A method for preparing a negative electrode of a zinc-nickel battery

Abstract

The present invention belongs to the field of alkaline zinc-nickel secondary batteries and discloses a method for preparing a negative electrode for a zinc-nickel secondary battery. The negative electrode slurry is formed by mixing a solid negative electrode active material, Zn powder, a negative electrode additive, a carbon material, a surfactant, and a polymer slurry medium in a certain proportion. Suitable polymer slurry media and slurrying processes can improve the uniformity and coating performance of the slurry, better control the load, improve the uniformity of the coating, and ensure the stability of the negative electrode. The polymer slurry medium uses a polymer with a certain ionic conductivity as a base material, and can construct an organic framework in the negative electrode, so that the active material is more evenly distributed and the structure of the electrode is stabilized. In addition, a highly conductive carbon material with a porous or layered structure is added, which together with the organic framework constructs an ion-electron mixed conductive framework, thereby improving the capacity and stability of the electrode.

Description

Technical Field

[0001] The invention belongs to the technical field of batteries, and particularly relates to a method for preparing a negative electrode of a zinc-nickel battery. Background Art

[0002] With the rapid rise of new energy sources in recent years and the need to meet the demands of green development, various energy storage and power batteries have ushered in tremendous development opportunities. Among them, zinc-nickel secondary batteries offer excellent application prospects in the energy storage and power battery fields due to their low self-discharge, low cost, high open-circuit voltage and discharge current, and, more importantly, high safety.

[0003] Nickel-zinc batteries, a promising energy source, have a simple manufacturing process, with slurry mixing being one of the most critical. Slurry mixing is generally divided into aqueous and organic medium slurries. The negative electrode material often has different components. If the components are not evenly dispersed, the stability of the electrode will be significantly affected.

[0004] Usually, if there are too many components in the slurry, the slurry mixing process will be much more difficult, the slurry mixing time will be much longer, and the components will be more difficult to disperse evenly, which will affect the subsequent performance and economic benefits.

[0005] In the prior art, zinc-nickel battery negative electrode slurries do not incorporate a high proportion of organic polymer composite media, and thus do not form an organic framework. The slurries often exhibit high fluidity, which facilitates thorough and uniform mixing. However, these highly fluid slurries are only suitable for coating by slurry drawing, which in turn limits the amount of electrode loading. Paste-like slurries with poor fluidity are also limited to the production of laminated batteries and are difficult to apply to thinner wound batteries.

[0006] For example, the prior art CN105161702A zinc-nickel battery adds polyols to the negative electrode active material, which maintains the uniform stability of the negative electrode active material during slurry mixing, allowing the slurry to maintain its initial state for a long time, ensuring the consistency of electrode production, thereby fundamentally ensuring the consistency of the battery and improving the cycle stability of the power system.

[0007] For example, the preparation method of the prior art CN110289395B includes the following steps: mixing and stirring the negative electrode powder and additives to obtain raw material powder; mixing and stirring the raw material powder with polytetrafluoroethylene emulsion to obtain a mixed powder, wherein the revolution speed is 20 to 50 rad / min, the rotation speed is 3000 to 5000 rad / min, and the revolution and rotation time is 10 to 20 minutes; mixing and stirring the mixed powder with a paste medium to obtain a paste; the paste composition, calculated by mass percentage, includes 77 to 85% of negative electrode powder, 5 to 10% of additives, 1 to 5% of polytetrafluoroethylene, and 8 to 17% of the paste medium. This solves the problem that the prior art neutralization paste has a low viscosity and is only suitable for the preparation of electrodes by the pulling method, resulting in thinner electrodes, low biomass, short life, and poor consistency.

[0008] For example, the prior art CN119050286 discloses a nickel-zinc battery positive electrode and its preparation method and application. The preparation method is relatively simple and does not optimize and adjust the negative electrode slurry.

[0009] For example, prior art CN119050286A discloses a zinc-nickel secondary battery negative electrode formulation that adds PAAK to a pre-slurry solution, then adds the negative electrode powder and stirs to form a slurry. However, the addition of PAAK can lead to significant agglomeration, making slurry mixing more difficult, which not only affects electrode performance but also increases costs.

[0010] Overall, this field urgently needs to develop a method for preparing zinc-nickel battery negative electrodes with good slurry coating performance, tightly bonded negative electrode sheets, uniform material dispersion, and effectively increased loading capacity. Summary of the Invention

[0011] In order to solve the above-mentioned deficiencies and shortcomings of the prior art, the present invention aims to provide a method for preparing a negative electrode for a zinc-nickel battery, which has good slurry coating performance, the prepared negative electrode plate is tightly bonded, the material is evenly dispersed, and the loading capacity and electrochemical performance of the plate are effectively improved.

