Sodium-Ion Intercalation Mechanism in MXene Nanosheets
Sodium-Ion Intercalation Mechanism in MXene Nanosheets
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DOI：
10.1021/acsnano.5b06958
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发表时间：
2016-03-01
期刊：
影响因子：
17.1
通讯作者：
Yamada, Atsuo
中科院分区：
文献类型：
--
作者：
Kajiyama, Satoshi;Szabova, Lucie;Yamada, Atsuo
MXene, a family of layered compounds consisting of nanosheets, is emerging as an electrode material for various electrochemical energy storage devices including supercapacitors, lithium-ion batteries, and sodium-ion batteries. However, the mechanism of its electrochemical reaction is not yet fully understood. Herein, using solid-state Na-23 magic angle spinning NMR and density functional theory calculation, we reveal that MXene Ti3C2Tx in a nonaqueous Na+ electrolyte exhibits reversible Na+ intercalation/deintercalation into the interlayer space. Detailed analyses demonstrate that Ti3C2Tx undergoes expansion of the interlayer distance during the first sodiation, whereby desolvated Na+ is intercalated/deintercalated reversibly. The interlayer distance is maintained during the whole sodiation/desodiation process due to the pillaring effect of trapped Na+ and the swelling effect of penetrated solvent molecules between the Ti3C2Tx sheets. Since Na+ intercalation/deintercalation during the electrochemical reaction is not accompanied by any substantial structural change, Ti3C2Tx shows good capacity retention over 100 cycles as well as excellent rate capability.
