Method for in-situ construction of ZnS-based solid electrolyte interface layer by using sulfur-free additive

Abstract

The invention provides a method for in-situ construction of a ZnS-based solid electrolyte interface layer by using a sulfur-free additive, and the method comprises the step of adding a small amount of sulfur-free N-acetyl glucosamine (NAG) organic additive into a conventional ZnSO4 electrolyte of an aqueous zinc ion battery for modification. In the charging and discharging process, ZnSO4 and NAG react, and a ZnS-based composite solid electrolyte interface (SEI) layer is formed on the surface of a zinc electrode in situ, so that the problems of dendritic crystals, hydrogen evolution, corrosion and the like are effectively inhibited, the cycle life of the zinc ion battery is obviously prolonged, and the rate capability of the zinc ion battery is obviously improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of new energy materials, and particularly relates to a method for in-situ constructing a ZnS-based solid electrolyte interface layer without sulfur additives. Background Art

[0002] Aqueous zinc-ion batteries (AZIBs) have attracted extensive attention due to the unique properties of zinc metal anodes, including abundant reserves, high theoretical capacity (820 mAh g -1 , 5855 mAh cm -3 ), and low redox potential (-0.76 V compared to the standard hydrogen electrode). Although the aqueous solvents in AZIBs are safe, economical, efficient, and environmentally friendly, and contribute to the rapid diffusion of zinc ions, they cause serious interfacial side reactions, such as hydrogen evolution and corrosion. These side reactions lead to poor cycle stability and low Coulombic efficiency of AZIBs. The inherent surface defects of the zinc anode result in uneven electric field distribution and uneven zinc ion distribution, leading to zinc dendrite growth and subsequent battery short circuit. These problems hinder the practical application of AZIBs.

[0003] In recent years, organic / inorganic composite solid electrolyte interface layers (SEIs) with high zinc ion conductivity and mechanical strength have attracted extensive attention. Patent Application No. CN202411158933.3, Invention Title "A Gradient Rigid-Flexible Coupled Solid Electrolyte Interface Enhanced Zinc-Ion Battery and Its Preparation Method", is in an electrolyte system of "water-in-salt" of zinc trifluoromethanesulfonate (Zn(OTf)2) and lithium bis(trifluoromethanesulfonyl)imide (LiTFSI). In ZnSO4 electrolyte, "An Electrolyte for Constructing a Solid Electrolyte Interface in Aqueous Zinc Batteries and Its Battery" (Patent Application No. CN202411227493.2) is an aqueous solution of zinc sulfate with a ZnSiF6 additive. The formed SEI layer has porous basic zinc sulfate (ZHS) as the skeleton, and ZnF2 is embedded in it to form a nanoscale zinc ion transport channel.

[0004] Although the electrochemical performance has been improved, these fluorine (F)-containing substances are usually expensive, thus weakening the low-cost advantage of AZIBs. More importantly, these F-containing substances usually contain strong C-F bonds and exhibit high resistance to degradation in the natural environment. Once an accidental spill occurs, these substances will cause long-term environmental and biological damage.

[0005] At the same time, among all zinc salts, ZnSO4 is one of the most promising zinc salts for AZIBs due to its low cost, non-toxicity, high stability, and excellent environmental friendliness. Given that ZnS exhibits excellent Zn 2+ ion conductivity and makes it a suitable component of the SEI layer, ZnSO4 is an ideal precursor for constructing a ZnS-based SEI layer. However, SO42- The anion has high chemical and electrochemical stability and is difficult to decompose to form the ZnS-based SEI layer. It only acts as an anion to maintain the charge balance of the electrolyte. Therefore, it is urgent to find a method to 2- A method for synthesizing a composite SEI layer can not only make full use of sulfate, but also circumvent the problems of high cost and environmental damage caused by the incorporation of F-containing substances. Summary of the invention

[0006] The purpose of the present invention is to solve the problems in the above-mentioned background technology and provide a method for in-situ construction of a ZnS-based solid electrolyte interface layer without sulfur additives.

