Battery and electrical device

Abstract

A battery comprising a negative electrode, a positive electrode, and a separator, wherein the negative electrode comprises a current collector and a negative active material layer arranged on the surface of the current collector, the negative active material layer comprising a silicon-based material, characterized in that the cohesive force of the negative electrode is designated by "A" in units of "N / m"; the separator is arranged in a direction parallel to the direction in which a tab extends outwards, such that it extends beyond the negative electrode near the side of the tab, the dimension of the separator extending beyond the negative electrode being designated by "B" in units of "mm"; the mass fraction of elemental silicon in the negative active material layer being designated by "C"; wherein "A", "B", and "C" satisfy the following relationship: 0.03 ≤ A 1 / 2*C / B ≤ 3.

Description

TECHNICAL AREA

[0001] The present invention relates to the technical field of batteries, and in particular to a battery and an electrical device. STATE OF THE ART

[0002] To achieve a high theoretical gram-based capacity in the battery, it is generally necessary to use silicon-containing negative active materials in the negative electrode; however, the use of silicon-based negative materials also presents some challenges and limitations. For example, the volume expansion of the silicon negative material can be up to 300%. When the negative electrode contains silicon material, it exhibits a greater tendency to elongate. This elongation of the negative electrode increases the risk of a short circuit between the negative and positive electrodes, thereby compromising the cell's safety characteristics. BRIEF SUMMARY OF THE INVENTION

[0003] Therefore, one object of the present invention is to provide a battery and an electrical device in which electrochemical properties such as energy density and cycle stability are ensured without compromising the safety characteristics of the battery.

[0004] To solve the aforementioned problem, the present invention provides a battery comprising a negative electrode, a positive electrode, and a separator, wherein the negative electrode has a current collector and a negative active material layer arranged on the surface of the current collector, wherein the negative active material layer comprises a silicon-based material, wherein the cohesive force of the negative electrode is designated as "A" in units of "N / m"; wherein, in a direction parallel to the direction in which a tab is extended outwards, the separator is arranged such that it extends beyond the negative electrode near the side of the tab, wherein the dimension of the separator extending beyond the negative electrode is designated as "B" in units of "mm"; wherein the mass fraction of elemental silicon in the negative active material layer is designated as "C";where “A”, “B” and “C” satisfy the following relationship: 0.03 ≤A; 1 / 2 *C / B ≤ 3.

[0005] The present invention also provides an electrical device which includes the battery described above.

[0006] The present invention has the following advantageous effects: The battery according to the present invention comprises a negative electrode, a positive electrode, and a separator, wherein the negative electrode comprises a current collector and a negative active material layer arranged on the surface of the current collector, the negative active material layer comprising a silicon-based material; wherein the cohesive force of the negative electrode is designated as "A" in units of "N / m"; wherein the separator is arranged in a direction parallel to the direction in which a tab is extended outwards such that it extends beyond the negative electrode near the side of the tab, the dimension of the separator extending beyond the negative electrode being designated as "B" in units of "mm"; wherein the mass fraction of elemental silicon in the negative active material layer is designated as "C".By comprehensively controlling the area so that it is 0.03 < A. 1 / 2 *C / B ≤ 3 corresponds to the present invention, providing a battery with high safety characteristics, while at the same time ensuring good energy density and cycle stability. DETAILED DESCRIPTION OF EXECUTION FORMS

[0007] The following examples serve to better understand the present invention and are not intended to limit the best embodiment or to restrict the scope and content of the present invention. All products that are identical or similar to the present invention and that are derived from the teachings of the present invention or by combining the present invention with features of other prior art techniques are to be considered as falling within the scope of protection of the present invention.

[0008] If no specific experimental steps or conditions are given in the examples, the conventional experimental steps or conditions described in the literature on this subject may be used. If no information is given about the manufacturer of the reagents or instruments, they are commercially available, conventional reagents.

[0009] The “ranges” disclosed in the present invention are defined by lower and upper limits, wherein a given range is defined by selecting a lower and an upper limit, the selected lower and upper limits defining the boundaries of the range in question. Ranges defined in this way can include or exclude the end values, and they can be combined arbitrarily. That is to say, any lower limit can be combined with any upper limit to form a range. For example, if ranges of 50% to 90% and 60% to 80% are listed for a specific parameter, it is understood that ranges of 50% to 80% and 60% to 90% are also provided.If minimum range values ​​of 1 and 2 are listed, and maximum range values ​​of 3, 4, and 5 are listed, then all of the following ranges are provided for: 1 to 3, 1 to 4, 1 to 5, 2 to 3, 2 to 4, and 2 to 5. Unless otherwise stated, the numerical range "a to b" in this application represents a shorthand for any combination of real numbers between a and b, where both a and b are real numbers. For example, the numerical range "0.5 to 4" means that, in this case, all real numbers in the range "1 to 4" are listed, such as: 0.5, 1, 1.5, 2, 2.5, 3, 3.5, 4, etc., where "0.5 to 4" is merely a shorthand for these combinations of numbers.

