Battery cell, battery device, power-consuming device and energy storage device

Abstract

Battery cell, characterized in that it comprises an electrode assembly and an electrolyte solution, wherein the electrode assembly comprises a cathode foil, an anode foil and a separator, wherein the separator is located between the cathode foil and the anode foil, wherein the cathode foil comprises a cathode collector and an active cathode substance layer provided on at least one side of the cathode collector, wherein the active cathode substance layer comprises an active cathode material, wherein the active cathode material comprises a lithium-containing phosphate with an olivine structure; wherein the anode foil comprises an anode collector and an active anode substance layer provided on at least one side of the anode collector, wherein the one-sided coating weight of the active anode substance layer is 80 mg / 1540.25 mm 2 up to 150 mg / 1540.25 mm 2 amounts; wherein the active anode substance layer comprises an active anode material, wherein the active anode material is a silicon-based material, wherein the mass fraction of the silicon element, based on the total mass of the active anode material layer, is 0.5% to 5%; where the viscosity of the electrolyte solution at room temperature is 2.3 mPa-s and 3.5 mPa-s.

Description

TECHNICAL AREA

[0001] The present application relates to the technical field of battery cells, in particular a battery cell, a battery device, a power-consuming device and an energy storage device. STATE OF THE ART

[0002] In recent years, battery cells have been widely used in energy storage systems such as hydroelectric, thermal, wind and solar power plants, as well as in a variety of fields such as power tools, electric bicycles, electric motorcycles, electric vehicles, military equipment, aerospace, etc.

[0003] With the market's demand for increased range and recharging efficiency of power-consuming devices doubling, the requirements for battery cell energy density have also risen. However, while energy density improves, cycle stability and fast-charging performance often deteriorate, creating a technical problem that urgently needs to be addressed in this field. CONTENT OF THE PRESENT INVENTION

[0004] The present application relates to the above subject matter and aims to provide a battery cell, a battery device, a power-consuming device, and an energy storage device. The battery cell incorporates improvements in energy density, fast-charging performance, and cycle stability to achieve a comprehensive performance improvement.

[0005] A first aspect of the present application provides a battery cell comprising an electrode assembly and an electrolyte solution, wherein the electrode assembly comprises a cathode foil, an anode foil, and a separator, the separator being located between the cathode foil and the anode foil, the cathode foil comprising a cathode collector and an active cathode substance layer provided on at least one side of the cathode collector, the active cathode substance layer comprising an active cathode material, the active cathode material comprising a lithium-containing phosphate with an olivine structure; wherein the anode foil comprises an anode collector and an active anode substance layer provided on at least one side of the anode collector, the one-sided coating weight of the active anode substance layer being 80 mg / 1540.25 mm² 2 up to 150 mg / 1540.25 mm 2is, wherein the active anode substance layer comprises an active anode material, wherein the active anode material is a silicon-based material, wherein the mass fraction of the silicon element, based on the total mass of the active anode material layer, is 0.5% to 5%, and wherein the viscosity of the electrolyte solution at room temperature is 2.3 mPa-s and 3.5 mPa-s.

[0006] The lithium-containing phosphate with an olivine structure has the advantage of being cost-effective and having a good lifetime. In combination with the silicon-containing cathode foil, which uses a silicon-based material with a high specific capacitance, the problem of low energy density in battery cells can be improved by using lithium-containing phosphates as the active cathode material. However, the silicon-based material undergoes a significant volume change during the cycle, which in turn leads to greater volume expansion of the anode foil and an increase in the expansion force of the electrical core. The increased pressure on the electrode foil causes the electrolyte solution to be extruded in the active cathode and anode material layers and is difficult to draw back in.The loss of electrolyte solution in the active substance layer leads to a "broken bridge" in the lithium-ion transfer path and triggers severe lithium precipitation in the anode, which then results in a cycle degradation of the battery cell, adversely affecting the fast-charging performance and the cycle life of the battery cell. In the battery cell of the embodiments of the present application, where the one-sided coating weight of the active anode substance layer is within the above range, while simultaneously taking energy density into account, it is possible to reduce the content of silicon-based material per unit area and shorten the lithium-ion diffusion path, which helps to reduce the volume expansion of the anode foil and the amount of extruded electrolyte solution.to reduce the internal resistance and improve the cycle stability and fast-charging performance of the battery cell; furthermore, by controlling the viscosity of the electrolyte solution in the above range, it combines good conductivity, stability, and dissociation rate, while simultaneously improving the infiltration capacity of the electrolyte solution onto the active substance layer, thereby improving the reabsorption of the extruded electrolyte solution and contributing to a further improvement in the cycle stability and fast-charging performance of the battery cell. The battery cell in the embodiment of the present application enables the battery cell to achieve excellent energy density, cycle life, and fast-charging performance through the interaction between the anode foil and the electrolyte solution.

[0007] In any embodiment, the one-sided coating weight of the active anode substance layer is 110 mg / 1540.25 mm². 2 up to 150 mg / 1540.25 mm 2 .

[0008] The one-sided coating weight of the active anode substance layer is within the above range, so the battery cell has excellent cycle life and fast charging performance, while further improving the energy density.

[0009] In any embodiment, the mass fraction of the silicon element, based on the total mass of the active anode substance layer, is 1.6% to 5%.

[0010] The mass fraction of the silicon element is within the above range, which gives the battery cell excellent cycle life and fast charging performance, while further improving energy density.

[0011] In any embodiment, the silicon-based material comprises one or more monomeric silicon, a silicon-carbon material, a silicon-oxygen material, a silicon-nitrogen material and a silicon alloy, optionally a silicon-carbon material.

[0012] The carbon material in the silicon-carbon material helps to mitigate the volume expansion of the silicon material, thereby balancing the energy density, fast charging performance, and cycle stability of the battery cell.

[0013] In any embodiment, the mass fraction of the silicon element in the silicon-carbon material, based on the total mass of the silicon-carbon material, is 40% to 80%.

[0014] In any embodiment, the volume-average particle size Dv50 of the silicon-carbon material is 5.0 µm to 12.5 µm.

[0015] The volume-average particle size of the silicon-carbon material is in the above range, which shortens the migration path of the lithium ions in the solid phase while also taking into account the lower reactivity, thus ensuring the fast charging capability and the cycle time of the battery cell.

[0016] In any embodiment, the silicon-carbon material has a specific surface area of ​​3.1 m². 2 / g up to 3.6 m 2 / g on.

[0017] The specific surface area of ​​the silicon-carbon material is in the above range, which shortens the migration path of the lithium ions in the solid phase while also taking into account the lower reactivity, thus ensuring the fast charging capability and the cycle time of the battery cell.

[0018] In any embodiment, the powder density of the silicon-carbon material at 25,000 N is 0.7 g / cm³. 3up to 1.2 g / cm³ 3 .

[0019] The silicon-carbon material with a powder density in the above range has no negative impact on the density of the anode foil and does not degrade the energy density of the battery cell.

[0020] In any embodiment, the active anode material comprises a carbon-based material.

[0021] In any embodiment, the carbon-based material comprises one or more of graphite and hard carbon, optionally graphite.

[0022] In any embodiment, the carbon-based material comprises composite graphite particles, wherein the composite graphite particles comprise graphite body particles and a carbon coating layer applied to at least a part of the surface of the composite graphite particles, wherein the composite graphite particles comprise secondary particles, and wherein the carbon coating layer comprises amorphous carbon.

[0023] Secondary particles refer to particles formed by the aggregation of more than two primary particles. The composite graphite particles containing secondary particles and the surface coating layer containing amorphous carbon contribute to further improving the infiltration performance of the electrolyte solution into the active anode substance layer and increasing the solid-phase transfer capacity of the active ions, thus further improving the fast-charging performance and cycle stability of the battery cell.

[0024] In any embodiment, the mass fraction of amorphous carbon, based on the total mass of the composite graphite particles, is 2% to 5%.

[0025] The amorphous carbon content is within a suitable range, so that the composite graphite material exhibits a high transfer capacity of active ions in the solid phase along with a high gram capacity, which contributes to a further improvement in the energy density and fast charging performance of the battery cell in a comprehensive way.

[0026] In any embodiment, the volume-average particle size Dv50 of the composite graphite particles is 8.5 µm to 16.5 µm.

[0027] The volume-average particle size of the composite graphite particles is in the above range, which shortens the migration path of the lithium ions in the solid phase and at the same time takes into account the lower reactivity, thus ensuring the fast charging capability as well as the cycle time of the battery cell.

[0028] In any embodiment, the density of the active anode substance layer is 1.10 g / cm³. 3 up to 1.50 g / cm²3 .

[0029] The density of the active anode substance layer is within the range above, so that the battery has excellent energy density while further improving the fast charging performance and cycle stability of the battery cells.

[0030] In any embodiment, the active anode substance layer has dimensions of 200 mm to 650 nm along the longitudinal direction of the electrode assembly.

[0031] The design of stacked electrode assemblies, where the dimension of the active anode substance layer along the longitudinal direction of the electrode assembly lies within the above range, is beneficial for considering the energy density, cycle stability and fast charging performance of the battery cell.

[0032] In any embodiment, the electrolyte solution comprises a first solvent, wherein the first solvent has a viscosity η of 0.3 mPa-s to 0.6 mPa-s at room temperature, wherein the mass fraction of the first solvent, based on the total mass of the electrolyte solution, is 8% to 60%.

[0033] The first solvent with a viscosity η in the above range has excellent stability and low viscosity, and the mass fraction of the first solvent is in the above range, which helps to reduce the viscosity of the electrolyte solution and increase the conductivity of the electrolyte solution while taking into account the stability of the electrolyte solution, thus contributing to a further comprehensive improvement in the fast charging performance and cycle stability of the battery cell.

[0034] In any embodiment, the mass fraction of the first solvent, based on the total mass of the electrolyte solution, is 30% to 60%.

[0035] If the mass fraction of the first solvent is in the above range, while the viscosity of the electrolyte solution is further reduced, the electrolyte solution exhibits good stability and conductivity, which allows for a further improvement in the cycle stability of the battery cell.

[0036] In any embodiment, the first solvent comprises a carboxylic acid ester solvent.

[0037] The carboxylic acid ester solvent has the advantages of low viscosity and high ionic conductivity, which promotes the infiltration of the electrolyte solution into the active cathode and anode substance layer and the rapid embedding and release of the active ions in the active anode substance layer, thus further improving the cycle stability and fast charging performance of the battery cell.

[0038] In any embodiment, the carboxylic acid ester solvent has a general structural formula of R'-COO-R", wherein R' comprises one or more of a hydrogen atom, a halogen atom, a C1 to C5 alkyl group and a C1 to C5 haloalkyl group, and wherein R" comprises one or more of a C1 to C5 alkyl group and a C1 to C5 alkyl halide group.

[0039] In any embodiment, the carboxylic acid ester solvent comprises one or more of methyl formate, methyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, propyl propionate, methyl butyrate, ethyl butyrate.

[0040] In any embodiment, the electrolyte solution further comprises a second solvent, wherein the second solvent comprises a carbonate solvent, the carbonate solvent comprising one or more of vinyl carbonate, propylene carbonate, butylene carbonate, dimethyl carbonate, diethyl carbonate and methylene carbonate.

[0041] The carbonate solvent has a high dielectric constant, and the carbonate solvent and lithium ions in the lithium-containing electrolyte salt can easily form a solvated structure to improve the dissociation rate of lithium ions and anions in the lithium-containing electrolyte salt, further improving the fast charging performance of the battery cell.

[0042] In any embodiment, the mass fraction of the carbonate solvent, based on the total mass of the electrolyte solution, is 18% to 75%.

[0043] Since the carbonate solvent has a high viscosity, the viscosity of the electrolyte solution increases with increasing carbonate solvent concentration, which negatively affects the electrolyte solution's conductivity. By carefully controlling the mass fraction of the carbonate solvent within the range described above, the electrolyte solution exhibits both appropriate viscosity and conductivity, as well as good dissociation rate and infiltration properties, contributing to a comprehensive improvement in the kinetic performance and cycle stability of the battery cell.

[0044] In any embodiment, the electrolyte solution comprises a lithium-containing electrolyte salt, wherein the mass fraction of the lithium-containing electrolyte salt in the electrolyte solution, based on the total mass of the electrolyte solution, is 10% to 18%.

[0045] If the molar concentration of the lithium-containing electrolyte salt in the electrolyte solution is in the above range, it is advantageous to consider the infiltration properties and the ionic conductivity of the electrolyte solution, which can comprehensively improve the cycle stability and fast charging performance of the battery cell.

[0046] In any embodiment, the lithium-containing electrolyte salt comprises one or more lithium bis(fluorosulfonyl)imide LiFSI and lithium hexafluorophosphate LiPF6.

[0047] LiFSI dissociates readily in the solvent of the electrolyte solution, and its molecular weight is lower than that of other types of fluorosulfonimide salts (e.g., lithium bis(trifluoromethanesulfonate)imide, LiTFSI). This contributes to improved electrolyte conductivity while simultaneously reducing the viscosity of the electrolyte solution. Furthermore, LiFSI exhibits good thermal stability and does not tend to decompose during cycling. This can reduce hydrogen fluoride generation during battery cycles and the likelihood of side reactions at the anode, further enhancing cycle stability and fast-charging performance of the battery cell.However, as the battery cell temperature increases, LiFSI decomposes rapidly above a certain temperature threshold, releasing a large amount of heat. This significantly increases the risk of thermal runaway, posing a greater safety risk for fast-charging batteries. The lithium-containing electrolyte salt can also include lithium hexafluorophosphate (LiPF6), which can reduce the risk of thermal runaway, keeping it within a manageable range and thus improving the battery cell's safety performance.

[0048] In any embodiment, the mass fraction of lithium bis(fluorosulfonyl)imide LiFSI, based on the total mass of the electrolyte solution, is 4% to 8%.

[0049] The battery cell with the molar concentration of lithium bis(fluorosulfonyl)imide in the electrolyte solution within the above range can take into account the kinetic performance, cycle stability and safety performance of the battery cell.

[0050] In any embodiment, the electrolyte solution further comprises an additive, wherein the additive comprises one or more of a carbonate additive, a sulfur-containing additive, a lithium salt-like additive and a fluorobenzene additive.

[0051] In any embodiment, the carbonate additive comprises one or more vinylidene carbonate and a vinyl carbonate derivative, wherein the vinyl carbonate derivative comprises a compound represented in Formula I,

[0052] wherein R1, R2, R3, R4 each independently comprise a hydrogen atom, a halogen atom, a C1 to C5 alkyl group and a C1 to C5 haloalkyl group, and wherein R1, R2, R3, R4 are not simultaneously hydrogen atoms, wherein the carbonate additive may optionally comprise one or more of vinylidene carbonate and fluorinated vinyl carbonate.

[0053] The carbonate additive can evolve into organic components within the SEI film, which contributes to improving the toughness of the SEI film, reducing SEI film breakage due to volume changes of the silicon-based material, preventing side reactions between the electrolyte solution and the silicon-based material, reducing battery gas generation, and lowering the anode-side interfacial impedance, further improving the cycle and storage life as well as the fast-charging performance of the battery cell.

[0054] In any embodiment, the sulfur-containing additive comprises one or more of vinyl sulfate, vinyl bisulfate, 1,3-propanesulfonate lactone, butyl sulfite, vinyl sulfite and methylenedisulfonylmethylene.

[0055] The sulfur-containing additive tends to have a high potential, and the sulfur-containing additive added to the electrolyte solution reacts preferentially during formation or the subsequent cycling process, developing into sulfur-containing inorganic components in the SEI film. The SEI film formed by the carbonate additive exhibits poor stability at high temperatures, which is detrimental to the stability of the battery cell in a high-temperature environment. The SEI film contains sulfur element, which can further improve the thermal stability of the SEI film at high temperatures and further reduce the interfacial impedance on the anode side, leading to further improvements in the cycle stability and fast-charging performance of the battery cell.

[0056] In any embodiment, the lithium salt-like additive comprises one or more of lithium difluorophosphate, lithium difluorooxalate borate, lithium tetrafluoroborate, lithium bisoxalate borate.

[0057] The lithium salt-like additive can develop into inorganic components within the SEI film, further improving its stiffness and stability, thereby enhancing the battery's cycle stability and fast-charging performance. Furthermore, this lithium salt-like additive can also form an interfacial electrolyte (CEI) film on the surface of the active cathode material, further improving the battery cell's cycle stability.

[0058] In any embodiment, the fluorobenzene additive comprises one or more fluorobenzenes and their derivatives.

[0059] The fluorobenzene additive can contribute to improving the infiltration properties of the electrolyte solution into the active cathode and anode substance layer, thereby further improving the cycle stability and fast charging performance of the battery cell.

[0060] In any embodiment, the mass fraction of the carbonate additive, based on the total mass of the electrolyte solution, is 3% to 8%.

[0061] The mass fraction of the carbonate additive in the electrolyte solution is within the above range, which both increases the stability of the SEI film and keeps the viscosity of the electrolyte solution at a suitable level to further improve the cycle life of the battery cell and the fast charging performance in a comprehensive way.

[0062] In any embodiment, the mass fraction of vinylidene carbonate, based on the total mass of the electrolyte solution, is 2% to 5%.

[0063] Vinylidene carbonate (VC) has a reduction potential similar to that of carboxylic acid ester solvents, thus inhibiting the reactivity of these solvents and improving the cycle life of the battery cell. However, an excessively high VC content leads to an increase in interfacial impedance and charge transfer impedance, negatively impacting the fast-charging performance of the battery cell. The mass fraction of vinylidene carbonate (VC) is within the range mentioned above, ensuring excellent cycle life and fast-charging performance for the battery.

[0064] In any embodiment, the mass fraction of the vinyl carbonate derivative, based on the total mass of the electrolyte solution, is 0% to 4%.

[0065] In any embodiment, the mass fraction of the vinyl carbonate derivative, based on the total mass of the electrolyte solution, is 1.5% to 3.5%.

[0066] The vinyl carbonate derivative can also form a film on the anode surface at high potential and has low interfacial and charge transfer impedance. Its mass fraction is within the range mentioned above, enabling the battery cell to achieve excellent fast-charging performance and cycle life. Adding vinylidene carbonate (VC) and vinyl carbonate derivatives to the electrolyte solution can significantly improve the fast-charging performance and cycle stability of the battery cell.

