Zinc phosphide negative electrode material and preparation method and application thereof

Abstract

The application provides a zinc phosphide negative electrode material, which comprises a zinc sheet substrate and a zinc phosphate protective layer; the zinc phosphate protective layer is obtained in situ on the surface of the zinc sheet by immersing the zinc sheet in a phosphoric acid solution; the phosphoric acid solution comprises phosphoric acid, zinc oxide, sodium fluoride, zinc nitrate, sodium perchlorate, organic ammonium and ammonia water. The zinc phosphide negative electrode material has good reversible deposition / dissolution performance, excellent energy storage performance, high stability and can be stably cycled for a long time.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of electrochemical energy storage materials, in particular to a zinc phosphide negative electrode material and a preparation method and application thereof. BACKGROUND

[0002] With the development of modern economy, energy and environmental problems, as bottlenecks restricting the development of the national economy, are two major problems faced by the current social development. Vigorously developing and using clean and renewable energy such as wind energy and solar energy is the source of power to promote and realize sustainable development, and developing safe and environmentally friendly large-scale energy storage technology is an important technical support for the full use of renewable energy. As a kind of efficient energy storage and conversion equipment, rechargeable batteries are expected to meet the huge market demand of renewable energy storage systems. At present, lithium ion batteries (LIBs) are widely used in electronic devices and transportation power due to their high energy density and high output voltage. However, the scarcity of lithium resources, high processing cost, flammable and toxic organic electrolyte and other problems hinder the application of LIBs in large-scale energy storage devices. Therefore, the development of high specific energy and high safety aqueous secondary batteries has attracted widespread attention from researchers.

[0003] In recent years, zinc ion batteries with zinc metal as the negative electrode have attracted great interest from researchers due to their environmental protection, safety and low cost. Compared with lithium metal, zinc is the second most abundant metal on earth after iron, and the theoretical capacity of zinc reaches 819 mA h / g, which has objective application prospect in the field of energy storage. At present, the main negative electrode materials of zinc ion batteries include zinc metal sheet, zinc powder electrode and electroplated zinc negative electrode. However, the deposition / dissolution process occurs in the charging and discharging process of zinc negative electrode, and in this process, zinc negative electrode is easy to form dendrites and "dead zinc". The growth of dendrites will trigger adverse side reactions such as hydrogen evolution reaction and electrode passivation, thereby leading to the performance degradation of the battery. When the dendrites are serious, they will also pierce the separator and contact the positive electrode, causing internal short circuit of the battery and leading to the failure of the battery. Therefore, how to inhibit the formation of dendrites is a problem to be solved to improve the stability of zinc negative electrode.

[0004] Zinc metal phosphating is an effective means to improve the stability of zinc negative electrode. However, at present, zinc phosphate coating is more widely used in the field of zinc metal corrosion protection, mainly to protect zinc metal from corrosion in air and water, prolong the service life of zinc metal, and has not involved any research on its electrochemical performance. For example, Chinese patents CN104087920B and CN101289742B form a phosphating film by first placing zinc metal in a phosphating solution, then spraying a coating on the phosphating film to improve the adhesion of the coating on the zinc metal, and achieve corrosion protection of the zinc metal; Chinese patent CN116096945A can obtain a corrosion-resistant zinc phosphate coating through a phosphating solution, but an activating additive needs to be added in the preparation process, and a large amount of organic compounds such as styrene and olefin compounds are added in the activating additive, which will cause environmental pollution, and the treatment of phosphating waste liquid in the later stage will also be more difficult. At present, there is no report on the research of zinc phosphate on zinc negative electrode. The present application adopts an original method to in-situ synthesize zinc negative electrode material with zinc phosphate protective layer, inhibit dendrite formation, and achieve the purpose of improving the stability of zinc negative electrode material, which will be beneficial to the development of high-performance aqueous zinc ion battery and promote the development of this field. SUMMARY

[0005] The present application provides a kind of phosphating zinc negative electrode material, it has better reversible deposition / dissolution performance, energy storage performance is excellent, simultaneously has high stability, can long time stable circulation.

