Supramolecular Biopolymer/Prussian Blue Hydrogels as Injectable Semisolid Electrodes for Shape-Conformable Electrochemical Energy Storage Devices

Abstract

Abstract The transition toward electrified transport, renewable energy integration, and wearable electronics demands sustainable, deformable energy storage systems capable of conforming to complex geometries while maintaining mechanical and electrochemical functionality at ambient conditions. Herein, we report injectable, self-healing, biobased electrolyte–electrode gels that combine mechanical adaptability with tunable electrochemical functionality in a single semisolid platform. Supramolecular hydrogels are based on ionic biopolymers—alginate and chitosan— that integrate carbon black (CB) as a percolating electronic network, potassium chloride as a salt electrolyte, and Prussian blue (PB) as a redox-active component, enabling ambient-temperature processing into shape-conformable energy storage architectures. The dynamic polymer network fully recovers after extreme deformation (up to 1000% strain), as verified by rheological characterization. Beyond structural resilience, the electrochemical response can be programmed through composition: increasing PB loading drives a transition from predominantly capacitive response at <1 mg/mL of PB to battery-type behavior (>10 mg/mL PB), enabling control over energy storage mechanisms within the same materials framework. By uniting injectability, self-healing, bio-derived chemistry, and tunable charge storage characteristics, this work establishes a versatile route toward sustainable, deformable energy storage systems for next-generation soft and conformable electronics.