Positive pole piece, battery and electric device

Abstract

The invention provides a positive pole piece, a battery and an electric device. The positive pole piece comprises a positive current collector, an active material layer and a non-active material layer, the active material layer and the non-active material layer are arranged on at least one surface of the positive current collector, the non-active material layer is arranged around the periphery of the active material layer, the active material layer comprises a positive active material, and the active material layer and the non-active material layer are arranged on the same layer. When the positive pole piece is used in the lithium metal battery to be matched with a lithium metal negative pole, the battery with relatively high energy density and relatively long cycle life can be obtained.

Description

Technical Field

[0001] The present application relates to the field of battery technology, and in particular to a positive electrode sheet, a battery and an electrical device. Background Art

[0002] In recent years, as the application scope of batteries has become wider and wider, batteries are widely used in energy storage power supply systems such as hydropower, thermal power, wind power and solar power stations, as well as in many fields such as power tools, electric bicycles, electric motorcycles and electric vehicles.

[0003] As batteries have made great progress, higher requirements have been placed on the energy density and cycle life of batteries. Therefore, seeking batteries with higher energy density and longer cycle life is one of the key areas of focus for those skilled in the art. Summary of the invention

[0004] The present application is made in view of the above-mentioned problems, and one of its purposes is to provide a positive electrode plate, which can be used in a lithium metal battery in combination with a specific negative electrode plate to obtain a battery with higher energy density and longer cycle life.

[0005] In order to achieve the above-mentioned purpose, the first aspect of the present application provides a positive electrode plate, including a positive electrode current collector and an active material layer and an inactive material layer arranged on at least one surface of the positive electrode current collector, the inactive material layer is arranged around the periphery of the active material layer, the active material layer includes a positive electrode active material, and the active material layer and the inactive material layer are arranged in the same layer.

[0006] The present application arranges an inactive material layer around the periphery of the active material layer of the positive electrode sheet, and the active material layer and the inactive material layer are arranged in the same layer. When the positive electrode sheet and the lithium metal foil negative electrode sheet are stacked to form a battery, the positive projection of the edge of the lithium metal foil on the positive electrode sheet is located within the range of the inactive material layer; in this way, the situation that the soft lithium metal foil is cut by the edge of the positive electrode sheet under pressure during the battery charging and discharging process, resulting in the loss of electrical connection of the negative electrode sheet, can be alleviated, thereby extending the cycle life of the battery using lithium metal foil as the negative electrode. In addition, the positive projection of the edge of the lithium metal foil on the positive electrode sheet is located within the range of the inactive material layer, and a region (i.e., an overhang region) of the electrode portion beyond the range of the active material layer of the positive electrode sheet can be formed on the lithium metal foil, thereby reducing the growth of lithium dendrites at the edge of the lithium metal foil. By matching the positive electrode sheet with the lithium metal foil negative electrode, a battery with higher energy density and longer cycle life can be obtained.

[0007] In any embodiment, the material of the inactive material layer includes an insulating material, and the insulating material includes one or more of an organic insulating material and an inorganic insulating material. In this way, the inactive material layer uses an insulating material, which can alleviate the situation in which the positive and negative electrodes are short-circuited due to accidental bending of the pole piece or the positive electrode burr piercing the separator and overlapping the negative electrode active material during the battery production process, and can improve the safety of the battery.

[0008] In any embodiment, the organic insulating material includes an organic polymer, and the organic polymer includes one or more of polymethyl methacrylate, polyimide, polyethylene, polypropylene, polytetrafluoroethylene, polyvinylidene fluoride, and polyvinylidene fluoride-hexafluoropropylene copolymer; the inorganic insulating material includes oxide particles, and the oxide particles include one or more of aluminum oxide particles and titanium oxide particles. The use of the above-mentioned organic insulating materials and inorganic insulating materials can effectively alleviate the short circuit of the positive and negative electrodes.

[0009] In any embodiment, the thickness of the inactive material layer is equal to the thickness of the active material layer. In this way, the uneven thickness of the positive electrode sheet can be alleviated, and the situation where the lithium metal foil is cut by the positive electrode sheet under pressure and the negative electrode sheet loses electrical connection can be better alleviated.

[0010] In any embodiment, the thickness of the inactive material layer on the side close to the active material layer is greater than the thickness of the inactive material layer on the side away from the active material layer. In this way, the thickness of the inactive material layer on the side close to the active material layer is larger, which can form a certain pressure on the edge of the lithium metal foil, can play a role in pulverizing the deposited metal lithium, and alleviate the growth of lithium dendrites in the edge area of ​​the lithium metal foil; the thickness of the inactive material layer on the side away from the active material layer is smaller, which is conducive to improving the energy density of the battery.

[0011] In any embodiment, the thickness of the inactive material layer gradually decreases in a direction extending outward from the side of the inactive material layer close to the active material layer, so as to reduce the weight of the positive electrode sheet and further improve the energy density of the battery.

[0012] In any embodiment, the inactive material layer includes a first region and a second region, the first region is close to the active material layer, the second region is located on the side of the first region away from the active material layer, the thickness of the inactive material layer in the first region is equal to the thickness of the active material layer; in the direction extending outward from the side close to the first region, the thickness of the inactive material layer in the second region gradually decreases. In this way, the thickness design of the inactive material layer in the first region can apply a certain pressure to the corresponding region of the lithium metal foil, play a role in pulverizing the deposited metallic lithium, and alleviate the growth of lithium dendrites on the lithium metal foil in the region; the thickness of the inactive material layer in the second region gradually decreases, which can further reduce the weight of the positive electrode sheet and improve the energy density of the battery.

[0013] In any embodiment, the positive electrode current collector includes a polymer support layer and a conductive layer disposed on at least one surface of the polymer support layer, and the active material layer and the inactive material layer are disposed on the surface of the conductive layer away from the polymer support layer. In this way, the positive electrode current collector adopts a composite current collector, which can further improve the energy density of the battery.

[0014] The second aspect of the present application also provides a battery, including a stacked positive electrode plate and a negative electrode plate, the positive electrode plate includes the positive electrode plate of the first aspect of the present application, the negative electrode plate includes a lithium metal foil, the lithium metal foil includes a pole piece portion and a pole ear lead portion connected to the pole piece portion, and the orthographic projection of the edge of the pole piece portion on the positive electrode plate is located within the range of the inactive material layer.

[0015] The above-mentioned battery adopts the positive electrode plate of the first aspect of the present application, and adopts lithium metal foil as the negative electrode plate, and the positive projection of the edge of the plate portion on the positive electrode plate is located within the range of the inactive material layer; during the battery charging and discharging process, even if the positive electrode plate is close to the negative electrode plate under pressure, the edge of the positive electrode plate will not cut the negative lithium metal foil, which can alleviate the situation in which the soft lithium metal foil is cut by the edge of the positive electrode plate under pressure during the battery charging and discharging process, resulting in the loss of electrical connection of the negative electrode plate, and can extend the cycle life of the battery; and the battery has a high energy density.

[0016] In any embodiment, the distance between the orthographic projection of the edge of the pole piece on the positive electrode sheet and the outer edge of the inactive material layer is a, and a is 1 mm to 5 mm; optionally, a is 1.5 mm to 3 mm. In this way, the pole piece can be effectively relieved from being cut by the edge of the positive electrode sheet, and the positive electrode sheet can be prevented from being too wide to affect the battery energy density.

[0017] In any embodiment, the positive projection of the active material layer on the negative electrode plate is located within the range of the plate portion. In this way, an overhang area can be formed at the edge of the plate portion, which can alleviate the growth of lithium dendrites at the edge of the plate portion and improve the safety of the battery.

[0018] In any embodiment, the distance between the orthographic projection of the edge of the pole piece on the positive pole piece and the outer edge of the active material layer is b, and b is 1mm to 5mm; optionally, b is 1.5mm to 3mm. In this way, the growth of lithium dendrites at the edge of the pole piece can be effectively alleviated to improve battery safety; and the width of the overhang area can be prevented from being too wide, which is conducive to improving the battery energy density.

[0019] In any embodiment, the inactive material layer includes a first region and a second region, the first region is close to the active material layer, and the second region is located on the side of the first region away from the active material layer; in the direction extending outward from the side close to the first region, the thickness of the inactive material layer in the second region gradually decreases; the thickness of the inactive material layer in the first region is equal to the thickness of the active material layer, and the width of the first region is ≥ b. In this way, the thickness design of the inactive material layer in the first region and the width design of the first region can apply a certain pressure to the corresponding region of the lithium metal foil, play a role in pulverizing the deposited metallic lithium, and alleviate the growth of lithium dendrites on the lithium metal foil in the region; the thickness of the inactive material layer in the second region gradually decreases, which can further alleviate the lithium metal foil from being cut by the positive electrode sheet under pressure, and can further reduce the weight of the positive electrode sheet and improve the battery energy density.

[0020] In any embodiment, the orthographic projection of the outer edge of the tab lead-out portion on the positive electrode sheet is located within the range of the inactive material layer. In this way, the tab lead-out portion can be relieved from being cut by the edge of the positive electrode sheet under pressure during the battery charging and discharging process, further improving the cycle life of the battery.

[0021] In any embodiment, the tab lead-out portion is provided with a tab lead-out foil compounded with the lithium metal foil, and the tab lead-out foil is connected with a tab connection sheet. In this way, the negative electrode tab can be welded on the tab connection sheet, greatly reducing the difficulty of leading and welding the negative electrode tab; and the tab lead-out foil and the lithium metal foil of the tab lead-out portion are compounded to collect current and improve the strength of the tab lead-out portion.

