Lithium-ion batteries have fuelled our age of portable electronics, but they have increasingly become a victim of their own success. Lithium mining is expensive, and the metal is dangerous to handle, making processing and recycling difficult.

Demand is also outstripping available supplies, whose geographic isolation in places like the Australian outback can make supply chains difficult.

EU data shows that Europe will need up to 60 times more lithium by 2050 to fulfil the demand for electric car batteries and renewable energy storage that will form the backbone of reaching emissions goals laid out in the European Green Deal.

Calcium is one the most abundant elements on the earth’s crust. It’s not as geographically concentrated as lithium is. This could make a battery cheap because the raw material is cheap

Dr M. Rosa Palacín, ICMAB-CSIC

That has led researchers like Dr M. Rosa Palacín to try and create similarly effective batteries out of more abundant elements found right inside Europe. Based at ICMAB-CSIC near Barcelona, she and her team from around the EU aim to build a prototype battery that uses periodic neighbour calcium instead of lithium. The effort is funded by a European Innovation Council Open Pathfinder grant and has been dubbed the CARBAT project.

Found in everything from bones to chalk, calcium is roughly 2000 times more common than lithium.

‘Calcium is one the most abundant elements on the earth’s crust,’ said Dr Palacín. ‘It’s not as geographically concentrated as lithium is. This could make a battery cheap because the raw material is cheap.’

A Calcium Supplement

All batteries rely on a similar structure. Positive ions flow from a negative electrode across an electrolyte to a positive electrode, while negative electric current flows outside the battery and can be used to power devices.

But using calcium as the negative electrode provides advantages that graphite-using lithium-ion batteries cannot – greater energy density, or how much energy can be stored per kilogram.

‘With this configuration we were suggesting in theory we could achieve very high energy density, and this is due to the fact that we would use a metal as one of the electrodes,’ Dr Palacín explained.

Lithium-ion batteries can’t achieve as high an energy density since they cannot use highly reactive metallic lithium as an electrode in a battery. It tends to form dendrites, tiny rigid tree-like structures that can grow inside a lithium battery and cause short circuits or even for the battery to explode over many uses.

Using calcium metal within the battery let researchers take advantage of its elemental properties, with two electrons in its outer shell that it can lose.

‘As any calcium travels through the electrolyte, two electrons would travel outside (instead of one with lithium),’ she said. ‘One could imagine that for the same battery size, the range would be higher if you used it in an electric vehicle, provided a suitable positive electrode is found.’

Finding the right salt

Yet that same property made choosing other components to build a prototype battery, such as the electrolyte that ions flow through, more complicated.

‘There are many interactions in the electrolyte between the Ca2+ ions and the solvent molecules, and this hindered the mobility of calcium,’ said Dr Palacín.

Very good conductivity in the electrolyte means that ions can move faster, and the battery will have a higher power.

To solve this, researchers modelled different salts and solvents to find an electrolyte that would create a passivation layer on the calcium electrode which makes it easier for ions to transfer.

‘In the end it seems that all the electrolyte salts which work contain boron,’ she said. ‘We used calcium tetrafluoroborate dissolved in a mixture of ethylene and propylene carbonate.’

The next steps for commercialising the prototype would be to improve the methods used to fabricate electrodes using calcium and to develop suitable positive electrodes.

‘All the engineering for the cell assembly was very challenging since new protocols had to be developed,’ Dr Palacín said.

Other abundant elements

Dr Juan Lastra at the Technical University of Denmark was involved in another effort to create batteries out of more common elements. A researcher on the SALBAGE project, he was part of a team that worked on making a battery out of an aluminium anode and a sulfur cathode.

While aluminium is even more abundant than calcium, using it in a battery created similar challenges.

‘All these multivalent ions (Ca2+, Al3+) are very reactive…and it is difficult to move these ions by themselves,’ he said.

In aluminium-sulfur batteries, the aluminium is always in the form of aluminium and some chloride ions, AlCl4-.

‘You have a conversion process where this aluminium gets decoupled gradually from the AlCl4 cluster to react with the sulfur in the cathode side,’ said Dr Lastra. ‘It’s more like the lead-acid battery you have in your car rather than the lithium-ion battery in your phone.’

Computer-built bendable batteries

To improve the transfer of these ions, the team focused on creating using a new type of electrolyte known as a deep eutectic solvent.
‘A eutectic solvent is when you put two solids together and they become a liquid,’ Dr Lastra explained. ‘Like when you put salt and ice together and they form a liquid (brine) even below freezing.’

Using a supercomputer, they modelled how to combine an aluminium chloride salt with urea, which is commonly found in urine, to find the best mixing ratio for a liquid electrolyte.

‘We model around 300 atoms at most…and our simulation time is not more than one nanosecond,’ said Dr Lastra. ‘But to simulate one nanosecond of this liquid takes half a year.’

It takes so long because the researchers must look at one million steps per nanosecond to properly simulate all the possible reactions.

