CoNi layered double hydroxide anchored on N-doped carbon coated carbon nanotubes network with 3D Core-shell structure for all-solid-state supercapacitors

Designing rational composites structure and integrating the advantage of components are highly desirable to realize high performance supercapacitors. Herein, by in-situ growth method, we fabricated the 3D core-shell structure N-CNTs@CoNi-LDH composite, which is consisted of CoNi layered double hydroxide as shell and N-doped carbon coated carbon nanotubes as core. Due to the introduction of N-doped carbon coated carbon nanotubes and the construction of 3D core-shell structure, the optimized N-CNTs@Co2Ni1-LDH electrode displays a specific capacity of 693 C g(-1) at 1 A g(-1), good rate characteristic (80% retention at 20 A g(-1)) and excellent electrochemical stabilization (93% retention after 10,000 cycles). Moreover, the constructed all-solid-state asymmetric supercapacitor using N-CNTs@Co2Ni1-LDH as positive electrode and honeycomb porous carbon as negative electrode achieves a high energy density of 51.3 Wh kg(-1) and good electrochemical stabilization (92% retention after 10,000 cycles) in PVA/KOH gel electrolyte. More significantly, the asymmetric supercapacitor delivers a high energy density of 23.1 Wh kg(-1) even at a high power density of 32 kW kg(-1).