It is highly desirable to design and synthesize two-dimensional nanostructured electrode materials with high electrical conductivity, large electrolyte-accessible surface area and more exposed active sites for energy storage applications. Herein, MXene/CoAl-LDH heterostructure has been prepared through electrostatic ordered hetero-assembly of monolayer MXene and edge-rich CoAl-LDH nanosheets in a face-to-face manner on molecular-scale for supercapacitor applications. Benefiting from the unique structure, strong interfacial interaction and synergistic effects between MXene and CoAl-LDH nanosheets, the electrical conductivity and exposed electrolyte-accessible active sites are significantly enhanced. The as-prepared MXene/CoAl-LDH-80% (ML-80) film exhibits high volumetric capacity of 2472 C cm⁻³ in 3 M KOH electrolyte with high rate capability of 70.6% at 20 A g⁻¹. Notably, to the best of our knowledge, the high volumetric capacity is the highest among other previously reported values for supercapacitors in aqueous electrolytes. Furthermore, our asymmetric supercapacitor device fabricated with ML-80 and MXene/graphene composite as cathode and anode, respectively, exhibits impressive volumetric energy density of 85.4 Wh L⁻¹ with impressive cycling stability of 94.4% retention ratio after 30,000 continuous charge/discharge cycles.

设计和合成具有高电导率，较大的电解质可及表面积和更多暴露的活性位点的二维纳米结构电极材料用于储能应用是非常需要的。本文中，MXene / CoAl-LDH异质结构是通过单层MXene和边缘富集的CoAl-LDH纳米片的静电有序异质组装以面对面的方式在分子尺度上以超级电容器应用制备的。得益于MXene和CoAl-LDH纳米片之间的独特结构，强大的界面相互作用和协同效应，显着增强了电导率和暴露的电解质可及的活性位。所制备的MXene / CoAl-LDH-80％（ML-80）膜表现出2472 C cm ^-3的高体积容量在3 M KOH电解质中的溶液在20 A g ^-1下具有70.6％的高倍率能力。值得注意的是，据我们所知，高容量容量是先前报道的水性电解质中超级电容器的其他所有值中最高的。此外，我们的分别由ML-80和MXene /石墨烯复合材料制成的非对称超级电容器器件作为阴极和阳极，其惊人的体积能量密度为85.4 Wh L ^-1，在30,000次连续充电/放电循环后，其循环稳定性达到了94.4％的惊人的保持率。 。