Enhanced bond switching at complexion layer facilitates high fracture energy of LATP solid-state electrolytes

Understanding the mechanical behavior of solid-state electrolytes is pivotal for the development of all-solid-state batteries. Using large-scale molecular dynamics simulations, here we show that Li_1.3Al_0.3Ti_1.7(PO₄)₃ (LATP) glass-ceramics, a promising solid-state electrolyte, feature an enhanced bond switching at the complexed glass-crystal interface, thereby facilitating their relatively high fracture energy. Specifically, we study the mechanical behavior of LATP during tensile simulations, focusing on the crack propagation. We find that the fracture behavior is strongly influenced by the size of the nanograins and their positions relative to the pre-crack, and the complexed interface is found to be susceptible to concentrated shear deformation. The fracture energy of LATP glass-ceramics is enhanced for larger grains, since these have higher contact area with the glass phase and thus a larger complexed interface. Based on structural analyses during the tensile process, we demonstrate the occurrence of enhanced bond switching events at complex interfaces. These events dissipate the strain energy associated with the fracture process. Particularly in cases where cracks tend to propagate along the interfaces, this enhancement significantly improves the fracture energy of LATP glass-ceramic electrolytes.