Battery and electric equipment

Abstract

The invention provides a battery and electric equipment, the battery comprises a negative plate and an electrolyte, the negative plate comprises a negative current collector and a negative active material layer arranged on at least one side surface of the negative current collector, the negative active material layer comprises a negative active material and an inducer, and the inducer comprises an oxygen-containing group compound; in the length direction of the negative electrode active material layer, the negative electrode active material layer comprises a central region and edge regions located on the two opposite sides of the central region; the mass ratio of the inducer in the central area is larger than that of the inducer in the edge area, and the electrolyte comprises cyclic carbonate. According to the invention, the uniformity of the SEI film can be effectively improved, and the cycle service life of the battery is prolonged.

Description

Technical Field

[0001] The present invention belongs to the technical field of lithium-ion batteries, and in particular relates to a battery and electrical equipment. Background Art

[0002] Batteries are common electrochemical devices with a wide range of applications. Cyclic carbonates, as negative electrode active materials and electrolyte additives, are crucial components of batteries, impacting performance such as cycle life. However, existing technologies, limited by the actual battery cycle process, exhibit uneven distribution of cyclic carbonates on the surface of the negative electrode active material layer, with high cyclic carbonate content at the end regions and low cyclic carbonate content at the center. This results in impeded lithium ion conduction in the center region, increased current density at the end regions, and an uneven SEI film. These defects, such as reduced cycle life, are common in batteries and urgently need to be addressed. Summary of the Invention

[0003] The present invention provides a battery and an electrical device to at least solve the problem in the prior art that uneven SEI film formation leads to a decrease in the cycle life of the battery.

[0004] The present invention provides a battery, comprising a negative electrode sheet and an electrolyte, wherein the negative electrode sheet comprises a negative electrode current collector and a negative electrode active material layer disposed on at least one side of the negative electrode current collector, wherein the negative electrode active material layer comprises a negative electrode active substance and an inducer, wherein the inducer comprises an oxygen-containing group compound;

[0005] Along the length direction of the negative electrode active material layer, the negative electrode active material layer includes a central region and edge regions located on opposite sides of the central region;

[0006] The mass proportion of the inducer in the central area is greater than the mass proportion of the inducer in the edge area;

[0007] The electrolyte includes a cyclic carbonate.

[0008] According to one embodiment of the present invention, the edge region includes N sub-edge regions distributed along the length direction of the negative electrode active material layer, N≥1, and the mass proportion of the inducer in the sub-edge region decreases successively from the central region to the edge region.

[0009] According to one embodiment of the present invention, the mass percentage of the inducer in the edge region is 0%-10%;

[0010] And / or, the mass percentage of the inducer in the central area is 0.001%-20%.

[0011] According to one embodiment of the present invention, the ratio of the area of ​​the central region to the area of ​​the negative electrode active material layer is (0.4-0.9):1;

[0012] And / or, the ratio of the area of ​​the edge region to the area of ​​the negative electrode active material layer is (0.1-0.6):1.

[0013] According to one embodiment of the present invention, the oxygen-containing group compound includes an oxygen-containing group, and the oxygen-containing group includes a hydroxyl group, an alkoxy group, an aldehyde group, an acetyl group, a carboxyl group, an acid anhydride group, an O - , O 2- OH - One or more of .

[0014] According to one embodiment of the present invention, the oxygen-containing group compound includes one or more of polyvinyl alcohol, phthalic anhydride, butyleneoxycyclotriphosphine, tetrafluoropropyl methacrylate, metal hydroxide, tetrabutylammonium hydroxide, and aluminum isopropoxide.

[0015] According to one embodiment of the present invention, the cyclic carbonate includes vinylene carbonate.

[0016] According to one embodiment of the present invention, the negative electrode active material includes one or more of graphite, carbon black, hard carbon, and soft carbon.

[0017] According to one embodiment of the present invention, the thickness of the negative electrode active material layer is 0.02 mm-0.12 mm.

[0018] According to one embodiment of the present invention, the negative electrode active material layer further includes one or more of a conductive agent, a binder, and a dispersant.

[0019] Another aspect of the present invention provides a battery comprising the above-mentioned negative electrode sheet.

[0020] Another aspect of the present invention provides an electrical device comprising the above-mentioned battery or the above-mentioned battery pack.

[0021] The present invention provides a battery and electrical equipment. In a negative electrode sheet, a negative electrode active material layer includes a negative electrode active substance and an inducer, wherein the inducer includes an oxygen-containing compound. Along the length of the negative electrode active material layer, the negative electrode active material layer includes a central region and edge regions located on opposite sides of the central region, wherein the mass proportion of the inducer in the central region is greater than the mass proportion of the inducer in the edge regions. The electrolyte includes vinylene carbonate. Under this negative electrode sheet composition system, the oxygen-containing compound in the negative electrode active material layer can induce the ring opening of cyclic carbonate, increase the film formation rate of the cyclic carbonate, form a stable SEI film, and promote the diffusion of the cyclic carbonate into the central region of the negative electrode active material layer, significantly improving the uniformity of the SEI film and reducing polarization increase, thereby increasing the cycle life of the battery. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 Schematic diagram of the structure of the first active material of the present invention;

[0023] Figure 2 Schematic diagram of the structure of the negative electrode sheet in some embodiments of the present invention;

[0024] Figure 3 Schematic diagram of the structure of the negative electrode sheet in some embodiments of the present invention.

[0025] Description of reference numerals:

[0026] 1 Negative electrode active material; 2 Inducer; 3 First edge region of the negative electrode active material layer; 4 Central region of the negative electrode active material layer; 5 Second edge region of the negative electrode active material layer; 6 Tab; 7 Negative electrode current collector; d x : width of the negative electrode active material layer in the first direction; d y : length of the negative electrode active material layer in the second direction; d z : thickness of the negative electrode active material layer in the third direction; d y1 : length of the first edge region of the negative electrode active material layer in the second direction; d y2 : length of the central region of the negative electrode active material layer in the second direction; d y3 : length of the second edge region of the negative electrode active material layer in the second direction; x: first direction; y: second direction; z: third direction. DETAILED DESCRIPTION

[0027] In order to enable those skilled in the art to better understand the scheme of the present invention, the present invention is further described in detail below. The specific embodiments listed below are only for describing the principles and features of the present invention. The examples are only used to explain the present invention and are not intended to limit the scope of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative efforts are within the scope of protection of the present invention.

