2D transition-metal carbides and nitrides, named MXenes, are promising materials for energy storage, but suffer from aggregation and restacking of the 2D nanosheets, which limits their electrochemical performance. In order to overcome this problem and realize the full potential of MXene nanosheets, a 3D MXene foam with developed porous structure is established via a simple sulfur-template method, which is freestanding, flexible, and highly conductive, and can be directly used as the electrode in lithium-ion batteries. The 3D porous architecture of the MXene foam offers massive active sites to enhance the lithium storage capacity. Moreover, its foam structure facilitates electrolyte infiltration for fast Li+ transfer. As a result, this flexible 3D porous MXene foam exhibits significantly enhanced capacity of 455.5 mAh g-1 at 50 mA g-1 , excellent rate performance (101 mAh g-1 at 18 A g-1 ), and superior ultralong-term cycle stability (220 mAh g-1 at 1 A g-1 after 3500 cycles). This work not only demonstrates the great superiority of the 3D porous MXene foam but also proposes the sulfur-template method for controllable constructing of the 3D foam from 2D nanosheets at a relatively low temperature.

中文翻译：

---

适用于高性能锂离子电池的柔性3D多孔MXene泡沫。

2D过渡金属碳化物和氮化物（称为MXenes）是有前途的能量存储材料，但由于2D纳米片的聚集和重新堆叠而受到限制，这限制了它们的电化学性能。为了克服这个问题并实现MXene纳米片的全部潜力，通过简单的硫模板法建立了具有发达的多孔结构的3D MXene泡沫，该方法具有独立性，柔韧性和高导电性，可以直接用作MXene纳米片。锂离子电池中的电极。MXene泡沫的3D多孔结构可提供大量的活性位点，以增强锂的储存能力。此外，其泡沫结构有助于电解质渗透，从而实现Li +的快速转移。结果，这种柔软的3D多孔MXene泡沫在50 mA g-1时显示出455.5 mAh g-1的显着增强的容量，极好的速率性能（在18 A g-1时为101 mAh g-1），以及出色的超长期循环稳定性（在3500次循环后在1 A g-1时为220 mAh g-1）。这项工作不仅证明了3D多孔MXene泡沫的巨大优势，而且提出了在相对较低的温度下可控地从2D纳米片构造3D泡沫的硫模板方法。