Pole piece with three-dimensional porous current collector and nickel-zinc battery

Abstract

The utility model discloses a kind of pole piece and nickel-zinc battery with three-dimensional porous current collector, wherein pole piece includes three-dimensional porous current collector, electrolyte active layer and active material layer;Electrolyte active layer is preset on three-dimensional porous current collector;Active material layer is coated on three-dimensional porous current collector;And electrolyte active layer is located between three-dimensional porous current collector and active material layer.Such can make active material close to current collector side more easily obtain ion participating in electrochemical reaction;With the aid of three-dimensional porous current collector's stereoscopic skeleton insertion active material layer, not only can provide more convenient electron transport path for active material close to electrolyte side, but also can improve the adhesion between current collector and active material layer.Such, it can shorten the transmission path of ion and electron in electrochemical process, by improving the transmission efficiency of electric charge, to improve the discharge capacity, rate performance and cycle life of alkaline nickel-zinc battery.

Description

Technical Field

[0001] This utility model relates to the field of battery technology, and in particular to an electrode with a three-dimensional porous current collector and a nickel-zinc battery. Background Technology

[0002] Alkaline nickel-zinc batteries utilize an aqueous alkaline electrolyte, with nickel hydroxide and nano-zinc oxide as the main active materials for the positive and negative electrodes, respectively. They feature high energy density, high power density, excellent charge-discharge performance, high safety, and environmental friendliness, making them promising for widespread application in large-scale energy storage systems, power tools, automotive start-stop power supplies, power supplies for light electric vehicles, emergency power supplies for data centers, medical equipment, smart transportation power supplies, and smart home devices. Currently, the gravimetric energy density of nickel-zinc batteries typically reaches only 60-80 Wh / kg, far lower than that of lithium-ion batteries. Through modification of active materials and optimization of battery electrode structure, the gravimetric energy density of nickel-zinc batteries can reach 120 Wh / kg. Furthermore, nickel-zinc batteries have exceptionally high power density, achieving a 20C discharge rate and releasing over 90% of their capacity within 3 minutes, making them particularly suitable for applications with high power density requirements.

[0003] To further improve the energy density of batteries, nickel-zinc batteries require thicker electrodes compared to lithium-ion batteries, resulting in a significantly higher active material loading and capacity per unit area. Typically, a cylindrical nickel-zinc battery of the same size has far fewer winding layers than a lithium-ion battery. Specifically, because lithium-ion batteries use organic electrolytes with lower ionic conductivity, the positive and negative electrodes are usually thinner, at 120-180 μm and 130-220 μm respectively, with a capacity of approximately 3-5 mAh / cm². From an electrode manufacturing perspective, this can be achieved using a wet coating process. However, nickel-zinc batteries use an aqueous alkaline electrolyte with higher ionic conductivity, allowing for thicker positive and negative electrodes (400-800 μm and 300-600 μm respectively), resulting in a capacity exceeding 10 mAh / cm², and even reaching over 20 mAh / cm². Electrodes can be fabricated using a wet slurry drawing process. Therefore, the design philosophy of nickel-zinc batteries is completely different from that of lithium-ion batteries. The electrodes of nickel-zinc batteries are usually designed to be thicker in order to achieve high capacity per unit area and high quality energy density.

[0004] However, thicker battery electrodes present significant technical drawbacks, hindering further performance improvements in nickel-zinc batteries. On one hand, the adhesion between the active material layer and the traditional planar current collector is poor, increasing the risk of active material layer detachment during charge-discharge cycles and leading to performance degradation. On the other hand, the electrolyte struggles to penetrate the thicker electrode, especially the active material near the current collector. The longer distance ions diffuse from the electrolyte to this region during electrochemical reactions significantly increases ion transport resistance, hindering rate improvements. Simultaneously, electrons generated by the electrochemical reaction are difficult to efficiently transfer from the surface of the active material near the electrolyte to the current collector, resulting in uneven charge transport across different locations. This prevents some active material from fully participating in the reaction, severely impacting the utilization rate of the active material and overall battery performance, particularly discharge capacity, rate performance, and cycle life. Utility Model Content

[0005] The purpose of this invention is to overcome the shortcomings of the prior art and provide an electrode with a three-dimensional porous current collector, thereby improving the electron and ion transport capabilities of the electrode and enhancing the charge and discharge capacity, rate performance, and cycle life of nickel-zinc batteries.

