Low-expansion-rate battery pole piece stacking structure and battery

Abstract

The utility model provides a low-expansion-rate battery pole piece stacking structure and a battery, and belongs to the technical field of batteries. The low-expansion-rate battery pole piece stacking structure comprises a plurality of positive pole pieces, a plurality of negative pole pieces and an isolating membrane, and at least one of the positive pole pieces and the negative pole pieces forms an unequal-thickness structure with the thickness gradually reduced through special-shaped coating, so that the positive pole pieces and the negative pole pieces can be gradually bent after being alternately attached and arranged to form an annular closed bare core; and an isolating membrane is clamped between any adjacent positive plate and negative plate. When expansion occurs, the positive plate and the negative plate which are annularly closed are attached and locked to each other so as to restrain expansion. The stacking structure does not need to be additionally provided with an external limiting structure, and is simple in structure and high in practicability. According to the battery adopting the low-expansion-rate battery pole piece stacking structure, the expansion rate of the battery can be greatly reduced, the safety of the battery is improved, and the service life of the battery is prolonged.

Description

Technical Field

[0001] This application belongs to the field of battery technology, and more specifically, relates to a low-expansion-rate battery electrode stacking structure and battery. Background Technology

[0002] Lithium-ion batteries undergo structural expansion or contraction during charging and discharging due to lithium insertion and extraction. During charging, the negative electrode side experiences either intercalation or alloying lithium insertion. Therefore, the negative electrode material generally exhibits significant volume expansion with increasing lithium insertion depth. For example, graphite negative electrodes typically experience a 10% to 15% volume expansion, while silicon-based negative electrodes can experience up to 300% volume expansion. This expansion of the battery's negative electrode significantly impacts battery performance and lifespan.

[0003] In the prior art, Chinese utility model patent CN208272050U discloses a silicon anode soft-pack lithium-ion battery cell structure. This structure features a steel casing surrounding the battery core. When the battery expands internally during charging, the entire core expands outwards, and the steel casing undergoes elastic deformation along with the core. When the battery contracts during discharge, the stress on the steel casing can contract inwards, reducing internal polarization and thus improving the cycle life of the silicon anode soft-pack lithium-ion battery. However, this solution restricts cell expansion through the forced confinement of the external steel casing, rather than by limiting expansion through the structure of the bare cell itself. Summary of the Invention

[0004] To address the shortcomings of existing technologies, this application provides a low-expansion-rate battery electrode stacking structure and battery, which can suppress expansion through the mutual restraint of the positive and negative electrode sheets.

[0005] To achieve the above objectives, the technical solution of this application provides a low expansion rate battery electrode stacking structure, including a plurality of positive electrode sheets, a plurality of negative electrode sheets and a separator. At least one of the positive electrode sheets and the negative electrode sheets is formed by irregular coating to form a structure with unequal thickness from thick to thin. The plurality of positive electrode sheets and the plurality of negative electrode sheets are alternately bonded and arranged, and a ring-shaped closed bare core is formed by the unequal thickness structure. A separator is sandwiched between any adjacent positive electrode sheets and negative electrode sheets.

[0006] Because the positive and negative electrodes are arranged in a closed ring-shaped bare core, when expansion occurs, the closed ring-shaped positive and negative electrodes adhere and lock together to suppress expansion. This stacked structure does not require additional external limiting structures, making it simple and highly practical.

[0007] Optionally, the separator is sandwiched between any adjacent positive and negative electrode plates through a Z-shaped stacked structure to achieve isolation stacking between the positive and negative electrode plates.

[0008] Optionally, the bare core has an outer peripheral wall and an inner peripheral wall, and the separator is bent at the outer peripheral wall and the inner peripheral wall to achieve a Z-shaped stacked structure.

[0009] Optionally, the bare core is in the form of a circular ring-shaped column or a polygonal ring-shaped column, which facilitates the fabrication of columnar batteries of different shapes.

[0010] A battery employs a low-expansion-rate battery electrode stacking structure as described above. Since the positive and negative electrodes are bonded and locked together through a ring structure, the battery expansion rate can be significantly reduced without setting additional limiting components, thereby improving the battery's safety and lifespan.

