Preparation and application of self-healing polyvinyl alcohol/bacterial cellulose hydrogel electrolyte

Abstract

Polyvinyl alcohol (PVA), bacterial cellulose (BC) and sulfuric acid were used as raw materials to prepare PVA/BC composite hydrogel electrolyte (CHEPVA/BC) by physical cross-linking freezing-thawing cycle method. After freeze-thaw cycles, PVA and BC form a large number of intermolecular hydrogen bonds, which endow the composite hydrogel with good self-healing property (SHP) and mechanical properties (MPs). The effect of BC content (BCC) on MPs and ionic conductivity (IC) of CHEPVA/BC were discussed. The results show that the composite hydrogel with BCC of 0.6% has the best SHPs and MPs, with breaking strength and IC as high as 0.41 MPa and 138.9 mS/cm, respectively. After the first healing cycle (FHC), IC and healing rate still reach 84.1 mS/cm and 74%, respectively. Polyaniline electrode was polymerized in-situ on the surface of the self-healing CHEPVA/BC, and a flexible all-in-one supercapacitor was designed and assembled. The results show that when aniline concentration is 0.2 mol/L, the supercapacitor device achieved high specific capacitance (580.8 mF/cm2), excellent energy density (20.17 μW·h/cm2) and power density (50 μW/cm2) at current density of 0.2 mA/cm2, and the capacitance retention rate after the FHC reaches 66%, showing good self-healing performance and great potential to maintain mechanical integrity and electrochemical stability. These findings indicate that the self-healing CHEPVA/BC has great application prospects in flexible wearable energy storage devices.