[0028] In the related art, due to the limitations of the actual battery cycle process, the cyclic carbonate is unevenly distributed on the surface of the negative electrode active material layer, showing that the cyclic carbonate content in the end area of ​​the negative electrode active material layer is high, and the cyclic carbonate content in the central area is low, resulting in the obstruction of lithium ion conduction in the central area, increased current density in the end area, and uneven SEI film, which makes the battery generally have defects such as reduced cycle life, which needs to be solved urgently.

[0029] In view of this, an embodiment of the present invention provides a battery, comprising a negative electrode sheet and an electrolyte, the negative electrode sheet comprising a negative electrode current collector and a negative electrode active material layer arranged on at least one side surface of the negative electrode current collector, the negative electrode active material layer comprising a negative electrode active substance and an inducer, the inducer comprising an oxygen-containing group compound; along the length direction of the negative electrode active material layer, the negative electrode active material layer comprises a central region, and edge regions located on opposite sides of the central region; the mass proportion of the inducer in the central region is greater than the mass proportion of the inducer in the edge region; the electrolyte comprises cyclic carbonate.

[0030] By introducing an inducer into the negative electrode active material layer and controlling the mass proportion of the inducer in the center region to be greater than the mass proportion of the inducer in the edge region, the cycle life of the battery can be significantly improved. The reason for this is that the oxygen-containing group compound can induce the ring opening of the cyclic carbonate, increase the film formation rate of the cyclic carbonate, and form a stable SEI film. At the same time, the mass proportion of the inducer in the center region is greater than the mass proportion of the inducer in the edge region, which can promote the diffusion of the cyclic carbonate to the center region of the negative electrode active material layer, improve the uniformity of the SEI film, reduce the polarization increase phenomenon, and thus improve the cycle life of the battery.

[0031] The embodiment of the present invention does not impose any special limitation on the shapes of the central region and the edge region divided by the negative electrode active material layer. For example, the shapes may be square, rectangular, trapezoidal, etc.

[0032] In the embodiment of the present invention, the inducer is present on the surface of the negative electrode active material, and the form of the inducer on the surface of the negative electrode active material is not particularly limited. Figure 1 As shown, the inducer 2 can be coated on the surface of the negative electrode active material 1 to form a first active material.

[0033] like Figure 2 and Figure 3 As shown, the negative electrode active material layer is divided into three regions along the second direction (i.e., the length direction of the negative electrode active material layer) from the side close to the negative electrode tab 6 to the side away from the negative electrode tab 6: a first edge region 3, a central region 4, and a second edge region 5. The mass proportion of the inducer in the first edge region 3 is x1, the mass proportion of the inducer in the central region 4 is x2, and the mass proportion of the inducer in the second edge region 5 is x3, wherein x2>x1, x2>x3. By increasing the mass proportion of the inducer in the central region of the negative electrode active material layer, the induction of the ring-opening reaction of the cyclic carbonate by the oxygen-containing group compound in the central region can be accelerated, the film formation rate of the cyclic carbonate can be increased, and the diffusion of the cyclic carbonate in the first and second edge regions to the central region can be promoted, thereby improving the uniformity of the SEI film and thus increasing the cycle life of the battery. Furthermore, the width d of the negative electrode active material layer in the first direction x is x The length d of the negative electrode active material layer in the second direction y is 60 mm to 300 mm. y The thickness d of the negative electrode active material layer in the third direction z is 300 mm to 1000 mm. z The length d of the first edge region in the negative electrode active material layer in the second direction is 0.02 mm to 0.12 mm. y1 The length d of the central area of ​​the negative electrode active material layer in the second direction is 10 mm to 500 mm. y2 The length d of the second edge region in the negative electrode active material layer in the second direction is 10 mm to 900 mm. y3 10mm-500mm.

[0034] In some embodiments, the edge region includes N sub-edge regions distributed along the length direction of the negative electrode active material layer, N ≥ 1, and the mass proportion of the inducer in the sub-edge region decreases in sequence from the center region to the edge region (e.g. Figure 2 As shown in the figure, the arrow indicates the direction from the center area to the edge area), which is conducive to better improving the uniformity of the SEI film and further increasing the cycle life of the battery.

[0035] For example, N can be 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, or 11. For example, when N=2, the edge region includes a first edge region and a second edge region distributed along the length direction of the negative electrode active material layer. By regulating the mass percentage of the inducer in the edge region, the mass percentage of the inducer in the central region, the ratio of the area of ​​the central region to the area of ​​the negative electrode active material layer, and the ratio of the area of ​​the edge region to the area of ​​the negative electrode active material layer, the uniformity of the SEI film can be further improved, thereby further increasing the cycle life of the battery.

[0036] In the embodiment of the present invention, the area of ​​the negative electrode active material layer is equal to the sum of the area of ​​the central region and the area of ​​the edge region.

[0037] In some embodiments, the weight percentage of the inducer in the edge region is 0%-10%.

[0038] For example, the mass percentage of the inducer in the edge region may be 0%, 1%, 2%, 4%, 6%, 8% or 10%, etc.

[0039] In some embodiments, the mass percentage of the inducer in the central region is 0.001%-20%.

[0040] For example, the mass percentage of the inducer in the central region can be 0.001%, 0.1%, 1%, 3%, 6%, 9%, 12%, 15%, 18% or 20%, etc.

[0041] In some embodiments, the ratio of the area of ​​the central region to the area of ​​the negative electrode active material layer is (0.4-0.9):1.

[0042] For example, the ratio of the area of ​​the central region to the area of ​​the negative electrode active material layer may be 0.4:1, 0.5:1, 0.6:1, 0.7:1, 0.8:1, or 0.9:1.

[0043] In some embodiments, the ratio of the area of ​​the edge region to the area of ​​the negative electrode active material layer is (0.1-0.6):1.

[0044] For example, the ratio of the area of ​​the edge region to the area of ​​the negative electrode active material layer may be 0.1:1, 0.2:1, 0.3:1, 0.4:1, 0.5:1, or 0.6:1.

[0045] In some embodiments, the oxygen-containing group compound includes an oxygen-containing group, and the oxygen-containing group includes a hydroxyl group, an alkoxy group, an aldehyde group, an acetyl group, a carboxyl group, an acid anhydride group, an O - , O 2- OH - One or more of the above can better induce the ring-opening reaction of the cyclic carbonate, promote the diffusion of the cyclic carbonate to the central area of ​​the negative electrode active material layer, and extend the cycle life of the battery.

[0046] In some embodiments, the oxygen-containing group compound includes one or more of polyvinyl alcohol, phthalic anhydride, butyleneoxycyclotriphosphine, tetrafluoropropyl methacrylate, metal hydroxide, tetrabutylammonium hydroxide, and aluminum isopropoxide.

