首页> 外文期刊>Journal of power sources >Critical evaluation of the stability of highly concentrated LiTFSI - Acetonitrile electrolytes vs. graphite, lithium metal and LiFePO_4 electrodes
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Critical evaluation of the stability of highly concentrated LiTFSI - Acetonitrile electrolytes vs. graphite, lithium metal and LiFePO_4 electrodes

机译:严格评估高浓度LiTFSI-乙腈电解质与石墨,锂金属和LiFePO_4电极的稳定性

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Highly concentrated LiTFSI - acetonitrile electrolytes have recently been shown to stabilize graphite electrodes in lithium-ion batteries (LIBs) much better than comparable more dilute systems. Here we revisit this system in order to optimise the salt concentration vs. both graphite and lithium metal electrodes with respect to electrochemical stability. However, we observe an instability regardless of concentration, making lithium metal unsuitable as a counter electrode, and this also affects evaluation of e.g. graphite electrodes. While the highly concentrated electrolytes have much improved electrochemical stabilities, their reductive decomposition below ca. 1.2 V vs. Li+/Li degrees still makes them less practical vs. graphite electrodes, and the oxidative reaction with Al at ca. 4.1 V vs. Li+/Li degrees makes them problematic for high voltage LIB cells. The former originates in an insufficiently stable solid electrolyte interphase (SEI) dissolving and continuously reforming - causing self-discharge, as observed by paused galvanostatic cycling, while the latter is likely caused by aluminium current collector corrosion. Yet, we show that medium voltage LiFePO4 positive electrodes can successfully be used as counter and reference electrodes.
机译:最近已证明,高浓度的LiTFSI-乙腈电解质可稳定锂离子电池(LIB)中的石墨电极,其效果要优于同类的稀体系。在这里,我们重新访问该系统,以便就电化学稳定性而言,相对于石墨电极和锂金属电极优化盐浓度。然而,我们观察到不考虑浓度的不稳定性,使得锂金属不适合用作对电极,并且这也影响例如对锂的评价。石墨电极。尽管高度浓缩的电解质具有大大改善的电化学稳定性,但它们的还原分解温度低于约200℃。相对于Li + / Li度为1.2 V,与石墨电极相比,它们仍然不那么实用,并且与Al的氧化反应大约在1200℃。 4.1 V vs. Li + / Li度使它们成为高压LIB电池的问题。前者起因于不稳定的固体电解质中间相(SEI)的溶解和连续重整-导致自放电,如通过暂停的恒电流循环所观察到的,而后者则可能是由于铝集流体腐蚀引起的。然而,我们表明中压LiFePO4正极可以成功用作对电极和参比电极。

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