2-Methylimidazole assisted synthesis of nanocrystalline shell reinforced PPy hydrogel with high mechanical and electrochemical performance

Electroactive and conductive hydrogels with porous network structure, super hydrophilicity, mechanical flexibility and biocompatibility are prominent electrode materials for flexible/wearable supercapacitors. In this work, novel PPy hydrogels (m-PPy) with crystalline core–shell structure have been facilely fabricated with assistance of 2-methylimidazole via one-step oxidative polymerization. The m-PPy hydrogels exhibit significantly improved recoverable compressive strength of up to 26.7 kPa at 50% strain and remarkable maximum compressive strength of up to 265 kPa, due to effective energy dissipation by nanocrystalline shells. The m-PPy3:3 exhibits high specific capacitance of 536 F g−1 and corresponding symmetric supercapacitor possesses superior areal specific capacitance of 603 mF cm−2, good rate capability and superb areal energy density of 53.6 μWh cm−2. Particularly, m-PPy3:3 based flexible supercapacitor presents remarkable flexibility and mechanical stability, which can sustain 10,000 bending cycles without severe degradation of electrochemical performance.