A method for in-situ electroactivation of zinc-ion battery materials

Abstract

This invention provides a positive electrode active material for zinc-ion batteries, its preparation, and its application. First, carbon-coated nano-vanadium trioxide material is prepared. Then, the prepared carbon-coated nano-vanadium trioxide material is subjected to in-situ electrochemical activation. After activation, it is used in zinc-ion batteries. This invention activates inactive vanadium trioxide into high-valence vanadium oxide through in-situ electrochemical means, increasing a large number of oxygen vacancies and electrochemical activity, thus providing a positive electrode material for zinc-ion batteries with high specific capacity, ultra-high rate performance, low cost, and environmental friendliness.

Description

TECHNICAL FIELD

[0001] The application belongs to the field of zinc ion batteries, and particularly relates to a preparation method and in-situ electrochemical activation method of carbon-coated nano vanadium trioxide material and application of the carbon-coated nano vanadium trioxide material in a zinc ion battery. BACKGROUND

[0002] The survival and development of human society are closely related to energy, and developing large-scale energy storage technology is the consensus worldwide. Among many energy storage technologies, secondary batteries are the representative of electrochemical energy storage conversion technology. Lithium ion batteries currently occupy the main market of portable mobile electronic devices, and are rapidly developing towards the market of hybrid electric vehicles, which will greatly increase the demand for lithium and increase the cost of lithium ion batteries. On the other hand, the organic electrolyte commonly used in lithium ion batteries is flammable, and once the battery runs out of control, it may catch fire or even explode, which is a common safety problem, making people gradually consider alternatives to lithium ion batteries. Water-based zinc-based batteries can fundamentally solve the safety problem of batteries, and the abundance of zinc in the earth's crust is much higher than that of lithium, so water-based zinc ion batteries are a very promising secondary battery.

[0003] At present, the development of zinc ion batteries is restricted, and the most studied zinc ion battery cathode material is vanadium-based material. Vanadium has rich variable valence, has the highest theoretical specific capacity, and its structure is more stable than that of manganese dioxide, so it is a very potential zinc ion battery cathode material. However, the rate and cycle performance of the material still restrict its further application. In addition, the vanadium-based material currently used as an active material is in the form of tetravalent and pentavalent vanadium, and trivalent vanadium oxide itself has no electrochemical activity. It is of great attraction to find a suitable method to use vanadium trioxide as a zinc ion battery cathode material. SUMMARY

[0004] The application aims to provide a zinc ion battery cathode electrode material with high specific capacity, super-high rate performance, low cost and environmental friendliness, and an effective electrochemical in-situ activation method for improving the activity of the material.

[0005] The technical scheme of the application is as follows:

[0006] A preparation method of a zinc ion battery cathode active material, comprising the following steps:

[0007] (1) mixing a vanadium source, an organic substance and deionized water to obtain a mixed solution A;

[0008] (2) The mixed solution A of step (1) is sol-gel reacted under water bath until the solution is evaporated to dryness, and the vanadium trioxide precursor powder is obtained after vacuum drying;

[0009] (3) The precursor powder of step (2) is pre-carbonized, and after sufficient grinding, calcination is performed to obtain carbon-coated nano vanadium trioxide material;

[0010] (4) The carbon-coated nano vanadium trioxide, conductive carbon and binder are thoroughly mixed and stirred in a certain proportion to obtain slurry A;

[0011] (5) The slurry A of step (1) is blade-coated on a stainless steel mesh current collector, transferred to a vacuum oven for drying, and the electrode is obtained after drying;

[0012] (6) The dried electrode is cut and assembled into a zinc ion battery. Specifically, the cut electrode, zinc foil, glass fiber membrane and zinc trifluoromethanesulfonate electrolyte are assembled into a 2016 type button cell, and the button cell is transferred to an oven for sufficient standing after sealing treatment;

[0013] (7) The prepared button cell is placed in a battery test system, and the constant current limited capacity and voltage method is used for charging and discharging as an activation process. After activation, the battery exhibits excellent charge and discharge performance.

[0014] In step (1), the molar ratio of vanadium source to organic matter is 1:0.5-4;

[0015] In step (7), the constant current is 20-200 mA / g, the capacity is limited to 500-2000 mAh / g, and the cycle charging and discharging is performed 5-20 times at a charging cutoff voltage of 1.5-1.8 V and a discharging cutoff voltage of 0.2-0.4 V.

