Negative plate and cylindrical battery

Abstract

The utility model discloses a negative plate and a cylindrical battery. The negative plate comprises a current collector, an active material layer and an anti-damage part, the active material layer is coated on the current collector, an active material removal area is arranged on the active material layer, and the active material removal area is positioned at one end of the current collector; and the anti-damage part is arranged on the active material removal area and is used for increasing the thickness of the negative plate corresponding to the active material removal area. Therefore, not only can the use of active materials be reduced, the weight of the battery roll core be reduced and the energy density of the battery be improved, but also the damage problems of warping and the like when the battery roll core enters the steel shell can be avoided, so that the yield of the battery can be improved.

Description

Technical Field

[0001] This utility model relates to the field of battery technology, and in particular to a negative electrode sheet and a cylindrical battery. Background Technology

[0002] With the rapid development of modern technology, market demand in portable electronic devices, electric vehicles, and energy storage is constantly growing, placing higher demands on the energy density of rechargeable batteries. Alkaline nickel-zinc batteries are highly promising aqueous rechargeable batteries, possessing advantages such as high power density and intrinsic safety. They can discharge at 20C rate and do not carry the risk of thermal runaway, making them promising for widespread application in automotive starting power supplies, power tools, backup power supplies, and emergency power supplies. Currently, the practical application of aqueous batteries is mainly limited by energy density. Taking alkaline nickel-zinc batteries as an example, their energy density is generally 60-100Wh / kg, still far lower than that of organic lithium-ion batteries. Currently, through optimization of active materials and battery structure, the energy density of alkaline nickel-zinc batteries is expected to be increased to ≥120Wh / kg, even comparable to organic lithium-ion batteries (lithium iron phosphate batteries). To further improve the energy density of alkaline nickel-zinc batteries, lightweight battery structure design is particularly important.

[0003] The negative electrode of an alkaline nickel-zinc battery is mainly composed of zinc oxide, zinc powder, binder, conductive agent, thickener, and other substances. As a crucial component of the alkaline nickel-zinc battery, the quality and performance of the negative electrode directly affect the overall performance of the battery. Taking a cylindrical battery as an example, the battery core in a cylindrical battery is formed by winding stacked negative electrode sheets, separators, and positive electrode sheets. For alkaline nickel-zinc cylindrical batteries, the active material on the traditional negative electrode sheet is usually entirely covered by a metal current collector. Furthermore, the length of the negative electrode sheet is often greater than that of the positive electrode sheet, and the theoretical capacity of the negative electrode sheet is often much higher than that of the positive electrode sheet. Therefore, after the negative electrode sheet is wound, its outermost layer of active material is usually non-participating in the electrochemical reaction, which not only wastes the outermost active material but also increases the weight of the alkaline nickel-zinc battery. Therefore, the traditional negative electrode structure is not conducive to improving the energy density of alkaline nickel-zinc batteries.

[0004] To further improve the energy density of alkaline nickel-zinc cylindrical batteries, the outermost active material of the negative electrode is typically removed, exposing the inner current collector. While this design reduces the weight of the negative electrode, it results in a thinner end, making the negative electrode tip prone to damage during battery core insertion into the steel casing. For example, the negative electrode tip may warp during casing insertion. A conventional solution is to leave a small portion of active material at the very edge; however, because this area is narrow, it is prone to shedding and powdering, posing a potential short-circuit risk and severely impacting the cycle life of the alkaline nickel-zinc battery. Utility Model Content

[0005] The purpose of this invention is to overcome the shortcomings of the prior art and provide a negative electrode sheet and cylindrical battery that can avoid damage to the end of the negative electrode sheet entering the steel shell, while also achieving a lightweight battery design.

[0006] The objective of this utility model is achieved through the following technical solution:

[0007] A negative electrode sheet includes: a current collector, an active material layer, and a damage prevention component; the active material layer is coated on the current collector, and an active material removal region is provided on the active material layer, the active material removal region being located at one end of the current collector; the damage prevention component is disposed on the side of the active material removal region away from the active material layer, and the damage prevention component is used to increase the thickness of the negative electrode sheet corresponding to the active material removal region.

[0008] In one embodiment, the area of ​​the anti-damage component accounts for 5%-100% of the area of ​​the active material removal region.

[0009] In one embodiment, the damage-preventing component is an adhesive tape, which is attached to the side of the active material removal area away from the active material layer.

