Anionic Effects on Li-Ion Activity and Li-Ion Intercalation Reaction Kinetics in Highly Concentrated Li Salt/Propylene Carbonate Solutions
Anionic Effects on Li-Ion Activity and Li-Ion Intercalation Reaction Kinetics in Highly Concentrated Li Salt/Propylene Carbonate Solutions
复制标题
高浓度锂盐/碳酸丙烯酯溶液中阴离子对锂离子活性和锂离子嵌入反应动力学的影响
DOI：
10.1021/acs.jpcc.2c08653
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发表时间：
2023
期刊：
影响因子：
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通讯作者：
Dokko Kaoru
中科院分区：
文献类型：
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作者：
Ugata Yosuke;Tatara Ryoichi;Ock Ji-young;Zhang Jingjun;Ueno Kazuhide;Watanabe Masayoshi;Dokko Kaoru
某些高浓度电解质（HCE）可提高锂离子电池中电极/电解质界面处的电荷转移反应速率。Li+在HCEs中的溶剂化结构显著影响电化学界面反应动力学。然而，不同的阴离子对这些动力学的影响尚未完全了解。因此，在本研究中，我们研究了阴离子物种对由各种锂盐和碳酸丙烯酯（PC）组成的HCEs的液体结构和电化学反应的影响。拉曼光谱表明，PC和阴离子都配位到HCEs中的Li+离子，并且未配位（游离）PC的浓度根据阴离子种类而变化。因此，电解质中Li+的活性根据阴离子种类而变化。使用具有弱刘易斯碱性阴离子的Li盐增加了Li+的活性，降低了HCE中游离PC的浓度。电解液中Li+的活度显著影响LiCoO 2薄膜电极的Li+嵌入/脱嵌反应速率。电化学阻抗谱表明，在刘易斯碱性较弱的HCE中，Li+离子活性较高，LiCoO 2的界面反应速率加快。
Certain highly concentrated electrolytes (HCEs) enhance the charge-transfer reaction rate at the electrode/electrolyte interface in Li-ion batteries. The solvation structure of Li+in HCEs significantly affects the electrochemical interfacial reaction kinetics. However, the effects of different anions on these kinetics have not yet been fully understood. Therefore, in this study, we investigated the effects of anionic species on the liquid structure and electrochemical reactions of HCEs composed of various Li salts and propylene carbonate (PC). Raman spectra revealed that both PC and anions were coordinated to Li+ions in HCEs and that the concentration of uncoordinated (free) PC changed depending on the anionic species. Consequently, the activity of Li+in the electrolyte changed depending on the anionic species. The use of Li salts with weakly Lewis basic anions increased the activity of Li+and decreased the concentration of free PC in HCEs. The activity of Li+in the electrolyte significantly affected the Li+intercalation/deintercalation reaction rate of the LiCoO2thin-film electrode. Electrochemical impedance spectroscopy revealed that the interfacial reaction rate of LiCoO2was enhanced in the HCEs with anions having weaker Lewis basicity owing to the higher Li+ion activity.