Detecting Potassium Ion Gradients at a Model Graphitic Interface
Detecting Potassium Ion Gradients at a Model Graphitic Interface
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DOI：
10.1016/j.electacta.2017.04.105
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发表时间：
2017-07-01
影响因子：
6.6
通讯作者：
Rodriguez-Lopez, Joaquin
中科院分区：
文献类型：
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作者：
Barton, Zachary J.;Hui, Jingshu;Rodriguez-Lopez, Joaquin
钾离子电池（KIBs）作为锂离子电池（LIBs）具有吸引力的低成本替代品而受到关注。新兴的KIB材料尚未被完全了解，因此正在开发原位表征技术来解决LIB材料操作的异同，包括界面离子转移和固体电解质界面相（SEI）形成方面。在这里，我们介绍了在扫描电化学显微镜（SECM）中使用汞盘孔微电极作为探针来检测工作石墨材料上的K+梯度。这些探针上的电化学控制的汞化和剥离反应允许它们在导电表面附近精确定位，并且一旦衬底偏向于插入K+，就可以检测局部浓度的变化。K+还原为Hg相遵循与Li+和Na+相似的行为，并产生用于评估局部底物反应性的电化学响应。利用这些探针，我们在原位证明了K+在图案化高取向热解石墨（HOPG）表面的可逆嵌入，这是碳质KIB材料的模型界面。我们的方法提供了局部K+通量的直接测量，这是无法通过体电分析技术解决的，因此我们的方法可能为新兴的基于kib的储能技术的反应机制提供信息。(C) 2017 Elsevier Ltd.版权所有。
Potassium ion batteries (KIBs) are gaining attention as attractive, low-cost alternatives to lithium ion batteries (LIBs). Emerging KIB materials are not yet fully understood, so in situ characterization techniques are being developed to address the similarities and differences to the operation of LIB materials, including aspects of interfacial ion transfer and solid electrolyte interphase (SEI) formation. Here, we introduce the use of Hg disc-well microelectrodes as probes in scanning electrochemical microscopy (SECM) for the detection of K+ gradients on an operating graphitic material. Electrochemically controlled amalgamation and stripping reactions on these probes permit their accurate positioning near a conductive surface, and the detection of local concentration changes once the substrate is biased to intercalate K+. K+ reduction into the Hg phase follows a behavior similar to that of Li+ and Na+ and yields an electrochemical response that is used to evaluate local substrate reactivity. Using these probes in situ, we demonstrate the reversible intercalation of K+ on a surface site of patterned highly oriented pyrolytic graphite (HOPG), a model interface for carbonaceous KIB materials. Our method affords a direct measurement of localized K+ fluxes, which are not resolvable through bulk electroanalytical techniques, thus making our approach potentially informative about reaction mechanisms for nascent KIB-based energy storage technologies. (C) 2017 Elsevier Ltd. All rights reserved.