Preparation method of zinc-nickel secondary battery negative electrode modified by calcium zincate

Abstract

The invention belongs to the technical field of batteries, and particularly relates to a preparation method of a calcium zincate modified zinc-nickel secondary battery negative electrode. The negative electrode slurry is prepared by mixing a solid negative electrode active substance zinc oxide, Zn powder, a negative electrode additive calcium zincate and bismuth oxide, a carbon material, a surfactant and an adhesive according to a certain proportion. The solid-phase sheet preparation process of the negative electrode can significantly improve the conductivity of the negative electrode and growth of zinc dendrites. And the double-sided laminated solid-phase negative electrode can better control the load of the negative electrode active material, and ensure the current collection uniformity and the stability of the negative electrode. And the tin-plated cable-stayed net with high conductivity is selected as a substrate material, so that a three-dimensional conductive frame can be constructed in the negative electrode, the utilization rate of active substances is higher, and the structural stability of the pole piece is enhanced. In addition, the high-conductivity carbon material and the organic framework have a synergistic effect to construct an ion-electron mixed conductive framework, so that the capacity and the stability of the pole piece are improved.

Description

Technical Field

[0001] This invention belongs to the field of battery technology, and specifically relates to a method for preparing a zinc-nickel secondary battery negative electrode modified with calcium zincate. Background Technology

[0002] Zinc-nickel rechargeable batteries, as a promising energy storage technology, have received widespread attention in recent years. With increasing global energy demand and a growing emphasis on environmental protection and sustainable development, traditional lead-acid and lithium-ion batteries have gradually revealed their shortcomings in terms of cost, safety, and resource consumption. Therefore, finding alternatives has become an important direction in energy storage technology research. Zinc-nickel batteries, utilizing zinc and nickel—two abundant and relatively inexpensive materials—offer strong environmental and cost advantages, making them a strong candidate to replace traditional battery systems. Compared to lead-acid batteries, zinc-nickel rechargeable batteries not only provide higher energy density and longer cycle life but also do not produce harmful substances during use, avoiding the environmental pollution problems common with lead-acid batteries. Furthermore, zinc, as a relatively abundant metal on Earth, offers a more stable resource supply compared to rare metals like cobalt and nickel used in lithium batteries. More importantly, zinc-nickel batteries have better safety, are less prone to thermal runaway during charging and discharging, and are suitable for applications with high safety requirements. However, despite their promising potential, zinc-nickel batteries still face some pressing technical challenges in practical applications.

[0003] First, zinc dendrite growth is a major problem for zinc anodes during charge and discharge. These dendrites can cause internal short circuits, affecting battery stability and lifespan. Second, corrosion and dissolution of the zinc anode also lead to capacity decay, limiting its ability to operate stably for extended periods. Third, although zinc-nickel batteries have a high theoretical energy density, their energy efficiency is low at high charge / discharge rates, and their relatively large size and weight make them less competitive in applications requiring high energy density and lightweight design. Furthermore, zinc-nickel batteries exhibit poor low-temperature performance, limiting their application in cold regions.

[0004] Therefore, improving the overall performance of zinc-nickel rechargeable batteries, especially addressing challenges related to zinc dendrite growth, zinc dissolution corrosion, energy efficiency, and low-temperature performance, has become a key research focus. Future research will likely concentrate on optimizing battery design, improving electrolyte formulations, and developing novel anode materials to overcome these technical bottlenecks and further enhance the overall performance of zinc-nickel batteries, enabling them to have broader application prospects in energy storage, electronic devices, and electric vehicles. In summary, although zinc-nickel batteries still have shortcomings in current technological applications, their advantages in safety, environmental friendliness, and cost-effectiveness give them enormous development potential in future energy storage technologies. Summary of the Invention

[0005] In order to overcome the shortcomings and deficiencies of zinc-nickel batteries, the present invention aims to provide a method for preparing a zinc-nickel secondary battery anode modified with calcium zincate, which can significantly improve the conductivity of the anode and control the growth of zinc dendrites.

