Olsson Emilia, Cottom Jonathon, Cai Qiong
Department of Chemical and Process Engineering, University of Surrey, Guildford, GU2 7XH, UK.
Department of Physics and Astronomy, University College London, London, WC1E 6BT, UK.
Small. 2021 May;17(18):e2007652. doi: 10.1002/smll.202007652. Epub 2021 Mar 18.
Hard carbon anodes have shown significant promise for next-generation battery technologies. These nanoporous carbon materials are highly complex and vary in structure depending on synthesis method, precursors, and pyrolysis temperature. Structurally, hard carbons are shown to consist of disordered planar and curved motifs, which have a dramatic impact on anode performance. Here, the impact of position on defect formation energy is explored through density functional theory simulations, employing a mixed planar bulk and curved surface model. At defect sites close to the surface, a dramatic decrease ( 50%) in defect formation energy is observed for all defects except the nitrogen substitutional defect. These results confirm the experimentally observed enhanced defect concentration at surfaces. Previous studies have shown that defects have a marked impact on metal storage. This work explores the interplay between position and defect type for lithium, sodium, and potassium adsorption. Regardless of defect location, it is found that the energetic contributions to the metal adsorption energies are principally dictated by the defect type and carbon interlayer distance.
硬碳阳极在下一代电池技术中显示出巨大的潜力。这些纳米多孔碳材料高度复杂，其结构会因合成方法、前驱体和热解温度的不同而有所变化。在结构上，硬碳由无序的平面和弯曲结构组成，这对阳极性能有显著影响。在此，通过密度泛函理论模拟，采用混合平面体和曲面模型，探讨了位置对缺陷形成能的影响。在靠近表面的缺陷位点，除氮替代缺陷外，所有缺陷的缺陷形成能均显著降低（50%）。这些结果证实了实验观察到的表面缺陷浓度增加。先前的研究表明，缺陷对金属存储有显著影响。这项工作探讨了锂、钠和钾吸附时位置与缺陷类型之间的相互作用。无论缺陷位置如何，发现对金属吸附能的能量贡献主要由缺陷类型和碳层间距决定。