[0012] The technical solutions adopted in the present invention are as follows:

[0013] A method for preparing a negative electrode of a zinc-nickel battery comprises the following steps:

[0014] Step (1): Mixing the negative electrode powder: fully and evenly stir the solid negative electrode active material and the negative electrode additive to obtain a negative electrode mixed powder; then pre-mix the zinc powder and the carbon material;

[0015] Step (2): preparing a polymer slurry medium: preparing different solutions of the polymer slurry medium in advance, mixing and stirring the different solutions to obtain a polymer slurry medium:

[0016] Step (3): slurry preparation, adding a surfactant sodium dodecylbenzenesulfonate (SDBS) aqueous solution to the polymer slurry medium and stirring evenly, then slowly pouring the negative electrode mixed powder into it, accompanied by high-speed stirring to break up, to prevent the negative electrode mixed powder from agglomerating after contacting the polymer slurry medium; then adding SBR emulsion and PTFE emulsion respectively, and finally adding zinc powder and carbon material to prepare the battery negative electrode slurry;

[0017] Step (4): Preparation of the negative electrode of the zinc-nickel battery: coating, drying, rolling, cutting, welding and extending the tabs and coating the diaphragm to obtain the negative electrode of the zinc-nickel battery;

[0018] The polymer slurry medium is formed by mixing a polymer matrix and a base reinforcing agent; the polymer matrix is ​​selected from one of a polyvinyl alcohol (PVA) aqueous solution, a polyethylene oxide (PEO) aqueous solution, and a polyethylene-vinyl acetate copolymer (EVA) aqueous solution; the base reinforcing agent is selected from a carboxymethyl cellulose (CMC) aqueous solution; the mass ratio of the polymer matrix to the base reinforcing agent solution is (20-25): (1-10);

[0019] The concentration of the polymer matrix is ​​2% to 5%, and the concentration of the base strengthening agent solution is 2% to 5%;

[0020] The SBR emulsion is an SBR aqueous solution with an SBR solid content of 50%;

[0021] The PTFE emulsion is a PTFE aqueous solution with a PTFE resin solid content of 60%;

[0022] The carbon material is one or more of colloidal graphite with a lamellar structure, graphene, conductive carbon black with a porous structure, and carbon nanotubes.

[0023] Preferably, the high-speed stirring speed in step (3) is 1500-2000 r / min.

[0024] Preferably, the step (4) specifically comprises the following steps: pre-pressing the punched tinned copper strip base to a thickness of 0.70-0.80 mm, then coating the slurry onto the punched tinned copper strip, setting the scraper gap to 0.75 mm, and scraping the material to obtain a punched tinned copper strip uniformly coated with the slurry; then drying the coated punched tinned copper strip at 60-80° C. for 1-4 hours, and then rolling it twice on a roller press, to obtain a negative electrode sheet after the two rolling steps. Subsequently, the sheet is cut into a specific shape and size, and a nickel extension tab with tab glue is welded to the cut trapezoidal tab by a spot welder, and finally a layer of PP diaphragm is coated around the negative electrode sheet to fully cover the reaction surface area of ​​the tab sheet, thereby obtaining a zinc-nickel battery negative electrode.

[0025] Preferably, the solid negative electrode active material is zinc oxide;

[0026] The negative electrode additive is one or more of metal single substance Bi powder, Sn powder, bismuth oxide, indium hydroxide, calcium hydroxide, aluminum oxide or lead oxide metal compound.

[0027] Preferably, the negative electrode additive is a combination of metallic element Bi powder or Sn powder and indium hydroxide, with a weight ratio of (1-4): (0.05-2).

[0028] A zinc-nickel battery negative electrode is prepared by the above-mentioned zinc-nickel battery negative electrode preparation method.

[0029] As preferably, it comprises the following components in parts by weight:

[0030] 50-70 parts of solid negative electrode active material

[0031] 8-15 parts of Zn powder

[0032] 2-8 parts of negative electrode additive

[0033] 1-5 parts of carbon material

[0034] 0.3-0.7 parts of sodium dodecylbenzenesulfonate (SDBS) aqueous solution

[0035] 20-30 parts of polymer slurry medium

[0036] 1-6 parts SBR emulsion

[0037] 3-5 parts PTFE emulsion

[0038] A zinc-nickel battery is assembled by assembling the above-mentioned zinc-nickel battery negative electrode and zinc-nickel battery positive electrode sheet.

[0039] The beneficial effects of the present invention are as follows:

[0040] (1) An ionically conductive polymer binder and an electronically conductive surfactant are added to the polymer slurry medium to form an organic polymer framework with ion and electronic conductivity. The viscoelasticity and conductivity of individual polymers work synergistically to improve the electrode capacity and stability at high discharge rates. Among them, the added polymer base reinforcement CMC solution has a better dispersion effect on the active substance and other powder materials than the PAAK solution, effectively avoiding the phenomenon of powder agglomeration during the stirring process, resulting in uneven slurry and difficulty in slurrying. Figure 4 A schematic diagram of the slurry prepared by adding PAAK is shown, and the agglomeration phenomenon is quite obvious.

[0041] (2) The mixed negative electrode powder is added to the polymer slurry medium under high-speed stirring, so that the active material and the negative electrode additive are evenly dispersed and fully contacted, thereby improving their cycle performance. In addition, high-speed stirring is also more conducive to the uniform formation of the slurry.

