Naked battery cell, battery and electronic equipment

Abstract

The invention provides a naked battery cell, a battery and electronic equipment, the naked battery cell is in a winding state, the naked battery cell comprises a plurality of negative plates, a plurality of positive plates and a plurality of diaphragms, the plurality of negative plates and the plurality of positive plates are staggered and stacked, and each diaphragm is located between one positive plate and one negative plate. According to the naked battery cell provided by the embodiment of the invention, the plurality of negative plates and the plurality of positive plates are arranged, which is equivalent to connecting a plurality of existing naked battery cells in parallel, so that the internal resistance of a battery formed by assembling the naked battery cells can be effectively reduced on the premise of ensuring the same energy density, and the performance of the battery is favorably improved.

Description

Technical Field

[0001] The present application relates to the field of energy storage technology, and in particular to a bare cell, a battery and an electronic device. Background Art

[0002] The current battery system design model is inherent. Under the premise of maintaining the same battery energy density, the internal resistance of the battery is usually large, causing the battery to generate higher heat, thus affecting the battery performance. Summary of the invention

[0003] The purpose of the embodiments of the present application is to provide a bare cell, a battery and an electronic device, wherein the bare cell has a small internal resistance, thereby facilitating improving the performance of a battery assembled from the bare cell.

[0004] An embodiment of the present application provides a bare battery cell, which is in a wound state. The bare battery cell includes multiple negative electrode sheets, multiple positive electrode sheets and multiple separators. The multiple negative electrode sheets and the multiple positive electrode sheets are stacked alternately, and each separator is located between a positive electrode sheet and a negative electrode sheet.

[0005] Compared with the existing bare battery cells that only use one negative electrode sheet and one positive electrode sheet, the bare battery cells provided in the embodiments of the present application, by providing multiple negative electrode sheets and multiple positive electrode sheets, are equivalent to connecting multiple existing bare battery cells in parallel. Under the premise of ensuring the same energy density, the internal resistance of the battery formed by assembling the bare batteries can be effectively reduced, thereby helping to improve the performance of the battery.

[0006] In a possible implementation, different negative electrode sheets have different negative electrode layers, and / or different positive electrode sheets have different positive electrode layers.

[0007] In a possible implementation, the plurality of negative electrode sheets include a first negative electrode sheet and a second negative electrode sheet, the first negative electrode sheet and the second negative electrode sheet each include a negative electrode current collector, a first negative electrode layer and a second negative electrode layer, and the first negative electrode layer and the second negative electrode layer are respectively covered on both side surfaces of the negative electrode current collector along the thickness direction;

[0008] The plurality of positive electrode sheets include a first positive electrode sheet and a second positive electrode sheet, each of the first positive electrode sheet and the second positive electrode sheet includes a positive electrode current collector, a first positive electrode layer and a second positive electrode layer, and the first positive electrode layer and the second positive electrode layer are respectively covered on both side surfaces of the positive electrode current collector along the thickness direction;

[0009] The first positive electrode sheet is arranged opposite to the first negative electrode sheet, and the second positive electrode sheet is arranged opposite to the second negative electrode sheet.

[0010] In one possible implementation, the negative electrode active material of the first negative electrode layer in the first negative electrode sheet is different from the negative electrode active material of the second negative electrode layer;

[0011] The negative electrode active material of the first negative electrode layer in the second negative electrode sheet is different from the negative electrode active material of the second negative electrode layer, the negative electrode active material of the first negative electrode layer in the second negative electrode sheet is the same as the negative electrode active material of the first negative electrode layer in the first negative electrode sheet, and the negative electrode active material of the second negative electrode layer in the second negative electrode sheet is the same as the negative electrode active material of the second negative electrode layer in the first negative electrode sheet;

[0012] The first positive electrode layer and the second positive electrode layer in the first positive electrode sheet are different, and the first positive electrode layer and the second positive electrode layer in the second positive electrode sheet are different.

[0013] Since the type of negative electrode active material will affect the performance of the assembled battery, the first negative electrode layer and the second negative electrode layer in the first negative electrode sheet and the second negative electrode sheet are limited to use negative electrode active materials with different functions, so that the first negative electrode layer and the second negative electrode layer of the first negative electrode sheet and the second negative electrode sheet correspond to different functional surfaces. At the same time, by limiting and adjusting the first positive electrode layer and the second positive electrode layer in the first positive electrode sheet and the second positive electrode sheet to be different, the double sides of the first positive electrode sheet and the second positive electrode sheet are different, so that the double sides of the first positive electrode sheet are adapted to the different functional surfaces of the first negative electrode sheet, and the double sides of the second positive electrode sheet are adapted to the different functional surfaces of the second negative electrode sheet. Finally, the battery assembled with bare cells takes into account different functions, solving the problem that the existing battery has a single function and limits the battery's usage scenarios.

[0014] In one possible embodiment, the positive electrode active material of the first positive electrode layer in the first positive electrode sheet is the same as the positive electrode active material of the second positive electrode layer, the positive electrode active material of the first positive electrode layer in the second positive electrode sheet is the same as the positive electrode active material of the second positive electrode layer, and is the same as the positive electrode active material of the first positive electrode layer of the first positive electrode sheet.

[0015] In one possible embodiment, based on the mass of the first negative electrode layer of the first negative electrode sheet, the material of the first negative electrode layer of the first negative electrode sheet includes 90% to 99% of ordinary graphite, 0 to 10% of CMC, 0 to 10% of SBR and 0 to 10% of conductive carbon black, and based on the mass of the second negative electrode layer of the first negative electrode sheet, the material of the second negative electrode layer of the first negative electrode sheet includes 90% to 98% of fast-filling graphite, 0 to 10% of CMC, 0 to 10% of SBR and 0 to 10% of conductive carbon black;

[0016] Based on the mass of the first negative electrode layer of the second negative electrode sheet, the material of the first negative electrode layer of the second negative electrode sheet includes 90% to 99% of ordinary graphite, 0 to 10% of CMC, 0 to 10% of SBR and 0 to 10% of conductive carbon black; based on the mass of the second negative electrode layer of the second negative electrode sheet, the material of the second negative electrode layer of the second negative electrode sheet includes 90% to 98% of fast-charged graphite, 0 to 10% of CMC, 0 to 10% of SBR and 0 to 10% of conductive carbon black;

[0017] Based on the mass of the first positive electrode layer of the first positive electrode sheet, the material of the first positive electrode layer of the first positive electrode sheet includes 90% to 98% of lithium cobalt oxide, 0 to 10% of PVDF and 0 to 10% of conductive carbon black; based on the mass of the second positive electrode layer of the first positive electrode sheet, the material of the second positive electrode layer of the first positive electrode sheet includes 90% to 98% of lithium cobalt oxide, 0 to 10% of PVDF and 0 to 10% of conductive carbon black;

[0018] Based on the mass of the first positive electrode layer of the second positive electrode sheet, the material of the first positive electrode layer of the second positive electrode sheet includes 90% to 98% of lithium cobalt oxide, 0 to 10% of PVDF and 0 to 10% of conductive carbon black. Based on the mass of the second positive electrode layer of the second positive electrode sheet, the material of the second positive electrode layer of the second positive electrode sheet includes 90% to 98% of lithium cobalt oxide, 0 to 10% of PVDF and 0 to 10% of conductive carbon black.

[0019] In one possible embodiment, based on the mass of the first negative electrode layer of the first negative electrode sheet, the material of the first negative electrode layer of the first negative electrode sheet includes 90% to 98% of a silicon-carbon negative electrode, 0 to 10% of CMC, 0 to 10% of SBR, and 0 to 10% of conductive carbon black, the silicon-carbon negative electrode includes a silicon-carbon material and graphite, and the content of the silicon-carbon material is 1% to 98% based on the mass of the silicon-carbon negative electrode, and based on the mass of the second negative electrode layer of the first negative electrode sheet, the material of the second negative electrode layer of the first negative electrode sheet includes 90% to 99% of ordinary graphite, 0 to 10% of CMC, 0 to 10% of SBR, and 0 to 10% of conductive carbon black;

[0020] Based on the mass of the first negative electrode layer of the second negative electrode sheet, the material of the first negative electrode layer of the second negative electrode sheet includes 90% to 98% of silicon-carbon negative electrode, 0 to 10% of CMC, 0 to 10% of SBR and 0 to 10% of conductive carbon black; based on the mass of the second negative electrode layer of the second negative electrode sheet, the material of the second negative electrode layer of the second negative electrode sheet includes 90% to 99% of ordinary graphite, 0 to 10% of CMC, 0 to 10% of SBR and 0 to 10% of conductive carbon black;

[0021] Based on the mass of the first positive electrode layer of the first positive electrode sheet, the material of the first positive electrode layer of the first positive electrode sheet includes 90% to 98% of lithium cobalt oxide, 0 to 10% of PVDF and 0 to 10% of conductive carbon black; based on the mass of the second positive electrode layer of the first positive electrode sheet, the material of the second positive electrode layer of the first positive electrode sheet includes 90% to 98% of lithium cobalt oxide, 0 to 10% of PVDF and 0 to 10% of conductive carbon black;

[0022] Based on the mass of the first positive electrode layer of the second positive electrode sheet, the material of the first positive electrode layer of the second positive electrode sheet includes 90% to 98% of lithium cobalt oxide, 0 to 10% of PVDF and 0 to 10% of conductive carbon black, and the material of the second positive electrode layer of the second positive electrode sheet includes 90% to 98% of lithium cobalt oxide, 0 to 10% of PVDF and 0 to 10% of conductive carbon black.

[0023] In one possible implementation, the negative electrode active material of the first negative electrode layer in the first negative electrode sheet is different from the negative electrode active material of the second negative electrode layer;

[0024] The negative electrode active material of the first negative electrode layer in the second negative electrode sheet is different from the negative electrode active material of the second negative electrode layer, the negative electrode active material of the first negative electrode layer in the second negative electrode sheet is the same as the negative electrode active material of the first negative electrode layer in the first negative electrode sheet, and the negative electrode active material of the second negative electrode layer in the second negative electrode sheet is the same as the negative electrode active material of the second negative electrode layer in the first negative electrode sheet;

[0025] The first positive electrode layer in the first positive electrode sheet is the same as the second positive electrode layer, the first positive electrode layer in the second positive electrode sheet is the same as the second positive electrode layer, and the first positive electrode layer of the second positive electrode sheet is different from the first positive electrode layer of the first positive electrode sheet.

[0026] Since the type of negative electrode active material will affect the performance of the assembled battery, the first negative electrode layer and the second negative electrode layer in the first negative electrode sheet and the second negative electrode sheet are limited to use negative electrode active materials with different functions, so that the first negative electrode layer and the second negative electrode layer of the first negative electrode sheet and the second negative electrode sheet correspond to different functional surfaces. At the same time, by limiting the adjustment of the first positive electrode layer and the second positive electrode layer in the first positive electrode sheet to be the same, the double sides of the first positive electrode sheet are adjusted to be the same, so as to achieve the first positive electrode sheet to adapt to one functional surface of the first negative electrode sheet or the second negative electrode sheet. By adjusting the first positive electrode layer and the second positive electrode layer in the second positive electrode sheet to be the same, and the first positive electrode layer in the second positive electrode sheet to be different from the first positive electrode layer of the first positive electrode sheet, the double sides of the second positive electrode sheet are adjusted to be the same, and different from the first positive electrode layer of the first positive electrode sheet, so as to achieve the second positive electrode sheet to adapt to another functional surface in the first negative electrode sheet or the second negative electrode sheet. Finally, the battery assembled with bare cells takes into account different functions, solving the problem that the existing battery has a single function and limits the use scenarios of the battery.

[0027] In a possible implementation, the positive electrode active material of the first positive electrode layer of the second positive electrode sheet is different from the positive electrode active material of the first positive electrode layer of the first positive electrode sheet.

