The formation of dendrites and other protrusions on lithium metal anodes is a subject of continued interest due to the potential to incorporate these anodes in next-generation rechargeable batteries with increased energy densities. Solid polymer electrolytes show improved stability against lithium metal compared to liquid carbonate electrolytes. We have studied the effect of salt concentration on the formation of protrusions formed on electrodeposited lithium through a rigid block copolymer electrolyte, polystyrene-block-poly(ethylene oxide) (PS-b-PEO or SEO), in a lithium‑lithium symmetric cell. The cell lifetime decreases by a factor of 100 when salt concentration is increased by a factor of 5. Our main objective is to understand the reason for this observation. We show that this decrease is not due to a salt-induced change of the morphology of the block-copolymer electrolyte, nor is it due to a salt-induced change of mechanical properties. We use an approach based on Newman's concentrated solution theory to fully characterize ion transport in the block-copolymer electrolyte, and report the conductivity, salt diffusion coefficient, cation transference number, and thermodynamic factor. Neither cell lifetime nor protrusion density in failed cells correlate with any of these electrochemical parameters. However, the electrochemical parameters can be used to predict salt concentration profiles in our symmetric cells. We posit that an important parameter in protrusion growth is the magnitude of the salt concentration gradient, ∆. We observe a direct correlation between ∆ and lithium protrusion growth.

锂金属阳极上枝晶和其他突起的形成一直是人们关注的话题，因为它们有可能将这些阳极结合到能量密度更高的下一代可充电电池中。与液态碳酸盐电解质相比，固态聚合物电解质对锂金属的稳定性有所改善。我们已经研究了盐浓度对通过刚性嵌段共聚物电解质聚苯乙烯-嵌段-聚环氧乙烷（PS- b）在电沉积锂上形成突起形成的影响。-PEO或SEO），在锂锂对称电池中。当盐浓度增加5倍时，电池寿命将减少100倍。我们的主要目的是了解进行此观察的原因。我们表明，这种降低不是由于盐引起的嵌段共聚物电解质形态的变化，也不是由于盐引起的机械性能的变化。我们使用基于纽曼浓缩溶液理论的方法来完全表征嵌段共聚物电解质中的离子传输，并报告电导率，盐扩散系数，阳离子转移数和热力学因子。失效电池中的电池寿命或突出密度都与这些电化学参数均不相关。然而，电化学参数可用于预测我们对称电池中的盐浓度曲线。我们认为，突起生长的一个重要参数是盐浓度梯度的幅度∆。我们观察到∆与锂突起生长之间存在直接关系。