Doping modified boron phosphate zinc positive electrode material and preparation method, application thereof

Abstract

The application belongs to the technical field of zinc ion battery materials, and discloses a doped modified zinc borophosphate positive electrode material and a preparation method thereof. 3‑x M x BPO7, wherein M is at least one of Ni, Mn, Cu and Co, and 0 < x < 0.5. The preparation method comprises the following steps: dissolving a zinc salt and a salt of M in deionized water or an organic solvent I to form a solution A; dissolving an organic ligand in deionized water or an organic solvent II to form a solution B; slowly adding the solution A into the solution B and stirring to react; after the reaction, centrifuging, washing and drying are performed to obtain a metal organic framework material; and the metal organic framework material is mixed with boric acid and ammonium hydrogen phosphate, and calcined to obtain the doped modified zinc borophosphate positive electrode material. The doped modified zinc borophosphate positive electrode material has excellent conductivity and an ultra-high ion diffusion rate in the actual application.

Description

Technical Field

[0001] This invention belongs to the field of zinc-ion battery material technology, specifically relating to the positive electrode material of zinc-ion batteries and its preparation method. Background Technology

[0002] Aqueous zinc-ion batteries are a new type of rechargeable battery that has been developed in recent years. They have advantages such as high energy density, high power density, efficient and safe discharge process, non-toxic and low-cost battery materials, and simple manufacturing process. They have high application value and development prospects in emerging large-scale energy storage fields such as electric vehicles and energy storage grids.

[0003] Currently, one of the main factors hindering the further development of aqueous zinc-ion batteries is the lack of suitable cathode materials. 2+ Due to the large radius of its hydrated ions, intercalation / extraction can cause irreversible deformation or even structural collapse of the cathode material, leading to rapid capacity decay. The cathode material also exhibits poor conductivity and significant electrode polarization during charging and discharging, causing the charging voltage and oxygen evolution voltage to partially overlap. During charging, the cathode material can catalyze the production of oxygen from water, resulting in battery swelling and failure. Divalent Zn... 2+ The electrostatic interaction between Zn and the crystal structure of the cathode material is too strong, leading to... 2+ Small embedded capacity, etc. Developed in Zn 2+ Cathode materials that can both increase capacity and maintain good structural stability are crucial during storage. Summary of the Invention

[0004] The main objective of this invention is to provide a doped and modified zinc borophosphate cathode material and its preparation method.

[0005] To achieve the above objectives, the present invention provides the following specific technical solutions.

[0006] First, this invention provides a doped and modified zinc borophosphate cathode material, wherein the molecular formula of the cathode material is Zn. 3-x M x BPO7, wherein M is at least one of Ni, Mn, Cu, and Co, and 0 <x≤0.5。

[0007] Secondly, the present invention provides a method for preparing the above-mentioned doped and modified zinc borophosphate cathode material, comprising the following steps: Dissolve the zinc salt and the salt of M in deionized water or organic solvent I to form solution A; Dissolve the organic ligand in deionized water or organic solvent II to form solution B; Solution A was slowly added to solution B and stirred to react. After the reaction was completed, the mixture was centrifuged, washed, and dried to obtain the metal-organic framework material. Metal-organic framework materials are mixed with boric acid and ammonium hydrogen phosphate and calcined to obtain doped and modified zinc borophosphate cathode materials.

[0008] In a further preferred embodiment, the zinc salt is at least one of zinc nitrate, zinc acetate, and zinc sulfate; the salt of M is at least one of nitrate, acetate, and sulfate. The organic ligand is one or more of 2-methylimidazole, terephthalic acid, trimesic acid, and isophthalic acid.

[0009] In a further preferred embodiment, the concentration of metal ions in solution A is 0.5-3 mol / L.

[0010] In a further preferred embodiment, the concentration of solution B is 0.3-3 mol / L.

[0011] In a further preferred embodiment, both organic solvent I and organic solvent II are at least one of methanol, ethanol, ethylene glycol, and acetone.

[0012] In a further preferred embodiment, the molar ratio of zinc salt, salt of M, and organic ligand in the reaction system formed by solutions A and B is 1:0.01~0.2:5~10.

[0013] In a further preferred embodiment, the molar ratio of the metal-organic framework material, boric acid, and ammonium hydrogen phosphate is 1:1.02 to 1.05:1.

[0014] In a further preferred embodiment, the calcination atmosphere is nitrogen or an inert atmosphere.

[0015] In a further preferred embodiment, the calcination temperature is 500~1000℃, and the calcination time is 4~10h.

[0016] Furthermore, the present invention provides a zinc-ion battery comprising the above-mentioned doped and modified zinc borophosphate cathode material.

