Eco-Sustainable Wheat-Derived Porous Carbon for Cutting-Edge Battery Cathodes

Amidst growing demand for sophisticated energy storage solutions, lithium-selenium (Li-Se) batteries have emerged as a viable substitute for lithium-sulfur (Li-S) batteries, presenting advantages including superior energy density, cost efficiency, and eco-friendliness. However, the implementation of Li-Se batteries encounters several obstacles, such as low active material utilization, inadequate electrical conductivity, rapid capacity degradation, and the notorious lithium polyselenide (LiPSe) shuttle effect. In this study, we address these obstacles by introducing porous carbon derived from wheat grains (denoted as WG_r) through a straightforward carbonization-KOH activation procedure. By optimizing the mass ratio of carbonized wheat grains to KOH in a 1:2 ratio, we obtained a carbon material WG₂ with a unique hierarchical porous structure that effectively encapsulates selenium within its small pores. The microporous feature in the WG₂ material promotes solid–solid reactions, mitigates the LiPSe shuttle effect, enhances electrical conductivity, and ensures high electrochemical utilization of selenium. The WG₂ material exhibits a diverse porous carbon framework with a Brunauer–Emmett–Teller (BET) surface area of 497.8519 m² g⁻¹ and a cumulative pore volume of 0.250 cm³ g⁻¹. Utilizing the WG₂ carbon structure as a cathode host substrate in Li-Se batteries, the composite WG₂@Se, with selenium loading of 43.13%, demonstrates impressive performance. After 600 cycles, it exhibits a reversible capacity of 384.6 mAh g⁻¹ (at 1 C) and a remarkable rate performance of 311.7 mAh g⁻¹ at 4 C. Furthermore, when applied in sodium-selenium (Na-Se) batteries, the WG₂@Se cathode displays superior rate capabilities and stable cycling performance. The incorporation of wheat grain-derived hierarchical porous carbon structure into Li/Na-Se batteries paves the way for cost-effective and eco-friendly techniques in the development of confined selenium cathodes. The research offers valuable understanding of the design and development of cutting-edge cathode materials, contributing to the ongoing efforts within the realm of Li/Na-Se batteries.

We utilized wheat grain-derived porous carbon (WG₂), obtained through carbonization and KOH activation, to successfully encapsulate selenium within its pores, significantly enhancing electrical conductivity and cycle stability, and mitigating the polyselenide shuttle effect in selenium-based batteries.