Understanding the ageing of rechargeable batteries (EEE-25-Walther)

Details

There is a huge demand for improving battery technology, mainly in the fields of global energy supply, electric vehicles and also portable consumer electronics:

● The expansion of renewable energy sources like photovoltaics and wind power must be accompanied by an expansion of energy storage facilities, some of which will be in the form of large battery packs that can store electrical energy when it is in over-supply and quickly liberate it when there is increased demand.

● More and more cars, lorries and buses will be equipped with electric motors and hence need large, reliable and safe batteries. These make up a large fraction of the weight and the cost of electric vehicles.

● Many household items and consumer electronics have been miniaturised within the last two decades and so have become portable, and for their use rechargeable batteries are needed.

This means better, safer and cheaper rechargeable batteries of different sizes will have to be developed, ranging from button cells for small electronic appliances to industrial-scale big battery packs in power stations for the national grid. There is thus both the drive to develop more efficient battery technologies and to better integrate series of rechargeable batteries into stacks for large power supplies.

This study will investigate the physical and chemical changes encountered during battery cell ageing, leading to an improved understanding how battery cells age and how their ageing can be mitigated by optimising the charge/discharge cycles. One aspect will also focus on differences between long-term calendar ageing, thermally accelerated ageing and repeated charge/discharge cycling. 

A combination of modelling and experimental methods will be used, with an emphasis on combining electrical measurements to assess electrical charge capacity, thermal imaging to determine hot spots during charging/discharging, micro computed tomography (µCT) using X-rays to monitor the three-dimensional structure of cells in-situ on the micron scale and post-mortem analysis of specific cross-sectioned cells for studies by scanning electron microscopy (SEM). 

The latter will include

●  monitoring local porosity (from mm down to 10nm) within the electrodes by secondary electrons (SE),

●  measuring local swelling of electrodes under stress by back-scattered electron (BSE) imaging,

●  investigating the interplay of redox reactions and elemental interdiffusion by energy-dispersive X-ray (EDX) spectroscopy and mapping,

●  studying crystallographic phase changes by electron back-scatter diffraction (EBSD).

Interested candidates are strongly encouraged to contact the project supervisors to discuss your interest in and suitability for the project prior to submitting your application.

Please refer to the EPSRC DTP webpage for detailed information about the EPSRC DTP and how to apply.

Apply Here: Application Form (sheffield.ac.uk)