[0067] In any embodiment, the mass fraction of the sulfur-containing additive, based on the total mass of the electrolyte solution, is 0% to 2%.

[0068] In any embodiment, the mass fraction of the sulfur-containing additive, based on the total mass of the electrolyte solution, is 0.5% to 2%.

[0069] The mass fraction of the sulfur-containing additive in the electrolyte solution is within the above range, which both increases the thermal stability of the SEI film at high temperatures and keeps the viscosity of the electrolyte solution at a suitable level to further improve the cycle life of the battery cell and the fast charging performance in a comprehensive way.

[0070] In any embodiment, the mass fraction of the lithium salt-like additive, based on the total mass of the electrolyte solution, is 0% to 1%.

[0071] In any embodiment, the mass fraction of the lithium salt-like additive, based on the total mass of the electrolyte solution, is 0.2% to 1%.

[0072] The mass fraction of the lithium salt-like additive in the electrolyte solution is within the above range, which both increases the stability of the SEI film and keeps the viscosity of the electrolyte solution at a suitable level to further improve the cycle life of the battery cell and the fast charging performance in a comprehensive way.

[0073] In any embodiment, the mass content of the fluorobenzene additive, based on the total mass of the electrolyte solution, is 0.1% to 1%.

[0074] The mass fraction of the fluorobenzene additive in the electrolyte solution is within the above range, which takes into account both the infiltration properties of the electrolyte solution and keeps the viscosity of the electrolyte solution at a suitable level to further improve the cycle life of the battery cell and the fast charging performance in a comprehensive way.

[0075] In any embodiment, along the longitudinal direction of the electrode assembly, the dimension of the active anode substance layer is larger than the dimension of the active cathode substance layer, wherein the difference between the dimension of the active anode substance layer and the dimension of the active cathode substance layer is OH1; and along the transverse direction of the electrode assembly, the dimension of the active anode substance layer is larger than the dimension of the active cathode substance layer, wherein the difference between the dimension of the active anode substance layer and the dimension of the active cathode substance layer is OH2, where OH1 is 1.0 mm to 4.0 mm; and / or where OH2 is 1.0 mm to 3.0 mm.

[0076] As the charging rate of the battery cell increases, the area near the electrode tab experiences high current density and a steep temperature rise, making the active anode layer susceptible to lithium dendrite formation near the electrode tab. The design of OH1 and OH2 improves the ability of the active anode layer, particularly the active anode layer near the electrode tab, to attract active ions in the longitudinal direction. It also positions the active cathode layer further away from the electrode tab and results in a more uniform current distribution in the active layer near the electrode tab, leading to a reduction in the temperature rise and thus significantly improving lithium precipitation in the anode foil.At the same time, the probability of cathode and anode overlap due to thermal contraction of the separator and internal short circuit of the battery is reduced, improving the fast charging performance and cycle stability of the battery cell, while controlling the values ​​of OH1 and OH2 in the above ranges, so that the battery cell can have excellent energy density.

[0077] In any embodiment, OH1 is greater than or equal to OH2.

[0078] By controlling that OH1 is larger than OH2, the cycle stability of the battery cell can be improved and at the same time a further improvement in the energy density of the battery cell can be enabled.

[0079] In any embodiment, the cathode collector comprises a cathode collector section and a cathode tab, wherein the cathode tab is provided at at least one end in the extension direction of the cathode collector section along the longitudinal direction of the electrode assembly or at at least one side in the extension direction along the width direction of the electrode assembly; and / or that the anode collector comprises an anode collector section and an anode tab, wherein the anode tab is provided at at least one end in the extension direction of the anode collector section along the longitudinal direction of the electrode assembly or at at least one side in the extension direction along the width direction of the electrode assembly.

[0080] In any embodiment, the active anode substance layer has a dimension of more than 500 mm along the longitudinal direction of the electrode assembly, wherein the anode tab is provided at both ends in the extension direction of the anode collector section along the longitudinal direction of the electrode assembly or at least on one side in the extension direction along the width direction of the electrode assembly.

[0081] The above electrode tab contributes to improving the overcurrent capability of the battery cell, alleviating the situation of lithium precipitation on the electrode tab side caused by the decomposition of the electrolyte solution and the uneven current distribution on the electrode tab side due to the high temperature during fast charging, and thus improving the fast charging performance and the cycle stability of the battery cell, which is particularly suitable for improving the fast charging performance of batteries with an active substance layer with a length dimension of more than 500 mm, taking into account the excellent volumetric energy density.

[0082] In any embodiment, the cathode tab is provided at at least one end in the extension direction of the cathode collector section along the longitudinal direction of the electrode assembly, wherein the ratio of the width of the cathode tab to the width of the cathode collector section is 0.25 to 1; and / or wherein the ratio of the width of the anode tab to the width of the anode collector section is 0.25 to 1.

[0083] In any embodiment, the cathode tab is provided on at least one side in the extension direction of the cathode collector section along the width direction of the electrode assembly, wherein the ratio of the width of the cathode tab to the length of the cathode collector section is 0.25 to 1; and / or wherein the ratio of the width of the anode tab to the length of the anode collector section is 0.25 to 1.

[0084] The width of the electrode tab lies within the above range, thereby increasing the overcurrent capability of the battery cell and improving the fast charging performance as well as the cycle stability of the battery cell.

[0085] In any embodiment, the active cathode material comprises: a lithium-containing phosphate with an olivine structure, and a coating layer, wherein the coating layer is located on at least a part of the surface of the lithium-containing phosphate, and the coating layer comprises a carbon element.

[0086] The coating layer contains carbon elements, which increases the electronic conductivity of the lithium-containing phosphate and improves the transfer rate of electrons in the solid phase, thereby further improving the energy density and fast charging performance of the battery cell.

[0087] In any embodiment, the mass fraction of the carbon element, based on the total mass of the active cathode material, is 0.8% to 2.3%.

[0088] With respect to the total mass of the active cathode material, the mass fraction of the carbon element lies within the above range, which means that the lithium-containing phosphate exhibits both excellent electronic conductivity and a high gram capacity, further comprehensively improving the energy density and fast charging performance of the battery cell.

[0089] In any embodiment, the coating layer further comprises a component as shown in Formula II,

[0090] Li 3-d1 Fe 2-d1 ml d1 (PO m1 ) n1 , Formula II, where 0≤d1≤1, 3≤m1≤5, 2≤n1≤4, where M1 comprises one or more of the elements Ti, Zr, Hf, Ge, Sn, where M1 optionally has the valency +4.

[0091] The component shown in Formula II is a fast-ion conductor with a NASICON structure. Its ionic conductivity is close to or greater than that of conductive liquids such as electrolyte solutions or molten salts. It features numerous three-dimensional lithium-ion diffusion and transfer channels and offers the advantages of high ionic conductivity and strong structural stability during multiple lithium de- / embedding cycles. The coating layer on the surface of the lithium-containing phosphate incorporates a fast-ion conductor with a NASICON structure. This significantly increases the lithium-ion transfer rate at the cathode end during multiple lithium de- / embedding cycles and improves the ionic conductivity of the active cathode material, further enhancing the energy density and fast-charging performance of the battery cell.

[0092] In any embodiment, the lithium-containing phosphate comprises a component represented in Formula III,

[0093] Li x1 A y1 Me a1 M b1 P 1-c1 X c1 Y z1 Formula III, where 0.5 ≤ x1 ≤ 1.3, 0 ≤ y1 ≤ 1.3, 0.9 ≤ x1 + yl1 ≤ 1.3, 0.9 ≤ a1 ≤ 1.5, 0 ≤ b1 ≤ 0.5, 0.9 ≤ a1 + b1 ≤ 1.5, 0 ≤ c1 ≤ 0.5, 3 ≤ z1 ≤ 5, where A comprises one or more of the elements Na, K and Mg; where Me comprises one or more of the elements Mn, Fe, Co and Ni; where M comprises one or more of the elements B, Mg, Al, Si, P, S, Ca, Sc, Ti, V, Cr, Cu, Zn, Sr, Y, Zr, Nb, Mo, Cd, Sn, Sb, Te, Ba, Ta, W, Yb, La and Ce; where X comprises one or more of the elements S, Si, Cl, B, C, N and P, and where Y comprises one or more of the elements O and F.

[0094] The lithium-containing phosphate with olivine structure, which the above component has, has good structural stability, which can reduce the loss during the fast charging process and further improve the fast charging performance and cycle stability of the battery cell.

[0095] In any embodiment, the active cathode material comprises one or more of lithium iron phosphate, lithium manganese phosphate, lithium ferromanganese phosphate, lithium nickel phosphate and lithium cobalt phosphate, as well as a modified form of one of the above substances, wherein the modified form comprises one or more of a doped modified form and a coated modified form.

[0096] In any embodiment, the powder density of the active cathode material at 30,000 N is 2.45 g / cm³. 3 up to 2.75 g / cm³ 3 .

[0097] An active cathode material with a powder density in the appropriate range leads to a high density of the active cathode substance layer, which in turn leads to a high energy density of the battery cell.

[0098] In any embodiment, the density of the active cathode substance layer is 2.5 g / cm³. 3 up to 2.83g / cm³ 3 .

[0099] The density of the active cathode substance layer lies within the above range, thus achieving a balance between the energy density, fast charging performance and the cycle stability of the battery cell.

[0100] In any embodiment, the one-sided coating weight of the active cathode substance layer is 200 mg / 1540.25 mm². 2 up to 370 mg / 1540.25 mm 2 .

[0101] An active cathode substance layer with a one-sided coating weight of the active cathode substance layer within the above range can better balance the fast charging performance and the energy density of the battery cell.

[0102] In any embodiment, the thickness of the cathode collector is 10 µm to 15 µm.

[0103] The reduced thickness of the cathode collector allows for a further improvement in the energy density of the battery cell.

[0104] In any embodiment, the anode foil further comprises a conductive anode layer, wherein the conductive anode layer is located between the anode collector and the active anode substance layer on at least one side, wherein the thickness of the conductive anode layer is 0.5 µm to 2 µm; and / or the cathode foil further comprises a conductive cathode layer, wherein the conductive cathode layer is located between the active cathode substance layer and the cathode collector, wherein the thickness of the conductive cathode layer is 0.5 µm to 2 µm.

[0105] The conductive cathode layer and / or the conductive anode layer contribute to increasing the electronic conductivity of the electrode foil of the battery cell, leading to a further improvement in the fast charging performance of the battery cell.

[0106] In any embodiment, the conductive anode layer comprises a conductive agent, while the conductive cathode layer comprises a conductive agent and a cathode binder; wherein the conductive agent comprises one or more of superconducting carbon, conductive graphite, acetylene black, carbon black, cotinine black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers; wherein the cathode binder comprises one or more of polyvinylidene fluoride, polytetrafluoroethylene, vinylidene fluoride-tetrafluoroethylene-propylene terpolymer, vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer, polyacrylic acid, and fluorine-containing acrylate resin.

[0107] In any embodiment, the porosity of the separator is 20% to 70%.

[0108] In any embodiment, the porosity of the separator is 35% to 60%.

[0109] The porosity of the separator in the above area helps to further balance the energy density, fast charging performance and cycle stability of the battery cell.

[0110] In any embodiment, the separator comprises: a base film; a first functional layer located on at least one side of the base film, wherein the first functional layer comprises a first inorganic substance; a second functional layer located on a side of the first functional layer facing away from the base film, wherein the second functional layer comprises a second inorganic substance and non-fluorinated polymer.

[0111] In any embodiment, the non-fluorinated polymer particles comprise an acrylate copolymer.

[0112] In any embodiment, the first inorganic substance and the second inorganic substance each independently comprise one or more of silicon oxide, aluminum oxide, boehmite, barium sulfate, calcium oxide, titanium oxide, zinc oxide, magnesium oxide, zirconium oxide and tin oxide.

[0113] The inorganic particles can improve the infiltration performance of the first and second functional layers into the electrolyte solution and their heat resistance, thereby further enhancing the fast-charging performance, cycle stability, and safety of the battery cell. The non-fluorinated polymer particles can improve the processing performance and stability of the separator, prevent separator movement within the battery cell that could lead to an internal short circuit, and thus further improve the cycle stability and safety of the battery cell.

[0114] In any embodiment, the thickness of the base film is 4 µm to 12 µm, optionally 5 µm to 9 µm.

[0115] The thickness of the base film in the area above helps to further balance the energy density, fast charging performance and cycle stability of the battery cell.

[0116] In any embodiment, the battery cell comprises a housing body and a cover assembly, wherein the cover assembly is provided at at least one end of the housing body, wherein the housing body and the cover assembly define a receiving cavity, wherein the electrode assembly is provided within the receiving cavity, and wherein the thickness of the housing body over a large area of ​​the battery cell is 0.1 mm to 0.5 mm.

[0117] In any embodiment, the thickness of the housing body of a large area of ​​the battery cell is 0.2 mm to 0.35 mm.

[0118] The thickness of the casing of a large area of ​​the battery cell lies within the above range, which is favorable for a further improvement in the energy density of the battery cell.

[0119] In any embodiment, the cover assembly comprises a first cover assembly and a second cover assembly, wherein the first cover assembly and the second cover assembly are provided at both ends of the housing body in the longitudinal direction or in the width direction, wherein the first cover assembly comprises a first cover plate and a first electrode clamp, while the second cover assembly comprises a second cover plate and a second electrode clamp, wherein the first electrode clamp and the second electrode clamp have opposite polarity.

[0120] As a result, the temperature rise of the battery cell during the charging process is reduced and the impedance of the battery cell is decreased, which contributes to an improvement in the fast charging performance, cycle life and safety performance of the battery cell.

[0121] In any embodiment, the minimum cross-sectional area of ​​the first electrode clamp and / or the second electrode clamp S is 150 mm². 2 ≤S≤1000 mm 2 .

[0122] The minimum cross-sectional area of ​​the first electrode clamp and / or the second electrode clamp is in the above range, which contributes to improving the overcurrent capability of the battery cell, reducing the heat generation of the electrode clamp, reducing the internal resistance of the battery cell and thus improving the fast charging performance of the battery cell as well as the cycle stability.

[0123] In any embodiment, the volumetric energy density of the battery cell is more than 440 Wh / L and less than or equal to 530 Wh / L.

[0124] In any embodiment, the volumetric energy density of the battery cell is 450 Wh / L to 510 Wh / L.

[0125] The battery cell also has a high energy density to meet the demand for greater range from power-consuming devices.

[0126] In any embodiment, the injection coefficient of the battery cell is 2.2 g / Ah to 3.0 g / Ah.

[0127] The injection coefficient within the above range can compensate for the cycle stability and energy density of the battery cells.

[0128] A second aspect of the present application provides a battery device comprising a battery cell according to the first aspect of the present application, wherein the battery device comprises at least one of a battery module, a battery pack and an energy storage battery.

[0129] A third aspect of the present application further provides a power-consuming device, wherein the power-consuming device comprises a battery cell according to the first aspect of the present application.

[0130] A fourth aspect of the present application provides an energy storage device, wherein the energy storage device comprises a battery cell according to the first aspect of the present application. BRIEF DESCRIPTION OF THE DRAWING Fig.Figure 1 is a schematic representation of a cathode foil and an anode foil in an embodiment of the present application; Fig. Figure 2 is a schematic representation of a cathode foil and an anode foil in an embodiment of the present application; Fig. Figure 3 is a schematic representation of the cathode collector in an embodiment of the present application; Fig. Figure 4 is a schematic representation of the cathode collector in an embodiment of the present application; Fig. Figure 5 is a schematic representation of the cathode collector in an embodiment of the present application; Fig. Figure 6 is a schematic representation of the cathode collector in an embodiment of the present application; Fig. Figure 7 is a schematic representation of the anode collector in an embodiment of the present application; Fig.Figure 8 is a schematic representation of the anode collector in an embodiment of the present application; Fig. Figure 9 is a schematic representation of the anode collector in an embodiment of the present application; Fig. Figure 10 is a schematic representation of the anode collector in an embodiment of the present application; Fig. Figure 11 is a schematic representation of the structure of a separator in an embodiment of the present application; Fig. Figure 12 is a schematic representation of the structure of a battery cell in an embodiment of the present application; Fig. Figure 13 shows a schematic representation of a power-consuming device which uses a battery cell as a power source, in an embodiment of the present application. Reference symbol list:

[0131] 1 Battery cell; 11 Housing body; 111 Housing body of a large area of ​​the battery cell; 12 Electrode assembly; 121 Cathode foil; 1211 Cathode collector; 1212 Active cathode substance layer; 12110 Cathode collector section; 12111 Cathode tab; 122 Anode foil; 1221 Anode collector; 1222 Active anode substance layer; 12210 Anode collector section; 12211 Anode tab; 123 Separator; 1231 Base film; 1232 First functional layer; 1233 Second functional layer; First electrode terminal 131, second electrode terminal 132, third electrode terminal 133, fourth electrode terminal 134. DETAILED DESCRIPTION

[0132] The following sections disclose in detail embodiments of the battery cell, battery device, power-consuming device, and energy storage device of the present application with corresponding reference to the accompanying drawings. However, there will be instances where an unnecessarily detailed description is omitted. For example, detailed descriptions of things that are already well known and repeated descriptions of the same structure will be left out. This is to avoid making the following description unnecessarily long and to facilitate understanding by those skilled in the art. Furthermore, the accompanying drawings and the following description serve to enable a person skilled in the art to fully understand the present application and are not intended to limit the subject matter specified in the claims.

[0133] The "range" disclosed here is defined in terms of a lower bound and an upper bound, with a particular range being defined by selecting a lower bound and an upper bound that establish the limits of that range. Ranges defined in this way can include or exclude end values ​​and can be combined in any way; that is, any lower bound can be combined with any upper bound to form a range. For example, if a range of 60-120 and 80-110 is specified for a particular parameter, a range of 60-110 and 80-120 is also to be expected. Furthermore, if the minimum values ​​1 and 2 and the maximum values ​​3, 4, and 5 are specified, the following ranges can be expected: 1-3, 1-4, 1-5, 2-3, 2-4, and 2-5.Unless otherwise specified, the range "ab" denotes any combination of real numbers between a and b, where both a and b are real numbers. For example, the range "0-5" means that all real numbers between 0 and 5 are listed here, and 0-5 is simply a shorthand representation of the combination of these values. Furthermore, stating that a parameter is an integer ≥ 2 is equivalent to stating that the parameter is, for example, an integer 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, and so on.

