High-capacity three-dimensional solar rechargeable micro-supercapacitor using MnO2/V2O5-based binary metal oxide nanocomposite ink

Due to the variable nature of solar cells, the development of a novel energy storage system, such as solar-charged self-powered micro-supercapacitor (MSC) power cells, is imperative. Herein, we report a pen-drawing MSC for powering portable units using high-performance binary metal oxide nanocomposite ink. For improving the capacitance of the MSC and operating its voltage up to 1.4 V, the nanocomposite ink demonstrated a redox strategy; this strategy involved fabricating MnO2, V2O5, and a conductive poly(3,4-ethylenedioxythiophene) (PEDOT) polymer onto graphene flakes as a sandwich structure. The MSC exhibited excellent electrochemical performance with an areal capacitance of 89.29 mF cm−2, a maximum energy density of 0.024 mWh cm−2 at a power density of 0.35 mW cm−2, and adequate cyclic stability (82 % capacitance retention after 2500 cycles). The strained MSC also exhibited mechanical stability within a potential window of 0–1.4 V at a scan rate of 100 mV s−1. Furthermore, vertically stacked MSC arrays connected in series and parallel networks were integrated with a commercial solar cell to fabricate solar-charged self-powered MSCs. The results showed that self-powered electronics integrated with pen-drawn MSCs and solar cells have potential applications in the field of solar energy storage, including portable or wearable electronics.