A water-based zinc ion battery positive electrode material, a preparation method and application thereof

Abstract

The application provides a water-based zinc ion battery positive electrode material and a preparation method and application thereof, and belongs to the technical field of water-based zinc ion batteries. The preparation method of the water-based zinc ion battery positive electrode material provided by the application comprises the following steps: mixing few-layer Bi2Te2Se nanosheets, a conductive agent, a binder and a solvent to obtain a slurry; the number of layers of the few-layer Bi2Te2Se nanosheets is 3-10 layers, and the thickness of each few-layer Bi2Te2Se nanosheet is 3-5 nm; and the obtained slurry is coated on the surface of a current collector and then dried to obtain the water-based zinc ion battery positive electrode material. The water-based zinc ion battery positive electrode material prepared by the application is used for preparing a water-based zinc ion battery, and the prepared water-based zinc ion battery has high specific capacity, good rate performance and long cycle life.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of aqueous zinc ion batteries, in particular to an aqueous zinc ion battery positive electrode material and a preparation method and application thereof. BACKGROUND

[0002] In recent years, the global energy situation is increasingly tense, environmental problems such as greenhouse effect and air pollution are increasingly serious, and the vigorous development of new energy vehicles makes people urgently want to develop more efficient and stable energy storage systems. The existing lithium ion battery has some non-negligible shortcomings, for example, the shortage of lithium resources and the uneven geographical distribution of raw materials cause the high cost of lithium ion batteries. In addition, the organic electrolyte used by the lithium ion battery is toxic and flammable, which can easily cause serious safety problems. This forces people to find alternatives to lithium ion batteries. Zinc is abundant in nature, and aqueous zinc ion batteries have the characteristics of high safety, low cost and environmental friendliness, which greatly stimulates the enthusiasm of researchers in the research of aqueous zinc ion batteries.

[0003] In the research of zinc ion batteries, the focus of the research is the positive electrode material that can realize the highly reversible zinc ion intercalation / deintercalation, because the good electrochemical performance of the aqueous zinc ion battery depends on the integrity and stability of the structure of the positive electrode material. Two-dimensional layered materials are very suitable for zinc ion intercalation and deintercalation because of their inherent interlayer spacing, and have great application potential in aqueous zinc ion batteries. As a typical two-dimensional layered material, metal chalcogenide is widely used in aqueous zinc ion batteries in recent years because of its layered structure similar to graphene, high specific capacity and element abundance. However, the metal chalcogenide used in aqueous zinc ion batteries is mostly limited to binary layered compounds, and has defects such as low capacity, poor rate performance and poor cycle stability. For example, Ting Xiong et al. [Nano-Micro Letters 2020, 12(1), 8] synthesized Bi2S3 nanoparticles for aqueous zinc ion batteries, but the specific capacity was less than 200 mAh·g -1 . Zeyi Wu et al. [Small 2020, 16(35), 2000698] synthesized VSe2 nanosheets by chemical liquid synthesis method, and the capacity was attenuated to 75.3% of the initial capacity after 500 cycles (0.5 A·g -1 ). In the prior art, the patent with the publication number CN 113981673B and the name of a preparation method of a composite material of 1T phase MoS2@rGO grown on carbon fiber and its application introduce an aqueous zinc ion battery positive electrode material combining metal chalcogenide MoS2 and rGO. Although the specific capacity of the material used in the aqueous zinc ion battery is improved, the material still has the defects of poor cycle performance and poor rate performance.

[0004] Therefore, it is urgent to provide a water-based zinc ion battery positive electrode material capable of achieving a good balance between high specific capacity, good rate performance and long cycle life. SUMMARY

[0005] The application aims to provide a water-based zinc ion battery positive electrode material, a preparation method and application thereof. The water-based zinc ion battery positive electrode material prepared by the application is used to prepare a water-based zinc ion battery, and the prepared water-based zinc ion battery has high specific capacity, good rate performance and long cycle life.

[0006] In order to achieve the above-mentioned application purposes, the application provides the following technical solutions.

