A battery

Abstract

The embodiment of the present application provides a battery, comprising electrolyte, the electrolyte comprises phosphonitrile ester compound, 1,2,4-butanetricarbonitrile; the mass ratio of phosphonitrile ester compound in electrolyte is 0.01wt%-5wt%, the mass ratio of 1,2,4-butanetricarbonitrile in electrolyte is 0.1wt%-5wt%, and the mass ratio of 1,2,4-butanetricarbonitrile and phosphonitrile ester is (0.1-100):1.The battery has good high-temperature stability and strong stability under shallow charge and shallow discharge cycle.

Description

Technical Field

[0001] This invention relates to the field of battery technology, and more particularly to a battery. Background Technology

[0002] With the rapid iteration and popularization of new energy electric vehicles, portable electronic devices and smart wearable devices, lithium-ion batteries, as the core energy storage unit of these products, directly determine the user experience and market competitiveness of end products. Therefore, the industry has put forward increasingly stringent requirements for the comprehensive performance of lithium-ion batteries. As the key core of battery performance regulation, the electrolyte system has become one of the research and development focuses in the new energy field.

[0003] Different application scenarios have different and highly specific performance requirements for lithium-ion batteries: New energy electric vehicles need to be adapted to the high temperature environment in summer and the frequent shallow charging and discharging conditions caused by daily short-distance driving to ensure range and safety; Smart wearable devices are limited by miniaturization design and need to achieve high energy density in a limited space, while being able to withstand human body temperature or high ambient temperature, and maintain structural stability and low gas production under frequent intermittent charging to avoid device damage; High-performance laptops, gaming devices and other high-power products need to maintain stable performance in high temperature and high rate charging and discharging scenarios.

[0004] All of the aforementioned application scenarios require lithium-ion batteries to simultaneously meet two core requirements: first, high-temperature interface stability, which must effectively suppress electrolyte decomposition and gas generation; and second, sustained performance under shallow charge-discharge cycles, which must prevent repeated rupture and regeneration of the SEI film and battery volume expansion. These dual requirements pose significant challenges to the formulation design, component selection, and performance adaptation of electrolyte systems. Existing electrolyte systems struggle to comprehensively address these requirements, becoming a key technological bottleneck restricting the efficient application of lithium-ion batteries in multiple scenarios. Summary of the Invention

[0005] This invention provides a battery that has good high-temperature stability and strong stability under shallow charge-discharge cycles.

[0006] This invention provides a battery comprising an electrolyte, wherein the electrolyte comprises a phosphate ester nitrile compound and 1,2,4-butanetrionitrile;

[0007] The phosphate ester nitrile compound accounts for 0.01 wt% to 5 wt% of the mass of the electrolyte.

[0008] The 1,2,4-butanetrionitrile in the electrolyte comprises 0.1 wt% to 5 wt% by mass.

[0009] The mass ratio of the 1,2,4-butanetrionitrile to the phosphate ester nitrile is (0.1~100):1.

[0010] In some embodiments of the present invention, the phosphate ester nitrile compound accounts for 0.1 wt% to 3 wt% of the mass in the electrolyte;

[0011] And / or, the mass ratio of the 1,2,4-butanetrionitrile to the phosphate ester nitrile is (0.2~50):1.

[0012] In some embodiments of the present invention, the phosphate ester nitrile compound comprises the structure shown in Formula I:

[0013] Formula I

[0014] R1, R2, and R3 are each independently selected from C1-C10 alkyl groups, C1-C10 alkoxy groups, and C2-C10 alkenyl groups, whether substituted or unsubstituted, and the substituents include at least one of cyano, halogen, and phenyl.

[0015] In some embodiments of the present invention, the phosphate ester nitrile compound comprises at least one of the structures shown in Formulas I-1 to I-6:

[0016] Formula I-1, Formula I-2,

[0017] Formula I-3, Formula I-4,

[0018] Formula I-5, Formula I-6.

[0019] In some embodiments of the present invention, the electrolyte satisfies at least one of the following conditions:

[0020] (1) The electrolyte comprises a first carboxylic acid ester, wherein the first carboxylic acid ester comprises at least one of ethyl propionate and propyl propionate;

[0021] (2) The electrolyte comprises fluorosulfonamide, which comprises at least one of N,N-dimethylaminosulfonyl fluoride, N,N-diethylaminosulfonyl fluoride, N-ethyl-N-methylaminosulfonyl fluoride, N,N-di(fluoromethyl)aminosulfonyl fluoride, N,N-di(difluoromethyl)aminosulfonyl fluoride, N,N-di(trifluoromethyl)aminosulfonyl fluoride, and 1,1,1-trifluoro-N,N-dimethylmethanesulfonamide;

[0022] (3) The electrolyte includes a first carbonate, which includes at least one of vinylene carbonate, difluoroethylene carbonate, and ethylene ethylene carbonate.

[0023] In some embodiments of the present invention, the electrolyte satisfies at least one of the following conditions:

[0024] (1) The mass percentage of the first carboxylic acid ester in the electrolyte is 5wt%~60wt%;

[0025] (2) The ratio of the mass of the first carboxylic acid ester in the electrolyte to the total mass of the phosphate ester nitrile and the 1,2,4-butanetrionitrile is (1~100):1;

[0026] (3) The mass percentage of the fluorosulfonamide in the electrolyte is 2wt%~30wt%;

[0027] (4) The mass percentage of the first carbonate in the electrolyte is 0.01wt%~4wt%.

[0028] In some embodiments of the present invention, the battery further includes a negative electrode sheet, the negative electrode sheet including a negative electrode current collector and a negative electrode active material layer disposed on at least one surface of the negative electrode current collector, the negative electrode active material layer including a negative electrode active material, the negative electrode active material including a silicon-carbon material, the silicon-carbon material including a coating layer, and the negative electrode sheet satisfying at least one of the following conditions:

[0029] (1) The coating layer includes nitrogen, and the mass percentage of nitrogen in the silicon-carbon material is 0.05 wt% to 4.8 wt%.

[0030] (2) The thickness of the coating layer is 1 nm to 30 nm;

[0031] (3) The silicon-carbon material includes a porous carbon matrix and silicon material deposited in the porous carbon matrix.

