Hyun Woo Jin, Thomas Cory M, Luu Norman S, Hersam Mark C
Department of Materials Science and Engineering, Northwestern University, Evanston, IL, 60208, USA.
Department of Chemistry, Northwestern University, Evanston, IL, 60208, USA.
Adv Mater. 2021 Apr;33(13):e2007864. doi: 10.1002/adma.202007864. Epub 2021 Feb 17.
Ionogel electrolytes based on ionic liquids and gelling matrices offer several advantages for solid-state lithium-ion batteries, including nonflammability, wide processing compatibility, and favorable electrochemical and thermal properties. However, the absence of ionic liquids that are concurrently stable at low and high potentials constrains the electrochemical windows of ionogel electrolytes and thus their high-energy-density applications. Here, ionogel electrolytes with a layered heterostructure are introduced, combining high-potential (anodic stability: >5 V vs Li/Li ) and low-potential (cathodic stability: <0 V vs Li/Li ) imidazolium ionic liquids in a hexagonal boron nitride nanoplatelet matrix. These layered heterostructure ionogel electrolytes lead to extended electrochemical windows, while preserving high ionic conductivity (>1 mS cm at room temperature). Using the layered heterostructure ionogel electrolytes, full-cell solid-state lithium-ion batteries with a nickel manganese cobalt oxide cathode and a graphite anode are demonstrated, exhibiting voltages that are unachievable with either the high-potential or low-potential ionic liquid alone. Compared to ionogel electrolytes based on mixed ionic liquids, the layered heterostructure ionogel electrolytes enable higher stability operation of full-cell lithium-ion batteries, resulting in significantly enhanced cycling performance.
基于离子液体和凝胶基质的离子凝胶电解质为固态锂离子电池提供了诸多优势，包括不可燃性、广泛的加工兼容性以及良好的电化学和热性能。然而，缺乏能在低电位和高电位下同时保持稳定的离子液体限制了离子凝胶电解质的电化学窗口，进而限制了它们在高能量密度方面的应用。在此，引入了具有层状异质结构的离子凝胶电解质，其在六方氮化硼纳米片基质中结合了高电位（阳极稳定性：相对于Li/Li >5 V）和低电位（阴极稳定性：相对于Li/Li <0 V）咪唑鎓离子液体。这些层状异质结构离子凝胶电解质可扩大电化学窗口，同时保持高离子电导率（室温下>1 mS cm）。使用层状异质结构离子凝胶电解质，展示了具有镍锰钴氧化物阴极和石墨阳极的全电池固态锂离子电池，其表现出单独使用高电位或低电位离子液体时无法实现的电压。与基于混合离子液体的离子凝胶电解质相比，层状异质结构离子凝胶电解质能使全电池锂离子电池实现更高稳定性的运行，从而显著提高循环性能。
