富锂锰基层状氧化物(LLO)由于其独特的氧氧化还原(OR)化学特性,有望作为锂离子电池(LIBs)的阴极材料,这可以增加额外的容量。然而,由于过渡金属(TM)-氧键弱,LLO面临着与OR过程不稳定性有关的挑战,导致氧损失和不可逆的相变,导致严重的容量和电压衰减。在这里,提出了一种表面和内部结构的协同电子调节策略,以增强氧稳定性。在材料的内部,TM和O原子周围的局部电子可能被周围的Mo原子离域,促进在高电压下形成更强的TM-O键。此外,在表面上,具有孤对电子的高反应性O原子被额外的TM原子钝化,这提供了一个更稳定的TM-O框架。因此,这种策略稳定了氧气并阻碍了TM的迁移,增强了结构演化的可逆性,导致增加的容量和电压保持。这项工作提出了一种有效的方法,通过表面到内部的电子结构调制来增强LLO的性能,同时也有助于更深入地了解它们的氧化还原反应。
Li-rich Mn-based layered oxides (LLO) hold great promise as cathode materials for lithium-ion batteries (LIBs) due to their unique oxygen redox (OR) chemistry, which enables additional capacity. However, the LLOs face challenges related to the instability of their OR process due to the weak transition metal (TM)-oxygen bond, leading to oxygen loss and irreversible phase transition that results in severe capacity and voltage decay. Herein, a synergistic electronic regulation strategy of surface and interior structures to enhance oxygen stability is proposed. In the interior of the materials, the local electrons around TM and O atoms may be delocalized by surrounding Mo atoms, facilitating the formation of stronger TM─O bonds at high voltages. Besides, on the surface, the highly reactive O atoms with lone pairs of electrons are passivated by additional TM atoms, which provides a more stable TM─O framework. Hence, this strategy stabilizes the oxygen and hinders TM migration, which enhances the reversibility in structural evolution, leading to increased capacity and voltage retention. This work presents an efficient approach to enhance the performance of LLOs through surface-to-interior electronic structure modulation, while also contributing to a deeper understanding of their redox reaction.