[0032] In some embodiments of the present invention, the battery further includes a positive electrode sheet, the positive electrode sheet including a positive current collector and a positive active material layer disposed on at least one side surface of the positive current collector, the positive active material layer including a positive active material, the positive active material including lithium cobalt oxide.

[0033] In some embodiments of the present invention, the lithium cobalt oxide material includes at least one of Ni and Mn elements;

[0034] Preferably, the Ni element in the lithium cobalt oxide material has a mass ratio of 100ppm to 3000ppm; preferably, the Mn element in the lithium cobalt oxide material has a mass ratio of 100ppm to 5000ppm.

[0035] In some embodiments of the present invention, the charging cut-off voltage of the battery is greater than or equal to 4.5V.

[0036] The battery provided in this embodiment of the invention, by adding phosphate ester nitrile compounds and 1,2,4-butanetrionitrile to the electrolyte and controlling their content and mass ratio, enables the battery to have high stability at high temperatures and strong stability under shallow charge and discharge cycles. Attached Figure Description

[0037] 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.

[0038] Figure 1 The graph shows the battery thickness expansion rate curves of Embodiment 1 and Comparative Example 1 of the present invention during shallow charge and discharge cycle performance testing at 45°C.

[0039] 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

[0040] 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.

[0041] Currently, lithium-ion batteries suffer from poor high-temperature stability and inadequate stability under shallow charge-discharge cycles. The core reasons for this are the high degree of side reactions at the electrode interface and the poor stability of the electrolyte. At high temperatures, the electrolyte is prone to oxidative decomposition, and the positive electrode is susceptible to structural collapse, leading to the dissolution of metal ions and further exacerbating internal side reactions. Simultaneously, the solid electrolyte interphase (SEI) film formed on the negative electrode surface is prone to rupture and regeneration at high temperatures, resulting in continuous lithium consumption and increased internal impedance. Furthermore, under shallow charge-discharge cycles, the electrolyte components are also prone to oxidative decomposition and gas generation at high state of charge (SOC), making it impossible for the electrode interface film to maintain long-term stability. This further exacerbates battery expansion and performance degradation, failing to meet practical application requirements.

[0042] Therefore, the inventors took into account both improving the high-temperature side reaction problem of the electrolyte and the ion transport efficiency, and attempted to improve the high-temperature stability of the battery as well as its stability under shallow charge and discharge cycles.

[0043] Based on this, embodiments of the present invention provide a battery comprising an electrolyte, the electrolyte comprising a phosphate ester nitrile compound and 1,2,4-butanetrionitrile; the phosphate ester nitrile compound has a mass percentage of 0.01wt% to 5wt% in the electrolyte, the 1,2,4-butanetrionitrile has a mass percentage of 0.1wt% to 5wt% in the electrolyte, and the mass ratio of 1,2,4-butanetrionitrile to phosphate ester nitrile is (0.1~100):1.

[0044] The battery of the present invention exhibits high stability at high temperatures and high stability under shallow charge-discharge cycles when using an electrolyte containing the above-mentioned components.

[0045] The specific structure of 1,2,4-butanetrionitrile in this embodiment of the invention is as follows: .

[0046] The inventors analyzed that the reason why the electrolyte of the present invention, including the above-mentioned components, can improve the stability of the battery at high temperature and under shallow charge and discharge conditions is that: when the electrolyte of the present invention includes the above-mentioned components, the phosphate ester nitrile compounds can preferentially oxidize and decompose on the positive electrode surface to form an inorganic protective film (CEI film) containing phosphate groups, providing reliable high-temperature protection for the battery and inhibiting the oxidative decomposition of the electrolyte under high-temperature conditions; at the same time, the densely distributed cyano groups in the 1,2,4-butanetrionitrile molecule have extremely strong complexing ability, which can complex the transition metal ions dissolved from the positive electrode, reduce the catalytic decomposition of the electrolyte by metal ions and the damage to the SEI film of the negative electrode, and further stabilize the positive electrode interface. Through the synergistic effect of both, a uniform and dense initial CEI film of "inorganic framework + organic polymer" can be formed in the early stage of cycling, balancing its robustness and flexibility. In the later stage of high-temperature cycling, when the CEI film suffers microscopic damage due to volume changes and acid etching, 1,2,4-butanetrionitrile, with its smaller steric hindrance and stronger adsorption and complexation ability, preferentially seizes the defect sites in the film layer and completes the repair, indirectly protecting the phosphate ester nitrile compounds and inhibiting the decomposition and gas generation of free phosphate ester nitrile compounds in the electrolyte in the later stage of cycling, thus avoiding the increase in battery expansion rate and the degradation of safety performance under shallow charge and discharge conditions. At the same time, the electrolyte viscosity and impedance within this ratio range are moderate, which can ensure the stability of lithium-ion transport kinetics, without affecting the normal charge and discharge of the battery, and maintaining the integrity of the negative electrode SEI film, inhibiting the continuous lithium consumption and impedance increase caused by repeated rupture and regeneration, ultimately achieving a dual improvement in high-temperature cycling stability and shallow charge and discharge stability, and extending the battery cycle life.

[0047] If the mass percentage of phosphate ester nitrile compounds is less than 0.01 wt%, the resulting CEI film will be insufficiently thick and lack density, failing to effectively improve the battery's high-temperature cycling performance. If the mass percentage is greater than 5 wt%, it will lead to a significant increase in electrolyte impedance, affecting lithium-ion transport efficiency. Furthermore, excessive phosphate ester nitrile compounds are prone to decomposition in the later stages of high-temperature cycling, generating large amounts of gas (such as CO2 and H2), exacerbating battery expansion under shallow charge and discharge conditions, and reducing battery safety and cycle stability. If the mass percentage of 1,2,4-butanetrionitrile is less than 0.1 wt%, its ability to complex cathode metal ions and repair CEI film defects is insufficient, failing to effectively curb the decomposition and gas production of phosphate ester nitrile compounds, making it difficult to improve shallow charge and discharge performance. If the mass percentage is greater than 5 wt%, the strong coordination effect of the cyano group will dominate, resulting in an overly dense cathode CEI film, significantly increasing interfacial impedance, hindering lithium-ion transport, degrading battery low-temperature performance, and affecting ion migration efficiency during high-temperature cycling, thereby reducing the overall battery stability.

