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PhD Defence Aditya Narayanan | Towards semi-solid flow batteries

Towards semi-solid flow batteries

Aditya Narayanan is a PhD student in the research group Physics of Complex Fluids (PCF). His supervisor is prof.dr. F.G. Mugele from the faculty of Science and Technology (TNW).

The Semi-Solid Flow Battery, a lithium ion based flow battery with electrodes in the form of particle slurries, is seen as a promising candidate for grid energy storage. Translating to a flow architecture however, presents unique challenges due to the dynamic nature of the colloidal slurries. Slurry electrodes are characterized by a (non-equilibrium) microstructure which can vary, depending on the acting forces and their history. Conversely, this structure at the microscale can have a significant influence on macroscopic properties. 

In this thesis, we study the impact of colloidal, mechanical and electrochemical effects on SSFBs and their fluid electrodes.  We do this using a novel instrument that allows us to control (and measure) both the mechanical and electrochemical state of fluid electrodes simultaneously. We find that mechanical forces and their history have a drastic effect on how the conductive particles wire electrochemically active particles. This is determined by a complex two stage agglomeration process. These results can help optimise pumping and storage strategies for such batteries. Subsequently we studied how electrochemical operation affects the battery. We found Solid Electrolyte Interface layer formation on particles, an essential component of traditional batteries, drastically hinders electron conduction in Semi-Solid Flow Batteries. We found these layers grow even when the battery is operated in regimes considered free of it, again with drastic effects. Our findings highlight the chemistry challenges to be overcome to realise such batteries.