Effect of chemical fluorination of carbon anodes on their electrochemical properties in KF-2HF
Effect of chemical fluorination of carbon anodes on their electrochemical properties in KF-2HF
复制标题
DOI：
10.1149/1.1838019
复制
发表时间：
1997-10-01
影响因子：
3.9
通讯作者：
Nicolas, F
中科院分区：
文献类型：
--
作者：
Groult, H;Devilliers, D;Nicolas, F
在碳电极上制备了两种碳氟表面层，并研究了这些电极在KF-2HF熔体中的电化学性能。第一个薄膜是通过在析氟反应过程中在 KF-2HF 中对碳进行电化学氧化而原位制备的。表层主要由导电石墨层间化合物C-x,(HF)(y)F组成，通常表示为C-x,F。第二层膜是通过在 275 摄氏度下用氟气对碳进行化学氟化而异位制备的，产生 C-x,F 和氟化石墨 CFx 的混合物。因此，KF-2HF 中的氟析出反应被完全抑制。 XPS 研究表明，C-x、F 和 CFx 化合物中分别存在离子和共价碳氟键。当在化学氟化之前将掺杂铝颗粒插入碳中时，由于电极表面和膜内随机分散的C-x,F-AlF3相的存在，发生了析氟反应。据推测，电子转移要么直接从电解质到基底发生，要么通过中间态的隧道效应发生。这些颗粒还促进氟气泡从电极表面脱离。
Two kinds of carbon-fluorine surface layers on carbon electrodes were prepared and the electrochemical properties of these electrodes were studied in the KF-2HF melt. The first film was prepared in situ by electrochemical oxidation of carbon in KF-2HF during the fluorine evolution reaction. The surface layer is mainly composed of conducting graphite intercalation compounds, C-x,(HF)(y)F, usually denoted C-x,F. The second film was prepared ex situ by chemical fluorination of carbon with fluorine gas at 275 degrees C, leading to a mixture of C-x,F and graphite fluorides, CFx. The fluorine evolution reaction is thus completely inhibited in KF-2HF. XPS investigations have shown that ionic and covalent carbon-fluorine bonds are present in the C-x,F and CFx compounds, respectively. When doping aluminum particles were inserted into carbon before chemical fluorination, the fluorine evolution reaction occurred due to the presence of C-x,F-AlF3 phases randomly scattered on the electrode surface and within the film. It is supposed that the electron transfer occurs either directly from the electrolyte to the substrate or by tunnel effect via intermediate-states, These particles also facilitate fluorine bubble detachment from the surface of the electrode.