[0028] In one possible embodiment, based on the mass of the first negative electrode layer of the first negative electrode sheet, the material of the first negative electrode layer of the first negative electrode sheet includes 90% to 98% of ordinary graphite, 0 to 10% of CMC, 0 to 10% of SBR and 0 to 10% of conductive carbon black, and based on the mass of the second negative electrode layer of the first negative electrode sheet, the material of the second negative electrode layer of the first negative electrode sheet includes 90% to 98% of silicon-carbon negative electrode, 0 to 10% of CMC, 0 to 10% of SBR and 0 to 10% of conductive carbon black;

[0029] Based on the mass of the first negative electrode layer of the second negative electrode sheet, the material of the first negative electrode layer of the second negative electrode sheet includes 90% to 98% of ordinary graphite, 0 to 10% of CMC, 0 to 10% of SBR and 0 to 10% of conductive carbon black; based on the mass of the second negative electrode layer of the second negative electrode sheet, the material of the second negative electrode layer of the second negative electrode sheet includes 90% to 98% of silicon-carbon negative electrode, 0 to 10% of CMC, 0 to 10% of SBR and 0 to 10% of conductive carbon black;

[0030] The silicon-carbon negative electrode comprises silicon-carbon material and graphite, and the content of the silicon-carbon material is 1% to 98% based on the mass of the silicon-carbon negative electrode;

[0031] Based on the mass of the first positive electrode layer of the first positive electrode sheet, the material of the first positive electrode layer of the first positive electrode sheet includes 90% to 98% of lithium cobalt oxide, 0% to 10% of PVDF and 0% to 10% of conductive carbon black;

[0032] Based on the mass of the first positive electrode layer of the second positive electrode sheet, the material of the first positive electrode layer of the second positive electrode sheet includes 90% to 98% of the ternary five-series material, 0 to 10% of PVDF and 0 to 10% of conductive carbon black.

[0033] In one possible implementation, the first negative electrode layer of the first negative electrode sheet is the same as the second negative electrode layer of the first negative electrode sheet, the first negative electrode layer of the second negative electrode sheet is the same as the second negative electrode layer of the second negative electrode sheet, and the negative electrode active material of the first negative electrode layer of the second negative electrode sheet is different from the negative electrode active material of the first negative electrode layer of the first negative electrode sheet;

[0034] The first positive electrode layer of the first positive electrode sheet is different from the second positive electrode layer of the first positive electrode sheet, and the first positive electrode layer of the second positive electrode sheet is different from the second positive electrode layer of the second positive electrode sheet.

[0035] Since the type of negative electrode active material will affect the performance of the assembled battery, the first negative electrode layer of the first negative electrode sheet is limited to be the same as the second negative electrode layer of the first negative electrode sheet, so that the first negative electrode sheet has the same functional surface. By limiting the first negative electrode layer of the second negative electrode sheet to be the same as the second negative electrode layer of the second negative electrode sheet, and the negative electrode active material of the first negative electrode layer of the second negative electrode sheet is different from the negative electrode active material of the first negative electrode layer of the first negative electrode sheet, the second negative electrode sheet has the same functional surface on both sides, and has a different functional surface from the first negative electrode sheet. At the same time, by limiting and adjusting the first positive electrode sheet and the first positive electrode layer and the second positive electrode sheet to be different, the first positive electrode sheet and the second positive electrode sheet have different surfaces on both sides, so that one side of the first positive electrode sheet and the second positive electrode sheet is adapted to the functional surface of the first negative electrode sheet, and the other side is adapted to the functional surface of the second negative electrode sheet. Finally, the battery assembled with bare cells takes into account different functions, solving the problem that the existing battery has a single function and limits the use scenarios of the battery.

[0036] In a possible implementation, each positive electrode sheet includes a positive electrode current collector and a positive electrode layer covering a surface of the positive electrode current collector, and at least one positive electrode sheet further includes a passivation layer;

[0037] The passivation layer covers the surface of the positive electrode current collector, and the passivation layer is located between the positive electrode current collector and the positive electrode layer.

[0038] The passivation layer has good thermal stability. By setting the passivation layer on the surface of the positive electrode current collector, when the battery assembled with bare cells is subjected to abnormal mechanical damage such as puncture, extrusion, and falling, the passivation layer can protect the positive electrode current collector to avoid short circuit caused by contact between the positive electrode current collector and the negative electrode sheet, thereby avoiding the possibility of thermal runaway of the battery, thereby greatly improving the safety performance of the battery, and ultimately making the battery assembled with bare cells have both the original functions and safety functions.

[0039] In a possible implementation, the material of the passivation layer is lithium iron phosphate or aluminum oxide.

[0040] In a possible implementation, each positive electrode sheet includes a positive electrode layer, each negative electrode sheet includes a negative electrode layer, the positive electrode layers of the plurality of positive electrode sheets are the same, and the negative electrode layers of the plurality of negative electrode sheets are the same.

[0041] In one possible embodiment, each negative electrode sheet includes a negative electrode current collector and two negative electrode layers, the two negative electrode layers are respectively covered on two surfaces of the negative electrode current collector that are arranged opposite to each other in the thickness direction, and the material of each negative electrode layer includes 90% to 99% of ordinary graphite, 0 to 10% of CMC, 0 to 10% of SBR and 0 to 10% of conductive carbon black based on the mass of the negative electrode layer;

[0042] Each positive electrode sheet includes a positive electrode current collector and two positive electrode layers. The two positive electrode layers are respectively covered on two surfaces of the positive electrode current collector that are arranged opposite to each other along the thickness direction. Based on the mass of the positive electrode layer, the material of each positive electrode layer includes 90% to 98% of lithium cobalt oxide, 0 to 10% of PVDF and 0 to 10% of conductive carbon black.

[0043] In a possible implementation, the bare cell further includes a plurality of negative electrode tabs and a plurality of positive electrode tabs, each negative electrode sheet is electrically connected to at least one negative electrode tab, and each positive electrode sheet is electrically connected to at least one positive electrode tab.

[0044] In a possible implementation, a first empty foil area is provided at the end of the negative electrode current collector of at least one negative electrode sheet facing the winding center of the bare battery core, and a second empty foil area is provided at the end of the positive electrode current collector of at least one positive electrode sheet facing the winding center of the bare battery core;

[0045] At least one negative electrode tab is disposed in the first empty foil area and is electrically connected to the negative electrode current collector of the negative electrode sheet having the first empty foil area, and at least one negative electrode tab is disposed in the middle section of a portion of the negative electrode sheet;

[0046] At least one positive electrode tab is arranged in the second empty foil area and is electrically connected to the positive electrode collector of the positive electrode sheet provided with the second empty foil area. At least one positive electrode tab is arranged in the middle section of a part of the positive electrode sheet.

[0047] Since there is no negative electrode active material in the first empty foil area, when the negative electrode ear provided in the first empty foil area is directly connected to the negative electrode current collector, there is no need to sacrifice the area of ​​the negative electrode active material. There is no positive electrode active material in the second empty foil area, and the positive electrode ear provided in the second empty foil area is directly connected to the positive electrode current collector, and there is no need to sacrifice the area of ​​the positive electrode active material. Therefore, the energy density loss of the battery formed by the bare cell is less, and a higher energy density can be designed. At the same time, since the first empty foil area is provided at the end of the negative electrode sheet facing the winding center, and the second empty foil area is provided at the end of the positive electrode sheet facing the winding center, when the battery formed by the bare cell is charged, the charging current is introduced into the bare cell through the negative electrode ear electrically connected to the first empty foil area, and introduced into the bare cell through the positive electrode ear electrically connected to the second empty foil area, and the current is dispersed from the innermost side of the bare cell (i.e., the winding center) to the outer side. The path through which the charging current flows is long, the internal resistance is large, and it is not suitable for fast charging. Therefore, this winding method is suitable for application scenarios that do not require high charging rates but require less energy density loss.

[0048] In a possible implementation, a first empty foil area is provided at an end of the negative electrode current collector of at least one negative electrode sheet facing the winding center of the bare battery cell;

[0049] At least one negative electrode tab is disposed in the first empty foil area and is electrically connected to the negative electrode current collector of the negative electrode sheet having the first empty foil area, and at least one negative electrode tab is disposed in the middle section of a portion of the negative electrode sheet;

[0050] Each positive electrode ear is arranged in the middle section of the positive electrode sheet.

[0051] By providing a first empty foil area in at least one negative electrode sheet, when the negative electrode ear provided in the first empty foil area is directly connected to the negative electrode current collector, there is no need to sacrifice the area of ​​the negative electrode active material, which can reduce the energy density loss to a certain extent. At the same time, each positive electrode ear is provided in the middle section of the positive electrode sheet. When the battery formed by the bare cell is charged, when the charging current is introduced into the bare cell through the positive electrode ear, it is dispersed from the middle section to the inside of the bare cell, and from the middle section to the outside. The path through which the charging current flows will be shorter, the internal resistance is smaller, and it is suitable for fast charging. Compared with the method of simultaneously providing the first empty foil area at the end of the negative electrode sheet toward the winding center and the second empty foil area at the end of the positive electrode sheet toward the winding center, the method of providing only the first empty foil area on the negative electrode sheet can take into account the requirements of charging rate and energy density.

[0052] In a possible implementation, a second empty foil area is provided at the end of the positive electrode current collector of at least one positive electrode sheet facing the winding center of the bare battery core;

[0053] Each negative electrode ear is arranged in the middle section of the negative electrode sheet, at least one positive electrode ear is arranged in the second empty foil area and is electrically connected to the positive electrode collector of the positive electrode sheet with the second empty foil area, and at least one positive electrode ear is arranged in the middle section of part of the positive electrode sheet.

[0054] By providing a second empty foil area in at least one positive electrode sheet, when the positive electrode ear provided in the second empty foil area is directly connected to the positive electrode current collector, there is no need to sacrifice the area of ​​the positive electrode active material, which can reduce the energy density loss to a certain extent. At the same time, each negative electrode ear is provided in the middle section of the negative electrode sheet. When the battery formed by the bare cell is charged, when the charging current is introduced into the bare cell through the negative electrode ear, it is dispersed from the middle section to the inside of the bare cell, and from the middle section to the outside. The path through which the charging current flows will be shorter, the internal resistance is smaller, and it is suitable for fast charging. Compared with the method of simultaneously providing the first empty foil area at the end of the negative electrode sheet toward the winding center and the second empty foil area at the end of the positive electrode sheet toward the winding center, the method of providing only the second empty foil area on the positive electrode sheet can take into account the requirements of charging rate and energy density.

[0055] In a possible implementation, each negative electrode tab is disposed in the middle section of the negative electrode sheet, and each positive electrode tab is disposed in the middle section of the positive electrode sheet.

[0056] By setting the negative pole ears to be located in the middle section of the negative electrode sheet, and the positive pole ears to be located in the middle section of the positive electrode sheet, when the battery formed by the bare cell is charged, the charging current is introduced into the bare cell through the negative pole ear located in the middle section of the negative electrode sheet and the positive pole ear located in the middle section Q2 of the positive electrode sheet, and both are dispersed from the middle section to the inside of the bare cell, and from the middle section to the outside. The path through which the charging current flows will be the shortest, the internal resistance will be the smallest, and it is suitable for fast charging. However, being set in the middle section requires occupying the area of ​​the active material, so part needs to be sacrificed, and the energy density loss is relatively large. Compared with the method of setting the first empty foil area at the end of the negative electrode sheet facing the winding center and / or setting the second empty foil area at the end of the positive electrode sheet facing the winding center, the method of setting the negative pole ear in the middle section of the negative electrode sheet and the positive pole ear in the middle section of the positive electrode sheet is suitable for application scenarios with low requirements for energy density loss but high requirements for charging rate.

[0057] An embodiment of the present application also provides a battery, including a shell, an electrolyte and a bare cell as described above, wherein the electrolyte is filled on the inner side of the shell, and the bare cell is installed on the inner side of the shell and immersed in the electrolyte.

[0058] An embodiment of the present application further provides an electronic device, which includes the battery as described above, and the battery is used to power the electronic device. BRIEF DESCRIPTION OF THE DRAWINGS

[0059] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0060] Figure 1 A schematic diagram of the structure of a battery cell provided in an embodiment of the present application;

[0061] Figure 2 for Figure 1 A schematic diagram of the structure of a bare cell in an unfolded state in the cell shown;

[0062] Figure 3 A schematic diagram of the structure of a battery cell provided in other embodiments of the present application;

[0063] Figure 4 for Figure 2 The winding diagram of the bare battery cell shown;

[0064] Figure 5 for Figure 2 The bare cell is a schematic structural diagram of the first embodiment;

[0065] Figure 6 for Figure 2 The bare cell is a schematic structural diagram of the first mode of the second embodiment;

[0066] Figure 7 for Figure 2 The structure schematic diagram of the bare battery cell in the second mode of the second embodiment is shown;

[0067] Figure 8 for Figure 2 The structure schematic diagram of the bare battery cell in the third embodiment is shown;

[0068] Fig. 9 It is a schematic structural diagram of a bare battery cell in an unfolded state according to the fourth embodiment of the present application;

[0069] Fig.10 for Figure 2 A schematic structural diagram of a first specific example of a first winding method of a bare cell;

[0070] Fig.11 for Figure 2 A schematic structural diagram of a second specific example of the first winding method of the bare battery cell;

[0071] Fig.12 for Figure 2 A schematic structural diagram of a third specific example of the first winding method of the bare cell shown;

[0072] Fig.13 for Figure 2 A schematic structural diagram of a first specific example of a second winding method of a bare cell;

[0073] Fig.14 for Figure 2 A schematic structural diagram of a second specific example of a second winding method of a bare cell;

[0074] Fig.15 for Figure 2 A schematic structural diagram of a first specific example of a third winding method of a bare cell is shown. DETAILED DESCRIPTION

[0075] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0076] An embodiment of the present application provides an electronic device, the electronic device includes a battery, and the battery is used to power the electronic device. Exemplarily, the electronic device may be a mobile phone, a tablet, a wearable device, etc.

