Stability of Calcium Ion Battery Electrolytes: Predictions from Ab Initio Molecular Dynamics Simulations
Stability of Calcium Ion Battery Electrolytes: Predictions from Ab Initio Molecular Dynamics Simulations
复制标题
钙离子电池电解质的稳定性：从头算分子动力学模拟的预测
DOI：
10.1021/acsami.0c21716
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发表时间：
2021
影响因子：
9.5
通讯作者：
Wong, Bryan M.
中科院分区：
文献类型：
--
作者：
Yamijala, Sharma S.;Kwon, Hyuna;Guo, Juchen;Wong, Bryan M.
镁离子电池、钙离子电池和锌离子电池等多价电池作为补充传统锂离子电池的新一代电化学储能装置已引起人们的广泛关注。其中，钙离子电池(CIB)由于难于可逆的钙沉积-溶解而被开发的最少。在这项工作中，我们考察了四种不同的钙盐与弱配位阴离子和现有电池技术中常用的三种不同溶剂的稳定性，以确定合适的CIB候选者。通过对盐-钙和溶剂-钙界面的Born-Oppenheimer分子动力学(BUMD)模拟，我们发现四甘醇溶剂和碳硼盐是很有前途的CIBs候选者。由于钙表面的强还原性质，其他盐和溶剂很容易分解。我们用含时投影态密度、含时电荷转移图和爬像微动弹性带计算解释了盐/溶剂在钙表面分解的微观机制。总之，这项工作首次使用BLOMD模拟对候选盐和溶剂在钙表面上的动态稳定性进行了机械评估，并为设计稳定的CIB电解质提供了一条可预测的途径。
Multivalent batteries, such as magnesium-ion, calcium-ion, and zinc-ion batteries, have attracted significant attention as next-generation electrochemical energy storage devices to complement conventional lithium-ion batteries (LIBs). Among them, calcium-ion batteries (CIBs) are the least explored due to difficult reversible Ca deposition–dissolution. In this work, we examined the stability of four different Ca salts with weakly coordinating anions and three different solvents commonly employed in existing battery technologies to identify suitable candidates for CIBs. By employing Born–Oppenheimer molecular dynamics (BOMD) simulations on salt-Ca and solvent-Ca interfaces, we find that the tetraglyme solvent and carborane salt are promising candidates for CIBs. Due to the strong reducing nature of the calcium surface, the other salts and solvents readily decompose. We explain the microscopic mechanisms of salt/solvent decomposition on the Ca surface using time-dependent projected density of states, time-dependent charge-transfer plots, and climbing-image nudged elastic band calculations. Collectively, this work presents the first mechanistic assessment of the dynamical stability of candidate salts and solvents on a Ca surface using BOMD simulations, and provides a predictive path toward designing stable electrolytes for CIBs.