Positive electrode cap, preparation method of positive electrode cap and zinc-nickel cylindrical battery of positive electrode cap

Abstract

The invention provides a positive electrode cap, a preparation method of the positive electrode cap and a zinc-nickel cylindrical battery, and aims to solve the problem that in the prior art, the positive electrode cap is damaged in the welding process of the positive electrode cap and a tab of the zinc-nickel cylindrical battery, so that side reaction is generated between the positive electrode cap and a zinc negative electrode. The positive electrode cap comprises a positive electrode cap body, the positive electrode cap body comprises a bottom plate, and an insulating glue layer is arranged on the bottom plate; the insulating glue layer comprises insulating glue, the insulating glue comprises an inorganic additive, the inorganic additive comprises a first inorganic additive, and the first inorganic additive comprises a cerium compound. According to the positive electrode cap provided by the invention, cerium ions in the insulation paste can be dissolved in the electrolyte and re-deposit in a damaged area to form a repair barrier for the damaged area of the positive electrode cap, so that the contact between the positive electrode cap and a zinc negative electrode is prevented, the consumption of zinc is reduced, and the electrochemical corrosion reaction is fundamentally inhibited; and the side reaction between the nickel-zinc cylindrical battery and the zinc negative electrode is solved, so that the cycle performance and the safety performance of the nickel-zinc cylindrical battery are improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of battery manufacturing, and in particular relates to an insulating adhesive, a preparation method of the insulating adhesive and a zinc-nickel cylindrical battery thereof. Background Art

[0002] In the current battery market, commercial zinc-nickel cylindrical batteries are widely used in various small electronic devices and portable tools. Currently, commercial zinc-nickel cylindrical batteries on the market mostly use nickel-plated steel as the positive cap base.

[0003] The large potential difference between nickel and iron metals and the zinc negative electrode metal renders the entire battery chemistry highly unstable. During battery use and storage, side reactions such as hydrogen evolution and passivation frequently occur. The hydrogen evolution reaction causes a sharp increase in internal battery pressure, leading to a rapid decrease in battery capacity, while the passivation reaction forms a layer of material on the electrode surface that hinders electrochemical reactions, significantly reducing the battery's charge and discharge efficiency. Combined with these side reactions, the battery's cycle life is significantly shortened, making it unable to meet user needs for long-term use. Furthermore, the battery's capacity recovery after long-term storage is extremely poor, severely impacting its practicality and market competitiveness.

[0004] In order to solve the above problems, relevant personnel in this technical field have also taken many improvement measures, such as using pure copper, copper tin-plated base plate, or tin-plated positive electrode cap base plate. Although these measures have improved the side reactions, the use of copper is limited due to the high cost of copper. Therefore, tinning the positive electrode cap base plate has become a better measure. During the spot welding process of the tab, the current is large, which will damage the tin-plated layer of the base plate, and the problem cannot be fundamentally solved. Summary of the Invention

[0005] Aiming at the problem that the positive electrode cap is damaged during the welding process between the positive electrode cap and the tab of a zinc-nickel cylindrical battery in the prior art, thereby causing a side reaction between the positive electrode cap and the zinc negative electrode, a positive electrode cap, a preparation method of the positive electrode cap and a zinc-nickel cylindrical battery are provided.

[0006] The technical solutions adopted by the present invention to solve the above technical problems are as follows: In one aspect, the present invention provides a positive electrode cap, comprising a positive electrode cap body, wherein the positive electrode cap body comprises a bottom plate, and an insulating rubber layer is provided on the bottom plate; The insulating adhesive layer includes insulating adhesive, the insulating adhesive includes an inorganic additive, the inorganic additive includes a first inorganic additive, and the first inorganic additive includes a cerium compound.

[0007] Optionally, the cerium compound includes one or more of cerium oxide, cerium fluoride or cerium chloride; The cerium oxide includes one or more of Ce2O3 and CeO2; and / or, the cerium fluoride includes one or more of CeF3 and CeF4; and / or, the cerium chloride includes one or more of CeCl3, CeCl4, CeCl3·7H2O, and K2CeCl5.

[0008] Optionally, the inorganic additive further includes a second inorganic additive, and the second inorganic additive includes one or more of silicon oxide, antimony oxide, wollastonite, asbestos, mica and bismuth sulfate.

