过渡金属Zn²⁺表面修饰Ti₃C₂T_x Mxene构筑高性能超级电容器负极

Surface Modification of Ti₃C₂Tₓ MXene with Transition Metal Zn²⁺ for Constructing High-Performance Supercapacitor Negative Electrodes

摘要: Ti₃C₂T_x Mxene因其独特的理化特性，被广泛认为是高性能超级电容器的有前景的负极材料。然而，其储能潜力受限于固有缺陷，如层间堆叠问题及存在不利的-F表面端基。本研究报道了一种调控并提升Ti₃C₂T_x电化学性能的表面修饰策略。采用离子交换法将Zn²⁺离子嵌入Ti₃C₂T_x的层间间隙，有效扩展了离子扩散路径并暴露更多活性位点。经此结构调控后，所得Ti₃C₂T_x-Zn薄膜电极在1 A·g⁻¹的电流密度下比电容高达361 F·g⁻¹，较原始Ti₃C₂T_x薄膜电极(242 F·g⁻¹)提升1.43倍；电流密度升至20 A·g⁻¹时电容保持率为85%，10 A·g⁻¹电流密度下1万次循环后容量保持率高达99.8%，展现出优异倍率性能与良好的循环稳定性。本研究通过层间工程优化Ti₃C₂T_x表面组分与结构，为过渡金属离子表面修饰MXene材料在超级电容器中的应用提供了科学依据与技术参考。

Abstract: Ti₃C₂T_x Mxene, with its distinctive physicochemical properties, is widely regarded as a promising anode material for high-performance supercapacitors. However, its energy storage potential is limited by inherent shortcomings, such as interlayer restacking and the presence of unfavorable –F surface terminations. This study reports a surface modification strategy aimed at regulating and improving the electrochemical performance of Ti₃C₂T_x. Through an ion-exchange approach, Zn²⁺ ions were intercalated into the interlayer gaps of Ti₃C₂T_x, effectively enlarging the ion diffusion pathways and exposing more active sites. After this structural modification, the resulting Ti₃C₂T_x-Zn film electrode delivered a high specific capacitance of 361  F·g⁻¹ at a current density of 1  A·g⁻¹, which is 1.43 times that of the pristine Ti3C2Tx film electrode (242  F·g⁻¹). The electrode also exhibited superior rate capability with 85% capacitance retention at 20  A·g⁻¹, as well as excellent cycling stability with 99.8% capacitance retention after 10,000 cycles at 10  A·g⁻¹. This work demonstrates that interlayer engineering can effectively optimize the surface composition and structure of Ti₃C₂T_x, providing scientific and technical insights into the application of transition-metal-ion surface modification of MXene materials in supercapacitors.