Centre for Clean Environment and Energy, and Griffith School of Environment, Griffith University, Gold Coast, QLD 4222, Australia.
ACS Appl Mater Interfaces. 2013 Feb;5(3):1108-12. doi: 10.1021/am302907v. Epub 2013 Feb 1.
Sodium hexatitanates (Na(2)Ti(6)O(13)) with tunnelled structures have been experimentally proposed to be good candidates for anode materials of lithium ion batteries because of their low potential, small shape transformation, and good reversibility. The understanding of the properties of this lithiated titanate is significant for their development. To this end, the first-principle calculations were performed to investigate the interaction between Li ions and Na(2)Ti(6)O(13) at the atomic level. After structural optimization with various Li:Ti ratios, the Li ions are found to energetically prefer to stay at the small rhombic tunnels of Na(2)Ti(6)O(13), where the diffusion energy barrier of Li ions is also lower. Such preference is determined by the chemical environment around Li ions. Our theoretical intercalation potential and volume change on the basis of the optimized atomic structures agree with the experimental observations. The analysis of the electronic properties reveals the Burstein-Moss effect in lithiated Na(2)Ti(6)O(13) due to the heavy n-type doping. Such materials possess high conductivity, which can benefit their applications in photoelectrochemical or electrochemical areas.
具有隧道结构的六钛酸钠（Na2Ti6O13）由于其低电位、小形状转变和良好的可逆性，被实验提出是锂离子电池阳极材料的候选材料。了解这种嵌锂钛酸盐的性质对于其发展至关重要。为此，进行了第一性原理计算，以在原子水平上研究锂离子与 Na2Ti6O13 之间的相互作用。在对各种 Li:Ti 比进行结构优化后，发现锂离子在能量上优先存在于 Na2Ti6O13 的小菱形隧道中，其中锂离子的扩散能垒也较低。这种偏好是由锂离子周围的化学环境决定的。我们的理论插层势和基于优化原子结构的体积变化与实验观察结果一致。电子性质的分析揭示了由于重 n 型掺杂，嵌锂 Na2Ti6O13 中的 Burstein-Moss 效应。这种材料具有高导电性，这有利于它们在光电化学或电化学领域的应用。
