A VO3−-induced S2−-exchange strategy to controllably construct a sub-nano-sulfide-functionalized layered double hydroxide for an enhanced supercapacitor performance

Abstract

Due to the intrinsic ion channels that originate from their lamellar structure and flexible composition, layered double hydroxides (LDHs) have aroused extensive attention in the scientific community. However, the related poor conductivity and narrow interlayer spaces of LDHs limit the mass-transfer rate during the fast charging/discharging process for supercapacitor application. Here, through a VO₃⁻-induced S²⁻ anion-exchange process, (Ni/Co)_1−xS sub-nanoparticle-functionalized VO₃⁻-doped Co/Ni-LDH hollow nanocages (S-CNV-LDH) are successfully prepared. The hierarchical hollow nanocage structure constructed by the (Ni/Co)_1−xS sub-nanoparticle-functionalized S-CNV-LDH nanoplates can provide rich channels, abundant heterojunction interfaces and enhanced conductivity for a fast and deep mass-transfer process. Therefore, the optimized S-CNV-LDH nanocages present a high specific capacitance of 1345 F g⁻¹ at 1 A g⁻¹ and an excellent rate capability of 84.6% at 10 A g⁻¹. Furthermore, an S-CNV-LDH‖AC device was fabricated using active carbon (AC) as the negative electrode and a high energy density of 42.51 W h kg⁻¹ is achieved at 0.8 kW kg⁻¹. This work provides a facile and controllable path for the preparation of sub-nano-sulfide in situ involved LDH materials.