[0134] Unless expressly stated otherwise, all embodiments and optional embodiments of the present application may be combined to form new technical solutions.

[0135] Unless expressly stated otherwise, all technical features of the present application, as well as optional technical features, may be combined to form a new technical solution.

[0136] Unless expressly stated otherwise, all steps of the present application may be carried out sequentially or randomly, preferably sequentially. For example, the method includes steps (a) and (b), which means that the method may include steps (a) and (b) carried out one after the other, or that it may include steps (b) and (a) carried out one after the other. The indication that the method may also include step (c) means, for example, that step (c) may be added to the method in any order; e.g., 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).

[0137] Unless otherwise stated, references to "including" and "comprehensive" in this application denote an open or closed formulation. For example, the terms "including" and "comprehensive" may mean that other, unlisted components may also be included or contained, or that only the listed components may be included or contained.

[0138] Unless otherwise stated, the term "or" in this application is comprehensive. For example, the phrase "A or B" means "A, B, or both A and B." More precisely, the condition "A or B" is satisfied by any one of the following: A is true (or exists) and B is false (or does not exist); A is false (or does not exist) and B is true (or exists); or both A and B are true (or exist).

[0139] The silicon-based material has a high theoretical specific capacity and can contribute to improving the energy density of battery cells as an active anode material. However, the silicon-based material undergoes significant volume changes during the cycle, leading to greater volume expansion of the silicon-containing anode foil, an increase in the expansion force of the electrical core, and an increase in the compression pressure on the cathode and anode foils. This causes the electrolyte solution to be extruded in the active material layer and is difficult to reabsorb, resulting in the problem of cycle degradation of the battery cell.

[0140] Based on this, a first aspect of the present application provides a battery cell comprising an electrode assembly and an electrolyte solution, wherein the electrode assembly comprises a cathode foil, an anode foil and a separator, the separator being located between the cathode foil and the anode foil, the cathode foil comprising a cathode collector and an active cathode substance layer provided on at least one side of the cathode collector, the active cathode substance layer comprising an active cathode material, the active cathode material comprising a lithium-containing phosphate with an olivine structure; wherein the anode foil comprises an anode collector and an active anode substance layer provided on at least one side of the anode collector, the one-sided coating weight of the active anode substance layer being 80 mg / 1540.25 mm² 2 up to 150 mg / 1540.25 mm 2is, wherein the active anode substance layer comprises an active anode material, wherein the active anode material is a silicon-based material, wherein the mass fraction of the silicon element, based on the total mass of the active anode material layer, is 0.5% to 5%, and wherein the viscosity of the electrolyte solution at room temperature is 2.3 mPa-s and 3.5 mPa-s.

[0141] The lithium-containing phosphate with an olivine structure is an active material with an olivine structure containing lithium ions and phosphate, and the nature of the active cathode material can be tested using any method known in engineering. For example, a physical phase analysis method such as X-ray diffraction (XRD) can be used in combination with an elemental analysis method such as energy spectroscopy and XPS.

[0142] In the present application, the “one-sided coating weight of the active anode substance layer” refers to the weight of the active anode substance layer per unit area on one side of the collector.

[0143] In the present application, the one-sided coating weight of the active anode substance layer can be tested using methods known in the art. For example, an anode foil (in the case of a double-sided coated anode foil, the active anode substance layer can be wiped off one side first) is taken from a disassembled battery, punched out, and cut into a small round disc with an area of ​​S1, weighed, and recorded as M1. Then, the active anode substance layer of the anode foil, which has been weighed as described above, is wiped off, and the weight of the anode collector is weighed and recorded as M0. One-sided coating weight of the anode foil = (M1-M0) / S1.

[0144] In some embodiments, the one-sided coating weight of the active anode substance layer can be 80 mg / 1540.25 mm². 2 , 90 mg / 1540.25 mm 2 , 100 mg / 1540.25 mm 2 , 110 mg / 1540.25 mm 2 , 120 mg / 1540.25 mm 2 , 130 mg / 1540.25 mm 2 , 140 mg / 1540.25 mm 2 , 150 mg / 1540.25 mm 2 or any value within a range between two of these values.

[0145] The qualitative characterization and quantitative characterization of each substance or element in the present application can be tested using suitable equipment and methods known to those skilled in the art. The relevant test procedure may refer to domestic and foreign testing standards, domestic and foreign company standards, etc., and those skilled in the art may also adaptively modify certain test steps / instrument parameters, etc., with regard to accuracy, in order to obtain a more accurate test result. A test procedure may be used qualitatively or quantitatively, and several test procedures may be used together for a qualitative or quantitative determination. In the present application, with respect to the total mass of the active anode substance layer, the mass fraction of the silicon element can be tested using methods known in the art.For example, the anode foil is soaked in a solvent such as water, the active anode material is separated from the anode collector, and the substances in the active anode material layer are extracted by pumping and filtering. These substances are then taken as test samples. The silicon content can be determined by placing the test samples in an inductively coupled plasma emission spectrometer, model ICAP7400, manufactured by Thermo Fisher Scientific Company in the USA, in accordance with standard GB / T30902-2014.

[0146] In some embodiments, the mass fraction of the silicon element can be 0.5%, 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, 5% or any value in a range between two of these values, based on the total mass of the active anode substance layer.

[0147] In the present application, “room temperature” means 25±3°C.

[0148] The viscosity of the electrolyte solution at room temperature has a well-established significance in engineering and can be tested using a known method. For example, the rotational method according to the national standard GB / T 10247-2008 "Method for measuring viscosity" can be used. Specifically, a certain mass of the electrolyte solution is taken, placed in a sample container, and immersed in a water bath at constant temperature for 10 to 20 minutes. Once the temperature of the sample matches the temperature of the water bath, the test is performed using a Brookfield rotational viscometer, model DV2TLV. The torque is generated in the spring by the shear force exerted on the sample by a rotor (number 18), which rotates continuously within the sample at a constant speed of 70 rpm. The torque is proportional to the viscosity to obtain the viscosity value.Five samples were tested, and the viscosity was taken as the average value of the five samples. The test device meets the following conditions for the test environment: 1. External environment of the device: the temperature is between 15°C and 28°C, and the relative humidity is <80%; 2. Internal environment of the device: two-thirds of the sample container is immersed in a water bath, and the medium is water, which is used to thermostat the samples; the hydrothermal temperature is 25 ± 3°C.

[0149] In some embodiments, the viscosity of the electrolyte solution at room temperature can be 2.3 mPa-s, 2.4 mPa-s, 2.5 mPa-s, 2.6 mPa-s, 2.7 mPa-s, 2.8 mPa-s, 2.9 mPa-s, 3.0 mPa-s, 3.1 mPa-s, 3.2 mPa-s, 3.3 mPa-s, 3.4 mPa-s, 3.5 mPa-s or any value in a range between two of these values.

[0150] The lithium-containing phosphate with an olivine structure has the advantage of being cost-effective and having a good lifetime. In combination with the silicon-containing cathode foil, which uses a silicon-based material with a high specific capacitance, the problem of low energy density in battery cells can be improved by using lithium-containing phosphates as the active cathode material. However, the silicon-based material undergoes a significant volume change during the cycle, which in turn leads to greater volume expansion of the anode foil and an increase in the expansion force of the electrical core. The increased pressure on the electrode foil causes the electrolyte solution to be extruded in the active cathode and anode material layers and is difficult to draw back in.The loss of electrolyte solution in the active substance layer leads to a "broken bridge" in the lithium-ion transfer path and triggers severe lithium precipitation in the anode, which then results in a cycle degradation of the battery cell, adversely affecting the fast-charging performance and the cycle life of the battery cell. In the battery cell of the embodiments of the present application, where the one-sided coating weight of the active anode substance layer is within the above range, while simultaneously taking energy density into account, it is possible to reduce the content of silicon-based material per unit area and shorten the lithium-ion diffusion path, which helps to reduce the volume expansion of the anode foil and the amount of extruded electrolyte solution.to reduce the internal resistance and improve the cycle stability and fast-charging performance of the battery cell; furthermore, by controlling the viscosity of the electrolyte solution in the above range, it combines good conductivity, stability, and dissociation rate, while simultaneously improving the infiltration capacity of the electrolyte solution onto the active substance layer, thereby improving the reabsorption of the extruded electrolyte solution and contributing to a further improvement in the cycle stability and fast-charging performance of the battery cell. The battery cell in the embodiment of the present application enables the battery cell to achieve excellent energy density, cycle life, and fast-charging performance through the interaction between the anode foil and the electrolyte solution.

[0151] In some embodiments, the one-sided coating weight of the active anode substance layer is 110 mg / 1540.25 mm². 2 up to 150 mg / 1540.25 mm 2 .

[0152] The one-sided coating weight of the active anode substance layer is within the above range, so the battery cell has excellent cycle life and fast charging performance, while further improving the energy density.

[0153] In some embodiments, the mass fraction of the silicon element, based on the total mass of the active anode substance layer, is 1.6% to 5%.

[0154] The mass fraction of the silicon element is within the above range, which gives the battery cell excellent cycle life and fast charging performance, while further improving energy density.

[0155] In some embodiments, the silicon-based material comprises one or more of monomeric silicon, a silicon-carbon material, a silicon-oxygen material, a silicon-nitrogen material and a silicon alloy, optionally a silicon-carbon material.

[0156] The carbon material in the silicon-carbon material helps to mitigate the volume expansion of the silicon material, thereby balancing the energy density, fast charging performance, and cycle stability of the battery cell.

[0157] In some embodiments, the mass fraction of the carbon element in the silicon-carbon material, relative to the total mass of the silicon-carbon material, is 40% to 80%.

[0158] In some embodiments, the mass fraction of the silicon element in the silicon-carbon material can be 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, or any value in a range between two of these values.

[0159] In some embodiments, the volume-average particle size Dv50 of the silicon-carbon material is 5.0 µm to 12.5 µm.

[0160] In the present application, “the volume-averaged particle size Dv50” has a meaning known in the art and corresponds to the particle size corresponding to a cumulative percentage volume distribution fraction of the material of 50%, which can be determined using instruments and methods known in the art. For example, a laser particle size analyzer has been used for convenient determination with reference to GB / T 19077-2016 Laser Diffraction Method of Particle Size Distribution. The testing instrument may be a Mastersizer 3000 laser particle size analyzer from Malvern Instruments Ltd, UK.

[0161] In some embodiments, the volume mean particle size Dv50 of the silicon-carbon material can be 5.0 µm, 5.6 µm, 6.0 µm, 6.5 µm, 7.0 µm, 7.5 µm, 8.0 µm, 8.5 µm, 9.0 µm, 9.5 µm, 10.0 µm, 10.5 µm, 11.0 µm, 11.5 µm, 12.0 µm, 12.5 µm or any value in a range between two of these values.

[0162] The volume-average particle size of the silicon-carbon material is in the above range, which shortens the migration path of the lithium ions in the solid phase while also taking into account the lower reactivity, thus ensuring the fast charging capability and the cycle time of the battery cell.

[0163] In some embodiments, the silicon-carbon material has a specific surface area of ​​3.1 m². 2 / g up to 3.6 m 2 / g on.

[0164] In the present application, the specific surface area has a meaning known in the art and can be tested by a method known in the art. The determination method can refer to GB / T19587-2017, is tested using the nitrogen adsorption method of specific surface area analysis, and is calculated using the BET (Brunauer-Emmett-Teller) method. The test for the analysis of the specific nitrogen adsorption surface area can be performed with a Tri-Star 3020 pore size analyzer from Micromeritics, USA.

[0165] In some embodiments, the specific surface area of ​​the silicon-carbon material can be 3.1 m². 2 / g, 3.15 m 2 / g, 3.2 m 2 / g, 3.25 m 2 / g, 3.3 m 2 / g, 3.35 m 2 / g, 3.4 m 2 / g, 3.45 m 2 / g, 3.5 m 2 / g, 3.55 m 2 / g, 3.6 m 2 / g or any value in a range between two of these values.

[0166] The specific surface area of ​​the silicon-carbon material is in the above range, which shortens the migration path of the lithium ions in the solid phase while also taking into account the lower reactivity, thus ensuring the fast charging capability and the cycle time of the battery cell.

[0167] In some embodiments, the powder density of the silicon-carbon material at 25,000 N is 0.7 g / cm³. 3 up to 1.2 g / cm³ 3 .

[0168] The powder density of the silicon-carbon material at 25,000 N has a well-known significance in engineering and can be tested using established methods and equipment. For example, it can be measured with an electronic pressure tester (e.g., the UTM7305 type electronic pressure tester) in accordance with GB / T 24533-2019. For example, the test procedure is as follows: 1 g of silicon-carbon material is weighed and removed, then placed into a mold with a base area of ​​1.327 cm². 2 Given a pressure of 25,000N, held for 30 seconds, then depressurized and held for 10 seconds, the powder density of the active material under the force of 25,000N is recorded and calculated.

[0169] In some embodiments, the powder density of the silicon-carbon material can be 0.7 g / cm³ at 25,000 N. 3 , 0.75 g / cm³ 3 , 0.8 g / cm³ 3, 0.85 g / cm³ 3 , 0.9 g / cm³ 3 , 0.95 g / cm³ 3 , 1.0 g / cm³ 3 , 1.05 g / cm³ 3 , 1.1 g / cm³ 3 , 1.15 g / cm³ 3 , 1.2 g / cm³ 3 or any value within a range between two of these values.

[0170] The silicon-carbon material with a powder density in the above range has no negative impact on the density of the anode foil and does not degrade the energy density of the battery cell.

[0171] In some embodiments, the active anode material comprises a carbon-based material.

[0172] In some embodiments, the carbon-based material comprises one or more of graphite and hard carbon, optionally graphite.

[0173] In some embodiments, the carbon-based material comprises composite graphite particles, wherein the composite graphite particles comprise graphite body particles and a carbon coating layer applied to at least a part of the surface of the composite graphite particles, wherein the composite graphite particles comprise secondary particles, and wherein the carbon coating layer comprises amorphous carbon.

[0174] Secondary particles refer to particles formed by the aggregation of more than two primary particles. The composite graphite particles containing secondary particles and the surface coating layer containing amorphous carbon contribute to further improving the infiltration performance of the electrolyte solution into the active anode substance layer and increasing the solid-phase transfer capacity of the active ions, thus further improving the fast-charging performance and cycle stability of the battery cell.

[0175] In some embodiments, the mass fraction of amorphous carbon, based on the total mass of the composite graphite particles, is 2% to 5%.

[0176] In some embodiments, the mass fraction of amorphous carbon can be 2%, 3%, 4%, 5% or any value in a range between two of these values, based on the total mass of the composite graphite particles.

[0177] The amorphous carbon content is within a suitable range, so that the composite graphite material exhibits a high transfer capacity of active ions in the solid phase along with a high gram capacity, which contributes to a further improvement in the energy density and fast charging performance of the battery cell in a comprehensive way.

[0178] In some embodiments, the composite graphite particles have a volume-average particle size Dv50 of 8.5 µm to 16.5 µm.

[0179] The volume-averaged particle size Dv50 has a well-established meaning in engineering and corresponds to the particle size that represents a cumulative percentage volume distribution fraction of 50% of the material, which can be determined using instruments and methods known in engineering. For example, a laser particle size analyzer has been used for convenient determination with reference to GB / T 19077-2016 Laser Diffraction Method for Particle Size Distribution. The testing instrument can be a Mastersizer 3000 laser particle size analyzer from Malvern Instruments Ltd, UK. The composite graphite particles can be freshly produced or obtained by scraping powder from the active anode material layer after disassembling the battery cell.For example: The battery was discharged to 0% SOC, then disassembled to remove the anode foil. A certain amount of powder was scraped off the electrode foil with a blade and then rinsed with deionized water using clear and repeated agitations for 5-10 cycles. After drying, it was sintered in a tube furnace at 400°C for 2 hours. After sintering was complete, an appropriate amount of the sample to be measured was taken (the sample concentration being adjusted to ensure that 8% to 12% of the color shade could be used), and deionized water was added while ultrasonic dispersion was performed to ensure complete dispersion of the sample. The sample was then analyzed according to standard GB / T 19077-2016 / ISO 13320:2009.

[0180] In some embodiments, the volume mean particle size Dv50 of the composite graphite particles 8.5 µm, 9.5 µm, 10.5 µm, 11.5 µm, 12.5 µm, 13.5 µm, 14.5 µm, 15.5 µm, 16.5 µm can be any value in a range between two of these values.

[0181] The volume-average particle size of the composite graphite particles is in the above range, which shortens the migration path of the lithium ions in the solid phase and at the same time takes into account the lower reactivity, thus ensuring the fast charging capability as well as the cycle time of the battery cell.

[0182] In some embodiments, the density of the active anode substance layer is 1.10 g / cm³. 3 up to 1.50 g / cm² 3 .

[0183] The density of the active anode layer has a well-established significance in engineering and can be tested using established methods. For example, the battery cell is heated to 25°C, charged to a cutoff voltage of 3.65 V with a constant current of 0.33 C, and then charged to 0.05 C with a constant voltage of 3.65 V. At this point, the battery cell is fully charged, and the anode foil is then removed, and the density of the active anode layer is measured. The density of the active anode layer is the weight of one side of the active anode layer measured after removal / thickness of one side of the active anode layer.

[0184] The thickness of the active anode layer is of well-known importance in engineering, as it can be tested using established methods, such as a universal measuring tape (e.g., the Mitutoyo 293-100 type with an accuracy of 0.1 µm). It is understood that the density of the active anode layer will differ from the design density of the battery cell when the battery is fully charged. Due to practical operating conditions, the density of the active anode layer is often slightly lower than the design density of the battery cell when the battery is fully charged.

[0185] In some embodiments, the density of the active anode substance layer can be 1.10 g / cm³. 3 , 1.15 g / cm³ 3 , 1.20 g / cm³ 3 , 1.25 g / cm³ 3 , 1.30 g / cm³ 3 , 1.35 g / cm³ 3 , 1.40 g / cm³ 3 , 1.45g / cm³ 3, 1.50 g / cm² 3 or any value within a range between two of these values.

