Battery cell and method for producing the same, battery, electric device

Abstract

The application provides a battery monomer and a preparation method thereof, a battery, and a power utilization device. The preparation method of the battery monomer comprises the following steps: crushing and grading a coke raw material to obtain first aggregate, wherein the volume particle size distribution Dv50 of the first aggregate is 2-5 μm, and the particle size distribution K value of the first aggregate is 1.6-1.8; mechanically shaping the first aggregate to obtain second aggregate, wherein the particle size distribution K' value of the second aggregate is 1.35-1.55; mixing and kneading the second aggregate and a binder to obtain mixed and kneaded material; pressing the mixed and kneaded material into a composite block through a forming process; crushing and grading the composite block to obtain an intermediate; performing high-temperature graphitization on the intermediate to obtain a graphite material; and preparing a negative electrode sheet by using the graphite material, so as to prepare the battery monomer. The technical scheme of the application is beneficial to reducing the volume expansion of the graphite negative electrode and improving the cycle life of the battery monomer.

Description

Technical Field

[0001] This application relates to the field of batteries, and more specifically, to a battery cell and its preparation method, a battery, and an electrical device. Background Technology

[0002] With increasing environmental pollution, the new energy industry is attracting more and more attention. Within the new energy industry, battery technology is a crucial factor in its development.

[0003] The development of battery technology requires consideration of various design factors, such as energy density, cycle life, capacity, and reliability. Therefore, how to reduce the volume expansion of graphite anodes during cycling to improve the cycle life of individual battery cells is an urgent problem to be solved. Summary of the Invention

[0004] This application is made in view of the above-mentioned problems, and its purpose is to provide a battery cell to reduce the volume expansion phenomenon of graphite negative electrode during cycling and improve the cycle life of the battery cell.

[0005] To achieve the above objectives, this application provides a battery cell and its preparation method, a battery, and an electrical device.

[0006] In a first aspect, a method for preparing a battery cell is provided, comprising: crushing and classifying coke raw material to obtain a first aggregate, wherein the volumetric particle size distribution Dv50' of the first aggregate is 2μm to 5μm and the particle size distribution K value of the first aggregate is 1.6 to 1.8; mechanically shaping the first aggregate to obtain a second aggregate, wherein the particle size distribution K' value of the second aggregate is 1.35 to 1.55; kneading a binder with the second aggregate to obtain a kneaded material, wherein the kneaded material is pressed into a composite block by a molding process; crushing, classifying and high-temperature graphitizing the composite block to obtain a graphite material; and using the graphite material to prepare a negative electrode sheet to prepare a battery cell.

[0007] In this embodiment, the coke raw material is crushed and shaped to obtain small-diameter aggregate particles. The small-diameter aggregate is mixed and kneaded with a binder to improve the uniformity of the mixing, thereby increasing the density and strength of the material. At the same time, the smaller primary particle size helps to achieve isotropy within the secondary particles and reduces expansion. The kneaded material is then crushed and granulated to obtain graphite material with small particle size and high isotropy, which improves particle strength and tap density. Therefore, the above solution can effectively reduce the volume expansion of the graphite anode during cycling, and the small particle size can improve the kinetic performance and increase the cycle life.

[0008] In one possible implementation, the coke feedstock includes at least one of petroleum coke, isokinetic coke, needle coke, and pitch coke. Using coke feedstock can improve adhesion, thereby increasing tap density, reducing volume expansion of graphite materials during cycling, and improving the cycle life of the prepared graphite anode material.

[0009] In one possible implementation, the molding process includes at least one of molding, extrusion, and isostatic pressing. During the kneading process, the molding process increases the tap density of the mixture by uniformly mixing and filling solid carbonaceous materials of different particle sizes, which helps to improve the cycle life and kinetic performance of the battery cells.

[0010] In one possible implementation, the mass ratio of the second aggregate to the binder is 100:(5-15). The aggregate and binder are mixed at this mass ratio to improve the cohesiveness and density of the mixed material.

[0011] In one possible implementation, mixing the second aggregate with the binder to form a mixture includes: mixing the binder and the second aggregate at the softening point of the binder, which is between 50°C and 80°C. The binder includes at least one selected from asphalt, phenolic resin, furfural resin, and epoxy resin.

[0012] In one possible implementation, the high-temperature graphitization process is carried out at a temperature above 3000°C.

[0013] Secondly, a battery cell is provided, comprising: a negative electrode sheet, the negative electrode sheet including a negative current collector and a negative electrode film layer, the negative electrode film layer being disposed on at least one surface of the negative current collector, the negative electrode film layer comprising graphite material; the OI value of the graphite material is 1.5 to 2.4; the tap density T of the graphite material satisfies: 1.15 g / cm³. 3 ≤T≤1.3g / cm 3 .

[0014] The graphite anode material in this application has a low OI value, resulting in high material isotropy and reduced directional selectivity of graphite material volume expansion. At the same time, the graphite material has a high tap density, thereby effectively reducing the volume expansion and microcrack generation of the graphite anode during cycling and improving the cycle life of the battery cell.

[0015] In one possible implementation, the particle strength of the graphite material is 93% to 98%, which can effectively reduce the volume expansion caused by graphite cycling and improve cycle life.

[0016] In one possible implementation, the powder compaction density of the graphite material is 1.6 g / cc to 1.9 g / cc. When the compaction density is within this range, the discharge capacity of the battery can be increased, the internal resistance reduced, and the cycle life of the individual battery cells extended.

[0017] In one possible implementation, the specific surface area of ​​the graphite material is 1.5 m². 2 / g~2.6m 2 / g. Controlling the specific surface area within the above range can reduce the volume expansion of the material and improve its rate performance.

[0018] In one possible implementation, the volumetric particle size distribution Dv50 of the graphite material satisfies: 10μm≤Dv50≤16μm. When the composite block is further crushed and classified, the Dv50 of the graphite material meets the above range, thus obtaining graphite material with small particle size and high isotropy, high particle strength, increased tap density, reduced volume expansion of graphite during the cycle, and improved kinetic performance due to the smaller particle size.

[0019] In one possible implementation, the graphite material has a graphitization degree of 90% to 94%. The high graphitization degree of the graphite material in the above technical solution helps to improve the electrochemical performance of the battery cell.

