Battery monomer, preparation method thereof and power utilization device

Abstract

The invention discloses a battery monomer, a preparation method thereof and an electric device. The battery monomer comprises a positive electrode plate, the positive electrode plate comprises a positive electrode current collector and a positive electrode film layer, the positive electrode film layer comprises a first film layer and a second film layer, the first film layer comprises a first lithium supplementing material, the first lithium supplementing material comprises a first metal oxide, the chemical formula of the first metal oxide meets Lia1M1Oc1, M1 comprises one or more of V, Nb, Cr, Mo, Fe, Co or Sn; the second film layer comprises a second lithium supplementing material, the second lithium supplementing material comprises a second metal oxide, the chemical formula of the second metal oxide meets Lia2Ni1-bM2bOc2, and M2 comprises one or more of Cu, Co, Mg, Zn, Mn, Al, Zr, Ti or Fe; and the first film layer is positioned between the positive current collector and the second film layer. According to the technical scheme, the cycle performance of the battery monomer can be improved, and gas production in the battery monomer is reduced.

Description

Technical Field

[0001] This application relates to the field of battery technology, and more specifically, to a battery cell, a method for preparing the same, and an electrical device thereof. Background Technology

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

[0003] Battery technology development requires consideration of various design factors, such as energy density, cycle life, capacity, and reliability. As a lithium replenishment material, metal oxides can provide active lithium ions to the battery to compensate for lithium ion consumption during formation and other stages, thereby improving the battery's long-term cycle performance. However, metal oxides also exhibit significant gas generation after delithiation. Therefore, how to provide a battery cell with less gas generation and better cycle performance is a pressing technical problem that needs to be solved. Summary of the Invention

[0004] This application is made in view of the above-mentioned problems, and its purpose is to provide a battery cell with less gas production and better cycle performance.

[0005] To achieve the above objectives, this application provides a battery cell, a method for preparing the same, and an electrical device thereof.

[0006] In a first aspect, a battery cell is provided, comprising: a positive electrode sheet, the positive electrode sheet including a positive current collector and a positive electrode film layer, the positive electrode film layer being disposed on at least one surface of the positive current collector, the positive electrode film layer including a first film layer and a second film layer; the first film layer including a first lithium supplementation material, the first lithium supplementation material including a first metal oxide, the first metal oxide having the chemical formula satisfying: Li a1 M 1 O c1 , 2.8≤a1≤8.2, 1.8≤c1≤6.2, M 1 The second film layer includes one or more of V, Nb, Cr, Mo, Fe, Co, or Sn; the second lithium-replenishing material includes a second metal oxide, the chemical formula of which satisfies: Li a2 Ni 1-b M 2 b O c2 1 <a2≤2.2,0≤b<1,1.8≤c2≤2.2,M 2 It includes one or more of Cu, Co, Mg, Zn, Mn, Al, Zr, Ti, or Fe; wherein the first film layer is located between the positive electrode current collector and the second film layer.

[0007] In this embodiment, the battery cell includes a positive electrode sheet, which includes a positive current collector and a positive electrode film layer disposed on at least one side of the positive current collector. The positive electrode film layer includes a first film layer and a second film layer. The first film layer includes a first lithium replenishment material, and the second film layer includes a second lithium replenishment material. Both the first and second lithium replenishment materials can provide lithium ions, thereby facilitating the replenishment of lithium ions consumed in the battery cell and improving the first charge capacity and cycle performance of the battery cell. The first lithium replenishment material includes a first metal oxide, and the chemical formula of the first metal oxide satisfies: Li a1 M 1 O c1 , 2.8≤a1≤8.2, 1.8≤c1≤6.2, M 1 The second lithium supplement material includes one or more of V, Nb, Cr, Mo, Fe, Co, or Sn; the second lithium supplement material includes a second metal oxide, the chemical formula of which satisfies: Li a2 Ni 1-b M 2 b O c2 1 <a2≤2.2,0≤b<1,1.8≤c2≤2.2,M 2 The electrode comprises one or more of Cu, Co, Mg, Zn, Mn, Al, Zr, Ti, or Fe, with the first film layer located between the positive electrode current collector and the second film layer. By coating the first film layer on the positive electrode current collector and the second film layer on the first film layer, i.e., the second metal oxide is closer to the electrolyte than the first metal oxide, on the one hand, the oxygen generated during the delithiation of the first metal oxide can be easily adsorbed by the second metal oxide; on the other hand, the dissolved oxygen in the electrolyte can also be bound by the second metal oxide, avoiding side reactions between oxygen and the electrolyte. Therefore, the positive electrode sheet of this embodiment can improve the cycle performance of the battery cell while reducing gas generation in the battery cell.

[0008] In one possible implementation, the molar ratio C of the first metal oxide and the second metal oxide satisfies: 1:1 ≤ C ≤ 10:1. Thus, when C ≥ 1:1, the first metal oxide has a higher proportion than the second metal oxide, which is beneficial for improving the cycle performance of the battery cell; when C ≤ 10:1, the second metal oxide has a suitable proportion, which is beneficial for reducing the amount of gas generated in the battery cell.

[0009] In one possible implementation, the molar ratio C of the first metal oxide and the second metal oxide satisfies: 3:1 ≤ C ≤ 5:1. Thus, by ensuring 3:1 ≤ C ≤ 5:1, it is beneficial to both reduce the gas production of individual battery cells and improve their cycle performance, thereby further balancing both gas production and cycle performance.

[0010] In one possible implementation, based on the total mass of the first film layer, the mass content P1 of the first metal oxide satisfies: 0.05wt% ≤ P1 ≤ 20wt%; and / or based on the total mass of the second film layer, the mass content P2 of the second metal oxide satisfies: 0.05wt% ≤ P2 ≤ 20wt%. This is beneficial for both improving the cycle performance of the battery cell and reducing the gas production of the battery cell.

[0011] In one possible implementation, based on the total mass of the first film layer, the mass content P1 of the first metal oxide satisfies: 0.1wt% ≤ P1 ≤ 5wt%; and / or based on the total mass of the second film layer, the mass content P2 of the second metal oxide satisfies: 0.1wt% ≤ P2 ≤ 5wt%. This allows for a further balance between gas generation and cycle performance of the battery cells.

[0012] In one possible implementation, the volume average particle size of the second metal oxide is greater than or equal to the volume average particle size of the first metal oxide. This helps to further reduce the amount of gas generated by the battery cells during the aging stage after formation.

[0013] In one possible implementation, the volume average particle size Dv50 of the first metal oxide 1 Satisfies: 0.1μm≤Dv50 1 ≤20μm, further, the average volumetric particle size Dv50 of the first metal oxide 1 Satisfies: 0.5μm≤Dv50 1 ≤5μm. This helps improve the cycle performance of individual battery cells.

[0014] In one possible implementation, the volume average particle size Dv50 of the second metal oxide 2 Satisfies: 0.1μm≤Dv50 2 ≤10μm, further, the volume average particle size Dv50 of the second metal oxide 2 Satisfies: 0.5μm≤Dv50 2 ≤5μm. This helps reduce the amount of gas produced by individual battery cells.

[0015] In one possible implementation, the first metal oxide comprises one or more of the following: Li3VO4, Li3NbO4, Li3CrO4, Li3MoO4, Li5FeO4, Li5CrO4, Li5VO4, Li5MoO4, Li6CoO4, Li6VO4, Li6CrO4, Li6MoO4, or Li8SnO6. In this way, the first metal oxide can release a greater number of lithium ions, thereby providing more active lithium ions to the battery cell, compensating for the consumption of active ions in the battery cell, and contributing to improved long-cycle performance of the battery cell.

[0016] In one possible implementation, the first metal oxide comprises Li5FeO4. Li5FeO4 has a high molar content of lithium, which can release more lithium ions, resulting in a significant improvement in the long-cycle performance of the battery cell.

[0017] In one possible implementation, the second metal oxide includes Li2NiO2 and Li2Ni. 0.5 Cu 0.5 O2 or Li2Ni 0.8 Cu 0.2 One or more of O2. When the second metal oxide includes Li2NiO2, it can further balance the gas production and cycle performance of the battery cell; the second metal oxide includes Li2Ni 0.5 Cu 0.5 O2 or Li2Ni 0.8 Cu 0.2 O2 can improve the conductivity of the second metal oxide, which in turn helps to improve the long-term cycle performance of the battery cell.

[0018] In one possible implementation, the first lithium replenishing material comprises the first metal oxide and an oxide and / or carbon material located on the surface of the first metal oxide; and / or, the second lithium replenishing material comprises the second metal oxide and an oxide and / or carbon material located on the surface of the second metal oxide.

[0019] The above configuration not only improves the conductivity of the first and / or second lithium replenishment materials, but also reduces the side reactions caused by the exposure of the first and / or second metal oxides, thereby improving the first charge capacity and cycle performance of the battery cell.

[0020] In one possible implementation, the oxide comprises a metal element, including one or more of Ni, W, Cu, Mn, Al, Fe, Ti, Mo, Ce, Co, Cr, or V. Oxides comprising the aforementioned metal elements exhibit good electrical conductivity, which is beneficial for improving the conductivity of the first and / or second lithium replenishment materials, thereby improving the cycle performance of the battery cell.