[0022] In any embodiment, the width of the tab connection sheet is c, the length of the tab lead foil is d, the width of the lithium metal foil near the end of the tab connection sheet is e, and c≤d≤e. Optionally, d=e. In this way, the tab lead foil has a longer length, which can increase the composite contact area between the tab lead foil and the lithium metal foil, which is more conducive to current collection and reduces the occurrence of overcurrent.

[0023] In any embodiment, the thickness of the lithium metal foil is 10 μm to 50 μm, and can be 30 μm to 50 μm, which is beneficial for the battery to have a higher energy density and a longer cycle life.

[0024] The third aspect of the present application further provides an electrical device, which comprises the battery of the second aspect of the present application.

[0025] The details of one or more embodiments of the present application are set forth in the following drawings and description. Other features, objects, and advantages of the present application will become apparent from the description, drawings, and claims. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In order to better describe and illustrate the embodiments or examples provided by the present application, reference may be made to one or more drawings. The additional details or examples used to describe the drawings should not be considered as limiting the scope of the disclosed application, the embodiments or examples currently described, and any of the best modes of these applications currently understood. Moreover, the same reference numerals are used throughout the drawings to represent the same components. In the drawings:

[0027] Figure 1 A schematic front view of a positive electrode sheet according to an embodiment of the present application;

[0028] Figure 2 A schematic cross-sectional view of a positive electrode sheet according to an embodiment of the present application;

[0029] Figure 3 A schematic cross-sectional view of a positive electrode sheet according to another embodiment of the present application;

[0030] Figure 4 A schematic cross-sectional view of a positive electrode sheet according to another embodiment of the present application;

[0031] Figure 5 A schematic cross-sectional view of a positive electrode current collector in one embodiment of the present application;

[0032] Figure 6 A schematic front view of a stacked positive electrode sheet and a negative electrode sheet in a battery according to an embodiment of the present application;

[0033] Figure 7 A schematic front view of a stacked positive electrode sheet and a negative electrode sheet in a battery according to another embodiment of the present application;

[0034] Figure 8 A cross-sectional schematic diagram of a stacked positive electrode sheet and a negative electrode sheet in a battery according to an embodiment of the present application;

[0035] Fig. 9 A cross-sectional schematic diagram of a stacked positive electrode sheet and a negative electrode sheet in a battery according to another embodiment of the present application;

[0036] Fig.10 A cross-sectional schematic diagram of a stacked positive electrode sheet and a negative electrode sheet in a battery according to another embodiment of the present application;

[0037] Fig.11 A schematic front view of a negative electrode sheet in a battery according to an embodiment of the present application;

[0038] Fig.12 A schematic side view of a negative electrode tab connecting piece of a battery in one embodiment of the present application when it is not cut;

[0039] Fig.13 It is a front view schematic diagram of a negative electrode tab connecting piece of a battery in one embodiment of the present application when it is not cut;

[0040] Fig.14 A schematic diagram of a battery cell according to an embodiment of the present application;

[0041] Fig.15 for Fig.14 An exploded view of a battery cell according to an embodiment of the present application is shown;

[0042] Fig.16 A schematic diagram of an electrical device using a battery as a power source according to an embodiment of the present application.

[0043] Description of reference numerals:

[0044] 5. Battery cell; 51. Shell; 52. Electrode assembly; 53. Cover plate;

[0045] 6. Electrical devices;

[0046] 10. positive electrode sheet; 11. positive electrode current collector; 12. active material layer; 13. inactive material layer; 111. polymer support layer; 112. conductive layer; 131. first region; 132. second region;

[0047] 20. Negative electrode plate; 21. Lithium metal foil; 22. Tab lead foil; 23. Tab connecting plate; 211. Pole plate portion; 212. Tab lead portion. DETAILED DESCRIPTION

[0048] Below, the embodiments of the positive electrode plate, battery and electrical device of the present application are described in detail with appropriate reference to the drawings. However, there may be cases where unnecessary detailed descriptions are omitted. For example, there are cases where detailed descriptions of well-known matters and repeated descriptions of actually the same structure are omitted. This is to avoid the following description from becoming unnecessarily lengthy and to facilitate the understanding of those skilled in the art. In addition, the drawings and the following descriptions are provided for those skilled in the art to fully understand the present application and are not intended to limit the subject matter described in the claims.

[0049] The "range" disclosed in the present application can be defined in the form of a lower limit and an upper limit, and a given range is defined by selecting a lower limit and an upper limit, and the selected lower limit and upper limit define the boundaries of a particular range. The range defined in this way can be inclusive or exclusive of the end values, and any end value can be included or excluded independently, and can be arbitrarily combined, that is, any lower limit can be combined with any upper limit to form a range. For example, if a range of 60 to 120 and 80 to 110 is listed for a specific parameter, it is understood that the range of 60 to 110 and 80 to 120 is also expected. In addition, if the minimum range values ​​1 and 2 are listed, and if the maximum range values ​​3, 4 and 5 are also listed, the following ranges can all be expected: 1 to 3, 1 to 4, 1 to 5, 2 to 3, 2 to 4 and 2 to 5. In the present application, unless otherwise specified, the numerical range "a to b" represents an abbreviation of any real number combination between a and b, where a and b are both real numbers. For example, the numerical range "0-5" means that all real numbers between "0-5" are listed in this document, and "0-5" is just an abbreviation of these numerical combinations. In addition, when a parameter is expressed as an integer ≥ 2, it is equivalent to listing the parameter as, for example, integers 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc. For example, when a parameter is expressed as an integer selected from "2-10", it is equivalent to listing the integers 2, 3, 4, 5, 6, 7, 8, 9 and 10.

[0050] In the present application, "plurality", "multiple" and the like, unless otherwise specified, refer to a number greater than or equal to 2. For example, "one or more" means one or greater than or equal to two.

[0051] Unless otherwise specified, all embodiments and optional embodiments of the present application can be combined with each other to form a new technical solution.

[0052] Reference to "embodiments" herein means that a particular feature, structure, or characteristic described in conjunction with the embodiments may be included in at least one embodiment or implementation of the present application. The appearance of the phrase in various locations in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment that is mutually exclusive with other embodiments. It is explicitly and implicitly understood by those skilled in the art that the embodiments described herein may be combined with other embodiments. The "implementation methods" mentioned herein have a similar understanding.

[0053] Those skilled in the art will appreciate that, in the methods of each embodiment or example, the order in which each step is written does not mean a strict order of execution and does not constitute any limitation on the implementation process, and the detailed order of execution of each step should be determined by its function and possible internal logic. If there is no special explanation, all steps of the present application can 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 steps (b) and (a) performed sequentially. For example, the method may also include step (c), indicating that step (c) can be added to the method in any order, for example, the method may include steps (a), (b) and (c), or steps (a), (c) and (b), or steps (c), (a) and (b), etc.

[0054] In the present application, in the open technical features or technical solutions described by the words "contain", "include", "comprise", etc., unless otherwise specified, additional members other than the listed members are not excluded, and it can be regarded as providing both closed features or solutions consisting of the listed members and open features or solutions including additional members in addition to the listed members. For example, A includes a1, a2 and a3. Unless otherwise specified, it may also include other members or may not include additional members. It can be regarded as providing both the feature or solution of "A consists of a1, a2 and a3" and the feature or solution of "A not only includes a1, a2 and a3, but also includes other members". In the present application, unless otherwise specified, A (such as B) means that B is a non-limiting example of A, and it can be understood that A is not limited to B.

[0055] In this application, "optionally", "optional", and "optional" mean optional, that is, any one of the two parallel schemes of "yes" or "no". If there are multiple "options" in a technical solution, unless otherwise specified and there is no contradiction or mutual restriction, each "option" is independent.

[0056] The weights described in the embodiments of the present application may be μg, mg, g, kg, or other weight units known in the chemical industry.

[0057] At present, as batteries have made great progress, higher requirements have been put forward for the energy density and cycle life of batteries. Therefore, seeking batteries with higher energy density and longer cycle life is one of the key directions of technical personnel in this field. In this regard, the present application provides a positive electrode sheet. By improving the structure of the positive electrode sheet and combining it with a lithium metal negative electrode, a battery with higher energy density and longer cycle life can be obtained.

[0058] See also Figures 1 to 4In some embodiments, the first aspect of the present application provides a positive electrode sheet 10, which includes a positive electrode current collector 11 and an active material layer 12 and an inactive material layer 13 disposed on at least one surface of the positive electrode current collector 11. The inactive material layer 13 is disposed around the periphery of the active material layer 12, the active material layer 12 includes a positive electrode active material, and the inactive material layer 13 does not include a positive electrode active material.

[0059] Lithium metal anode is the ultimate anode solution for ultra-high energy density lithium-ion batteries. Compared with graphite and other anode active materials, lithium metal can achieve higher energy density. The lithium metal anode used in current lithium metal batteries is usually formed by covering ultra-thin lithium foil on copper foil, where the copper foil is used to provide current and as a substrate to provide mechanical support and strength for the lithium metal foil. However, the density of copper foil (about 8.92g / cm 2 ) is the density of lithium metal (about 0.53 g / cm 2 ). This means that when pursuing the ultimate high energy density, the weight of copper foil is a major factor. If copper foil can be completely eliminated as the negative electrode substrate, the energy density of the battery can be further improved. At the same time, the thickness design of lithium metal foil can also obtain more space, support longer cycle consumption, and extend the cycle life of lithium metal batteries.