[0042] (3) Compared with the traditional single binder, the use of composite binder can improve the adhesion between the active material of the electrode and the substrate, thereby effectively improving the phenomenon of powder shedding in the late cycle of zinc-nickel batteries, which leads to a significant decrease in capacity.

[0043] (4) Introducing carbon materials into the organic framework of the electrode to build an efficient conductive network in the negative electrode, thereby improving the ability of the electrode to conduct electrons and thus reducing the polarization of the electrode. In addition, carbon materials with porous or layered structures can also effectively increase the contact area between the electrolyte and the electrode, allowing more active substances to participate in the reaction. The two work synergistically to improve the charging acceptance capacity of the electrode and effectively improve the charging and discharging efficiency and capacity of the electrode.

[0044] (5) The interactively entangled long-chain polymers in the electrode network interact with the porous carbon material or layered carbon material to jointly construct the transmission channel of zincate ions, improve the deposition and stripping of zinc, inhibit dendrite formation and electrode passivation, and thus improve the cycle life.

[0045] (6) The use of a colloidal polymer slurry medium has the advantages of being easy to store, stable in alkaline solution, and having uniform dispersion of the components.

[0046] (7) A specific addition sequence is used to add materials to the polymer slurry medium in batches, accompanied by high-speed stirring, to minimize agglomeration during slurry stirring, improve slurry dispersion, and enhance electrode consistency. A detailed description of the process control points in subsequent slurry coating, drying, and roller pressing is also provided, which has great guiding significance. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present application. For those skilled in the art, other drawings can be obtained based on these drawings without creative work.

[0048] Figure 1 This is a schematic diagram of the slurry in Example 1 of the present application;

[0049] Figure 2 This is a schematic diagram of the negative electrode of this application;

[0050] Figure 3 This is a schematic diagram of the negative electrode sheet of Example 1 of the present application;

[0051] Figure 4 This is a schematic diagram of the slurry of Comparative Example 3 of the present application having obvious agglomeration phenomenon;

[0052] Figure 5 The voltage-current-time comparison diagram (Figure a) and the coulombic efficiency-cycle number comparison diagram (Figure b) of Example 1 of the present application and a commercially available electrode under full battery testing are shown;

[0053] Figure 6 The voltage, current-time diagram (Figure a) and the coulombic efficiency-cycle number diagram (Figure b) of the full battery test of Example 5 of the present application are shown;

[0054] Figure 7 The voltage, current-time graph (Figure a) and the coulombic efficiency-cycle number graph (Figure b) of the full battery test of Example 6 of the present application are shown;

[0055] Figure 8 This is a schematic diagram of the slurry fineness measurement results of Example 1 of the present application; DETAILED DESCRIPTION

[0056] In order to enable those skilled in the art to better understand the technical solutions in the embodiments of the present invention and to make the above-mentioned objects, features and advantages of the present invention more obvious and understandable, the specific implementation methods of the present invention are further described below.

[0057] The endpoints of the ranges and any values ​​disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoints of each range, the endpoints of each range and individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0058] Example 1:

[0059] A zinc-nickel battery negative electrode slurry comprises the following components in parts by weight: 51.12 parts of medical-grade zinc oxide as a solid negative electrode active material, 12.5 parts of Zn powder with a mesh size of 500 or larger, 3.08 parts of a negative electrode additive comprising 1 part of metallic element Bi and 0.08 parts of indium hydroxide in a weight ratio of 2 parts, 1 part of colloidal graphite as a carbon material, 0.5 parts of a sodium dodecylbenzenesulfonate (SDBS) aqueous solution with a 10% SDBS solid content as a surfactant, 1.8 parts of an SBR aqueous solution with a 50% SBR solid content, 4 parts by weight of a PTFE aqueous solution with a 60% PTFE resin solid content, and 27 parts of a polymer slurry medium comprising a 4% polyvinyl alcohol solution and a 3% sodium carboxymethyl cellulose aqueous solution in a ratio of 22:5, wherein the 4% polyvinyl alcohol solution is a solution obtained by dissolving 4 parts of polyvinyl alcohol in 96 parts of deionized water, and the 3% sodium carboxymethyl cellulose aqueous solution is a solution obtained by dissolving 3 parts of sodium carboxymethyl cellulose in 97 parts of deionized water.

[0060] A method for preparing a negative electrode of a zinc-nickel battery comprises the following steps:

[0061] Step (1): Mixing the negative electrode powder: fully stir the solid negative electrode active material and the negative electrode additive to obtain a negative electrode mixed powder, and then pre-mix the required zinc powder and carbon material;

[0062] Step (2): preparing a polymer slurry medium: preparing different solutions of the polymer slurry medium in advance, mixing and stirring the different solutions to obtain a polymer slurry medium:

[0063] Step (3): slurry preparation, adding a surfactant sodium dodecylbenzenesulfonate (SDBS) aqueous solution to the polymer slurry medium and stirring evenly, then slowly pouring the negative electrode mixed powder into it, accompanied by high-speed stirring at 1600r / min to disperse it, to prevent the negative electrode mixed powder from agglomerating after contacting the polymer slurry medium; then adding SBR emulsion and PTFE emulsion respectively and continuing to stir for 2min, finally adding zinc powder and carbon material mixed powder and stirring for 1min to prepare the battery negative electrode slurry; Figure 1 shown.