[0077] The battery includes a battery cell and a battery protection board. The battery protection board is electrically connected to the battery cell and is used to protect the battery cell.

[0078] See also Figure 1 , Figure 2 and Figure 3 , Figure 1 This is a schematic diagram of the structure of the battery cell 1 provided in an embodiment of the present application. Figure 2 for Figure 1 The structure diagram of the bare battery cell 1000 in the battery cell 1 is shown in the unfolded state. Figure 3 This is a schematic diagram of the structure of the battery cell 1 provided in other embodiments of the present application.

[0079] The battery cell 1 includes a shell, an electrolyte and a bare battery cell 1000. The electrolyte is filled inside the shell, and the bare battery cell 1000 is installed inside the shell and immersed in the electrolyte.

[0080] The bare cell 1000 includes a plurality of pole piece assemblies 100, a plurality of diaphragms 300 and a plurality of tab assemblies 500. In the present application, "plurality" refers to two or more. The plurality of pole piece assemblies 100 are stacked in sequence, some of the diaphragms 300 are arranged on the inner side of each pole piece assembly 100, and some of the diaphragms 300 are arranged between two adjacent pole piece assemblies 100. Each tab assembly 500 is electrically connected to a pole piece assembly 100.

[0081] Specifically, each electrode assembly 100 includes a negative electrode sheet 110 and a positive electrode sheet 130. Among them, the negative electrode sheet 110 includes a negative electrode collector 10 and a negative electrode layer covering the surface of the negative electrode collector 10. In this embodiment, the negative electrode sheet 110 includes a negative electrode collector 10, a first negative electrode layer 30 and a second negative electrode layer 50. The first negative electrode layer 30 and the second negative electrode layer 50 are respectively covered on the two side surfaces of the negative electrode collector 10 that are arranged opposite to each other in the thickness direction. Exemplarily, the first negative electrode layer 30 and the second negative electrode layer 50 are covered on the surface of the negative electrode collector 10 by double-sided coating. Exemplarily, the negative electrode collector 10 is Cu foil. The materials of the first negative electrode layer 30 and the second negative electrode layer 50 both include negative electrode active materials and negative electrode auxiliary materials. Exemplary negative electrode active materials include, but are not limited to, graphite-based negative electrodes, silicon-based negative electrodes, alloys (including binary alloys Li-M and ternary alloys Li-XM), metallic lithium negative electrodes, hard carbon-based negative electrodes, soft carbon-based negative electrodes, and lithium titanate negative electrodes (Li4Ti5O 12 ) and other materials. Among them, graphite-based negative electrodes include ordinary graphite and fast-charging graphite. The method for distinguishing ordinary graphite from fast-charging graphite is mainly through Raman spectroscopy. Ordinary graphite and fast-charging type graphite can be distinguished by the intensity ratio of the Raman D peak and G peak of graphite. Specifically, the D peak and G peak intensity ratio of ordinary graphite is 0.07-0.1; the D peak and G peak intensity ratio of 3C fast-charging graphite in fast-charging graphite is 0.2-0.3; the D peak and G peak intensity ratio of 5C fast-charging graphite in fast-charging graphite is greater than 0.3. The silicon-carbon negative electrode is a composite negative electrode in which silicon-carbon material and graphite are mixed in a certain mass ratio. Based on the mass of the silicon-carbon negative electrode, the content of silicon-carbon material is 1% to 98%, and illustratively, the content of silicon-carbon material is 5% to 10%. Among them, the silicon-carbon material can be obtained by depositing carbon on the silicon material. Negative electrode auxiliary materials include conductive agents and adhesives. Exemplarily, the conductive agent includes conductive carbon black, and the binder includes CMC (Carboxymethyl Cellulose) and SBR (Polymerized Styrene Butadiene Rubber).

[0082] The positive electrode sheet 130 includes a positive electrode collector 20 and a positive electrode layer coated on the surface of the positive electrode collector 20. In the present embodiment, the positive electrode sheet 130 includes a positive electrode collector 20, a first positive electrode layer 40 and a second positive electrode layer 60. The first positive electrode layer 40 and the second positive electrode layer 60 are respectively coated on the two side surfaces of the positive electrode collector 20 which are arranged opposite to each other in the thickness direction. Exemplarily, the first positive electrode layer 40 and the second positive electrode layer 60 are coated on the surface of the positive electrode collector 20 by double-sided coating. Exemplarily, the positive electrode collector 20 is Al foil. The first positive electrode layer 40 and the second positive electrode layer 60 both include positive electrode active materials and positive electrode auxiliary materials. Exemplarily, the positive electrode active materials include but are not limited to lithium cobalt oxide positive electrode materials, ternary five-series materials (such as lithium nickel cobalt manganese oxide LiNi 0.5 Co 0.3 Mn 0.2 O2), sodium layered transition metal oxides (Na 1-x MO2, where 0≤x<1, M is a transition metal) and sodium vanadium phosphate and the like. The positive electrode auxiliary materials include a conductive agent and a binder. Exemplarily, the conductive agent includes conductive carbon black, and the binder includes PVDF (Polyvinylidene Difluoride).

[0083] It should be noted that the ratio of each component in the negative electrode layer of the negative electrode sheet 110 and the positive electrode layer of the positive electrode sheet 130 can be adjusted according to the specific embodiment. Under normal circumstances, the ratio N / P between the capacity of the negative electrode sheet 110 and the capacity of the positive electrode sheet 130 in the bare battery cell 1000 is between 1.05 and 1.12.

[0084] A plurality of negative electrode sheets 110 and a plurality of positive electrode sheets 130 are stacked alternately, and each separator 300 is located between a negative electrode sheet 110 and a positive electrode sheet 130 , so that the separator 300 is disposed inside each electrode sheet assembly 100 and between two adjacent electrode sheet assemblies 100 .

[0085] Each pole tab assembly 500 includes at least one negative pole tab 510 and at least one positive pole tab 530. There is at least one negative pole tab 510 and at least one positive pole tab 530. The negative pole sheet 110 of a pole sheet assembly 100 is electrically connected to at least one negative pole tab 510, and the positive pole sheet 130 of a pole sheet assembly 100 is electrically connected to at least one positive pole tab 530, so as to realize the electrical connection between each pole tab assembly 500 and a pole sheet assembly 100. Exemplarily, the number of negative pole tabs 510 electrically connected to a negative pole sheet 110 is one, two, three, etc., and the number of positive pole tabs 530 electrically connected to a positive pole sheet 130 is one, two, three, etc. Exemplarily, in other embodiments, the pole tab assembly 500 includes six pole tabs. Exemplarily, the bare cell 1000 has 3 positive tabs 530 and 3 negative tabs 510 , 4 positive tabs 530 and 2 negative tabs 510 , 2 positive tabs 530 and 4 negative tabs 510 , 1 positive tab 530 and 5 negative tabs 510 , and 5 positive tabs 530 and 1 negative tab 510 .

[0086] When assembling the bare battery cell 1000, the tab assembly 500 can be electrically connected to the electrode assembly 100 first, and then the diaphragm 300, the negative electrode sheet 110 of one electrode assembly 100, the diaphragm 300, the positive electrode sheet 130 of one electrode assembly 100, the diaphragm 300, the negative electrode sheet 110 of another electrode assembly 100, the diaphragm 300, the positive electrode sheet 130 of another electrode assembly 100... are stacked in sequence, and then wound to form the bare battery cell 1000.

[0087] Compared with the existing bare battery cell that only uses one negative electrode sheet 110 and one positive electrode sheet 130, the bare battery cell 1000 provided in the embodiment of the present application, by providing multiple negative electrode sheets 110 and multiple positive electrode sheets 130, is equivalent to connecting multiple existing bare batteries in parallel. Under the premise of ensuring the same energy density, the internal resistance of the battery formed by assembling the bare batteries 1000 can be effectively reduced, thereby helping to improve the performance of the battery.

[0088] Exemplarily, in the bare cell 1000 of this embodiment, there are two pole piece assemblies 100, four separators 300, and two pole tab assemblies 500, that is, a bare cell 1000 with four pole tabs. Specifically, the two pole piece assemblies 100 respectively include a first pole piece assembly 101 and a second pole piece assembly 103, and the first pole piece assembly 101 and the second pole piece assembly 103 are stacked in sequence. Among them, the first pole piece assembly 101 includes a first negative electrode sheet 110a and a first positive electrode sheet 130a, and the second pole piece assembly 103 includes a second negative electrode sheet 110b and a second positive electrode sheet 130b. The first negative electrode sheet 110a and the second negative electrode sheet 110b both include a negative electrode collector 10, a first negative electrode layer 30 and a second negative electrode layer 50. The first positive electrode sheet 130a and the second positive electrode sheet 130b both include a positive electrode collector 20, a first positive electrode layer 40 and a second positive electrode layer 60. The four separators 300 include a first separator 310, a second separator 320, a third separator 330 and a fourth separator 340. The two tab assemblies 500 include a first tab assembly 501 and a second tab assembly 503. The first tab assembly 501 includes a first negative tab 510a and a first positive tab 530a, and the second tab assembly 503 includes a second negative tab 510b and a second positive tab 530b. Figure 1 As shown, in this embodiment, the first negative electrode tab 510a, the second negative electrode tab 510b, the first positive electrode tab 530a and the second positive electrode tab 530b are all located on the same side of the bare battery cell 1000. In other embodiments, the tabs in the tab assembly 500 are located on both sides of the bare battery cell 1000 along the height direction, such as Figure 3 As shown, the first negative electrode tab 510a and the first positive electrode tab 530a are located on one side of the bare cell 1000 along the height direction, and the second negative electrode tab 510b and the second positive electrode tab 530b are located on the other side of the bare cell 1000 along the height direction.

[0089] See also Figure 4 , Figure 4 for Figure 2 The winding diagram of the bare battery cell 1000 is shown. Figure 4 The tab assembly 500 is not shown. Figure 4 As shown, the first separator 310, the first negative electrode sheet 110a, the second separator 320, the first positive electrode sheet 130a, the third separator 330, the second negative electrode sheet 110b, the fourth separator 340 and the second positive electrode sheet 130b are wound to form a bare cell 1000 using a winding needle 700. In the wound bare cell 1000, the first positive electrode sheet 130a is arranged opposite to the first negative electrode sheet 110a, and the second positive electrode sheet 130b is arranged opposite to the second negative electrode sheet 110b.

[0090] Combined with reference Figure 5 , Figure 5 for Figure 2 The bare cell 1000 is a schematic structural diagram of the first embodiment.

[0091] In the bare cell 1000 of the first example of the first embodiment, the negative electrode layer of each negative electrode sheet 110 is the same, and the positive electrode layer of each positive electrode sheet 130 is the same. By using the negative electrode sheets 110 and the positive electrode sheets 130 of the same design, the structural design is simple, and the internal resistance of the battery assembled by the bare cells 1000 can be effectively reduced under the premise of ensuring the same energy density. Among them, "the negative electrode layers are the same" means that the type, compaction density, coating weight and proportion of negative electrode auxiliary materials in the negative electrode layers are the same. "The positive electrode layers are the same" means that the type, compaction density, coating weight and proportion of positive electrode auxiliary materials in the positive electrode layers are the same.

[0092] Exemplarily, the electrode assembly 100 includes a first electrode assembly 101 and a second electrode assembly 103. The negative electrode layer of the first negative electrode sheet 110a of the first electrode assembly 101 is the same as the negative electrode layer of the second negative electrode sheet 110b in the second electrode assembly 103, that is, the type, compaction density, coating weight and proportion of negative electrode auxiliary materials of the first negative electrode layer 30 and the second negative electrode layer 50 in the first negative electrode sheet 110a and the second negative electrode sheet 110b are the same. In this example, the first negative electrode layer 30 and the second negative electrode layer 50 coated on both sides of the negative electrode current collector 10 are the same, and both are marked with functional surface A1. The positive electrode layer of the first positive electrode sheet 130a of the first electrode sheet assembly 101 is the same as the positive electrode layer of the second positive electrode sheet 130b of the second electrode sheet assembly 103, that is, the type, compaction density, coating weight and proportion of positive electrode auxiliary materials in the first positive electrode layer 40 and the second positive electrode layer 60 in the first positive electrode sheet 130a and the second positive electrode sheet 130b are the same. In this example, the first positive electrode layer 40 and the second positive electrode layer 60 covered on both sides of the positive electrode current collector 20 are the same, and both are marked as functional surface B1.