[0020] In one possible implementation, the specific capacity of the graphite material is 330 mAh / g to 355 mAh / g.

[0021] Thirdly, a battery is provided, comprising a battery cell according to the first aspect and any possible implementation thereof, and / or a battery cell obtained by a preparation method according to the second aspect and any possible implementation thereof.

[0022] Fourthly, an electrical device is provided, including the battery of the third aspect. Attached Figure Description

[0023] Figure 1 This is a schematic diagram of a method for preparing a battery cell according to an embodiment of this application.

[0024] Figure 2 This is a first charge-discharge curve diagram of an embodiment of this application.

[0025] Figure 3 This is a schematic diagram of a battery cell according to an embodiment of this application.

[0026] Figure 4 This is a schematic diagram of a battery according to an embodiment of this application.

[0027] Figure 5 This is a schematic diagram of an electrical device according to an embodiment of this application.

[0028] Explanation of reference numerals in the attached figures:

[0029] 3. Battery cell; 31. Housing; 32. End cap assembly; 33. Electrode assembly; 34. Connecting component; 322. Electrode terminal; 330. Electrode assembly body; 331. Tab; 4. Battery; 5. Electrical device. Detailed Implementation

[0030] The following detailed description, with appropriate reference to the accompanying drawings, discloses embodiments of the battery cell, its manufacturing method, the battery, and the power-consuming device of this application. However, unnecessary detailed descriptions may be omitted. For example, detailed descriptions of well-known matters and repetitive descriptions of practically identical structures may be omitted. This is to avoid unnecessarily lengthy descriptions and to facilitate understanding by those skilled in the art. Furthermore, the accompanying drawings and the following description are provided for the purpose of enabling those skilled in the art to fully understand this application and are not intended to limit the subject matter of the claims.

[0031] The "range" disclosed in this application is defined by a lower limit and an upper limit. A given range is defined by selecting a lower limit and an upper limit, which define the boundaries of a particular range. Ranges defined in this way can include or exclude endpoints and can be arbitrarily combined; that is, any lower limit can be combined with any upper limit to form a range. For example, if ranges of 60-120 and 80-110 are listed for a specific parameter, it is expected that ranges of 60-110 and 80-120 are also included. Furthermore, if minimum range values ​​of 1 and 2 are listed, and if maximum range values ​​of 3, 4, and 5 are listed, then the following ranges are all expected: 1-3, 1-4, 1-5, 2-3, 2-4, and 2-5. In this application, unless otherwise stated, the numerical range "ab" represents a shortened representation of any combination of real numbers between a and b, where a and b are real numbers. For example, the numerical range "0-5" indicates that all real numbers between "0-5" have been listed in this article; "0-5" is simply a shortened representation of these numerical combinations. Furthermore, when a parameter is stated as an integer ≥2, it is equivalent to disclosing that the parameter is, for example, an integer such as 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0032] Unless otherwise specified, all embodiments and optional embodiments of this application can be combined to form new technical solutions.

[0033] Unless otherwise specified, all technical features and optional technical features of this application may be combined to form new technical solutions.

[0034] Unless otherwise specified, all steps in this application may be performed sequentially or randomly, preferably sequentially. For example, the method includes steps (a) and (b), indicating that the method may include steps (a) and (b) performed sequentially, or it may include steps (b) and (a) performed sequentially. For example, the method may also include step (c), indicating that step (c) may be added to the method in any order. For example, the method may include steps (a), (b), and (c), or it may include steps (a), (c), and (b), or it may include steps (c), (a), and (b), etc.

[0035] In recent years, rechargeable batteries have seen significant development due to their high energy density and long lifespan, finding widespread application in power tools, electronic products, electric vehicles, aerospace, and other fields. Typically, a rechargeable battery consists of a positive electrode, a negative electrode, an electrolyte, and a separator. During charging and discharging, active ions repeatedly insert and extract between the positive and negative electrodes. The electrolyte acts as a conductor of these active ions between the electrodes. The separator, positioned between the positive and negative electrodes, prevents short circuits while allowing active ions to pass through, ensuring the normal electrochemical reaction of the rechargeable battery.

[0036] The development of battery technology must consider multiple design factors simultaneously, such as energy density, cycle life, discharge capacity, charge / discharge rate, fast charging capability, reliability, and initial charge capacity. With the widespread use of batteries, the requirements for battery life are gradually increasing. Currently, commercially available anode materials are mainly graphite. However, graphite materials undergo significant volume expansion during cycling, generating numerous microcracks, increasing side reactions, and causing repeated growth of the solid electrolyte interface (SEI) film, ultimately leading to deterioration in cycle performance.

[0037] In related technologies, some processing methods optimize graphite orientation through granulation to reduce the volume expansion of graphite materials, thereby improving the isotropy of the material, suppressing electrode stress release, and reducing cyclic expansion. However, these methods result in lower tap density and weaker particle strength in the secondary particles obtained from granulation, leading to decreased electrode processing performance and easy breakage of particles after cold pressing, causing the orientation to revert to anisotropy.

[0038] In view of this, in one embodiment of this application, a method for preparing a battery cell is provided, comprising: crushing and classifying coke raw material to obtain a first aggregate, wherein the volumetric particle size distribution Dv50' of the first aggregate is 2μm to 5μm and the particle size distribution K value of the first aggregate is 1.6 to 1.8; mechanically shaping the first aggregate to obtain a second aggregate, wherein the particle size distribution K' value of the second aggregate is 1.35 to 1.55; mixing the second aggregate with a binder to obtain a mixed material; pressing the mixed material into a composite block through a molding process; subjecting the composite block to a secondary crushing and classification process to obtain an intermediate; subjecting the intermediate to high-temperature graphitization to obtain a graphite material; and using the graphite material to prepare a negative electrode sheet to prepare a battery cell. In this way, by crushing, classifying and reshaping the raw materials to obtain small-diameter aggregates, the use of small-diameter aggregates for briquetting can improve the uniformity of mixing, thereby increasing the density and strength of the material; at the same time, the smaller primary particle size helps to improve the isotropy within the secondary particles; after briquetting the mixed materials and then crushing and classifying them again, the particle strength and tap density can be further improved, the volume expansion during graphite cycling can be reduced, the cycle life of the battery cells can be improved and the dynamic performance can be enhanced.