[0007] The application provides a preparation method of a water-based zinc ion battery positive electrode material, comprising the following steps:

[0008] (1) mixing few-layer Bi2Te2Se nanosheets, a conductive agent, a binder and a solvent to obtain a slurry; the few-layer Bi2Te2Se nanosheets have 3-10 layers, and each few-layer Bi2Te2Se nanosheet has a thickness of 3-5 nm;

[0009] (2) coating the slurry obtained in step (1) on the surface of a current collector and then drying to obtain a water-based zinc ion battery positive electrode material.

[0010] Preferably, the few-layer Bi2Te2Se nanosheets in step (1) have a sheet length of 500 nm-5 μm.

[0011] Preferably, the preparation method of the few-layer Bi2Te2Se nanosheets in step (1) comprises: mixing multi-layer Bi2Te2Se powder, an intercalation agent and a solvent, and then sequentially performing ultrasonic treatment, vacuum filtration, cleaning and drying to obtain the few-layer Bi2Te2Se nanosheets.

[0012] Preferably, the ratio of the mass of the multi-layer Bi2Te2Se powder to the volume of the intercalation agent and the volume of the solvent is 0.2 g:(0.1-0.3) mL:(20-60) mL.

[0013] Preferably, the power of the ultrasonic treatment is 200-300 W, and the time of the ultrasonic treatment is 60-180 min.

[0014] Preferably, the temperature of the drying is 50-70℃, and the time of the drying is 5-7 h.

[0015] Preferably, the ratio of the mass of the few-layer Bi2Te2Se nanosheets, the mass of the conductive agent and the mass of the binder in step (1) is (6-8):(1-2):(1-2).

[0016] Preferably, the loading of the few-layer Bi2Te2Se nanosheets in the slurry in step (2) on the surface of the current collector is 0.5-1.5 mg·cm -2 .

[0017] The application further provides the water-based zinc ion battery positive electrode material prepared by the preparation method.

[0018] The application further provides application of the water-based zinc ion battery positive electrode material in a water-based zinc ion battery.

[0019] The application provides a preparation method of a water-based zinc ion battery positive electrode material, comprising the following steps: mixing few-layer Bi2Te2Se nanosheets, a conductive agent, a binder and a solvent to obtain a slurry; the number of layers of the few-layer Bi2Te2Se nanosheets is 3-10, and the thickness of each few-layer Bi2Te2Se nanosheet is 3-5 nm; coating the obtained slurry on the surface of a current collector and then drying to obtain the water-based zinc ion battery positive electrode material. The few-layer Bi2Te2Se nanosheets used in the application have an ultrathin layered structure, which effectively reduces the ion diffusion distance, and the characteristic gap between the layers provides sufficient space for zinc ion storage, which is beneficial to improve the specific capacity of the battery; and the few-layer Bi2Te2Se nanosheets have a stable crystal structure, which can maintain the integrity of the structure during long-term charging and discharging, and will not collapse and destroy the layered structure, which is beneficial to provide long cycle life for the battery; in addition, the few-layer Bi2Te2Se nanosheets not only have excellent electrochemical properties, but also have high safety, are environmentally friendly and have low cost.

[0020] The results of the examples show that the water-based zinc ion battery prepared by using the water-based zinc ion battery positive electrode material prepared by the application has a high specific capacity of 297.5 mAh·g -1 at a current density of 0.2 A·g -1 , a long cycle life of 2200 times (a capacity retention rate of 94% at a current density of 2 A·g -1 ) and excellent rate performance, and realizes a good balance among high specific capacity, good rate performance and long cycle life. BRIEF DESCRIPTION OF DRAWINGS

[0021] Figure 1 A working principle diagram of the water-based zinc ion battery positive electrode material provided by the application in a water-based zinc ion battery;

[0022] Figure 2 An XRD diagram of the water-based zinc ion battery positive electrode material provided by Example 1 of the application;

[0023] Figure 3 TEM image of the water-based zinc ion battery positive electrode material provided by the present application and element mapping image in the TEM image area; wherein, (a) is the TEM image of the water-based zinc ion battery positive electrode material provided by the present application, (b) is the element mapping image in the area of (a);

[0024] Figure 4 Thickness test diagram of each nanosheet of the few-layer Bi2Te2Se nanosheet prepared by step (1) of the present application; wherein, (a) is the AFM image of the water-based zinc ion battery positive electrode material provided by the present application, (b) is the curve change diagram of the sheet thickness of each few-layer Bi2Te2Se nanosheet shown in the area of (a);

