chemical vapor deposition (low-pressure chemical vapor deposition, plasma-enhanced chemical vapor deposition (PECVD), metal-organic chemical vapor deposition (MOCVD), etc.), and electrochemical deposition can be used for the deposition process in the coating treatment.

[0091] This invention does not impose special limitations on the processing temperature and processing time of the deposition process; the appropriate temperature and processing time can be selected based on the actual situation.

[0092] In some embodiments, the negative electrode active material includes one or more of graphite oxide material obtained through oxidation treatment, lithium titanate material, and silicon-carbon oxide composite material. The use of these materials is more conducive to adjusting the electrochemical active area of ​​the negative electrode active material, thereby improving the battery's fast-charging performance and cycle life. Specifically, the graphite oxide material is obtained by oxidizing graphite material, the lithium titanate material is obtained by oxidizing lithium titanate, and the silicon-carbon oxide composite material is obtained by oxidizing silicon-carbon composite material.

[0093] In one embodiment, the above-mentioned negative electrode active material is prepared by a method including the following steps: the negative electrode material is oxidized by an oxidant to obtain the above-mentioned negative electrode active material.

[0094] Oxidizing agents include one or more of oxygen, nitric acid, sulfuric acid, and potassium permanganate;

[0095] The negative electrode material includes one or more of graphite, lithium titanate, and silicon-carbon composite materials.

[0096] The embodiments of the present invention do not impose special limitations on the processing time and temperature of the oxidation treatment; they can be selected according to the actual situation.

[0097] In some embodiments, the oxidant includes one or more of oxygen, nitric acid, sulfuric acid, and potassium permanganate. When the above-mentioned oxidants are used for oxidation treatment, the adjustment effect on the electrochemical active area of ​​the negative electrode active material is better, and there are fewer residual impurities after oxidation treatment, resulting in less impact on battery performance. When the oxidant includes oxygen, the negative electrode material can be calcined in an oxygen-containing atmosphere to complete the oxidation treatment; when the oxidant includes one or more of nitric acid, sulfuric acid, and potassium permanganate, the negative electrode material can be oxidized in a solution containing the above substances. For example, when using nitric acid as the oxidant to oxidize the negative electrode material, concentrated nitric acid (65-68%) can be used at 60-100°C for 4-20 hours to obtain the negative electrode active material; when using H2SO4 as the oxidant, H2SO4 (concentration 95-98%) can be used with a voltage of 1-10V at 20-30°C for 4-20 hours to obtain the negative electrode active material. When using KMnO4 as an oxidant, KMnO4 with a mass of 5 to 10 times that of graphite can be dissolved in a mixed acid solution with a volume ratio of H2SO4:H3PO4 = 9:1 to carry out the oxidation reaction.

[0098] The negative electrode material includes one or more of graphite, lithium titanate, and silicon-carbon composite materials. Using the above-mentioned negative electrode materials to prepare negative electrode active materials is beneficial to further improve the energy density of the battery.

[0099] This invention provides a method for preparing a battery, comprising the following steps: coating a positive electrode slurry, including a positive electrode active material and a lithium supplement, onto a positive electrode current collector to obtain a positive electrode sheet;

[0100] A negative electrode sheet is obtained by coating a negative electrode slurry containing a negative electrode active material onto a negative electrode current collector.

[0101] A battery is obtained by assembling the positive electrode, negative electrode, and separator.

[0102] Generally, a battery includes an electrolyte, a battery cell, and a casing for encapsulating the battery cell. The electrolyte is injected into the battery cell within the casing. The battery cell includes electrode plates (including positive and negative electrode plates) and a separator located between the positive and negative electrode plates. The battery cell can be a stacked cell, meaning it is composed of positive electrode plates, a separator, and negative electrode plates stacked alternately; or it can be a wound cell, meaning it is composed of positive electrode plates, a separator, and negative electrode plates stacked and then wound together. In practice, a stacked cell can be formed by alternating layers of positive electrode plates, a separator, and negative electrode plates, and then the cell is encapsulated using an aluminum-plastic film.

