Mesoporous Carbon Derived from Wheat Grains for Advanced Lithium/Sodium-Selenium Batteries Cathode

Abstract

With the increasing demand for advanced energy storage systems, lithium-selenium (Li-Se) batteries have emerged as a promising alternative to lithium-sulfur (Li-S) batteries, offering high energy density, cost-effectiveness, and environmental friendliness. However, practical implementation of Li-Se batteries encounters several challenges, including low active material utilization, poor electrical conductivity, rapid capacity degradation, and the lithium polyselenide (LiPSe) shuttle effect. In this study, we address these obstacles by introducing porous carbon derived from wheat grains (WGr) through a straightforward carbonization-KOH activation process. By optimizing the ratio of carbonized wheat grains to KOH at 1:2, we created a unique mesoporous carbon material, WG2, effectively encapsulating selenium within its pores. WG2's mesoporous structure promotes solid-solid reactions, reduces the LiPSe shuttle effect, enhances electrical conductivity, and maximizes selenium's electrochemical utilization. With a BET surface area of 497.8519 m² g-1 and a cumulative pore volume of 0.250 cm³ g-1, WG2 demonstrates excellent structural diversity. Utilizing WG2 as a cathode host material in Li-Se batteries, the composite WG2@Se, loaded with 43.13% selenium, exhibits outstanding performance. After 600 cycles, it achieves a reversible capacity of 384.6 mAh g-1 (at 1C) and an impressive rate performance of 275.32 mAh g-1 at 4C. Moreover, when applied in sodium-selenium (Na-Se) batteries, WG2@Se displays superior rate capabilities and stable cycling performance. The integration of wheat grain-derived mesoporous carbon into Li/Na-Se batteries introduces cost-effective and eco-friendly methods for confined selenium cathode development. This study offers valuable insights, contributing significantly to the advancement of advanced cathode materials in the realm of Li/Na-Se batteries.

Keywords: Wheat grains, Mesoporous carbon framework, Carbon/Se composites, Carbonate electrolyte, Li-Se batteries, Na-Se batteries