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

[0007] An electrode with a three-dimensional porous current collector includes: a three-dimensional porous current collector, an electrolyte active layer, and an active material layer; the electrolyte active layer is pre-embedded on the three-dimensional porous current collector; the active material layer is coated on the three-dimensional porous current collector; and the electrolyte active layer is located between the three-dimensional porous current collector and the active material layer.

[0008] In one embodiment, the three-dimensional porous current collector has a pore structure, and the electrolyte active layer is pre-set within the pore structure and on the surface of the three-dimensional porous current collector.

[0009] In one embodiment, the three-dimensional porous current collector forms the pore structure through a chemical etching process or a laser engraving process.

[0010] In one embodiment, the porosity of the pore structure in the three-dimensional porous current collector is 35-60%.

[0011] In one embodiment, the surface of the three-dimensional porous current collector is further provided with a corrosion-resistant protective layer, which is located between the three-dimensional porous current collector and the electrolyte active layer.

[0012] In one embodiment, the corrosion-resistant protective layer is a tin-plated layer, a bismuth-plated layer, a zinc-plated layer, or an indium-plated layer.

[0013] In one embodiment, the thickness of the corrosion-resistant protective layer is 0.5-3 μm.

[0014] In one embodiment, the electrolyte active layer includes an electrolyte and an adhesion enhancement structure disposed at the contact interface between the electrolyte and the three-dimensional porous current collector.

[0015] In one embodiment, the three-dimensional porous current collector is further provided with a perforated structure.

[0016] A nickel-zinc battery includes the aforementioned electrode with a three-dimensional porous current collector, wherein the electrode is combined with a separator to form a battery cell, and the nickel-zinc battery also includes a housing, wherein the battery cell is placed inside the housing.

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

[0018] 1. The electrode with a three-dimensional porous current collector of this utility model pre-positions the electrolyte active layer between the three-dimensional porous current collector and the active material layer. This is equivalent to pre-storing an ion reservoir on the side of the active material layer near the three-dimensional porous current collector. It does not require the external electrolyte to slowly permeate from the outer surface of the active material layer. This allows the active material near the current collector to directly obtain ions from the electrolyte active layer, thereby shortening the ion transport distance and resistance. It also prevents the inner active material of the thick electrode from being unable to participate in the electrochemical reaction due to "insufficient ion supply", thereby improving ion transport efficiency and reaction balance, and thus improving the charge and discharge capacity and rate performance of the nickel-zinc battery.

[0019] 2. The electrode with a three-dimensional porous current collector of this utility model replaces the traditional planar current collector with a three-dimensional porous current collector. Its porous characteristics can not only provide sufficient pre-storage space for the electrolyte active layer, but also greatly improve the interfacial adhesion between the current collector and the active material layer, reduce the risk of the active material layer falling off during charge and discharge cycles, and thus improve the cycle life of nickel-zinc batteries.

[0020] 3. The electrode with a three-dimensional porous current collector of this utility model replaces the traditional planar current collector with a three-dimensional porous current collector, so that the protruding part of the three-dimensional porous current collector can be inserted into the active material layer, which greatly shortens the electron transport path from the active material layer near the electrolyte side to the current collector and improves the electron transport efficiency. At the same time, with the electrolyte active layer pre-set on the current collector, the electron and ion transport capabilities of the electrode are greatly improved, so that the active material layer is fully utilized and the charge and discharge capacity, rate performance and cycle life of nickel-zinc batteries are improved.

[0021] 4. The electrode with three-dimensional porous current collector of this utility model improves the corrosion resistance and suppresses electrochemical side reactions of the three-dimensional porous current collector by setting a tin plating layer, bismuth plating layer, zinc plating layer or indium plating layer on the surface of the three-dimensional porous current collector, and ensures that the current collector has good stability in alkaline environment through the plating layer. Attached Figure Description

[0022] 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.

