LiTFSI‐Regulated Free‐Standing Conductive Polymer Hydrogels for Flexible Supercapacitors

Abstract

The advancement of flexible and wearable electronics necessitates energy‐storage materials that reconcile high electrochemical performance with robust mechanical deformability and environmental adaptability. Here, we design a free‐standing conductive hydrogel electrode by integrating poly(3,4‐ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) into a polyacrylamide/poly(vinyl alcohol) (PAAm/PVA) double‐network scaffold, using lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) as an ionic modulator. The dual‐network PAAm/PVA skeleton provides robust deformable support, while LiTFSI incorporation is associated with changes in PEDOT chain conformation, intermolecular packing, and nanoscale organization. These structural changes accompany the improved electrical and electrochemical performance of the PEDOT:PSS–PAAm/PVA–LiTFSI (PPLi) hydrogel. The optimized PPLi hydrogel exhibits high conductivity (28.4 S cm −1 on average, 33.2 S cm −1 at maximum), high specific capacitance (202.5 F g −1 ), excellent stretchability (∼506%), and excellent anti‐freezing capacity down to −40°C. The assembled all‐hydrogel symmetric supercapacitor delivers superior energy output, outstanding capacitance retention of 98.8% over 10 000 cycles, and stable output under twisting, folding, and 100% tensile strain. The device retains 85% capacitance at −40°C and powers wearable electronics when integrated into flexible wristbands. This work provides a mild and scalable strategy for coupling three‐dimensional free‐standing architectures with ionic regulation to develop conductive polymer hydrogel electrodes with high mechanical robustness and electrochemical efficiency for wearable energy‐storage applications.