Zinc ion battery electrolyte containing polysaccharide zinc chelate and preparation method and application thereof

Abstract

The present application relates to a kind of zinc ion battery electrolyte containing polysaccharide zinc chelate and preparation method and application, the electrolyte includes deionized water solvent, soluble zinc salt solute and polysaccharide zinc chelate additive, the addition amount of the polysaccharide zinc chelate additive is 0.20 mmol / L~1.35 mmol / L;The polysaccharide zinc chelate additive is any one or multiple of zinc hyaluronate, zinc tannate, zinc alginic polysaccharide, rice bran polysaccharide zinc chelate, zinc chelate of radix mori polysaccharide.In the zinc salt aqueous electrolyte, a trace of green and safe polysaccharide zinc chelate additive is added, on the one hand, hydrogen evolution side reaction is effectively inhibited, on the other hand, the growth of negative electrode surface dendrite is inhibited;The electrolyte is applied to aqueous zinc ion battery, can significantly improve the cycle stability of battery, effectively prolong the cycle life of zinc ion battery.

Description

Technical Field

[0001] The present invention belongs to the technical field of aqueous zinc ion batteries, and in particular relates to a zinc ion battery electrolyte containing a polysaccharide zinc chelate, and a preparation method and application thereof. Background Art

[0002] With the rapid development of renewable energy, batteries, as an important component of energy storage systems, must meet the requirements of high safety, low cost, and long life. Compared with traditional lithium-ion batteries, aqueous batteries have the advantages of inherent safety, environmental protection, and long cycle life, and are the most powerful competitor for the next generation of large-scale energy storage battery technology. Aqueous zinc-ion batteries (AZIBs) have a high theoretical specific capacity (820mAh·g -1 and 5855mAh•cm -3 ) and lower electrode potential (-0.76V vs standard hydrogen electrode), as well as advantages such as low cost, high safety and green environmental protection, are regarded as a strong competitor to lithium-ion batteries and have attracted much attention.

[0003] The industrialization of aqueous zinc-ion batteries is still in its infancy, and laboratory research results have not been well validated in large-scale trials. Issues at the zinc anode (dendrites, corrosion, and hydrogen evolution) and the cathode (dissolution and structural collapse) severely limit the battery's cycle life and coulombic efficiency. Currently, the use of electrolyte additives to optimize zinc-ion battery stability has been extensively studied. Among reported zinc-ion battery electrolyte additives, patent CN115332646A discloses a zinc-ion battery electrolyte containing fully or partially water-soluble organic small molecule compounds such as dimethyl sulfoxide and N,N-dimethylformamide as additives. This organic solvent weakens water hydrogen bonds, inhibiting the hydrogen evolution reaction and effectively improving the battery's high-temperature performance. Patent CN113948779A utilizes oxoacid salts or organic small molecule compounds containing S or F substituents as additives to form an inorganic solid protective film on the electrode material, improving the battery's cycling stability. However, most of these small organic molecule compounds are organic solvents with certain toxicity, and the concentration added to the electrolyte is relatively high (0.05-0.5 mol / L), which makes it difficult to meet the safety, environmental protection and low-cost requirements of aqueous zinc-ion batteries.

[0004] Organic polymer chemicals have the advantages of high stability, characteristic structure, and adjustable functional group design, and are increasingly being used as additives to improve the performance of aqueous zinc-ion batteries. Patent CN114388903 A uses a green and safe carboxymethyl cellulose as a zinc-ion battery electrolyte additive, utilizing the large number of highly hydrophilic hydroxyl functional groups on the carboxymethyl cellulose polymer to regulate the zinc ion solvation structure, thereby alleviating zinc dendrite growth and extending battery life. However, although this type of additive with only a single action site can optimize zinc deposition / stripping behavior to a certain extent, it is still difficult to achieve long-term and stable interface regulation under trace addition conditions. Summary of the Invention

[0005] In view of current technological deficiencies, the present invention provides a zinc ion battery electrolyte containing a polysaccharide zinc chelate, as well as a preparation method and application. This invention adds a trace amount of a green and safe polysaccharide zinc chelate additive to a zinc-salt electrolyte. By utilizing the dual functional sites of hydrophilic groups and zinc-philic coordination groups in the polysaccharide zinc chelate structure, this method optimizes the zinc ion solvation structure by reducing the number of active water molecules, thereby suppressing the hydrogen evolution side reaction. Furthermore, this method achieves uniform zinc ion deposition by constructing a directional zinc ion transport channel, thereby suppressing dendrite growth on the negative electrode surface. Application of this electrolyte to aqueous zinc ion batteries can significantly improve the battery's cycle stability and effectively extend the cycle life of the zinc ion battery.