[0023] Figure 1 This is a schematic diagram of the planar structure of a three-dimensional porous current collector in one embodiment of the present invention;

[0024] Figure 2 This is a schematic diagram of the cross-sectional structure of a three-dimensional porous current collector in one embodiment of the present invention;

[0025] Figure 3 This is a schematic diagram of the stacked structure of an electrode sheet with a three-dimensional porous current collector in one embodiment of the present invention;

[0026] Figure 4 for Figure 3 A magnified schematic diagram of the structure at point A of the electrode with a three-dimensional porous current collector;

[0027] Figure 5 This is a schematic diagram of the cross-sectional structure of a three-dimensional porous current collector with a perforated structure in another embodiment of the present invention;

[0028] Figure 6 for Figure 5 A schematic diagram of the cross-sectional structure of a three-dimensional porous current collector with pore and perforated structures. Detailed Implementation

[0029] 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.

[0030] Please see Figure 1 , Figure 2 , Figure 3 and Figure 4 As shown, an electrode 10 with a three-dimensional porous current collector includes: a three-dimensional porous current collector 100, an electrolyte active layer 200, and an active material layer 300; the electrolyte active layer 200 is pre-set on the three-dimensional porous current collector 100; the active material layer 300 is coated on the three-dimensional porous current collector 100; and the electrolyte active layer 200 is located between the three-dimensional porous current collector 100 and the active material layer 300.

[0031] It should be noted that, taking alkaline nickel-zinc batteries as an example, compared to the common lithium-ion battery electrode 10, the alkaline nickel-zinc battery electrode is thicker, resulting in a much higher load of active material per unit area and a much higher capacity per unit area than lithium-ion batteries. However, the thicker battery electrode has three core problems: poor adhesion between the active material and the traditional planar current collector, leading to the risk of powder shedding during charging and discharging; difficulty for the electrolyte to penetrate into the inner layer of the electrode, resulting in a long ion transport distance; and uneven charge transport, leading to low utilization of the active material. Therefore, in this utility model, a structure of "three-dimensional porous current collector 100 + electrolyte active layer 200 + active material layer 300" is used to solve the above technical problems.

[0032] Specifically, to address the problem of "poor adhesion between the active material layer 300 and the traditional planar current collector, leading to the risk of powder detachment during charging and discharging," a three-dimensional porous current collector 100 is used instead of the traditional planar current collector. Utilizing the porous characteristics of the three-dimensional porous current collector 100, the interfacial bonding between the active material layer 300 and the current collector is enhanced, reducing the risk of powder detachment during charge-discharge cycles and thus improving the cycle life of the nickel-zinc battery. It also provides a larger pre-storage space for the electrolyte. To address the problem of "difficulty in electrolyte penetration into the inner layer of the electrode, resulting in long ion transport distances," this invention pre-positions the electrolyte active layer 200 between the current collector and the active material, effectively pre-storing... This "inner layer ion direct supply channel" of the electrode differs from traditional electrodes 10, which rely on external electrolyte to penetrate from the surface to the depth. The inner layer active material near the current collector can directly obtain ions from the adjacent electrolyte active layer 200 without long-distance migration, reducing ion transport resistance and ensuring that the inner layer active material of the electrode can also obtain ions in time to participate in the reaction during charging and discharging, thereby improving the charge and discharge rate of the nickel-zinc battery. Regarding the problem of "uneven charge transport and low utilization of active materials", since the nickel-zinc battery electrode 10 is relatively thick, that is, the active material layer 300 is relatively thick, if a traditional planar current collector is used, it is difficult for electrons in the electrochemical reaction to be transported from the surface of the active material layer 300 near the electrolyte to the current collector. Therefore, in this invention, by employing a three-dimensional porous current collector 100, the porous nature of the current collector allows the protruding areas to be inserted into the active material layer 300. This shortens the distance between the current collector and the surface of the active material layer 300 near the electrolyte, effectively providing a shortcut for electrons to reach the active material layer 300 near the electrolyte, significantly reducing the electron transport path and improving electron transport efficiency. Thus, by combining the three-dimensional porous current collector 100 with the pre-stored electrolyte active layer 200, the charge transport of the active material becomes more balanced, ensuring that the active material at different locations can fully participate in the electrochemical reaction, improving the utilization rate of the active material and the overall battery performance, and enhancing the discharge capacity, rate performance, and cycle life of the electrode 10. In this embodiment, the active material layer 300 is typically disposed on both sides of the three-dimensional porous current collector 100, so the corresponding electrolyte active layer 200 also has two sides. See the attached document for details. Figure 3 As shown.