[0186] The density of the active anode substance layer is within the range above, so that the battery has excellent energy density while further improving the fast charging performance and cycle stability of the battery cells.

[0187] In some embodiments, the electrode assembly has a stacked structure.

[0188] In some embodiments, such as in Fig. As shown in Figure 1, the anode foil 122 comprises an anode collector 1221 and an active cathode substance layer 1222, which is provided on at least one side of the anode collector 1221, wherein the dimension of the active anode substance layer 1222 along the longitudinal direction of the electrode assembly is 200 mm to 650 mm, the dimension can be measured with a measuring ruler.

[0189] In some embodiments, the dimension of the active anode substance layer along the longitudinal direction of the electrode assembly can be 200 nm, 250 nm, 300 mm, 350 mm, 400 mm, 450 mm, 500 mm, 550 mm, 600 mm, 650 mm or any value in a range between two of these values.

[0190] The design of stacked electrode assemblies, where the dimension of the active anode substance layer along the longitudinal direction of the electrode assembly lies within the above range, is beneficial for considering the energy density, cycle stability and fast charging performance of the battery cell.

[0191] In some embodiments, the active anode substance layer optionally comprises a binder. This binder may be 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).

[0192] In some embodiments, the active anode material layer optionally comprises a conductive material. The conductive material can be at least one of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dot, carbon nanotubes, graphene, and carbon nanofibers.

[0193] In some embodiments, the electrolyte solution comprises a first solvent, wherein the first solvent has a viscosity η of 0.3 mPa-s to 0.6 mPa-s at room temperature, wherein the mass fraction of the first solvent, based on the total mass of the electrolyte solution, is 8% to 60%.

[0194] The type and mass of the solvent in the electrolyte solution can be determined by testing the electrolyte solution using methods known to those skilled in the art in this field. In the embodiments of the present application, a freshly prepared electrolyte solution can be taken as a sample, and a free electrolyte solution from a freshly prepared battery can be taken as a sample, or a discharged battery cell (which has been discharged to a discharge cut-off voltage so that the state of charge of the battery cell is approximately 0% SOC) can be disassembled in the reverse manner, and the free electrolyte solution obtained from the battery cell can be taken as a sample. The test was carried out by ion chromatographic analysis.The type and concentration of the organic components in the electrolyte solution are known in their technical significance and can be detected using established equipment and methods. For example, the organic components in the electrolyte solution can be qualitatively and quantitatively analyzed by gas chromatography in accordance with GB / T9722-2023 "General principles for gas chromatography of chemical reagents". The type and concentration of the inorganic component / lithium salt in the electrolyte solution are known in their technical significance and can be detected using established equipment and methods. For example, the inorganic component / lithium salt in the electrolyte solution can be qualitatively or quantitatively analyzed by ion chromatography in accordance with standard JY / T020-2002 "General principles of ion chromatography analysis methods".

[0195] The viscosity of the first solvent at room temperature can be tested using a similar procedure to the viscosity of the electrolyte solution at room temperature (see above).

[0196] In some embodiments, the mass fraction of the first solvent may be 8%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60% or any value in a range between two of these values, based on the total mass of the electrolyte solution.

[0197] In some embodiments, the viscosity η of the first solvent can be 0.3 mPa-s, 0.35 mPa-s, 0.4 mPa-s, 0.45 mPa-s, 0.5 mPa-s, 0.55 mPa-s, 0.6 mPa-s or any value in a range between two of these values.

[0198] The first solvent with a viscosity η in the above range has excellent stability and low viscosity, and the mass fraction of the first solvent is in the above range, which helps to reduce the viscosity of the electrolyte solution and increase the conductivity of the electrolyte solution while taking into account the stability of the electrolyte solution, thus contributing to a further comprehensive improvement in the fast charging performance and cycle stability of the battery cell.

[0199] In some embodiments, the mass fraction of the first solvent, based on the total mass of the electrolyte solution, is 30% to 60%.

[0200] If the mass fraction of the first solvent is in the above range, while the viscosity of the electrolyte solution is further reduced, the electrolyte solution exhibits good stability and conductivity, which allows for a further improvement in the cycle stability of the battery cell.

[0201] In some embodiments, the first solvent comprises a carboxylic acid ester solvent.

[0202] The carboxylic acid ester solvent has the advantages of low viscosity and high ionic conductivity, which promotes the infiltration of the electrolyte solution into the active cathode and anode substance layer and the rapid embedding and release of the active ions in the active anode substance layer, thus further improving the cycle stability and fast charging performance of the battery cell.

[0203] In some embodiments, the carboxylic acid ester solvent has a general structural formula of R '-COO-R", wherein R' comprises one or more of a hydrogen atom, a halogen atom, a C1 to C5 alkyl group and a C1 to C5 haloalkyl group, wherein R" comprises one or more of a C1 to C5 alkyl group and a C1 to C5 alkyl halide group.

[0204] “C1 to C5 alkyl group” means an unbranched or branched alkyl group with 1 to 5 carbon atoms, including one or more of the groups methyl, ethyl, propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, n-pentyl, 2-pentyl, 2-methylbutyl, 3-methylbutyl, 1,2-dimethylpropyl, 1,1-dimethylpropyl, 2,2-dimethylpropyl and 1-ethylpropyl.

[0205] “C1-C5 halogenalkyl” means an unbranched or branched alkyl group with 1-5 carbon atoms in which at least one hydrogen atom is replaced by a halogen, including but not limited to one or more of chloroalkyl, bromoalkyl, iodoalkyl.

[0206] "Halogen" means an element of group VIIA of the periodic table of chemical elements; in particular, halogens include the elements fluorine, chlorine, bromine, iodine or astatine.

[0207] In some embodiments, the carboxylic acid ester solvent comprises one or more of methyl formate, methyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, propyl propionate, methyl butyrate, ethyl butyrate.

[0208] In some embodiments, the electrolyte solution further comprises a second solvent, wherein the second solvent comprises a carbonate solvent, the carbonate solvent comprising one or more of vinyl carbonate, propylene carbonate, butylene carbonate, dimethyl carbonate, diethyl carbonate and methylene carbonate.

[0209] The carbonate solvent has a high dielectric constant, and the carbonate solvent and lithium ions in the lithium-containing electrolyte salt can easily form a solvated structure to improve the dissociation rate of lithium ions and anions in the lithium-containing electrolyte salt, further improving the fast charging performance of the battery cell.

[0210] In some embodiments, the mass fraction of the carbonate solvent, based on the total mass of the electrolyte solution, is 18% to 75%.

[0211] In some embodiments, the mass fraction of the carbonate solvent can be 18%, 20%, 30%, 40%, 50%, 60%, 70%, 75% or any value in a range between two of these values, based on the total mass of the electrolyte solution.

[0212] Since the carbonate solvent has a high viscosity, the viscosity of the electrolyte solution increases with increasing carbonate solvent concentration, which negatively affects the electrolyte solution's conductivity. By carefully controlling the mass fraction of the carbonate solvent within the range described above, the electrolyte solution exhibits both appropriate viscosity and conductivity, as well as good dissociation rate and infiltration properties, contributing to a comprehensive improvement in the kinetic performance and cycle stability of the battery cell.

[0213] In some embodiments, the electrolyte solution comprises a lithium-containing electrolyte salt, wherein the mass fraction of the lithium-containing electrolyte salt in the electrolyte solution, based on the total mass of the electrolyte solution, is 10% to 18%.

[0214] The type and mass of the lithium-containing electrolyte salt in the electrolyte solution can be determined by testing the electrolyte solution using methods known to those skilled in the art. For example, the test methods described above can be used to determine the type and mass of the solvent in the electrolyte solution.

[0215] In some embodiments, the mass fraction of the lithium-containing electrolyte salt in the electrolyte solution can be 10%, 11%, 12%, 13%, 14%, 15%, 16%, 17%, 18% or any value in a range between two of these values.

[0216] If the molar concentration of the lithium-containing electrolyte salt in the electrolyte solution is in the above range, it is advantageous to consider the infiltration properties and the ionic conductivity of the electrolyte solution, which can comprehensively improve the cycle stability and fast charging performance of the battery cell.

[0217] In some embodiments, the lithium-containing electrolyte salt comprises one or more of lithium bis(fluorosulfonyl)imide LiFSI and lithium hexafluorophosphate LiPF6.

[0218] LiFSI dissociates readily in the solvent of the electrolyte solution, and its molecular weight is lower than that of other types of fluorosulfonimide salts (e.g., lithium bis(trifluoromethanesulfonate)imide, LiTFSI). This contributes to improved electrolyte conductivity while simultaneously reducing the viscosity of the electrolyte solution. Furthermore, LiFSI exhibits good thermal stability and does not tend to decompose during cycling. This can reduce hydrogen fluoride generation during battery cycles and the likelihood of side reactions at the anode, further enhancing cycle stability and fast-charging performance of the battery cell.However, as the battery cell temperature increases, LiFSI decomposes rapidly above a certain temperature threshold, releasing a large amount of heat. This significantly increases the risk of thermal runaway, posing a greater safety risk for fast-charging batteries. The lithium-containing electrolyte salt can also include lithium hexafluorophosphate (LiPF6), which can reduce the risk of thermal runaway, keeping it within a manageable range and thus improving the battery cell's safety performance.

[0219] In some embodiments, the mass fraction of lithium bis(fluorosulfonyl)imide LiFSI, based on the total mass of the electrolyte solution, is 4% to 8%.

[0220] In some embodiments, the mass fraction of lithium bis(fluorosulfonyl)imide LiFSI in the electrolyte solution can be 4%, 5%, 6%, 7%, 8% or any value in a range between two of these values, based on the total mass of the electrolyte solution.

[0221] The battery cell with the molar concentration of lithium bis(fluorosulfonyl)imide in the electrolyte solution within the above range can take into account the kinetic performance, cycle stability and safety performance of the battery cell.

[0222] In some embodiments, the electrolyte solution further comprises an additive, wherein the additive comprises one or more of a carbonate additive, a sulfur-containing additive, a lithium salt-like additive and a fluorobenzene additive.

[0223] The additive is a component with a low concentration in the electrolyte solution, generally comprising no more than 10% by mass, and has the properties that it can be used in a very targeted manner and in small doses, so that it can significantly optimize the performance of a specific aspect of the battery without changing the production process.

[0224] In the present application, the carbonate additive, i.e. the compounds and their derivatives containing a carbonate group (-O-CO-O-), as well as the mixtures containing said compounds and their derivatives, is the application.

[0225] In the present application, the fluorobenzene additive is organic compounds and their derivatives in which one or more hydrogen atoms on the benzene ring have been replaced by fluorine atoms, as well as mixtures containing these compounds and their derivatives.

[0226] The type of additive in the electrolyte solution can be determined by testing the electrolyte solution using methods known to those skilled in the art. For example, the test methods described above can be used to determine the type and mass of the solvent in the electrolyte solution.

[0227] In some embodiments, the carbonate additive comprises one or more vinylidene carbonate and a vinyl carbonate derivative, wherein the vinyl carbonate derivative comprises a compound represented in Formula I,

[0228] wherein R1, R2, R3, R4 each independently comprise a hydrogen atom, a halogen atom, a C1 to C5 alkyl group and a C1 to C5 haloalkyl group, and wherein R1, R2, R3, R4 are not simultaneously hydrogen atoms, wherein the carbonate additive may optionally comprise one or more of vinylidene carbonate and fluorinated vinyl carbonate.

[0229] The carbonate additive can evolve into organic components within the SEI film, which contributes to improving the toughness of the SEI film, reducing SEI film breakage due to volume changes of the silicon-based material, preventing side reactions between the electrolyte solution and the silicon-based material, reducing battery gas generation, and lowering the anode-side interfacial impedance, further improving the cycle and storage life as well as the fast-charging performance of the battery cell.

[0230] In some embodiments, the sulfur-containing additive comprises one or more of vinyl sulfate, vinyl bisulfate, 1,3-propanesulfonate lactone, butyl sulfite, vinyl sulfite and methylenedisulfonylmethylene.

[0231] The sulfur-containing additive tends to have a high potential, and the sulfur-containing additive added to the electrolyte solution reacts preferentially during formation or the subsequent cycling process, developing into sulfur-containing inorganic components in the SEI film. The SEI film formed by the carbonate additive exhibits poor stability at high temperatures, which is detrimental to the stability of the battery cell in a high-temperature environment. The SEI film contains sulfur element, which can further improve the thermal stability of the SEI film at high temperatures and further reduce the interfacial impedance on the anode side, leading to further improvements in the cycle stability and fast-charging performance of the battery cell.

[0232] In some embodiments, the lithium salt-like additive comprises one or more of lithium difluorophosphate, lithium difluorooxalate borate, lithium tetrafluoroborate, lithium bisoxalate borate.

[0233] The lithium salt-like additive can develop into inorganic components within the SEI film, further improving its stiffness and stability, thereby enhancing the battery's cycle stability and fast-charging performance. Furthermore, this lithium salt-like additive can also form an interfacial electrolyte (CEI) film on the surface of the active cathode material, further improving the battery cell's cycle stability.

[0234] In some embodiments, the fluorobenzene additive comprises one or more of a fluorobenzene and its derivatives.

[0235] The fluorobenzene additive can contribute to improving the infiltration properties of the electrolyte solution into the active cathode and anode substance layer, thereby further improving the cycle stability and fast charging performance of the battery cell.

[0236] In some embodiments, the mass fraction of the carbonate additive, based on the total mass of the electrolyte solution, is 3% to 8%.

[0237] The percentage by mass of the additive, relative to the total mass of the electrolyte solution, can be tested using any method known in the art, e.g., using the previously described method for testing the mass fraction of the solvent and the lithium-containing electrolyte salt in the electrolyte solution. It should be noted that the mass fraction of the additive in the electrolyte solution may be somewhat lower than the initial mass fraction of the additive added to the electrolyte solution, as the additive in the electrolyte solution is depleted during the formation and cycle for generating the relevant components of the SEI film and / or CEI film.

[0238] In some embodiments, the mass fraction of the carbonate additive is optionally 3%, 4%, 5%, 6%, 7%, 8% or any value in a range between any two of these values, based on the total mass of the electrolyte solution.

[0239] The mass fraction of the carbonate additive in the electrolyte solution is within the above range, which both increases the stability of the SEI film and keeps the viscosity of the electrolyte solution at a suitable level to further improve the cycle life of the battery cell and the fast charging performance in a comprehensive way.

[0240] In some embodiments, the mass fraction of vinylidene carbonate, based on the total mass of the electrolyte solution, is 2% to 5%.

[0241] In some embodiments, the mass fraction of vinylidene carbonate can be 2%, 3%, 4%, 5%, or any value in a range between two of these values, based on the total mass of the electrolyte solution.

[0242] Vinylidene carbonate (VC) has a reduction potential similar to that of carboxylic acid ester solvents, thus inhibiting the reactivity of these solvents and improving the cycle life of the battery cell. However, an excessively high VC content leads to an increase in interfacial impedance and charge transfer impedance, negatively impacting the fast-charging performance of the battery cell. The mass fraction of vinylidene carbonate (VC) is within the range mentioned above, ensuring excellent cycle life and fast-charging performance for the battery.

[0243] In some embodiments, the mass fraction of the vinyl carbonate derivative, based on the total mass of the electrolyte solution, is 0% to 4%.

[0244] In some embodiments, the mass fraction of the vinyl carbonate derivative, based on the total mass of the electrolyte solution, is 1.5% to 3.5%.

[0245] In some embodiments, the mass fraction of the vinyl carbonate derivative, based on the total mass of the electrolyte solution, can be 0.5%, 1%, 2%, 3%, 4%, or any value in a range between two of these values.

[0246] It should be noted that when charging and discharging the battery cell, if the vinyl carbonate derivative is added in small quantities, and if the electrolyte solution is obtained by disassembling the battery cell and the vinyl carbonate derivative content is tested by gas chromatography, the content may be 0%. It is understood that in some embodiments, the vinyl carbonate derivative added to the electrolyte solution is completely converted into an organic component within the SEI film during the formation process. In other embodiments, the vinyl carbonate derivative remains in the electrolyte solution to reinforce the SEI film during subsequent battery cell cycles.

[0247] The vinyl carbonate derivative can also form a film on the anode surface at high potential and has low interfacial and charge transfer impedance. Its mass fraction is within the range mentioned above, enabling the battery cell to achieve excellent fast-charging performance and cycle life. Adding vinylidene carbonate (VC) and vinyl carbonate derivatives to the electrolyte solution can significantly improve the fast-charging performance and cycle stability of the battery cell.

[0248] In some embodiments, the mass fraction of the sulfur-containing additive, based on the total mass of the electrolyte solution, is 0% to 2%.

[0249] In some embodiments, the mass fraction of the sulfur-containing additive, based on the total mass of the electrolyte solution, is 0.5% to 2%.

[0250] In some embodiments, the mass fraction of the sulfur-containing additive can be 0.5%, 1%, 1.5%, 2% or any value in a range between two of these values, based on the total mass of the electrolyte solution.

[0251] Since the additives in the electrolyte solution are consumed during formation and charge / discharge cycles to produce the corresponding components in the SEI film and / or CEI film, the content of the sulfur-containing additive and the lithium salt-like additive can be 0% after disassembly of the battery cell to obtain the electrolyte solution in a gas chromatographic analysis.

[0252] In particular, if the mass fraction of the sulfur-containing additive is 0%, for example, no sulfur-containing additive may be added to the freshly prepared electrolyte solution, or the electrolyte solution obtained after disassembling the battery cell may not contain any sulfur-containing additive. It may be the case that no sulfur-containing additive is added to the freshly prepared electrolyte solution, or a small amount of sulfur-containing additive is added, which, however, participates in the SEI film formation reaction during battery cell formation, so that the mass fraction of the sulfur-containing additive in the test procedure is 0%. Optionally, the freshly prepared electrolyte solution includes the sulfur-containing additive.

