Jiangxi Key Laboratory of Power Battery and Materials, School of Materials Science and Engineering, Jiangxi University of Science and Technology , Ganzhou 341000, People's Republic of China.
U.S. Army Armaments Research Development and Engineering Center, Benet Laboratories , Watervliet, New York 12189, United States.
ACS Nano. 2017 May 23;11(5):5051-5061. doi: 10.1021/acsnano.7b01780. Epub 2017 Apr 20.
Silicon (Si) shows promise as an anode material in lithium-ion batteries due to its very high specific capacity. However, Si is highly brittle, and in an effort to prevent Si from fracturing, the research community has migrated from the use of Si films to Si nanoparticle based electrodes. However, such a strategy significantly reduces volumetric energy density due to the porosity of Si nanoparticle electrodes. Here we show that contrary to conventional wisdom, Si films can be stabilized by two strategies: (a) anchoring the Si films to a carbon nanotube macrofilm (CNM) current collector and (b) draping the films with a graphene monolayer. After electrochemical cycling, the graphene-coated Si films on CNM resembled a tough mud-cracked surface in which the graphene capping layer suppresses delamination and stabilizes the solid electrolyte interface. The graphene-draped Si films on CNM exhibit long cycle life (>1000 charge/discharge steps) with an average specific capacity of ∼806 mAh g. The volumetric capacity averaged over 1000 cycles of charge/discharge is ∼2821 mAh cm, which is 2 to 5 times higher than what is reported in the literature for Si nanoparticle based electrodes. The graphene-draped Si anode could also be successfully cycled against commercial cathodes in a full-cell configuration.
硅（Si）由于其极高的比容量，有望成为锂离子电池的阳极材料。然而，Si 非常脆，为了防止 Si 断裂，研究界已经从使用 Si 薄膜迁移到基于 Si 纳米粒子的电极。然而，由于 Si 纳米粒子电极的多孔性，这种策略会显著降低体积能量密度。在这里，我们表明与传统观点相反，Si 薄膜可以通过两种策略来稳定：（a）将 Si 薄膜锚定在碳纳米管宏观薄膜（CNM）集电器上，以及（b）用单层石墨烯包裹薄膜。在电化学循环后，CNM 上的石墨烯涂层 Si 薄膜类似于坚韧的泥裂表面，其中石墨烯覆盖层抑制分层并稳定固体电解质界面。在 CNM 上的石墨烯包裹的 Si 薄膜具有长循环寿命（>1000 次充放电步骤），平均比容量约为 806 mAh g。在 1000 次充放电循环的体积容量平均为 2821 mAh cm，是文献中报道的基于 Si 纳米粒子电极的容量的 2 到 5 倍。石墨烯包裹的 Si 阳极也可以在全电池配置中成功地与商业阴极循环。
