MgO-Coated Layered Cathode Oxide With Enhanced Stability for Sodium-Ion Batteries

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.

Structural degradation mechanisms and modulation technologies of layered oxide cathodes for sodium‐ion batteries

“…Similarly, the TiO 2 coating can suppress surface reactions on an O3-NaMn 0.33 Fe 0.33 Ni 0.33 O 2 cathode and improve its structural stability. [135] Besides, the integrity of the lattice and cycling stability of layered oxide cathodes can be maintained by ZrO 2 [50,136] or MgO [137] coating.…”

“…[ 132 ] (b) Structural evolution near the surface of the NaMCNB electrode. Reproduced with permission: Copyright 2020, Elsevier B.V. [ 138 ]…”

Anion-Induced Uniform and Robust Cathode–Electrolyte Interphase for Layered Metal Oxide Cathodes of Sodium Ion Batteries

“…3,4 However, layered metal oxide materials mainly suffer from problems of poor cycling stability due to irreversible phase conversion and interfacial side reactions with electrolytes. 5 The modification of layered oxide cathodes primarily focuses on the design of electrode materials, such as element doping, 6−8 surface coating, 9,10 nanostructure design, 11,12 O/P phase mixture, 13,14 and so on. Recently, due to their pivotal role as transport media in SIBs, both the electrolyte and its interphase with the electrode are receiving more and more scholarly focus.…”

Unprecedented Cyclability and Moisture Durability of NaCrO2 Sodium-Ion Battery Cathode via Simultaneous Al Doping and Cr2O3 Coating

“…Oxide coating, which is a common approach in other cathode materials, , has been rarely explored in O3-NaCrO 2 . However, a recent study by Wang et al showed the positive effect of in-situ-generated Cr 2 O 3 layers on the cyclic stability of O3-NaCrO 2 .…”

“…Among them, pitchderived carbon-coated O3-NaCrO 2 showed the highest cyclic stability, with approximately 90% of its initial capacity retained after 300 C/D cycles. 19 Oxide coating, which is a common approach in other cathode materials, 31,32 has been rarely explored in O3-NaCrO 2 . However, a recent study by Wang et al showed the positive effect of in-situ-generated Cr 2 O 3 layers on the cyclic stability of O3-NaCrO 2 .…”