The Research On Lithium Anode Protection In High Performance Lithium Carbon Dioxide Battery

With the rapid development of economy and society,the global fossil energy reserves are increasingly decreasing,and the use of traditional fossil energy will produce a large amount of polluting gas,which seriously hinders the rapid development of society.Renewable new energy（wind energy,water energy,geothermal energy,etc.）has developed rapidly in response to the situation.However,these energy sources cannot be widely used due to geographical and weather restrictions.Therefore,efficient energy storage and conversion systems have gradually attracted extensive research.Among many energy storage systems,lithium carbon dioxide（Li-CO₂）batteries have attracted wide attention because they can not only absorb and utilize CO₂,but also provide a super high energy density(1876 Wh kg^-1)which is more than 5 times higher than current lithium ion batteries.Nevertheless,Li-CO₂batteries still have many problems,such as large overpotential,poor cycle life,and low rate performance.In recent years,many effective catalysts have been developed to improve the performance of Li-CO₂batteries.While the problems caused by Li anode,such as Li dendrite,pulverization and passivation,still hinder the further development of Li-CO₂batteries.Therefore,the design of a uniform and dense Li anode protective layer is very important for the commercial production of Li metal batteries.Therefore,this paper mainly from the application of Li anode protection in high energy density Li-CO₂battery,the main research results are as follows:（1）The concentration of Li⁺flux at the electrode-electrolyte interface leads to uneven nucleation on the Li metal surface,promoting the formation of Li dendrites and liquid electrolytes are prone to leakage and side reactions with Li metal,which seriously impede the commercial production of Li metal batteries.In this study,a lithium ethylenediamine（LE）layer was constructed on the Li anode and further cross-linked with tetraethylene glycol dimethyl ether in the electrolyte to obtain tetraethylene glycol dimethyl ether based polymer electrolyte（TPE）.Uniform LE layer combined with in-situ TPE can not only inhibit dendrite formation,reduce Li-induced side reactions and the corresponding passivation/pulverization,but also reduce the interfacial impedance,so that the battery can work normally under bending conditions.Therefore,LE-Li anode exhibits more stable electrochemical properties than pure Li anode in symmetric batteries.In addition,the Li-CO₂battery using LE-Li/TPE has a high discharge capacity of 22873 m Ah g^-1and good full discharge/charge performance.When running at cut-off capacity,the battery can run 105 times stably,and the overpotential is less than 1.9V,which is better than pure Li/electrolyte based Li-CO₂battery.The flexible Li-CO₂battery based on LE-Li/TPE also shows excellent performance at different bending angles.（2）The non-uniform deposition of Li⁺will lead to the growth of Li dendrites and the volume expansion of Li anode during the cycle,which will seriously affect the battery performance and even cause safety problems.Therefore,an artificial mixed layer of Li₃BO₂based polymer and Zn Li alloy has been prepared by a simple chemical modification strategy.Therefore,the ZB-Li anode has high lithium ion conductivity and can regulate the uniform deposition of Li ions,so that the plating/stripping of Li is uniform,stable and fast.In symmetrical batteries with current densities of 0.1 and 1m A cm^-2,the prepared Li anode shows cyclic stability values of over 2000 and 800hours with low voltage lag,respectively.In addition,we also test the ZB-Li anode and pure Li anode in Li-CO₂battery,ZB-Li anode based battery can stable cycle 100cycles,far better than pure Li anode based battery,but also has excellent reversibility.In the LFP battery,the ZB-Li anode can cycle about 170 cycles at 1C,and the specific capacity can still reach 150 m Ah g^-1.Moreover,the ZB-Li anode has better rate performance.