[0016] The concentration of vanadium source in the mixed solution A is 0.1-0.5 mol / L, preferably 0.2-0.4 mol / L.

[0017] Based on the above technical solution, preferably, the vanadium source is at least one of vanadium phosphate, ammonium metavanadate, vanadium pentoxide and lithium metavanadate;

[0018] Based on the above technical solution, preferably, the organic small molecule is one of citric acid, glucose, oxalic acid and ascorbic acid;

[0019] Based on the above technical solution, preferably, the water bath temperature of step (2) is 60-90°C, preferably 60-80°C. Since the solubility of vanadium source in water is poor, increasing the temperature can improve its solubility, produce a uniform solution, which is beneficial to the uniform reaction of vanadium pentoxide precursor solution with organic molecules.

[0020] Based on the above technical scheme, preferably, in step (2), the drying condition is 80℃ vacuum drying for 12-24h.

[0021] Based on the above technical scheme, preferably, in step (3), the pre-carbonization temperature is 200-500℃, preferably 300-400℃, and the pre-carbonization time is 3-7h. Pre-carbonization can facilitate the subsequent better crystallization growth process.

[0022] Based on the above technical scheme, preferably, in step (4), the calcination temperature is 600-800℃, preferably 700-800℃, and the calcination time is 6-10h. The calcination process can not only complete the crystal growth of nano vanadium trioxide, but also generate a carbon coating layer on the crystal surface.

[0023] Based on the above technical scheme, preferably, in step (4), the conductive carbon is one of SuperP and Ketjen black; and the binder is one of PVDF, CMC-SBR and PTFE.

[0024] Based on the above technical scheme, preferably, in step (1), the ratio is 7:2:1.

[0025] Based on the above technical scheme, preferably, in step (4), the constant current condition is 50-200mA / g.

[0026] The application also provides a zinc ion battery positive electrode active material prepared by the above preparation method. The application also provides an application of the above zinc ion battery positive electrode active material in a zinc ion battery.

[0027] Advantages

[0028] (1) In the application, vanadium source and organic matter are blended, then sol-gel reaction is carried out, and then carbon-coated vanadium trioxide material is prepared by high-temperature carbonization. The vanadium trioxide has a nano size and a 1-10nm thick carbon coating layer. After in-situ electroactivation, the electrical conductivity of the material is improved, thereby improving the rate performance of the material. The unique carbon-coated nano material is beneficial to the activation process of the current.

[0029] (2) In the application, the prepared carbon-coated vanadium trioxide is assembled into a battery, and then charging and discharging are carried out under the condition of constant current and limited capacity. In this process, in-situ electroactivation is carried out. A large number of oxygen vacancies are introduced in the activation process, and the vanadium trioxide is activated into high-valence vanadium oxide, thereby improving the activity and capacity of the composite material and being beneficial to the capacity of the material. BRIEF DESCRIPTION OF DRAWINGS

[0030] Figure 1is a TEM image of the carbon-coated vanadium trioxide nanomaterial prepared in Example 2. The prepared material has a 3 nm carbon coating layer.

[0031] Figure 2 is an XRD image of the zinc ion battery positive electrode material prepared in Example 1 and Comparative Example 1.

[0032] Figure 3 is an EPR image of the zinc ion battery positive electrode material prepared in Example 1 and Comparative Example 1. In the image, the material prepared in Example 1 exhibits abundant oxygen vacancies.

[0033] Figure 4 is a comparison of the charge-discharge curves of the zinc ion battery positive electrode material prepared in Example 1 and Comparative Example 1.

[0034] Figure 5 is a rate performance chart of the battery of Example 2.

[0035] Figure 6 is an XPS image of the electrode of Example 1 before and after activation. DETAILED DESCRIPTION

[0036] Example 1

[0037] (1) 40 mmol of ammonium metavanadate, 20 mmol of citric acid, and 200 mL of deionized water were mixed to obtain a mixed solution A, and the vanadium source concentration in the mixed solution A was 0.2 mol / L;

[0038] (2) The mixed solution A of step (1) was subjected to a sol-gel reaction at 80°C under water bath conditions until the solution was evaporated to dryness, and after vacuum drying, the vanadium trioxide material precursor powder was obtained;

[0039] (3) The powder of step (2) was pre-carbonized at 300°C under argon atmosphere for 5 h, and after sufficient grinding, calcination was performed at 700°C under argon atmosphere for 7 h to obtain the carbon-coated vanadium trioxide nanomaterial; the carbon coating layer was 3 nm thick, and the average particle size was about 200 nm.