[0011] Optionally, it also includes a shell, an outer insulating layer, an inner insulating layer, a core, a positive current collector, a negative current collector, and a cover plate. The positive electrode has a positive tab, the negative electrode has a negative tab, and the cover plate has a positive terminal and a negative terminal. The outer insulating layer is sleeved on the outside of the bare core, the shell is sleeved on the outside of the outer insulating layer, the inner insulating layer is nested inside the bare core, and the core is nested inside the inner insulating layer. The positive current collector is connected to all the positive tabs, the negative current collector is connected to all the negative tabs, the positive current collector is connected to the positive terminal, and the negative current collector is connected to the negative terminal. The cover plate covers the ends of the shell and the core to seal the bare core, and the bare core is filled with electrolyte.

[0012] The positive electrode plate is connected to the positive terminal via a positive current collector, and the negative electrode tab is connected to the negative terminal via a negative current collector. The battery is connected to the outside via the positive and negative terminals to realize the battery function.

[0013] Optionally, all positive tabs are arranged to form a ring-shaped positive tab body, and all negative tabs are arranged to form a ring-shaped negative tab body. The positive and negative tab bodies are nested and spaced apart to avoid direct contact and conduction between them. Both the positive and negative tab bodies face the cover plate. The positive and negative current collectors are both ring-shaped. The positive current collector is located between the positive tab body and the cover plate, and is connected to the end of the positive tab body. The negative current collector is located between the negative tab body and the cover plate, and is connected to the end of the negative tab body.

[0014] Optionally, the positive current collector is provided with a positive electrode connection portion facing the cover plate, and the positive current collector is connected to the positive terminal through the positive electrode connection portion. The negative current collector is provided with a negative electrode connection portion facing the cover plate, and the negative current collector is connected to the negative terminal through the negative electrode connection portion.

[0015] Optionally, the cover plate is equipped with a pressure relief valve to release pressure when the internal pressure of the battery increases. Simultaneously, the cover plate has an injection hole connecting to the bare cell for adding electrolyte.

[0016] The advantages of the technical solution in this application compared to the prior art are as follows:

[0017] Because at least one of the positive and negative electrode sheets is coated with an irregularly shaped material to form a structure of unequal thickness, gradually decreasing in thickness, the positive and negative electrode sheets will gradually bend after being alternately bonded and arranged, forming a closed annular core. A separator is sandwiched between any adjacent positive and negative electrode sheets. Since the positive and negative electrode sheets are arranged in a closed annular core, when expansion occurs, the closed annular positive and negative electrode sheets adhere and lock together to suppress expansion. This stacked structure requires no additional external limiting structure, is simple in structure, and highly practical. Attached Figure Description

[0018] To more clearly illustrate the technical solutions in the embodiments of this application, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0019] Figure 1 This is a schematic diagram of the bare core structure;

[0020] Figure 2 This is a schematic diagram of the positive electrode structure;

[0021] Figure 3 This is a schematic diagram of the negative electrode structure;

[0022] Figure 4 An exploded view of the bare core structure of the separator stacked with the positive and negative electrode plates via a Z-shaped stacked structure;

[0023] Figure 5 A schematic diagram of a bare core structure stacked in a ring-shaped hexagonal prism form;

[0024] Figure 6 This is an exploded view of the battery structure.

[0025] Figure 7 This is a schematic diagram of a battery structure where the positive terminal and the negative terminal are located at the top and bottom, respectively.

[0026] Figure 8 This is a comparison chart of the expansion rate of the battery in this embodiment and that of an existing square aluminum-cased laminated energy storage battery.

