Poly(carbonate)-based ionic plastic crystal fast ion-conductor for solid-state rechargeable lithium batteries

Liquid plasticizers with a relatively higher dielectric coefficient like ethylene carbonate (EC), propylene carbonate (PC), and ethyl methyl carbonate (EMC) are the most commonly used electrolyte materials in commercial rechargeable lithium batteries (LIBs) due to their outstanding dissociation ability to lithium salts. However, volatility and fluidity result in their inevitable demerits like leakage and potential safety problem of the final LIBs. Here we for the first time device a subtle method to prepare a novel thermal-stable and non-fluid poly(carbonate) solid-state electrolyte to merge EC with lithium carriers. To this aim, a series of carbonate substituted imidazole ionic plastic crystals (G-NTOC) with different polymerization degrees have been synthesized. The resulting G-NTOC shows an excellent solid-state temperature window (R.T.-115 °C). More importantly, the maximum ionic conductivity and lithium transference number of the prepared G-NTOC reach 0.36 × 10−3 S cm−1 and 0.523 at 30 °C, respectively. Galvanostatic cycling test results reveal that the developed G-NTOC solid-state electrolytes are favorable to restraining the growth of lithium dendrite due to the excellent compatibility between the electrode and the produced plastic crystal electrolyte. The fabricated Li|G-NTOC|LiFePO4 all-solid-state cell initially delivers a maximum discharge capacity of 152.1 mAh g−1 at the discharge rate of 0.1C. After charging-discharging the cell for 60 times, Coulombic efficiency of the solid-state cell still exceeds 97%. Notably, the Li|G-NTOC|LiFePO4 cell can stably light a commercial LED with a rated power of 0.06 W for more than 1 h at 30 °C, and the output power nearly maintains unchanged with the charging-discharging cycling test, implying a sizeable potential application in the next generation of solid-state LIBs.