MXene electrode material performance in magnesium batteries
Two-dimensional Ti3C2Tx MXene materials have attracted attention due to their excellent electrical conductivity and high volume capacity in supercapacitors, lithium-ion batteries, and sodium-ion batteries. Magnesium-ion batteries have been developed because of their low cost, good safety performance, and large theoretical volume energy density. It has become one of the most promising substitutes for lithium-ion batteries. The theory predicts that pure Ti3C2 has a strong Mg2+ storage performance. However, to date, it has not been possible to synthesize MXene with no surface functional groups. Previous studies have shown that divalent magnesium The ions cannot be reversibly embedded in the Ti3C2Tx, resulting in almost no Mg storage capacity for the Ti3C2Tx MXene. Therefore, it is necessary to explore suitable experimental methods to open the MXene magnesium ion storage performance.
Recently, the research team of Lanzhou Institute of Chemical Physics, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, used the pre-inserted cationic surfactant cetyltrimethylammonium bromide (CTAB) method to change the electronic properties of MXene, which enabled Ti3C2Tx MXene to exhibit higher magnesium content. Ionic storage capacity. The researchers systematically tested the sample: Anionic surfactant sodium lauryl sulfate SDS and cationic surfactants with the same alkyl chain length dodecyltrimethylammonium bromide DTAB were compared. It shows that surfactants increase the interlayer spacing of MXene, but only the cationic surfactant promotes the storage of Mg2+ in MXene. XPS and density functional theory calculations show that the embedded CTA+ cations reduce the Mg2+ on the surface of MXene. Diffusion barriers, which in turn greatly enhance the reversible intercalation/deintercalation performance of Mg2+ in the MXene layer. Studies have shown that magnesium batteries with MXene as the positive electrode exhibit a high volume of 300 mAh·cm-3 at a current density of 50 mA·g-1. Specific capacity and excellent rate characteristics. This study gives MXene another new application in the field of electrochemical energy storage. Magnesium battery positive electrode material provides a new choice.
The results of this study were recently published online on ACS Nano.
