Enhancing high-performance supercapattery electrodes: harnessing structural and compositional synergies via phosphorus doping on bimetallic boride for rapid charging

Currently, there is an urgent need for the innovative development of efficient electrochemical energy storage (EES) devices, particularly for use in electric vehicles (EVs). Supercapatteries have been proposed as an effective EES device because they combine the benefits of batteries and supercapacitors to produce a high energy density device with high power capacity over a long-life span. In the present study, phosphorus-doped nickel cobalt boride is tested as an electrode material due to its unique supercapattery behavior that produces high specific capacity with high-rate capability. In this material, nickel, cobalt, and boride combine to offer electrochemical activation, electrochemical reversibility, and electrical conductivity, respectively, while phosphorus doping is employed to tune the electrochemical behavior. The supercapattery electrode delivers high specific capacity with a battery-type charge storage mechanism of 1576 C g⁻¹ (≈3502 F g⁻¹) at 2 A g⁻¹ with a capacity retention of about 85.2% after 50 000 cycles performed at a high current density of 40 A g⁻¹. The supercapattery device results at a high energy density of 41.56 W h kg⁻¹ even at the highest power density of 15 000 W kg⁻¹ with capacity retention of 83.33%