中国科学院物理研究所李泓团队通过无掺杂方法实现了高性能无缺陷LiCoO₂阴极。该项研究成果发表在2025年6月17日出版的《美国化学会志》上。

提高层状氧化物阴极的充电电压以实现更高的容量会引起与过渡金属板滑动相关的相变，这会显著影响材料的结构稳定性。通常采用掺杂惰性元素来延迟这种向更高电压的相变。然而，这些电化学惰性元素不参与氧化还原反应，从而损害了锂的存储容量。这种折衷提出了一个关键且未被充分探索的问题，即容量降低的掺杂材料是否仍然在能量密度方面保持优势。

研究组使用LiCoO₂作为模型材料，观察到Al掺杂剂浓度的增加确实延迟了H1-3相变的起始电压。然而，与这种相变相关的脱锂程度基本保持不变。当放电容量被控制在略低于全局H1-3相变的阈值时，与掺杂样品相比，未掺杂材料在较低的充电截止电压下表现出更优异的容量保持和速率性能。 

综合实验表征和理论计算表明，掺杂诱导的结构缺陷阻碍了Li⁺的传导，促进了氧的释放，从而加速了性能的退化。这项研究表明，在高压层状氧化物阴极的开发中，优先提高材料容量至关重要。此外，必须仔细评估掺杂的不利影响，因为工业制备方法通常会导致非理想掺杂剂的掺入，从而导致不希望的结构缺陷，这些缺陷对高压相变的可逆性特别有害。

附：英文原文

Title: Achieving High-Performance Defect-Free LiCoO2 Cathode via a Dopant-Free Approach

Author: Sichen Jiao, Yu Li, Ting Lin, Shuhang Feng, Chengzhen Zhang, Hongyi Pan, Weiguang Lin, Xiqian Yu, Lin Gu, Xuejie Huang, Liquan Chen, Hong Li

Issue&Volume: June 17, 2025

Abstract: Elevating the charging voltage of layered oxide cathodes to achieve higher capacity induces phase transitions associated with transition metal slab gliding, which significantly impacts the material’s structural stability. Doping with inert elements is commonly employed to delay such phase transitions to higher voltages. However, these electrochemically inactive elements do not participate in redox reactions, thereby compromising lithium storage capacity. This compromise raises a critical and underexplored issue regarding whether doped materials with reduced capacity still maintain an advantage in energy density. In this study, using LiCoO2 as a model material, it was observed that an increase in the concentration of Al dopant indeed delayed the onset voltage of the H1–3 phase transition. However, the extent of delithiation associated with this phase transition remains largely unchanged. When the discharge capacity is controlled to just below the threshold for the global H1–3 phase transition, the undoped material demonstrates even superior capacity retention and rate performance compared to the doped samples, at a lower charging cutoff voltage. Comprehensive experimental characterizations and theoretical calculations reveal that the doping-induced structural defects hinder Li+ conduction and promote oxygen release, consequently accelerating performance degradation. This study suggests that in the development of high-voltage layered oxide cathodes, it is crucial to prioritize enhancing material capacity. Additionally, it is imperative to meticulously assess the adverse effects of doping, as industrial preparation methods often lead to nonideal dopant incorporation, causing undesirable structural defects that are particularly harmful to the reversibility of high-voltage phase transitions.

DOI: 10.1021/jacs.5c05162

Source: https://pubs.acs.org/doi/abs/10.1021/jacs.5c05162