Polyacrylate-graft-polypyrrole Copolymer as Intrinsically Elastic Electrodes for Stretchable Supercapacitors

Constructing elastic electrodes with high mechanical and electrochemical stability remains a challenge in developing flexible supercapacitors. Instability of elastic composite electrodes stems from detachment of noncovalently associated electroactive components from elastic substrates under cyclic deformations. Herein, a novel all-organic copolymer consisting of polypyrrole grafted from a polyacrylate elastomer is proposed as elastic electrodes for stretchable supercapacitors. The single copolymer is obtained by graft polymerization in the swollen state, characterized by a wrinkled polypyrrole coating covalently attached on an elastic core. The copolymer is intrinsically elastic and maintains structural integrity under bending, twisting, and stretching deformations to ensure stable electrochemical performance. In addition, the grafted polypyrrole aggregates densely under the constraint of the backbone and gives a competitive conductivity of 41.6 S cm^-1. A stretchable supercapacitor is constructed using the copolymer as electrodes and an acid hydrogel as an electrolyte, resulting in a specific capacitance of 430 mF cm^-2. The supercapacitor delivers a capacitance retention of 100% after 1000 stretching-releasing cycles, exhibiting mechanical and electrochemical reliability under elastic deformations.