[0010] The present invention provides a battery comprising a negative electrode, a positive electrode, and a separator. The negative electrode includes a current collector and a negative active material layer arranged on the surface of the current collector. The negative active material layer comprises a silicon-based material. The cohesive force of the negative electrode is "A" in units of "N / m". The separator is arranged in a direction parallel to the direction in which a tab extends outwards, such that it extends beyond the negative electrode near the side of the tab. The dimension of the separator extending beyond the negative electrode is "B" in units of "mm". The mass fraction of elemental silicon in the negative active material layer is "C". "A", "B", and "C" satisfy the following relationship: 0.03 ≤ A 1 / 2*C / B ≤ 3. In the present invention, the value of A can be 1 / 2 * C / B can take any value between 0.03 and 3, for example 0.03, 0.05, 0.1, 0.3, 0.5, 1, 1.5, 2, 2.5, 3, etc.

[0011] In the present invention, “C” refers to the mass percentage of elemental silicon in the negative active material layer. By adding silicon material to the negative active material layer, the overall energy density of the battery can be increased. “A” represents the cohesive force of the negative electrode, which refers to the bond strength between the negative active particles in the active coating of the negative electrode. “B” represents the dimension of the separator, which extends beyond the negative electrode near the side of the tab. The separator is arranged between the positive and negative electrodes to prevent short circuits between them. The separator is generally arranged to extend beyond the negative electrode.The tab is exposed to overcurrent, and the current density near the tab is relatively high. The negative active material layer near the tab is the first to undergo the electrochemical reaction of lithium ion intercalation, causing the negative electrode to elongate further. This can easily lead to a short circuit with the positive electrode, resulting in an internal short circuit.

[0012] The present application solves the problem of ensuring electrochemical properties such as energy density and cycle stability without compromising the battery's safety characteristics by comprehensively controlling the relationship between the mass fraction "C" of elemental silicon, the cohesive force "A" of the negative electrode, and the dimension "B" of the separator, which extends beyond the negative electrode near the side of the tab. In particular, the addition of silicon material to the negative electrode improves the overall energy density of the battery; however, the addition of silicon material also causes a greater volume expansion of the negative electrode, which in turn increases its length; the cohesive force reflects the bonding force between the active particles of the negative electrode.If the cohesive force is low, the bond strength between the particles is weak, and the electrode expands considerably in the thickness direction. This can easily lead to a loss of electrical contact between the active material and the current collector, resulting in rapid capacity degradation and low cycle life. Conversely, if the cohesive force is too high, the negative electrode expands, potentially causing a short circuit between the negative and positive electrodes. To prevent short circuits in the battery, the dimensions of the negative electrode must be adjusted to a larger separator. However, this reduces the battery's usable space, resulting in a low energy density and wasted space.This can further increase the battery's internal resistance, impair the lithium-ion transfer rate, accelerate capacity loss, and thus reduce the battery's cycle life. According to the present invention, the cohesive force "A" undergoes an exponential transformation to smooth its fluctuations and thus enable more suitable data evaluation and application. In summary, in the present invention, when "A. 1 / 2 *C / B is too large, the silicon content increases, the cohesive force increases, the electrode extension increases, the separator extending beyond the negative electrode becomes too small, and the risk of short circuits between the positive and negative electrodes increases. If “A 1 / 2*C / B” assumes values ​​that are too small, the silicon content is low, the energy density is low, the separator extending beyond the negative electrode becomes too small, and the battery's energy density is low. If the cohesive force assumes values ​​that are too small, the particle-particle bond strength is weak, and the electrode expands considerably in its thickness direction, which can easily lead to a loss of electrical contact between the active material and the current collector, resulting in rapid capacity degradation and low cycle life. In other words, the present invention enables, by “A 1 / 2 *C / B“ is comprehensively controlled in such a way that it lies in the range of 0.03 to 3, to provide a battery with high safety characteristics while ensuring high energy density, high cycle stability and other electrochemical properties.

[0013] Furthermore, the present invention achieves by increasing the value of “A 1 / 2 *C / B“ is controlled such that it lies within the more preferred range of 0.045 to 1.4, safety characteristics, energy density and cycle stability of an improved type.

