Self-improving anodes for lithium-ion batteries: continuous interlamellar spacing expansion induced capacity increase in polydopamine-derived nitrogen-doped carbon tubes during cycling

Polydopamine-derived nitrogen-doped carbon has attracted tremendous attention owing to its huge success in improving the electrochemical properties of high-capacity lithium-storage materials (such as S, Si and Sn). In this study, we first demonstrate its excellent and durable lithium-storage capability by designing a one-dimensional hollow structure through a template-assisted method. The polydopamine-derived nitrogen-doped carbon tubes show high specific capacity, excellent rate capability and robust durability. Interestingly, the capacity gradually increased from 587 to 1103 mA h g−1 upon the 500th cycle at 500 mA g−1. The self-improvement in capacity stems from the continuous interlamellar spacing expansion of the graphene-like carbon layers as confirmed by HR-TEM. Our work offers a new insight into the electrochemical behaviour of polydopamine-derived carbon and is beneficial for its future utilization in high-performance lithium-ion battery electrode materials.