[0060] However, the negative electrode does not use a copper foil substrate and lithium metal foil to laminate, but directly uses lithium metal foil as the negative electrode plate, which needs to overcome the following problems: the lithium metal foil itself is soft and has poor strength. During the battery charging and discharging process, the lithium metal foil is very easy to be cut by the edge of the positive electrode under pressure, causing the lithium metal foil to lose electrical contact with the negative electrode tab, which in turn causes battery failure and a short battery cycle life.

[0061] In view of the above problems, the present application provides an inactive material layer 13 around the outer periphery of the active material layer 12 of the positive electrode plate 10, and the active material layer 12 and the inactive material layer 13 are provided in the same layer, and the inactive material layer 13 does not include the positive electrode active material; when the positive electrode plate 10 and the lithium metal foil negative electrode plate are stacked to form a battery, the orthographic projection of the edge of the electrode portion 211 of the lithium metal foil 21 on the positive electrode plate 10 is located within the range of the inactive material layer 13, that is, the inactive material layer 13 can cover the edge of the electrode portion 211; in this way, during the battery charging and discharging process, even if the positive electrode plate is close to the negative electrode plate under pressure, the edge of the positive electrode plate will not cut the negative lithium metal foil, which can alleviate the situation in which the soft lithium metal foil is cut by the edge of the positive electrode plate under pressure during the battery charging and discharging process, resulting in the negative electrode plate losing electrical connection, thereby extending the cycle life of the battery using lithium metal foil as the negative electrode. By combining the positive electrode plate with a lithium metal foil negative electrode, a battery with higher energy density and longer cycle life can be obtained.

[0062] In some embodiments, the material of the inactive material layer 13 includes an insulating material, which includes one or more of an organic insulating material and an inorganic insulating material. The material of the inactive material layer 13 is an insulating material, which can alleviate the situation in which the positive and negative electrodes are short-circuited due to accidental bending of the pole piece or the positive electrode burr piercing the isolation membrane and overlapping the negative electrode active material during the battery production process. By using an insulating material as the inactive material layer 13, even if the pole piece is bent or the positive electrode burr pierces the isolation membrane and overlaps the negative electrode active material, it will not cause the positive and negative electrodes to be conductive, and the positive and negative electrodes will not short-circuit, which can improve the safety of the battery.

[0063] In some embodiments, the insulating material of the inactive material layer 13 includes one or more of polymethyl methacrylate (PMMA), polyimide (PI), polyethylene (PE), polypropylene (PP), polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVDF), polyvinylidene fluoride-hexafluoropropylene copolymer (PVDF-HFP), aluminum oxide particles, and titanium oxide particles. The use of the above-mentioned insulating materials can effectively alleviate the short circuit of the positive and negative electrodes. Among the above-mentioned insulating materials, polymethyl methacrylate, polyimide, polyethylene, polypropylene, polytetrafluoroethylene, polyvinylidene fluoride, and polyvinylidene fluoride-hexafluoropropylene copolymer are organic polymer insulating materials, which can be formed on the positive electrode collector 11 by gluing or slurry coating; aluminum oxide particles and titanium oxide particles are inorganic particle insulating materials, which can be formed on the positive electrode collector 11 by slurry coating. The particle size of aluminum oxide particles and titanium oxide particles can be nanometer or micrometer.

[0064] It can be understood that the inactive material layer 13 can be formed by using one or more of the above-mentioned insulating polymers, or by using one or more of the above-mentioned insulating inorganic particles, or by mixing the above-mentioned one or more polymers with the above-mentioned one or more inorganic particles.

[0065] See also Figure 2 In some embodiments, the thickness of the inactive material layer 13 is equal to the thickness of the active material layer 12. By setting the thickness of the inactive material layer 13 to be equal to the thickness of the active material layer 12, the uneven thickness on the positive electrode sheet 10 can be alleviated, and the situation where the lithium metal foil is cut by the positive electrode sheet under pressure and the negative electrode sheet loses electrical connection can be better alleviated.

[0066] In some embodiments, the thickness of the inactive material layer 13 on the side close to the active material layer 12 is greater than the thickness of the inactive material layer 13 on the side away from the active material layer 12. In this way, the thickness of the inactive material layer 13 on the side close to the active material layer 12 is larger, which can form a certain pressure on the edge of the lithium metal foil 21, can play a role in pulverizing the deposited metal lithium, and alleviate the growth of lithium dendrites in the edge area of ​​the lithium metal foil 21; the thickness of the inactive material layer 13 on the side away from the active material layer 12 is smaller, which is conducive to improving the energy density of the battery.

[0067] See also Figure 3 In some embodiments, the thickness of the inactive material layer 13 gradually decreases in the direction extending outward from the side of the inactive material layer 13 close to the active material layer 12. In this way, the inactive material layer 13 close to the active material layer 12 can be made thicker, which is more conducive to alleviating the growth of lithium dendrites in the edge area of ​​the lithium metal foil 21; and the thickness of the inactive material layer 13 close to the edge of the positive electrode sheet 10 can be made smaller, which is more conducive to reducing the weight of the positive electrode sheet 10, thereby improving the energy density of the battery.

[0068] It can be understood that the thickness of the inactive material layer 13 can be in a straight line form, a curve form or a gradient form, and gradually decreases in a direction extending outward from a side of the inactive material layer 13 close to the active material layer 12 .

[0069] See also Figure 4In some embodiments, the inactive material layer 13 includes a first region 131 and a second region 132. The first region 131 is close to the active material layer 12, and the second region 132 is located on the side of the first region 131 away from the active material layer 12; the thickness of the inactive material layer 13 in the first region 131 is equal to the thickness of the active material layer 12; and the thickness of the inactive material layer 13 in the second region 132 gradually decreases in a direction extending outward from the side close to the first region 131.

[0070] Since the edge of the negative electrode lithium metal foil corresponds to the area close to the active material layer 12, lithium dendrites are easily grown, by setting the thickness of the inactive material layer 13 in the first area 131 close to the active material layer 12 in the positive electrode plate 10 to be equal to the thickness of the active material layer 12, the inactive material layer 13 in the first area 131 can apply a certain pressure to the corresponding area of ​​the lithium metal foil, play a role in pulverizing the deposited metal lithium, and alleviate the growth of lithium dendrites on the lithium metal foil in this area. In addition, in the direction extending outward from the side close to the first area 131, the thickness of the inactive material layer 13 in the second area 132 is gradually reduced, which is more conducive to reducing the weight of the positive electrode plate 10 and improving the energy density of the battery.

[0071] It can be understood that the thickness of the inactive material layer 13 in the second region 132 may be gradually reduced in a direction extending outward from the side close to the first region 131 in a straight line form, a curve form or a gradient form.

[0072] See also Figure 5 In some embodiments, the positive electrode current collector 11 includes a polymer support layer 111 and a conductive layer 112 disposed on at least one surface of the polymer support layer 111, and the active material layer 12 and the inactive material layer 13 are disposed on the surface of the conductive layer 112 away from the polymer support layer 111. In this way, the positive electrode current collector 11 uses a composite current collector and can use an ultra-thin conductive layer 112, which can further improve the energy density of the battery.

[0073] It should be noted that the material of the polymer support layer 111 may be, but is not limited to, one or more of polyethylene terephthalate (PET), polyimide (PI), polystyrene (PS), polyethylene (PE), polypropylene (PP), polycarbonate (PC), polyvinyl chloride (PET), and polymethyl methacrylate (PMMA). The thickness of the polymer support layer 111 may be 1 μm to 20 μm; in order to further improve the energy density of the battery, the thickness of the polymer support layer 111 may be 1 μm to 5 μm. The material of the conductive layer 112 may be metallic aluminum, and the conductive layer 112 may be formed on the surface of the polymer support layer 111 by magnetron sputtering or evaporation. The thickness of the conductive layer 112 may be 0.5 μm to 5 μm, and in order to further improve the energy density of the battery, the thickness of the conductive layer 112 may be 0.5 μm to 2 μm.

[0074] In some of the embodiments, the above-mentioned positive electrode plate 10 can be prepared by the following method: providing a polymer support layer 111, forming a conductive layer 112 on the surface of the polymer support layer 111 by magnetron sputtering or evaporation, etc., to obtain a positive electrode collector 11; attaching a positive electrode slurry to the conductive layer 112 of the positive electrode collector 11 to form a positive electrode slurry layer, wherein the positive electrode slurry includes a positive electrode active material; drying the positive electrode slurry layer to form an active material layer 12; forming an inactive material layer 13 on the conductive layer 112 by gluing or slurry coating, so that the inactive material layer 13 is arranged around the active material layer 12, thereby obtaining the positive electrode plate 10.

[0075] See also Figures 6 to 10 In some embodiments, the second aspect of the present application provides a battery, which includes a stacked positive electrode sheet 10 and a negative electrode sheet 20. The positive electrode sheet 10 uses the positive electrode sheet 10 of the first aspect of the present application, and the negative electrode sheet 20 uses a lithium metal foil 21; the lithium metal foil 21 includes a pole piece portion 211 and a tab lead-out portion 212 connected to the pole piece portion 211, and the orthographic projection of the edge of the pole piece portion 211 on the positive electrode sheet 10 is located within the range of the inactive material layer 13.

[0076] The above-mentioned battery adopts the positive electrode plate 10 of the first aspect of the present application, and adopts the lithium metal foil 21 as the negative electrode plate 20, and the orthographic projection of the edge of the plate portion 211 on the positive electrode plate 10 is located within the range of the inactive material layer 13; during the battery charging and discharging process, even if the positive electrode plate 10 is close to the negative electrode plate 20 under pressure, the edge of the positive electrode plate 10 will not cut the negative lithium metal foil 21, which can alleviate the situation in which the soft lithium metal foil 21 is cut by the edge of the positive electrode plate 10 under pressure during the battery charging and discharging process, resulting in the loss of electrical connection of the negative electrode plate 20, and can extend the cycle life of the battery; and the battery has a higher energy density.

