Composition regulation of polyacrylonitrile-based polymer electrolytes enabling dual-interfacially stable solid-state lithium batteries

Abstract

The polyacrylonitrile (PAN) is an attractive matrix of polymer electrolytes owing to its wide electrochemical window and strong coordination with Li salts. However, the PAN-based electrolytes undergo severe interfacial problems from both cathode and anode sides, including uneven ionic transfer induced by high rigidity of dry PAN-based polymer, as well as inferior stability against Li-metal anode. Herein, the composition regulation of PAN-based electrolytes is proposed by introducing succinonitrile (SN) plastic crystal and LiNO3 salt for the construction of interfacially stable solid-state lithium batteries. The plastic nature of SN enables the rapid ionic transfer in electrolytes, along with the establishment of conformally interfacial contacts. Meanwhile, a stable solid-electrolyte-interface (SEI) layer consisting of Li3N and LiNO2 is in-situ formed at Li/electrolyte interface, contributing to the inhibition of uncontrol reactions between PAN and Li-metal. Consequently, the resultant Li symmetric cell delivers an extended critical current density of 1.7 mA cm−2 and an outstanding cycling lifespan of 700 h at 0.1 mA cm−2. Moreover, the corresponding solid-state LiNi0.6Co0.2Mn0.2O2/Li full cell shows an initial discharge capacity of 161 mAh/g followed by an outstanding capacity retention of 88.7 % after 100 cycles at 0.1C. This work paves the way for application of PAN-based electrolytes in the field of solid-state batteries by facile composition regulation.