battery

Abstract

The application provides a battery, which comprises a cell and a shell sleeved outside the cell, a plurality of positive electrode sheets and a plurality of negative electrode sheets of the cell are arranged alternately and spaced, and a separation piece is arranged between adjacent positive electrode sheets and negative electrode sheets for separating the positive electrode sheets and the negative electrode sheets; the arrangement direction of the plurality of positive electrode sheets and the plurality of negative electrode sheets is parallel to the thickness direction of the positive electrode sheets and the negative electrode sheets, the positive electrode sheets at both ends in the arrangement direction among the plurality of positive electrode sheets have buffer regions between both sides of the positive electrode sheets in a first direction and both sides of the shell in the first direction, the negative electrode sheets at both ends in the arrangement direction among the plurality of negative electrode sheets have buffer regions between both sides of the negative electrode sheets in the first direction and both sides of the shell in the first direction, the first direction is perpendicular to the arrangement direction, and the buffer regions have the separation pieces and do not contain the positive electrode sheets and the negative electrode sheets. The battery provided by the application can reduce the probability of lithium or sodium precipitation on the side edges of the cell, thereby improving the cycle capacity retention rate of the battery and improving the cycle performance of the battery.

Description

Technical Field

[0001] This invention relates to the field of battery technology, and more specifically, to a battery. Background Technology

[0002] With increasing global environmental awareness, the new energy industry is gaining popularity. One type of existing soft-pack rechargeable battery (also known as a rechargeable battery or storage battery) consists of an aluminum-plastic film and a battery cell. The aluminum-plastic film can be used as a soft outer shell to cover the battery cell.

[0003] However, in the long-term charge-discharge cycle use of a certain type of soft-pack secondary battery, lithium or sodium plating is prone to occur on the side edges of the cell. This results in a faster rate of capacity decline during the charge-discharge cycle, meaning that the battery has poor cycle capacity retention and poor cycle performance. Summary of the Invention

[0004] The present invention aims to solve at least one of the technical problems existing in the prior art, and proposes a battery that can reduce the probability of lithium or sodium plating on the side edges of the battery cell, thereby improving the cycle capacity retention rate and cycle performance of the battery.

[0005] To achieve the purpose of this invention, a battery is provided, comprising a battery cell and a casing disposed outside the battery cell. The battery cell includes a separator, a plurality of positive electrode plates and a plurality of negative electrode plates, wherein the plurality of positive electrode plates and the plurality of negative electrode plates are arranged alternately and at intervals, and the separator is disposed between adjacent positive electrode plates and the negative electrode plates, wherein the separator is used to isolate adjacent positive electrode plates and the negative electrode plates.

[0006] The arrangement direction of the plurality of positive electrode sheets and the plurality of negative electrode sheets is parallel to the thickness direction of the positive electrode sheets and the negative electrode sheets. Among the plurality of positive electrode sheets, the positive electrode sheets at both ends of the arrangement direction have buffer areas between the two sides of the positive electrode sheet in the first direction and the two sides of the outer shell in the first direction. Among the plurality of negative electrode sheets, the negative electrode sheets at both ends of the arrangement direction have buffer areas between the two sides of the negative electrode sheet in the first direction and the two sides of the outer shell in the first direction. The first direction is perpendicular to the arrangement direction.

[0007] The buffer region contains the separator but does not contain the positive electrode and the negative electrode.

[0008] Optionally, the length of the positive electrode at both ends of the arrangement direction in the first direction is less than the length of the positive electrode at the middle portion of the arrangement direction in the first direction; the length of the negative electrode at both ends of the arrangement direction in the first direction is less than the length of the negative electrode at the middle portion of the arrangement direction in the first direction; and the length of the outer casing in the first direction is equal from one side to the other in the arrangement direction.

[0009] Optionally, the length of the positive electrode in the first direction gradually decreases from the positive electrode in the middle of the plurality of positive electrodes in the arrangement direction to the positive electrodes at both ends of the arrangement direction, and / or the length of the negative electrode in the first direction gradually decreases from the negative electrode in the middle of the plurality of negative electrodes in the arrangement direction to the negative electrodes at both ends of the arrangement direction.

