JCIS: N/S co-doped V-based MXene high-performance lithium storage

As a new class of two-dimensional materials, MXenes has received continuous and extensive attention since it was discovered in 2011. Thanks to its metal conductivity, mechanical stability and electrochemical activity, MXene-based electrode materials have broad application prospects in the field of energy storage. Up to now, V2CTxMXene, as a representative of the more extensive research in the MXene material system, has attracted the interest of many researchers due to its higher theoretical lithium storage capacity (~940 mAh g-1). However, the capacity of the experimentally obtained V2CTx MXene still has a large gap compared with its theoretical capacity. This is due to its layer stacking and accumulation, resulting in poor ion transmission between the electrode and the electrolyte. Therefore, research on the high-performance lithium storage V2CTx MXene is very important.

Recently, Professor Pan Likuns team from East China Normal University published a research paper titled Nitrogen and sulfur co-doped vanadium carbide MXene for highly reversible lithium-ion storage in the internationally renowned academic journal Journal of Colloid and Interface Science, reporting a kind of N, S co-doped V2CTx MXene has excellent lithium storage performance. At a current density of 0.1 A g-1, a reversible capacity of 590 mAh g-1 can be generated after 100 cycles.

Figure 1. Synthesis diagram of N and S co-doped V2CTxMXene.









Figure 2. SEM characterization of N and S co-doped V2CTxMXene.









Figure 3. Physical composition characterization of N and S co-doped V2CTx MXene.









Figure 4. Electrochemical performance test of V2CTx MXene co-doped with N and S.











Figure 5. Electrochemical performance test of N and S co-doped V2CTx MXene.









Figure 6. Kinetic analysis of N and S co-doped V2CTx MXene.









Figure 7. N, S co-doped V2CTx MXene energy storage mechanism analysis









Figure 8. Ex-situ XPS spectra of N and S co-doped V2CTx MXene under different charge and discharge conditions.







The N, S co-doped V2CTx MXene prepared in this paper is achieved by one-step calcination directly with thiourea. Compared with other V2CTx MXene lithium battery anode materials, it has higher reversible capacity, better rate performance and better long-term cycle stability. The performance improvement can be mainly attributed to the synergistic effect brought about by the co-doping of N and S, which improves the electrochemical reaction activity and charge transport ability, thereby enhancing the rapid diffusion of ions and electrons. In addition, the co-doping of N and S expands the interlayer spacing, which can accommodate more lithium ions and promote the dynamics of ion transport during the process of lithium insertion/delithiation.

Literature link:

https://doi.org/10.1016/j.jcis.2020.12.044


Source: MXene Frontier

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