[0033] Furthermore, the three-dimensional porous current collector 100 has a pore structure 110, and the electrolyte active layer 200 is preset in the pore structure 110 and on the surface of the three-dimensional porous current collector 100.

[0034] It should be specifically noted that for alkaline nickel-zinc batteries, the electrolyte active layer 200 is composed of alkaline active materials such as sodium hydroxide, potassium hydroxide, and lithium hydroxide. The electrolyte active layer 200 can then be pre-attached to the three-dimensional porous current collector 100 using methods such as impregnation or ultrasonic spraying. Taking impregnation as an example, the three-dimensional porous current collector 100 is immersed in the electrolyte active layer 200 slurry, held under negative pressure for a period of time, with controlled lifting speed, followed by vacuum drying and curing. This allows the electrolyte active layer 200 to adhere to the surface or pore structure 110 of the three-dimensional porous current collector 100. This not only improves the ion diffusion efficiency within the electrode but also increases the electrolyte loading.

[0035] Furthermore, the three-dimensional porous current collector 100 forms a porous structure 110 through a chemical etching process or a laser engraving process.

[0036] It should be noted that whether chemical etching or laser engraving is used, the purpose is to form an uneven, three-dimensional structure on the surface of the current collector. In this embodiment, the three-dimensional porous current collector 100 is a three-dimensional porous copper current collector, a three-dimensional porous zinc current collector, or a three-dimensional porous zinc alloy current collector. Taking the three-dimensional porous copper current collector as an example, using chemical etching, the current collector substrate can be a zinc-copper alloy substrate. Utilizing the difference in corrosion rates between copper and zinc in the zinc-copper alloy substrate, zinc is selectively dissolved in an acidic mixture, thereby forming pores on the surface of the current collector, resulting in an uneven, three-dimensional porous structure, which is the three-dimensional porous copper current collector. If laser engraving is used, a copper substrate can be used. A fiber laser is used to locally ablate the copper substrate, and pores are processed on the surface of the copper substrate according to a preset pattern, thereby enabling more precise control over the size and distribution of the pores. Thus, the porous structure on the three-dimensional porous current collector 100 not only allows for the pre-storage of the electrolyte active layer 200, but also enhances the bonding strength between the active material layer 300 and the current collector, and further improves the electron transport efficiency of the active material layer 300 near the electrolyte side. Furthermore, the porous structure 110 formed in the above manner is a three-dimensional interconnected porous structure, which not only significantly improves the interfacial bonding strength between the active material layer 300 and the current collector, but also significantly enhances the ion transport efficiency.

[0037] In one embodiment, the porosity of the pore structure 110 on the three-dimensional porous current collector 100 is 35-60%. Porosity, also known as the pore ratio on the three-dimensional porous current collector, is key to balancing charge transport efficiency and current collector mechanical strength. Insufficient porosity not only reduces the electrolyte loading but also decreases electron transport efficiency; however, excessive porosity leads to a sparse current collector framework, insufficient mechanical strength, and susceptibility to deformation during processing, making it unable to support the thick active material layer 300, and potentially causing electrode breakage in severe cases. Therefore, a porosity of 35-60% is preferred.