[0048] If the mass ratio of 1,2,4-butanetrionitrile to phosphate ester nitrile compounds is less than 0.1, it indicates a relative deficiency of 1,2,4-butanetrionitrile, which cannot effectively suppress the severe decomposition and gas generation of phosphate ester nitrile compounds. Under shallow charge and discharge conditions, the battery will experience significant problems such as expansion and performance degradation. If the mass ratio is greater than 100, it indicates a relative excess of 1,2,4-butanetrionitrile. In this case, although the system can greatly suppress gas generation and metal ion dissolution, the excessive cyano groups will cause the interfacial film to become too dense, further increasing the impedance and affecting the lithium-ion transport kinetics. At the same time, the excessive dilution of the phosphate ester nitrile compound content will prevent it from fully utilizing its high-temperature film-forming protection advantages, leading to a deterioration in the battery's high-temperature cycle stability and making it difficult to meet the dual requirements of high-temperature protection and shallow charge and discharge stability.

[0049] Therefore, in the battery of the present invention, by controlling the content and mass ratio of phosphate ester nitrile compounds and 1,2,4-butanetrionitrile in the electrolyte, the synergistic effect of the two in improving ion transport performance and electrolyte side reactions can be fully utilized, so that the battery can have high stability at high temperature and strong stability under shallow charge and discharge cycles.

[0050] For example, the mass percentage of phosphate nitrile compounds in the electrolyte is, for example, 0.01 wt%, 0.05 wt%, 1 wt%, 2 wt%, 3 wt%, 4 wt%, 5 wt%, or any combination thereof; the mass percentage of 1,2,4-butanetrionitrile in the electrolyte is, for example, 0.1 wt%, 1 wt%, 2 wt%, 3 wt%, 4 wt%, 5 wt%, or any combination thereof; the mass ratio of 1,2,4-butanetrionitrile to phosphate nitrile compounds is, for example, 0.1:1, 1:1, 5:1, 10:1, 20:1, 30:1, 40:1, 50:1, 60:1, 70:1, 80:1, 90:1, 100:1, or any combination thereof.

[0051] The components of the electrolyte can be tested using conventional testing methods and instruments in the art, such as gas chromatography-mass spectrometry (GC-MS) or high performance liquid chromatography (HPLC).

[0052] The electrolyte in this embodiment of the invention may include only one type of phosphate ester nitrile compound, or it may include multiple different types of phosphate ester nitrile compounds.

[0053] In some embodiments of the present invention, the phosphate ester nitrile compound accounts for 0.1wt% to 3wt% of the electrolyte, which can further improve the compactness and stability of the CEI film, better exert its high-temperature protection function, and further improve the stability and cycle life of the battery under high-temperature cycling and shallow charge-discharge conditions. For example, the phosphate ester nitrile compound accounts for 0.1wt%, 1wt%, 2wt%, 3wt%, or any combination thereof in the electrolyte.

[0054] In some embodiments of the present invention, the mass ratio of 1,2,4-butanetrionitrile to phosphate ester nitrile is (0.2~50):1, which can further enhance the synergistic protective effect of the two, and is more conducive to optimizing the battery performance under high-temperature cycling and shallow charge-discharge conditions, thereby further extending the battery's cycle life. For example, the mass ratio of 1,2,4-butanetrionitrile to phosphate ester nitrile is, for example, 0.2:1, 5:1, 10:1, 20:1, 30:1, 40:1, 50:1, or any combination thereof.

[0055] In some embodiments of the present invention, the phosphate ester nitrile compounds include the structure shown in Formula I:

[0056] Formula I

[0057] R1, R2, and R3 are each independently selected from C1-C10 alkyl groups, C1-C10 alkoxy groups, and C2-C10 alkenyl groups, whether substituted or unsubstituted, and the substituents include at least one of cyano, halogen, and phenyl.

[0058] In some embodiments of the present invention, the phosphate ester nitrile compound includes at least one of the structures shown in Formulas I-1 to I-6:

[0059] Formula I-1, Formula I-2,

[0060] Formula I-3, Formula I-4,

[0061] Formula I-5, Formula I-6.

[0062] When the electrolyte in the battery of the present invention includes the above-mentioned phosphate ester nitrile compounds, it can further optimize its oxidation film formation efficiency on the positive electrode surface, which is more conducive to forming a CEI film with a more regular structure and stronger density, further improving the stability of lithium ion transport dynamics, and better synergistically improving the stability of the battery under high temperature cycling and shallow charge and discharge conditions.

[0063] In some embodiments, the phosphate ester nitrile compound may also include one or more of tris(3-cyanopropyl) phosphate and tris(3-cyanomethyl) phosphate.

[0064] In some embodiments of the present invention, the electrolyte satisfies at least one of the following conditions:

[0065] (1) The electrolyte includes a first carboxylic acid ester, which includes at least one of ethyl propionate and propyl propionate;

[0066] (2) The electrolyte includes fluorosulfonamides, which include at least one of N,N-dimethylaminosulfonyl fluoride, N,N-diethylaminosulfonyl fluoride, N-ethyl-N-methylaminosulfonyl fluoride, N,N-di(fluoromethyl)aminosulfonyl fluoride, N,N-di(difluoromethyl)aminosulfonyl fluoride, N,N-di(trifluoromethyl)aminosulfonyl fluoride, and 1,1,1-trifluoro-N,N-dimethylmethanesulfonamide;

[0067] (3) The electrolyte includes a first carbonate, which includes at least one of vinylene carbonate, difluoroethylene carbonate, and ethylene ethylene carbonate.

[0068] In some embodiments, when the electrolyte includes a first carboxylic acid ester, and the first carboxylic acid ester includes at least one of ethyl propionate and propyl propionate, the stability of the battery under high-temperature cycling and shallow charge-discharge conditions can be further improved.

[0069] In some embodiments, when the electrolyte includes a fluorosulfonamide, and the fluorosulfonamide includes at least one of N,N-dimethylaminosulfonyl fluoride, N,N-diethylaminosulfonyl fluoride, N-ethyl-N-methylaminosulfonyl fluoride, N,N-di(fluoromethyl)aminosulfonyl fluoride, N,N-di(difluoromethyl)aminosulfonyl fluoride, N,N-di(trifluoromethyl)aminosulfonyl fluoride, and 1,1,1-trifluoro-N,N-dimethylmethanesulfonamide, the film-forming characteristics of the negative electrode interface can be better optimized, and the density and stability of the negative electrode interface film can be improved; the cycle stability of the battery under shallow charge and discharge conditions can be further enhanced, and the overall cycle life of the battery can be better extended.