Armed with the right ratio for the electrolyte, researchers for the project in Spain found that they could make the electrolyte a gel by adding polymers to the solution.

‘Having a gel is very advantageous in terms of safety and in terms of form factor,’ said Dr Lastra. ‘If you have gel then your battery will be flexible, and you will be able to bend it.’

Using a gel instead of a liquid also adds safety in that the battery can’t easily leak. This comes on top of the fact that the materials are all safe and inexpensive.

‘It’s all based on cheap materials. Aluminium, sulfur, the electrolyte itself and urea is very, very cheap. Even the polymer is cheap,’ Dr Lastra said.

For stationary applications, like storing energy from a wind farm or solar power, this type of technology could be competitive

Dr Juan Lastra, Technical University of Denmark

The safety of the components could be a key factor in future-proofing the battery. One of the main disadvantages seen with lithium-ion batteries has been that they contain toxic and rare elements, making it hard to integrate them in the circular economy.

Aluminium-sulfur batteries offer the promise of sourcing components from within Europe and increased energy security for industry. Future refinement could even help increase our uptake of renewable energy by storing power when they are not actively generating it.

‘For stationary applications, like storing energy from a wind farm or solar power, this type of technology could be competitive,’ Dr Lastra said.

The research in this article was funded by the EU. If you liked this article, please consider sharing it on social media.

Why the EU supports energy storage research and innovation

With electrification set to be one of the main pathways to decarbonisation, batteries as electricity storage devices will become one of the key enablers of a low-carbon economy. Which is why developing  batteries/energy storage is a strategic priority for the EU

Hence, global demand for batteries is expected to grow very rapidly over the coming years, making the market for batteries a very strategic one. Click here to learn more.

This article was originally published in Horizon, the EU Research and Innovation magazine

food packaging phas

For green products to be successful, there have to be markets. For PHAs, a family of plastics that are both bio-based and biodegradable, there appear to be many. Invest-NL and Wageningen University & Research are joining forces to accelerate the market introduction of PHAs. They have developed a roadmap that shows which PHAs are appropriate for specific applications, what the characteristics of logical early adapter products are, and what developments are still needed.

PHAs are made by micro-organisms from raw materials such as sugars and vegetable oils and from various waste streams such as food waste and sewage sludge. Although production volumes are still limited and production costs are high, the market demand is clearly growing. When the production volumes go up, the costs may also go down, which in turn can open up new markets. What complicates the market implementation is the fact that the production of PHAs requires a different production process than the processes used to make conventional plastics such as PE, PP, and PET. This will require substantial investments and a lot of research.

PHAs when biodegradability is essential

Wageningen Food & Biobased Research has been conducting technological research for 30 years into the production and usage possibilities of PHAs for various applications. They are currently participating in the European Urbiofin project, which aims to make PHAs from urban waste for use in packaging materials. In collaboration with Invest-NL they studied the market opportunities that will arise in the coming decades for the various types of PHA materials and the developments that are still required.

“These materials are a perfect fit for markets for which biodegradability in various natural environments is essential,” says Wouter Post, researcher at Wageningen Food & Biobased Research. These applications are included in the roadmap in phase 1 of the market implementation. “There are currently various types of PHA entering the market which each have their own specific set of material properties. As a result, unique market opportunities arise for each individual PHA type. This means that the market now needs clarity on which PHAs are appropriate for specific applications, such as products like paper coatings and agricultural plastics.

Opportunities for coffee and tea packaging

There are significantly fewer direct matches among the available PHAs for applications that require more specific mechanical properties (phase 2). Still, there seem to be opportunities for specific PHA materials for plant plugs, coffee and tea packaging, and artificial reefs. According to the researchers, there are technical opportunities for biodegradable tableware (plates, cups, cutlery) in the near future. But there are strict legal regulations for the production of these materials that make the use of plastics (and therefore also PHAs) more difficult. It is therefore still unclear whether it is interesting for this industry to enter this market with PHA products.


desalination of seawater

Desalination of seawater, converting salt water into fresh water is important in water-scarce countries. For that process, certain charged particles – known as ions – have to be removed from the water. However, some ions are difficult to remove from water due to their chemical properties. Recent research by scientists from Israel and the Netherlands is helping to improve this ion-removal process.

The researchers were able to predict the behaviour of boron ions during water processing and thus simplify their removal. The study is available on-line at the Proceedings of the National Academy of Sciences (PNAS). Many harmful or valuable ions in seawater, brackish water or freshwater are amphoteric: their properties vary with the pH. “It is difficult to remove these particles from the water with standard membrane technologies,” says Jouke Dykstra, Assistant Professor at the Department of Environmental Technology at Wageningen University & Research. “You then have to add certain chemicals to control the pH. But we want to avoid that as much as possible: there is a strong trend to use fewer chemicals.”

