NiCoP nanowire@NiCo-layered double hydroxides nanosheet heterostructure for flexible asymmetric supercapacitors

Abstract

Reasonable design of multi-component composites with heterostructures is an effective strategy to improve the performances of energy storage materials. Herein, we fabricate a supercapacitor electrode consisting of a 3D hierarchical NiCoP@NiCo-LDH core/shell heterostructure on conductive carbon cloth (CC). Such special structure integrates the advantages of the highly interconnected nanosheets of NiCo-LDH, the high conductivity of NiCoP, excellent mechanical strength of CC, and the 3D hierarchical open structure. Density functional theory (DFT) calculations reveal the superior electrical conductivity of NiCoP core and the powerful affinity for OH− of NiCo-LDH shell, which provide additional theoretical assistance for the improved electrochemical performance. Benefiting from the well-defined core/shell heterostructure and efficient synergetic effects among multi-components, the CC/NiCoP@NiCo-LDH electrode exhibits a high capacitance of 4.683 F cm−2 (1951 F g−1) at the current density of 1 mA cm−2 and an excellent rate capability of 89.3% at 20 mA cm−2. In addition, a flexible asymmetric supercapacitor (FASC) composed of CC/NiCoP@NiCo-LDH as the positive electrode and activated carbon (AC) as the negative electrode achieves a high energy density of 57 Wh kg−1 at the power density of 850 W kg−1 and an outstanding cycling stability of 97% capacitance retention after 10,000 cycles. The above results suggest that CC/NiCoP@NiCo-LDH has potential to be selected as a candidate of positive electrode for constructing FASC.