[0027] Icons: 1. Positive electrode plate; 101. Positive electrode tab; 102. Aluminum foil; 103. Positive electrode coating; 2. Negative electrode plate; 201. Negative electrode tab; 202. Copper foil; 203. Negative electrode coating; 3. Separator; 4. Bare core; 401. Outer peripheral wall; 402. Inner peripheral wall; 5. Outer shell; 6. Outer insulation layer; 7. Inner insulation layer; 8. Core tube; 9. Positive current collector; 901. Positive electrode connection part; 10. Negative current collector; 110. Negative electrode connection part; 11. Cover plate; 111. Positive electrode terminal; 112. Negative electrode terminal; 113. Pressure relief valve; 114. Injection hole; 12. Positive electrode tab body; 13. Negative electrode tab body. Detailed Implementation

[0028] To make the technical problems, technical solutions, and beneficial effects to be solved by this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and are not intended to limit the scope of this application.

[0029] Example 1:

[0030] This embodiment provides a low-expansion-rate battery electrode stacking structure, including several positive electrode sheets 1, several negative electrode sheets 2, and a separator 3. Based on Figure 2 and Figure 3 As shown, the positive electrode 1 is made of aluminum foil 102 and a positive electrode coating 103 coated on both sides of the aluminum foil 102, and the negative electrode 2 is made of copper foil 202 and a negative electrode coating 203 coated on both sides of the copper foil 202. Both the positive electrode 1 and the negative electrode 2 are formed into a structure of unequal thickness, with the thickness gradually decreasing from thick to thin, through irregular coating. The thickness on the left side of both is greater than the thickness on the right side. Thus, based on... Figure 1 As shown, after several positive electrode plates 1 and several negative electrode plates 2 are alternately bonded and arranged, the overall shape will gradually bend so as to form a ring-shaped closed bare core 4 through the unequal thickness structure. A separator 3 is sandwiched between any adjacent positive electrode plates 1 and negative electrode plates 2.

[0031] Because the positive electrode 1 and negative electrode 2 are arranged in a closed annular core 4, when the negative electrode 2 expands reasonably during normal charging and discharging, the closed annular positive electrode 1 and negative electrode adhere and lock together, suppressing expansion through their own structure, thereby significantly reducing the overall battery expansion rate. Since this stacked structure does not require additional external limiting structures, it reduces the number of components, resulting in a simple structure and high practicality. This low-expansion-rate battery electrode stacking structure can be applied to primary or secondary batteries such as lithium, sodium, magnesium, and fluorine ions.

[0032] based on Figure 4As shown, the separator 3 is sandwiched between any adjacent positive electrode 1 and negative electrode 2 through a Z-shaped stacked structure. The annular bare core 4 has an outer peripheral wall 401 and an inner peripheral wall 402. The separator 3 is bent at the outer peripheral wall 401 and the inner peripheral wall 402 to realize the Z-shaped stacked structure and realize the isolation stacking between the positive electrode 1 and the negative electrode 2.

[0033] In this embodiment, based on Figure 2 and Figure 3 As shown, both the positive electrode 1 and the negative electrode 2 have a fan-shaped or trapezoidal structure to achieve an unequal thickness structure where the thickness gradually decreases. The positive electrode 1, the negative electrode 2, and the separator 3 are stacked to form a ring-shaped columnar structure. Of course, in other embodiments, only the positive electrode 1 can be an unequal thickness structure where the thickness gradually decreases, while the corresponding negative electrode 2 has a conventional planar structure; or only the negative electrode 2 can be an unequal thickness structure where the thickness gradually decreases, while the corresponding positive electrode 1 has a conventional planar structure; or only a portion of the positive electrode 1 and the negative electrode 2 can be an unequal thickness structure where the thickness gradually decreases, which can also achieve a ring-shaped closure after stacking.

[0034] At the same time, based on Figure 5 As shown, in addition to stacking the above-mentioned circular columnar structure, the bare core 4 can also be stacked into a polygonal circular columnar structure such as a hexagonal prism or an octagonal prism, so as to make columnar batteries of different shapes.

[0035] Example 2:

[0036] This embodiment provides a battery that employs the low-expansion-rate battery electrode stacking structure shown in Embodiment 1. Because the positive electrode 1 and the negative electrode are bonded and locked together via a ring structure, the battery's expansion rate can be significantly reduced without the need for additional limiting components, thereby improving battery safety and lifespan.

