Self-constructing a lattice-oxygen-stabilized interface in Li-rich cathodes to enable high-energy all-solid-state batteries

Abstract

Employing lithium-rich oxides as cathode materials offers an ideal option for achieving high-energy all-solid-state lithium batteries (ASSLBs), while lithium-rich cathode materials are usually hard to directly match with solid-state electrolytes (SSEs), severely limiting the capacity utilization of the high-capacity cathodes in ASSLBs. Here, a composite cathode system with only SSEs and lithium-rich oxides is used to investigate the compatibility, where the single-crystal Li₂RuO₃ (LRO) with high electronic conductivity is selected as a model lithium-rich oxide to avoid additional conductive carbon interfaces. By matching with two classical SSEs, Li₆PS₅Cl and Li₃InCl₆ (LIC), we reveal that the interface compatibility of SSEs/LRO, especially the compatibility of SSEs with the oxidized lattice oxygen (O⁽²⁻ⁿ⁾⁻, 0 < n < 2) of LRO, is the dominant factor of the electrochemical properties. Furthermore, a self-constructed lattice-oxygen-stabilized interface formed by the interaction of indium with O⁽²⁻ⁿ⁾⁻ is first reported, which effectively prevents the O loss and interface degradation of LRO, resulting in a reversible capacity of 294.0 mA h g⁻¹ with an initial coulombic efficiency of 98.1% and a capacity retention of 99.6% after 300 cycles, as well as a specific energy of 495 W h kg⁻¹ based on the mass of a 30 wt%-LIC/70 wt%-LRO composite cathode and Li anode.