Battery cell, battery device, and electric device

Abstract

The present application discloses a battery cell, a battery device, and an electric device. The battery cell comprises a positive electrode sheet and a negative electrode sheet; in the positive electrode sheet, a positive electrode active material layer comprises a positive electrode active material, the positive electrode active material comprises a nickel cobalt manganese metal oxide, and on the basis of the total molar mass of nickel, cobalt and manganese in the nickel cobalt manganese metal oxide, the molar proportion of nickel in the nickel cobalt manganese metal oxide is 80%-96%; or the positive electrode active material comprises a nickel cobalt aluminum metal oxide, and on the basis of the total molar mass of nickel, cobalt and aluminum in the nickel cobalt aluminum metal oxide, the molar proportion of nickel in the nickel cobalt aluminum metal oxide is 80%-96%; in the negative electrode sheet, a negative electrode active material layer comprises a negative electrode active material, and the negative electrode active material comprises graphite and a silicon-containing material; and on the basis of the total mass of the negative electrode active material, the mass proportion of silicon in the negative electrode active material is 0.1%-10%, and the thickness of a negative electrode current collector is 3%-8% of the total thickness of the negative electrode sheet. Therefore, a battery can have both a higher energy density and a longer service life.

Description

Battery cell, battery device and electric device

[0001] Priority information

[0002] This application claims priority to and the benefit of Chinese Patent Application No. 202411161595.9, filed on August 22, 2024, and is incorporated herein by reference in its entirety. TECHNICAL FIELD

[0003] The present application belongs to the technical field of batteries, and specifically relates to a battery cell, a battery device and an electric device. BACKGROUND

[0004] Secondary batteries are not only applied to energy storage power systems such as hydroelectric, thermal, wind and solar power stations, but also widely used in electric vehicles such as electric bicycles, electric motorcycles, electric cars, electric transportation tools, military equipment, aerospace and other fields. With the development of the current society, people have higher and higher requirements for batteries, such as high energy density or long service life. SUMMARY

[0005] The present application provides a battery cell, aiming to obtain high energy density and long service life.

[0006] In order to achieve the above-mentioned purpose, in the first aspect of the present application, a battery cell is provided, which comprises a positive electrode sheet and a negative electrode sheet:

[0007] The positive electrode sheet comprises a positive electrode current collector and a positive electrode active material layer arranged on at least one side of the positive electrode current collector, the positive electrode active material layer comprising a positive electrode active material, and the negative electrode sheet comprises a negative electrode current collector and a negative electrode active material layer arranged on at least one side of the negative electrode current collector, the negative electrode active material layer comprising a negative electrode active material, wherein,

[0008] The positive electrode active material comprises a nickel-cobalt-manganese metal oxide, and the mole percentage of nickel element in the nickel-cobalt-manganese metal oxide is 80% to 96% based on the total mole amount of nickel-cobalt-manganese elements in the nickel-cobalt-manganese metal oxide, or

[0009] The positive electrode active material comprises a nickel-cobalt-aluminum metal oxide, and the mole percentage of nickel element in the nickel-cobalt-aluminum metal oxide is 80% to 96% based on the total mole amount of nickel-cobalt-aluminum elements in the nickel-cobalt-aluminum metal oxide.

[0010] The negative electrode active material comprises graphite and a silicon-containing material, and the mass percentage of silicon element in the negative electrode active material is 0.1% to 10% based on the total mass of the negative electrode active material, and the thickness of the negative electrode current collector is 3% to 8% of the total thickness of the negative electrode sheet.

[0011] The battery cell of the first aspect of the present application has at least the following beneficial effects: by comprehensively regulating the nickel content in the high-nickel positive electrode active material system and the amount of silicon-containing material in the negative electrode plate to meet the given range respectively, and adjusting the thickness ratio of the current collector in the negative electrode plate to be within the given range, the risk of damage or disconnection of the electrode plate due to repeated expansion during long-term cycling of the battery cell can be reduced while improving the energy density of the battery. Further, the battery can have both high energy density and long service life.

[0012] In some embodiments of the present application, the mass percentage of silicon in the negative electrode active material is 0.5% to 9.5%, or optionally 2% to 9.5%, based on the total mass of the negative electrode active material. This is beneficial for balancing high initial efficiency and good cycle stability on the basis of improving the energy density of the battery.

[0013] In some embodiments of the present application, the thickness of the negative electrode current collector is 4% to 7% of the total thickness of the negative electrode plate. This can further balance the cycle performance and energy density of the battery, prolonging the service life of the battery.

[0014] In some embodiments of the present application, the thickness of the positive electrode current collector is 7.5% to 15%, or optionally 10% to 13.5%, of the total thickness of the positive electrode plate. This can further balance the cycle performance and energy density of the battery, prolonging the service life of the battery.

[0015] In some embodiments of the present application, the positive electrode active material includes nickel-cobalt-manganese metal oxide, and the molar percentage of nickel in the nickel-cobalt-manganese metal oxide is 83% to 91%, based on the total molar amount of nickel, cobalt and manganese in the nickel-cobalt-manganese metal oxide; or the positive electrode active material includes nickel-cobalt-aluminum metal oxide, and the molar percentage of nickel in the nickel-cobalt-aluminum metal oxide is 83% to 91%, based on the total molar amount of nickel, cobalt and aluminum in the nickel-cobalt-aluminum metal oxide. This is beneficial for further improving the cycle performance of the battery on the basis of improving the energy density of the battery, prolonging the service life of the battery.

[0016] In some embodiments of the present application, the silicon-containing material includes silicon-oxygen material and / or silicon-carbon material.

[0017] In some embodiments of the present application, the mass percentage of silicon in the negative electrode active material is 2% to 6%, or optionally 3% to 5%, based on the total mass of the negative electrode active material. This is beneficial for balancing high initial efficiency and cycle stability on the basis of improving the energy density of the battery.

[0018] In some embodiments of the present application, the silicon-containing material further comprises a metal element, the metal element comprising one or more of Na, Li, Ti, Fe, Co. Thereby, the energy density and electrochemical performance of the battery can be further improved.

[0019] In some embodiments of the present application, the mass of the metal element is 0.1% to 0.6% of the mass of the silicon element. Thereby, the energy density and electrochemical performance of the battery can be further improved.

[0020] In some embodiments of the present application, at least part of the surface of the silicon-containing material comprises a carbon coating layer. Thereby, the structural stability of the silicon-containing material during charge and discharge cycles can be improved, and the electrical conductivity of the silicon-containing material can also be improved.

[0021] In some embodiments of the present application, the graphite comprises natural graphite. Thereby, the energy density of the battery can be further improved.

[0022] In some embodiments of the present application, the positive electrode active material comprises a polycrystalline material.

[0023] In some embodiments of the present application, the particle size distribution of the positive electrode active material is bimodal, and the particle sizes corresponding to the two peaks are D1 and D2, respectively, 0.5 μm≤D1≤1.5 μm, and 7 μm≤D2≤12 μm. Thereby, the energy density of the battery can be further improved.

[0024] In some embodiments of the present application, the positive electrode active material further comprises a lithium supplement agent. Thereby, the energy density of the battery can be improved while the battery has high initial efficiency and cycle performance.

[0025] In some embodiments of the present application, the lithium supplement agent comprises Li x M y O z , 1≤x≤5, 1≤y≤3, 1≤z≤8, and M comprises one or more of Ni, Co, V, Cr, Mn, Fe, Mo, Cu, and Zn.

[0026] In some embodiments of the present application, the lithium supplement agent comprises Li2NiO2 and / or Li5FeO4. Thereby, the positive electrode lithium supplement effect can be good.

[0027] In some embodiments of the present application, the lithium supplement agent comprises Li n NiO m and / or Li p FeO p , wherein 0≤n≤2, 0

[0028] In some embodiments of the present application, the lithium supplement agent comprises NiO m and / or Li p FeO q , wherein 0 < m < 2, 0 < p < 1, and 0 < q < 2.

[0029] In some embodiments of the present application, the mass ratio of the lithium supplement agent is 0.5% to 5%, or optionally 1% to 3%, based on the total mass of the positive electrode active material. In this way, the battery can have both high initial efficiency and energy density, and good cycle performance.

[0030] In some embodiments of the present application, the positive electrode active material comprises a nickel-cobalt-manganese metal oxide, and the nickel-cobalt-manganese metal oxide comprises one or more of Na, K, Mg, B, Al, Si, P, S, Ca, Sc, Ti, V, Cr, Fe, Cu, Zn, Sr, Y, Zr, Nb, Mo, Cd, Sn, Sb, Te, Ba, Ta, W, Yb, La, Ce, F, and optionally one or more of Al, Zr, B, P, and Ti. In this way, the electrochemical performance of the positive electrode active material can be further improved.

[0031] In some embodiments of the present application, the nickel-cobalt-manganese metal oxide comprises Al, and the mass ratio of the Al is 0.01% to 0.1%, based on the total mass of the positive electrode active material.

[0032] In some embodiments of the present application, the nickel-cobalt-manganese metal oxide comprises Zr, and the mass ratio of the Zr is 0.1% to 0.5%, based on the total mass of the positive electrode active material.

[0033] In some embodiments of the present application, the nickel-cobalt-manganese metal oxide comprises B, and the mass ratio of the B is 0.01% to 0.15%, based on the total mass of the positive electrode active material.

[0034] In some embodiments of the present application, the nickel-cobalt-manganese metal oxide comprises P, and the mass ratio of the P is 0.05% to 0.2%, based on the total mass of the positive electrode active material.

[0035] In some embodiments of the present application, the single-sided coating area density of the positive electrode active material layer is 20 mg / cm 2 to 30 mg / cm 2 . In this way, the battery can have both high energy density and good kinetic performance.

[0036] In some embodiments of the present application, the compaction density of the positive electrode active material layer is 3.3 g / cm 3 to 3.6 g / cm3 Thus, the battery has high energy density and good kinetic performance.

[0037] In some embodiments of the present application, the thickness of the positive electrode current collector is 13-19 μm, and optionally 15-17 μm. Thus, the risk of fracture of the current collector and the active material layer is reduced, and the energy density of the battery is considered, so that the battery has high energy density, good cycle stability and long service life.

[0038] In some embodiments of the present application, the single-sided coating area density of the negative electrode active material layer is 10-18 mg / cm 2 2 , and optionally 13-15 mg / cm 2 2 . Thus, the battery has high energy density and good kinetic performance.

[0039] In some embodiments of the present application, the compaction density of the negative electrode active material layer is 1.3-1.7 g / cm 3 3 , and optionally 1.4-1.55 g / cm 3 3 . Thus, the battery has high energy density and good kinetic performance.

[0040] In some embodiments of the present application, the thickness of the negative electrode current collector is 6-13 μm, and optionally 8-11 μm.

[0041] In some embodiments of the present application, the battery cell further comprises an electrolyte, and the electrolyte comprises an organic solvent, and the organic solvent comprises a cyclic carbonate and a linear carbonate. Thus, it is further beneficial to obtain a battery with high energy density.

[0042] In some embodiments of the present application, the cyclic carbonate comprises EC and / or PC, and the linear carbonate comprises one or more of EMC, DMC and DEC.

[0043] In some embodiments of the present application, the mass fraction of the cyclic carbonate is 15-25%, and the mass fraction of the linear carbonate is 50-70%, based on the total mass of the electrolyte.

