Brine-filled MXene “Sandwich” system for synergistically enhanced electrochemical energy storage and solar desalination

The growing demand for freshwater and energy, especially in off-grid and coastal regions, necessitates the development of efficient, sustainable solutions. This study presents an innovative sandwich system, where Ti₃C₂T_x MXene-MoS₂ membranes form the top and bottom layers, while the core is composed of a brine solution and nonwoven fabric. The seawater or saline solutions commonly used in the interfacial solar vapor generation (ISVG) process, as well as serving as the electrolyte for electrochemical energy storage, further optimizing system integration. As a proof-of-concept, the sandwich system simultaneously generates freshwater and stores electrical energy, demonstrating a maximum evaporation rate of 3.01 kg m⁻² h⁻¹ under 1 sun irradiation and a capacitance area ratio of 70.4 mF·cm⁻² at 1 mA cm⁻². After 1000 charge-discharge cycles, the device retains 90.36 % of its capacitance, indicating exceptional long-term stability. Furthermore, the structural design of this system facilitates effective water-salt separation, preventing salt blockage on the evaporator surface, thus enhancing the system's efficiency and longevity. This integrated system presents a promising solution for sustainable freshwater production and energy storage.