Mitigating Interfacial Potential Drop of Cathode-Solid Electrolyte via Ionic Conductor Layer to Enhance Interface Dynamics for Solid Batteries

The rapid capacity decay caused by the poor contact and large polarization at the interface between the cathode and solid electrolytes is still a big challenge to overcome for high-power-density solid batteries. In this study, a superior Li⁺ conductive transition layer Li_1.4Al_0.4Ti_1.6(PO₄)₃ is introduced to coat LiNi_0.6Co_0.2Mn_0.2O₂, as a model cathode, to mitigate polarization and enhance dynamic characteristics. The critical attribute for such superior dynamics is investigated by the atomic force microscopy with boundary potential analysis, revealing that the formed interfacial transition layer provides a gradual potential slope and sustain-released polarization, and endows the battery with improved cycling stability (90% after 100 cycles) and excellent rate capability (116 mA h g^-1 at 2 C) at room temperature, which enlightens the comprehension of interface engineering in the future solid batteries systems.