[0044] In some embodiments of the present application, the electrolyte further comprises an additive, and the additive comprises FEC and / or VC. Thus, it is beneficial to further improve the initial efficiency, energy density and cycle performance of the battery.

[0045] ​​​​In some embodiments of the present application, the battery cell further comprises: a separator film, a ceramic coating containing inorganic oxide is arranged on one side of the separator film facing the positive electrode tab. Thereby, the oxidation resistance and high temperature stability of the separator film are improved.

[0046] In some embodiments of the present application, the separator film is further provided with a first adhesive coating between the separator film and the ceramic coating.

[0047] In some embodiments of the present application, the separator film is provided with a second adhesive coating on one side facing the negative electrode tab.

[0048] In some embodiments of the present application, the total thickness of the separator film is 7-14 μm, and optionally 7-10 μm.

[0049] In some embodiments of the present application, the battery cell is a cylindrical battery, which comprises a shell comprising an upper cover, a lower cover and a side wall, and the thickness of the side wall is 0.2-0.4 mm, and optionally 0.25-0.3 mm. Thereby, the side wall of the shell has a lower thickness and mass, which is beneficial for further improving the energy density of the battery.

[0050] In some embodiments of the present application, the thickness of the shell wall of the upper cover or the lower cover is 0.25-0.45 mm, and optionally 0.27-0.33 mm. Thereby, the upper cover or the lower cover of the shell has a lower thickness and mass, which is beneficial for further improving the energy density of the battery.

[0051] The second aspect of the present application provides a battery device, which comprises: the battery cell of the first aspect of the present application, and the electric device comprises at least one of a battery module, a battery pack and an energy storage device.

[0052] The third aspect of the present application provides an electric device, which comprises: the battery cell of the first aspect of the present application or the electric device of the second aspect of the present application, and the battery cell or the electric device is used for providing electric energy. BRIEF DESCRIPTION OF DRAWINGS

[0053] The above and / or additional aspects and advantages of the present application will become apparent and more readily appreciated from the following description, taken in conjunction with the following drawings in which:

[0054] FIG. 1 is a structural schematic diagram of a battery cell according to an embodiment of the present application.

[0055] FIG. 2 is a structural schematic diagram of a battery module according to an embodiment of the present application.

[0056] FIG. 3 is a structural schematic diagram of a battery pack according to an embodiment of the present application.

[0057] Fig. 4 is an exploded view of Fig. 3.

[0058] Fig. 5 is a schematic view of an embodiment of a power consuming device using the battery device of the present application as a power source.

[0059] BRIEF DESCRIPTION OF DRAWINGS 1: battery cell; 2: battery module; 3: battery pack; 4: upper case; 5: lower case. DETAILED DESCRIPTION

[0060] The present application will be further clarified by the following examples. It should be understood that these examples are included merely for purposes of illustration and are not intended to limit the scope of the application.

[0061] Reference in the specification to "an embodiment" or "the embodiment" means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the application. The appearances of the phrase "in an embodiment" or "in the embodiment" in various places in the specification are not necessarily all referring to the same embodiment, nor are they necessarily all referring to a single, alternative embodiment that all implementations can employ. It will be apparent to those skilled in the art that the embodiments described herein can be employed in other embodiments.

[0062] "Range" as disclosed herein is defined in the form of a lower limit and / or an upper limit, a given range is defined by selecting a lower limit and / or an upper limit, the selected lower limit and / or upper limit define the boundaries of the particular range. Such ranges defined by a lower limit and / or an upper limit can be inclusive or exclusive of the end values, and can be arbitrarily combined, i.e., any lower limit can be combined with any upper limit to form a range that is not explicitly recited, and any lower limit can be combined with any other lower limit to form a range that is not explicitly recited, and any upper limit can be combined with any other upper limit to form a range that is not explicitly recited. In addition, each individual disclosed point or single numerical value can itself be a lower limit or an upper limit combined with any other point or single numerical value or with other lower limits or upper limits to form a range that is not explicitly recited.

[0063] If not specifically stated, all embodiments and optional embodiments of the present application can be combined with each other to form new technical solutions, and such technical solutions should be considered to be included in the disclosure of the present application.

[0064] If not specifically stated, all technical features and optional technical features of the present application can be combined with each other to form new technical solutions, and such technical solutions should be considered to be included in the disclosure of the present application.

[0065] If there is no special description, all the steps of the present application can be carried out in sequence or randomly, preferably in sequence. For example, the method comprises steps S1 and S2, which means that the method can comprise steps S1 and S2 in sequence, or steps S2 and S1 in sequence. For example, the method also comprises step S3, which means that step S3 can be added to the method in any order, for example, the method can comprise steps S1, S2 and S3, or steps S1, S3 and S2, or steps S3, S1 and S2, etc.

[0066] If there is no special description, in the present application, the term "and / or" is only a description of the association relationship of the associated objects, which means that there can be three relationships, for example, A and / or B, which means that there are three cases of A alone, A and B together, and B alone. In addition, the character " / " in this paper generally means that the front and rear associated objects are an "or" relationship.

[0067] In the present application, the terms "a plurality of" and "a plurality of" refer to two or more.

[0068] Unless otherwise defined, all technical and scientific terms used in the present application have the same meaning as understood by a person skilled in the art to which the present application belongs; the terms used in the present application are only for the purpose of describing the specific embodiments and are not intended to limit the present application; the terms "include" and "have" in the specification and claims of the present application and any modification thereof are intended to cover non-exclusive inclusion. Unless otherwise stated, the terms used in the present application have the same meaning as generally understood by those skilled in the art. Unless otherwise stated, the values of the parameters mentioned in the present application can be measured by various measurement methods commonly used in the art (for example, tests can be performed according to the methods given in the examples of the present application).

[0069] With the continuous promotion of the green environmental protection theme, the application of batteries has penetrated into all aspects of life, including vehicles, electronic devices, energy storage devices, etc. However, as the application of batteries continues to expand, people's requirements for batteries are also getting higher and higher. For example, taking lithium-ion batteries as an example, high-energy-density and long-service-life secondary batteries have become an important research direction in the battery industry. In the existing battery system, there are many improvement directions to improve the energy density and service life of the battery, including but not limited to the selection of positive and negative active materials, the improvement of battery structure, the optimization of electrolyte, etc. For example, there is a scheme of using high-nickel positive active material combined with graphite negative electrode to prolong the service life of the battery from the aspects of battery energy density and cycle stability, but the scheme has limited ability to improve the energy density of the battery.

[0070] The application aims to develop a battery cell with high energy density and long service life. The energy density of the battery cell is improved by using high-nickel positive electrode active material in combination with graphite and silicon-containing material negative electrode. At the same time, the cycle performance of the battery cell is considered by controlling the nickel content in the positive electrode active material, the incorporation amount of the silicon-containing material in the negative electrode plate, and the thickness ratio of the current collector in the negative electrode plate. The cycle life of the battery cell is improved on the basis of obtaining high energy density, and the service life of the battery cell is prolonged.

[0071] In the positive electrode tab of the application, the positive electrode active material comprises nickel-cobalt-manganese metal oxide, and the mole percentage of nickel element in the nickel-cobalt-manganese metal oxide is 80% to 96% based on the total mole amount of nickel-cobalt-manganese elements in the nickel-cobalt-manganese metal oxide, or the positive electrode active material comprises nickel-cobalt-aluminum metal oxide, and the mole percentage of nickel element in the nickel-cobalt-aluminum metal oxide is 80% to 96% based on the total mole amount of nickel-cobalt-aluminum elements in the nickel-cobalt-aluminum metal oxide; in the negative electrode tab, the negative electrode active material comprises graphite and silicon-containing material, and the mass percentage of silicon element in the negative electrode active material is 0.1% to 10% based on the total mass of the negative electrode active material, and the thickness of the negative electrode current collector is 3% to 8% of the total thickness of the negative electrode tab. The positive electrode tab uses high-nickel ternary active material, and the negative electrode tab uses graphite and silicon-containing material, which can fully utilize the characteristics of high capacity of positive and negative electrode materials to improve the capacity of the positive and negative electrode tabs and significantly improve the energy density of the battery. However, the silicon-containing material is prone to particle breakage and pulverization due to large volume expansion during the charging and discharging cycle, which in turn causes rapid capacity decay of the battery. Therefore, although appropriately increasing the amount of silicon-containing material in the negative electrode tab has a positive effect on the improvement of the energy density of the battery, the cycle performance of the battery will decrease with the increase of the amount of silicon-containing material, especially when the positive electrode active material is a high-nickel material, the cycle capacity decay of the battery is more severe, so the amount of silicon-containing material in the negative electrode tab needs to be controlled within a suitable range. However, although the appropriate amount of silicon-containing material in the negative electrode tab can improve the energy density and reduce the cycle decay, the characteristics of the silicon-containing material in the negative electrode tab that is prone to expansion also cause the negative electrode current collector connected thereto to be repeatedly stretched by stress during long-term cycling, so if the negative electrode current collector in the negative electrode tab is set too thin (low tensile strength), it is easy to cause the negative electrode active material layer to be damaged or cracked due to the low tensile strength of the negative electrode current collector, reducing the cycle life and reliability of the battery, and if the current collector is set too thick, the energy density of the battery will also be reduced and the internal resistance of the battery will also be increased. In the application, by comprehensively adjusting the nickel content in the high-nickel positive electrode active material system and the amount of silicon-containing material in the negative electrode tab to meet the given range respectively, and adjusting the thickness ratio of the current collector in the negative electrode tab to be within the given range, the energy density of the battery can be improved while reducing the risk of damage or disconnection of the electrode tab due to repeated expansion of the battery during long-term cycling. Furthermore, the battery cell can have both high energy density and long service life.

[0072] The battery cell disclosed by the embodiments of the present application can be used in various energy storage systems using the battery cell or a battery device having the battery cell as a power source or using the battery cell or the battery device having the battery cell as an energy storage element. The power consumption equipment can include, but is not limited to, a mobile phone, a tablet, a notebook computer, an electric toy, an electric tool, an electric vehicle, an electric automobile, a ship, a spacecraft, and the like. Among them, the electric toy can include a fixed or mobile electric toy, for example, a game machine, an electric automobile toy, an electric ship toy, and an electric aircraft toy, and the like, and the spacecraft can include an airplane, a rocket, a space shuttle, a spacecraft, and the like.

[0073] The first aspect of the present application provides a battery cell, comprising: a positive electrode tab and a negative electrode tab. The positive electrode tab comprises a positive electrode current collector and a positive electrode active material layer arranged on at least one side of the positive electrode current collector, the positive electrode active material layer comprising a positive electrode active material; the negative electrode tab comprises a negative electrode current collector and a negative electrode active material layer arranged on at least one side of the negative electrode current collector, the negative electrode active material layer comprising a negative electrode active material; wherein the positive electrode active material comprises a nickel-cobalt-manganese metal oxide, the mole percentage of nickel element in the nickel-cobalt-manganese metal oxide is 80% to 96% based on the total mole amount of nickel-cobalt-manganese elements in the nickel-cobalt-manganese metal oxide, or the positive electrode active material comprises a nickel-cobalt-aluminum metal oxide, the mole percentage of nickel element in the nickel-cobalt-aluminum metal oxide is 80% to 96% based on the total mole amount of nickel-cobalt-aluminum elements in the nickel-cobalt-aluminum metal oxide; the negative electrode active material comprises graphite and a silicon-containing material, the mass percentage of silicon element in the negative electrode active material is 0.1% to 10% based on the total mass of the negative electrode active material; and the thickness of the negative electrode current collector is 3% to 8% of the total thickness of the negative electrode tab.

