Chemical-Delithiation-Induced Surface Reconstruction in Layered Oxide Cathodes for High-Performance All-Solid-State Batteries

Abstract

Developing all-solid-state batteries (ASSBs) based on high-capacity cathodes (e.g., Ni-rich and Li-rich layered oxides) offers a promising route toward next-generation batteries with high energy density and safety. However, under high voltage, the cathode/solid electrolyte (SE) interface suffers from severe chemical degradation due to enhanced cathode–catholyte interactions. Here, we propose a chemical-delithiation-induced surface reconstruction strategy for Li-rich layered oxide cathodes, as a proof of concept, to effectively eliminate cathode-catholyte interfacial chemical degradation in ASSBs. We found that chemical-delithiation treatment by NO2BF4 induces a surface reconstruction of Li-rich layered oxide, forming a cation-disordered subsurface layer, which can then incorporate fluorine alike disordered rock-salt cathodes. Such surface reconstruction passivates the oxidative surface of Li-rich cathode in which oxygen redox is prevalent at high potential, thus eliminating the interfacial chemical degradation during cycling. As a result, the treated Li-rich layered cathode achieved a reversible capacity of ∼300.3 mA h g–1 that is comparable to liquid cells and a capacity retention of 82.3% over 1500 cycles at 1 C. By extending this strategy to Ni-rich layered oxides, we further demonstrate its universality in interfacial chemical design for high-energy-density ASSBs.