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

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 Li 2 O 2 as well as the parasitic products Li 2 CO 3 give an essential impact on electrochemical properties . To address these issues, a free-standing Co 3 O 4 -NiO@Ni electrode with Co 3 O 4 -NiO heterostructure nanoneedle arrays on Ni foam was fabricated. The Co 3 O 4 -NiO heterostructure would control the morphology and size of Li 2 O 2 . The free-standing carbon-free electrode design would avoid the generation of Li 2 CO 3 . Ultrathin Li 2 O 2 film is preferentially generated within the Co 3 O 4 -NiO heterostructure nanoneedles during the discharge process. The film-like morphology of Li 2 O 2 would decrease the Li 2 O 2 /electrode interfacial resistance and charge overpotential, and enhance the discharge capacity. The free-standing Co 3 O 4 -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 Li 2 O 2 .