Kim Hee Jae, Voronina Natalia, Yashiro Hitoshi, Myung Seung-Taek
Hybrid Materials Research Center, Department of Nanotechnology and Advanced Materials Engineering & Sejong Battery Institute, Sejong University, Gunja-dong, Gwangjin-gu, Seoul 05006, South Korea.
Department of Chemistry and Bioengineering, Iwate University, 4-3-5 Ueda, Morioka, Iwate 020-8551, Japan.
ACS Appl Mater Interfaces. 2020 Sep 23;12(38):42723-42733. doi: 10.1021/acsami.0c10471. Epub 2020 Sep 13.
Cu, Al, and 316L stainless steel are the main components of the current collectors and coin-type cells used in the characterization of potassium-ion battery (KIB) materials and are expected to be electrochemically inactive. Herein, their electrochemical stabilities in a nonaqueous potassium-bis(fluorosulfonyl)imide (KFSI)-based electrolyte are investigated. In dynamic- and transient-mode polarization, passivation of each metal is observed to occur below 3.9, 3.8, and 4.05 V versus K/K for Cu, Al, and 316L stainless steel, respectively, which are considered the threshold potentials. The composition of the passive layers of each metal is determined using time-of-flight secondary-ion mass spectrometry. The passive layers of Cu and Al consist of Cu-O (CuO or CuO) and Al-O (AlO), respectively, and 316L stainless steel is passivated with an outermost Cr-F (CrF) layer and an inner Cr-O (CrO) layer. Above the threshold potentials, however, severe corrosion of each metal occurs accompanied by the dissolution of metal ions, which could affect the reliability of experimental results for KIBs using KFSI-based electrolytes.
铜、铝和316L不锈钢是用于钾离子电池（KIB）材料表征的集流体和硬币型电池的主要成分，预计它们在电化学上是惰性的。在此，研究了它们在基于双（氟磺酰）亚胺钾（KFSI）的非水电解液中的电化学稳定性。在动态和瞬态极化中，相对于K/K，观察到铜、铝和316L不锈钢分别在3.9、3.8和4.05 V以下发生每种金属的钝化，这些电位被视为阈值电位。使用飞行时间二次离子质谱法确定每种金属钝化层的组成。铜和铝的钝化层分别由Cu-O（CuO或Cu₂O）和Al-O（Al₂O₃）组成，316L不锈钢被最外层的Cr-F（CrF₃）层和内层的Cr-O（Cr₂O₃）层钝化。然而，在阈值电位以上，每种金属都会发生严重腐蚀，并伴有金属离子的溶解，这可能会影响使用基于KFSI的电解液的钾离子电池实验结果的可靠性。