[0047] In some embodiments, the cyclic carbonate includes vinylene carbonate (VC), which is conducive to forming a dense and uniform SEI film, thereby further improving the cycle life of the battery.

[0048] In some embodiments, the negative electrode active material includes one or more of graphite, carbon black, hard carbon, and soft carbon, which is beneficial to improving the conductivity of the electrode sheet and the energy density of the battery.

[0049] In some embodiments, the thickness of the negative electrode active material layer is 0.02 mm to 0.12 mm, which can shorten the transmission path of lithium ions and electrons, while improving the energy density and cycle life of the battery.

[0050] For example, the thickness of the negative electrode active material layer may be 0.02 mm, 0.03 mm, 0.04 mm, 0.05 mm, 0.06 mm, 0.07 mm, 0.08 mm, 0.09 mm, 0.10 mm, 0.11 mm, or 0.12 mm.

[0051] In embodiments of the present invention, the thickness of the negative electrode active material layer is typically measured using a scanning electron microscope (SEM). Specifically, after the battery is discharged and the negative electrode sheet is removed from the battery, the negative electrode active material layer is scraped off the negative electrode sheet. The scraped negative electrode active material is placed on the SEM sample stage for SEM testing. The thickness is measured perpendicular to the negative electrode active material layer using the measurement tools in the SEM software. The thickness of 100 negative electrode active material layers is read and the average value is calculated as the negative electrode active material layer thickness test result.

[0052] In some embodiments, in order to improve the structural stability and conductivity of the negative electrode active material layer, the negative electrode active material layer further includes one or more of a conductive agent, a binder, and a dispersant.

[0053] In some embodiments, the mass percentage of the binder in the negative electrode active material layer can be 1% to 5%, for example, 1%, 1.5%, 2.0%, 2.5%, 3.0%, 3.5%, 4.0%, 4.5%, 5.0% or a range composed of any two thereof. By controlling the binder content in the negative electrode active material layer within the above range, it is beneficial to improve the structural stability of the negative electrode sheet, and at the same time, it will not squeeze out the content of other components such as the negative electrode active material, which is beneficial to improving the overall performance of the negative electrode sheet.

[0054] In some embodiments, the mass percentage of the conductive agent in the negative electrode active material layer can be 0.1% to 20%, for example, 0.1%, 1%, 3%, 5%, 7%, 10%, 13%, 15%, 18%, 20% or any two thereof.

[0055] In some embodiments, the mass percentage of the dispersant in the negative electrode active material layer can be 1% to 5%, for example, 1%, 1.5%, 2.0%, 2.5%, 3.0%, 3.5%, 4.0%, 4.5%, 5.0% or a range consisting of any two thereof.

[0056] In the embodiment of the present invention, the negative electrode active material layer may be provided on one surface of the negative electrode current collector in the thickness direction, or on two opposite surfaces of the negative electrode current collector in the thickness direction.

[0057] In the embodiment of the present invention, the binder in the negative electrode active material layer can be any binder suitable for the negative electrode known in the art. For example, the binder in the negative electrode active material layer can include 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 (for example, polyethylene-polyethylene glycol block copolymers, etc.), polyethers and their copolymers (for example, polyethylene oxide, etc.), polyphenylene ethers and their copolymers, polysiloxanes and their copolymers (for example, polydimethylsiloxane, poly(dimethylsiloxane-co-alkylmethylsiloxane), etc.), polyesters and their copolymers (for example, polyvinyl ester, polyvinyl acetate, polyacrylate, etc.), carboxymethyl cellulose, styrene-butadiene latex, nitrile rubber, and polyacrylic acid (PAA). Specifically, the polyolefin includes one or more of polyethylene, polypropylene, ethylene / propylene copolymer, ethylene / vinylidene fluoride copolymer, and propylene / vinylidene fluoride copolymer; polytetrafluoroethylene and its copolymers can 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.

[0058] In an embodiment of the present invention, the conductive agent in the negative electrode active material layer may be a conventional conductive material in the art. For example, the conductive agent in the negative electrode active material layer may include one or more of conductive carbon black, conductive graphite, carbon nanotubes (CNTs), carbon fibers, graphene, acetylene black, and Ketjen black.

[0059] In the embodiment of the present invention, the dispersant in the negative electrode active material layer may be a conventional dispersant in the art. For example, the dispersant in the negative electrode active material layer may include one or more of carboxymethyl cellulose, polycarboxylate, polyacrylate, polyacrylate, and polyvinyl alcohol.

[0060] The embodiment of the present invention may adopt a conventional negative electrode current collector in the art, for example, the negative electrode current collector includes copper foil.

[0061] In some embodiments, the negative electrode sheet is prepared by a wet process, and its preparation method may include the following steps: applying a negative electrode slurry for forming a negative electrode active layer on at least one side of a negative electrode current collector to form a negative electrode active layer to prepare a negative electrode sheet.

[0062] In a specific implementation, the materials used to form the negative electrode active material layer, such as the negative electrode active material, conductive agent, binder, dispersant, and inducer, can be placed in a solvent and evenly dispersed to obtain a first slurry. The materials used to form the negative electrode active material layer, such as the negative electrode active material, conductive agent, binder, and dispersant, can be placed in a solvent and evenly dispersed to obtain a second slurry. Subsequently, the negative electrode current collector copper foil is divided into three regions along the length of the copper foil and is coated in sections using intermittent coating. The first slurry or the second slurry can be directly coated on the surface of the negative electrode current collector, or the first and second slurries can be coated using a multi-nozzle coating machine. By controlling the number of coating nozzles for the first slurry relative to the total number of coating nozzles (i.e., the coating nozzles for the first slurry and the coating nozzles for the second slurry), the mass percentage of the inducer in each region of the negative electrode active material layer can be controlled. After drying, the negative electrode sheet is obtained by cold pressing, cutting, and slitting.

[0063] The negative electrode slurry is coated on the surface of the negative electrode current collector and dried in an oven or other drying equipment to remove the solvent to obtain a pole piece precursor; then, conventional rolling equipment is used to roll the pole piece precursor under certain pressure and roller gap conditions, and the pole piece precursor after rolling is cut into pieces (i.e., cut to a negative electrode sheet of a preset size) to obtain a negative electrode sheet.

