Abstract
Na0.67Ni0.33Mn0.67O2 is a prospective layered cathode material for sodium-ion batteries owing to its low cost, ease of synthesis, and high specific capacity. However, due to direct contact with electrolytes during the cycling process, the cyclic stability is not satisfied. To address this issue, magnesium oxide (MgO) surface modification was performed in this study to improve the material’s cycling properties. MgO layers of various thicknesses were successfully coated onto the cathode, and their electrochemical performances were thoroughly investigated. Among the as-prepared samples, the 2 wt% MgO-coated sample demonstrated the best rate capability and cycling stability. It had an initial reversible discharge capacity of 105 mAh g−1 in the voltage range from 2.0 to 4.5 V at 0.2 C with a high cycle retention of 81.5%. Electrochemical impedance spectroscopy (EIS) results showed that the 2 wt% MgO-coated electrode had the highest conductivity due to the smaller charge transfer resistance (Rct) value. All the test results show that the MgO modification improves the electrochemical properties of Na0.67Ni0.33Mn0.67O2 cathode material. This research could lead to the development of a promising strategy for improving the electrochemical performance of next-generation sodium-ion batteries.
Highlights
The rapid development of electronic equipment and low-power electric vehicles has increased the demand for energy storage materials with high energy efficiency, abundant resources, and environmental friendliness (Kundu et al, 2015; González et al, 2016)
The reflection peaks located at 15.7°, 35.9°, and 43.5° are consistent with the (002), (100), and (103) planes for different thicknesses of magnesium oxide (MgO)/NM cathode materials, which conforms to the P2 structure (JCPDS No 00-05-0894) of electrodes
Different-thickness MgO/NM were further synthesized by using a facile wet chemistry route as the electrode material of sodium-ion batteries (SIBs)
Summary
The rapid development of electronic equipment and low-power electric vehicles has increased the demand for energy storage materials with high energy efficiency, abundant resources, and environmental friendliness (Kundu et al, 2015; González et al, 2016). Lithiumion batteries (LIBs) are currently recognized as an energy storage product with high energy density and good performance rating. Sodium-ion batteries (SIBs) have the advantages of a wider source of raw materials, lower cost, and more safety than LIBs. In some energy storage fields with low energy density requirements, the shortage of lithium resources can be alleviated to a certain extent (Pu et al, 2019; Hakim et al, 2021). The electrochemical performance of SIBs is mainly determined by the cathode material. Most of them have the fatal issue of low average working voltage, which
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