[0010] Optionally, taking the positive electrode in the middle of the plurality of positive electrode sheets in the arrangement direction as the axis of symmetry, the positive electrode sheets at symmetrical positions at both ends of the arrangement direction have equal lengths in a first direction, and / or, taking the negative electrode in the middle of the plurality of negative electrode sheets in the arrangement direction as the axis of symmetry, the negative electrode sheets at symmetrical positions at both ends of the arrangement direction have equal lengths in a first direction.

[0011] Optionally, the two sides of the isolation member in the first direction are in contact with the inner walls of the outer casing on both sides in the first direction.

[0012] Optionally, in a second direction perpendicular to both the arrangement direction and the first direction, a positive electrode tab is provided on one side of the positive electrode sheet, and a negative electrode tab is provided on one side of the negative electrode sheet.

[0013] Optionally, in the second direction, the positive electrode tab and the negative electrode tab are located on the same side or opposite sides.

[0014] Optionally, the outer casing is rectangular or square in cross-section formed by the first direction and the arrangement direction.

[0015] Optionally, the buffer area is triangular in shape in the cross section formed by the first direction and the arrangement direction.

[0016] Optionally, the outer casing is made of aluminum-plastic film.

[0017] The present invention has the following beneficial effects:

[0018] The battery provided by this invention has buffer regions between the two sides of the positive electrode sheets at both ends of the arrangement direction in a first direction and the two sides of the outer casing in the first direction, and buffer regions between the two sides of the negative electrode sheets at both ends of the arrangement direction in a first direction and the two sides of the outer casing in the first direction, with the buffer regions containing spacers between adjacent positive and negative electrode sheets but not containing the positive and negative electrode sheets themselves. Since the first direction is perpendicular to the arrangement direction parallel to the thickness direction of the positive and negative electrode sheets, this design ensures that when the positive and / or negative electrode sheets expand along their thickness direction, causing deformation of the outer casing, the pressure of the outer casing on the side edges of the battery cell first squeezes the buffer regions and the spacers within them. After the buffer regions are completely squeezed by the outer casing, the pressure on the battery cell side edges is further reduced. The positive and / or negative electrode plates at both ends of the arrangement direction are only subjected to the pressure of the casing on both sides of the first direction (i.e., the positions corresponding to the side edges of the cell). In this way, the buffer area and the separator in the buffer area can play a certain supporting and buffering role between the casing and the positive and / or negative electrode plates. Thus, when the positive and / or negative electrode plates expand along their thickness direction and cause the casing to deform, the casing will not directly press on the positive and / or negative electrode plates at both ends of the arrangement direction on both sides of the first direction. This can improve the uniformity of the extrusion force from different directions on the positive and / or negative electrode plates corresponding to the positions of the side edges of the cell, thereby reducing the probability of lithium or sodium plating on the side edges of the cell, and thus improving the cycle capacity retention rate and cycle performance of the battery. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the battery structure when it is not expanded, as provided in an embodiment of the present invention.

[0020] Figure 2 This is a schematic diagram of the battery structure during expansion, provided in an embodiment of the present invention.

[0021] Figure 3 Photos of lithium or sodium plating on the negative electrode of an existing battery after multiple charge-discharge cycles;

[0022] Figure 4 This is a photograph of the negative electrode of the battery provided in an embodiment of the present invention, showing that no lithium or sodium has been deposited after multiple charge-discharge cycles;

[0023] Figure 5 A comparison graph showing the capacity retention rate of existing batteries after multiple charge-discharge cycles with that of the battery provided in the embodiments of the present invention after multiple charge-discharge cycles;

[0024] Explanation of reference numerals in the attached figures:

[0025] 1-Battery; 11-Casing; 12-Positive electrode; 13-Negative electrode; 14-Buffer area; 15-Separator; 16-Negative electrode tab. Detailed Implementation

[0026] To enable those skilled in the art to better understand the technical solution of the present invention, the following analysis is conducted on an existing soft-pack secondary battery where lithium or sodium plating easily occurs on the side edges of the cell during long-term charge-discharge cycle use. The inventors of this invention discovered that in the long-term charge-discharge cycle use of a conventional soft-pack secondary battery, the electrode plates of the battery cell gradually expand, and the thickness gradually increases, causing the battery cell to expand. This expansion leads to deformation of the aluminum-plastic film, increasing its thickness. The side edges of the aluminum-plastic film contract towards the side edges of the battery cell. This deformation of the aluminum-plastic film compresses the battery cell. Specifically, the side edges of the battery cell are subjected to oblique compressive forces from the side edges of the aluminum-plastic film and compressive forces from the thickness direction of the aluminum-plastic film onto the thickness direction of the battery cell. In other words, the side edges of the battery cell are subjected to compressive forces in different directions, while the rest of the battery cell is subjected to compressive forces in only one direction. This results in a pressure difference between the side edges and the rest of the battery cell, and this pressure difference increases with the expansion of the battery cell. As the pressure difference between the side edges and the rest of the battery cell increases, the side edges of the battery cell are more prone to lithium or sodium deposition.

