Nanoporous ALD-modified oxygen-deficient NiO flakes as anodes for lithium-ion batteries

Abstract

The flake-like nature of materials possessing continuous porous skeletons makes them naturally suited for energy storage and other applications. Nickel oxide (NiO) stands out as a highly attractive anode material for lithium-ion batteries due to its relatively high theoretical specific capacity. Nevertheless, the sluggish kinetics of its reactions and significant volume variations during cycling curtail its rate capability and electrochemical stability. In this work, we successfully fabricate nanoporous oxygen-deficient NiO@Al2O3 flakes by a multi-step process involving magnetron sputtering deposition, subsequent thermal oxidation treatment, and a particle atomic layer deposition surface coating technique. The resultant nanoporous oxygen-deficient NiO@Al2O3 flakes demonstrate the potential to establish an intricate network that facilitates efficient charge transfer, rapid ion diffusion, and mechanical robustness throughout electrochemical processes. Particularly noteworthy is the role of the ultrathin Al2O3 coating, which greatly bolsters the cycle life. When employed as lithium storage materials, the nanoporous NiO@Al2O3 flakes exhibit remarkable attributes, including high specific capacity (720 mAh g−1 at 25 mA g−1), superior rate capability (300 mAh g−1 at 5000 mA g−1) and sustained cycling ability, showcasing a reversible capacity of 413 mAh g−1 after 500 cycles at 150 mA g−1 (equivalent to a duration exceeding 4 months). Moreover, the distinctive morphologies and compositions observed after extended cycles definitively corroborate the efficacy of the nanoporous flake architecture. Finally, we present a full-cell configuration comprising a NiO@Al2O3 flakes anode paired with a LiNi0.8Mn0.1Co0.1O2 cathode, which notably exhibits remarkable cycle stability, retaining 84.2 % of its capacity after 100 cycles at 200 mA g−1. This effective and versatile strategy might hold promise for extension to alternative anode and cathode materials, potentially enabling enhanced specific capacity and rendering them suitable for energy storage applications.