Owing to their unique structural and electronic characteristics, MXenes are considered to be the most potential anode materials for Li-ion capacitors (LICs). However, the stacking of layers, which would inevitably lead to the reduction of active sites and the sluggish lithiation kinetics, highly inhibits their electrochemical performance. Herein, to overcome the stacking and simultaneously improve the reversible capacity and cycle stability of MXenes, a kind of Ti₃C₂ with Sn⁴⁺ intercalated between the layers and amorphous SnO₂ layer modified (AS-Ti₃C₂) is proposed. The intercalated Sn⁴⁺ between the layers not only could facilitate Li-ion diffusion kinetics by expanding the interlayer spacing but also provide additional capacity by interlayered-alloying reactions. Meanwhile, the in-situ formed amorphous SnO₂ modified layers could offer abundant channels for fast Li-ion diffusion and provide a new interface between electrolyte and electrode to lower the energy barrier for interfacial charge transfer. Benefit from the synergy effects of faster ion diffusion kinetics and lower charge transfer barrier, AS-Ti₃C₂ delivers much improved rate performance and enhanced cycle stability in Li-ion half-cells, maintaining 91.5% capacity retention (after 1500 cycles @2000 mA g^-1). Moreover, LICs assembled by AS-Ti₃C₂ anodes and activated carbon (AC) cathodes deliver superior electrochemical properties including long cycle life (82.1% after 4000 cycles @2000 mA g^-1), high energy (105.7 Wh kg^-1) and power (8000 W kg^-1) densities. Our findings reveal that the interlayered and interfacial co-modification is feasible to improve the properties of MXenes.

由于其独特的结构和电子特性，MXene被认为是锂离子电容器（LIC）最有潜力的阳极材料。然而，层的堆叠将不可避免地导致活性部位的减少和迟缓的锂化动力学，这极大地抑制了它们的电化学性能。在本文中，为了克服堆叠并且同时提高MXene的可逆容量和循环稳定性，提出了一种在层之间插入有Sn ⁴⁺的Ti ₃ C ₂和改性的非晶SnO ₂层（AS-Ti ₃ C ₂）。插层Sn ⁴⁺层之间的相互作用不仅可以通过扩大层间间距来促进锂离子扩散动力学，而且还可以通过层间合金化反应提供额外的容量。同时，原位形成的非晶态SnO ₂改性层可为快速的锂离子扩散提供丰富的通道，并在电解质和电极之间提供新的界面，从而降低界面电荷转移的能垒。得益于更快的离子扩散动力学和更低的电荷转移势垒的协同效应，AS-Ti ₃ C ₂大大提高了锂离子半电池的倍率性能并增强了循环稳定性，保持了91.5％的容量保持率（1500次@ 2000后） mA g ^-1）。此外，由AS-Ti ₃组装的LICC ₂阳极和活性炭（AC）阴极具有出色的电化学性能，包括长循环寿命（2000 mA g ^-1时，在4000次循环后为82.1％），高能量（105.7 Wh kg ^-1）和功率（8000 W kg ^-1）密度。我们的发现表明，层间和界面共改性对于改善MXene的性能是可行的。