[0027] The battery provided by the present invention will now be described in detail with reference to the accompanying drawings.

[0028] like Figure 1 and Figure 2 As shown, this embodiment of the invention provides a battery 1, including a battery cell and a casing 11 covering the battery cell. The battery cell includes a separator 15, a plurality of positive electrode plates 12 and a plurality of negative electrode plates 13. The plurality of positive electrode plates 12 and the plurality of negative electrode plates 13 are arranged alternately and at intervals. A separator 15 is provided between adjacent positive electrode plates 12 and negative electrode plates 13 to isolate adjacent positive electrode plates 12 and negative electrode plates 13. The arrangement direction of the plurality of positive electrode plates 12 and the plurality of negative electrode plates 13 is the same as that of the positive electrode plates 12 and the negative electrode plates 13. The thickness direction is parallel. Among the multiple positive electrode sheets 12, the positive electrode sheets 12 at both ends of the arrangement direction have a buffer region 14 between the two sides of the outer shell 11 in the first direction and the two sides of the outer shell 11 in the first direction. Among the multiple negative electrode sheets 13, the negative electrode sheets 13 at both ends of the arrangement direction have a buffer region 14 between the two sides of the outer shell 11 in the first direction and the two sides of the outer shell 11 in the first direction. The first direction is perpendicular to the arrangement direction. The buffer region 14 has a separator 15 but does not contain the positive electrode sheet 12 and the negative electrode sheet 13.

[0029] The battery 1 provided in this embodiment of the invention has a buffer region 14 between the two sides of the positive electrode 12 at both ends of the arrangement direction in a first direction and the two sides of the outer casing 11 in the first direction, and a buffer region 14 between the two sides of the negative electrode 13 at both ends of the arrangement direction in a first direction and the two sides of the outer casing 11 in the first direction, since the first direction is perpendicular to the arrangement direction parallel to the thickness direction of the positive electrode 12 and the negative electrode 13. Therefore, this design allows the outer casing 11 to press the side edge of the cell first against the buffer region 14 and the spacer 15 in the buffer region 14 when the positive electrode 12 and / or the negative electrode 13 expand along their thickness direction, causing the outer casing 11 to deform. After the buffer region 14 is completely pressed by the outer casing 11, the positive electrode 12 at both ends of the arrangement direction and / or the negative electrode 13 have buffer regions 14 between the two sides of the cell and the outer casing 11 in the first direction. The negative electrode 13 is only squeezed by the outer casing 11 on both sides in the first direction (i.e., the positions corresponding to the side edges of the cell). In this way, the buffer area 14 and the separator 15 in the buffer area 14 can play a certain supporting and buffering role between the outer casing 11 and the positive electrode 12 and / or negative electrode 13. Thus, when the positive electrode 12 and / or negative electrode 13 expand along its thickness direction and cause the outer casing 11 to deform, the outer casing 11 can prevent the positive electrode 12 and / or negative electrode 13 at both ends of the arrangement direction from being directly squeezed on both sides in the first direction. This can improve the uniformity of the squeezing force from different directions on the positive electrode 12 and / or negative electrode 13 corresponding to the positions of the side edges of the cell, thereby reducing the probability of lithium or sodium deposition on the side edges of the cell, and thus improving the cycle capacity retention rate of the battery 1 and improving the cycle performance of the battery 1.