[0039] In addition, the following description, with appropriate reference to the accompanying drawings, will illustrate the method for preparing the battery cell, the battery cell, the battery, and the power-consuming device of this application.

[0040] [Preparation methods for battery cells]

[0041] In one embodiment of this application, a method for preparing a battery cell is provided.

[0042] Figure 1 This is a schematic diagram illustrating a method for preparing a single battery cell according to an embodiment of this application. (In conjunction with...) Figure 1 As shown, the preparation method 1 of the battery cell may include the following steps.

[0043] Step 110: The coke raw material is crushed and graded to obtain the first aggregate.

[0044] Step 120: Mechanically shape the first aggregate to obtain the second aggregate.

[0045] Step 130: Mix the second aggregate with the binder to obtain a mixed material.

[0046] Step 140: The mixed materials are pressed into composite blocks through a molding process, and the composite blocks are subjected to secondary crushing and grading to obtain intermediates.

[0047] Step 150: The intermediate is subjected to high-temperature graphitization treatment to obtain graphite material.

[0048] Step 160: Prepare a negative electrode sheet using graphite material to prepare a battery cell.

[0049] Therefore, by using small-diameter aggregates for briquetting, this application can improve the uniformity of mixing, thereby increasing the density and strength of the material and enhancing its isotropy. At the same time, after briquetting the mixed material, it can further increase the isotropy of the material, improve the particle strength and tap density, thereby reducing the volume expansion of the electrode sheet during cycling and improving the cycle life of the battery cell.

[0050] The volumetric particle size distribution Dv50 of the first aggregate is 2μm to 5μm.

[0051] Dv50 can refer to the particle size corresponding to 50% of the cumulative particle size distribution number of a sample, which means that 50% of the particles are smaller than Dv50.

[0052] Specifically, the volumetric particle size distribution of the first aggregate can be 2μm, 3μm, 4μm, 5μm, or a value within the range obtained by any combination of the above values.

[0053] When the volumetric particle size of the first aggregate is within the above range, using aggregate with a smaller particle size for briquetting can improve the uniformity of mixing, thereby increasing the density and strength of the material.

[0054] In some embodiments, the particle size distribution K of the first aggregate is 1.6 to 1.8, and the particle size distribution K' of the second aggregate is 1.35 to 1.55.

[0055] The K-value of particle size distribution is commonly used to describe the particle size distribution characteristics of particulate materials. It reflects the width and uniformity of the particle size distribution. The calculation formula is (D90-D10) / D50, where D90, D50, and D10 represent the particle sizes corresponding to 90%, 50%, and 10% of the cumulative volume in the particle size distribution, respectively. A larger K-value indicates a wider particle size distribution and greater differences in particle size. The K' value here is used to distinguish it from the K-values ​​of other materials, representing the particle size distribution of different substances.

[0056] Specifically, the particle size distribution K' of the second aggregate can be 1.35, 1.4, 1.46, 1.5, 1.55, or a value within the range obtained by any combination of the above values.

[0057] The particle size distribution K' value of the second aggregate is smaller than that of the first aggregate. Through mechanical shaping, the particle size of the aggregate is controlled to be within a small range, which helps to improve the isotropy of the secondary particles formed after briquetting, reduce the volume expansion of graphite materials during cycling, and extend the cycle life of battery cells.

[0058] In some embodiments, the coking raw material includes at least one of petroleum coke, isoprismatic coke, needle coke, and pitch coke.

[0059] Petroleum coke, isokinetic coke, needle coke, and pitch coke are precursors for graphite materials. Needle coke is a high-capacity, high-density graphite. Graphite anode materials prepared using needle coke as a precursor show a significant improvement in compaction density. Similar effects are also observed with non-needle coke, such as petroleum coke and pitch coke.

[0060] In some embodiments, the molding process includes at least one of molding, extrusion, and isostatic pressing.

[0061] The forming processes of graphite materials include molding, extrusion, and isostatic pressing. Molding is formed by pressing with a mold; extrusion is a semi-continuous production method with high production efficiency; isostatic pressing is a process in which the liquid pressure is applied uniformly and constantly, resulting in graphite materials with excellent properties, such as uniform structure, high density, and high strength. It can also improve the isotropy of graphite materials and reduce the volume expansion of materials during cycling.

[0062] In some embodiments, the mass ratio of the second aggregate to the binder is 100:(5-15). The aggregate and binder are mixed at the above mass ratio to improve the cohesiveness and density of the mixed material.

[0063] In some embodiments, the second aggregate is kneaded with the binder at the softening point of the binder, which is between 50°C and 80°C. Optionally, the binder includes at least one selected from asphalt, phenolic resin, furfural resin, and epoxy resin.

[0064] In some embodiments, the high-temperature graphitization process temperature is above 3000°C.

[0065] Heating graphite materials to 3000℃ can enhance their properties. The graphitization process rearranges carbon atoms into a more ordered structure, thereby improving the material's mechanical strength, thermal conductivity, and electrical conductivity.

[0066] [Battery cell]

[0067] This application provides a battery cell including a negative electrode sheet, which includes a negative current collector and a negative electrode film. The negative electrode film is disposed on at least one surface of the negative current collector and includes a graphite material. The OI value of the graphite material is 1.5 to 2.4, and the tap density of the graphite material is 1.15 g / cm³. 3 ~1.3g / cm 3 .

[0068] Specifically, the tap density of graphite material can be 1.15 g / cm³. 3 1.18g / cm 3 1.22g / cm 3 1.3g / cm3 , or its value is within the range obtained by any combination of the above values.

[0069] The OI value of graphite material can be 1.5, 1.7, 1.83, 1.9, 1.96, 2.0, 2.2, 2.4, or a value within the range obtained by any combination of the above values.

[0070] The OI value of graphite particles is I 004 / I 110 The ratio of I 004 and I 110 It is the intensity of the peak when X-ray diffraction is used to test the structure of a material, representing the orientation index. The smaller the ratio, the better the isotropy.

[0071] Tap density refers to the density of a powder material after it has been tapped under certain conditions. It is a parameter used to measure the maximum density that a powder material can achieve after being vibrated in its natural packed state.

