A synergistic electrochemical approach of boron-doped carbon/cobalt pyrophosphate//MXene for high-performance all solid-state asymmetric devices

Abstract

The incorporation of boron into the carbon matrix makes it an efficient candidate for supercapacitor application. Furthermore, the excellent stability of cobalt pyrophosphate and the inherent redox behaviour of cobalt provides an opportunity to synthesize boron-doped carbon/cobalt pyrophosphate hybrid materials. Herein, a two-step process is followed for the synthesis of a boron-doped carbon/cobalt pyrophosphate hybrid. Through the appropriate adjustment of the amount of boron during synthesis, the electrochemical performances of a set of materials were studied. The material synthesized with 4 mg of boron (B-GC@CPP-4) exhibited a specific capacitance of 395.1 F g⁻¹ at 1.5 A g⁻¹ mass normalized current density. However, the intrinsic hydrophilicity and metallic conductivity of MXene make it an eminent electroactive material for use as a negative electrode. Owing to the above properties, the all-solid-state asymmetric supercapacitor cell (ASC) was fabricated [B-GC@CPP-4//MXene], which exhibited a specific capacitance of 125 F g⁻¹ with an energy density of 45 W h kg⁻¹ at a power density of 1735 W kg⁻¹at 2 A g⁻¹ current density. The ASC device possesses an excellent coulombic efficiency of 98.5% and capacitance retention of 96% over 10 000 consecutive charge/discharge cycles. Boron, with one electron less than carbon, is the vital reason behind the improved electrochemical performance of the hybrid material. The study reveals B-GC@CPP-4//MXene to be a promising set-up for energy storage devices.