Agarose Based Solid Electrolyte for All-Solid-State Lithium Ion Batteries Working from −20 °C to 80 °C

Agarose based solid electrolyte host is synthesized by crosslinking agarose with 3-glycidoxypropyltrimethoxysilane. This host exhibits an impressive dissolubility for lithium salt. Below 25 °C, the ionic conductivities are 2∼3 orders of magnitude higher than that of PEO based solid electrolytes. And, high lithium ion transference number of 0.78 at −20 °C and decomposition potential of 4.63 V at 80 °C are obtained. At 25 °C, LiFePO4 all-solid-state lithium-ion batteries (ASSLIB) assembled with the electrolyte display an average discharge capacity of 156.2 ± 4.0 mAh g−1 for 150 cycles at 0.1 C. At 80 °C, it delivers 111.6 ± 19.0 mAh g−1 for 500 cycles at 5 C. The batteries are also capable of operating at 0 °C and 0.1 C with 94.9 ± 6.9 mAh g−1 for 150 cycles, and at −20 °C and 0.025 C with 36.2 ± 3.7 mAh g−1 for 100 cycles, revealing a momentous widening for the working temperature of ASSLIB.