[0014] In a preferred embodiment, the cohesive force “A” of the negative electrode is in the range of 0.3 to 220 N / m, preferably from 5 to 150 N / m. The cohesive force “A” represents the bond strength between particles in the negative active material layer. The value of “A” should be neither too high nor too low. If the value of “A” is too low, the particle-particle bond is weak, leading to significant expansion across the entire thickness of the electrode. This results in a loss of electrical contact between the active material and the current collector, rapid capacitance degradation, and low cycle life. If the value of “A” is too high, expansion across the thickness of the negative electrode is suppressed, but horizontal expansion is increased. By controlling this horizontal expansion of the negative electrode, the risk of a short circuit with the positive terminal is reduced.For example, “A” can be controlled such that it is 0.3 N / m, 0.5 N / m, 1 N / m, 3 N / m, 5 N / m, 7 N / m, 10 N / m, 30 N / m, 50 N / m, 80 N / m, 100 N / m, 120 N / m, 150 N / m, 180 N / m, 200 N / m, 220 N / m, etc.

[0015] The present invention is not subject to any restrictions regarding the method for adjusting the cohesive force “A” of the negative electrode. For example, it can be adjusted by modifying the type and proportion of the binder used in the manufacture of the negative electrode or by controlling parameters such as temperature and pressure. In the present application, the adjustment is primarily based on the type and proportion of the binder.

[0016] In a preferred embodiment, the value of "B" is in the range of 1 to 4 mm. The value range for "B" should be neither too large nor too small. A large "B" reduces the battery's space utilization, resulting in unused space and reduced energy density, while simultaneously increasing internal resistance and impairing cycle stability. A small "B" does not meet the requirements for the negative electrode extension, which affects safety characteristics. In the present invention, the value of "B" is controlled to be between 1 and 4 mm, preferably 1.5 and 3 mm, in order to effectively balance safety characteristics, energy density, and cycle stability. The value of "B" can be set, for example, to 1, 1.5, 2, 2.5, 3, 3.5, 4, etc.

[0017] In a preferred embodiment, the value of "C" is controlled such that it lies within a suitable range, thereby improving the battery's energy density while simultaneously preventing excessive elongation of the negative electrode to ensure safety characteristics. The value of "C" must not be too high or too low. If the value of "C" is too low, the energy density will be insufficient. If the value of "C" is too high, the elemental silicon will undergo significant volume expansion during charging and discharging. The corresponding negative electrode will also expand excessively in the horizontal direction, potentially extending beyond the separator and short-circuiting the positive electrode.According to the present invention, the mass fraction “C” of elemental silicon in the negative active material layer is controlled to be between 1.5% and 30%, preferably between 4% and 20%, in order to improve the energy density of the battery while simultaneously preventing excessive expansion of the negative electrode, thus ensuring the safety characteristics. For example, the mass fraction “C” of elemental silicon in the negative active material layer can be set to 1.5%, 2%, 3%, 5%, 10%, 12%, 15%, 20%, 25%, 30%, etc.

[0018] The present invention further optimizes the areal density of the negative active material layer. A low areal density leads to a low negative electrode capacitance, while a high areal density increases the electrode extent and the risk of a short circuit with the positive electrode. Therefore, the areal density in the present invention is 60 to 300 g / m². 2 For example, the areal density can be reduced to 60 g / m². 2 , 80 g / m 2 , 100 g / m 2 , 150 g / m 2 , 200 g / m 2 , 250 g / m 2 , 300 g / m 2 etc. will be adjusted.

[0019] Within the scope of the present invention, the method for adjusting the areal density of the negative active material layer is subject to no restrictions. For example, the areal density of the negative active material layer in the present invention can be controlled by parameters such as layer thickness, degree of rolling, and temperature during the negative electrode process.

[0020] In the present invention, the silicon-based material may comprise a silicon-carbon material and / or a silicon-oxygen material. In particular, the silicon-based material may be one or more negative silicon-carbon composite materials, negative silicon monoxide materials, modified negative silicon monoxide materials, or nano-silicon materials.

[0021] If the silicon-based material incorporates a silicon-carbon material, the silicon-carbon material is a silicon-carbon composite containing a porous carbon matrix and silicon particles deposited within that matrix. The porous carbon matrix acts as a buffer by reducing the volume expansion of the negative electrode during charging and discharging. Therefore, if the silicon-based material is a silicon-carbon material, the porous carbon can reduce the expansion of the negative electrode. 1 / 2 *C / B“ is further controlled in such a way that it lies within 0.045 to 1, the energy density can be further improved while maintaining cycle stability.

[0022] Furthermore, the negative active material layer can also include one or more of artificial graphite, natural graphite, and hard carbon.

[0023] The following describes embodiments of an electrochemical device and an electrical device according to the present invention. Unnecessarily detailed descriptions may be omitted. For example, detailed descriptions of well-known substances and repeated descriptions of essentially similar structures may be left out. This is to avoid making the following description unnecessarily lengthy and to facilitate understanding by those skilled in the art. Furthermore, the following description is provided to those skilled in the art for a complete understanding of the present application and is not intended to limit the subject matter specified in the claims. [Battery]

[0024] The battery in question is a secondary battery, also known as a rechargeable battery or storage battery, which is a battery that can be recharged to reactivate the active material after the battery has been discharged and to allow further use.

