Composite polymer electrolyte reinforced by graphitic carbon nitride nanosheets for room-temperature all-solid-state lithium batteries

Abstract

By virtue of the flexibility and safety, polyethylene oxide (PEO) based electrolytes are regarded as an appealing candidate for all-solid-state lithium batteries. However, their application is limited by the poor ionic conductivity at room temperature, narrow electrochemical stability window and uncontrolled growth of lithium dendrite. To alleviate these problems, we introduce the ultrathin graphitic carbon nitride nanosheets (GCN) as advanced nanofillers into PEO based electrolytes (GCN-CPE). Benefiting from the high surface area and abundant surface N-active sites of GCN, the GCN-CPE displays decreased crystallinity and enhanced ionic conductivity. Meanwhile, Fourier transform infrared (FTIR) and chronoamperometry studies indicate that GCN can facilitate Li + migration in the composite electrolyte. Additionally, the GCN-CPE displays an extended electrochemical window compared with PEO based electrolytes. As a result, Li symmetric battery assembled with GCN-CPE shows a stable Li plating/stripping cycling performance, and the all-solid-state Li/LiNi 0.6 Co 0.2 Mn 0.2 O 2 (NCM622) batteries using GCN-CPE exhibit satisfactory cyclability and rate capability in a voltage range of 3−4.2 V at 30 °C.