Ru-atom clusters embedded in Ti₃C₂T_x lattice for enhanced ammonium ion storage

Ammonium ion (NH₄⁺) based aqueous hybrid supercapacitors (AAHSCs) are attracting great attention due to their environmental friendliness and outstanding electrochemical performance. Two-dimensional (2D) transition metal carbides/nitrides, and carbonitrides known as MXenes, are promising candidates for AAHSCs cathode materials. However, their performance is limited by the intrinsic self-restacking effect and agglomeration. To overcome this issue, this work prepared ruthenium atomic clusters (Ru-AC) embedded in 2D Ti₃C₂T_x nanosheets. This unique structure expands the Ti₃C₂T_x lattice, facilitating NH₄⁺ intercalation. It provides more active sites for the adsorption/desorption of electrolyte ions. The ultra-fine grain and high specific surface area of Ru-AC can significantly promote ion transport and mechanical stress, significantly improving electrode stability during electrochemical reactions. In addition, the intrinsic high conductivity of Ru-AC accelerates the transfer of charge, enhancing electrochemical reaction efficiency. The assembled Ru@Ti₃C₂T_x//AC-AAHSC devices demonstrate outstanding energy storage performance, achieving a high energy density up to 94.08 Wh/kg and superior cycling stability (96.88 % capacity retention after 10,000 cycles). This work presents a new approach for developing high-performance AAHSCs.