[0006] The objective of this invention is achieved through the following solution: A method for preparing a zinc-nickel secondary battery negative electrode modified with calcium zincate includes the following steps: Step (1): Negative electrode dry powder mixing: Zinc oxide and negative electrode additives are thoroughly mixed to obtain negative electrode mixed powder. Zinc powder and carbon material are mixed evenly to obtain negative electrode conductive powder. The two powders are then mixed evenly to obtain negative electrode powder, wherein the negative electrode additives are calcium zincate and bismuth oxide. Step (2): Preparation of negative electrode powder: Mix the negative electrode dry powder with ethanol evenly, then add PTFE emulsion and SBR emulsion to obtain a slurry, and finally stir the slurry until the powder is fibrous to obtain negative electrode powder; Step (3): Fabrication of negative electrode film: Repeatedly fold and roll the negative electrode powder to press out the negative electrode film; Step (4): Preparation of zinc-nickel battery negative electrode: The negative electrode film is prepared by bonding, rolling, drying, cutting, welding the extended tabs and coating the separator.

[0007] The mass ratio of zinc oxide to negative electrode additive in step (1) is 60~85:10~40, preferably 60~70:10~20; The mass ratio of calcium zincate to bismuth oxide in step (1) is 10~35:0.05~2, preferably 25~35:1; more preferably 28~30:1.

[0008] The mass ratio of zinc oxide to zinc powder in step (1) is 60~85:8~15, preferably 60~70:10~14; The mass ratio of zinc powder to carbon material in step (1) is 8~15:1~5, preferably 10~15:1.5~4; The carbon material in step (1) is micron-sized graphite particles KS-6 and nano-sized carbon black. The two materials fill the spaces between the electrode active materials to form a continuous conductive network, which together enhances the conductivity and stability of the electrode. Preferably, the mass ratio of the micron-sized graphite particles KS-6 to the nano-sized carbon black is 0.5~5:1, and more preferably 1:1.

[0009] The PTFE solid content in the PTFE emulsion in step (2) is 50% to 70%, preferably 60%; The SBR emulsion mentioned in step (2) has an SBR solid content of 50% to 70%, preferably 60%; In step (2), the mass ratio of zinc oxide to ethanol, PTFE emulsion and SBR emulsion in the negative electrode dry powder is 60-85:15-30:10~30:1~5, preferably 60~70:18~28:15~30:1~3.

[0010] Preferably, the stirring speed for uniform mixing in step (2) is 600-800 r / min.

[0011] Preferably, the stirring speed when adding PTFE emulsion and SBR emulsion in step (2) is 5~30 r / s; more preferably, PTFE emulsion and SBR emulsion are added by the following steps: adding PTFE emulsion and SBR emulsion at 5 r / s and rotating in the same direction, and mixing for 1 minute; then increasing the speed to 15 r / s and rotating in the same direction for 2 minutes; then maintaining 20 r / s and rotating in the same direction, and continuing to mix for 10 minutes; continuing to mix the mixture at 30 r / s and rotating in the same direction for 10 minutes.

[0012] Preferably, each solid raw material in step (2) is sieved through a 200-mesh sieve before use.

[0013] Preferably, step (3) involves repeatedly folding and pressing the negative electrode powder with a tabletop noodle press, and then pressing it into a negative electrode sheet using a 50T double roller press. More preferably, the specific steps are as follows: First, adjust the gap between the two rollers of the tabletop noodle press to 0.8mm, repeatedly fold and press the solid material to ensure that the sheet thickness is 1mm, and then adjust the gap between the rollers of the 50T double roller press to 0.15mm to press out a 0.3mm solid negative electrode sheet.

