Surface-Coated NaNi0.815Co0.15Al0.035O2 Cathode-Based Sodium-Ion Batteries with Enhanced Performance

Abstract

The cathode material is the main component for stabilizing sodium-ion batteries, and there is an urgent need for cathode materials with long-term cyclability and better capacity retention. Surface stabilization is one approach that can improve the performance of the cathode materials. This study focuses on modifying the surface of NaNi0.815Co0.15Al0.035O2 (Na-NCA) cathode materials using the hydrothermal method with different amounts (0.5, 1.0, and 1.5 wt %) of Na-ion conducting Na3PO4 by the liquid precipitation method and its impact on the electrochemical performance of Na-NCA has been investigated. Transmission electron microscopy analysis confirms the coating layer of Na3PO4 with thicknesses ∼2.2 and 20 nm for Na3PO4@0.5 and Na3PO4@1, respectively, and varying thicknesses (∼20-10 nm) is observed for Na3PO4@1.5 cathodes. Electrochemical testing indicates that the sample with a thickness of ∼2.2 nm shows a uniform coating layer, high discharge capacity, better kinetics of Na+ ions, and capacity retention than that of pristine Na-NCA. © 2023 American Chemical Society.