A Computational Comparison of Ether and Ester Electrolyte Stability on a Ca Metal Anode
A Computational Comparison of Ether and Ester Electrolyte Stability on a Ca Metal Anode
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DOI：
10.34133/2021/9769347
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发表时间：
2021
影响因子：
12.9
通讯作者：
Diana Liepinya;Manuel Smeu
中科院分区：
文献类型：
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作者：
Diana Liepinya;Manuel Smeu
钙离子电池(CIB)具有提供廉价能量存储的潜力，但由于缺乏合适的电解液，其实现受到阻碍。在最近实验进展的推动下，我们进行了从头算分子动力学模拟来研究阳极-电解液界面的早期分解反应。通过考察溶剂-四氢呋喃(THF)或碳酸亚乙酯(EC)-和盐-Ca(BH4)2、Ca(BF4)2、Ca(BCl4)2和Ca(ClO4)2的不同组合，我们确定了电解质溶液之间的各种行为趋势。接下来，我们使用纯THF和逐渐增加的负电荷执行单独的轨迹；尽管增加了-32E，但没有检测到THF分解。电荷分析表明，在还原环境中，THF将多余的电荷均匀地分布在其碳氢骨架上，而EC将电荷集中在其酯氧和羰基碳上，从而导致分解。两种溶剂的电荷-时间曲线表明，EC的分解产物可以还原多达五个电子，而THF的分解产物仅限于一个电子。最终，我们发现Ca(BH4)2和THF是所研究的最稳定的溶液，证实了它适合作为CIB电解液的实验证据。
Ca-ion batteries (CIBs) have the potential to provide inexpensive energy storage, but their realization is impeded by the lack of suitable electrolytes. Motivated by recent experimental progress, we perform ab initio molecular dynamics simulations to investigate early decomposition reactions at the anode-electrolyte interface. By examining different combinations of solvent—tetrahydrofuran (THF) or ethylene carbonate (EC)—and salt—Ca(BH4)2, Ca(BF4)2, Ca(BCl4)2, and Ca(ClO4)2—we identify a variety of behavioral trends between electrolyte solutions. Next, we perform a separate trajectory with pure THF and gradually increased negative charge; despite an addition of -32e, no THF decomposition is detected. Charge analysis reveals that in a reductive environment, THF distributes excess charge evenly across its hydrocarbon backbone, while EC concentrates charge on its ester oxygens and carbonyl carbon, resulting in decomposition. Graphs of charge vs. time for both solvents reveal that EC decomposition products can be reduced by up to five electrons, while those of THF are limited to a single electron. Ultimately, we find Ca(BH4)2 and THF to be the most stable solution investigated herein, corroborating experimental evidence of its suitability as a CIB electrolyte.