Zeng Weihao, Xia Fanjie, Wang Juan, Yang Jinlong, Peng Haoyang, Shu Wei, Li Quan, Wang Hong, Wang Guan, Mu Shichun, Wu Jinsong
State Key Laboratory of Advanced Technology for Materials Synthesis and Processing, Wuhan University of Technology, Wuhan, Hubei, China.
Guangdong Research Center for Interfacial Engineering of Functional Materials, Shenzhen University, Shenzhen, China.
Nat Commun. 2024 Aug 27;15(1):7371. doi: 10.1038/s41467-024-51168-1.
Fast-charging, non-aqueous lithium-based batteries are desired for practical applications. In this regard, LiMnO is considered an appealing positive electrode active material because of its favourable ionic diffusivity due to the presence of three-dimensional Li-ion diffusion channels. However, LiMnO exhibits inadequate rate capabilities and rapid structural degradation at high currents. To circumvent these issues, here we introduce quintuple low-valence cations to increase the entropy of LiMnO. As a result, the entropy-increased LiMnO-based material, i.e., LiMnCuMgFeZnNiO, when tested in non-aqueous lithium metal coin cell configuration, enable 1000 cell cycles at 1.48 A g (corresponding to a cell charging time of 4 minutes) and 25°C with a discharge capacity retention of about 80%. We demonstrate that the increased entropy in LiMnO leads to an increase in the disordering of dopant cations and a contracted local structure, where the enlarged LiO space and enhanced Mn-O covalency improve the Li-ion transport and stabilize the diffusion channels. We also prove that stress caused by cycling at a high cell state of charge is relieved through elastic deformation via a solid-solution transition, thus avoiding structural degradation upon prolonged cycling.
实际应用中需要快速充电的非水锂基电池。在这方面，LiMnO因其存在三维锂离子扩散通道而具有良好的离子扩散率，被认为是一种有吸引力的正极活性材料。然而，LiMnO在高电流下表现出不足的倍率性能和快速的结构降解。为了解决这些问题，我们在此引入五元低价阳离子以增加LiMnO的熵。结果，熵增加的基于LiMnO的材料，即LiMnCuMgFeZnNiO，在非水锂金属硬币电池配置中进行测试时，在1.48 A g（对应于电池充电时间4分钟）和25°C的条件下能够实现1000次电池循环，放电容量保持率约为80%。我们证明，LiMnO中增加的熵导致掺杂阳离子无序度增加和局部结构收缩，其中扩大的LiO空间和增强的Mn - O共价性改善了锂离子传输并稳定了扩散通道。我们还证明，通过固溶体转变的弹性变形缓解了在高电池充电状态下循环所引起的应力，从而避免了长时间循环后的结构降解。
