Electrochemical Performance of Iron Oxide Nanoflakes on Carbon Cloth under an External Magnetic Field

Effective Energy Storage Performance Derived from 3D Porous Dendrimer Architecture Metal Phosphides//Metal Nitride-Sulfides

The present work addresses the limitations by fabricating a wide range of negative electrodes, including metal nitrides/sulfides on a 3D bimetallic conductive porous network (3D-Ni and 3D-NiCo) via a dynamic hydrogen bubble template (DHBT) method followed by vapour phase growth (VPG) process. Among the prepared negative electrodes, the 3D-Fe3S4-Fe4N/NiCo nanostructure demonstrates an impressive specific capacitance (Cs) of 1125 F g-1 (2475 mF cm-2) at 1 A g-1 with 80% capacitance retention over 5000 cycles. Similarly, a 3D-Mn3P nanostructured positive electrode fabricated via electrodeposition followed by a phosphorization process exhibits a maximum specific capacity (Cg) of 923.04 C g-1 (1846.08 mF cm-2) at 1 A g-1 with 80% stability. A 3D-Mn3P/Ni//3D-Fe3S4-Fe4N/NiCo supercapattery is also assembled, and it shows a notable CS of 151 F g-1 at 1 A g-1, as well as a high energy density (ED) of 51 Wh kg-1,a power density (PD) of 782.57 W kg-1 and a capacitance efficiency of 76% over 10 000 cycles. This may be ascribed to the use of a bimetallic 3D porous conductive template and the attachment of transition metal sulfide and nitride. The development of negative electrodes and supercapattery devices is greatly aided by this exploration of novel synthesis techniques and material choice.

Solvothermal Synthesis and Pyrolysis Toward Heteroatom-Doped Carbon Microspheres for Zinc-Ion Hybrid Capacitors

Heteroatom-doped porous carbon materials have investigated to promote the energy density of zinc-ion hybrid capacitors (ZICs). Yet, the quest for high-performance carbon materials or cathodes brings to light the question of which dopants facilitate fast energy storage kinetics and various types of pseudocapacitive reactions. Investigation of carbon materials with precise quantitative dopants as the key variable represents an effective appropriate approach to comprehending the intricate role of dopants in energy storage areas. Here, a straightforward solvothermal strategy is demonstrated for a variety of pristine and iron-incorporated polymer microspheres, used as precursors for durable spherical carbons intended for cathode applications in ZICs. The strategy effectively governs the incorporation of dopants within the carbon materials, whilewhile maintaining consistent morphology, microtexture, and pore structure across different carbon variations. The synergistic effect of various dopants enhance the pseudocapacitance and facilitate the ion storage process. In consequence, the optimal cathode delivers considerable capacity (178.8 mAh g-1 at 0.5 A g-1), good energy density (120.2 Wh kg-1 at 336 W kg-1), and excellent cycling stability (101.5% capacity retention at 35 000 cycles). The demonstration showcases a viable method for crafting carbon materials with precise dopants to accommodate the zinc anode, thus enabling high-capacity and high-energy ZICs.

Synergistic Effects of Fe2O3 Nanotube/Polyaniline Composites for an Electrochemical Supercapacitor with Enhanced Capacitance

α-Fe₂O₃, which is an attractive material for supercapacitor electrodes, has been studied to address the issue of low capacitance through structural development and complexation to maximize the use of surface pseudocapacitance. In this study, the limited performance of α-Fe₂O₃ was greatly improved by optimizing the nanotube structure of α-Fe₂O₃ and its combination with polyaniline (PANI). α-Fe₂O₃ nanotubes (α-NT) were fabricated in a form in which the thickness and inner diameter of the tube were controlled by Fe(CO)₅ vapor deposition using anodized aluminum oxide as a template. PANI was combined with the prepared α-NT in two forms: PANI@α-NT-a enclosed inside and outside with PANI and PANI@α-NT-b containing PANI only on the inside. In contrast to α-NT, which showed a very low specific capacitance, these two composites showed significantly improved capacitances of 185 Fg⁻¹ for PANI@α-NT-a and 62 Fg⁻¹ for PANI@α-NT-b. In the electrochemical impedance spectroscopy analysis, it was observed that the resistance of charge transfer was minimized in PANI@α-NT-a, and the pseudocapacitance on the entire surface of the α-Fe₂O₃ nanotubes was utilized with high efficiency through binding and conductivity improvements by PANI. PANI@α-NT-a exhibited a capacitance retention of 36% even when the current density was increased 10-fold, and showed excellent stability of 90.1% over 3000 charge–discharge cycles. This approach of incorporating conducting polymers through well-controlled nanostructures suggests a solution to overcome the limitations of α-Fe₂O₃ electrode materials and improve performance.