[0025] A typical secondary battery consists of an electrode assembly, an electrolyte, and an outer casing. The electrode assembly comprises a positive electrode, a negative electrode, and a separator. The electrode assembly and electrolyte are housed within the outer casing. During the charging and discharging process, active ions (such as lithium ions) are intercalated and released between the positive and negative electrodes. The separator, located between the positive and negative electrodes, primarily prevents short circuits between them while allowing the active ions to pass through. The electrolyte, situated between the positive and negative electrodes, mainly serves to conduct the active ions.

[0026] For example, the process for manufacturing a secondary battery proceeds as follows: the positive electrode, separator, and negative electrode are stacked on top of each other, with the separator positioned between the positive and negative electrodes for insulation. They are then wound or stacked to form an electrode assembly. The electrode assembly is subsequently placed in an outer packaging, dried, and then filled with electrolyte. The secondary battery is obtained through vacuum packaging, maturation, assembly, and shaping. [Positive electrode]

[0027] The positive electrode typically includes a positive current collector and a positive foil layer arranged on at least one side of the positive current collector. The positive foil layer includes a positive active material. This positive active material may be one of the previously disclosed positive active materials or an optimized version of an existing positive active material.

[0028] Within the scope of the present invention, the type of positive active material used in the positive electrode is not subject to any particular restrictions. For example, the positive active material used in the present invention includes lithium-containing transition metal oxides (e.g., LiCoO2), phosphides (e.g., LiFePO4), or lithium intercalation compounds (e.g., lithium cobalt oxide, lithium nickel oxide, and other positive electrode materials for binary lithium batteries, or lithium nickel cobalt manganese oxide, lithium cobalt aluminum oxide, and other positive electrode materials for ternary lithium batteries).

[0029] According to some embodiments, the positive electrode can be produced by the following process: dispersing the components used to produce the positive electrode, such as the positive active material, the conductivity agent, the binder, and all other components, in a solvent (e.g., N-methylpyrrolidone) to form a positive slurry; applying the positive slurry in layers to a positive current collector; and then drying, rolling, and cutting to obtain the positive electrode.

[0030] In the present application, the binder is used to improve adhesion between the particles of the positive active material and between the positive active material and the current collector. The type of binder used in the positive electrode is not subject to any particular restrictions; the binder can be any conventional choice in the field of batteries. In particular, the binder can be polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), polyvinyl alcohol (PVA), styrene-butadiene rubber (SBR), polyacrylonitrile (PAN), polyimide (PI), polyacrylic acid (PAA), polyacrylate, polyolefin, sodium carboxymethylcellulose (CMC), and / or sodium alginate.

[0031] In the present invention, the positive current collector is not subject to any particular restrictions, as long as it is conductive and does not cause any adverse chemical changes in the battery. Examples of materials that can be used are stainless steel, aluminum, nickel, titanium, heated carbon, or aluminum or stainless steel that has undergone a surface treatment with a mixture of carbon, nickel, titanium, and silver. [Negative electrode]

[0032] The negative electrode comprises a negative current collector and a negative active material layer arranged on at least one side of the negative current collector. The negative active material layer comprises a silicon-based material. Within the scope of this application, the type of silicon-based material is not subject to any particular restrictions; the silicon-based material may be a silicon-carbon material and / or a silicon-oxygen material. For example, the silicon-based material may be one or more components of a negative silicon-carbon composite, a negative silicon monoxide material, a negative modified silicon monoxide material, or a nano-silicon material.In some embodiments, the negative active material in the negative active material layer may optionally include artificial graphite, natural graphite and / or hard carbon.

[0033] According to some embodiments, the negative electrode can be produced by the following process: dispersing the components for the production of the negative electrode described above, such as the negative active material, a conductivity agent, a binder, and all other components, in a solvent (e.g., water) to form a negative slurry; applying the negative slurry in layers to the negative current collector; and then drying, rolling, cutting, and other steps to obtain the negative electrode.

[0034] In the present invention, the type of negative conductivity agent is not subject to any particular restrictions. In some embodiments, the negative conductivity agent may, for example, be one or more conventional negative conductivity agents, such as carbon black, carbon nanotubes, etc.

[0035] In the present invention, the type of negative binder is not subject to any specific restrictions. In some embodiments, the binder may, for example, be one or more conventional negative binders such as styrene-butadiene rubber latex (SBR), polyvinylidene fluoride (PVDF), polyacrylic acid (PAA), and sodium carboxymethylcellulose (CMC). In the present invention, the binder is preferably PAA, SBR, and CMC. The mass ratio of PAA, SBR, and CMC may be (34.38 to 74.29) : (20 to 59.38) : (5 to 7.14).