[0077] If the orthographic projection of the edge of the pole piece 211 on the positive electrode plate 10 is outside the range of the inactive material layer 13, that is, the edge of the pole piece 211 is located outside the inactive material layer 13, and the inactive material layer 13 cannot cover the edge of the pole piece 211; then since the pole piece 211 of the lithium metal foil 21 is soft in texture, the pole piece 211 is easily cut by the edge of the positive electrode plate 10 under pressure during the battery charging and discharging process, affecting the cycle life of the battery.

[0078] See also Figure 6 In some embodiments, the distance between the orthographic projection of the edge of the pole piece 211 of the lithium metal foil 21 on the positive electrode sheet 10 and the outer edge of the inactive material layer 13 is a, and a=1mm-5mm. In this way, the outer edge of the inactive material layer 13 exceeds the edge of the pole piece 211 by 1mm-5mm, which can effectively alleviate the pole piece 211 from being cut by the edge of the positive electrode sheet 10, and prevent the positive electrode sheet 10 from being too wide to affect the battery energy density.

[0079] It will be appreciated that a may be, but is not limited to, 1.0mm, 1.1mm, 1.2mm, 1.3mm, 1.4mm, 1.5mm, 1.6mm, 1.7mm, 1.8mm, 1.9mm, 2.0mm, 2.1mm, 2.2mm, 2.3mm, 2.4mm, 2.5mm, 2.6mm, 2.7mm, 2.8mm, 2.9mm, 3.0mm, 3.1mm, 3.2mm, 3.3mm, 3.4mm, 3.5mm, 3.6mm, 3.7mm, 3.8mm, 3.9mm, 4.0mm, 4.1mm, 4.2mm, 4.3mm, 4.4mm, 4.5mm, 4.6mm, 4.7mm, 4.8mm, 4.9mm, and 5.0mm.

[0080] In some embodiments, the distance a between the orthographic projection of the edge of the pole piece 211 of the lithium metal foil 21 on the positive electrode sheet 10 and the outer edge of the inactive material layer 13 is 1.5 mm to 3 mm. In this way, the pole piece 211 can be better relieved from being cut by the edge of the positive electrode sheet 10, which is conducive to further improving the energy density of the battery.

[0081] See also Figure 6 and Figure 7In some embodiments, the positive projection of the active material layer 12 on the negative electrode plate 20 is located within the range of the plate portion 211, that is, the range of the plate portion 211 can cover the range of the active material layer 12. In this way, an overhang area can be formed at the edge of the plate portion 211, which can alleviate the growth of lithium dendrites at the edge of the plate portion 211 and improve the safety of the battery. It should be noted that the overhang area refers to the area where the plate portion 211 exceeds the active material layer 12.

[0082] See also Figure 6 In some embodiments, the distance between the orthographic projection of the edge of the pole piece 211 on the positive pole piece 10 and the outer edge of the active material layer 12 is b, and b=1mm-5mm. In this way, the formation of lithium dendrites at the edge of the pole piece 211 can be effectively alleviated to improve the battery safety; and the width of the overhang area can be made not too wide, which is conducive to improving the battery energy density.

[0083] It will be appreciated that b may be, but is not limited to, 1.0mm, 1.1mm, 1.2mm, 1.3mm, 1.4mm, 1.5mm, 1.6mm, 1.7mm, 1.8mm, 1.9mm, 2.0mm, 2.1mm, 2.2mm, 2.3mm, 2.4mm, 2.5mm, 2.6mm, 2.7mm, 2.8mm, 2.9mm, 3.0mm, 3.1mm, 3.2mm, 3.3mm, 3.4mm, 3.5mm, 3.6mm, 3.7mm, 3.8mm, 3.9mm, 4.0mm, 4.1mm, 4.2mm, 4.3mm, 4.4mm, 4.5mm, 4.6mm, 4.7mm, 4.8mm, 4.9mm, and 5.0mm.

[0084] In some embodiments, the distance b between the orthographic projection of the edge of the pole piece 211 on the positive pole piece 10 and the outer edge of the active material layer 12 is 1.5 mm to 3 mm. In this way, the growth of lithium dendrites at the edge of the pole piece 211 can be better alleviated, and the energy density of the battery can be further improved.

[0085] See also Fig.10 In some embodiments, the inactive material layer 13 includes a first region 131 and a second region 132. The first region 131 is disposed close to the active material layer 12, and the second region 132 is located on the side of the first region 131 away from the active material layer 12; and the thickness of the inactive material layer 13 in the second region 132 gradually decreases in the direction extending outward from the side close to the first region 131; the thickness of the inactive material layer 13 in the first region 131 is equal to the thickness of the active material layer 12, and the width of the first region 131 is ≥b.

[0086] By adopting the above-mentioned setting, the width of the first region 131 is set to ≥ b, so that the first region 131 can cover the overhang area at the edge of the pole piece 211; and the thickness of the inactive material layer 13 in the first region 131 is equal to the thickness of the active material layer 12. During the battery charging and discharging process, the inactive material layer 13 in the first region 131 can apply pressure to the overhang area, so that the metal lithium deposited in the overhang area is powdered, which is more conducive to inhibiting the growth of lithium dendrites. In addition, in the direction extending outward from the side close to the first region 131, the thickness of the inactive material layer 13 in the second region 132 is gradually reduced, which can further alleviate the pole piece 211 being cut by the edge of the positive pole piece 10 under pressure, and can reduce the weight of the positive pole piece 10 and improve the energy density of the battery.

[0087] See also Figures 11 to 13 In some embodiments, the tab lead-out portion 212 is provided with a tab lead-out foil 22 composited with the lithium metal foil 21, and the tab lead-out foil 22 is connected with a tab connecting piece 23. In addition to the fact that the lithium metal foil 21 is easily cut by the edge of the positive electrode under pressure, the battery using the lithium metal foil 21 as the negative electrode plate 20 also has the problem of difficulty in leading out and welding the negative electrode tab. In this regard, the present application provides a tab lead-out portion 212 on the lithium metal foil 21, and the tab lead-out portion 212 is provided with a tab lead-out foil 22 composited with the lithium metal foil 21, and the tab lead-out foil 22 is connected with a tab connecting piece 23. In this way, the negative electrode tab can be welded on the tab connecting piece 23, which greatly reduces the difficulty of leading out and welding the negative electrode tab. The tab lead-out foil 22 and the lithium metal foil 21 of the tab lead-out portion 212 are composited to play the role of collecting current, and at the same time can improve the strength of the tab lead-out portion 212.

[0088] It is understood that the tab lead-out foil 22 needs to be a metal foil with good conductivity. As a specific example, the tab lead-out foil 22 can be a copper foil.

[0089] In some embodiments, the tab lead-out portion 212 is located at one end of the pole piece portion 211, and the width f of the tab lead-out portion 212 can be 1 mm to 10 mm, and can be 1 mm to 3 mm; the thickness of the tab lead-out foil 22 can be 2 μm to 20 μm, and can be 2 μm to 5 μm; the width of the lithium metal foil 21 can be 10 mm to 500 mm. The thickness of the lithium metal foil 21 can be 5 μm to 200 μm, and can be 10 μm to 50 μm, and can be 30 μm to 50 μm. The thickness of the lithium metal foil 21 within this range can enable the battery to have a higher energy density and a longer cycle life.

[0090] In some embodiments, the tab lead-out foil 22 of the tab lead-out portion 212 can be attached to the lithium metal foil 21 by rolling. Specifically, the tab lead-out foil 22 can be sandwiched between two lithium metal foils 21, and the two lithium metal foils 21 and the tab lead-out foil 22 can be rolled together under heating conditions (see Fig.12 ). Since the lithium metal foil 21 has good ductility under heating conditions, it can ensure that the tab lead foil 22 is sandwiched in the middle without causing a thickness difference at the junction of the tab lead portion 212 and the pole piece portion 211, and will not affect the thickness uniformity of the battery cell edge. When rolling and laminating the tab lead foil 22, a part of the tab lead foil 22 can be extended outside the lithium metal foil 21 to form a blank area at one end (see Fig.13 ), after rolling and laminating, the blank area is cut according to the required size to form the tab connection sheet 23. In this way, the tab connection sheet 23 and the tab lead foil 22 are an integrated structure.

[0091] See also Figure 7 In some embodiments, the orthographic projection of the outer edge of the tab lead-out portion 212 on the positive electrode sheet 10 is within the range of the inactive material layer 13. Although the strength of the tab lead-out portion 212 is improved compared to the strength of the pure lithium metal foil 21 due to the tab lead-out foil 22 being covered, it is not ruled out that the tab lead-out portion 212 may be cut by the edge of the positive electrode sheet 10 when the thickness of the tab lead-out foil 22 is relatively thin. In this regard, by making the orthographic projection of the outer edge of the tab lead-out portion 212 on the positive electrode sheet 10 within the range of the inactive material layer 13, that is, the inactive material layer 13 can cover the outer edge of the tab lead-out portion 212, it can alleviate the tab lead-out portion 212 from being cut by the edge of the positive electrode sheet 10 under pressure during the battery charging and discharging process, and further improve the cycle life of the battery.