[0074] In the battery cell of the present application, the positive electrode sheet adopts high-nickel multi-element active material, and the negative electrode sheet adopts graphite and silicon-containing material, which can fully utilize the high capacity characteristics of the positive and negative electrode materials to improve the capacity of the positive and negative electrode sheets, and significantly improve the energy density of the battery. However, the silicon-containing material is prone to particle breakage and pulverization due to large volume expansion during the charging and discharging cycle, which in turn causes rapid capacity decay of the battery. Therefore, although appropriately increasing the amount of silicon-containing material in the negative electrode sheet has a positive effect on the improvement of the energy density of the battery, the cycle performance of the battery will be reduced as the amount of silicon-containing material increases, especially when the positive active material is a high-nickel material, the cycle capacity decay of the battery is more severe. Therefore, the amount of silicon-containing material in the negative electrode sheet needs to be controlled within a suitable range. However, although the appropriate amount of silicon-containing material in the negative electrode sheet can improve the energy density and reduce the cycle decay, the silicon-containing material in the negative electrode sheet is prone to expansion, which causes the negative active material layer to be repeatedly expanded during long-term cycling, resulting in the negative current collector being repeatedly stretched by stress. Therefore, if the negative current collector in the negative electrode sheet is too thin (low tensile strength), it is easy to cause the negative active material layer to be damaged or cracked due to the low tensile strength of the negative current collector, reducing the cycle life and reliability of the battery. If the thickness of the current collector is too thick, the energy density of the battery will be reduced and the internal resistance of the battery will be increased.

[0075] This problem is particularly pronounced in cylindrical batteries. For example, in a cylindrical battery, the outermost positive electrode sheet is subjected to a large stress during long-term cycling, and is more likely to be damaged or disconnected due to the unreasonable thickness ratio of the current collector to the electrode sheet, which has a more significant impact on the cycle performance.

[0076] In the present application, by comprehensively adjusting the nickel content in the high-nickel positive active material system and the amount of silicon-containing material in the negative electrode sheet to meet the given range, and adjusting the thickness ratio of the current collector in the negative electrode sheet to be within the given range, the energy density of the battery can be improved while reducing the risk of damage or disconnection of the electrode sheet due to repeated expansion during long-term cycling of the battery cell. For example, in a cylindrical battery, the risk of damage or disconnection of the outermost positive electrode sheet can be reduced, and the energy density, cycle life and reliability of the battery cell can be improved.

[0077] Therefore, the battery cell of the first aspect of the present application has at least the following beneficial effects: the battery can have both high energy density and long service life.

[0078] For example, the positive active material can include nickel-cobalt-manganese metal oxide, and the mole ratio of nickel in the nickel-cobalt-manganese metal oxide can be 80%, 82%, 85%, 88%, 90%, 92%, 95%, or 96%, etc., based on the total mole amount of nickel, cobalt and manganese elements in the nickel-cobalt-manganese metal oxide.

[0079] For example, the positive active material can include nickel cobalt aluminum metal oxide, and the mole percentage of nickel in the nickel cobalt aluminum metal oxide can be 80%, 82%, 85%, 88%, 90%, 92%, 95%, or 96%, etc., based on the total moles of nickel, cobalt, and aluminum elements in the nickel cobalt aluminum metal oxide.

[0080] For example, the mass percentage of silicon in the negative active material can be 0.1%, 0.3%, 0.5%, 0.8%, 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, or 10%, etc., based on the total mass of the negative active material.

[0081] For example, the thickness of the negative current collector can be 3%, 4%, 5%, 6%, 7%, or 8%, etc., of the total thickness of the negative electrode tab.

[0082] In this application, the analysis method of the relative mole percentage of nickel in the positive active material and the mass percentage of silicon in the negative active material can include but is not limited to inductively coupled plasma emission spectrometry (ICP) test or EDS energy spectrum analysis. For example, reference can be made to EPA6010D-2014 "Inductively Coupled Plasma Atomic Emission Spectrometry", after the battery is disassembled, the active material sample to be tested is separated from the electrode tab, after the sample to be tested is treated by chemical method and digested into solution, it is atomized into plasma to excite the characteristic spectrum of the element, and the element content is qualitatively and quantitatively analyzed according to the wavelength and intensity (proportional to concentration) of the spectrum. In addition, the thickness percentage of the current collector in the negative electrode tab can be calculated by testing the total thickness and the thickness of the current collector in combination with conventional instruments such as thickness meter. In actual operation, mechanical stripping method can be used to obtain the active material sample to be tested from the electrode tab when testing the element composition in the active material, and one or more of heat treatment, mechanical stripping, and chemical dissolution method can be used to effectively separate the active material layer and the current collector of the electrode tab when testing the thickness of the current collector.

[0083] [Positive electrode tab]

[0084] In some embodiments of the present application, the thickness of the positive electrode current collector can be 7.5% to 15% of the total thickness of the positive electrode tab. For example, the thickness of the positive electrode current collector can be 7.5%, 8%, 9%, 10%, 11%, 12%, 13%, 14%, or 15% of the total thickness of the positive electrode tab, and the like. High-nickel materials expand more than low-nickel materials during cycling. This characteristic of high-nickel materials also causes the positive active material layer to be repeatedly stretched due to repeated expansion during long-term cycling. Therefore, if the thickness of the positive electrode current collector in the positive electrode tab is set to be relatively thin (low tensile strength), the positive electrode current collector is easily stretched due to the positive active material layer, which increases the risk of damage or cracking of the positive active material layer due to low tensile strength, and reduces the cycle life and reliability of the battery. By controlling the thickness of the positive electrode current collector in the positive electrode tab to be within the given range, the cycle performance and reliability of the battery cell can be further improved, and the energy density of the battery cell can be considered. The adverse effects of increasing the thickness of the positive electrode current collector on the energy density and internal resistance of the battery can be reduced. Thus, the battery can have high energy density, good cycle stability, and long service life. Alternatively, the thickness of the positive electrode current collector can be 10% to 13.5% of the total thickness of the positive electrode tab.

[0085] In some embodiments of the present application, the positive active material can include a nickel-cobalt-manganese metal oxide. The mole percentage of nickel in the nickel-cobalt-manganese metal oxide can be 83% to 91% based on the total moles of nickel, cobalt, and manganese in the nickel-cobalt-manganese metal oxide. Alternatively, the positive active material can include a nickel-cobalt-aluminum metal oxide. The mole percentage of nickel in the nickel-cobalt-aluminum metal oxide can be 83% to 91% based on the total moles of nickel, cobalt, and aluminum in the nickel-cobalt-aluminum metal oxide. For high-nickel-content nickel-cobalt-manganese and / or nickel-cobalt-aluminum positive active materials, controlling the relative mole content of nickel to be within the given range can further consider the cycle stability of the battery while improving the energy density of the battery, reduce the risk of structural instability or lithium-nickel mixing of the positive active material due to high nickel content, and prolong the service life of the battery.

[0086] In some embodiments of the present application, the positive active material can include a polycrystalline material. Alternatively, the polycrystalline material can include secondary particles formed by the accumulation of primary particles. In some embodiments, the positive active material can be a polycrystalline material. In other embodiments, the positive active material can include a polycrystalline material and a single-crystal material. Compared to the polycrystalline material, the single-crystal material has a relatively small particle size, which can fill the pores of the polycrystalline material, thereby improving the compaction density of the positive active material layer. In addition, the crystal structure of the single-crystal particle is more stable, and the voltage is higher, and the cycle life is better. Mixing single-crystal materials and polycrystalline materials can further improve the energy density and cycle performance of the battery and prolong the service life.

[0087] In some embodiments of the present application, the particle size distribution of the positive electrode active material can be bimodal distribution, and the particle sizes corresponding to the peaks of the two peaks can be D1 and D2, respectively, 0.5 pm≤D1≤1.5 pm, and 7 pm≤D2≤12 pm. For example, the value of D1 can be 0.5 pm, 0.8 pm, 1 pm, 1.2 pm, or 1.5 pm, and the value of D2 can be 7 pm, 8 pm, 9 pm, 10 pm, 11 pm, or 12 pm. The particle size distribution of the positive electrode active material can be determined and counted using a laser particle size analyzer (Malvern Master Size 2000) according to the standard GB / T 19077-2016 / ISO 13320:2009. The particle size distribution of the positive electrode active material can be bimodal distribution by using two kinds of positive electrode active materials with different particle size distributions, so that the small particle size positive electrode active material particles can fill the pores of the large particle positive electrode active material, and a higher electrode compaction density can be achieved. In the embodiments of the present application, by controlling the particle size distribution of the positive electrode active material to be bimodal distribution and meeting the given range, the compaction density of the positive electrode active material layer can be significantly improved, and the energy density of the battery can be further improved.

[0088] In some embodiments of the present application, the positive electrode active material can be a polycrystalline material, the particle size distribution of the positive electrode active material can be bimodal distribution, and the particle sizes corresponding to the peaks of the two peaks can be D1 and D2, respectively, 0.5 pm≤D1≤1.5 pm, and 7 pm≤D1≤12 pm. Compared with the mixing of single crystals and polycrystals, using a polycrystalline material and meeting the given bimodal distribution condition of the particle size distribution can further improve the energy density of the battery.

[0089] In some embodiments of the present application, the positive electrode active material can further include a lithium supplement agent. Compared with graphite, the active sites of silicon-containing materials are relatively more, and the Li consumed in the formation of SEI film in lithium batteries is also relatively more. In addition, the volume expansion of silicon-containing materials during charge and discharge cycles is also relatively large, which is easy to cause the continuous rupture and regeneration of SEI film due to cycle expansion, thereby consuming more Li. By adding a lithium supplement agent to the positive electrode active material, the consumption of Li by the silicon-containing material can be compensated or alleviated, the adverse effects of the introduction of the silicon-containing material on the initial efficiency and cycle performance of the battery can be reduced, and the high-temperature storage performance of the battery can also be improved. Therefore, the battery can have high energy density, high initial efficiency, good cycle performance, and high-temperature storage performance, and the service life of the battery can be prolonged.

[0090] In some embodiments of the present application, the lithium supplement agent can include Li x M y O z, 1≤x≤5, 1≤y≤3, 1≤z≤8, M includes one or more elements of Ni, Co, V, Cr, Mn, Fe, Mo, Cu, Zn. For example, x can be 1, 2, 3, 4, 5, or a range formed by any of the above values, and optionally, x can be 1 x M y O z , and / or Li p FeO q can play a good positive electrode lithium supplement effect. It can be understood that during the formation and use of the battery, lithium in the lithium supplement agent will be partially or completely released as the lithium supplement process proceeds, causing the lithium supplement agent to change from the initial state to a partially or completely delithiated state, at which time x≤1 and / or z≤1 can occur.