[0025] Figure 5 CV curve of the water-based zinc ion battery of the present application and straight line diagram of Log(i) and Log(v); wherein, (a) is the CV curve of the water-based zinc ion battery of application example 1 at different scanning rates, (b) is the straight line diagram of Log(i) and Log(v) based on the current response at the 5 peaks in (a);

[0026] Figure 6 GCD curve diagram of the water-based zinc ion battery of the present application in application example 1 at a current density of 0.2-2A·g -1 ;

[0027] Figure 7 Rate performance diagram of the water-based zinc ion battery of the present application in application example 1 at a current density of 0.2-2A·g -1 ;

[0028] Figure 8 Cycle performance diagram of the water-based zinc ion battery of the present application in application example 1;

[0029] Figure 9 EIS diagram of the water-based zinc ion battery of the present application in application example 1; wherein, Figure 9 the inserted drawing in (a) is the corresponding circuit principle diagram of EIS curve fitting;

[0030] Figure 10 Comparison diagram of specific capacity of the water-based zinc ion battery positive electrode material provided by the present application and electrode materials (VS2, Bi2S3, MnS, MoS2, VSe2, Bi2S3 positive electrode material) of comparative examples 1-6;

[0031] Figure 11 GCD curve diagram of the water-based zinc ion battery of the present application in application example 1 at a current density of 2A·g -1SEM images of the few-layer Bi2Te2Se nanosheets in the used positive electrode material after 1000 cycles and 2000 cycles at a current density of 0.5 A / g, respectively; wherein (a) is the SEM image after 1000 cycles, (b) is the SEM image after 2000 cycles. DETAILED DESCRIPTION

[0032] The application provides a preparation method of a water-based zinc ion battery positive electrode material.

[0033] (1) mixing few-layer Bi2Te2Se nanosheets, a conductive agent, a binder and a solvent to obtain a slurry; the few-layer Bi2Te2Se nanosheets have 3-10 layers, and each few-layer Bi2Te2Se nanosheet has a thickness of 3-5 nm;

[0034] (2) coating the slurry obtained in step (1) on the surface of a current collector and drying to obtain the water-based zinc ion battery positive electrode material.

[0035] The application mixes few-layer Bi2Te2Se nanosheets, a conductive agent, a binder and a solvent to obtain a slurry.

[0036] In the application, the few-layer Bi2Te2Se nanosheets have 3-10 layers, preferably 4-9 layers, and more preferably 5-8 layers; and each few-layer Bi2Te2Se nanosheet has a thickness of 3-5 nm. By controlling the number of layers and the thickness of each nanosheet of the few-layer Bi2Te2Se nanosheet within the above range, the application can ensure that the few-layer Bi2Te2Se nanosheet has an ultrathin structure, can effectively reduce the ion diffusion distance, and the characteristic gap between layers can provide sufficient space for zinc ion storage, which is more conducive to improving the specific capacity of the battery.

[0037] In the application, the sheet length of the few-layer Bi2Te2Se nanosheet is preferably 500 nm-5 μm, and more preferably 600 nm-4.55 μm. By controlling the sheet length of the few-layer Bi2Te2Se powder within the above range, the application is more conducive to maintaining the integrity of the structure, so that the prepared water-based zinc ion battery has long cycle stability.

[0038] In the application, the preparation method of the few-layer Bi2Te2Se nanosheet preferably comprises: mixing multi-layer Bi2Te2Se powder, an intercalation agent and a solvent, and then sequentially performing ultrasonic treatment, vacuum filtration, cleaning and drying to obtain the few-layer Bi2Te2Se nanosheet.

[0039] The application does not have special limitations on the source of the multi-layer Bi2Te2Se powder, and commercially available materials or materials prepared by conventional methods in the art can be used.

[0040] In the present application, the intercalating agent is preferably N-methyl pyrrolidone. The present application expands the interlayer spacing by intercalating the above-mentioned intercalating agent into the interlayer of the multilayer Bi2Te2Se, thus making it more favorable for the Bi2Te2Se platelets to be peeled off from the original layered multilayer Bi2Te2Se structure into a few-layer ultrathin structure during ultrasonic treatment.

[0041] In the present application, the solvent is preferably isopropyl alcohol. The present application makes it more favorable for the components to be uniformly dispersed by selecting the above-mentioned solvent.

