Zinc manganese pyrophosphate compound, method for preparing the same, and use thereof

Abstract

The application discloses a zinc manganese pyrophosphate compound, the chemical molecular formula of which is represented as (Mn 0.93 Zn 0.07 )2P2O7. A zinc salt and a manganese salt are dissolved in deionized water or an organic solvent to form a metal salt solution, the temperature of the metal salt solution is adjusted to be not higher than 10 DEG C, then pyrophosphoric acid is added into the metal salt solution, and after stirring for a period of time, centrifugal separation, washing and drying are performed to obtain the zinc manganese pyrophosphate. The zinc manganese pyrophosphate compound can be used as a positive electrode material of a zinc ion battery, and the cycle performance and rate performance of the zinc ion battery are improved.

Description

Technical Field

[0001] This invention belongs to the field of zinc-ion battery technology, specifically relating to new compounds, their preparation methods, and their applications in zinc-ion batteries. Background Technology

[0002] Aqueous zinc-ion batteries possess advantages such as safety, environmental friendliness, abundant reserves, and low cost, and are considered a promising new electrochemical energy storage system. Currently, research on zinc-ion batteries is still in its early stages, and the main obstacle to its development is the lack of cathode materials that combine high capacity and long-cycle stability. The development of cathode materials for aqueous zinc-ion batteries can refer to mature lithium-ion battery systems. In lithium-ion battery systems, three energy storage mechanisms have been extensively studied: intercalation, conversion, and alloying. In contrast, aqueous zinc-ion battery systems only have Zn... 2+ or H + / Zn 2+ Intercalation / deintercalation mechanisms have been widely reported, significantly limiting the range of cathode materials that can be selected. Furthermore, due to the high surface charge density of zinc ions, they are surrounded by 10-12 water molecules in aqueous electrolytes, forming dense and robust hydrated ionic groups. This results in slow diffusion kinetics of zinc ions within the cathode active material, leading to a specific capacity of zinc-ion batteries that is far lower than the theoretical capacity, greatly limiting the battery's cycle performance and rate performance. Summary of the Invention

[0003] The first objective of this invention is to provide a compound that can be used as a positive electrode material for zinc-ion batteries, thereby improving the cycle performance and rate performance of zinc-ion batteries.

[0004] A second objective of this invention is to provide a method for preparing the above-mentioned compound.

[0005] A third objective of this invention is to provide applications of the above-described compounds.

[0006] To achieve the first objective, the present invention provides a zinc manganese pyrophosphate compound, with the chemical formula (Mn) 0.93 Zn 0.07 2P2O7 can be used as a positive electrode material for zinc-ion batteries.

[0007] To achieve the second objective, the present invention provides a method for preparing zinc manganese pyrophosphate, comprising the following steps: dissolving zinc salt and manganese salt in deionized water or an organic solvent to form a metal salt solution, adjusting the temperature of the metal salt solution to not exceed 10°C, then adding pyrophosphate to the metal salt solution, stirring and reacting for a period of time, and then centrifuging, washing, and drying to obtain zinc manganese pyrophosphate.

[0008] In a further preferred embodiment, the zinc salt is at least one of zinc nitrate, zinc acetate, and zinc sulfate; the manganese salt is at least one of manganese nitrate, manganese acetate, and manganese sulfate; and the organic solvent is at least one of ethanol, methanol, ethylene glycol, and acetone.

[0009] In a further preferred embodiment, the concentration of the metal salt solution is 1~3 mol / L.

[0010] In a further preferred embodiment, the molar ratio of the zinc salt, manganese salt, and pyrophosphate is 0.15:2:1~2.

[0011] In a further preferred embodiment, the stirring reaction time is 5 to 10 hours.

[0012] In a further preferred embodiment, the drying temperature is 60-100°C and the time is 4-20 hours.

[0013] To achieve the third objective, the present invention provides the application of the above-mentioned zinc manganese pyrophosphate compound in zinc-ion batteries.

[0014] The present invention has the following significant technical advantages: (1) Zinc manganese pyrophosphate is a new substance synthesized in this invention, adding a new member to the field of chemical materials.

[0015] (2) The present invention synthesizes zinc manganese pyrophosphate as a positive electrode material for zinc-ion batteries, providing a new option for positive electrode materials of aqueous zinc-ion batteries.

[0016] (3) The present invention synthesizes zinc manganese pyrophosphate by a one-step liquid phase method. The process is simple and easy to implement, and has a very high tolerance for equipment.

[0017] (4) The zinc manganese pyrophosphate prepared by this invention has high phase purity, good structural uniformity and uniform particle size. As a positive electrode material for zinc-ion batteries, it can effectively improve the cycle performance and rate performance of zinc-ion batteries. Attached Figure Description

[0018] Figure 1 The (Mn) prepared in Example 1 0.93 Zn 0.07 SEM image of 2P2O7 material.