[0014] As a preferred embodiment, the specific steps of step (4) are as follows: First, the negative electrode film is cut to the same size as the tin-plated inclined copper mesh. Then, the tin-plated inclined mesh is placed between two negative electrode films and pressed together by rollers with a gap of 0.3 mm to obtain a solid negative electrode sheet of 0.45 mm. The solid negative electrode sheet is then dried at a temperature of 80~120℃ for 1 to 4 hours, and then rolled twice by a roller press to obtain the negative electrode sheet. The negative electrode sheet is cut into a specific shape and size, and the nickel extension tab with tab adhesive is welded to the cut trapezoidal tab position. A layer of PP separator is wrapped around the negative electrode sheet to ensure that the separator completely covers the reaction surface of the electrode sheet, and finally the negative electrode of the zinc-nickel battery is obtained.

[0015] A zinc-nickel battery, comprising a zinc-nickel battery negative electrode prepared by the above method.

[0016] The beneficial effects of this invention are as follows: The negative electrode slurry of this invention is composed of solid negative electrode active materials zinc oxide and Zn powder, negative electrode additives calcium zincate and bismuth oxide, carbon materials, surfactants, and binders mixed in a certain proportion. The solid-phase sheeting process of the negative electrode can significantly improve the conductivity of the negative electrode and the growth of zinc dendrites. Double-sided bonding of the solid-phase negative electrode better controls the loading of the negative electrode active materials, ensuring the uniformity of current collection and guaranteeing the stability of the negative electrode. Using a highly conductive tin-plated inclined wire mesh as the substrate material helps to construct a three-dimensional conductive framework in the negative electrode, resulting in higher utilization of the active materials and enhanced structural stability of the electrode sheet. Furthermore, the highly conductive carbon material works synergistically with the organic framework to construct an ion-electron hybrid conductive framework, thereby improving the capacity and stability of the electrode sheet. Attached Figure Description

[0017] Figure 1 This is a graph showing the relationship between the charge / discharge specific capacity and coulombic efficiency of the zinc-nickel secondary batteries prepared in Example 1 and Comparative Example 1 of the present invention, and the cycle number.

[0018] Figure 2 The charge-discharge curves of the zinc-nickel secondary battery prepared in Example 1 of this invention are shown. Detailed Implementation

[0019] To facilitate understanding of the present invention, a more complete description will be given below with reference to the accompanying drawings. Preferred embodiments of the invention are shown in the drawings. However, the invention can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to provide a thorough and complete understanding of the disclosure of the invention.

[0020] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein in the description of the invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0021] Example 1: A dry-process negative electrode for zinc-nickel batteries comprises the following components in parts by weight: 65 parts of pharmaceutical-grade zinc oxide as the negative electrode active material, 12 parts of Zn powder (500 mesh or finer), and the following negative electrode additives: 14.5 parts of calcium zincate, 0.5 parts of bismuth oxide, 2 parts of carbon material (a combination of KS-6 and nano-grade carbon black in a mass ratio of 1:1), 20 parts of a 60% PTFE aqueous solution and 2 parts of a 60% SBR emulsion as binders, and 27 parts of ethanol (industrial-grade anhydrous ethanol).

[0022] The dry electrode process, which includes dry powder mixing and PTFE pre-fiberization, calendering to form a film, and lamination to prepare the electrode, consists of the following steps: Step 1: Negative electrode dry powder mixing: The negative electrode active material and negative electrode additive are thoroughly mixed to obtain negative electrode mixed powder. Then, zinc powder and carbon material are also premixed evenly to obtain negative electrode conductive powder. The two powders are then put into a dry powder mixer and mixed evenly to obtain negative electrode powder. Step 2: Add ethanol to the negative electrode powder and stir, mixing at high speed (5 r / s) in the opposite direction for 15 minutes. This breaks up the agglomerates of carbon-carbon materials and ensures that they are evenly coated on the surface of the active material particles.

[0023] Step 3: Add binder: At room temperature (25°C), add the PTFE emulsion at a low speed (5 r / s) in the same direction and mix for 1 minute. Introduce the PTFE emulsion into the system so that it initially adheres to the surface of the active material coated with carbon black, avoiding immediate and severe fibrosis.

[0024] Step 4: Preliminary fiberization: Increase the rotation speed to high speed (15 r / s) and mix in the same direction for 2 minutes. Apply strong shear force to begin stretching the PTFE particles and forming a preliminary fiber network.

