Tubular carbon nanofibers loaded with different MnO₂: Preparation and electrochemical performance

A kind of novel composite materials are fabricated via growing worm-like MnO2 on acidified tubular carbon nanofibers (CMTCFs@MnO2). The preparation strategies include confined hyper-crosslinking, surface carboxylation modification, and in-situ redox. Four CMTCFs@MnO2 with different MnO2 spatial distribution density are prepared by adjusting the ratio of potassium permanganate and CMTCFs. When used as anode materials for lithium-ion batteries (LIBs), the proper worm-like MnO2 coating density (CMTCFs@MnO2-3) can effectively balance the relationship between the maximum capacity and electron transport. Thus, the optimized CMTCFs@MnO2-3 electrode delivers large reversible capacity of 1147.4 mAh g–1 at 500 mA g–1 after 400 cycles. Even at a high current density of 1000 mA g–1, a remarkable reversible capacity of 1013.5 mAh g–1 is still maintained after 500 cycles. Moreover, the activation behavior of optimized CMTCFs@MnO2-3 electrode during high current density test makes it exhibit enhanced rate performance. Compared with the initial rate performance, the average specific capacity of CMTCFs@MnO2-3 electrode increases by a maximum of 87% after long-term cycles at 1000 mA g–1.