[0091] In some embodiments of the present application, the lithium supplement agent can include, but is not limited to, Li2NiO2 and / or Li5FeO4. In the manufacturing process of the positive electrode sheet, Li2NiO2 and / or Li5FeO4 can be directly incorporated into the positive electrode active material layer. Li2NiO2 can form LiNiO2 with lithium extraction capacity after delithiation, LiNiO2 can become Li 1-x2 NiO2, 0≤x2≤1, and can recover to LiNiO2 in the lithium intercalation state; Li5FeO4 has strong lithium supplement capacity, and LiFeO2 formed after delithiation does not cause obvious side reactions. Therefore, using Li2NiO2 and / or Li5FeO4 as a lithium supplement agent can achieve a good capacity compensation effect.

[0092] In some embodiments of the present application, the lithium supplement agent can include an initial state, a partially delithiated state, and a completely delithiated state. When the lithium supplement agent changes from the initial state to the partially delithiated state and the completely delithiated state, the lithium supplement agent can include Li n NiO m and / or Li p FeO qwherein, 0≤n≤2, 0 For example, n can be 0, 0.5, 1, 1.5, or 2, or a range of any of the above values; m can be 0.5, 1, 1.5, or 2, or a range of any of the above values; p can be 0.5, 1, 2, 3, 4, or 5, or a range of any of the above values; q can be 1, 2, 3, or 4, or a range of any of the above values. For example, when the lithium in Li2NiO2 is partially removed, the composition of the lithium supplement Li n NiO m may include one or more of 0 n NiO m may include Li2NiO2. m For example, when the lithium in Li5FeO4 is partially removed, the composition of the lithium supplement Li p FeO q may include one or more of 1 p FeO q may include LiFeO2, which may, under the influence of polarization and other factors, continue to remove lithium, resulting in Li p FeO q .

[0093] In some embodiments of the present application, when the lithium supplement is converted from the initial state to the fully delithiated state, the lithium supplement can include NiO m and / or Li p FeO q wherein, 0 For example, m can be 0.5, 1, 1.5, or 2, or a range of any of the above values; p can be 0.2, 0.5, 0.8, or 1, or a range of any of the above values; q can be 0.2, 0.5, 1, 1.5, or 2, or a range of any of the above values. For example, when the lithium supplement is fully delithiated, the delithiated lithium supplement can include, but is not limited to, NiO and / or LiFeO2.

[0094] In the embodiments of the present application, the positive electrode active material layer or the positive electrode active material can be qualitatively and quantitatively analyzed in combination with one or more of a scanning electron microscope, an EDS energy spectrometer, an X-ray diffractometer, an inductively coupled plasma emission spectrometer and the like conventional instruments and conventional methods. For example, in the positive electrode active material layer, the lithium supplement agent and the nickel-cobalt-manganese metal oxide particles or the nickel-cobalt-aluminum metal oxide generally differ in size, and the lithium supplement agent does not completely disappear after delithiation, but remains residual elements and particle skeletons. The lithium supplement agent generally has a certain volume shrinkage after delithiation, so that the residual particle skeletons form a certain gap with the surrounding area. Based on the above differences, the possible positions of the lithium supplement agent in the cross section of the positive electrode active material layer can be quickly screened in the scanning electron microscope test, and the element composition and content of the lithium supplement agent can be analyzed in combination with the EDS energy spectrometer. In addition, the XRD characterization of the positive electrode active material to be tested can be further combined with the X-ray diffractometer to determine the crystal structure of the lithium supplement agent, and the content of the lithium supplement agent can be further determined in combination with the ICP test.

[0095] In some embodiments of the present application, the mass ratio of the positive electrode active material in the positive electrode active material layer can be 97.5% to 98.5%, for example, 97.5%, 98% or 98.5%, etc., based on the total mass of the positive electrode active material layer. The content of the positive electrode active material can be tested by thermogravimetric analysis of the positive electrode active material layer sample in the discharged state (e.g., after discharging to the lower limit cutoff voltage). For example, the sample to be tested can be heated at a heating rate of 5°C / min until the mass of the sample to be tested no longer changes significantly, and the temperature range of the heating can be 25°C to 600°C. The content of the positive electrode active material meeting the given range is beneficial to further improve the energy density of the battery.

[0096] In some embodiments of the present application, the mass percentage of the lithium supplementing agent can be 0.5% to 5%, for example, 0.5%, 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, or 5%, etc., based on the total mass of the positive electrode active material. The content of the lithium supplementing agent in the positive electrode active material can be calculated by testing the total content of Li in the positive electrode active material per unit area, the residual Li content in the lithium supplementing agent, and the Li content in the nickel-cobalt-manganese metal oxide or nickel-cobalt-aluminum metal oxide, etc. Alternatively, the content of the lithium supplementing agent in the positive electrode active material can be tested in the discharged state (e.g., after discharging to the lower limit cutoff voltage). Appropriate increase in the content of the lithium supplementing agent is conducive to improving the initial efficiency of the battery and the cycle performance of the battery. In the present application, the content of the lithium supplementing agent is controlled to meet the given conditions, which can reduce the risk of significant decrease in the energy density of the battery due to excessive addition of the lithium supplementing agent on the basis of improving the initial efficiency of the battery, thereby enabling the battery to have high initial efficiency and energy density, good cycle performance, and long service life. Further, the mass percentage of the lithium supplementing agent can be 1% to 3% based on the total mass of the positive electrode active material, which can further enable the battery to have high initial efficiency and energy density, good cycle performance.

[0097] In some embodiments of the present application, the positive electrode active material can include a nickel-cobalt-manganese metal oxide, which can include one or more of Na, K, Mg, B, Al, Si, P, S, Ca, Sc, Ti, V, Cr, Fe, Cu, Zn, Sr, Y, Zr, Nb, Mo, Cd, Sn, Sb, Te, Ba, Ta, W, Yb, La, Ce, F. For example, in a lithium battery, the nickel-cobalt-manganese metal oxide can include Li x1 Ni a Co b Mn c M1 dO2, wherein, 0.8≤x1≤1.2, 0.8≤a≤0.96, 0.04≤b≤0.12, 0.03≤c≤0.07, 0≤d≤0.13, optionally, a+b+c+d=1, M1 can be one or more of Na, K, Mg, B, Al, Si, P, S, Ca, Sc, Ti, V, Cr, Fe, Cu, Zn, Sr, Y, Zr, Nb, Mo, Cd, Sn, Sb, Te, Ba, Ta, W, Yb, La, Ce, F. The other elements (such as M1 elements) in the nickel-cobalt-manganese metal oxide can be qualitatively and quantitatively analyzed by inductively coupled plasma emission spectrometry (ICP) testing or EDS energy spectrum analysis, etc. For example, the ICP testing can be performed under a discharge state, for example, the battery cell can be fully discharged (e.g., discharged to the lower limit cutoff voltage), and then the battery cell is disassembled to obtain the positive electrode active material sample to be tested, and then the relevant test is performed. The doping of the elements in the nickel-cobalt-manganese ternary active material can further improve the electrochemical performance and prolong the service life of the battery.

[0098] In some embodiments of the present application, the positive electrode active material can include a nickel-cobalt-manganese metal oxide, and the nickel-cobalt-manganese metal oxide can include one or more of Al, Zr, B, P, Ti. The doping of elements such as Zr or B in the nickel-cobalt-manganese metal oxide is beneficial to further stabilize the structure of the high-nickel ternary active material and improve the cycle stability. In this way, the battery can further have high energy density and good cycle stability, and the service life of the battery can be prolonged.

[0099] In some embodiments of the present application, the nickel-cobalt-manganese metal oxide can include Al elements, and the mass fraction of the Al elements can be 0.01% to 0.1% based on the total mass of the positive electrode active material, for example, 0.01%, 0.02%, 0.05%, 0.08%, or 0.1%, etc.

[0100] In some embodiments of the present application, the nickel-cobalt-manganese metal oxide can include Zr elements, and the mass fraction of the Zr elements can be 0.1% to 0.5% based on the total mass of the positive electrode active material, for example, 0.1%, 0.2%, 0.3%, 0.4%, or 0.5%, etc.

[0101] In some embodiments of the present application, the nickel-cobalt-manganese metal oxide can include B elements, and the mass fraction of the B elements can be 0.01% to 0.15% based on the total mass of the positive electrode active material, for example, 0.01%, 0.02%, 0.05%, 0.08%, 0.1%, 0.12%, or 0.15%, etc.

[0102] In some embodiments of the present application, the nickel-cobalt-manganese metal oxide can include a P element, and the mass percentage of the P element can be 0.05% to 0.2%, such as 0.05%, 0.08%, 0.1%, 0.12%, 0.15%, 0.18%, or 0.2%, etc., based on the total mass of the positive electrode active material.

[0103] In the present application, controlling the content of the elements in the nickel-cobalt-manganese metal oxide to meet the given range is not only conducive to further improving the electrochemical performance of the nickel-cobalt-manganese ternary active material, but also can reduce the risk of adversely affecting the performance of the battery due to the introduction of a higher content of doping elements.

[0104] In some embodiments of the present application, the single-sided coating area density of the positive electrode active material layer can be 20 mg / cm 2 to 30 mg / cm 2 , such as 20 mg / cm 2 , 22.5 mg / cm 2 , 25 mg / cm 2 , 27.5 mg / cm 2 , or 30 mg / cm 2 , etc. Appropriately increasing the area density of the positive electrode active material layer is conducive to further improving the energy density of the battery, and the area density of the positive electrode active material layer meeting the given range can reduce the risk of the battery dynamics performance being reduced due to the higher coating area density of the electrode sheet on the basis of the battery having a higher energy density, and thus the battery can have both a higher energy density and better dynamics performance.

[0105] In some embodiments of the present application, the compaction density of the positive electrode active material layer can be 3.3 g / cm 3 to 3.6 g / cm 3 , such as 3.3 g / cm 3 , 3.35 g / cm 3 , 3.4 g / cm 3 , 3.45 g / cm 3 , 3.5 g / cm 3 , 3.55 g / cm 3 , or 3.6 g / cm 3 , etc. Appropriately increasing the compaction density of the positive electrode active material layer is conducive to further improving the energy density of the battery, and the compaction density of the positive electrode active material layer meeting the given range can reduce the risk of the battery dynamics performance being reduced due to the higher compaction density of the electrode sheet on the basis of the battery having a higher energy density, and thus the battery can have both a higher energy density and better dynamics performance.

[0106] In the present application, the single-side coating area density of the positive electrode active material layer and the compaction density of the positive electrode active material layer can be determined by discharging the battery monomer to 0% SOC and referring to the following method: the positive electrode tab of the battery monomer is disassembled, for example, the single-side coated positive electrode tab (if it is a double-side coated tab, the positive electrode active material layer on one side can be wiped off first), punched into a small disc with an area of S1, weighed, recorded as M1, and its thickness H1 is measured. Then the positive electrode active material layer of the above weighed positive electrode tab is wiped off, the weight of the positive electrode current collector is weighed, recorded as M0, and its thickness H0 is measured. The single-side coating area density of the positive electrode active material layer = (the weight of the positive electrode tab M1 - the weight of the positive electrode current collector M0) / S1, the thickness of the positive electrode active material layer = the thickness of the positive electrode tab H1 - the thickness of the positive electrode current collector H0, and the compaction density of the positive electrode active material layer = the single-side coating area density of the positive electrode active material layer / the thickness of the positive electrode active material layer.