[0007] The present invention uses the strong interaction between N-acetylglucosamine (NAG) additive and zinc electrode to adjust the solvation structure and preferentially adsorb on the surface of zinc electrode, and in situ constructs an organic / inorganic composite SEI layer containing zinc chelate, ZnS and ZnCO3. Through the optimization of hydrated zinc ions and electrolyte / electrode interface, not only the side reactions related to water are effectively suppressed, but also the desolvation process of zinc ions is accelerated, thereby significantly reducing the generation of by-products and promoting the uniform deposition of zinc ions.

[0008] The present invention adopts the following technical solution: A method for in-situ construction of a ZnS-based solid electrolyte interface layer without sulfur additives, the method comprising the following steps: (1) Preparing a mixed solution: uniformly dispersing a certain amount of ZnSO4 and N-acetylglucosamine in deionized water to obtain a uniform mixed solution; (2) Assembling a battery: Using the mixed solution as the electrolyte, it is applied to a button cell; (3) In situ construction of ZnS-based composite SEI layer: During the charge and discharge process, due to the reaction between ZnSO4 and N-acetylglucosamine, a ZnS-based SEI layer is formed in situ on the surface of the zinc electrode.

[0009] Furthermore, ZnSO4 is ZnSO4·1H2O or ZnSO4·7H2O.

[0010] Furthermore, in the mixed solution, ZnSO4 solution is the main component of the electrolyte, and N-acetylglucosamine is used as an additive.

[0011] Furthermore, the molar concentration of ZnSO4 ranges from 1 to 2 mol / L.

[0012] Furthermore, the molar concentration of N-acetylglucosamine ranges from 0.1 to 0.8 mol / L.

[0013] Further, the coin-type battery used is any one of a Zn / / Zn symmetric battery, a Zn / / Cu half-cell, and a Zn / / Na5V 12 O 32 full cell.

[0014] Further, the organic matter of the ZnS-based composite SEI layer is a zinc chelate, and the inorganic matters are ZnS and ZnCO3.

[0015] Advantages of the present invention: N-acetylglucosamine is introduced as a multifunctional electrolyte additive to achieve a stable and reversible Zn electrode. During the electrochemical cycling process, NAG reacts with ZnSO4 to in-situ form a stable composite SEI layer on the zinc electrode, including organic (zinc chelate) and inorganic (ZnS and ZnCO3) components, effectively regulating the uniform deposition of Zn 2+ . Therefore, the Zn / / Zn symmetric battery based on the NAG additive can stably operate for 6500 h at 0.5 mA cm -2 and reach 3600 h at 1 mA cm -2 , showing excellent cycling performance and rate performance, significantly exceeding that of the symmetric battery constructed based on the ZnSO4 electrolyte. In the Zn / / Cu half-cell, the average Coulombic efficiency of 800 cycles is as high as 99.6%. In addition, the Zn / / NVO full cell with the NAG additive also shows significantly enhanced cycling stability and rate performance. This work provides new insights into the synthesis mechanism of the organic / inorganic interface layer on the zinc anode for highly reversible AZIBs. Description of the Drawings

[0016] Figure 1 is a comparative diagram of cyclic polarization curves of the Zn / / Zn symmetric battery assembled based on the comparative example and Example 3 of the present invention at 0.5 mA cm -2 and 0.5 mAhcm -2 current densities.

[0017] Figure 2 is a comparative diagram of cycles of the Zn / / Zn symmetric battery assembled based on the comparative example and Example 3 of the present invention at 1 mA cm -2 and 1 mAh cm -2 current densities.

[0018] Figure 3 is a comparative diagram of rate performance of the Zn / / Zn symmetric battery assembled based on the comparative example and Example 3 of the present invention.

[0019] Figure 4 is a comparative diagram of the Zn / / Cu half-cell assembled based on the comparative example and Example 3 of the present invention at 1 mA cm -2and 1 mAh cm -2 CE cycle comparison diagram at the current density.

[0020] Figure 5 For the Zn / / Na5V assembled based on the comparative example and Example 3 of the present invention 12 O 32 Cycle comparison diagram of the full cell.

[0021] Figure 6 HRTEM diagram of the zinc electrode after the battery cycle based on Example 3 of the present invention.

[0022] Figure 7 XPS depth profiles of C1s, N1s and S2p on the surface of the zinc electrode after the battery cycle based on Example 3 of the present invention.

[0023] Figure 8 SEM comparison diagram of the zinc electrode after the cycle of the Zn / / Zn symmetric cell assembled based on the comparative example and Example 3 of the present invention.

