Self-assembled architecture of 2D layered double hydroxide pillared with 0D polyoxomolybdate anions: High-performance redox-type cathode for solid-state hybrid supercapacitor

Herein, mesoporous self-assembled architecture of two-dimensional (2D) nickel chromium-layered double hydroxide (NiCr-LDH) monolayers pillared with 0D polyoxomolybdate anions (NCMo) was prepared via a lattice engineering rapid exfoliation-restacking synthesis route. The self-assembled 2D-0D NCMo architecture exhibited expanded surface area, porous interconnected nanosheet morphology, flexible chemical composition, layer-bylayer stacking structure, and excellent electrochemical activity. The NCMo architecture exhibited promising electrochemical performance with a large specific capacity of 567 C g-1 at a current density of 1 A g-1, and an excellent cyclic retention of 89 % after 5000 charge-discharge cycles. Additionally, an all-solid-state hybrid supercapacitor (HSC) device was assembled using NCMo architecture as the redox-type cathode, reduced graphene oxide (rGO) as the EDLC-type anode, and PVA-KOH gel as the electrolyte. The NCMo-2//PVA-KOH//rGO HSC device exhibited a high specific capacitance (171.8 F g-1 at 10 A g-1), decent cycling stability (91 % after 10,000 cycles), and a high energy/power density (61.1 Wh kg-1/6.7 W kg-1). The findings of this study demonstrate that the intercalation of polyoxomolybdate is an effective lattice-engineered method for improving the electrode functionality of self-assembled LDH-based architectures.