Theory-Guided Design of Unconventional Phase Metal Heteronanostructures for Higher-Rate Stable Li-CO₂ and Li-Air Batteries

Lithium-carbon dioxide (Li-CO₂) and Li-air batteries hold great potential in achieving carbon neutral given their ultrahigh theoretical energy density and eco-friendly features. However, these Li-gas batteries still suffer from low discharging-charging rate and poor cycling life due to sluggish decomposition kinetics of discharge products especially Li₂CO₃. Here we report the theory-guided design and preparation of unconventional phase metal heteronanostructures as cathode catalysts for high-performance Li-CO₂/air batteries. The assembled Li-CO₂ cells with unconventional phase 4H/face-centered cubic (fcc) ruthenium-nickel heteronanostructures deliver a narrow discharge-charge gap of 0.65 V, excellent rate capability and long-term cycling stability over 200 cycles at 250 mA g⁻¹. The constructed Li-air batteries can steadily run for above 150 cycles in ambient air. Electrochemical mechanism studies reveal that 4H/fcc Ru−Ni with high-electroactivity facets can boost redox reaction kinetics and tune discharge reactions towards Li₂C₂O₄ path, alleviating electrolyte/catalyst failures induced by the aggressive singlet oxygen from solo decomposition of Li₂CO₃.