Superlithiated Polydopamine Derivative for High-Capacity and High-Rate Anode for Lithium-Ion Batteries

Organic electrode materials, with low-cost synthesis and environmental friendliness, have gained significant research interest in lithium-ion batteries (LIBs). Polydopamine (PDA), as a bioderived organic electrode material, exhibits a low capacity of ∼100 mAh g–1, greatly limiting the practical application in LIBs. In this work, we find that a simple heat treatment at 300 °C can endow PDA-derived material (PDA300) with superior electrochemical performance. The obtained PDA300 electrode exhibits an ultrahigh capacity of 977 mAh g–1 at 50 mA g–1. Further combining the PDA300 with highly conductive Ti3C2Tx MXene, the obtained PDA300/Ti3C2Tx composite is demonstrated by high capacity (1190 mAh g–1, 50 mA g–1), excellent rate capability (remaining 552 mAh g–1 at 5 A g–1), and good cycling stability (82% retaining after 1000 cycles). The outstanding lithium storage performance is highly associated with the superlithiation process of the unsaturated carbon–carbon bonds in the PDA derivative and the introduction of the highly conductive Ti3C2Tx substrate with a unique two-dimensional nanostructure. This work will provide new opportunities for the expansion of high-performance organic anodes for LIBs.