Study On Performance And Reaction Mechanism Of Lithium-air Batteries With Gold Nanocolloid Electrolyte Solutions

With the continuous development of society,the energy crisis and environmental crisis are becoming more and more serious.The research and development of the power system with friendly environment and high energy density is imperative.The lithium-air battery,as the next generation of high-energy density power cells（the theory is 11 kWh/kg）,has attracted wide attention.passivation is one of the reasons for the failure of Li-air battery,which iscaused by blocking mass transfer channel and covering cathode by Li₂O₂,uncomplete decomposition of Li₂O₂ and accumulation of by-products.Forming small-sized and/or film-like amorphous Li₂O₂,enhancing the kinetics and charge transformation of Li₂O₂ can retard the cathode passivation,improving the performanceof Li-air battery.In this project,nano Au colloidal electrolyte was constructed to induce surface ORR reaction,combined with high ORR catalytic activity and high electron conductivity to ease positive electrode passivation.By characterizing the morphology of the discharge products,testing the impedance of the system,observing the accumulation of products and by-products during the battery cycle,th nano Au colloidal electrolytes were used to control the morphology and the decomposition of Li₂O₂.Synergy,the specific study is as follows:（1）Preparation of Au nanoparticles with trimethylol phosphine oxide ligand（THP-Au,2 nm）and Au nanoparticles with thiosuccinate ligand（MSA-Au,3 nm）.The two Au nanoparticles were dispersed in 1M LiClO₄+DMSO organic solution to prepare a colloidal electrolyte,and the dispersibility of the particles in the solution was compared.It was found that the stability of the MSA-Au colloidal electrolyte is much better than that of the THP-Au colloidal electrolyte.（2）The THP-Au and MSA-Au colloidal electrolytes were used to assemble the batteries and the cycle performance was tested.The results showed that the THP-Au colloidal electrolyte exhibited a lower charge-discharge voltage range,but its cycle performance was poor;and the addition of MSA-Au nanoparticles could effectively improve the cycling performance of the battery at a concentration of 0.5 mg/mL.The best performance of the MSA-Au colloidal electrolyte is 160 cycles higher than the normal system.The mechanism of MSA-Au colloidal electrolyte on the battery was analyzed.It was found that the nano-Au colloidal electrolyte can change the morphology of the discharge product,increase the total discharge capacity of the battery,reduce the internal impedance of the battery,and can buffer the lithium anode corrosion.（3）One-pot synthesis of amphiphilic Janus Au nanoparticle,addition of Janus Au to 1M LiClO₄+DMSO solution as electrolyte solution,complete impregnation with separator,anodic addition of separator,positive electrode of separator Three types of electrolytes were used to assemble batteries.As a result,it was found that the presence of Janus Au can effectively improve the cycling performance of the battery.When the concentration of Janus Au is 0.2 mg/mL,the membrane is completely impregnated,and the battery can be cycled more than 300 times.The Janus Au Sol system electrolyte battery was studied using PU-Glass separator,but the homemade PU-Glass separator failed to improve the cycling stability of the Janus Au system lithium-air battery.The reason may be that the presence of PU increased the battery’s Impedance increases the over-voltage of the battery’s charge and discharge,resulting in reduced cycle performance.