Desalination of seawater

As an example of this ion removal process, Dykstra refers to the desalination of seawater. This is happening worldwide at locations with a shortage of fresh water. For example, many countries around the Mediterranean use desalinated seawater for irrigation. “But seawater also contains boron, which is toxic in high concentrations and it inhibits plant growth. Obviously, this is a problem for irrigation, and that is why we are looking for new ways to remove boron and other ions from sea water.” Desalination is becoming increasingly important due to drought in many regions. Dykstra: “New technologies are needed to continue to meet the demand for fresh water, not only in the Mediterranean and the Middle East, but also in the Netherlands.”

Wageningen researchers are working on this challenge together with colleagues from Technion – the Israel Institute of Technology, and from Wetsus – the European Centre of Excellence for Sustainable Water Technology in Leeuwarden. Together they have developed a new theoretical model of the behaviour of boron during a process known as capacitive deionisation. This is an emerging, membraneless technique for water treatment and desalination using microporous, flow-through electrodes When an electric current is applied, ions are adsorbed to the electrodes and hence removed from the water. Dykstra: “We are the first in science to develop a theoretical model that enables us to predict this behaviour and use it to our advantage.”

Entirely new design

The Israeli and Dutch researchers discovered that such systems require a completely new design. For example, they demonstrated both theoretically and experimentally that the water has to flow from the positive to the negative electrode, and not the other way around, as is now customary. “Our research has shown that a good theoretical model is essential to effectively control such complex chemical processes,” concludes Dykstra. “This approach offers many interesting possibilities. You could also use this model for other challenges in waste water treatment, including removing arsenic or small organic molecules, such as drug residues or herbicides.”

PNAS summarizes the process: Water treatment is required for a sustainable potable water supply and can be leveraged to harvest valuable elements. Crucial to these processes is the removal of charge pH-dependent species from polluted water, such as boron, ammonia, and phosphate. These species can be challenging for conventional technologies. Currently, boron removal requires several reverse-osmosis stages, combined with dosing a caustic agent. Capacitive deionization (CDI) promises to enable effective removal of such species without chemical additives but requires a deep understanding of the coupled interplay of pH dynamics, ion electrosorption, and transport phenomena. Here, we provide a detailed theory tackling this topic and show both theoretically and experimentally highly counterintuitive design rules governing pH-dependent ion removal by CDI.

Photo by Lance Cheung on Foter

starch from co2

Creating starch from co2 is not a new process. Plants do it all the time. But Chinese researches now discovered a way to do it much more efficiently in a lab. That would potentially save up to 90% of farm land, water, fertiliser and pesticides, they claim.

Chinese scientists recently reported a new technology for artificial starch synthesis from carbon dioxide (CO2). The results were published in Science on September 24.

The new route makes it possible to shift the mode of starch production from traditional agricultural planting to industrial manufacturing, and opens up a new technical route for synthesizing complex molecules from CO2, reports Eurekalert.

Starch is the major component of grain as well as an important industrial raw material. At present, it is mainly produced by crops such as maize by fixing CO2 through photosynthesis. This process involves about 60 biochemical reactions as well as complex physiological regulation. The theoretical energy conversion efficiency of this process is only about 2%.

A sustainable production of starch and use of CO2 are urgently needed to solve the food crisis and climate change. Designing new ways to replace plant photosynthesis for converting CO2 to starch can contribute to achieve that.

To address this issue, scientists at the Tianjin Institute of Industrial Biotechnology (TIB) of the Chinese Academy of Sciences (CAS) designed a chemoenzymatic system as well as an artificial starch anabolic route consisting of only 11 core reactions to convert CO2 into starch.

The abstract of the research says: “Starches, a storage form of carbohydrates, are a major source of calories in the human diet and a primary feedstock for bioindustry. We report a chemical-biochemical hybrid pathway for starch synthesis from carbon dioxide (CO2) and hydrogen in a cell-free system. The artificial starch anabolic pathway (ASAP), consisting of 11 core reactions, was drafted by computational pathway design, established through modular assembly and substitution, and optimized by protein engineering of three bottleneck-associated enzymes. In a chemoenzymatic system with spatial and temporal segregation, ASAP, driven by hydrogen, converts CO2 to starch at a rate of 22 nanomoles of CO2 per minute per milligram of total catalyst, an ~8.5-fold higher rate than starch synthesis in maize. This approach opens the way toward future chemo-biohybrid starch synthesis from CO2.”

Starch from co2 can be 8.5 times more efficient

The artificial route can produce starch from CO2 with an efficiency 8.5-fold higher than starch biosynthesis in maize, suggesting a big step towards going beyond nature. It provides a new scientific basis for creating biological systems with unprecedented functions.

The research is a first step towards industrial manufacturing of starch from CO2. From the moment the total cost of the process will become comparable with agricultural planting, this technology is expected to save more than 90% of cultivated land and freshwater resources.

In addition, it would help to prevent the negative environmental impact of pesticides and fertilizers, improve human food security and facilitate a carbon-neutral bioeconomy.