Tailoring the growth route of lithium peroxide through the rational design of a sodium-doped nickel phosphate catalyst for lithium-oxygen batteries.

Abstract

Tailoring the morphology and structure of Li2O2, the discharge product of lithium-oxygen batteries (LOBs), through the rational design of cathode catalysts is an efficient strategy to promote the electrochemical performance of LOBs. In this work, sodium-doped nickel phosphate nanorods (Na-NiPO NRs) grown on Ni foam (NF) were prepared by the hydrothermal method and subsequent calcination. For the Na-NiPO NRs, the electronic structure could be optimized and abundant void space among the nanorods would provide abundant transport channels. Adopted as the cathodes, the Na-NiPO NRs could facilitate the uniform growth of sea cucumber-like Li2O2 with sufficient Li2O2-electrolyte and Li2O2-catalyst interfaces, significantly promoting the charge process. Therefore, LOBs could deliver a high discharge capacity of 10365.0 mA h g-1 at 100 mA g-1. And a low potential gap of 1.16 V can be achieved at 200 mA g-1 with a capacity of 500 mA h g-1. The proposed strategy demonstrates the role of the morphology and electronic structure of the cathode catalysts in tuning the Li2O2 morphology and provides a novel approach for achieving high-performance LOBs.