Pan Ruijun, Xu Xingxing, Sun Rui, Wang Zhaohui, Lindh Jonas, Edström Kristina, Strømme Maria, Nyholm Leif
Department of Chemistry-Ångström Laboratory, Uppsala University, Box 538, SE-751 21, Uppsala, Sweden.
Solid State Electronics, Department of Engineering Sciences, The Ångström Laboratory, Uppsala University, Box 538, SE-751 21, Uppsala, Sweden.
Small. 2018 May;14(21):e1704371. doi: 10.1002/smll.201704371. Epub 2018 Apr 19.
Poor cycling stability and safety concerns regarding lithium (Li) metal anodes are two major issues preventing the commercialization of high-energy density Li metal-based batteries. Herein, a novel tri-layer separator design that significantly enhances the cycling stability and safety of Li metal-based batteries is presented. A thin, thermally stable, flexible, and hydrophilic cellulose nanofiber layer, produced using a straightforward paper-making process, is directly laminated on each side of a plasma-treated polyethylene (PE) separator. The 2.5 µm thick, mesoporous (≈20 nm average pore size) cellulose nanofiber layer stabilizes the Li metal anodes by generating a uniform Li flux toward the electrode through its homogenous nanochannels, leading to improved cycling stability. As the tri-layer separator maintains its dimensional stability even at 200 °C when the internal PE layer is melted and blocks the ion transport through the separator, the separator also provides an effective thermal shutdown function. The present nanocellulose-based tri-layer separator design thus significantly facilitates the realization of high-energy density Li metal-based batteries.
锂金属负极较差的循环稳定性以及安全问题是阻碍高能量密度锂金属电池商业化的两个主要因素。在此，我们提出了一种新颖的三层隔膜设计，该设计显著提高了锂金属电池的循环稳定性和安全性。通过简单的造纸工艺制备的薄的、热稳定的、柔性的和亲水的纤维素纳米纤维层，直接层压在经过等离子体处理的聚乙烯（PE）隔膜的每一侧。2.5微米厚、具有中孔结构（平均孔径约20纳米）的纤维素纳米纤维层通过其均匀的纳米通道向电极产生均匀的锂通量，从而稳定锂金属负极，进而提高循环稳定性。由于当内部PE层熔化并阻断离子通过隔膜传输时，三层隔膜即使在200℃仍能保持其尺寸稳定性，因此该隔膜还提供了有效的热关闭功能。基于纳米纤维素的三层隔膜设计因此显著促进了高能量密度锂金属电池的实现。