[0025] Step 5: Deep Fiberization: Maintain high speed (20 r / s) and co-rotation, and continue mixing for 10 minutes. This allows the PTFE to fully fiberize, forming a strong, continuous three-dimensional fiber network that firmly "nets" all active materials and conductive agent particles within it.

[0026] Step 6: High-speed homogenization: The mixture is rotated in the same direction at high speed (30 r / s) for 10 minutes. This further breaks up any large agglomerates that may have formed during the fiberization process, resulting in a homogeneous mixed powder for calendering.

[0027] Step 7: Negative Electrode Formation: After PTFE fiberization, the mixture needs to be pressed into a self-supporting electrode film. As the rolling process proceeds, ethanol evaporates and the electrode thickness continuously decreases. This is the basic purpose of rolling. Finally, the electrode is laminated, that is, the above-mentioned self-supporting electrode film is pressed onto the current collector. After rolling, the negative electrode sheet is obtained. Specifically, the gap between the two rollers of the benchtop press is first adjusted to 0.8mm, and the solid material is repeatedly folded and rolled to ensure that the thickness of the sheet is 1mm. Then, the gap between the rollers of the 50T double-roll press is adjusted to 0.15mm to press out a 0.3mm dry negative electrode sheet.

[0028] Step 8: Negative Electrode Preparation: First, cut the negative electrode film to the same size as the tin-plated inclined copper mesh. Then, place the tin-plated inclined mesh between two negative electrode films and press them together with rollers with a gap of 0.3mm to obtain a 0.45mm dry negative electrode sheet. Next, dry the dry negative electrode sheet at a temperature of 80~120℃ for 1 to 4 hours, and then roll it twice through a roller press to obtain the negative electrode sheet. Then, cut it to a size of 9.4cm×7.7cm and cut out the tab shape. Then, use a spot welding machine to weld the nickel extension tab with tab adhesive to the tab on the top of the electrode sheet. Finally, wrap a layer of PP separator around the negative electrode sheet to fully cover the reaction surface area of ​​the electrode sheet to obtain the zinc-nickel battery dry negative electrode.

[0029] The prepared negative electrode was assembled with a commercial positive electrode (conventional FC09-Ⅲ cobalt-coated spherical nickel hydroxide positive electrode) to form a zinc-nickel battery. The activation process involved constant current charging at 0.2C for 6 hours and constant current discharging at 0.2C to 1.2V, repeated 3 times. The cycle test involved constant current charging at 0.2C for 6 hours and constant current discharging at 0.2C to 1.4V.

[0030] The prepared negative electrode had a loading of 110.5 mg / cm2, and the assembled full cell had a discharge specific capacity of 425 mAh / g.

[0031] Examples 2-7 The difference between Examples 2-7 and Example 1 is that the proportion of calcium zincate added is 1%, 2%, 3%, 10%, 20%, and 30%, respectively.

[0032] Comparative Example 1 The difference from Example 1 is that the negative electrode uses a commercial sample (Chilwee AA zinc oxide negative electrode) and is assembled with a commercial positive electrode to form a zinc-nickel battery.

[0033] Table 1 Comparison of negative electrode performance between Example 1 and Comparative Example 1

[0034] Table 2 Negative electrode performance of Examples 2-7

[0035] Table 3 Data on the negative electrode charge-discharge platform of Examples 2-7

[0036] Figure 1 The graph shows the relationship between the charge / discharge specific capacity and coulombic efficiency of the zinc-nickel secondary batteries prepared in Example 1 and Comparative Example 1 as a function of cycle number. It can be seen that Example 1 is significantly better than Comparative Example 1, with higher coulombic efficiency and significantly better capacity retention.

[0037] Figure 2 The graph shows the charge-discharge curves of the zinc-nickel secondary battery prepared in Example 1. As can be seen from the graph, the median discharge voltage of the negative electrode of the zinc-nickel secondary battery modified with calcium zincate is 1.75V~1.8V, significantly higher than the discharge plateau of commercial zinc-nickel secondary batteries. This indicates that the battery modified with calcium zincate has a higher energy density.

