Ceramic-in-polymer solid electrolyte reinforced by in-situ polymerization of PEGDA interlayer for lithium metal battery

Abstract

The solid electrolyte -is regarded as the proprietary electrolyte to solve the safety problem of high-energy-density lithium metal batteries (LMBs). Combined with the both advantages of inorganic ceramic and polymer electrolytes, the ceramic-in-polymer solid electrolyte of 15 wt% Li0.33La0.557TiO3-in-poly(vinylidene fluoride-co-hexafiuoropropylene) (LLTO-in-P(VdF-HFP)) is proposed. Since the severe lithiation reaction between LLTO ceramic and lithium metal anode, in situ polymerization of degradable poly(ethylene glycol) diacrylate (PEGDA) as protective layer on the surface lithium metal is constructed, which not only effectively avoids the side reaction, but also suppresses the growth of lithium dendrites. Under the premise of ensuring the safety of solid state LMBs, trace liquid electrolyte is added into the electrolyte/electrode interface to reduce solid-solid interfacial resistance. The unique design of solid electrolyte combined with protective lithium anode is beneficial to the stable cycling of Li||Li symmetric cells for more than 700 h under current density of 0.2 mA cm−2, compared with only 200 h cycling life for the same electrolyte using the bare lithium anode. The assembled Li||LiNi0.6Co0.2Mn0.2O2 full-cell exhibits a specific discharge capacity of 176 mAh g−1 at 0.2C rate between 3.0 and 4.35 V, maintaining 90.6% of initial capacity after 200 cycles. Therefore, the developed solid electrolyte with unique protected lithium anode exhibits potential application in high-energy-density solid LMBs.