[0093] It is understandable that in other embodiments of the bare cell 1000, the negative electrode layers of different negative electrode sheets 110 are different, and / or the positive electrode layers of different positive electrode sheets 130 are different. Among them, "different negative electrode layers" means that at least one of the type, compaction density, coating weight and proportion of negative electrode auxiliary materials in the negative electrode layer is different. "Different positive electrode layers" means that at least one of the type, compaction density, coating weight and proportion of positive electrode auxiliary materials in the positive electrode layer is different. Specific examples are given below:

[0094] Combined with reference Figure 6 and Figure 7 , Figure 6 for Figure 2 The bare cell 1000 is a schematic structural diagram of the first mode of the second embodiment. Figure 7 for Figure 2 The bare cell 1000 is a schematic structural diagram of the second mode of the second embodiment.

[0095] In the bare battery cell 1000 of the second embodiment, the negative electrode active material of the first negative electrode layer 30 in the first negative electrode sheet 110a is different from the negative electrode active material of the second negative electrode layer 50, that is, different types of negative electrode active materials are coated on both sides of the negative electrode current collector 10 in the first negative electrode sheet 110a. Since the type of negative electrode active material will affect the performance of the assembled battery, the first negative electrode layer 30 and the second negative electrode layer 50 in the first negative electrode sheet 110a are limited to use negative electrode active materials with different functions, and the first negative electrode layer 30 and the second negative electrode layer 50 in the first negative electrode sheet 110a correspond to different functional surfaces, which are marked as functional surface A1 and functional surface A2 respectively.

[0096] The negative electrode active material of the first negative electrode layer 30 in the second negative electrode sheet 110b is different from the negative electrode active material of the second negative electrode layer 50, that is, the negative electrode current collector 10 in the second negative electrode sheet 110b is covered with different types of negative electrode active materials on both sides, and the first negative electrode layer 30 and the second negative electrode layer 50 correspond to different functional surfaces. In this example, the negative electrode active material of the first negative electrode layer 30 in the second negative electrode sheet 110b is the same as the negative electrode active material of the first negative electrode layer 30 in the first negative electrode sheet 110a, that is, one side of the second negative electrode sheet 110b having the first negative electrode layer 30 and one side of the first negative electrode sheet 110a having the first negative electrode layer 30 have the same function, that is, both are functional surfaces A1. The negative electrode active material of the second negative electrode layer 50 in the second negative electrode sheet 110b is the same as the negative electrode active material of the second negative electrode layer 50 in the first negative electrode sheet 110a, that is, one side of the second negative electrode sheet 110b having the second negative electrode layer 50 has the same function as one side of the first negative electrode sheet 110a having the second negative electrode layer 50, that is, both are functional surfaces A2.

[0097] Exemplarily, taking the first negative electrode sheet 110a as an example, the negative electrode active material of the first negative electrode layer 30 in the first negative electrode sheet 110a and the second negative electrode sheet 110b is selected from negative electrode active materials with high capacity function (such as ordinary graphite), and the first negative electrode layer 30 corresponds to the high capacity surface. The negative electrode active material of the second negative electrode layer 50 is selected from negative electrode active materials with fast charging function (such as fast charging graphite), and the second negative electrode layer 50 corresponds to the fast charging surface, so as to achieve the final assembled battery with both high capacity and fast charging effects. Among them, the content of fast charging graphite in the second negative electrode layer 50 is usually lower than the content of ordinary graphite in the first negative electrode layer 30.

[0098] In this case, in order to adapt the first negative electrode sheet 110a and the second negative electrode sheet 110b having different functional surfaces, see Figure 6The first method is to adjust the first positive electrode layer 40 and the second positive electrode layer 60 in the first positive electrode sheet 130a to be different, that is, to adjust the two sides of the positive electrode collector 20 of the first positive electrode sheet 130a to be different, so as to adapt to different functional surfaces in the first negative electrode sheet 110a or the second negative electrode sheet 110b. Specifically, the first positive electrode layer 40 in the first positive electrode sheet 130a is marked as functional surface B1 to adapt to the functional surface A1 in the first negative electrode sheet 110a or the functional surface A1 in the second negative electrode sheet 110b, and the second positive electrode layer 60 in the first positive electrode sheet 130a is marked as functional surface B2 to adapt to the functional surface A2 in the first negative electrode sheet 110a or the functional surface A2 in the second negative electrode sheet 110b. Exemplarily, the positive electrode active material of the first positive electrode layer 40 in the first positive electrode sheet 130a is the same as the positive electrode active material of the second positive electrode layer 60, that is, the same positive electrode active material is used, but the content, compaction density, surface density and other parameters of the positive electrode auxiliary materials in the first positive electrode layer 40 and the second positive electrode layer 60 are adjusted to achieve the difference between the first positive electrode layer 40 and the second positive electrode layer 60.

[0099] Similarly, by adjusting the first positive electrode layer 40 and the second positive electrode layer 60 in the second positive electrode sheet 130b to be different, that is, adjusting the two sides of the positive electrode collector 20 of the second positive electrode sheet 130b to be different, to adapt to the different functional surfaces in the second negative electrode sheet 110b. Exemplarily, the positive electrode active material of the first positive electrode layer 40 in the second positive electrode sheet 130b is the same as the positive electrode active material of the second positive electrode layer 60, and is the same as the positive electrode active material of the first positive electrode layer 40 of the first positive electrode sheet 130a. Ultimately, the battery assembled from the bare cell 1000 takes into account different functions, solving the problem that the existing battery has a single function and limits the use scenarios of the battery.

[0100] See also Figure 7 The second method can be achieved by adjusting the first positive electrode layer 40 and the second positive electrode layer 60 in the first positive electrode sheet 130a to be the same, that is, adjusting the two sides of the positive electrode collector 20 of the first positive electrode sheet 130a to be the same, so as to achieve the first positive electrode sheet 130a to adapt to one functional surface of the first negative electrode sheet 110a or the second negative electrode sheet 110b. Specifically, the first positive electrode layer 40 and the second positive electrode layer 60 of the first positive electrode sheet 130a are both marked as functional surface B2, so as to adapt to the functional surface A2 of the first negative electrode sheet 110a or the functional surface A2 of the second negative electrode sheet 110b.

[0101] By adjusting the first positive electrode layer 40 and the second positive electrode layer 60 in the second positive electrode sheet 130b to be the same, and the first positive electrode layer 40 in the second positive electrode sheet 130b is different from the first positive electrode layer 40 of the first positive electrode sheet 130a, that is, adjusting the two sides of the positive electrode collector 20 of the second positive electrode sheet 130b to be the same, and different from the first positive electrode layer 40 of the first positive electrode sheet 130a, the second positive electrode sheet 130b is adapted to another functional surface in the first negative electrode sheet 110a or the second negative electrode sheet 110b. Specifically, the first positive electrode layer 40 and the second positive electrode layer 60 of the second positive electrode sheet 130b are both marked as functional surface B1, so as to adapt to the functional surface A1 of the first negative electrode sheet 110a, or to adapt to the functional surface A1 of the second negative electrode sheet 110b. Exemplarily, the positive electrode active material of the first positive electrode layer 40 of the second positive electrode sheet 130b is different from the positive electrode active material of the first positive electrode layer 40 of the first positive electrode sheet 130a, that is, by using different positive electrode active materials, the first positive electrode layer 40 of the second positive electrode sheet 130b is different from the first positive electrode layer 40 of the first positive electrode sheet 130a. Finally, the battery assembled from the bare cell 1000 takes into account different functions, solving the problem that the existing battery has a single function and limits the use scenarios of the battery.

[0102] See also Figure 8 , Figure 8 for Figure 2 The bare cell 1000 is a schematic structural diagram of the third embodiment.

[0103] In the bare cell 1000 of the third embodiment, the first negative electrode layer 30 of the first negative electrode sheet 110a is the same as the second negative electrode layer 50 of the first negative electrode sheet 110a, that is, both sides of the negative electrode collector 10 of the first negative electrode sheet 110a are the same and have the same functional surface, both marked as functional surface A1.

[0104] The first negative electrode layer 30 of the second negative electrode sheet 110b is the same as the second negative electrode layer 50 of the second negative electrode sheet 110b, and the negative electrode active material of the first negative electrode layer 30 of the second negative electrode sheet 110b is different from the negative electrode active material of the first negative electrode layer 30 of the first negative electrode sheet 110a, that is, both sides of the negative electrode collector 10 of the second negative electrode sheet 110b are the same and have the same functional surface, and have a different functional surface from the first negative electrode sheet 110a, both of which are marked as functional surface A2.

[0105] At this time, in order to adapt the first negative electrode sheet 110a and the second negative electrode sheet 110b at the same time, see Figure 8, the first positive electrode layer 40 of the first positive electrode sheet 130a is adjusted to be different from the second positive electrode layer 60 of the first positive electrode sheet 130a, that is, the two sides of the positive electrode current collector 20 of the first positive electrode sheet 130a are adjusted to be different. Specifically, the first positive electrode layer 40 of the first positive electrode sheet 130a is marked as the functional surface B1 to adapt to the functional surface A1 of the first negative electrode sheet 110a. The second positive electrode layer 60 is marked as the functional surface B2 to adapt to the functional surface B2 of the second negative electrode sheet 110b.

[0106] Similarly, the first positive electrode layer 40 of the second positive electrode sheet 130b is different from the second positive electrode layer 60 of the second positive electrode sheet 130b, that is, the two sides of the positive electrode collector 20 of the second positive electrode sheet 130b are adjusted to be different. Specifically, the first positive electrode layer 40 of the second positive electrode sheet 130b is marked as functional surface B1 to adapt to the functional surface A1 of the first negative electrode sheet 110a. The second positive electrode layer 60 is marked as functional surface B2 to adapt to the functional surface B2 of the second negative electrode sheet 110b. Ultimately, the battery assembled from the bare cell 1000 takes into account different functions, solving the problem that the existing battery has a single function and limits the use scenarios of the battery.

[0107] Combined with reference Fig. 9 , Fig. 9 It is a structural schematic diagram of the bare battery cell 1000 in the fourth embodiment of the present application in an unfolded state.

[0108] The bare cell 1000 of the fourth embodiment is different from the bare cell 1000 of the first embodiment in that at least one positive electrode sheet 130 of the bare cell 1000 of the fourth embodiment further includes a passivation layer 80 .

[0109] Specifically, the passivation layer 80 covers at least one surface of the positive electrode collector 20 of the positive electrode sheet 130 along the thickness direction, and is located between the positive electrode collector 20 and the positive electrode layer. When the passivation layer 80 is provided on the surface of the positive electrode collector 20 facing the first positive electrode layer 40, the passivation layer 80 is located between the positive electrode collector 20 and the first positive electrode layer 40. When the passivation layer 80 is provided on the surface of the positive electrode collector 20 facing the second positive electrode layer 60, the passivation layer 80 is located between the positive electrode collector 20 and the second positive electrode layer 60.

[0110] In the first example of the fourth embodiment, the passivation layer 80 is only provided on both side surfaces of the positive electrode collector 20 of the second positive electrode sheet 130b in the second electrode sheet assembly 103 along the thickness direction. At this time, the passivation layer 80 is located between the positive electrode collector 20 and the first positive electrode layer 40, and between the positive electrode collector 20 and the second positive electrode layer 60. It can be understood that in other examples, the passivation layer 80 may also be provided only on one side surface of the second positive electrode sheet 130b in the second electrode sheet assembly 103, or the passivation layer 80 may be provided on both side surfaces of the positive electrode collector 20 of the first positive electrode sheet 130a in the first electrode sheet assembly 101 and both side surfaces of the positive electrode collector 20 of the second positive electrode sheet 130b in the second electrode sheet assembly 103, or the passivation layer 80 may be provided on both side surfaces of the positive electrode collector 20 of the first positive electrode sheet 130a in the first electrode sheet assembly 101 and one side surface of the positive electrode collector 20 of the second positive electrode sheet 130b in the second electrode sheet assembly 103, or the passivation layer 80 may be provided on both side surfaces of the positive electrode collector 20 of the first positive electrode sheet 130a in the first electrode sheet assembly 101 and one side surface of the positive electrode collector 20 of the second positive electrode sheet 130b in the second electrode sheet assembly 103.

