Ding Changsheng, Nohira Toshiyuki, Hagiwara Rika
Graduate School of Energy Science, Kyoto University, Sakyo-ku, Kyoto 606-8501, Japan.
Institute of Advanced Energy, Kyoto University, Uji 611-0011, Japan.
Phys Chem Chem Phys. 2016 Nov 9;18(44):30770-30776. doi: 10.1039/c6cp05944a.
TiO is widely investigated as a negative electrode for lithium-ion batteries. In sodium-ion batteries, however, the sodiation-desodiation mechanism of TiO is still unclear. Here, we report a new sodiation-desodiation mechanism for an anatase TiO/C electrode in an ionic liquid electrolyte at 90 °C, where it shows a high reversible capacity of 278 mA h g. During the first charge process, TiO reacts with Na ions to form a NaTiTiO solid solution. During the first discharge process, the solid solution converts into a mixture of TiO, NaTiO, and TiO, with the former two being X-ray amorphous. In the subsequent cycle, the mixture acts as the active material, reversibly reacting with Na ions to re-form the NaTiTiO solid solution. This mechanism, which has not been reported for Na or Li ion insertion-extraction in anatase TiO, can help understand this promising electrode material and develop safe sodium-ion batteries with high energy density.
二氧化钛（TiO）作为锂离子电池的负极材料已得到广泛研究。然而，在钠离子电池中，TiO的 sodiation - desodiation 机制仍不清楚。在此，我们报道了一种在90°C的离子液体电解质中锐钛矿型TiO/C电极的新型sodiation - desodiation机制，该电极在此条件下展现出278 mA h g的高可逆容量。在首次充电过程中，TiO与Na离子反应形成NaTiTiO固溶体。在首次放电过程中，该固溶体转变为TiO、NaTiO和TiO的混合物，前两者为X射线非晶态。在随后的循环中，该混合物作为活性材料，与Na离子可逆反应以重新形成NaTiTiO固溶体。这种在锐钛矿型TiO中未被报道的Na或Li离子嵌入 - 脱出机制，有助于理解这种有前景的电极材料，并开发具有高能量密度的安全钠离子电池。