[0038] In another implementation, please refer to Figure 5 and Figure 6 As shown, the three-dimensional porous current collector 100 is also provided with a perforated structure 100a. That is, before processing the porous structure 110, the current collector substrate is first mechanically punched to form through holes in the current collector substrate. For example, the punching structure 100a includes multiple through holes arranged in an array with the same spacing. The punching structure 100a is provided on both sides of the current collector substrate, so that the current collector substrate has a better three-dimensional effect. At the same time, in conjunction with the porous structure 110, the three-dimensional porous current collector 100 has a larger surface area and can accommodate more active materials and electrolytes. That is, it is not only beneficial to increase the loading of the electrolyte active layer 200 and reduce the risk of the electrolyte active layer 200 falling off, but also more beneficial to the coating of the active material layer 300, ensuring that the three-dimensional porous current collector 100 can be coated with a thicker active material. At the same time, it improves the adhesion of the active material layer 300 and reduces the risk of the active material layer 300 falling off and shedding powder during charge and discharge cycles. This makes it easier to prepare electrodes with thicker active material layers, thereby improving the charge and discharge performance, rate performance and cycle stability of the battery.

[0039] Please see Figure 3 As shown, in one embodiment, the surface of the three-dimensional porous current collector 100 is further provided with a corrosion-resistant protective layer 120, which is located between the three-dimensional porous current collector 100 and the electrolyte active layer 200.

[0040] It should be noted that the copper current collector in alkaline nickel-zinc batteries is susceptible to corrosion by alkaline electrolytes. Therefore, a corrosion-resistant protective layer 120 is plated between the electrolyte active layer 200 and the active material layer 300 to isolate the current collector from direct contact with the electrolyte or the electrolyte active layer 200, thus providing corrosion protection. For example, in this embodiment, the corrosion-resistant protective layer is a tin plating layer, a bismuth plating layer, a zinc plating layer, or an indium plating layer. Taking a tin plating layer as an example, tin forms a dense oxide film in the alkaline electrolyte, isolating the copper substrate from direct contact with the electrolyte or the electrolyte active layer 200, thereby providing corrosion protection for the current collector. Furthermore, tin plating, bismuth plating, zinc plating, or indium plating all possess conductivity, do not hinder electron transport, and also suppress electrochemical gas evolution side reactions. Thus, not only is electron transport between the active material layer 300 and the current collector not hindered, but corrosion resistance and conductivity are also achieved, significantly improving corrosion resistance. Preferably, the thickness of the tin plating layer 120 is 0.5-3 μm. For example, when the tin plating layer 120 is 3 μm, the plating layer does not affect the filling efficiency of the electrolyte active layer 200 and the electron transport efficiency.

[0041] In one embodiment, the electrolyte active layer 200 includes an electrolyte and an adhesion enhancement structure disposed at the interface between the electrolyte and the three-dimensional porous current collector 100. Thus, by providing the adhesion enhancement structure, the bonding force between the electrolyte and the three-dimensional porous current collector 100 can be improved, ensuring the stability of the electrolyte and reducing the risk of electrolyte detachment during electrode processing. Simultaneously, it can also ensure the electrolyte retention rate during long-term charge-discharge cycles, preventing electrolyte loss and insufficient ion supply to the active material, and ensuring the continuous stability of the electrochemical reaction. For example, in this embodiment, the adhesion enhancement structure is an aqueous binder or thickener. When pre-storing the electrolyte, the electrolyte is mixed with the aqueous binder or thickener, and then disposed on the three-dimensional porous current collector 100 by impregnation or ultrasonic spraying to improve the adhesion strength at the interface between the electrolyte active layer 200 and the three-dimensional porous current collector 100. For example, the aqueous binder or thickener can be a substance with good alkali resistance, such as sodium carboxymethyl cellulose, guar gum, polyacrylic acid, styrene-butadiene rubber, hydroxypropyl methylcellulose, sodium alginate, or chitosan.

[0042] In another embodiment, because the electrolyte material in the electrolyte active layer 200 is sometimes consumed and sometimes generated in large quantities during the charging and discharging process, resulting in large fluctuations in the electrolyte concentration within the system, it is necessary to load the electrolyte material onto a carrier with a high specific surface area and alkali resistance. The carrier adsorbs and stores the pre-existing electrolyte material; that is, the carrier acts as a medium for storing the electrolyte, allowing it to be pre-stored on the surface of the current collector. For example, when the electrolyte is consumed or insufficient, the carrier releases and replenishes the electrolyte; conversely, when a large amount of electrolyte is generated, the carrier adsorbs and stores the excess electrolyte to maintain the electrolyte concentration balance within the battery. Such a high specific surface area and alkali-resistant carrier can be magnesium oxide, titanium oxide, zirconium oxide, cerium oxide, hydrotalcite, activated carbon, carbon nanotubes, boron nitride, etc.

