Large-scale construction of hydrogen bond network of aqueous zinc ion battery by hydroxyl-rich multifunctional sugar

Abstract

The invention discloses an application of hydroxyl-rich sugar in an aqueous zinc ion battery, an electrolyte comprises a zinc salt and a solvent, and the solvent comprises water and D-fructose. The concentration of the D-fructose is 0 to 1 mol / L. The mixed electrolyte is formed by adding a proper amount of D-fructose into the zinc salt, so that the stability of the zinc negative electrode is effectively improved, the generation of byproducts is reduced, and the cycling stability of the zinc ion battery is improved. The lithium ion battery can be circulated for 2350 hours under the condition of 1 mA cm <-21 > mAh cm <-2 >, the coulombic efficiency of the battery is high, and the cost is low.

Description

Technical Field

[0001] The invention relates to the field of electrochemical energy storage, and in particular to the preparation of a hydroxyl-rich electrolyte for an aqueous zinc ion battery and the application of the battery. Background Art

[0002] With the development of smart electronic devices, electric vehicles, large-scale energy storage and other fields, people have higher and higher requirements on the energy density, fast charging and discharging performance and safety performance of energy storage devices. Lithium-ion batteries are widely used in various portable electronic devices due to their high energy density, excellent cycle stability and high coulombic efficiency. However, the shortage of lithium resources, high cost and battery safety issues have limited their large-scale application. In contrast, zinc resources are abundant, low cost, high safety and have a high theoretical specific capacity (820 mAh g -1 ), therefore, zinc-ion batteries have greater development prospects.

[0003] Aqueous zinc-ion batteries (AZIBs) are a new type of environmentally friendly battery with the advantages of simple preparation process, non-toxic and low-cost battery materials, safe and environmentally friendly aqueous electrolytes, and high energy density. Therefore, aqueous zinc-ion batteries are expected to be used in large-scale energy storage grid systems. However, zinc dendrites, hydrogen evolution reactions, and electrode corrosion during the reaction process greatly affect the cycle performance and stability of zinc batteries. These adverse reactions have greatly affected the application of aqueous zinc-ion batteries.

[0004] Functional groups play a huge role in improving the performance of aqueous zinc ion batteries. Only a small amount of them need to be added to significantly improve the performance. The present invention introduces hydroxyl-rich sugars, which effectively improve the interaction of hydrogen bonds between water molecules in aqueous electrolytes and improve the electrochemical performance of aqueous batteries. At present, hydroxyl-rich additives used in aqueous zinc ion batteries include D-arabinose, trehalose, D-trehalose, etc. These additives can effectively regulate Zn 2+ with SO 4 2- and H 2 O molecules, thereby promoting the 2+ The present invention adopts an advanced technical solution and uses D-fructose to improve the cycle stability of zinc ion batteries. The cycle time exceeds 2300 hours. Summary of the invention

[0005] The purpose of the present invention is to provide an electrolyte rich in hydroxyl and its application in AZIBS, solve the problem of conventional electrolyte dendrite growth and large-scale production of by-products, and promote uniform deposition of zinc negative electrode. By adding an appropriate amount of D-fructose to zinc salt, reversible zinc deposition / dissolution is achieved, the cycle stability of positive electrode materials is improved, and thus the cycle performance of zinc ion batteries at room temperature is improved.

[0006] To achieve the above objectives, the present invention adopts the following technical solutions: Low-temperature aqueous zinc-ion battery electrolyte is mainly composed of zinc salt and water.

[0007] Based on the above scheme, preferably, the zinc salt is zinc sulfate, zinc chloride, zinc nitrate, zinc acetate, zinc phosphate, Any of zinc fluoromethanesulfonate, zinc bis(trifluoromethanesulfonyl)imide, zinc tetrafluoroborate, zinc hexafluorophosphate, zinc bis(oxalate)borate The invention further preferably comprises one or a combination of at least two of them, and zinc sulfate is further preferred.

[0008] Based on the above scheme, the organic solvent additive is D-fructose.

[0009] The concentration of the electrolyte salt is 0 M to 1 M, where M is the molar concentration, that is, the ratio of the number of moles of the electrolyte salt to the volume of the solvent (M: mol L -1 .

[0010] Based on the above scheme, preferably, the zinc salt concentration is 0.1-2.5 mol L -1 (M), more preferably 1 M.

[0011] Based on the above scheme, preferably, the content of D-fructose in the mixed electrolyte is 0-1 mol L -1 The low-temperature aqueous ion battery electrolyte is specifically ZS, GT-0.1, GT-0.5, and GT-1.

[0012] Based on the above scheme, preferably, the zinc ion battery is composed of a positive electrode, a membrane and a zinc negative electrode material. The positive electrode is a zinc ion insertion and extraction type material, and the manganese-based material is MnO 2 , Ca 0.28 MnO 2 One or two of the following; the vanadium-based material is V 2 O 5 、V 2 O 3 、Zn 2 V 2 O 7 And Na 3 VO 4 One or more of the following; the membrane is a glass fiber membrane or a Celgard membrane; the zinc negative electrode is zinc foil or zinc powder.

