Preparation And Electrochemical Properties Of Lithium Alloy Anode Materials

As a key component of next-generation high-energy batteries,lithium metal anodes have attracted extensive attention from the research community due to their high specific capacity and low redox potential.However,lithium metal batteries usually suffer from uneven lithium deposition,lithium dendrite growth,and poor transport kinetics,which limit the commercial application of metallic lithium anodes.Therefore,it is of great significance for the practical application of lithium metal batteries to carry out research on the modification of lithium metal anodes and improve the cycle stability of lithium anodes.At present,the modification methods of metal lithium anode mainly include:electrolyte modification,design of new anode structure,and use of solid electrolyte.In this thesis,we designed and prepared a lithium alloy anode,and applied it in different liquid and solid systems for electrochemical testing and research.The main contents are as follows:On the one hand,lithium-friendly metals zinc,tin and Lithium is melted,and a lithium-zinc-tin alloy electrode is prepared and characterized and electrochemically tested.In situ optical microscopy results show that the lithium alloy anode can achieve a very uniform lithium metal deposition/stripping behavior,which can effectively inhibit the growth of dendrites.Electrochemical tests show that in a symmetric battery with ether-based electrolyte,the lithium alloy has a cycle life of more than 650 h at 1 m A cm^-2and 1 m Ah cm^-2,which is better than that of metal lithium anode.At other current densities and areal capacities,the lithium alloy anode also outperforms the cycle stability of the metal lithium anode.At the same time,the lithium alloy electrode is used in the lithium-sulfur battery system,and the initial discharge specific capacity of sulfur reaches1195 m Ah g^-1,which is better than that of pure metal lithium anode,and has better electrochemical performance.On the other hand,when lithium alloy electrodes are applied to PEO polymer so lid-state lithium batteries,the cycle stability of lithium alloy symmetric batteries is higher than metal lithium symmetry at 0.1 m A cm^-2,0.1 m Ah cm^-2,especially lithium-tin alloys,exhibiting a long cycle exceeding 400 h for lithium metal.The performance test of the full battery matched with the LFP positive electrode shows that the lithium alloy has better electrochemical performance than pure lithium metal,and can play a role in optimizing the lithium metal negative electrode to a certain extent.In the PEO gel polymer electrolyte with LLZTO added,the lithium alloy electrode also exhibited excellent cycle stability.Through the study of alloy lithium anodes,it is found that for metal lithium battery systems,the formation and accumulation of inactive lithium and the growth of lithium dendrites are the main reasons for the limited life of high specific energy density lithium metal batteries.Therefore,understanding and addressing the fundamental issues underlying the failure of Li anodes in Li metal batteries will help realize their commercialization.