[0040] (4) The powder of step (3), Super P, and PVDF were thoroughly mixed and stirred in a ratio of 7:2:1 to form a slurry;

[0041] (5) The slurry A of step (4) was blade-coated on a stainless steel mesh current collector, transferred to a vacuum oven for drying, and after drying, the piece was cut, assembled with zinc foil, glass fiber membrane, and zinc trifluoromethanesulfonate electrolyte into a 2016 type button cell, and after sealing treatment, the button cell was transferred to a 40°C oven and left to stand for 24 h.

[0042] (6) The coin cell from step (5) was placed in a battery testing system for activation treatment. The activation process involved a current of 100 mA / g limiting the capacity to 500 mAh / g, followed by 10 charge-discharge cycles at 0.2-1.6 V. The activated carbon-coated vanadium oxide nanoparticle electrode was obtained, and its XRD, EPR, and XPS patterns are shown below. Figure 2 , Figure 3 , Figure 6 As shown, Figure 3 In this study, by comparing the electrode with that of Comparative Example 1, it was demonstrated that the activation process introduced abundant oxygen vacancies. Figure 6 In the electrode before activation, the valence state of V can be seen to be increased, which proves the formation of high-valence vanadium oxide.

[0043] (7) The activated battery from step (6) was subjected to performance testing. The test conditions were: a constant current of 100 mA / g and a first charge-discharge cycle at a voltage of 0.4-1.4V. The resulting charge-discharge curves are shown below. Figure 4 ,Depend on Figure 4 It can be seen that the activated electrode has a reversible specific capacity of nearly 450 mAh / g, which is much higher than that of the unactivated electrode.

[0044] Example 2

[0045] (1) Mix 40 mmol ammonium metavanadate, 40 mmol citric acid and 200 mL deionized water to obtain mixed solution A, wherein the concentration of vanadium source in mixed solution A is 0.2 mol / L;

[0046] (2) The mixed solution A from step (1) is subjected to a sol-gel reaction at 90°C in a water bath until the solution evaporates to dryness. After vacuum drying, the vanadium trioxide precursor powder is obtained.

[0047] (3) The powder from step (2) was pre-carbonized at 350°C under an argon atmosphere for 5 hours, and after thorough grinding, it was calcined at 750°C under an argon atmosphere for 7 hours to obtain carbon-coated nano-vanadium trioxide material. Its TEM image is shown below. Figure 1 As shown in the figure, the carbon coating thickness is 3 nm and the average particle size is about 200 nm.

[0048] (4) Mix the powder, Super P and PVDF from step (3) thoroughly in a ratio of 7:2:1 to form a slurry;

[0049] (5) The slurry A from step (4) is scraped onto the stainless steel mesh current collector, transferred to a vacuum oven for drying, cut into pieces after drying, and assembled with zinc foil, glass fiber membrane and trifluoromethane sulfonic acid electrolyte to form a 2016 type button cell. After sealing, the button cell is transferred to a 40°C oven and left to stand for 24 hours.

[0050] (6) The button cell in step (5) is placed in a battery test system, and the capacity is limited to 2000 mAh / g at a current of 200 mA / g and cycled at a voltage of 0.2-1.6 V for 10 cycles as an activation process, to obtain a carbon-coated nano-oxide electrode after activation.

[0051] (7) The battery after activation in step (6) is subjected to performance test, and the test conditions are: constant current of 100 mA / g, first cycle charging and discharging at a voltage of 0.4-1.4 V, and the obtained battery rate performance is as shown in Figure 5

[0052] Example 3

[0053] (1) 40 mmol of ammonium metavanadate, 60 mmol of citric acid and 200 mL of deionized water are mixed to obtain a mixed solution A, and the vanadium source concentration in the mixed solution A is 0.2 mol / L;

[0054] (2) The mixed solution A in step (1) is subjected to sol-gel reaction under the condition of 85°C water bath until the solution is evaporated to dryness, and the vanadium trioxide material precursor powder is obtained after vacuum drying;

[0055] (3) The powder in step (2) is subjected to pre-carbonization treatment under argon atmosphere at 350°C for 5h, and after sufficient grinding, calcination under argon atmosphere at 800°C for 7h to obtain a carbon-coated nano-vanadium trioxide material; the carbon-coated layer has a thickness of 8 nm, and the average particle size is about 200 nm.

