Article III

Analysis of Graphene Production, Use, and Effectiveness in Solar Cells and Batteries

Photo Source:

https://en.wikipedia.org/wiki/Graphene

Abstract

Graphene is a very durable and remarkably thin derivative of graphite which has been noted for its unique properties when used as a conductor. As such, there is considerable interest in the development of graphene-based technologies for production purposes and use in lithium-ion battery and solar cells. Many methods for mass-producing synthesized graphene have been explored in recent years, but the research field remains restrained by the lack of reliable production methods that can consistently manufacture graphene in large quantities without sacrificing material quality. Future studies may want to consider bridging this gap. Regardless, current research of graphene related technologies is showing significant promise in furthering energy storage and developing material mass-production.


Keywords: Graphene, energy storage, lithium-ion battery, solar cell, technology


Introduction

Graphene is a two-dimensional material comprised of a single layer of carbon atoms.1 Compared to other types of similar materials, graphene is one of the thinnest and sturdiest that has ever been discovered. It conducts electricity exceedingly well and is very effective at conducting heat.2 Although it remains difficult to reliably produce in a mass format, current production techniques are able to yield enough to support research endeavors. As of this review, successful sources of graphene synthesis include mechanical exfoliation, the Hummer’s Method, jet cavitation, and chemical vapor deposition.3 These methods vary in terms of graphene efficacy and purity, but all offer reliable sources of graphene for experimental purposes.

Due to its unique qualities, extensive research has been completed on its potential applications within current technology. Graphene has demonstrated itself very capable of facilitating electric fields, making it suitable for use as an anode material in lithium-ion battery development and research.4 As graphene is also exceedingly resilient and sturdy, it has recently been a focus of research within the solar cell community as a conducting electrode. The main focus of this review will be to survey current graphene research being completed in battery and solar cell technology. Additional research on the production of graphene will also be presented and expanded upon in relevant sections.

Graphene Synthesis and Common Production Methodology

Colloquially, graphene was discovered in 2004 by Andre Geim and Kostya Novoselov in the form of patented nano-plates.2, 4 Before this discovery, records hold that single-layer graphite had been isolated as early as the 1960s.2 Though its history is much longer than most would assume, mass methods of synthesis have yet to be fully realized. Any discovered method that can produce comparatively large amounts of graphene is riddled with oxidation defects, and any method that produces pure graphene cannot effectively mass-produce due to cost and overall feasibility. Regardless, many functional methods have been discovered and are currently used for research purposes (see Table 1). The most commonly used method of synthesis is mechanical exfoliation – a technique that effectively strips graphene layers from a graphite sample. 5 Though popular, mechanical exfoliation yields little graphene when compared to the amount of required graphite, is time consuming, and produces varying degrees of quality.5 Nevertheless, the overall quality and production costs for this method are generally more favored than others.

Another process called the Hummer’s Method applies concentrated chemicals to graphite samples to produce graphene oxide – an oxidized form of graphene.6 Though not ‘pure’ graphene, graphene oxide can sometimes be substituted as an alternative to pure graphene and can be further reduced to create graphene nanosheets.7

One study was able to subject graphene oxide created via Hummer’s Method to ultrasonic vibrations that resulted in reduced graphene oxide (rGO).8 Although rGO still contains defects that separate it from graphene-level purity, its mechanical properties still allow for it to function well as a graphene derivative.5 The effort that is required to produce rGO is not always considered effective, causing chemical exfoliation to be less favored.

Battery Integration and Jet Cavitation

The standard lithium-ion battery has made possible many technological advancements, and increasing its efficacy could lead to greater industrial development in larger technologies such as electric vehicles.9 Recent graphene innovation has led to an interest in using the material as an anode in lithium-ion battery types.10 The material’s unique qualities have been shown to positively impact the anode’s function in battery capacity, reliability, and rechargeability.10 A study that fully utilized a lithium-ion battery design with a low-oxidized, graphene-based anode produced a battery that demonstrated higher battery cyclability, a more functional voltage rating, and higher rate capability when compared to lower-quality graphene or non-graphene-based anodes.11 The study’s results also suggest that this lithium-ion battery design is efficient enough to successfully power technology as large as an electric vehicle.11 Though lithium-ion batteries have already been powering larger technologies for many years, the use of graphene as an anode gave the already-efficient battery an even greater efficiency.

