Development of Sustainable Electrochemical Supercapacitors using Food Waste

Research Question: Can food waste be used as a sustainable and cost-effective alternative material to produce electrochemical capacitors?
Development of Sustainable Electrochemical Supercapacitors using Food Waste
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Project Outline: Advances in renewable energy and environmentally friendly technologies such as electric vehicles have led to a need for better, more sustainable energy storage devices [1]. Currently, the most widely used energy storage devices, particularly in portable devices and vehicles are batteries. However, batteries are often produced by methods that are not environmentally friendly, are difficult to recycle or use non-renewable resources. More recently, supercapacitors have increasingly been deployed as energy storage devices. They have the double advantage of 1000s more charge/discharge cycles and faster charging and discharging than batteries [2].  

Electric double-layer capacitors, a type of supercapacitor using electrodes based on activated carbon, show great promise as an energy storage material of the future [3]. They can be made from readily available carbon-based materials. Furthermore, those made from biomass have been shown to be highly effective and sustainable. Heat treatment of biomass generates activated carbon, which, when applied to electrodes, allows for the production of excellent electrochemical capacitors. The key reasons for this are that the activated carbon has a high surface area, hierarchical porosity and relative chemical inertness [4].

The goal of this research proposal is to explore the potential of utilising food waste as a sustainable and cost-effective alternative material to for the production of electrochemical capacitors. Traditional supercapacitor materials such as activated carbon and graphene can be expensive and environmentally damaging to source. Food waste, on the other hand, is a readily available and sustainable resource that can be used as an alternative material for capacitor creation. Additionally, using food waste, rather than leaving it to decompose reduces the production of methane, a harmful greenhouse gas. 

The requirements for electrochemical capacitors are well established, and so target materials will undergo processing to convert them to activated carbon, and then they will be subjected to nitrogen adsorption analysis to determine the specific surface area of reactivity. Another important factor in the efficacy of such materials is the porous structure, so Scanning Electron Microscopy and Energy Dispersive X-ray analysis will also be undertaken for any material that meets the target range. 

The target material will then be assembled into a capacitor, with an aqueous electrolyte and binder to be tested as a capacitor. As well as the practical viability using physics and chemistry, research will also be undertaken into the availability and economics of using and processing such waste materials on a commercial scale.

Ultimately, the overarching aim is to develop a scalable electrochemical capacitor system (electrode, electrolyte and binder) that is created from recycled biomaterials whilst delivering the required performance characteristics as a sustainable energy storage device.   If successful, this research could lead to the creation of a new industry that not only addresses the issue of food waste but also provides a solution for the energy storage problem. This will be beneficial for both the environment and economy by reducing the carbon footprint, creating jobs and reducing waste management costs.

Objectives of the project:

  1. Establish standard method of creating activated carbon from biomass

  2. Determine the acceptance criteria based on established literature and current benchmarks for commercial capacitors. 

  3. Determine test method and success criteria for the biomass in terms of its performance characteristics, and suitability for an electrochemical capacitor electrode.

  4. Validate test methods using commercial products that have established performance test data.

  5. Identify target food waste materials through literature searches for screening as part of this study, whilst considering their availability, stability and their storage requirements.

  6. Develop the experimental method for creating activated carbon from food waste, starting with established methods from the literature.

  7. Evaluate the performance of these potential food waste materials using the validated test methods as electrochemical capacitors against the benchmarked commercially available traditional capacitor materials.

  8. Identify any potential food waste options that can provide at the very least parity in terms of electrochemical capacity performance versus the commercial traditional capacity materials.

  9. Investigate the economic and environmental opportunity of utilising food waste as a material for capacitor creation.

Further work (possibly in year 2):

  1. Develop a compatible, environmentally friendly electrolyte for use with the identified biomass electrode.

  2. Develop a compatible and environmentally friendly binder system for the electrochemical capacitor as currently fluorinated polymers are used as binders, and they are environmentally hazardous in both production and ultimately in their degradation.

(Image of Activated Carbon Sources[2])

References

  1. R. B. Schainker (2004) "Executive overview: energy storage options for a sustainable energy future," IEEE Power Engineering Society General Meeting, Denver, CO, USA, 2004, pp. 2309-2314 Vol.2, doi: 10.1109/PES.2004.1373298.
  2. Burke,A. (2000) Ultracapacitors: why, how, and where is the technology, Journal of Power Sources, Volume 91, Issue 1, Pages 37-50, ISSN 0378-7753
  3. Krzysztof, Platek, Piwek and Frackowiak (2018) Sustainable materials for electrochemical capacitors, Materials Today, Vol 21, No. 4, May.
  4. Guo, Liu, Yin, Xiao-Xiao Zhang, Shan and Duan (2023) Preparation of supercapacitor carbon materials from food waste via low-temperature pyrolysis, Journal of Analytical and Applied Pyrolysis, Available online 24 January 2023, 105880.

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