[0010] In one embodiment, the adhesive paper is an alkali-resistant adhesive paper.

[0011] In one embodiment, the damage-resistant component is a polymer coating layer applied to the side of the active material removal area away from the active material layer.

[0012] In one embodiment, the polymer coating is an alkali-resistant polymer coating.

[0013] In one embodiment, the active material layer is provided on both sides of the current collector, and an active material removal area is provided on one side of the active material layer, the active material removal area being located at one end of the current collector.

[0014] In one embodiment, the thickness of the damage-resistant component is less than or equal to the thickness of one of the active material layers.

[0015] In one embodiment, the damage-resistant component is provided with an inclined surface, which gradually slopes downwards from the top surface of the damage-resistant component toward the current collector.

[0016] A cylindrical battery includes a negative electrode sheet, a positive electrode sheet, a separator, and a steel shell. The negative electrode sheet, the separator, and the positive electrode sheet are stacked and wound to form a battery core. The active material removal area is located on the outermost ring of the wound negative electrode sheet. The battery core is housed within the steel shell.

[0017] Compared with the prior art, the present invention has at least the following advantages:

[0018] 1. The negative electrode sheet of this utility model adds an anti-damage component to the active material removal area. The anti-damage component increases the thickness of the corresponding active material removal area of ​​the negative electrode sheet, avoiding damage such as warping of the battery core when it is inserted into the steel shell due to the thinning of the end of the negative electrode sheet. This can improve the consistency and yield of the battery, as well as the efficiency of inserting the battery core into the steel shell.

[0019] 2. The negative electrode of this utility model removes the active material at one end of the negative electrode to form an active material removal area, thereby reducing the use of active material, realizing a lightweight design of the negative electrode, reducing the weight of the battery core, and further improving the energy density of the battery.

[0020] 3. The negative electrode of this utility model can reduce the production cost of batteries to a certain extent by reducing the use of active materials. Attached Figure Description

[0021] To more clearly illustrate the technical solutions of the embodiments of this utility model, the accompanying drawings used in the embodiments will be briefly described below.

[0022] Figure 1 This is a schematic diagram of the structure of the battery core in one embodiment of the present invention;

[0023] Figure 2 This is a schematic diagram of the stacked structure of the negative electrode sheet in the first embodiment of this utility model;

[0024] Figure 3 This is a schematic diagram of the stacked structure of the negative electrode sheet in the second embodiment of this utility model;

[0025] Figure 4 This is a schematic diagram of the stacked structure of the negative electrode sheet in the third embodiment of this utility model. Detailed Implementation

[0026] To facilitate understanding of this utility model, a more comprehensive description of this utility model will be given below with reference to the accompanying drawings.

[0027] Please see Figure 1 , Figure 2 and Figure 3 As shown, a negative electrode 10 includes: a current collector 100, an active material layer 200, and a damage prevention component 300. The active material layer 200 is coated on the current collector 100, and an active material removal region 210 is provided on the active material layer 200, located at one end of the current collector 100. The damage prevention component 300 is disposed on the side of the active material removal region 210 away from the active material layer 200, and the damage prevention component 300 is used to increase the thickness of the negative electrode 10 corresponding to the active material removal region 210. Taking an alkaline nickel-zinc battery as an example, the active material layer 200 contains substances such as nano-zinc oxide, metallic zinc powder, nano-bismuth oxide, binder, and thickener, and may also contain inorganic and organic additives that inhibit gas evolution side reactions, control the direction of zinc dendrite growth, and inhibit deformation of the negative electrode 10 during charging and discharging.