[0072] In the above technical solution, when the OI value of the graphite material is less than 2.4, it indicates that the material has high isotropy, and when the tap density of the graphite material is greater than or equal to 1.15 g / cm³... 3 This helps reduce the volume expansion of graphite anode materials during cycling, increase the density of the anode film and increase the content of active materials per unit volume, thereby improving the dynamic performance of the battery cell and enhancing cycle life.

[0073] In some embodiments, the particle strength of the graphite material is greater than or equal to 95%.

[0074] Specifically, the particle strength of graphite materials can be 95%, 97%, 97.4%, 98%, 99%, or a value within the range obtained by any combination of the above values.

[0075] Graphite materials have high particle strength, which can effectively reduce the volume expansion caused by graphite cycling and improve cycle life.

[0076] In some embodiments, the powder compaction density of the graphite material is 1.6 g / CC to 1.9 g / CC.

[0077] Specifically, the compaction density of graphite powder can be 1.6 g / cc, 1.7 g / cc, 1.8 g / cc, 1.9 g / cc, or a value within the range obtained by any combination of the above values.

[0078] Compaction density has a significant impact on battery performance during the cell manufacturing process. Higher compaction density allows for higher battery capacity, making it a key indicator of material energy density. Conversely, excessively low compaction density hinders lithium-ion insertion and extraction. Appropriate compaction density increases discharge capacity, reduces internal resistance, minimizes polarization losses, extends cycle life, and improves lithium-ion utilization.

[0079] When the compaction density of graphite materials is within the above range, it is beneficial to improve the dynamic performance of battery cells and extend cycle life.

[0080] In some embodiments, the specific surface area of ​​the graphite material is 1.5 m². 2 / g~2.6m 2 / g.

[0081] Specifically, the specific surface area of ​​graphite materials can be 1.5 m². 2 / g, 1.7m 2 / g, 1.9m 2 / g, 2.0m 2 / g, 2.2m 2 / g, 2.4m 2 / g, 2.6m 2 / g, or its value within the range obtained by any combination of the above values.

[0082] Specific surface area (Brunauer-Emmett-Teller, BET) refers to the total surface area per unit mass of material.

[0083] When the specific surface area of ​​graphite material is not less than 1.5m² 2 At a specific surface area of ​​ / g, it has more active sites and reaction area. When the specific surface area of ​​graphite material is not greater than 2.6m², it has more active sites and reaction area. 2 At a density of / g, the graphite material has a reasonable contact area with the electrolyte, reducing the formation of the SEI film and decreasing the volume expansion of the material.

[0084] In some embodiments, the volumetric particle size distribution Dv50' of the graphite material satisfies: 10μm≤Dv50≤16μm.

[0085] Specifically, the volumetric particle size distribution Dv50' of the graphite material can be 10μm, 11.1μm, 12μm, 13μm, 15μm, 16μm, or a value within the range obtained by any combination of the above values.

[0086] The Dv50' here is to distinguish it from the Dv50 of other materials mentioned earlier, representing the volume average particle size of different substances.

[0087] When Dv50' is greater than or equal to 10 μm, the risk of agglomeration between graphite particles can be reduced, which is beneficial for the material to be more uniformly distributed in the negative electrode film layer; when Dv50' is less than or equal to 16 μm, the dynamic performance of the battery cell can be improved, which is beneficial for improving the long-term cycle performance of the battery cell.

[0088] In some embodiments, the graphitization degree of the graphite material is 90% to 94%.

[0089] Specifically, the graphitization degree of graphite materials can be 90%, 91%, 92%, 93.2%, 94%, or a value within the range obtained by any combination of the above values.

[0090] Graphitization degree refers to the degree of order in the graphite crystal structure of a material. High graphitization degree means that the carbon atoms in the material are more ordered, forming a more ordered graphite crystal structure. Materials with higher graphitization degree have more direct electron transport paths and better electrical conductivity, which helps to improve the overall conductivity of the battery cell, reduce internal resistance, and reduce the extraction and insertion of lithium ions in the material, thereby helping to improve the power performance and rate performance of the battery cell. In addition, materials with high graphitization degree have smoother and flatter surfaces, which can reduce the number of surface defects. These surface defects are the parts where side reactions occur between the electrolyte and the material, which helps to improve the stability of the battery cell.

[0091] When the graphitization degree of graphite material is not less than 90%, it helps to improve the conductivity of the battery cell and reduce side reactions; when the graphitization degree of graphite material is not greater than 94%, it can prevent the formation of a thick SEI film in the battery cell, avoid excessive consumption of active lithium ions, and reduce the impact on the cycle life of the battery cell.

[0092] In some embodiments, the specific capacity of the graphite material is 330 mAh / g to 355 mAh / g.

[0093] Specifically, the specific capacity of graphite materials can be 330mAh / g, 345mAh / g, 350mAh / g, 355mAh / g, or a value within the range obtained by any combination of the above values.

[0094] When the specific capacity of graphite material is within the above range, the energy density of the battery cell is relatively high, which improves the discharge performance and cycle life of the battery.

[0095] [Positive electrode plate]

[0096] The positive electrode includes a positive current collector and a positive electrode film layer disposed on at least one surface of the positive current collector, the positive electrode film layer including a positive electrode active material.

[0097] As an example, the positive current collector has two surfaces opposite each other in its own thickness direction, and the positive electrode film layer is disposed on either or both of the two opposite surfaces of the positive current collector.

[0098] In some embodiments, the positive current collector may be a metal foil or a composite current collector. For example, aluminum foil may be used as the metal foil. The composite current collector may include a polymer substrate and a metal layer formed on at least one surface of the polymer substrate. The composite current collector may be formed by forming a metal material (aluminum, aluminum alloy, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy, etc.) on a polymer substrate (such as a substrate of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).

