The next generation battery materials will be found using supercomputers

Lithium batteries are considerably more expensive than alkaline batteries but they are already invaluable to the modern society since they are lighter, have a higher energy density, much longer lifespan and take up considerably less space. Lithium-ion (Li-ion) batteries are present in everything from smartphones, laptops and power tools to electric cars.

The annual production of Li-ion cells exceeds one billion, but even though the energy density of Li-ion batteries has more than doubled since they were introduced in 1991, the need for portable energy has grown even more. All over the world universities, conglomerates and individual companies are now researching on new generation batteries with even higher energy densities.

Batteries to match gasoline

The Technical University of Denmark (DTU) has performed research in the area of batteries for decades. Now, Associate Professor Juan Maria García Lastra from the Department of Energy Conversion and Storage (DTU Energy) at Technical University of Denmark has been granted 7 million DKK by the Villum Foundation to research and develop new materials for the next generation high density batteries using supercomputers for calculations and simulations.

“Lithium-ion batteries are state of the art right now, but their energy density remains one order of magnitude smaller than that of gasoline. If we are to reduce the use of gasoline powered cars, we have to develop electric cars with batteries that can match the energy density of gasoline”, explains Juan Maria García Lastra.

Metal-air batteries (MAB) are promising candidates to take over from Li-ion batteries, although they suffer from several major drawbacks that must be solved before they can enter the market. One major drawback is the formation of a non-conducting layer on the cathode during the discharge of the batteries, resulting in what is called sudden death of a battery when the electron-conductivity suddenly ends.

“We will have to enhance the conductivity of the insulating layer and either hinder its formation or make it less insulating to allow electrons to pass through”, says Juan Maria García Lastra.

Several metallic materials are being considered as candidates in the present project “In silico design of efficient materials for next generation batteries (Mat4Bat)” and one thing they all have in common is that they are proven to be rechargeable when used in batteries. The team will focus on aluminum, sodium and the well-known lithium.

“We have conducted research on lithium-air batteries for three years, and now we expand it with two new materials.”

Supercomputers become outdated too fast

Research in performance, longevity, electrical conductivity and high energy density in metal-air batteries requires in-depth understanding of the basic, fundamental properties of electron and ion-conductivity on the nanoscale. Despite decades of research these aspects still elude scientists all over the world.

“We have to develop new theoretical knowledge and go beyond the state of the art. In order to obtain this new knowledge, we need new theoretical models. These models are so complex that we need to use supercomputers to deal with them and see what they predict”, says Juan Maria García Lastra.

The traditional trial-and-error experimental strategies are too slow and expensive if the DTU-team is to find viable solutions. Instead the team will develop algorithms for the supercomputers for predicting possible materials and subsequently testing them, but the process will need vast amounts of computer power.

“We are going to do some very heavy calculations. We estimate that we need the power of 100 CPU cores in parallel during a week for just one specific calculation. Even though we have access to the Niflheim supercomputer at DTU, it is gradually becoming outdated. So we will have to update Niflheim with the newest CPU cores if we are to make inroads in the chemistry and explore new territories within battery-research.”

Strategies and Collaborators

Exploring uncharted territories has always been a time-consuming process and the development of functional algorithms to find new materials for the next generation high density batteries is no small feat. The DTU-researchers, however, are prepared for this challenge.

One strategy of the DTU researchers will include testing the new theoretical tools and models on known systems such as Li-ion batteries.  This will also improve the knowledge and understanding of existing battery-techniques and materials along the way. They will also be collaborating with leading groups within the field of battery development and leading groups within computational simulations. Collaborations within the battery field include Professor M. Stanley Whittingham, one of the founder of the Li-ion-technology, from Binghamton University and Professor Shao-Horn, a leader in the field of metal-air batteries, from MIT (Massachusetts Institute of Technology). Professors Ángel Rubio from the Max Planck Institute for Structure and Dynamics of Matter in Hamburg and Stefan Kurth of the Nano-bio Spectroscopy Group  from the University of Basque Country in Spain are pioneers in the field of theory and will collaborate on modelling and development of novel theoretical tools.

“First we develop theoretical tools and algorithms and apply them to known results.  We subsequently screen all the different materials with our models and eventually will be able to predict possible materials and test the promising candidates in the labs. It will take some time but I am optimistic”, says Juan Maria García Lastra.

The project will last five years. Two PhD students and two postdocs will be hired for the project.