High-performance stretchable flexible supercapacitor based on lignosulfonate/Prussian blue analogous nanohybrids reinforced rubber by direct laser writing

With the advent of the Internet-of-Things (IoT) era, flexible supercapacitors (F-SC) have emerged as one of the most promising power sources for wearable devices. However, the rapid fabrication of F-SC with high energy density and stretchability remains a challenge. In this study, an intrinsically stretchable rubber-based supercapacitor, for the first time, was fabricated from Co-Fe Prussian blue analogous (Co-Fe PBA)/sodium lignosulfonate (LS) nanohybrids (PBA-LS) reinforced carboxylated nitrile rubber (XNBR) by direct laser writing (DLW) technology. Under the transient photothermal action of programable high-energy laser irradiation, biomass-derived LS among PBA-LS nanohybrids was directly transformed into patterned porous graphitized carbon on the surface of PBA-LS/XNBR substrates (PLX), while Co-Fe PBA was pyrolyzed into bimetallic compound nanoparticles as pseudocapacitive materials embedded into the carbon framework. Benefiting from the in-situ doping of the bimetallic compounds within the LS-derived carbon framework on flexible PLX substrates, the rubber-based electrode showed an excellent electrochemical activity, reversibility and stability. Accordingly, symmetric interdigitated F-SCs could be rapidly fabricated by DLW, showing high areal capacitance of 479.08 mF cm−2 and energy density of up to 80.07 μWh cm−2. To achieve their stretchability, "island-bridge" structured stretchable F-SCs (SF-SC) were fabricated through Kirigami technology and liquid metal linkage. The rubber-based SF-SC demonstrated high voltage window and energy density as well as excellent electromechanical stability for powering small devices. This work provided new insights into the scalable fabrication of flexible energy storage devices by DLW, and it was of significant importance for the development of rubber-based flexible electronics and the valorization of biomass LS.