[0103] The electrolyte in this embodiment of the invention can be a conventional electrolyte in the art. For example, the electrolyte is a non-aqueous electrolyte, which may specifically include organic solvents, additives and electrolyte salts. Organic solvents include one or more of ethylene carbonate (EC), diethyl carbonate (DEC) and propylene carbonate (PC). Additives include, for example, fluoroethylene carbonate (FEC) and vinylene carbonate (VC). Electrolyte salts may include lithium salts, such as lithium hexafluorophosphate (LiPF6), but are not limited thereto.

[0104] In this embodiment of the invention, the separator is used to separate the positive electrode and the negative electrode to prevent the positive electrode and the negative electrode from short-circuiting due to contact. Conventional separators in the art can be used in this embodiment of the invention, and there are no special limitations.

[0105] In this embodiment of the invention, the battery cell can be packaged using conventional housing materials in the art, such as flexible packaging materials like aluminum-plastic film, but is not limited thereto.

[0106] The embodiments of the present invention can assemble components such as positive electrode, separator and negative electrode into a battery using conventional methods in the art. For example, positive electrode, separator and negative electrode can be stacked in an alternating manner to obtain a stacked cell (or wound into a wound cell); then the cell is placed in a casing (outer packaging) and after conventional processes such as electrolyte injection, encapsulation, formation and capacity testing, a battery is obtained.

[0107] The positive electrode sheet includes a positive current collector and a positive active material layer. Specifically, the positive active layer can be provided on one side of the surface of the positive current collector in the thickness direction, or the positive active layer can be provided on both sides of the surface of the positive current collector in the thickness direction.

[0108] The positive electrode active material layer may include positive electrode active material, conductive agent and binder. In the positive electrode coating, the mass percentage of positive electrode active material may be 70% to 99%, for example, 70%, 75%, 80%, 85%, 90%, 93%, 95%, 97%, 99% or any combination thereof. The mass fraction of binder may be 0.5% to 15%, for example, 0.5%, 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, 5%, 8%, 10%, 13%, 15% or any combination thereof.

[0109] The binder for the positive electrode active material layer includes one or more of the following: polyvinylidene fluoride (PVDF), polyvinylidene fluoride, polyvinyl fluoride, polyethylene, polypropylene, polyvinyl alcohol, carboxymethyl cellulose, hydroxypropyl cellulose, diacetyl cellulose, polyvinyl chloride, carboxylated polyvinyl chloride, ethylene oxide-containing polymers, polyvinylpyrrolidone, and polyurethane.

[0110] In some embodiments, the positive electrode active material may include LiCoO2, LiNiO2, or LiCo. x Ni 1-x O2 (0≤x≤1), LiCo x Ni 1-x-y Al y O2(0≤x≤1,0≤y≤1), LiMn2O4, LiFe x Mn y M z O4 (M is one or more of Al, Mg, Ga, Cr, Co, Ni, Cu, Zn or Mo, 0≤x≤1, 0≤y≤1, 0≤z≤1, x+y+z=1), Li 1+x L 1－y－z M y N z O2 (L, M, N are one or more of Li, Co, Mn, Ni, Fe, Al, Mg, Ga, Ti, Cr, Cu, Zn, Mo, F, I, S, B, -0.1≤x≤0.2, 0≤y≤1, 0≤z≤1, 0≤y+z≤1), LiFePO4, Li3V2(PO4)3, Li3V3(PO4)3, LiVPO4F, Li2CuO2, Li5FeO4, and metal sulfides and oxides (such as TiS2, V2S3, FeS, FeS2, LiMS) x (M is at least one of the transition metal elements such as Ti, Fe, Ni, Cu, Mo, etc., 1≤x≤2.5), TiO2, Cr3O8, V2O5, MnO2, etc.

