A Self‐Supporting Film Electrode of Ball‐Shaped Mn‐Doped NiCoP Grown on 3D Walnut Shell‐Derived Carbon for High‐Performance Supercapacitors and Aqueous Zinc‐Ion Batteries

There are few reports on materials that can serve as electrodes for both supercapacitors and aqueous zinc‐ion batteries. Bimetallic phosphides exhibit high conductivity and excellent structural plasticity. Hence, a self‐supporting film electrode of ball‐shaped Mn‐doped NiCoP grown on 3D walnut shell‐derived carbon (WSC‐N/O@Mn‐NiCoP) was prepared in this work. The results indicate that the WSC‐N/O@Mn‐NiCoP delivers a high specific capacitance of 1972 F g −1 at 1.0 A g −1 . Furthermore, WSC‐N/O@Mn‐NiCoP can be used as an electrode for both supercapacitors and aqueous zinc‐ion batteries. The assembled WSC‐N/O@Mn‐NiCoP//WSC‐N/O (ASC) device delivers an energy density of 69.1 Wh kg −1 at 375 W kg −1 , with 85.8% capacitance retention after 8500 cycles. The energy density of Zn//WSC‐N/O@Mn‐NiCoP (AZIBs) achieves an energy density of 148.9 Wh kg −1 at 750 W kg −1 , with 80.6% capacitance retention after 1000 cycles. This excellent performance stems from the fact that biomass carbon provides abundant attachment sites to buffer volume variations and preserve structural integrity, while manganese doping activates multimetal redox reactions, delivering high capacity and ultra‐long cycle life. In short, this work provides a viable strategy for preparing high‐performance electrode materials.