[0092] See also Fig.11 In some embodiments, the width of the tab connecting piece 23 is c, the length of the tab lead foil 22 is d, the width of the end of the lithium metal foil 21 close to the tab connecting piece 23 is e, and c≤d≤e. That is, the length of the tab lead foil 22 is greater than or equal to the width of the tab connecting piece 23, and less than or equal to the width of the end of the lithium metal foil 21 close to the tab connecting piece 23. Generally speaking, the length of the tab lead foil 22 needs to be set longer to better collect current. In a specific example, the length of the tab lead foil 22 is equal to the width of the end of the lithium metal foil 21 close to the tab connecting piece 23.

[0093] In some embodiments, the third aspect of the present application provides an electrical device, which includes the battery of the second aspect of the present application.

[0094] The battery and the electrical device of the present application will be described below with reference to the accompanying drawings as appropriate.

[0095] Unless otherwise specified, the components, material types or contents of the batteries mentioned apply to both lithium-ion batteries and sodium-ion batteries.

[0096] In one embodiment of the present application, a battery is provided.

[0097] Typically, a battery includes a positive electrode sheet, a negative electrode sheet, an electrolyte, and a separator. During the battery charge and discharge process, active ions are embedded and removed back and forth between the positive electrode sheet and the negative electrode sheet. The electrolyte plays the role of conducting ions between the positive electrode sheet and the negative electrode sheet. The separator is set between the positive electrode sheet and the negative electrode sheet, mainly to prevent the positive and negative electrodes from short-circuiting, while allowing ions to pass through.

[0098] Positive electrode

[0099] The positive electrode sheet includes a positive electrode current collector and an active material layer disposed on at least one surface of the positive electrode current collector.

[0100] As a non-limiting example, the positive electrode current collector has two surfaces opposite to each other in its thickness direction, and the active material layer is disposed on any one or both of the two opposite surfaces of the positive electrode current collector.

[0101] In some embodiments, the positive electrode plate adopts the positive electrode plate of the first aspect of the present application.

[0102] In some embodiments, the positive electrode current collector may be a metal foil or a composite current collector. For example, aluminum foil may be used as the metal foil. The composite current collector may include a polymer material base layer and a metal layer formed on at least one surface of the polymer material base layer. The composite current collector may be obtained by forming a metal material on a polymer material substrate. In the positive electrode current collector, non-limiting examples of the metal material may include one or more of aluminum, aluminum alloy, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy. In the positive electrode current collector, non-limiting examples of the polymer material substrate may include one or more of substrates such as polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.

[0103] In some embodiments, the positive electrode active material may include a positive electrode active material for a battery known in the art.

[0104] As a non-limiting example, the positive active material of the lithium-ion battery may include one or more of the following materials: lithium-containing phosphates with an olivine structure, lithium transition metal oxides and their respective modified compounds. However, the present application is not limited to these materials, and other traditional materials that can be used as positive active materials for batteries can also be used. These positive active materials can be used alone or in combination of two or more. Among them, examples of lithium transition metal oxides may include, but are not limited to, one or more of lithium cobalt oxide, lithium nickel oxide, lithium manganese oxide, lithium nickel cobalt oxide, lithium manganese cobalt oxide, lithium nickel manganese oxide, lithium nickel cobalt manganese oxide and their modified compounds. Non-limiting examples of lithium-containing phosphates with an olivine structure may include, but are not limited to, one or more of lithium iron phosphate, a composite material of lithium iron phosphate and carbon, lithium manganese phosphate, a composite material of lithium manganese phosphate and carbon, lithium iron manganese phosphate, and a composite material of lithium iron manganese phosphate and carbon. Non-limiting examples of lithium cobalt oxides may include LiCoO2; non-limiting examples of lithium nickel oxides may include LiNiO2; non-limiting examples of lithium manganese oxides may include LiMnO2, LiMn2O4, etc.; non-limiting examples of lithium nickel cobalt manganese oxides may include LiNi 1 / 3Co 1 / 3 Mn 1 / 3 O2 (also referred to as NCM 333 )、LiNi 0.5 Co 0.2 Mn 0.3 O2 (also referred to as NCM 523 )、LiNi 0.5 Co 0.25 Mn 0.25 O2 (also referred to as NCM 211 )、LiNi 0.6 Co 0.2 Mn 0.2 O2 (also referred to as NCM 622 )、LiNi 0.8 Co 0.1 Mn 0.1 O2 (also referred to as NCM 811 ) etc.; Non-limiting examples of lithium nickel cobalt aluminum oxide may include LiNi 0.8 Co 0.15 Al 0.05 O2.

[0105] It is understandable that the battery will be accompanied by lithium (Li) deintercalation and consumption during the charging and discharging process, and the content of Li in the positive electrode plate is different when the battery is discharged to different states. In the list of positive electrode materials in this application, unless otherwise specified, the content of Li is the initial state of the material. The positive electrode material is applied to the positive electrode plate in the battery system, and after the charge and discharge cycle, the content of Li in the positive electrode material contained in the plate usually changes. Among them, the content of Li can be measured by molar content, but is not limited to this. Regarding "the content of Li is the initial state of the material", the initial state of the material refers to the state before the material is added to the positive electrode slurry. It is understandable that the new material obtained by appropriate modification on the basis of the listed positive electrode materials is also within the scope of the positive electrode material. The aforementioned appropriate modification refers to the acceptable modification method for the positive electrode material, and non-limiting examples include coating modification.

[0106] In the list of positive electrode materials in this application, the content of oxygen (O) is only a theoretical state value. The release of oxygen from the lattice will cause the molar content of oxygen to change, and the actual content of O will fluctuate. Among them, the content of O can be measured by molar content, but is not limited to this.

[0107] As a non-limiting example, the positive electrode active material of the sodium ion battery may include one or more of the following materials: one or more of sodium transition metal oxides, polyanionic compounds, and Prussian blue compounds. However, the present application is not limited to these materials, and other conventionally known materials that can be used as positive electrode active materials for sodium ion batteries may also be used.

[0108] As an optional technical solution of the present application, in the sodium transition metal oxide, the transition metal can be one or more of Mn, Fe, Ni, Co, Cr, Cu, Ti, Zn, V, Zr and Ce. Sodium transition metal oxide is, for example, Na x MO2, wherein M is one or more of Ti, V, Mn, Co, Ni, Fe, Cr and Cu, and 0<x≤1.

[0109] As an optional technical solution of the present application, the polyanionic compound can be a compound having sodium ions, transition metal ions and tetrahedral (YO4) n- A class of compounds with anionic units. The transition metal can be one or more of Mn, Fe, Ni, Co, Cr, Cu, Ti, Zn, V, Zr and Ce; Y can be one or more of P, S and Si; n represents (YO4) n- valence state.

[0110] Polyanionic compounds can also be those with sodium ions, transition metal ions, tetrahedral (YO4) n-A class of compounds with anion units and halogen anions. The transition metal can be one or more of Mn, Fe, Ni, Co, Cr, Cu, Ti, Zn, V, Zr and Ce; Y can be one or more of P, S and Si, and n represents (YO4) n- valence state; the halogen can be one or more of F, Cl and Br.

[0111] Polyanionic compounds can also be sodium ions, tetrahedral (YO4) n- Anion unit, polyhedral unit (ZO y ) m+ and an optional halogen anion. Y can be one or more of P, S and Si, and n represents (YO4) n- valence state; Z represents a transition metal, which may be one or more of Mn, Fe, Ni, Co, Cr, Cu, Ti, Zn, V, Zr and Ce; m represents (ZO y ) m+ valence state; the halogen can be one or more of F, Cl and Br.

[0112] Polyanionic compounds include NaFePO4, Na3V2(PO4)3 (sodium vanadium phosphate, abbreviated as NVP), Na4Fe3(PO4)2 (P2O7), NaM'PO4F (M' is one or more of V, Fe, Mn and Ni) and Na3(VO y )2(PO4)2F 3-2y One or more of (0≤y≤1).

[0113] Prussian blue compounds can be sodium ions, transition metal ions and cyanide ions (CN - ) compounds. The transition metal may be one or more of Mn, Fe, Ni, Co, Cr, Cu, Ti, Zn, V, Zr and Ce. Prussian blue compounds are, for example, Na a Me b Me' c (CN)6, wherein Me and Me' are each independently one or more of Ni, Cu, Fe, Mn, Co and Zn, 0<a≤2, 0<b<1, 0<c<1.

[0114] The weight ratio of the positive electrode active material in the active material layer is 80 wt % to 100 wt % based on the total weight of the active material layer.

[0115] In some embodiments, the active material layer may also optionally include a binder. As a non-limiting example, the binder may include one or more of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), vinylidene fluoride-tetrafluoroethylene-propylene terpolymer, vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer, and fluorine-containing acrylate resin. The weight ratio of the binder in the active material layer is 0 wt % to 20 wt %, based on the total weight of the active material layer.

[0116] In some embodiments, the active material layer may further include a conductive agent. As a non-limiting example, the conductive agent may include one or more of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers. The weight ratio of the conductive agent in the active material layer is 0 wt % to 20 wt %, based on the total weight of the active material layer.

[0117] In some embodiments, the positive electrode sheet can be prepared by the following method: the components for preparing the positive electrode sheet, such as the positive electrode active material, the conductive agent, the binder and any other components are dispersed in a solvent (such as N-methylpyrrolidone) to form a positive electrode slurry, wherein the positive electrode slurry has a solid content of 40wt% to 80wt%, and the viscosity at room temperature is adjusted to 5000mPa·s to 25000mPa·s, the positive electrode slurry is coated on the surface of the positive electrode collector, and after drying, the positive electrode sheet is formed by cold rolling; the positive electrode powder coating unit surface density is 150mg / m 2 ~350 mg / m 2 The compaction density of the positive electrode is 3.0g / cm 3 ~3.6g / cm 3 , optional 3.3g / cm 3 ~3.5g / cm 3 .