[0056] (4) The powder in step (3), Super P and PVDF are mixed and stirred to form a slurry in a ratio of 7:2:1;

[0057] (5) The slurry A in step (4) is coated on a stainless steel mesh current collector, transferred to a vacuum oven for drying, and after drying, the piece is cut, assembled with zinc foil, glass fiber membrane and zinc trifluoromethanesulfonate electrolyte into a 2016 type button cell, and after sealing treatment, the button cell is transferred to a 40°C oven for 24h.

[0058] (6) The button cell in step (5) is placed in a battery test system, and the capacity is limited to 500 mAh / g at a current of 100 mA / g and cycled at a voltage of 0.2-1.6 V for 10 cycles as an activation process, to obtain a carbon-coated nano-vanadium oxide electrode after activation.

[0059] (7) The battery after activation in step 6) is subjected to performance test, and the test conditions are: constant current of 100 mA / g, first cycle charging and discharging at a voltage of 0.4-1.4 V.

[0060] Example 4

[0061] ​(1) mixed 20 mmol of ammonium metavanadate, 80 mmol of citric acid and 200 mL of deionized water to obtain a mixed solution A, wherein the concentration of vanadium source in the mixed solution A is 0.1 mol / L;

[0062] (2) the mixed solution A of step (1) was subjected to a sol-gel reaction under the condition of a water bath at 85°C until the solution was evaporated to dryness, and the vanadium trioxide material precursor powder was obtained after vacuum drying;

[0063] (3) the powder of step (2) was subjected to a pre-carbonization treatment under an argon atmosphere at 350°C for 5 h, and after being fully ground, the carbon-coated nano vanadium trioxide material was obtained by calcination under an argon atmosphere at 800°C for 7 h; the thickness of the carbon coating layer is 10 nm, and the average size of the particles is about 200 nm.

[0064] (4) the powder of step (3), Super P and PVDF were fully mixed and stirred in a ratio of 7:2:1 to form a slurry;

[0065] (5) the slurry A of step (4) was blade-coated on a stainless steel mesh current collector, transferred to a vacuum oven for drying, and after drying, the piece was cut, assembled with zinc foil, glass fiber membrane and zinc trifluoromethanesulfonate electrolyte into a 2016 type button cell, and after sealing treatment, the button cell was transferred to a 40°C oven and left to stand for 24 h.

[0066] (6) the button cell in step (5) was placed in a battery test system, and after 5 cycles of cyclic charge and discharge at a current limit capacity of 1000 mAh / g under a voltage of 0.2-1.8 V as an activation process, the activated carbon-coated nano oxide electrode was obtained.

[0067] (7) the performance of the activated battery of step 6) was tested under the following conditions: 100 mA / g constant current, and the first cycle of charge and discharge was performed under a voltage of 0.4-1.4 V.

[0068] Comparative Example 1

[0069] (1) mixed 40 mmol of ammonium metavanadate, 20 mmol of citric acid and 200 mL of deionized water to obtain a mixed solution A, wherein the concentration of vanadium source in the mixed solution A is 0.2 mol / L;

[0070] (2) the mixed solution A of step (1) was subjected to a sol-gel reaction under the condition of a water bath at 80°C until the solution was evaporated to dryness, and the vanadium trioxide material precursor powder was obtained after vacuum drying;

[0071] (3) the powder of step (2) was subjected to a pre-carbonization treatment under an argon atmosphere at 300°C for 5 h, and after being fully ground, the carbon-coated nano vanadium trioxide material was obtained by calcination under an argon atmosphere at 700°C;

[0072] (4) The powder of step (3), Super P and PVDF are mixed in a ratio of 7:2:1 to form a slurry;

[0073] (5) The slurry A of step (4) is coated on a stainless steel mesh current collector, transferred to a vacuum oven for drying, and then cut into pieces. The zinc foil, glass fiber membrane, and zinc trifluoromethane sulfonate electrolyte are assembled into a 2016 type button cell. After sealing, the button cell is transferred to a 40°C oven and left for 24 hours.

