Multifunctional Separator Allows Stable Cycling of Potassium Metal Anodes and of Potassium Metal Batteries
Multifunctional Separator Allows Stable Cycling of Potassium Metal Anodes and of Potassium Metal Batteries
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DOI：
10.1002/adma.202105855
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发表时间：
2021-12-13
影响因子：
29.4
通讯作者：
Mitlin, David
中科院分区：
文献类型：
--
作者：
Liu, Pengcheng;Hao, Hongchang;Mitlin, David
这是用于钾金属电池（KMB）的多功能隔膜的第一份报告。聚丙烯上双层流延微型 AlF3 (AlF3@PP) 具有最先进的电化学性能：对称电池在 0.5 mA cm(-2) 和 0.5 mAh cm(-2) 下循环 1000 次（2000 小时）后保持稳定，过电位为 0.042 V。在 5.0 mA cm(-2) 下，600 个循环（240 小时）内保持稳定性，过电势为 0.138 V。循环后的电镀表面无枝晶，而剥离表面包含光滑的固体电解质界面（SEI）。传统的 PP 电池会迅速失效，电镀时会出现枝晶，剥离时会出现“死金属”和 SEI 团块。具有 AlF3@PP 的六氰基铁酸钾 (III) 阴极 KMB 显示出增强的容量保持率（100 次循环时为 91%，而 100 次循环时为 58%）。 AlF3 与 K 部分反应，形成含有 KF、AlF3 和 Al2O3 相的人工 SEI。 AlF3@PP 促进电解质完全润湿并增强吸收，提高离子电导率并增加离子迁移数。 F-19 NMR 揭示了较高的 K+ 迁移数归因于 AlF3 和 FSI- 阴离子之间的强相互作用。润湿和性能的增强是普遍的，通过酯基和醚基溶剂、钾盐、钠盐或锂盐以及不同的商业分离器得到证明。在全电池中，AlF3 可防止 Fe 交叉和循环引起的阴极粉化。
This is the first report of a multifunctional separator for potassium-metal batteries (KMBs). Double-coated tape-cast microscale AlF3 on polypropylene (AlF3@PP) yields state-of-the-art electrochemical performance: symmetric cells are stable after 1000 cycles (2000 h) at 0.5 mA cm(-2) and 0.5 mAh cm(-2), with 0.042 V overpotential. Stability is maintained at 5.0 mA cm(-2) for 600 cycles (240 h), with 0.138 V overpotential. Postcycled plated surface is dendrite-free, while stripped surface contains smooth solid electrolyte interphase (SEI). Conventional PP cells fail rapidly, with dendrites at plating, and "dead metal" and SEI clumps at stripping. Potassium hexacyanoferrate(III) cathode KMBs with AlF3@PP display enhanced capacity retention (91% at 100 cycles vs 58%). AlF3 partially reacts with K to form an artificial SEI containing KF, AlF3, and Al2O3 phases. The AlF3@PP promotes complete electrolyte wetting and enhances uptake, improves ion conductivity, and increases ion transference number. The higher of K+ transference number is ascribed to the strong interaction between AlF3 and FSI- anions, as revealed through F-19 NMR. The enhancement in wetting and performance is general, being demonstrated with ester- and ether-based solvents, with K-, Na-, or Li- salts, and with different commercial separators. In full batteries, AlF3 prevents Fe crossover and cycling-induced cathode pulverization.