Organic Ionic Plastic Crystal‐Based Composite Electrolyte with Surface Enhanced Ion Transport and Its Use in All‐Solid‐State Lithium Batteries

Solid‐state electrolytes have been identified as one of the most attractive materials for the fabrication of reliable and safe lithium batteries. This work demonstrates a facile strategy to prepare highly conductive organic ionic plastic crystal (OIPC) composites by combination of a low weight fraction of Li + doped OIPC ( N ‐ethyl‐ N ‐methylpyrrolidinium bis(fluorosulfonyl)amide, [C 2 mpyr][FSI]) with commercial poly(vinylidene difluoride) (PVDF) powder. Benefiting from the enhancement of lithium ion dynamics, as evidenced by the solid‐state NMR measurements, the composite electrolyte shows an order of magnitude higher conductivity than that of the bulk material. Lithium metal/LiFePO 4 cells incorporating the prepared composite electrolytes show impressively high specific capacity and good cycling stability (99.8% coulombic efficiency after 1200 cycles at 2 C, room temperature), which is the first demonstration of long‐term cycling performance at such high rate for an OIPC‐based electrolyte. The high voltage cathode, LiCo 1/3 Ni 1/3 Mn 1/3 O 2 was tested and good rate performance and stable capacities have been achieved.