Quadrangular Prism Porous Shells Constructed by Parallelly Interconnected and Lattice-Strained NiCoP Nanoflakes for Maximized Energy Storage

One of the challenges with pseudocapacitive energy storage is maximizing the utilization of active materials while assuring their cycling stability due to diffusion confinement and low electron transferability. Herein, a new insight into the design of architectures with combined advantages of ultrathin 2D materials’ oriented distribution and structural modulation at the atomic scale is proposed. Porous quadrangular prism shells (PQPSs) constructed by parallelly and interconnected lattice-strained NiCoP nanoflakes are achieved via quadrangular prism-assisted surface anisotropic growth, template removal, and ion exchange. An aqueous asymmetric supercapacitor with the NiCoP PQPSs and activated carbon (AC) delivers outstanding cycle stability with 103.1% capacity retention even after 30 000 cycles at 20 A g⁻¹, much superior electrochemical performance over that reported for single-metal phosphides. The NiCoP//AC exhibits a prominent high energy density of 47.7 Wh kg⁻¹ at 800 W kg⁻¹, superior over most state-of-the-art devices. This is mainly attributed to the fact that the nanoflake-built shells effectively avoid “dead volume,” thus providing abundant ion-accessible active sites and straight ion transport channels as well as the lattice tensile strain demonstrated by geometrical phase analysis facilitates charge transportation. This work provides an innovative route to the controlled synthesis of space-oriented phosphides’ arrays for improved energy storage.