[0253] When certain substances, such as additives, are added to the electrolyte solution, the additive concentration in the battery cell's electrolyte solution is related to the various life cycles or storage conditions of the battery after formation, since the additive has the property of participating in film formation on the surface of the active material. Therefore, the additive concentration in the freshly prepared electrolyte solution may differ from that in the electrolyte solution obtained by reverse disassembly of the battery cell. However, a person skilled in the art can determine the approximate range of the concentration of the corresponding substances in the fresh electrolyte solution based on the battery cell's performance level (e.g., number of cycles), residual concentration, and the like. Similarly, a person skilled in the art can also determine the approximate range of the corresponding concentration in the non-freshly prepared (i.e., previously used) electrolyte solution.(converse) content based on the additive content of the freshly produced additive based on the performance requirements for the battery cell, the storage environment, and the like.

[0254] Therefore, the additive content referred to in the technical solution of the present application can be the content of the additive that is actively added to the fresh electrolyte solution, or the content of the residual additive that is determined conversely according to the actual battery condition.

[0255] In some embodiments, the sulfur-containing additive added to the electrolyte solution is completely converted into sulfur-containing components in the SEI film during the formation process, and the amount of sulfur-containing additive added to the electrolyte solution can be determined from X-ray photoelectron spectroscopy (XPS) tests of the anode material. In some embodiments, the sulfur-containing additive remains in the electrolyte solution to strengthen the SEI film during subsequent battery cell cycles.

[0256] In the present application, the X-ray photoelectron spectroscopy (XPS) of the anode material can be tested in any manner known in the art. For example, the battery cell is disassembled, and the anode foil is cleaned more than three times with a solvent such as dimethyl carbonate (DMC) to clean the electrode foil. The powder is then scraped off for sampling, and the resulting sample powder of the anode material is adhered to the conductive substrate. An X-ray photoelectron spectrometer (e.g., AXIS ULTRA) was used to perform the X-ray photoelectron spectroscopy test. The sampling rate and time of the X-ray source were set to focus and detect the elements and functional groups at a depth of 5 nm to 10 nm from the surface of the anode material. The X-ray photoelectron spectroscopy (XPS) of the sample was then obtained, and the characteristic element peaks in the spectrum were subsequently analyzed.

[0257] The mass fraction of the sulfur-containing additive in the electrolyte solution is within the above range, which both increases the thermal stability of the SEI film at high temperatures and keeps the viscosity of the electrolyte solution at a suitable level to further improve the cycle life of the battery cell and the fast charging performance in a comprehensive way.

[0258] In some embodiments, the mass fraction of the lithium salt-like additive, based on the total mass of the electrolyte solution, is 0% to 1%.

[0259] In some embodiments, the mass fraction of the lithium salt-like additive, based on the total mass of the electrolyte solution, is 0.2% to 1%.

[0260] In some embodiments, the mass fraction of the lithium salt-like additive is optionally 0.2%, 0.4%, 0.6%, 0.8%, 1% or any value in a range between any two of these values, based on the total mass of the electrolyte solution.

[0261] It is understood that in some embodiments, the lithium salt-like additive added to the electrolyte solution is completely converted into an inorganic component within the SEI film and / or CEI film during the formation process. In other embodiments, the lithium salt-like additive remains in the electrolyte solution to reinforce the SEI film and / or the CEI film during subsequent battery cell cycles.

[0262] The mass fraction of the lithium salt-like additive in the electrolyte solution is within the above range, which both increases the stability of the SEI film and keeps the viscosity of the electrolyte solution at a suitable level to further improve the cycle life of the battery cell and the fast charging performance in a comprehensive way.

[0263] In some embodiments, the mass content of the fluorobenzene additive, based on the total mass of the electrolyte solution, is 0.1% to 1%.

[0264] In some embodiments, the mass fraction of the fluorobenzene additive is optionally 0.1%, 0.2%, 0.3%, 0.4%, 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1.0% or any value in a range between any two of these values, based on the total mass of the electrolyte solution.

[0265] The mass fraction of the fluorobenzene additive in the electrolyte solution is within the above range, which takes into account both the infiltration properties of the electrolyte solution and keeps the viscosity of the electrolyte solution at a suitable level to further improve the cycle life of the battery cell and the fast charging performance in a comprehensive way.

[0266] In some embodiments, along the longitudinal direction of the electrode assembly, the dimension of the active anode substance layer is larger than the dimension of the active cathode substance layer, wherein the difference between the dimension of the active anode substance layer and the dimension of the active cathode substance layer is OH1; and along the transverse direction of the electrode assembly, the dimension of the active anode substance layer is larger than the dimension of the active cathode substance layer, wherein the difference between the dimension of the active anode substance layer and the dimension of the active cathode substance layer is OH2, where OH1 is 1.0 mm to 4.0 mm; and / or where OH2 is 1.0 mm to 3.0 mm.

[0267] In the present application, as in Fig. Figure 1 shows the dimension of the active cathode substance layer 1212 OH along the longitudinal direction of the electrode assembly 12. 11, the dimension of the active anode substance layer 1222 OH 21 , and the difference between the dimension of the active anode substance layer 1222 and the dimension of the active cathode substance layer 1212 is OH1=OH 21 -OH 11 ; As in Fig. Figure 2 shows the dimension of the active cathode substance layer 1212 OH along the width direction of the electrode assembly. 12 , the dimension of the active anode substance layer 1222 OH 22 , and the difference between the dimension of the active anode substance layer 1222 and the dimension of the active cathode substance layer 1212 is OH1=OH 22 -OH 12 , and the dimensions can be measured with a ruler.

[0268] In some embodiments, OH1 is optionally 1.0 mm, 1.1 mm, 1.3 mm, 1.5 mm, 1.7 mm, 1.9 mm, 2.1 mm, 2.3 mm, 2.5 mm, 2.7 mm, 2.9 mm, 3.1 mm, 3.3 mm, 3.5 mm, 3.7 mm, 3.9 mm, 4.0 mm or any value in a range between any two of these values.

[0269] In some embodiments, OH2 is optionally 1.0 mm, 1.1 mm, 1.3 mm, 1.5 mm, 1.7 mm, 1.9 mm, 2.1 mm, 2.3 mm, 2.5 mm, 2.7 mm, 2.9 mm, 3.0 mm or any value in a range between any two of these values.

[0270] As the charging rate of the battery cell increases, the area near the electrode tab experiences high current density and a steep temperature rise, making the active anode layer susceptible to lithium dendrite formation near the electrode tab. The design of OH1 and OH2 improves the ability of the active anode layer, particularly the active anode layer near the electrode tab, to attract active ions in the longitudinal direction. It also positions the active cathode layer further away from the electrode tab and results in a more uniform current distribution in the active layer near the electrode tab, leading to a reduction in the temperature rise and thus significantly improving lithium precipitation in the anode foil.At the same time, the probability of cathode and anode overlap due to thermal contraction of the separator and internal short circuit of the battery is reduced, improving the fast charging performance and cycle stability of the battery cell, while controlling the values ​​of OH1 and OH2 in the above ranges, so that the battery cell can have excellent energy density.

[0271] In some embodiments, OH1 is greater than or equal to OH2.

[0272] By controlling that OH1 is larger than OH2, the cycle stability of the battery cell can be improved and at the same time a further improvement in the energy density of the battery cell can be enabled.

[0273] In some embodiments, the cathode collector comprises a cathode collector section and a cathode tab, wherein the cathode tab is provided at at least one end in the extension direction of the cathode collector section along the longitudinal direction of the electrode assembly or at at least one side in the extension direction along the width direction of the electrode assembly.

[0274] In some embodiments, such as in Fig. As shown in Figure 3, the cathode collector 1211 comprises a cathode collector section 12110 and a cathode tab 12111, wherein the cathode tab 12111 is provided at one end in the extension direction of the cathode collector section 12110 along the longitudinal direction of the electrode assembly.

[0275] The above arrangement of the electrode tabs contributes to improving the energy density of the battery cell.

[0276] In some embodiments, such as in Fig.As shown in Figure 4, the cathode tab 12111 is provided at both ends in the extension direction of the cathode collector section 12110 along the longitudinal direction of the electrode assembly.

[0277] The above electrode tab contributes to improving the overcurrent capability of the battery cell, alleviating the situation of lithium precipitation on the electrode tab side caused by the decomposition of the electrolyte solution and the uneven current distribution on the electrode tab side due to the high temperature during fast charging, and thus improving the fast charging performance and the cycle stability of the battery cell, which is particularly suitable for improving the fast charging performance of batteries with an active substance layer with a length dimension of more than 500 mm, taking into account the excellent volumetric energy density.

[0278] In some embodiments, such as in Fig.As shown in Figure 5, the cathode tab 12111 is provided on one side in the extension direction of the cathode collector section 12110 along the width direction of the electrode assembly.

[0279] In some embodiments, such as in Fig. As shown in Figure 6, the cathode tab 12111 is provided on both sides in the extension direction of the cathode collector section 12110 along the width direction of the electrode assembly.

[0280] The electrode tab above contributes to further improving the overcurrent capability of the battery cell and thus further improving the fast charging performance and the cycle stability of the battery cell, which is particularly suitable for improving the fast charging performance of batteries with the active substance layer having a length dimension of more than 500 mm.

[0281] In some embodiments, the anode collector comprises an anode collector section and an anode tab, wherein the anode tab is provided at least at one end in the extension direction of the anode collector section along the longitudinal direction of the electrode assembly or at least at one side in the extension direction along the width direction of the electrode assembly.

[0282] In some embodiments, such as in Fig. As shown in Figure 7, the anode collector 1221 comprises an anode collector section 12210 and an anode tab 12211, wherein the anode tab 12211 is provided at one end in the extension direction of the anode collector section 12210 along the longitudinal direction of the electrode assembly.

[0283] In some embodiments, such as in Fig.As shown in Figure 8, the anode tab 12211 is provided at both ends in the extension direction of the anode collector section 12210 along the longitudinal direction of the electrode assembly.

[0284] In some embodiments, such as in Fig. As shown in Figure 9, the anode tab 12211 is provided on one side in the extension direction of the anode collector section 12210 along the width direction of the electrode assembly.

[0285] In some embodiments, such as in Fig. As shown in Figure 10, the anode tab 12211 is provided on both sides in the extension direction of the anode collector section 12210 along the width direction of the electrode assembly.

[0286] In some embodiments, the active anode substance layer has a dimension of more than 500 mm along the longitudinal direction of the electrode assembly, wherein the anode tab is provided at both ends in the extension direction of the anode collector section along the longitudinal direction of the electrode assembly or on at least one side in the extension direction along the width direction of the electrode assembly.

[0287] In some embodiments, such as in Fig. 3 and Fig. As shown in Figure 4, the cathode tab is provided at at least one end in the extension direction of the cathode collector section along the longitudinal direction of the electrode assembly, wherein the ratio of the width of the cathode tab to the width of the cathode collector section is 0.25 to 1.

[0288] In some embodiments, such as in Fig. 7 and Fig.As shown in Figure 8, the anode tab is provided at at least one end in the extension direction of the anode collector section along the longitudinal direction of the electrode assembly, wherein the ratio of the width of the anode tab to the width of the anode collector section is 0.25 to 1.

[0289] In some embodiments, such as in Fig. 5 and Fig. As shown in Figure 6, the cathode tab is provided on at least one side in the extension direction of the cathode collector section along the width direction of the electrode assembly, wherein the ratio of the width of the cathode tab to the length of the cathode collector section is 0.25 to 1.

[0290] In some embodiments, such as in Fig. 9 and Fig.As shown in Figure 10, the anode tab is provided on at least one side in the extension direction of the anode collector section along the width direction of the electrode assembly, wherein the ratio of the width of the anode tab to the length of the anode collector section is 0.25 to 1.

[0291] In some embodiments, the ratio of the width of the cathode tab to the width of the cathode collector section or the ratio of the width of the anode tab to the width of the anode collector section may be 0.25, 0.35, 0.45, 0.55, 0.65, 0.75, 0.85, 0.95, 1 or any value in a range between two of these values.

[0292] The width of the electrode tab lies within the above range, thereby increasing the overcurrent capability of the battery cell and improving the fast charging performance as well as the cycle stability of the battery cell.

[0293] In some embodiments, the active cathode material comprises: a lithium-containing phosphate with an olivine structure, and a coating layer, wherein the coating layer is located on at least a part of the surface of the lithium-containing phosphate, and the coating layer comprises a carbon element.

[0294] The coating layer contains carbon elements, which increases the electronic conductivity of the lithium-containing phosphate and improves the transfer rate of electrons in the solid phase, thereby further improving the energy density and fast charging performance of the battery cell.

[0295] In some embodiments, the mass fraction of the carbon element, based on the total mass of the active cathode material, is 0.8% to 2.3%.

[0296] In some embodiments, the mass fraction of the carbon element is optionally 0.8%, 1.1%, 1.4%, 1.7%, 2.0%, 2.3% or any value in a range between two of these values, based on the total mass of the active cathode material.

[0297] With respect to the total mass of the active cathode material, the mass fraction of the carbon element lies within the above range, which means that the lithium-containing phosphate exhibits both excellent electronic conductivity and a high gram capacity, further comprehensively improving the energy density and fast charging performance of the battery cell.

[0298] In some embodiments, the coating layer further comprises a component shown in Formula II,

[0299] Li 3-d1 Fe 2-d1 M1 d1 (PO m1 ) n1, Formula II, where 0≤d1≤1, 3≤m1≤5, 2≤n1≤4, where M1 comprises one or more of the elements Ti, Zr, Hf, Ge, Sn, where M1 optionally has the valency +4.

[0300] In some embodiments, d1 is optionally 0, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1 or any value in a range between any two of these values; m1 is optionally 3, 3.1, 3.2, 3.3, 3.4, 3.5, 3.6, 3.7, 3.8, 3.9, 4, 4.1, 4.2, 4.3, 4.4, 4.5, 4.6, 4.7, 4.8, 4.9, 5 or any value in a range between any two of these values; n1 is optionally 2, 2.1, 2.2, 2.3, 2.4, 2.5, 2.6, 2.7, 2.8, 2.9, 3, 3.1, 3.2, 3.3, 3.4, 3.5, 3.6, 3.7, 3.8, 3.9, 4 or any value in a range between any two of these values.

[0301] In some embodiments, the component shown in Formula II comprises one or more of Li2FeTi(PO4)3, Li2FeZr(PO4)3, Li2FeSn(PO4)3.

[0302] It should be noted that the coating layer can be structured as a single or multiple layer, i.e., the carbon-containing component in the coating layer and the component shown in Formula II can form a mixed phase or be arranged in layers.

[0303] The phase structure of the coating layer can be characterized using any method known in engineering, e.g., the active cathode material can be characterized by transmission electron microscopy to show that the coating layer of the active cathode material and the substrate have different phase structures, and the components of the coating layer can be assessed by combining diffraction patterns and energy spectrum analysis.

[0304] The component shown in Formula II is a fast-ion conductor with a NASICON structure. Its ionic conductivity is close to or greater than that of conductive liquids such as electrolyte solutions or molten salts. It features numerous three-dimensional lithium-ion diffusion and transfer channels and offers the advantages of high ionic conductivity and strong structural stability during multiple lithium de- / embedding cycles. The coating layer on the surface of the lithium-containing phosphate incorporates a fast-ion conductor with a NASICON structure. This significantly increases the lithium-ion transfer rate at the cathode end during multiple lithium de- / embedding cycles and improves the ionic conductivity of the active cathode material, further enhancing the energy density and fast-charging performance of the battery cell.

[0305] In some embodiments, the lithium-containing phosphate comprises a component represented in formula III,

[0306] Li x1 A y1 Me a1 M 31 P 1-c1 X c1 Y z1 Formula III, where 0.5 ≤ x1 ≤ 1.3, 0 ≤ y1 ≤ 1.3, 0.9 ≤ x1 + y1 ≤ 1.3, 0.9 ≤ a1 ≤ 1.5, 0 ≤ b1 ≤ 0.5, 0.9 ≤ a1 + b1 ≤ 1.5, 0 ≤ c1 ≤ 0.5, 3 ≤ z1 ≤ 5, where A comprises one or more of the elements Na, K and Mg; where Me comprises one or more of the elements Mn, Fe, Co and Ni; where M comprises one or more of the elements B, Mg, Al, Si, P, S, Ca, Sc, Ti, V, Cr, Cu, Zn, Sr, Y, Zr, Nb, Mo, Cd, Sn, Sb, Te, Ba, Ta, W, Yb, La and Ce; where X comprises one or more of the elements S, Si, Cl, B, C, N and P, and where Y comprises one or more of the elements O and F.

[0307] In some embodiments, x1 is optionally 0.5, 0.6, 0.7, 0.8, 0.9, 1, 1.1, 1.2, 1.3 or any value in a range between any two of these values; y1 is optionally 0, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1, 1.1, 1.2, 1.3 or any value in a range between any two of these values; x1 + y1 is optionally 0.9, 1, 1.1, 1.2, 1.3 or any value in a range between any two of these values; a1 is optionally 0.9, 1, 1.1, 1.2, 1.3, 1.4, 1.5 or any value in a range between any two of these values; b1 is optionally 0, 0.1, 0.2, 0.3, 0.4, 0.5 or any value in a range between any two of these values, a1+b1 optional 0.9, 1, 1.1, 1.2, 1.3, 1.4, 1.5 or any value in a range between any two of these values, c1 optional 0, 0.1, 0.2, 0.3, 0.4, 0.5 or any value in a range between any two of these values, z1 optional 3, 3.1, 3.2, 3.3, 3.4, 3.5, 3.6, 3.7, 3.8, 3.9, 4, 4.1, 4.2, 4.3, 4.4, 4.5, 4.6, 4.7, 4.8, 4.9, 5, or any value in a range between any two of these values.

[0308] The lithium-containing phosphate with olivine structure, which the above component has, has good structural stability, which can reduce the loss during the fast charging process and further improve the fast charging performance and cycle stability of the battery cell.

[0309] In some embodiments, the active cathode material comprises one or more of lithium iron phosphate, lithium manganese phosphate, lithium ferromanganese phosphate, lithium nickel phosphate and lithium cobalt phosphate, as well as a modified form of one of the above substances, wherein the modified form comprises one or more of a doped modified form and a coated modified form.

[0310] In some embodiments, the active cathode material has a powder density of 2.45 g / cm³ at 30,000 N. 3 up to 2.75 g / cm³ 3 on.

