Oxygen redox at high voltage has emerged as a transformative paradigm for high-energy battery cathodes such as layered transition-metal oxides by offering extra capacity beyond conventional transition-metal redox. However, these cathodes suffer from voltage hysteresis, voltage fade and capacity drop upon cycling. Single-crystalline cathodes have recently shown some improvements, but these challenges remain. Here we reveal the fundamental origin of oxygen redox instability to be from the domain boundaries that are present in single-crystalline cathode particles. By investigating single-crystalline cathodes with different domain boundaries structures, we show that the elimination of domain boundaries enhances the reversible lattice oxygen redox while inhibiting the irreversible oxygen release. This leads to significantly suppressed structural degradation and improved mechanical integrity during battery cycling and abuse heating. The robust oxygen redox enabled through domain boundary control provides practical opportunities towards high-energy, long-cycling, safe batteries.

通过提供超出传统过渡金属氧化还原的额外容量，高压氧氧化还原已成为高能电池阴极（例如层状过渡金属氧化物）的变革范式。然而，这些阴极在循环时会受到电压滞后、电压衰减和容量下降的影响。单晶阴极最近显示出一些改进，但这些挑战仍然存在。在这里，我们揭示了氧氧化还原不稳定性的根本原因来自单晶阴极颗粒中存在的畴边界。通过研究具有不同畴界结构的单晶阴极，我们表明畴界的消除增强了可逆晶格氧的氧化还原，同时抑制了不可逆的氧释放。这导致在电池循环和滥用加热期间显着抑制结构退化并改善机械完整性。通过域边界控制实现的强大的氧氧化还原为高能量、长循环、安全电池提供了实际机会。