Non-Noble-Metal Catalyst and Zn/Graphene Film for Low-Cost and Ultra-Long-Durability Solid-State Zn-Air Batteries in Harsh Electrolytes

摘要

Exploration and development of cost-effective, ultra-long durability, andhigh-performing non-noble-metal catalysts for the oxygen reduction reaction(ORR) to replace Pt-based catalysts for electrochemical energy conversiondevices is still of great challenge. Although several types of non-noble-metalcatalysts (N-doped graphene, transition metal nanoparticles, single atomicmetal-nitrogen-carbon, etc.) are claimed to have comparable or overwhelmingcatalytic performances compared with commercial Pt/C, their long-durability,especially in harsh electrolytes, are still unsatisfactory for practical applications.Herein, the classical Fe_3C-NG catalysts are synthesized and investigatedto understand the catalytic and degradation behaviors in Zn-Airbatteries. Experimental analysis and theoretical calculations reveal that theMott–Schottky heterojunction formed by Fe_3C quantum dots (QDs) andN-doped graphene carbon (Fe_3C-NG) boosts the ORR, since the Fe_3C quantumdots provide rapid electron transfer to the valence band of NG. Moleculardynamic simulation suggests that the graphene structure in NG is relativelystable in extremely corrosive electrolyte, which avoids the corrosion of Fe_3Cquantum dots. In combination of the Zn/graphene composite film and solidstateelectrolyte, the optimized Zn-air battery with Fe_3C-NG catalyst delivers ahigh open circuit voltage of 1.506 V, high energy density of 706.4 Wh kg~(–1), andlong-term stability for 1000 h.