Millefeuille-like phase change composite with multi-level oriented architecture for efficient thermal management and electromagnetic interference shielding

Exploiting an advanced phase change material (PCM) isochronally combining superior thermal conductivity (TC) and electromagnetic interference shielding efficiency (EMI SE) is in desperate desire but extremely challenging for integrated and high-frequency microelectronics. Herein, inspired by the architecture of millefeuille cake, a novel multi-level assembly design of microlaminated graphene-carbon/MXene-encapsulated PCM (GCMP), is proposed based on a unique two-step bidirectional freeze-casting (BFC) and compression routine. Biaxial-oriented graphene-carbon skeleton (rGO-C) is manufactured by 1st BFC and subsequent thermal annealing. In 2nd BFC, MXene and poly(vinyl alcohol), containing hydrogen-bond binding sites, are selected as "physical crosslinking agents" to in-situ encapsulate polyethylene glycol on the surfaces of rGO-C skeleton. Notably, the tailored GCMP achieves ultrahigh in-plane TC of 20.96 W m−1 K−1 and admirable EMI SE up to ∼70.5 dB, together with the available latent heat of 153.8 J cm−3, superior anti-leakage capability, and remarkable thermal reliability. Furtherly, the GCMP-supported devices are separately demonstrated for high-efficiency thermal management in microelectronic cooling and solar-thermoelectric conversion. This work opens a new avenue toward the multi-level micronano structure design of multi-function macro-PCM, which is highly desirable in next-generation electronics, energy storage/conversion systems, aeronautic/military sectors, and artificial intelligence domains.