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Abstract：
Flexible graphite foils with varying thicknesses (S = 282 ± 5 μm, M = 494 ± 7 μm, L = 746 ± 8 μm) and an initial density of 0.70 g/cm3 were obtained using the nitrate method. The specific electrical and thermal conductivity of these foils were investigated. As the density increased from 0.70 g/cm3 to 1.75 g/cm3, the specific electrical conductivity increased from 69 to 192 kS/m and the thermal conductivity increased from 109 to 326 W/(m·K) due to the rolling of graphite foils. The study showed that conductivity and anisotropy depend on the shape, orientation, and contact area of thermally expanded graphite (TEG) mesoparticles (mesostructural factor), and the crystal structure of nanocrystallites (nanostructural factor). A proposed mesostructural model explained these increases, with denser foils showing elongated, narrowed TEG particles and larger contact areas, confirmed by electron microscopy results. For graphite foils 200 and 750 μm thick, increased density led to a larger coherent scattering region, likely due to the rotation of graphite mesoparticles under mechanical action, while thinner foils (<200 μm) with densities > 1.7 g/cm3 showed increased plastic deformation, indicated by a sharp reduction in the coherent scattering region size. This was also evident from the decrease in misorientation angles with increasing density. Rolling reduced nanocrystallite misorientation angles along the rolling direction compared to the transverse direction (TD) (for 1.75 g/cm3 density ΔMA = 1.2° (S), 2.6° (M), and 2.4° (L)), explaining the observed anisotropy in the electrical and mechanical properties of the rolled graphite foils. X-ray analysis confirmed the preferred nanocrystallite orientation and anisotropy coefficients (A) using Kearns parameters, which aligned well with experimental measurements (for L series foils calculated as: A0.70 = 1.05, A1.30 = 1.10, and A1.75 = 1.16). These calculated values corresponded well with the experimental measurements of specific electrical conductivity, where the anisotropy coefficient changed from 1.00 to 1.16 and mechanical properties varied from 0.98 to 1.13.
摘要：
不同厚度的柔性石墨箔（S=282±5μm，M=494±7μm,L=746±8μm），使用硝酸盐法获得的初始密度为0.70g/cm3。研究了这些箔的比电导率和热导率。随着密度从0.70g/cm3增加到1.75g/cm3，由于石墨箔的轧制，比电导率从69kS/m增加到192kS/m，热导率从109增加到326W/（m·K）。研究表明，电导率和各向异性取决于形状，定位,和热膨胀石墨（TEG）介观颗粒的接触面积（介观结构因子），和纳米微晶的晶体结构（纳米结构因子）。提出的细观结构模型解释了这些增加，密度更大的箔片显示为细长的，狭窄的TEG颗粒和更大的接触面积，由电子显微镜结果证实。对于200和750μm厚的石墨箔，密度增加导致更大的相干散射区域，可能是由于石墨介孔颗粒在机械作用下的旋转，而密度>1.7g/cm3的较薄的箔（<200μm）显示出增加的塑性变形，由相干散射区域尺寸的急剧减小表示。这从取向差角度随密度增加而减小也是明显的。与横向（TD）相比，沿轧制方向轧制减小的纳米微晶取向角（对于1.75g/cm3密度ΔMA=1.2°（S），2.6°(M),和2.4°(L))，解释了在轧制石墨箔的电气和机械性能中观察到的各向异性。X射线分析使用Kearns参数证实了优选的纳米微晶取向和各向异性系数（A），与实验测量结果吻合良好（对于L系列箔，计算为：A0.70=1.05，A1.30=1.10和A1.75=1.16）。这些计算值与比电导率的实验测量值非常吻合，其中各向异性系数从1.00变化到1.16，机械性能从0.98变化到1.13。
