Crosslinked poly(ethylene oxide)-based membrane electrolyte consisting of polyhedral oligomeric silsesquioxane nanocages for all-solid-state lithium ion batteries

Development of suitable solid membrane electrolyte for all-solid-state lithium ion battery is of great importance to address the safety issue arisen from the current lithium ion battery technology. Herein, we report the synthesis and properties of a poly(ethylene oxide)-based, crosslinked solid membrane electrolyte with nanocages of polyhedral oligomeric silsesquioxane through UV-induced crosslinking technique. Benefiting from the crosslinked structure, the synthesized membrane electrolyte exhibits an improved mechanical strength and electrochemical stability compared to the sample without crosslinked structure. The optimized membrane electrolyte has the ionic conductivity of 3.83 x 10(-4) Scm(-1) at 60 degrees C with an electrochemical window of 5.3 V. The thus-assembled battery using lithium plate as anode and lithium iron phosphate as cathode delivers an initial discharge capacity of 150 mAh(-1) at 60 degrees C, higher than that of battery assembled from membrane electrolyte without crosslinked structure. Although the battery is more stable than that assembled from membrane electrolyte without crosslinked structure, the initial discharge capacity decreases to 139 mAhg(-1) after 42 charging-discharging cycles. Nevertheless, the results presented here demonstrate that the UV-induced crosslinking strategy can be an effective approach for the practical synthesis of solid-state membrane electrolyte.