[0006] In order to achieve the above object, the present invention adopts the following technical solutions:

[0007] A zinc ion battery electrolyte containing a polysaccharide zinc chelate, the electrolyte comprising a deionized water solvent, a soluble zinc salt solute and a polysaccharide zinc chelate additive, wherein the addition amount of the polysaccharide zinc chelate additive is 0.20 mmol / L to 1.35 mmol / L; the polysaccharide zinc chelate additive is any one or more of zinc hyaluronate, zinc tannate, seaweed polysaccharide zinc, rice bran polysaccharide zinc chelate, and Polygonum multiflorum polysaccharide zinc chelate.

[0008] Preferably, the soluble zinc salt solute is any one or more of zinc sulfate, zinc acetate, zinc nitrate, zinc chloride, zinc bromide, zinc trifluoromethanesulfonate, and zinc iodide.

[0009] Preferably, the concentration of the soluble zinc salt solute is 0.5 mol / L to 4.0 mol / L.

[0010] Preferably, the polysaccharide zinc chelate additive is hyaluronate zinc (HA-Zn), the molecular formula of which is [Zn(C 14 H 20 O 11 N)2] n , with a molecular weight of 30,000 to 50,000 Da.

[0011] Preferably, the amount of the polysaccharide zinc chelate additive added is 0.50 mmol / L. The amount of the polysaccharide zinc chelate additive added in the present invention can achieve long-term and stable interface regulation under the condition of adding a small amount or even a trace amount.

[0012] The present invention also provides a method for preparing the above-mentioned zinc ion battery electrolyte containing the polysaccharide zinc chelate, comprising the following steps:

[0013] Step S1: mixing a soluble zinc salt and deionized water in proportion, and dissolving them by ultrasonication at room temperature until the solution is completely clear and transparent without precipitation, to obtain a mixed solution;

[0014] Step S2: adding the polysaccharide zinc chelate additive to the mixed solution of step S1, and dissolving the polysaccharide zinc chelate additive by ultrasonication until the polysaccharide zinc chelate additive is completely dissolved to obtain an aqueous zinc ion battery electrolyte.

[0015] In addition, the present invention also provides the use of the zinc ion battery electrolyte of the polysaccharide zinc chelate in an aqueous zinc ion battery.

[0016] Preferably, the aqueous zinc ion battery is any one of a zinc-zinc symmetric battery (Zn||Zn symmetric battery), a zinc-copper half-cell (Zn||Cu half-cell), and a zinc-vanadium dioxide full battery (Zn||VO2 full battery).

[0017] Preferably, the zinc-zinc symmetrical battery is composed of a 50 μm thick zinc foil, a glass fiber separator and an aqueous zinc ion battery electrolyte; the zinc-copper half-cell is composed of a commercial 50 μm thick zinc foil, a commercial copper foil current collector, a glass fiber separator and an aqueous zinc ion battery electrolyte; the zinc-vanadium dioxide full battery is composed of a commercial 50 μm thick zinc foil, a commercial vanadium dioxide positive electrode sheet and an aqueous zinc ion battery electrolyte.

[0018] As a preferred method, the Zn-Zn symmetrical battery is -2 Current density, 1mAh•cm -2 The capacity density is stable and the cycle time is more than 4700 hours. The zinc-copper half-cell is stable and the cycle time is more than 4700 hours. -2 Current density, 1mAh•cm -2 The cycle life is greater than 1400 times at the capacity density.