[0028] It should be noted that the length of the negative electrode 10 is often greater than that of the positive electrode. After the negative electrode 10 is wound, its outermost active material layer 200 does not participate in the electrochemical reaction. By removing the active material at one end of the negative electrode 10, forming the active material removal area 210, the amount of active material used can be reduced, achieving a lightweight design of the negative electrode 10, reducing the weight of the battery core, and thus further improving the energy density of the battery. In addition, by reducing the amount of active material used in the negative electrode 10, the production cost of the battery can also be reduced to a certain extent. At the same time, in order to avoid damage such as warping at the end of the negative electrode 10 when the battery core is inserted into the steel casing due to its thinner end, an anti-damage component 300 is provided on the active material removal area 210. The anti-damage component 300 increases the thickness of the active material removal area 210 corresponding to the negative electrode sheet 10, ensuring the thickness and flatness of the outermost ring of the negative electrode sheet. This ensures the strength of the outermost ring of the negative electrode sheet, thus preventing damage such as warping when the battery core is inserted into the steel casing, and ensuring smooth insertion of the battery core into the steel casing, improving the battery casing rate and yield. Furthermore, by setting the anti-damage component 300, instead of the conventional method of reserving a local active material at the very edge, the problem of active material shedding and powdering can be avoided, thereby reducing the risk of battery short circuits and improving battery cycle life. It should also be noted that the current collector 100 can be copper foil, tin-plated copper foil, zinc foil, tin-plated zinc foil, or a zinc alloy current collector; preferably, the current collector 100 is tin-plated copper foil with a thickness ranging from 15-50 μm.

[0029] Please see Figure 2 , Figure 3 or Figure 4 As shown, in one embodiment, the area of ​​the anti-damage component 300 accounts for 5%-100% of the area of ​​the active material removal region 210. This ensures that the anti-damage component 300 can fully perform its function. Preferably, the area of ​​the anti-damage component 300 accounts for 5%-20% of the area of ​​the active material removal region 210. This ensures the function of the anti-damage component 300 while avoiding increasing the weight of the negative electrode 10, thereby ensuring the battery's lightweight design and improving its energy density and reliability.

[0030] In one embodiment, the anti-damage component 300 is an adhesive tape, which is attached to the side of the active material removal area 210 away from the active material layer 200. By increasing the thickness of the negative electrode sheet 10 corresponding to the active material removal area 210 through the adhesive tape, damage problems such as warping at the end of the negative electrode sheet 10 can be avoided. In this embodiment, taking an alkaline nickel-zinc cylindrical battery as an example, since the electrolyte of the alkaline nickel-zinc cylindrical battery is alkaline, for example, the alkaline electrolyte contains alkaline substances such as sodium hydroxide, potassium hydroxide, and lithium hydroxide, wherein the concentration of hydroxide ions is 6-15 mol / L, and may also contain organic or inorganic additives that inhibit gas evolution side reactions, zinc dendrite growth, and negative electrode deformation. Therefore, in order to ensure the service life of the adhesive tape, the adhesive tape is an alkali-resistant adhesive tape, such as polytetrafluoroethylene tape, polyethylene tape, polypropylene tape, or polyester high-temperature tape. Since alkali-resistant adhesive paper is a polymer material, its density is much lower than that of the active material of the negative electrode (such as zinc oxide and zinc powder). At the same time, the thickness of alkali-resistant adhesive paper can be less than 200 mm of the active material layer of the negative electrode, thus achieving the effect of lightweight design of alkaline nickel-zinc batteries.

[0031] In another embodiment, the anti-damage component 300 is a polymer coating layer, which is applied to the side of the active material removal area 210 away from the active material layer 200. That is, the polymer material is directly coated onto the side of the active material removal area 210 away from the active material layer 200, thereby increasing the thickness of the negative electrode 10 corresponding to the active material removal area 210 and preventing problems such as warping at the end of the negative electrode 10 when it is inserted into the steel casing. In this embodiment, the polymer coating layer is an alkali-resistant polymer coating layer. Similarly, using an alkali-resistant polymer coating layer makes it suitable for alkaline nickel-zinc batteries, ensuring the service life of the polymer coating layer; for example, alkali-resistant polymer materials such as polytetrafluoroethylene, polystyrene, polymethyl methacrylate, polycarbonate, polypropylene, or polyethylene can be used. In another embodiment, the polymer coating layer can also be a hydrophobic polymer coating layer. The manufacturing methods for alkali-resistant and hydrophobic polymer coating layers can employ coating processes such as screen printing, ultrasonic spraying, and blade coating.

[0032] Please see Figure 2 or Figure 3 As shown, in one embodiment, active material layers 200 are respectively provided on both sides of the current collector 100, and an active material removal area 210 is provided on one side of the active material layer 200, which is located at one end of the current collector 100. That is, when active material layers 200 are provided on both sides of the current collector 100, the active material on one side of the outermost ring of the negative electrode sheet 10 is removed to form the active material removal area 210, thereby achieving a lightweight design of the battery and improving the energy density of the battery. In this embodiment, the thickness of the anti-damage component 300 is equal to the thickness of one side of the active material layer 200, thereby ensuring the flatness of the end of the battery core after it is wound into a battery core, and avoiding damage problems such as warping when the battery core is inserted into the casing.