[0118] The calculation formula of the compacted density is:

[0119] Compacted density = coating surface density / (thickness of the electrode after extrusion - thickness of the current collector).

[0120] The mass M of the positive electrode active material per unit area of ​​the positive electrode film can be obtained by weighing using a standard balance.

[0121] The thickness T of the positive electrode film can be measured by using a micrometer, for example, a Mitutoyo 293-100 micrometer with an accuracy of 0.1 μm. It should be noted that the thickness of the positive electrode film described in this application refers to the thickness of the positive electrode film in the positive electrode sheet used for assembling the battery after cold pressing.

[0122] Negative electrode

[0123] The negative electrode sheet adopts the negative electrode sheet including lithium metal foil in the present application.

[0124] Electrolytes

[0125] The electrolyte has the function of conducting ions between the positive electrode and the negative electrode. The present application has no particular restrictions on the type of electrolyte, which can be selected according to needs. For example, the electrolyte can be liquid, gel or all-solid.

[0126] In some embodiments, the electrolyte is an electrolyte solution, which includes an electrolyte salt and a solvent.

[0127] In some embodiments, the electrolyte salt of the lithium ion battery may include one or more of lithium hexafluorophosphate (LiPF6), lithium tetrafluoroborate (LiBF4), lithium perchlorate (LiClO4), lithium hexafluoroarsenate (LiAsF6), lithium bis(fluorosulfonyl)imide (LiFSI), lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), lithium trifluoromethanesulfonate (LiTFS), lithium difluorooxalatoborate (LiDFOB), lithium dioxalatoborate (LiBOB), lithium difluorophosphate (LiPO2F2), lithium difluorobis(oxalatophosphate) (LiDFOP) and lithium tetrafluorooxalatophosphate (LiTFOP).

[0128] In some embodiments, the solvent may include fluoroethylene carbonate (FEC), ethylene carbonate (EC), propylene carbonate (PC), ethyl methyl carbonate (EMC), diethyl carbonate (DEC), dimethyl carbonate (DMC), dipropyl carbonate (DPC), methyl propyl carbonate (MPC), ethyl propyl carbonate (EPC), butylene carbonate (BC), methyl formate (MF), methyl acetate (MA), ethyl acetate (EA), propyl acetate (PA), methyl propionate (MP), ethyl propionate (EP), propyl propionate (PP), methyl butyrate (MB), ethyl butyrate (EB), 1,4-butyrolactone (GBL), sulfolane (SF), dimethyl sulfone (MSM), methyl ethyl sulfone ( EMS and diethyl sulfone (ESE), methyl ether (DME), ethyl ether (DEE), propyl ether (DPE), butyl ether (DBE), methyl ethyl ether (MEE), methyl propyl ether (MPE), methyl butyl ether (MBE), ethyl propyl ether (EPE), ethyl butyl ether (EBE), propyl butyl ether (PBE), dimethoxymethane (DMM), diethoxymethane (DEM), dipropoxymethane (DPM), dimethoxyethane (DME), dimethoxypropane (DMP), diethoxyethane (DEE), ethylene glycol methyl ethyl ether (EGEME), diethylene glycol dimethyl ether (DEGDME), triethylene glycol dimethyl ether (TEGDME), tetraethylene glycol dimethyl ether (TEGDME), tetrahydrofuran (THF), 1,3-dioxolane (DOL), tetrahydropyran (THP), 1,3-dioxane (1,3-DX), 1,4-dioxane (1,4-DX), fluorobenzene, p-difluorobenzene, m-difluorobenzene, o-difluorobenzene, trifluorotoluene, trifluoromethoxybenzene, decafluoropentane, 1,1,2,2-tetrafluoroethyl-2,2,3,3-tetrafluoropropyl ether, 1,2-dimethoxy-1,1,2,2-tetrafluoroethane, 1,2-bis(difluoromethoxy)ethane, 1,2-bis(trifluoromethoxy)ethane, 1,2-diethoxy-1,1,2,2-tetrafluoroethane, 1,2-bis(1,1,2,2-tetrafluoroethoxy)ethane, bis(2,2,2-trifluoroethyl) ether, bis( The invention can be selected from the group consisting of 1H,1H,5H-octafluoropentyl-1,1,2,2-tetrafluoroethyl ether, ethyl trifluoromethyl ether, difluoromethyl-2,2,3,3,3-pentafluoropropyl ether, heptafluoropropyl-1,2,2,2-tetrafluoroethyl ether, difluoromethyl 2,2,3,3-tetrafluoropropyl ether, perfluoroisopropyl methyl ether, 1,1,2,2-tetrafluoroethyl-2,2,2-trifluoroethyl ether, ethyl-1,1,2,2-tetrafluoroethyl ether, ethyl-2,2,2-tetrafluoroethyl ether, bis(1,1,2,2-tetrafluoroethyl) ether, N,N-dimethylfluorosulfonamide, and N,N-dimethyltrifluoromethanesulfonamide.

[0129] In some embodiments, the electrolyte may further include additives, such as negative electrode film-forming additives, positive electrode film-forming additives, and additives that can improve certain battery properties, such as additives that improve battery overcharge performance, additives that improve battery high or low temperature performance, etc.

[0130] In some embodiments, the additives in the electrolyte may include, but are not limited to, one or more of fluoroethylene carbonate (FEC), difluoroethylene carbonate (DFEC), trifluoromethylethylene carbonate (TFPC), and the like.

[0131] Isolation film

[0132] In some embodiments, the battery further includes a separator. The present application has no particular limitation on the type of separator, and any known porous separator with good chemical stability and mechanical stability can be selected.

[0133] In some embodiments, the material of the isolation membrane may include one or more of glass fiber, non-woven fabric, polyethylene, polypropylene and polyvinylidene fluoride. The isolation membrane may be a single-layer film or a multi-layer composite film, without particular limitation. When the isolation membrane is a multi-layer composite film, the materials of each layer may be the same or different, without particular limitation.

[0134] In some embodiments, the isolation film has a thickness of 6 μm to 40 μm, and may be 12 μm to 20 μm.

[0135] In some embodiments, the positive electrode sheet, the negative electrode sheet, and the separator may be formed into an electrode assembly by a winding process or a lamination process.

[0136] In some embodiments, the battery may include an outer packaging, which may be used to encapsulate the electrode assembly and the electrolyte.

[0137] In some embodiments, the outer packaging of the battery may be a hard shell, such as a hard plastic shell, an aluminum shell, a steel shell, etc. The outer packaging of the battery may also be a soft package, such as a bag-type soft package. The material of the soft package may be plastic, and further, non-limiting examples of plastic may include one or more of polypropylene, polybutylene terephthalate, and polybutylene succinate.

[0138] The battery includes at least one battery cell. The battery may include one or more battery cells.

[0139] In this application, unless otherwise specified, "battery cell" refers to a basic unit that can realize the mutual conversion of chemical energy and electrical energy, and further, generally speaking, at least includes a positive electrode sheet, a negative electrode sheet and an electrolyte. During the battery charging and discharging process, active ions are embedded and released back and forth between the positive electrode sheet and the negative electrode sheet. The electrolyte plays the role of conducting active ions between the positive electrode sheet and the negative electrode sheet.

[0140] The present application has no particular limitation on the shape of the battery cell, which may be cylindrical, square or any other shape. Fig.14 The battery cell 5 is a square structure as an example.

[0141] In some embodiments, reference Fig.15 , the outer packaging may include a shell 51 and a cover plate 53. Among them, the shell 51 may 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 51 has an opening connected to the receiving cavity, and the cover plate 53 can be covered on the opening to close the receiving cavity. The positive electrode sheet, the negative electrode sheet and the isolation membrane can form an electrode assembly 52 through a winding process or a lamination process. The electrode assembly 52 is encapsulated in the receiving cavity. The electrolyte is infiltrated in the electrode assembly 52. ​​The number of electrode assemblies 52 contained in the battery cell 5 can be one or more, and those skilled in the art can select according to specific actual needs.

[0142] In some embodiments, the battery cells 5 can be assembled into a battery module. The number of battery cells 5 contained in the battery module can be one or more, and the specific number can be selected by those skilled in the art according to the application and capacity of the battery module.

[0143] In the battery module, the plurality of battery cells 5 may be arranged in sequence along the length direction of the battery module. Of course, they may also be arranged in any other manner. Further, the plurality of battery cells 5 may be fixed by fasteners.

[0144] Optionally, the battery module may further include a housing having a receiving space, and the plurality of battery cells 5 are received in the receiving space.

[0145] In some embodiments, the battery modules described above may also be assembled into a battery pack. The battery pack may contain one or more battery modules, and the specific number may be selected by those skilled in the art according to the application and capacity of the battery pack.

[0146] The battery pack may include a battery box and a plurality of battery modules disposed in the battery box. The battery box includes an upper box body and a lower box body, and the upper box body can be covered on the lower box body to form a closed space for accommodating the battery modules. The plurality of battery modules can be arranged in the battery box in any manner.

[0147] In addition, the present application also provides an electrical device, which includes at least one of the batteries, battery modules, or battery packs provided in the present application. The battery, battery module, or battery pack can be used as a power source for the electrical device, and can also be used as an energy storage unit for the electrical device. The electrical device may include mobile devices (such as mobile phones, laptops, etc.), electric vehicles (such as pure electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, electric bicycles, electric scooters, electric golf carts, electric trucks, etc.), electric trains, ships and satellites, energy storage systems, etc., but are not limited thereto.