[0024] Figure 9 Formation process of the SEI layer and its TEM diagram. Detailed implementation mode

[0025] To make the objectives, technical solutions and advantages of the present invention clearer, the technical solutions in the present invention will be clearly and completely described below. Obviously, the described embodiments are some, but not all, of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art without making creative efforts based on the embodiments in the present invention belong to the scope of protection of the present invention.

[0026] As Figure 9 shown, the NAG additive of the present invention plays a key role in the formation of the composite SEI layer. During the charge and discharge process, it not only decomposes to generate an organic phase (Zn chelate), but also assists SO4 2- to be reduced to form inorganic phases of ZnS and ZnCO3, thereby in-situ constructing a ZnS-based composite SEI layer on the zinc electrode. The specific method is as follows: Example 1 3.6 g of zinc sulfate monohydrate and 0.22 g of N-acetylglucosamine were uniformly dispersed in 10 mL of deionized water to prepare a ZnSO4-2+NAG-0.1 electrolyte.

[0027] Example 2 3.6 g of zinc sulfate monohydrate and 1.10 g of N-acetylglucosamine were uniformly dispersed in 10 mL of deionized water to prepare a ZnSO4-2+NAG-0.5 electrolyte.

[0028] Example 3 3.6 g of zinc sulfate monohydrate and 1.76 g of N-acetylglucosamine were uniformly dispersed in 10 mL of deionized water to prepare a ZnSO4-2+NAG-0.8 electrolyte solution.

[0029] Example 4 3.6 g of zinc sulfate monohydrate and 1.98 g of N-acetylglucosamine were uniformly dispersed in 10 mL of deionized water to prepare a ZnSO4-2+NAG-0.9 electrolyte solution. After standing, white precipitates appeared in this electrolyte solution, reducing the stability of the electrolyte solution and affecting the battery cycle life. Therefore, it was not used for the assembly of coin cells.

[0030] Example 5 1.8 g of zinc sulfate monohydrate and 1.98 g of N-acetylglucosamine were uniformly dispersed in 10 mL of deionized water to prepare a ZnSO4-1+NAG-0.8 electrolyte solution.

[0031] Example 6 2.7 g of zinc sulfate monohydrate and 1.98 g of N-acetylglucosamine were uniformly dispersed in 10 mL of deionized water to prepare a ZnSO4-1.5+NAG-0.8 electrolyte solution.

[0032] Experimental content: A pure 2M ZnSO4 solution was used as a comparative example. The electrolyte solutions of the comparative example and Example 3 were assembled into Zn / / Zn symmetric cells, Zn / / Cu half-cells, and Zn / / Na5V 12 O 32 full cells, and the battery performance was tested on Neware.

[0033] Experimental results: The Zn / / Zn symmetric cell assembled based on Example 3 of the present invention had a cycle life of up to 6500 hours at 0.5 mA cm -2 and 0.5 mAh cm -2 as shown). In addition, the cycle life of the Zn / / Zn symmetric cell at 1 mA cm Figure 1 and 1 mAh cm -2 and 1 mAh cm -2 was significantly extended to 3600 hours, while the cycle life of the comparative example Zn / / Zn symmetric cell was only 110 hours (as Figure 2 shown). In addition, Figure 3 shows the rate performance of the Zn / / Zn symmetric cells assembled based on the comparative example and Example 3. The introduction of the NAG additive significantly improved the rate performance of the zinc-ion battery. Figure 4 Figure [X] is the Zn / / Cu half-cell assembled based on Example 3. At 1 mA cm -2 and 1 mAh cm -2At a current density of, the average Coulombic efficiency after 800 cycles is as high as 99.6%. Figure 5 is based on the Zn / / Na5V assembled from the comparative example and Example 3 12 O 32 Cycle comparison diagram of the battery. After introducing the NAG additive, the cycle stability of the battery is significantly improved.

