With the properties of high theoretical capacity and excellent structural stability, TiO₂ has been widely studied as anode material for sodium-ion batteries (SIBs). In this work, a composite structure of ultra-small TiO₂ nanoparticles embedded in carbon nanosheets (TCNS) is obtained by annealing polyvinylpyrrolidone coated Zn-Ti layered double hydroxide under inert atmosphere, with zinc species removed by hydrochloric acid. As sodium-ion battery anode, the resultant TCNS shows a high reversible capacity of 271.2 mAh g⁻¹ at 50 mA g⁻¹ and considerable cycling stability (maintaining 196.7 mAh g⁻¹ after 2000 cycles at 2 A g⁻¹). Ex-situ XRD and TEM investigations clearly illustrate the structure changes of anatase during the sodium storage process. Specifically, ultra-small TiO₂ nanoparticles in TCNS show obvious crystal distortion as triggered by the initial insertion of sodium ions, with the reversible sodium storage happening at the (101) active plane of anatase. As experimentally and theoretically evidenced, the twisted crystal structure is maintained in the subsequent cycles, which can effectively promote the sodium diffusion rate in anatase, resulting in the excellent rate and cycle performances of TCNS anode. This study provides informative guidance to explore high-performance TiO₂ anodes for SIBs, with novel insights into the sodium ion insertion/extraction mechanism comprehensively elucidated during reversible sodium storage process.

具有高理论容量和优异的结构稳定性的特性，TiO ₂作为钠离子电池（SIB）的负极材料已被广泛研究。在这项工作中，通过在惰性气氛下对聚乙烯吡咯烷酮涂层的Zn-Ti层状双氢氧化物进行退火，并用盐酸除去锌物质，从而获得了嵌入碳纳米片（TCNS）中的超小TiO ₂纳米粒子的复合结构。作为钠离子电池负极，将所得的TCN节目271.2毫安g的高可逆容量^-1在50mA克^-1和相当大的循环稳定性（保持196.7毫安克^-1以2A克2000次循环之后^-1）。异位XRD和TEM研究清楚地说明了钠储存过程中锐钛矿的结构变化。具体而言，TCNS中的超小TiO ₂纳米颗粒显示出明显的晶体变形，这是由钠离子的初始插入触发的，可逆的钠存储发生在锐钛矿的（101）活性平面上。从实验和理论上证明，在随后的循环中保持了扭曲的晶体结构，这可以有效地促进锐钛矿中钠的扩散速率，从而使TCNS阳极具有出色的速率和循环性能。该研究为探索高性能TiO ₂提供了有益的指导。 用于SIB的阳极，对可逆钠存储过程中钠离子的插入/萃取机理有新的见解。