[0019] Figure 2 The (Mn) prepared in Example 1 0.93 Zn 0.07 HRTEM image of 2P2O7 material. Detailed Implementation

[0020] 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.

[0021] 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.

[0022] 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.

[0023] Example 1 0.06 mol zinc nitrate and 0.8 mol manganese nitrate were dissolved in 500 ml of deionized water to form a metal salt solution. The metal salt solution was maintained at 5 °C with continuous stirring, while 0.4 mol pyrophosphate was added dropwise. After stirring for 5 h, the solution was centrifuged, washed, and dried at 90 °C for 6 h to obtain (Mn) 0.93 Zn 0.07 )2P2O7 material.

[0024] Figure 1 The image shows a SEM image of the prepared material, which reveals that the material has a spherical morphology.

[0025] Further phase and compositional analysis was performed on the prepared material, and the results are as follows: Figure 2 As shown, analysis of the HRTEM image reveals that the material is (Mn) 0.93 Zn 0.07 )2P2O7.

[0026] Example 2 0.09 mol zinc acetate and 1.2 mol manganese sulfate were dissolved in 800 ml methanol to form a metal salt solution. The metal salt solution was maintained at 0℃ with continuous stirring, while 0.6 mol pyrophosphate was added dropwise. After stirring for 10 h, the solution was centrifuged, washed, and dried at 100℃ for 4 h to obtain (Mn). 0.93 Zn 0.07 )2P2O7 material.

[0027] Example 3 0.12 mol zinc sulfate and 1.6 mol manganese acetate were dissolved in 600 ml of ethanol to form a metal salt solution. The metal salt solution was maintained at 10 °C with continuous stirring, while 0.8 mol pyrophosphate was added dropwise. After stirring for 6 h, the solution was centrifuged, washed, and dried at 95 °C for 10 h to obtain (Mn). 0.93 Zn 0.07 )2P2O7 material.

[0028] Example 4 0.075 mol zinc sulfate and 1 mol manganese acetate were dissolved in 800 ml ethylene glycol to form a metal salt solution. The metal salt solution was maintained at 10 °C with continuous stirring, while 0.5 mol pyrophosphate was added dropwise. After stirring for 10 h, the solution was centrifuged, washed, and dried at 75 °C for 20 h to obtain (Mn). 0.93 Zn 0.07 )2P2O7 material.

[0029] Example 5 0.045 mol zinc sulfate and 0.6 mol manganese acetate were dissolved in 400 ml acetone to form a metal salt solution. The metal salt solution was maintained at 5 °C with continuous stirring, while 0.6 mol pyrophosphate was added dropwise. After stirring for 6 h, the solution was centrifuged, washed, and dried at 60 °C for 20 h to obtain (Mn). 0.93 Zn 0.07 )2P2O7 material.

[0030] The materials prepared in Examples 1-5 and manganese dioxide (purchased from Jiangsu Xianfeng Nanomaterials Technology Co., Ltd.), which is currently the most widely studied material, were used as the positive electrode material. These were 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 the solvent. The mixture was stirred at 800 rpm for 2 hours in a small beaker to obtain a slurry. The slurry was coated onto a stainless steel current collector using an automatic coating machine, placed 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. Finally, a CR2032 coin cell was assembled. This cell 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.

[0031] 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.

[0032] Table 1 As can be seen from Table 1, compared with manganese dioxide, the new material (Mn) 0.93 Zn 0.07 As a positive electrode material for zinc-ion batteries, 2P2O7 results in batteries with higher capacity retention.

[0033] 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 compound, characterized in that, The compound is zinc manganese pyrophosphate, with the chemical formula (Mn) 0.93 Zn 0.07 )2P2O7.

2. The method for preparing the compound according to claim 1, characterized in that, Includes the following steps: Zinc and manganese salts are dissolved in deionized water or organic solvents to form metal salt solutions. The temperature of the metal salt solution is adjusted to not exceed 10°C. Then, pyrophosphate is added to the metal salt solution, and after stirring and reacting for a period of time, the solution is centrifuged, washed, and dried to obtain zinc manganese pyrophosphate.

3. The preparation method according to claim 2, characterized in that, The zinc salt is at least one of zinc nitrate, zinc acetate, and zinc sulfate; the manganese salt is at least one of manganese nitrate, manganese acetate, and manganese sulfate; and the organic solvent is at least one of ethanol, methanol, ethylene glycol, and acetone.

4. The preparation method according to claim 2 or 3, characterized in that, The concentration of the metal salt solution is 1~3 mol / L.

5. The preparation method according to claim 2 or 3, characterized in that, The molar ratio of the zinc salt, manganese salt, and pyrophosphate is 0.15:2:1~2.

6. The preparation method according to claim 1, characterized in that, The stirring reaction time is 5-10 hours.

7. The preparation method according to claim 1, characterized in that, The drying temperature is 60-100℃, and the time is 4-20h.

8. The application of the compound as described in claim 1 in zinc-ion batteries.

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