[0070] In some embodiments, when the electrolyte includes a first carbonate, and the first carbonate includes at least one of vinylene carbonate (VC), difluoroethylene carbonate (DFEC), and ethylene ethylene carbonate (VEC), an elastic polymer substrate film is preferentially formed on the surface of the negative electrode to better buffer the volume expansion effect of the silicon-carbon negative electrode and further synergistically improve the stability of the battery under high-temperature cycling and shallow charge-discharge conditions.

[0071] In some embodiments of the present invention, the electrolyte satisfies at least one of the following conditions:

[0072] (1) The mass percentage of the first carboxylic acid ester in the electrolyte is 5wt%~60wt%;

[0073] (2) The ratio of the mass of the first carboxylic acid ester in the electrolyte to the total mass of the phosphate ester nitrile and 1,2,4-butanetrionitrile is (1~100):1;

[0074] (3) The mass percentage of fluorosulfonamide in the electrolyte is 2wt%~30wt%;

[0075] (4) The mass percentage of the first carbonate in the electrolyte is 0.01wt%~4wt%.

[0076] In some embodiments, when the mass percentage of the first carboxylic acid ester in the electrolyte is 5wt% to 65wt%, it can further ensure the ion transport stability of the battery under high-temperature conditions, and is more conducive to synergistically improving the battery's high and low temperature adaptability. For example, the mass percentage of the first carboxylic acid ester in the electrolyte is, for example, 5wt%, 10wt%, 20wt%, 30wt%, 40wt%, 50wt%, 60wt%, 65wt%, or any combination thereof.

[0077] In some embodiments, when the mass ratio of the first carboxylic acid ester to the total mass of the phosphate ester nitrile and 1,2,4-butanetrionitrile in the electrolyte is (1~100):1, the overall ion transport characteristics of the electrolyte can be further optimized. This is beneficial for leveraging the role of the first carboxylic acid ester in optimizing the lithium-ion solvation structure, better reducing the lithium-ion desolvation energy barrier to alleviate the problem of increased system impedance, thereby balancing the system's kinetic performance and interface protection effectiveness. This further ensures the ion transport stability of the battery under high-temperature conditions and improves the battery's stability under high-temperature cycling and shallow charge-discharge conditions. For example, the mass ratio of the first carboxylic acid ester to the total mass of the phosphate ester nitrile and 1,2,4-butanetrionitrile in the electrolyte is, for example, 1:1, 8:1, 15:1, 25:1, 35:1, 40:1, 50:1, 60:1, 70:1, 80:1, 90:1, 100:1, or any combination thereof.

[0078] In some embodiments, when the mass percentage of fluorosulfonamide in the electrolyte is 2wt% to 30wt%, it is beneficial to further improve the stability of the battery under high-temperature cycling and shallow charge-discharge conditions. For example, the mass percentage of fluorosulfonamide is, for example, 2wt%, 5wt%, 10wt%, 15wt%, 20wt%, 25wt%, 30wt%, or any combination thereof.

[0079] In some embodiments, when the mass percentage of the first carbonate in the electrolyte is 0.01wt% to 4wt%, the stability of the battery under high-temperature cycling and shallow charge-discharge conditions is improved. For example, the mass percentage of the first carbonate in the electrolyte is, for example, 0.01wt%, 0.1wt%, 0.5wt%, 1wt%, 2wt%, 3wt%, 4wt%, or any combination thereof.

[0080] In some embodiments of the present invention, the electrolyte further includes one or more of the following: a second carboxylic acid ester (mainly used as a solvent), a second carbonate (mainly used as a solvent), an ether solvent, other nitrile additives, and other additives.

[0081] In some embodiments, the second carboxylic acid ester includes one or more of ethyl acetate, propyl acetate, n-butyl acetate, isobutyl acetate, methyl propionate, ethyl n-butyrate, ethyl difluoroacetate, ethyl fluoropropionate, methyl fluorobutyrate, ethyl fluoroacetate, propyl fluoroacetate, n-butyl fluoroacetate, isobutyl fluoroacetate, methyl fluoropropionate, propyl fluoropropionate, ethyl n-butyrate, and ethyl difluoroacetate.

[0082] In some embodiments, the second carbonate includes one or more of propylene carbonate, dimethyl carbonate, diethyl carbonate, methyl ethyl carbonate, fluoropropylene carbonate, dimethyl fluorocarbonate, diethyl fluorocarbonate, and methyl ethyl fluorocarbonate.

[0083] In some embodiments, the ether solvent includes 1,1,2,2-tetrafluoroethyl-2,2,3,3-tetrafluoropropyl ether.

[0084] In some embodiments, other nitrile additives include one or more of benzonitrile, p-toluenenitrile, adiponitrile, succinate, glutaronitrile, octanoic acid nitrile, ethylene glycol bis(propionitrile) ether, 1,3,6-hexanetrionitrile (HTCN), 1,2,6-hexanetrionitrile, glycerol trionitrile, 1,2,3-tris(2-acrylonitrile ethoxy)propane, and 1,2,3-propanetricarbonitrile.

[0085] In some embodiments, other additives include one or more of the following: vinyl sulfate, 1,3-propanesulfonyl lactone, 1,3-propenesulfonate lactone, fluorovinyl carbonate, tetravinylsilane, tris(trimethylsilyl)borate, hexamethyldisilazane, fluorobenzene, triphenyl phosphite, and substances represented by Formula II:

[0086] Formula II.

[0087] When the electrolyte in the battery of the present invention includes the above-mentioned components, it can further optimize the film formation efficiency and film structure at the positive and negative electrode interfaces, and is more conducive to forming dense, stable and highly ion-conductive CEI and SEI films on the positive and negative electrode surfaces, respectively. This further suppresses the redox decomposition of the electrolyte and the loss of positive and negative electrode active materials under high-temperature conditions. At the same time, the above-mentioned additives are more conducive to improving the compatibility between the components of the electrolyte, and are more conducive to strengthening the synergistic effect with phosphate ester nitrile compounds and 1,2,4-butanetrionitrile, further reducing the side reaction gas generation during the high-temperature cycling process of the battery, and is more conducive to ensuring the stability of lithium ion transport kinetics at the positive and negative electrode interfaces and in the electrolyte.

