With the rapid development of electrical energy storage technologies, traditional battery systems are limited in practical applications by insufficient energy density and short cycle life. This review provides a comprehensive and critical summary of MXene or MXene-based composites as electrode materials for high-performance energy storage devices. By integrating the synthesis techniques of MXenes that have been studied, this paper systematically illustrates the physicochemical properties, synthesis strategies, and mechanisms of MXenes, and analyzes the bottlenecks in their large-scale preparation. Meanwhile, it collates the latest research achievements of MXenes in the field of metal–ion batteries in recent years, focusing on integrating their latest progress in lithium–ion, sodium–ion, lithium–sulfur, and multivalent ion (Zn²⁺, Mg²⁺, Al³⁺) batteries, and reveals their action mechanisms in different electrode material cases. Combining DFT analysis of the effects of surface functional groups on adsorption energy with experimental studies clarifies the structure–activity relationships of MXene-based composites. However, the development of energy storage electrode materials using MXenes and their hybrid compounds remains in its infancy. Future development directions for MXene-based batteries should focus on understanding and regulating surface chemistry, investigating specific energy storage mechanisms in electrodes, and exploring and developing electrode materials related to bimetallic MXenes.

The phase transition of MAPbI3 during the annealing process has been extensively reported, but there is a lack of research on the preformation of resulting perovskite solar cells (PSCs). Here, we systematically investigated the impact of annealing temperature on the crystal structure of MAPbI3. Our findings reveal that an optimal annealing temperature of 100°C yields high crystallinity and a mixture of tetragonal and cubic phases. Deviating from this temperature range results in incomplete conversion to perovskite material at lower temperatures or formation of only cubic crystal structure above 100°C, leading to degradation at higher temperatures. Theoretical calculations also indicate that the conduction band energy level for the cubic phase is approximately 154 meV lower than that for the tetragonal phase, creating an electron extraction barrier between perovskite and TiO2. Solar cells fabricated with mixed-phase films annealed at 100°C exhibit superior performance with a conversion efficiency of 22.01%, attributed to both energetically favourable crystal structure and excellent crystallinity.