[0009] Optionally, the mass ratio of the first inorganic additive to the second inorganic additive is 1:10-1:1.

[0010] Optionally, the insulating adhesive further includes a leveling agent and an organic adhesive, the leveling agent includes one or more of polydimethylsiloxane, silicone oil and polyacrylic acid; and / or the organic adhesive includes one or more of asphalt and natural rubber.

[0011] Optionally, the insulating adhesive includes the following components by weight: 3-8 parts of leveling agent 85-92 parts of organic glue 2-6 parts of inorganic additives.

[0012] Optionally, the thickness of the insulating adhesive layer is 100-300 μm.

[0013] Optionally, a tin-plated layer is further provided on the bottom plate, and the tin-plated layer is provided between the insulating adhesive layer and the bottom plate.

[0014] Optionally, the thickness of the tin plating layer is 3-5 μm.

[0015] Optionally, the method for preparing the positive electrode cap includes the following operations: Take the positive electrode cap body and plate tin on its bottom plate surface; Mix the leveling agent, organic glue and inorganic additives, and mix them evenly to obtain insulating glue; The insulating glue is coated on the surface of the tinned layer on the bottom plate of the positive electrode cap, and after drying, the positive electrode cap is obtained.

[0016] On the other hand, the present invention provides a nickel-zinc cylindrical battery, comprising a positive electrode, a negative electrode, an electrolyte, a positive electrode ear, and the positive electrode cap or the positive electrode cap prepared by the preparation method of the positive electrode cap.

[0017] The beneficial effects of this application are: The positive electrode cap provided in the present application comprises a positive electrode cap body, the positive electrode cap body comprises a bottom plate, an insulating adhesive layer is provided on the bottom plate, the insulating adhesive layer comprises insulating adhesive, the first additive in the insulating adhesive comprises a cerium compound, and in a nickel-zinc battery system, the cerium ions in the cerium compound can play a role through a dissolution-redeposition process; during the spot welding process of the tab, the tinned layer of the positive electrode cap bottom plate is damaged by the current, and this process may cause the bottom plate to be exposed, resulting in contact between the positive electrode cap and the electrolyte, thereby affecting the performance of the nickel-zinc battery; at this time, the cerium ions in the insulating adhesive of the present application It will dissolve in the electrolyte and redeposit in the damaged area to form a new protective layer, forming a repair barrier for the damaged area of ​​the positive cap, further preventing the contact between the positive cap and the zinc negative electrode, and reducing the consumption of zinc; in addition, the insulating rubber layer as a whole has insulating properties itself, which can prevent the transfer of electrons between the positive cap and the zinc negative electrode, making it impossible for the microbattery that may be formed to form a complete circuit, fundamentally inhibiting the occurrence of electrochemical corrosion reactions, solving the side reactions between the nickel-zinc cylindrical battery and the zinc negative electrode, and thus improving the cycle performance and safety performance of the nickel-zinc cylindrical battery. DETAILED DESCRIPTION

[0018] In order to make the technical problems, technical solutions and beneficial effects solved by the present invention more clearly understood, the present invention is further described in detail below in conjunction with the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0019] The present invention provides a positive electrode cap, comprising a positive electrode cap body, wherein the positive electrode cap body comprises a bottom plate, and an insulating rubber layer is provided on the bottom plate; The insulating adhesive layer includes insulating adhesive, the insulating adhesive includes an inorganic additive, the inorganic additive includes a first inorganic additive, and the first inorganic additive includes a cerium compound.

[0020] Specifically, the positive electrode cap provided in the present application includes a positive electrode cap body, the positive electrode cap body includes a bottom plate, an insulating adhesive layer is provided on the bottom plate, the insulating adhesive layer includes insulating adhesive, and the first additive in the insulating adhesive includes a cerium compound. In the nickel-zinc battery system, the cerium ions in the cerium compound can play a role through the process of dissolution-redeposition; during the spot welding of the tab, the tin plating layer of the positive electrode cap bottom plate is damaged by the current. This process may cause the bottom plate to be exposed, resulting in contact between the positive electrode cap and the electrolyte, affecting the performance of the nickel-zinc battery; at this time, the cerium in the insulating adhesive of the present application The ions will dissolve in the electrolyte and redeposit in the damaged area to form a new protective layer, forming a repair barrier for the damaged area of ​​the positive cap, further preventing the contact between the positive cap and the zinc negative electrode, and reducing zinc consumption; in addition, the insulating glue layer as a whole has its own insulating properties, which can prevent the transfer of electrons between the positive cap and the zinc negative electrode, making it impossible for any microbatteries that may be formed to form a complete circuit, fundamentally inhibiting the occurrence of electrochemical corrosion reactions, solving the side reactions between the nickel-zinc cylindrical battery and the zinc negative electrode, and thus improving the cycle performance and safety performance of the nickel-zinc cylindrical battery.

