Kim Ju Young, Shin Dong Ok, Kim Kwang Man, Oh Jimin, Kim Jumi, Kang Seok Hun, Lee Myeong Ju, Lee Young-Gi
Research Group of Multidisciplinary Sensors, Electronics and Telecommunications Research Institute (ETRI), Daejeon, 34129, Republic of Korea.
Sci Rep. 2019 Feb 21;9(1):2464. doi: 10.1038/s41598-019-39237-8.
Functional separators, which have additional functions apart from the ionic conduction and electronic insulation of conventional separators, are highly in demand to realize the development of advanced lithium ion secondary batteries with high safety, high power density, and so on. Their fabrication is simply performed by additional deposition of diverse functional materials on conventional separators. However, the hydrophobic wetting nature of conventional separators induces the polarity-dependent wetting feature of slurries. Thus, an eco-friendly coating process of water-based slurry that is highly polar is hard to realize, which restricts the use of various functional materials dispersible in the polar solvent. This paper presents a surface modification of conventional separators that uses a solution-based coating of graphene oxide with a hydrophilic group. The simple method enables the large-scale tuning of surface wetting properties by altering the morphology and the surface polarity of conventional separators, without significant degradation of lithium ion transport. On the surface modified separator, superior wetting properties are realized and a functional separator, applicable to lithium metal secondary batteries, is demonstrated as an example. We believe that this simple surface modification using graphene oxide contributes to successful fabrication of various functional separators that are suitable for advanced secondary batteries.
功能型隔膜除了具备传统隔膜的离子传导和电子绝缘功能外，还具有其他附加功能，对于实现高安全性、高功率密度等先进锂离子二次电池的发展具有迫切需求。其制备只需在传统隔膜上额外沉积各种功能材料即可。然而，传统隔膜的疏水润湿特性导致浆料呈现极性依赖的润湿特性。因此，难以实现高度极性的水基浆料的环保涂覆工艺，这限制了可分散在极性溶剂中的各种功能材料的使用。本文提出了一种对传统隔膜进行表面改性的方法，即使用带有亲水基团的氧化石墨烯进行溶液涂覆。该简单方法能够通过改变传统隔膜的形态和表面极性来大规模调节表面润湿性能，而不会显著降低锂离子传输性能。在表面改性隔膜上，实现了优异的润湿性能，并以适用于锂金属二次电池的功能型隔膜为例进行了展示。我们相信，这种使用氧化石墨烯的简单表面改性有助于成功制备适用于先进二次电池的各种功能型隔膜。