[0042] The ratio of the mass of the multilayer Bi2Te2Se powder to the volume of the intercalating agent and the volume of the solvent is preferably 0.2 g:(0.1-0.3) mL:(20-60) mL, and more preferably 0.2 g:(0.15-0.25) mL:(30-50) mL. The present application makes it more favorable for the intercalating agent to be intercalated into the multilayer Bi2Te2Se powder and for the components to be uniformly dispersed by controlling the ratio of the mass of the multilayer Bi2Te2Se powder to the volume of the intercalating agent and the volume of the solvent within the above-mentioned range.

[0043] In the present application, the mixing method is preferably grinding. In the present application, the grinding time is preferably 40-80 min, and more preferably 60 min. The present application makes it more favorable for the intercalating agent to be intercalated into the interlayer of the multilayer Bi2Te2Se powder and for the platelets to be completely peeled off by adopting the grinding mixing method.

[0044] In the present application, the power of the ultrasonic treatment is preferably 200-300 W, and more preferably 220-260 W; and the time of the ultrasonic treatment is preferably 60-180 min, and more preferably 60-120 min. The present application makes it possible for the multilayer Bi2Te2Se powder to be completely peeled off into a few-layer ultrathin layered Bi2Te2Se nanosheet by controlling the power and the time of the ultrasonic treatment within the above-mentioned range.

[0045] The present application does not have special requirements for the operation of the vacuum filtration and washing, and the operation of the vacuum filtration and washing known in the art can be adopted to sufficiently remove the residual intercalating agent and solvent.

[0046] In the present application, the drying temperature is preferably 50-70℃, and more preferably 60℃; and the drying time is preferably 5-7 h. The present application makes it more favorable for the water remaining between the platelets to be sufficiently removed by controlling the temperature and the time of the drying within the above-mentioned range.

[0047] In the present application, the ratio of the mass of the few-layer Bi2Te2Se nanosheet, the mass of the conductive agent and the mass of the binder is preferably (6-8):(1-2):(1-2), more preferably (6.5-7.5):(1.2-1.8):(1.2-1.8). By controlling the ratio of the mass of the few-layer Bi2Te2Se nanosheet, the mass of the conductive agent and the mass of the binder within the above range, the present application can make the positive electrode material obtain good electrochemical performance, so that the battery prepared has high specific capacity, good rate capability and long cycle life.

[0048] In the present application, the ratio of the total mass of the few-layer Bi2Te2Se nanosheet, the conductive agent and the binder to the volume of the solvent is preferably (60-80) mg:1 mL, more preferably (65-75) mg:1 mL. By controlling the ratio of the total mass of the few-layer Bi2Te2Se nanosheet, the conductive agent and the binder to the volume of the solvent within the above range, the present application is more conducive to the uniform dispersion of the few-layer Bi2Te2Se nanosheet and the slurry to obtain appropriate viscosity and flowability and conductivity.

[0049] In the present application, the conductive agent is preferably acetylene black. In the present application, the binder is preferably polyvinylidene fluoride. In the present application, the solvent is preferably N-methyl pyrrolidone. By selecting the above types of conductive agent, binder and solvent, the present application is more conducive to the slurry to obtain appropriate viscosity and flowability and conductivity.

[0050] After obtaining the slurry, the present application coats the slurry on the surface of the current collector and then dries to obtain the positive electrode material of the aqueous zinc ion battery.

[0051] The present application does not have special limitations on the coating operation, and a uniform film layer can be obtained by using the coating operation well known in the art.

[0052] In the present application, the loading of the few-layer Bi2Te2Se nanosheet in the slurry on the surface of the current collector is preferably 0.5-1.5 mg·cm -2 , more preferably 1 mg·cm -2 . By controlling the loading of the few-layer Bi2Te2Se nanosheet in the slurry on the surface of the current collector within the above range, the present application is more conducive to obtaining a positive electrode material with good electrochemical performance.

[0053] In the present application, the current collector is preferably a titanium sheet. By selecting a titanium sheet as the current collector, the present application is more conducive to the positive electrode material to obtain good electrochemical performance.