[0006] The present application is realized by the following technical scheme:

[0007] A kind of phosphating zinc negative electrode material, including zinc sheet substrate and zinc phosphate protective layer;The zinc phosphate protective layer is obtained by in-situ generation on the surface of the zinc sheet by immersing the zinc sheet in phosphoric acid solution;The phosphoric acid solution includes phosphoric acid, zinc oxide, sodium fluoride, zinc nitrate, sodium perchlorate, organic ammonium, ammonia.

[0008] Preferably, the microstructure of the zinc phosphate protective layer is a uniform and dense nanosheet structure, the thickness of the nanosheet is 20-90 nm, and the diameter is 4-8 μm.

[0009] Preferably, in the phosphoric acid solution, the molar ratio of phosphoric acid to zinc oxide is 1:1-3;The molar ratio of sodium perchlorate to organic ammonium is 3-5:1;The molar ratio of phosphoric acid to ammonia is 1:2-3.

[0010] Preferably, the concentration of phosphoric acid in the phosphoric acid solution is 0.01-0.1 mol / L; the concentration of zinc oxide is 0.01-0.3 mol / L; the concentration of sodium fluoride is 0.01-0.05 mol / L; the concentration of sodium perchlorate is 0.02-0.03 mol / L; the concentration of organic ammonium is 0.005-0.01 mol / L; the concentration of zinc nitrate is 0.1-0.2 mol / L; and the concentration of ammonia is 0.02-0.2 mol / L.

[0011] Preferably, the pH value of the phosphoric acid solution ranges from 1 to 4.

[0012] The application also provides a preparation method of the zinc phosphide negative electrode material.

[0013] S1. The surface of the zinc sheet is sequentially cleaned with dilute hydrochloric acid, deionized water and ethanol for a period of time, and the cleaned zinc sheet is immersed in anhydrous ethanol for use;

[0014] S2. The cleaned zinc sheet is immersed in a phosphoric acid solution for reaction, and a zinc phosphate protective layer is formed on the surface of the zinc sheet. After the zinc sheet with the protective layer is taken out and dried, the zinc phosphide negative electrode material is obtained.

[0015] Preferably, in the step S1, the cleaning time of the zinc sheet in each cleaning solution is 5-30 min.

[0016] Preferably, the concentration of the dilute hydrochloric acid is 1-4 mol / L.

[0017] Preferably, in the step S2, the reaction temperature is 30-70℃; the reaction time is 30-180 s; and the drying temperature is 60-70℃.

[0018] In the application, the zinc sheet substrate, phosphoric acid and zinc oxide are the main reactants. Specifically, the zinc sheet substrate reacts with phosphoric acid as a zinc source, and zinc oxide participates in the reaction as a supplementary zinc source during the reaction of phosphoric acid and the zinc sheet substrate. In order to ensure that the reaction can be fully carried out, the molar ratio of phosphoric acid to zinc oxide is set to 1:1-3. The phosphating principle mainly utilizes the reaction of zinc and phosphoric acid under certain conditions, and the reaction equation is as follows:

[0019] 3Zn+2H3PO4+4H2O=Zn3(PO4)2.4H2O+3H2

[0020] Meanwhile, the molar ratio of phosphoric acid to ammonia water in the phosphoric acid solution is set to 1:2-3, so as to adjust the pH of the phosphoric acid solution to a suitable range, so that the phosphating reaction can occur smoothly; the molar ratio of sodium perchlorate to organic ammonium added is 3-5:1, which not only makes the addition of the two not cause a large pH change of the phosphoric acid solution, but also provides a relatively stable reaction environment for the phosphating reaction, better controls the reaction rate and adjusts the morphology and growth uniformity of the Zn3(PO4)2.4H2O protective layer; in addition, sodium fluoride and zinc nitrate can further adjust the reaction rate, combined with the adjustment of the reaction temperature and reaction time, so that the phosphating reaction can proceed at the optimal reaction rate, the structure and morphology of the Zn3(PO4)2.4H2O product are optimized, and thus the Zn3(PO4)2.4H2O protective layer with uniform deposition and uniform size is obtained.