[0033] Please see Figure 3As shown, in one embodiment, the anti-damage component 300 is provided with an inclined surface 310, which gradually decreases in inclination from the top surface of the anti-damage component 300 towards the current collector 100. That is, the anti-damage component 300 has a trapezoidal structure. Thus, by using a gradient adhesive paper or polymer coating, the end of the battery core can have a certain inclination, making it easier for the battery core to be inserted into the steel casing, improving the yield rate of battery core insertion into the steel casing and increasing the tightness of the battery core, thereby improving the consistency and energy density of the battery. For example, if the thickness of the single-sided active material layer 200 is 0.15mm-0.4mm, then the corresponding thickness of the anti-damage component 300 is also 0.15mm-0.4mm. When the anti-damage component 300 has a trapezoidal structure, the thickness at the highest point of the anti-damage component 300 is 0.15mm-0.4mm, and the thickness at the lowest point is 0.03mm-0.1mm.

[0034] In one embodiment, the current collector 100 is a three-dimensional metal substrate. For example, the current collector 100 can be a mesh structure, a porous structure, or a burr mesh structure. Please refer to [link / reference]. Figure 4 As shown, the current collector 100 has a porous structure with multiple through holes, each penetrating both sides of the current collector 100. This improves the adhesion between the active material layer 200 and the current collector 100, reduces the risk of the active material layer 200 detaching and shedding powder, and improves the cycle life of the battery.

[0035] A cylindrical battery includes the aforementioned negative electrode 10, a positive electrode, a separator, and a steel casing. The negative electrode 10, separator, and positive electrode are stacked and wound sequentially to form a battery core. The active material removal region 210 is located on the outermost ring of the wound negative electrode 10. The battery core is housed within the steel casing. The separator is primarily made of plastics such as polyethylene and polypropylene, and includes a non-woven fabric separator capable of absorbing alkaline electrolyte and a microporous membrane preventing zinc dendrite penetration. Preferably, the separator thickness is 100-250 μm.

[0036] The embodiments described above are merely illustrative of several implementations of this utility model, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the utility model patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this utility model, and these all fall within the protection scope of this utility model. Therefore, the protection scope of this utility model patent should be determined by the appended claims.

Claims

1. A negative electrode sheet characterized by comprising: The negative electrode sheet comprises: a current collector; an active material layer coated on the current collector, wherein an active material removal area is arranged on the active material layer and located at one end of the current collector; and a damage prevention piece arranged on the side of the active material removal area away from the active material layer, and used to increase the thickness of the negative electrode sheet corresponding to the active material removal area. The area ratio of the damage prevention piece to the active material removal area is 5%-100%.

2. The negative electrode sheet according to claim 1, characterized by The damage prevention piece is adhesive tape attached to the side of the active material removal area away from the active material layer.

3. The negative electrode sheet according to claim 1, characterized by The adhesive tape is alkali-resistant adhesive tape.

4. The negative electrode sheet according to claim 3, characterized by The damage prevention piece is a high polymer coating layer coated on the side of the active material removal area away from the active material layer.

5. The negative electrode sheet according to claim 1, wherein The high polymer coating layer is alkali-resistant high polymer coating layer.

6. The negative electrode sheet according to claim 5, characterized by The current collector is provided with the active material layer on both sides, and the active material removal area is arranged on one of the active material layers and located at one end of the current collector.

7. The negative electrode sheet according to claim 1, wherein The thickness of the damage prevention piece is less than or equal to the thickness of one of the active material layers.

8. The negative electrode sheet according to claim 7, characterized by An inclined surface is arranged on the damage prevention piece, which gradually decreases from the top surface of the damage prevention piece towards the current collector.

9. The negative electrode sheet according to any one of claims 1 to 8, wherein The negative electrode sheet according to any one of claims 1-9, further comprising a positive electrode sheet, a separator and a steel shell, wherein the negative electrode sheet, the separator and the positive electrode sheet are sequentially stacked and wound to form a battery roll core, and the active material removal area is located at the outermost circle of the negative electrode sheet after winding, and the battery roll core is contained in the steel shell.

10. A cylindrical battery, characterized by comprising: ​

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