Swiss


Lithium ion batteries could provide a greener alternative to fossil fuels, but until now their production has been ironically energy intensive. Anna Demming speaks to Professor Katharina Fromm about how her group has improved the efficiency of battery material production and the other applications the research could benefit.


Lithium battery materials: The right arrangements for efficient production


Companies are already producing lithium ion battery materials on a large scale.


However, the high energy


consumption of conventional production methods impinges on the viability of lithium ion batteries as an environmentally friendly alternative to fossil fuels. “I went to see some of the companies


that produce electrode material and battery material and it was a little bit of a shock to me,” explains Professor Katharina Fromm, head of the Fromm group at Fribourg University in Switzerland. “They had huge buildings with large ovens where they would bake the compounds — everybody was working in T-shirts and yet all the windows were still open, in winter. They were heating the environment.” The current convention for making ion


battery compounds is to mix several metal oxides at low temperature to obtain the correct stoichiometric ratio. The mixture is then heated to 800°C or even 1000°C for up to 24 hours over an oxygen stream. This is followed by a second sintering stage at similar temperatures for around another 12 hours. “It starts with cheap ingredients but it takes a long time and is also a high- energy consumption procedure,” says Professor Fromm. “So we thought maybe there is something we could do about it.” One of the main research areas in the


Fromm Group is the study of multimetallic precursor compounds. “These are molecules that can contain many different metal ions in a specific ratio to each other,” Professor From explains. The molecules are linked to each other by so-called ligand molecules. The


ligands are carbon-based ‘organic’


molecules and are burnt away to form the mixed metal oxide materials. In fact, it turns out that the organic ligands are key to the group’s success in developing an energy-efficient approach to producing battery electrode material. Good electronic performance in lithium ion batteries requires metal oxides in a


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high-temperature phase, a particular molecular organisation that the material naturally assumes at very high temperatures. Professor Fromm and her colleagues found that, using organic ligands, they could pre-arrange the molecules into the structure of the high- temperature phase of the compound. Then


the ligands could be removed at a much lower temperature and over much shorter processing times to achieve the


same


material as the more energy-intensive conventional approaches. “This is the trick – to pre-organise the metal ions previously before we burn the organic stuff away,” adds Professor Fromm. With this approach


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