[0311] The powder density of the cathode material at 30,000 N has a well-established significance and can be tested using established methods and equipment. For example, it can be measured using an electronic pressure tester (e.g., the UTM7305 type electronic pressure tester) in accordance with GB / T 24533-2019. For example, the test procedure is as follows: 1 g of active cathode material is weighed and removed, then placed into a mold with a base area of ​​1.327 cm². 2 Given a pressure of 30000 N, held for 30 seconds, then depressurized and held for 10 seconds, the powder density of the active material under the force of 30000 N is recorded and calculated.

[0312] In some embodiments, the compression density of the active cathode substance layer at 30,000 N is optionally 2.45 g / cm³. 3 , 2.50 g / cm³ 3 , 2.55 g / cm³ 3, 2.60 g / cm³ 3 , 2.65 g / cm³ 3 , 2.70 g / cm³ 3 , 2.75 g / cm³ 3 or any value within a range between two of these values.

[0313] An active cathode material with a powder density in the appropriate range leads to a high density of the active cathode substance layer, which in turn leads to a high energy density of the battery cell.

[0314] In some embodiments, the density of the active cathode substance layer is 2.5 g / cm³. 3 up to 2.83 g / cm³ 3 .

[0315] The density of the active cathode substance layer can be tested using a similar procedure to the density of the active anode substance layer (see above).

[0316] In some embodiments, the density of the active cathode substance layer is optionally 2.50 g / cm³. 3 , 2.53 g / cm³ 3 , 2.55 g / cm³ 3 , 2.57 g / cm³ 3, 2.59 g / cm³ 3 , 2.61 g / cm³ 3 , 2.63 g / cm³ 3 , 2.65 g / cm³ 3 , 2.67 g / cm³ 3 , 2.69 g / cm³ 3 , 2.71 g / cm³ 3 , 2.73 g / cm³ 3 , 2.75 g / cm³ 3 , 2.77 g / cm³ 3 , 2.79 g / cm³ 3 , 2.81 g / cm³ 3 , 2.83 g / cm³ 3 or any value within a range between two of these values.

[0317] The density of the active cathode substance layer lies within the above range, thus achieving a balance between the energy density, fast charging performance and the cycle stability of the battery cell.

[0318] In some embodiments, the one-sided coating weight of the active cathode substance layer is 200 mg / 1540.25 mm². 2 up to 370 mg / 1540.25 mm 2 .

[0319] The one-sided coating weight of the active cathode substance layer can be tested using a similar procedure to the one-sided coating weight of the active anode substance layer described above.

[0320] In some embodiments, the one-sided coating weight of the active cathode substance layer is optionally 230 mg / 1540.25 mm². 2 , 240 mg / 1540.25 mm 2 , 250 mg / 1540.25 mm 2 , 260 mg / 1540.25 mm 2 , 270 mg / 1540.25 mm 2 , 280 mg / 1540.25 mm 2 , 290 mg / 1540.25 mm 2 , 300 mg / 1540.25 mm 2 , 310 mg / 1540.25 mm 2 , 320 mg / 1540.25 mm 2 , 330 mg / 1540.25 mm 2 , 340 mg / 1540.25 mm 2 , 350 mg / 1540.25 mm 2 , 360 mg / 1540.25 mm 2 , 370 mg / 1540.25 mm 2 or any value within a range between two of these values.

[0321] An active cathode substance layer with a one-sided coating weight of the active cathode substance layer within the above range can better balance the fast charging performance and the energy density of the battery cell.

[0322] In some embodiments, the thickness of the cathode collector is 10 µm to 15 µm.

[0323] The material of the cathode collector and / or the anode collector is not particularly restricted, as long as it does not cause any chemical changes in the battery cell and is electrically conductive. The collector comprises a metal foil with a pure metal content of 95% or more, e.g., at least a copper foil, an aluminum foil, a stainless steel foil, a titanium foil, a nickel foil, but also an alloy foil of at least two main elements, such as copper, aluminum, nickel, titanium, iron, and may include copper, an aluminum-cadmium alloy, iron, or stainless steel that has been surface-treated with carbon, nickel, titanium, silver, copper, and the like.Furthermore, the connection with the active anode substance can be improved by the formation of microscopically small bumps and depressions on the surface and can be used in various forms such as films, plates, foils, nets, porous bodies, foams, nonwovens and the like.

[0324] In some embodiments, the thickness of the cathode collector is optionally 10µm, 11µm, 12µm, 13µm, 14µm, 15µm or any value in a range between two of these values.

[0325] The reduced thickness of the cathode collector allows for a further improvement in the energy density of the battery cell.

[0326] In some embodiments, the active cathode substance layer optionally comprises a binder. For example, the binder may comprise at least one of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), vinylidene fluoride-tetrafluoroethylene propylene terpolymer, vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer, and fluorine-containing acrylate resin.

[0327] In some embodiments, the active cathode material layer optionally comprises a conductive agent. For example, the conductive agent may comprise at least one of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dot, carbon nanotubes, graphene, and carbon nanofibers.

[0328] In some embodiments, the anode foil further comprises a conductive anode layer, wherein the conductive anode layer is located between the anode collector and the active anode substance layer on at least one side, wherein the thickness of the conductive anode layer is 0.5 µm to 2 µm; and / or the cathode foil further comprises a conductive cathode layer, wherein the conductive cathode layer is located between the active cathode substance layer and the cathode collector, wherein the thickness of the conductive cathode layer is 0.5 µm to 2 µm.

[0329] In some embodiments, the thickness of the conductive cathode layer or the conductive anode layer is optionally 0.5µm, 0.6µm, 0.7µm, 0.8µm, 0.9µm, 1.0µm, 1.1µm, 1.2µm, 1.3µm, 1.4µm, 1.5µm, 1.6µm, 1.7µm, 1.8µm, 1.9µm, 2.0µm or any value in a range between two of these values.

[0330] The conductive cathode layer and / or the conductive anode layer contribute to increasing the electronic conductivity of the electrode foil of the battery cell, leading to a further improvement in the fast charging performance of the battery cell.

[0331] In some embodiments, the conductive anode layer comprises a conductive agent, while the conductive cathode layer comprises a conductive agent and a cathode binder; wherein the conductive agent comprises one or more of superconducting carbon, conductive graphite, acetylene black, carbon black, cotinine black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers; wherein the cathode binder comprises one or more of polyvinylidene fluoride, polytetrafluoroethylene, vinylidene fluoride-tetrafluoroethylene-propylene terpolymer, vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer, polyacrylic acid, and fluorine-containing acrylate resin.

[0332] In some embodiments, the porosity of the separator is 20% to 70%.

[0333] In some embodiments, the porosity of the separator is 35% to 60%.

[0334] In some embodiments, the porosity of the separator is optionally 20%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70% or any value in a range between two of these values.

[0335] In this application, porosity refers to the percentage of the separator's pore volume that occupies its total volume. Porosity can be tested according to standard GB / T 36363-2018, Polyolefin separators for battery cells. It should be noted that the actual test procedure may deviate slightly from the standard due to differences in testing equipment, testing errors, and a minor deviation from the standard procedure itself. This deviation aims to minimize the impact of such deviations on the porosity test results and obtain a more accurate test value.

[0336] The porosity of the separator in the above area helps to further balance the energy density, fast charging performance and cycle stability of the battery cell.

[0337] In some embodiments, such as in Fig. As shown in Figure 11, the separator 123 comprises the following: a base film 1231; a first functional layer 1232 located on at least one side of the base film 1231, wherein the first functional layer 1232 comprises a first inorganic substance; a second functional layer 1233 located on a side of the first functional layer facing away from the base film 1231, wherein the second functional layer 1232 comprises a second inorganic substance and non-fluorinated polymer.

[0338] In some embodiments, the non-fluorinated polymer particles comprise an acrylate copolymer.

[0339] In some embodiments, the first inorganic substance and the second inorganic substance each independently comprise one or more of silicon oxide, aluminum oxide, boehmite, barium sulfate, calcium oxide, titanium oxide, zinc oxide, magnesium oxide, zirconium oxide and tin oxide.

[0340] The inorganic particles can improve the infiltration performance of the first and second functional layers into the electrolyte solution and their heat resistance, thereby further enhancing the fast-charging performance, cycle stability, and safety of the battery cell. The non-fluorinated polymer particles can improve the processing performance and stability of the separator, prevent separator movement within the battery cell that could lead to an internal short circuit, and thus further improve the cycle stability and safety of the battery cell.

[0341] In some embodiments, the base film comprises at least one or more layers of glass fiber, nonwoven fabric, polyethylene, polypropylene, and polyvinylidene fluoride. The base film can be, without any particular restriction, a single-layer film or a multi-layer composite film.

[0342] In some embodiments, the thickness of the base film is 4 µm to 12 µm, optionally 5 µm to 9 µm.

[0343] In some embodiments, the thickness of the base film can be 4 µm, 5 µm, 6 µm, 7 µm, 8 µm, 9 µm, 10 µm, 11 µm, 12 µm or any value in a range between two of these values.

[0344] The thickness of the base film in the area above helps to further balance the energy density, fast charging performance and cycle stability of the battery cell.

[0345] In some embodiments, such as in Fig.As shown in Figure 12, the battery cell 1 comprises a housing body 11 and a cover assembly, wherein the cover assembly is provided at at least one end of the housing body 11, wherein the housing body 11 and the cover assembly define a receiving cavity, wherein the electrode assembly is provided within the receiving cavity, wherein the thickness of the housing body 111 over a large area of ​​the battery cell is 0.1 mm to 0.5 mm.

[0346] In some embodiments, the thickness of the housing body 111 of the large area of ​​the battery cell is 0.2 mm to 0.35 mm.

[0347] In some embodiments, the thickness of the large-area battery cell casing can be 0.1 mm, 0.15 mm, 0.2 mm, 0.25 mm, 0.3 mm, 0.35 mm, 0.4 mm, 0.45 mm, 0.5 mm, or any value in the range between two of these values. The casing thickness of a large-area battery cell within the above range is advantageous for further improving the battery cell's energy density.

[0348] In some embodiments, the cover assembly comprises a first cover assembly and a second cover assembly, wherein the first cover assembly and the second cover assembly are provided at both ends of the housing body in the longitudinal direction or in the lateral direction, wherein the first cover assembly comprises a first cover plate and a first electrode clamp, while the second cover assembly comprises a second cover plate and a second electrode clamp, wherein the first electrode clamp and the second electrode clamp have opposite polarity.

[0349] In some embodiments, such as in Fig.As shown in Figure 12, the battery cell 1 comprises a first cover assembly and a second cover assembly, wherein the first cover assembly comprises a first cover plate, a first electrode terminal 131, a third electrode terminal 133, wherein the first electrode terminal 131 and the third electrode terminal 133 have opposite polarity, and wherein the second cover assembly comprises a second cover plate, a second electrode terminal 132 and a fourth electrode terminal 134, wherein the second electrode terminal 132 and the fourth electrode terminal 134 have opposite polarity.

[0350] As a result, the temperature rise of the battery cell during the charging process is reduced and the impedance of the battery cell is decreased, which contributes to an improvement in the fast charging performance, cycle life and safety performance of the battery cell.

[0351] In some embodiments, the minimum cross-sectional area of ​​the first electrode clamp and / or the second electrode clamp S is 150 mm². 2 ≤S≤1000 mm 2 .

[0352] In the present application, the minimum cross-sectional area of ​​the first electrode clamp refers to a minimum cross-sectional area in the first electrode clamp along a direction perpendicular to the direction in which the current flows, and the minimum cross-sectional area of ​​the second electrode clamp refers to a minimum cross-sectional area in the second electrode clamp along a direction perpendicular to the direction in which the current flows.

[0353] In the present application, the test for the minimum cross-sectional area of ​​the first electrode clamp and / or the second electrode clamp can be calculated based on the shape of the minimum cross-sectional area and its area calculation formula. For example, if the minimum cross-section of the electrode clamp is circular, the minimum cross-sectional area can be determined by measuring the radius of the circle, and if the minimum cross-section is square, the minimum cross-sectional area can be determined by measuring the length and width of the square.

[0354] In some embodiments, the minimum cross-sectional area of ​​the first electrode clamp and / or the second electrode clamp can be S 150 mm² 2 , 300 mm 2 , 450 mm 2 , 600 mm 2 , 750 mm 2 , 900 mm 2 , 1000 mm 2 etc. or lie within a range between the above values.

[0355] The minimum cross-sectional area of ​​the first electrode clamp and / or the second electrode clamp is in the above range, which contributes to improving the overcurrent capability of the battery cell, reducing the heat generation of the electrode clamp, reducing the internal resistance of the battery cell and thus improving the fast charging performance of the battery cell as well as the cycle stability.

[0356] In some embodiments, the volumetric energy density of the battery cell is more than 440 Wh / L and less than or equal to 530 Wh / L.

[0357] In some embodiments, the volumetric energy density of the battery cell is 450 Wh / L to 510 Wh / L.

[0358] The volumetric energy density of the battery cell can be tested using any method known in engineering. For example, the battery cell is stored at 25°C, charged to 3.65V at a constant current of 0.33C, then charged to 0.05C at a constant voltage and left to stand for 30 minutes, discharged to 2.0V at a constant current of 0.33C, and the discharge capacity at this time is recorded as A0, unit: Ah. The length, width, and height of the battery cell are measured with calipers (generally calculated from the dimensions of the battery casing, excluding the height of the electrode clamp and separator outside the casing), and the volume of the battery cell V0, unit: L, is calculated. The volumetric energy density of the battery cell is VED = (A0 × discharge platform voltage) / V0, unit: Wh / L.

[0359] In some embodiments, the volumetric energy density of the battery cell can optionally be 441 Wh / L, 450 Wh / L, 460 Wh / L, 470 Wh / L, 480 Wh / L, 490 Wh / L, 500 Wh / L, 510 Wh / L, 520 Wh / L, 530 Wh / L or any value in a range between two of these values.

[0360] The battery cell also has a high energy density to meet the demand for greater range from power-consuming devices.

[0361] In some embodiments, the injection coefficient of the battery cell is 2.2 g / Ah to 3.0 g / Ah.

[0362] The injection coefficient of a battery cell is the ratio between the mass of the electrolyte solution inside the battery cell and the battery's capacity. The injection coefficient can be tested according to any method known in the art. For example, the mass of the electrolyte solution in the battery cell can be tested as follows: Weigh the battery and record the mass as M0. Disassemble the battery cell and pour out the free electrolyte solution. Remove the internal electrode assembly and separate the cathode foil, anode foil, separator, and mechanical parts. Soak and clean the cathode foil, anode foil, separator, and mechanical parts with a dimethyl carbonate (DMC) solvent for a period of 24 to 48 hours, repeating the soaking process more than three times.Place the above cathode foil, anode foil, separator, and mechanical parts in an oven at 100°C for more than 24 hours until completely dry. Weigh the dried cathode foil, anode foil, separator, and mechanical parts, recording the mass as M1. The mass of the electrolyte solution in the battery cell is thus (M0 - M1). The injection coefficient is calculated as (M0 - M1) / the nominal capacity of the battery cell. The nominal capacity is the nominal capacity of the battery, or it is charged to 3.65 V at a charge rate of 0.33 C, then charged to 0.05 C at a constant voltage of 3.65 V, left to stand for 10 minutes, and then charged to 2.0 V at a discharge rate of 0.33 C, and the discharge capacity of the battery cell is used as the nominal capacity.

[0363] In some embodiments, the injection coefficient of the battery cell can optionally be 2.2 g / Ah, 2.3 g / Ah, 2.4 g / Ah, 2.5 g / Ah, 2.6 g / Ah, 2.7 g / Ah, 2.8 g / Ah, 2.9 g / Ah, 3.0 g / Ah or any value in a range between two of these values.

[0364] The injection coefficient within the above range can compensate for the cycle stability and energy density of the battery cells.

[0365] In some embodiments, the battery cell may include an outer casing. The outer casing can be used to encapsulate the electrode component and electrolyte described above.

[0366] In some embodiments, the outer packaging of the battery cell can be a hard casing, e.g., a hard plastic casing, an aluminum casing, a steel casing, etc. The outer packaging of the battery cell can also be a soft casing, e.g., a bag-like soft casing. The soft casing can be made of plastic, and examples of plastics include polypropylene, polybutylene terephthalate, and polybutylene succinate.

[0367] The present application does not impose any special restrictions regarding the shape of the battery cell, which can be cylindrical, square, or any other shape. For example, in Fig. Figure 12 shows a battery cell 1 with a rectangular structure as an example.

[0368] In some embodiments, such as in Fig.As shown in Figure 12, the outer packaging can comprise a housing body 11 and a cover assembly. The housing body 11 can comprise a base plate and side plates connected to the base plate, the base plate and the side plates forming a receiving cavity. The housing body 11 has an opening that communicates with the receiving cavity, and the cover assembly can serve to cover the opening to close the receiving cavity. The cathode foil, the anode foil, and the separator can be assembled into an electrode assembly by a winding or stacking process. The electrode assembly is encapsulated in the receiving cavity. The electrolyte solution is exchanged into the electrode assembly. The number of electrode assemblies contained in the battery cell 1 can be one or more, and the person skilled in the art can make the selection according to specific requirements.

[0369] In some embodiments, the battery cells can be assembled into a battery module, and the number of battery cells contained in the battery module can be one or a plurality, the exact number being selectable by the person skilled in this technical field depending on the application and capacity of the battery module.

[0370] Optionally, the battery module can also include a housing with a receiving space in which the multitude of battery cells 1 are accommodated.

[0371] In some embodiments, the battery modules described above can also be assembled into a battery pack, wherein the number of battery modules contained in the battery pack is one or more and can be selected by a person skilled in this art depending on the application and capacity of the battery pack.

[0372] A second aspect of the present application provides a battery device comprising a battery cell according to the first aspect of the present application, wherein the battery device comprises at least one of a battery module, a battery pack and an energy storage battery.

[0373] Furthermore, a third aspect of the present application provides a power-consuming device, wherein the power-consuming device comprises a battery cell according to the first aspect of the present application. The battery cell, battery module, or battery pack can be used as a power source for the power-consuming device or as an energy storage unit for the power-consuming device. The power-consuming 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.

[0374] Depending on requirements, the power-consuming device can be a battery cell, a battery module or a battery pack.

[0375] Fig. Figure 13 shows an example of the power-consuming device. The power-consuming 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 battery cell of this power-consuming device, a battery pack or battery module can be used.