[0021] In some embodiments, the cerium compound includes one or more of cerium oxide, cerium fluoride, or cerium chloride; The cerium oxide includes one or more of Ce2O3 and CeO2; and / or, the cerium fluoride includes one or more of CeF3 and CeF4; and / or, the cerium chloride includes one or more of CeCl3, CeCl4, CeCl3·7H2O, and K2CeCl5.

[0022] Specifically, in the nickel-zinc battery system, cerium oxide can undergo valence changes under certain conditions, and dissolution-redeposition is achieved through the valence change of cerium ions; when the insulating glue layer is damaged and the electrolyte around the zinc negative electrode contacts the exposed positive electrode cap bottom plate, Ce³⁺ can lose electrons in the damaged area and be re-oxidized to Ce 4 ⁺, and deposited at the damaged area to form a new protective layer, preventing further reaction between the positive cap bottom plate and the zinc negative electrode, reducing zinc consumption, and playing a self-repair and protection role.

[0023] In the battery's internal environment, cerium ions from cerium fluoride can also participate in the dissolution-redeposition process. Some fluoride ions may escape from the electrolyte, allowing cerium ions to enter the electrolyte in some form. When they encounter damaged areas of the insulating adhesive layer, the cerium ions react with surrounding materials and redeposit to form new cerium fluoride or other cerium-containing compounds, forming a protective layer in the damaged area, preventing microbattery reactions and reducing corrosion of the zinc negative electrode.

[0024] Cerium chloride will ionize in the electrolyte environment of nickel-zinc batteries to produce cerium ions and chloride ions. When the insulating rubber layer is damaged, the cerium ions can diffuse in the damaged area along with the electrolyte and redeposit at the damaged area. Moreover, the dissolution-redeposition process of cerium chloride is relatively easy to carry out, which can quickly repair and protect the damage to the insulating rubber layer to a certain extent.

[0025] In some embodiments, the inorganic additive further includes a second inorganic additive, wherein the second inorganic additive includes one or more of silicon oxide, antimony oxide, wollastonite, asbestos, mica, and bismuth sulfate.

[0026] Specifically, the wollastonite, asbestos, and mica in the second inorganic additive contain multiple elements such as magnesium, aluminum, calcium, and lithium. The rich trace metals have a stable electrochemical potential compared to zinc, the active material of the negative electrode of the nickel-zinc battery, and react slowly or even do not react under acidic and alkaline conditions. Under extreme conditions of high current and high voltage, metals such as magnesium, aluminum, and lithium are preferentially sacrificed, which is beneficial to reducing the consumption of the negative electrode active material and plays a role in stabilizing the chemical activity. In addition, the above-mentioned elements are also one of the components in the negative electrode system of the nickel-zinc battery described in this application. Using the above-mentioned substance as the second inorganic additive of the insulating glue layer reduces the introduction of components in the system.

[0027] In some embodiments, the mass ratio of the first inorganic additive to the second inorganic additive is 1:10-1:1.

[0028] Specifically, the present application sets the addition mass ratio of the first inorganic additive and the second inorganic additive within the above-mentioned range, which can better exert the synergistic effect between the two; the first inorganic additive is effective in forming a protective layer, while the second inorganic additive is beneficial to improving the stability of the battery. By adjusting the mass ratio, the above two additives can better exert their overall protective and stabilizing effects, effectively blocking the microbattery pathway and reducing the corrosion of the zinc negative electrode.

[0029] The appropriate ratio can make the dissolution-redeposition process of cerium ions smoother and more efficient, allowing the components of the first inorganic additive and the second inorganic additive to play a role in a timely and effective manner during the operation of the battery, thereby more quickly preventing the reaction between the positive cap bottom plate and the zinc negative electrode and reducing zinc consumption.