[0037] In detail, based on Figure 2 , Figure 3 and Figure 6As shown, the battery also includes a casing 5, an outer insulating layer 6, an inner insulating layer 7, a core 8, a positive current collector 9, a negative current collector 10, and a cover plate 11. The positive electrode 1 has a positive tab 101, and the negative electrode 2 has a negative tab 201. The positive current collector 9 and the negative current collector 10 are made of copper or a copper-nickel alloy. The cover plate 11 has a positive terminal 111 and a negative terminal 112. An outer insulating layer 6 is fitted over the outside of the bare core 4, an outer shell 5 is fitted over the outside of the outer insulating layer 6, an inner insulating layer 7 is nested inside the bare core 4, and a core cylinder 8 is nested inside the inner insulating layer 7. A positive current collector 9 is connected to all positive tabs 101, and a negative current collector 10 is connected to all negative tabs 201. The positive current collector 9 is connected to the positive terminal 111, and the negative current collector 10 is connected to the negative terminal 112. The cover plate 11 covers the ends of the outer shell 5 and the core cylinder 8 to seal the bare core 4, which is filled with electrolyte. Thus, the entire bare core 4 is sealed by the outer shell 5, the outer insulating layer 6, the inner insulating layer 7, the core cylinder 8, and the cover plate 11. The positive electrode 1 is connected to the positive terminal 111 through the positive electrode tab 101 and the positive current collector 9, and the negative electrode 2 is connected to the negative terminal 112 through the negative electrode tab 201 and the negative current collector 10. The battery is connected to the outside through the positive terminal 111 and the negative terminal 112 to realize the function of the battery.

[0038] based on Figure 6 As shown, all positive tabs 101 are arranged to form a ring-shaped positive tab body 12, and all negative tabs 201 are arranged to form a ring-shaped negative tab body 13. The positive tab bodies 12 and negative tab bodies 13 are nested and spaced apart to avoid direct contact and conduction between them. Both the positive tab bodies 12 and negative tab bodies 13 face the cover plate 11. In this embodiment, there is one cover plate 11, which covers the top opening of the outer casing 5, while the bottom of the outer casing 5 is closed. Both the positive tab bodies 12 and negative tab bodies 13 face the cover plate 11. Both the positive current collector 9 and the negative current collector 10 are annular. The positive current collector 9 is located between the positive electrode body 12 and the cover plate 11, and is connected to the ends of all the positive electrode bodies 12. The negative current collector 10 is located between the negative electrode body 13 and the cover plate 11, and is connected to the ends of all the negative electrode bodies 13. In this way, all the positive electrode plates 1 and all the negative electrode plates 2 can be connected to the positive terminal 111 and the negative terminal 112 respectively.

[0039] The positive current collector 9 is provided with a positive electrode connection portion 901 facing the cover plate 11. The positive current collector 9 is connected to the positive terminal 111 through the positive electrode connection portion 901, thus achieving conductivity. The negative current collector 10 is provided with a negative electrode connection portion 110 facing the cover plate 11. The negative current collector 10 is connected to the negative terminal 112 through the negative electrode connection portion 110, thus achieving conductivity. At the same time, the cover plate 11 is provided with a pressure relief valve 113 to relieve pressure when the internal pressure of the battery increases. The cover plate 11 has an electrolyte injection hole 114 that communicates with the bare core 4 for adding electrolyte.

[0040] In other embodiments, based on Figure 7 As shown, the top and bottom of the outer casing 5 can both be open, and there are two cover plates 11, which are respectively fastened to the top and bottom of the outer casing 5. The top cover plate 11 has a positive terminal 111, and the bottom cover plate 11 has a negative terminal 112. The positive electrode body 12 is positioned facing the top cover plate 11 and is connected to the positive terminal 111 through the positive current collector 9. The negative electrode body 13 is positioned facing the bottom cover plate 11 and is connected to the negative terminal 112 through the negative current collector 10.