[0017] The present invention has the following significant technical advantages: The doped and modified zinc borophosphate cathode material provided by this invention exhibits excellent conductivity and ultra-high ion diffusion rate in practical applications.

[0018] In the preparation method of the present invention, doped metal ions are introduced into the precursor by wet process, which ensures the uniform dispersion of doped metal ions in the host material and ensures the uniformity of the structure.

[0019] In the preparation method of the present invention, a metal-organic framework is used as a template to prepare a doped and modified zinc borophosphate cathode material by high-temperature sintering. The preparation process is simple and easy to implement, and is very compatible with existing equipment, without the need to develop new equipment. Attached Figure Description

[0020] Figure 1 The image shows a SEM image of the material prepared in Example 1.

[0021] Figure 2 The image shows the HRTEM image of the material prepared in Example 1.

[0022] Figure 3 The image shows the XRD pattern of the material prepared in Example 1.

[0023] Figure 4 This is a mapping diagram of Zn and Co in the material prepared in Example 1. Detailed Implementation

[0024] To facilitate understanding of the present invention, the present invention will be described more fully and in detail below with reference to the accompanying drawings and preferred embodiments, but the scope of protection of the present invention is not limited to the following specific embodiments.

[0025] Unless otherwise defined, all technical terms used herein have the same meaning as commonly understood by those skilled in the art. The technical terms used herein are for the purpose of describing particular embodiments only and are not intended to limit the scope of the invention.

[0026] Unless otherwise specified, all raw materials, reagents, instruments and equipment used in this invention can be purchased from the market or prepared by existing methods.

[0027] Example 1 Solution A was prepared by dissolving 0.04 mol zinc nitrate and 4 mmol cobalt nitrate in 50 mL deionized water. Solution B was prepared by dissolving 0.25 mol 2-methylimidazole in 100 mL deionized water. Solution A was slowly added to solution B while stirring continuously for 6 h. After centrifugation, washing, and drying, a cubic metal-doped Zn-MOF material was obtained. The metal-doped Zn-MOF was then uniformly mixed with 0.041 mol boric acid and 0.04 mol ammonium hydrogen phosphate in a solid phase and calcined at 700 °C for 4 h under a nitrogen atmosphere to obtain the Co-doped zinc borophosphate cathode material Zn. 2.73 Co 0.27 BPO7.

[0028] Figure 1 The image shows a SEM image of the material prepared in Example 1. As can be seen from the image, the material exhibits a near-spherical shape. Meanwhile, through... Figures 2-4 The phase of the material can be determined to be Zn. 2.73 Co 0.27 BPO7. Figure 2 The HRTEM image can be used to determine if the material is Zn based on the lattice spacing. 2.73 Co0.27 BPO7 phase. Furthermore, through... Figure 3 XRD analysis determined that the material's phase was Zn3BPO7. Combined with... Figure 4 The elemental distribution diagram shows that zinc and cobalt are evenly distributed and coexist within the material, indicating that the material's phase is Zn. 2.73 Co 0.27 BPO7 phase.

[0029] Comparative Example 1 The only difference between Comparative Example 1 and Example 1 is that Comparative Example 1 is not doped with Co.

[0030] 0.04 mol of zinc nitrate was dissolved in 50 ml of deionized water to form solution A. 0.25 mol of 2-methylimidazole was dissolved in 100 ml of deionized water to form solution B. Solution A was slowly added to solution B while continuously stirring for 6 hours. After centrifugation, washing, and drying, a cubic Zn-MOF material was obtained. Zn-MOF was then uniformly mixed with 0.041 mol of boric acid and 0.04 mol of ammonium hydrogen phosphate in a solid-state environment and calcined at 700 °C for 4 hours under a nitrogen atmosphere to obtain the metal-doped Zn3BPO7 zinc cathode material.

[0031] Example 2 Solution A was prepared by dissolving 0.025 mol zinc sulfate and 5 mmol nickel acetate in 50 mL methanol. Solution B was prepared by dissolving 0.25 mol terephthalic acid in 100 mL deionized water. Solution A was slowly added to solution B while stirring continuously for 8 hours. After centrifugation, washing, and drying, a cubic nickel-doped Zn-MOF material was obtained. The nickel-doped Zn-MOF was then uniformly mixed with 0.026 mol boric acid and 0.025 mol ammonium hydrogen phosphate in a solid phase and calcined at 500 °C for 10 hours under an argon atmosphere to obtain the metal-doped zinc cathode material Zn. 2.5 Ni 0.5 BPO7.