[0021] The present application adjusts the concentration and ratio of each component in the phosphoric acid solution, and adjusts the pH, reaction temperature and reaction time, so as to adjust the morphology and structure of the zinc phosphate product, the deposition uniformity on the surface of the zinc sheet substrate and the bonding strength with the zinc sheet substrate, thereby synthesizing the Zn3(PO4)2.4H2O protective layer which can effectively adjust the deposition behavior of zinc metal on the electrode surface, make the zinc metal uniformly deposited, and inhibit the formation of zinc dendrites; at the same time, since the Zn3(PO4)2.4H2O itself is insoluble in water and has good corrosion resistance, the passivation and corrosion generated in the hydrogen evolution side reaction process of the zinc negative electrode can be avoided, the corrosion resistance of the zinc negative electrode material is enhanced, thereby obtaining a high-stability zinc negative electrode material and prolonging the service life.

[0022] The present application also provides the application of the above-mentioned any zinc phosphating negative electrode material or the zinc phosphating negative electrode material obtained by the above-mentioned any preparation method in the preparation of a water-based zinc ion battery.

[0023] Compared with the prior art, the present application has the following beneficial effects:

[0024] (1) Compared with coating zinc phosphate on zinc metal, the zinc phosphate protective layer of the present application is generated in situ on the surface of the zinc sheet substrate as a zinc source, has a smaller size, a moderate thickness and a better bonding strength with the substrate, and the protective layer is not easy to fall off. The zinc phosphate protective layer not only can induce the uniform deposition of zinc metal, inhibit the nucleation and growth of zinc dendrites, but also can improve the corrosion resistance of the zinc negative electrode material, thereby improving the stability of the zinc negative electrode, so that the zinc phosphating negative electrode material obtained can be stably cycled for more than 700 hours, has a long service life, and has a coulomb efficiency close to 100%. At the same time, the zinc negative electrode material also has high capacity and good rate performance.

[0025] (2) The zinc phosphate protective layer of the present application is synthesized by soaking in a solution, which not only has a very simple reaction process, but also has a short synthesis time, and can realize high-efficiency preparation of the zinc phosphide negative material. The present application does not need to add an external binder and a conductive agent during preparation of the zinc phosphide negative material. The provided preparation method is not only simple in operation, but also low in cost, low in energy consumption and environmentally friendly, can meet large-area and large-batch preparation, and is suitable for industrial application. BRIEF DESCRIPTION OF DRAWINGS

[0026] Figure 1 Fig. (a) is a scanning electron microscope (SEM) picture of the zinc phosphide negative material (Zn@Zn3(PO4)2.4H2O) in Example 1, (b) is a picture of Zn in Comparative Example 1, and (c) is a picture of Zn@Zn3(PO4)2.4H2O in Example 1.

[0027] Figure 2 Fig. is an XRD chart of Zn and Zn@Zn3(PO4)2.4H2O in Example 1.

[0028] Figure 3 Fig. is a picture of Zn and Zn@Zn3(PO4)2.4H2O in Example 1 during zinc metal deposition.

[0029] Figure 4 Fig. is a charge-discharge curve of Zn and Zn@Zn3(PO4)2.4H2O in Example 1 under different current densities.

[0030] Figure 5 Fig. is a cycle life curve of Zn@Zn3(PO4)2.4H2O in Example 1. DETAILED DESCRIPTION

[0031] The present application will be further described below in conjunction with specific examples, but the examples do not limit the present application in any form. Unless otherwise specified, the raw materials and reagents used in the examples of the present application are conventional commercially available products and have not been subjected to any form of treatment.

[0032] Example 1

[0033] A zinc phosphide negative material comprises a zinc sheet substrate and a zinc phosphate protective layer. The zinc phosphate protective layer is obtained by in-situ generation on the surface of the zinc sheet by soaking the zinc sheet in a phosphoric acid solution. The phosphoric acid solution comprises 0.015 mol / L phosphoric acid, 0.03 mol / L zinc oxide, 0.04 mol / L sodium fluoride, 0.1 mol / L zinc nitrate, 0.028 mol / L sodium perchlorate, 0.007 mol / L organic ammonium, and 0.03 mol / L ammonia water. In the phosphoric acid solution, the molar ratio of phosphoric acid to zinc oxide is 1:2, the molar ratio of sodium perchlorate to organic ammonium is 4:1, and the molar ratio of phosphoric acid to ammonia water is 1:2. The pH value of the phosphoric acid solution is 2-3.

