Rakov Dmitrii A, Chen Fangfang, Ferdousi Shammi A, Li Hua, Pathirana Thushan, Simonov Alexandr N, Howlett Patrick C, Atkin Rob, Forsyth Maria
Institute for Frontier Materials, Deakin University, Geelong, Victoria, Australia.
ARC Centre of Excellence for Electromaterials Science (ACES), Deakin University, Burwood, Victoria, Australia.
Nat Mater. 2020 Oct;19(10):1096-1101. doi: 10.1038/s41563-020-0673-0. Epub 2020 May 4.
Non-uniform metal deposition and dendrite formation in high-density energy storage devices reduces the efficiency, safety and life of batteries with metal anodes. Superconcentrated ionic-liquid electrolytes (for example 1:1 ionic liquid:alkali ion) coupled with anode preconditioning at more negative potentials can completely mitigate these issues, and therefore revolutionize high-density energy storage devices. However, the mechanisms by which very high salt concentration and preconditioning potential enable uniform metal deposition and prevent dendrite formation at the metal anode during cycling are poorly understood, and therefore not optimized. Here, we use atomic force microscopy and molecular dynamics simulations to unravel the influence of these factors on the interface chemistry in a sodium electrolyte, demonstrating how a molten-salt-like structure at the electrode surface results in dendrite-free metal cycling at higher rates. Such a structure will support the formation of a more favourable solid electrolyte interphase, accepted as being a critical factor in stable battery cycling. This new understanding will enable engineering of efficient anode electrodes by tuning the interfacial nanostructure via salt concentration and high-voltage preconditioning.
高密度储能装置中金属沉积不均匀和枝晶形成会降低含金属阳极电池的效率、安全性和寿命。超浓离子液体电解质（例如1:1离子液体:碱金属离子）与在更负电位下的阳极预处理相结合，可以完全缓解这些问题，从而彻底改变高密度储能装置。然而，目前人们对极高盐浓度和预处理电位在循环过程中实现金属均匀沉积并防止金属阳极形成枝晶的机制了解甚少，因此尚未得到优化。在此，我们使用原子力显微镜和分子动力学模拟来揭示这些因素对钠电解质中界面化学的影响，证明电极表面类似熔盐的结构如何实现更高速率的无枝晶金属循环。这种结构将有助于形成更有利的固体电解质界面相，这被认为是电池稳定循环的关键因素。这一新认识将通过盐浓度和高压预处理来调节界面纳米结构，从而实现高效阳极电极的工程化。
