基于Cr³⁺插层调控Ti₃C₂T_x Mxene性能用于超级电容器负极

Cr³⁺ Intercalation-Mediated Performance Tuning of Ti₃C₂T_x MXene as Anode Material for Supercapacitors

摘要: Ti₃C₂T_x MXene是能源存储领域的研究热点之一，在超级电容器负极材料领域拥有巨大应用潜力，然而Ti₃C₂T_x MXene存在表面活性位点不足、有害官能团阻碍离子传输及循环稳定性欠佳的问题。本文利用过渡金属离子插层调控策略将Cr³⁺引入，有效丰富Ti₃C₂T_x-Cr薄膜电极表面金属原子活性中心，同时Cr³⁺占据Ti格位或空位增强结构稳定性，实现表面官能团调控与结构优化，从而得到高性能Ti₃C₂T_x-Cr薄膜电极。得益于表面改性与结构优化，Ti₃C₂T_x-Cr薄膜电极在1 A·g⁻¹的电流密度下比电容高达334 F·g⁻¹，较原始Ti₃C₂T_x薄膜电极(247 F·g⁻¹)提升1.35倍；电流密度升至20 A·g⁻¹时电容保持率为91%，10 A·g⁻¹电流密度下30,000次循环后容量保持率高达99.3%，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，为过渡金属离子插层改性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 is one of the research hotspots in the field of energy storage and holds great application potential as a negative electrode material for supercapacitors. However, Ti₃C₂T_x MXene suffers from inherent drawbacks such as insufficient surface active sites, harmful functional groups hindering ion transport, and poor cycling stability. In this work, we employed a transition metal ion intercalation regulation strategy to introduce Cr³⁺ into Ti₃C₂T_x, which effectively enriched the surface metal atom active sites of the Ti₃C₂T_x-Cr film electrode. Meanwhile, Cr³⁺ occupied Ti lattice sites or vacancies to enhance structural stability, enabling the regulation of surface functional groups and structural optimization, thus yielding a high-performance Ti₃C₂T_x-Cr film electrode. Benefiting from surface modification and structural optimization, the Ti₃C₂T_x-Cr film electrode delivered a high specific capacitance of 334 F·g⁻¹ at a current density of 1 A·g⁻¹, which is 1.35 times higher than that of the pristine Ti₃C₂T_x film electrode (247 F·g⁻¹). When the current density increased to 20 A·g⁻¹, the capacitance retention rate reached 91%, and after 30,000 cycles at 10 A·g⁻¹, the capacity retention rate remained as high as 99.3%, demonstrating excellent rate performance and superior cycling stability. This study optimizes the surface composition and structure of Ti₃C₂T_x through interlayer engineering, providing a scientific basis and technical reference for the application of transition metal ion-intercalated MXene materials in supercapacitors.