[0034] A preparation method of a zinc phosphide negative electrode material, comprising the following steps:

[0035] S1. The surface of a zinc sheet (2 cm x 3 cm) is sequentially cleaned by ultrasonic cleaning with 3 mol / L dilute hydrochloric acid, deionized water and ethanol for 10 min, and the cleaned zinc sheet is immersed in anhydrous ethanol for use;

[0036] S2. The cleaned zinc sheet is immersed in a phosphoric acid solution for reaction, the reaction temperature is 40°C, and the reaction time is 60 s, to obtain a zinc phosphate protective layer formed on the surface of the zinc sheet, and the zinc sheet with the protective layer is taken out and dried at 60°C to obtain the zinc phosphide negative electrode material.

[0037] Performance test: as shown in Figure 1 (a), field emission scanning electron microscopy test finds that the surface of Zn@Zn3(PO4)2.4H2O is a uniform and dense nanosheet structure, the thickness of the nanosheet is 20-50 nm, and the diameter is 5 μm. As shown in Figure 1 (b) and (c), the real photos show that the surface of the zinc sheet before phosphating is silver-white and shiny, and the surface of the zinc sheet after phosphating is covered with a uniform gray protective layer.

[0038] As shown in Figure 2 , the X-ray powder diffraction pattern (XRD) shows that Zn@Zn3(PO4)2.4H2O is composed of Zn and Zn3(PO4)2.4H2O, indicating that the phosphating process successfully constructs a Zn3(PO4)2.4H2O protective layer on the surface of the Zn sheet, and the obvious diffraction peaks indicate that the protective layer has good crystallinity.

[0039] As shown in Figure 3 , during the deposition process of 0-60 min, dendrites begin to form on the surface of the Zn sheet from 10 min, and the dendrites grow rapidly, and by 60 min, a large number of dendrites have grown on the surface of the Zn sheet. The surface of Zn@Zn3(PO4)2.4H2O is protected by Zn3(PO4)2.4H2O, which induces uniform deposition of zinc metal without obvious dendrite formation, indicating that Zn@Zn3(PO4)2.4H2O has good anti-dendrite growth ability.

[0040] As shown in Figure 4 , the Zn@Zn3(PO4)2.4H2O electrode has good reversible deposition / dissolution performance due to the absence of interference from dendrite growth, and has smaller polarization performance than the Zn electrode, indicating that the Zn@Zn3(PO4)2.4H2O electrode has more excellent energy storage performance.

[0041] As shown in Figure 5As shown, it exhibits good cycle stability of Zn@Zn3(PO4)2.4H2O electrode, stable cycling over 770 hours at 2mAh cm -2 at a current density of 2mAh cm-2.

[0042] Example 2

[0043] A zinc phosphide negative electrode material, comprising a zinc sheet substrate and a zinc phosphate protective layer; the zinc phosphate protective layer is obtained by immersing the zinc sheet in a phosphoric acid solution to generate in situ on the surface of the zinc sheet. The phosphoric acid solution comprises 0.1 mol / L phosphoric acid, 0.3 mol / L zinc oxide, 0.04 mol / L sodium fluoride, 0.1 mol / L zinc nitrate, 0.03 mol / L sodium perchlorate, 0.01 mol / L organic ammonium, and 0.2 mol / L ammonia water; in the phosphoric acid solution, the molar ratio of phosphoric acid to zinc oxide is 1:3; the molar ratio of sodium perchlorate to organic ammonium is 3:1; the molar ratio of phosphoric acid to ammonia water is 1:2; and the pH value of the phosphoric acid solution is 1-2.

[0044] A preparation method of a zinc phosphide negative electrode material, comprising the following steps:

[0045] S1. The surface of the zinc sheet (2cm x 3cm) is sequentially cleaned with 3mol / L dilute hydrochloric acid, deionized water, and ethanol by ultrasonic cleaning for 10 minutes, and the cleaned zinc sheet is immersed in anhydrous ethanol for use;

[0046] S2. The cleaned zinc sheet is immersed in a phosphoric acid solution for reaction, the reaction temperature is 50℃, the reaction time is 30s, and a zinc phosphate protective layer generated on the surface of the zinc sheet is obtained. After the zinc sheet with the protective layer is taken out and dried at 60℃, a zinc phosphide negative electrode material is obtained.

