Summary/ Reader Response Draft #2

 The article "How an accidental discovery made this year could change the world." written by Lockett (April, 2022), introduces the discovery of Lithium-sulfur(Li-S) batteries and their benefits with it. The Li-S batteries are cheaper to make, use environmentally friendly materials, can be three times lighter, and have a low chance of catching fire compared to lithium-ion(Li-ion) batteries, but Li-S batteries typically have around 1000 charge cycles. Hence, there is a need to increase its charge cycles. However, according to the author, researchers find it difficult to increase the charge cycle of Li-S batteries by changing compounds in the battery’s cathode. “The uncontrolled dendritic and lithium growth, as well as electrolyte decomposition inherent in lithium metal-based batteries, cause safety issues and low Coulombic efficiency.” as observed by Li et al (June 2015). This causes a shuttling effect on Li-S batteries, due to the dissolution of lithium-polysulfides formed when the battery charges and discharges. However, the author states that the researchers were able to find a chemical phase of sulfur that was able to prevent the batteries from degrading. “Here, we stabilize a rare monoclinic γ-sulfur phase within carbon nanofibers that enables successful operation of Lithium-Sulfur (Li-S) batteries in carbonate electrolyte for 4000 cycles(Pai, Singh, Tang, & Kalra, February 2022).” Rahul et al imply that with the introduction of gamma sulfur, they can stop the reaction that creates polysulfides. “which stabilizes to 800 mAh·g−1 in the first few cycles and then it remains stable with a small 0.0375% decay rate over 4000 cycles. The cells exhibit a high capacity of 650 mAh·g−1 even after the end of 4000 cycles.” Rahul et al mention that the decay rate of the new Li-S batteries is almost negligible even after 4000 cycles. With this breakthrough in Li-S batteries, the researchers still have yet to grasp the understanding of this phenomenon. Lockett believed that Li-S batteries have the potential to revolutionize the world. In my opinion, Li-S batteries should replace Li-ion batteries because sulfur is abundant, it causes lesser ecological harm and is cheaper. While having a higher energy density means it can be lighter while storing just as much energy. However, it will take a while before Li-S batteries replace Li-ion batteries.

Regarding cost, they use sulfur as a raw material as a by-product of the oil industry instead of expensive cobalt, which is susceptible to the fragility of global supply chains. And they can save substantial amounts per unit of power (Merrifield, 2020). There are three types of Li-ion batteries used in this comparison, Lithium Cobalt Oxide(LCO), Lithium Nickel Cobalt Manganese Oxide(NMC), and Lithium Nickel Cobalt Aluminum Oxide(NCA). Sulfur is 243 times cheaper than Nickel and 550 times cheaper than Cobalt.(Benveniste Pérez, Rallo, Canals Casals, Merino, Amante García,2018). According to research on drones, there might be significant cost savings with Li-S being available for roughly €72 per kWh, which is 30% less than comparable Li-ion technology(Merrifield, 2020).

The ecological cost of rechargeable batteries and the components that make up the batteries is becoming more and more of a worry. As was stated previously, nickel and cobalt are frequently found in Li-ion batteries; these minerals are now produced through extensive mining operations, and the main concern lies in cobalt mining(Gifford, July 2020). When Cobalt mines are exhausted miners extract cobalt from communal land, farmland, and homes. Cobalt and other metal mining waste can contaminate water, air, and soil, reducing crop yields, tainting food and water, and posing risks to reproductive and respiratory health (Northwestern University, December 2021). In contrast, sulfur is plentiful to a point that the US Geographical Survey describes it as near limitless and it can be found being produced on many continents. Furthermore, the environmental agencies, sulfur does not cause any major health risks(Gifford, July 2020). 