[0034] To detect the generated SEI layer, it was detected by high-resolution transmission electron microscopy (HRTEM) imaging that the thickness of the SEI layer is about 18 nm (as Figure 6 shown). The results show that the NAG additive plays a key role in the formation of the F-free composite SEI layer. In this process, the NAG additive not only decomposes to generate an organic phase (zinc chelate), but also assists in the reduction of SO4 2- to jointly achieve the formation of inorganic phases of ZnS and ZnCO3. In addition, to explore the composition of the SEI layer, Ar + sputtered X-ray photoelectron spectroscopy (XPS) was also used to analyze the zinc electrode after cycling. The results are as Figure 7 shown. The SEI layer contains organic (zinc chelate) and inorganic (ZnS and ZnCO3) components. The detection results are consistent with the HRTEM results, further verifying the composition of the SEI layer. At the same time, to prove the effective role of this ZnS-based SEI layer in zinc ion deposition during cycling, the Zn / / Zn symmetric batteries assembled based on Example 3 and the comparative example were disassembled after cycling, and the morphology of the zinc electrode was observed by scanning electron microscopy (SEM), as Figure 8 shown. It can be clearly seen that after cycling in the electrolyte of the comparative example, a large number of disordered and loosely packed flaky Zn aggregates and by-products are formed on the surface of the zinc electrode; on the contrary, in the case of adding NAG, due to uniform Zn deposition / dissolution, a smooth and uniform surface morphology is observed.

[0035] The present invention provides a method for constructing a ZnS-based SEI layer using a sulfur-free additive, thereby realizing a highly reversible zinc negative electrode. Compared with other electrolyte optimizations, the battery assembled based on Example 3 exhibits excellent plating / stripping performance (shown in Table 1).

[0036] Table 1 Comparison of cycle performance between the examples of the present invention and recent related studies on Zn / / Zn symmetric batteries:

[0037] In summary, the present invention provides a method for in-situ constructing a ZnS-based solid electrolyte interface layer without sulfur additives. By adding a small amount of sulfur-free N-acetylglucosamine organic additive to a conventional ZnSO4 electrolyte for modification, a ZnS-based composite SEI layer is in-situ formed on the surface of the zinc electrode during the charge-discharge cycle, significantly improving the cycle performance and cycle stability of the aqueous zinc-ion battery.

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[10] Xu J.; Lv W L.; Yang W.; Jin Y.; Jin Q Z.; Sun B.; Zhang Z L.;Wang T Y.; Zheng L F.; Shi X L.; Sun B.; Wang G X. In situ construction ofprotective films on Zn metal anodes via natural protein additives enablinghigh-performance zinc ion batteries. ACS Nano 2022, 16, 11392-11404.

[11] Zhang W.; Dai Y H.; Chen R W.; Xu Z M.; Li J W.; Zong W.; Li HX.; Li Z.; Zhang Z Y.; Zhu J X.; Guo F.; Gao X.; Du Z J.; Chen J T.; Wang TL.; He G J.; Parkin I P. Highly reversible zinc metal anode in a diluteaqueous electrolyte enabled by a pH buffer additive. Angewandte ChemieInternational Edition 2023, 62, e202212695. Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements for some of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the present invention in each embodiment.

Claims

1. A method for in-situ construction of a ZnS-based solid electrolyte interface layer without sulfur additives, characterized in that: The method comprises the following steps: (1) preparing a mixed solution: uniformly dispersing ZnSO4 with a molar concentration of 1-2 mol / L and N-acetylglucosamine with a molar concentration of 0.1-0.8 mol / L in deionized water to obtain a uniform mixed solution; (2) Assembling a battery: Using the mixed solution as the electrolyte, it is applied to a button cell; (3) In situ construction of ZnS-based composite SEI layer: During the charge and discharge process, due to the reaction between ZnSO4 and N-acetylglucosamine, a ZnS-based composite SEI layer is formed in situ on the surface of the zinc electrode.

2. The method according to claim 1, characterized in that The ZnSO4 is ZnSO4·1H2O or ZnSO4·7H2O.

3. The method according to claim 1 or 2, characterized in that: In the mixed solution, ZnSO4 solution is the main component of the electrolyte, and N-acetylglucosamine is used as an additive.

4. The method according to claim 1, characterized in that: The button cell is a Zn / / Zn symmetrical cell, a Zn / / Cu half cell, and a Zn / / Na5V 12 O 32 Any of the full batteries.

5. The method according to claim 1, characterized in that The organic matter of the ZnS-based composite SEI layer is zinc chelate, and the inorganic matter is ZnS and ZnCO3.

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