[0036] Within the scope of the present invention, the type of negative current collector is not subject to any particular restrictions. In some embodiments, the negative current collector may, for example, be one of the conventional negative current collectors, such as copper foil. [Electrolyte]

[0037] The electrolyte serves to conduct ions between the positive and negative electrodes. Within the scope of the present invention, the type of electrolyte is not subject to any particular restrictions and can be selected based on requirements. For example, the electrolyte of the present invention can be any electrolyte suitable for electrochemical energy storage devices and known in the field. The electrolyte comprises an electrolyte and a solvent. The electrolyte typically contains a lithium salt, and additives can also be added to the electrolyte.

[0038] Lithium salts include, for example, at least one of the following: lithium hexafluorophosphate (LiPF6), lithium tetrafluoroborate (LiBF4), lithium perchlorate (LiClO4), lithium hexafluoroarsenate (LiAsF6), lithium bis-(fluorosulfonyl)imide (LiFSI), lithium bis-(trifluoromethanesulfonyl)imide (LiTFSI), lithium trifluoromethanesulfonate (LiTFS), lithium difluorooxalatoborate (LiDFOB), lithium dioxalatoborate (LiBOB), lithium difluorophosphate (LiPO2F2), lithium difluorobis-(oxalatophosphate) (LiDFOP), and lithium tetrafluorooxalatophosphate (LiTFOP). The concentration of the electrolyte can range from 0.5 to 5 mol / L.

[0039] The solvents include, in a specific manner, at least one of the following: ethylene carbonate (EC), propylene carbonate (PC), ethyl methyl carbonate (EMC), diethyl carbonate (DEC), dimethyl carbonate (DMC), dipropyl carbonate (DPC), methyl propyl carbonate (MPC), ethyl propyl carbonate (EPC), butylene carbonate (BC), fluoroethylene carbonate (FEC), methyl formate (MF), methyl acetate (MA), ethyl acetate (EA), propyl acetate (PA), methyl propionate (MP), ethyl propionate (EP), propyl propionate (PP), methyl butyrate (MB), ethyl butyrate (EB), 1,4-butanediol (GBL), sulfolane (SF), dimethyl sulfone (MSM), ethyl methyl sulfone (EMS), and diethyl sulfone (ESE).

[0040] In some embodiments, the additive may be, for example, conventional electrolyte additives such as fluoroethylene carbonate (FEC), chloroethyl carbonate (CEC) and vinylene carbonate (VC). [Separator]

[0041] In some embodiments, the secondary battery further includes a separator. Within the scope of the present application, the type of separator is not subject to any particular restrictions; any known porous separators with good chemical and mechanical stability may be used.

[0042] In some embodiments, the separator can be made of PP, PE, or PP / PF, for example. Alternatively, the separator can be constructed such that a coating is applied to a base film. The coating base film can be made of PP, PE, or PP / PF, and the coating can be an inorganic and / or an organic coating. The inorganic coating can be selected from aluminum oxide ceramics, borax, and the like, and the organic coating can be selected from PVDF and the like. Examples and comparative examples

[0043] A battery comprising a positive electrode, a negative electrode, a separator, an electrolyte, and an outer packaging. The battery is manufactured as follows: 1. Production of the positive electrode

[0044] The specific procedure for manufacturing the positive electrode is as follows: The positive active material LiNi 0,8 Co 0,1 Mn 0,1O2 (NCM811) is obtained; the positive active material NCM811, the conductivity agent acetylene carbon black and the binder PVDF are mixed in a mass ratio of 96:2:2, the solvent NMP is added, and the mixture is stirred in a vacuum mixer until the mixture is uniform to obtain a positive slurry; the positive slurry is applied in layers to both surfaces of the aluminum foil, which is dried at room temperature to transfer the mixture to an oven for further drying; subsequently, the positive electrode is obtained by cold rolling and slitting. 2. Production of the negative electrode

[0045] The specific procedure for manufacturing the negative electrode is as follows: The negative active material made of graphite and the silicon-based material are mixed in the mass ratio according to Table 1 to obtain a mixture; the mixture is mixed with the conductivity agent made of acetylene carbon black, the conductivity agent made of SWCNT and the binder to obtain an overall mixture.The amount of conductivity agent made from acetylene carbon black added is 0.95% of the total mixture, the amount of conductivity agent made from SWCNT added is 0.05% of the total mixture, the amount and composition of the binder added are listed in Table 1; deionized water is added under the action of a vacuum stirrer and stirred until the system is uniform to obtain a negative electrode slurry; the negative slurry is applied in layers to both surfaces of a copper foil, dried at room temperature, and then placed in an oven for further drying. After drying, it is cold-rolled and cut to produce a negative electrode with a density of 1.42 g / cm³. 3 to obtain. 3. Obtaining the separator

