Facile Preparation of an Excellent Mechanical Property Electroactive Biopolymer-Based Conductive Composite Film and Self-Enhancing Cellulose Hydrogel to Construct a High-Performance Wearable Supercapacitor

Wearable supercapacitors, as one of the most important power supplies for wearable electronics, require excellent flexibility and deformability and a structure that is not easily delaminated. In this work, a robust ligninsulfonate/single-wall carbon nanotube film/holey reduced graphene oxide (Lig/SWCNT/HrGO) film with excellent tensile strength (121.8 MPa) and flexibility has been prepared via a filtration process followed by a hydrothermal treatment. During the filtration process, the SWCNT and small-size holey graphene oxide (HGO) can form a multilayer-like interconnected structure, and a part of HGO with a large specific surface area intersperses in the SWCNT network. HGO can be further reduced to HrGO, and the HrGO, Lig, and SWCNT can combine tightly to generate a compact multilayer-like structure during the hydrothermal process. High-strength, flexible, porous cellulose hydrogel (9.56 MPa) has been fabricated via a self-enhancing method through phase inversion of microcrystalline cellulose and partially dissolved bacterial cellulose mixture dispersion. A wearable supercapacitor is assembled by the Lig/SWCNT/HrGO films and self-enhancing cellulose hydrogel, which exhibits excellent tensile strength (112.3 MPa), areal capacitance (1121 mF cm–2), and energy density (77.8 μWh cm–2). More importantly, the areal capacitance shows a nearly linear increase with an increase in the mass of the film electrode. When the film electrode mass reaches up to 16.5 mg cm–2, the wearable supercapacitor delivers an ultrahigh areal capacitance of 4110 mF cm–2 and an energy density of 285.4 μWh cm–2. Remarkably, the wearable supercapacitor can sustain many types of arbitrary deformation and this outstanding flexibility is attributed to the strong interaction between wood-derived cellulose and Lig, which prevents the delamination of the electrodes and the separator. This work provides a facile approach for the preparation of a biopolymer-based, multilayer-like structure film and a self-enhancing method to obtain high-strength cellulose hydrogel, thus developing a biomimetic high-performance wearable energy storage device.