The mechanism revealed in this work has the potential to be generalized to different solvents and different solid systems. To achieve solvent/molecule-assisted solid-solid phase transitions, the following conditions should be met: Firstly, the solid-solid phase transition is cumbersome due to a high energy barrier or a complex transition pathway, and therefore, it needs to be accomplished through a two-step C-A-C mechanism. Second, the assisting solvent or molecule should have an appropriate size, making it easier to enter the disordered interface but not to disrupt the crystal structure. Third, the assisting molecules should have a high polarity, ensuring strong interactions with ions in the disordered region, thereby enhancing the diffusion of the interfacial ions.