Another study used graphene/graphite nanosheets as composite anodes in lithium-ion battery cells and found a similarly high rate capability and conductivity.12 Compared to a regular graphite anode, the graphene/graphite nanosheet composite demonstrated a much higher charge capacity after 100 complete cycles.12 This study distances itself from the previous by using jet cavitation graphene production, a method of aqueous exfoliation, instead of chemical exfoliation.12 Cavitation uses tiny bubbles that implode, collapse, and release aqueous shock-waves that exfoliate the graphite sample.13 Jet cavitated graphene can be more renewable than chemical exfoliation and can create less oxidized samples, depending on the cavitation method.14 Cavitation is useful for battery integration as it generally produces a purer graphene sample with less oxidation and allows for better conducting properties. When evaluated against a typical graphite anode, a higher quality battery with a lower contact resistance and improved functionality was produced by the jet cavitated, graphene-based anode.12


Solar Cell Integration and Chemical Vapor Deposition

Within the already silicon-dominated solar cell field, graphene has attracted interest due to its potential as a transparent conducting electrode.15 Compared to silicon and other materials, graphene synthesized via chemical vapor deposition (CVD) is more efficient in terms of transmittance and low sheet resistance.10 CVD produced graphene is becoming more common in solar cell research because of its ability to replace silicon as a conducting material.10 Graphene manufactured via deposition can be produced on a much larger scale than exfoliated graphene, but can also exhibit lesser electronic qualities and structural flaws depending on the substrate.16, 17 The deposition process begins by placing a substrate within a furnace chamber heated via hydrogen flow, which causes the substrate’s grain size to enlarge and reduces the metal oxide amount.17 Next, a hydrocarbon gas is mixed with hydrogen, which forms carbon and causes a reaction that results in carbon growth on the metal substrate.17 Then, the remaining graphene monolayer may be harvested.

Though CVD can produce flawed, electronically inferior graphene, the use of a hexagonal boron-nitride substrate was able to fabricate graphene with comparable results to exfoliated graphene.16 Since deposition is the method that produces the most, the aforementioned experiment may even help in establishing a reliable method of mass-production. A study utilizing CVD graphene as an electrode material in a silicon-based quantum dot solar cell found a Power Conversion Efficiency (PCE) of 8.23% compared to only 5.21% without a graphene quantum dot.18 Although ostensibly not the most efficient solar cell PCE recorded, the cell retained almost 84% of the initial power efficiency after exposed to air for 30 days.18 Another study found the PCE of an organic solar cell to be around 3.56% by utilizing a molybdenum disulfide (MoS2) transport layer.19 When a graphene quantum dot was added to the solar cell, the PCE was increased to 4.23%, indicating a significant increase in conversion efficiency.19 It should be noted that these studies are not being directly compared in this review because of potential cofounding variables and serve only to highlight the benefits of graphene integration in solar cells.

Conclusion

As a derivative of graphite, graphene is a very durable and extraordinarily thin material that is of the most unique ever discovered. Its properties have lent itself well to increasing the cyclability, durability, and rechargeability of the lithium-ion battery when used as an anode material. When used as an electrode or quantum dot material in solar cells, photovoltaic efficacy is shown to increase and surpass non-graphene technologies. The differing production methods ranging from Hummer’s Method to chemical vapor deposition have helped make the material more ubiquitous and accessible in the scientific community. Yet, a lack of reliable graphene mass production and synthesis prevent this material from becoming commercially accessible. Any method that effectively produces graphene is too long and slow of a process to be widely available, and any method that produces a large crop is riddled with defects and structural impurities. Future research may wish to focus on finding a happy medium between mass production and graphene purity so that more technologies can benefit from graphene-based research.

References

1. Hao-Hsun, C.; Tseng-Hsiang, H.; Yu-Sheng, S., Graphene-Enhanced Battery Components in Rechargeable Lithium-Ion and Lithium Metal Batteries. C 2021, 7 (3), 1-28.

2. Sharon, M.; Sharon, M., Graphene : an introduction to the fundamentals and industrial applications. Scrivener Publishing: 2015.

3. Al Faruque, M. A.; Syduzzaman, M.; Sarkar, J.; Bilisik, K.; Naebe, M., A Review on the Production Methods and Applications of Graphene-Based Materials. Nanomaterials (Basel, Switzerland) 2021, 11 (9).

