Strong Magnetic-Field-Engineered Porous Template for Fabricating Hierarchical Porous Ni–Co–Zn–P Nanoplate Arrays as Battery-Type Electrodes of Advanced All-Solid-State Supercapacitors

Abstract

The sluggish charge transport kinetics that exist in the energy storage process of all-solid-state supercapacitors (ASSSCs) can be improved by designing open hierarchical porous structures for binder-free electrodes. Herein, a template-directed strategy is developed to fabricate open hierarchical porous Ni-Co-Zn-P nanoplate arrays (NCZP^6T) through phosphating the electrodeposited NiCo-LDH nanosheets loaded on a template. At first, porous conductive NiZn alloy nanoplate arrays are rationally devised as the template by a strong magnetic field (SMF)-assisted electrodeposition. The Lorentz force caused by coupling the SMF with the electrical current induces a magnetohydrodynamic (MHD) flow (including the micro-MHD flow), which homogenizes the deposition coating, tunes the nucleation and growth of the NiZn alloy, and produces pores in the nanoplates. The open hierarchical porous structure offers a larger specific surface area and pore volume for accelerating charge transport and gives a synergistic effect between the inner porous conductive NiZn array template and the outer electrochemical active phosphides for high-performance hybrid ASSSCs. Accordingly, the battery-type electrode of NCZP^6T shows a much higher specific capacitance of 3.81 F cm^-2 at 1 mA cm^-2, enhanced rate capability, and remarkable cycling stability at progressively varying current densities. Finally, the NCZP^6T//FeS ASSSC delivers a high energy density of 77 μW h cm^-2 at a large power density of 12 mW cm^-2, outperforming most state-of-the-art supercapacitors.