[0376] Another example of such a device is a mobile phone, a tablet, a laptop, etc. The device usually needs to be light and thin and can use a battery cell as a power source.

[0377] The embodiments of the present application also provide an energy storage device which uses a battery as a power source, wherein the energy storage device may be, but is not limited to, an energy storage container, an energy storage cabinet, an energy storage power plant, an energy storage battery pack or a portable energy storage system. Example of implementation

[0378] To clarify and make the technical problems, technical solutions, and advantageous effects of the present application more understandable, the present application is described in more detail below in conjunction with exemplary embodiments. It is clear that the described exemplary embodiments represent only a subset of the exemplary embodiments of the present application and not all of them. The following description of at least one exemplary embodiment serves only for illustration and in no way constitutes a limitation of the present application and its applications. Based on the exemplary embodiments of the present application, all other exemplary embodiments that can be obtained by a person skilled in the art without inventive step fall within the scope of protection of the present application.

[0379] Unless otherwise specified in the exemplary embodiments, they correspond to the techniques or conditions described in the relevant literature or the information in the product specification. The reagents or instruments used without manufacturer information are all commercially available products. Exemplary embodiment 1(1) Production of the anode foil

[0380] The anode foil comprises an anode collector, a conductive anode layer on the anode collector and an active anode substance layer, and the anode collector is a copper foil with a thickness of 5 µm;

[0381] The conductive anode layer on the anode collector is an active substance layer formed by mixing a conductive anode compound of superconducting carbon, an anode binder of styrene-butadiene rubber (SBR), a thickening agent of sodium carboxymethylcellulose (CMC-Na), and a solvent, water. This mixture is applied to the surface of the anode collector and, after drying, is obtained by coating it. The thickness is 1 µm. The mass fraction of the conductive anode compound in the conductive anode layer is 35%, the mass fraction of the anode binder in the conductive anode layer is 60%, and the mass fraction of the thickening agent in the conductive anode layer is 5%.

[0382] The active anode substance layer comprises a first active anode substance layer and a second active anode substance layer, wherein the first active anode substance layer is located on the surface of the conductive anode layer and the second active anode substance layer is located on the surface of the first active anode substance layer;

[0383] The first active anode material layer comprises composite graphite particles, a silicon-carbon material, a conductive agent acetylene black, a binder styrene-butadiene rubber, and a thickening agent sodium carboxymethylcellulose with a mass ratio of 93:3.5:0.5:2:1, wherein the silicon content in the silicon-carbon material is 48%, the volume mean particle size Dv50 of the silicon-carbon material is 8.8 µm, and the specific surface area of ​​the silicon-carbon material is 3.4 m². 2 / g; the powder density of the silicon-carbon material at 25,000 N is 0.92 g / cm³3 , and the Dv50 of the composite graphite particles is 11.3 µm;

[0384] The second active anode layer comprises composite graphite particles, a silicon-carbon material, a conductive agent (acetylene black), a binder (styrene-butadiene rubber), and a thickener (sodium carboxymethylcellulose) in a mass ratio of 94:3.5:0.5:1:1. The silicon content of the silicon-carbon material is 48%, the volume-mean particle size (Dv50) of the silicon-carbon material is 8.8 µm, and the specific surface area of ​​the silicon-carbon material is 3.4 m². 2 / g, the powder density of the silicon-carbon material at 25,000 N is 0.92 g / cm³ 3, and the composite graphite particles have a Dv50 of 11.3 µm; The composite graphite particles comprise graphite body particles and a carbon coating layer which is coated on at least a part of the surface of the graphite body particles, wherein the carbon coating layer comprises amorphous carbon and the mass fraction of the amorphous carbon, based on the total mass of the composite graphite particles, is 3.5%.

[0385] The first anode slurry is evenly coated onto the conductive anode layer of the copper foil of the anode collector for drying; the second anode slurry is coated onto the surface of the dried first anode slurry, and the anode foil is obtained after drying and cold pressing. The ratio of the thicknesses of the first active substance layer and the second active substance layer is 1:1; the mass fraction of the silicon element, based on the total mass of the active anode substance layer, is 1.68%; and the one-sided coating weight of the active anode substance layer is 111 mg / 1540.25 mm². 2 . (2) Production of the cathode foil

[0386] The cathode foil comprises a cathode collector, a conductive cathode layer on the cathode collector and an active cathode substance layer, and the cathode collector is an aluminum foil with a thickness of 12 µm.

[0387] The conductive cathode layer on the cathode collector is an active substance layer formed by mixing a conductive cathode agent of superconducting carbon, a cathode binder of polyvinylidene fluoride (PVDF) and a solvent of N-methylpyrrolidone (NMP), and obtained by coating it onto the surface of the collector and after drying. The thickness is 1 µm, and the mass fraction of the conductive cathode agent in the conductive cathode layer is 40%, while the mass fraction of the cathode binder is 60%.

[0388] The active cathode material, the binder polyvinylidene fluoride, and the conductive agent acetylene black are mixed in a 97:2:1 ratio. Then, the solvent N-methylpyrrolidone (NMP) is added and stirred to form a cathode slurry. The active cathode material comprises lithium iron phosphate, which has a coating layer on the surface of the lithium iron phosphate particles. This coating layer consists of lithium titanium iron phosphate (Li₂FeTi(PO₄)₃) and carbon. The mass fraction of carbon is 1.12%, and the powder density of the lithium iron phosphate material at 30,000 N is 2.65 g / cm³. 3 .

[0389] The conductive cathode slurry is applied evenly to the aluminum foil of the cathode collector, and after drying, the conductive cathode layer is obtained. The cathode slurry is then applied evenly to the conductive cathode layer, dried, and cold-pressed to obtain the cathode foil. The one-sided coating weight of the active cathode substance layer is 270 mg / 1540.25 mm². 2 . (3) Preparation of the electrolyte solution

[0390] The electrolyte solution comprises a solvent, a lithium-containing electrolyte salt, and an additive.

[0391] The solvent comprises ethyl acetate with a mass fraction of 22% and methyl acetate with a mass fraction of 19.7% (first solvent), vinyl carbonate with a mass fraction of 27.3% and dimethyl carbonate with a mass fraction of 6.7% (second solvent), wherein the mass fraction of each component in the solvent is calculated on the basis of the total mass of the electrolyte solution;

[0392] Based on the total mass of the electrolyte solution, the total mass content of the additive is 9.3%, wherein the additive is vinylidene carbonate VC, fluoroethylene carbonate FEC, vinylidene sulfite ES and lithium difluorooxalate borate LiDFOB in a mass ratio of 4:2.5:2:0.8;

[0393] Based on the total mass of the electrolyte solution, the lithium-containing electrolyte salt comprises lithium bis(fluorosulfonyl)imide (LiFSI) at a mass fraction of 5% and lithium hexafluorophosphate (LiPF6) at a mass fraction of 10%. The viscosity of the electrolyte solution at room temperature is 2.58 mPa·s. (4) Production of the separator

[0394] The separator comprises a base film and a functional layer, wherein the base film comprises a polyethylene film layer with a thickness of 5 µm and the separator has a porosity of 42%;

[0395] The functional layer comprises a first functional layer and a second functional layer, wherein the first functional layer is a film layer formed by coating aluminum oxide particles and a binder polyvinylidene fluoride on one side of the base film with a thickness of 1 µm, and the average particle size of the aluminum oxide particles is 10 nm; the second functional layer is a film layer formed by coating composite particles of polyacrylate and calcium oxide particles dispersed on the polyacrylate on the surface of the first functional layer, with a thickness of 5 µm, the average particle size of the calcium oxide particles is 10 nm. (5) Production of the battery cell

[0396] The cathode foil, separator, and anode foil are stacked in a row, with the separator positioned between the cathode and anode foils for insulation. Electrode tabs are located at both ends of the collector section, extending along the length of the electrode assembly. The ratio between the width of the cathode and anode tabs and the width of the collector is 1 / 3, resulting in a stacked electrode assembly. This assembly is then inserted into the housing, which is fitted with a cathode and anode clamp. After drying, the electrolyte solution is injected at a rate of 2.45 g / Ah. Following vacuum encapsulation, settling, forming, shaping, and other processes, a battery cell is obtained.The active cathode layer measures 630 mm in length along the electrode assembly, with OH1 measuring 4 mm. The active cathode layer measures 95 mm in width along the electrode assembly, with OH2 measuring 3 mm. The battery housing is made of aluminum and has a thickness of 0.35 mm. The energy density of the battery cell is 460 Wh / L. The density of the active anode layer is 1.26 g / cm³. 3 , and the density of the active cathode substance layer is 2.75 g / cm³ 3 . Example 2-3

[0397] The manufacturing process of embodiments 2 to 3 is essentially the same as that of embodiment 1, with the difference that the mass fraction of the silicon element in the first active anode substance layer and in the second active anode substance layer is adjusted, the mass of the composite graphite particles is changed accordingly, and the one-sided coating weight of the active cathode substance layer is adjusted accordingly, as shown in Tables 1 and 2. Example 4-5

[0398] The manufacturing process of embodiments 4 to 5 is essentially the same as that of embodiment 1, with the difference that the one-sided coating weight of the active anode substance layer and the one-sided coating weight of the active cathode substance layer are adjusted accordingly, as shown in Tables 1 and 2. Example 6-9

[0399] The manufacturing process of embodiments 6 to 9 is essentially the same as that of embodiment 1, with the difference that the mass fraction of the first solvent and the second solvent is adjusted and the viscosity of the electrolyte solution is changed accordingly, as shown in Tables 1 and 2. Example 10

[0400] The manufacturing process of embodiment 10 is essentially the same as that of embodiment 1, with the difference that the type of lithium-containing electrolyte salt in the electrolyte solution is adapted and the viscosity of the electrolyte solution is changed accordingly, as shown in Tables 1 and 2. Example 11-14

[0401] The manufacturing process of embodiments 11 to 14 is essentially the same as that of embodiment 1, with the difference that the mass fraction of the lithium-containing electrolyte salt in the electrolyte solution and the amount of additive added are adjusted, the amount of solvent is adjusted accordingly, and the viscosity of the electrolyte solution is changed accordingly, as shown in Tables 1 and 2. Comparison example 1-6

[0402] The manufacturing process of comparative examples 1 to 6 is essentially the same as that of embodiment 1, with the difference that some parameters in the battery cell are adjusted, as listed in Tables 1 and 2. Test procedure: 1. Fast charging performance

[0403] At 30°C, the battery cell was cycled 200 times according to the following charge and discharge strategies, then fully charged to 100% SOC according to the corresponding charge strategies, the anode foil was removed, the anode foil was opened, the area of ​​lithium precipitation (grey-white area) was observed and the area of ​​lithium precipitation was measured, and the degree of lithium precipitation was as follows:

[0404] No lithium precipitation: The percentage of the area with lithium precipitation in the area of ​​the active anode substance layer is < 0.05%.

[0405] Slight lithium precipitation: The percentage of the area with lithium precipitation in the area of ​​the active anode substance layer is < 2%.

[0406] Severe lithium precipitation: The percentage of the area with lithium precipitation in the area of ​​the active anode substance layer is ≥ 2%.

[0407] Charging the battery cell: The charging process includes the following steps:

[0408] Charging from 0% SOC to 40% SOC at a constant current of 5.0 C; charging from 40% SOC to 45% SOC at a constant current of 4.6 C; charging from 45% SOC to 50% SOC at a constant current of 4.3 C; charging from 50% SOC to 55% SOC at a constant current of 4.0 C; charging from 55% SOC to 60% SOC at a constant current of 3.7 C; charging from 60% SOC to 65% SOC at a constant current of 3.4 C; charging from 65% SOC to 70% SOC at a constant current of 3.1 C; charging from 70% SOC to 75% SOC at a constant current of 2.9 C; Charging from 75% SOC to 80% SOC at a constant current of 2.7C; charging from 80% SOC to 85% SOC at a constant current of 1.8C; charging from 85% SOC to 90% SOC at a constant current of 1.3C; charging from 90% SOC to 95% SOC at a constant current of 0.7C; charging from 95% SOC to 98% SOC at a constant current of 0.33C;Charging from 98% SOC to 100% SOC at a constant current of 0.1C.;

[0409] The cut-off voltage for the last charging step in the above charging steps is 3.65 V.

[0410] The discharge strategy is as follows: discharge with constant current at 0.33C up to a cut-off voltage of, for example, 2.0 V.

[0411] In the above-described charging and discharging test of the battery cell, the battery cell can be installed in a battery device, and the desired charging and discharging strategy can be controlled by the battery management system for the test. 2. Volumetric energy density

[0412] The battery cell is stored at 25°C, charged to 3.65V at a constant current of 0.33C, then charged to 0.05C at a constant voltage and left to stand for 30 minutes, discharged to 2.0V at a constant current of 0.33C, and the discharge capacity at this time is recorded as A0, unit: Ah; the length, width, and height of the battery cell are measured with calipers (generally calculated from the dimensions of the battery casing, excluding the height of the electrode clamp and separator outside the casing), and the volume of the battery cell V0, unit L, is calculated; the volumetric energy density of the battery cell VED=(A0×discharge platform voltage) / V0, unit Wh / L. 3. Cycle performance

[0413] At 60°C, the battery cell is charged to the charge cutoff voltage of 3.6V at a constant current of 0.8C, then charged to the charge cutoff voltage of 3.65V at a constant current of 0.1C and left for 30 minutes; discharged to 3.1V at a constant current of 1C and left for 30 minutes. This is one charge / discharge cycle. Repeat the above charge / discharge cycle steps until the capacity maintenance rate of the cycle (i.e., C) is reached. n (C0 × 100%) is 80%, and the number of cycles is recorded. The higher the number of cycles, the better the cycle performance of the battery cell. Test result

[0446] Table 1 number Active anode substance layer Battery cell Mass fraction of the material is silicon-based Mass fraction of the silicon element Single-sided coating weight (mg / 1540.25mm²) 2 ) Fast charging performance Volumetric energy density (Wh / L) Cycle performance at 60°C / cycles Example 1 3,50% 1,68% 111 No lithium precipitation 460 822 Example 2 1,04% 0,5% 111 No lithium precipitation 443 1031 Example 3 10,4% 5% 111 Light lithium precipitation 505 735 Example 4 3,50% 1,68% 80 No lithium precipitation 446 843 Example 5 3,50% 1,68% 150 Light lithium precipitation 475 804 Comparative example 1 0% 0% 111 No lithium precipitation 436 1187 Comparative example 2 15% 7,2% 111 Light lithium precipitation 536 421 Comparative example 3 3,50% 1,68% 60 No lithium precipitation 437 853 Comparative example 4 3,50% 1,68% 170 Heavy lithium precipitation 484 737

[0414] According to the comparison between the embodiments of the present application and the comparative examples, the one-sided coating weight of the active anode substance layer in the battery cell is 80 mg / 1540.25 mm². 2up to 150 mg / 1540.25 mm 2 , and based on the total mass of the active anode substance layer, the mass fraction of the silicon element is 0.5% to 5%, and the viscosity of the electrolyte solution at room temperature is 2.3 mPa-s to 3.5 mPa-s, which takes into account the improvement of the energy density, fast charging performance and cycle stability of the battery cell and allows for a comprehensive improvement in battery performance.

[0415] As can be seen from the comparison of embodiments 1 and 3 with embodiment 2, the mass fraction of the silicon element, based on the total mass of the active anode substance layer, is 1.6% to 5%, and the battery cell has excellent fast charging performance and cycle stability, while the volumetric energy density is further improved.

[0416] As can be seen from the comparison of embodiments 1 and 5 with embodiment 4, the one-sided coating weight of the active anode substance layer is 110 mg / 1540.25 mm². 2 up to 150 mg / 1540.25 mm 2 , and the battery cell has excellent fast charging performance and cycle stability, while further improving energy density.

[0417] As can be seen from the exemplary embodiments, the electrolyte solution comprises a first solvent with a viscosity η of 0.3 mPa-s to 0.6 mPa-s, and the battery cell has excellent energy density, fast charging performance and cycle stability.

[0418] As can be seen from embodiments 1, 6 to 9, the mass fraction of the first solvent is 8% to 60% and of the second solvent is 18% to 75%, based on the total mass of the electrolyte solution, and the battery cell has excellent energy density, fast charging performance and cycle stability.

[0419] As can be seen from the comparison of embodiments 1, 8 and 9 with embodiment 7, the mass fraction of the first solvent, based on the total mass of the electrolyte solution, is 30% to 60%, and the battery cell has excellent volumetric energy density and cycle stability, while the fast charging performance is further improved.

[0420] As can be seen from the comparison of embodiments 1 and 10, the lithium-containing electrolyte salt comprises LiFSI, which contributes to a further reduction in the viscosity of the electrolyte solution, and the fast charging performance and cycle stability of the battery cell are further improved.

[0421] As can be seen from embodiments 1, 11 and 12, the mass fraction of the lithium-containing electrolyte salt in the electrolyte solution is 10% to 18%, and the battery cell has excellent energy density, fast charging performance and cycle stability.

[0422] As can be seen from embodiments 1, 11 and 12, the mass fraction of the added amount of the carbonate additive, based on the total mass of the electrolyte solution, is 3% to 8%, and the battery cell has excellent energy density, fast charging performance and cycle stability.

[0423] As can be seen from embodiments 1 and 13, the mass fraction of the sulfur-containing additive is 0.5% to 2% and of the lithium salt-like additive is 0.2% to 1%, based on the total mass of the electrolyte solution, and the battery cell has excellent energy density, fast charging performance and cycle stability.

[0424] As can be seen from the comparison of embodiment 14 with embodiment 1, the electrolyte solution comprising a fluorobenzene additive contributes to further improving the cycle stability and fast charging performance of the battery cell.

