M/F PhD Towards positive electrode materials for innovative potassium-ion full-Cell

Updated: 29 days ago
Location: Tremblay en France, LE DE FRANCE
Deadline: 09 Nov 2019

Created in 1995, the Bordeaux Institute of Condensed Matter Chemistry (ICMCB)
focuses its research on Solid Chemistry, Materials Science and
Molecular Sciences: designing, preparing, shaping and characterizing
materials to discover, master and optimize specific functions.
The ICMCB conducts fundamental research on model materials and / or
likely to have applications.
The complementarity of approaches and the synergy thus created have allowed the Institute
to reinforce its national and international position in the field of materials.

The goal of the collaborative project between ICGM in Montpellier, IPREM in Pau and ICMCB in Bordeaux, performed in the frame of the RS2E French Network on the Electrochemical Energy Storage, will be to answer to the questions: are K-ion systems competitive with Li-ion and Na-ion batteries? Are the benefits of K in terms of ionic conductivity in organic electrolytes, energy density (in agreement with a very low standard potential), abundance and cost, higher than the limitations expected from its higher atomic mass and Shannon's ionic radius compared to Li+ and Na+? As a proof of concept, K-ion batteries combining efficient positive and negative electrodes with a suitable electrolyte will be prepared in the frame of the project.
The subject of the PhD thesis performed in collaboration between ICMCB in Bordeaux and ICGM in Montpellier will be focused on polyanionic frameworks (KMPO4X-type structure) by playing with the nature of both the transition metal ion and the anion, and on Prussian Blue Analogues (K2M1[M2(CN)6]y.zH2O) as positive electrodes. The first step will be to synthesize a large panel of materials, and then to select two of them (one polyanionic and one PBA) as the materials of interest to prepare full K-ion cells. The second step will be to characterize the reactions involved upon their cycling in K-ion batteries. Indeed, it is crucial to get in-depth knowledge of the structural and redox mechanisms occurring during the de-intercalation and re-intercalation of the K+ ions from/into the framework and to determine their reversibility. For this K-ion battery technology, it will be even more important to characterize the degradation mechanisms occurring at the interface between the electrode and the electrolyte. Complementary diffraction and spectroscopy techniques will be combined to reach this knowledge, often in situ and operando during the operation of the battery.
As the project will be performed in the frame of a collaboration involving ICMCB (Bordeaux), ICGM (Montpellier) and IPREM (Pau), mobility of the PhD student will be required, especially between Bordeaux and Montpellier. Indeed, the student will share his time between the two labs..

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