[0013] Innovation A hydroxyl-rich sugar, D-fructose, was introduced, which can improve the solvation structure of aqueous solvents and enhance the adsorption capacity of solvents. GT molecules can be preferentially adsorbed to the surface of zinc negative electrode, making zinc dendrites grow three-dimensionally and greatly reducing the generation of by-products. GT molecules contain a large number of hydroxyl groups, which can destroy the original hydrogen bonds in water molecules. GT molecules form stronger hydrogen bonds with water molecules, thus improving Zn 2+ with SO 4 and H 2 The interaction between the O molecules inhibits the activity of water molecules and improves the stability during the reaction. In summary, the GT molecules achieve compact zinc deposition, optimize the interface reaction, and improve the cycle performance.

[0014] Beneficial effects of the present invention: The innovative use of a functional electrolyte can produce reversible deposition and uniform fine zinc particles, greatly stabilizing the zinc anode and Zn||NVO full battery. GT molecules can greatly improve the surface condition and solvation structure of the zinc anode, thereby improving the cycle performance of the battery. -2 , 1 mAh cm -2 Under the condition of , the battery can stably cycle for 2350 h. The battery assembled with Cu can stably cycle for 800 cycles. The coulombic efficiency is stable. When the battery is assembled with NVO material, it can stably cycle for 1000 cycles. What is more remarkable is that its soft-pack battery also has excellent performance and can realize practical functions such as lighting a light bulb. This shows that the future prospects of zinc-ion batteries are bright and the application value is high. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 : Raman spectra of various electrolytes in Example 1 at 3000 ~ 3800 cm -1 Raman peak fitting diagram of the range.

[0016] Figure 2 : Infrared spectra of various electrolytes in Example 2.

[0017] Figure 3 : CA diagram of the symmetrical battery assembled with ZS and GT-0.5 electrolytes at -150 mV in Example 3.

[0018] Figure 4 :In Example 4, the symmetrical battery assembled with ZS and GT-0.5 electrolytes was measured at different temperatures and the Nyquist plot was fitted with the Arrhenius curve.

[0019] Figure 5 : XRD diagram of zinc foil in Example 5 after cycling in various electrolytes.

[0020] Figure 6: SEM images of zinc foil in Example 6 after cycling in various electrolytes.

[0021] Figure 7 : Constant current charge and discharge curves of the Zn||Zn symmetric battery in Example 7 at room temperature in various electrolytes.

[0022] Figure 8 : Cycling stability diagram of Zn||NVO button cell in Example 8.

[0023] Fig. 9 : Cycling stability diagram of Zn||NVO soft pack battery in Example 9.

[0024] Fig.10 : The soft-pack battery in Example 10 lights up the light strip. DETAILED DESCRIPTION

[0025] The following examples are provided to further illustrate the present invention, but are not intended to limit the scope of the present invention. Example

[0026] Prepare 1 M zinc sulfate electrolyte (ZS) To prepare 1 M zinc sulfate, the amount of D-fructose added was 0.10 mol L -1 (GT-0.1).

[0027] To prepare 1 M zinc sulfate, add 0.5 mol L D-fructose. -1 (GT-0.5).

[0028] To prepare 1 M zinc sulfate, the amount of D-fructose added was 1 mol L -1 (GT-1).

[0029] The above electrolyte was tested by Raman spectroscopy, and the 3000 ~ 3800 cm -1 The Raman peaks in the range are fitted. The fitting results are shown in Figure 1 , Example

[0030] The hydrogen bonding interaction between GT molecules and water molecules was tested by infrared spectroscopy for the ZS, GT-0.1, GT-0.5 and GT-1 electrolytes in Example 1.

[0031] Test results see Figure 2 After adding GT, the OH bonds in the electrolyte move to the high field. Example

[0032] The CA of the symmetrical battery assembled with the ZS and GT-0.5 electrolytes in Example 1 was measured at -150 mV.

[0033] Test results see Figure 3 The chronoamperometric curve can represent the transition from two-dimensional to three-dimensional deposition. It can be seen that the GT sample started three-dimensional deposition at 10 s, while the ZS sample ended the two-dimensional deposition and entered three-dimensional deposition at 50 s, which further indicates that the GT molecule is conducive to the uniform deposition of zinc ions on the zinc negative electrode. Example

[0034] The symmetrical battery assembled with the ZS and GT-0.5 electrolytes in Example 1 was tested for Nyquist plots at different temperatures and fitted with Arrhenius curves.

[0035] Test results see Figure 4 The activation energy of the battery assembled with GT is significantly lower than that of the battery assembled with pure ZS. Example

[0036] ZS and GT-0.5 electrolytes in Example 1.

[0037] The button cell test was conducted to assemble a Zn||Zn symmetrical battery. ZS and GT-0.5 electrolytes were used respectively at 1 mAcm -2 , 1mA cm -2 Constant current charge and discharge test was carried out under the conditions of

[0038] After 25 cycles of deposition, the zinc negative electrode was washed with deionized water, dried, and the surface of the zinc foil was analyzed by XRD. Figure 5 After cycling in ZS, a large amount of Zn 4 SO 4 (OH) 6 ·xH 2 O hydrogen evolution byproduct. However, the byproducts on the surface of zinc foil after cycling in 0.25 L-Cys were greatly reduced. The above results show that hydrogen evolution corrosion of zinc is greatly inhibited in 0.25 L-Cys mixed electrolyte. Example

[0039] The zinc negative electrode after the ZS and GT-0.5 electrolyte cycles in Example 4.