[0111] Exemplarily, the material of the passivation layer 80 may be lithium iron phosphate or aluminum oxide, and the passivation layer 80 has good thermal stability. By providing the passivation layer 80 on the surface of the positive electrode current collector 20, when the battery assembled from the bare cell 1000 is subjected to abnormal mechanical damage such as puncture, extrusion, and falling, the passivation layer 80 can protect the positive electrode current collector 20 to avoid short circuit caused by contact between the positive electrode current collector 20 and the negative electrode sheet 110, thereby avoiding the possibility of thermal runaway of the battery, thereby greatly improving the safety performance of the battery, and finally making the battery assembled from the bare cell 1000 take into account both the original function and the safety function.

[0112] It is understandable that a passivation layer 80 may also be added to the positive electrode sheet 130 of at least one electrode sheet assembly 100 in the bare battery cell 1000 of the second embodiment and the third embodiment.

[0113] The following combination Figures 10 to 15 The winding method of the bare cell 1000 is described. It should be noted that in actual production, the bare cell 1000 is wound in about 20 to 30 layers. Figures 10 to 15 Only part of the winding layers of the bare battery cell 1000 are shown. In addition, it should be noted that Figures 10 to 15 The bare cell 1000 in the figure is only a schematic diagram. Figures 10 to 15 The innermost circle of the bare cell 1000 is shown as a right angle part, but in fact it will show a certain arc during the winding process. Figures 10 to 15 No adhesive tape is shown in the bare cell 1000. In fact, adhesive tape will be placed at each pole ear position, the empty foil of the current collector, and the contact position of the negative electrode sheet.

[0114] Combined with reference Figure 1 and Fig.10 , Fig.10 for Figure 2 A schematic structural diagram of a first specific example of a first winding method of a bare cell 1000 is shown.

[0115] like Figure 1 As shown, when the bare cell 1000 is in the unfolded state, along the extension direction of the bare cell 1000, the negative electrode sheet 110 and the positive electrode sheet 130 of each electrode sheet assembly 100 include a first end Q1, a middle section Q2 and a second end Q3, and the middle section Q2 is connected between the first end Q1 and the second end Q3. Among them, the first end Q1 of the negative electrode sheet 110 and the second end Q3 of the negative electrode sheet 110 are arranged opposite to each other along the extension direction of the negative electrode sheet 110, and the first end Q1 of the positive electrode sheet 130 and the second end Q3 of the positive electrode sheet 130 are arranged opposite to each other along the extension direction of the positive electrode sheet 130.

[0116] When the bare cell 1000 is wound, the first end Q1, the middle section Q2 and the second end Q3 of the negative electrode sheet 110 are wound in sequence, and the first end Q1, the middle section Q2 and the second end Q3 of the positive electrode sheet 130 are wound in sequence. Exemplarily, the bare cell 1000 is wound with 20 to 30 layers. Fig.10 As shown, when the bare cell 1000 is in a wound state, in each electrode assembly 100 , the first end Q1 of the negative electrode sheet 110 and the first end Q1 of the positive electrode sheet 130 are both oriented along the winding center.

[0117] In the first winding mode of the bare cell 1000, a first empty foil area 91 is provided at a first end Q1 of the negative electrode collector 10 of at least one negative electrode sheet 110 toward the winding center of the bare cell 1000, and a second empty foil area 92 is provided at a first end Q1 of the positive electrode collector 20 of at least one positive electrode sheet 130 toward the winding center of the bare cell 1000;

[0118] At least one negative electrode tab 510 is disposed in the first empty foil area 91 and is electrically connected to the negative electrode current collector 10 of the negative electrode sheet 110 provided with the first empty foil area 91. At least one negative electrode tab 510 is disposed in the middle section Q2 of a portion of the negative electrode sheet 110.

[0119] At least one positive electrode tab 530 is disposed in the second empty foil area 92 and is electrically connected to the positive electrode current collector 20 of the positive electrode sheet 130 . At least one positive electrode tab 530 is disposed in the middle section Q2 of a portion of the positive electrode sheet 130 .

[0120] In the first specific example of the first winding method, the bare cell 1000 includes a first electrode sheet assembly 101 and a second electrode sheet assembly 103. The first negative electrode sheet 110a of the first electrode sheet assembly 101 is provided with a first empty foil area 91 at the first end Q1 facing the winding center, and the first positive electrode sheet 130a is provided with a second empty foil area 92 at the first end Q1 facing the winding center. The first negative electrode ear 510a of the first electrode ear assembly 501 is provided in the first empty foil area 91 and is electrically connected to the negative electrode collector 10 of the first negative electrode sheet 110a. The first positive electrode ear 530a of the first electrode ear assembly 501 is provided in the second empty foil area 92 and is electrically connected to the positive electrode collector 20 of the first positive electrode sheet 130a. Among them, the first empty foil area 91 and the second empty foil area 92 are located on both sides of the symmetry axis in the length direction of the bare cell 1000. The second negative electrode tab 510b of the second electrode tab assembly 503 is disposed at the middle section Q2 of the second negative electrode sheet 110b, and the second positive electrode tab 530b of the second electrode tab assembly 503 is disposed at the middle section Q2 of the second positive electrode sheet 130b.

[0121] In the first winding method, since there is no negative electrode active material in the first empty foil area 91, when the negative electrode ear 510 provided in the first empty foil area 91 is directly connected to the negative electrode collector 10, there is no need to sacrifice the area of ​​the negative electrode active material. There is no positive electrode active material in the second empty foil area 92, and the positive electrode ear 530 provided in the second empty foil area 92 is directly connected to the positive electrode collector 20, and there is no need to sacrifice the area of ​​the positive electrode active material. Therefore, the energy density loss of the battery formed by the bare battery cell 1000 is less, and a higher energy density can be designed. At the same time, since the first empty foil area 91 is provided at the end of the negative electrode sheet 110 toward the winding center, and the second empty foil area 92 is provided at the end of the positive electrode sheet 130 toward the winding center, when the battery formed by the bare cell 1000 is charged, the charging current is introduced into the bare cell 1000 through the negative electrode ear 510 electrically connected to the first empty foil area 91, and introduced into the bare cell 1000 through the positive electrode ear 530 electrically connected to the second empty foil area 92, and the current is dispersed from the innermost side (i.e., the winding center) of the bare cell 1000 to the outside. The path through which the charging current flows is long, the internal resistance is large, and it is not suitable for fast charging. Therefore, the first winding method is suitable for application scenarios that do not require high charging rates but require less energy density loss.

[0122] Combined with reference Figure 1 and Fig.11 , Fig.11 for Figure 2 A schematic structural diagram of a second specific example of the first winding method of the bare cell 1000 is shown.

[0123] The second specific example of the first winding method is different from the first specific example of the first winding method in that, in the second specific example, the first empty foil area 91 and the second empty foil area 92 are located on the same side of the axis of symmetry in the length direction of the bare battery cell 1000, and the first end Q1 of the second negative electrode sheet 110b is located on the side of the first end Q1 of the first positive electrode sheet 130a that is away from the first end Q1 of the first negative electrode sheet 110a.

[0124] Specifically, compared with the first specific example, since the first empty foil area 91 and the second empty foil area 92 in the second specific example are located on the same side of the symmetry axis in the length direction of the bare cell 1000, the first positive electrode sheet 130a can be provided with more positive electrode active materials. In addition, the first end Q1 of the second negative electrode sheet 110b is located on the side of the first end Q1 of the first positive electrode sheet 130a away from the first end Q1 of the first negative electrode sheet 110a, and the second negative electrode sheet 110b can be wrapped for half a circle more, thereby providing more negative electrode active materials, thereby making the energy density of the battery formed by the bare cell 1000 higher.

[0125] Combined with reference Figure 1 and Fig.12 , Fig.12 for Figure 2 A schematic structural diagram of a third specific example of the first winding method of the bare cell 1000 is shown.

[0126] The third specific example of the second winding method is different from the second specific example in that, in the third specific example, a third empty foil area 93 is provided at the second end Q3 of the positive electrode collector 20 of the second positive electrode sheet 130b away from the winding center of the bare battery cell 1000, and the third empty foil area 93 partially covers the middle section Q2 of the second positive electrode sheet 130b.

[0127] By setting a third empty foil area 93 on the outermost second positive electrode sheet 130b of the bare battery cell 1000, and using the third empty foil area 93 to wrap the middle section Q2 of the second positive electrode sheet 130b, the middle section Q2 of the second positive electrode sheet 130b can be protected, thereby facilitating improving the safety performance of the bare battery cell 1000.

[0128] Combined with reference Figure 1 and Fig.13 , Fig.13 for Figure 2 A schematic structural diagram of a first specific example of a second winding method of a bare cell 1000 is shown.

[0129] In the second winding method of the bare battery cell 1000, the negative electrode collector 10 of at least one negative electrode sheet 110 is provided with a first empty foil area 91 at the first end Q1 facing the winding center of the bare battery cell 1000; at least one negative electrode ear 510 is provided in the first empty foil area 91 and is electrically connected to the negative electrode collector 10 of the negative electrode sheet 110 provided with the first empty foil area 91, and at least one negative electrode ear 510 is provided in the middle section Q2 of a portion of the negative electrode sheet 110; each positive electrode ear 530 is provided in the middle section Q2 of the positive electrode sheet 130.

[0130] In the first specific example of the second winding method, the bare cell 1000 includes a first electrode sheet assembly 101 and a second electrode sheet assembly 103, and a first empty foil area 91 is provided at the first end Q1 of the first negative electrode sheet 110a of the first electrode sheet assembly 101 toward the winding center. The first negative electrode ear 510a of the first electrode tab assembly 501 is provided in the first empty foil area 91 and is electrically connected to the negative electrode current collector 10 of the first negative electrode sheet 110a, and the first positive electrode ear 530a of the first electrode tab assembly 501 is provided in the middle section Q2 of the first positive electrode sheet 130a. The second negative electrode ear 510b of the second electrode tab assembly 503 is provided in the middle section Q2 of the second negative electrode sheet 110b, and the second positive electrode ear 530b of the second electrode tab assembly 503 is provided in the middle section Q2 of the second positive electrode sheet 130b.

[0131] Compared with the first winding method, in the second winding method, only part of the negative electrode sheet 110 is provided with the first empty foil area 91. When the negative electrode ear 510 provided in the first empty foil area 91 is directly connected to the negative electrode current collector 10, there is no need to sacrifice the area of ​​the negative electrode active material, which can reduce the energy density loss to a certain extent. At the same time, each positive electrode ear 530 is provided in the middle section Q2 of the positive electrode sheet 130. When the battery formed by the bare battery cell 1000 is charged, the charging current is introduced into the bare battery cell 1000 through the positive electrode ear 530. It is dispersed from the middle section Q2 to the inside of the bare battery cell 1000 (ie, to the first end Q1), and from the middle section Q2 to the outside (ie, to the second end Q3). The path through which the charging current flows will be shorter and the internal resistance will be smaller. Compared with the first winding method, it is suitable for fast charging. Therefore, the second winding method can take into account the requirements of charging rate and energy density.

[0132] It can be understood that, based on the same mechanism, in other winding methods, a second empty foil area 92 can be provided at the first end Q1 of the positive electrode collector 20 of at least one positive electrode sheet 130 facing the winding center of the bare battery cell 1000; each negative electrode ear 510 is provided in the middle section Q2 of the negative electrode sheet 110, at least one positive electrode ear 530 is provided in the second empty foil area 92, and is electrically connected to the positive electrode collector 20 of the positive electrode sheet 130 provided with the second empty foil area 92, and at least one positive electrode ear 530 is provided in the middle section Q2 of a portion of the positive electrode sheet 130.

[0133] Exemplarily, the bare cell 1000 includes a first electrode sheet assembly 101 and a second electrode sheet assembly 103, and the first positive electrode sheet 130a of the first electrode sheet assembly 101 is provided with a second empty foil area 92 at the first end Q1 facing the winding center. The first negative electrode ear 510a of the first electrode tab assembly 501 is provided in the middle section Q2 of the first negative electrode sheet 110a, and the first positive electrode ear 530a of the first electrode tab assembly 501 is provided in the second empty foil area 92 and is electrically connected to the positive electrode collector 20 of the first positive electrode sheet 130a. The second negative electrode ear 510b of the second electrode tab assembly 503 is provided in the middle section Q2 of the second negative electrode sheet 110b, and the second positive electrode ear 530b of the second electrode tab assembly 503 is provided in the middle section Q2 of the second positive electrode sheet 130b. At this time, each negative electrode ear 510 is arranged in the middle section Q2 of the negative electrode sheet 110. When the battery formed by the bare cell 1000 is charged, the charging current is introduced into the bare cell 1000 through the negative electrode ear 510. The charging current is dispersed from the middle section Q2 to the inside of the bare cell 1000 (that is, to the first end Q1), and from the middle section Q2 to the outside (that is, to the second end Q3). The path through which the charging current flows will be shorter and the internal resistance will be smaller, which is suitable for fast charging.

