MXenes have excellent electrochemical performance due to their remarkable electrical conductivity and abundant surface functional groups. However, the smaller interlayer spacing and self-stacking limit their practical applications. Herein, the Ba2+ ions pillared Ti₃C₂ MXene (Ba2+–Ti₃C2) with enlarged interlayer spacing has been successfully fabricated by electrostatic self-assembly. The pillared Ba2+ ions between Ti₃C₂ layers can enlarge interlayer spacing, increase specific surface area, expose more active sites and provide open ions transfer channels due to its pillaring effects on the layered structure of Ti₃C₂. The Ba2+–Ti₃C₂ exhibits a higher specific capacitance (168F⋅g−1 at 0.2A⋅g−1) than pure Ti₃C₂ (123 F⋅g−1 at 0.2A⋅g−1) and outstanding cycle performance, which remains at 164 F⋅g−1 after 1100 cycles at 1A⋅g−1. The Ba2+–Ti₃C₂//AC asymmetric supercapacitor achieved a high power density of 1140W⋅Kg−1 as well as long cycle stability with capacitance retention of 86.35% at a current density of 1A⋅g−1 after 4000 cycles. The results demonstrate that expeading interlayer spacing can obviously enhance and optimize the supercapactive performance of MXenes, providing an idea to design the 2D energy storage materials with large interlayer spacing and high rate capability.

中文翻译：

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Ba2+柱状Ti3C2的自组装与扩大的层间间距以提高超级电容性能

MXenes由于其卓越的导电性和丰富的表面官能团而具有优异的电化学性能。然而，较小的层间距和自堆叠限制了它们的实际应用。在此，巴2+离子柱 Ti ₃ C ₂ MXene (Ba2+–Ti ₃ C2)通过静电自组装成功地制造了具有更大层间距的材料。有柱子的巴2+_{Ti 3} C ₂层之间的离子由于其对Ti ₃ C ₂层状结构的柱状作用，可以扩大层间距，增加比表面积，暴露更多的活性位点并提供开放的离子传输通道。巴2+–Ti ₃ C ₂表现出更高的比电容（168F⋅G-1在 0.2一种⋅G-1)比纯 Ti ₃ C ₂ (123 F⋅G-1在 0.2一种⋅G-1)和出色的循环性能，保持在 164 F⋅G-11100 次循环后 1一种⋅G-1. 巴2+–Ti ₃ C ₂ //AC非对称超级电容器实现了1140的高功率密度W⋅公斤-1以及长循环稳定性，在电流密度为 1 时电容保持率为 86.35%一种⋅G-14000 次循环后。结果表明，扩大层间距可以明显增强和优化MXenes的超级电容性能，为设计具有大层间距和高倍率能力的二维储能材料提供了思路。