[0021] In one possible implementation, the oxide comprises Al2O3. This is beneficial for improving the conductivity of the first and / or second lithium replenishment materials, thereby improving the first-cycle charge capacity and cycle performance of the battery cell.

[0022] In one possible implementation, in the first lithium replenishment material, based on the total mass of the first lithium replenishment material, the mass content D1 of the oxide satisfies: 0.1 wt% ≤ D1 ≤ 10 wt%, and / or, the mass content E1 of the carbon material satisfies: 0.1 wt% ≤ E1 ≤ 10 wt%; and / or, in the second lithium replenishment material, based on the total mass of the second lithium replenishment material, the mass content D2 of the oxide satisfies: 0.1 wt% ≤ D2 ≤ 10 wt%, and / or, the mass content E2 of the carbon material satisfies: 0.1 wt% ≤ E2 ≤ 10 wt%. By setting the mass content of the oxide and / or the mass content of the carbon material to meet the above ranges, the conductivity of the first lithium replenishment material and / or the second lithium replenishment material, as well as the amount of lithium ions released, can be balanced, which is beneficial to improving the long-term cycle performance of the battery cell.

[0023] In one possible implementation, in the first lithium replenishment material, based on the total mass of the first lithium replenishment material, the mass content D1 of the oxide satisfies: 0.5wt% ≤ D1 ≤ 5wt%, and / or, the mass content E1 of the carbon material satisfies: 0.5wt% ≤ E1 ≤ 5wt%; and / or, in the second lithium replenishment material, based on the total mass of the second lithium replenishment material, the mass content D2 of the oxide satisfies: 0.5wt% ≤ D2 ≤ 5wt%, and / or, the mass content E2 of the carbon material satisfies: 0.5wt% ≤ E2 ≤ 5wt%. This is beneficial for further improving the cycle performance of the battery cells.

[0024] In one possible implementation, the carbon material includes one or more of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, or carbon nanofibers. This is beneficial for improving the conductivity of the first and / or second lithium replenishment materials and for reducing side reactions caused by the exposure of lithium metal oxides and / or second metal oxides, thereby improving the cycle performance of the battery cell.

[0025] In one possible implementation, both the second film layer and the second film layer further include a positive electrode active material, wherein the volume average particle size of the positive electrode active material is Dv50. 3 Satisfies: 0.1μm≤Dv50 3 ≤10μm. By setting the volume average particle size of the positive electrode active material within the above range, the positive electrode active material, the first lithium supplement material, and the second lithium supplement material have a better particle size distribution, which is beneficial to improving the long-term cycle performance of the battery cell.

[0026] In one possible implementation, the positive electrode active material comprises a lithium-containing phosphate with an olivine structure, wherein the lithium-containing phosphate with the olivine structure includes lithium iron phosphate. This results in a more stable positive electrode active material, which is beneficial for improving the long-term performance and lifespan of the battery cell.

[0027] In one possible implementation, the battery cell is a pre-formation battery cell. After the formation process, lithium ions are released from the first lithium-replenishing material and the second lithium-enriching material in the positive electrode of the battery cell, thereby improving the cycle performance of the battery cell.

[0028] In a second aspect, a method for preparing a battery cell is provided, comprising: providing a positive electrode sheet to prepare the battery cell; wherein providing the positive electrode sheet comprises: coating a first film layer on at least one side of the surface of a positive current collector, wherein the first film layer comprises a first lithium supplementation material, the first lithium supplementation material comprises a first metal oxide, and the chemical formula of the first metal oxide satisfies: Li a1 M 1 O c1 , 2.8≤a1≤8.2, 1.8≤c1≤6.2, M 1 The first film layer is coated with a second film layer on at least one side of the surface of the first film layer, wherein the second film layer includes a second lithium-supplementing material, the second lithium-supplementing material includes a second metal oxide, and the chemical formula of the second metal oxide satisfies: Li a2 Ni 1-b M 2 b O c2 1 <a2≤2.2,0≤b<1,1.8≤c2≤2.2,M 2 It includes one or more of Cu, Co, Mg, Zn, Mn, Al, Zr, Ti, or Fe.

[0029] The above-mentioned positive electrode preparation method is relatively simple and has low preparation complexity; and when the prepared positive electrode is applied to a battery cell, the battery cell has good cycle performance and low gas production.

[0030] Thirdly, an electrical device is provided, comprising a battery cell as described in the first aspect and any possible implementation thereof, and / or a battery cell obtained by the preparation method of the second aspect.

[0031] In one possible implementation, the electrical device includes an energy storage device or a heavy-duty truck. Energy storage devices and heavy-duty trucks have high requirements for the lifespan and long-term cycle performance of individual battery cells; applying individual battery cells to these electrical devices can improve their lifespan. Attached Figure Description

[0032] To more clearly illustrate the technical solutions of the embodiments of this application, the drawings used in the embodiments of this application will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on the drawings without creative effort.

[0033] Figure 1 This is a schematic diagram of the structure of the positive electrode sheet according to one embodiment of this application;

[0034] Figure 2 This is a schematic diagram of a battery cell according to one embodiment of this application;

[0035] Figure 3 This is a schematic diagram of a method for preparing a battery cell according to an embodiment of this application;

[0036] Figure 4 This is a schematic diagram of a battery according to one embodiment of this application;

[0037] Figure 5 This is a schematic diagram of an electrical device according to one embodiment of this application;

[0038] Figure 6 This is a schematic diagram of an electrical device according to one embodiment of this application. Detailed Implementation

[0039] The positive electrode sheet and its preparation method, as well as the embodiments of the battery cell, of this application have been described in detail with appropriate reference to the accompanying drawings. However, unnecessary detailed descriptions may be omitted. For example, detailed descriptions of well-known matters and repetitive descriptions of practically identical structures may be omitted. This is to avoid unnecessarily lengthy descriptions and to facilitate understanding by those skilled in the art. Furthermore, the accompanying drawings and the following description are provided to enable those skilled in the art to fully understand this application and are not intended to limit the subject matter of the claims.

[0040] The "range" disclosed in this application is defined by a lower limit and an upper limit. A given range is defined by selecting a lower limit and an upper limit, which define the boundaries of a particular range. Ranges defined in this way can include or exclude endpoints and can be arbitrarily combined; that is, any lower limit can be combined with any upper limit to form a range. For example, if ranges of 60-120 and 80-110 are listed for a specific parameter, it is expected that ranges of 60-110 and 80-120 are also included. Furthermore, if minimum range values ​​of 1 and 2 are listed, and if maximum range values ​​of 3, 4, and 5 are listed, then the following ranges are all expected: 1-3, 1-4, 1-5, 2-3, 2-4, and 2-5. In this application, unless otherwise stated, the numerical range "ab" represents a shortened representation of any combination of real numbers between a and b, where a and b are real numbers. For example, the numerical range "0-5" indicates that all real numbers between "0-5" have been listed in this article; "0-5" is simply a shortened representation of these numerical combinations. Furthermore, when a parameter is stated as an integer ≥2, it is equivalent to disclosing that the parameter is, for example, an integer such as 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0041] Unless otherwise specified, all embodiments and optional embodiments of this application can be combined to form new technical solutions.

[0042] Unless otherwise specified, all technical features and optional technical features of this application may be combined to form new technical solutions.

[0043] Unless otherwise specified, all steps in this application may be performed sequentially or randomly, preferably sequentially. For example, the method includes steps (a) and (b), indicating that the method may include steps (a) and (b) performed sequentially, or it may include steps (b) and (a) performed sequentially. For example, the mention that the method may also include step (c) indicates that step (c) may be added to the method in any order. For example, the method may include steps (a), (b), and (c), or it may include steps (a), (c), and (b), or it may include steps (c), (a), and (b), etc.

[0044] The development of battery technology needs to consider various design factors simultaneously. For example, energy density, cycle life, discharge capacity, charge-discharge rate, reliability, initial charge capacity, etc. During the formation of the solid electrolyte interface (SEI) film of a battery cell, about 10% of the active lithium is consumed, and the consumption of active lithium is not conducive to improving the capacity of the battery cell. Adding a certain amount of lithium supplement material to the battery cell can supplement active lithium. For example, adding metal oxides to the positive electrode sheet to supplement active lithium, thereby improving the cycle performance of the battery cell during long cycles. However, during the charging process, some metal oxides with high oxygen content can contain more lithium ions due to the electronegativity of oxygen. When de-lithiated, they will release more active lithium ions to supplement more capacity, so more oxygen will be released. This will damage the structural stability of the positive electrode film layer, and the oxygen will dissolve in the electrolyte and react with the electrolyte during subsequent charging processes (such as the aging stage after formation), which will further cause obvious gas generation in the battery cell, which is not conducive to improving the performance of the battery cell.

