Materials Chemistry Conference in Birmingham

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It has been time for the Material Chemistry (MC) Conference again, the 14th of this name. Birmingham’s Aston University hosted the event this July.

Material Chemistry is a broad field. It spans from energy device materials to polymers, from biological applications to purely theoretical ones. Apart from plenary talks, there were four parallel sessions and it was not always easy for me to decide which might be of interest for me.

Clearly, the “In” material at the moment is perovskite. Perovskite is a long known mineral (discovered 1839) containing the elements Barium, titanium and oxygen in a certain ordering. All these elements can be substituted, and if the ratios are maintained, you obtain materials with the same structure but with a surprising range of properties. For example, they can be used as capacitors, superconductors, in LEDs and very recently in post-silicon solar cell technologies.

One very fascinating talk concerned debonding. That is to invent an adhesive which breaks up by some trigger, chemical or other, and releases the parts bonded together by this adhesive. Imagine a smartphone assembled with this adhesive. After it has reached its life’s end, you just use this trigger and the whole thing falls apart. You can easily separate the different building units and recycle them more easily.

One of my main interests – at least right now – is medical applications. One subject here is hydrogels, which are networks of hydrophilic polymers. They can be used for drug delivery or tissue engineering. Another emerging subject is 3D printing of implants and so on. You can print substitutes for cartilage, teeth or bones. But you can also use biologically degradable materials which are inserted into some wound and favour healing. They are “anchor points” for biological materials that grow along the implant and eventually close the wound while the original implant is degraded. The ideas even go father: Printing whole organs, for example a heart. The printing technology is pretty far advanced, but the materials for medical applications still need development – and approval of the FDA and other regulatory authorities of course.

Another issue is energy, of course. Although lithium ion batteries are state of the art nowadays, there are still a lot of questions to be answered and problems to be solved. One talk concerned a study of electrode manufacturing for LIBs. The manufacturing of LIBs is a long process and one step is a formation process that takes several weeks! The research group studied the different steps and tried to curtail the whole process. But although they showed some fascinating ideas, these are far from being implemented in current processes. What a pity.

There were a lot of other subject matters and I certainly missed some interesting ones. But all in all in I learned quite a lot and it was an inspiring event showing that Chemistry is at the centre for solving many of the problems the world faces today.

My Topic of the Month – Sodium Ion Batteries (SIB)

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These days, almost every child knows about lithium ion batteries (LIB). Many modern technologies that we are so dependent on today – smartphones, notebooks, etc. – would be unthinkable without these batteries. And they are thought to be indispensable for electro-powered mobility in the future. A vision that I do not share, but that is another issue…

Lithium has the lowest density among metals under standard conditions; thus, it is very light. Additionally, its ions are small, and it has an extremely negative redox potential, or in other words, it is extremely base. The latter enables high cell voltages of approximately 3 V (cf. nickel accumulators with a voltage of 1.2 to 1.5 V). The first results in high energy densities, i.e. a lot of energy per unit weight (Li-ion: 120-210 Wh/kg, Ni-batteries: 40-110 Wh/kg). These are the characteristics that enabled the realization of the small and durable batteries for smartphones and notebooks. Unfortunately, the base behavior also causes some problems, because lithium is extremely reactive, as some spectacular fires of electric cars of an American manufacturer demonstrate. Moreover, it does not occur in infinite quantities (it is less common than, e. g., copper, but more abundant than, e. g., lead), and its production is rather expensive.

Exchanging Lithium with Sodium

Should the development of electromobility develop as envisioned by ignorant dreamers, bottlenecks in the supply of lithium are possible. Therefore, more abundant and cheaper metals would be attractive. One metal being discussed as a substitute is sodium. This metal is chemically quite similar to lithium, but its ions are slightly larger, which increases problems associated with volume changes of the battery components in the course of charging and discharging. In addition, it is of course also heavier, which has a negative effect on the energy density. On the other hand, it occurs much more frequently than lithium (e. g. in the form of table salt) and is therefore cheaper to have. A review in Angewandte Chemie now addresses the chemical / physical / technical implications of replacing lithium with sodium. It has been shown that the battery chemistry often becomes more complex and some require solutions for well-resolved problems of lithium-ion batteries, but sodium ion batteries do not per se perform worse. SIB probably will not provide solutions for vehicle technology, but possibly for stationary energy storage, e. g. in connection with photovoltaics or wind turbines, where the weight of the battery is irrelevant. But even though research on SIB has achieved great progress in recent years, it is still in its infancy and a technical realization will take time.

Said paper, whose translation into Geman was done by me, by the way, can be found at:

German: http://onlinelibrary.wiley.com/doi/10.1002/ange.201703772/abstract

English: http://onlinelibrary.wiley.com/doi/10.1002/anie.201703772/abstract

 

Materials Chemistry 2017 in Liverpool

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Every second year, the advances of materials chemistry are discussed in a fantastic conference of the Royal Chemical Society (RSC). Material is a broad term, and most issues in modern life need materials, be it clothes, mobile phones, energy devices or medicine. No big surprise therefore, that so many researchers of so many fields come together. 5 parallel sessions were offered each day, surrounded by plenary lectures and poster sessions. It was most difficult to make the right choices.
Whereas thermoelectric materials may seem completely uninteresting to the layman (who is probably wondering what I am talking about), novel materials for solar cells seem much important for our future energy supply. In fact, both techniques are interesting to solve our energy problems in future. Solar cells are self-explaining, but thermoelectrica convert thermal energy into electricy which is very interesting for process heat or exhaust gas heat in a car. And both have been the central point of multiple talks. The progresses made for perovskite and dye-sensitized solar cells are very interesting and one concept was presented that enables an indoor application. This means, you can produce energy while reading a book in lamp light!
Another interesting field are applications in the medical area, namely drug delivery, contrast agents, etc. A most inspiring method is the use of “bioink” which includes biomaterials such as cells or enzymes in a printable matrix. This can then be used for concepts like organ-on-a-chip, and, eventually, organ printing.
In the end, I have learned a lot, met very nice people and experienced a most exciting city – Liverpool – celebrating its musical and shiping heritage.