Metal-Free On-Chip Battery-Supercapacitor Hybrid System Based on Rationally Designed Highly Conducting Laser-Irradiated Graphene-Based Electrodes

Battery-supercapacitor hybrid (BSH) devices generally provide both high energy and power density but usually suffer from the serious electrochemical kinetics mismatch of cathodes and anodes mainly due to complex faradaic reactions of the unmatched battery-type electrodes used for charge storage, which inevitably degrade rate capability and power density. In this work, we have grown MnO2 nanoflowers and polypyrrole (PPy) nanoparticles uniformly on a conducting laser-irradiated graphene (LIG) network. This work also demonstrates a high-performing rechargeable Zn-MnO2 battery system based on a zinc anode and LIG@MnO2 cathode in a mild acidic electrolyte, which delivers good storage capacity with extreme stability under optimized electrolyte conditions. For the very first time, a BSH system was designed utilizing LIG@PPy as a supercapacitive electrode and LIG@MnO2 as a battery electrode in a mild electrolyte system of 1 M ZnSO4 + 0.2 M MnSO4. The BSH full cell exhibited enhanced energy density and promising Zn-ion storage capability. The in-house made on-chip BSH cell exhibits high capacity (2.97 mAh cm-2), a cell voltage of 1.9 V, and a 97.8% capacitive retention after 9000 continuous charge-discharge cycles. Furthermore, the assembled LIG@MnO2//LIG@PPy BSH system delivers a total energy density of 5.9 mWh cm-2, among the highest values achieved in aqueous hybrid storage devices.