Biomass-derived porous carbon enables sustainable electromagnetic wave absorption, radar stealth, and energy storage

Integrating sustainable, multifunctional materials into next-generation wearable and implantable medical devices requires simultaneous advances in electromagnetic wave absorption (EMWA) and on-body energy storage. Traditional and synthetic absorbing materials often struggle to adapt to complex EM environments because of narrow absorption bandwidths, complex component optimization, multi-step manufacturing processes, and limited functionality. They can also pose risks for long-term skin contact. To overcome these issues, a cost-effective fabrication process was developed to produce environmentally friendly, lightweight Tasali shells made from a biomass-derived porous carbon composite. This composite features a distinctive structure that creates a strong 3D conductive network, improves heterogeneous interfaces, and enhances its large surface area and multiple loss mechanisms, thereby enhancing its multifunctionality. These various loss mechanisms include conductive loss, polarization loss, and the hierarchical pore structure. Conductive loss arises from the graphitized carbon network, which enables electron flow and the ohmic dissipation of EM energy, while also providing the electrical conductivity (σ) necessary for efficient charge transport in energy storage. The composite achieves improved EMWA performance (RL of −51 dB) within the 5 GHz band at a very thin thickness, and a radar cross-section (RCS) of 25.7 dB m 2 at 30º, indicating stealth capabilities. Moreover, it delivers high energy storage performance, with a specific capacitance of 781.6 F/g, a coulombic efficiency of 80.3%, and a capacitance retention of 74.2%, demonstrating excellent long-term electrochemical stability over 1000 cycles. This research presents a practical approach for eco-friendly smart wearable devices that handle responses and ensure personal safety.