Enhanced performance and cycling behavior in symmetric supercapacitors developed by pure HfB2 and HfB2-SiC composites

Abstract

Boron-based materials have attracted growing interest as promising candidates for energy storage applications. This study focuses on synthesizing pure HfB2 powders through a straightforward method involving the mechanical activation of a powder mixture comprising hafnium tetrachloride (HfCl4), boron (B), and magnesium (Mg). The HfB2 powders were mechanically alloyed with varying amounts of SiC powders to create HfB2-based composite structures. The chemical and microstructural properties of the synthesized samples were assessed using XRD, SEM/EDX, and DLS characterization techniques. Supercapacitor device performances of all resulting powders as symmetrical electrodes were systematically investigated. The test results revealed that the pure HfB2 electrode material exhibited a pseudocapacitor behavior, whereas composite powders exhibited battery-like behavior. Composite powders, demonstrated enhanced supercapacitor performance surpassing that of pure powder in terms of energy density and cycle efficiency. The pure HfB2 electrode displayed the highest power density (95 Wkg  1) among all samples: Its distinctive pseudocapacitor behavior results in the highest power density, providing valuable insights into the intricate relationship between composition and electrochemical performance in boron-based supercapacitor materials. Moreover, these results propose that by synthesizing composite powders, the charge storage mechanism can be altered and used to improve the energy density.