Defect-Modulated Fast-Freezing Amorphization for Highly Ductile Solid-State Electrolytes

All solid-state batteries (ASSBs) have attracted widespread attention due to their high safety, yet their development remains constrained by mechanical failure. This limitation essentially stems from the intrinsically low ductility of electrolytes, which arises from their high crystallinity. Herein, we propose a defect-modulated fast-freezing approach to achieve the crystalline-to-amorphous transformation. Quantitative defects are introduced into the pristine lattice to reduce the inherent framework stability, followed by the freezing of its high-temperature state to achieve a fully amorphous structure. The resulting amorphized Li3ErCl6 (a-LEC) exhibits a polymer-like low Young's modulus of 1.9 GPa. Meanwhile, the defect-modulated fast-freezing approach increases the ionic conductivity of the electrolyte from 0.21 to 2.32 mS/cm. Using this a-LEC, ASSBs exhibit a capacity decay of only 0.026% per cycle over 1000 cycles, even at a quasi-zero stack pressure of 1 MPa. This new amorphization strategy paves a promising path toward stable ASSBs with robust and facile interphase.