[0019] Compared with the prior art, the present invention has the following beneficial effects:

[0020] 1. The long-lasting aqueous zinc-ion battery electrolyte prepared by the present invention has a polysaccharide zinc chelate additive containing a large number of strongly hydrophilic groups such as hydroxyl, carboxyl, and phosphate groups. The strong hydrogen bonding effect of these groups greatly reduces the activity of free water molecules. At the same time, they spontaneously and preferentially adsorb on the surface of the zinc negative electrode, forming a uniform zinc negative electrode interface protective layer, thereby inhibiting hydrogen evolution corrosion and side reactions, and improving cycle stability and long-lasting performance.

[0021] 2. The molecular structure of the polysaccharide zinc chelate additive in the present invention also contains zinc-philic ligands. These specific sites construct a directional transport and migration channel for zinc ions from the electrolyte to the zinc negative electrode interface, thereby achieving uniform deposition of zinc ions on the negative electrode surface and effectively inhibiting the growth of dendrites.

[0022] 3. This invention significantly improves the electrochemical properties of the zinc negative electrode, such as cycle stability and corrosion resistance, by adding a trace amount of a green, low-cost, and highly safe polysaccharide zinc chelate additive without changing the basic physical properties of the aqueous zinc ion battery electrolyte, such as pH value and viscosity, or modifying the typical battery assembly process. A zinc-zinc symmetrical battery using the long-lasting aqueous zinc ion battery electrolyte of this invention can achieve a high charge / discharge rate of 1 mA·cm -2 Current density, 1mAh·cm -2 The capacity density was maintained at a stable cycle for more than 4700 hours, and the zinc-copper half-cell was -2 Current density, 1mAh·cm -2 The cycle life is greater than 1400 times at the capacity density. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 (a) shows the image of the commercial zinc sheet after being immersed in the electrolyte of Example 1 for 12 days; Figure 1 (b) shows the image of the commercial zinc sheet after being immersed in the electrolyte of Example 2 for 12 days; Figure 1 (c) is an image of a commercial zinc sheet after being immersed in the electrolyte of Comparative Example 1 for 12 days;

[0024] Figure 2 (a) is a nano-infrared imaging image of the surface ether bond functional groups of a commercial zinc sheet after being immersed in the electrolyte of Example 1 for 12 days, rinsed and dried; Figure 2 (b) is a nano-infrared imaging image of the surface ether bonds of a commercial zinc sheet after being immersed in the electrolyte of Comparative Example 1 for 12 days, rinsed, and dried; Figure 2 (c) is a nano-infrared imaging image of the surface carboxyl functional groups of a commercial zinc sheet after being immersed in the electrolyte of Example 3 for 12 days, rinsed and dried; Figure 2 (d) is a nano-infrared imaging image of the carboxyl functional group of a commercial zinc sheet after being immersed in the electrolyte of Comparative Example 1 for 12 days, rinsed and dried;

[0025] Figure 3 (a) is a commercial zinc sheet in the electrolyte of Example 1 with a 5 mA·cm -2 SEM image of the surface after electroplating for 1 h at the current density; Figure 3 (b) is a commercial zinc sheet in the electrolyte of Example 2 with a 5 mA·cm -2 SEM image of the surface after electroplating for 1 h at the current density; Figure 3 (c) is a commercial zinc sheet in the electrolyte of Example 4 at 5 mA·cm -2 SEM image of the surface after electroplating for 1 h at the current density; Figure 3 (d) is the commercial zinc sheet in the electrolyte of Comparative Example 1 with a 5 mA·cm -2 SEM image of the surface after electroplating for 1 h at the current density;

[0026] Figure 4 The half-cells assembled with commercial zinc sheet and copper foil respectively and the 2M zinc sulfate aqueous solution obtained in Comparative Example 1 and the aqueous zinc ion battery composite electrolyte containing polysaccharide zinc chelating agent additive in Example 1, Example 3 and Comparative Example 2 were tested at 5 mA·cm -2 Current density, 1mAh·cm -2 Coulomb efficiency test comparison curve under capacity density;

