Ultrafast and Highly Efficient Sodium Ion Storage in Manganese‐Based Tunnel‐Structured Cathode
Hanghui Liu, Ruijie Feng, Fiaz Hussain, Yanchen Liu, Liuqi Wang, Q. Fan, Mingzhu Ni, Ce Qiu, Mingqing Sun, Jinshi Wang, Tong Wang, Zhengyi Shi, Xiaohui Zhu, Hui Xia
Abstract
Abstract Na 0.44 MnO 2 with tunnel structure is considered a promising low‐cost cathode material for sodium‐ion batteries. However, the sluggish Na + transport kinetics and low initial Coulombic efficiency restrict its practical applications in rechargeable sodium‐ion batteries. Herein, a manganese‐based tunnel‐structured cathode with high rate capability and high initial Coulombic efficiency is prepared by niobium doping and sodium compensation. Via materials characterizations and theoretical calculations, it is demonstrated that a proper amount of niobium doping in tunnel structure can effectively improve its structural stability and charge transport kinetics, resulting in outstanding rate capability (76.6% capacity retained from 0.5 to 30 C) and superior cycling performance (82.3% capacity retention after 800 cycles at 5 C) for the optimized Nb‐doped Na 0.44 MnO 2 cathode (Na 0.44 Mn 0.98 Nb 0.02 O 2 ). Furthermore, NaCrO 2 is added into the Na 0.44 Mn 0.98 Nb 0.02 O 2 cathode as a self‐sacrificing sodium compensation additive, and a high initial Coulombic efficiency close to 100% is achieved for the composite cathode. This work establishes a facile strategy to design advanced manganese‐based cathode materials for large‐scale energy storage applications.