Acid etching halloysite loaded cobalt boride material for supercapacitor electrode application

Inexpensive and eco-friendly cobalt boride@etched halloysite (CoB@eHal) composites with excellent electrochemical performances were fabricated by a facile combination of acid etching and chemical liquid-phase reduction. The highly conductive CoB nanoparticles were tightly combined with etched halloysite in a loaded manner. Owing to the open channels of etched halloysite after acid etching and the loading of intermetallic CoB, the CoB@eHal-12 composite exhibited a relatively large specific surface and low charge transfer resistance. The charge storage mechanism belonged to redox pseudocapacitance, and the contribution of pseudocapacitance in the whole charge storage process is 67.9%. The optimized CoB@eHal-12 demonstrated satisfactory specific capacitance of 266.9 F g ⁻¹ at 0.5 A g ⁻¹ , outstanding rate capacity and unexceptionable cycling stability of approximately 84.7% retention over 10,000 continuous charge-discharge cycles. Furthermore, an asymmetric supercapacitor was constructed by using the CoB@eHal-12 as a cathode and activated carbon (AC) as an anode. The obtained CoB@eHal-12//AC device delivered a maximum energy density of 17.0 W h kg ⁻¹ with a power density of 200.2 W kg ⁻¹, and a satisfactory life cycle.