[0099] In some embodiments, the positive electrode active material may be a known battery positive electrode active material. As an example, the positive electrode active material may include at least one of the following materials: lithium phosphates with an olivine structure, lithium transition metal oxides, and their respective modified compounds. However, this application is not limited to these materials, and other conventional materials that can be used as battery positive electrode active materials may also be used. These positive electrode active materials may be used alone or in combination of two or more. Examples of lithium transition metal oxides include, but are not limited to, lithium cobalt oxides (such as LiCoO2), lithium nickel oxides (such as LiNiO2), lithium manganese oxides (such as LiMnO2, LiMn2O4), lithium nickel cobalt oxides, lithium manganese cobalt oxides, lithium nickel manganese oxides, and lithium nickel cobalt manganese oxides (such as LiNi). 1 / 3 Co 1 / 3 Mn 1 / 3 O2 (also known as NCM) 333 LiNi 0.5 Co 0.2 Mn 0.3 O2 (also known as NCM) 523 LiNi 0.5 Co 0.25 Mn 0.25 O2 (also known as NCM) 211 LiNi 0.6 Co 0.2 Mn 0.2 O2 (also known as NCM) 622 LiNi 0.8 Co 0.1 Mn 0.1 O2 (also known as NCM) 811 ), lithium nickel cobalt aluminum oxide (such as LiNi) 0.85 Co 0.15 Al 0.05At least one of O2 and its modified compounds. Examples of lithium phosphates with an olivine structure include, but are not limited to, lithium iron phosphate (such as LiFePO4 (also referred to as LFP)), lithium iron phosphate and carbon composites, lithium manganese phosphate (such as LiMnPO4), lithium manganese phosphate and carbon composites, lithium manganese iron phosphate, and lithium manganese iron phosphate and carbon composites.

[0100] In some embodiments, the positive electrode film layer may optionally include a binder. As an example, the binder may include at least one selected from polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), PVDF-tetrafluoroethylene-propylene terpolymer, PVDF-hexafluoropropylene-tetrafluoroethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer, and fluorinated acrylate resin.

[0101] In some embodiments, the positive electrode film may optionally include a conductive agent. As an example, the conductive agent may include at least one selected from superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0102] In some embodiments, the positive electrode sheet can be prepared by dispersing the above-mentioned components for preparing the positive electrode sheet, such as positive active material, conductive agent, binder and any other components, in a solvent (e.g., N-methylpyrrolidone) to form a positive electrode slurry; coating the positive electrode slurry onto the positive electrode current collector, and then obtaining the positive electrode sheet after drying, cold pressing and other processes.

[0103] [Negative electrode plate]

[0104] In some embodiments, the negative electrode sheet may include a negative current collector and a negative electrode film layer disposed on at least one surface of the negative current collector, the negative electrode film layer comprising a negative electrode active material.

[0105] As an example, the negative electrode current collector has two surfaces opposite each other in its own thickness direction, and the negative electrode film layer is disposed on either or both of the two opposite surfaces of the negative electrode current collector.

[0106] In some embodiments, the negative electrode current collector may be a metal foil or a composite current collector. For example, copper foil may be used as the metal foil. The composite current collector may include a polymer substrate and a metal layer formed on at least one surface of the polymer substrate. The composite current collector may be formed by forming a metal material (copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy, etc.) on a polymer substrate (such as a substrate of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).

[0107] In some embodiments, the negative electrode active material includes graphite material with an OI value of 1.5 to 2.4, and a tap density T of 1.15 g / cm³. 3 ≤T≤1.3g / cm 3 The negative electrode active material may also include at least one of the following materials: natural graphite, soft carbon, hard carbon, silicon-based materials, tin-based materials, and lithium titanate. The silicon-based material may be selected from at least one of elemental silicon, silicon oxide compounds, silicon-carbon composites, silicon-nitrogen composites, and silicon alloys. The tin-based material may be selected from at least one of elemental tin, tin oxide compounds, and tin alloys. However, this application is not limited to these materials, and other conventional materials that can be used as negative electrode active materials for batteries may also be used. These negative electrode active materials may be used alone or in combination of two or more.

[0108] In some embodiments, the negative electrode film layer may optionally include a binder. The binder may be selected from at least one of styrene-butadiene rubber (SBR), polyacrylic acid (PAA), sodium polyacrylate (PAAS), polyacrylamide (PAM), polyvinyl alcohol (PVA), sodium alginate (SA), polymethacrylic acid (PMAA), and carboxymethyl chitosan (CMCS).

[0109] In some embodiments, the negative electrode film may optionally include a conductive agent. The conductive agent may be selected from at least one of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0110] In some embodiments, the negative electrode film may optionally include other additives, such as thickeners (e.g., sodium carboxymethyl cellulose (CMC-Na)).

[0111] In some embodiments, the negative electrode sheet can be prepared by dispersing the components used to prepare the negative electrode sheet, such as the negative electrode active material, conductive agent, binder and any other components, in a solvent (e.g., deionized water) to form a negative electrode slurry; coating the negative electrode slurry onto the negative electrode current collector, and then obtaining the negative electrode sheet after drying, cold pressing and other processes.

[0112] [Electrolytes]

[0113] The electrolyte acts as a conductor of ions between the positive and negative electrodes. This application does not impose specific restrictions on the type of electrolyte; it can be selected according to requirements. For example, the electrolyte can be liquid, gel, or entirely solid.

[0114] In some embodiments, the electrolyte is an electrolyte solution. The electrolyte solution includes an electrolyte salt and a solvent.

[0115] For lithium-ion battery cells or lithium metal battery cells, the electrolyte salt may include one or more of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium perchlorate, lithium hexafluoroarsenate, lithium bis(fluorosulfonyl)imide, lithium bis(trifluoromethanesulfonyl)imide, lithium trifluoromethanesulfonate, lithium difluorophosphate, lithium difluorooxalate borate, lithium dioxalate borate, lithium difluorodioxalate phosphate, and lithium tetrafluorooxalate phosphate.

[0116] For lithium-ion battery cells or lithium metal battery cells, the solvent may include one or more of the following: ethylene carbonate, propylene carbonate, methyl ethyl carbonate, diethyl carbonate, dimethyl carbonate, dipropyl carbonate, methyl propyl carbonate, ethyl propyl carbonate, butyl carbonate, fluoroethylene carbonate, methyl formate, methyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, propyl propionate, methyl butyrate, ethyl butyrate, 1,4-butyrolactone, sulfolane, dimethyl sulfone, methyl ethyl sulfone, and diethyl sulfone.

