Stable coal tar pitch-derived hard carbon anodes with modulated oxygen functional groups for enhanced Li-ion storage

Abstract

As a major class of anode materials for lithium-ion batteries (LIBs), carbon-based materials are widely researched and utilized owing to their resource abundance, low cost, and easy of fabrication. However, the primary challenges for carbon anodes are their limited cycle life and poor rate capability. Herein, by modulating hard carbon with oxygen functional groups, we achieve enhanced rate capability and improved cycling stability in LIBs, outperforming unmodified naturally porous carbon. Coal tar pitch (CTP), a low-cost industrial byproduct, was used as the carbon source to prepare porous carbon (PC). The obtained PC was then subjected to sequential acid and alkali treatments to modulate its surface oxygen-containing functional groups. The mechanism by which acid and alkali solutions modify the pore structures and oxygen-containing functional groups of carbon materials has been elucidated through FTIR, XPS, and other in situ characterization techniques. As an anode material for LIBs, it exhibited a high reversible capacity of 711.3 mA h g⁻¹ after 100 cycles at 0.1 A g⁻¹, while still maintaining a capacity of 440.4 mA h g⁻¹ after 550 cycles at 0.5 A g⁻¹. Moreover, when applied in the full cell, sodium ion batteries (SIBs) and lithium-ion capacitors (LICs), the obtained PC material also showed excellent cycling stability. This work provides new perspectives on the design of anode materials for both LIBs, SIBs and LICs.