Dendrites as climbing dislocations in ceramic electrolytes: Initiation of growth
Dendrites as climbing dislocations in ceramic electrolytes: Initiation of growth
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DOI：
10.1016/j.jpowsour.2020.227989
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发表时间：
2020-04
影响因子：
9.2
通讯作者：
S. S. Shishvan-S.;N. Fleck;R. McMeeking;V. Deshpande
中科院分区：
文献类型：
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作者：
S. S. Shishvan-S.;N. Fleck;R. McMeeking;V. Deshpande
我们通过攀爬厚边位错来理想化陶瓷电解液中的树枝晶生长。枝晶的生长是在枝晶尖端Li+的恒定化学势下进行的：从电解液到枝晶尖端的Li+流量提供了断裂和楔入电解液的自由能。这一自由能依赖于枝晶尖端的Li+过电势，因此与施加的充电电流密度有关。对于Li/LLZO/Li对称电池，预测的临界电流密度与测量结果一致：临界电流密度随枝晶初始长度的增加而减小，随电极/电解液界面离子电阻的增大而减小。模拟还表明，阴极/电解液界面上的空穴局部提高了Li+的过电位，并显著降低了引发枝晶生长的临界电流密度。
We idealise dendrite growth in a ceramic electrolyte by climb of a thick edge dislocation. Growth of the dendrite occurs at constant chemical potential of Li+ at the dendrite tip: the free-energy to fracture and wedge open the electrolyte is provided by the flux of Li+ from the electrolyte into the dendrite tip. This free-energy is dependent on the Li+ overpotential at the dendrite tip and is thereby related to the imposed charging current density. The predicted critical current density agrees with measurements for Li/LLZO/Li symmetric cells: the critical current density decreases with increasing initial length of the dendrite and with increasing electrode/electrolyte interfacial ionic resistance. The simulations also reveal that a void on the cathode/electrolyte interface locally enhances the Li+ overpotential and significantly reduces the critical current density for the initiation of dendrite growth.