[0088] The above-mentioned composition of the electrolyte can be tested using conventional testing methods and instruments in the art, such as gas chromatography-mass spectrometry (GC-MS), high performance liquid chromatography (HPLC), or ion chromatography.

[0089] In some embodiments of the present invention, the battery further includes a negative electrode sheet, which includes a negative electrode current collector and a negative electrode active material layer disposed on at least one side surface of the negative electrode current collector. The negative electrode active material layer includes a negative electrode active material, which includes a silicon-carbon material. The silicon-carbon material includes a coating layer. The negative electrode sheet satisfies at least one of the following conditions:

[0090] (1) The coating layer includes nitrogen, and the mass percentage of nitrogen in the silicon-carbon material is 0.05wt%~4.8wt%;

[0091] (2) The thickness of the coating layer is 1 nm to 30 nm;

[0092] (3) Silicon-carbon materials include porous carbon matrix and silicon materials deposited in porous carbon matrix.

[0093] In some embodiments, the coating layer includes nitrogen, with a nitrogen content in the silicon-carbon material ranging from 0.05 wt% to 4.8 wt%. This optimizes the number and distribution of nitrogen-containing functional groups on the silicon-carbon anode surface, allowing for strong interactions with the cyano groups of 1,2,4-butanetrionitrile (BTCN) molecules. This preferentially anchors and enriches BTCN molecules on the carbon coating layer surface. Simultaneously, this mass percentage range is more conducive to guiding the controlled decomposition of BTCN, promoting its decomposition products to participate in the construction of a dense and stable composite SEI film rich in highly ionic conductors. This further transforms BTCN from a disruptor of the anode interface into an interface enhancer, further improving the cycle stability of the battery under high-temperature cycling and shallow charge-discharge conditions. For example, the mass percentage of nitrogen in the silicon-carbon material may be, for instance, 0.05 wt%, 0.5 wt%, 1 wt%, 2 wt%, 3 wt%, 4 wt%, 4.8 wt%, or any combination thereof.

[0094] In some embodiments, when the thickness of the coating layer is 1 nm to 30 nm, it can better isolate harmful components such as nitrile additives in the electrolyte from contact with the silicon-carbon active material, further suppressing side reactions and gas generation at the negative electrode interface, further improving the interface stability of the battery under high-temperature cycling and shallow charge-discharge conditions, and further extending the long-term cycle life of the battery. For example, the thickness of the coating layer is, for example, a range of 1 nm, 5.1 nm, 10.3 nm, 15.2 nm, 20.9 nm, 25.3 nm, 30 nm, or any combination thereof.

[0095] In some embodiments, the silicon-carbon material includes a porous carbon matrix and silicon material deposited in the porous carbon matrix.

[0096] In some embodiments, the average particle size of the silicon-carbon material is 1 μm to 15 μm, which can further optimize the packing density and pore structure of the silicon-carbon anode in the electrode, thereby improving the wettability of the electrolyte inside the electrode and the lithium-ion transport efficiency, and reducing the ion transport impedance at the anode interface. Simultaneously, this particle size range is more conducive to buffering the volume expansion stress of the silicon material during cycling, maintaining the structural integrity of the silicon-carbon anode, promoting the formation of a uniform and dense composite SEI film on the anode surface, and further improving the overall performance of the battery under high-temperature cycling and shallow charge / discharge conditions, as well as the battery's long-term cycle life. For example, the average particle size of the silicon-carbon material is, for example, a range of 1 μm, 3 μm, 5 μm, 8 μm, 10 μm, 12 μm, 15 μm, or any combination thereof.

[0097] The embodiments of this invention can use conventional testing methods and instruments to test the characteristics and component distribution of the coating layer of silicon-carbon materials, such as transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS). Specifically, after the battery is fully discharged, it can be disassembled, the negative electrode sheet separated, and a sample of an appropriate amount of the negative electrode active material layer placed under a transmission electron microscope. Corresponding detection conditions are set (e.g., adjusting the accelerating voltage and magnification), and the thickness of the coating layer on the surface of the silicon-carbon material is observed and analyzed. Simultaneously, the distribution of nitrogen in the silicon-carbon material is detected, and the mass percentage of nitrogen in the silicon-carbon material and the actual thickness of the coating layer are calculated. The pretreated silicon-carbon material sample is then placed under an X-ray photoelectron spectrometer, and corresponding detection conditions are set (e.g., adjusting the X-ray source power and detection pass power). The chemical state of nitrogen-containing functional groups (e.g., -C≡N, -CN-) in the coating layer is detected, and the composite structural characteristics of the porous carbon matrix and silicon material in the silicon-carbon material are verified.

[0098] In some embodiments of the present invention, the battery further includes a positive electrode sheet, which includes a positive current collector and a positive active material layer disposed on at least one side surface of the positive current collector. The positive active material layer includes a positive active material, which includes lithium cobalt oxide.

[0099] In some embodiments, the lithium cobalt oxide material includes at least one of Ni and Mn elements; preferably, the mass percentage of Ni in the lithium cobalt oxide material is 100ppm to 3000ppm; preferably, the mass percentage of Mn in the lithium cobalt oxide material is 100ppm to 5000ppm, which can further optimize the lattice regularity of the lithium cobalt oxide material, better enhance the intrinsic structural stability of the lithium cobalt oxide material, better improve its structural retention capability under high voltage charge and discharge conditions, further improve the working voltage platform of the battery, and is more conducive to adapting to the electrochemical system of high voltage lithium cobalt oxide / silicon-carbon batteries. For example, the mass percentage of Ni in lithium cobalt oxide materials is, for example, a range of 100 ppm, 534 ppm, 1021 ppm, 1554 ppm, 2123 ppm, 3000 ppm, or any two of these; the mass percentage of Mn in lithium cobalt oxide materials is, for example, a range of 200 ppm, 407 ppm, 634 ppm, 813 ppm, 1081 ppm, 2001 ppm, 3034 ppm, 4000 ppm, 5000 ppm, or any two of these.