[0032] Example 3 Solution A was prepared by dissolving 0.07 mol zinc nitrate and 5 mmol copper sulfate in 50 mL ethanol. Solution B was prepared by dissolving 0.4 mol trimesic acid in 200 mL ethylene glycol. Solution A was slowly added to solution B while stirring continuously for 4 hours. After centrifugation, washing, and drying, a cubic copper-doped Zn-MOF material was obtained. The copper-doped Zn-MOF was then uniformly mixed with 0.072 mol boric acid and 0.07 mol ammonium hydrogen phosphate in a solid phase and calcined at 1000 °C for 4 hours under a nitrogen atmosphere to obtain the zinc-doped cathode material Zn. 2.8 Cu 0.2 BPO7.

[0033] Example 4 Solution A was prepared by dissolving 0.299 mol zinc acetate and 1 mmol manganese nitrate in 100 ml deionized water. Solution B was prepared by dissolving 2 mol isophthalic acid in 1000 ml acetone. Solution A was slowly added to solution B while stirring continuously for 4 hours. After centrifugation, washing, and drying, a cubic manganese-doped Zn-MOF material was obtained. The manganese-doped Zn-MOF was then uniformly mixed with 0.31 mol boric acid and 0.299 mol ammonium hydrogen phosphate in a solid phase and calcined at 800 °C for 6 hours under a nitrogen atmosphere to obtain the zinc-doped cathode material Zn. 2.99 Mn 0.01 BPO7.

[0034] Battery assembly is completed using the following method: The materials obtained in Examples 1-4 and the comparative example were used as positive electrode materials, and mixed with conductive agent acetylene black (AB) and binder polyvinylidene fluoride (PVDF) in a mass ratio of 7:2:1. Using N-methylpyrrolidone (NMP) as solvent, the mixture was stirred at 800 r / min for 2 hours in a small beaker to obtain a slurry. The slurry was coated onto a current collector stainless steel foil using an automatic coating machine, laid flat on tempered glass, and dried in a vacuum drying oven at 85°C for 4 hours. The resulting electrode sheets were then die-cut into 12 mm diameter sheets and dried in a vacuum drying oven at 105°C for 4 hours before being assembled into CR2032 coin cells. This battery uses a 16 mm diameter, 0.5 mm thick pure zinc sheet as the negative electrode, a mixture of 3M zinc sulfate and 0.05M manganese sulfate as the electrolyte, and a 18 mm diameter Whatman GF / D glass fiber membrane as the separator.

[0035] After the battery assembly was completed and aged for 12 hours, charge-discharge tests were conducted at different potentials. The discharge specific capacity of the battery after 100 cycles at a current density of 100 mA / g under a voltage of 0.8-1.9V is shown in Table 1.

[0036] Table 1 As can be seen from Table 1, doping with metal elements can improve the electrochemical performance of zinc borophosphate materials.

[0037] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for preparing a doped and modified zinc borophosphate cathode material, characterized in that, Includes the following steps: Dissolve the zinc salt and the salt of M in deionized water or organic solvent I to form solution A; Dissolve the organic ligand in deionized water or organic solvent II to form solution B; Solution A was slowly added to solution B and stirred to react. After the reaction was completed, the mixture was centrifuged, washed, and dried to obtain the metal-organic framework material. Metal-organic framework material, boric acid, and ammonium hydrogen phosphate were mixed in a molar ratio of 1:1.02 to 1.05:1 and calcined to obtain a doped and modified zinc borophosphate cathode material. The molecular formula of the positive electrode material is Zn. 3-x M x BPO7, wherein M is at least one of Ni, Mn, Cu, and Co, and 0 <x≤0.5。 2. The preparation method according to claim 1, characterized in that, The zinc salt is at least one of zinc nitrate, zinc acetate, and zinc sulfate; the salt of M is at least one of nitrate, acetate, and sulfate; and the organic ligand is one or more of 2-methylimidazole, terephthalic acid, trimesic acid, and isophthalic acid.

3. The preparation method according to claim 1 or 2, characterized in that, The concentration of metal ions in solution A is 0.5-3 mol / L; the concentration of metal ions in solution B is 0.3-3 mol / L.

4. The preparation method according to claim 1, characterized in that, Both organic solvent I and organic solvent II are at least one of methanol, ethanol, ethylene glycol, and acetone.

5. The preparation method according to claim 1 or 2, characterized in that, In the reaction system formed by solutions A and B, the molar ratio of zinc salt, salt of M, and organic ligand is 1:0.01~0.2:5~10.

6. The preparation method according to claim 1, characterized in that, The calcination atmosphere is an inert atmosphere.

7. The preparation method according to claim 1, characterized in that, The calcination temperature is 500~1000℃, and the calcination time is 4~10h.

8. A zinc-ion battery, characterized in that, The doped and modified zinc borophosphate cathode material prepared by the preparation method according to any one of claims 1-7.

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