A novel de-coupling solid polymer electrolyte via semi-interpenetrating network for lithium metal battery

Abstract

Compared with linear homopolymer and block copolymer electrolytes, network-based solid polymer electrolytes (SPEs) demonstrated much improved lithium dendrite resistance and cell cyclability in lithium metal batteries (LMBs), suggesting that polymer chain architecture plays a pivotal role in SPE design. To further improve the state-of-the-art performance of SPEs, in this work, we report a novel interpenetrating network (IPN) SPE that is comprised of poly (ethylene oxide) and poly (propylene carbonate) (PPC) chains. The synthesis of the SPE is based on the crosslinking of octakis(3-glycidyloxypropyldimethylsiloxy)octasilsesquioxane and amine-terminated polyethylene glycol while incorporating linear PPC with a controlled concentration. The IPN SPEs showed improved ionic conductivity and a nearly threefold increase of lithium ion transference number. The optimized SPE could be stably cycled for over 300 ​h ​at a harsh current density of 1.5 ​mA ​cm−2 in the galvanostatic symmetrical cell plating/stripping experiment. Scanning electron microscopy (SEM) revealed that incorporation of PPC could effectively reduce the uneven lithium deposition while X-ray photoelectron spectroscopy (XPS) was used to confirm the active components that are associated with the stable solid electrolyte interface. Full LMBs fabricated using the IPN SPE, a lithium metal anode and a LiFePO4 cathode delivered high specific capacity of over 160 ​mAh g−1 at 0.1 C and over 95 ​mAh g−1 at 2 ​C with an excellent Coulombic efficiency and lifetime. This work demonstrated a new pathway of SPE molecular design towards high performance SPEs for LMB applications.