[0111] In specific implementations, positive electrode active materials include lithium cobalt oxide (LiCoO2), lithium manganese oxide (LiMn2O4), lithium iron phosphate (LiFePO4), and ternary positive electrode materials (LiCo). x Ni 1-x O2 (0≤x≤1), LiCo x Ni 1-x-y Al y Using one or more of O2 (0≤x≤1, 0≤y≤1) to prepare positive electrode active materials is beneficial to improving the energy density of the battery.

[0112] The positive electrode sheet of this invention includes a lithium replenishing agent. This invention does not specifically limit the type of lithium replenishing agent, as long as it can replenish lithium in the battery.

[0113] In some embodiments, the lithium supplement includes one or more of lithium carbonate, lithium hydroxide, lithium oxalate, lithium fluoride, lithium acetate, lithium ferrite, and lithium nickelate.

[0114] The present invention does not impose any special limitation on the method of adding lithium replenishing agent. For example, it can be prepared by dry mixing with positive electrode active material, conductive agent and binder in a dry state to form positive electrode slurry and then proceed with subsequent preparation; or it can be added by wet coating, that is, the lithium replenishing agent is first dissolved or dispersed in a suitable solvent to form a slurry, and then coated on the surface of positive electrode active material. After drying to remove the solvent, the battery is obtained.

[0115] The embodiments of the present invention may employ conventional positive current collectors in the art, for example, positive current collectors may include aluminum foil.

[0116] In this embodiment of the invention, the positive electrode sheet can be prepared by conventional methods in the art, such as by coating. Specifically, the positive electrode active material, conductive agent, binder, and other components used to form the positive electrode active layer can be dispersed in a solvent, such as N-methylpyrrolidone (NMP), to prepare a positive electrode slurry. This slurry is then coated onto the surface of the positive electrode current collector, and after drying, rolling, and other processes, the positive electrode sheet is obtained. The coating, drying, and rolling processes involved are conventional operations for preparing positive electrode sheets using the coating method, and are not particularly limited thereto.

[0117] In one specific embodiment, the negative electrode sheet includes a negative electrode active material and a negative electrode active layer. The negative electrode active material layer can be provided on one side surface in the thickness direction of the negative electrode current collector, or negative electrode active material layers can be provided on both opposite sides surface in the thickness direction of the negative electrode current collector.

[0118] In this embodiment of the invention, the binder in the negative electrode active material layer includes at least one of polytetrafluoroethylene (PTFE), styrene-butadiene rubber (SBR), sodium carboxymethyl cellulose (CMC), tetrafluoroethylene and its copolymers, polyvinylidene fluoride and its copolymers, polyolefins and their copolymers (e.g., polyethylene-polyethylene glycol block copolymers), polyethers and their copolymers (e.g., polyethylene oxide), polyphenylene ethers and their copolymers, polysiloxanes and their copolymers (e.g., polydimethylsiloxane, poly(dimethylsiloxane-co-alkylmethylsiloxane)), polyesters and their copolymers (e.g., polyethylene ester, polyvinyl acetate, polyacrylate), carboxymethyl cellulose, styrene-butadiene latex, nitrile rubber, and polyacrylic acid (PAA).

[0119] Specifically, polyolefins include one or more of polyethylene, polypropylene, ethylene / propylene copolymer, ethylene / vinylidene fluoride copolymer, and propylene / vinylidene fluoride copolymer; polytetrafluoroethylene and its copolymers may be at least one of tetrafluoroethylene / ethylene copolymer, tetrafluoroethylene / propylene copolymer, tetrafluoroethylene / vinylidene fluoride copolymer, tetrafluoroethylene / ether copolymer, tetrafluoroethylene / branched polyether copolymer, tetrafluoroethylene / vinyl ether copolymer, tetrafluoroethylene / branched polyether / vinyl ether copolymer, and tetrafluoroethylene / siloxane copolymer.

[0120] In addition, the negative electrode active material layer also includes a negative electrode active material, specifically, the selection of the negative electrode active material is as described above. Generally, the mass percentage of the negative electrode active material in the negative electrode active material layer can be 80% to 100%, and the mass percentage of the negative electrode active material in the negative electrode active material layer can be, for example, 80%, 82%, 85%, 88%, 90%, 92%, 95%, 98%, 100%, or any combination thereof.