[0046] The separator used in this example is a coated separator. The base film in the separator is made of polyethylene (PE), and the coating consists of an aluminum oxide ceramic layer. A PE separator of suitable dimensions is cut out based on the separator dimension "B" in Table 2, such that it extends beyond the negative electrode. 4. Preparation of the electrolyte

[0047] The electrolyte is prepared as follows: In a glovebox under an argon atmosphere, fluoroethylene carbonate (FEC), ethyl methyl carbonate (EMC), dimethyl carbonate (DMC), and propylene carbonate (PC) are mixed with an organic solvent in a mass ratio of 15:20:60:5. Thoroughly dried lithium salt LiPF6 is dissolved in the organic solvent mixture, whereupon 0.5% of propane-1,3-sultone, 0.5% of tris-(trimethylsilyl) phosphate, and 1% of vinyl sulfate are added to the electrolyte and stirred until completely dissolved to form an electrolyte with a lithium salt concentration of 1.3 M. 5. Assembling the secondary battery

[0048] The specific procedure is as follows: The positive electrode, separator, and negative electrode are stacked on top of each other in that order, with the separator positioned between the positive and negative electrodes to provide insulation. The electrode assembly is then wound to form a coil. This coil is placed in an outer packaging sleeve, dried, and then filled with electrolyte. The battery then undergoes conventional vacuum packaging, maturation, formation, and shaping processes to produce a lithium-ion secondary battery.

[0049] In the above-mentioned examples and comparative examples, the investigation procedures for the areal density “ρ” of the negative electrode, the cohesive force “A” of the negative electrode, the dimension “B” of the separator extending beyond the negative electrode and the mass fraction “C” of silicon in the negative active material layer are as follows: 1. Investigation of the areal density “ρ”:

[0050] A sampler is used to take a sample from the negative electrode, and the sample with mass "m1" is weighed. The same method is used for the sample from the negative current collector, and the sample from the negative current collector with mass "m2" is weighed. The sample area "S" obtained using the sampler is calculated. The areal density "ρ" of the negative active material layer is given by (m1 - m2) / S, in units of g / m². 2 . 2. Examination of “B”:

[0051] The batteries produced in the examples and comparative examples are discharged at 0.33 C. The batteries are disassembled, and the excess length of the separator relative to the tab of the negative electrode is measured. This length is referred to in the present invention as dimension “B”, in units of mm. 3. Examination of “A”:

[0052] The batteries produced in the examples and comparison examples are discharged at 0.33 C. The negative electrodes are removed and soaked in dimethyl carbonate (DMC) solution for 2 hours. After removal, they are dried for 12 hours at 60 °C.

[0053] A standard steel plate (50 mm x 125 mm) is used as the substrate for the stiffness test. The surface of the steel plate is wiped with a dust-free cloth dipped in alcohol. One side of a 50 mm x 125 mm piece of 3M double-sided adhesive tape is attached to the steel plate to ensure smooth, wrinkle-free adhesion. The negative electrode with the active coating is cut to a 50 mm x 125 mm sample to be tested. The electrode under test is attached to the other adhesive side of the double-sided tape, after which another layer of double-sided tape is applied to the electrode surface to ensure smooth, wrinkle-free adhesion. After rolling with a roller, the tensile gripper of a universal testing machine is used to clamp the steel plate at one end and the 3M tape at the other.The stroke of the tensile testing machine is set to 100 mm, and a tensile test is performed at a speed of 300 mm / min. When the curve displayed in the software-based recording of the tensile testing machine flattens out and the displacement exceeds 80 mm, the machine stops, and the average tensile force in the flattened part of the curve is read, i.e., the cohesive force "A", in units of "N / m". 4. Examination of “C”:

[0054] The silicon content in the negative electrode is determined using the alkaline digestion / ICP method. The battery is specifically discharged at 0.33 C, cleaned with DMC solvent, soaked for 48 hours, and dried at 60 °C. The powder is scraped from the negative active material layer. A sample of the powder is weighed and placed in a nickel crucible previously filled with potassium hydroxide. A small amount of potassium hydroxide is added to cover the sample surface. Two drops of ethanol are added, and the mixture is heated in an electric furnace until the potassium hydroxide is melted and anhydrous. The sample is then transferred to a muffle furnace at 1100 °C and held at this temperature for 8 hours. The nickel crucible is removed and allowed to cool slightly. The sample is transferred to a 300 mL plastic beaker and extracted with hot water. After the reaction, the crucible is washed.The extract is acidified by the addition of HCl, and a mixed acid of hydrogen peroxide and hydrochloric acid is added to more comprehensively convert the silicon-containing compounds into silicon ions. After cooling, the sample is washed with water, transferred to a 100 mL volumetric flask, filled to the mark, and shaken to mix. After allowing the solution to stand, an aliquot is transferred to another 100 mL volumetric flask, filled to the mark, shaken, and allowed to settle to obtain the solution to be analyzed. A blank solution is also prepared as a control. No powder is added to the blank solution. This blank control is prepared according to the protocol to eliminate any possible influence from the handling procedures.