[0064] Generally, during the rolling process, two rollers are used for rolling. There is a gap (roller gap) between the two rollers. The two rollers rotate in opposite directions (one roller rotates clockwise and the other roller rotates counterclockwise). During the rolling process, the electrode precursor passes through the gap between the two rollers and is squeezed by the two rollers to achieve the rolling process of the electrode precursor.

[0065] In the embodiments of the present invention, unless otherwise specified, the processes of coating, drying, rolling and the like involved are all conventional operations in the art, and the equipment used may be conventional equipment in the art, without particular limitation.

[0066] An embodiment of the present invention further provides a battery, comprising the above-mentioned negative electrode sheet or a negative electrode sheet prepared according to the above-mentioned method for preparing the negative electrode sheet. The battery has the same advantages as the above-mentioned negative electrode sheet, which will not be described in detail.

[0067] In some embodiments, the battery may be a lithium-ion battery.

[0068] Generally speaking, a battery includes an electrolyte, a cell, and a casing that encapsulates the cell. The electrolyte is injected into the cell within the casing, and the cell includes a positive electrode sheet, a negative electrode sheet, and a separator located between the positive and negative electrodes. The cell can be a laminated cell, where the positive electrode sheet, separator, and negative electrode sheet are stacked in an alternating pattern. Alternatively, the cell can be a wound cell, where the positive electrode sheet, separator, and negative electrode sheet are stacked and then wound.

[0069] Specifically, the positive electrode sheet includes a positive electrode collector and a positive electrode active layer located on at least one side surface of the positive electrode collector. Specifically, the positive electrode active layer can be provided on one side surface in the thickness direction of the positive electrode collector, or the positive electrode active layer can be provided on the surfaces of the opposite sides in the thickness direction of the positive electrode collector.

[0070] Specifically, the positive electrode active layer may include a positive electrode active material, a conductive agent and a binder. In the positive electrode active layer, the mass percentage of the positive electrode active material may be 70% to 99%, for example, 70%, 75%, 80%, 85%, 90%, 93%, 95%, 97%, 99% or a range consisting of any two thereof, the mass fraction of the conductive agent 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 a range consisting of any two thereof, and the mass fraction of the 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 a range consisting of any two thereof.

[0071] In some embodiments, the positive electrode active material may include LiCoO2, LiNiO2, 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 zO2 (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, and metal sulfides and oxides (such as V2S3, FeS, LiMS x (M is at least one transition metal element such as Ti, Fe, Ni, Cu, Mo, 1≤x≤2.5), one or more of TiO2, MnO2, etc.

[0072] In an embodiment of the present invention, the conductive agent in the positive electrode active layer may be a conventional conductive material in the art. For example, the conductive agent in the positive electrode active layer may include one or more of conductive carbon black, conductive graphite, carbon nanotubes (CNTs), carbon fibers, graphene, acetylene black, and Ketjen black.

[0073] In an embodiment of the present invention, the binder in the positive electrode active layer may be a conventional binding material in the art. For example, the binder in the positive electrode active layer may include one or more of polyvinylidene fluoride (PVDF), polyvinylidene fluoride, polyvinyl fluoride, polyethylene, polypropylene, polyvinyl alcohol, carboxymethyl cellulose, hydroxypropyl cellulose, diacetyl cellulose, polyvinyl chloride, carboxylated polyvinyl chloride, polymers containing ethylene oxide, polyvinyl pyrrolidone, polyurethane, and the like.

[0074] The embodiment of the present invention may adopt a conventional positive electrode current collector in the art, for example, the positive electrode current collector includes aluminum foil.

[0075] In the embodiments of the present invention, the positive electrode sheet can be prepared by conventional methods in the art, such as a coating method. Specifically, the components used to form the positive electrode active layer, such as the positive electrode active material, conductive agent, and binder, can be dispersed in a solvent, such as N-methylpyrrolidone (NMP), to prepare a positive electrode slurry, which is then coated on the surface of the positive electrode current collector. After drying and roller pressing, the positive electrode sheet is prepared. The coating, drying, and roller pressing steps involved are conventional operations for preparing positive electrode sheets using the coating method and are not particularly limited thereto.

[0076] The electrolyte of the embodiment of the present invention can be a conventional electrolyte in the field. For example, the electrolyte is a non-aqueous electrolyte, which may specifically include an organic solvent, an additive and an electrolyte salt. The organic solvent includes, for example, one or more of ethylene carbonate (EC), diethyl carbonate (DEC) and propylene carbonate (PC), the additive includes, for example, fluoroethylene carbonate (FEC), the additive includes, for example, vinylene carbonate (VC), the electrolyte salt may include a lithium salt, the lithium salt includes, for example, lithium hexafluorophosphate (LiPF6), lithium bis(fluorosulfonyl)imide (LiFSI), etc., but is not limited thereto.

[0077] In the embodiment of the present invention, the separator is used to separate the positive electrode sheet and the negative electrode sheet to prevent the positive electrode sheet and the negative electrode sheet from short-circuiting. The embodiment of the present invention can adopt conventional separators in the art without special limitation.

[0078] In the embodiment of the present invention, conventional shell materials in the art may be used to encapsulate the battery cell. The shell may include, for example, a soft packaging material such as an aluminum-plastic film, but is not limited thereto.

[0079] In the embodiment of the present invention, components such as positive electrode sheets, separators, and negative electrode sheets can be assembled into a battery by conventional methods in the art. For example, the positive electrode sheets, separators, and negative electrode sheets can be stacked in an alternating manner to produce a laminated battery cell (or wound into a wound battery cell); the battery cell can then be placed in a shell (outer packaging), and after conventional processes such as liquid injection (i.e., injecting electrolyte) and packaging, a battery can be produced.

[0080] An embodiment of the present invention further provides a battery pack including the above-mentioned battery. The battery pack has advantages corresponding to those of the above-mentioned negative electrode sheet, which will not be described in detail.

[0081] Generally, a battery pack includes multiple batteries as described above, which are connected as single cells to form a battery pack. These batteries can be electrically connected using conventional methods in the art, such as series connection, parallel connection, or a combination of these connection methods, without particular limitation.

[0082] An embodiment of the present invention further provides an electrical device, comprising the above-mentioned battery or the above-mentioned battery pack. The electrical device has advantages corresponding to the above-mentioned negative electrode sheet, which will not be described in detail.

[0083] The electrical equipment in the embodiments of the present invention can be conventional electrical equipment in the field, such as power equipment (such as electric vehicles, electric cars), electronic equipment (such as mobile phones, tablets, laptops, digital cameras, etc.), wearable devices (such as watches, bracelets, VR glasses, etc.), energy storage power stations, etc., without special restrictions.

