Wu Jiaxin, Ma Yuhan, Zhang Haichang, Xie Haonan, Hu Jin, Shi Chunsheng, Chen Biao, He Chunnian, Zhao Naiqin
School of Materials Science and Engineering, Tianjin Key Laboratory of Composite and Functional Materials, Tianjin University, Tianjin 300350, China.
Joint School of the National University of Singapore and Tianjin University, International Campus of Tianjin University, Fuzhou 350207, China.
ACS Appl Mater Interfaces. 2024 Apr 3;16(13):16351-16362. doi: 10.1021/acsami.4c01316. Epub 2024 Mar 21.
Poly(ethylene oxide) (PEO)-based electrolytes have been extensively studied for all-solid-state lithium-metal batteries due to their excellent film-forming capabilities and low cost. However, the limited ionic conductivity and poor mechanical strength of the PEO-based electrolytes cannot prevent the growth of undesirable lithium dendrites, leading to the failure of batteries. Metal-organic frameworks (MOFs) are functional materials with a periodic porous structure that can improve the electrochemical performance of PEO-based electrolytes. However, the enhancement effect of MOFs with different metal centers and the interaction mechanism with PEO remain unclear. Herein, MOF-74s with Cu or Ni centers are prepared and used as fillers of PEO-based electrolytes. Adding 15 wt % of Cu-MOF-74 to the PEO-based electrolyte (15%Cu-MOF/P-Li) effectively improves the ionic conductivity, lithium transference number, and mechanical strength of the PEO-based electrolyte simultaneously. Furthermore, the ordered pore channels of Cu-MOF-74 provide uniform Li-ion transport pathways, facilitating homogeneous Li deposition. As a result, the lithium symmetric cell with 15%Cu-MOF/P-Li shows stable cycles for 1080 h at 0.1 mA cm and 0.1 mAh cm, and the Li | 15% Cu-MOF/P-Li | LFP full cell exhibits a long cycle life up to 200 cycles at 60 °C and 0.5 C, with a capacity retention rate of 89.7%.
基于聚环氧乙烷（PEO）的电解质因其出色的成膜能力和低成本，已在全固态锂金属电池领域得到广泛研究。然而，基于PEO的电解质离子电导率有限且机械强度较差，无法阻止不良锂枝晶的生长，导致电池失效。金属有机框架（MOF）是具有周期性多孔结构的功能材料，可改善基于PEO的电解质的电化学性能。然而，不同金属中心的MOF的增强效果以及与PEO的相互作用机制仍不明确。在此，制备了具有铜或镍中心的MOF-74，并将其用作基于PEO的电解质的填料。向基于PEO的电解质（15%Cu-MOF/P-Li）中添加15 wt%的Cu-MOF-74可有效同时提高基于PEO的电解质的离子电导率、锂迁移数和机械强度。此外，Cu-MOF-74的有序孔道提供了均匀的锂离子传输路径，有利于锂的均匀沉积。结果，具有15%Cu-MOF/P-Li的锂对称电池在0.1 mA cm和0.1 mAh cm下可稳定循环1080 h，Li | 15% Cu-MOF/P-Li | LFP全电池在60℃和0.5 C下表现出长达200次循环的长循环寿命，容量保持率为89.7%。