[0117] For sodium-ion battery cells or sodium metal battery cells, the electrolyte salt may include at least one of NaPF6, NaBF4, NaN(SO2F)2, NaClO4, NaAsF6, NaB(C2O4)2, NaBF2(C2O4), NaN(SO2RF)2, and NaN(SO2F)(SO2RF), where RF includes C b F 2b+1 b is an integer from 1 to 10; optionally, the electrolyte salt includes at least one of NaPF6, NaN(SO2F)2, and NaBF2(C2O4); optionally, b is an integer from 1 to 3; optionally, RF includes at least one of CF3, C2F5, and CF2CF2CF3.

[0118] For sodium-ion battery cells or sodium metal battery cells, the solvent may include at least one of ethylene carbonate, propylene carbonate, methyl ethyl carbonate, diethyl carbonate, dimethyl carbonate, dipropyl carbonate, methyl propyl carbonate, ethyl propyl carbonate, butyl carbonate, fluoroethylene carbonate, methyl formate, methyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, methyl butyrate, ethyl butyrate, 1,4-butyrolactone, sulfolane, dimethyl sulfone, methyl ethyl sulfone, diethyl sulfone, 1,3-dioxolane, tetrahydrofuran, ethylene glycol dimethyl ether, and acetonitrile; optionally, the solvent may include at least one of ethylene carbonate, propylene carbonate, methyl ethyl carbonate, diethyl carbonate, dimethyl carbonate, dipropyl carbonate, methyl propyl carbonate, ethyl propyl carbonate, and butyl carbonate.

[0119] In some embodiments, the electrolyte may optionally include additives. For example, additives may include negative electrode film-forming additives, positive electrode film-forming additives, and may also include additives that can improve certain battery performance, such as additives that improve battery overcharge performance, additives that improve battery high-temperature or low-temperature performance, etc.

[0120] [Isolation membrane]

[0121] This application does not impose any particular restrictions on the type of separator membrane; any known porous separator membrane with good chemical and mechanical stability can be selected.

[0122] In some embodiments, the material of the separator can be selected from at least one of glass fiber, nonwoven fabric, polyethylene, polypropylene, and polyvinylidene fluoride. The separator can be a single-layer film or a multi-layer composite film, without particular limitation. When the separator is a multi-layer composite film, the materials of each layer can be the same or different, without particular limitation.

[0123] In some implementations, the positive electrode, negative electrode, and separator can be fabricated into an electrode assembly using a winding or stacking process.

[0124] [Battery Device]

[0125] In some embodiments, the secondary battery may include an outer packaging. This outer packaging may be used to encapsulate the electrode assembly and electrolyte described above.

[0126] In some embodiments, the outer packaging of the secondary battery can be a hard shell, such as a hard plastic shell, an aluminum shell, or a steel shell. The outer packaging of the secondary battery can also be a soft pack, such as a pouch. The material of the soft pack can be plastic; examples of plastics include polypropylene, polybutylene terephthalate, and polybutylene succinate.

[0127] This application does not impose any particular limitation on the shape of the secondary battery; it can be cylindrical, square, or any other arbitrary shape. For example, Figure 3 This is a square-structured battery cell 3, used as an example.

[0128] In some implementations, refer to Figure 3 The battery cell 3 includes a housing 31, an end cap assembly 32, and an electrode assembly 33 disposed within the housing 31. The housing 31 may include a base plate and side plates connected to the base plate, the base plate and side plates forming a receiving cavity. The housing 31 has an opening communicating with the receiving cavity, and the end cap assembly 32 can be closed by covering the opening. The end cap assembly 32 includes electrode terminals 322, such as... Figure 3As shown, the end cap assembly 32 includes two electrode terminals 322, one of which is a positive electrode terminal and the other is a negative electrode terminal. The electrode assembly 33 is encapsulated within the receiving cavity. Electrolyte is immersed in the electrode assembly 33. The positive electrode sheet, negative electrode sheet, and separator can be formed into the electrode assembly 33 via a winding process or a stacking process. The electrode assembly 33 includes an electrode assembly body 330 and tabs 331 extending from the electrode assembly body 330. The battery cell 3 also includes a connecting member 34 for connecting the tabs 331 and the electrode terminals 322 of the electrode assembly 33. The battery cell 3 can contain one or more electrode assemblies 33, which can be selected by those skilled in the art according to specific practical needs.

[0129] In some implementations, the secondary batteries can be assembled into a battery module, and the number of secondary batteries contained in the battery module can be one or more, the specific number of which can be selected by those skilled in the art according to the application and capacity of the battery module.

[0130] Figure 4 This is a battery 4 as an example. Referring to the figure, in battery 4, multiple battery cells 3 can be arranged sequentially along the length of battery 4. Of course, they can also be arranged in any other arbitrary way. Furthermore, these multiple battery cells 3 can be fixed in place by fasteners.

[0131] Optionally, the battery 4 may also include a housing with a receiving space in which multiple battery cells 3 are housed.

[0132] In some embodiments, the battery modules described above can also be assembled into a battery / battery pack. The number of battery modules contained in the battery pack can be one or more, and the specific number can be selected by those skilled in the art according to the application and capacity of the battery pack.

[0133] [Electrical appliances]

[0134] In addition, this application also provides an electrical device, which includes at least one of the secondary battery, battery module, or battery pack provided in this application. The secondary battery, battery module, or battery pack can be used as a power source for the electrical device, or as an energy storage unit for the electrical device. The electrical device may include, but is not limited to, mobile devices (e.g., mobile phones, laptops, etc.), electric vehicles (e.g., pure electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, electric bicycles, electric scooters, electric golf carts, electric trucks, etc.), electric trains, ships and satellites, energy storage systems, etc.

[0135] As the electrical device, a secondary battery, battery module, or battery pack can be selected according to its usage requirements.

[0136] Figure 5Here is an example of an electrical device 5. This electrical device is a pure electric vehicle, a hybrid electric vehicle, or a plug-in hybrid electric vehicle, etc. To meet the high power and high energy density requirements of the secondary battery for this electrical device, a battery pack or battery module can be used.

[0137] Another example device could be a mobile phone, tablet, or laptop. These devices typically require a slim and lightweight design and can use a rechargeable battery as their power source.

[0138] [Example]

[0139] The following describes embodiments of this application. The embodiments described below are exemplary and are only used to explain this application, and should not be construed as limiting this application. Where specific techniques or conditions are not specified in the embodiments, they are performed according to the techniques or conditions described in the literature in this field or according to the product instructions. Reagents or instruments used, unless otherwise specified, are all conventional products that can be obtained commercially.