[0064] Step (4): Preparation of the negative electrode of the zinc-nickel battery: The negative electrode of the zinc-nickel battery is prepared by coating, drying, rolling, cutting, welding and extending the tabs and coating the diaphragm; specifically, the prepared slurry is applied to the punched tin-plated copper strip substrate with a scraper, wherein the punched tin-plated copper strip substrate is pre-pressed to a thickness of 0.73mm, and then the slurry is applied to the punched tin-plated copper strip and the scraper gap is set to 0.75mm to scrape and integrate the material to obtain a punched tin-plated copper strip evenly coated with the slurry. The coated punched tin-plated copper strip is then dried in a blast drying oven at 70°C for 2 hours, and then rolled twice on a roller press, wherein the roller gap is set to 0.50mm for the first rolling and 0.42mm for the second rolling. After the two rollings are completed, the negative electrode sheet is obtained. Then cut it into a size of 9.4cm×7.7cm, cut out the shape of the tab, and weld the nickel extension tab with tab glue to the trapezoidal tab above the pole piece by a spot welding machine, such as Figure 2 The schematic diagram of the negative electrode of the zinc-nickel battery is shown in FIG. Finally, a layer of PP diaphragm is coated around the negative electrode plate to fully cover the reaction surface area of ​​the plate. The prepared negative electrode of the zinc-nickel battery is as shown in FIG. Figure 3 As shown;

[0065] The prepared negative electrode sheet was assembled with a commercial positive electrode into a zinc-nickel battery, and the full battery was subjected to a full battery cycle test at an 8C discharge rate and a DOD of 8%.

[0066] The following examples and comparative examples are expressed in the same way.

[0067] The viscosity of the prepared slurry is about 10000mPa·s and the density is 2.10g / cm 3 , the fineness is 38μm, and the slurry is evenly dispersed, which is beneficial to improving the coating conditions and enhancing the stability of the electrode.

[0068] The prepared negative electrode loading capacity is 110.5 mg / cm 2 The assembled full battery discharge capacity reached 425.8mAh / g, and it cycled stably for more than 3500 times at a high discharge rate of 8C, showing excellent stability. In addition, we also compared the electrode of the present invention with the electrode of the market. Figure 5 As can be seen, commercially available electrodes can barely sustain high-rate cycling, with the first cycle voltage already very low. Furthermore, the coulombic efficiency of commercially available electrodes is unstable, fluctuating significantly after 600 cycles, with an average coulombic efficiency below 80%. In comparison, the electrode of the present invention exhibits superior stability, with a coulombic efficiency exceeding 93%.

[0069] The discharge specific capacity is obtained from the test system in Table 3, specifically the discharge specific capacity measured in step 5.

[0070] The cycle test method is shown in Table 4: First, the first step is 13.82mA / cm2 Constant current charging to 1.9V is switched to constant voltage charging. The jump condition is time ≥ 5h or current ≤ 0.05A. The second step is to stand for 10s. The third step is 138.16mA / cm 2 Constant current discharge, the jump condition is time ≥ 36s or voltage ≤ 0.7V, the fourth step is to stand for 30s, the fifth step is 27.63mA / cm 2 After constant current charging reaches 1.9V, switch to constant voltage charging. The jump condition is time ≥ 5min or current ≤ 0.2A, and then cycle according to steps 2 to 5.

[0071] Example 2:

[0072] Compared with Example 1, this example is different in that the polyvinyl alcohol solution is replaced by a polyethylene oxide (PEO) aqueous solution.

[0073] The viscosity of the prepared slurry is about 10000mPa·s and the density is 2.11g / cm 3 The fineness is 39μm, and the slurry is evenly dispersed, which is beneficial to improving the coating conditions and enhancing the stability of the electrode. The prepared negative electrode loading is 109.8mg / cm 2 The assembled full-battery discharge capacity reached 405.2mAh / g, and it could be stably cycled for more than 2500 cycles at a high discharge rate of 8C.

[0074] Example 3:

[0075] Compared with Example 1, the difference of this example is that the polyvinyl alcohol solution is replaced by a polyethylene-vinyl acetate copolymer (EVA) aqueous solution.

[0076] The viscosity of the prepared slurry is about 10000mPa·s and the density is 2.09g / cm 3 The fineness is 38μm, and the slurry is evenly dispersed, which is beneficial to improving the coating conditions and enhancing the stability of the electrode. The prepared negative electrode loading is 109.6mg / cm 2 The assembled full-battery discharge capacity reached 406.9mAh / g, and it could be stably cycled for more than 2400 cycles at a high discharge rate of 8C.

[0077] Example 4:

[0078] Compared with Example 1, the difference of this example is that the 3% sodium carboxymethyl cellulose aqueous solution is replaced by a 2% sodium carboxymethyl cellulose aqueous solution.

