Contrastive Studies on Thermal Initiators for In Situ Polymerization of Gel Polymer Electrolyte in Supercapacitor

Gel polymer electrolyte (GPE) has great prospect in developing advanced supercapacitor (SC) with high energy density and high safety. This work investigated two common thermal initiators, azobisisobutyronitrile (AIBN) and benzoyl peroxide (BPO) employed for in situ polymerization of the GPE containing organic electrolyte, focusing on their thermal decomposition behaviors, thermal initiation efficiencies, and effects on physicochemical properties of the GPE and electrochemical performances of the SC. The results demonstrate that the two initiators undergo thermal decomposition featured as bond cleavage to release free radials at moderate temperature. In contrast to BPO, AIBN contributes to more adequate polymerization with higher initiation efficiency, which benefits the redox stability of the generated GPE and thereby long-term cycling performance of the SC at high voltage. Meanwhile, AIBN-initiated GPE exhibits better ionic transport kinetics, enabling the SC to achieve excellent rate capability with restricted polarization.