[0140] Example 1

[0141] (1) Preparation of positive electrode sheet

[0142] Lithium iron phosphate, conductive carbon black, and polyvinylidene fluoride (PVDF) were dissolved in N-methylpyrrolidone (NMP) at a mass ratio of 96%:2%:2% and thoroughly mixed to prepare a positive electrode slurry. The positive electrode slurry was then uniformly coated on two opposite surfaces of the positive electrode current collector aluminum foil, and subsequently dried, cold-pressed, and slit to obtain the positive electrode sheet.

[0143] (2) Preparation of negative electrode sheet

[0144] Petroleum coke was crushed and classified to obtain a first aggregate with a volumetric particle size distribution (Dv50) of 3 μm and a particle size distribution (K) value of 1.71. The first aggregate was mechanically shaped to obtain a second aggregate with a volumetric particle size distribution (Dv50) of 3 μm and a particle size distribution (K') value of 1.46. The second aggregate and binder asphalt were mixed at a mass ratio of 100:10. The resulting mixture was placed in an isostatic press and pressurized to 200 MPa at a pressurization rate of 3 MPa / min. After stabilizing the pressure for 60 min, the pressure was released at a depressurization rate of 3 MPa / min to form a composite block. The composite block was then crushed and classified a second time to obtain an intermediate with a volumetric particle size distribution (Dv50') of 10.8 μm. The intermediate was then subjected to high-temperature graphitization at 3000℃ to obtain graphite material. The prepared graphite material, conductive carbon black (Super P), thickener sodium carboxymethyl cellulose (CMC-Na), and binder styrene-butadiene rubber (SBR) were dissolved in deionized water at a mass ratio of 96.4:1:1.2:1.4 and thoroughly mixed to prepare a negative electrode slurry. The negative electrode slurry was coated onto a copper foil negative electrode current collector, and then dried, cold-pressed, and slit to obtain the negative electrode sheet.

[0145] (3) Separating membrane

[0146] A polyethylene film with a thickness of 12μm was used as the separator.

[0147] (4) Preparation of electrolyte

[0148] The organic solvents ethylene carbonate (EC), ethyl methyl carbonate (EMC), and diethyl carbonate (DEC) were mixed in a volume ratio of 1:1:1 to obtain a mixed solvent. Then, a thoroughly dried lithium salt (LiPF6) was dissolved in the above mixed solvent at a ratio of 1 mol / L to obtain an electrolyte.

[0149] (5) Preparation of battery cells

[0150] The positive electrode sheet, separator, and negative electrode sheet are stacked, wound, and hot-pressed in sequence to obtain an electrode assembly. The electrode assembly is placed in an outer packaging, and the electrolyte prepared above is added. After encapsulation, standing, formation, aging and other processes, a battery cell is obtained.

[0151] Example 2

[0152] Compared with Example 1, the volumetric particle size distribution Dv50 of the first aggregate in Example 2 is 5.0 μm.

[0153] Example 3

[0154] Compared with Example 1, the second aggregate particle size distribution K value in Example 3 is 1.35.

[0155] Example 4

[0156] Compared with Example 1, the second aggregate particle size distribution K value in Example 4 is 1.55.

[0157] Comparative Example 1

[0158] Compared with Example 1, Comparative Example 1 directly obtained the intermediate by granulation of the kneaded material in a horizontal reactor, without pressing the kneaded material into blocks through a molding process and then crushing and classifying it to obtain the intermediate.

[0159] Comparative Example 2

[0160] Compared with Example 1, Comparative Example 2 did not mechanically shape the first aggregate.

[0161] The battery cells obtained in Examples 1-4 and Comparative Examples 1-2 were subjected to parameter and performance tests. The test results are shown in Table 1 below.

[0162] Table 1: Relevant parameters and test results of Examples 1-4 and Comparative Examples 1-2

[0163]

[0164]

[0165] (1) Particle size Dv50 test

[0166] Particle size analysis can be performed using a laser particle size analyzer (Malvin 3000, MasterSizer 3000) to measure the particle size of the graphite anode sample and the aggregate, respectively. A helium-neon red light source is used as the main light source. Take a clean small beaker, add 1g of the sample to be tested, add 20ml of deionized water, and sonicate at 53kHz / 120W for 5 minutes to ensure complete dispersion. Turn on the laser particle size analyzer, clean the optical path system, and automatically test the background. Stir the sonicated solution to ensure uniform dispersion, place it in the sample cell as required, and then measure the sample according to GB / T19077-2016 / ISO 13320:2009 standard.

[0167] (2) Particle strength test

[0168] The graphite anode material was placed on the sample stage and held under a pressure of 2T for 5 seconds. Its particle size D50 was then measured. The particle strength was calculated using the following formula: Particle strength = Particle size D50 of graphite anode material after holding pressure / Particle size D50 of graphite anode material before holding pressure.

[0169] (3) Compaction density test

[0170] A certain amount of powder is placed in a compaction mold. The powder sample area is s, the mass is m, and the thickness is h1. The mold is then placed on a compaction density instrument, and different pressures are set. The thickness h2 (thickness after depressurization) of the powder under different pressures can be read on the instrument. The compaction density is calculated using the following formula: Compaction density = m / [s×(h1-h2)], with units of g / cm³. 3 .

[0171] The measurement deviation of compacted density is within ±0.05 g / cm³. 3 Within the range.

[0172] (4) Specific surface area test

[0173] After measuring the amount of gas adsorbed on the solid surface at a pressure of 20 MPa under constant temperature, the amount of monolayer adsorption of the sample was obtained based on the Brown-Etter-Taylor (BET) multilayer adsorption theory and its formula, thereby calculating the specific surface area of ​​the solid.

[0174] (5) Tap density test

[0175] The mass per unit volume of powder in a container after it has been compacted under specified conditions is determined according to the standard GB / T 5162-2006.

[0176] (6) Gram capacity test

[0177] At 25°C, the coin cell half-cell with the negative electrode sheet of Example 1 prepared above was first discharged to 0.005V with a constant current of 50μA, allowed to stand for 5 minutes, and then discharged to 0.005V with a constant current of 10μA. The first discharge capacity of the coin cell was recorded. After that, it was charged to 2.0V with a constant current of 0.1mA, and the first charge capacity of the coin cell was recorded.