[0027] Figure 5 Symmetrical cells assembled with commercial zinc flakes, 2M zinc sulfate aqueous solution obtained in Comparative Example 1, and aqueous zinc ion battery composite electrolytes containing polysaccharide zinc chelating agent additives in Example 1, Example 4, and Comparative Example 3 were tested at 1 mA·cm -2 Current density, 1mAh·cm -2 Time-voltage comparison chart of cycle stability test under capacity density;

[0028] Figure 6 The full cell assembled with commercial VO2 and the 2M zinc sulfate aqueous solution obtained in Comparative Example 1 and the aqueous zinc ion battery composite electrolyte containing polysaccharide zinc chelating agent additive in Example 1 was tested at 1A·g -1 Discharge specific capacity and Coulombic efficiency plots for cycling at different current densities. DETAILED DESCRIPTION

[0029] The technical solutions of the present invention are further specifically described below through examples. These examples are provided for the purpose of illustrating the present invention and are not intended to limit the present invention. All other examples obtained by persons of ordinary skill in the art based on the examples in this application without creative work are intended to fall within the scope of protection of this application.

[0030] The test methods used in the examples are conventional methods unless otherwise specified; the reagents and materials used are commercially available unless otherwise specified.

[0031] Example 1

[0032] Preparation of electrolyte: 5.74 g of zinc sulfate heptahydrate (ZnS04·7H20) was weighed and dissolved in 7.48 mL of deionized water to prepare a 2 mol / L (M) ZnS04solution for standby. 0.2 g of zinc hyaluronate (HA-Zn) powder (Mw= 40,000 Da) was added to the above ZnS04solution, and placed in an ultrasonic cleaner for shaking until completely dissolved, to obtain a colorless and clear electrolyte with a zinc hyaluronate concentration of 0.50 mmol / L.

[0033] Battery assembly: 50 pm thick commercial zinc foil was cut into a zinc electrode piece with a diameter of φ12 mm, washed with anhydrous ethanol and dried for standby; a glass fiber separator was cut into a round piece with a diameter of φ16 mm for standby; a commercial copper foil current collector was cut into a copper current collector round piece with a diameter of φ12 mm, washed with anhydrous ethanol and dried for standby. A commercial VO2electrode piece was cut into a VO2current collector round piece with a diameter of φ12 mm, washed with anhydrous ethanol and dried for standby. The zinc electrode piece, the separator, and the zinc electrode piece were stacked in sequence into a battery shell of CR2032 type, 60-100 pL of electrolyte was added to wet the inside, and a CR2032 type Zn||Zn symmetric button cell was assembled, which was marked as Zn||Zn-(HA-Zn) 0.50 . The copper current collector, the separator, and the zinc electrode piece were stacked in sequence into a battery shell of CR2032 type, 60-100 pL of electrolyte was added to wet the inside, and a CR2032 type Zn||Cu button cell was assembled, which was marked as Zn||Cu-(HA-Zn) 0.50 . The VO2current collector, the separator, and the zinc electrode piece were stacked in sequence into a battery shell of CR2032 type, 60-100 pL of electrolyte was added to wet the inside, and a CR2032 type Zn||VO2button cell was assembled, which was marked as Zn||VO2-(HA-Zn) 0.50 .

[0034] Battery test: the test method of Zn||Zn symmetric battery was as follows: constant current charging and discharging at a current density of 1 mA / cm 2 to 1 mAh / cm 2 , and so on. The test method of Zn||Cu half battery was as follows: constant current discharging at a current density of 5 mA / cm 2 for 12 min, and then constant current charging to 1 V at the same current density, and so on. The test method of Zn||VO2full battery was as follows: constant current charging at a current density of 1 A·g -1The charge-discharge test was carried out at a current density of 5 mA / cm2. In addition, the Tafel corrosion current test was carried out on the Zn||Zn symmetric battery, with parameters of -0.25 V to 0.25 V and a scanning rate of 1 mV / s.