[0030] like Figure 1 and Figure 2 As shown, taking an example with 5 positive electrode plates 12 and 6 negative electrode plates 13, in the arrangement direction of the multiple positive electrode plates 12 and multiple negative electrode plates 13 parallel to the thickness direction of the multiple positive electrode plates 12 and multiple negative electrode plates 13, by... Figure 1 and Figure 2From top to bottom, the electrodes can be arranged in sequence as follows: first negative electrode 13, first positive electrode 12, second negative electrode 13, second positive electrode 12, third negative electrode 13, third positive electrode 12, fourth negative electrode 13, fourth positive electrode 12, fifth negative electrode 13, fifth positive electrode 12, and sixth negative electrode 13, with a spacer 15 provided between adjacent positive electrode 12 and negative electrode 13. Among the plurality of positive electrode plates 12, the positive electrode plate 12 in the middle portion of the arrangement direction is the third positive electrode plate 12; the positive electrode plates 12 in one end portion of the arrangement direction are the first and second positive electrode plates 12; and the positive electrode plates 12 in the other end portion of the arrangement direction are the fourth and fifth positive electrode plates 12. Similarly, among the plurality of negative electrode plates 13, the negative electrode plates 13 in the middle portion of the arrangement direction are the third and fourth negative electrode plates 13; and the positive electrode plates 12 in one end portion of the arrangement direction are the fourth and fifth positive electrode plates 12. The negative electrode 13 at one end is the first negative electrode 13 and the second negative electrode 13, and the negative electrode 13 at the other end of the arrangement direction is the fifth negative electrode 13 and the sixth negative electrode 13. That is to say, the first negative electrode 13, the first positive electrode 12, the second negative electrode 13, the second positive electrode 12, the fourth positive electrode 12, the fifth negative electrode 13, the fifth positive electrode 12 and the sixth negative electrode 13 have a buffer area 14 between the first negative electrode 13 and the outer casing 11 on both sides in the first direction.

[0031] like Figure 2 As shown, when the positive electrode 12 and / or the negative electrode 13 expand along their thickness direction, causing the outer casing 11 to deform, the thickness of the outer casing 11 will increase due to the increased thickness of the positive electrode 12 and / or the negative electrode 13. The side edges of the outer casing 11 will contract towards the side edges of the battery cell, and the side edges of the battery cell will be subjected to an oblique compressive force (e.g., the side edges of the outer casing 11 on the side edges of the battery cell). Figure 2 As shown in the figure, the extrusion pressure Fa is also subjected to extrusion pressure in the thickness direction of the cell on the thickness direction of the outer casing 11 (e.g., the extrusion pressure Fa is shown in the figure). Figure 2 As shown in the extrusion pressure Fb, the side edges of the battery cell are subjected to extrusion forces from different directions of the casing 11, while the rest of the battery cell is subjected to extrusion forces from only one direction of the casing 11. Because the first negative electrode 13, the first positive electrode 12, the second negative electrode 13, the second positive electrode 12, the fourth positive electrode 12, the fifth negative electrode 13, the fifth positive electrode 12, and the sixth negative electrode 13, corresponding to the positions of the side edges of the battery cell, all have buffer regions 14 between their sides in the first direction and the sides of the casing 11 in the first direction, and these buffer regions 14 contain separators 15 between these positive electrode 12 and negative electrode 13 but do not contain these positive electrode 12 and negative electrode 13 themselves.

[0032] Therefore, the compression of the side edges of the outer casing 11 onto the side edges of the battery cell will first compress the buffer areas 14 and the spacers 15 within the buffer areas 14. Only after the buffer areas 14 are completely compressed by the outer casing 11 will the first negative electrode 13, the first positive electrode 12, the second negative electrode 13, the second positive electrode 12, the fourth positive electrode 12, the fifth negative electrode 13, the fifth positive electrode 12, and the sixth negative electrode 13 be compressed by the outer casing 11 on both sides in the first direction (i.e., the positions corresponding to the side edges of the battery cell). In this way, the buffer areas 14 and the spacers 15 within the buffer areas 14 can provide a certain degree of support and buffering between the outer casing 11 and the positive electrode 12 and / or the negative electrode 13. This prevents the outer casing 11 from deforming when the positive electrode 12 and / or the negative electrode 13 expand along their thickness direction. The first negative electrode 13, the first positive electrode 12, the second negative electrode 13, the second positive electrode 12, the fourth positive electrode 12, the fifth negative electrode 13, the fifth positive electrode 12, and the sixth negative electrode 13 are directly squeezed onto both sides in the first direction. This improves the uniformity of the extrusion force from different directions on the first negative electrode 13, the first positive electrode 12, the second negative electrode 13, the second positive electrode 12, the fourth positive electrode 12, the fifth negative electrode 13, the fifth positive electrode 12, and the sixth negative electrode 13 corresponding to the side edge positions of the battery cell. This reduces the probability of lithium or sodium deposition on the side edge of the battery cell, thereby reducing the rate of capacity decrease of the battery 1 during charge and discharge cycles, and improving the cycle capacity retention rate and cycle performance of the battery 1.