[0045] In view of the above problems, an embodiment of the present application provides a battery cell, including: a positive electrode sheet, the positive electrode sheet includes a first film layer and a second film layer, the first film layer includes a first lithium supplement material, the first lithium supplement material includes a first metal oxide, and the chemical formula of the first metal oxide satisfies: Li a1 M 1 O c1 , 2.8 ≤ a1 ≤ 8.2, 1.8 ≤ c1 ≤ 6.2, M 1 includes one or more of V, Nb, Cr, Mo, Fe, Co or Sn; the second film layer includes a second lithium supplement material, the second lithium supplement material includes a second metal oxide, and the chemical formula of the second metal oxide satisfies: Li a2 Ni 1-b M 2 b O c2 , 1 < a2 ≤ 2.2, 0 ≤ b < 1, 1.8 ≤ c2 ≤ 2.2, M2 includes one or more of Cu, Co, Mg, Zn, Mn, Al, Zr, Ti or Fe; wherein, the first film layer is located between the positive electrode current collector and the second film layer. By first coating the first lithium supplement material and then coating the second lithium supplement material on the first lithium supplement material, it is beneficial to improve the cycle performance of the battery cell while reducing the gas generation of the battery cell during the aging stage, and thus is beneficial to improving the performance of the battery cell.

[0046] The first and second lithium replenishing materials in the embodiments of this application are used as lithium replenishing agents to compensate for the irreversible lithium loss caused during SEI film formation. During the charging process of the battery cell, lithium ions are extracted from the first and second lithium replenishing materials to provide active lithium ions.

[0047] During the charging process of a single battery cell, lithium ions are released from the positive electrode active material, move and embed into the negative electrode; while during the discharging process, lithium ions are released from the negative electrode, move and embed into the positive electrode active material.

[0048] It should be understood that the “intercalation” process described in this application refers to the process by which lithium ions are intercalated into the positive electrode active material or the negative electrode due to an electrochemical reaction, and the “extraction” and “deintercalation” processes described in this application refer to the process by which lithium ions are extracted from the positive electrode active material or the negative electrode due to an electrochemical reaction.

[0049] In the embodiments of this application, formation can be understood as the initialization of a battery cell, which is the process of activating the active material of the battery cell; it can also be understood as a process of charging the battery cell, and formation helps to form the SEI film in the battery cell.

[0050] In the embodiments of this application, aging can refer to the process of leaving the battery cells at room temperature or high temperature after formation. The aging process helps the SEI structure to reorganize and form a loose and porous film, which is beneficial to make the voltage of the battery cells more accurate and stable, and also helps the electrolyte to fully wet the electrode.

[0051] In this application's embodiments, a single battery cell can refer to the smallest structural unit of a battery. Multiple battery cells can first be assembled into a battery module, and then the battery module can be assembled into a battery; multiple battery cells can also be directly assembled into a battery.

[0052] [Battery cell]

[0053] This application provides a battery cell including a positive electrode.

[0054] Figure 1 This is a schematic diagram of the structure of the positive electrode sheet according to one embodiment of this application. For example, as shown... Figure 1 As shown, the positive electrode 1 includes a positive current collector 10 and a positive electrode film layer 11 disposed on at least one side surface of the positive current collector 10.

[0055] The positive current collector 10 has two opposing surfaces along its thickness direction. The positive electrode film layer 11 can be disposed on one surface of the positive current collector 10 or on both surfaces of the positive current collector 10. As an example, such as... Figure 1 As shown, the positive electrode film layer 11 is disposed on both sides of the positive electrode current collector 10.

[0056] The positive electrode film layer 11 includes a first film layer 110 and a second film layer 120. The first film layer 110 includes a first lithium replenishing material, and the second film layer 120 includes a second lithium replenishing material. The first lithium replenishing material and the second lithium replenishing material are different lithium replenishing materials.

[0057] The first and second lithium replenishment materials have a high molar lithium content, allowing for the release of more lithium ions to compensate for irreversible lithium loss. For example, the molar lithium content in both materials is greater than 1.

[0058] The first lithium supplement material includes a first metal oxide, the chemical formula of which satisfies: Li a1 M 1 O c1 , 2.8≤a1≤8.2, 1.8≤c1≤6.2, M 1 It includes one or more of V, Nb, Cr, Mo, Fe, Co, or Sn.

[0059] Specifically, a1 can be 2.8, 3, 4, 5, 6, 7, 8, 8.2 or any value within the above range, and c1 can be 1.8, 2, 3, 4, 5, 6, 6.2 or any value within the above range.

[0060] The second lithium supplement material includes a second metal oxide, the chemical formula of which satisfies: Li a2 Ni 1- b M 2 b O c2 1 <a2≤2.2,0≤b<1,1.8≤c2≤2.2,M 2 It includes one or more of Cu, Co, Mg, Zn, Mn, Al, Zr, Ti, or Fe.

[0061] Specifically, a2 can be 1.04, 1.2, 1.5, 1.8, 2, 2.2 or any value within the above range, b can be 0.3, 0.4, 0.5, 0.8, 1 or any value within the above range, and c2 can be 1.8, 2, 2.2 or any value within the above range.

[0062] Specifically, when b is 0, the transition metal element in the second metal oxide is mainly Ni; when b is greater than 0, the second metal oxide is also doped with other transition metal elements, such as Cu, Co, Mg, Zn, etc.

[0063] The second metal oxide can be a layered material, where layered structure refers to a layered crystal lattice structure. In the layered structure of the second metal oxide, lithium oxide occupies one layer, metal oxide occupies one layer, and excess lithium occupies the metal oxide layer.

[0064] In some embodiments, the first metal oxide includes Li5FeO4 and the second metal oxide includes Li2NiO2.

[0065] The first membrane layer 110 is located between the positive electrode current collector 10 and the second membrane layer 120.

[0066] That is, compared to the first membrane layer 110, the second membrane layer 120 is farther away from the positive electrode current collector 10; or compared to the second membrane layer 120, the first membrane layer 110 is closer to the positive electrode current collector 10.

[0067] During the charging process of a battery cell, the first metal oxide releases oxygen after lithium removal. For example, during the formation process of a battery cell, the first metal oxide removes lithium and releases oxygen. Although the oxygen can be extracted using a degassing device during the formation stage, some oxygen still dissolves in the electrolyte. During the aging stage after formation, the oxygen reacts with the electrolyte to produce gas. This not only leads to longer manufacturing time and higher costs for the battery cell, but also reduces the stability of the positive electrode film, the reliability of the battery cell, and the yield rate during later use. In addition, the oxygen produced by the first metal oxide oxidizes the solvent in the electrolyte, further generating oxidizing gases, thus triggering a series of gas-generating reactions, ultimately leading to a reduction in the lifespan of the battery cell.

[0068] Setting a first lithium replenishing material and a second lithium replenishing material in the positive electrode not only achieves the lithium replenishment effect, but also reduces gas production in the aging stage of the battery cell after formation. This can be explained by the following possible mechanisms: (1) During the charging process of the battery cell, lithium occupying the metal oxide layer in the second metal oxide is unstable and easily detaches. After detachment, the lithium leaves vacancies, forming vacancy clusters, which capture oxygen in the surface lattice structure, reducing the problem caused by oxygen generated by the first lithium replenishing material's lithium depletion; (2) Nickel ions in the second metal oxide can also react with oxygen dissolved in the electrolyte, thereby absorbing oxygen. It should be noted that the above mechanisms are only used to explain the reasons for reduced gas production in the battery cell and are not a limitation on the battery cell.

[0069] It should be noted that during the charging and discharging process of the battery, Li undergoes insertion / extraction and consumption, resulting in different molar contents of Li at different discharge states. In the examples of the first lithium replenishment material, the second lithium replenishment material, and the positive electrode active material in this application, the molar contents of Li refer to the initial state of the material, i.e., the state before feeding. When the positive electrode material is applied to the battery system, the molar contents of Li will change after charge-discharge cycles. Similarly, in the examples of the first lithium replenishment material, the second lithium replenishment material, and the positive electrode active material in this application, the molar contents of O are only theoretical values. Oxygen release from the crystal lattice will cause changes in the molar contents of oxygen, resulting in fluctuations in the actual molar contents of O.

[0070] In the above scheme, the battery cell includes a positive electrode 1, which includes a positive current collector 10 and a positive electrode film 11 disposed on at least one side of the surface of the positive current collector 10. The positive electrode film 11 includes a first film 110 and a second film 120; the first film 110 includes a first lithium replenishment material, which includes a first metal oxide, the chemical formula of which satisfies: Li a1 M 1 O c1 , 2.8≤a1≤8.2, 1.8≤c1≤6.2, M 1 The second film layer 120 includes one or more of V, Nb, Cr, Mo, Fe, Co, or Sn; the second lithium-replenishing material includes a second metal oxide, the chemical formula of which satisfies: Li a2 Ni 1-b M 2 b O c2 1 <a2≤2.2,0≤b<1,1.8≤c2≤2.2,M 2 The first film layer 110 comprises one or more of Cu, Co, Mg, Zn, Mn, Al, Zr, Ti, or Fe; wherein the second film layer 120 is disposed on at least one side of the surface of the first film layer 110 away from the positive electrode current collector 10. This improves the cycle performance of the battery cell and reduces gas generation within the battery cell; furthermore, because the second metal oxide is closer to the electrolyte, it also reduces side reactions between oxygen and the electrolyte.