[0107] It should be noted that in the present application, discharging the battery monomer to 0% SOC means: charging the battery monomer to 4.25V at 1 / 3C constant current, then charging to 0.05C current at 4.25V constant voltage, standing for 5 minutes, and then discharging to 2.5V at 1 / 3C, corresponding to the state of charge of the battery monomer.

[0108] In some embodiments of the present application, the thickness of the positive electrode current collector can be 13-19 μm, for example, it can be 13 μm, 14 μm, 15 μm, 16 μm, 17 μm, 18 μm or 19 μm, etc. Appropriately increasing the thickness of the positive electrode current collector can reduce the risk of damage to the positive electrode current collector at a higher compaction density, as well as the risk of tab breakage due to expansion or stress pulling during the charge and discharge cycle. By making the thickness of the current collector meet the given range, both the risk of current collector breakage during tab preparation and the risk of tab breakage during battery use can be reduced, improving the cycle performance of the battery, and also taking into account the energy density of the battery, reducing the adverse effects of increasing the thickness of the current collector on the energy density of the battery, so that the battery has both high energy density, good cycle stability and long service life. Further, the thickness of the positive electrode current collector can be 15-17 μm.

[0109] In some embodiments of the present application, the positive electrode current collector can use conventional metal foil or composite current collector (metallic material can be arranged on a polymer substrate to form a composite current collector). As an example, the positive electrode current collector can include at least one of copper foil, aluminum foil, nickel foil, stainless steel foil, stainless steel mesh and carbon-coated aluminum foil.

[0110] In some embodiments of the present application, the positive active material layer can also optionally include at least one of a binder, a conductive agent, and other optional additives. Among them, the binder, conductive agent, and additives can all be conventional choices in the art, for example, the conductive agent can include but is not limited to one or more of super-p, acetylene black, carbon black, ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers, and the binder can include but is not limited to one or more of styrene-butadiene rubber (SBR), water-based acrylic resin, polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), ethylene-vinyl acetate copolymer (EVA), polyacrylic acid (PAA), carboxymethyl cellulose (CMC), polyvinyl alcohol (PVA), and polyvinyl butyral (PVB). These materials can all be obtained through commercial channels.

[0111] [anode sheet]

[0112] In some embodiments of the present application, the mass fraction of silicon in the negative active material can be 0.5% to 9.5%, for example, it can be 0.5%, 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, or 9.5%, etc., based on the total mass of the negative active material. Controlling the proportion of silicon-containing material in the negative active material to make the mass fraction of silicon in the negative active material meet the given range is beneficial to further balance the promotion effect of the silicon-containing material on the improvement of the battery energy density and the adverse effects brought by the large number of active sites and large cycle expansion volume of the silicon-containing material on the initial efficiency and cycle capacity retention rate of the battery, thereby being beneficial to further improving the battery energy density while considering high initial efficiency and cycle stability. Optionally, the mass fraction of silicon in the negative active material can be 2% to 9.5%, based on the total mass of the negative active material.

[0113] In some embodiments of the present application, the thickness of the negative current collector can be 4% to 7% of the total thickness of the anode sheet. In this way, on the basis of reducing the risk of damage or fracture of the anode sheet caused by repeated expansion of the battery during long-term cycling, the adverse effects of the increase in the thickness of the negative current collector on the energy density of the battery are further reduced, so that the battery has high energy density, good cycle stability, and long service life.

[0114] In some embodiments of the present application, the graphite can include natural graphite. Compared with artificial graphite, natural graphite has higher specific capacity, and the use of natural graphite in combination with silicon-containing material is beneficial to further improving the energy density of the battery.

[0115] In some embodiments of the present application, the silicon-containing material can include a silicon-oxygen material and / or a silicon-carbon material. Thereby, the energy density of the battery can be further improved. The type of the silicon-containing material can be qualitatively analyzed by one or more of conventional characterization methods such as X-ray diffraction analysis (XRD), EDS energy spectrum analysis, etc.

[0116] In some embodiments of the present application, the mass percentage of silicon in the negative active material can be 2% to 6%, for example, 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, 5%, 5.5%, or 6%, based on the total mass of the negative active material. Controlling the proportion of the silicon-containing material in the negative active material such that the mass percentage of silicon in the negative active material meets the given range can further balance the improvement effect of the silicon-containing material on the improvement of the energy density of the battery and the adverse effects of the large number of active sites and large cycle expansion volume of the silicon-containing material on the initial efficiency and cycle capacity retention rate of the battery, thereby further improving the energy density of the battery while taking into account the high initial efficiency and cycle stability. Further, the mass percentage of silicon in the negative active material can be 3% to 5%, based on the total mass of the negative active material.

[0117] In some embodiments of the present application, the silicon-containing material can also include a metal element, which can include one or more of Na, Li, Ti, Fe, and Co. Whether the silicon-containing material contains a metal element can be analyzed by one or more of conventional characterization methods such as EDS energy spectrum analysis and ICP testing in a discharged state (e.g., discharged to the lower limit cutoff voltage or discharged to 0% SOC). For example, after being discharged to 0% SOC, the battery cell can be disassembled, the electrode can be soaked in DMC, and then the electrode can be quenched by plasma, a cross section can be taken and observed under a scanning electron microscope, and the type of metal element in the silicon-containing material can be tested by an EDS energy spectrometer. Doping Na or Li in the silicon-containing material can occupy the active sites of the silicon-containing material, reduce the consumption of Li in the process of forming the SEI film, and thereby improve the energy density and cycle life of the battery; doping Ti, Fe, or Co in the silicon-containing material can increase the carrier concentration and improve the conductivity of the silicon-containing material, and thereby the energy density and electrochemical performance of the battery can be further improved.

[0118] In some embodiments of this application, the silicon-containing material includes a metal element, the mass of which can be 0.1% to 0.6% of the mass of silicon, such as 0.1%, 0.2%, 0.3%, 0.4%, 0.5%, or 0.6% of the mass of silicon. The content of the metal element in the negative electrode active material can be analyzed using one or more conventional characterization methods, such as ICP testing and EDS energy dispersive spectroscopy, under discharge conditions (e.g., discharged to the lower cutoff voltage or discharged to 0% SOC), thereby obtaining the relative content of the metal element and silicon element in the negative electrode active material. For example, after discharging to 0% SOC, the battery cell can be disassembled to obtain the negative electrode sheet, soaked in DMC, and 2g of powder scraped off. The metal content can then be tested using ICP. Ensuring the metal element content meets the given range is beneficial for further improving the battery's energy density and / or electrochemical performance.

[0119] In some embodiments of this application, at least a portion of the surface of the silicon-containing material may include a carbon coating layer. This not only improves the structural stability of the silicon-containing material during charge-discharge cycles and reduces the risk of pulverization due to volume expansion, but also enhances the conductivity of the silicon-containing material, thereby further improving the electrochemical performance of the battery.

[0120] In some embodiments of this application, the surface density of the single-sided coating of the negative electrode active material layer can be 10 mg / cm³. 2 ~18mg / cm 2 For example, it can be 10 mg / cm³ 2 12mg / cm 2 14mg / cm 2 16mg / cm 2 Or 18mg / cm 2 Appropriately increasing the areal density of the negative electrode active material layer is beneficial for further improving the energy density of the battery. Ensuring the areal density of the negative electrode active material layer meets the given range can reduce the risk of decreased battery kinetic performance due to higher electrode coating areal density, while maintaining a high energy density. This allows the battery to achieve both high energy density and good kinetic performance. Furthermore, the single-sided coating areal density of the negative electrode active material layer can be 13 mg / cm³. 2 ~15mg / cm 2 .

[0121] In some embodiments of this application, the compaction density of the negative electrode active material layer can be 1.3 g / cm³. 3 ~1.7g / cm 3 For example, it can be 1.3g / cm³. 3 1.4g / cm 3 1.5g / cm 3 1.6g / cm3 or 1.7 g / cm 3 and the like. Appropriately increasing the compaction density of the negative active material layer is conducive to further improving the energy density of the battery. When the compaction density of the negative active material layer meets the given range, the risk of the kinetic performance of the battery being reduced due to the high compaction density of the electrode sheet can be reduced on the basis of the battery having a high energy density, and thus the battery can have both a high energy density and good kinetic performance. Further, the compaction density of the negative active material layer can be 1.4 g / cm 3 ~ 1.55 g / cm 3 .

[0122] In the present application, the single-sided coating area density of the negative active material layer and the compaction density of the negative active material layer can be tested according to the relevant test methods of the positive electrode sheet.

[0123] In some embodiments of the present application, the thickness of the negative current collector is 6 μm ~ 13 μm, for example, it can be 6 μm, 7 μm, 8 μm, 9 μm, 10 μm, 11 μm, 12 μm or 13 μm, etc. Appropriately increasing the thickness of the negative current collector can reduce the risk of the negative current collector being damaged at a high compaction density, and the risk of the electrode sheet being broken due to expansion during the charge and discharge cycle. When the thickness of the current collector meets the given range, both the risk of the current collector being broken during the preparation of the electrode sheet and the risk of the electrode sheet being broken during the use of the battery can be reduced, the cycle performance of the battery is improved, and the energy density of the battery is also considered, the adverse effects of the increase in the thickness of the current collector on the energy density of the battery are reduced, and the battery has both a high energy density, good cycle stability and a long service life. Further, the thickness of the negative current collector can be 8 μm ~ 11 μm.

[0124] In some embodiments of the present application, the negative current collector can use a conventional metal foil or a composite current collector (for example, a metal material can be arranged on a polymer substrate to form a composite current collector). As an example, the negative current collector can use a copper foil or the like metal foil.

[0125] In some embodiments of the present application, the negative active material layer usually further includes a binder and a conductive agent. The conductive agent is used to improve the conductivity of the negative active material layer, and the binder is used to firmly bond the negative active material and the binder to the negative current collector. The present application does not make specific limitations on the types of conductive agents and binders of the negative electrode sheet, which can be selected according to actual needs. As an example, the conductive agent can include, but is not limited to, at least one of super conductive carbon, acetylene black, carbon black, ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers. As an example, the binder can include, but is not limited to, at least one of styrene butadiene rubber (SBR), styrene-butadiene rubber (SBCs), water-based acrylic resin, and carboxymethyl cellulose (CMC). In addition, the negative active material layer can also optionally include a thickening agent, such as carboxymethyl cellulose (CMC) and the like. However, the present application is not limited thereto, and other materials that can be used as thickening agents for lithium ion battery negative electrode sheets can also be used.

[0126] [Electrolyte]

[0127] In some embodiments of the present application, the battery cell can further include an electrolyte. The electrolyte can include an organic solvent, and the organic solvent can include a cyclic carbonate and a linear carbonate.

[0128] As an example, in the case of a lithium battery, the electrolyte can include an organic solvent and a lithium salt, and the organic solvent can include a cyclic carbonate and a linear carbonate. In this way, it is further beneficial to obtain a battery with high energy density.

[0129] As an example, the cyclic carbonate can include EC (ethylene carbonate) and / or PC (propylene carbonate), for example, it can be EC. The linear carbonate can include one or more of EMC (methyl ethyl carbonate), DMC (dimethyl carbonate), and DEC (diethyl carbonate).

