STEM Structural energy harvesting composite materials Project Objectives
The STEM project set out to develop new multifunctional structural composite materials combining high performance mechanical properties and applications in energy. In a major breakthrough, researchers showed that inorganic nanowires can be synthesised floating in the gas phase, which enables their direct assembly into continuous, macroscopic materials. This unlocks the possibility of assembling virtually any one-dimensional nanomaterial into freestanding solids without the use of solvents or polymers. The group is currently working on applying this synthetic route to new nanomaterials and particularly on exploring the potential of this method for more sustainable production of high-performance lithium ion battery electrodes.
New methods for tomorrow’s nano-structured materials The next generation of lithium-ion batteries are set to be based on silicon, so it’s essential that the material is produced in a cost-effective and sustainable way. Researchers in the STEM project have developed a new method of making nano-structured materials which could help improve energy storage capacity, as Dr Juan-Jose Vilatela explains. The
established process of manufacturing battery electrodes involves the use of solvents or polymers, but with sustainability a prominent concern, researchers are looking for alternatives. Based at the IMDEA Materials Institute in Madrid, Dr JuanJosé Vilatela and his colleagues in the STEM project have developed a new process to make nano-structured materials. “We have developed a process to assemble silicon into electrodes, without the use of any solvents or polymers,” he explains. The STEM project was originally focused on developing structural composite materials for energy harvesting, before researchers branched out in a slightly new direction. “We had experience of assembling one type of nano-material in a gas phase. We then thought that this could be a universal method, so we started exploring this for silicon,” says Dr Vilatela. A lot of progress has been made in this respect over the course of the project, with researchers developing a method to effectively synthesise silicon floating in gas. This represents a significant breakthrough which opens up further possibilities, believes Dr Vilatela. “Typically nanomaterials are produced on a substrate, and from there they are processed into a macroscopic object. We are now able to synthesise inorganic nano-materials floating in the gas phase, without any substrate. We can then directly assemble them into a macroscopic object,” he outlines. This fabrication process has been demonstrated for silicon, which holds potential for use as an electrode, while researchers have also gained some very promising results on silicon carbide.
46
easy to source in comparison to graphite. The aim now for Dr Vilatela and his colleagues is to prove the viability and cost-effectiveness of this new method. “We are trying to demonstrate the performance of this material as electrodes in large batteries, and also to increase production capacity. The main challenge we face is in scaling up production to larger amounts,” he outlines. A further significant challenge involves demonstrating the performance of these materials as electrodes, particularly their cyclability. “This means that the electrochemical properties of these materials, such as their ability to storage energy during repeated charge and discharge cycles, need to be preserved. We need to
Production of nanostructured materials by direct assembly of nanowires floating the gas phase.
We are now able to synthesise inorganic nanomaterials floating in the gas phase, without any substrate. We can then directly assemble them into a macroscopic object. “This could be interesting as an insulator, while it also has some good optoelectronic properties,” says Dr Vilatela.
Fabricating nano-materials The approach developed in the project is not limited to silicon and could potentially be applicable to any 1-dimensional nanomaterial, so essentially all nanowires. These could be metal oxides, semi-conductors, or insulators for example, with researchers aiming to demonstrate that this process can be used to fabricate different types of nano-materials. “Our interest is in demonstrating that this
Tesla Panasonic battery cells.
is a universal process to assemble nanomaterials,” says Dr Vilatela. Researchers have so far shown that this process can be used to assemble silicon into electrodes, without the use of any solvents or polymers, work which holds important implications for energy storage. “Silicon is envisaged as an electrode for energy storage in transport, as well as in stationary applications. It is recognised as the best replacement for graphite in almost all lithium-ion batteries,” continues Dr Vilatela. The key advantage of silicon over the materials currently used is that it can store 10 times more energy, while it is also relatively
EU Research
the point of fabrication, for a regular electric vehicle. The process that we have developed can eliminate the use of all solvents,” he stresses. “This could greatly reduce the carbon footprint of our batteries. We have now applied for further grants to extend our work and to study this process in more detail.”
Exploiting the technology The objective then will be to start validating these nano-structured electrodes in 2021, and to have enough production capacity to move towards certification at a pilot plant in a couple of years. Then beyond that point, Dr Vilatela hopes to bring these electrodes to the market by 2025, which
Silicon is envisaged as an electrode for energy storage in transport, as well as in stationary applications. Silicon is widely recognised as the best replacement for graphite in almost all lithium-ion batteries. demonstrate their long-term performance as a battery electrode,” says Dr Vilatela. This work is very much in line with wider objectives around reducing carbon emissions and addressing concerns about climate change. While a lot of attention is focused on introducing materials that store more energy, it’s also important to develop sustainable methods to produce batteries, and Dr Vilatela believes his group’s research could have a significant impact in this respect.“ Studies show that current battery cell manufacturing methods using processing solvents and polymers lead to several tonnes of CO2 being emitted at
www.euresearcher.com
meets the ambitious objectives set down by the European Union. “The goal of the EU is to have silicon anodes by 2025,” he says. This is motivated in large part by the need to reduce dependence on imports of the critical raw materials currently used in batteries, specifically graphite. “Most of the natural graphite suitable for batteries is found in Asia. So, in Europe there is a general recognition that it is critical to find a replacement,” explains Dr Vilatela. “We are now looking to accelerate the exploitation of this technology and its industrialisation.”
Project Funding
Funded by the Horizon 2020 Programme: ERC Starting Grant (Grant Agreement 678565) and ERC Proof of Concept (Grant Agreement 963912).
Contact Details
Project Coordinator, Dr. Juan Jose Vilatela IMDEA Materials Institute C/ Eric Kandel, 2 Tecnogetafe 28906, Getafe, Madrid (Spain) T: +34 915 49 34 22 E: juanjose.vilatela@imdea.org W: https://www.materials.imdea.org/ groups/mng/
https://pubs.rsc.org/en/Content/ ArticleLanding/2020/MH/D0MH00777C#!divCitation
Dr. Juan J. Vilatela
Dr. Juan J. Vilatela leads a research group focused on developing macroscopic materials made up of nanobuilding blocks in such a way that the unique properties at the nanoscale are preserved through the assembly process. This leads to the production of a new generation of highperformance engineering materials.
47