[0121] The embodiments of the present invention may employ conventional negative electrode current collectors in the art, for example, negative electrode current collectors include copper foil.

[0122] In embodiments of the present invention, the negative electrode sheet can be prepared by a dry process (i.e., rolling the material used to form the negative electrode active layer into a film and then combining it with the negative electrode current collector to obtain the negative electrode sheet), or by a wet process (coating method) (i.e., coating the negative electrode slurry used to form the negative electrode active layer onto the surface of the negative electrode current collector, and then drying, rolling and other processes to form the negative electrode active layer on the surface of the negative electrode sheet to obtain the negative electrode sheet).

[0123] This invention provides a battery pack including the battery described above. This battery pack has advantages corresponding to the battery described above, which will not be elaborated further.

[0124] Generally, a battery pack includes multiple batteries as individual cells, which are connected to form the battery pack. These batteries can be electrically connected using methods conventional in the art, such as series connection, parallel connection, or a combination of these connection methods, without any particular limitation.

[0125] The present invention also provides an electrical device, including the aforementioned battery or battery pack. This electrical device has advantages corresponding to the aforementioned battery, which will not be elaborated further.

[0126] The electrical equipment provided by this invention can be conventional electrical equipment in the field, such as power equipment (e.g., electric vehicles, electric cars), electrical equipment (e.g., mobile phones, tablets, laptops, digital cameras, etc.), wearable devices (e.g., watches, bracelets, VR glasses, etc.), energy storage power stations, etc., without any particular limitation.

[0127] The technical solution of the present invention will be further described below with reference to specific embodiments.

[0128] Example 1

[0129] The battery manufacturing process in this embodiment is as follows:

[0130] 1) Graphite anode material is coated with asphalt using chemical vapor deposition (CVD) to obtain an anode active material with a graphite core and an amorphous carbon coating layer. The anode active material is dissolved in N-methylpyrrolidone (NMP) to obtain an anode slurry. The slurry is then sieved (using a 200-mesh sieve) and coated onto a negative electrode current collector (copper foil). After drying at 100°C, cold pressing, and die-cutting, a negative electrode sheet is obtained. The mass ratio of the anode active material, conductive agent (carbon black), and binder (CMC) in the anode slurry is 100:1.5:3.4. S is obtained through specific surface area testing, and A is obtained through electrochemical active area testing. anode .

[0131] 2) Including positive electrode active material, lithium supplement (Li5FeO) 4， C Li A positive electrode slurry (0.1%) is coated onto a positive electrode current collector (aluminum foil), dried at 110℃, cold-pressed, and die-cut to obtain a positive electrode sheet; wherein, the mass ratio of positive electrode material (ternary material NCM811, lithium supplement), conductive agent (carbon nanotube), and binder (polyvinylidene fluoride) in the positive electrode slurry is 96:2:2; the solvent of the positive electrode slurry is N-methylpyrrolidone (NMP).

[0132] 3) The positive electrode, separator (PP / PE), and negative electrode are stacked alternately to obtain a stacked cell; then the cell is placed in a casing (aluminum-plastic film), vacuum baked to remove moisture, and then subjected to conventional processes such as electrolyte injection (i.e., injection of electrolyte, the electrolyte being LiPF6:EC:EMC:EA = 15:24:55:6), encapsulation, formation, and capacity testing to obtain the battery.

[0133] Electrochemical active area A of the negative electrode active material anode The mass ratio of lithium supplement to positive electrode active material C Li The specific surface area S and A of the negative electrode active material anode ·C Li / S is shown in Table 1.

[0134] Example 2

[0135] This embodiment is basically the same as Embodiment 1, except that the graphite anode material is coated with asphalt using physical vapor deposition (PVD) to obtain an anode active material with a graphite core and an amorphous carbon coating layer.