[0130] In some embodiments of the present application, the mass percentage of the cyclic carbonate can be 15% to 25%, and the mass percentage of the linear carbonate can be 50% to 70%, based on the total mass of the electrolyte. For example, the mass percentage of the cyclic carbonate can be 15%, 18%, 20%, 22%, or 25%, and the mass percentage of the linear carbonate can be 50%, 55%, 60%, 65%, or 70%, based on the total mass of the electrolyte. In this way, it is beneficial to improve the stability of the electrolyte.

[0131] In some embodiments of the present application, the electrolyte can further include an additive, which can include FEC (fluoroethylene carbonate) and / or VC (vinylene carbonate). Adding FEC helps the positive electrode tab to form a stable CEI film and a tough SEI film on the surface of the negative electrode tab, reducing the consumption of more Li caused by the expansion of the silicon-containing material. Adding VC helps to form a stable polycarbonate SEI film on the surface of the negative electrode tab, further improving the cycle performance of the battery.

[0132] In some embodiments of the present application, the electrolyte can further optionally include other additives that can improve certain performance of the battery, such as additives that improve the overcharge performance of the battery, additives that improve the high-temperature performance of the battery, additives that improve the low-temperature performance of the battery, and the like.

[0133] In some embodiments of the present application, the electrolyte further includes an electrolyte salt, which can include a lithium salt.

[0134] In some embodiments of the present application, the electrolyte can include an organic solvent, a lithium salt, and an additive, the organic solvent can include a cyclic carbonate and a linear carbonate, the cyclic carbonate can include EC, the linear carbonate can include one or more of EMC, DMC, DEC, the additive can include FEC and VC, and the lithium salt can include LiPF6.

[0135] It can be understood that the concentration of the lithium salt in the electrolyte and the mass percentage of the additive in the electrolyte can be flexibly selected according to actual needs, which are not particularly limited here.

[0136] [Separator]

[0137] Generally, the battery monomer further includes a separator. The material of the separator in the present application is not particularly limited, and any known porous structure separator with electrochemical stability and mechanical stability can be selected according to actual needs, for example, it can include but is not limited to a single layer or multi-layer film containing at least one of glass fiber, non-woven fabric, polyethylene, polypropylene, and polyvinylidene fluoride.

[0138] In some embodiments of the present application, the side of the separator facing the positive electrode tab can be provided with a ceramic coating containing inorganic oxide, for example, the inorganic oxide can include but is not limited to boehmite. Optionally, the ceramic coating can further include a binder, which can include but is not limited to an acrylate-based binder. The ceramic coating containing inorganic oxide is beneficial to improve the oxidation resistance and high-temperature stability of the separator.

[0139] In some embodiments of the present application, the separator can further be provided with a first adhesive coating, which can be located between the separator and the ceramic coating.

[0140] In some embodiments of the present application, the side of the separator film facing the negative electrode tab can be provided with a second adhesive coating.

[0141] The first adhesive coating and the second adhesive coating can each independently include, but are not limited to, polyvinylidene fluoride (PVDF) and / or polymethyl methacrylate (PMMA). The provision of the first adhesive coating and / or the second adhesive coating is advantageous in saving internal space of the battery and improving the volumetric energy density of the battery.

[0142] In some embodiments of the present application, the total thickness of the separator film can be 7-14 μm, for example, 7 μm, 8 μm, 9 μm, 10 μm, 11 μm, 12 μm, 13 μm or 14 μm, etc. Thereby, it is further advantageous to avoid the risk of reducing the energy density of the battery due to a large thickness of the separator film. Further, the total thickness of the separator film can be 7-10 μm.

[0143] The embodiments of the present application do not have special restrictions on the shape of the battery cell, for example, in some embodiments of the present application, the battery cell can be a soft pack battery, a square battery or a cylindrical battery. As shown in FIG. 1, the battery cell 1 is a square structure as an example.

[0144] In some embodiments of the present application, the battery cell can be a cylindrical battery, which can include a shell, and the shell can include an upper cover, a lower cover and a side wall.

[0145] For example, the thickness of the side wall of the shell can be 0.2-0.4 mm, such as 0.2 mm, 0.25 mm, 0.3 mm, 0.35 mm or 0.4 mm, etc., and optionally 0.25-0.3 mm. Thereby, the side wall of the shell can have a lower thickness and mass, which is advantageous for further improving the energy density of the battery.

[0146] For example, the thickness of the shell wall of the upper cover or the lower cover of the shell can be 0.25-0.45 mm, such as 0.25 mm, 0.3 mm, 0.35 mm, 0.4 mm or 0.45 mm, etc., and optionally 0.27-0.33 mm. Thereby, the upper cover or the lower cover of the shell can have a lower thickness and mass, which is advantageous for further improving the energy density of the battery.

[0147] For example, in a cylindrical battery shell, the upper cover of the shell can be provided with a cap, and the cap can include a pole, and the tab of the positive electrode tab can be connected to the pole through a first current collecting part; the tab of the negative electrode tab can be connected to the shell wall of the lower cover of the shell through a second current collecting part. Optionally, the cap can be a steel cap. The cap structure not only facilitates the welding connection of the cylindrical battery through the current collecting part (such as a current collecting bar), but also facilitates pressure relief after battery failure, and reduces the safety risk of high-nickel high-silicon system batteries due to large gas production caused by thermal runaway.

[0148] In some embodiments, the battery cell can include an outer package. The outer package is used to encapsulate the positive electrode tab, the negative electrode tab, and the electrolyte.

[0149] In some embodiments, the outer package can include a shell and a cover plate. The shell can include a bottom plate and a side plate connected to the bottom plate, and the bottom plate and the side plate enclose a receiving cavity. The shell has an opening communicating with the receiving cavity, and the cover plate can be arranged on the opening to close the receiving cavity.

[0150] The positive electrode tab, the negative electrode tab, and the separator film can form an electrode assembly through a winding process or a stacking process. The electrode assembly is encapsulated in the receiving cavity. The number of electrode assemblies contained in the battery cell can include one or several, which can be adjusted according to requirements.

[0151] In some embodiments, the outer package of the battery cell can include a hard shell, such as a hard plastic shell, an aluminum shell, or a steel shell.

[0152] The outer package of the battery cell can also include a soft package, such as a bag-type soft package. The material of the soft package can be plastic, such as at least one of polypropylene (PP), polybutylene terephthalate (PBT), and polybutylene succinate (PBS).

[0153] The second aspect of the present application provides a battery device, which includes the battery cell of the first aspect of the present application. Optionally, the power consumption device can include at least one of a battery module, a battery pack, and an energy storage device.

[0154] In some embodiments, the battery device can be a battery cell, a battery module, or a battery pack assembled from battery cells. The number of battery cells contained in the battery module or the battery pack can be multiple, and the specific number can be adjusted according to the application and capacity of the battery module.

[0155] FIG. 2 is a battery module 2 as an example. Referring to FIG. 2, in the battery module 2, a plurality of battery cells 1 can be arranged in series along the length direction of the battery module 2. Of course, the plurality of battery cells 1 can be arranged in any other manner. The plurality of battery cells 1 can be further fixed by fasteners. The battery module 2 can further include a housing having an accommodation space in which the plurality of battery cells 1 are accommodated. In some embodiments, the above-described battery module can be assembled into a battery pack, and the number of battery modules included in the battery pack can be adjusted according to the application and capacity of the battery pack.

[0156] FIGS. 3 and 4 are a battery pack 3 as an example. Referring to FIGS. 3 and 4, the battery pack 3 can include a battery case and a plurality of battery modules 2 arranged in the battery case. The battery case includes an upper case 4 and a lower case 5, and the upper case 4 can be arranged on the lower case 5 to form a closed space for accommodating the battery modules 2. The plurality of battery modules 2 can be arranged in the battery case in any manner.

[0157] A third aspect of the present application provides a power consuming device, which includes the battery cell of the first aspect of the present application or the battery device of the second aspect of the present application, and the battery cell or the battery device is used to provide electric energy.

[0158] Specifically, the battery cell or the battery device can be used as a power supply of the power consuming device, or can be used as an energy storage unit of the power consuming device. The power consuming device can include but is not limited to a mobile device (such as a mobile phone, a notebook computer), an electric vehicle (such as a pure electric vehicle, a hybrid electric vehicle, a plug-in hybrid electric vehicle, an electric bicycle, an electric scooter, an electric golf cart, an electric truck), an electric train, a ship and a satellite, and an energy storage system.

[0159] FIG. 5 is a power consuming device as an example. The power consuming device includes a pure electric vehicle, a hybrid electric vehicle, or a plug-in hybrid electric vehicle. As another example of the power consuming device, a mobile phone, a tablet computer, or a notebook computer can be included. The power consuming device generally requires thinning, and a battery cell can be used as a power supply.

[0160] Hereinafter, examples of the present application will be described. The examples described below are exemplary and are intended to explain the present application, and should not be understood as limiting the present application. In the examples, specific techniques or conditions not mentioned are performed according to the techniques or conditions described in the literature in the art or according to the product manual. The reagents or instruments not mentioned by the manufacturer are all conventional products that can be obtained on the market.

[0161] Example 1

[0162] (1) Positive electrode tab

[0163] The positive electrode current collector aluminum foil is provided with positive electrode active material layers on two opposite surfaces, the thickness of the positive electrode active material layers provided on the two surfaces of the aluminum foil is equal, the thickness of the aluminum foil is 17 microns, the thickness ratio of the current collector in the positive electrode tab is 10%, and the single-sided coating area density of the positive electrode active material layer is 25.6 mg / cm 2 The positive electrode active material layer includes, based on the mass of the positive electrode active material layer, 98% of a positive electrode active material (ternary active material lithium nickel cobalt manganese oxide (metal oxide), the molar ratio of nickel cobalt manganese is 0.83:0.11:0.06, the particle size distribution of the positive electrode active material is unimodal distribution, and the particle size corresponding to the peak value of the particle size distribution peak is 8.3 microns), 1.1% of a conductive agent (conductive carbon black Super P), and 0.9% of a binder polyvinylidene fluoride (PVDF).

[0164] (2) Negative electrode tab

[0165] The negative electrode current collector copper foil is provided with negative electrode active material layers on two opposite surfaces, the thickness of the negative electrode active material layers provided on the two surfaces of the copper foil is equal, the thickness of the copper foil is 10 microns, the thickness ratio of the current collector in the negative electrode tab is 5%, and the single-sided coating area density of the negative electrode active material layer is 14 mg / cm 2 The negative electrode active material includes natural graphite and silicon-containing material SiO. Based on the mass of the negative electrode active material layer, it includes 96% of a positive electrode active material (based on the total mass of the negative electrode active material, the mass percentage of silicon in the negative electrode active material is 2.3%), 0.8% of a conductive agent (Super P), 2% of a binder butadiene rubber (SBR), and 1.2 of a thickening agent carboxymethyl cellulose sodium (CMC-Na).

[0166] (3) Electrolyte

[0167] The organic solvent is configured by EC, DMC, and EMC in a mass ratio of 28:36:34, and the electrolyte salt is LiPF6. The concentration of LiPF6 in the electrolyte is 1 mol / L.

[0168] (4) Separator: polyethylene film.

[0169] (5) Battery cell: including the above positive electrode tab, negative electrode tab, separator, and electrolyte.