[0071] In some embodiments, the molar ratio C of the first metal oxide and the second metal oxide satisfies: 1:1 ≤ C ≤ 10:1.

[0072] Specifically, the molar ratio C of the first metal oxide and the second metal oxide can be 1:1, 2:1, 3:1, 4:1, 5:1, 6:1, 7:1, 8:1, 9:1, 10:1 or any value within the above range.

[0073] The higher the molar ratio C of the first metal oxide and the second metal oxide, the more lithium ions can be provided, which is beneficial to improving the cycle performance of the battery cell. However, as the molar ratio C increases, the content of the second metal oxide is lower, and less oxygen can be adsorbed, resulting in a weaker improvement in gas production in the battery cell.

[0074] In the above scheme, when C≥1:1, the first metal oxide has a higher proportion than the second metal oxide, which is beneficial to improving the cycle performance of the battery cell; when C≤10:1, the second metal oxide has a suitable proportion, which is beneficial to reducing the risk of excessive oxygen due to the low proportion of the second metal oxide, thereby reducing the oxygen content dissolved in the electrolyte and the battery cell has less gas production.

[0075] In some embodiments, the molar ratio C of the first metal oxide and the second metal oxide satisfies: 3:1 ≤ C ≤ 5:1.

[0076] In the above scheme, by making 3:1≤C≤5:1, it is beneficial to reduce the gas production of the battery cells and improve the cycle performance of the battery cells, thus further balancing the gas production and cycle performance of the battery cells.

[0077] In some embodiments, based on the total mass of the first film layer 110, the mass content P1 of the first metal oxide satisfies: 0.05wt% ≤ P1 ≤ 20wt%; and / or based on the total mass of the second film layer 120, the mass content P2 of the second metal oxide satisfies: 0.05wt% ≤ P2 ≤ 20wt%.

[0078] When the molar ratio of the first metal oxide and the second metal oxide is satisfied, the greater the proportion of the first metal oxide in the first film layer 110, the more lithium ions are provided, which is beneficial to improving the cycle performance of the battery cell. The greater the proportion of the second metal oxide in the second film layer 120, the more oxygen can be adsorbed, which is also more effective in improving the gas production of the battery cell.

[0079] Furthermore, in some embodiments, based on the total mass of the first film layer 110, the mass content P1 of the first metal oxide satisfies: 0.1wt% ≤ P1 ≤ 5wt%; and / or based on the total mass of the second film layer 120, the mass content P2 of the second metal oxide satisfies: 0.1wt% ≤ P2 ≤ 5wt%.

[0080] In the above scheme, by making the first metal oxide and the second metal oxide have appropriate proportions in the first film layer 110 and the second film layer 120, respectively, the battery cell can take into account both gas production and cycle performance.

[0081] In some embodiments, the volume average particle size of the second metal oxide is greater than or equal to the volume average particle size of the first metal oxide.

[0082] Specifically, as an example, the volume average particle size of the first metal oxide is smaller than that of the second metal oxide. This facilitates a more uniform mixing of the first and second metal oxides, and allows the oxygen generated by the first metal oxide to be adsorbed more readily. This reduces the risk of generating excessive amounts of other gases within the battery cell due to the presence of oxygen, thereby reducing the risk of gas on the electrode surface hindering lithium-ion intercalation and lowering the risk of black spots appearing on the electrode.

[0083] In the above scheme, by making the volume average particle size of the second metal oxide greater than or equal to the volume average particle size of the first metal oxide, it is beneficial to further reduce the risk of the battery cell generating more gas during the aging process due to the presence of oxygen, and to further reduce the amount of gas generated by the battery cell during the aging process.

[0084] In some embodiments, the volume average particle size Dv50 of the first metal oxide 1 Satisfies: 0.1μm≤Dv50 1 ≤20μm.

[0085] Dv50 can refer to the particle size at which the cumulative particle size distribution number (DV50) of a sample reaches 50%, meaning that particles smaller than DV50 account for 50% of the total particle size distribution. Here, Dv50... 1 This is to be compatible with the Dv50 below. 2 To distinguish them, the volume average particle size is indicated.

[0086] Specifically, the volume average particle size Dv50 of the first metal oxide 1 It can be 0.1μm, 2μm, 5μm, 8μm, 10μm, 15μm, 20μm or any value within the above range.

[0087] In Dv50 1 When the particle size is greater than or equal to 0.1 μm, the risk of agglomeration between the first metal oxide particles can be reduced, which is beneficial for a more uniform distribution of the first lithium supplement material in the positive electrode film layer. The oxygen generated by the first metal oxide is also more uniformly distributed, thus helping to reduce the amount of gas produced within the battery cell; in Dv50 1 When the thickness is less than or equal to 20 μm, the path length for lithium ions to escape from the first metal oxide is more suitable, which is conducive to the extraction and diffusion of lithium ions, thereby improving the cycle performance of the battery cell.

[0088] In the above embodiments, by ensuring that 0.1μm ≤ Dv50 1With a diameter of ≤20μm, the battery cells produce less gas during the aging stage after formation and have better cycle performance.

[0089] In some embodiments, the average volumetric particle size Dv50 of the first metal oxide 1 It satisfies: 0.5μm≤Dv501≤5μm.

[0090] In Dv50 1 When the particle size is greater than or equal to 0.5 μm, the risk of agglomeration between the first metal oxide particles can be reduced, which is beneficial for a more uniform distribution of the first metal oxide in the positive electrode film layer and for reducing gas generation in the battery cell; in Dv50 1 When the thickness is less than or equal to 5 μm, the path length for lithium ions to escape from the first metal oxide is more suitable, which is conducive to the extraction and diffusion of lithium ions. Furthermore, the first metal oxide has a lower resistivity, which is beneficial to improving the first charge capacity and cycle performance of the battery cell.

[0091] In the above scheme, by setting 0.5μm≤Dv50 1 A depth of ≤5μm helps reduce gas production in individual battery cells, thereby improving the initial charge capacity and cycle performance of the battery cells.

[0092] In some embodiments, the volume average particle size Dv50 of the second metal oxide 2 Satisfies: 0.1μm≤Dv50 2 ≤10μm.

[0093] Specifically, the volume average particle size Dv50 of the second metal oxide 2 It can be 0.1μm, 0.5μm, 1μm, 2μm, 4μm, 4.5μm, 5μm, 5.6μm, 6μm, 6.2μm, 7.5μm, 8.8μm, 10μm or any value within the above range.

[0094] In Dv50 2 When the particle size is greater than or equal to 0.1 μm, the risk of agglomeration between the particles of the second metal oxide can be reduced, which is beneficial for a more uniform distribution of the second metal oxide in the positive electrode film layer and for reducing the amount of gas generated by the battery cell during the formation stage; in Dv50 2 When the thickness is less than or equal to 10 μm, the path length for lithium ions to escape from the second metal oxide is more suitable, which is conducive to the extraction of lithium ions and thus helps to improve the long-term cycle performance of the battery cell.

[0095] In the above embodiments, by making 0.1μm≤Dv50 2 With a diameter of ≤10μm, the battery cells have a high initial charge capacity and low gas production.

[0096] In some embodiments, the volume average particle size Dv50 of the second metal oxide 2 Satisfies: 0.5μm≤Dv50 2 ≤5μm. This results in better cycle performance for individual battery cells and less gas production during the aging process.

[0097] In some embodiments, the volume average particle size of the first metal oxide is smaller than that of the second metal oxide, 0.1 μm ≤ Dv50. 1 ≤20μm and 0.1μm≤Dv50 2 With a thickness of ≤10μm, the battery cells produce less gas during the aging process and exhibit better cycle performance.

[0098] In some embodiments, the volume average particle size of the first metal oxide is smaller than that of the second metal oxide, 0.5 μm ≤ Dv50. 1 ≤5μm and 0.5μm≤Dv50 2 With a diameter of ≤5μm, the battery cells produce less gas during the aging process and have better cycle performance.

[0099] In some embodiments, the first metal oxide includes one or more of Li3VO4, Li3NbO4, Li3CrO4, Li3MoO4, Li5FeO4, Li5CrO4, Li5VO4, Li5MoO4, Li6CoO4, Li6VO4, Li6CrO4, Li6MoO4, or Li8SnO6.

[0100] The aforementioned first metal oxide can release more lithium ions, thereby providing more active lithium ions to the battery cell, compensating for the consumption of active ions in the battery cell, and helping to improve the long-term cycle performance of the battery cell.

[0101] In some embodiments, the first metal oxide comprises Li5FeO4. Li5FeO4 has a high molar lithium content, which allows for the release of more lithium ions, resulting in a significant improvement in the cycle performance of the battery cell. Furthermore, Li5FeO4 is easy to apply and compatible with slurry preparation processes and the operating voltage of the battery cell. In addition, compared to Li6CoO4 and Li6MnO4, the use of Li5FeO4 results in less gas generation and better cycle performance in the battery cell.

[0102] In some embodiments, the second metal oxide includes Li2NiO2 and Li2Ni. 0.5 Cu 0.5 O2 or Li2Ni 0.8 Cu 0.2 One or more of O2.