[0040] The surface of zinc foil was analyzed by SEM. The test results are shown in Figure 6 In GT-0.5, the zinc deposition is uniform and dense, while in ZS, the zinc deposition is loose and there are a large number of irregular particles. This shows that GT electrolyte can significantly improve the zinc deposition morphology, thereby inhibiting the formation of zinc dendrites. Example

[0041] ZS, GT-0.1, GT-0.5 and GT-1 electrolytes in Example 1.

[0042] The five electrolytes were used to assemble a Zn||Zn symmetric cell with a power of 1 mA cm -2 , 1 mAh cm -2 The charge and discharge tests were performed at 25°C as the test conditions.

[0043] Test results see Figure 7 At room temperature, compared with the traditional ZS electrolyte, the GT-0.5 mixed electrolyte The stable cycle time of the Zn||Zn symmetric battery is significantly improved, which shows that the stability of the zinc negative electrode is greatly improved due to the improvement of the zinc deposition morphology and the inhibition of hydrogen evolution corrosion by the Zn||Zn mixed electrolyte. Example

[0044] The ZS, GT-0.1, GT-0.5 and GT-1 electrolytes in Example 1 were used.

[0045] Preparation of NVO cathode material: 2 g V 2 O 5 The powder was added to 30 mL of 2M NaCl aqueous solution and then stirred at 30 °C for 96 h. The product was washed with deionized water several times and freeze-dried to obtain the NVO positive electrode material. The prepared NVO was mixed with Ketjen-black conductive agent and PVDF binder in a mass ratio of 7:2:1 in N-methyl-pyrrolidone to form a uniform slurry, which was then coated on a stainless steel mesh. After drying at 70 °C for 8 h, the NVO cathode was cut into discs with a diameter of 12 mm. The surface mass loading of NVO in each cathode was controlled to be ~1.4 mg cm -2 To suppress the dissolution of NVO, 1 M Na 2 SO 4 .

[0046] Battery assembly: ZS and GT-0.5 electrolytes in Example 1 were used to assemble Zn||NVO full cells at 5 A g -1 Perform charge and discharge tests for the test conditions.

[0047] Test results see Figure 8 The Zn||NVO full battery using ZS electrolyte has a lower specific capacity. However, the Zn||ZVO full battery using GT-0.5 mixed electrolyte still maintains a specific capacity of 100 mAh g after 1000 cycles. -1 This indicates that GT-0.5 electrolyte can achieve stable operation of zinc ion batteries. Example

[0048] The Zn||NVO soft-pack battery using GT-0.5 mixed electrolyte has high cycling stability.

[0049] Embodiment 10: The soft-pack battery using GT-0.5 hybrid electrolyte can light up the light strip at room temperature, indicating that GT-0.5 hybrid electrolyte has practical application value.

Claims

1. An aqueous zinc ion battery electrolyte, characterized in that: The electrolyte comprises zinc salt and a solvent, and the solvent comprises water and D-fructose.

2. The electrolyte according to claim 1, characterized in that The D-fructose concentration is 0-1 mol / L.

3. The electrolyte according to claim 2, characterized in that The D-fructose concentration gradient is 0 mol / L, 0.1 mol / L, 0.5 mol / L, and 1 mol / L.

4. The electrolyte according to claim 1, characterized in that The zinc salt is any one of zinc sulfate, zinc chloride, zinc nitrate, zinc acetate, zinc phosphate, zinc trifluoromethanesulfonate, zinc bistrifluoromethanesulfonyl imide, zinc tetrafluoroborate, zinc hexafluorophosphate, and zinc bisoxalate borate, or a combination of at least two thereof.

5. The electrolyte according to claim 4, characterized in that The zinc salt is zinc sulfate.

6. The electrolyte according to claim 1, characterized in that The concentration of the zinc salt in the electrolyte is 1 mol / L.

7. An aqueous zinc ion battery, characterized in that: The aqueous zinc ion battery comprises the electrolyte according to any one of claims 1 to 6.

8. The zinc ion battery according to claim 7, characterized in that: The zinc ion battery comprises a positive electrode, a membrane and a zinc negative electrode; the positive electrode is made of a zinc ion embedding and releasing material, and the zinc ion embedding and releasing material is a manganese-based material, a vanadium-based material or a combination thereof; the manganese-based material is MnO2, Ca 0.28 The vanadium-based material is one or more of V2O5, V2O3, Zn2V2O7 and Na3VO4; the membrane is a glass fiber membrane or a Celgard membrane; the zinc negative electrode is zinc foil or zinc powder.

9. The zinc ion battery according to claim 8, characterized in that: The positive electrode is Na3VO4 (NVO); the membrane is a glass fiber membrane; and the zinc negative electrode is zinc foil.

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