Study On Surface Modification Of Lithium Metal Anode

Lithium metal is a very promising anode material and has received extensive attention for researchers.The interest in Li metal stems from its lowest redox potential and ultra-high theoretical capacity.However,lithium metal electrodes suffer from dendrite growth,severe side reactions,easy formation of dead lithium,and volume expansion during charging and discharging,which hinders the practical application of lithium metal electrodes in batteries.This paper focuses on the electrode-electrolyte interface,adopting artificial coating and electrolyte additives to control the structure and composition of SEI film.And the influence on the electrochemical performance of lithium metal anode was investigated.Lithium metal electrode modified by artificial coating was prepared by drop coating method.The coating used Li F as the main material and paraffin wax（PW）as the binder.At a current density of 1 m A/cm²,the symmetric battery assembled with PW-Li F-coated modified lithium metal electrode could stably cycle for 330 h,and the nucleation overpotential could be maintained below 20 m V.The coating preparation method was further optimized,and the modified lithium metal electrode was prepared by spraying.At a current density of 1 m A/cm²,the cycle life of the symmetrical battery was increased to 450 h,improving 36.4%.N,N dimethylacetamide（DMA）has a strong interaction with Li⁺,which could promote the dissolution of Li NO₃ in carbonate electrolytes Therefore lithium nitrate could be well dissolved in the carbonate electrolyte.Under the optimized conditions,when the doping content of Li NO₃/DMA solution（10 wt.%Li NO₃）in the modified electrolyte was 20wt.%,the symmetrical battery could stably cycle for 290 h at a current density of 1 m A/cm².The discharge specific capacity of Li Fe PO₄-Li full battery in the modified electrolyte system was 91.68 m Ah/g at a high rate of 5 C,which was 2.6 times that of the full battery in the unmodified electrolyte system（35.2 mAh/g）.