《Unraveling the LiNbO₃ coating layer on battery performances of lithium argyrodite-based all-solid-state batteries under different cut-off voltages》

The coating layer can effectively alleviate the adverse side effects of the active material/sulfide electrolyte interface in the cathode mixture. A large number of studies have reported the effect of the coating on the typical voltage window, and the effect on different voltage windows is unclear. Here, we systematically studied the degradation mechanism of bare and LiNbO3-coated LiCoO2 electrodes in all-solid-state batteries during cycling at different cut-off voltages. When the upper limit voltage is 3.6 V, the coated electrode exhibits better electrochemical performance than the bare electrode at different charge/discharge rates, while at higher cut-off voltages (3.9 and 4.2 V), both electrodes exhibit rapid degradation of battery performance. The electrochemical performance is highly dependent on the interfacial stability between the active material and the solid electrolyte in the cathode mixture and the structural instability of lithium cobalt oxide under different voltage windows. The evolution of interfacial resistance was systematically studied by in-situ EIS, relaxation time distribution (DRT), TEM, and XPS. The structural changes of bare and coated LiNbO3 electrodes before and after cycling at different cut-off voltages were studied by XRD, TEM, and dQ / dV analysis. The complex interface and the phase transition of lithium cobalt oxide are clarified, which provides a strong theoretical basis for the construction of high-performance all-solid-state batteries.

https://www.sciencedirect.com/science/article/pii/S0013468622017029