Advancements in Aqueous Supercapacitors with DyFeO3

Aqueous supercapacitors (SCs) are devices that store electrical energy. They are considered valuable due to their ability to charge and discharge quickly and their long lifespan. However, these devices face some challenges. One major issue is their limited voltage and Energy Density because water can break down at high voltages. This is a big problem since it restricts how much energy these SCs can store and deliver.

#The Role of DyFeO3

To overcome this challenge, we have developed a type of aqueous supercapacitor using a material called DyFeO3 as the electrodes. DyFeO3 is a type of perovskite oxide with useful properties for energy storage. It has a special structure that allows it to work well in storing electrical energy.

We created a specific type of supercapacitor known as an aqueous symmetric supercapacitor (ASSC). This type uses the same material for both the positive and negative electrodes. Our ASSC operates with a 0.5 M sodium sulfate (Na2SO4) water-based electrolyte and can work where other supercapacitors struggle.

#Achieving High Performance

We observed impressive results from our ASSC. It can function at a high voltage of 2.5 V, providing an energy density of 41.81 Wh/kg at a power density of 1250 W/kg. It can recharge and discharge over 5000 cycles while keeping 94% of its capacity.

To push this further, we introduced a small amount of acetonitrile into the aqueous electrolyte, raising the energy storage capability even more. When we added 20% acetonitrile, the voltage range increased to 3.1 V, and the energy density climbed to 84.43 Wh/kg at a power density of 1550 W/kg. This was a notable improvement and showed great stability during long testing periods.

#Why DyFeO3 Works Well

DyFeO3 is particularly effective for several reasons. It has a porous structure that increases the surface area available for storing charge. This means that more ions can interact with the material, which is essential for energy storage. Moreover, DyFeO3 contains oxygen vacancies, which enhance its reactivity and allow for better ion movement.

The unique properties of DyFeO3, including its structure and the behavior of the ions it contains, make it a strong candidate for use in supercapacitors. It allows for both electrochemical double-layer capacitance and pseudocapacitance, which together improve energy storage capacity.

#Choosing the Right Electrolyte

The type of electrolyte used in a supercapacitor is crucial. While nonaqueous electrolytes are commonly used because they can operate at higher voltages, they bring problems like being flammable and costly. In contrast, aqueous electrolytes, like the sodium sulfate solution we used, provide a safer and cheaper alternative.

By using a 0.5 M sodium sulfate electrolyte, we ensured that our supercapacitor operates safely. The choice of this electrolyte also improved ionic conductivity, which is essential for good energy storage performance.

#Expanding the Voltage Range

Various strategies can be employed to widen the operational voltage range of aqueous electrolytes. Previous attempts have included modifying pH levels or adding different materials, but they often yielded limited results.

Our work focused on adding acetonitrile to the electrolyte, which was a simple yet effective approach. This addition not only increased the voltage range but also helped reduce the tendency for water to split into hydrogen and oxygen at higher voltages.

#Testing and Performance

We conducted numerous tests to evaluate the performance of our ASSCs. Using cyclic voltammetry and other electrochemical techniques, we gathered data showing how well our devices operated.

The tests confirmed that our ASSC with DyFeO3 outperformed many others. The energy and Power Densities achieved were much higher than those in many existing systems. For example, when tested, our ASSC maintained strong performance even at high charging and discharging rates.

#Durability and Stability

Durability is critical for energy storage devices. Our ASSCs showed remarkable stability during extended testing. After operating for a long time, they retained a large percentage of their capacitance and maintained high efficiency.

Through stretch testing at different temperatures, we found that while performance dipped at extreme temperatures, our devices still performed well within a wide range of conditions.

#Comparisons with Other Systems

When compared with traditional energy storage systems, our ASSC performed very well. Devices created using other materials often showed lower efficiency and stability. For example, while one highly concentrated electrolyte system only retained about 66% of its capacitance after extensive cycling, our supercapacitor maintained over 90% effectiveness.

This differentiated our ASSC in both performance and cost-efficiency, showcasing that DyFeO3 is a strong candidate for future energy storage solutions.

#Charge Storage Mechanism

Understanding how our supercapacitor stores energy helps explain its effectiveness. When voltage is applied, ions from the electrolyte move toward the electrodes. This movement creates a structure called an electric double layer, which is important for energy storage.

The porous structure of DyFeO3 helps the ions enter the material, enhancing charge storage capacity. The addition of acetonitrile also alters how ions interact within the electrolyte, allowing for better overall performance.

#Conclusion

In summary, we have developed a new type of aqueous symmetric supercapacitor that uses DyFeO3 as an electrode material. Our findings indicate that this material provides high performance, durability, and cost-effectiveness, making it a promising candidate for future energy storage applications.

By utilizing a simple aqueous electrolyte and adding a small amount of acetonitrile, we successfully expanded the operational voltage range and improved energy storage capabilities. This advancement paves the way for improved energy storage devices that can be used in various applications, from electric vehicles to renewable energy systems.

Ongoing research will continue to optimize and explore the potential of DyFeO3 in energy storage technology, paving the way for a more sustainable future.