[0030] In some embodiments, the insulating adhesive further includes a leveling agent and an organic adhesive, the leveling agent includes one or more of polydimethylsiloxane, silicone oil, and polyacrylic acid; and / or the organic adhesive includes one or more of asphalt and natural rubber.

[0031] Specifically, the low surface tension and leveling properties of the leveling agent can enable the insulating glue to spread better during the coating process, fill tiny bumps and make the surface of the insulating glue layer smoother, which helps to evenly distribute the insulating glue on the positive cap base plate, ensure the uniform thickness of the insulating glue layer, make the insulation performance and protective effect more stable, and effectively block the path between the positive cap substrate and the battery cell to form a micro-battery.

[0032] Organic glue can firmly bond inorganic additives, leveling agents and other ingredients together to form a stable insulating glue system; for example, the high elasticity and flexibility of natural rubber enable the insulating glue layer to withstand the volume changes and mechanical vibrations of the battery during charging and discharging, and is not easily broken or damaged, maintaining good coverage and insulation of the positive cap. In addition, natural rubber has good insulating properties and works synergistically with other ingredients to further improve the overall insulating effect of the insulating glue layer, blocking the electron conduction path between the positive cap bottom plate and zinc, and reducing the corrosion of the zinc negative electrode.

[0033] In some embodiments, the insulating adhesive comprises the following components by weight: 3-8 parts of leveling agent 85-92 parts of organic glue 2-6 parts of inorganic additives.

[0034] In some embodiments, the thickness of the insulating adhesive layer is 100-300 μm.

[0035] Specifically, controlling the thickness of the insulating adhesive layer within the range of 100-300 μm helps to make the electric field distribution within the insulating adhesive layer more uniform. If the adhesive layer is too thin, the electric field may be concentrated in certain weak areas, causing local discharge or insulation breakdown. A thickness of 100-300 μm can make the electric field relatively evenly distributed within the adhesive layer, reducing the possibility of insulation failure due to uneven electric field.

[0036] The thickness of 100-300μm gives the insulating rubber layer a certain mechanical strength and toughness, which can withstand various mechanical stresses during the production, assembly and use of the battery. It can effectively protect the welding points and bottom plate of the positive cap and prevent them from being damaged by external mechanical forces, thereby ensuring the integrity of the battery structure.

[0037] In some embodiments, a tin-plated layer is further provided on the bottom plate, and the tin-plated layer is provided between the insulating adhesive layer and the bottom plate.

[0038] Specifically, the tin plating layer and the insulating adhesive layer form a double protective structure. The tin plating layer initially blocks the contact between the bottom plate and the outside world, while the insulating adhesive layer further blocks the path of the microbattery from a physical and chemical level. When the tin plating layer is locally damaged, the components in the insulating adhesive layer (such as inorganic additives containing cerium compounds) can further protect the bottom plate through self-repair and other effects, preventing electrochemical corrosion reactions between the positive cap bottom plate and the zinc negative electrode. The two work together to greatly improve the protection effect of the zinc negative electrode.

[0039] The tin plating layer can improve the bonding strength between the insulating adhesive layer and the base plate. When the base plate surface of the positive cap is directly bonded to the insulating adhesive layer, there may be a problem of insufficient adhesion. The surface properties of the tin plating layer are relatively more suitable for bonding with the insulating adhesive layer, which can make the insulating adhesive layer more firmly adhere to the base plate. During the use of the battery, it can also ensure that the insulating adhesive layer is firm and does not fall off, and continues to play its insulating and protective role.

[0040] In some embodiments, the thickness of the tin plating layer is 3-5 μm.

[0041] Specifically, the tin plating layer within this range can form an effective barrier layer between the base plate and the external environment, effectively preventing the metal material of the base plate from directly contacting substances such as air, moisture, and the electrolyte inside the battery, thereby reducing the risk of oxidation and corrosion, extending the service life of the base plate, and ensuring the stability of the battery structure.

[0042] During the welding process, the 3-5μm tin plating layer can melt well at the welding temperature and form a good bond with the welding material, ensuring good electrical connection between the electrode and the base plate, and ensuring stable charge and discharge performance of the battery.

