CoNi bimetallic engineering on porous carbon for high energy density hybrid supercapacitors

Abstract

Rationally designed, structurally stable, and high-capacity transition metal alloy decorated carbon composites have attracted considerable attention as electrode materials for high-performance hybrid supercapacitors (HSCs). A unique electrode material composed of mixed transition metals (Co and Ni) on fryums-derived porous carbon was synthesized using a facile one-step pyrolysis approach. The CoNi@C composite exhibited rich redox kinetics and good electrochemical performance in an aqueous alkaline electrolyte. In particular, the CoNi@C composite delivered a maximum specific capacity of 390 mA h g−1 at 1 A g−1 with good capacitance retention of 91 % over 5000 cycles. The gravimetric specific capacity of the CoNi@C composite was 1.3 times better than that of the single alloy composite. Moreover, the HSC fabricated with CoNi@C, and activated carbon electrodes exhibited a high energy density of 57.6 Wh kg−1 at a power density of 742 W kg−1 and good cycling stability with a low-capacity loss of 8 % after 5000 cycles. Utilizing high-voltage and energy density, the HSCs can power light-emitting diodes of different wavelengths, demonstrating its practical applicability in energy storage technologies. The structural verification of fryum-derived carbon revealed a good graphitization degree, ensuring its remarkable adaptability for device fabrication.