4. Novoselov, K. S.; Geim, A. K.; Morozov, S. V.; Jiang, D.; Zhang, Y.; Dubonos, S. V.; Grigorieva, I. V.; Firsov, A. A., Electric Field Effect in Atomically Thin Carbon Films. Science 2004, 306 (5696), 666-669.

5. Warner, J. H., Graphene. [electronic resource] : fundamentals and emergent applications. 1st ed.; Elsevier: 2013.

6. Kuanyshbekov, T. K.; Akatan, K.; Kabdrakhmanova, S. K.; Nemkaeva, R.; Aitzhanov, M.; Imasheva, A.; Kairatuly, E., SYNTHESIS OF GRAPHENE OXIDE FROM GRAPHITE BY THE HUMMERS METHOD. Oxidation Communications 2021, 44 (2), 356-365.

7. Islam, A.; Mukherjee, B.; Pandey, K. K.; Keshri, A. K., Ultra-Fast, Chemical-Free, Mass Production of High Quality Exfoliated Graphene. ACS Nano 2021, 15 (1), 1775-1784.

8. Tu, F.; Liu, S.; Jin, G.; Yan, G.; Pan, C., Fabrication of graphene from graphene oxide by ultrasonication with high Li storage capability. Powder Technology 2013, 249, 146-150.

9. Shan, H.; Zhang, J.; Cao, H.; Hou, G.; Tang, Y.; Zheng, G., An efficient and independent modeling method for lithium-ion battery degradation. Ionics: International Journal of IonicsThe Science and Technology of Ionic Motion 2022, 28 (1), 99-105.

10. Choi, W.; Lee, J.-w., Graphene. [electronic resource] : synthesis and applications. CRC Press: 2012.

11. Jiao, L.; Liu, Z.; Sun, Z.; Wu, T.; Gao, Y.; Li, H.; Li, F.; Niu, L., An advanced lithium ion battery based on a high quality graphitic graphene anode and a Li[Ni0.6Co0.2Mn0.2]O2 cathode. Electrochimica Acta 2018, 259, 48-55.

12. Jingshi, W.; Zhigang, S.; Min, Y., Scalable and High-Performance Graphene/Graphite Nanosheet Composite Anode for Lithium Ion Batteries via Jet Cavitation. Energy Technology 2020, 8 (10), 1-6.

13. Tyurnina, A. V.; Tzanakis, I.; Morton, J.; Mi, J.; Porfyrakis, K.; Maciejewska, B. M.; Grobert, N.; Eskin, D. G., Ultrasonic exfoliation of graphene in water: A key parameter study. Carbon 2020, 168, 737-747.

14. Yi, M.; Li, J.; Shen, Z.; Zhang, X.; Ma, S., Morphology and structure of mono- and few-layer graphene produced by jet cavitation. Applied Physics Letters 2011, 99 (12), 123112.

15. Jo, S.; Kim, H. G.; Son, Y. J.; Chae, A.; Lee, H.-B.-R.; In, I., Formulation of PEDOT:S-Graphene Hybrid and Its Application as Transparent Conducting Electrode Materials. Materials Today: Proceedings 2019, 10 (Part 3), 448-455.

16. Petrone, N.; Dean, C. R.; Meric, I.; van der Zande, A. M.; Huang, P. Y.; Wang, L.; Muller, D.; Shepard, K. L.; Hone, J., Chemical vapor deposition-derived graphene with electrical performance of exfoliated graphene. Nano letters 2012, 12 (6), 2751-2756.

17. Saeed, M.; Alshammari, Y.; Majeed, S. A.; Al-Nasrallah, E., Chemical Vapour Deposition of Graphene-Synthesis, Characterisation, and Applications: A Review. Molecules 2020, 25 (17).

18. Jang, C. W.; Shin, D. H.; Choi, S.-H., Porous silicon solar cells with 13.66% efficiency achieved by employing graphene-quantum-dots interfacial layer, doped-graphene electrode, and bathocuproine back-surface passivation layer. Journal of Alloys and Compounds 2021, 877.

19. Shin, D. H.; Jang, C. W.; Ko, J. S.; Choi, S.-H., Enhancement of efficiency and stability in organic solar cells by employing MoS2 transport layer, graphene electrode, and graphene quantum dots-added active layer. Applied Surface Science 2021, 538.

Non-primary: 1, 2, 3, 5, 9, 16