[0079] The viscosity of the prepared slurry is about 9000 mPa·s and the density is 2.02 g / cm 3The fineness is 36μm, and the slurry is evenly dispersed, which is beneficial to improving the coating conditions and enhancing the stability of the electrode. The prepared negative electrode loading is 102.9mg / cm 2 The assembled full-battery discharge capacity reached 410.6mAh / g, and it could be stably cycled for more than 2800 cycles at a high discharge rate of 8C.

[0080] Example 5:

[0081] Compared with Example 1, the difference of this example is that the 3% sodium carboxymethyl cellulose aqueous solution is replaced by a 5% sodium carboxymethyl cellulose aqueous solution.

[0082] The viscosity of the prepared slurry is about 11000mPa·s and the density is 2.23g / cm 3 The fineness is 37μm, and the slurry is evenly dispersed, which is beneficial to improving the coating conditions and enhancing the stability of the electrode. The prepared negative electrode loading is 115.1mg / cm 2 The assembled full battery discharge capacity reaches 419.5 mAh / g. As shown in Figure 6, the voltage, current-time diagram and coulombic efficiency-cycle number diagram of this embodiment are displayed. It can be seen that the stable cycle exceeds 3500 cycles at a high discharge rate of 8C, and its coulombic efficiency is higher than 92%, so this embodiment is one of the preferred examples.

[0083] Example 6:

[0084] Compared with Example 1, the difference of this embodiment is that the weight portion of colloidal graphite is 3 parts.

[0085] The viscosity of the prepared slurry is about 10500mPa·s and the density is 2.13g / cm 3 The fineness is 38μm, and the slurry is evenly dispersed, which is beneficial to improving the coating conditions and enhancing the stability of the electrode. The negative electrode loading capacity prepared is 112.3mg / cm 2 ,The assembled full battery discharge capacity reaches 422.3mAh / g, and, Figure 7 The voltage, current-time graph and coulombic efficiency-cycle number graph of this embodiment are shown. It can be seen that it can stably cycle for more than 3500 cycles at a high discharge rate of 8C, and the coulombic efficiency is higher than 91%, so this embodiment is one of the preferred examples.

[0086] Example 7:

[0087] Compared with Example 1, the difference of this example is that: 1 part of an SBR aqueous solution with an SBR solid content of 50% is used.

[0088] The viscosity of the prepared slurry is about 10000mPa·s and the density is 2.08g / cm 3The fineness is 36μm, and the slurry is evenly dispersed, which is beneficial to improving the coating conditions and enhancing the stability of the electrode. The prepared negative electrode loading is 108.1mg / cm 2 The assembled full-battery discharge capacity reached 415.6mAh / g, and it could be stably cycled for more than 2800 cycles at a high discharge rate of 8C.

[0089] Example 8:

[0090] Compared with Example 1, the difference of this example is that: 6 parts of an SBR aqueous solution with an SBR solid content of 50% are used.

[0091] The viscosity of the prepared slurry is about 11000mPa·s and the density is 2.14g / cm 3 The fineness is 40μm, and the slurry is evenly dispersed, which is beneficial to improving the coating conditions and enhancing the stability of the electrode. The prepared negative electrode loading is 112.2mg / cm 2 The assembled full-battery discharge capacity reached 416.2mAh / g, and it could be stably cycled for more than 2800 cycles at a high discharge rate of 8C.

[0092] Example 9:

[0093] Compared with Example 1, the difference of this example is that the weight portion of the PTFE aqueous solution with a PTFE resin solid content of 60% is 3 parts.

[0094] The viscosity of the prepared slurry is about 10500mPa·s and the density is 2.10g / cm 3 The fineness is 37μm, and the slurry is evenly dispersed, which is beneficial to improving the coating conditions and enhancing the stability of the electrode. The prepared negative electrode loading is 109.9mg / cm 2 The assembled full-battery discharge capacity reached 415.7mAh / g, and it could be stably cycled for more than 2500 cycles at a high discharge rate of 8C.

[0095] Example 10:

[0096] Compared with Example 1, the difference of this example is that the weight portion of the PTFE aqueous solution with a PTFE resin solid content of 60% is 5 parts.

[0097] The viscosity of the prepared slurry is about 9500mPa·s and the density is 2.15g / cm 3 The fineness is 40μm, and the slurry is evenly dispersed, which is beneficial to improving the coating conditions and enhancing the stability of the electrode. The prepared negative electrode loading is 112.6mg / cm 2 The assembled full-battery discharge capacity reached 414.8mAh / g, and it could be stably cycled for more than 2500 cycles at a high discharge rate of 8C.

[0098] Example 11:

[0099] Compared with Example 1, this embodiment is different in that the negative electrode additives are metallic element Sn powder and indium hydroxide.

[0100] The viscosity of the prepared slurry is about 10000mPa·s and the density is 2.09g / cm 3 The fineness is 38μm, and the slurry is evenly dispersed, which is beneficial to improving the coating conditions and enhancing the stability of the electrode. The prepared negative electrode loading is 110.2mg / cm 2 The assembled full-battery discharge capacity reaches 418.4mAh / g, and it can be stably cycled for more than 3000 cycles at a high discharge rate of 8C.