[0148] As the electrical device, a battery, a battery module or a battery pack may be selected according to its usage requirements.

[0149] Fig.16 The power consumption device 6 is taken as an example. The power consumption device is a pure electric vehicle, a hybrid electric vehicle, or a plug-in hybrid electric vehicle, etc. In order to meet the power consumption device's requirements for high power and high energy density of the battery, a battery pack or a battery module can be used.

[0150] As another example, the device may be a mobile phone, a tablet computer, a notebook computer, etc. The device is usually required to be light and thin, and a battery may be used as a power source.

[0151] The following are some examples.

[0152] In order to make the technical problems, technical solutions and beneficial effects solved by the present application clearer, the present application will be further described in detail below in conjunction with the embodiments and drawings. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all of the embodiments. The following description of at least one exemplary embodiment is actually only illustrative and is by no means intended to limit the present application and its applications. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in the field without creative work are within the scope of protection of the present application.

[0153] If no specific techniques or conditions are specified in the examples, the techniques or conditions described in the literature in the field or the product instructions are used. If no manufacturer is specified for the reagents or instruments used, they are all conventional products that can be purchased commercially.

[0154] 1. Implementation

[0155] Embodiment 1:

[0156] 1) Preparation of positive electrode

[0157] The positive electrode active material NCM 811, Ketjen black as a conductive agent, and polyvinylidene fluoride as a binder are stirred and dispersed in N-methylpyrrolidone (NMP) at a mass ratio of 98:1:1 to prepare a positive electrode slurry, which is coated on a 7μm thick positive electrode current collector aluminum foil, and an active material layer is formed on the positive electrode current collector after being compacted by a cold press; a mixed slurry of polyvinylidene fluoride and alumina particles is coated on the positive electrode current collector, and the mass ratio of polyvinylidene fluoride to alumina particles in the mixed slurry is 1:9, and the mixed slurry is made to surround the active material layer, and an inactive material layer is formed around the active material layer after curing to obtain a positive electrode sheet. The thickness of the inactive material layer is equal to the thickness of the active material layer.

[0158] 2) Negative electrode sheet preparation

[0159] Two lithium metal foils are stacked, and copper foil is sandwiched at one end of the two lithium metal foils, wherein one end of the copper foil extends from the end of the lithium metal foil to form a blank area; rolling is performed under heating conditions to laminate the two lithium metal foils and the copper foil into one, and the area on the lithium metal foil laminated with copper foil forms the tab lead-out part, and the area not laminated with copper foil forms the pole piece part; the blank area of ​​the copper foil is cut to form a tab connecting piece, thereby obtaining a negative pole piece. Among them, the thickness of the lithium metal foil formed as a whole after lamination is 30μm, and the length of the copper foil in the tab lead-out part is equal to the width of the lithium metal foil.

[0160] 3) Preparation of electrolyte

[0161] Lithium salt LiPF6 is added to a mixed solvent of ethylene carbonate (EC) and ethyl methyl carbonate (EMC) in a mass ratio of 35:65, and mixed evenly to obtain an electrolyte, wherein the molar concentration of LiPF6 in the electrolyte is 1 mol / L.

[0162] 4) Isolation film

[0163] A 12 μm thick polyethylene porous membrane was selected as the isolation membrane.

[0164] 5) Preparation of lithium metal batteries

[0165] The positive electrode sheet, the separator, and the negative electrode sheet prepared above are stacked in order, so that the separator is located between the positive electrode sheet and the negative electrode sheet to play a role of isolation, and then wound to obtain a bare battery cell; the schematic diagram of the stacking of the positive electrode sheet and the negative electrode sheet is as shown in Figure 7 As shown;

[0166] Among them, the orthographic projection of the active material layer of the positive electrode sheet on the negative electrode sheet is located within the range of the electrode sheet portion of the negative electrode sheet; the orthographic projection of the edge of the electrode sheet portion of the negative electrode sheet on the positive electrode sheet is located within the range of the inactive material layer; the orthographic projection of the outer edge of the electrode tab lead-out portion on the positive electrode sheet is located within the range of the inactive material layer; the spacing a between the orthographic projection of the edge of the electrode sheet portion on the positive electrode sheet and the outer edge of the inactive material layer is 1.5 mm; the spacing b between the orthographic projection of the edge of the electrode sheet portion on the positive electrode sheet and the outer edge of the active material layer is 1.5 mm;

[0167] The bare battery cell is inserted into the battery housing, and a lithium metal battery is obtained through the processes of baking, liquid injection, static, packaging, formation, and capacity division. The electrolyte injection coefficient is 1.5g / Ah.

[0168] Embodiment 2:

[0169] This embodiment is basically the same as the embodiment 1, except that: the positive electrode current collector adopts a composite current collector; the positive electrode current collector comprises a polyimide polymer support layer, metal aluminum is evaporated on both the upper and lower surfaces of the polymer support layer as a conductive layer, and the active material layer and the inactive material layer are both arranged on the conductive layer; the thickness of the polymer support layer is 3 μm, and the thickness of the conductive layer is 2 μm. The structural schematic diagram of the positive electrode sheet in this embodiment is shown in FIG. Figure 2 As shown; the schematic diagram of the structure of the positive electrode current collector is as shown Figure 5 shown.

[0170] Embodiment 3:

[0171] This embodiment is basically the same as embodiment 2, except that the thickness of the inactive material layer is designed to be gradual; the thickness of the inactive material layer gradually decreases from being equal to the thickness of the active material layer to zero in the direction extending outward from the side of the inactive material layer close to the active material layer. Figure 3 shown.

[0172] Embodiment 4:

[0173] This embodiment is basically the same as embodiment 2, with the only difference being that: the thickness of the inactive material layer is designed in different regions; the inactive material layer includes a first region and a second region, the first region is close to the active material layer, the second region is located on the side of the first region away from the active material layer, and the thickness of the inactive material layer in the first region is equal to the thickness of the active material layer; the width of the first region is equal to the distance b between the orthographic projection of the edge of the electrode portion on the positive electrode and the outer edge of the active material layer, which is 1.5 mm; in the direction extending outward from the side close to the first region, the thickness of the inactive material layer in the second region gradually decreases from being equal to the thickness of the active material layer to zero. The structural schematic diagram of the positive electrode in this embodiment is shown in FIG. Figure 4 shown.

[0174] Embodiment 5:

[0175] This embodiment is basically the same as Embodiment 2, with the only difference being that: the spacing a between the orthographic projection of the edge of the electrode portion in the bare cell on the positive electrode sheet and the outer edge of the inactive material layer is 1 mm; the spacing b between the orthographic projection of the edge of the electrode portion on the positive electrode sheet and the outer edge of the active material layer is 1 mm.

[0176] Embodiment 6:

[0177] This embodiment is basically the same as Embodiment 2, with the only difference being that: the spacing a between the orthographic projection of the edge of the electrode portion in the bare cell on the positive electrode sheet and the outer edge of the inactive material layer is 3 mm; the spacing b between the orthographic projection of the edge of the electrode portion on the positive electrode sheet and the outer edge of the active material layer is 3 mm.

[0178] Embodiment 7:

[0179] This embodiment is basically the same as Embodiment 2, with the only difference being that: the distance a between the orthographic projection of the edge of the electrode portion in the bare cell on the positive electrode sheet and the outer edge of the inactive material layer is 5 mm; the distance b between the orthographic projection of the edge of the electrode portion on the positive electrode sheet and the outer edge of the active material layer is 5 mm.

[0180] Embodiment 8:

[0181] This embodiment is basically the same as Embodiment 7, except that the orthographic projection of the outer edge of the tab lead-out portion on the positive electrode sheet is outside the range of the inactive material layer, that is, the inactive material layer cannot cover the outer edge of the tab lead-out portion. Figure 6 shown.

[0182] Embodiment 9:

[0183] This embodiment is basically the same as Embodiment 2, except that the material of the inactive material layer in the positive electrode plate is different; in this embodiment, the inactive material layer is a mixture of polyvinylidene fluoride-hexafluoropropylene copolymer and titanium oxide particles.

[0184] Embodiment 10:

[0185] This embodiment is basically the same as Embodiment 2, except that the thickness of the negative electrode lithium metal foil is 10 μm.

[0186] Embodiment 11:

[0187] This embodiment is basically the same as Embodiment 2, except that the thickness of the negative electrode lithium metal foil is 50 μm.

[0188] Embodiment 12:

[0189] This embodiment is substantially the same as the embodiment 2, except that: the negative electrode uses a copper foil with a thickness of 10 μm as the negative electrode current collector, and a lithium metal layer with a thickness of 15 μm is formed on each of the two surfaces of the copper foil.

[0190] 2. Comparison

[0191] Comparative Example 1:

[0192] This comparative example is basically the same as Example 2, with the only difference being that: an active material layer is disposed on the entire conductive layer of the positive electrode sheet, and no inactive material layer is disposed around the active material layer; and the positive projection of the active material layer of the positive electrode sheet on the negative electrode sheet is located within the range of the electrode sheet portion of the negative electrode sheet; the edge of the electrode sheet portion of the negative electrode sheet exceeds the range of the active material layer of the positive electrode sheet, that is, the electrode sheet portion exceeds the active material layer of the positive electrode sheet in both the length direction and the width direction of the electrode sheet, thereby forming an overhang area.