[0170] Test method:

[0171] (1) Inductively coupled plasma emission spectrometry for elemental composition

[0172] Instrument standard reference EPA6010D-2014 "Inductively Coupled Plasma Atomic Emission Spectrometry". The sample is treated by chemical method to be digested into solution, atomized into plasma to be excited into characteristic spectrum of elements, and the element content is qualitatively and quantitatively analyzed according to the wavelength and intensity (proportional to concentration) of the spectrum.

[0173] (2) Positive active material particle size test

[0174] Equipment model: MasterSizer 2000 laser particle size analyzer, reference standard process: GB / T19077-2016 / ISO 13320:2009, specific test process: take the appropriate amount of sample to be tested (sample concentration to ensure 8-12% obscuration), add 20ml deionized water, and ultrasonic for 5min (53KHz / 120W), ensure that the sample is completely dispersed, then measure the sample according to GB / T19077-2016 / ISO 13320:2009 standard.

[0175] (3) Energy density test

[0176] At 25℃, first measure the length, width and height of the battery monomer (the height of the pole is not included) with a steel ruler, record the volume V, charge to 4.25V at 1 / 3C constant current, then charge to 0.05C at 4.25V constant voltage, stand for 5min, then discharge to 2.5V at 1 / 3C, cycle 3 times, take the discharge energy of the third cycle as W, the volume energy density of the battery monomer = W / V.

[0177] (4) Cycle performance test

[0178] At 25℃, the battery monomer after formation is placed for 30min, and discharged to 2.8V at 1 / 3C constant current. Then follow the steps for charge and discharge cycle: stand for 5min, charge to 4.15V at 1 / 2C constant current, then constant voltage charge to 0.05C; stand for 5min; discharge to 2.8V at 1 / 2C constant current, record the discharge capacity at this time as C0. After 500 cycles, record the discharge capacity C 500 of the 500th cycle. Calculate the capacity retention rate of 500 cycles according to the following formula:

[0179] Capacity retention rate of 500 cycles (%): C 500 / C0x100%.

[0180] (5) High temperature storage performance test

[0181] The battery was charged at a constant current of 1 / 3 C to 4.25 V at 25 °C, then charged at 4.25 V constant voltage until the current dropped to 0.05 C, and then discharged at a constant current of 1 / 3 C to 2.5 V to obtain the pre-storage discharge capacity (C d1 ); then the battery was again charged at a constant current of 1 / 3 C to 4.15 V, and then charged at 4.15 V constant voltage until the current dropped to 0.05 C. Then the battery was placed in a 45 °C constant temperature oven for 150 days, and after taking out, the battery was charged at a constant current of 1 / 3 C to 4.25 V at 25 °C, then charged at 4.25 V constant voltage until the current dropped to 0.05 C, and then discharged at a constant current of 1 / 3 C to 2.5 V to obtain the post-storage discharge capacity (C d2 ). The high-temperature storage capacity retention rate (%) was calculated according to the following formula: C d2 / C d1 x 100%.

[0182] Example 2, Example 3, Example 3, Example 4, Example 5, Comparative Example 1, Comparative Example 2

[0183] The positive electrode sheet and the electrolyte in the battery monomer were the same as in Example 1, and the difference was that in the negative electrode sheet, the mass ratio of the silicon-containing material in the negative electrode active material was different, and the mass ratio of silicon in the negative electrode active material was also different, but the mass ratio of the negative electrode active material in the negative electrode active material layer was the same as in Example 1.

[0184] Example 6

[0185] The positive electrode sheet and the electrolyte in the battery monomer were the same as in Example 1, and the difference was that in the negative electrode sheet, the type of silicon-containing material was different, the silicon-containing material was SiC, and the mass ratio of silicon in the negative electrode active material changed with the silicon-containing material, but the mass ratio of the silicon-containing material in the negative electrode active material was the same as in Example 1.

[0186] Example 7, Example 8, Example 9, Comparative Example 3, Comparative Example 4

[0187] The positive electrode sheet and the electrolyte in the battery monomer were the same as in Example 1, and the difference was that in the negative electrode sheet, the thickness of the negative electrode current collector was different, and the thickness ratio of the negative electrode current collector in the negative electrode sheet was also different.

[0188] The differences between Example 1 to Example 9 and Comparative Example 1 to Comparative Example 4 are shown in Table 1.

[0189] Table 1

[0190] It can be seen from Examples 1 to 9, and Comparative Examples 1 and 2 that the battery cell has both high energy density and cycle capacity retention rate, which indicates that the high-nickel positive active material is used in the positive electrode sheet, the graphite and the silicon-containing material are used in combination in the negative electrode sheet, and the incorporation amount of the silicon-containing material in the negative electrode sheet and the thickness ratio of the current collector in the negative electrode sheet are controlled in the appropriate range, so that the battery cell has both high energy density and long cycle life.

[0191] It can be seen from Examples 1 to 5, Comparative Example 1 and Comparative Example 2 that with the increase of the silicon content in the negative electrode sheet, the volumetric energy density of the battery cell shows a trend of first increasing and then decreasing, while the cycle capacity retention rate and the high-temperature storage performance of the battery cell show a downward trend, which may be caused by the cracking or damage of the active material layer of the negative electrode sheet due to the excessive content of the silicon-containing material. It indicates that controlling the amount of the silicon-containing material in the negative active material in the appropriate range can better balance the energy density and cycle performance of the battery cell, thereby being beneficial to obtaining a longer service life.

[0192] It can be seen from Examples 1, 7 to 9, and Comparative Examples 3 and 4 that with the increase of the thickness ratio of the current collector in the negative electrode sheet, the cycle capacity retention rate and the high-temperature storage performance of the battery cell show a trend of first increasing and then tending to be stable, while the volumetric energy density of the battery cell shows a downward trend. It indicates that appropriately increasing the thickness ratio of the current collector in the negative electrode sheet can not only improve the cycle capacity retention rate of the battery cell, but also take into account the volumetric energy density of the battery cell, so that the battery cell has both high energy density and good cycle performance, which is beneficial to obtaining a longer service life.

[0193] It can be seen from Examples 1 and 6 that using the silicon-carbon material instead of the silicon-oxygen material in combination with the graphite can also improve the energy density of the battery cell.

[0194] Examples 10, 11, 12, 13 and 14

[0195] The battery cell in Example 1, the difference is that in the positive electrode sheet, the thickness of the positive electrode current collector is different, and the thickness ratio of the positive electrode current collector in the positive electrode sheet is also different.

[0196] The differences between Examples 10 to 14 and Example 1 are shown in Table 2.

[0197] Table 2

[0198] It can be seen from Examples 1, 10 to 14 that, with the increase of the thickness ratio of the current collector in the positive electrode sheet, the cycle capacity retention rate and the high-temperature storage performance of the battery cell first increase and then tend to be stable, and the volumetric energy density of the battery cell decreases. It shows that appropriately increasing the thickness ratio of the positive electrode current collector can further improve the cycle capacity retention rate of the battery cell, and the volumetric energy density of the battery cell is also considered, so that the battery cell has high energy density and good cycle performance, which is beneficial to obtain long service life.

[0199] Example 15

[0200] The battery cell is the same as Example 1 in the negative electrode sheet and the electrolyte, and the difference lies in that in the positive electrode sheet, the type of the ternary active material is different, and in Example 15, the ternary active material is lithium nickel cobalt aluminate (metal oxide), and the molar ratio of nickel, cobalt and aluminum in lithium nickel cobalt aluminate is 0.91:0.05:0.04.

[0201] Comparative Example 5

[0202] The battery cell is the same as Example 15 in the electrolyte, and the difference lies in that in the positive electrode sheet, the thickness of the positive electrode current collector is different, and the thickness ratio of the positive electrode current collector in the positive electrode sheet is also different; in the negative electrode sheet, the thickness of the negative electrode current collector is different, and the thickness ratio of the negative electrode current collector in the negative electrode sheet is also different.

[0203] Comparative Example 6, Comparative Example 7

[0204] The battery cell is the same as Example 10 in the positive electrode sheet and the electrolyte, and the difference lies in that in the negative electrode sheet, the mass ratio of the silicon-containing material in the negative electrode active material is different, and the mass ratio of the silicon element in the negative electrode active material is also different, but the mass ratio of the negative electrode active material in the negative electrode active material layer is the same as Example 15.

[0205] The differences of Example 15, Comparative Example 5, Comparative Example 6 and Comparative Example 7 are shown in Table 3.

[0206] Table 3

[0207] Example 16, Example 17, Example 18, Example 19

[0208] The battery cell is the same as Example 1 in the negative electrode sheet and the electrolyte, and the difference lies in that in the positive electrode sheet, the positive electrode active material also adds a lithium supplement agent, that is, the positive electrode active material includes a ternary active material and a lithium supplement agent, but the mass ratio of the positive electrode active material in the positive electrode active material layer is the same as Example 1.

[0209] Comparative Example 8

[0210] The battery monomer is the same as example 1, except that in the positive electrode sheet, the positive active material also adds a lithium supplement, that is, the positive active material includes a ternary active material and a lithium supplement, but the mass percentage of the positive active material in the positive active material layer is the same as that of example 1; in the negative electrode sheet, the negative active material only includes natural graphite and does not contain silicon-containing material, and the mass percentage of silicon element in the negative active material is also different, but the mass percentage of the negative active material in the negative active material layer is the same as that of example 1.

[0211] The differences between example 16, example 17, example 18, example 19 and comparative example 8 and example 1 are shown in table 4.

[0212] Table 4

[0213] As can be seen from example 1, example 16 to example 19, the addition of lithium supplement can obviously improve the cycle capacity retention rate and high temperature storage capacity retention rate of the battery monomer, and with the increase of the amount of lithium supplement, the cycle capacity retention rate and high temperature storage capacity retention rate of the battery monomer also increase, but the energy density of the battery monomer shows a trend of first increasing and then decreasing, the main reason for which is that when the content of lithium supplement is relatively high, the relative amount of ternary active material decreases, and the improvement effect of lithium supplement on the energy density of the battery monomer is not enough to make up for the influence of the decrease of the amount of ternary active material on the energy density of the battery monomer. It is shown that appropriately increasing the amount of lithium supplement is beneficial to further making the battery monomer have higher energy density, better cycle performance and high temperature storage performance. In addition, on the basis of example 16, it can be further illustrated by comparative example 8 that the energy density and cycle performance of the battery monomer can be balanced by adjusting the amount of silicon-containing material in the negative electrode sheet.

[0214] Example 20

[0215] The battery monomer is the same as example 16, except that in the positive electrode sheet, the particle size distribution of the positive active material is different, and the particle size distribution graph of the positive active material in example 20 shows a bimodal distribution, the peak value of the small particle size peak corresponds to a particle size of 1 μm, and the peak value of the large particle size peak corresponds to a particle size of 9 μm.

[0216] Example 21

[0217] The battery monomer is the same as example 16, except that in the negative electrode sheet, the surface of the silicon-containing material is coated with carbon material.

[0218] The differences between example 16, example 20 and example 21 are shown in table 5.

[0219] Table 4

[0220] It can be seen from the combination of Embodiment 16 and Embodiment 20 that the battery monomer energy density is improved when the positive electrode active material particle size distribution chart is bimodal, which indicates that the use of positive electrode active material with different particle sizes in the positive electrode plate is beneficial to further improve the battery monomer with high energy density and good cycle performance, and prolong the service life of the battery monomer.