[0101] Example 12:

[0102] Compared with Example 1, this embodiment is different in that the negative electrode additives are bismuth oxide and indium hydroxide.

[0103] The viscosity of the prepared slurry is about 10000mPa·s and the density is 2.10g / cm 3 The fineness is 37μm, and the slurry is evenly dispersed, which is beneficial to improving the coating conditions and enhancing the stability of the electrode. The prepared negative electrode loading is 110.7mg / cm 2 The assembled full-battery discharge capacity reached 413.8mAh / g, and it could be stably cycled for more than 2800 cycles at a high discharge rate of 8C.

[0104] Example 13:

[0105] Compared with Example 1, the difference of this embodiment is that: in step (3), the particles are dispersed with high-speed stirring at 2000 r / min.

[0106] The viscosity of the prepared slurry is about 10500mPa·s and the density is 2.09g / cm 3 The fineness is 38μm, and the slurry is evenly dispersed, which is beneficial to improving the coating conditions and enhancing the stability of the electrode. The prepared negative electrode loading is 110.4mg / cm 2 The assembled full-battery discharge capacity reached 419.1mAh / g, and it could be stably cycled for more than 3000 cycles at a high discharge rate of 8C.

[0107] Example 14:

[0108] Compared with Example 1, the difference of this embodiment is that: in step (3), the particles are dispersed with high-speed stirring at 1500 r / min.

[0109] The viscosity of the prepared slurry is about 10000mPa·s and the density is 2.10g / cm3 The fineness is 39μm, and the slurry is evenly dispersed, which is beneficial to improving the coating conditions and enhancing the stability of the electrode. The prepared negative electrode loading is 109.5mg / cm 2 The assembled full battery has a discharge capacity of 418.2 mAh / g and can be stably cycled for more than 3,000 cycles at a high discharge rate of 8C.

[0110] Comparative Example 1:

[0111] Compared with Example 1, the difference of this comparative example is that the entire polymer slurry medium is replaced by deionized water.

[0112] The viscosity of the prepared slurry is about 8500mPa·s and the density is 2.01g / cm 3 The fineness is 34μm, and the slurry is evenly dispersed, which is beneficial to improving the coating conditions and enhancing the stability of the electrode. The prepared negative electrode loading is 100.2mg / cm 2 The assembled full-battery discharge capacity reaches 403.6mAh / g, and it can be stably cycled for more than 2000 cycles at a high discharge rate of 8C.

[0113] Comparative Example 2:

[0114] Compared with Example 1, the difference of this comparative example is that the 4% polyvinyl alcohol solution in the polymer slurry medium is replaced by deionized water.

[0115] The viscosity of the prepared slurry is about 10000mPa·s and the density is 2.06g / cm 3 The fineness is 36μm, and the slurry is evenly dispersed, which is beneficial to improving the coating conditions and enhancing the stability of the electrode. The prepared negative electrode loading is 107.9mg / cm 2 The assembled full-battery discharge capacity reached 405.8mAh / g, and it could be stably cycled for more than 2,300 cycles at a high discharge rate of 8C.

[0116] Comparative Example 3:

[0117] Compared with Example 1, the difference of this comparative example is that the sodium carboxymethyl cellulose aqueous solution in the polymer slurry medium is replaced by potassium polyacrylate (PAAK) solution.

[0118] The viscosity of the prepared slurry is about 11500mPa·s and the density is 2.15g / cm 3 , the fineness is 42μm, the slurry is as Figure 4 As shown, there is a more obvious agglomeration phenomenon, which will affect the coating conditions and the stability of the electrode. The prepared negative electrode loading is 116.9 mg / cm 2The assembled full battery has a discharge capacity of 413.7 mAh / g and can be stably cycled for more than 2000 cycles at a high discharge rate of 8C.

[0119] Comparative Example 4:

[0120] Compared with Example 1, the difference of this comparative example is that the weight portion of the negative electrode additive is 0 parts.

[0121] The viscosity of the prepared slurry is about 10000mPa·s and the density is 2.10g / cm 3 The fineness is 39μm, and the slurry is evenly dispersed, which is beneficial to improving the coating conditions and enhancing the stability of the electrode. The prepared negative electrode loading is 110.1mg / cm 2 The assembled full-battery discharge capacity reached 407.9mAh / g, and it could be stably cycled for more than 1500 cycles at a high discharge rate of 8C.

[0122] Comparative Example 5:

[0123] Compared with Example 1, the difference of this comparative example is that the negative electrode additive is indium hydroxide, and the weight portion is 0.08 parts.

[0124] The viscosity of the prepared slurry is about 10000mPa·s and the density is 2.09g / cm 3 The fineness is 37μm, and the slurry is evenly dispersed, which is beneficial to improving the coating conditions and enhancing the stability of the electrode. The prepared negative electrode loading is 111.4mg / cm 2 The assembled full-battery discharge capacity reached 409.4 mAh / g, and it could be stably cycled for more than 1,800 cycles at a high discharge rate of 8C.

