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 Ti₃C₂T _x MXene, the obtained PDA300/Ti₃C₂T _x 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 Ti₃C₂T _x substrate with a unique two-dimensional nanostructure. This work will provide new opportunities for the expansion of high-performance organic anodes for LIBs.