Improvement of solid-solid interface compatibility and capacitance retention of carbon electrode systems by using MXene as a transition layer

The development of low-internal-resistance and high-stability Al current collectors suitable for supercapacitor organic electrolytes has been desired due to the highly susceptible oxidative passivation problem. Existing solution strategies mainly focus on traditional modification techniques such as carbon-based coatings and surface roughness modulation, making them significantly deficient in terms of interfacial impedance compatibility and electrochemical stability. Herein, an innovative interfacial work function matching strategy utilizing MXene (Ti₃C₂T_x) as a transition layer material is first reported to address these concerns. Using a simple self-assembly method, we constructed an MXene transition layer (Al@MX) on the Al surface, which reduces the equivalent series resistance by more than 80 % and effectively improves capacitance retention from 7 % for bare Al to 61 % for Al@MX after 1000 cycles, as well as remarkable cycling stability. More importantly, the solid-solid interfacial electron transport barrier between Al current collector and YP50F active carbon material is significantly reduced by 24.7 %. These experimental results fully demonstrate that the proposed strategy effectively inhibits the oxidation of the Al current collector and suppresses the decay of capacitance. The unique two-dimensional structure of MXene, combined with its excellent electrochemical stability, offers a potential solution to match the work function of interfacial materials such as between the Al current collector and the carbon active material. This insight in the internal resistance reduction lays a critical technological foundation for developing high-performance SCs, and highlights the potential of MXene in enhancing the charge transfer and storage efficiency of energy storage devices.