Enhanced thermal conductivity in natural graphite-based multigraphene materials

We report natural graphite-based multigraphene materials with thermal conductivity enhanced by 20% compared to our previously reported results. The influence of density on the thermal conductivity of these materials was examined. Increasing the density from 1.0 to 1.8 g cm−3 leads to a more than twofold enhancement in thermal conductivity, surpassing the 600 W m−1 K−1 threshold. This result is attributed to a reduction in crystallite misorientation angles to below 15° and a two-order-of-magnitude decrease in defect density from 2 × 10−2 % to 4 × 10−4 %. A multiscale thermal conductivity model for such multigraphene materials was developed, calibrated, and assessed using experimental x-ray diffraction data and electrical conductivity measurements.