All-Solid-State Batteries With Mechanically Stable Interfaces Consisting of a Zero-Strain Cation-Disordered Rocksalt Cathode

Interface stabilization is critical to the development of working all-solid-state batteries. Rigid cathode/solid electrolyte interfaces often disintegrate due to anisotropic volume change of cathode-active materials, resulting in irreversible capacity loss. Herein, we demonstrate that Li_1.211Mo_0.467Cr_0.3O₂ (LMCO), a pioneering cation-disordered rocksalt oxide (DRX) cathode that has intrinsically small volume change upon lithium intercalation, can be integrated with a thiophosphate-based solid electrolyte for all-solid-state batteries. Interface stability of the all-solid LMCO cell was investigated by electrochemical impedance spectroscopy, X-ray micro-computed tomography, and electron microscopy. Since LMCO was initially synthesized as a layered phase exhibiting a large volume change, interface disintegration can be observable in the early cycles. As layered LMCO phase-transformed into DRX LMCO in subsequent cycles, reintegration of the interfaces occurs within a pressurized cell as a result of its zero-stain behavior. Consequently, the DRX LMCO cathode maintains interface integrity, and thus electrical wiring, over an extended number of cycles, leading to improved capacity retention with small internal cell resistance.