[0125] Comparative Example 6:

[0126] Compared with Example 1, the difference of this comparative example is that the weight portion of the SBR aqueous solution with an SBR solid content of 50% is 0.

[0127] The viscosity of the prepared slurry is about 10000mPa·s and the density is 2.07g / cm 3 The fineness is 36μm, and the slurry is evenly dispersed, which is beneficial to improving the coating conditions and enhancing the stability of the electrode. The prepared negative electrode loading is 107.3mg / cm 2 The assembled full-battery discharge capacity reached 406.2mAh / g, and it could be stably cycled for more than 2,300 cycles at a high discharge rate of 8C.

[0128] Comparative Example 7:

[0129] Compared with Example 1, the difference of this comparative example is that the weight portion of the PTFE aqueous solution with a PTFE resin solid content of 60% is 0.

[0130] The viscosity of the prepared slurry is about 10500mPa·s and the density is 2.10g / cm 3 The fineness is 36μm, and the slurry is evenly dispersed, which is beneficial to improving the coating conditions and enhancing the stability of the electrode. The prepared negative electrode loading is 106.8mg / cm 2 The assembled full battery has a discharge capacity of 405.2 mAh / g and can be stably cycled for more than 2000 cycles at a high discharge rate of 8C.

[0131] Comparative Example 8:

[0132] Compared with Example 1, the difference of this comparative example is that the preparation method comprises the following steps:

[0133] Step (1): preparing a polymer slurry medium: preparing different solutions of the polymer slurry medium in advance, mixing and stirring the different solutions to obtain a polymer slurry medium:

[0134] Step (3): Slurry preparation: solid active material, negative electrode additive, SDBS, carbon material, and zinc powder are added to the slurry medium, and the mixture is dispersed with high-speed stirring at 1500 r / min. Then, SBR emulsion and PTFE emulsion are added respectively and stirring is continued for 2 minutes to obtain battery negative electrode slurry.

[0135] The viscosity of the prepared slurry is about 10500mPa·s and the density is 2.11g / cm 3 The fineness is 42μm, and the slurry is evenly dispersed, which is beneficial to improving the coating conditions and enhancing the stability of the electrode. The prepared negative electrode loading is 111.9mg / cm 2 The assembled full-battery discharge capacity reached 414.2mAh / g, and it could be stably cycled for more than 2000 cycles at a high discharge rate of 8C.

[0136] Comparative Example 9:

[0137] Compared with Example 1, the difference of this comparative example is that: in step (3), the stirring is carried out at a stirring speed of 1000 r / min.

[0138] The viscosity of the prepared slurry is about 10000mPa·s and the density is 2.08g / cm 3 The fineness is 43μm, and the slurry is evenly dispersed, which is beneficial to improving the coating conditions and enhancing the stability of the electrode. The prepared negative electrode loading is 111.3mg / cm 2 The assembled full battery has a discharge capacity of 412.2 mAh / g and can be stably cycled for more than 2000 cycles at a high discharge rate of 8C.

[0139] Comparative Example 10:

[0140] Compared with Example 1, the difference of this comparative example is that: in step (3), the mixture is dispersed with high-speed stirring at 2500 r / min.

[0141] The viscosity of the prepared slurry is about 10000mPa·s and the density is 2.12g / cm 3 The fineness is 38μm, and the slurry is evenly dispersed, which is beneficial to improving the coating conditions and enhancing the stability of the electrode. The prepared negative electrode loading is 109.4mg / cm 2 The assembled full-battery discharge capacity reached 413.2mAh / g, and it could be stably cycled for more than 2500 cycles at a high discharge rate of 8C.

[0142] Comparative Example 11:

[0143] Compared with Example 1, the difference of this comparative example is that the weight portion of colloidal graphite is 0 parts.

[0144] The viscosity of the prepared slurry is about 10000mPa·s and the density is 2.11g / cm 3 The fineness is 38μm, and the slurry is evenly dispersed, which is beneficial to improving the coating conditions and enhancing the stability of the electrode. The prepared negative electrode loading is 110.6mg / cm 2 The assembled full battery has a discharge capacity of 410.8 mAh / g and can be stably cycled for more than 2000 cycles at a high discharge rate of 8C.

[0145] The slurry parameters of the embodiments and comparative examples of the present application are shown in Table 1 below, the electrode parameters and full battery performance are shown in Table 2, the discharge specific capacity test system is shown in Table 3 below, and the cycle test system is shown in Table 4 below.