[0041] To further illustrate the technical effects of this invention, two sets of experiments are conducted. Scheme 1 uses the battery with a low-expansion-rate electrode stacking structure as described in this invention, while Scheme 2 uses a commercially available square aluminum-cased stacked energy storage battery. Both Scheme 1 and Scheme 2 have a battery capacity of 280Ah. To ensure a more vigorous reaction, both were subjected to a 15-day 1C charge-discharge test at 60°C, with the battery expansion rate recorded daily for two consecutive days.

[0042] based on Figure 8 As shown, Figure 8 The novel aluminum-cased ring-shaped stacked battery in this design is one example of a battery with a low-expansion-rate electrode stacking structure. Figure 8 The cycle test results show that after 15 days of cycling, the expansion rate of the commonly used square aluminum-cased stacked energy storage battery in Scheme 2 exceeds 12%, while the expansion rate of the battery in Scheme 1, which has a low-expansion-rate electrode stacking structure, is only 1%. This demonstrates that the positive electrode 1 and negative electrode 2, which are condensed together by a ring structure, can significantly reduce the battery's expansion rate.

[0043] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A low-expansion battery electrode sheet stacking structure, comprising a plurality of positive electrode sheets, a plurality of negative electrode sheets, and a separator film; characterized in that At least one of the positive electrode sheets and the negative electrode sheets is formed into an unequal thickness structure with a thickness gradually decreasing from thick to thin by profile coating, the plurality of positive electrode sheets and the plurality of negative electrode sheets are arranged alternately and are closed into a bare core in a ring shape by the unequal thickness structure, and the bare core is clamped between any adjacent positive electrode sheet and negative electrode sheet. The separator film is clamped between any adjacent positive electrode sheet and negative electrode sheet by a Z-shaped lamination structure, and the bare core has an outer peripheral wall and an inner peripheral wall, and the separator film is bent at the outer peripheral wall and the inner peripheral wall.

2. The low expansion battery electrode sheet stack structure of claim 1, wherein: The bare core is in a circular column shape or a polygonal ring column shape.

3. A battery, characterized by: The low-expansion battery electrode sheet stacking structure according to any one of claims 1-2 is adopted.

4. The battery of claim 3, wherein: Further comprising a shell, an outer insulating layer, an inner insulating layer, a core barrel, a positive current collector, a negative current collector, and a cover plate, the positive electrode sheet has a positive electrode lug, the negative electrode sheet has a negative electrode lug, the cover plate has a positive terminal post and a negative terminal post; The outer insulating layer is sleeved on the outside of the bare core, the shell is sleeved on the outside of the outer insulating layer, the inner insulating layer is nested on the inside of the bare core, the core barrel is nested on the inside of the inner insulating layer, the positive current collector is connected with all the positive electrode lugs, the negative current collector is connected with all the negative electrode lugs, the positive current collector is connected with the positive terminal post, the negative current collector is connected with the negative terminal post, the cover plate covers the end of the shell and the core barrel to seal the bare core, and the bare core is filled with electrolyte.

5. The battery of claim 4, wherein: All the positive electrode lugs are arranged into a ring-shaped positive electrode lug body, all the negative electrode lugs are arranged into a ring-shaped negative electrode lug body, the positive electrode lug body and the negative electrode lug body are nested and spaced apart from each other, and the positive electrode lug body and the negative electrode lug body are both arranged towards the cover plate; The positive current collector and the negative current collector are both in a ring shape, the positive current collector is located between the positive electrode lug body and the cover plate, the positive current collector is connected with the end of the positive electrode lug body, the negative current collector is located between the negative electrode lug body and the cover plate, and the negative current collector is connected with the end of the negative electrode lug body.

6. The battery of claim 5, wherein: The positive current collector is provided with a positive electrode connecting portion towards the cover plate, the positive current collector is connected with the positive terminal post through the positive electrode connecting portion, the negative current collector is provided with a negative electrode connecting portion towards the cover plate, and the negative current collector is connected with the negative terminal post through the negative electrode connecting portion.

7. The battery of claim 4 or 5 or 6, wherein: The cover plate is provided with a pressure relief valve, and the cover plate is provided with a liquid injection hole communicating with the bare core.

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