Unraveling the Spatial Asynchronous Activation Mechanism of Oxygen Redox-Involved Cathode for High-Voltage Solid-State Batteries

Li-rich layered oxides (LRLO) exhibit significant potential for use in all-solid-state lithium batteries (ASSLBs) owing to their high capacities and wide range of operating voltages. However, the practical application of LRLO in ASSLBs is hindered by the severe failure of carrier transport at the solid-solid interface, which subsequently limits the electrochemical activity of these batteries. Here, the spatially asynchronous activation mechanism of the LRLO in ASSLBs is presented. A spectroscopic study extending from the surface into the bulk interior of LRLO indicates that the activation kinetics of anionic oxygen prefers hysteretic delivery over uniform delivery and fast transition metals (TMs) activation. This spatial hetero activation is dominated by the failure of carrier transport at the interface, which is induced by microstructural defects in the composite cathode. This study is expected to facilitate the microstructural design of high-performance LRLO-based ASSLBs. The carrier transport failure at solid-solid interface induced by the microstructure defects within composite cathode causes the spatial asynchronous activation of Li-rich cathode in ASSLBs: a sluggish activation of O from the surface to the bulk region throughout the long-term cycles over a fast and uniform activation of transition metals predominantly occurs in the initial cycle.image