Sequentially bridged MXene platelets for strong high‐temperature EM‐IR bi‐stealth sheets

Abstract Combination of flexible multifunctional stealth technology properties such as electromagnetic (EM) and infrared (IR) stealth is crucial to the development of aerospace, military, and electronic fields, but the synthesis technology still has a significant challenge. Herein, we have successfully designed and synthesized highly flexible MXene@cellulose lamellae/borate ion (MXCB) sheets with strong high‐temperature EM‐IR bi‐stealth through sequential bridging of hydrogen and covalent bonds. The resultant MXCB sheets display high conductivity and good mechanical features such as flexibility, stretchability, fatigue resistance, and ultrasonic damage. MXCB sheets have a high tensile strength of 795 MPa. Furthermore, MXCB sheets with different thicknesses indicate exceptional high‐temperature thermal‐camouflage characteristics. This reduces the radiation temperature of the target object (>300 °C) to 100 °C. The conductivity of MXCB sheet with 3 μm thickness is 6108 S/cm and the EM interference (EMI) shielding value is 39.74 dB. The normalized surface‐specific EMI SE absolute shielding effectiveness (SSE/t) is as high as 39312.78 dB·cm2/g, which remained 99.39% even after 10,000 times repeated folding. These multifunctional ultrathin MXCB sheets can be arranged by vacuum‐assisted induction to develop EM‐IR bi‐stealth sheet