[0043] A nickel-zinc battery includes an electrode 10 with a three-dimensional porous current collector, as described above. The electrode 10, together with a separator, forms a battery cell. The nickel-zinc battery also includes a casing, in which the battery cell is placed. For alkaline nickel-zinc batteries, the current collector substrates for the positive and negative electrodes are different. When the electrode 10 with a three-dimensional porous current collector is applied to the positive electrode 10, the current collector substrate is a metallic nickel substrate; while when the electrode 10 with a three-dimensional porous current collector is applied to the negative electrode 10, the current collector substrate is a metallic copper substrate. The above description mainly focuses on the negative electrode 10. The positive electrode 10, separator, and negative electrode 10 are stacked and wound to form a battery cell, which is then placed inside a cylindrical casing.

[0044] Taking an alkaline nickel-zinc battery as an example, after preparing a three-dimensional porous current collector 100 containing an electrolyte active layer 200 using the above method, a slurry containing nano-zinc oxide, metallic zinc powder, bismuth oxide, indium oxide, aluminum oxide, binder, thickener, and other substances is uniformly coated onto the surface of the three-dimensional porous current collector 100 containing the electrolyte active layer 200. After drying, rolling, slicing, and other processes, the negative electrode sheet 10 of the nickel-zinc battery can be obtained. Alternatively, after preparing a three-dimensional porous current collector 100 containing an electrolyte active layer 200 using the above method, a slurry containing spherical nickel hydroxide, metallic nickel powder, yttrium oxide, tungsten oxide, zinc oxide, binder, thickener, and other substances is uniformly coated onto the surface of the three-dimensional porous current collector 100 containing the electrolyte active layer 200. After drying, rolling, slicing, welding, and other processes, the positive electrode sheet 10 of the nickel-zinc battery can be obtained.

[0045] 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 pole piece having a three-dimensional porous current collector, characterized by, include: Three-dimensional porous current collector; An electrolyte active layer is pre-installed on the three-dimensional porous current collector; and An active material layer is coated on the three-dimensional porous current collector; Furthermore, the electrolyte active layer is located between the three-dimensional porous current collector and the active material layer.

2. The pole piece having a three-dimensional porous current collector of claim 1, wherein, The three-dimensional porous current collector has a porous structure, and the electrolyte active layer is pre-set within the porous structure and on the surface of the three-dimensional porous current collector.

3. The pole piece having a three-dimensional porous current collector of claim 2, wherein, The three-dimensional porous current collector forms the pore structure through chemical etching or laser engraving processes.

4. The pole piece having a three-dimensional porous current collector of claim 3, wherein, The porosity of the pore structure in the three-dimensional porous current collector is 35-60%.

5. The pole piece having a three-dimensional porous current collector of claim 1, wherein, The surface of the three-dimensional porous current collector is also provided with a corrosion-resistant protective layer, which is located between the three-dimensional porous current collector and the electrolyte active layer.

6. The pole piece having a three-dimensional porous current collector of claim 5, wherein, The corrosion-resistant protective layer is a tin-plated layer, a bismuth-plated layer, a zinc-plated layer, or an indium-plated layer.

7. The pole piece having a three-dimensional porous current collector of claim 5, wherein, The thickness of the corrosion-resistant protective layer is 0.5-3 μm.

8. The pole piece having a three-dimensional porous current collector of any one of claims 1-7, wherein, The electrolyte active layer includes an electrolyte and an adhesion enhancement structure disposed at the contact interface between the electrolyte and the three-dimensional porous current collector.

9. The pole piece having a three-dimensional porous current collector of any one of claims 1-7, wherein, The three-dimensional porous current collector is also provided with a perforated structure.

10. A nickel-zinc battery, characterized by The battery includes an electrode with a three-dimensional porous current collector as described in any one of claims 1-9, wherein the electrode is combined with a separator to form a battery cell, and the nickel-zinc battery further includes a housing, wherein the battery cell is placed inside the housing.

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