Suppressing Dendrites via Interfacial Ionic Conductivity Regulation in Lithium Metal Batteries

Abstract

Uncontrolled Li dendrite growth is a severe trial for the practical application of lithium metal batteries. Lithium metal surface membrane engineering has been proven to be a promising dendrite inhibition strategy. However, the research on the influence of the conductivity of protective membranes on the surface potential distribution of the lithium metal electrode is relatively scarce. The regulation of the potential distribution on the electrode surface is very important for dendrite inhibition. From the view of both cost effectiveness and protective effect, we prepared the ceramic–polymer composite protective membrane [Li7La3Zr1.7Ti0.3O12/poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF–HFP) (LLZTO/PH)] and focused on the influence of the membrane conductivity on the electrode interface potential distribution and the effect of dendrite inhibition. The optimal addition of 5 wt % LLZTO establishes a continuous low potential gradient with a uniform charge distribution from the electrolyte to the Li metal surface based on the simulations, thus suppressing the growth of the lithium dendrite. Impressively, excellent electrochemical performance with the stable cycling over 2000 h at 0.5 mA cm–2 and 900 h at 2 mA cm–2 (Li/Li symmetric cell) and high coulombic efficiency of 99% for about 470 cycles (Li/Cu cell) can be achieved by the protection of the LLZTO/PH composite membrane. This work demonstrates a potential strategy to establish a high-performance Li metal protective membrane and enhance the interfacial ionic conductivity to acquire a dendrite-free anode.