[0134] Combined with reference Figure 1 and Fig.14 , Fig.14 for Figure 2 A schematic structural diagram of a second specific example of a second winding method of the bare cell 1000 is shown.

[0135] The second specific example of the second winding method is different from the first specific example of the second winding method in that, in the second specific example of the second winding method, the first end Q1 of the first negative electrode sheet 110a, the first end Q1 of the first positive electrode sheet 130a, and the first end Q1 of the second negative electrode sheet 110b are located on the same side of the axis of symmetry in the length direction of the bare battery cell 1000.

[0136] Specifically, compared with the first specific example of the second winding method, in the second specific example of the second winding method, the first positive electrode sheet 130a and the second negative electrode sheet 110b can be wrapped half a circle more, thereby providing more active materials, which is beneficial to improve the energy density of the battery formed by the bare cell 1000.

[0137] Combined with reference Figure 1 and Fig.15 , Fig.15 for Figure 2 A schematic structural diagram of a first specific example of a third winding method of a bare cell 1000 is shown.

[0138] In the bare cell 1000 of the third winding method, each negative electrode tab 510 is disposed in the middle section Q2 of the negative electrode sheet 110 , and each positive electrode tab 530 is disposed in the middle section Q2 of the positive electrode sheet 130 .

[0139] Specifically, in the first specific example of the third winding method, the bare cell 1000 includes a first pole piece assembly 101 and a second pole piece assembly 103, the first negative pole ear 510a of the first pole ear assembly 501 is arranged in the middle section Q2 of the first negative pole piece 110a, and the first positive pole ear 530a of the first pole ear assembly 501 is arranged in the middle section Q2 of the first positive pole piece 130a. The second negative pole ear 510b of the second pole ear assembly 503 is arranged in the middle section Q2 of the second negative pole piece 110b, and the second positive pole ear 530b of the second pole ear assembly 503 is arranged in the middle section Q2 of the second positive pole piece 130b.

[0140] Compared with the first winding method and the second winding method, in the third winding method, the negative electrode ear 510 is located in the middle section Q2 of the negative electrode sheet 110, and the positive electrode ear 530 is located in the middle section Q2 of the positive electrode sheet 130. When the battery formed by the bare cell 1000 is charged, the charging current is introduced into the bare cell 1000 through the negative electrode ear 510 located in the middle section Q2 of the negative electrode sheet 110 and the positive electrode ear 530 located in the middle section Q2 of the positive electrode sheet 130, and is dispersed from the middle section Q2 to the inside of the bare cell 1000 (ie, to the first end Q1), and from the middle section Q2 to the outside (ie, to the second end Q3). The path through which the charging current flows will be the shortest, the internal resistance will be the smallest, and it is suitable for fast charging. However, being set in the middle section Q2 requires occupying the area of ​​the active material, so a part needs to be sacrificed, and the energy density loss is relatively large. Therefore, the third winding method is suitable for application scenarios with low requirements for energy density loss but high requirements for charging rate.

[0141] The bare battery cell 1000 provided in the present application is described in detail below in conjunction with specific embodiments.

[0142] Embodiment 1: Specific example of the first embodiment (same pole piece design)

[0143] Embodiment 1 provides a battery, which is prepared according to the following steps:

[0144] (1) The first negative electrode sheet 110a and the second negative electrode sheet 110b have the same design: the negative electrode current collector 10 is Cu foil, the negative electrode active material uses conventional 3C graphite, and the negative electrode slurry ratio of the first negative electrode layer 30 and the second negative electrode layer 50 is negative electrode active material: CMC: SBR: conductive carbon black = 97%: 1.2%: 1.3%: 0.5%, and the surface density is 8 mg / cm 2 , compacted density is 1.6g / cm 3 .

[0145] (2) The first positive electrode sheet 130a and the second positive electrode sheet 130b have the same design: the positive electrode current collector 20 is Al foil, the positive electrode active material uses 4.5V voltage system lithium cobalt oxide, and the positive electrode slurry ratio of the first positive electrode layer 40 and the second positive electrode layer 60 is positive electrode active material: PVDF: conductive carbon black = 97.6%: 1.2%: 1.2%, and the surface density is 14 mg / cm 2 , the compacted density is 4.15g / cm 3 .

[0146] (3) The negative electrode slurry is coated on the surface of the negative electrode collector 10, and the positive electrode slurry is coated on the surface of the positive electrode collector 20. After coating, the first negative electrode sheet 110a, the second negative electrode sheet 110b, the first positive electrode sheet 130a and the second positive electrode sheet 130b are obtained by drying and cold pressing.

[0147] (4) The first positive electrode sheet 130a is arranged opposite to the first negative electrode sheet 110a, and the second positive electrode sheet 130b is arranged opposite to the second negative electrode sheet 110b, and the positive electrode sheet and the negative electrode sheet are separated by the separator 300. The bare battery cell 1000 is obtained by winding, and then packaged, injected with electrolyte, formed, and finally sealed to obtain the final battery cell, which is connected to the battery protection board for connection and packaging to form a complete battery.

[0148] Comparative Example 1 provides a battery, which, compared with the battery of Example 1, only includes a first positive electrode sheet 130a and a first negative electrode sheet 110a. The battery of Example 1 and the battery of Comparative Example 1 are compared. The battery of Comparative Example 1 contains only one set of electrode sheet assemblies, and the internal resistance is 28mΩ, while the battery of Example 1 contains two sets of electrode sheet assemblies, and the internal resistance of the battery is reduced from 28mΩ to 14mΩ. The experimental results show that, under the premise of maintaining the same battery energy density, by arranging multiple sets of electrode sheet assemblies in the battery, the internal resistance of the battery can be effectively reduced.

[0149] Embodiment 2: Specific example of the first method in the second embodiment (a battery with high capacity and fast charging)

[0150] Embodiment 2 provides a battery, wherein the fast-charging graphite is 5C fast-charging graphite, which is prepared according to the following steps:

[0151] (1) The first negative electrode sheet 110a has different functional surfaces on both sides: the negative electrode current collector 10 is Cu foil, the first negative electrode layer 30 corresponds to the high capacity surface, and the negative electrode slurry ratio of the first negative electrode layer 30 is ordinary graphite: CMC: SBR: conductive carbon black = 97.7%: 0.9%: 0.9%: 0.5%, and the surface density is 8 mg / cm 2 , compacted density is 1.73g / cm 3The second negative electrode layer 50 corresponds to the fast charging surface. The negative electrode slurry ratio of the second negative electrode layer 50 is fast charging graphite: CMC: SBR: conductive carbon black = 97%: 1%: 1%: 1%, and the surface density is 7 mg / cm 2 , compacted density is 1.65g / cm 3 .

[0152] The second negative electrode sheet 110b has different functional surfaces on both sides: the negative electrode current collector 10 is Cu foil, the first negative electrode layer 30 corresponds to the high capacity surface, and the negative electrode slurry ratio of the first negative electrode layer 30 is ordinary graphite: CMC: SBR: conductive carbon black = 97.5%: 1%: 1%: 0.5%, and the surface density is 7.9 mg / cm 2 , compacted density is 1.73g / cm 3 The second negative electrode layer 50 corresponds to the fast charging surface. The negative electrode slurry ratio of the second negative electrode layer 50 is fast charging graphite: CMC: SBR: conductive carbon black = 96.8%: 1.1%: 1.1%: 1%, and the surface density is 7 mg / cm 2 , compacted density is 1.65g / cm 3 .

[0153] (2) The first positive electrode sheet 130a is adapted to the different functional surfaces of the negative electrode sheet on both sides: the positive electrode current collector 20 is Al foil, the positive electrode active materials in the first positive electrode layer 40 and the second positive electrode layer 60 are both made of 4.5V voltage system lithium cobalt oxide, the first positive electrode layer 40 is adapted to the high capacity surface, and the positive electrode slurry ratio of the first positive electrode layer 40 is positive electrode active material: PVDF: conductive carbon black = 97.6%: 1.2%: 1.2%, and the surface density is 14 mg / cm 2 , compacted density is 4.20g / cm 3 The second positive electrode layer 60 is adapted to the fast charging surface. The positive electrode slurry ratio of the second positive electrode layer 60 is positive electrode active material: PVDF: conductive carbon black = 96.7%: 1.5%: 1.8%, and the surface density is 11 mg / cm 2 , compacted density is 4.15g / cm 3 .

[0154] The second positive electrode sheet 130b is adapted to the different functional surfaces of the negative electrode sheet on both sides: the positive electrode current collector 20 is Al foil, the positive electrode active materials in the first positive electrode layer 40 and the second positive electrode layer 60 are both made of 4.5V voltage system lithium cobalt oxide, the first positive electrode layer 40 is adapted to the high capacity surface, and the positive electrode slurry ratio of the first positive electrode layer 40 is positive electrode active material: PVDF: conductive carbon black = 97.8%: 1.1%: 1.1%, and the surface density is 14.2mg / cm 2 , compacted density is 4.20g / cm 3The second positive electrode layer 60 is adapted to the fast charging surface. The positive electrode slurry ratio of the second positive electrode layer 60 is positive electrode active material: PVDF: conductive carbon black = 96%: 2%: 2%, and the surface density is 11 mg / cm 2 , compacted density is 4.15g / cm 3 .

[0155] (3) The negative electrode slurry is coated on the surface of the negative electrode collector 10, and the positive electrode slurry is coated on the surface of the positive electrode collector 20. After coating, the first negative electrode sheet 110a, the second negative electrode sheet 110b, the first positive electrode sheet 130a and the second positive electrode sheet 130b are obtained by drying and cold pressing.

[0156] The first positive electrode sheet 130a is arranged opposite to the first negative electrode sheet 110a, and the second positive electrode sheet 130b is arranged opposite to the second negative electrode sheet 110b, and the positive electrode sheet and the negative electrode sheet are separated by the diaphragm 300. Among them, the positive electrode layer adapted to the high-capacity surface of the positive electrode sheet corresponds to the high-capacity surface of the negative electrode sheet, and the positive electrode layer adapted to the fast-charging surface of the positive electrode sheet corresponds to the fast-charging surface of the negative electrode sheet. The bare battery cell 1000 is obtained by winding, and then packaged, injected with electrolyte, formed, and finally sealed to obtain the final battery cell, which is connected to the battery protection board for connection and packaging to form a complete battery.

[0157] The battery of Example 2 was tested. The battery of Example 2 achieved a higher energy density (>750Wh / L) while taking into account the fast charging capability (>3C charging rate).

[0158] Embodiment 3: Specific example of the first method in the second embodiment (battery with high capacity and low cycle expansion rate)

[0159] Embodiment 3 provides a battery, which is prepared according to the following steps:

[0160] (1) The first negative electrode sheet 110a has different functional surfaces on both sides: the negative electrode current collector 10 is Cu foil, the first negative electrode layer 30 corresponds to the silicon-carbon surface, and the negative electrode slurry ratio of the first negative electrode layer 30 is silicon-carbon negative electrode material: CMC: SBR: conductive carbon black = 96.6%: 1%: 1.2%: 1.2%, and the surface density is 6 mg / cm 2 , compacted density is 1.6g / cm 3 In this embodiment, the silicon-carbon negative electrode is made of a mixture of silicon-carbon material and graphite. In the silicon-carbon negative electrode, the content of silicon-carbon material is 5% to 10%. The second negative electrode layer 50 corresponds to the graphite surface, and the negative electrode slurry ratio of the second negative electrode layer 50 is ordinary graphite: CMC: SBR: conductive carbon black = 97.6%: 0.8%: 0.8%: 0.8%, and the surface density is 7.3 mg / cm 2 , compacted density is 1.73g / cm 3 .

[0161] The second negative electrode sheet 110 b is coated on both sides, and the coating design is the same as that of the first negative electrode sheet 110 a .

