Carbon coated NaLi0.2Mn0.8O2 as a superb cathode material for sodium ion batteries

Abstract

P2 structure materials have been known as a promising cathode material for sodium ion battery. However, their substandard rate capability is a major obstacle for the application of sodium ion batteries to overcome. Herein, we improved the rate capacity of the P2-type sodium-lithium-manganese oxide material by a carbon additive on the material surface. The structure and morphology of pristine sodium-lithium-manganese oxide (NLM) and carbon-coated sodium-lithium-manganese oxide (NLM@C) were confirmed by X-ray diffraction (XRD), Raman spectra, thermal gravimetric analysis (TGA), scanning electron microscopy and energy-dispersive X-ray spectroscopy (SEM-EDS), and transmission electron microscopy (TEM). The electrochemical results revealed that the carbon coating improves rate capability of NLM@C material and increases its specific capacity. Specifically, the NLM@C material delivered a specific capacity of 160 mAh g⁻¹ at 0.1 C, ca. 33% higher than that of pristine NLM material; the NLM@C material retained a capacity of 115 mAh g⁻¹ at a high charged/discharged rate of 1 C. The result suggests that NLM@C material is a promising cathode material for sodium-ion battery applications.