[0054] In the present application, the temperature of the drying is preferably 50-70 DEG C, and the time of the drying is preferably 5-7 hours. By controlling the temperature and time of the drying within the above ranges, the solvent can be fully volatilized, and the problems such as curling and cracking of the film layer can be avoided, which is more conducive to obtaining good electrochemical performance of the positive electrode material.

[0055] The working principle diagram of the water-based zinc ion battery positive electrode material provided by the present application in a water-based zinc ion battery is shown in Figure 1 Figure 1 As can be seen, during the discharging process, the zinc negative electrode loses electrons to become zinc ions, which then move to the Bi2Te2Se positive electrode (i.e. the water-based zinc ion battery positive electrode material) and are adsorbed and embedded in the Bi2Te2Se positive electrode; during the charging process, the zinc ions are de-embedded from the Bi2Te2Se positive electrode and migrate to the negative electrode to form zinc.

[0056] The water-based zinc ion battery positive electrode material prepared by the present application is used to prepare a water-based zinc ion battery, and the prepared water-based zinc ion battery has high specific capacity, good rate performance and long cycle life; moreover, the raw materials of the preparation method provided by the present application are easy to obtain, the cost is low, the environmental friendliness is higher, the method is simple, and the parameters are easy to control.

[0057] The present application also provides a water-based zinc ion battery positive electrode material prepared by the preparation method.

[0058] The water-based zinc ion battery positive electrode material provided by the present application has high specific capacity, good rate performance and long cycle life when used to prepare a water-based zinc ion battery.

[0059] The present application also provides the application of the water-based zinc ion battery positive electrode material in a water-based zinc ion battery.

[0060] The water-based zinc ion battery provided by the present application can replace lithium ion batteries and has high specific capacity, good rate performance and long cycle life, and has a better application prospect.

[0061] The technical solutions in the present application will be clearly and completely described below by combining the embodiments in the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present application.

[0062] Embodiment 1

[0063] A preparation method of a water-based zinc ion battery positive electrode material comprises the following steps:

[0064] ​(1) mixing the few-layer Bi2Te2Se nanosheets with a conductive agent, a binder and a solvent to obtain a slurry;

[0065] The preparation method of the few-layer Bi2Te2Se nanosheets is as follows: mixing multi-layer Bi2Te2Se powder with an intercalation agent and a solvent, and then sequentially performing ultrasonic treatment, vacuum suction filtration, cleaning and drying to obtain the few-layer Bi2Te2Se nanosheets; specifically, 0.2 g of multi-layer Bi2Te2Se powder is added into 0.2 mL of N-methylpyrrolidone for grinding for 60 min, and then dispersed in 40 mL of isopropanol, and ultrasonic treatment is performed at an ultrasonic power of 240 W for 120 min to obtain a few-layer Bi2Te2Se nanosheet suspension; the ratio of the mass of the multi-layer Bi2Te2Se powder to the volume of the intercalation agent (N-methylpyrrolidone) and the volume of the solvent (isopropanol) is 0.2 g:0.2 mL:40 mL; then the prepared few-layer Bi2Te2Se nanosheet suspension is subjected to vacuum suction filtration, then cleaned with ethanol, and finally transferred to a vacuum drying oven for drying, with a drying temperature of 60℃ and a drying time of 6 h, to obtain the few-layer Bi2Te2Se nanosheets.

[0066] The number of layers of the few-layer Bi2Te2Se nanosheets is 3-5 layers, and the thickness of each nanosheet is 3-5 nm; the length of the sheet layer of the few-layer Bi2Te2Se nanosheets is 500 nm-5 μm;

[0067] The ratio of the mass of the few-layer Bi2Te2Se nanosheets, the mass of the conductive agent and the mass of the binder is 7:2:1, and the ratio of the total mass of the few-layer Bi2Te2Se nanosheets, the conductive agent and the binder to the volume of the solvent is 71.3 mg:1 mL; the conductive agent is acetylene black, the binder is polyvinylidene fluoride, and the solvent is N-methylpyrrolidone.

[0068] (2) drying the slurry obtained in step (1) after coating on the surface of the current collector to obtain the positive electrode material of the aqueous zinc ion battery; specifically, the slurry obtained in step (1) is coated on the surface of a current collector (i.e. a rectangular titanium sheet) with a size of 2 cm x 1 cm, and the loading of the few-layer Bi2Te2Se nanosheets in the slurry on the surface of the current collector is 1 mg·cm -2 , and then dried in a vacuum drying oven at a temperature of 60℃ for 6 h to obtain the positive electrode material of the aqueous zinc ion battery.