[0100] In this embodiment of the invention, the above-mentioned lithium cobalt oxide material can be synthesized using conventional methods in the art, for example, by the following method:

[0101] Step 1: Mix the first Co source and the first Li source with specific Mn and Ni contents evenly, and perform the first sintering in a dry air atmosphere. The sintering temperature is 900℃-1050℃ and the sintering time is 8h-12h. After sintering, allow it to cool naturally to room temperature.

[0102] The second step involves uniformly mixing a second Co source and a second Li source with specific Mn and Ni contents, and then performing a second sintering in a dry air atmosphere at a sintering temperature of 900℃-1050℃ for 5-10 hours. After sintering, the mixture is allowed to cool naturally to room temperature.

[0103] In some embodiments, the above-mentioned lithium cobalt oxide material may be further doped with other elements, such as one or more of Al, Ti, La, Y, and Zr. The preparation method of the above-mentioned lithium cobalt oxide material further includes a third step: mixing the materials prepared in the first step and the second step evenly, adding an optional first Al source, a first Ti source, a first La source, a first Y source, and a second Zr source for a third sintering, the sintering temperature being 700℃-950℃, the sintering time being 1h-5h, and naturally cooling to room temperature to obtain the lithium cobalt oxide of the present invention.

[0104] In this embodiment of the invention, the term "optional" means that it can be added or not.

[0105] In this embodiment of the invention, in the third step, the materials obtained in the first and second steps can be mixed in any mass ratio.

[0106] In the embodiments of the present invention, the first Co source and the second Co source each independently include at least one of cobalt tetroxide, cobalt hydroxide, and cobalt carbonate; the first Li source and the second Li source each independently include at least one of lithium carbonate and lithium fluoride; the first Al source includes at least one of Al2O3, Al(OH)3, Al2(SO4)3, Al2(CO3)3, and Al(NO3)3; the first Ti source includes at least one of TiO2, TiF4, TiCl3, Ti(OH)4, Ti(CO3)2, and Ti(SO4)2; the first La source includes at least one of La2O3, La(OH)3, La(CO3)3, La2(SO4)3, LaTiO3, and LaZrO3; the first Y source includes at least one of Y2O3, Y(OH)3, Y2(CO3)3, Y2(SO4)3, and Y(NO3)3; and the first Zr source and the second Zr source each independently include at least one of zirconium oxide and zirconium hydroxide.

[0107] In one specific embodiment, the first Al source includes Al2(SO4)3.

[0108] In the embodiments of the present invention, the specific amounts of materials used are as described above, and will not be repeated here.

[0109] In some embodiments, the Dv50 of the lithium cobalt oxide material is 5 μm to 25 μm. For example, the Dv50 of the lithium cobalt oxide material is, for example, a range of 5 μm, 8.1 μm, 10.5 μm, 15.3 μm, 20.9 μm, 25 μm or any combination thereof.

[0110] The embodiments of this invention can employ conventional testing methods and instruments in the art to test the structural and compositional characteristics of the positive electrode active material layer and the positive electrode active material therein. For example, testing can be performed using inductively coupled plasma optical emission spectrometry (ICP-OES) and scanning electron microscopy (SEM). Specifically, after the battery is fully discharged, it can be disassembled, the positive electrode sheet separated, and a suitable sample of the positive electrode active material layer placed under an X-ray diffractometer. Corresponding detection conditions are set (such as adjusting the scanning angle range and scanning rate) to verify the doping ratio of Ni and Mn elements in the lithium cobalt oxide material. The sample is then placed under a scanning electron microscope, and corresponding detection conditions are set (such as adjusting the accelerating voltage and magnification) to observe the Dv50 of the lithium cobalt oxide material in the positive electrode active material layer. Energy dispersive X-ray spectroscopy (EDS) can also be used to confirm the lithium cobalt oxide material.

[0111] In some embodiments of the present invention, the battery further includes a separator, the separator including a separator substrate and an inorganic coating disposed on at least one side surface of the separator substrate; the inorganic coating includes inorganic materials, including one or more of aluminum oxide, boehmite, silicon dioxide, zirconium dioxide, barium sulfate, magnesium hydroxide, fluorapatite, fluorophlogopite, mullite, aluminum titanate, copper oxide, titanium dioxide, and zinc oxide.

[0112] In some embodiments, the membrane substrate may be selected from commonly used base membrane materials in the art, including but not limited to polyethylene (PE), polypropylene (PP), and PP and PE composite membranes, which is beneficial to further improve the mechanical properties of the membrane.

[0113] In some embodiments, the inorganic coating further includes an adhesive, which includes one or more of polyvinylidene fluoride and polyacrylate.

[0114] In some embodiments of the present invention, the charging cut-off voltage of the battery is greater than or equal to 4.5V, which is more conducive to leveraging the high specific capacity advantage of lithium cobalt oxide / silicon-carbon batteries and better adapting to the application requirements of high energy density and high operating voltage batteries.

[0115] Generally, a battery includes an electrolyte, a battery cell, and a casing that encapsulates the battery cell. The electrolyte is injected into the battery cell inside the casing. The battery cell includes a positive electrode, a negative electrode, and a separator located between the positive and negative electrode. The battery cell can be a stacked cell, meaning it is composed of alternating layers of positive electrode, separator, and negative electrode; or it can be a wound cell, meaning it is composed of stacked positive electrode, separator, and negative electrode, which are then wound together.

[0116] 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.

[0117] In some embodiments, the positive electrode active material layer comprises, by mass percentage, 80% to 99.8% positive electrode active material, 0.1% to 10% positive electrode conductive agent, and 0.1% to 10% positive electrode binder.

[0118] In this embodiment of the invention, the positive electrode conductive agent may include one or more of conductive carbon black, conductive graphite, carbon nanotubes (CNTs), carbon fibers, graphene, acetylene black, and Ketjen black.

[0119] In this embodiment of the invention, the positive electrode binder may include 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, polyurethane, etc.

[0120] The embodiments of the present invention may employ conventional positive current collectors in the art, for example, positive current collectors may include aluminum foil.

