Waste banana bract-derived porous carbon as anode for lithium/sodium-ion batteries with hybrid adsorption-pore filling/insertion mechanism

Abstract

Lithium-ion batteries (LIBs) and sodium-ion batteries (SIBs) are critical electrochemical energy storage devices with promising applications; however, commercial graphite cannot meet the growing energy demand owing to its limited capacity and rate performance. In this study, addressing the utilization requirements of waste banana bracts, a straightforward KOH activation and carbonization method at 700°C-900 °C is employed to produce porous carbon from waste banana bracts for use in LIBs and SIBs. The large surface area and heteroatom doping provide abundant storage sites, while the porous structure facilitates ion storage and diffusion through the creation of fast channels. As a result, the banana bracts-derived carbon exhibits high capacity and long cycle life. LIBs exhibit high capacities of up to 953.89 mAh g⁻¹ at 0.1 A g⁻¹, which remain at 320.41 mAh g⁻¹ after 1000 cycles at 1 A g⁻¹. Similarly, SIBs show remarkable capacities of 212.16 mAh g⁻¹ at 0.1 A g⁻¹, maintaining stable capacity over 1000 cycles. These capacities and rate performances surpass conventional graphite anodes. Moreover, electrochemical studies, including cyclic voltammetry, ex-situ X-ray diffraction, and ex-situ Raman spectroscopy, elucidate the storage mechanism, demonstrating the promising potential of banana bracts-derived carbon as an anode material for both LIBs and SIBs.