[0069] Example 2

[0070] The ratio of the mass of the multi-layer Bi2Te2Se powder to the volume of the intercalation agent (N-methylpyrrolidone) and the volume of the solvent (isopropyl alcohol) in the method for preparing the few-layer Bi2Te2Se nanosheets in Example 1 Step (1) is replaced with: 0.2 g: 0.1 mL: 20 mL; the time for ultrasonic treatment is replaced with 60 min. The remaining technical features are the same as in Example 1.

[0071] Example 3

[0072] The ratio of the mass of the multi-layer Bi2Te2Se powder to the volume of the intercalation agent (N-methylpyrrolidone) and the volume of the solvent (isopropyl alcohol) in the method for preparing the few-layer Bi2Te2Se nanosheets in Example 1 Step (1) is replaced with: 0.2 g: 0.3 mL: 60 mL; the time for ultrasonic treatment is replaced with 180 min. The remaining technical features are the same as in Example 1.

[0073] Example 4

[0074] The drying temperature in the method for preparing the few-layer Bi2Te2Se nanosheets in Example 1 Step (1) is replaced with 50°C, and the drying time is replaced with 7 h. The remaining technical features are the same as in Example 1.

[0075] Example 5

[0076] The drying temperature in the method for preparing the few-layer Bi2Te2Se nanosheets in Example 1 Step (1) is replaced with 70°C, and the drying time is replaced with 5 h. The remaining technical features are the same as in Example 1.

[0077] Example 6

[0078] The ratio of the mass of the few-layer Bi2Te2Se nanosheets to the mass of the conductive agent and the mass of the binder described in Example 1 Step (2) is replaced with: 6: 2: 2. The remaining technical features are the same as in Example 1.

[0079] Example 7

[0080] The ratio of the mass of the few-layer Bi2Te2Se nanosheets to the mass of the conductive agent and the mass of the binder described in Example 1 Step (2) is replaced with: 8: 1: 1. The remaining technical features are the same as in Example 1.

[0081] Example 8

[0082] The drying temperature in Example 1 Step (2) is replaced with 50°C, and the drying time is replaced with 7 h. The remaining technical features are the same as in Example 1.

[0083] Example 9

[0084] The temperature of drying in step (2) of Example 1 is replaced by 70℃, and the time of drying is replaced by 5h. The rest of the technical features are the same as Example 1.

[0085] Comparative Examples 1-6

[0086] VS2, Bi2S3, MnS, MoS2, VSe2, Bi2S3 cathode materials are prepared by replacing the few-layer Bi2Te2Se nanosheets in Example 1 with VS2, Bi2S3, MnS, MoS2, VSe2, Bi2S3, respectively.

[0087] Application Examples 1-9

[0088] Water-based zinc ion batteries are prepared by using the water-based zinc ion battery cathode materials provided in Examples 1-9, respectively. The above-prepared Examples 1-9 cathode materials are used, a zinc foil negative electrode is used, and a 2 mol / L zinc trifluoromethanesulfonate electrolyte is used to test the electrochemical performance of the water-based zinc ion battery in a two-electrode system.

[0089] Comparative Application Examples 1-6

[0090] Zinc ion batteries are prepared by using the cathode materials provided in Comparative Examples 1-6, respectively. The above-prepared Comparative Examples 1-6 cathode materials are used, a zinc foil negative electrode is used, and a 2 mol / L zinc trifluoromethanesulfonate electrolyte is used to test the electrochemical performance of the water-based zinc ion battery in a two-electrode system.

[0091] The crystal phase of the water-based zinc ion battery cathode material provided in Example 1 of the application is detected by X-ray diffractometer, and the XRD spectrum obtained by detection is shown in Figure 2 .

[0092] From Figure 2 It can be seen that all the diffraction peaks correspond to the standard card of Bi2Te2Se (JCPDS No. 29-0248), indicating that the crystal structure of the material has not been changed by grinding, and no additional impurity phase exists.

[0093] The microstructure and element type of the water-based zinc ion battery cathode material provided in Example 1 of the application are observed and detected by transmission electron microscopy, and the results are shown in Figure 3 ; wherein (a) is the TEM image of the water-based zinc ion battery cathode material provided in Example 1 of the application, and (b) is the element mapping image in the area of (a).