[0035] Physicochemical property analysis: The zinc sheet was immersed in the 2M zinc sulfate electrolyte containing 0.50 mmol / L zinc hyaluronate additive for 5 mA·cm -2 After galvanizing at a current density for 1 h, the surface morphology of the zinc sheet was characterized by a scanning electron microscope; after the zinc sheet was immersed in the 2M zinc sulfate electrolyte containing 0.50 mmol / L zinc hyaluronate additive for 12 days, then rinsed and dried, the distribution of the zinc hyaluronate characteristic groups on the surface of the zinc sheet was characterized by a nanometer infrared spectrometer.

[0036] Example 2

[0037] This example was a parallel test similar to Example 1, and the concentration of zinc hyaluronate in the electrolyte was 0.25 mmol / L, and the remaining operation steps were the same as those in Example 1, to obtain a colorless and clear electrolyte. At the same time, the button-type battery was assembled in the manner of Example 1, wherein the Zn||Zn symmetric battery and the Zn||Cu half battery were respectively recorded as Zn||Zn-(HA-Zn) 0.25 , Zn||Cu-(HA-Zn) 0.25 .

[0038] Example 3

[0039] This example was a parallel test similar to Example 1, and zinc tannate was used as an electrolyte additive, with a concentration of 0.50 mmol / L (Mw=40,000 Da), and the remaining operation steps were the same as those in Example 1, to obtain a colorless and clear electrolyte. At the same time, the button-type battery was assembled in the manner of Example 1, wherein the Zn||Zn symmetric battery and the Zn||Cu half battery were respectively recorded as Zn||Zn-(CHO-Zn) 0.50 , Zn||Cu-(CHO-Zn) 0.50 .

[0040] Example 4

[0041] This example was a parallel test similar to Example 3, and the concentration of zinc tannate in the electrolyte was 0.25 mmol / L, and the remaining operation steps were the same as those in Example 3, to obtain a colorless and clear electrolyte. At the same time, the button-type battery was assembled in the manner of Example 1, wherein the Zn||Zn symmetric battery and the Zn||Cu half battery were respectively recorded as Zn||Zn-(CHO-Zn) 0.25 , Zn||Cu-(CHO-Zn) 0.25 .

[0042] Comparative Example 1

[0043] In this comparative example, no additives were added; the electrolyte consisted solely of a 2 mol / L ZnSO₄ solution. The remaining steps were identical to those in Example 1. Coin cells were assembled and tested as in Example 1, where the Zn||Zn symmetrical cell, Zn||Cu half-cell, and Zn||VO₂ full cell were designated Zn||Zn-Blank, Zn||Cu-Blank, and Zn||VO₂-Blank, respectively.

[0044] Comparative Example 2

[0045] In this comparative example, a high-precision balance was used to weigh 0.02 g of zinc hyaluronate and add it to 7.48 mL of a 2 M (mol / L) ZnSO4 solution to obtain an electrolyte solution with a concentration of 0.05 mmol / L. The remaining steps were the same as those in Example 1. Meanwhile, button cells were assembled and tested in the same manner as in Example 1, where the Zn||Zn symmetrical cell and the Zn||Cu half-cell were denoted as Zn||Zn-(HA-Zn) and Zn||Zn-(HA-Zn) respectively. 0.05 、Zn||Cu-(HA-Zn) 0.05 .

[0046] Comparative Example 3

[0047] In this comparative example, a high-precision balance was used to weigh 0.004 g of zinc tannate and add it to 7.48 mL of a 2 M (mol / L) ZnSO4 solution to obtain an electrolyte solution with a concentration of 0.01 mmol / L. The remaining steps were the same as those in Example 1. Furthermore, button cells were assembled and tested in the same manner as in Example 1, where the Zn||Zn symmetrical cell and the Zn||Cu half-cell were designated as Zn||Zn-(HA-Zn) and Zn||Zn-(HA-Zn) respectively. 0.01 and Zn||Cu-(HA-Zn) 0.01 .