[0193] Comparative Example 2:

[0194] This comparative example is basically the same as Example 10, with the only difference being that: an active material layer is arranged on the entire conductive layer of the positive electrode sheet, and no inactive material layer is arranged around the active material layer; and the orthographic projection of the active material layer of the positive electrode sheet on the negative electrode sheet is located within the range of the electrode sheet portion of the negative electrode sheet; the edge of the electrode sheet portion of the negative electrode sheet exceeds the range of the active material layer of the positive electrode sheet, that is, the electrode sheet portion exceeds the active material layer of the positive electrode sheet in both the length direction and the width direction of the electrode sheet, thereby forming an overhang area.

[0195] 3. Performance Test

[0196] 1) Battery energy density calculation

[0197] Weigh the mass of the lithium metal battery cell prepared above and record it as m. Then set the ambient temperature to 25°C, and then conduct the charge and discharge test. During the charging process, a constant current-constant voltage charging process is adopted. The constant current charging uses a rate of 0.1C. When the voltage is charged to 4.3V, it enters the constant voltage charging mode, and the cut-off current is set to 0.05C. After full charge, let the battery cell stand for 10 minutes, and then use a rate of 0.1C to perform a constant current discharge test, and the lower limit cut-off voltage is set to 2.8V. After the discharge is cut off, the total discharge energy is recorded as E0. The battery cell energy density e can be calculated by the following formula: e=E0 / m.

[0198] 2) Battery cycle life test

[0199] Take the battery cell with determined energy density, set the ambient temperature to 25°C, and perform charge and discharge cycles at a rate of 0.2C charging and 1C discharging. The cut-off voltages for charging and discharging are set to 4.3V and 2.8V, respectively, and the charging process adopts a constant current-constant voltage charging method. Specifically, when the 0.2C constant current charging reaches the cut-off voltage of 4.3V, continue to use a 4.3V constant voltage charging until the current decays to 0.05C. When the discharge capacity decays to 80% of the first cycle discharge capacity, the battery life is considered to be terminated, and the number of cycles at this time is the cycle life of the battery cell.

[0200] The parameters and performance test results of the lithium metal batteries of the above embodiments and comparative examples are shown in Table 1.

[0201] Table 1

[0202]

[0203]

[0204]

[0205] From Table 1, we can see that:

[0206] The lithium metal batteries of the embodiments of the present application have higher energy density and longer cycle life.

[0207] By comparing Example 1 with Example 2, it can be seen that the use of a composite current collector in the positive electrode can significantly improve the energy density of the battery while maintaining the cycle life.

[0208] By comparing Example 2 and Example 3, it can be seen that the inactive material layer of the positive electrode plate in Example 3 adopts a thickness gradient design (that is, in the direction extending outward from the side of the inactive material layer close to the active material layer, the thickness of the inactive material layer gradually decreases from being equal to the thickness of the active material layer to zero), which can further improve the energy density of the battery.

[0209] By comparing Examples 2 to 4, it can be seen that the thickness of the inactive material layer of the positive electrode plate in Example 4 is divided into different regions, which can ensure that the lithium in the overhang area of ​​the negative electrode is in a pressurized state during the cycle, reduce the growth of lithium dendrites in this area, and achieve maximum weight reduction. The lithium metal battery of Example 4 has high energy density and long cycle performance.

[0210] By comparing Example 2 with Examples 5 to 7, it can be seen that by controlling the widths of a and b within the range of 1 mm to 5 mm, the battery can have both a higher energy density and a longer cycle life; further, by controlling the widths of a and b within the range of 1.5 mm to 3 mm, the energy density and cycle life of the battery can be better balanced.

[0211] By comparing Example 7 with Example 8, it can be seen that the inactive material layer in Example 7 covers the tab lead-out portion, which is beneficial to ensuring that the entire region of the negative electrode lithium metal foil is under pressure, and is more beneficial to extending the cycle life of the battery.

[0212] By comparing Example 2 with Examples 10 to 11, it can be seen that controlling the thickness of the negative electrode lithium metal foil within the range of 10μm to 50μm can make the battery have a high energy density and a long cycle life; further, controlling the thickness of the negative electrode lithium metal foil within the range of 30μm to 50μm can better balance the energy density and cycle life of the battery, thereby obtaining a battery with high energy density and long cycle life.

[0213] The negative electrode of the battery in Example 12 is made of 10 μm copper foil covered with 15 μm lithium metal layers on both sides. Although the cycle life of the battery is good, its energy density is lower than that of Example 2.

[0214] By comparing Example 2 with Comparative Examples 1-2, it can be seen that when the positive electrode sheet of the lithium metal battery does not use the positive electrode sheet of the present application, the cycle life of the battery is significantly reduced. The batteries of Comparative Examples 1-2 cannot achieve both high energy density and long cycle life.

[0215] The above description of various embodiments tends to emphasize the differences between the various embodiments. The same or similar aspects can be referenced to each other, and for the sake of brevity, they will not be repeated herein.

[0216] It should be noted that the present application is not limited to the above-mentioned embodiments. The above-mentioned embodiments are only examples, and the embodiments having the same structure as the technical idea and exerting the same effect within the scope of the technical solution of the present application are all included in the technical scope of the present application. In addition, without departing from the scope of the main purpose of the present application, various modifications that can be thought of by those skilled in the art to the embodiments and other methods of combining some of the constituent elements in the embodiments are also included in the scope of the present application.

Claims

1. A positive electrode sheet, characterized in that: The invention comprises a positive electrode current collector and an active material layer and an inactive material layer arranged on at least one surface of the positive electrode current collector, wherein the inactive material layer is arranged around the periphery of the active material layer, the active material layer comprises a positive electrode active material, and the active material layer and the inactive material layer are arranged in the same layer.

2. The positive electrode sheet according to claim 1, characterized in that: The material of the inactive material layer includes an insulating material, and the insulating material includes one or more of an organic insulating material and an inorganic insulating material.

3. The positive electrode sheet according to claim 1 or 2, characterized in that: Satisfy at least one of the following (1) to (2): (1) The organic insulating material includes an organic polymer, and the organic polymer includes one or more of polymethyl methacrylate, polyimide, polyethylene, polypropylene, polytetrafluoroethylene, polyvinylidene fluoride, and polyvinylidene fluoride-hexafluoropropylene copolymer; (2) The inorganic insulating material includes oxide particles, and the oxide particles include one or more of aluminum oxide particles and titanium oxide particles.

4. The positive electrode sheet according to any one of claims 1 to 3, characterized in that: The thickness of the inactive material layer is equal to the thickness of the active material layer.

5. The positive electrode sheet according to any one of claims 1 to 4, characterized in that: The thickness of the inactive material layer at a side close to the active material layer is greater than the thickness of the inactive material layer at a side far from the active material layer.

6. The positive electrode sheet according to any one of claims 1 to 5, characterized in that: The thickness of the inactive material layer gradually decreases in a direction extending outward from a side of the inactive material layer close to the active material layer.

7. The positive electrode sheet according to any one of claims 1 to 6, characterized in that: The inactive material layer includes a first region and a second region, the first region is close to the active material layer, the second region is located on the side of the first region away from the active material layer, the thickness of the inactive material layer in the first region is equal to the thickness of the active material layer; in a direction extending outward from the side close to the first region, the thickness of the inactive material layer in the second region gradually decreases.

8. The positive electrode sheet according to any one of claims 1 to 7, characterized in that: The positive electrode current collector comprises a polymer support layer and a conductive layer disposed on at least one surface of the polymer support layer, and the active material layer and the inactive material layer are disposed on a surface of the conductive layer away from the polymer support layer.

9. A battery, characterized in that: It comprises a positive electrode sheet and a negative electrode sheet which are stacked, the positive electrode sheet comprises the positive electrode sheet according to any one of claims 1 to 8, the negative electrode sheet comprises a lithium metal foil, the lithium metal foil comprises a pole piece portion and a tab lead portion connected to the pole piece portion, and the orthographic projection of the edge of the pole piece portion on the positive electrode sheet is located within the range of the inactive material layer.

10. The battery according to claim 9, characterized in that The distance between the orthographic projection of the edge of the pole piece on the positive pole piece and the outer edge of the inactive material layer is a, and a is 1 mm to 5 mm; optionally, a is 1.5 mm to 3 mm.

11. The battery according to claim 9 or 10, characterized in that: The orthographic projection of the active material layer on the negative electrode sheet is located within the range of the electrode sheet portion.

12. The battery according to claim 11, characterized in that The distance between the orthographic projection of the edge of the pole piece on the positive pole piece and the outer edge of the active material layer is b, and b is 1 mm to 5 mm; optionally, b is 1.5 mm to 3 mm.

13. The battery according to claim 12, characterized in that The inactive material layer includes a first region and a second region, the first region is close to the active material layer, and the second region is located on the side of the first region away from the active material layer; in a direction extending outward from the side close to the first region, the thickness of the inactive material layer in the second region gradually decreases; the thickness of the inactive material layer in the first region is equal to the thickness of the active material layer.

14. The battery according to any one of claims 9 to 13, characterized in that The orthographic projection of the outer edge of the tab lead-out portion on the positive electrode sheet is located within the range of the inactive material layer.

15. The battery according to any one of claims 9 to 14, characterized in that The tab lead-out portion is provided with a tab lead-out foil compounded with the lithium metal foil, and the tab lead-out foil is connected to a tab connecting piece.

16. The battery according to claim 15, characterized in that The width of the tab connecting piece is c, the length of the tab lead foil is d, the width of the lithium metal foil at one end close to the tab connecting piece is e, and c≤d≤e.

17. The battery according to any one of claims 9 to 16, characterized in that The thickness of the lithium metal foil is 10 μm to 50 μm, and can be 30 μm to 50 μm.

18. An electrical device, characterized in that: A battery comprising the battery according to any one of claims 9 to 17.

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