A team of scientists from India, Bangladesh, the Czech Republic, and Korea has presented research into using polymer composites with quantum dots to develop supercapacitors. They have published the results of their study in the journal Polymers this week.
Study: Polymer Composites with Quantum Dots as Potential Electrode Materials for Supercapacitors Application: A Review. Image Credit: Tayfun Ruzgar/Shutterstock.com
Beyond Fossil Fuels: The Road to a More Sustainable Future
Fossil fuels have spurred rapid development in modern society and industry, but their use comes with a huge cost in terms of greenhouse gas emissions and environmental damage. The growing evidence for anthropogenic climate change has facilitated the urgent need to switch to renewable energy sources such as wind, solar, hydroelectric, geothermal, and biomass. Furthermore, resource scarcity has raised the prospect of a future energy crisis if business-as-usual models are maintained.
Amongst the proposed technologies to ensure a green, sustainable future, batteries, supercapacitors, and fuel cells have been the subject of intense research over the past few decades. This is owing to characteristics such as excellent electrochemical properties, device performance, and energy density.
Batteries have emerged as a forerunner in this technological revolution due to their more reliable energy density compared to other devices, but their cost is higher than alternatives such as supercapacitors. Additionally, their cycle performance can be more limited, meaning that they may not be able to meet the demands of advanced electronics. Moreover, they are limited by safety issues, low flexibility, and weight.
Supercapacitors, on the other hand, overcome the issues with traditional batteries. Small, compact supercapacitors can be used as flexible energy storage devices, and solid-state, semi-solid, and gel-electrolyte supercapacitors can overcome safety issues. These next-generation energy storage devices are generally divided into electric double layer supercapacitors, pseudo-supercapacitors, faradic-supercapacitors, and hybrid supercapacitors.
Improving Supercapacitors with Nanomaterials and Advanced Materials
Supercapacitor design can benefit from the incorporation of advanced nanomaterials, helping to realize more compact and economical devices. In recent years, there has been a focus on developing their working mechanisms rather than individual components. Harmonizing these two elements is key to improving their efficiency.
Supercapacitors are composed of two electrodes with an electrolyte between them, with a separator inserted between the negative and positive electrodes to isolate them. Electrodes are generally made of activated carbon. The electrolyte is typically organic or aqueous. Several electrolytes have been explored in recent studies, with restrictions on the use of toxic materials. Research has also recently focused on the valorization of waste materials in supercapacitors.
Amongst the various nanomaterials explored for use in supercapacitors, quantum dots have emerged as attractive candidates. Favorable characteristics of these materials include an enriched surface area, easy doping, solubility in both aqueous and non-aqueous solvents, good functionalization, and their quantum confinement effect. Quantum dots have been widely proposed for applications such as bio-sensing, bio-imaging, photovoltaics, and fuel cells.
Quantum Dots , what are they? How they work and what their Applications?
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Characteristics such as their larger surface-to-volume ratio, high concentration of edge atoms, and highly dense active sites aid the transportation and movement activity of ions, especially their adsorption and desorption. The enhanced surface area of quantum dots is especially beneficial for supercapacitor applications. Moreover, their ability to coalesce with other nanomaterials facilitates the synthesis of composite nanomaterials. Quantum dots can significantly improve the storage and electrochemical properties of supercapacitors.
The study published this week in Polymers has investigated different types of quantum dots, discussing their benefits and drawbacks and exploring several supercapacitor setups incorporating these nanomaterials. Additionally, the authors have focused on different synthesis techniques such as electrochemical processes, solvothermal/hydrothermal processes, and microwave synthesis to prepare quantum dots with different morphologies and sizes. Quantum dots can be prepared from biomass and waste materials, conferring benefits in terms of sustainability.
The study has also investigated the advantages that polymer composites can bring to supercapacitor design. It has been noted that these materials, whilst exhibiting attractive properties such as excellent specific energy and faster redox reactions, these materials are limited by factors such as swelling during repeated charge-discharge cycles.
The authors have noted that incorporating quantum dots into conducting polymeric materials has demonstrated promising improvements for the materials. They have noted the development of organic polymer composites with quantum dots that possess different morphologies which have seen application in technologies such as solar cells, memory devices, and biological sensors. Quantum dots can be incorporated into conductive polymeric composites to improve the cycle life and mechanical stability of supercapacitor electrodes.
Compositing carbonaceous compounds with polymers has been proposed as a strategy to overcome challenges with polymeric materials for use as electrodes in supercapacitors. This approach improves characteristics such as thermal stability, conductivity, and intermolecular chain reactions, conferring enhanced properties for energy storage devices. Whilst there is significant potential for the use of quantum dots and polymeric materials in supercapacitors, challenges exist. These are discussed in depth in the study.
Reporting on recent advances in research in the area, the authors have provided a comprehensive analysis of the current and future perspectives on the use of conductive polymeric materials and quantum dots as electrode materials for supercapacitors. Further research is necessary to realize the large-scale industrial application of these materials.
Das, H.T et al. (2022) Polymer Composites with Quantum Dots as Potential Electrode Materials for Supercapacitors Application: A Review [online] Polymers 14(5) 1053 | mdpi.com. Available at: https://www.mdpi.com/2073-4360/14/5/1053
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