[0103] In the above scheme, including Li2NiO2 as the second metal oxide can further balance the gas production of the battery cell and the cycle performance of the battery cell; including Li2Ni 0.5 Cu 0.5 O2 or Li2Ni 0.8 Cu 0.2 O2 helps improve the conductivity of the second metal oxide, which in turn helps improve the long-term cycle performance of the battery cell.

[0104] In some embodiments, the first lithium replenishing material includes a first metal oxide and an oxide and / or carbon material located on the surface of the first metal oxide; and / or, the second lithium replenishing material includes a second metal oxide and an oxide and / or carbon material located on the surface of the second metal oxide.

[0105] As one example, the first lithium replenishing material includes a first metal oxide and an oxide on the surface of the first metal oxide; as another example, the first lithium replenishing material includes a first metal oxide and a carbon material on the surface of the first metal oxide; as yet another example, the first lithium replenishing material includes a first metal oxide and a carbon material and an oxide on the surface of the first metal oxide.

[0106] As one example, the second lithium replenishing material includes a second metal oxide and an oxide located on the surface of the second metal oxide; as another example, the second lithium replenishing material includes a second metal oxide and a carbon material located on the surface of the second metal oxide; as yet another example, the second lithium replenishing material includes a second metal oxide and a carbon material and an oxide located on the surface of the second metal oxide.

[0107] Oxide and / or carbon materials may be located on a portion of the surface of the first metal oxide and / or the second metal oxide, or they may be located on the entire surface of the first metal oxide and / or the second metal oxide.

[0108] As one example, the first lithium replenishing material includes carbon material and / or oxides located on the surface of the first metal oxide, and the second lithium replenishing material does not include carbon material and / or oxides located on the surface of the second metal oxide; as another example, the first lithium replenishing material does not include carbon material and / or oxides located on the surface of the first metal oxide, and the second lithium replenishing material includes carbon material and / or oxides located on the surface of the second metal oxide; as yet another example, the first lithium replenishing material includes carbon material and / or oxides located on the surface of the first metal oxide, and the second lithium replenishing material includes carbon material and / or oxides located on the surface of the second metal oxide.

[0109] The oxide can be an oxide that includes a metal element, such as aluminum oxide; the carbon material can be one or more of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0110] The inclusion of carbon materials and / or oxides can reduce the risk of reaction between the first metal oxide and / or the second metal oxide and water, and reduce the risk of side reactions, which is beneficial to improving the cycle performance of the battery cell. Carbon materials and / or oxides can also serve as fillers to fill the pores in the first metal oxide caused by delithiation and oxygen release, thereby improving the stability of the cathode film and enhancing the cycle performance of the battery cell. Furthermore, carbon materials can improve the conductivity of the first oxide and / or the second oxide, which is beneficial to increasing the first-cycle charging capacity of the battery cell.

[0111] In some embodiments, the oxide includes a metal element, which may be one or more of Ni, W, Cu, Mn, Al, Fe, Ti, Mo, Ce, Co, Cr, or V. Oxides containing the aforementioned metal elements have good electrical conductivity, which is beneficial for improving the conductivity of the first and / or second lithium replenishment materials, thereby improving the cycle performance of the battery cell.

[0112] In some embodiments, the oxide includes Al2O3. This is beneficial for improving the conductivity of the first and / or second lithium replenishment materials, thereby improving the cycle performance of the battery cell.

[0113] In some embodiments, in the first lithium replenishment material, based on the total mass of the first lithium replenishment material, the mass content of oxide D1 satisfies: 0.1 wt% ≤ D1 ≤ 10 wt%, and / or, the mass content of carbon material E1 satisfies: 0.1 wt% ≤ E1 ≤ 10 wt%; and / or, in the second lithium replenishment material, based on the total mass of the second lithium replenishment material, the mass content of oxide D2 satisfies: 0.1 wt% ≤ D2 ≤ 10 wt%, and / or, the mass content of carbon material E2 satisfies: 0.1 wt% ≤ E2 ≤ 10 wt%.

[0114] Specifically, D1 can be 0.1wt%, 1wt%, 2wt%, 5wt%, 8wt%, 10wt%, or any value within the above range, and E1 can be 0.1wt%, 1wt%, 2wt%, 5wt%, 8wt%, 10wt%, or any value within the above range.

[0115] Specifically, D2 can be 0.1wt%, 1wt%, 2wt%, 5wt%, 8wt%, 10wt%, or any value within the above range, and E2 can be 0.1wt%, 1wt%, 2wt%, 5wt%, 8wt%, 10wt%, or any value within the above range.

[0116] By setting the mass content of oxides and / or carbon materials to meet the above range, the conductivity of the first and / or second lithium replenishment materials as well as the amount of lithium ions released can be taken into account, which is beneficial to improving the cycle performance of the battery cell.

[0117] In some embodiments, in the first lithium replenishment material, based on the total mass of the first lithium replenishment material, the mass content D1 of the oxide satisfies: 0.5wt% ≤ D1 ≤ 5wt%, and / or, the mass content E1 of the carbon material satisfies: 0.5wt% ≤ E1 ≤ 5wt%; and / or, in the second lithium replenishment material, based on the total mass of the second lithium replenishment material, the mass content D2 of the oxide satisfies: 0.5wt% ≤ D2 ≤ 5wt%, and / or, the mass content E2 of the carbon material satisfies: 0.5wt% ≤ E2 ≤ 5wt%. This is beneficial for further improving the cycle performance of the battery cells.

[0118] In some embodiments, the carbon material includes one or more of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, or carbon nanofibers.

[0119] In the above scheme, by including carbon materials in the first film layer 110 and the second film layer 120, it is beneficial to improve the conductivity of the first lithium replenishment material and / or the second lithium replenishment material, and to reduce the side reactions caused by the exposure of lithium metal oxide and / or the second metal oxide, thereby improving the cycle performance of the battery cell.

[0120] In some embodiments, the positive electrode film 11 further includes a positive electrode active material, the positive electrode active material having a volume average particle size Dv50. 3 Satisfies: 0.1μm≤Dv50 3 ≤10μm.

[0121] Specifically, Dv50 3 It can be 1μm, 3μm, 5μm, 7μm, 10μm or any value within the above range.

[0122] In Dv50 3 With a particle size ≥0.1μm, the risk of agglomeration of the positive electrode active material can be reduced, and the positive electrode active material, the first lithium supplement material, and the second lithium supplement material can be mixed more uniformly, which is beneficial for reducing gas generation in the battery cell and improving the cycle performance of the battery cell; in Dv50 3 In the case of ≤10μm, lithium ions have a suitable transport path, which is conducive to the transport and diffusion of lithium ions, and the battery cell has good cycle performance.

[0123] In the above scheme, by setting the volume average particle size of the positive electrode active material within the above range, the positive electrode active material, the first lithium replenishment material and the second lithium replenishment material have a better particle size matching, which is conducive to adsorbing oxygen generated by the first lithium replenishment material while releasing more lithium ions, and is conducive to improving the first charge capacity of the battery cell and the long-term cycle performance.

[0124] In some embodiments, the positive electrode active material includes a lithium phosphate with an olivine structure, wherein the lithium phosphate with the olivine structure includes lithium iron phosphate. This results in a more stable positive electrode active material, which is beneficial for improving the long-term performance and lifespan of the battery cell.

[0125] Lithium-containing phosphates with an olivine structure may also include one or more of lithium manganese iron phosphate, lithium iron phosphate, and lithium titanate.

[0126] The positive electrode active material may include one or more of the following: a layered lithium-containing transition metal oxide and a spinel-structured lithium salt.

[0127] Layered lithium-containing transition metal oxides can include ternary materials such as lithium nickel cobalt manganese oxide and manganese-based materials. For example, ternary materials can be LiNi. 0.8 Co 0.1 Mn 0.1 O2, LiNi 0.6 Co 0.2 Mn 0.2 O2. For example, other metallic elements can be doped into ternary materials to improve certain properties. For instance, Zr, Al, and other materials can be doped.

[0128] Lithium-containing phosphates with an olivine structure may also include one or more of lithium manganese phosphate and lithium iron manganese phosphate.

[0129] Spinel-structured lithium salts can include lithium manganese oxide.

[0130] In some embodiments, the battery cell further includes an electrolyte comprising a solvent, an electrolyte salt, and additives, including any one or a combination of at least two of vinylene carbonate (VC), vinyl sulfate (DTD), fluoroethylene carbonate (FEC), or propane lactone (PS). This facilitates the formation of an SEI film of suitable thickness on the surface of the positive and negative electrode active material particles during the formation process, while reducing lithium consumption during formation and improving the long-term cycle stability and lifespan of the battery after formation.

[0131] In some implementations, based on the total mass of the electrolyte, the mass content K of the additive satisfies: 0.05wt% ≤ K ≤ 20wt%. This ensures that the additive in the electrolyte has an appropriate mass content, which is beneficial for improving the long-term cycle performance and lifespan of the battery cells.

[0132] In some embodiments, the battery cell is the battery cell before formation. After the formation process, the first and second lithium replenishing materials in the positive electrode of the battery cell release more lithium ions, thereby improving the cycle performance of the battery cell.