[0074] (6) The button cell in step (5) is placed in a battery test system, and the unactivated carbon-coated nano vanadium trioxide electrode is subjected to charge and discharge test. The test conditions are as follows: constant current of 100 mA / g, first cycle charge and discharge at 0.4-1.4V voltage, and capacity test at 20A / g high rate.

[0075] Comparative Example 2

[0076] (1) 40 mmol of ammonium metavanadate, 60 mmol of citric acid and 200 mL of deionized water are mixed to obtain a mixed solution A, and the vanadium source concentration in the mixed solution A is 0.2 mol / L;

[0077] (2) The mixed solution A of step (1) is subjected to sol-gel reaction at 85°C water bath until the solution is evaporated to dryness, and the vanadium trioxide material precursor powder is obtained after vacuum drying;

[0078] (3) The powder of step (2) is pre-carbonized at 350°C under argon atmosphere for 5h, and then ground thoroughly. The carbon-coated nano vanadium trioxide material is obtained after calcination at 800°C under argon atmosphere for 7h. The carbon coating layer thickness is 8nm, and the average particle size is about 200nm.

[0079] (4) The powder of step (3), Super P and PVDF are mixed in a ratio of 7:2:1 to form a slurry;

[0080] (5) The slurry A of step (4) is coated on a stainless steel mesh current collector, transferred to a vacuum oven for drying, and then cut into pieces. The zinc foil, glass fiber membrane, and zinc trifluoromethane sulfonate electrolyte are assembled into a 2016 type button cell. After sealing, the button cell is transferred to a 40°C oven and left for 24 hours.

[0081] (6) The button cell in step (5) is placed in a battery test system, and the unactivated carbon-coated nano vanadium trioxide electrode is subjected to charge and discharge test. The test conditions are as follows: constant current of 100 mA / g, first cycle charge and discharge at 0.4-1.4V voltage, and capacity test at 20A / g high rate.

[0082] (7) The activated battery of step 6) is subjected to performance test, test conditions: constant current of 100 mA / g, first cycle charge-discharge at 0.4-1.4V voltage.

[0083] Comparative Example 3

[0084] (1) 60 mmol of ammonium metavanadate, 20 mmol of citric acid and 200 mL of deionized water are mixed to obtain a mixed solution A, wherein the concentration of vanadium source in the mixed solution A is 0.2 mol / L;

[0085] (2) The mixed solution A of step (1) is subjected to sol-gel reaction under the condition of 85°C water bath until the solution is evaporated to dryness, and the vanadium trioxide material precursor powder is obtained after vacuum drying;

[0086] (3) The powder of step (2) is subjected to pre-carbonization treatment under argon atmosphere at 350°C for 5h, and after being fully ground, calcination under argon atmosphere at 800°C for 7h to obtain carbon-coated nano vanadium trioxide material; the thickness of the carbon coating layer is 2 nm, and the average size of the particles is about 200 nm.

[0087] (4) The powder of step (3), Super P and PVDF are fully mixed and stirred in a ratio of 7:2:1 to form a slurry;

[0088] (5) The slurry A of step (4) is coated on a stainless steel mesh current collector, transferred to a vacuum oven for drying, and after drying, the piece is cut, assembled with zinc foil, glass fiber membrane and zinc trifluoromethanesulfonate electrolyte into a 2016 type button cell, and after sealing treatment, the button cell is transferred to a 40°C oven for 24h.

[0089] (6) The button cell in step (5) is placed in a battery test system, and after 200 mA / g current limited capacity 2000 mAh / g, it is cycled at 0.2-1.6V voltage for 10 cycles as an activation process, to obtain an activated carbon-coated nano vanadium oxide electrode.

[0090] (7) The activated battery of step 6) is subjected to performance test, test conditions: constant current of 100 mA / g, first cycle charge-discharge at 0.4-1.4V voltage. And test the capacity under 20A / g high rate.