[0162] (2) The first positive electrode sheet 130a is adapted to different functional surfaces of the negative electrode sheet on both sides: the positive electrode current collector 20 is Al foil, the positive electrode active materials in the first positive electrode layer 40 and the second positive electrode layer 60 are both lithium cobalt oxide of 4.55V voltage system, the first positive electrode layer 40 is adapted to the silicon carbon surface, and the positive electrode slurry ratio of the first positive electrode layer 40 is positive electrode active material: PVDF: conductive carbon black = 97.8%: 1.1%: 1.1%, and the surface density is 14.3 mg / cm 2 , compacted density is 4.20g / cm 3 The second positive electrode layer 60 is adapted to the graphite surface. The positive electrode slurry ratio of the second positive electrode layer 60 is positive electrode active material: PVDF: conductive carbon black = 97.2%: 1.4%: 1.4%, and the surface density is 13 mg / cm 2 , compacted density is 4.20g / cm 3 .

[0163] The second positive electrode sheet 130b is adapted to the different functional surfaces of the negative electrode sheet on both sides: the positive electrode current collector 20 is Al foil, the positive electrode active materials in the first positive electrode layer 40 and the second positive electrode layer 60 are both lithium cobalt oxide of 4.55V voltage system, the first positive electrode layer 40 is adapted to the silicon carbon surface, and the positive electrode slurry ratio of the first positive electrode layer 40 is positive electrode active material: PVDF: conductive carbon black = 97.8%: 1.1%: 1.1%, and the surface density is 14.3mg / cm 2 , compacted density is 4.20g / cm 3 The second positive electrode layer 60 is adapted to the graphite surface. The positive electrode slurry ratio of the second positive electrode layer 60 is positive electrode active material: PVDF: conductive carbon black = 97.2%: 1.4%: 1.4%, and the surface density is 13 mg / cm 2 , compacted density is 4.20g / cm 3 .

[0164] (3) The negative electrode slurry is coated on the surface of the negative electrode collector 10, and the positive electrode slurry is coated on the surface of the positive electrode collector 20. After coating, the first negative electrode sheet 110a, the second negative electrode sheet 110b, the first positive electrode sheet 130a and the second positive electrode sheet 130b are obtained by drying and cold pressing.

[0165] (4) The first positive electrode sheet 130a is arranged opposite to the first negative electrode sheet 110a, and the second positive electrode sheet 130b is arranged opposite to the second negative electrode sheet 110b, and the positive electrode sheet and the negative electrode sheet are separated by the diaphragm 300. Among them, the positive electrode layer adapted to the silicon-carbon surface in the positive electrode sheet corresponds to the silicon-carbon surface of the negative electrode sheet, and the positive electrode layer adapted to the graphite surface in the positive electrode sheet corresponds to the graphite surface of the negative electrode sheet. The bare battery cell 1000 is obtained by winding, and then packaged, injected with electrolyte, formed, and finally sealed to obtain the final battery cell, which is connected to the battery protection board for connection and packaging to form a complete battery.

[0166] The battery of Example 3 was tested. The battery of Example 3 had a relatively high energy density (>780Wh / L) and a relatively low cycle thickness expansion rate (<10%).

[0167] Embodiment 4: Specific example of the second method in the second embodiment (lithium cobalt oxide and ternary hybrid battery)

[0168] Embodiment 4 provides a battery, which is prepared according to the following steps:

[0169] (1) The first negative electrode sheet 110a has different functional surfaces on both sides: the negative electrode current collector 10 is Cu foil, the first negative electrode layer 30 corresponds to the graphite negative electrode surface, and the negative electrode slurry ratio is ordinary graphite: CMC: SBR: conductive carbon black = 97.6%: 0.8%: 0.8%: 0.8%, and the surface density is 7.3 mg / cm 2 , compacted density is 1.73g / cm 3 The second negative electrode layer 50 corresponds to the silicon-carbon negative electrode surface, and the negative electrode slurry ratio is silicon-carbon negative electrode: CMC: SBR: conductive carbon black = 94.6%: 1%: 1.2%: 3.2%, and the surface density is 6 mg / cm 2 , compacted density is 1.6g / cm 3 .

[0170] The second negative electrode sheet 110b has different functional surfaces on both sides: the negative electrode current collector 10 is Cu foil, the first negative electrode layer 30 corresponds to the graphite negative electrode surface, and the negative electrode slurry ratio is ordinary graphite: CMC: SBR: conductive carbon black = 97.6%: 0.8%: 0.8%: 0.8%, and the surface density is 7.3 mg / cm 2 , compacted density is 1.73g / cm 3 The second negative electrode layer 50 corresponds to the silicon-carbon negative electrode surface, and the negative electrode slurry ratio is silicon-carbon negative electrode: CMC: SBR: conductive carbon black = 94.6%: 1%: 1.2%: 3.2%, and the surface density is 6 mg / cm 2 , compacted density is 1.6g / cm 3 .

[0171] (2) The first positive electrode sheet 130a is adapted to the negative electrode sheet with a graphite negative electrode surface: the positive electrode current collector 20 is Al foil, the first positive electrode layer 40 and the second positive electrode layer 60 are designed the same, the positive electrode active material uses a 4.5V voltage system lithium cobalt oxide positive electrode material, and the positive electrode slurry ratio is positive electrode active material: PVDF: conductive carbon black = 97.2%: 1.4%: 1.4%, and the surface density is 13 mg / cm 2 , compacted density is 4.20g / cm 3 .

[0172] The second positive electrode sheet 130b is adapted to the negative electrode sheet with a silicon-carbon negative electrode surface: the positive electrode current collector 20 is Al foil, the first positive electrode layer 40 and the second positive electrode layer 60 are designed the same, and the positive electrode active material is 4.4V ternary five-series material LiNi 0.5 Co 0.3 Mn 0.2 O2, the positive electrode slurry ratio is positive electrode active material: PVDF: conductive carbon black = 95.8%: 2.1%: 2.1%, the surface density is 13.3mg / cm 2 , compacted density is 3.7g / cm 3 .

[0173] (3) The negative electrode slurry is coated on the surface of the negative electrode collector 10, and the positive electrode slurry is coated on the surface of the positive electrode collector 20. After coating, the first negative electrode sheet 110a, the second negative electrode sheet 110b, the first positive electrode sheet 130a and the second positive electrode sheet 130b are obtained by drying and cold pressing.

[0174] (4) The first positive electrode sheet 130a is arranged opposite to the first negative electrode sheet 110a, and the second positive electrode sheet 130b is arranged opposite to the second negative electrode sheet 110b, and the positive electrode sheet and the negative electrode sheet are separated by the separator 300. The bare battery cell 1000 is obtained by winding, and then packaged, injected with electrolyte, formed, and finally sealed to obtain the final battery cell, which is connected to the battery protection board for connection and packaging to form a complete battery.

[0175] In the battery of this embodiment, the gram capacity of the positive electrode active material used in the first positive electrode sheet 130a and the positive electrode active material used in the second positive electrode sheet 130b is not much different, but the 4.4V ternary five-series material LiNi 0.5 Co 0.3 Mn 0.2 The cost of O2 is relatively low, and the battery of Example 4 can reduce the battery cost without sacrificing energy density.

[0176] Embodiment 5: Specific example of the fourth embodiment (battery with high capacity and safety performance)

[0177] Embodiment 5 provides a battery, which is prepared according to the following steps:

[0178] (1) The first negative electrode sheet 110a has the same design on both sides: the negative electrode current collector 10 is Cu foil, the first negative electrode layer 30 and the second negative electrode layer 50 have the same design, and the negative electrode slurry ratio is ordinary graphite: CMC: SBR: conductive carbon black = 97.7%: 0.9%: 0.9%: 0.5%, and the surface density is 8 mg / cm 2 , compacted density is 1.73g / cm 3 .

[0179] The second negative electrode sheet 110 b is the same as the first negative electrode sheet 110 a .

[0180] (2) The first positive electrode sheet 130a has the same design on both sides: the positive electrode current collector 20 is Al foil, the first positive electrode layer 40 and the second positive electrode layer 60 have the same design, the positive electrode active material uses 4.5V voltage system lithium cobalt oxide positive electrode material, and the positive electrode slurry ratio is positive electrode active material: PVDF: conductive carbon black = 97.6%: 1.2%: 1.2%, and the surface density is 14 mg / cm 2 , compacted density is 4.20g / cm 3 .

[0181] The second positive electrode sheet 130b also includes a passivation layer 80, which is coated on both sides of the positive electrode current collector 20: the positive electrode current collector 20 is Al foil, the passivation layer 80 is a lithium iron phosphate layer, the first positive electrode layer 40 and the second positive electrode layer 60 are both coated on the surface of the passivation layer 80 away from the positive electrode current collector 20, and have the same design, the positive electrode active material uses a 4.5V voltage system lithium cobalt oxide positive electrode material, and the positive electrode slurry ratio is positive electrode active material: PVDF: conductive carbon black = 97%: 1.5%: 1.5%, and the surface density is 13.5mg / cm 2 , compacted density is 4.15g / cm 3 .

[0182] (3) The negative electrode slurry is coated on the surface of the negative electrode collector 10, and the positive electrode slurry is coated on the surface of the positive electrode collector 20. After coating, the first negative electrode sheet 110a, the second negative electrode sheet 110b, the first positive electrode sheet 130a and the second positive electrode sheet 130b are obtained by drying and cold pressing.

[0183] (4) The first positive electrode sheet 130a is arranged opposite to the first negative electrode sheet 110a, and the second positive electrode sheet 130b is arranged opposite to the second negative electrode sheet 110b, and the positive electrode sheet and the negative electrode sheet are separated by the separator 300. The bare battery cell 1000 is obtained by winding, and then packaged, injected with electrolyte, formed, and finally sealed to obtain the final battery cell, which is connected to the battery protection board for connection and packaging to form a complete battery.

[0184] The battery of Example 5 was subjected to a needle puncture test. Compared with ordinary batteries, the battery of Example 5 can pass the needle puncture test with 100% power. The experimental results show that, under the premise of having a high capacity, the safety of the battery can be improved by providing a passivation layer 80 on the surface of the positive electrode current collector 20.

[0185] What is disclosed above is only a preferred embodiment of the present application, and it certainly cannot be used to limit the scope of rights of the present application. Ordinary technicians in this field can understand that all or part of the processes of implementing the above embodiments and equivalent changes made according to the claims of the present application are still within the scope covered by the present application.

Claims

1. A bare battery cell, characterized in that: The bare battery cell is in a wound state, and includes a plurality of negative electrode sheets, a plurality of positive electrode sheets and a plurality of separators. The plurality of negative electrode sheets and the plurality of positive electrode sheets are stacked alternately, and each separator is located between one positive electrode sheet and one negative electrode sheet.

2. The bare battery cell according to claim 1, characterized in that: The negative electrode layers of different negative electrode sheets are different, and / or the positive electrode layers of different positive electrode sheets are different.

3. The bare battery cell according to claim 2, characterized in that: The plurality of negative electrode sheets include a first negative electrode sheet and a second negative electrode sheet, each of the first negative electrode sheet and the second negative electrode sheet includes a negative electrode current collector, a first negative electrode layer and a second negative electrode layer, and the first negative electrode layer and the second negative electrode layer are respectively covered on both side surfaces of the negative electrode current collector along the thickness direction; The plurality of positive electrode sheets include a first positive electrode sheet and a second positive electrode sheet, each of the first positive electrode sheet and the second positive electrode sheet includes a positive electrode current collector, a first positive electrode layer and a second positive electrode layer, and the first positive electrode layer and the second positive electrode layer are respectively covered on both side surfaces of the positive electrode current collector along the thickness direction; The first positive electrode sheet is arranged opposite to the first negative electrode sheet, and the second positive electrode sheet is arranged opposite to the second negative electrode sheet.

4. The bare battery cell according to claim 3, characterized in that: The negative electrode active material of the first negative electrode layer in the first negative electrode sheet is different from the negative electrode active material of the second negative electrode layer; The negative electrode active material of the first negative electrode layer in the second negative electrode sheet is different from the negative electrode active material of the second negative electrode layer, the negative electrode active material of the first negative electrode layer in the second negative electrode sheet is the same as the negative electrode active material of the first negative electrode layer in the first negative electrode sheet, and the negative electrode active material of the second negative electrode layer in the second negative electrode sheet is the same as the negative electrode active material of the second negative electrode layer in the first negative electrode sheet; The first positive electrode layer in the first positive electrode sheet is different from the second positive electrode layer, and the first positive electrode layer in the second positive electrode sheet is different from the second positive electrode layer.