[0033] However, in practical applications, the number of positive electrode plates 12 and negative electrode plates 13 included in the battery cell are not limited to this, nor are the number of positive electrode plates 12 and negative electrode plates 13 in the middle part of the arrangement direction of the multiple positive electrode plates 12 and the multiple negative electrode plates 13, nor are the number of positive electrode plates 12 and negative electrode plates 13 in the two ends part of the arrangement direction of the multiple positive electrode plates 12 and the multiple negative electrode plates 13.

[0034] In one embodiment of the present invention, the outer shell 11 may be made of aluminum-plastic film.

[0035] Optionally, the first direction can be the width direction of the positive electrode 12 and / or the negative electrode 13.

[0036] Optionally, battery 1 can be a lithium-ion secondary battery 1 or a sodium-ion secondary battery 1.

[0037] Optionally, the negative electrode active material in the negative electrode 13 may include one or more of silicon, silicon alloy, silicon oxide, silicon carbon, graphite, hard carbon, tin, and tin alloy.

[0038] Optionally, the positive electrode active material of the positive electrode 12 can be an 811 high-nickel ternary material. However, the positive electrode active material of the positive electrode 12 is not limited to this. For example, the positive electrode active material of the positive electrode 12 can also be a lithium-ion positive electrode material or a sodium-ion positive electrode material.

[0039] Optionally, the lithium-ion cathode material can be one or a mixture of several of the following materials: binary materials, ternary materials, lithium iron phosphate materials, lithium cobalt oxide materials, lithium manganese oxide materials, lithium nickel oxide materials, lithium titanate materials, and lithium manganese iron phosphate materials.

[0040] Optionally, the sodium ion cathode material can be one or a mixture of polyanionic materials, Prussian blue materials, and layered oxide materials.

[0041] Optionally, an electrolyte may be injected into the housing 11.

[0042] like Figure 1 and Figure 2 As shown, in one embodiment of the present invention, the length of the positive electrode 12 at both ends of the arrangement direction in the first direction of the plurality of positive electrode sheets 12 may be less than the length of the positive electrode 12 at the middle part of the arrangement direction in the first direction. The length of the negative electrode 13 at both ends of the arrangement direction in the first direction of the plurality of negative electrode sheets 13 may be less than the length of the negative electrode 13 at the middle part of the arrangement direction in the first direction. The length of the outer shell 11 in the first direction is equal from one side to the other side of the arrangement direction.

[0043] Since the outer casing 11 is fitted over the battery cell, the length of the outer casing 11 in the first direction is greater than the length of any positive electrode 12 in the first direction and greater than the length of any negative electrode 13 in the first direction. Therefore, this design enables the positive electrode 12 at both ends of the arrangement direction to have a buffer area 14 between the two sides of the outer casing 11 in the first direction and the two sides of the negative electrode 13 at both ends of the arrangement direction to have a buffer area 14 between the two sides of the outer casing 11 in the first direction.

[0044] Specifically, taking the first negative electrode 13, the first positive electrode 12, the second negative electrode 13, the second positive electrode 12, the third negative electrode 13, the third positive electrode 12, the fourth negative electrode 13, the fourth positive electrode 12, the fifth negative electrode 13, the fifth positive electrode 12, and the sixth negative electrode 13 mentioned above as examples. The lengths of the first positive electrode 12, the second positive electrode 12, the fourth positive electrode 12, and the fifth positive electrode 12 in the first direction can all be less than the length of the third positive electrode 12 in the first direction. Similarly, the lengths of the first negative electrode 13, the second negative electrode 13, the fifth negative electrode 13, and the sixth negative electrode 13 in the first direction can all be less than the lengths of the third and fourth negative electrode 13 in the first direction. This enables the first negative electrode 13, the first positive electrode 12, the second negative electrode 13, the second positive electrode 12, the fourth positive electrode 12, the fifth negative electrode 13, the fifth positive electrode 12, and the sixth negative electrode 13 to have buffer areas 14 between the first negative electrode 13 and the outer casing 11 on both sides in the first direction.