[0121] In some embodiments, the negative electrode active material layer may include a negative electrode active material, a negative electrode conductive agent, and a negative electrode binder, all of which can be conventional materials in the art. For example, the negative electrode conductive agent may include one or more of conductive carbon black, carbon nanotubes (CNT), acetylene black, graphene, Ketjen black, and carbon fiber; the negative electrode binder may include one or more of sodium carboxymethyl cellulose (CMC), styrene-butadiene rubber (SBR), polyvinyl chloride, carboxylated polyvinyl chloride, polyvinyl fluoride, ethylene oxide-containing polymers, polyvinylpyrrolidone, polyurethane, polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, polypropylene, polyamide-imide, polyvinyl alcohol, and sodium polyacrylate.

[0122] In the negative electrode active material layer, by mass percentage, the negative electrode active material is 80~98.5wt%, the negative electrode conductive agent is 0.1~10wt%, and the negative electrode binder is 0.1~10wt%.

[0123] 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.

[0124] 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 coming into contact and short-circuiting.

[0125] This invention also provides an electrical device including the battery described above, which has advantages corresponding to the battery described above, and will not be described in detail here.

[0126] The electrical equipment used in the embodiments of the present invention can be conventional electrical equipment in the art, such as power equipment (e.g., electric vehicles, electric cars), electronic equipment (e.g., mobile phones, tablets, laptops, digital cameras, etc.), wearable devices (e.g., watches, bracelets, VR glasses, etc.), energy storage power stations, etc., and there are no particular limitations on this.

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

[0128] Example 1

[0129] The battery in this embodiment is prepared through the following process:

[0130] 1) Preparation of positive electrode sheet

[0131] Lithium cobalt oxide (LiCoO2, Dv50 of 12.1 μm, with Ni content of 1031 ppm and Mn content of 1802 ppm), carbon black, polyvinylidene fluoride, and N-methylpyrrolidone were dispersed in N-methylpyrrolidone at a mass ratio of 97.2:1.0:1.3 and stirred thoroughly to obtain a uniform positive electrode slurry. The positive electrode slurry was coated onto the surface of the positive electrode current collector, and after drying, rolling, and cutting, a positive electrode sheet was obtained.

[0132] 2) Preparation of negative electrode sheet

[0133] Weigh out the negative electrode active material graphite, silicon carbon material (silicon content of 12wt%, nitrogen element in silicon carbon material mass ratio of 2wt%, silicon carbon material including coating layer, coating layer thickness of 15.3nm), carbon black, styrene-butadiene rubber, and thickener sodium carboxymethyl cellulose, and disperse them in deionized water at a mass ratio of 67:30:0.8:1.2:1. Stir thoroughly to obtain a uniform negative electrode slurry. Coat the negative electrode slurry onto the surface of the negative electrode current collector copper foil, and obtain the negative electrode sheet after drying, rolling and cutting.

[0134] 3) Electrolyte preparation: In an argon-atmospheric glove box (water content < 0.1 ppm, oxygen content < 0.1 ppm), first mix the solvents ethylene carbonate (EC), propylene carbonate (PC), ethyl propionate (EP), propyl propionate (PP), and N,N-dimethylaminosulfonyl fluoride (DMSF) thoroughly; then add 14 wt% lithium hexafluorophosphate (LiPF6) and 6 wt% lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) based on the total mass of the electrolyte to the mixed solvent, and stir until completely dissolved; subsequently add 10 wt% fluoroethylene carbonate (FEC), 1 wt% of compound I-1, and 1.5 wt% of other compounds based on the total mass of the electrolyte. wt% of 1,2,4-butanetrionitrile (BTCN), 0.5wt% of vinylene carbonate (VC), 1.5wt% of 1,3,6-hexanetrionitrile (HTCN), 1wt% of succinic anionyl (SN), and 1wt% of the sulfur-containing heterocyclic compound shown in Formula II were thoroughly stirred until homogeneous. After testing, the water and free acid content of the electrolyte met the standards, and a non-aqueous electrolyte was obtained. The mass percentage of the first carboxylic acid ester EP and PP (ratio 1:2) was 5%, the mass percentage of DMSF was 10%, and the balance was EC and PC (ratio 1:1). The total mass ratio of the first carboxylic acid ester to the phosphate nitrile compound and BTCN was 2.

[0135] 4) The diaphragm is made of polyethylene (PE).

[0136] 5) Assembly of lithium-ion batteries: The positive electrode, separator and negative electrode prepared above are stacked in sequence, with the separator placed between the positive electrode and the negative electrode. After welding the tabs, the batteries are wound to obtain the battery core. The core is placed in an aluminum-plastic film packaging bag, and the processes of liquid injection, formation, secondary packaging and sorting are completed in sequence to obtain the lithium-ion battery.

[0137] The differences between Examples 2-22 and Example 1 are shown in Tables 1 and 2. In the electrolytes of the above examples and comparative examples, where the composition of each component in the electrolyte has changed compared to Example 1, the mass of each component that has decreased or increased corresponds to an increase or decrease in the mass of EC and PC.

[0138]

[0139]

[0140] 45℃ Cyclic Performance Test: The lithium-ion batteries prepared in the above examples and comparative examples were placed in a constant temperature environment of 45℃ and left to stand for 10 minutes. After the battery temperature stabilized at 45±2℃, they were charged at a constant current of 1C to the upper limit voltage (4.53V), and then charged at a constant voltage of 4.53V to 0.05C, and left to stand for 5 minutes. Next, they were discharged at a constant current of 0.5C to 3V, and the discharge capacity at this time was recorded as Q1. After standing for 5 minutes, this was one charge-discharge cycle. The above process constituted one complete charge-discharge cycle, and a total of 400 charge-discharge cycles were performed. The highest discharge capacity of the first 3 charge-discharge cycles was recorded as the initial capacity Q1, and the discharge capacity of the 400th charge-discharge cycle was recorded as Q2. The battery performance parameters were calculated according to the following formula: Capacity retention rate = Q2 / Q1×100%. The test results (capacity retention rate) are shown in Table 3.

