The limited energy density, lifetime and rate performance of Li-ion battery cells remain a hurdle for their adaptation in e.g. electric vehicles. Whereas the focus has been on the quest for new electrode chemistries with higher energy, advances in the electrode architecture are needed to be able to increase the accessible Li-ion capacity of the electrode materials at relevant charging rates. The high energy cells of today can deliver about 700Wh/L and need about 1.5 hours to charge. Through optimization of the electrode architecture only, one should be able to exceed cell energies of 800Wh/L and charging at full capacity in about 30 minutes. The performance of the electrodes can be improved considerably by coating of powders with extremely thin-films. These coatings can, for example, provide a protective function to increase the life time of the Li-ion cell. As such, ultra-thin coatings deposited by a technique known as Atomic layer deposition (ALD) have shown to improve the lifetime of Li-ion batteries. It would, however, be much more interesting if these coatings could also increase the electronic and ionic conductance of the electrode particles themselves. As such, the accessible capacity and rate performance of the electrodes could be increased considerably. An issue with these inorganic thin-film coatings around the electrode particles is that they can break and as such quickly degrade due to fact that the electrodes swell and shrink during the successive discharging and charging of the battery cell. As a solution, molecular layer deposition (MLD) of mixed conductor coatings (i.e. layers conducting both electrons and ions) will be investigated in this PhD work. MLD is a self-limiting deposition technique very much similar to ALD but with this difference that organic molecules or polymers are built in the inorganic coating. As such, the elasticity of these hybrid materials can be tuned. The combination of elastic, electronic and/or ionic conductivity in these thin-film coatings is expected to improve the battery’s lifetime, energy density and rate performance.
During your doctoral research, you will develop MLD processes of functional electrode coatings that help accommodate the volume changes in the electrodes. You have or will acquire a strong background in hybrid organic-inorganic and mesoporous materials, knowledge of ALD/MLD processes and material characterization techniques. In addition, you will acquire hands on experience with various electrochemical characterization techniques. You will perform your research in the electrochemical storage team in imec in close collaboration with the COCOON group at Gent University.
Required background: chemistry, nanomaterials, physics or an equivalent background with interest in electrochemistry.
Type of work: experimental
Supervisors: Philippe Vereecken, Christophe Detavernier
Daily advisor: Brecht Put
The reference code for this PhD position is SE1712-34. Mention this reference code on your application form.