RSC Advances Blog

I have recently started my PhD – studying spin-crossover complexes, and my synthetic approach is largely focused on the use of mechanochemistry (1). The general response to me saying that I’m busy is: ‘don’t you just grind stuff?’, and the answer is no because I have analysis to do like everyone else. As mechanochemistry is a (mostly) solid state technique, powder X-ray diffraction is a go-to technique for product analysis. Comparison to starting materials can give an indication that a reaction has taken place, and then the detailed analysis can begin.

Elucidation of the structure of novel compounds which are not compatible with NMR, is often facilitated by single crystal XRD (SCXRD). The data from SCXRD can be used to simulate powder patterns for comparison with the mechanochemically synthesized powders.

Colour changes during grinding can also be indicative of reaction success. Therefore, mechanochemistry can allow for rapid screening of a huge number of different reactions in the search for interesting materials. However, don’t be too quick to dismiss an unsuccessful reaction if you haven’t tried liquid-assisted grinding (LAG). Whilst mechanochemistry is typically a solid-state technique, the addition of a small quantity of appropriate solvent (< 1 equiv. in µL per mg) (2,3) can be useful to get the reaction started.

My first experience with mechanochemistry quickly taught me that retrieving powder from a mortar is not easy, no matter how much it is scraped by a spatula. In the spirit of minimizing waste, the un-scrapeable powder is dissolved in a small amount of appropriate solvent and divided up into numerous vials, where techniques such as vapour diffusion and slow evaporation are used to harvest crystals.

I am still new to the world of mechanochemistry and have a lot to improve on, but it has opened my eyes to a synthetic approach that isn’t regularly seen in undergraduate studies and even research labs. It’s a promising area with a lot of applications, where the methodology could easily be manipulated for manufacturing purposes. However, if you are interested in trying some mechanochemistry, it is important to be aware of the potential hazards associated with the neat grinding of certain compounds, especially those which may explode!

References:

1              J. H. Askew and H. J. Shepherd, Chem. Commun., 2017, 54, 180–183.
2              T. Friić, S. L. Childs, S. A. A. Rizvi and W. Jones, CrystEngComm, 2009, 11, 418–426.
3              D. Tan and F. García, Chem. Soc. Rev., 2019, 48, 2274–2292.

About the Web Writer:

Lee Birchall has recently started his PhD under the supervision of Dr. Helena Shepherd at the University of Kent, where he also completed his MSc under the supervision of Dr. Stefano Biagini. He obtained a first class BSc at University College London. He enjoys music, languages and windsurfing and you can find him on Twitter at @LTBIRCH.

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Global energy demand grows very fast, while fossil fuel reserves decrease. For this reason, enormous efforts are focused on the production of new renewable, clean, safe and reliable forms of energy to ensure a sustainable future. At the same time, it is necessary to include energy vectors that allow storing and transporting said energy to be used when and where it is required. Lithium-based batteries are currently presented as one of the best systems to meet this need. Although its use in portable electronic devices is already established, the implementation in stationary energy accumulation and in the electric vehicle sector demands a notable increase in its energy density. That is why these new demands make a primary aspect, and which is currently a topic of study worldwide, to the development of materials with which the components for rechargeable lithium batteries are produced.

In the case of lithium-sulfur batteries, metallic lithium is used as the active material for the anode and sulfur for the cathode. After several electrochemical charge and discharge cycles, small branches form on the surface of the lithium metal electrode, called dendrites. These ramifications can cause a short circuit leading to spontaneous discharges, causing rapid heating and even fire, making them unsafe. Therefore, new investigations have found promising alternatives to avoid these drawbacks, based on the deposition of protective polymers on the surface of the metallic Li anode and the study of its effect on the degradation of the material properties. The polymers to be used are polymeric ionic liquids. Ionic liquids are molten salts whose melting temperature is less than 100°C. Considering the non-flammability and non-volatility properties of ionic liquids, they make reasonable alternatives as part of electrolytes because they offer important improvements, for example, in terms of safety. For this reason, the imim-DEHP protic ionic liquid synthesized for the first time by me and reported in the paper RSC Advances, 2017, 7, 44743 will be used, since we have observed that, with small amounts of water, imim-DEHP has the ability to form a gel, so it will be used in lithium batteries to coat the lithium anodes. Thus showing the versatility of this amphiphilic ionic liquid, since it forms organized systems in water and in non-polar organic solvents, as well as gels with a small amount of water.

Find out more:

Improvement of the amphiphilic properties of a dialkyl phosphate by creation of a protic ionic liquid-like surfactant
Cristian M. O. Lépori, Juana J. Silber, R. Darío Falcone and N. Mariano Correa
RSC Adv., 2017, 7, 44743

About the Web Writer:

Cristian M. O. Lépori is Doctor in Chemical Sciences and currently has a postdoctoral position at the “Enrique Gaviola” Institute of Physics, CONICET, National University of Córdoba (Argentina). He works in the area of nuclear magnetic resonance studying hybrid materials formed with porous matrices and ionic liquids for use in lithium batteries. He likes to plan, organize and carry out science dissemination activities. You can find him on Twitter at @cristianlepo.

Submit to RSC Advances today! Check out our author guidelines for information on our article types or find out more about the advantages of publishing in a Royal Society of Chemistry journal.

Keep up to date with our latest HOT articles, Reviews, Collections & more by following us on Twitter. You can also keep informed by signing up to our E-Alerts.