[0047] Example 3

[0048] A zinc phosphide negative electrode material, comprising a zinc sheet substrate and a zinc phosphate protective layer; the zinc phosphate protective layer is obtained by immersing the zinc sheet in a phosphoric acid solution to generate in situ on the surface of the zinc sheet. The phosphoric acid solution comprises 0.035 mol / L phosphoric acid, 0.035 mol / L zinc oxide, 0.04 mol / L sodium fluoride, 0.1 mol / L zinc nitrate, 0.028 mol / L sodium perchlorate, 0.007 mol / L organic ammonium, and 0.105 mol / L ammonia water; in the phosphoric acid solution, the molar ratio of phosphoric acid to zinc oxide is 1:1; the molar ratio of sodium perchlorate to organic ammonium is 4:1; the molar ratio of phosphoric acid to ammonia water is 1:3; and the pH value of the phosphoric acid solution is 2.5-3.5.

[0049] A preparation method of a zinc phosphide negative electrode material, comprising the following steps:

[0050] S1. The surface of the zinc sheet (2 cm x 3 cm) was sequentially cleaned with 3 mol / L dilute hydrochloric acid, deionized water, and ethanol by ultrasonic cleaning for 10 min, and the cleaned zinc sheet was immersed in anhydrous ethanol for use;

[0051] S2. The cleaned zinc sheet was immersed in a phosphoric acid solution for reaction, the reaction temperature was 30℃, the reaction time was 150s, the zinc phosphate protective layer generated on the surface of the zinc sheet was obtained, and the zinc sheet with the protective layer was taken out and dried at 70℃ to obtain the zinc phosphide negative electrode material.

[0052] Example 4

[0053] A zinc phosphide negative electrode material includes a zinc sheet substrate and a zinc phosphate protective layer. The zinc phosphate protective layer is obtained by immersing the zinc sheet in a phosphoric acid solution to generate in situ on the surface of the zinc sheet. The phosphoric acid solution includes 0.05 mol / L phosphoric acid, 0.1 mol / L zinc oxide, 0.04 mol / L sodium fluoride, 0.1 mol / L zinc nitrate, 0.025 mol / L sodium perchlorate, 0.005 mol / L organic ammonium, and 0.15 mol / L ammonia water. In the phosphoric acid solution, the molar ratio of phosphoric acid to zinc oxide is 1:2, the molar ratio of sodium perchlorate to organic ammonium is 5:1, and the molar ratio of phosphoric acid to ammonia water is 1:3. The pH value of the phosphoric acid solution is 2-3.

[0054] A method for preparing a zinc phosphide negative electrode material includes the following steps:

[0055] S1. The surface of the zinc sheet (2 cm x 3 cm) was sequentially cleaned with 3 mol / L dilute hydrochloric acid, deionized water, and ethanol by ultrasonic cleaning for 10 min, and the cleaned zinc sheet was immersed in anhydrous ethanol for use;

[0056] S2. The cleaned zinc sheet was immersed in a phosphoric acid solution for reaction, the reaction temperature was 60℃, the reaction time was 60s, the zinc phosphate protective layer generated on the surface of the zinc sheet was obtained, and the zinc sheet with the protective layer was taken out and dried at 70℃ to obtain the zinc phosphide negative electrode material.

[0057] Comparative Example 1

[0058] The difference from Example 1 is that the zinc sheet is not phosphated, it is a pure zinc sheet, and only the S1 step in the preparation method of Example 1 is used to clean the pure zinc sheet.

[0059] Comparative Example 2

[0060] The difference from Example 1 is that the phosphoric acid solution comprises 0.15 mol / L phosphoric acid, 0.6 mol / L zinc oxide, 0.1 mol / L sodium fluoride, 0.3 mol / L zinc nitrate, 0.12 mol / L sodium perchlorate, 0.02 mol / L organic ammonium, and 0.6 mol / L ammonia water; in the phosphoric acid solution, the molar ratio of phosphoric acid to zinc oxide is 1:4; the molar ratio of sodium perchlorate to organic ammonium is 6:1; the molar ratio of phosphoric acid to ammonia water is 1:4; and the pH value of the phosphoric acid solution is 1-1.5. The preparation steps are consistent with those of Example 1.

