Enhanced electrochemical performance of C-NiO/NiCO2O4//AC asymmetric supercapacitor based on material design and device exploration

Asymmetric supercapacitors (ASCs) as a promising candidate to complement batteries, have been studied for decades due to the relatively high power density. The energy storage of ASCs is significantly affected by the well-designed electrode material and delicate charge balance of electrodes. With the hope to design better supercapacitor devices, we firstly synthesize C-NiO/NiCO2O4 nanocomposites with the modified nanowire structure and a small amount of carbon, effectively boosting the specific capacitance and cyclic-stability. In addition, a multi-electrode system is developed to investigate match degrees of C-NiO/NiCO2O4//AC ACSs, and the inter-restricted behavior of positive and negative electrodes. By this real-time electrochemical method, the potential contributions of electrodes in ASCs are further revealed during charge/discharge process. Therefore, ASC device with optimal match degree delivers areal capacitance up to 3482 mF cm(-2), and the maximum energy and power density of 42.69 mWh cm(-3) and 1.66 W cm(-3). Importantly, this work throws light on the fundamental study for supercapacitors in terms of materials design and charge match degrees. (C) 2018 Published by Elsevier Ltd.