[0221] It can be seen from the combination of Embodiment 16 and Embodiment 21 that the surface of the silicon-containing material in the negative electrode plate is coated with carbon material, which is beneficial to further improve the energy density and cycle performance of the battery monomer, and in addition, the high-temperature storage performance of the battery monomer is also improved.

[0222] Embodiment 22, Embodiment 23, Embodiment 24, Embodiment 25, Embodiment 26

[0223] The battery monomer is the same as Embodiment 16 in the negative electrode plate and the electrolyte, and the difference is that in the positive electrode plate, the ternary active material lithium nickel cobalt manganese oxide has a doped element.

[0224] Embodiment 27, Embodiment 28

[0225] The battery monomer is the same as Embodiment 16 in the positive electrode plate and the electrolyte, and the difference is that in the negative electrode plate, the silicon-oxygen material has a doped metal element.

[0226] The difference between Embodiments 22 to 28 and Embodiment 16 is shown in Table 6.

[0227] Table 6

[0228] It can be seen from the combination of Embodiment 16 and Embodiments 22 to 26 that doping a small amount of other elements such as Al, Zr, B, etc. in the ternary active material lithium nickel cobalt manganese oxide is beneficial to further improve the cycle performance of the battery monomer.

[0229] It can be seen from the combination of Embodiment 16 and Embodiments 27-28 that doping a small amount of metal elements such as Fe or Co in the silicon-containing material is beneficial to further improve the energy density of the battery.

[0230] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, rather than limit them. Although the present application has been described in detail with reference to the foregoing embodiments, it should be understood by those skilled in the art that the technical solutions recorded in the foregoing embodiments can be modified, or some or all of the technical features can be replaced equivalently. Such modifications or replacements do not change the essence of the corresponding technical solutions, which should be covered in the scope of the claims and the specification of the present application. In particular, the technical features mentioned in each embodiment can be combined in any manner as long as there is no structural conflict. The present application is not limited to the specific embodiments disclosed herein, but includes all technical solutions falling within the scope of the claims.

Claims

1. A battery cell, comprising a positive electrode tab and a negative electrode tab, wherein the positive electrode tab comprises a positive electrode current collector and a positive electrode active material layer disposed on at least one side of the positive electrode current collector, the positive electrode active material layer comprising a positive electrode active material, and the negative electrode tab comprises a negative electrode current collector and a negative electrode active material layer disposed on at least one side of the negative electrode current collector, the negative electrode active material layer comprising a negative electrode active material, wherein the positive electrode active material comprises a nickel-cobalt-manganese metal oxide, a molar percentage of nickel in the nickel-cobalt-manganese metal oxide is 80%-96% based on a total molar amount of nickel-cobalt-manganese elements in the nickel-cobalt-manganese metal oxide, or the positive electrode active material comprises a nickel-cobalt-aluminum metal oxide, a molar percentage of nickel in the nickel-cobalt-aluminum metal oxide is 80%-96% based on a total molar amount of nickel-cobalt-aluminum elements in the nickel-cobalt-aluminum metal oxide; the negative electrode active material comprises graphite and a silicon-containing material, a mass percentage of silicon in the negative electrode active material is 0.1%-10% based on a total mass of the negative electrode active material, and a thickness of the negative electrode current collector is 3%-8% of a total thickness of the negative electrode tab. A mass percentage of silicon in the negative electrode active material is 0.5%-9.5%, optionally 2%-9.5%, based on a total mass of the negative electrode active material. The thickness of the negative electrode current collector is 4%-7% of the total thickness of the negative electrode tab. The thickness of the positive electrode current collector is 7.5%-15%, optionally 10%-13.5%, of a total thickness of the positive electrode tab. The positive electrode active material comprises a nickel-cobalt-manganese metal oxide, a molar percentage of nickel in the nickel-cobalt-manganese metal oxide is 83%-91% based on a total molar amount of nickel-cobalt-manganese elements in the nickel-cobalt-manganese metal oxide; or the positive electrode active material comprises a nickel-cobalt-aluminum metal oxide, a molar percentage of nickel in the nickel-cobalt-aluminum metal oxide is 83%-91% based on a total molar amount of nickel-cobalt-aluminum elements in the nickel-cobalt-aluminum metal oxide.

2. The battery cell of claim 1, wherein, The silicon-containing material comprises a silicon-oxygen material and / or a silicon-carbon material.

3. The battery cell of claim 1 or 2, wherein, A mass percentage of silicon in the negative electrode active material is 2%-6%, optionally 3%-5%, based on a total mass of the negative electrode active material.

4. The battery cell according to any one of claims 1 to 3, wherein, The silicon-containing material further comprises a metal element, the metal element comprising one or more of Na, Li, Ti, Fe, and Co.

5. The battery cell according to any one of claims 1 to 4, wherein, A mass of the metal element is 0.1%-0.6% of a mass of the silicon element. At least part of a surface of the silicon-containing material comprises a carbon coating layer.

6. The battery cell of any one of claims 1-5, wherein, The graphite comprises natural graphite.

7. The battery cell according to any one of claims 1 to 6, wherein, The positive electrode active material comprises a polycrystalline material.

8. The battery cell according to any one of claims 1 to 7, wherein, A particle size distribution of the positive electrode active material is bimodal, and peak values of two peaks correspond to particle sizes of D1 and D2, respectively, 0.5 μm≤D1≤1.5 μm, and 7 μm≤D2≤12 μm.

9. The battery cell of claim 8, wherein, The positive electrode active material further comprises a lithium supplement agent.

10. The battery cell of any one of claims 1-9, wherein, The lithium supplement agent comprises Li2NiO2 and / or Li5FeO4.

11. The battery cell of any one of claims 1-10, wherein, A mass percentage of the lithium supplement agent is 0.5%-5%, optionally 1%-3%, based on a total mass of the positive electrode active material.

12. The battery cell of any one of claims 1-11, wherein, ​ 13. The battery cell of any one of claims 1-12, wherein, ​ 14. The battery cell of any one of claims 1-13, wherein, ​ 15. The battery cell of claim 14, wherein, The lithium supplement agent comprises Li x M y O z , 1≤x≤5, 1≤y≤3, 1≤z≤8, M comprises one or more elements of Ni, Co, V, Cr, Mn, Fe, Mo, Cu, Zn.

16. The battery cell of claim 14 or 15, wherein, ​ 17. The battery cell of claim 14 or 15, wherein, The lithium supplement agent comprises Li n NiO m and / or Li p FeO q wherein 0≤n≤2, 0 18. The battery cell of claim 14 or 15, wherein, The lithium supplement agent comprises NiO m and / or Li p FeO q wherein 0 < m < 2, 0 < p < 1, and 0 < q < 2.

19. The battery cell of any one of claims 14-18, wherein, ​ 20. The battery cell of any one of claims 1-19, wherein, The positive electrode active material comprises a nickel-cobalt-manganese metal oxide, the nickel-cobalt-manganese metal oxide comprises one or more elements of Na, K, Mg, B, Al, Si, P, S, Ca, Sc, Ti, V, Cr, Fe, Cu, Zn, Sr, Y, Zr, Nb, Mo, Cd, Sn, Sb, Te, Ba, Ta, W, Yb, La, Ce, F, and optionally comprises one or more elements of Al, Zr, B, P, Ti.

21. The battery cell of claim 20, wherein, The nickel-cobalt-manganese metal oxide comprises Al, and the mass percentage of the Al in the positive electrode active material is 0.01% to 0.1% based on the total mass of the positive electrode active material.

22. The battery cell of claim 20 or 21, wherein, The nickel-cobalt-manganese metal oxide comprises Zr, and the mass percentage of the Zr in the positive electrode active material is 0.1% to 0.5% based on the total mass of the positive electrode active material.

23. The battery cell of any one of claims 20-22, wherein, The nickel-cobalt-manganese metal oxide comprises B, and the mass percentage of the B in the positive electrode active material is 0.01% to 0.15% based on the total mass of the positive electrode active material.

24. The battery cell of any one of claims 20-23, wherein, The nickel-cobalt-manganese metal oxide comprises P, and the mass percentage of the P in the positive electrode active material is 0.05% to 0.2% based on the total mass of the positive electrode active material.

25. The battery cell of any one of claims 1-24, wherein, The single-sided coating area density of the positive electrode active material layer is 20 mg / cm 2 ~ 30 mg / cm 2 .

26. The battery cell of any one of claims 1-25, wherein, The compacted density of the positive electrode active material layer is 3.3 g / cm 3 ~ 3.6 g / cm 3 .

27. The battery cell of any one of claims 1-26, wherein, The thickness of the positive electrode current collector is 13 μm to 19 μm, and is optionally 15 μm to 17 μm.

28. The battery cell of any one of claims 1-27, wherein, The single-sided coating area density of the negative electrode active material layer is 10 mg / cm 2 ~ 18 mg / cm 2 , and can be 13 mg / cm 2 ~ 15 mg / cm 2 .

29. The battery cell of any one of claims 1-28, wherein, The compacted density of the negative active material layer is 1.3 g / cm 3 ~ 1.7 g / cm 3 , and can be 1.4 g / cm 3 ~ 1.55 g / cm 3 .

30. The battery cell of any one of claims 1-29, wherein, The thickness of the negative electrode current collector is 6 μm to 13 μm, and is optionally 8 μm to 11 μm.

31. The battery cell of any one of claims 1-30, wherein, Further comprising: An electrolyte, the electrolyte comprises an organic solvent, the organic solvent comprises a cyclic carbonate and a linear carbonate.

32. The battery cell of claim 31, wherein, The cyclic carbonate comprises EC and / or PC, and the linear carbonate comprises one or more of EMC, DMC, and DEC.

33. The battery cell of claim 31 or 32, wherein, The mass percentage of the cyclic carbonate is 15% to 25% based on the total mass of the electrolyte, and the mass percentage of the linear carbonate is 50% to 70% based on the total mass of the electrolyte.

34. The battery cell of any one of claims 31-33, wherein, The electrolyte further comprises an additive, the additive comprises FEC and / or VC.

35. The battery cell of any one of claims 1-34, wherein, Further comprising: A separator film, a ceramic coating layer comprising an inorganic oxide is arranged on one side of the separator film facing the positive electrode tab.

36. The battery cell of claim 35, wherein, The separator film is further provided with a first adhesive coating layer between the separator film and the ceramic coating layer.

37. The battery cell of claim 35 or 36, wherein, A second adhesive coating layer is arranged on one side of the separator film facing the negative electrode tab.

38. The battery cell of any one of claims 35-37, wherein, The total thickness of the separator film is 7 μm to 14 μm, and is optionally 7 μm to 10 μm.

39. The battery cell of any one of claims 1-38, wherein, The battery cell is a cylindrical battery, the cylindrical battery comprises a shell, the shell comprises an upper cover, a lower cover, and a side wall, the thickness of the side wall is 0.2 mm to 0.4 mm, and is optionally 0.25 mm to 0.3 mm.

40. The battery cell of claim 39, wherein, The thickness of the shell wall of the upper cover or the lower cover is 0.25 mm to 0.45 mm, and is optionally 0.27 mm to 0.33 mm.

41. A battery device, wherein, The battery cell of any one of claims 1 to 40, the use device comprises at least one of a battery module, a battery pack, and an energy storage device.

42. An electrical device, comprising: The battery cell of any one of claims 1 to 40 or the battery device of claim 41, the battery cell or the battery device is used to provide electrical energy.

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