Fabrication of carboxylated tubular carbon nanofibers as anode electrodes for high-performance lithium‐ion batteries

A novel carboxyl-modified tubular carbon nanofibers (CMTCFs) are prepared by modifying carboxyl groups on the tubular polymer nanofibers (TPFs) using carbonization and liquid phase oxidation technology. The carboxyl content on nanofibers is effectively controlled by adjusting the oxidation time. The content of the carboxyl group increases and the morphology of nanofibers remains well with an extension of functionalization time. Four kinds of CMTCFs with different carboxyl content are obtained. The obtained samples are systematically characterized and their electrochemical performance is investigated. The influence of carboxyl content on the electrochemical property of electrode materials is revealed. Results show that the proper carboxyl content on CMTCFs (1.3987 mmol g–1, CMTCFs-1) can effectively balance the relationship between capacity and reaction kinetics. The optimized CMTCFs-1 electrode exhibits a high reversible capacity of 588.5 mAh g–1 at a current density of 1000 mA g–1 after 500 cycles. Compared to the second cycle, the reversible capacity is only reduced by 10%. Moreover, even at a high current density of 3000 mA g–1, the average reversible capacity is 354.73 mAh g–1.