Polyaniline‐Derived Heteroatom‐Doped Carbon‐Encapsulated Fe ₂ O ₃ / CN for Durable Supercapacitors

Hematite (α‐Fe 2 O 3 ) is a promising supercapacitor anode due to its high theoretical capacity, low cost, and eco‐friendliness, yet its application is hindered by poor conductivity and structural instability. Herein, a unique Fe 2 O 3 composite encapsulated within a polyaniline‐derived N, S, Cu‐doped carbon layer was fabricated on carbon cloth via an integrated method involving hydrothermal growth, Cu 2+ ‐catalyzed electrodeposition, and carbonization. This conformal carbon sheath acts as a synergistic conductive network, mechanical buffer, and source of active sites. The optimized Fe 2 O 3 /CN electrode exhibits a high specific capacitance of 517.15 F g −1 at 1 A g −1 and dramatically enhanced cycling stability with 92.48% retention after 5000 cycles, far exceeding pure Fe 2 O 3 (51.15%). The assembled solid‐state asymmetric supercapacitor (Fe 2 O 3 /CN@CC//PANI@CC) delivers an energy density of 33.82 Wh kg −1 at 737.5 W kg −1 and maintains 87.57% capacity after 5000 cycles. This work demonstrates an effective polymer‐derived carbon coating strategy for developing durable, high‐performance metal oxide‐based electrodes.