[0045] like Figure 1 As shown, in one embodiment of the present invention, the outer shell 11 may be rectangular or square in cross-section formed by the first direction and the arrangement direction.

[0046] Optionally, the outer shell 11 can be rectangular or cubic.

[0047] like Figure 1 and Figure 2 As shown, in one embodiment of the present invention, the length of the positive electrode 12 in the first direction can gradually decrease from the positive electrode 12 in the middle of the arrangement direction to the positive electrode 12 at both ends of the arrangement direction, and / or the length of the negative electrode 13 in the first direction can gradually decrease from the negative electrode 13 in the middle of the arrangement direction to the negative electrode 13 at both ends of the arrangement direction.

[0048] This design allows the positive electrode 12 at both ends of the arrangement direction to be subjected to oblique extrusion forces from the side edges of the outer casing 11 when the positive electrode 12 and / or negative electrode 13 expand along their thickness direction, causing the outer casing 11 to deform. This, in turn, further reduces the probability of lithium or sodium deposition on the side edges of the cell, thereby further improving the cycle capacity retention rate of the battery 1 and enhancing the cycle performance of the battery 1.

[0049] Specifically, taking the first negative electrode 13, the first positive electrode 12, the second negative electrode 13, the second positive electrode 12, the third negative electrode 13, the third positive electrode 12, the fourth negative electrode 13, the fourth positive electrode 12, the fifth negative electrode 13, the fifth positive electrode 12, and the sixth negative electrode 13 mentioned above as examples. Specifically, the lengths of the second and fourth positive electrode plates 12 in the first direction can both be less than the length of the third positive electrode plate 12 in the first direction; the lengths of the first and fifth positive electrode plates 12 in the first direction can both be less than the lengths of the second and fourth positive electrode plates 12 in the first direction; the lengths of the second and fifth negative electrode plates 13 in the first direction can both be less than the lengths of the third and fourth negative electrode plates 13 in the first direction; and the lengths of the first and sixth negative electrode plates 13 in the first direction can both be less than the lengths of the second and fifth negative electrode plates 13 in the first direction. Thus, when the outer casing 11 is rectangular or square in cross-section formed by the first direction and the arrangement direction, the buffer area 14 can be triangular in cross-section formed by the first direction and the arrangement direction.

[0050] like Figure 1 As shown, in one embodiment of the present invention, the buffer region 14 may be triangular in cross-section formed by the first direction and the arrangement direction.

[0051] Optionally, the buffer area 14 can be in the form of a triangular prism.

[0052] Optionally, the buffer region 14 may be a right triangle in the cross-section formed by the first direction and the arrangement direction.

[0053] Optionally, the buffer area 14 can be a right-angled triangular prism.

[0054] like Figure 1 and Figure 2 As shown, in one embodiment of the present invention, the positive electrode 12 in the middle of the arrangement direction among a plurality of positive electrode sheets 12 can be used as the axis of symmetry, and the positive electrode sheets 12 at both ends of the arrangement direction located at symmetrical positions have equal lengths in the first direction. And / or, the negative electrode 13 in the middle of the arrangement direction among a plurality of negative electrode sheets 13 can be used as the axis of symmetry, and the negative electrode sheets 13 at both ends of the arrangement direction located at symmetrical positions have equal lengths in the first direction.

[0055] This design allows the positive electrode 12 at both ends of the arrangement direction to be subjected to oblique extrusion forces from the side edges of the outer casing 11 when the positive electrode 12 and / or negative electrode 13 expand along their thickness direction, causing the outer casing 11 to deform. This, in turn, further reduces the probability of lithium or sodium deposition on the side edges of the cell, thereby further improving the cycle capacity retention rate of the battery 1 and enhancing the cycle performance of the battery 1.

