Towards high performance lithium-oxygen batteries: Co3O4-NiO heterostructure induced preferential growth of ultrathin Li2O2 film

Abstract Lithium-oxygen batteries (LOBs) with superior energy density are recognized as a promising next-generation energy storage device for electric vehicles. However, the morphology and particle size of Li2O2 as well as the parasitic products Li2CO3 give an essential impact on electrochemical properties. To address these issues, a free-standing Co3O4-NiO@Ni electrode with Co3O4-NiO heterostructure nanoneedle arrays on Ni foam was fabricated. The Co3O4-NiO heterostructure would control the morphology and size of Li2O2. The free-standing carbon-free electrode design would avoid the generation of Li2CO3. Ultrathin Li2O2 film is preferentially generated within the Co3O4-NiO heterostructure nanoneedles during the discharge process. The film-like morphology of Li2O2 would decrease the Li2O2/electrode interfacial resistance and charge overpotential, and enhance the discharge capacity. The free-standing Co3O4-NiO@Ni electrode exhibits an improved electrochemical performance with a high discharge specific capacity of 7905 mAh g−1 at 0.1 A g−1 and good cyclic stability of 120 cycles at 0.1 A g−1 with a cutoff capacity of 500 mAh g−1. This work provides a new strategy for improving the electrochemical performance of LOBs through the morphology control of Li2O2.