Synthesis of soybean-derived porous carbon as selenium host for high-performance lithium-selenium batteries

Selenium (Se) is a promising cathode material for rechargeable lithium batteries due to its prominent volumetric capacity and relatively high electrical conductivity. However, designing a sustainable and cost-effective porous carbon as Se host in the cathode with appealing electrochemical performance is a challenge. Herein, a hierarchically porous carbon was synthesized from soybean in a carbonization/activation process and used to develop the selenium cathode material for lithium-selenium (Li-Se) batteries. The effect of activation temperature (500, 600, and 700 °C) on the porous structure of the activated carbons was investigated and correlated to the electrochemical performance of their carbon/selenium (C/Se) cathode composite in Li-Se batteries with a carbonate-based electrolyte. It was revealed that the specific surface area and pore volume of the porous carbon increased with elevating the activation temperature. The Li-Se battery using the carbon activated at 600 °C (C600) showed a superior reversible discharge capacity of 640 mAh g−1 at 0.1 C after 100 cycles, exceptional rate capability, and good long cycling stability of ∼400 mAh g−1 at 1 C over 500 cycles. The superior electrochemical performance of C600/Se cathode compared to the other samples was attributed to its microporous structure coupled with large surface area and pore volume, which could favor effective confinement of Se, electrolyte wetting, Li-ion diffusion, and accommodation of volume change. This work suggests the sustainable development of microporous carbon with a structure suitable for cathode material in Li-Se batteries.