[0141] 45℃ Shallow Charge-Discharge Cycle Performance Test: The lithium-ion batteries prepared in the above examples and comparative examples were placed in a constant temperature environment of 45℃ and left to stand for 1 hour. After the battery temperature stabilized at 45±2℃, they were discharged at a rate of 0.2C to 3.0V. After the discharge was completed, they were left to stand for 10 minutes. Then, they were charged at a rate of 1.5C to 4.25V (current cutoff condition was 1.5C), and continued to be charged at a rate of 1.5C to the upper limit voltage of 4.53V (current cutoff was 0.05C). Then, they were charged at a constant voltage of 4.53V until the current dropped to 0.05C. After the charging was completed, they were left to stand for 10 minutes. Then, they were discharged at a rate of 0.05C until the remaining battery capacity was 95% SOC, and then charged at a rate of 0.5C to full charge (current cutoff was 0.05C). After the charging was completed, they were left to stand for 10 minutes. The above process constitutes a complete shallow charge-discharge cycle. A total of 1000 shallow charge-discharge cycles were performed. Record the initial battery thickness H3 before the first cycle and the battery thickness H4 after 1000 cycles, and observe whether the battery exhibits bulging. Calculate the battery's 45℃ shallow charge / discharge expansion rate using the following formula: 45℃ shallow charge / discharge expansion rate = (1 - H4 / H3) × 100%. The test results (thickness expansion rate) are shown in Table 3. The thickness expansion rate curves of the batteries in Example 1 and Comparative Example 1 during the 45℃ shallow charge / discharge cycle performance test are shown in the figure. Figure 1 As shown, by Figure 1 It can be seen that, compared with Comparative Example 1, the battery of Example 1 has stronger stability under the conditions of high temperature shallow charge and shallow discharge.

[0142] The charging cutoff voltage of the batteries prepared in the embodiments and comparative examples of this invention is greater than or equal to 4.5V.

[0143]

[0144] As shown in Table 3, compared with the comparative example, the embodiments of the present invention, by adding phosphate ester nitrile compounds and 1,2,4-butanetrionitrile to the electrolyte of the battery and controlling their content and mass ratio, enable the battery to have a higher capacity retention rate at high temperature, a smaller thickness expansion rate under high temperature shallow charge and discharge cycles, and stronger stability.

[0145] 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 in that, The electrolyte includes a phosphate ester nitrile compound and 1,2,4-butanetrionitrile; The phosphate ester nitrile compound accounts for 0.01 wt% to 5 wt% of the mass of the electrolyte. The 1,2,4-butanetrionitrile in the electrolyte comprises 0.1 wt% to 5 wt% by mass. The mass ratio of the 1,2,4-butanetrionitrile to the phosphate ester nitrile is (0.1~100):

1.

2. The battery according to claim 1, characterized in that, The phosphate ester nitrile compound accounts for 0.1 wt% to 3 wt% of the mass in the electrolyte; And / or, the mass ratio of the 1,2,4-butanetrionitrile to the phosphate ester nitrile is (0.2~50):

1.

3. The battery according to claim 2, characterized in that, The phosphate ester nitrile compounds include the structure shown in Formula I: Equation I R1, R2, and R3 are each independently selected from C1-C10 alkyl groups, C1-C10 alkoxy groups, and C2-C10 alkenyl groups, whether substituted or unsubstituted, and the substituents include at least one of cyano, halogen, and phenyl.

4. The battery according to claim 3, characterized in that, The phosphate ester nitrile compounds include at least one of the structures shown in Formulas I-1 to I-6: Equation I-1, Equation I-2, Equation I-3, Formula I-4, Formula I-5, Formula I-6.

5. The battery according to any one of claims 1-4, characterized in that, The electrolyte satisfies at least one of the following conditions: (1) The electrolyte comprises a first carboxylic acid ester, wherein the first carboxylic acid ester comprises at least one of ethyl propionate and propyl propionate; (2) The electrolyte comprises fluorosulfonamide, which comprises at least one of N,N-dimethylaminosulfonyl fluoride, N,N-diethylaminosulfonyl fluoride, N-ethyl-N-methylaminosulfonyl fluoride, N,N-di(fluoromethyl)aminosulfonyl fluoride, N,N-di(difluoromethyl)aminosulfonyl fluoride, N,N-di(trifluoromethyl)aminosulfonyl fluoride, and 1,1,1-trifluoro-N,N-dimethylmethanesulfonamide; (3) The electrolyte includes a first carbonate, which includes at least one of vinylene carbonate, difluoroethylene carbonate, and ethylene ethylene carbonate.

6. The battery according to claim 5, characterized in that, The electrolyte satisfies at least one of the following conditions: (1) The mass percentage of the first carboxylic acid ester in the electrolyte is 5wt%~60wt%; (2) The ratio of the mass of the first carboxylic acid ester in the electrolyte to the total mass of the phosphate ester nitrile and the 1,2,4-butanetrionitrile is (1~100):1; (3) The mass percentage of the fluorosulfonamide in the electrolyte is 2wt%~30wt%; (4) The mass percentage of the first carbonate in the electrolyte is 0.01wt%~4wt%.

7. The battery according to any one of claims 1-6, characterized in that, The battery further includes a negative electrode sheet, the negative electrode sheet including a negative electrode current collector and a negative electrode active material layer disposed on at least one surface of the negative electrode current collector, the negative electrode active material layer including a negative electrode active material, the negative electrode active material including a silicon-carbon material, the silicon-carbon material including a coating layer, and the negative electrode sheet satisfying at least one of the following conditions: (1) The coating layer includes nitrogen, and the mass percentage of nitrogen in the silicon-carbon material is 0.05 wt% to 4.8 wt%. (2) The thickness of the coating layer is 1 nm to 30 nm; (3) The silicon-carbon material includes a porous carbon matrix and silicon material deposited in the porous carbon matrix.

8. The battery according to any one of claims 1-7, characterized in that, The battery further includes a positive electrode sheet, which includes a positive current collector and a positive active material layer disposed on at least one side surface of the positive current collector. The positive active material layer includes a positive active material, which includes lithium cobalt oxide.

9. The battery according to claim 8, characterized in that, The lithium cobalt oxide material includes at least one of Ni and Mn elements; Preferably, the Ni element in the lithium cobalt oxide material has a mass ratio of 100ppm to 3000ppm; preferably, the Mn element in the lithium cobalt oxide material has a mass ratio of 100ppm to 5000ppm.

10. The battery according to any one of claims 1-9, characterized in that, The charging cutoff voltage of the battery is greater than or equal to 4.5V.

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