An ion-conductive Li7La3Zr2O12-based composite membrane for dendrite-free lithium metal batteries

Lithium (Li) metal is pursued as the anode for next generation lithium batteries because of the highest energy density and the lowest reduction potential. However, the formation of lithium dendrite caused by nonuniform Li deposition exists. Moreover, the safety issue arising from hazardous Li dendrites hinders the practical application of lithium metal batteries (LMBs). In this work, an organic and inorganic composite protective membrane (CPM) consisting of PVDF-HFP and LLZO particles is prepared by a simple tape-casting method. The CPM modified Li symmetric cell exhibits no obvious voltage hysteresis over 500 h at 2 mA cm−2 and 1 mAh cm−2. Moreover, the CPM modified Li | LFP cell can stably run 800 cycles at 1C and retain a high average Coulombic efficiency of ~99.95%. Moreover, the in-situ formation of LiF between metallic Li anode and the C–F group in PVDF-HFP exhibits high modulus, effectively suppressing the growth of lithium dendrites. The uniform Li deposition is achieved owing to the high ionic conductivity and Li+ transference number of CPM. In addition, the high modulus LiF layer can stabilize interface and greatly reduce interfacial resistance after cycling.