[0084] The present invention is further described below through specific examples.

[0085] Example 1

[0086] 1. Preparation of electrolyte

[0087] In an argon atmosphere glove box with a water content of <1ppm and an oxygen content of <1ppm, ethylene carbonate (EC), ethyl methyl carbonate (EMC), and dimethyl carbonate (DMC) were uniformly mixed in a mass ratio of 1:1.2:0.8, and 2wt% (based on the mass of the electrolyte) of the film-forming additive VC was added. Then, lithium hexafluorophosphate (LiPF6) and lithium bis(fluorosulfonyl)imide (LiFSI) (the mass ratio of LiPF6 and LiFSI was 87:13) were added to prepare an electrolyte with a concentration of 1 mol / L.

[0088] 2. Preparation of positive electrode

[0089] The positive electrode active material lithium iron phosphate, the conductive agent carbon black, and the binder (PVDF) were mixed in a mass ratio of 88:9.5:2.5, and N-methylpyrrolidone (NMP) was added. The mixture was stirred in a vacuum mixer to form a uniform positive electrode slurry. The positive electrode slurry was then evenly coated on the positive electrode current collector aluminum foil. After drying, the mixture was cold pressed, cut into pieces, and slit to obtain the positive electrode sheet.

[0090] The conductive agent includes carbon nanotubes (CNTs) and carbon black, and the mass ratio of CNTs to carbon black is 90:10.

[0091] 3. Preparation of negative electrode sheet

[0092] 3-1. First slurry: Graphite (negative electrode active material), conductive agent (carbon black), styrene-butadiene rubber (SBR) (binder), carboxymethyl cellulose (CMC) (dispersant), and lithium hydroxide (inducer) are thoroughly stirred and mixed in water at a mass ratio of 75.5:19:1:2.5:2 to obtain a first slurry. The mass percentage of the inducing agent (i.e., oxygen-containing compound) in the solid component of the first slurry is 2%.

[0093] 3-2. Second slurry: Graphite, conductive agent (carbon black), binder (SBR), and dispersant (CMC) are mixed thoroughly in water at a mass ratio of 77:19.3:1:2.7 to obtain the second slurry;

[0094] The negative electrode current collector copper foil was divided into three regions along its length: a first edge region, a center region, and a second edge region. The ratio of the center region area to the negative electrode active material layer was 0.9:1, 0.05:1, and 0.05:1, respectively. Intermittent coating was used for segmented coating. The first and second edge regions were directly coated with the second slurry; the center region was coated with the first and second slurries using a multi-nozzle coater. By controlling the number of nozzles applying the first slurry to 20% of the total number of nozzles (i.e., nozzles applying the first slurry and nozzles applying the second slurry), the weight percentage of the inducer in the center region of the negative electrode active material layer was 0.4%. After drying, a negative electrode active material layer with a thickness of 0.02 mm was formed on the surface of the negative electrode current collector copper foil. The negative electrode sheet was then cold pressed, cut, and slit.

[0095] 4. Preparation of diaphragm

[0096] The diaphragm is made of polypropylene.

[0097] 5. Preparation of lithium-ion batteries

[0098] The positive electrode sheet, separator, and negative electrode sheet are stacked in sequence to form a core, secured with structural components, and then installed in an aluminum or steel casing. The prepared electrolyte is injected into the dried core. After vacuum packaging, impregnation, formation, and capacity separation, the lithium-ion battery is complete.

[0099] Example 2

[0100] The difference between this embodiment and embodiment 1 is that the mass percentage of the inducer in the central area of ​​the negative electrode active material layer is 1%. The negative electrode sheet is divided into three areas along the length direction of the electrode sheet, namely the first edge area, the central area, and the second edge area. The ratio of the area of ​​the central area to the area of ​​the negative electrode active material layer is 0.8:1, the ratio of the area of ​​the first edge area to the area of ​​the single side of the negative electrode sheet is 0.1:1, and the ratio of the area of ​​the second edge area to the area of ​​the negative electrode active material layer is 0.1:1. Intermittent coating is used for segmented coating. The first edge area and the second edge area are directly coated with the second slurry; the central area is coated with the first slurry and the second slurry by a multi-nozzle coating machine. By controlling the number of coating nozzles for the first slurry to account for 50% of the total number of coating nozzles, the mass percentage of the inducer in the central area of ​​the negative electrode active material layer is 1%. The thickness of the negative electrode active material layer is 0.06mm.

[0101] Example 3

[0102] The difference between this embodiment and embodiment 1 is that during the preparation of the negative electrode sheet:

[0103] 3-1. First slurry: Graphite (negative electrode active material), conductive agent (carbon black), binder (SBR), dispersant (CMC), and inducer lithium hydroxide are thoroughly stirred and mixed in water at a mass ratio of 71:18.9:1:2.1:7 to obtain a first slurry, wherein the mass percentage of the inducer (i.e., oxygen-containing group compound) in the solid component of the first slurry is 7%;

[0104] 3-2. Second slurry: Graphite, conductive agent (carbon black), binder (SBR), and dispersant (CMC) are mixed thoroughly in water at a mass ratio of 77:19.3:1:2.7 to obtain the second slurry;

[0105] The negative electrode sheet is divided into three regions along the length direction of the electrode sheet, namely the first edge region, the center region and the second edge region. The ratio of the area of ​​the center region to the area of ​​the negative electrode active material layer is 0.4:1, the ratio of the area of ​​the first edge region to the area of ​​the negative electrode active material layer is 0.3:1, and the ratio of the area of ​​the second edge region to the area of ​​the negative electrode active material layer is 0.3:1. In the first edge area and the second edge area, the first slurry and the second slurry are coated by a multi-nozzle coater, and the number of coating nozzles for the first slurry is controlled to account for 10% of the total number of coating nozzles, so that the mass percentage of the inducer in the first edge area of ​​the negative active material layer is 0.7%, and the mass percentage of the inducer in the second edge area is 0.7%; in the center area, the first slurry and the second slurry are coated by a multi-nozzle coater, and the number of coating nozzles for the first slurry is controlled to account for 80% of the total number of coating nozzles, so that the mass percentage of the inducer in the center area of ​​the negative active material layer is 5.6%. After drying, a negative active material layer is formed on the surface of the negative current collector copper foil, and the thickness of the negative active material layer is 0.12 mm. After cold pressing, cutting and slitting, the negative electrode sheet is obtained.

