摘要
锂金属负极因高理论比容量(3860 mAh/g)与低氧化还原电位(-3.04 V vs.SHE)等优势,吸引了高比能电池领域的广泛关注.然而,锂金属负极的实际应用仍面临着诸多难点与挑战,其中锂枝晶生长问题尤为突出.在众多解决策略中,电解液调控策略因工艺简便、系统兼容性强、成本低廉、效果显著等特性,被认为是抑制锂枝晶生长最具应用前景的策略之一.本文首先总结了几种锂枝晶生长模型,包括固体电解质界面扩散控制模型、表面形核生长扩散模型、电荷诱导模型和空间电荷模型等,着重讨论了电解液调控策略抑制枝晶生长的模型基础,结果说明了电极界面层(SEI)的物化性能决定了金属锂的沉积行为,而SEI层的组分、力学性能、脱溶剂化过程等受电解液组分影响.随后系统地归纳了电解液优化策略的研究进展,主要介绍了成膜添加剂、溶剂化调控SEI型添加剂、电荷诱导型添加剂、合金型添加剂、高浓盐电解液和局部高浓盐电解液等,对比了各种策略的优缺点.最后,对电解液优化策略进行了总结并对未来发展方向进行了展望.
Abstract
Lithium metal anodes have attracted extensive research attention because of their high theoretical capacity(3860 mAh/g)and low redox potential(-3.04 V vs.SHE).However,the current practical application of lithium metal anodes still faces various challenges,among which the problem of lithium dendrite growth is notable.Among several solution strategies,electrolyte optimization is a promising strategy for inhibiting lithium dendrite growth because of its simple preparation process,strong system compatibility,low cost,and remarkable effect.In this study,we summarize several lithium dendrite growth models,including the solid electrolyte interface diffusion model,surface nucleation growth diffusion model,charge induction model,and space charge model,focusing on the model basis for electrolyte regulation strategies to inhibit dendrite growth.As a result,the physical and chemical properties of the electrode interface layer(SEI)determine the deposition behavior of metallic lithium,and the SEI composition,mechanical properties,and desolvation process are affected by the electrolyte components.Next,the research progress on electrolyte optimization strategies is systematically reviewed,mainly considering film-forming additives,solvent-regulated SEI additives,charge-induced additives,alloy additives,high-concentration salt electrolytes,and local high-concentration salt electrolytes.The advantages and disadvantages of various optimization strategies are summarized.Finally,future research directions for electrolyte optimization strategies are suggested.
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