5. The bare battery cell according to claim 4, characterized in that: The positive electrode active material of the first positive electrode layer in the first positive electrode sheet is the same as the positive electrode active material of the second positive electrode layer, the positive electrode active material of the first positive electrode layer in the second positive electrode sheet is the same as the positive electrode active material of the second positive electrode layer, and is the same as the positive electrode active material of the first positive electrode layer of the first positive electrode sheet.

6. The bare battery cell according to claim 5, characterized in that: Based on the mass of the first negative electrode layer of the first negative electrode sheet, the material of the first negative electrode layer of the first negative electrode sheet includes 90% to 99% of ordinary graphite, 0 to 10% of CMC, 0 to 10% of SBR and 0 to 10% of conductive carbon black; based on the mass of the second negative electrode layer of the first negative electrode sheet, the material of the second negative electrode layer of the first negative electrode sheet includes 90% to 98% of fast-filling graphite, 0 to 10% of CMC, 0 to 10% of SBR and 0 to 10% of conductive carbon black; Based on the mass of the first negative electrode layer of the second negative electrode sheet, the material of the first negative electrode layer of the second negative electrode sheet includes 90% to 99% of ordinary graphite, 0 to 10% of CMC, 0 to 10% of SBR and 0 to 10% of conductive carbon black; based on the mass of the second negative electrode layer of the second negative electrode sheet, the material of the second negative electrode layer of the second negative electrode sheet includes 90% to 98% of fast-filling graphite, 0 to 10% of CMC, 0 to 10% of SBR and 0 to 10% of conductive carbon black; Based on the mass of the first positive electrode layer of the first positive electrode sheet, the material of the first positive electrode layer of the first positive electrode sheet includes 90% to 98% of lithium cobalt oxide, 0 to 10% of PVDF and 0 to 10% of conductive carbon black; based on the mass of the second positive electrode layer of the first positive electrode sheet, the material of the second positive electrode layer of the first positive electrode sheet includes 90% to 98% of lithium cobalt oxide, 0 to 10% of PVDF and 0 to 10% of conductive carbon black; Based on the mass of the first positive electrode layer of the second positive electrode sheet, the material of the first positive electrode layer of the second positive electrode sheet includes 90% to 98% of lithium cobalt oxide, 0 to 10% of PVDF and 0 to 10% of conductive carbon black. Based on the mass of the second positive electrode layer of the second positive electrode sheet, the material of the second positive electrode layer of the second positive electrode sheet includes 90% to 98% of lithium cobalt oxide, 0 to 10% of PVDF and 0 to 10% of conductive carbon black.

7. The bare battery cell according to claim 5, characterized in that: Based on the mass of the first negative electrode layer of the first negative electrode sheet, the material of the first negative electrode layer of the first negative electrode sheet includes 90% to 98% of silicon-carbon negative electrode, 0 to 10% of CMC, 0 to 10% of SBR and 0 to 10% of conductive carbon black, the silicon-carbon negative electrode includes silicon-carbon material and graphite, and the content of the silicon-carbon material is 1% to 98% based on the mass of the silicon-carbon negative electrode, and based on the mass of the second negative electrode layer of the first negative electrode sheet, the material of the second negative electrode layer of the first negative electrode sheet includes 90% to 99% of ordinary graphite, 0 to 10% of CMC, 0 to 10% of SBR and 0 to 10% of conductive carbon black; Based on the mass of the first negative electrode layer of the second negative electrode sheet, the material of the first negative electrode layer of the second negative electrode sheet includes 90% to 98% of silicon-carbon negative electrode, 0 to 10% of CMC, 0 to 10% of SBR and 0 to 10% of conductive carbon black; based on the mass of the second negative electrode layer of the second negative electrode sheet, the material of the second negative electrode layer of the second negative electrode sheet includes 90% to 99% of ordinary graphite, 0 to 10% of CMC, 0 to 10% of SBR and 0 to 10% of conductive carbon black; Based on the mass of the first positive electrode layer of the first positive electrode sheet, the material of the first positive electrode layer of the first positive electrode sheet includes 90% to 98% of lithium cobalt oxide, 0 to 10% of PVDF and 0 to 10% of conductive carbon black; based on the mass of the second positive electrode layer of the first positive electrode sheet, the material of the second positive electrode layer of the first positive electrode sheet includes 90% to 98% of lithium cobalt oxide, 0 to 10% of PVDF and 0 to 10% of conductive carbon black; Based on the mass of the first positive electrode layer of the second positive electrode sheet, the material of the first positive electrode layer of the second positive electrode sheet includes 90% to 98% of lithium cobalt oxide, 0 to 10% of PVDF and 0 to 10% of conductive carbon black, and the material of the second positive electrode layer of the second positive electrode sheet includes 90% to 98% of lithium cobalt oxide, 0 to 10% of PVDF and 0 to 10% of conductive carbon black.

8. The bare battery cell according to claim 4, characterized in that: The negative electrode active material of the first negative electrode layer in the first negative electrode sheet is different from the negative electrode active material of the second negative electrode layer; The negative electrode active material of the first negative electrode layer in the second negative electrode sheet is different from the negative electrode active material of the second negative electrode layer, the negative electrode active material of the first negative electrode layer in the second negative electrode sheet is the same as the negative electrode active material of the first negative electrode layer in the first negative electrode sheet, and the negative electrode active material of the second negative electrode layer in the second negative electrode sheet is the same as the negative electrode active material of the second negative electrode layer in the first negative electrode sheet; The first positive electrode layer in the first positive electrode sheet is the same as the second positive electrode layer, the first positive electrode layer in the second positive electrode sheet is the same as the second positive electrode layer, and the first positive electrode layer of the second positive electrode sheet is different from the first positive electrode layer of the first positive electrode sheet.

9. The bare battery cell according to claim 8, characterized in that: The positive electrode active material of the first positive electrode layer of the second positive electrode sheet is different from the positive electrode active material of the first positive electrode layer of the first positive electrode sheet.

10. The bare battery cell according to claim 9, characterized in that: Based on the mass of the first negative electrode layer of the first negative electrode sheet, the material of the first negative electrode layer of the first negative electrode sheet includes 90% to 98% of ordinary graphite, 0 to 10% of CMC, 0 to 10% of SBR and 0 to 10% of conductive carbon black; based on the mass of the second negative electrode layer of the first negative electrode sheet, the material of the second negative electrode layer of the first negative electrode sheet includes 90% to 98% of silicon-carbon negative electrode, 0 to 10% of CMC, 0 to 10% of SBR and 0 to 10% of conductive carbon black; Based on the mass of the first negative electrode layer of the second negative electrode sheet, the material of the first negative electrode layer of the second negative electrode sheet includes 90% to 98% of ordinary graphite, 0 to 10% of CMC, 0 to 10% of SBR and 0 to 10% of conductive carbon black; based on the mass of the second negative electrode layer of the second negative electrode sheet, the material of the second negative electrode layer of the second negative electrode sheet includes 90% to 98% of silicon-carbon negative electrode, 0 to 10% of CMC, 0 to 10% of SBR and 0 to 10% of conductive carbon black; Wherein, the silicon-carbon negative electrode comprises silicon-carbon material and graphite, and the content of the silicon-carbon material is 1% to 98% based on the mass of the silicon-carbon negative electrode; Based on the mass of the first positive electrode layer of the first positive electrode sheet, the material of the first positive electrode layer of the first positive electrode sheet includes 90% to 98% of lithium cobalt oxide, 0% to 10% of PVDF and 0% to 10% of conductive carbon black; Based on the mass of the first positive electrode layer of the second positive electrode sheet, the material of the first positive electrode layer of the second positive electrode sheet includes 90% to 98% of ternary five-series material, 0 to 10% of PVDF and 0 to 10% of conductive carbon black.

11. The bare battery cell according to claim 4, characterized in that: The first negative electrode layer of the first negative electrode sheet is the same as the second negative electrode layer of the first negative electrode sheet, the first negative electrode layer of the second negative electrode sheet is the same as the second negative electrode layer of the second negative electrode sheet, and the negative electrode active material of the first negative electrode layer of the second negative electrode sheet is different from the negative electrode active material of the first negative electrode layer of the first negative electrode sheet; The first positive electrode layer of the first positive electrode sheet is different from the second positive electrode layer of the first positive electrode sheet, and the first positive electrode layer of the second positive electrode sheet is different from the second positive electrode layer of the second positive electrode sheet.

12. The bare battery cell according to claim 1, characterized in that: Each of the positive electrode sheets comprises a positive electrode current collector and a positive electrode layer covering the surface of the positive electrode current collector, and at least one of the positive electrode sheets further comprises a passivation layer; The passivation layer covers the surface of the positive electrode current collector, and the passivation layer is located between the positive electrode current collector and the positive electrode layer.

13. The bare battery cell according to claim 12, characterized in that: The material of the passivation layer is lithium iron phosphate or aluminum oxide.

14. The bare battery cell according to claim 1, characterized in that: Each of the positive electrode sheets includes a positive electrode layer, each of the negative electrode sheets includes a negative electrode layer, the positive electrode layers of the plurality of positive electrode sheets are the same, and the negative electrode layers of the plurality of negative electrode sheets are the same.

15. The bare battery cell according to claim 14, characterized in that: Each of the negative electrode sheets comprises a negative electrode current collector and two negative electrode layers, the two negative electrode layers are respectively coated on two surfaces of the negative electrode current collector which are arranged opposite to each other in the thickness direction, and the material of each negative electrode layer comprises 90% to 99% of ordinary graphite, 0 to 10% of CMC, 0 to 10% of SBR and 0 to 10% of conductive carbon black based on the mass of the negative electrode layer; Each of the positive electrode sheets comprises a positive electrode current collector and two positive electrode layers, wherein the two positive electrode layers are respectively covered on two surfaces of the positive electrode current collector which are arranged opposite to each other in the thickness direction. Based on the mass of the positive electrode layers, the material of each positive electrode layer comprises 90% to 98% of lithium cobalt oxide, 0 to 10% of PVDF and 0 to 10% of conductive carbon black.

16. The bare battery cell according to any one of claims 1 to 15, characterized in that: The bare battery cell further includes a plurality of negative electrode tabs and a plurality of positive electrode tabs, each negative electrode sheet is electrically connected to at least one of the negative electrode tabs, and each positive electrode sheet is electrically connected to at least one of the positive electrode tabs.

17. The bare battery cell according to claim 16, characterized in that: A first empty foil area is provided at the end of the negative electrode collector of at least one of the negative electrode sheets facing the winding center of the bare battery core, and a second empty foil area is provided at the end of the positive electrode collector of at least one of the positive electrode sheets facing the winding center of the bare battery core; At least one of the negative electrode tabs is disposed in the first empty foil area and is electrically connected to the negative electrode current collector of the negative electrode sheet provided with the first empty foil area, and at least one of the negative electrode tabs is disposed in the middle section of a portion of the negative electrode sheet; At least one of the positive electrode tabs is disposed in the second empty foil area and is electrically connected to the positive electrode collector of the positive electrode sheet having the second empty foil area, and at least one of the positive electrode tabs is disposed in the middle section of a portion of the positive electrode sheet.

18. The bare battery cell according to claim 16, characterized in that: A first empty foil area is provided at the end of the negative electrode current collector of at least one of the negative electrode sheets facing the winding center of the bare battery core; At least one of the negative electrode tabs is disposed in the first empty foil area and is electrically connected to the negative electrode current collector of the negative electrode sheet provided with the first empty foil area, and at least one of the negative electrode tabs is disposed in the middle section of a portion of the negative electrode sheet; Each of the positive electrode tabs is arranged in the middle section of the positive electrode sheet.

19. The bare battery cell according to claim 16, characterized in that: A second empty foil area is provided at the end of the positive electrode current collector of at least one of the positive electrode sheets facing the winding center of the bare battery core; Each of the negative electrode tabs is arranged in the middle section of the negative electrode sheet, at least one of the positive electrode tabs is arranged in the second empty foil area and is electrically connected to the positive electrode collector of the positive electrode sheet with the second empty foil area, and at least one of the positive electrode tabs is arranged in the middle section of a portion of the positive electrode sheet.

20. The bare battery cell according to claim 16, characterized in that: Each of the negative electrode tabs is arranged at the middle section of the negative electrode sheet, and each of the positive electrode tabs is arranged at the middle section of the positive electrode sheet.

21. A battery, characterized in that: It comprises a shell, an electrolyte and a bare battery cell as described in any one of claims 1 to 20, wherein the electrolyte is filled on the inner side of the shell, and the bare battery cell is installed on the inner side of the shell and immersed in the electrolyte.

22. An electronic device, characterized in that: The electronic device comprises the battery as claimed in claim 21, wherein the battery is used to power the electronic device.

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