[0106] Example 4

[0107] The difference between this embodiment and embodiment 1 is that, during the preparation of the negative electrode sheet, the inducer is replaced with polyvinyl alcohol.

[0108] Example 5

[0109] The difference between this embodiment and embodiment 2 is that during the preparation of the negative electrode sheet, the inducer is replaced with polyvinyl alcohol.

[0110] Example 6

[0111] The difference between this embodiment and embodiment 3 is that during the preparation of the negative electrode sheet, the inducer is replaced with polyvinyl alcohol.

[0112] Example 7

[0113] The difference between this embodiment and embodiment 1 is that, during the preparation of the negative electrode sheet, the inducer is replaced with tetrabutylammonium hydroxide.

[0114] Example 8

[0115] The difference between this embodiment and embodiment 2 is that, during the preparation of the negative electrode sheet, the inducer is replaced with tetrabutylammonium hydroxide.

[0116] Example 9

[0117] The difference between this embodiment and embodiment 3 is that during the preparation of the negative electrode sheet, the inducer is replaced with tetrabutylammonium hydroxide.

[0118] Example 10

[0119] The difference between this embodiment and embodiment 1 is that during the preparation of the negative electrode sheet, the inducer is replaced with aluminum isopropoxide.

[0120] Example 11

[0121] The difference between this embodiment and embodiment 2 is that during the preparation of the negative electrode sheet, the inducer is replaced with aluminum isopropoxide.

[0122] Example 12

[0123] The difference between this embodiment and embodiment 3 is that during the preparation of the negative electrode sheet, the inducer is replaced with aluminum isopropoxide.

[0124] Example 13

[0125] The difference between this embodiment and embodiment 1 is that, during the preparation of the negative electrode sheet, the inducer is replaced with butenyloxycyclotriphosphophene.

[0126] Example 14

[0127] The difference between this embodiment and embodiment 2 is that, during the preparation of the negative electrode sheet, the inducer is replaced with butenyloxycyclotriphosphophene.

[0128] Example 15

[0129] The difference between this embodiment and embodiment 3 is that, during the preparation of the negative electrode sheet, the inducer is replaced with butenyloxycyclotriphosphophene.

[0130] Example 16

[0131] The difference between this embodiment and embodiment 1 is that, during the preparation of the negative electrode sheet, the inducer is replaced with tetrafluoropropyl methacrylate.

[0132] Example 17

[0133] The difference between this embodiment and embodiment 2 is that, during the preparation of the negative electrode sheet, the inducer is replaced with tetrafluoropropyl methacrylate.

[0134] Example 18

[0135] The difference between this embodiment and embodiment 3 is that, during the preparation of the negative electrode sheet, the inducer is replaced with tetrafluoropropyl methacrylate.

[0136] Example 19

[0137] The difference between this embodiment and embodiment 1 is that, during the preparation of the negative electrode sheet, the inducer is replaced with phthalic anhydride.

[0138] Example 20

[0139] The difference between this embodiment and embodiment 2 is that, during the preparation of the negative electrode sheet, the inducer is replaced with phthalic anhydride.

[0140] Example 21

[0141] The difference between this embodiment and embodiment 3 is that, during the preparation of the negative electrode sheet, the inducer is replaced with phthalic anhydride.

[0142] Example 22

[0143] The difference between this embodiment and embodiment 1 is that, during the preparation of the negative electrode sheet, the mass percentage of the inducer in the central region of the negative electrode active material layer is 0.01%. The specific steps are as follows:

[0144] The negative electrode current collector copper foil was divided into three regions along its length: a first edge region, a center region, and a second edge region. The ratio of the center region area to the negative electrode active material layer was 0.9:1, 0.05:1, and 0.05:1, respectively. Intermittent coating was used for segmented coating. The first and second edge regions were directly coated with the second slurry; the center region was coated with the first and second slurries using a multi-nozzle coating machine. By controlling the number of nozzles applying the first slurry to 0.5% of the total number of nozzles (i.e., nozzles applying the first and second slurries), the weight percentage of the inducer in the center region of the negative electrode active material layer was maintained at 0.01%. After drying, the negative electrode active material layer was formed on the surface of the negative electrode current collector copper foil. The negative electrode sheet was then cold pressed, cut, and slit.

[0145] Example 23

[0146] The difference between this embodiment and embodiment 1 is that, during the preparation of the negative electrode sheet, the mass percentage of the inducer in the central region of the negative electrode active material layer is 0.004%. The specific steps are as follows:

[0147] The negative electrode current collector copper foil was divided into three regions along its length: a first edge region, a center region, and a second edge region. The ratio of the center region area to the negative electrode active material layer was 0.9:1, the first edge region area to the negative electrode active material layer area was 0.05:1, and the second edge region area to the negative electrode active material layer area was 0.05:1. Intermittent coating was used for segmented coating. The first and second edge regions were directly coated with the second slurry; the center region was coated with the first and second slurries using a multi-nozzle coating machine. By controlling the number of nozzles applying the first slurry to 0.2% of the total number of nozzles (i.e., nozzles applying the first and second slurries), the weight percentage of the inducer in the center region of the negative electrode active material layer was maintained at 0.004%. After drying, the negative electrode active material layer was formed on the surface of the negative electrode current collector copper foil. The negative electrode sheet was then cold pressed, cut, and slit.

[0148] Example 24

[0149] The difference between this embodiment and Example 1 is that, during the preparation of the negative electrode sheet, the mass percentage of the oxygen-containing group compound in the solid component of the first slurry is 30%. The specific steps are as follows: the negative electrode active material graphite, the conductive agent (carbon black), the binder styrene-butadiene rubber (SBR), the dispersant carboxymethyl cellulose (CMC), and the inducer lithium hydroxide are thoroughly stirred and mixed in water at a mass ratio of 60:15:1:0.9:23.1 to obtain a first slurry.

[0150] Example 25

[0151] The difference between this embodiment and Example 1 is that, during the preparation of the negative electrode sheet, the mass percentage of the oxygen-containing group compound in the solid component of the first slurry is 0.1%. The specific steps are as follows: the negative electrode active material graphite, the conductive agent (carbon black), the binder styrene-butadiene rubber (SBR), the dispersant carboxymethyl cellulose (CMC), and the inducer lithium hydroxide are thoroughly stirred and mixed in water in a mass ratio of 77: 19.2: 1: 2.7: 0.1 to obtain a first slurry.