[0146] Table 1. Slurry parameters of the examples and comparative examples of the present application

[0147]

[0148] The viscosity test is performed using a rotational viscometer. First, ensure that the sample temperature is maintained at 23±0.5°C. Then, start the viscometer rotor and read the value after the viscometer reading stabilizes. Take two samples and test them until the difference between the values ​​of the two samples tested consecutively is less than 3%. The average of the two values ​​is taken, referring to the single-cylinder rotation method in "GB / T 2794-2022 Determination of viscosity of adhesives";

[0149] The fineness test is carried out using a QXC single-slot scraper fineness meter with a range of 150μm. The test is carried out in accordance with the national standard "GB / T 6753.1-2007 Paints, varnishes and printing inks - Determination of fineness of grinding". Figure 8 This is a schematic diagram of the slurry fineness test in Example 1;

[0150] Table 2. Table of pole piece parameters and full battery performance of the examples and comparative examples of the present application

[0151]

[0152]

[0153] Table 3. Full battery capacity test system

[0154]

[0155] Table 4 Full battery cycle test system

[0156]

[0157] While the embodiments of the present invention have been described in detail above, the present invention is not limited to the described embodiments. It will be apparent to those skilled in the art that various changes, modifications, substitutions, and variations to these embodiments, without departing from the principles and spirit of the present invention, are still within the scope of protection of the present invention.

Claims

1. A method for preparing a negative electrode for a zinc-nickel battery, characterized in that: The steps include: Step (1): Mixing the negative electrode powder: fully mix the solid negative electrode active material and the negative electrode additive to obtain a negative electrode mixed powder; then pre-mix the required zinc powder and carbon material; Step (2): preparing a polymer slurry medium: preparing different solutions in the polymer slurry medium in advance, mixing and stirring the different solutions to obtain a polymer slurry medium; Step (3): Slurry preparation: add the surfactant sodium dodecylbenzenesulfonate SDBS aqueous solution to the polymer slurry medium and stir evenly, then slowly pour the negative electrode mixed powder into it, and stir at high speed to break it up to prevent the negative electrode mixed powder from agglomerating after contacting the polymer slurry medium; then add SBR emulsion and PTFE emulsion respectively, and finally add zinc powder and carbon material mixed powder to prepare the battery negative electrode slurry; The high-speed stirring speed is 1500-2000r / min; Step (4): negative electrode preparation: coating, drying, rolling, cutting, welding and extending the tabs and coating the diaphragm to prepare the negative electrode of the zinc-nickel battery; The polymer slurry medium is formed by mixing a polymer matrix and a base reinforcing agent; the polymer matrix is ​​selected from one of a polyvinyl alcohol (PVA) aqueous solution, a polyethylene oxide (PEO) aqueous solution, and a polyethylene-vinyl acetate copolymer (EVA) aqueous solution; the base reinforcing agent is an aqueous solution of carboxymethyl cellulose (CMC); the mass ratio of the polymer matrix to the base reinforcing agent is (20-25): (1-10); The concentration of the polymer matrix is ​​2% to 5%, and the concentration of the base reinforcing agent is 2% to 5%; The SBR emulsion is an SBR aqueous solution with an SBR solid content of 50%; The PTFE emulsion is a PTFE aqueous solution with a PTFE resin solid content of 60%; The carbon material is one or more of colloidal graphite with a lamellar structure, graphene, conductive carbon black with a porous structure, and carbon nanotubes; The negative electrode additive is a combination of metallic elemental Bi powder or Sn powder and indium hydroxide, with a weight ratio of (1-4): (0.05-2).

2. A method for preparing a negative electrode for a zinc-nickel battery as claimed in claim 1, characterized in that: The step (4) specifically includes the following: coating the prepared slurry on the punched tin-plated copper strip substrate, specifically pre-pressing the punched tin-plated copper strip substrate to a thickness of 0.70-0.80 mm, then coating the slurry on the punched tin-plated copper strip and setting the scraper gap to 0.75 mm to perform scraping and integration to obtain a punched tin-plated copper strip evenly coated with the slurry; then drying the coated punched tin-plated copper strip at 60-80°C for 1-4 hours, then rolling it twice on a roller press, and obtaining a negative electrode sheet after the two rolling processes; then cutting it into a specific shape and size, and welding the nickel extended tab with tab glue to the cut trapezoidal tab by a spot welding machine, and finally wrapping a layer of PP diaphragm around the negative electrode sheet to fully cover the reaction surface area of ​​the negative electrode sheet, thereby finally obtaining a zinc-nickel battery negative electrode.

3. A method for preparing a negative electrode for a zinc-nickel battery according to claim 1, characterized in that: The solid negative electrode active material is zinc oxide.

4. A zinc-nickel battery negative electrode, characterized in that: The negative electrode of the zinc-nickel battery is prepared by the preparation method of any one of claims 1 to 3.

5. A zinc-nickel battery negative electrode as claimed in claim 4, characterized in that: It comprises the following components in parts by weight: 50-70 parts of solid negative electrode active material 8-15 parts zinc powder 2-8 parts of negative electrode additive 1-5 parts of carbon material 0.3-0.7 parts of sodium dodecylbenzenesulfonate SDBS aqueous solution 20~30 parts of polymer slurry medium 1-6 parts SBR emulsion 3-5 parts of PTFE emulsion.

6. A zinc-nickel battery, characterized in that: The nickel-zinc battery is assembled from the negative electrode of the nickel-zinc battery according to claim 4 or 5 and the positive electrode of the nickel-zinc battery.

Images