Amorphous Cobalt Boride Alloy Synthesized by Liquid Phase Methods as Electrode Materials for Electrochemical Capacitors

Abstract An amorphous cobalt boride alloy with high electronic conductivity is fabricated through the liquid‐phase reduction method. Benefiting from large specific surface area and hierarchical pore structure, the as‐synthesized Co‐B nanoflakes expose substantial electrochemical active sites, promote the transfer of electrons and ions, and accelerate the redox kinetic process. The as‐obtained amorphous Co‐B alloy sample displays a specific capacitance of 411 F g⁻¹ at 0.5 A g⁻¹, and with the current density increased to 10 A g⁻¹, it maintains 69% of the initial capacitance. The as‐assembled asymmetric supercapacitor device reveals electrochemical properties comprising an excellent specific capacitance of 64.3 F g⁻¹ at 0.25 A g⁻¹, superior cyclical stability of 105% after 20,000 cycles at 3 A g⁻¹, and maximum energy density of 22.9 Wh kg⁻¹ at a power density of 200.3 W kg⁻¹. This study demonstrates great potential in developing high‐conductivity materials for an asymmetric supercapacitor through utilizing an amorphous cobalt boride alloy as a promising electrode material.