Sodium-ion batteries have become a potential alternative to Li-ion batteries due to the abundance of sodium resources. Sodium-ion cathode materials have been widely studied with particular focus on layered oxide lithium analogues. Generally, the capacity is limited by the redox processes of transition metals. Recently, however, the redox participation of oxygen gained a lot of research interest. Here the Mg-doped cathode material P2-Na_0.56Mg_0.04Ni_0.19Mn_0.70O₂ is studied, which is shown to exhibit a good capacity (ca. 120 mAh/g) and high average operating voltage (ca. 3.5 V vs. Na⁺/Na). Due to the Mg-doping, the material exhibits a reversible phase transition above 4.3 V, which is attractive in terms of lifetime stability. In this study, we combine X-ray photoelectron spectroscopy, X-ray absorption spectroscopy and resonant inelastic X-ray scattering spectroscopy techniques to shed light on both, cationic and anionic contributions towards charge compensation.

由于钠资源丰富，钠离子电池已成为锂离子电池的潜在替代品。钠离子阴极材料已被广泛研究，特别关注于层状氧化物锂类似物。通常，容量受过渡金属的氧化还原过程限制。然而，最近，氧气的氧化还原参与引起了很多研究兴趣。在这里，研究了掺Mg的正极材料P2-Na _0.56 Mg _0.04 Ni _0.19 Mn _0.70 O ₂，该材料显示出良好的容量（约120 mAh / g）和高平均工作电压（约3.5 V vs. 5 V）。钠⁺/ Na）。由于掺杂了Mg，该材料在4.3 V以上显示出可逆的相变，这在使用寿命稳定性方面很有吸引力。在这项研究中，我们结合了X射线光电子能谱，X射线吸收能谱和共振非弹性X射线散射能谱技术，以阐明阳离子和阴离子对电荷补偿的贡献。