Two-dimensional materials with optical turnability have wide prospect in related applications such as electrochromic coating and thermal camouflage. Here we report a Li-intercalated ultrathin graphite device with tunable visible-near-infrared reflectivity. After Li-ion intercalation, the Fermi surface of ultrathin graphite will move to a higher level, which prevents the interband optical transitions below it. Therefore, it is possible to change the absorptivity or emissivity of ultrathin graphite through reversible Li-ion intercalation, which accomplishes the modification to reflectivity indirectly. In our experiment, the strong fluorescence background and Peak shifts in Raman spectra, as well as the enlarged layer spacing in XRD spectra, together confirmed that Li-ions were successfully intercalated into the graphite layers. The relative reflectivity of ultrathin graphite increased sharply in a wide range from 460 nm to 1500 nm after complete Li-ion intercalation. At a typical near-infrared wavelength 1500 nm for instance, the relative reflectivity is 0.28 for pristine graphite while 0.70 for fully lithiated graphite. Such reversible intercalated modulation in visible-near-infrared reflectivity of ultrathin graphite might provide a new way to design electrochromic coating, thermal camouflage or radar stealth systems, which also promotes further understanding and optical applications of graphene and other 2D materials.

具有光学转向性的二维材料在电致变色涂层和热伪装等相关应用中具有广阔的前景。在这里，我们报告了一种具有可调可见光-近红外反射率的嵌锂超薄石墨器件。锂离子嵌入后，超薄石墨的费米面将移动到更高的水平，从而防止其下方的带间光学跃迁。因此，可以通过可逆的锂离子嵌入来改变超薄石墨的吸收率或发射率，间接完成对反射率的改变。在我们的实验中，拉曼光谱中的强荧光背景和峰位移，以及 XRD 光谱中扩大的层间距，共同证实了锂离子成功嵌入石墨层中。完全嵌入锂离子后，超薄石墨的相对反射率在 460 nm 到 1500 nm 的宽范围内急剧增加。例如，在典型的近红外波长 1500 nm 下，原始石墨的相对反射率为 0.28，而完全锂化石墨的相对反射率为 0.70。超薄石墨可见-近红外反射率的这种可逆插层调制可能为设计电致变色涂层、热伪装或雷达隐身系统提供一种新方法，这也促进了对石墨烯和其他二维材料的进一步理解和光学应用。70 代表全锂化石墨。超薄石墨可见-近红外反射率的这种可逆插层调制可能为设计电致变色涂层、热伪装或雷达隐身系统提供一种新方法，这也促进了对石墨烯和其他二维材料的进一步理解和光学应用。70 代表全锂化石墨。超薄石墨可见-近红外反射率的这种可逆插层调制可能为设计电致变色涂层、热伪装或雷达隐身系统提供一种新方法，这也促进了对石墨烯和其他二维材料的进一步理解和光学应用。