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With the increase in heat power density in modern integrating electronics, thermal interface materials (TIM) that can efficiently fill the gaps between the heat source and heat sinks and enhance heat dissipation are urgently needed owing to their high thermal conductivity and excellent mechanical durability. Among all the emerged TIMs, graphene-based TIMs have attracted increasing attention because of the ultrahigh intrinsic thermal conductivity of graphene nanosheets. Despite extensive efforts, developing high-performance graphene-based papers with high through-plane thermal conductivity remains challenging despite their high in-plane thermal conductivity. In this study, a novel strategy for enhancing the through-plane thermal conductivity of graphene papers by in situ depositing AgNWs on graphene sheets (IGAP) was proposed, which could boost the through-plane thermal conductivity of the graphene paper up to 7.48 W m−1 K−1 under packaging conditions. In the TIM performance test under actual and simulated operating conditions, our IGAP exhibits strongly enhanced heat dissipation performance compared to the commercial thermal pads. We envision that our IGAP as a TIM has great potential for boosting the development of next-generation integrating circuit electronics. [ABSTRACT FROM AUTHOR]

Comprehensive Summary: As the power density of electronic devices increases, there has been an urgent demand to develop highly conductive polymer composites to address the accompanying thermal management issues. Due to the ultra‐high intrinsic thermal conductivity, graphene is considered a very promising filler to improve the thermal conductivity of polymers. However, graphene‐based polymer composites prepared by the conventional mixing method generally have limited thermal conductivity, even under high graphene loading, due to the failure to construct efficient heat transfer pathways in the polymer matrix. Here, a spiral graphene framework (SGF) containing continuous and highly ordered graphene microtubes was developed based on a modified CVD method. After embedding into the epoxy (EP) matrix, the graphene microtubes can act as efficient heat pathways, endowing the SGF/EP composites with a high through‐plane thermal conductivity of 1.35 W·m−1·K−1 at an ultralow graphene loading of 0.86 wt%. This result gives a thermal conductivity enhancement per 1 wt% filler loading of 710%, significantly outperforming various graphene structures as fillers. In addition, we demonstrated the practical application of the SGF/EP composite as a thermal interface material for efficient thermal management of the light‐emitting diode (LED). [ABSTRACT FROM AUTHOR]

Graphene is usually embedded into polymer matrices for the development of thermally conductive composites, preferably forming an interconnected and anisotropic framework. Currently, the directional self‐assembly of exfoliated graphene sheets is demonstrated to be the most effective way to synthesize anisotropic graphene frameworks. However, achieving a thermal conductivity enhancement (TCE) over 1500% with per 1 vol% graphene content in polymer matrices remains challenging, due to the high junction thermal resistance between the adjacent graphene sheets within the self‐assembled graphene framework. Here, a multiscale structural modulation strategy for obtaining highly ordered structure of graphene framework and simultaneously reducing the junction thermal resistance is demonstrated. The resultant anisotropic framework contributes to the polymer composites with a record‐high thermal conductivity of 56.8–62.4 W m−1 K−1 at the graphene loading of ≈13.3 vol%, giving an ultrahigh TCE per 1 vol% graphene over 2400%. Furthermore, thermal energy management applications of the composites as phase change materials for solar‐thermal energy conversion and as thermal interface materials for electronic device cooling are demonstrated. The finding provides valuable guidance for designing high‐performance thermally conductive composites and raises their possibility for practical use in thermal energy storage and thermal management of electronics. [ABSTRACT FROM AUTHOR]

With the increasing power density of electrical and electronic devices, there has been an urgent demand for the development of thermal interface materials (TIMs) with high through-plane thermal conductivity for handling the issue of thermal management. Graphene exhibited significant potential for the development of TIMs, due to its ultra-high intrinsic thermal conductivity. In this perspective, we introduce three state-of-the-art graphene-based TIMs, including dispersed graphene/polymers, graphene framework/polymers and inorganic graphene-based monoliths. The advantages and limitations of them were discussed from an application point of view. In addition, possible strategies and future research directions in the development of high-performance graphene-based TIMs are also discussed. [ABSTRACT FROM AUTHOR]

[Display omitted] • Size-dependent assembly of graphene sheets constructs vertical heat pathways across the graphene paper. • GHGP exhibits both high through-plane thermal conductivity and good compressibility. • The cooling efficiency of GHGP was 2.2 times that of the state-of-the-art commercial TIM. Graphene-based papers have recently triggered considerable interests in developing the application as thermal interface materials (TIMs) for addressing the interfacial heat transfer issue, but their low through-plane thermal conductivity (κ ⊥), resulting from the layer-by-layer stacked architecture, limits the direct use as TIMs. Although various hybrid graphene papers prepared by combining the graphene sheets and the thermally conductive insertions have been proposed to solve this problem, achieving a satisfactory κ ⊥ higher than that of commercial TIMs (>5 W m−1 K−1) remains challenging. Here, a strategy aimed at the construction of heat pathways along the through-plane direction inside the graphene paper for achieving a high κ ⊥ was demonstrated through the simultaneous filtration of graphene sheets with two different lateral sizes. The as-prepared graphene paper presented a hierarchical structure composed of loosely stacked horizontal layers formed by large graphene sheets, intercalated by a random arrangement of small graphene sheets. Due to the heat pathways formed by small graphene sheets along the through-plane direction, the hierarchically structured graphene paper exhibited an improved κ ⊥ as high as 12.6 W m−1 K−1 after a common graphitization post-treatment. In the practical test, our proposed paper as an all-graphene TIM achieved an enhancement in cooling efficiency of ≈ 2.2 times compared to that of the state-of-the-art TIM, demonstrating its superior performance to meet the ever-increasing heat dissipation requirement. [ABSTRACT FROM AUTHOR]