A super-high energy density asymmetric supercapacitor based on 3D core–shell structured NiCo-layered double hydroxide@carbon nanotube and activated polyaniline-derived carbon electrodes with commercial level mass loading

Abstract

Realization of high cell energy density at high mass loading is a critical requirement for the practical applications of supercapacitors. To date, the cell energy density of supercapacitor devices has been mainly limited by the low utilization efficiency of electroactive materials on positive electrodes at high mass loading and the low capacitance value of common activated carbon materials on negative electrodes. In this study, a super-high energy density asymmetric supercapacitor device with commercial mass loading was successfully fabricated by using a 3D core–shell structured NiCo-layered double hydroxide@carbon nanotube (NiCo-LDH@CNT) composite as the positive electrode and activated polyaniline-derived carbon (APDC) as the negative electrode. Due to its unique core–shell structure, the NiCo-LDH@CNT/nickel foam (NF) electrode with a mass loading of 8.5 mg cm⁻² delivered a high capacitance of 2046 F g⁻¹ at 1 A g⁻¹, and still retained a high capacitance of 1335 F g⁻¹ as the current density increased up to 15 A g⁻¹. Coupled with the high performance APDC-based negative electrode with a capacitance of 487 F g⁻¹ at 1 A g⁻¹, the asymmetric NiCo-LDHs@CNT/NF//APDC/NF supercapacitor device delivered a maximum energy density of 89.7 W h kg⁻¹ with an operational voltage of 1.75 V, and a maximum power density of 8.7 kW kg⁻¹ at an energy density of 41.7 W h kg⁻¹, suggesting its promising applications in future.