[0133] In the embodiments of this application, after formation and aging processes, compared with battery cells that do not use the positive electrode sheet of this application, the battery cells of this application have better cycle performance and smaller volume expansion. After the aging process, the smaller volume expansion is beneficial to improving the yield of battery cells and to making battery cells more reliable in later use. Better cycle performance is beneficial to improving the service life of battery cells.

[0134] As an example, when the first metal oxide includes Li5FeO4, it delithigates into LiFeO2; when the second metal oxide includes Li2NiO2, it delithigates into Li2O and NiO. After the battery cell undergoes formation, the presence of Li5FeO4 and Li2NiO2 in the positive electrode can be determined by detecting LiFeO2, Li2O, and NiO within the battery cell. Furthermore, the first and second lithium-adding materials added to the positive electrode can be determined by observing the pores left on the positive electrode after the decomposition of the first and second metal oxides and the size of these pores.

[0135] This application does not impose any particular limitation on the shape of the battery cell; it can be cylindrical, square, or any other arbitrary shape. The battery cell can be a lithium-ion battery, a lithium-sulfur battery, a sodium-ion battery, a magnesium-ion battery, etc.

[0136] Figure 2 This is a schematic diagram of a battery cell according to one embodiment of this application. For example, such as... Figure 2 As shown, the battery cell 3 is a square battery cell. The battery cell 3 includes a housing 31, an end cap assembly 32, and an electrode assembly 33 disposed in the housing 31.

[0137] The electrode assembly 33 can be made from a positive electrode, a negative electrode, and a separator through a winding process or a stacking process.

[0138] End cap assembly 32 includes electrode terminals 322, such as Figure 2 As shown, the end cap assembly 32 includes two electrode terminals 322, one of which is a positive electrode terminal and the other is a negative electrode terminal.

[0139] The battery cell 3 also includes a current collector 34, which is used to connect the tab 331 of the electrode assembly 33 and the electrode terminal 322. For example, in the case where the electrode 1 in this embodiment is a positive electrode, one current collector 34 is used to connect the tab of the positive electrode and the positive electrode terminal, and another current collector 34 is used to connect the tab of the negative electrode and the negative electrode terminal.

[0140] In some embodiments, the battery cell 3 includes an electrode assembly 33, which includes an electrode assembly body 330 and a tab 331 extending from the electrode assembly body 330.

[0141] In some embodiments, the battery cell 3 can be assembled into a battery module, and the number of battery cells 3 contained in the battery module can be one or more, the specific number of which can be selected by those skilled in the art according to the application and capacity of the battery module.

[0142] [Positive electrode plate]

[0143] The positive electrode current collector 10 can be a metal foil or a composite positive electrode current collector. For example, the positive electrode current collector can be an aluminum foil.

[0144] The composite positive electrode current collector may include a polymer material substrate and a metal layer formed on at least one surface of the polymer material substrate. The composite positive electrode current collector can be formed by forming a metal material (aluminum, aluminum alloy, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy, etc.) on a polymer material substrate (such as a substrate of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).

[0145] The positive electrode film layer 11 may also optionally include a binder. As an example, the binder may include one or more of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), PVDF-tetrafluoroethylene-propylene terpolymer, PVDF-hexafluoropropylene-tetrafluoroethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer, and fluorinated acrylate resin.

[0146] The positive electrode film 11 may optionally include a conductive agent. The conductive agent may be selected from one or more of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0147] [Negative electrode plate]

[0148] The negative electrode includes a negative current collector and a negative electrode film layer disposed on the negative current collector.

[0149] The negative electrode current collector can be a metal foil or a composite negative electrode current collector. The negative electrode current collector can be copper foil. Composite negative electrode current collectors can be formed by depositing metallic materials (copper, copper alloys, nickel, nickel alloys, titanium, titanium alloys, silver, and silver alloys, etc.) onto a polymer substrate (such as polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).

[0150] The negative electrode film layer includes a negative electrode active material. The negative electrode active material can be any negative electrode active material known in the art for use in batteries. As an example, the negative electrode active material may include one or more of the following materials: artificial graphite, natural graphite, soft carbon, hard carbon, silicon-based materials, tin-based materials, and lithium titanate, etc. The silicon-based material may be selected from one or more of elemental silicon, silicon oxide compounds, silicon-carbon composites, silicon-nitrogen composites, and silicon alloys. The tin-based material may be selected from one or more of elemental tin, tin oxide compounds, and tin alloys. However, this application is not limited to these materials, and other conventional materials that can be used as negative electrode active materials for batteries may also be used. These negative electrode active materials may be used alone or in combination of two or more.

[0151] The negative electrode film layer may also optionally include a binder. As an example, the binder may include one or more of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), PVDF-tetrafluoroethylene-propylene terpolymer, PVDF-hexafluoropropylene-tetrafluoroethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer, and fluorinated acrylate resins.

[0152] The negative electrode film may optionally include a conductive agent. The conductive agent may be selected from one or more of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0153] [Electrolytes]

[0154] The electrolyte acts as a conductor of ions between the positive and negative electrodes. This application does not impose specific limitations on the type of electrolyte; it can be selected according to requirements. For example, the electrolyte can be liquid, gel-like, or entirely solid.

[0155] In some embodiments, the electrolyte is an electrolyte solution. The electrolyte solution includes an electrolyte salt and a solvent.

[0156] Electrolyte salts may include one or more of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium perchlorate, lithium hexafluoroarsenate, lithium bis(fluorosulfonyl)imide, lithium bis(trifluoromethanesulfonyl)imide, lithium trifluoromethanesulfonate, lithium difluorophosphate, lithium difluorooxalate borate, lithium dioxalate borate, lithium difluorodioxalate phosphate, and lithium tetrafluorooxalate phosphate.

[0157] Solvents may include one or more of the following: ethylene carbonate, propylene carbonate, methyl ethyl carbonate, diethyl carbonate, dimethyl carbonate, dipropyl carbonate, methyl propyl carbonate, ethyl propyl carbonate, butyl carbonate, fluoroethylene carbonate, methyl formate, methyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, propyl propionate, methyl butyrate, ethyl butyrate, 1,4-butyrolactone, sulfolane, dimethyl sulfone, methyl ethyl sulfone, and diethyl sulfone.

[0158] The electrolyte may also optionally include negative electrode film-forming additives, positive electrode film-forming additives, and performance additives that can improve certain battery performance, such as performance additives that improve battery overcharge performance, battery high temperature or low temperature performance, etc.

[0159] [Isolation membrane]

[0160] The separator is used to separate the positive electrode and the negative electrode. This application does not impose any particular limitation on the type of separator; any known porous separator with good chemical and mechanical stability can be selected.

[0161] The material of the separator can be selected from one or more of glass fiber, non-woven fabric, polyethylene, polypropylene, and polyvinylidene fluoride. The separator can be a single-layer film or a multi-layer composite film; there are no particular restrictions. When the separator is a multi-layer composite film, the materials of each layer can be the same or different; there are no particular restrictions.

[0162] Positive electrode, negative electrode and separator can be made into electrode assembly by winding process or stacking process.

[0163] [Preparation methods for battery cells]

[0164] Figure 3 This is a schematic diagram of a method for preparing a battery cell according to an embodiment of this application. (In conjunction with...) Figure 3 As shown, the electrode preparation method 200 may include the following steps.

[0165] Step 210: Provide a positive electrode sheet to prepare a battery cell.

[0166] The provision of the positive electrode includes: coating a first film layer on at least one side of the surface of the positive current collector, wherein the first film layer includes a first lithium replenishment material, the first lithium replenishment material includes a first metal oxide, and the chemical formula of the first metal oxide satisfies: Li a1 M 1 O c1 , 2.8≤a1≤8.2, 1.8≤c1≤6.2, M 1The first film layer is coated with a second film layer on at least one side of the surface of the first film layer, wherein the second film layer includes a second lithium-supplementing material, the second lithium-supplementing material includes a second metal oxide, and the chemical formula of the second metal oxide satisfies: Li a2 Ni 1-b M 2 b O c2 1 <a2≤2.2,0≤b<1,1.8≤c2≤2.2,M 2 It includes one or more of Cu, Co, Mg, Zn, Mn, Al, Zr, Ti, or Fe.

[0167] In the process of preparing the positive electrode sheet, positive active material, binder, conductive agent and solvent can also be added, and after mixing, a slurry of the first film layer or the second film layer is obtained.

[0168] As an example, a slurry of a first film layer and a second film layer are sequentially coated on both sides of the current collector to prepare a positive electrode sheet.

[0169] In some embodiments, after step 210, the positive electrode sheet, negative electrode sheet, and separator can be prepared into an electrode assembly by winding or stacking, and then the electrode assembly is placed into a housing to prepare a battery cell.

[0170] In the battery cell preparation method of this application embodiment, a first coating containing a first lithium replenishing material is first applied, followed by a second coating containing a second lithium replenishing material. This not only provides better lithium replenishment and improves the cycle performance of the battery cell, but also reduces gas generation during the aging stage after formation, thereby reducing the amount of gas generated in the battery cell and improving its long-term cycle performance. Furthermore, this preparation method does not require sintering of the first and second lithium replenishing materials, making the preparation method relatively simple and less complex.

