Highly Conductive Hierarchical TiO₂ Micro‐Sheet Enables Thick Electrodes in Sodium Storage

Abstract

TiO2‐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 TiO2 (CNT/S‐TiO2) 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‐TiO2 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‐TiO2 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‐TiO2 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.