Design of self-supporting porous soft-hard carbon hybrid materials for ultra-long cycling lithium-ion storage

Abstract

Hard carbon materials are of great interest for battery electrodes due to their affordability, extensive surface area, robust chemical resilience, and superior electrical conductivity. However, limitations in non-faradaic reaction mechanisms restrict lithium storage capacity. To achieve high energy density in hard carbon anodes, we employed pre-oxidized coal pitch, polymethyl methacrylate as a soft template, and polyacrylonitrile-assisted electrospinning to fabricate oxygen/nitrogen co-doped coal pitch-based carbon fibers (HSPCNF) featuring a multichannel structure. By precisely controlling precursor solution composition and carbonization temperature, we optimized the microstructure, yielding coexisting short-range ordered graphite microcrystals and disordered carbon, effectively enhancing electronic conductivity and lithium-ion diffusion. The multichannel structure significantly increases electrochemical active sites and facilitates electrolyte infiltration. HSPCNF-600 achieved a high initial reversible capacity of 1020.3 mAh g⁻¹ at 0.1 A g⁻¹. More notably, it maintains 97.7 % capacity after 2000 cycles at 1 A g⁻¹ and delivers a considerable reversible capacity of 190.1 mAh g⁻¹ with 93.4 % capacity retention even after 10000 cycles at 10 A g⁻¹. This study provides a novel strategy for advanced anode material design and high-value utilization of coal-derived carbon.