Solid-Liquid Interface Optimization For High-Performance Anode In Aqueous Zinc-Ion Batteries

The development of battery energy storage system is one of the hot topics in the power storage field.In the past two decades,the development and application of lead-acid batteries and lithium-ion batteries have changed people’s life style forever and greatly facilitated people’s life.However,these two kinds of batteries have their own shortcomings.For example,lead-acid batteries possess toxic and harmful properties which limit its further development.And lithium-ion batteries have long been trapped in the safety problems caused by organic electrolyte.Thus,the development of aqueous metal ion batteries ushered in an opportunity.Among all the metal ion batteries,aqueous rechargeable zinc ion batteries（ARZIBs）have been favored by researchers because of its characteristics of safety,stability,high theoretical capacity,and simple preparation conditions.In the last five years,the cathode materials of ARZIBs have become a research hotspot.Through the unremitting efforts of researchers,manganese oxides,vanadium oxides and prussian blue analogs are considered feasible and gradually industrialized.However,in the process of improving the cathode material to enhance the capacity,the potential dangers are ignored.Like lithium metal,zinc metal also possesses a problem of dendrite growth during charge/discharge process.The dendrite growth is caused by three reasons:1)the uneven surface electric field distribution;2)the hydrogen evolution and corrosion side reaction competing with the zinc deposition reaction;3)the rough surface of the zinc sheet.Dendrite growth can not only exacerbate side reactions,but also pierce the separator,resulting in short circuit inside the battery.In our study,the physical and chemical problems existing in the charging and discharging process of anode are discussed in ARZIBs,aiming at improving the stability and ion migration speed of anode.Here,the strategy of solid-liquid interface optimization is used for high-performance anode.Moreover,the stability and practicability of the system are also discussed.Firstly,Zn-ZSM-5 prepared by ion exchange method was studied and mixed with acetylene black to construct 3D anode（Zn@Zn-ZSM-5）.On the one hand,the introduction of zinc ions can not only provide more active sites for zinc ion deposition,but also increase the migration rate of zinc ions on the anode by using the interatomic repulsion.On the other hand,the introduction of acetylene black can provide a conductive network for Zn-ZSM-5 layer to meet the requirements of electron transmission.Physical characterization and electrochemical results show that the Zn@Zn-ZSM-5 anode can not only provide enlarged electroactive area to serve the fast kinetics of Zn²⁺,but also withstand the inside strain and stress to suppress the growth of dendrite during zinc plating and stripping process.Secondly,the corrosion reaction mechanism of zinc anode in Zn（CF₃SO₃）₂electrolyte and the contribution mechanism of methanol additive in long cycle stability of battery were studied.Methanol can mix with water in any ratio through the formation of hydrogen bonds,which participates in the solvation shell of Zn²⁺ion in a manner of forming the[Zn（OH₂）_x（CH₃OH）_y]²⁺cations.The interaction between zinc ion,methanol and water can effectively inhibit the side reaction caused by the decomposition of active water on the surface of anode.Thirdly,inspired by the successful strategy of electrolyte optimization,the application of ethanol,ethylene glycol and dimethyl sulfoxide is studied as additive in ARZIBs.Although the three additives can mix with Zn（CF₃SO₃）₂ solution,the result about the long-term stability indicates that ethanol is more suitable for the electrolyte of zinc ion battery with near neutral aqueous electrolyte.Ethanol can participate in the initial solvent shell of zinc ion,forming[Zn（OH₂）_x（CH₃CH₂OH）_y]²⁺complex cation,The complex cation can not only reduce the water content on the surface of anode,but also greatly improve the life span of anode in ARZIBs.In conclusion,solid-liquid interface optimization is a feasible strategy for the improvement of ARZIBs,which aims to improve the performance of the anode and provide a variety of ways for the commercialization of ARZIBs.