Protective Coating of Single-Crystalline Ni-Rich Cathode Enables Fast Charging in All-Solid-State Batteries
Wengao Zhao, Ruizhuo Zhang, Fucheng Ren, Leonhard Karger, Sören L. Dreyer, Jing Lin, Yuan Ma, Yong Cheng, Avnish Singh Pal, Martin Velazquez‐Rizo, Ali Ahmadian, Ziyan Zhang, Philipp Müller, Jürgen Janek, Yong Yang, Aleksandr Kondrakov, Torsten Brezesinski
Abstract
Improving interfacial stability between cathode active material (CAM) and solid electrolyte (SE) is vital for developing high-performance all-solid-state batteries (ASSBs), with compatibility issues among the cell components representing a major challenge. CAM surface coating with a chemically inert ion conductor is a promising approach to suppress side reactions occurring at the cathode interfaces. Another strategy to mitigate mechanical degradation involves utilizing single-crystalline particle morphologies. Their more robust bulk structure and lower tortuosity for charge transport, compared to polycrystalline (PC) CAMs, can significantly enhance cyclability in ASSBs. Herein, we coated a LiNbO 3 protective layer onto the free surface of quasi single-crystalline LiNi 0.83 Co 0.12 Mn 0.05 O 2 (SC83) particles. Pellet-stack ASSB cells using the LiNbO 3 @SC83 CAM and argyrodite Li 6 PS 5 Cl as SE showed a capacity retention of 88% after 1000 cycles at the 1 C rate, compared to only 71% for the uncoated counterpart and far superior to that of LiNbO 3 @PC83 (30%). The effectiveness of LiNbO 3 coating and the SC-NCM nature in mitigating electro-chemo-mechanical degradation was studied by combining modeling and physical/electrochemical characterizations. We demonstrate that the capacity decay at fast charge is due primarily to the mechanical degradation of CAM particles, while it is strongly determined by CAM|SE interfacial reactions under slow-charging conditions.