[0152] Example 26

[0153] The difference between this embodiment and embodiment 3 is that the negative electrode sheet preparation process includes the following specific steps: the negative electrode sheet is divided into three regions along the length direction of the electrode sheet, namely a first edge region, a center region, and a second edge region. The ratio of the center region area to the negative electrode active material layer area is 0.4:1, the ratio of the first edge region area to the negative electrode active material layer area is 0.3:1, and the ratio of the second edge region area to the negative electrode active material layer area is 0.3:1. Intermittent coating is used for segmented coating. In the first edge area and the second edge area, the first slurry and the second slurry are coated by a multi-nozzle coater, and the number of coating nozzles for the first slurry is controlled to account for 60% of the total number of coating nozzles, so that the mass percentage of the first active material in the first edge area of ​​the negative active material layer is 60%, and the mass percentage of the inducer in the second edge area is 4.2%; in the central area, the first slurry and the second slurry are coated by a multi-nozzle coater, and the number of coating nozzles for the first slurry is controlled to account for 80% of the total number of coating nozzles, so that the mass percentage of the inducer in the central area of ​​the negative active material layer is 5.6%. After drying, a negative active material layer is formed on the surface of the negative current collector copper foil, and then the negative electrode sheet is obtained after cold pressing, cutting and slitting.

[0154] Example 27

[0155] The difference between this embodiment and embodiment 3 is that, in the process of preparing the negative electrode sheet, 3-1, first slurry: the negative electrode active material graphite, the conductive agent (carbon black), the binder styrene-butadiene rubber (SBR), the dispersant carboxymethyl cellulose (CMC), and the inducer lithium hydroxide are fully stirred and mixed in water at a mass ratio of 75:1.5:1:1:20 to obtain a first slurry, wherein the mass percentage of the inducer (i.e., the oxygen-containing group compound) in the solid component of the first slurry is 20%;

[0156] 3-2. Second slurry: Graphite, conductive agent (carbon black), binder (SBR), and dispersant (CMC) are mixed thoroughly in water at a mass ratio of 77:19.3:1:2.7 to obtain the second slurry;

[0157] The negative electrode current collector copper foil was divided into three regions along its length: a first edge region, a center region, and a second edge region. The ratio of the center region area to the negative electrode active material layer area was 0.9:1, the first edge region area to the negative electrode active material layer area ratio was 0.05:1, and the second edge region area to the negative electrode active material layer area ratio was 0.05:1. Intermittent coating was used for segmented coating. Among them, in the first edge area and the second edge area, the first slurry and the second slurry are coated by a multi-nozzle coating machine, and the number of coating nozzles for the first slurry is controlled to account for 50% of the total number of coating nozzles, so that the mass percentage of the inducer in the first edge area of ​​the negative active material layer is 10%, and the mass percentage of the inducer in the second edge area is 10%; the first slurry is directly coated on the center area to achieve a mass percentage of the inducer in the center area of ​​the negative active material layer of 20%. After drying, a negative active material layer is formed on the surface of the negative current collector copper foil. The thickness of the negative active material layer is 0.02 mm, and then the negative electrode sheet is obtained after cold pressing, cutting and slitting.

[0158] Comparative Example 1

[0159] The difference between this comparative example and Example 1 is that no inducer is added during the preparation of the negative electrode sheet, and the specific steps include:

[0160] (1) Preparation of electrolyte

[0161] In an argon atmosphere glove box with a water content of <1ppm and an oxygen content of <1ppm, ethylene carbonate (EC), ethyl methyl carbonate (EMC), and dimethyl carbonate (DMC) were uniformly mixed in a mass ratio of 1:1.2:0.8, a film-forming additive was added, and then LiPF6 and LiFSI were added to prepare an electrolyte with a concentration of 1 mol / L.

[0162] (2) Preparation of positive electrode

[0163] The positive electrode active material (lithium iron phosphate), conductive agent carbon nanotubes (CNT, carbon black), and binder (PVDF) are mixed in a mass ratio of 88:9.5:2.5, and N-methylpyrrolidone (NMP) is added. The mixture is stirred into a uniform positive electrode slurry in a vacuum mixer, and then the positive electrode slurry is evenly coated on the positive electrode current collector aluminum foil. After drying, the positive electrode sheet is obtained by cold pressing, cutting, and slitting.

[0164] (3) Preparation of negative electrode sheet

[0165] The negative electrode active material graphite, conductive agent (carbon black), binder (SBR), and dispersant (CMC) are thoroughly stirred and mixed in water at a mass ratio of 77:19.3:1:2.7, then coated on copper foil and dried, and then cold pressed, cut into pieces, and slit to obtain the negative electrode sheet.

[0166] (4) Preparation of diaphragm

[0167] The diaphragm is made of polypropylene.

[0168] (5) Preparation of lithium-ion batteries

[0169] The positive electrode sheet, separator, and negative electrode sheet are stacked in sequence to form a core, secured with structural components, and then installed in an aluminum or steel casing. The prepared electrolyte is injected into the dried core. After vacuum packaging, impregnation, formation, and capacity separation, the lithium-ion battery is complete.

[0170] Comparative Example 2

[0171] The difference between this comparative example and Example 1 is that the mass percentage of the inducer in each region of the negative electrode active material layer is the same during the preparation of the negative electrode sheet, and specifically includes the following steps:

[0172] The negative electrode current collector copper foil was divided into three regions along its length: a first edge region, a center region, and a second edge region. The ratio of the center region area to the negative electrode active material layer area was 0.9:1, the first edge region area to the negative electrode active material layer area ratio was 0.05:1, and the second edge region area to the negative electrode active material layer area ratio was 0.05:1. Intermittent coating was used for segmented coating. Among them, the first edge area, the center area and the second edge area are all coated with the first slurry and the second slurry by a multi-nozzle coater. By controlling the number of coating nozzles for the first slurry to account for 20% of the total number of coating nozzles (i.e., the coating nozzles for the first slurry and the coating nozzles for the second slurry), the mass percentage of the inducer in the center area of ​​the negative active material layer is 0.4%, the mass percentage of the inducer in the first edge area is 0.4%, and the mass percentage of the inducer in the second edge area is 0.4%. After drying, a negative active material layer is formed on the surface of the negative current collector copper foil, and then the negative electrode sheet is obtained after cold pressing, cutting and slitting.