[0094] From the (a) TEM image in Figure 3 , it can be seen that the Bi2Te2Se in the cathode material is an irregular layered structure; from the (b) element mapping in Figure 3 , it can be seen that the Bi, Te, and Se elements are uniformly distributed.

[0095] The thickness of each layer of the layered Bi2Te2Se nanosheet prepared in step (1) of Example 1 of the present application was measured by atomic force microscopy, and the results are shown in Figure 4 ; wherein (a) is an AFM image of the positive electrode material for aqueous zinc ion battery provided in Example 1 of the present application, and (b) is a graph showing the change in the thickness of each layer in the region of (a).

[0096] As can be seen from Figure 4 , the few-layer Bi2Te2Se nanosheet has 3-5 layers, and the thickness of each nanosheet is between 3-5 nm. The thicknesses of the five nanosheets shown in (a) are 4.88 nm, 4.81 nm, 4.43 nm, 3.63 nm, and 4.89 nm, respectively. Such an ultrathin layered structure is conducive to the intercalation and deintercalation of zinc ions.

[0097] The aqueous zinc ion battery of Application Example 1 of the present application was subjected to electrochemical testing at a scan rate of 0.1-1.0 mV·s -1 , and the value of b was calculated according to the formula i = av b (wherein a and b are adjustable parameters, and i and v are current and scan rate). The CV curve obtained by testing and the straight line graph of Log(i) and Log(v) are shown in Figure 5 ; wherein (a) is the CV curve of the aqueous zinc ion battery of Application Example 1 of the present application at different scan rates, and (b) is the straight line graph of Log(i) and Log(v) based on the current response at the five peaks in (a).

[0098] As can be seen from Figure 5 (a), when b = 0.5 or 1, it indicates that the kinetic process is controlled by the diffusion process or the surface capacitance process. As can be seen from (b), the b values of the five peaks are 0.64, 0.50, 0.81, 0.99, and 0.88, respectively, indicating that the electrochemical reaction process is jointly controlled by the diffusion process and the surface capacitance process.

[0099] The aqueous zinc ion battery of Application Example 1 of the present application was subjected to electrochemical testing at a current density of 0.2-2 A·g -1 , and the GCD curve obtained by testing is shown in Figure 6 .

[0100] As can be seen from Figure 6 , the specific discharge capacity at a current density of 0.2, 0.4, 0.8, 1.2, 1.6, and 2 A·g -1 is 297.5, 286.1, 260.2, 239.4, 222.1, and 208.7 mAh·g -1 , respectively, indicating that the positive electrode material for aqueous zinc ion battery has a high specific capacity.

[0101] In the range of 0.2~2A·g -1 The electrochemical test of the aqueous zinc ion battery of Application Example 1 of the present invention was carried out at a current density of Figure 7 shown.

[0102] Depend on Figure 7 It can be seen that when the current density is increased from 0.2A·g -1 Increased to 2A·g -1 After 24 cycles, it returns to 0.2A·g -1 At a current density of 355.8 mAh g -1 The high specific capacity indicates that aqueous zinc-ion batteries have excellent rate performance.

[0103] The aqueous zinc ion battery of the present invention is subjected to the conditions of 2A·g -1 After 2200 charge and discharge cycles at a current density of Figure 8 shown.

[0104] Depend on Figure 8 It can be seen that at 2A·g -1 After 2200 charge and discharge cycles at a current density of , the capacity retention rate is as high as 94%, indicating that the aqueous zinc ion battery has a long cycle life.

[0105] The electrochemical test of the aqueous zinc ion battery of Application Example 1 of the present invention was carried out, and the EIS diagram obtained by the test was as follows: Figure 9 shown; among them, Figure 9 The inset is the corresponding circuit schematic for EIS curve fitting.

[0106] Depend on Figure 9 It can be seen that EIS consists of a semicircle in the high-frequency region and a straight line in the low-frequency region. According to the fitting calculation results, the equivalent series resistance R of the aqueous zinc ion battery is s is 8.7Ω, the charge transfer resistance R ct The smaller resistance value indicates that the aqueous zinc-ion battery has excellent conductivity and strong electron transfer kinetics.

