Sustainable solid-state strategy to hierarchical core-shell structured Fe 3O 4@graphene towards a safer and green sodium ion full battery

摘要

AbstractA sustainable solid-state strategy of SPEX milling is developed to coat metal oxide (e.g., Fe3O4) with tunable layers of graphene, and a new hierarchical core-shell structured Fe3O4@graphene composite is constructed. The presented green process can preserve the physicochemical properties of metal (oxide) nanocrystals well while conveniently modifying them with graphene carbon, which is unique from the conventional approaches carried out in the solution followed by high temperature calcinations/carbonization. This strategy is environmental-friendly, cost-effective and feasible to extend for preparing more metal (oxide)-graphene materials readily with controllable layers of graphene. In energy storage applications, as-prepared Fe3O4@graphene only modified with 10?wt% of graphene can show greater capacity of 283?mAh?g?1at 100?mA?g?1with capacity retention of 84% over 100 cycles in sodium battery (vs.17% of pristine Fe3O4). As an appealing nonflammable anode, a completely new full battery of Fe3O4@graphite/Na2.4Fe1.8(SO4)3is assembled, and an impressive energy density beyond 300?Wh kgcathode?1with a high working voltage of 3.2?V is attained. Such kind of green battery comprising from the earth-abundant elements (i.e., Na, Fe, S and O) can demonstrate extremely long cycle ability over 500 cycles and robust rate capability even to 10?C (where 1?C define as 108?mA gcathode?1) which are rarely reported before.Graphical abstractDisplay OmittedHighlights?A sustainable solid-state strategy is developed to coat metal (oxide) with graphene carbon.?A new hierarchical core-shell structured Fe3O4@graphene composite is constructed.?As-prepared Fe3O4@graphene demonstrates greater sodium storage capability.?Sodium ion battery of Fe3O4@graphene/Na2.4Fe1.8(SO4)3 with higher energy is configured.?The concept of green battery comprising from the earth-abundant