Highly Conductive Hierarchical TiO<sub>2</sub> Micro‐Sheet Enables Thick Electrodes in Sodium Storage
Chunting Wang, Qian Yao, Mingyue Wang, Zheng Cheng, Nana Wang, Zhongchao Bai, Jian Yang, Shi Xue Dou, Huakun Liu
Abstract
Abstract TiO 2 ‐based materials are considered to be the promising anodes of sodium‐ion batteries (NIBs) because of their high safety and good stability. However, their low specific capacity and high safety operating voltage plateau impose a severe challenge for high energy density batteries. Herein, interconnected micro‐sheets consisting of carbon nanotubes and sulfur doped TiO 2 (CNT/S‐TiO 2 ) are synthesized via an ultrasonic process and subsequent calcination, enabling the fabrication of high‐performance material. The utilization of SWCNT overcomes the structure instabilities during electrode preparation of thick electrodes. The incorporation of SWCNT and sulfur dopants in the CNT/S‐TiO 2 composite not only enhances conductivity but also improves ion transport dynamics, resulting in rapid charge delivery and high specific capacity at the thick electrode level. Consequently, CNT/S‐TiO 2 demonstrates excellent rate performance (from 0.3 to 15 C, with 72.4% capacity retention) and long cycling stability (10000 cycles at a load of 1.96 mg cm −2 ). More importantly, the high S‐TiO 2 content (90%) in the thick electrode (21.2 mg cm −2 ) achieves a high areal capacity retention of 3.4 mA h cm −2 after 100 cycles, which surpasses the actual application requirements.