In the latest article published in the journal Ceramics International, Chinese researchers have prepared FeS-graphene composites using single-step pyrolytic sulfidation processes by utilizing organic alcohol as a deep eutectic solvent.
Study: Lithium storage performance of FeS@graphene anode materials prepared in a deep eutectic solvent. Image Credit: Immersion Imagery/Shutterstock.com
Importance of Lithium-Ion Batteries
LIBs (lithium-ion batteries) are recognized as the most viable future energy source for electric cars. Lithium-ion batteries (LIBs) are widely used in portable devices, electric automobiles, and long-term battery storage due to high power density and prolonged cyclic stability. Li-ion batteries are also used to power large maritime apparatus and warships.
However, the energy content of present LIBs falls short of the requirements of technological devices such as high-end cell phones. The specific capacity of graphite electrodes, the principal anode material of commercial LIBs, is now extremely near to its theoretical specific capacitance (372 mAhg-1), limiting graphite electrode growth as anode materials.
Applications of Transition Metal Compounds
Transition metal composites have a large theoretical capacity, a low cost, and a straightforward manufacturing procedure. As cell anode materials, transition metal sulphides such as Iron Sulphides, Nickel Sulphides, and Cobalt Sulphides are being researched. In comparison to carbon-based and transition metal oxide materials, the layer of transitional metal sulphides utilized as anodes for LIBs not only offers a route for lithium-ion transmission but also ameliorates the low expansion impact of anodes.
Importance of Iron Sulphide (FeS)
Owing to its relatively high specific capacity (609 mAhg-1), strong electrochemical characteristics, plentiful natural storage, and inexpensive cost, FeS has raised interest. However, FeS anodes suffer from size fluctuations, poor electrical conductivity, and cyclability as a result of reactions while recharging.
The majority of existing techniques are centred on modifying and optimizing carbon materials using FeS.
The majority of recent papers on the production of metal sulphide/carbon composites involve multi-step processes, such as the synthesis method, hydrothermal synthesis, and decomposition method, which need a long experiment time, laborious operations, and are expensive. Previously, the researcher developed onion-like carbon covered FeS nanocrystals with good cycle stability (719.2 mAhg-1 after 200 cycles of 0.1 Ag-1) and exceptional high-rate performance.
What is Deep Eutectic Solvent?
Deep eutectic solvent has received considerable interest as a novel type of green solvent that is manufactured from a specific proportion of intramolecular hydrogen bonding donors and acceptors.
It has received extensive attention and obtained great experimental data in the fields of extraction and determination, electrodynamics, and materials engineering due to its low fluctuation, high electrical conductivity, outstanding stabilisation effectiveness, strong bioavailability, and other properties superior to those of conventional ionic solvents.
Deep eutectic fluid is a new form of solvent that is cleaner, more environmentally friendly, and inexpensive. It is a cheap natural resource that is simple to create, has a high utilization rate, and produces little pollution.
Further Reading: Effect of Fast-Charging on Lithium-Ion Battery Performance
As deep eutectic solvents are made up of metal chlorides and organic alcohols and may produce a liquid combined with a low molecular scale at low temperatures, FeS@graphene hybrids can be made sequentially by pyrolytic elastomers. Because polyethylene glycol (PEG) is a non-ionic surfactant with strong micelle formation and distribution, it may minimize size distribution composite production, and the carbon formed in the high thermal fracture can increase the material's electrical properties.
Research Findings
The FeS@graphene composite's Raman spectra showed two typical peaks corresponding at 1354 and 1583 cm, which were compatible with graphene's D and G peaks. The FeS nanoparticles were small, distributed, and tightly attached to graphene, and the interface was a coiled graphene ultra-thin film. Based on these findings, a temperature of 550 °C was determined to be the ideal roasting temp, and electrolytic experiments will be conducted to corroborate this initial conclusion.
The FeS@graphene achieved a higher specific discharge capacitance than pure FeS. During the entire cycle procedure, the Coulombic effectiveness of the FeS@graphene compound was nearly 100 percent. At the current densities of 5oC, the rate performance of pure FeS was likewise much poorer than that of the FeS@graphene composite, which had a far superior rate capability than pure FeS.
To summarize, FeS@graphene nanomaterials were made using a convolution neural network eutectic solvent and a one-step pyrolytic crosslinking technique to overcome the problems of lower thermal conductivity, significant volume expansions during recharging, and low strength in conventional anode materials. As a result of its remarkable electrochemical performance, the FeS@graphene composite made from DES has a lot of potential in the future.
Further Reading
D. Ju, X. Cao, H. Li, J. Zheng, C. Chen, Z. Wang, J. Qiu, Y. Zhang, M. Liu, Q. Zhu. Lithium storage performance of FeS@graphene anode materials prepared in a deep eutectic solvent. 2022. Ceramics International. Available at: https://www.sciencedirect.com/science/article/pii/S0272884222002450?via%3Dihub
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