Department of Materials Science and Engineering, University of Maryland , College Park, Maryland 20742, United States.
Nano Lett. 2014 Jan 8;14(1):139-47. doi: 10.1021/nl4035626. Epub 2013 Dec 5.
Atomic-layer-deposition (ALD) coatings have been increasingly used to improve battery performance. However, the electrochemical and mechanistic roles remain largely unclear, especially for ALD coatings on electrodes that undergo significant volume changes (up to 100%) during charging/discharging. Here we investigate an anode consisting of tin nanoparticles (SnNPs) with an ALD-Al2O3 coating. For the first time, in situ transmission electron microscopy unveiled the dynamic mechanical protection of the ALD-Al2O3 coating by coherently deforming with the SnNPs under the huge volume changes during charging/discharging. Battery tests in coin-cells further showed the ALD-Al2O3 coating remarkably boosts the cycling performance of the Sn anodes, comparing with those made of bare SnNPs. Chemomechanical simulations clearly revealed that a bare SnNP debonds and falls off the underlying substrate upon charging, and by contrast the ALD-Al2O3 coating, like ion-conductive nanoglue, robustly anchors the SnNP anode to the substrate during charging/discharging, a key to improving battery cycle performance.
原子层沉积（ALD）涂层已越来越多地被用于提高电池性能。然而，其电化学和机械作用在很大程度上仍不清楚，特别是对于在充电/放电过程中经历显著体积变化（高达 100%）的电极上的 ALD 涂层。在这里，我们研究了一种由锡纳米颗粒（SnNPs）组成的阳极，并带有 ALD-Al2O3 涂层。这是首次通过原位透射电子显微镜揭示了 ALD-Al2O3 涂层在充电/放电过程中与 SnNPs 一致变形的动态机械保护作用，因为 SnNPs 经历了巨大的体积变化。在硬币电池中的电池测试进一步表明，ALD-Al2O3 涂层显著提高了 Sn 阳极的循环性能，与裸 SnNPs 制成的阳极相比。化学机械模拟清楚地表明，在充电时，裸 SnNP 会在充电时脱粘并从底层基底上脱落，而相比之下，ALD-Al2O3 涂层则像离子导电纳米胶一样，在充电/放电过程中牢固地将 SnNP 阳极固定在基底上，这是提高电池循环性能的关键。
