Search For Cathode Materials Research Articles

Enhanced ORR catalytic activity of rare earth-doped Gd oxide ions in a CoFe2O4 cathode for low-temperature solid oxide fuel cells (LT-SOFCs)

The search for cathode materials with fast oxygen reduction reaction (ORR) catalytic activities and high ionic conductivity is the key obstacle to SOFCs commercialization and its operation at low temperatures. In order to search for a cathode with enhanced catalytic functionality, herein we report a single-phase CoFe2O4 (CFO) and CoGd0.2Fe1.80O4 (CGFO), which can be employed as an active cathode to improve electrocatalytic ORR functionalities at low temperature. It is found that CGFO having enriched oxygen vacancies exhibits the least polarization resistance (RP) of 0.42 Ωcm2 compared to the pure CFO which shows polarization resistance of 0.56 Ω cm2 under H2/air conditions. Furthermore, Density functional theory (DFT) calculations also show that the number of oxygen vacancies increases in the CGFO sample. The CGFO cathode based SOFC achieved a peak power density (PPD) of 475 mW/cm-2 at 550 °C, higher than CFO cathode based SOFC which delivers 315 mW/cm-2. Subsequently, fast ORR catalytic functionalities and least electrode polarization resistance make spinel ferrite based CGFO a potential cathode for low-temperature SOFCs.

Macroporous vanadium dioxide–reduced graphene oxide microspheres: Cathode material with enhanced electrochemical kinetics for aqueous zinc-ion batteries

Aqueous zinc-ion batteries are being extensively investigated owing to their safe operating conditions. Therefore, the search for cathode materials with optimum composition and nanostructure that enable high zinc-ion storage performance is underway. This study introduces a procedure for the formation of vanadium dioxide-nanoflake-reduced graphene oxide composite (P-VO2@rGO) microspheres with open pores through spray pyrolysis. Spherical cathode materials are formed by spray pyrolysis through the addition of polystyrene nanobeads and graphene oxide nanosheets in the spray solution. This enabled the formation of porous and crumpled graphene oxide microspheres, wherein thin VO2 nanoflakes are anchored. As a cathode for zinc-ion batteries, P-VO2@rGO exhibits a high rate capability (159 mA h g−1; current density = 5.0 A g−1) and stable cycle performance for the 300 cycles at 1.0 A g−1. To discern the synergistic effect of the reduced graphene oxide (rGO) and 3D-porous structure with a small crystal size on the zinc-ion storage, control samples (VO2-rGO composite and porous VO2 microspheres) are synthesized and tested as cathodes for zinc-ion batteries. The synergistic effect of compositing rGO and introducing porous structure with small crystal size enables high reversible capacity and enhances electrochemical kinetics of the electrode.

Delocalized Li@Mn6 superstructure units enable layer stability of high-performance Mn-rich cathode materials

<h2>Summary</h2> The search for cathode materials with high energy density, long-term cycling stability, and low cost is one of the most important challenges for current lithium-ion batteries. To address the structural instability in Mn-rich layered cathodes, we demonstrate herein through thorough experimental and theoretical studies that delocalizing Li@Mn₆ superstructure units within transition-metal layers is an effective strategy to enhance the layer stability of a Li-excess Mn-rich layered oxide (LMRO) cathode. The delocalized Li@Mn₆ superstructure units can not only increase the Mn valence to inhibit the adverse Jahn-Teller effect but also harness the anionic redox activity with suppressed O–Mn₀ species. Benefited from its stable layered structure, the LMRO cathode can retain a high capacity and energy density of 251 mA h g⁻¹ and 791 W h kg⁻¹, respectively, after 100 cycles with nearly 100% retention. This work provides a feasible route to develop the high-performance layered cathodes with stable anionic redox chemistry.

BaFe0.6Ce0.1Co0.3O3-δ as a high-performance cathode for intermediate-temperature solid oxide fuel cells

The search for cathode materials with high oxygen reduction reactions activity is a key step toward reducing the operation temperature of solid oxide fuel cells. We report a novel perovskite-type BaFe0.6Ce0.1Co0.3O3-δ (BFCC) cathode, which exhibits outstanding activity for oxygen reduction reactions and yields low interfacial resistances, e.g., 0.113Ωcm2 at 650°C. The SEM results show that BFCC is chemically, thermally compatible with Ce0.8Sm0.2O2-δ (SDC) at operation temperatures. The tri-layer single cells of Ni–SDC|SDC|BFCC are operated from 500 to 650°C with humidified hydrogen (∼ 3% H2O) as fuel and oxygen as oxidant. It shows excellent power densities of 1422mWcm−2 at 650°C and 1086mWcm−2 at 600°C. Preliminary results demonstrate that the BFCC is a promising cathode material for reduced-temperature solid oxide fuel cells.