Enhanced Electrochemical Matching between NiCo2O4/Reduced Graphene Oxide and Polymer Cement Electrolyte for Structural Supercapacitor

Electrochemical performance of electrode in structural supercapacitor is much lower than that in common supercapacitor owing to solidification confinement of ions movement. Herein, NiCo2O4/reduced graphene oxide (rGO) nanosheets are firstly assembled with KOH/polyacrylic acid (PAA)/cement, LiOTf/PAA cement, KOH/polyethylene oxide (PEO) cement and LiOTf/PEO cement into four structural supercapacitors through hydration process. As the NiCo2O4 content in NiCo2O4/rGO composite exceeds 13 wt%, the areal capacitance of NiCo2O4/rGO electrode at high current densities decreases. The (13%) NiCo2O4/rGO electrode presents the best electrochemical performances with initial areal capacitance of 3.16 F cm−2 at 0.5 mA cm−2, capacitance retention rate of 61% after current density increasing by 80-fold and retention of 86.1% after 10000 cycles at 10 mA cm−2. The corresponding four structural supercapacitors show superior electrochemical performances with areal capacitances of ∼ 330.4 mF cm−2, coulombic efficiencies of ∼ 100%, power densities of ∼ 2.7 mW cm−2 and energy densities of ∼ 0.64 mWh cm−2. The electrochemical efficiencies of (13%) NiCo2O4/rGO electrodes in four structural supercapacitor devices are in the range of 0.16 ∼ 0.12, which are prominent in high-end structural supercapacitors. Thus NiCo2O4/rGO electrode is demonstrated to enhance the electrochemical matching with polymer cement electrolyte for structural supercapacitor.