Flexible graphite film (FGF), as a traditional interface heat dissipation material, has high anisotropy. It is a challenge to enhance both in-plane and through-plane thermal conductivity of FGF. For this reason, the effects of oxygen content, layer spacing, density and particle size on the in-plane and through-plane thermal conductivity of FGF were studied by both molecular simulation and experimental investigation. The simulation results indicate that the ways to improve the thermal conductivity of FGF include reducing oxygen content and layer spacing, increasing the density and matching the size of graphite sheets. The FGF prepared from room temperature exfoliated graphite (RTFGF) has a wide range of adjustable density (1.3–2.0 g/cm³) and thickness (50–400 μm). The thermal conductivity of the RTFGF is significantly improved after heat treatment owing to reduced oxygen content and layer spacing, which is consistent with the simulation results. Moreover, RTFGF with both high in-plane (518 W·m⁻¹·K⁻¹) and through-plane (7.2 W·m⁻¹·K⁻¹) thermal conductivity can be obtained by particle size matching of graphite.

Exfoliated graphite (EG) is promising oil sorbent as well as an intermediate product for the preparation of flexible graphite films (FGFs). It has been a critical challenge to energy conservation and pollution abatement for the traditional EG production technique. Here, we propose a simple and effective preparation method to acquire EG in which flake graphite is intercalated and exfoliated at room temperature, not involving any pollutant emission. The influence factors in the preparation process were explored, such as the amount of H₂SO₄ and H₂O₂, the temperature for the preparation of room temperature exfoliated graphite (RTEG). In contrast to the EG by high temperature exfoliation (HTEG), RTEG exhibits a homogeneous structure and a significantly increased volume and surface area. Moreover, EG blocks with high oil sorption capacity and excellent reuse performance can be obtained by RTEG method. Especially, FGFs fabricated by RTEG has high flexibility, thermal conductivity and electrical conductivity. It suggests that this environment-friendly technology is suitable for large-scale industrial implementation of graphite-based oil sorbents and flexible materials.