[0091] Comparative Example 4

[0092] (1) 40 mmol of ammonium metavanadate, 20 mmol of citric acid and 200 mL of deionized water are mixed to obtain a mixed solution A, wherein the concentration of vanadium source in the mixed solution A is 0.2 mol / L;

[0093] (2) The mixed solution A of step (1) is subjected to a sol-gel reaction under the condition of a water bath at 85°C until the solution is evaporated to dryness, and the vanadium trioxide material precursor powder is obtained after vacuum drying;

[0094] (3) The powder of step (2) is subjected to a pre-carbonization treatment under an argon atmosphere at 350°C for 5h, and after being fully ground, is calcined under an argon atmosphere at 800°C for 7h to obtain a carbon-coated nano vanadium trioxide material; the carbon coating layer has a thickness of 5nm, and the average particle size is about 200nm.

[0095] (4) The powder of step (3), Super P and PVDF are fully mixed and stirred into a slurry at a ratio of 7:2:1;

[0096] (5) The slurry A of step (4) is blade-coated on a stainless steel mesh current collector, transferred to a vacuum oven for drying, and after drying, the piece is cut, assembled with a zinc foil, a glass fiber membrane and a zinc trifluoromethanesulfonate electrolyte into a 2016 type button cell, and after sealing treatment, the button cell is transferred to a 40°C oven and left to stand for 24h.

[0097] (6) The button cell in step (5) is placed in a battery test system, and after a current limit capacity of 500mAh / g at 100mA / g, cyclic charging and discharging at a voltage of 0.2-1.2V for 10 cycles is carried out as an activation process to obtain an activated carbon-coated nano vanadium oxide electrode.

[0098] (7) The activated battery of step 6) is subjected to performance testing, and the test conditions are: a constant current of 100mA / g, a first cycle of charging and discharging at a voltage of 0.4-1.4V, and a capacity test at a high rate of 20A / g.

[0099] Comparative Example 5

[0100] (1) 40mmol of ammonium metavanadate, 40mmol of citric acid and 200mL of deionized water are mixed to obtain a mixed solution A, and the vanadium source concentration in the mixed solution A is 0.2mol / L;

[0101] (2) The mixed solution A of step (1) is subjected to a sol-gel reaction under the condition of a water bath at 85°C until the solution is evaporated to dryness, and the vanadium trioxide material precursor powder is obtained after vacuum drying;

[0102] (3) The powder of step (2) is subjected to a pre-carbonization treatment under an argon atmosphere at 350°C for 5h, and after being fully ground, is calcined under an argon atmosphere at 800°C for 7h to obtain a carbon-coated nano vanadium trioxide material; the carbon coating layer has a thickness of 5nm, and the average particle size is about 200nm.

[0103] (4) The powder of step (3), Super P and PVDF are fully mixed and stirred into a slurry at a ratio of 7:2:1;

[0104] (5) The slurry A of step (4) is coated on a stainless steel mesh current collector, transferred to a vacuum oven for drying, and after drying, the piece is cut, assembled with a zinc foil, a glass fiber membrane, and a zinc trifluoromethanesulfonate electrolyte into a 2016 type button cell, and after sealing treatment, the button cell is transferred to a 40°C oven and left for 24h.

[0105] (6) The button cell in step (5) is placed in a battery test system, and after a current limit capacity of 5000mAh / g at 100mA / g, it is cycled at a voltage of 0.2-1.6V for 10 cycles as an activation process, to obtain an activated carbon-coated nanovanadium oxide electrode.

[0106] (7) The activated battery of step 6) is tested for performance, and the test conditions are: constant current of 100mA / g, and first cycle charge-discharge at a voltage of 0.4-1.4V.

[0107] Comparative Example 6

[0108] (1) 40mmol of ammonium metavanadate, 10mmol of citric acid, and 200mL of deionized water are mixed to obtain a mixed solution A, and the vanadium source concentration in the mixed solution A is 0.2mol / L;

[0109] (2) The mixed solution A of step (1) is subjected to a sol-gel reaction at 85°C under water bath conditions until the solution is evaporated to dryness, and after vacuum drying, the vanadium trioxide material precursor powder is obtained;

[0110] (3) The powder of step (2) is pretreated at 350°C under argon atmosphere for 5h, and after sufficient grinding, it is calcined at 800°C under argon atmosphere for 7h to obtain a nanovanadium trioxide material; due to the low content of organic matter, the product has no carbon coating layer, and the average particle size is about 200nm.

