Mechanochemistry induced mixed ionic/electronic conductive interphase enabling dendrite-free lithium metal anodes

High-energy-density lithium metal batteries have shown promising applications in drones and electrical vehicles. However, the growth of lithium dendrites and the formation of unstable solid electrolyte interphase (SEI) become the main factors restricting their development. In this study, dendrite-free lithium metal anodes (ZB@Li) were developed with ionic/electronic conductive interface layers by a solvent-free mechanochemical method. By rubbing zinc borate (ZB) powder on lithium foil, a mixed interface layer is formed with the generation of lithium borate phase and the Li–Zn alloy phase. The lithium borate phase provides a low diffusion energy barrier and high ionic conductivity for sufficient potential gradient to induce rapid deposition of ions on the interface layer. The Li–Zn alloy phase owns the lithiophilic characteristic and a high electronic conductivity. The combination of the two phases provides mixed ions/electrons paths with enhanced transport kinetics and realize uniform and planar deposition of lithium. As a result, the ZB@Li symmetrical cell exhibits a prolonged cycling performance of over 4,200 h and the ZB@Li||LFP (LFP= lithium iron phosphate [LiFePO]) full cell shows a long cycle life for more than 500 cycles at 2 C with a high capacity retention rate of 84.6% at a high loading mass of 10 mg/cm.