[0043] In some embodiments, the method for preparing the positive electrode cap comprises the following operations: Take the positive electrode cap body and plate tin on its bottom plate surface; Mix the leveling agent, organic glue and inorganic additives, and mix them evenly to obtain insulating glue; The insulating glue is coated on the surface of the tinned layer on the bottom plate of the positive electrode cap, and after drying, the positive electrode cap is obtained.

[0044] Another embodiment of the present invention provides a nickel-zinc cylindrical battery, comprising a positive electrode, a negative electrode, an electrolyte, a positive electrode tab, and the positive electrode cap or the positive electrode cap prepared by the positive electrode cap preparation method.

[0045] Specifically, in the nickel-zinc cylindrical battery, the positive electrode undergoes an oxidation reaction and releases electrons, the negative electrode accepts electrons and undergoes a reduction reaction, and the positive tab connects the positive electrode and the positive cap to carry out electron transfer; and the insulating adhesive in the insulating adhesive layer provided on the positive cap bottom plate described in the present application includes a cerium compound. In the nickel-zinc battery system, the cerium ions in the cerium compound can play a role through a dissolution-redeposition process; during the tab spot welding process, the tin plating layer of the positive cap bottom plate is damaged by the current. This process may cause the bottom plate to be exposed, resulting in contact between the positive cap and the electrolyte, affecting the performance of the nickel-zinc battery; at this time, the cerium ions in the insulating adhesive of the present application will dissolve in the electrolyte and redeposit in the damaged area to form a new protective layer, forming a repair barrier for the damaged area of ​​the positive cap, further preventing contact between the positive cap and the zinc negative electrode, preventing the positive cap substrate and the zinc of the negative electrode from forming a micro-battery that accelerates zinc corrosion, thereby improving the stability, safety and service life of the battery.

[0046] The present invention is further described below with reference to the following examples.

[0047] Example 1 This embodiment is used to illustrate a method for preparing a positive electrode cap and a zinc-nickel cylindrical battery disclosed in the present invention, and includes the following steps: Prepare the positive electrode cap: Take 5 parts of leveling agent polydimethylsiloxane, 90 parts of organic adhesive asphalt and 5 parts of inorganic additives (first additive CeF3, second additive wollastonite, CeF3: wollastonite = 1:2), and mix them to obtain insulating adhesive; Taking the positive electrode cap body, tinning the bottom plate thereof to obtain a positive electrode cap body having a tinned layer, wherein the tinned layer has a thickness of 3 μm; Applying insulating glue to the surface of the tinned layer of the base plate to a thickness of 200 μm to obtain a positive electrode cap; Preparation of positive electrode: Ni(OH)2, ZnO, CoO, Ni powder, Ca(OH)2, Y2O3, Yb2O3, graphite, CMC, and PTFE were mixed in a ratio of 86.5:1:3:2:1:2:2:1:0.5:3, coated on the positive electrode current collector, and rolled, softened, and cut to obtain a positive electrode; Preparation of negative electrode: Take 1% conductive material, 0.3% thickener, and 1% dispersant and mix them evenly. Then add 0.02% In2O3, 0.08% Bi2O3, and 3% Al2O3. After mixing again, add 58% ZnO, 30% Zn, and 3.6% binder. After stirring evenly, apply it on the negative electrode current collector. After roller pressing, softening, and cutting, the negative electrode is obtained. Prepare the electrolyte: The electrolyte composition of this embodiment is 80% (5-5.5 mol / L) KOH, 2% (5 mol / L) ZnO, 10% silica sol, and 3-5% disodium hydrogen phosphate.

[0048] Example 2 This example is used to illustrate a method for preparing a positive electrode cap and a zinc-nickel cylindrical battery thereof disclosed in the present invention, and includes most of the operations in Example 1, except that: In the preparation of the insulating adhesive, the mass ratio of the first additive to the second additive is 1:1.

[0049] Example 3 This example is used to illustrate a method for preparing a positive electrode cap and a zinc-nickel cylindrical battery thereof disclosed in the present invention, and includes most of the operations in Example 1, except that: In the preparation of the insulating adhesive, the mass ratio of the first additive to the second additive is 1:3.

