A Sustainable and Cost‐Effective Nitrogen‐Doped Three‐Dimensional Porous Carbon for High‐Performance Lithium‐Sulfur Batteries

Abstract Affordable clean energy is one of the major sustainable development goals that can transform our world. At present, researchers are working to develop cheap electrode materials to develop energy storage devices, the Lithium‐sulfur (Li−S) battery is considered a promising energy storage device owing to its excellent theoretical specific capacity and energy density. Herein, utilizing the ramie degumming waste liquid as raw materials, after freeze‐drying and high‐temperature calcination, a sustainable and cost‐effective three‐dimensional (3D) porous nitrogen‐doped ramie carbon (N‐RC) was synthesized. The N‐RC calcined at 800 °C (N‐RC‐800) shows a superior high specific surface area of 1491.85 m 2 ⋅ g −1 and a notable high pore volume of 0.90 cm 3 ⋅ g −1 . When employed as a sulfur host, the S@N‐RC‐800 cathode illustrates excellent initial discharge capacity (1120.6 mAh ⋅ g −1 ) and maintains a reversible capacity of 625.4 mAh ⋅ g −1 after 500 cycles at 1 C. Simultaneously, the S@N‐RC‐800 cathode also shows excellent coulombic efficiency and ideal rate performance. Such exceptional electrochemical performance of S@N‐RC‐800 can be primarily attributable to N‐RC's high specific surface area, high porosity, and abundant polar functional groups. This green and low‐cost synthesis strategy offers a new avenue for harnessing the potential of waste biomass in the context of clean energy storage.