[0136] Example 3

[0137] This embodiment is basically the same as Embodiment 1, except that glucose is used to coat the negative electrode material graphite by electrodeposition to obtain a negative electrode active material with a graphite core and an amorphous carbon coating layer.

[0138] Example 4

[0139] This embodiment is basically the same as Example 1, except that graphite oxide is used as the negative electrode active material. Graphite oxide is prepared by the following method: the negative electrode material graphite is oxidized (the treatment conditions are: 100g of graphite is added to 600g of concentrated nitric acid (65-68%), and refluxed at high temperature (90-100℃) for 8 hours) to obtain the negative electrode active material (graphite oxide).

[0140] Example 5

[0141] This embodiment is basically the same as Embodiment 1, except that graphite oxide is used as the negative electrode active material. Graphite oxide is prepared by the following method: the negative electrode material graphite is oxidized (the treatment conditions are: 100g of graphite is added to 650g of H2SO4 solution (96%), a voltage of 3V is applied, and the treatment is carried out at room temperature for 5 hours) to obtain the negative electrode active material (graphite oxide).

[0142] Example 6

[0143] This embodiment is basically the same as Example 1, except that graphite oxide is used as the negative electrode active material. Graphite oxide is prepared by the following method: the negative electrode material graphite is oxidized (the treatment conditions are: 100g of graphite and 500g of KMnO4 are added to 800mL of mixed acid with a volume ratio of H2SO4:H3PO4 = 9:1, and refluxed at high temperature for 3 hours) to obtain the negative electrode active material (graphite oxide).

[0144] Example 7

[0145] This embodiment is basically the same as Example 1, except that graphite oxide is used as the negative electrode active material. Graphite oxide is prepared by the following method: the negative electrode material graphite is oxidized (the treatment conditions are: 100g of graphite and 500g of KMnO4 are added to 800mL of mixed acid with a volume ratio of H2SO4:H3PO4 = 9:1, and the reaction is carried out at 50°C for 12 hours) to obtain the negative electrode active material (graphite oxide).

[0146] Example 8

[0147] This embodiment is basically the same as Example 1, except that graphite oxide is used as the negative electrode active material. Graphite oxide is prepared by the following method: the negative electrode material graphite is oxidized (the treatment conditions are: 100g of graphite and 600mL of H2SO4 / NaNO3 mixture are stirred in an ice bath (0-4℃) for 30 minutes, 400g of KMnO4 is slowly added and stirred at room temperature for 4 hours, then the temperature is raised to 50℃ and reacted for 1 hour). The negative electrode active material (graphite oxide) is obtained.

[0148] Example 9

[0149] This embodiment is basically the same as embodiment 4, except that C in this embodiment... Li It is 0.05%.

[0150] Example 10

[0151] This embodiment is basically the same as embodiment 4, except that C in this embodiment... Li It is 0.08%.

[0152] Example 11

[0153] This embodiment is basically the same as embodiment 4, except that C in this embodiment... Li It is 0.12%.

[0154] Example 12

[0155] This embodiment is basically the same as embodiment 4, except that C in this embodiment... Li It is 0.15%.

[0156] Example 13

[0157] This embodiment is basically the same as embodiment 4, except that C in this embodiment... Li It is 0.20%.

[0158] Example 14

[0159] This embodiment is basically the same as embodiment 4, except that C in this embodiment... Li It is 0.01%.

[0160] Example 15

[0161] This embodiment is basically the same as embodiment 4, except that C in this embodiment... Li It is 0.40%.

[0162] Example 16

[0163] This embodiment is basically the same as embodiment 4, except that C in this embodiment... Li It is 0.50%.

[0164] Example 17

[0165] This embodiment is basically the same as embodiment 4, except that C in this embodiment... Li It is 2.25%.

[0166] Example 18

[0167] This embodiment is basically the same as Embodiment 4, except that the lithium supplementer in this embodiment is Li2NiO2, C Li It is 0.15%.