[0050] Example 4 This example is used to illustrate a method for preparing a positive electrode cap and a zinc-nickel cylindrical battery thereof disclosed in the present invention, and includes most of the operations in Example 1, except that: In the preparation of the insulating adhesive, the first additive is cerium oxide (Ce2O3) and the second additive is silicon oxide.

[0051] Example 5 This example is used to illustrate a method for preparing a positive electrode cap and a zinc-nickel cylindrical battery thereof disclosed in the present invention, and includes most of the operations in Example 1, except that: In the preparation of the insulating adhesive, the first additive is cerium chloride (CeCl3) and the second additive is antimony oxide.

[0052] Example 6 This example is used to illustrate a method for preparing a positive electrode cap and a zinc-nickel cylindrical battery thereof disclosed in the present invention, and includes most of the operations in Example 1, except that: In the preparation of the insulating adhesive, the first additive is cerium chloride (CeCl3) and cerium fluoride (CeF3), CeCl3:CeF3=1:1, and the second additive is wollastonite.

[0053] Example 7 This example is used to illustrate a method for preparing a positive electrode cap and a zinc-nickel cylindrical battery thereof disclosed in the present invention, and includes most of the operations in Example 1, except that: In the preparation of the insulating adhesive, the first additive is cerium chloride (CeCl3), cerium fluoride (CeF3) and cerium oxide (Ce2O3), CeCl3:CeF3:Ce2O3=1:1:1, and the second additive is wollastonite.

[0054] Example 8 This example is used to illustrate a method for preparing a positive electrode cap and a zinc-nickel cylindrical battery thereof disclosed in the present invention, and includes most of the operations in Example 1, except that: The coating thickness of the insulating adhesive is 100 μm.

[0055] Example 9 This example is used to illustrate a method for preparing a positive electrode cap and a zinc-nickel cylindrical battery thereof disclosed in the present invention, and includes most of the operations in Example 1, except that: The coating thickness of the insulating adhesive is 300 μm.

[0056] Example 10 This example is used to illustrate a method for preparing a positive electrode cap and a zinc-nickel cylindrical battery thereof disclosed in the present invention, and includes most of the operations in Example 1, except that: The thickness of the tin plating layer is 4 μm.

[0057] Example 11 This example is used to illustrate a method for preparing a positive electrode cap and a zinc-nickel cylindrical battery thereof disclosed in the present invention, and includes most of the operations in Example 1, except that: The thickness of the tin plating layer is 5 μm.

[0058] Example 12 This example is used to illustrate a method for preparing a positive electrode cap and a zinc-nickel cylindrical battery thereof disclosed in the present invention, and includes most of the operations in Example 1, except that: In the preparation of the insulating adhesive, the leveling agent is 8 parts, the organic adhesive is 87 parts, and the inorganic additive is 5 parts.

[0059] Example 13 This example is used to illustrate a method for preparing a positive electrode cap and a zinc-nickel cylindrical battery thereof disclosed in the present invention, and includes most of the operations in Example 1, except that: In the preparation of the insulating adhesive, the leveling agent is 5 parts, the organic adhesive is 92 parts, and the inorganic additive is 3 parts.

[0060] Example 14 This example is used to illustrate a method for preparing a positive electrode cap and a zinc-nickel cylindrical battery thereof disclosed in the present invention, and includes most of the operations in Example 1, except that: In the preparation of the insulating adhesive, the leveling agent is 3 parts, the organic adhesive is 92 parts, and the inorganic additive is 5 parts.

[0061] Comparative Example 1 This comparative example is used to compare and illustrate a method for preparing a positive electrode cap and a zinc-nickel cylindrical battery thereof disclosed in the present invention, and includes most of the operations in Example 1, except that: During the preparation of the insulating adhesive, no first additive was added.

[0062] Comparative Example 2 This comparative example is used to compare and illustrate a method for preparing a positive electrode cap and a zinc-nickel cylindrical battery thereof disclosed in the present invention, and includes most of the operations in Example 1, except that: In the preparation of insulating glue, potassium fluoride is selected as the first additive.