[0055] The test solution is subjected to ICP analysis. The wavelength for element detection is selected, and the experimental conditions are defined. Based on the properties of the sample and the ICP analysis of the solution under investigation, a spectral wavelength of 288.158 nm is selected for silicon detection. The silicon content in the sample is determined by ICP analysis.

[0056] Table 1 shows the parameters and conditions corresponding to the various examples and comparison examples, which were determined using the above investigation method. Table 1 Silicon-based material: Graphite Type of silicon-based material Binder composition ρ A C B Example 1 25,04 : 70,46 Silicon-carbon material 2.3% PAA + 0.7% SBR + 0.2% CMC 120 104 12 1,5 Example 2 40,50 : 54,70 Silicon-carbon material 2.6% PAA + 1.3% SBR + 0.2% CMC 100 136 20 2,5 Example 3 8,22 : 87,78 Silicon-carbon material 1.1% PAA + 1.7% SBR + 0.2% CMC 165 7,5 4 1,6 Example 4 9,64 : 86,36 Silicon-carbon material 1% PAA + 1.8% SBR + 0.2% CMC 160 5,5 4,7 2,3 Example 5 9,07 : 86,93 Silicon-carbon material 1% PAA + 1.7% SBR + 0.2% CMC 165 5 4,5 3 Example 6 40,87 : 54,33 Silicon-carbon material 2.62% PAA + 1.2% SBR + 0.2% CMC 100 150 20 1,6 Example 7 52,69 : 47,31 Silicon-carbon material 2.8% PAA + 1% SBR + 0.2% CMC 80 219 22 1,1 Example 8 36,16 : 54,84 Silicon-carbon material 0.9% PAA + 2.4% SBR + 0.2% CMC 80 0,4 18 3,5 Example 9 16,08 : 79,92 Silicon-carbon material 1% PAA + 1.5% SBR + 0.2% CMC 70 3 8 1,1 Example 10 61,73 : 33,27 Silicon-carbon material 2.68% PAA + 1.2% SBR + 0.2% CMC 178 195 30 3 Example 11 63,81 : 31,19 Silicon-carbon material 2.86% PAA + 1.2% SBR + 0.2% CMC 70 245 32 2 Example 12 50,51 : 44,49 Silicon-oxygen material 2.2% PAA + 1.3% SBR + 0.2% CMC 90 90 25 1 Example 13 50,47 : 44,53 Silicon-carbon material 2.2% PAA + 1.3% SBR + 0.2% CMC 90 90 25 1 Comparison example 1 3,15 : 93,05 Silicon-carbon material 0.9% PAA + 2.1% SBR + 0.2% CMC 178 0,3 1,5 4 Comparison example 2 61,66 : 33,34 Silicon-carbon material 2.7% PAA + 1.1% SBR + 0.2% CMC 70 218 30 1

[0057] Performance tests are conducted on the batteries used in the examples and comparison examples, using the parameters mentioned above. The testing method is as follows: Test 1 - Examination of safety characteristics:

[0058] A fully charged lithium-ion battery is left to rest at 25 °C. The following charging strategy is applied: charging at 0.5 C with a constant current until a cutoff voltage of 4.25 V is reached, followed by charging at a constant voltage until the cutoff current is ≤0.05 C. During charging, the open-circuit voltage (OCV) is measured at regular intervals, and the voltage change and drop (the "K" value) are recorded. The K value is calculated as (OCVI - OCV²) / (11 - t²). A calculated K value of < 0.023 indicates normal operation; other values ​​indicate a short circuit. Test 2 - Investigation of energy density: a: Charging the battery with a constant current of 0.33 C up to a maximum voltage of 4.25 V, then charging with a constant voltage until the cut-off current is at most 0.05 C, after which discharging takes place. These steps are repeated three times, with the third discharge energy being recorded as the battery discharge energy “E”. b: The battery is weighed using an electronic scale to obtain its weight “M”. c: The gravimetric energy density is calculated as “E / M” in units of “Wh / kg”. Test 3 - Lifetime test at 25 °C:

[0059] The lithium-ion battery is left to rest for 120 minutes at 25 °C, then charged at a constant current of 0.5 C up to a cutoff voltage of 4.25 V, and subsequently charged at a constant voltage until the cutoff current is ≤0.05 C. After a 10-minute rest period, the battery is discharged at a constant current of 0.5 C down to 2.5 V. This completes one cycle. These steps are repeated until the battery reaches 80% state of health (SOH), at which point the number of cycles is recorded.

