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.