[0168] Example 19

[0169] This embodiment is basically the same as Embodiment 1, except that TiO2 is used as the coating material to coat the graphite anode material using a sol-gel method, resulting in an anode active material with a graphite core and a TiO2 coating layer. Li It is 0.15%.

[0170] Example 20

[0171] This embodiment is basically the same as Embodiment 4, except that in this embodiment, the negative electrode active material is a silicon-carbon composite negative electrode material coated with asphalt using chemical vapor deposition (CVD), resulting in a silicon-carbon composite core and an amorphous carbon coating layer. Li It is 0.15%.

[0172] Example 21

[0173] This embodiment is basically the same as Embodiment 11, except that in this embodiment, the negative electrode active material is a silicon-carbon composite negative electrode material coated with glucose by electrodeposition, resulting in a silicon-carbon composite core and an amorphous carbon coating layer. Li It is 0.15%.

[0174] Example 22

[0175] This embodiment is basically the same as Embodiment 11, except that the lithium supplementer in this embodiment is Li2NiO2, C Li It is 0.15%.

[0176] Comparative Example 1

[0177] This comparative example is basically the same as Example 5, except that C in this comparative example Li It is 4.00%.

[0178] Comparative Example 2

[0179] This comparative example is basically the same as Example 7, except that C in this comparative example...Li It is 0.01%.

[0180] Comparative Example 3

[0181] This comparative example is basically the same as Example 1, except that the negative electrode material is coated (the processing conditions are: phenolic resin coating of graphite is achieved by chemical vapor deposition (CVD)) to obtain the negative electrode active material (coated graphite: the core is graphite, and the coating layer is TiO2). Li It is 1.50%.

[0182] Test case

[0183] Fast charging performance test: During the charging process of the battery cell at 25℃, when lithium plating occurs on the negative electrode, the thickness of the electrode sheet increases sharply, causing an inflection point in the cell thickness growth. Therefore, an in-situ thickness gauge was used to measure the thickness change of the battery cell during charging, and a SOC-thickness curve was plotted. By reading the SOC at the thickness inflection point, the lithium plating boundary under different test conditions was obtained. Specifically, in the above embodiments and comparative examples, an in-situ thickness gauge was connected to the battery. First, the battery was charged to 3.8V at a rate of 1 / 3C. If a thickness inflection point appeared, the test was stopped. If no thickness inflection point appeared, the battery was discharged to 2V, and then recharged to 3.8V at a rate of 1C. If a thickness inflection point appeared, the test was stopped. If no thickness inflection point appeared, the battery was discharged to 2V, and then recharged to 3.8V at a rate increased by 0.5C from the previous charge. This process was repeated until the battery thickness inflection point appeared. The test results are shown in Table 2. The significance of the 6C lithium plating boundary in Table 2 is: under a charging rate of 6C, the SOC value (battery state of charge) corresponding to the thickness inflection point on the SOC-thickness curve. Figure 2 It can be seen that when the battery is prepared by using the negative electrode active material of Example 3 of the present invention, the SOC value corresponding to the thickness inflection point of the SOC-thickness curve is 50.5%, while the thickness inflection point of Comparative Example 1 is 29.3%. Therefore, Example 3 has better fast charging performance.

[0184] Cycle life test: At 60℃, the battery is charged at a constant current of 1C to 3.8V, and then charged at a constant voltage until the current reaches 0.05C. At this point, the battery is fully charged, and the charging capacity is recorded, which is the first charge capacity. After the battery is left to rest for 10 minutes, it is discharged at a constant current of 1C to 2.0V. This completes one charge-discharge cycle, and the discharge capacity is recorded, which is the first discharge capacity. The battery is then subjected to the cycle charge-discharge test using the above method, and the discharge capacity after each cycle is recorded.

[0185] Battery capacity retention rate (%) after 200 cycles at 60℃ = Discharge capacity after 200 cycles / Discharge capacity in the first cycle × 100%.