[0178] Figure 2 This is a first charge-discharge curve diagram according to an embodiment of this application, in conjunction with... Figure 2 As shown, the initial discharge capacity is greater than 330 mAh / g, indicating a relatively high discharge capacity. By improving the isotropy of the material, the tap density of the material increases, thereby improving the specific capacity of the battery cell.

[0179] (7) OI value test

[0180] The OI value of the negative electrode graphite material can be tested using instruments and methods known in the art. For example, an X-ray diffractometer (such as a Bruker D8 Discover) can be used for testing, and the testing can be referenced in JIS K0131-1996 and JB / T 4220-2011 to obtain the X-ray diffraction pattern of the powder sample. The OI value is calculated using the formula: OI = I 004 / I 110 The OI value of the powder in the sample was calculated.004 I is the integrated area of ​​the diffraction peak of the (004) crystal plane in the powder sample. 110 The integral area of ​​the diffraction peak of the (110) crystal plane in the powder sample. In the X-ray diffraction analysis test of this application, a copper target can be used as the anode target, CuKα rays can be used as the radiation source, the ray wavelength scanning 2θ angle range is 20°~80°, and the scanning rate is 4° / min. Among them, the test is based on the results of the battery after formation or cycling, and the battery is disassembled.

[0181] As shown in Examples 1-4 and Comparative Examples 1-2, compared to battery cells prepared from graphite materials without mechanical shaping and briquetting, battery cells prepared from graphite materials obtained by crushing and shaping the coking raw materials and then briquetting and crushing the mixed materials exhibit improved specific capacity, initial graphitization degree, particle strength, isotropy, and tap density, while simultaneously reducing the cycle expansion rate. This indicates that using uniform, small-diameter aggregates for briquetting can enhance the particle strength of the material, improve its isotropy, reduce volume expansion during graphite cycling, and improve kinetic performance.

[0182] Comparative analysis of Examples 1 and 2 shows that crushing and classifying coke raw materials into small-particle-size aggregates can improve the material's recycling performance and reduce the expansion rate of graphite materials. As the particle size of the first aggregate decreases, the particle strength, tap density, isotropy, and recycling performance all improve.

[0183] Comparative analysis of Examples 1 and 3-4 shows that further mechanically shaping the first aggregate into uniform particles can improve the isotropy of the material, thereby reducing the risk of expansion of the graphite material. As the K' value decreases, the particle strength, isotropy, tap density, and cycle performance also increase.

[0184] It should be noted that this application is not limited to the above-described embodiments. The above embodiments are merely examples, and any embodiments with the same structure and effect as the technical concept within the scope of this application are included in the technical scope of this application. Furthermore, various modifications that can be conceived by those skilled in the art to the embodiments, and other ways of constructing by combining some of the constituent elements of the embodiments, without departing from the spirit of this application, are also included in the scope of this application.

Claims

1. A method for preparing a single battery cell, characterized in that, include: The coke raw material is crushed and graded to obtain the first aggregate. The volumetric particle size distribution Dv50 of the first aggregate is 2μm to 5μm, and the particle size distribution K value of the first aggregate is 1.6 to 1.

8. The first aggregate is mechanically shaped to obtain the second aggregate, and the particle size distribution K' value of the second aggregate is 1.35 to 1.

55. The second aggregate is mixed with the binder to obtain a mixed material; The mixed material is pressed into composite blocks by a molding process, and the composite blocks are subjected to secondary crushing and grading to obtain intermediates. The intermediate is subjected to high-temperature graphitization treatment to obtain graphite material; The graphite material is used to prepare a negative electrode sheet for the preparation of a battery cell.

2. The method according to claim 1, characterized in that, The coke raw material includes at least one of petroleum coke, isopriate coke, needle coke, and pitch coke.

3. The method according to claim 1 or 2, characterized in that, The molding process includes at least one of the following: molding, extrusion, and isostatic pressing.

4. The method according to any one of claims 1 to 3, characterized in that, The mass ratio of the second aggregate to the binder is 100:(5-15).

5. The method according to any one of claims 1 to 4, characterized in that, The step of mixing the second aggregate with the binder to form a mixed material includes: mixing the second aggregate with the binder at the softening point of the binder, wherein the softening point is between 50°C and 80°C.

6. The method according to any one of claims 1 to 5, characterized in that, The adhesive includes at least one of asphalt, phenolic resin, furfural resin, and epoxy resin.

7. The method according to any one of claims 1 to 6, characterized in that, The high-temperature graphitization process is carried out at a temperature of 3000℃ or higher.

8. A single battery cell, characterized in that, include: A negative electrode sheet, the negative electrode sheet comprising a negative current collector and a negative electrode film layer, the negative electrode film layer being disposed on at least one surface of the negative current collector, the negative electrode film layer comprising a graphite material; The OI value of the graphite material is 1.5 to 2.4; The tap density T of the graphite material satisfies: 1.15 g / cm³ 3 ≤T≤1.3g / cm 3 .

9. The battery cell according to claim 8, characterized in that, The particle strength of the graphite material is 93% to 98%.

10. The battery cell according to claim 8 or 9, characterized in that, The powder compaction density of the graphite material is 1.6 g / CC to 1.9 g / CC.

11. The battery cell according to any one of claims 8 to 10, characterized in that, The specific surface area of ​​the graphite material is 1.5 m². 2 / g~2.6m 2 / g.

12. The battery cell according to any one of claims 8 to 11, characterized in that, The volumetric particle size distribution Dv50' of the graphite material satisfies: 10μm≤Dv50'≤16μm.

13. The battery cell according to any one of claims 8 to 12, characterized in that, The graphitization degree of the graphite material is 90% to 94%.

14. The battery cell according to any one of claims 8 to 13, characterized in that, The specific capacity of the graphite material is 330mAh / g to 355mAh / g.

15. A battery, characterized in that, Includes battery cells prepared by the method of any one of claims 1-7, and / or battery cells as described in any one of claims 8-14.

16. An electrical appliance, characterized in that, Includes the battery as described in claim 15.

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