A concentrated poly(ethylene carbonate)/poly(trimethylene carbonate) blend electrolyte for all-solid-state Li battery

Abstract

Electrochemical and ion-transport properties of polymer blend electrolytes comprising poly(ethylene carbonate) (PEC), poly(trimethylene carbonate) (PTMC) and lithium bis(fluorosulfonyl) imide (LiFSI) were studied in this work, and the electrolyte with the best blend composition was applied in all-solid-state Li batteries. The ionic conductivity of both PEC and PTMC single-polymer electrolytes increased with increasing Li salt concentration. All PEC and PTMC blend electrolytes show ionic conductivities on the order of 10−5 S cm−1 at 50 °C, and the ionic conductivities increase slightly with increasing PEC contents. The PEC6PTMC4-LiFSI 150 mol% electrolyte demonstrated better Li/electrolyte electrochemical and interfacial stability than that of PEC and PTMC single-polymer electrolytes and maintained a polarization as low as 5 mV for up to 200 h during Li metal plating and stripping. A Li|SPE|LFP cell with the PEC6PTMC4-LiFSI 150 mol% electrolyte exhibited reversible charge/discharge capacities close to 150 mAh g−1 at 50 °C and a C/10 rate, which is 88% of the theoretical value (170 mAh g−1). Concentrated poly(ethylene carbonate) (PEC) and poly(trimethylene carbonate) (PTMC) blend electrolytes with 150 mol% of LiFSI were prepared and the PEC6PTMC4 electrolyte was applied in all-solid-state Li batteries. The blend electrolyte has an ionic conductivity of 10−5 S cm−1 and a Li+ transference number (t+) of 0.73. Meanwhile, the PEC6PTMC4 electrolyte exhibits a good electrochemical stability with Li electrode than those of PEC and PTMC single-polymer electrolytes. An LFP half-cell exhibits a discharge capacity of 150 mAh g−1 at 50 °C and a C/10 rate.