[0186] Furthermore, in Embodiment 3 of the present invention, the capacity can still be maintained at more than 85% after about 1000 cycles, while in Comparative Example 1, the capacity has dropped to 80% after about 1000 cycles. Therefore, the battery in Embodiment 3 has a better capacity retention rate.

[0187] Table 1

[0188]

[0189]

[0190] Table 2

[0191]

[0192]

[0193] As shown in Table 2, compared with Comparative Examples 1-3, the lithium-ion batteries prepared in Examples 1-22 of this invention have good cycle performance and good fast-charging performance. This is attributed to the precise control of the amount of lithium replenishing agent achieved by the electrochemical active area and specific surface area of ​​the negative electrode active material in the negative electrode sheet. This not only improves the lithium-ion insertion / extraction rate, reduces the polarization effect, reduces the risk of lithium dendrite formation, and improves fast-charging performance, but also replenishes the active lithium lost due to side reactions and lithium dendrite formation, thereby extending the cycle life.

[0194] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A battery, characterized by, The battery comprises a positive electrode sheet and a negative electrode sheet; the positive electrode sheet comprises a positive electrode active material and a lithium supplement agent; The negative electrode sheet comprises a negative electrode active material; The battery satisfies: 0.00005 · S < A anode · C Li ≤ 0.03 · S Formula I wherein A anode is the electrochemically active area of the negative active material, in m 2 / g C Li is the mass ratio of the lithium supplement agent to the positive active material; S is the specific surface area of the negative electrode active material, in m2 / g. 2 / g.

2. The battery of claim 1, wherein, The battery satisfies: 0.0005 · S < A anode · C Li ≤ 0.015 · S.

3. The battery according to claim 1 or 2, characterized in that, A anode ≤2m 2 / g; and / or, C Li 0.01 to 5% and / or, S < 3m 2 / g.

4. The battery according to any one of claims 1 to 3, characterized in that A anode is 0.5-1.5 m 2 / g; and / or, C Li is 0.05 to 0.2 percent; and / or S is 0.5 to 1.5 m 2 / g.

5. The battery according to any one of claims 1 to 4, characterized in that, The positive electrode active material comprises one or more of lithium cobaltate, lithium manganate, lithium iron phosphate, and a positive electrode ternary material; The lithium supplement agent comprises one or more of lithium carbonate, lithium hydroxide, lithium oxalate, lithium fluoride, lithium acetate, lithium ferrate, and lithium nickelate.

6. The battery according to any one of claims 1 to 5, characterized in that, The negative electrode active material comprises a coating layer and an inner core, and the coating layer covers at least part of the inner core; The coating layer comprises one or more of a metal oxide, a carbon-based material, a polymer, and a lithium salt; The inner core comprises one or more of graphite, lithium titanate, and a silicon-carbon composite material.

7. The battery according to any one of claims 1 to 5, wherein The negative electrode active material comprises one or more of an oxidized graphite material, an oxidized lithium titanate material, and an oxidized silicon-carbon composite material obtained after oxidation treatment.

8. The battery of claim 7, wherein, The negative electrode active material is prepared by a method comprising the following steps: The negative electrode material is subjected to oxidation treatment by using an oxidizing agent to obtain the negative electrode active material; The oxidizing agent comprises one or more of oxygen, nitric acid, sulfuric acid, and potassium permanganate; The negative electrode material comprises one or more of graphite, lithium titanate, and a silicon-carbon composite material.

9. A method of producing a battery as claimed in any one of claims 1-8, characterized in that The method comprises the following steps: A positive electrode slurry comprising a positive electrode active material and a lithium supplement agent is coated on a positive electrode current collector to obtain a positive electrode sheet; A negative electrode slurry comprising a negative electrode active material is coated on a negative electrode current collector to obtain a negative electrode sheet; The positive electrode sheet, the negative electrode sheet, and a separator are assembled to obtain the battery.

10. An electric device, characterized by The battery comprises the battery of any one of claims 1-8 or the battery prepared by the preparation method of the battery of claim 9.

Images