[0111] (4) The powder of step (3), Super P, and PVDF are thoroughly mixed and stirred in a ratio of 7:2:1 to form a slurry;

[0112] (5) The slurry A of step (4) is coated on a stainless steel mesh current collector, transferred to a vacuum oven for drying, and after drying, the piece is cut, assembled with a zinc foil, a glass fiber membrane, and a zinc trifluoromethanesulfonate electrolyte into a 2016 type button cell, and after sealing treatment, the button cell is transferred to a 40°C oven and left for 24h.

[0113] (6) The button cell in step (5) is placed in a battery test system, and after a current limit capacity of 2000mAh / g at 200mA / g, it is cycled at a voltage of 0.2-1.6V for 10 cycles as an activation process, to obtain an activated nanovanadium oxide electrode.

[0114] (7) The activated battery of step 6) was subjected to performance test, test conditions: 100 mA / g and 20 A / g constant current, charging and discharging at 0.4-1.4 V voltage.

[0115] Table 1. Battery test results of examples 1-4 and comparative examples 1-6

[0116]

[0117] It can be seen from the battery test results that the carbon-coated vanadium trioxide prepared does not need activation treatment, and when directly used as an electrode material to assemble a battery, the activity is very low, and the reversible capacity is only a few tens of milliampere hours per gram. Insufficient activation also cannot maximize the capacity of the material. When the molar ratio of vanadium source to organic matter is too high, the carbon coating layer cannot be obtained, and when the molar ratio is too low, the carbon coating layer is too thick, and the electrolyte cannot be effectively infiltrated, which will all lead to a decrease in performance.

Claims

1. A method of preparing a zinc-ion battery cathode active material, characterized in that, The method comprises the following steps: (1) mixing a vanadium source, an organic matter and deionized water to obtain a mixed solution A; (2) performing a sol-gel reaction on the mixed solution A of step (1) under a water bath until the solution is evaporated to dryness, and then vacuum drying to obtain a vanadium trioxide precursor powder; (3) performing a pre-carbonization treatment on the precursor powder of step (2), and then calcining after sufficient grinding to obtain a carbon-coated nano vanadium trioxide material; (4) mixing the carbon-coated nano vanadium trioxide material, conductive carbon and a binder, and then stirring to obtain a slurry A; (5) coating the slurry A of step (1) on a current collector, and then transferring to a vacuum oven for drying to obtain an electrode; (6) cutting the dried electrode, and then assembling into a zinc ion battery, and then sealing and transferring to an oven for standing; (7) placing the standing zinc ion battery in a battery test system, and then performing a constant current limited capacity and voltage method for charging and discharging activation, and then obtaining the zinc ion battery positive electrode active material after activation; In step (1), the molar ratio of the vanadium source to the organic matter is 1:0.5-4; In step (7), the constant current is 20-200 mA / g, the capacity limit is 500-2000 mAh / g, and the cycle charging and discharging is performed 5-20 times at a charging cutoff voltage of 1.5-1.8 V and a discharging cutoff voltage of 0.2-0.4 V; In step (1), the vanadium source is ammonium metavanadate; and the organic matter is one or two or more of citric acid, glucose, oxalic acid and ascorbic acid. In step (3), the pre-carbonization temperature is 200-500 ℃, and the calcination temperature is 600-800 ℃.

2. The production method according to claim 1, characterized by, The vanadium source concentration in the mixed solution A is 0.1-0.5 mol / L.

3. The preparation method according to claim 1, characterized in that, In step (2), the water bath temperature is 60-90 ℃, and the drying condition is 80 ℃ vacuum drying for 12-24 h.

4. The method of claim 1, wherein, In step (3), the pre-carbonization time is 3-7 h, and the calcination time is 6-10 h.

5. The production method according to claim 4, characterized by, The pre-carbonization temperature is 300-400 ℃, and the calcination temperature is 700-800 ℃.

6. The method of claim 1, wherein, In step (4), the ratio of the carbon-coated nano vanadium trioxide material, conductive carbon and binder is 7:2:1; the conductive carbon is one of Super P and Ketjen black; and the binder is one of PVDF, CMC-SBR and PTFE.

7. A zinc ion battery positive electrode active material prepared by the preparation method of any one of claims 1-6.

8. The zinc-ion battery positive electrode active material of claim 7, wherein, The positive electrode active material has a uniform carbon coating layer, the carbon coating layer has a thickness of 1-10 nm, and the particle size is 100-500 nm.

9. Application of the zinc ion battery positive electrode active material of claim 7 in a zinc ion battery.

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