Ensemble effect in porous bimetallic N/C nanocage-grafted CNTs for improved Li-O2 battery Cathodes

Abstract

The geometric design of atomically dispersed 'framework-active sites' grafted with carbonaceous materials to establish a well-connected three-dimensional network represents a compelling strategy for enhancing the performance of lithium-oxygen batteries, particularly in terms of cyclability. This paper introduces a simple approach that utilizes self-assembly heterogeneous nucleation to fabricate discrete bimetallic (Co, Ni) micron lattices grafted onto CNTs, exhibiting commendable surface properties. This intriguing hierarchical structure optimally harnesses the profound structural effects of CNTs weaving matrix, thereby imparting essential properties to the cathode, including high catalytic activity, intrinsically accessible active sites, and continuous porosity to accommodate discharge products. And such binary metal-nitride grafted configuration is significant in mitigating the embarrassing presence of nitrides (low conductivity) and carbon material (inferior activity). Consequently, cell measurement results indicate that a comparable capacity of 8599.7 mAh g⁻¹ and cyclic performance exceeding 200 cycles are achieved in a semi-solid state battery, outperforming commercially available RuC catalysts. And the DFT calculations further demonstrate the strong electronic coupling transfer and exceptional bifunctional activity observed in this binary metal-nitride sample. Therefore, this work exemplifies both steerable preparation techniques and the considerable potential inherent in geometric design for bimetallic sites grafted with carbonaceous material-based catalysts as they transition from Li-O₂ to Li-air batteries.