Structural reconstruction of N/S-assisted carbon polyhedral matrix endowed with bimetallic phosphide heterostructures for energy storage

Abstract

The synergism of heteroatom-doped carbon polyhedral with mixed-metal networks offers a myriad of electroactive sites that aid in excellent capacitive performance. Herein, a simple precipitation method was implemented to synthesis thiourea functionalized bimetallic ZIF-67 polyhedral as a sacrificial template, facilitating the construction of a superior N/S‑carbon matrix with a Co-Ni-P (CNS/CNP) architecture through various thermal phosphorization processes. The CNS/CNP-2 revealed remarkable attributes after phosphorization at 500 °C, including a maximum specific capacitance of 588 F g−1 at a specific current of 1 A g−1 in 3 M KOH electrolyte. This outstanding performance arises from the synergy of N/S carbon matrix, which significantly increases electroactive sites and structural stability, and Co-Ni-P network, which enhances both redox-active site density and conductivity, facilitating rapid ion diffusion. Furthermore, an asymmetrical supercapacitor was integrated as CNS/CNP-2//AC and revealed a maximum specific energy and power of 30.3 W h kg−1 and 12,489 W kg−1, respectively, with capacitance retention of 90% even for 10,000 cycles. The ASC device was designed as a coin-cell to facilitate real-time applications. The study demonstrates that a synergistic effect between Co–Ni metal ions and a heteroatom matrix can yield an electrode material with a high specific capacity for energy storage devices. © 2023