Synergy of Strain and Ligand Effects Activating Core–Shell Cu@RuCu Catalysts for High-Performance Li–O ₂ Batteries

Achieving high-capacity and long-cycle-life lithium–oxygen batteries (LOBs) remains a critical challenge due to sluggish oxygen redox kinetics. The core–shell architectures hold great promise as excellent dual-functional LOB catalysts owing to the synergy of strain and ligand effects between the catalytic surface and substrate. However, their controllable synthesis is hindered by the significant differences in the intrinsic crystallographic properties of the core and shell components. Herein, Cu@RuCu core–shell nanoparticles are constructed via a high-temperature solvothermal surface alloying strategy. The ligand effect induced by the interfacial charge transfer from metallic Cu core to RuCu shell effectively modulates the electronic structure of active Ru sites, thus optimizing the adsorption/desorption behavior of LiO2 intermediates. The substantial strain effect within the RuCu alloy shell further adjusts the microcoordination environment of active sites. Besides, the protective RuCu shell could suppress the oxidation of the Cu core in an oxygen-rich discharge/charge process. Synergizing the strain and ligand dual effect, Cu@RuCu core–shell catalysts enable LOBs to deliver a low overpotential (0.53 V) and long-term cyclability (400 cycles, at 1000 mA g–1), exceeding most state-of-the-art noble-metal-based electrocatalysts. This work offers a generalizable surface alloying strategy for the design of high-performance core–shell LOB catalysts with strain and ligand dual effects.