Three-dimensional hierarchical urchin-like TiNb₂O₇ microspheres encapsulated in N-doped carbon for high-rate lithium...

Wadsley-Roth phase TiNb₂O₇ has been known as a potential anode material in high-power lithium-ion batteries (LIBs) owing to its enhanced safety, reliable cycling performance, and substantial theoretical capacity. However, its commercial application is restricted by poor electronic conductivity and slow Li-ion migration kinetics. Herein, we have developed urchin-structured TiNb₂O₇ microspheres with an ultrathin N-doped carbon coating through a two-step hydrothermal and polydopamine carbonization process. When used as LIBs anode, the TiNb₂O₇@N-C composite demonstrates a remarkable rate capability of 216 mAh g^-1 at 30 C and a durable lifespan with a capacity retention of 89 % after 500 cycles (10 C). In addition, by pairing with LiNi_0.5Mn_1.5O₄ cathode, the full cell also reveals outstanding electrochemical performance even at high rates. The enhanced lithium storage capabilities of TiNb₂O₇@N-C can be credited to the integrated superiorities of the multilevel urchin-like architecture and the external conductive layer, which shortens the Li⁺/electron transfer paths, buffer the volume fluctuations of active substance, and improves the overall conductivity of the composite electrode.