[0048] Physicochemical properties analysis and electrochemical performance testing

[0049] Observe the zinc sheets soaked in the electrolyte in Example 1, Example 2 and Comparative Example 1. Figure 1 Specifically, the commercial zinc sheet was immersed in the aqueous zinc ion battery electrolyte containing the polysaccharide zinc chelating agent additive in Example 1 for 12 days. Figure 1 As shown in (a); the image of the commercial zinc sheet after being immersed in the aqueous zinc ion battery electrolyte containing the polysaccharide zinc chelating agent additive in Example 2 for 12 days is as shown in Figure 1 As shown in (b); the image of the commercial zinc sheet after being immersed in the 2M zinc sulfate aqueous solution electrolyte obtained in Comparative Example 1 for 12 days is as shown in Figure 1 As shown in (c) in the figure. Figure 1 (a) in Figure 1 (b) and Figure 1 As can be seen from (c) in the figure, a layer of white substance is adsorbed on the surface of the zinc sheets in Examples 1 and 2; while no white substance is found on the surface of the zinc sheet in Comparative Example 1, but a layer of shiny basic zinc sulfate by-product Zn4SO4(OH)6·5H2O is distributed. This preliminarily proves the adsorption distribution of zinc hyaluronate and zinc tannate on the zinc negative electrode, as well as their protective effects on the zinc negative electrode.

[0050] Since the molecular structures of zinc hyaluronate and zinc tannate contain characteristic groups such as ether bonds and carboxyl groups, Figure 2 The distribution of characteristic groups on the surface of the dried zinc sheet was further characterized using a nano-infrared spectrometer. Specifically, the nano-infrared imaging of the surface ether bond functional groups of the commercial zinc sheet after being immersed in the aqueous zinc ion battery electrolyte containing the polysaccharide zinc chelating agent additive in Example 1 for 12 days and then rinsed and dried is shown in FIG. Figure 2 As shown in (a); the nano-infrared imaging of the surface ether bonds of the commercial zinc sheet after being immersed in the 2M zinc sulfate aqueous electrolyte obtained in Comparative Example 1 for 12 days, rinsed and dried is shown in Figure 2 As shown in (b); the nano-infrared imaging of the surface carboxyl functional groups of the commercial zinc sheet after being immersed in the aqueous zinc ion battery electrolyte containing the polysaccharide zinc chelating agent additive in Example 3 for 12 days, rinsed and dried is shown in Figure 2 As shown in (c); the nano-infrared imaging of the carboxyl functional group of the commercial zinc sheet after being immersed in the 2M zinc sulfate aqueous electrolyte obtained in Comparative Example 1 for 12 days, rinsed and dried is shown in Figure 2 As shown in (d) in Example 1 ( Figure 2 Obvious ether bond signals can be found on the surface of the zinc sheet in (a). Figure 2 Obvious carboxyl signals can be found on the surface of the zinc sheet in (c), and they are evenly distributed on the surface of the zinc sheet. This shows that zinc hyaluronate and zinc tannate are evenly adsorbed on the surface of the zinc sheet, and also proves the uniform distribution of zinc ion transport shuttle sites (zinc-philic coordination structures) on it, which creates excellent conditions for the directional screening transport and uniform deposition of zinc ions. On the contrary, in comparative example 1 ( Figure 2 (b) Figure 2 (d) No ether bond and carboxyl group signals were observed on the surface of the zinc sheet immersed in zinc sulfate electrolyte.

[0051] The deposition morphology of the zinc negative electrode surface in Example 1, Example 2, Example 4 and Comparative Example 1 was characterized by SEM. Figure 3 Specifically, the commercial zinc sheet was subjected to 5 mA·cm -2 The SEM image of the surface after electroplating for 1h at the current density is as follows Figure 3As shown in (a); the commercial zinc sheet was subjected to 5 mA·cm -2 The SEM image of the surface after electroplating for 1h at the current density is as follows Figure 3 As shown in (b); the commercial zinc sheet was subjected to 5 mA·cm -2 The SEM image of the surface after electroplating for 1h at the current density is as follows Figure 3 As shown in (c); the commercial zinc sheet was subjected to 5 mA·cm in the 2M zinc sulfate aqueous solution electrolyte obtained in Comparative Example 1. -2 The SEM image of the surface after electroplating for 1h at the current density is as follows Figure 3 As shown in (d) in the figure.