The main selling point of Li-S batteries compared to Li-ion batteries is their higher energy density per unit weight(Gifford, July 2020). The current Li-S has an energy density of 200 - 500 Wh/kg, while the LCO has 240 Wh/kg, the NMC has 220 Wh/kg and the NCA has 260 Wh/kg (Benveniste Pérez et al, 2018). Batteries with high energy density increases the run time of the battery in relation to the size. It can produce the same amount energy with a smaller footprint compared to batteries with lower energy density (Cloud ,August 2020). This means that Li-S batteries can smaller and lighter, yet last longer without charging.

One of the challenges faced by researchers is being able to construct Li-S batteries that can reach an energy density of 2600 Wh/kg, even though they can reach such a high amount of energy density theoretically, practically they only achieved 500 W/kg. In order to achieve higher energy density will require high sulfur loading and high sulfur utilization. It hasn’t been possible to achieve all of these standards simultaneously despite the researchers’ discussions and formulation of some parameters  (Feng et al,2020). 

In conclusion, even though the Li-S battery may seem to be better than the Li-ion battery in many aspects. It appears that Li-S batteries are yet to be commercialized, while the market for electric vehicles is rising. Scientists are researching ways to increase energy density and prevent degradation. If scientists can achieve this, the Li-S battery will replace the Li-ion battery soon, as the Li-S battery will be more efficient.


References


Benveniste Pérez, G., Rallo, H., Canals Casals, L., Merino, A., & Amante García, B. (2018). Comparison of the state of lithium-sulfur and lithium-ion batteries applied to electromobility. 

https://upcommons.upc.edu/bitstream/handle/2117/121911/comparison_state.pdf;sequence=1 


Cloud, M.(2020, August 21). What is the energy density of lithium-ion battery? Flux powerhttps://www.fluxpower.com/blog/what-is-the-energy-density-of-a-lithium-ion-battery



Feng, Y., Wang, G., Ju, J., Zhao, Y., Kang, W., Deng, N., & Cheng, B. (2020). Towards high energy density Li-S batteries with high sulfur loading: From key issues to advanced strategies. ScienceDirect. pp  320-355

https://www.sciencedirect.com/science/article/pii/S2405829720302658?fr=RR-2&ref=pdf_download&rr=7522a044ab458829 


Gifford, S.(2020, July). Lithium-sulfur batteries: advantages. The Faraday Institution.

https://www.faraday.ac.uk/lis-advantages/ 


Lockett, W. (2022 ,April 21). An accidental discovery could change the world. Freethink

https://www.freethink.com/environment/lithium-sulfur-battery


Li, W., Yao, H., Yan, K., Zheng, G., Liang, Z., Chiang, Y., & Cui, Y. (2015, June 17).

  The synergetic effect of lithium polysulfide and lithium nitrate to prevent lithium dendrite growth.

Nature Communications

https://www.nature.com/articles/ncomms8436


Merrifield R.( 2020, June 05). Cheaper, lighter and more energy-dense: the promise of lithium sulfur batteries. European Commission.

https://ec.europa.eu/research-and-innovation/en/horizon-magazine/cheaper-lighter-and-more-energy-dense-promise-lithium-sulphur-batteries#:~:text=Rather%20than%20using%20costly%20cobalt,power%20can%20offer%20substantial%20savings. 



Northwestern University.(2021, December 17). Understanding cobalt’s human cost:Social consequences of green energy must be assessed in addition to environmental impacts, researchers say. ScienceDaily.

https://www.sciencedaily.com/releases/2021/12/211217113232.htm#:~:text=Waste%20generated%20from%20mining%20cobalt,were%20unsafe%2C%20unfair%20and%20stressful

Pai, R., Singh, A., Tang, M., & Kalra, V. (2022, February 10). Stabilization of gamma sulfur at room temperature to enable the use of carbonate electrolyte in Li-s batteries. Nature Communications

https://www.nature.com/articles/s42004-022-00626-2?utm_medium=affiliate&utm_source=commission_junction&utm_campaign=CONR_PF018_ECOM_GL_PHSS_ALWYS_PRODUCT&utm

_content=textlink&utm_term=PID100062364&CJEVENT=70ab9fddb82a11ec811f534d0a18050f 












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