[0425] It should be noted that this disclosure is not limited to the embodiments mentioned above. The embodiments mentioned above are only examples, and embodiments within the scope of the technical solution of this disclosure that have essentially the same composition as the technical idea and have the same effect are included within the technical scope of this disclosure. Furthermore, within the scope of this disclosure, it also includes other ways of constructing the embodiments by combining some of the constituent elements of the embodiments and applying various deformations to the embodiments, which a person skilled in the art can imagine without departing from the subject matter of this disclosure. QUOTES INCLUDED IN THE DESCRIPTION

[0000] This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited non-patent literature

[0000] Standard GB / T 10247-2008

[0148] GB / T19587-2017

[0164] Standard JY / T020-2002

[0194]

Claims

[1] Battery cell, characterized by , that it comprises an electrode assembly and an electrolyte solution, wherein the electrode assembly comprises a cathode foil, an anode foil and a separator, the separator being located between the cathode foil and the anode foil, the cathode foil comprising a cathode collector and an active cathode substance layer provided on at least one side of the cathode collector, the active cathode substance layer comprising an active cathode material, the active cathode material comprising a lithium-containing phosphate with an olivine structure; wherein the anode foil comprises an anode collector and an active anode substance layer provided on at least one side of the anode collector, wherein the one-sided coating weight of the active anode substance layer is 80 mg / 1540.25 mm 2 up to 150 mg / 1540.25 mm 2 amounts; wherein the active anode substance layer comprises an active anode material, wherein the active anode material is a silicon-based material, wherein the mass fraction of the silicon element, based on the total mass of the active anode material layer, is 0.5% to 5%; where the viscosity of the electrolyte solution at room temperature is 2.3 mPa-s and 3.5 mPa-s. [2] Battery cell according to claim 1, characterized by , that the one-sided coating weight of the active anode substance layer is 110 mg / 1540.25 mm 2 up to 150 mg / 1540.25 mm 2 amounts. [3] Battery cell according to claim 1 or 2, characterized by , that the mass fraction of the silicon element, relative to the total mass of the active anode substance layer, is 1.6% to 5%. [4] Battery cell according to any one of claims 1 to 3, characterized bythat the silicon-based material comprises one or more of monomeric silicon, silicon-carbon material, silicon-oxygen material, silicon-nitrogen material and a silicon alloy, optionally silicon-carbon material. [5] Battery cell according to claim 4, characterized by that the silicon-carbon material meets at least one of the following conditions: (1) the mass fraction of the carbon element in the silicon-carbon material is 40% to 80%, based on the total mass of the silicon-carbon material. (2) the volume mean particle size Dv50 of the silicon-carbon material is 5.0 µm to 12.5 µm; (3) the specific surface area of ​​the silicon-carbon material is 3.1 m² 2 / g up to 3.6 m 2 / G; (4) The powder density of the silicon-carbon material at 25,000 N is 0.7 g / cm³. 3 up to 1.2 g / cm³ 3 . [6] Battery cell according to any one of claims 1 to 5, characterized by that the active anode material further comprises a carbon-based material. [7] Battery cell according to claim 6, characterized by that the carbon-based material comprises one or more of graphite and hard carbon, optionally graphite. [8] Battery cell according to claim 6 or 7, characterized by , that the carbon-based material comprises composite graphite particles, wherein the composite graphite particles comprise graphite body particles and a carbon coating layer applied to at least a part of the surface of the composite graphite particles, wherein the composite graphite particles comprise secondary particles, and wherein the carbon coating layer comprises amorphous carbon. [9] Battery cell according to claim 8, characterized by , that the mass fraction of amorphous carbon, relative to the total mass of the composite graphite particles, is 2% to 5%. [10] Battery cell according to claim 8 or 9, characterized by , that the volume-average particle size Dv50 of the composite graphite particles is 8.5 µm to 16.5 µm. [11] Battery cell according to any one of claims 1 to 10, characterized by that the density of the active anode substance layer is 1.10 g / cm³ 3 up to 1.50 g / cm² 3 amounts. [12] Battery cell according to any one of claims 1 to 11, characterized by , that the active anode substance layer has a dimension of 200 mm to 650 nm along the longitudinal direction of the electrode assembly. [13] Battery cell according to any one of claims 1 to 12, characterized by , that the electrolyte solution comprises a first solvent, wherein the first solvent has a viscosity η of 0.3 mPa-s to 0.6 mPa-s at room temperature, wherein the mass fraction of the first solvent, based on the total mass of the electrolyte solution, is 8% to 60%. [14] Battery cell according to claim 13, characterized by, that the mass fraction of the first solvent, based on the total mass of the electrolyte solution, is 30% to 60%. [15] Battery cell according to claim 13 or 14, characterized by that the first solvent comprises a carboxylic acid ester solvent. [16] Battery cell according to claim 15, characterized by that the carboxylic acid ester solvent has a general structural formula of R ' -COO-R", where R , comprising one or more of a hydrogen atom, a halogen atom, a C1 to C5 alkyl group and a C1 to C5 haloalkyl group, wherein R ,, comprising one or more of a C1 to C5 alkyl group and a C1 to C5 alkyl halide group. [17] Battery cell according to claim 15 or 16, characterized by , that the carboxylic acid ester solvent comprises one or more of methyl formate, methyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, propyl propionate, methyl butyrate, ethyl butyrate. [18] Battery cell according to any one of claims 1 to 17, characterized by , that the electrolyte solution further comprises a second solvent, wherein the second solvent comprises a carbonate solvent, the carbonate solvent comprising one or more of vinyl carbonate, propylene carbonate, butylene carbonate, dimethyl carbonate, diethyl carbonate and methylene carbonate. [19] Battery cell according to claim 18, characterized by , that the mass fraction of the carbonate solvent, based on the total mass of the electrolyte solution, is 18% to 75%. [20] Battery cell according to any one of claims 1 to 19, characterized by that the electrolyte solution comprises a lithium-containing electrolyte salt, wherein the mass fraction of the lithium-containing electrolyte salt in the electrolyte solution, based on the total mass of the electrolyte solution, is 10% to 18%. [21] Battery cell according to claim 20, characterized bythat the lithium-containing electrolyte salt comprises one or more of lithium bis(fluorosulfonyl)imide LiFSI and lithium hexafluorophosphate LiPF6. [22] Battery cell according to claim 21, characterized by , that the mass fraction of lithium bis(fluorosulfonyl)imide LiFSI, based on the total mass of the electrolyte solution, is 4% to 8%. [23] Battery cell according to any one of claims 1 to 22, characterized by , that the electrolyte solution further comprises an additive, wherein the additive comprises one or more of a carbonate additive, a sulfur-containing additive, a lithium salt-like additive and a fluorobenzene additive. [24] Battery cell according to claim 23, characterized by , that the carbonate additive comprises one or more of vinylidene carbonate and a vinyl carbonate derivative, wherein the vinyl carbonate derivative comprises a compound represented in formula, wherein R1, R2, R3, R4 each independently comprise a hydrogen atom, a halogen atom, a C1 to C5 alkyl group and a C1 to C5 haloalkyl group, and wherein R1, R2, R3, R4 are not simultaneously hydrogen atoms, wherein the carbonate additive may optionally comprise one or more of vinylidene carbonate and fluorinated vinyl carbonate; wherein the sulfur-containing additive comprises one or more of vinyl sulfate, vinyl bisulfate, 1,3-propanesulfonate lactone, butyl sulfite, vinyl sulfite and methylenedisulfonylmethylene; wherein the lithium salt-like additive comprises one or more of lithium difluorophosphate, lithium difluorooxalate borate, lithium tetrafluoroborate, lithium bisoxalate borate; and / or wherein the fluorobenzene additive comprises one or more of a fluorobenzene and its derivatives. [25] Battery cell according to claim 23 or 24, characterized by, that the mass fraction of the carbonate additive, based on the total mass of the electrolyte solution, is 3% to 8%. [26] Battery cell according to any one of claims 23 to 25, characterized by , that the mass fraction of vinylidene carbonate, based on the total mass of the electrolyte solution, is 2% to 5%. [27] Battery cell according to any one of claims 23 to 26, characterized by , that the mass fraction of the vinyl carbonate derivative in the electrolyte solution, based on the total mass of the electrolyte solution, is 0% to 4%. [28] Battery cell according to any one of claims 23 to 26, characterized by , that the mass fraction of the vinyl carbonate derivative in the electrolyte solution, based on the total mass of the electrolyte solution, is 1.5% to 3.5%. [29] Battery cell according to any one of claims 23 to 28, characterized by , that the mass fraction of the sulfur-containing additive, based on the total mass of the electrolyte solution, is 0% to 2%. [30] Battery cell according to any one of claims 23 to 28, characterized by , that the mass fraction of the sulfur-containing additive, based on the total mass of the electrolyte solution, is 0.5% to 2%. [31] Battery cell according to any one of claims 23 to 30, characterized by , that the mass fraction of the lithium salt-like additive, based on the total mass of the electrolyte solution, is 0% to 1%. [32] Battery cell according to any one of claims 23 to 30, characterized by , that the mass fraction of the lithium salt-like additive, based on the total mass of the electrolyte solution, is 0.2% to 1%. [33] Battery cell according to any one of claims 23 to 32, characterized by , that the mass content of the fluorobenzene additive, based on the total mass of the electrolyte solution, is 0.1% to 1%. [34] Battery cell according to any one of claims 1 to 33, characterized by, that along the longitudinal direction of the electrode assembly the dimension of the active anode substance layer is larger than the dimension of the active cathode substance layer, wherein the difference between the dimension of the active anode substance layer and the dimension of the active cathode substance layer is OH1; wherein along the width direction of the electrode assembly the dimension of the active anode substance layer is larger than the dimension of the active cathode substance layer, and wherein the difference between the dimension of the active anode substance layer and the dimension of the active cathode substance layer is OH2; where OH1 is 1.0 mm to 4.0 mm; and / or where OH2 is 1.0 mm to 3.0 mm. [35] Battery cell according to claim 34, characterized by , that OH1 is greater than or equal to OH2. [36] Battery cell according to any one of claims 1 to 35, characterized bythat the cathode collector comprises a cathode collector section and a cathode tab, wherein the cathode tab is provided at at least one end in the extension direction of the cathode collector section along the longitudinal direction of the electrode assembly or at at least one side in the extension direction along the width direction of the electrode assembly; and / or that the anode collector comprises an anode collector section and an anode tab, wherein the anode tab is provided at at least one end in the extension direction of the anode collector section along the longitudinal direction of the electrode assembly or at at least one side in the extension direction along the width direction of the electrode assembly. [37] Battery cell according to claim 36, characterized bythat the active anode substance layer has a dimension of more than 500 mm along the longitudinal direction of the electrode assembly, wherein the anode tab is provided at both ends in the extension direction of the anode collector section along the longitudinal direction of the electrode assembly or at least on one side in the extension direction along the width direction of the electrode assembly. [38] Battery cell according to claim 36 or 37, characterized by , that the cathode tab is provided at at least one end in the extension direction of the cathode collector section along the longitudinal direction of the electrode assembly, wherein the ratio of the width of the cathode tab to the width of the cathode collector section is 0.25 to 1; and / or wherein the ratio of the width of the anode tab to the width of the anode collector section is 0.25 to 1. [39] Battery cell according to claim 36 or 37, characterized by, that the cathode tab is provided on at least one side in the extension direction of the cathode collector section along the width direction of the electrode assembly, wherein the ratio of the width of the cathode tab to the length of the cathode collector section is 0.25 to 1; and / or wherein the ratio of the width of the anode tab to the length of the anode collector section is 0.25 to 1. [40] Battery cell according to any one of claims 1 to 39, characterized by , that the active cathode material comprises the following: a lithium-containing phosphate with an olivine structure, and a coating layer, wherein the coating layer is located on at least a part of the surface of the lithium-containing phosphate, and the coating layer comprises a carbon element. [41] Battery cell according to claim 40, characterized by, that the mass fraction of the carbon element, based on the total mass of the active cathode material, is 0.8% to 2.3%. [42] Battery cell according to claim 40 or 41, characterized by , that the coating layer further comprises a component represented in Formula II, Li 3-d1 Fe 2-d1 M1 d1 (PO m1 ) n1 Formula II where 0≤d1≤1, 3 <m1<5, 2≤n1≤4, wobei M1 eines oder mehrere der Elemente Ti, Zr, Hf, Ge, Sn umfasst, wobei M1 optional die Wertigkeit +4 aufweist. [43] Battery cell according to any one of claims 40 to 42, characterized by , that the lithium-containing phosphate includes a component represented in formula III, Li x1 A y1 Me a1 M b1 P 1-c1 X c1 Y z1 Formula III where 0.5 ≤ x1 ≤ 1.3, 0 ≤ y1 ≤ 1.3, 0.9 ≤ x1 + y1 ≤ 1.3; 0.9 ≤ a1 ≤ 1.5, 0 ≤ b1 ≤ 0.5, 0.9 ≤ a1 + b1 ≤ 1.5; 0 ≤ c1 ≤ 0.5; where 3 ≤ z1 ≤ 5; where A comprises one or more of the elements Na, K, and Mg; where Me comprises one or more of the elements Mn, Fe, Co, and Ni; where M comprises one or more of the elements B, Mg, Al, Si, P, S, Ca, Sc, Ti, V, Cr, Cu, Zn, Sr, Y, Zr, Nb, Mo, Cd, Sn, Sb, Te, Ba, Ta, W, Yb, La, and Ce; where X comprises one or more of the elements S, Si, Cl, B, C, N, P; where Y comprises one or more of the elements O, F. [44] Battery cell according to any one of claims 1 to 43, characterized by , that the active cathode material comprises one or more of lithium iron phosphate, lithium manganese phosphate, lithium ferromanganese phosphate, lithium nickel phosphate and lithium cobalt phosphate, as well as a modified form of one of the above substances, wherein the modified form comprises one or more of a doped modified form and a coated modified form. [45] Battery cell according to any one of claims 1 to 44, characterized by , that the powder density of the active cathode material at 30,000 N is 2.45 g / cm³ 3 up to 2.75 g / cm³ 3 amounts. [46] Battery cell according to any one of claims 1 to 45, characterized by , that the density of the active cathode substance layer is 2.5 g / cm³ 3 up to 2.83 g / cm³ 3 amounts. [47] Battery cell according to any one of claims 1 to 46, characterized by , that the one-sided coating weight of the active cathode substance layer is 200mg / 1540.25mm 2 up to 370 mg / 1540.25 mm 2 amounts. [48] ​​Battery cell according to any one of claims 1 to 47, characterized by , that the thickness of the cathode collector is 10 µm to 15 µm. [49] Battery cell according to any one of claims 1 to 48, characterized bythat the anode foil further comprises a conductive anode layer, wherein the conductive anode layer is located between the anode collector and the active anode substance layer on at least one side, wherein the thickness of the conductive anode layer is 0.5 µm to 2 µm; and / or that the cathode foil further comprises a conductive cathode layer, wherein the conductive cathode layer is located between the active cathode substance layer and the cathode collector, wherein the thickness of the conductive cathode layer is 0.5 µm to 2 µm. [50] Battery cell according to claim 49, characterized by, that the conductive anode layer comprises a conductive agent, while the conductive cathode layer comprises a conductive agent and a cathode binder, wherein the conductive agent comprises one or more of superconducting carbon, conductive graphite, acetylene black, carbon black, cotinine black, carbon dots, carbon nanotubes, graphene and carbon nanofibers; wherein the cathode binder comprises one or more of polyvinylidene fluoride, polytetrafluoroethylene, vinylidene fluoride-tetrafluoroethylene propylene terpolymer, vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer, polyacrylic acid and fluorine-containing acrylate resin. [51] Battery cell according to any one of claims 1 to 50, characterized by that the porosity of the separator is between 20% and 70%. [52] Battery cell according to claim 51, characterized by that the porosity of the separator is between 35% and 60%. [53] Battery cell according to any one of claims 1 to 52, characterized by , that the separator includes the following: a basic film; a first functional layer located on at least one side of the base film, wherein the first functional layer comprises a first inorganic substance; a second functional layer located on a side of the first functional layer facing away from the base film, wherein the second functional layer comprises a second inorganic substance and a non-fluorinated polymer. [54] Battery cell according to claim 53, characterized by that the non-fluorinated polymer comprises an acrylate copolymer. [55] Battery cell according to claim 53 or 54, wherein the first inorganic substance and the second inorganic substance each independently comprise one or more of silicon oxide, aluminum oxide, boehmite, barium sulfate, calcium oxide, titanium oxide, zinc oxide, magnesium oxide, zirconium oxide and tin oxide. [56] Battery cell according to any one of claims 53 to 55, characterized by , that the thickness of the base film is 4 µm to 12 µm. [57] Battery cell according to any one of claims 53 to 56, characterized by , that the thickness of the base film is 5 µm to 9 µm. [58] Battery cell according to any one of claims 1 to 57, characterized by, that the battery cell comprises a housing body and a cover assembly, wherein the cover assembly is provided at at least one end of the housing body, wherein the housing body and the cover assembly define a receiving cavity, wherein the electrode assembly is provided within the receiving cavity, wherein the thickness of the housing body over a large area of ​​the battery cell is 0.1 mm to 0.5 mm. [59] Battery cell according to claim 58, characterized by , that the thickness of the casing body over a large area of ​​the battery cell is 0.2 mm to 0.35 mm. [60] Battery cell according to claim 58 or 59, characterized by, that the cover assembly comprises a first cover assembly and a second cover assembly, wherein the first cover assembly and the second cover assembly are provided at both ends of the housing body in the longitudinal direction or in the width direction, wherein the first cover assembly comprises a first cover plate and a first electrode clamp, while the second cover assembly comprises a second cover plate and a second electrode clamp, wherein the first electrode clamp and the second electrode clamp have opposite polarity. [61] Battery cell according to claim 60, characterized by , that a minimum cross-sectional area of ​​the first electrode clamp and / or the second electrode clamp is S and 150 mm 2 ≤S≤1000 mm 2 fulfilled. [62] Battery cell according to any one of claims 1 to 61, characterized bythat the volumetric energy density of the battery cell is more than 440 Wh / L and less than or equal to 530 Wh / L. [63] Battery cell according to claim 62, characterized by , that the volumetric energy density of the battery cell is 450 Wh / L to 510 Wh / L. [64] Battery cell according to any one of claims 1 to 63, characterized by , that the injection coefficient of the battery cell is 2.2 g / Ah to 3.0 g / Ah. [65] Battery device, characterized by that it comprises a battery cell according to one of claims 1 to 64, wherein the battery device is at least one battery module, one battery pack or one energy storage battery. [66] Power-consuming device, characterized by that it comprises a battery device according to claim 65. [67] Energy storage device, characterized bythat it comprises a battery device according to claim 65, wherein the battery device is used for storing electrical energy.

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