[0173] Performance Testing

[0174] 1) Cycle Capacity Retention: The lithium-ion batteries prepared in each Example and Comparative Example were charged at room temperature (25±3°C) at a constant current rate of 0.33C to 3.8V, allowed to rest for 30 minutes, and then discharged at a constant current rate of 0.33C to 2V and allowed to rest for 30 minutes. This constituted one cycle. The capacity retention after 1500 cycles at room temperature was recorded (i.e., the ratio of the discharge capacity after 1500 cycles to the discharge capacity after the first cycle). To ensure a constant battery temperature during the cycle test, the battery was placed in a high and low temperature test chamber for testing. Cycle Capacity Retention = (Discharge Capacity at the Last Cycle / Discharge Capacity at the First Cycle) × 100%. The results are shown in Table 1.

[0175] 2) The ratio of the VC mass per unit area in the central area to the VC mass per unit area in the first edge area: After the above-mentioned rate performance test (i.e., room temperature cycle test) is completed, the VC content on the negative electrode sheet is measured. Use a pipette to accurately transfer 6 mL of acetonitrile in advance and place it in a centrifuge tube and seal it for later use. Remove the battery casing and structural parts that have completed the test, disassemble the negative electrode sheet whose VC content needs to be measured, use a sampler according to the nine-square sampling method to cut 1 to 2 negative electrode sheets and place them in a sample tube filled with acetonitrile solvent and seal it. After sealing the sample tube containing the negative electrode sheet, place it on a shaker to assist in dissolution for more than 24 hours to accelerate the dissolution of the electrolyte inside the electrode sheet. A gas chromatography-mass spectrometer (GC-MS) is used to detect the acetonitrile content and the VC mass in the negative electrode sample, respectively. According to the formula, the VC mass per unit area of ​​the central area (unit: g / cm 2 ) = VC mass of the central area / sampling area of ​​the central area, according to the formula VC mass per unit area of ​​the first edge area (unit g / cm 2 ) = VC mass of the first edge area / sampling area of ​​the first edge area, calculate the ratio (R) of the VC content per unit area of ​​the central area of ​​the negative electrode sheet to the VC content per unit area of ​​the first edge area. The results are shown in Table 1.

[0176] 3) Negative Electrode Active Material Layer Thickness: The batteries from each Example and Comparative Example were fully discharged and then disassembled. The negative electrode sheets were removed and the negative electrode active material layer was scraped off. The scraped negative electrode active material was placed on a SEM sample stage for SEM testing. The thickness of the negative electrode active material layer was measured perpendicular to the negative electrode active material layer using the measurement tool in the SEM software. The thickness data for 100 negative electrode active material layers were read and the average value was calculated as the negative electrode active material layer thickness test result. The results are shown in Table 1.

[0177] The ratio of the area of ​​the first edge region to the area of ​​the negative electrode active material layer A1:1, the ratio of the area of ​​the central region to the area of ​​the negative electrode active material layer A2:1, the ratio of the area of ​​the second edge region to the area of ​​the negative electrode active material layer A3:1, the type of inducer, the mass percentage of the inducer in the central region x2, the mass percentage of the inducer in the first edge region x1, the mass percentage of the inducer in the second edge region x3, the thickness D of the negative electrode active material layer, the ratio (R) of the mass per unit area VC of the central region to the mass per unit area of ​​the first edge region in each embodiment and comparative example are summarized in Table 1. Except for the differences shown in Table 1, the other conditions are basically the same.

[0178] Table 1

[0179]

[0180] The following conclusions can be drawn from Table 1: No inducer was introduced into the negative electrode active material layer in Comparative Example 1, the mass percentage of the negative electrode active material layer in each region of the negative electrode active material layer in Comparative Example 2 was the same, and the uniformity of VC distribution on the surface of the negative electrode active material layer of Comparative Example 1-2 and the cycle life of the battery were seriously deteriorated.

[0181] Compared to Comparative Examples 1-2, the negative electrode sheets in Examples 1-27 had a lower ratio of the VC mass per unit area in the center region to the VC mass per unit area in the first edge region, indicating a more uniform VC distribution on the surface of the negative electrode active material layer in Examples 1-27, forming a more uniform SEI film. Furthermore, the batteries in Examples 1-27 had a higher cycle capacity retention rate, indicating that the batteries in Examples 1-27 had a longer cycle life.

[0182] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the above embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements 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 invention comprises a negative electrode sheet and an electrolyte, wherein the negative electrode sheet comprises a negative electrode current collector and a negative electrode active material layer provided on at least one side surface of the negative electrode current collector, wherein the negative electrode active material layer comprises a negative electrode active substance and an inducer, wherein the inducer comprises an oxygen-containing group compound; Along the length direction of the negative electrode active material layer, the negative electrode active material layer includes a central region and edge regions located on opposite sides of the central region; The mass proportion of the inducer in the central region is greater than the mass proportion of the inducer in the edge region; The electrolyte includes a cyclic carbonate.

2. The battery according to claim 1, characterized in that The edge region includes N sub-edge regions distributed along the length direction of the negative electrode active material layer, where N≥1. From the central region to the edge region, the mass proportion of the inducer in the sub-edge regions decreases successively.

3. The battery according to claim 1 or 2, characterized in that The mass percentage of the inducer in the edge area is 0%-10%; And / or, the mass percentage of the inducer in the central area is 0.001%-20%.

4. The battery according to any one of claims 1 to 3, characterized in that The ratio of the area of ​​the central region to the area of ​​the negative electrode active material layer is (0.4-0.9):1; And / or, the ratio of the area of ​​the edge region to the area of ​​the negative electrode active material layer is (0.1-0.6):

1.

5. The battery according to any one of claims 1 to 4, characterized in that: The oxygen-containing group compound includes oxygen-containing groups, and the oxygen-containing groups include hydroxyl, alkoxy, aldehyde, acetyl, carboxyl, anhydride, O - , O 2- OH - One or more of .

6. The battery according to claim 5, characterized in that The oxygen-containing group compound includes one or more of polyvinyl alcohol, phthalic anhydride, butyleneoxycyclotriphosphine, tetrafluoropropyl methacrylate, metal hydroxide, tetrabutylammonium hydroxide, and aluminum isopropoxide.

7. The battery according to any one of claims 1 to 6, characterized in that: The cyclic carbonate includes vinylene carbonate.

8. The battery according to any one of claims 1 to 7, characterized in that: The negative electrode active material includes one or more of graphite, carbon black, hard carbon, and soft carbon.

9. The battery according to any one of claims 1 to 8, characterized in that: The thickness of the negative electrode active material layer is 0.02 mm to 0.12 mm.

10. The battery according to any one of claims 1 to 9, characterized in that: The negative electrode active material layer further includes one or more of a conductive agent, a binder, and a dispersant.

11. An electrical device, characterized in that: A battery comprising the battery according to any one of claims 1 to 10.

Images