[0038] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of this invention patent should be determined by the appended claims.

Claims

1. A method for preparing a zinc-nickel secondary battery negative electrode modified with calcium zincate, characterized in that... Includes the following steps: Step (1): Negative electrode dry powder mixing: Zinc oxide and negative electrode additives are thoroughly mixed to obtain negative electrode mixed powder. Zinc powder and carbon material are mixed evenly to obtain negative electrode conductive powder. The two powders are then mixed evenly to obtain negative electrode powder, wherein the negative electrode additives are calcium zincate and bismuth oxide. Step (2): Preparation of negative electrode powder: Mix the negative electrode dry powder with ethanol evenly, then add PTFE emulsion and SBR emulsion to obtain a slurry, and finally stir the slurry until the powder is fibrous to obtain negative electrode powder; Step (3): Fabrication of negative electrode film: Repeatedly fold and roll the negative electrode powder to press out the negative electrode film; Step (4): Preparation of zinc-nickel battery negative electrode: The negative electrode film is prepared by bonding, rolling, drying, cutting, welding the extended tabs and coating the separator.

2. The preparation method according to claim 1, characterized in that: The mass ratio of zinc oxide to negative electrode additive in step (1) is 60-85:10~40; the mass ratio of calcium zincate to bismuth oxide in step (1) is 10-35:0.05-2.

3. The preparation method according to claim 1, characterized in that: The mass ratio of zinc oxide to negative electrode additive in step (1) is 60~70:10~20; the mass ratio of calcium zincate to bismuth oxide in step (1) is 25~35:

1.

4. The preparation method according to claim 1, characterized in that: The mass ratio of zinc oxide to zinc powder in step (1) is 60~85:8~15; the mass ratio of zinc powder to carbon material in step (1) is 8~15:1~5.

5. The preparation method according to claim 1, characterized in that: The mass ratio of zinc oxide to zinc powder in step (1) is 60~70:10~14; the mass ratio of zinc powder to carbon material in step (1) is 10~15:1.5~4.

6. The preparation method according to claim 1, characterized in that: The carbon material in step (1) is micron-sized graphite particles KS-6 and nano-sized carbon black; the mass ratio of the micron-sized graphite particles KS-6 and nano-sized carbon black is 0.5~5:1; the PTFE emulsion in step (2) has a PTFE solid content of 50%~70%; the SBR emulsion in step (2) has an SBR solid content of 50%~70%.

7. The preparation method according to claim 1, characterized in that: In step (2), the mass ratio of zinc oxide to ethanol, PTFE emulsion and SBR emulsion in the negative electrode dry powder is 60-85:15-30:10-30:1-5.

8. The preparation method according to claim 1, characterized in that: The stirring speed when adding PTFE emulsion and SBR emulsion in step (2) is 5~30 r / s; step (3) is to repeatedly fold and roll the negative electrode powder with a tabletop noodle press, and then press it into a negative electrode sheet through a 50T double roller press.

9. The preparation method according to claim 1, characterized in that: The specific steps of step (4) are as follows: First, the negative electrode film is cut to the same size as the tin-plated inclined copper mesh. Then, the tin-plated inclined mesh is placed between the two negative electrode films and pressed together by rollers with a gap of 0.3 mm to obtain a solid negative electrode sheet of 0.45 mm. Then, the solid negative electrode sheet is dried at a temperature of 80~120℃ for 1 to 4 hours. After that, it is rolled twice by a roller press to obtain the negative electrode sheet. The negative electrode sheet is cut into a specific shape and size. The nickel extension tab with tab adhesive is welded to the cut trapezoidal tab position. A layer of PP separator is wrapped around the negative electrode sheet to ensure that the separator completely covers the reaction surface of the electrode sheet. Finally, the negative electrode of the zinc-nickel battery is obtained.

10. A zinc-nickel battery, characterized in that... Includes the zinc-nickel battery negative electrode prepared by the method according to any one of claims 1 to 9.

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