Efficient and Safe Battery Operation – Aspects of Expansion and Utilization

Efficient yet safe operation of Li-ion batteries is a main consideration for their application in electric and hybrid electric vehicles. Observations of swelling of commercial cells during cycling pose a serious safety concern and motivate the study of expansion and pressure effects on cell performance and on local conditions and dynamics within cells. The use of mixed active material electrodes in commercial and near commercial Li-ion cells, some of which suffer from large volume expansion, further encourages this direction of research and also motivates investigation of material utilization. The mixing of different active materials is motivated by their complementary properties regarding for example capacity, power, safety, or stability. Their competing kinetics within one electrode can be expected to have effect on material utilization and local conditions within the cell during complex cycling, such as hybrid vehicle cycling. Using electrochemical models, the interior of batteries can be probed, with information of local conditions in relation to cell performance. The development of physics-based models in close communication with experimental observations serves to create diagnostic tools to increasing our understanding of Li-ion batteries and their continuous development for vehicle applications.

This proposed project spans from June 1 2016 – December 31 2017 and entails electrochemical modeling studies and experimental characterizations of different battery/electrode chemistries where the interplay of pressure/expansion and electrode dynamics is of interest. A focus is kept on commercial cells and cell conditions relevant to usage in electrified vehicles. KTH Royal Institute of Technology is the main applicant, and the projects is performed within Swedish Electric and Hybrid Vehicle Center, with collaboration from industrial partners Scania, AB Volvo and Volvo Cars Corporation, and academia with Uppsala University.

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