Constructing multi-dimensional alternating layer nested structure for enhancing electromagnetic shielding, thermal management and strain sensing

•The multi-dimensional alternating layer nested (MALN) structure films were fabricated by layer-by-layer assembly.•With a thickness of only 90 μm, the EMI SE and SSE/t of MALN structure films achieve 98.95 dB and 11606.14 dB/g·cm−2.•The “absorption-reflection–absorption” loss path and multiple synergistic loss mechanisms of MALN structure were proposed.•The MALN structure films possess thermal management include thermal conduction, Joule heating, photothermal conversion.•The MALN structure films also have strain sensing capacity to detect bending, pressing, speaking and writing actions. It is imperatively desired to design excellent electromagnetic interference (EMI) shielding and thermal management simultaneously. Herein, fabricating the multi-dimensional alternating layer nested (MALN) structure composite film, which consisted of the alternating multilayer structure constructed by silver nanowires (AgNWs)/cellulose nanofiber (CNF) layer and the graphene nanoplates (GNPs)/CNF layer, the dense conducting networks built by interweaving AgNWs in CNF networks, and the “mille-feuille” structure of GNPs and CNF. The heterogeneous layers of AgNWs/CNF layer and GNPs/CNF layer with significant conductivity differences, as well as the “mille-feuille” structure of CNF and GNPs, provide abundant macro/micro heterogeneous interface polarization losses and multiple reflection losses. Adjusting the addition of AgNWs or GNPs in different layers to form the conductivity gradient, endowing the “absorption-reflection–absorption” loss path and excellent conduction loss of film. Therefore, the MALN structure composite film with a thickness of 90 μm exhibits an impressive EMI shielding efficiency (SE) of 98.95 dB and a specific SE (SSE/t) of 11606.14 dB/g·cm−2, attribute to its excellent conduction loss, abundant macroscopic/microcosmic heterogeneous interfacial polarization losses, multiple reflection losses, and the absorption-reflection–absorption loss path. Meanwhile, the in-plane thermal conductivity (λ∥) and out-plane thermal conductivity (λ⊥) achieve of 8.69 W/(m·k) and 0.16 W/(m·k). Additionally, the obtained film also demonstrates exceptional joule heating, remarkable photothermal conversion, outstanding mechanical properties, and distinguished strain sensing capabilities, which exhibiting significant potential in wearable electronic devices.