[0052] Since the polysaccharide zinc chelator is evenly distributed on the zinc surface, it can construct a directional transmission channel for zinc ion shuttle. Figure 3 (a) in Example 2 ( Figure 3 (b) in Example 4 ( Figure 3 In (c)), the zinc ions exhibited horizontal growth deposition behavior, and were stacked in parallel and orderly on the negative electrode surface, eventually forming a uniform, dense, and core-refined deposition structure, which effectively inhibited the growth of zinc dendrites. In comparative example 1 ( Figure 3 In (d), the two-dimensional diffusion of zinc ions is evident, forming unevenly packed zinc clusters on the negative electrode surface with large, dispersed nuclei. SEM imaging also demonstrates that the hydrophilic polysaccharide zinc chelator additive contributes to a uniform zinc deposition morphology.

[0053] In Example 1, Zn||Cu-(HA-Zn) 0.50 、Zn||Cu-(CHO-Zn) in Example 3 0.50 , Zn||Cu-Blank in Comparative Example 1 and Zn||Cu-(HA-Zn) in Comparative Example 2 0.50 The coulombic efficiency and cycle life curves of button half-cells are as follows: Figure 4 Comparative Example 1 and Comparative Example 2 at 5 mA·cm -2 Current density, 1mAh·cm -2 The stable cycle numbers at the capacity density were less than 160 and 180 cycles, respectively, and the coulombic efficiency was only 99.1% and 99.26%, respectively, showing poor cycle performance. Since the polysaccharide zinc chelate additive contains a large number of hydrophilic hydroxyl groups and zinc-philic coordination structures, it can effectively inhibit the hydrogen evolution side reaction and dendrite growth. -2 Current density, 1mAh·cm -2The stable cycles at the capacity density are greater than 1400 cycles and 850 cycles, respectively, and the coulombic efficiencies are up to 99.65% and 99.59%, respectively, which can significantly improve the cycle life and coulombic efficiency, so as to obtain a zinc ion battery with long cycle performance and high rate performance.

[0054] Zn||Zn-(HA-Zn) in Example 1 0.50 Zn||Cu-(CHO-Zn) in Example 4 0.25 Zn||Zn-Blank in Comparative Example 1 and Zn||Cu-(CHO-Zn) in Comparative Example 3 0.01 The cycle stability and cycle life curves of the symmetrical button cells are shown in Figure 5 Example 1 and Example 4 can stably cycle at 1 mA·cm -2 -2 current density, 1 mAh·cm -2 -2 capacity density for more than 4700 h and 3100 h, and exhibit excellent cycle stability and life; while Comparative Example 1 and Comparative Example 3 can stably cycle for less than 120 h and 190 h at 1 mA·cm -2 -2 current density, 1 mAh·cm -2 -2 capacity density, and their cycle stability and life are far lower than those of Example 1 and Example 4. The test results of the zinc-zinc symmetrical cells prove that the addition of a small amount of polysaccharide zinc chelate can effectively prolong the cycle life and stability of the cells.

[0055] Zn||VO2-(HA-Zn) in Example 1 0.50 The capacity retention and cycle life curves of the full cells of Zn||VO2-(HA-Zn) in Example 1 and Zn||VO2-Blank in Comparative Example 1 are shown in Figure 6 Example 1 can stably cycle the full cell at 1 A·g -1 -1 current density for up to 910 cycles, and there is no obvious capacity decay; while the full cell of Comparative Example 1 at 1 A·g -1 -1 current density has a significant decrease in capacity retention to below 60% after 209 cycles of charge and discharge. The test results of the full cells prove that the addition of a small amount of polysaccharide zinc chelate has a significant effect on improving the capacity retention and cycle life of the cells.

[0056] In summary, the polysaccharide zinc chelate additive in the application contains a large number of hydrophilic groups and zincophilic coordination groups, wherein the strong hydrophilic hydroxyl, carboxyl, phosphoric acid group and the like have strong hydrogen bonding effect, which can greatly reduce the activity of free water molecules, optimize the solvation structure of zinc ions, and spontaneously adsorb on the surface of the zinc negative electrode to form a uniform protective layer, thereby inhibiting hydrogen evolution corrosion and side reactions, and improving the cycle stability and long-term performance of the battery. At the same time, the zincophilic coordination sites in the molecular structure of the polysaccharide zinc chelate additive can act as a directional transport migration channel for zinc ions, thereby realizing uniform deposition of zinc ions on the negative electrode surface, effectively inhibiting the growth of dendrites, and overall improving the cycle performance and rate performance of the aqueous zinc ion battery.