[0063] Performance Testing The following performance tests were performed on Examples 1-14 and Comparative Examples 1-2 prepared above: Supplement the corresponding test methods and test steps Cycle life At 25°C, the nickel-zinc batteries prepared in the examples and comparative examples were charged at 1C to 1.9V, then charged at 1.9V constant voltage to a cutoff current of 13.5mA, and discharged at 1C to 1.3V. The charge and discharge were repeated until the battery capacity dropped to 60% of the initial charge, and the number of charge and discharge cycles was recorded.

[0064] 5C high rate performance At 25°C, the nickel-zinc batteries prepared in each embodiment and comparative example were charged at 0.2C to 1.9V, then charged at a constant voltage of 1.9V to a cutoff current of 13.5mA, and discharged at 0.2C to 1.3V, and the 0.2C capacity was recorded; the nickel-zinc batteries prepared in each embodiment and comparative example were then charged at 0.2C to 1.9V, then charged at a constant voltage of 1.9V to a cutoff current of 13.5mA, and discharged at 5C to 1.3V, and the 5C capacity was recorded. The percentage of 5C high-rate discharge capacity = 5C capacity / 0.2C capacity * 100% High temperature cycle capacity retention rate (1) At 25°C, fully charge the battery using a constant current and constant voltage charging method. Charge to 1.9V at 0.2C, then charge at 1.9V constant voltage until the cut-off current reaches 13.5mA. (2) Store fully charged batteries in a 60°C oven for 28 days (3) After storage, discharge the battery at 0.2C to 1.3V, then charge it using the same charging method as (1), leave it for 10 minutes, and then discharge it at 0.2C to 1.3V. Repeat the above charging and discharging steps 3 times.

[0065] The test results are entered in Table 1.

[0066] Table 1 From the test results in Table 1, it can be seen that the cycle life of Examples 1 to 14 is 220 times or more, the cycle life of Comparative Example 1 is 210 times, and the cycle life of Comparative Example 2 is 200 times. By comparison, it can be seen that the embodiments in which the insulating glue is added with a first inorganic additive containing a cerium compound generally have a cycle life longer than Comparative Example 1 in which no first additive is added, and Comparative Example 2 in which other additives (potassium fluoride) are used as the first additive. Among them, the cycle life of Example 7 reaches 300 times, which shows that the first inorganic additive containing a cerium compound can significantly improve the cycle life of the battery, because cerium ions can form a repair barrier through dissolution-redeposition during battery use, reduce the contact between the positive electrode cap and the zinc negative electrode, inhibit side reactions, and thus extend the number of charge and discharge cycles of the battery. The 5C high-rate performance of Examples 1-14 is between 60% and 85%, while that of Comparative Example 1 is 58% and that of Comparative Example 2 is 55%. The high-rate performance data of the Examples is generally better than that of the Comparative Examples. This indicates that the self-repair process involving the cerium compound can stabilize the internal structure and reaction of the battery, allowing the battery to maintain good performance even during high-rate discharge, thereby facilitating the use of the battery in high-power scenarios. The SOC of Examples 1-14 is between 47.3% and 55.1%, and the SOH is between 89.6% and 95.2%. The SOC of Comparative Examples 1-2 is 46.2% and 45.7%, and the SOH is 88.2% and 87.4%, respectively. By comparison, it can be seen that the storage performance of Examples 1-14 is significantly higher than that of Comparative Examples 1-2, indicating that during the storage process, the cerium ions in the insulating adhesive containing cerium compounds play a role through the process of self-dissolution-redeposition, repairing the damaged area of ​​the positive electrode cap, maintaining the stability of the internal structure and performance of the battery, reducing the negative impact of storage on battery performance, and effectively improving the performance retention ability of the battery after storage; The internal resistance of the batteries of Examples 1-14 was between 20.1 and 31.4 mΩ, compared to 32.9 mΩ for Comparative Example 1 and 33.6 mΩ for Comparative Example 2. The internal resistance of the batteries of the Examples was relatively low because the dual protective structure of the insulating rubber layer and the tin plating layer effectively reduced side reactions within the battery, lowered the internal resistance of the battery, reduced energy loss during the charge and discharge process, and improved the charge and discharge efficiency and overall performance of the battery. Example 1, Example 10 and Example 11 have tin plating layers of different thicknesses. When the thickness of the tin plating layer increases from 3 μm to 4 μm, the cycle life does not change. When it increases to 5 μm, the cycle life decreases slightly. It is speculated that the excessive thickness of the tin plating layer may affect the stability of the internal structure of the battery, resulting in a slight decrease in the cycle life. From the 5C high-rate performance test results of Example 1, Example 10 and Example 11, it can be concluded that a thicker tin plating layer may hinder the electron conduction and ion diffusion inside the battery, and affect the reaction rate of the battery during high-current discharge. A thinner tin plating layer (3 μm) is more conducive to the electrochemical reaction inside the battery under high-rate discharge conditions. In addition, as the thickness of the tin plating layer increases, the storage performance gradually decreases. This means that the thicker tin plating layer may not be able to effectively prevent the side reactions inside the battery during battery storage, or the interaction between the tin plating layer and the insulating glue layer changes, affecting the overall chemical stability of the battery, resulting in a decrease in storage performance. From Examples 12-14, it can be seen that the cycle life of Example 12 is 250 times, and that of Examples 13 and 14 is 240 times. From the data, it can be seen that with the increase of the leveling agent (Example 14-12), the cycle life shows a trend of first increasing and then decreasing. The organic glue decreases from 92 parts to 87 parts (Example 13-Example 12), and the cycle life also increases first and then decreases. This shows that an appropriate amount of leveling agent and organic glue helps to improve the cycle life. The leveling agent can make the insulating glue spread better, ensure the stability of the insulating performance, and extend the cycle life. In addition, the organic glue can bond the various components to provide good insulation and protection.