[0061] Comparative Example 3

[0062] The difference from Example 1 is that the reaction temperature is 80℃ and the reaction time is 20s, and the rest of the preparation steps and the phosphoric acid solution used are consistent with those of Example 1.

[0063] Comparative Example 4

[0064] The difference from Example 1 is that no sodium perchlorate and organic ammonium are added to the phosphoric acid solution, and the pH value of the phosphoric acid solution is 1.5-2, and the rest of the components and parameters of the phosphoric acid solution and the preparation steps are consistent with those of Example 1.

[0065] The zinc negative electrode materials of Examples 2-4 and Comparative Examples 1-4 are subjected to performance detection, and the detection results are shown in the following table:

[0066]

[0067] Obviously, the above examples of the present application are only examples for clearly illustrating the present application, and are not intended to limit the embodiments of the present application. For those skilled in the art, other different forms of changes or variations can be made on the basis of the above description. Here, it is not necessary and impossible to exhaust all the embodiments. Any modification, equivalent replacement and improvement made within the spirit and principles of the present application shall be included in the protection scope of the claims of the present application.

Claims

1. A zinc phosphide negative electrode material, characterized in that, The zinc sheet substrate and the zinc phosphate protective layer; the zinc phosphate protective layer is obtained in situ on the surface of the zinc sheet by soaking the zinc sheet in a phosphoric acid solution for reaction, and the reaction temperature is 30-70 DEG C; the phosphoric acid solution comprises phosphoric acid, zinc oxide, sodium fluoride, zinc nitrate, sodium perchlorate, organic ammonium, ammonia; in the phosphoric acid solution, the molar ratio of phosphoric acid to zinc oxide is 1:1-3; the molar ratio of sodium perchlorate to organic ammonium is 3-5:1; the molar ratio of phosphoric acid to ammonia is 1:2-3; in the phosphoric acid solution, the concentration of phosphoric acid is 0.01-0.1 mol / L; the concentration of zinc oxide is 0.01-0.3 mol / L; the concentration of sodium fluoride is 0.01-0.05 mol / L; the concentration of sodium perchlorate is 0.02-0.03 mol / L; the concentration of organic ammonium is 0.005-0.01 mol / L; the concentration of zinc nitrate is 0.1-0.2 mol / L; the concentration of ammonia is 0.02-0.2 mol / L; the micro-morphology of the zinc phosphate protective layer is a uniform and dense nanosheet structure, the thickness of the nanosheet is 20-90 nm, and the diameter is 4-8 microns.

2. The zinc phosphide negative electrode material of claim 1, wherein, The pH value of the phosphoric acid solution ranges from 1 to 4.

3. The method of claim 1, wherein the zinc phosphide negative electrode material is prepared by the steps of: The method comprises the following steps: ​ S1. The surface of the zinc sheet is sequentially cleaned with dilute hydrochloric acid, deionized water and ethanol for a period of time, and the cleaned zinc sheet is immersed in anhydrous ethanol for use; S2. The cleaned zinc sheet is immersed in a phosphoric acid solution for reaction to obtain a zinc phosphate protective layer generated on the surface of the zinc sheet, and the zinc sheet with the protective layer is taken out and dried to obtain a zinc phosphide negative electrode material.

4. The method of claim 3, wherein the zinc phosphide negative electrode material is prepared by the process of claim 1 or 2. In the step S1, the cleaning time of the zinc sheet in each cleaning solution is 5-30 min.

5. The method for preparing the zinc phosphide negative electrode material according to claim 4, wherein: The concentration of the dilute hydrochloric acid is 1-4 mol / L.

6. The method of claim 3, wherein the zinc phosphide negative electrode material is prepared by the steps of: In the step S2, the reaction temperature is 30-70 DEG C; the reaction time is 30-180 s; and the drying temperature is 60-70 DEG C. ​ 7. The use of the zinc phosphide negative electrode material of any one of claims 1-2 or the zinc phosphide negative electrode material obtained by the preparation method of any one of claims 3-6 in the preparation of a water-based zinc ion battery.

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