论文标题
库仑稳定的氧孔极化物可实现完全可逆的氧气氧化还原
Coulombically-stabilized oxygen hole polarons enable fully reversible oxygen redox
论文作者
论文摘要
稳定高价值的氧化还原夫妇和外来电子状态需要了解稳定机制。在氧化物中，无论是考虑用于能量储存还是计算，高度氧化的氧化物矿物物种都能复杂形成短价键，并且与明显的局部结构扭曲有关。在电池的氧化毒性电极中，尽管这种重组会部分稳定氧氧化还原，但也会引起大量的滞后作用。在这项工作中，我们研究了分层Na2-XMN3O7中的氧氧化还原，这是一种带有MN空位的正极材料。我们表明，氧化氧化物阳离子与层间空位之间的库仑相互作用会贬低氧气的再生和稳定在4.2 V vs./na+的氧气上。这些库仑相互作用可提供与O-O共价键一样大的热力学节能，并在多个电化学循环中启用了约40 mV电压磁滞，并具有可忽略的电压褪色。我们的结果通过突出几个原子距离的库仑相互作用的作用来确定氧化还原能量的完整图片，并提出了稳定高度氧化的氧气以在能量储存及其他方面应用的途径。
Stabilizing high-valent redox couples and exotic electronic states necessitate an understanding of the stabilization mechanism. In oxides, whether they are being considered for energy storage or computing, highly oxidized oxide-anion species rehybridize to form short covalent bonds and are related to significant local structural distortions. In intercalation oxide electrodes for batteries, while such reorganization partially stabilizes oxygen redox, it also gives rise to substantial hysteresis. In this work, we investigate oxygen redox in layered Na2-XMn3O7, a positive electrode material with ordered Mn vacancies. We show that coulombic interactions between oxidized oxide-anions and the interlayer Na vacancies can disfavor rehybridization and stabilize hole polarons on oxygen at 4.2 V vs. Na/Na+. These coulombic interactions provide thermodynamic energy saving as large as O-O covalent bonding and enable ~ 40 mV voltage hysteresis over multiple electrochemical cycles with negligible voltage fade. Our results establish a complete picture of redox energetics by highlighting the role of coulombic interactions across several atomic distances and suggest avenues to stabilize highly oxidized oxygen for applications in energy storage and beyond.