[0171] [Battery]

[0172] This application provides a battery, including the battery cell described in the above embodiments. The battery cell can be a battery cell after formation and aging processes. Figure 4 This is a schematic diagram of a battery according to one embodiment of this application. Figure 4 As shown, battery 5 may include multiple battery cells (not shown in the figure).

[0173] Battery cells 3 can be directly assembled into battery 5, or they can be first assembled into battery modules, and then multiple battery modules can be assembled into battery 5.

[0174] [Electrical appliances]

[0175] This application provides an electrical device, including the battery described in the above embodiments.

[0176] In some embodiments, the electrical device includes an energy storage device or a heavy-duty truck. Energy storage devices and heavy-duty trucks have high requirements for the lifespan and long-term cycle performance of battery cells. Applying battery cells to the aforementioned electrical devices can improve the lifespan of the electrical devices.

[0177] Electrical devices can also be lighting devices, spacecraft, etc., and the embodiments of this application include, but are not limited to, these.

[0178] Figure 5 This is a schematic diagram of an electrical device according to one embodiment of this application. Figure 5 As shown, this application provides an electrical device, which is a heavy-duty truck 6. The battery in the heavy-duty truck 6 can be replaced by a battery swapping device to replace the battery with insufficient power with a fully charged battery.

[0179] Figure 6 This is a schematic diagram of an electrical device according to one embodiment of this application. Figure 6 As shown, this application provides an electrical device, which is an energy storage device 7, and the energy storage device 7 may include multiple batteries 5. The energy storage device 7 can be applied to a power storage station to store and release electrical energy.

[0180] The following describes embodiments of this application. The embodiments described below are exemplary and are only used to explain this application, and should not be construed as limiting this application. Where specific techniques or conditions are not specified in the embodiments, they are performed according to the techniques or conditions described in the literature in this field or according to the product instructions. Reagents or instruments used, unless otherwise specified, are all conventional products that can be obtained commercially.

[0181] [Example]

[0182] [Example 1]

[0183] (1) Preparation of positive electrode sheet

[0184] (1.1) Preparation of the first film layer: The positive electrode active material lithium iron phosphate, the first metal oxide Li5FeO4, the binder polyvinylidene fluoride (PVDF) and the conductive carbon black are mixed evenly in a mass ratio of 90:6:2:2, dissolved in the solvent N-methylpyrrolidone (NMP), and stirred and mixed evenly to prepare the first film layer slurry.

[0185] (1.2) Preparation of the second film layer: The positive electrode active material lithium iron phosphate, the second metal oxide Li2NiO2, the binder polyvinylidene fluoride (PVDF) and the conductive carbon black are mixed evenly in a mass ratio of 96:1:2:2, and then dissolved in the solvent N-methylpyrrolidone (NMP). After being stirred and mixed evenly, the second film layer slurry is prepared.

[0186] (1.3) Preparation of positive electrode sheet: The first film layer slurry is uniformly coated on the two opposite surfaces of the positive current collector aluminum foil, and the second film layer slurry is uniformly coated on the two opposite surfaces of the first film layer. After drying, cold pressing and cutting, the positive electrode sheet is obtained.

[0187] The molar ratio of the first metal oxide to the second metal oxide is 5:1; the mass percentage of the first metal oxide Li5FeO4 in the positive electrode film is 6%; the mass percentage of the second metal oxide Li2NiO2 in the positive electrode film is 1%; and the volume average particle size Dv50 of the first lithium supplementation material is... 1 The volume average particle size Dv50 of the second lithium replenishment material is 9.9 μm. 2 The carbon material has a particle size of 4.7 μm, a carbon material content of 2.5 wt% (E1), a carbon material content of 1.5% (E2), and a volume average particle size (Dv50) of 4.7 μm. 3 It is 1μm.

[0188] (2) Preparation of negative electrode sheet: The negative electrode active material artificial graphite, conductive agent acetylene black, binder styrene-butadiene rubber (SBR) and thickener sodium carboxymethyl cellulose (CMC-Na) are dissolved in deionized water at a mass ratio of 96:1.5:1.5:1.0 and mixed thoroughly to prepare a negative electrode slurry; the negative electrode slurry is coated on the negative electrode current collector copper foil, and then dried, cold pressed and cut to obtain the negative electrode sheet.

[0189] (3) Separation membrane: A polyethylene membrane with a thickness of 13μm is used.

[0190] (4) Preparation of electrolyte: Ethyl carbonate (EC), diethyl carbonate (DEC) and dimethyl carbonate (DMC) are mixed in a volume ratio of 1:1:1, and then LiPF6 is uniformly dissolved in the above solution to obtain an electrolyte with a concentration of 1 mol / L of LiPF6.

[0191] (5) Preparation of lithium-ion battery: The above positive electrode sheet, separator and negative electrode sheet are stacked and wound in sequence to obtain electrode assembly; the electrode assembly is placed in outer packaging, the electrolyte prepared above is added, and after encapsulation, standing, formation and aging processes, a battery cell is obtained.

[0192] [Example 2]

[0193] The difference between Example 2 and Example 1 is that the molar ratio of the first metal oxide and the second metal oxide is 10:1.

[0194] [Example 3]

[0195] The difference between Example 3 and Example 1 is that the molar ratio of the first metal oxide and the second metal oxide is 3:1.

[0196] [Example 4]

[0197] The difference between Example 4 and Example 1 is that the molar ratio of the first metal oxide and the second metal oxide is 1:1.

[0198] [Example 4]

[0199] The difference between Example 4 and Example 1 is that the molar ratio of the first metal oxide and the second metal oxide is 1:1.

[0200] [Example 5]

[0201] The difference between Example 5 and Example 1 is that the second metal oxide is Li. 1.04 NiO2.

[0202] [Example 6]

[0203] The difference between Example 6 and Example 1 is that the particle size of the DV50 positive electrode active material is 2 μm.

[0204] [Example 7]

[0205] The difference between Example 7 and Example 1 is that the particle size of the DV50 positive electrode active material is 4 μm.

[0206] [Comparative Example 1]

[0207] The difference between Comparative Example 1 and Example 1 is that the second metal oxide is not included.

[0208] [Comparative Example 2]

[0209] The difference between Comparative Example 2 and Example 1 is that the second film layer, which includes the second metal oxide, is disposed between the current collector and the first film layer.

[0210] Table 1. Specific parameters of Examples 1-7 and Comparative Examples 1-2

[0211]

[0212] The following is a brief description of the testing methods for the physicochemical and performance parameters involved in the embodiments of this application. It should be understood that the following testing methods are only examples, and other testing methods known in the art can also be used for testing.

[0213] 1. Testing of gas production during aging

[0214] After formation, the battery cells were left to stand at 45°C for 48 hours, and the gas production during aging was measured. The aging gas production can be obtained using infrared spectroscopy or water displacement methods. Specifically, the volume before and after standing can be measured using the water displacement method, and the gas production is calculated based on the volume change. The aging gas production is ΔM / (ρ 液 ×Q), where ΔM is the mass of the drained water, ρ 液 Let Q be the density of the liquid, and Q be the capacity of a single battery cell.

[0215] 2. Cyclic capacity retention test

[0216] Within a voltage range of 2.5V to 3.65V and 25℃, the battery is charged at a 0.1C rate to the voltage limit, then charged at a constant voltage until the current is ≤0.05mA. After resting for 2 minutes, it is discharged at a 0.1C rate to 2.5V. The initial capacity at this point is Q1. After the nth cycle, the capacity measured using the same process is Qn. The cycle capacity retention rate is (1-(Qn / Q1)^(1 / n))×100%, where Qn is the battery capacity after the nth cycle, Q1 is the initial battery capacity, and n is the number of cycles.

[0217] 3. Identification of the first metal oxide and the second metal oxide

[0218] As an example, the positive electrode sheet of a single battery cell before formation is used as a sample. A scanning electron microscope is used to observe the positive electrode sheet, and the particle size can be used to distinguish the first metal oxide, the second metal oxide, and the positive electrode active material. Then, the positive electrode film layer can be scraped off, and the scraped material is added to aqua regia and digested under mechanical stirring for 30 minutes. The digested solution is then added to an ICAP7400 spectrometer to quantitatively analyze the mass fraction of each element in the material. The mass content of the first and second metal oxides is calculated based on the mass fraction of each element.

[0219] As another example, the specific types and mass content of the first metal oxide and the second metal oxide are determined by the raw materials added in the preparation method.

[0220] 4. Test of volume average particle size

[0221] The volume average particle size Dv50 can be determined by measuring the raw materials used to prepare the positive electrode sheet. For example, it can be determined by laser particle size analyzer according to GB / T 19077-2016 Particle Size Distribution Laser Diffraction Method.

[0222] In addition, the positive electrode sheet can be observed using a scanning electron microscope. A specific area can be selected, and the volume average particle size can be calculated based on the size and number of particles observed in that area.