[0067] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A positive electrode cap, characterized in that: It includes a positive cap body, the positive cap body includes a bottom plate, and the bottom plate is provided with an insulating rubber layer; The insulating adhesive layer includes insulating adhesive, the insulating adhesive includes an inorganic additive, the inorganic additive includes a first inorganic additive, and the first inorganic additive includes a cerium compound.

2. A positive electrode cap according to claim 1, characterized in that: The cerium compound includes one or more of cerium oxide, cerium fluoride or cerium chloride; The cerium oxide includes one or more of Ce2O3 and CeO2; and / or, the cerium fluoride includes one or more of CeF3 and CeF4; and / or, the cerium chloride includes one or more of CeCl3, CeCl4, CeCl3·7H2O, and K2CeCl5.

3. The positive electrode cap according to claim 1, characterized in that: The inorganic additive further includes a second inorganic additive, and the second inorganic additive includes one or more of silicon oxide, antimony oxide, wollastonite, asbestos, mica and bismuth sulfate.

4. A positive electrode cap according to claim 3, characterized in that: The mass ratio of the first inorganic additive to the second inorganic additive is 1:10-1:

1.

5. The positive electrode cap according to claim 1, characterized in that: The insulating adhesive further comprises a leveling agent and an organic adhesive, wherein the leveling agent comprises one or more of polydimethylsiloxane, silicone oil and polyacrylic acid; and / or the organic adhesive comprises one or more of asphalt and natural rubber.

6. The positive electrode cap according to claim 5, characterized in that: The insulating adhesive comprises the following components by weight: 3-8 parts of leveling agent 85-92 parts of organic glue 2-6 parts of inorganic additives.

7. The positive electrode cap according to claim 1, characterized in that: The thickness of the insulating adhesive layer is 100-300 μm.

8. The positive electrode cap according to claim 1, characterized in that: The bottom plate is further provided with a tinned layer, and the tinned layer is provided between the insulating adhesive layer and the bottom plate.

9. The positive electrode cap according to claim 8, characterized in that: The thickness of the tinned layer is 3-5 μm.

10. The method for preparing a positive electrode cap according to any one of claims 1 to 9, characterized in that: The following operations are included: Take the positive electrode cap body and plate tin on its bottom plate surface; Mix the leveling agent, organic glue and inorganic additives, and mix them evenly to obtain insulating glue; The insulating glue is coated on the surface of the tinned layer on the bottom plate of the positive electrode cap, and after drying, the positive electrode cap is obtained.

11. A nickel-zinc cylindrical battery, characterized in that: The invention comprises a positive electrode, a negative electrode, an electrolyte, a positive electrode ear, and a positive electrode cap according to any one of claims 1 to 9 or a positive electrode cap prepared by the preparation method of the positive electrode cap according to claim 10, wherein the positive electrode ear is connected to the positive electrode and the positive electrode cap.

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