Ionic liquid‐induced ultrathin and uniform N‐doped carbon‐wrapped T‐Nb ₂ O ₅ microsphere anode for high‐performance lithium‐ion battery

Abstract

Abstract Orthorhombic‐phase Nb 2 O 5 (T‐Nb 2 O 5 ) has been widely investigated as an intercalation anode material for Li‐ion batteries due to the larger interplanar lattice spacing and high safety. However, its applications are limited by the intrinsic low electric conductivity. Herein, an ultrathin N‐doped carbon‐coating layer was constructed on porous T‐Nb 2 O 5 microspheres uniformly via a convenient thermal treatment method with ionic liquid as a carbon precursor. The synthesized T‐Nb 2 O 5 @N–C exhibits significantly enhanced rate capability (155.5 mAh·g –1 at 20C) than initial T‐Nb 2 O 5 (110.2 mAh·g –1 at 20C). Besides, T‐Nb 2 O 5 @N–C shows ultralong cycle life, with only a 0.02% decrease in the capacity per cycle at a high current density of 10C. The corresponding electrochemical tests show that the preferable rate capability of T‐Nb 2 O 5 @N–C electrode is attributed to the increased electronic conductivity and pseudocapacitance contribution induced by ultrathin surface N‐doped carbon layer. On the other hand, the mesoporous structure of T‐Nb 2 O 5 @N–C ensures fast Li + diffusion dynamics and electrolyte penetration. Furthermore, T‐Nb 2 O 5 @N–C also performs well in a LiNi 0.5 Mn 0.3 Co 0.2 O 4 ||T‐Nb 2 O 5 @N–C full cell. This work provides a facile method to construct integrated anode materials for potential applications in lithium‐ion batteries.