[0057] The above examples are only used to illustrate the technical solutions of the present application, but not to limit them; although the present application has been described in detail with reference to the foregoing examples, those skilled in the art should understand that they can still modify the technical solutions recorded in the foregoing examples, or make equivalent replacement for part or all of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A zinc ion battery electrolyte containing a polysaccharide zinc chelate, characterized in that: The electrolyte includes a deionized water solvent, a soluble zinc salt solute and a polysaccharide zinc chelate additive, wherein the concentration of the polysaccharide zinc chelate additive in the electrolyte is 0.20 mmol / L to 1.35 mmol / L; the polysaccharide zinc chelate additive is ultrasonically dissolved so that the additive is uniformly dispersed in the electrolyte; the polysaccharide zinc chelate additive is any one or more of zinc hyaluronate, zinc tannate, seaweed polysaccharide zinc, rice bran polysaccharide zinc chelate, and Polygonum multiflorum polysaccharide zinc chelate.

2. The zinc ion battery electrolyte containing polysaccharide zinc chelate according to claim 1, characterized in that: The soluble zinc salt solute is any one or more of zinc sulfate, zinc acetate, zinc nitrate, zinc chloride, zinc bromide, zinc trifluoromethanesulfonate, and zinc iodide.

3. The zinc ion battery electrolyte containing polysaccharide zinc chelate according to claim 1, characterized in that: The concentration of the soluble zinc salt solute is 0.5 mol / L to 4.0 mol / L.

4. The zinc ion battery electrolyte containing polysaccharide zinc chelate according to claim 1, characterized in that: The polysaccharide zinc chelate additive is zinc hyaluronate.

5. The zinc ion battery electrolyte containing polysaccharide zinc chelate according to claim 4, characterized in that: The concentration of the polysaccharide zinc chelate additive in the electrolyte is 0.50 mmol / L.

6. A method for preparing a zinc ion battery electrolyte containing a polysaccharide zinc chelate according to claim 1, characterized in that The steps include: Step S1: mixing a soluble zinc salt and deionized water in proportion, and dissolving them by ultrasonication at room temperature until the solution is completely clear and transparent without precipitation, to obtain a mixed solution; Step S2: adding the polysaccharide zinc chelate additive to the mixed solution of step S1, and dissolving the polysaccharide zinc chelate additive by ultrasonication until the polysaccharide zinc chelate additive is completely dissolved to obtain an aqueous zinc ion battery electrolyte.

7. Use of the zinc ion battery electrolyte of the polysaccharide zinc chelate according to claim 1 in an aqueous zinc ion battery.

8. The application according to claim 7, characterized in that: The aqueous zinc ion battery is any one of a zinc-zinc symmetrical battery, a zinc-copper half-cell, and a zinc-vanadium dioxide full battery.

9. The application according to claim 8, characterized in that: The zinc-zinc symmetrical battery consists of a 50µm thick zinc foil, a glass fiber separator, and an aqueous zinc-ion battery electrolyte; the zinc-copper half-cell consists of a commercial 50µm thick zinc foil, a commercial copper foil current collector, a glass fiber separator, and an aqueous zinc-ion battery electrolyte; the zinc-vanadium dioxide full battery consists of a commercial 50µm thick zinc foil, a commercial vanadium dioxide positive electrode sheet, and an aqueous zinc-ion battery electrolyte.

10. The application according to claim 8, characterized in that: Symmetric zinc-zinc battery at 1 mA·cm -2 Current density, 1mAh•cm -2 The capacity density is stable and the cycle time is more than 4700 hours. The zinc-copper half-cell is stable and the cycle time is more than 4700 hours. -2 Current density, 1mAh•cm -2 The cycle life is greater than 1400 times at the capacity density.

Images