[0056] Specifically, taking the first negative electrode 13, the first positive electrode 12, the second negative electrode 13, the second positive electrode 12, the third negative electrode 13, the third positive electrode 12, the fourth negative electrode 13, the fourth positive electrode 12, the fifth negative electrode 13, the fifth positive electrode 12, and the sixth negative electrode 13 mentioned above as examples, the second positive electrode 12 and the fourth positive electrode 12 are symmetrical about the third positive electrode 12, and the first positive electrode 12 and the fifth positive electrode 12 are symmetrical about the third positive electrode 12. Therefore, the second positive electrode 12... The length of the first negative electrode 13 in the first direction is equal to the length of the fourth positive electrode 12 in the first direction. The second negative electrode 13 and the fifth negative electrode 13 are located symmetrically about the third negative electrode 13 and the fourth negative electrode 13. The first negative electrode 13 and the sixth negative electrode 13 are located symmetrically about the third negative electrode 13 and the fourth negative electrode 13. Therefore, the length of the second negative electrode 13 in the first direction is equal to the length of the fifth negative electrode 13 in the first direction, and the length of the first negative electrode 13 in the first direction is equal to the length of the sixth negative electrode 13 in the first direction.

[0057] Optionally, the separator 15 may pass sequentially between the plurality of positive electrode plates 12 and the plurality of negative electrode plates 13.

[0058] Optionally, the spacer 15 can be a diaphragm.

[0059] Optionally, the diaphragm can be a polyethylene microporous membrane or a polypropylene microporous membrane coated with ceramic (also known as a ceramic diaphragm), or it can be a polyethylene microporous membrane or a polypropylene microporous membrane coated with polyvinylidene fluoride (PVDF) (also known as an adhesive diaphragm).

[0060] like Figure 1 and Figure 2 As shown, in one embodiment of the present invention, the two sides of the isolation member 15 in the first direction can contact the inner walls of the outer casing 11 on both sides in the first direction respectively.

[0061] This design can enhance the supporting and buffering effect of the separator 15 between the outer casing 11 and the positive electrode 12 and / or the negative electrode, thereby further reducing the probability of lithium or sodium deposition on the side edges of the cell, and thus further improving the cycle capacity retention rate of the battery 1 and improving the cycle performance of the battery 1.

[0062] like Figure 1 and Figure 2 As shown, in one embodiment of the present invention, a positive electrode tab (not shown in the figure) may be provided on one side of the positive electrode 12 in a second direction that is perpendicular to the arrangement direction and the first direction, respectively, and a negative electrode tab 16 may be provided on one side of the negative electrode 13.

[0063] In practical applications, the positive electrode 12 can be electrically connected to an external charging and discharging device through the positive electrode tab, and the negative electrode 13 can be electrically connected to an external charging and discharging device through the negative electrode tab 16, thereby realizing the charging and discharging between the battery cell and the external charging and discharging device.

[0064] Optionally, the second direction can be the length direction of the positive electrode 12 and / or the negative electrode 13.

[0065] like Figure 1 and Figure 2 As shown, in one embodiment of the present invention, in the second direction, the positive electrode tab and the negative electrode tab 16 may be located on opposite sides. However, the relative positions of the positive electrode tab and the negative electrode tab 16 are not limited thereto. For example, in the second direction, the positive electrode tab and the negative electrode tab 16 may also be located on the same side. That is, in one embodiment of the present invention, in the second direction, the positive electrode tab and the negative electrode tab 16 may be located on the same side or on opposite sides.

[0066] like Figure 5 The diagram shows a comparison between two types of secondary batteries 1 using existing structures and two types of secondary batteries 1 using the battery structure provided in this embodiment of the invention. The positive electrode 12 of both types of secondary batteries 1 using existing structures and those using the battery structure provided in this embodiment of the invention are made of the same material, the negative electrode 13 is made of the same material, and the separator 15 is made of the same material. They also use the same housing 11 and are filled with electrolyte. With the aluminum metal plate pressurized to 8 N*m and a 5% allowance for battery expansion (distance between the aluminum metal plate and battery 1 / thickness of battery 1), charge-discharge cycle tests were conducted at 45°C at a 1C / 1C rate and a charge-discharge range of 2.5V-4V. After 450 charge-discharge cycles, the negative electrode 13 of the two types of secondary batteries 1 using existing structures showed lithium or sodium plating (e.g., ...) at its edge after disassembly. Figure 3 As shown at point R in the middle), and the cycle capacity retention rate of battery 1 is low (e.g., Figure 5As shown by the two curves in the lower middle section), the negative electrode 13 of the two secondary batteries 1 using the battery structure provided in this embodiment of the invention showed no abnormalities after disassembly, and no lithium or sodium plating was observed (e.g. Figure 4 As shown), and battery 1 has a high cycle capacity retention rate (e.g. Figure 5 (As shown by the two curves in the upper middle).

