In situ formation of MnO@N-doped carbon for asymmetric supercapacitor with enhanced cycling performance

Abstract

Searching electrodes with high specific capacitance, rate capability, long cycling life and economic efficiency is central for next-generation supercapacitors. In this work, a hybrid electrode consisting of MnO and N-doped carbon (MnO–NC) was constructed using KMnO₄ and carboxymethyl chitosan as manganese sources and carbon sources respectively. The effect of the ratio of KMnO₄ to carboxymethyl chitosan on the structure and electrochemical performance of MnO–NC was investigated in detail. At the optimized condition, a high specific capacitance of 326.36 F g⁻¹ was obtained with satisfied cyclic stability. Moreover, an asymmetric supercapacitor (ASC) device (MnO–NC//AC), consisting of MnO–NC as the positive electrode and activated carbon (AC) as the negative electrode was assemble, which exhibited a specific energy density was 9.35 W h kg⁻¹ at a power density of 374.83 W kg⁻¹. Owing to the long activation process, the capacitance of the ASC device remains 172% after 10 000 cycles. These results indicate that the prepared MnO–NC has great prospects for the application of high-performance supercapacitors.