[0060] The values ​​for “A” based on these parameters 1 / 2 *C / B” and the corresponding results are listed in Table 2. Table 2 A(N / m) C Bmm A 1 / 2 *C / B Short-circuit test Energy density Cycle stability Example 1 104 12 1,5 0,816 Normal condition 322,594 1124 Example 2 136 20 2,5 0,933 Normal condition 333,147 1020 Example 3 7,5 4 1,6 0,068 Normal condition 297,698 1500 Example 4 5,5 4,7 2,3 0,048 Normal condition 301,267 1440 Example 5 5 4,5 3 0,034 Normal condition 291,659 1350 Example 6 150 20 1,6 1,531 Normal condition 330,860 986 Example 7 219 22 1,1 2,960 Normal condition 322,786 815 Example 8 0,4 18 3,5 0,033 Normal condition 319,159 912 Example 9 3 8 1,1 0,126 Normal condition 309,786 1140 Example 10 195 30 3 1,396 Normal condition 336,159 956 Example 11 245 32 2 2,504 Normal condition 339,067 694 Example 12 90 25 1 2,372 Normal condition 321,281 710 Example 13 90 25 1 2,372 Normal condition 329,860 786 Comparative example 1 0,3 1,5 4 0,002 Normal condition 245,580 986 Comparative example 2 218 30 1 4,429 Short circuit 341,410 /

[0061] The data in Tables 1 and 2 show that comprehensive control of the value of “A 1 / 2 *C / B”, such that this lies in the range of 0.03 to 3, a battery with high safety characteristics can be obtained, while simultaneously ensuring good electrochemical properties such as energy density and cycle stability. Further optimization of the value of “A 1 / 2 *C / B”, such that it lies in the range of 0.045 to 1.6, can provide a battery with even better overall energy density and cycle stability. Alternatively, if the silicon-based material includes a silicon-carbon material, further optimization of the value of “A” is possible. 1 / 2*C / B“, such that it lies in the range of 0.045 to 1, resulting in a battery with even better overall energy density and cycle stability.

[0062] It is understood that the above examples are merely for illustrative purposes and are not to be considered limiting examples. Those skilled in the art will readily recognize that further modifications or adaptations based on the above descriptions are possible. It is neither expedient nor possible to compile an exhaustive list of all possible embodiments. Obvious modifications or adaptations arising from these examples remain within the scope of protection of the present invention.

Claims

[1] Battery comprising a negative electrode, a positive electrode and a separator, wherein the negative electrode comprises a current collector and a negative active material layer arranged on the surface of the current collector, wherein the negative active material layer comprises a silicon-based material, characterized by , that the cohesive force of the negative electrode is denoted by “A” in units of “N / m”; in a direction parallel to the direction in which a tab is extended outwards, the separator is arranged such that it extends beyond the negative electrode near the side of the tab, the dimension of the separator extending beyond the negative electrode being denoted by “B” in units of “mm”; the mass fraction of elemental silicon in the negative active material layer being denoted by “C”; where “A”, “B” and “C” satisfy the following relationship: 0.03 ≤ A 1 / 2*C / B ≤ 3. [2] Battery according to claim 1, characterized by , that the value of “A 1 / 2 * C / B“ is in the range of 0.045 to 1.

4. [3] Battery according to claim 1 or 2, characterized by , that “A” is in the range of 0.3 to 220; and / or “B” is in the range of 1 to 4; and / or “C” is in the range of 1.5% to 30%. [4] Battery according to claim 3, characterized by , that “A” lies in the range of 5 to 150; and / or “B” is in the range of 1.5 to 3; and / or “C” is in the range of 4% to 20%. [5] Battery according to claim 1 or 2, characterized by , that the areal density of the negative active material layer is in the range of 60 to 300 g / m² 2 lies. [6] Battery according to claim 1 or 2, characterized by that the silicon-based material has a silicon-carbon material and / or a silicon-oxygen material. [7] Battery according to claim 6, characterized by, that if the silicon-based material has a silicon-carbon material, the value of “A 1 / 2 *C / B“ is in the range of 0.045 to 1. [8] Battery according to claim 6, characterized by , that the negative active material layer continues to contain one or more of artificial graphite, natural graphite and hard carbon. [9] Battery according to any of the preceding claims, characterized by , that the negative active material layer comprises a binder, wherein the binder is selected from styrene-butadiene rubber latex (SBR), polyvinylidene fluoride (PVDF), polyacrylic acid (PAA) and sodium carboxymethylcellulose (CMC). [10] Battery according to claim 9, characterized by that the binder is PAA, SBR and CMC. [11] Battery according to claim 10, characterized by , that the binder PAA:SBR:CMC has a mass ratio of (34.38 to 74.29) : (20 to 59.38) : (5 to 7.14). [12] Electrical device, characterized by that it has the battery according to one of the preceding claims.