[0067] In summary, the battery 1 provided in this embodiment of the invention can reduce the probability of lithium or sodium plating on the side edges of the battery cell, thereby improving the cycle capacity retention rate and cycle performance of the battery 1.

[0068] It is understood that the above embodiments are merely exemplary embodiments used to illustrate the principles of the present invention, and the present invention is not limited thereto. For those skilled in the art, various modifications and improvements can be made without departing from the spirit and essence of the present invention, and these modifications and improvements are also considered to be within the scope of protection of the present invention.

Claims

1. A battery, characterized in that, The device includes a battery cell and a housing surrounding the battery cell. The battery cell includes an insulating element, multiple positive electrode plates and multiple negative electrode plates. The multiple positive electrode plates and multiple negative electrode plates are arranged alternately and at intervals. The insulating element is disposed between adjacent positive electrode plates and negative electrode plates. The insulating element is used to isolate adjacent positive electrode plates and negative electrode plates. The arrangement direction of the plurality of positive electrode sheets and the plurality of negative electrode sheets is parallel to the thickness direction of the positive electrode sheets and the negative electrode sheets. Among the plurality of positive electrode sheets, the positive electrode sheets at both ends of the arrangement direction have buffer areas between the two sides of the positive electrode sheet in the first direction and the two sides of the outer shell in the first direction. Among the plurality of negative electrode sheets, the negative electrode sheets at both ends of the arrangement direction have buffer areas between the two sides of the negative electrode sheet in the first direction and the two sides of the outer shell in the first direction. The first direction is perpendicular to the arrangement direction. The buffer region includes the separator but does not contain the positive and negative electrode plates. The buffer region and the separator in the buffer region provide a certain support and buffer between the outer shell and the positive and / or negative electrode plates. This prevents the outer shell from directly pressing the positive and / or negative electrode plates at both ends of the arrangement direction when the positive and / or negative electrode plates expand along their thickness direction, causing the outer shell to deform. This reduces the probability of lithium or sodium plating on the side edges of the cell. The length of the negative electrode in the first direction gradually decreases from the negative electrode in the middle of the arrangement direction to the negative electrode at both ends of the arrangement direction.

2. The battery according to claim 1, characterized in that, In the plurality of positive electrode sheets, the length of the positive electrode sheets at both ends of the arrangement direction in the first direction is less than the length of the positive electrode sheets at the middle portion of the arrangement direction in the first direction; in the plurality of negative electrode sheets, the length of the negative electrode sheets at both ends of the arrangement direction in the first direction is less than the length of the negative electrode sheets at the middle portion of the arrangement direction in the first direction; and the length of the outer casing in the first direction is equal from one side to the other in the arrangement direction.

3. The battery according to claim 2, characterized in that, The length of the positive electrode in the first direction gradually decreases from the positive electrode in the middle of the arrangement direction to the positive electrode at both ends of the arrangement direction.

4. The battery according to claim 3, characterized in that, With the positive electrode in the middle of the arrangement direction as the axis of symmetry, the positive electrode pieces at symmetrical positions at both ends of the arrangement direction have equal lengths in a first direction, and / or, with the negative electrode in the middle of the arrangement direction as the axis of symmetry, the negative electrode pieces at symmetrical positions at both ends of the arrangement direction have equal lengths in a first direction.

5. The battery according to claim 1, characterized in that, The isolation member is in contact with the inner walls of the outer casing on both sides in the first direction, corresponding to each other.

6. The battery according to claim 1, characterized in that, In a second direction perpendicular to both the arrangement direction and the first direction, a positive electrode tab is provided on one side of the positive electrode sheet, and a negative electrode tab is provided on one side of the negative electrode sheet.

7. The battery according to claim 6, characterized in that, In the second direction, the positive electrode tab and the negative electrode tab are located on the same side or opposite sides.

8. The battery according to claim 1, characterized in that, The outer shell is rectangular or square in cross-section formed by the first direction and the arrangement direction.

9. The battery according to claim 1, characterized in that, The buffer area is triangular in shape on the cross section formed by the first direction and the arrangement direction.

10. The battery according to claim 1, characterized in that, The outer shell is made of aluminum-plastic film.

Images