[0223] Table 2 Test results of Examples 1-7 and Comparative Examples 1-2

[0224] Aging gas production (ml / Ah) 1000-cycle capacity retention Example 1 0.25 96.70％ Example 2 0.85 92.50％ Example 3 0.23 94.80％ Example 4 0.21 95.20％ Example 5 0.68 93.50％ Example 6 0.31 95.90％ Example 7 0.36 96.10％ Comparative Example 1 2.17 90.50％ Comparative Example 2 1.68 91.10％

[0225] As can be seen from Examples 1-7 and Comparative Example 1, adding a second metal oxide to the positive electrode film layer can effectively reduce the amount of gas generated in the battery and improve the battery's capacity retention rate, that is, improve the battery's cycle performance.

[0226] As can be seen from Examples 1-7 and Comparative Example 2, placing the second film layer, which includes the second metal oxide, above the first film layer, i.e., the first film layer is located between the current collector and the second film layer, makes the second film layer closer to the electrolyte, which is beneficial to further reduce the amount of gas generated in the battery and improve the cycle performance.

[0227] As can be seen from Examples 1-4, by maintaining the molar ratio of the first metal oxide and the second metal oxide at 1:1-10:1, the battery produces less gas and has better cycle performance.

[0228] As can be seen from Examples 1 and 5, various second metal oxides can reduce battery gas production.

[0229] It should be noted that this application is not limited to the above-described embodiments. The above embodiments are merely examples, and any embodiments with the same structure and effect as the technical concept within the scope of this application are included in the technical scope of this application. Furthermore, various modifications that can be conceived by those skilled in the art to the embodiments, and other ways of constructing by combining some of the constituent elements of the embodiments, without departing from the spirit of this application, are also included in the scope of this application.

Claims

1. A battery cell, characterized in that, include: A positive electrode sheet, the positive electrode sheet comprising a positive current collector and a positive electrode film layer, the positive electrode film layer being disposed on at least one side surface of the positive current collector, the positive electrode film layer comprising a first film layer and a second film layer; The first film layer includes a first lithium replenishing material, which includes a first metal oxide, the chemical formula of which satisfies: Li a1 M 1 O c1 , 2.8≤a1≤8.2, 1.8≤c1≤6.2, M 1 Including one or more of V, Nb, Cr, Mo, Fe, Co, or Sn; The second film layer includes a second lithium replenishing material, which includes a second metal oxide, the chemical formula of which satisfies: Li a2 Ni 1-b M 2 b O c2 1 <a2≤2.2,0≤b<1,1.8≤c2≤2.2,M 2 Including one or more of Cu, Co, Mg, Zn, Mn, Al, Zr, Ti, or Fe; The first membrane layer is located between the positive electrode current collector and the second membrane layer.

2. The battery cell according to claim 1, characterized in that, The molar ratio C of the first metal oxide and the second metal oxide satisfies: 1:1≤C≤10:

1.

3. The battery cell according to claim 1 or 2, characterized in that, The molar ratio C of the first metal oxide and the second metal oxide satisfies: 3:1 ≤ C ≤ 5:

1.

4. The battery cell according to any one of claims 1-3, characterized in that, Based on the total mass of the first film layer, the mass content P1 of the first metal oxide satisfies: 0.05wt% ≤ P1 ≤ 20wt%; and / or Based on the total mass of the second film layer, the mass content P2 of the second metal oxide satisfies: 0.05wt% ≤ P2 ≤ 20wt%.

5. The battery cell according to any one of claims 1-4, characterized in that, Based on the total mass of the first film layer, the mass content P1 of the first metal oxide satisfies: 0.1wt% ≤ P1 ≤ 5wt%; and / or Based on the total mass of the second film layer, the mass content P2 of the second metal oxide satisfies: 0.1wt% ≤ P2 ≤ 5wt%.

6. The battery cell according to any one of claims 1-5, characterized in that, The volume average particle size of the second metal oxide is greater than or equal to the volume average particle size of the first metal oxide.

7. The battery cell according to claim 6, characterized in that, The volume average particle size Dv50 of the first metal oxide 1 Satisfies: 0.1μm≤Dv50 1 ≤20μm.

8. The battery cell according to claim 6 or 7, characterized in that, The volume average particle size Dv50 of the first metal oxide 1 Satisfies: 0.5μm≤Dv50 1 ≤5μm.

9. The battery cell according to any one of claims 6-8, characterized in that, The volume average particle size Dv50 of the second metal oxide 2 Satisfies: 0.1μm≤Dv50 2 ≤10μm.

10. The battery cell according to any one of claims 6-9, characterized in that, The volume average particle size Dv50 of the second metal oxide 2 Satisfies: 0.5μm≤Dv50 2 ≤5μm.

11. The battery cell according to any one of claims 1-10, characterized in that, The first metal oxide includes one or more of the following: Li3VO4, Li3NbO4, Li3CrO4, Li3MoO4, Li5FeO4, Li5CrO4, Li5VO4, Li5MoO4, Li6CoO4, Li6VO4, Li6CrO4, Li6MoO4, or Li8SnO6.

12. The battery cell according to any one of claims 1-11, characterized in that, The first metal oxide includes Li5FeO4.

13. The battery cell according to any one of claims 1-12, characterized in that, The second metal oxide includes Li2NiO2 and Li2Ni. 0.5 Cu 0.5 O2 or Li2Ni 0.8 Cu 0.2 One or more of O2.

14. The battery cell according to any one of claims 1-13, characterized in that, The first lithium replenishment material includes the first metal oxide and oxide and / or carbon materials located on the surface of the first metal oxide; And / or, The second lithium supplement material includes the second metal oxide and oxide and / or carbon materials located on the surface of the second metal oxide.

15. The battery cell according to claim 14, characterized in that, The oxide includes a metallic element, which includes one or more of Ni, W, Cu, Mn, Al, Fe, Ti, Mo, Ce, Co, Cr, or V.

16. The battery cell according to claim 14 or 15, characterized in that, The oxide includes Al2O3.

17. The battery cell according to any one of claims 14-16, characterized in that, In the first lithium replenishment material, based on the total mass of the first lithium replenishment material, the mass content D1 of the oxide satisfies: 0.1wt% ≤ D1 ≤ 10wt%, and / or, the mass content E1 of the carbon material satisfies: 0.1wt% ≤ E1 ≤ 10wt%. And / or, In the second lithium replenishing material, based on the total mass of the second lithium replenishing material, the mass content D2 of the oxide satisfies: 0.1wt% ≤ D2 ≤ 10wt%, and / or, the mass content E2 of the carbon material satisfies: 0.1wt% ≤ E2 ≤ 10wt%.

18. The battery cell according to any one of claims 14-17, characterized in that, In the first lithium replenishment material, based on the total mass of the first lithium replenishment material, the mass content D1 of the oxide satisfies: 0.5wt% ≤ D1 ≤ 5wt%, and / or, the mass content E1 of the carbon material satisfies: 0.5wt% ≤ E1 ≤ 5wt%. And / or, In the second lithium replenishing material, based on the total mass of the second lithium replenishing material, the mass content D2 of the oxide satisfies: 0.5wt% ≤ D2 ≤ 5wt%, and / or, the mass content E2 of the carbon material satisfies: 0.5wt% ≤ E2 ≤ 5wt%.

19. The battery cell according to any one of claims 14-18, characterized in that, The carbon material includes one or more of the following: superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, or carbon nanofibers.

20. The battery cell according to any one of claims 1-19, characterized in that, Both the first and second membrane layers further include a positive electrode active material, wherein the volume average particle size of the positive electrode active material is Dv50. 3 Satisfies: 0.1μm≤Dv50 3 ≤10μm.

21. The battery cell according to claim 20, characterized in that, The positive electrode active material includes: a lithium phosphate with an olivine structure, wherein the lithium phosphate with an olivine structure includes lithium iron phosphate.

22. The battery cell according to any one of claims 1-21, characterized in that, The battery cell is the battery cell before formation.

23. A method for preparing a single battery cell, characterized in that, include: A positive electrode sheet is provided to prepare the battery cell; The positive electrode sheet provided includes: A first film layer is coated on at least one side of the surface of the positive electrode current collector, wherein the first film layer includes a first lithium replenishment material, the first lithium replenishment material includes a first metal oxide, and the chemical formula of the first metal oxide satisfies: Li a1 M 1 O c1 , 2.8≤a1≤8.2, 1.8≤c1≤6.2, M 1 Including one or more of V, Nb, Cr, Mo, Fe, Co, or Sn; A second film layer is coated on at least one side of the surface of the first film layer, wherein the second film layer includes a second lithium replenishing material, the second lithium replenishing material includes a second metal oxide, and the chemical formula of the second metal oxide satisfies: Li a2 Ni 1-b M 2 b O c2 1 <a2≤2.2,0≤b<1,1.8≤c2≤2.2,M 2 It includes one or more of Cu, Co, Mg, Zn, Mn, Al, Zr, Ti, or Fe.

24. An electrical appliance, characterized in that, include: The battery cell according to any one of claims 1-22, and / or the battery cell obtained by the preparation method according to claim 23.

25. The electrical appliance according to claim 24, characterized in that, The electrical equipment includes energy storage devices or heavy-duty trucks.

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