Electrochemical and Electromagnetic Shielding Properties of Free‐Standing and Heteroatom Self‐Doped Carbon Nanofiber Webs Derived From Polyazomethine Containing Thiophene Moiety and Ether Linkage

Abstract Free‐standing, heteroatom self‐doped carbon nanofiber (CNF) webs are fabricated for advanced energy storage and electromagnetic interference (EMI) shielding applications. These webs are produced via electrospinning a polyazomethine (PAMTE) precursor incorporating thiophene and ether linkages, followed by carbonization at 700–900 °C. The PAMTE precursor is synthesized through a polycondensation reaction between 2,5‐diformylthiophene and 3,4′‐diaminophenyl ether. The carbonization temperature influences the morphology, composition, and electrical and electrochemical properties of the CNFs. As the temperature increases, the fiber diameter decreases, and the carbon content rise from 83.28 to 86.56 at%. Meanwhile, nitrogen, oxygen, and sulfur content diminishes. Consequently, the CNFs carbonized at 900 °C (PAMTE‐900) exhibit high electrical conductivity of ≈8.82 S cm⁻¹ and good wettability to water. In a symmetric two‐electrode supercapacitor system composed of PAMTE‐900 as free‐standing, binder‐free electrode materials with 1 m H₂SO₄ electrolyte, excellent electrochemical properties are attained, including a specific capacitance of 148 F g⁻¹, an energy density of 19.7 Wh kg⁻¹, and a power density of 249.9 W kg⁻¹ at 0.5 A g⁻¹. Moreover, the system exhibits excellent cycling stability, retaining ≈98.7% of its initial capacitance after 3000 charge–discharge cycles. In addition to its electrochemical properties, PAMTE‐900 demonstrates outstanding EMI shielding effectiveness, with a thickness‐normalized value of ≈117 dB mm⁻¹.