In Situ Fabrication of Nano Porous NiO-Capped Ni3P film as Anode for Li-Ion Battery with Different Lithiation Path and Significantly Enhanced Electrochemical Performance

• A nano porous NiO covered Ni3P films was fabricated by a low cost way.
• The P-rich condition contributed to the formation of porous surface.
• The lithiation path was changed by the porous film evidently.
• The porous NiO film kept Ni3P complete & decreased electrical resistance of cell.

Nickel phosphide (Ni3P) is a promising anode material for lithium-ion batteries owing to its high specific capacity, though significant improvement in its cycling stability is highly desired. Here we propose an effective and low-cost solution via a three-dimensional construction of porous NiO covered Ni3P films over a substrate of Ni foam, through electroless plating of P-rich Ni3P and subsequent in situ oxidation in air. The in situ oxidation of P-rich Ni3P resulted in the formation of nano porous NiO capping layer. Remarkable enhancement in the cycling stability of such a composite anode was thus realized. The initial discharge capacity for a CR2016-type coin cell was as high as 920 mA h g−1, and there was still a reversible capacity of 550 mA h g−1 after 60 cycles at a current density of 38.8 mA g−1. The presence of porous NiO capping layer changed the lithiation path and significantly improved the cycling performance. The decreased resistance in charge transport due to the existence of adequate channels for Li ions diffusion also enhanced rate performance. A pristine Ni3P films was researched as a comparison.

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