[0107] The specific capacity of the aqueous zinc ion battery positive electrode material provided in Example 1 of the present invention and the electrode materials of Comparative Examples 1 to 6 (VS2, Bi2S3, MnS, MoS2, VSe2, Bi2S3 positive electrode materials) were tested and compared, and the specific capacity comparison diagram obtained is as follows: Figure 10 shown.

[0108] Depend on Figure 10 It can be seen that the aqueous zinc ion battery positive electrode material provided by Example 1 of the present invention has both high specific capacity and rate performance, and is superior to other metal sulfide compound electrode materials.

[0109] The application example 1 aqueous zinc ion battery was cycled for 1000 times and 2000 times at a current density of 2A·g-1, respectively, and the microstructure of the layered Bi2Te2Se nanosheet in the used positive electrode material was observed, and the observed SEM images are shown in -1 Figure 11 (a) is the SEM image after 1000 cycles, and (b) is the SEM image after 2000 cycles.

[0110] As can be seen from (a) in Figure 11 , after the application example 1 aqueous zinc ion battery was cycled for 1000 times, the layered structure of the few-layer Bi2Te2Se nanosheet in the used positive electrode material was still good and was not destroyed; as can be seen from (b) in Figure 11 , after the application example 1 aqueous zinc ion battery was cycled for 2000 times, although the edge of the few-layer Bi2Te2Se nanosheet in the used positive electrode material was rough, the layered structure could still be observed, indicating that the aqueous zinc ion battery positive electrode material used in the aqueous zinc ion battery of the application has excellent structural stability.

[0111] In summary, the aqueous zinc ion battery prepared by using the aqueous zinc ion battery positive electrode material provided by the application has the advantages of structural stability, high specific capacity, good rate performance, long cycle life and the like, and has a broad application prospect in aqueous zinc ion batteries.

[0112] The above only describes the preferred embodiments of the application, and it should be pointed out that for ordinary skilled persons in the art, some improvements and refinements can be made without departing from the principles of the application, and these improvements and refinements should also be regarded as the protection scope of the application.​

Claims

1. A method for preparing a positive electrode material for an aqueous zinc ion battery, characterized in that: The steps include: (1) mixing a few-layer Bi2Te2Se nanosheet with a conductive agent, a binder, and a solvent to obtain a slurry; the number of layers of the few-layer Bi2Te2Se nanosheet is 3 to 10, and the thickness of each few-layer Bi2Te2Se nanosheet is 3 to 5 nm; (2) coating the slurry obtained in step (1) on the surface of the current collector and then drying it to obtain an aqueous zinc ion battery positive electrode material.

2. The preparation method according to claim 1, wherein The length of the few-layer Bi2Te2Se nanosheets in step (1) is 500nm to 5μm.

3. The preparation method according to claim 1 or 2, wherein The method for preparing the few-layer Bi2Te2Se nanosheets in step (1) comprises: mixing multilayer Bi2Te2Se powder with an intercalating agent and a solvent, and then sequentially performing ultrasonic treatment, vacuum filtration, washing and drying to obtain the few-layer Bi2Te2Se nanosheets.

4. The preparation method according to claim 3, wherein The ratio of the mass of the multilayer Bi2Te2Se powder to the volume of the intercalation agent and the volume of the solvent is: 0.2 g: (0.1-0.3) mL: (20-60) mL.

5. The preparation method according to claim 3, wherein The power of the ultrasonic treatment is 200-300W, and the time of the ultrasonic treatment is 60-180 minutes.

6. The preparation method according to claim 3, wherein The drying temperature is 50-70° C., and the drying time is 5-7 hours.

7. The preparation method according to claim 1 or 2, wherein In the step (1), the ratio of the mass of the few-layer Bi2Te2Se nanosheets, the mass of the conductive agent and the mass of the binder is: (6-8): (1-2): (1-2).

8. The preparation method according to claim 1, wherein The loading of the few-layer Bi2Te2Se nanosheets in the slurry on the surface of the current collector in step (2) is 0.5-1.5 mg·cm -2 .

9. Aqueous zinc ion battery positive electrode material prepared by the preparation method according to any one of claims 1 to 8.

10. Use of the aqueous zinc ion battery cathode material according to claim 9 in an aqueous zinc ion battery.

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