• Miles Rivett

  • Theme:Low Carbon Fuels
  • Project:Thermal Management and Degradation Pathways of Sustainable Batteries
  • Supervisor: Chris Vagg ,Alex Lunt ,Frank Marken
  • The Gorgon's Head - Bath University Logo
Photo of Miles Rivett

Bio

Miles graduated from the University of Hull in 2021 with an MChem (1st Class Hons) in Chemistry. During his degree, Miles developed a strong passion for chemical sustainability and its place within Industry and worked on projects researching sustainable transition metal catalysts for the synthesis of biodegradable polymers.

Miles's industrial experience has covered product innovation, optimisation, and sustainability within the chemical manufacturing industry. He worked for two years at Venator Materials as a product and application technologist. The role expanded his knowledge of product development and application testing, as well as the challenges faced in the industry, namely  environmental, regulatory, and customer requirements. 

Miles's passion of environmental sustainability continued to grow and he started researching the challenges other industries faced as they move towards net zero climate targets. His passion for the automotive industry, particularly the electrification of passenger vehicles inspired him to apply for the AAPS CDT to develop his knowledge of electric propulsion system and to contribute to its progression towards a more sustainable future.

FunFacts

  • I love all types of motorsport and have watched Formula 1 since I was six.
  • Classic car enthusiast and amateur mechanic. I enjoy fixing my own cars when they have any issues.
  • I enjoy learning about countries languages and cultures. I have visited over 15 countries and have been learning to speak German for over 10 years.
  • I have cared for five species of pets during my life, mainly cats and ferrets!

Thermal Management and Degradation Pathways of Sustainable Batteries

Miles' research will focus on understanding the link between battery degradation and methods of battery thermal management, especially with respect to cells of different sizes.

Exposure to high temperatures and temperature cycling are two of the most significant aggravating factors for battery aging. The trend in automotive applications is for ever increasing cell sizes, with some vehicles now featuring cells of several hundred amp-hours and up to 1m long. As cells sizes increase achieving a uniform temperature across and through the cell is increasingly difficult because only the cell surface is cooled, and because the cooling fluid (air/water/oil) will typically reach some parts of the cell before others. This non-uniform temperature distribution will very likely lead to non-uniform aging of the cells, which Miles' PhD aims to investigate, quantify, understand, and propose mitigation mechanisms against. This is an important topic not only for maximising the lifetime of the cells in the vehicle, but also when considering the potential value of the cells in second life, or how they might be recycled.

Work will focus initially on immersive cooling, where battery cells are directly immersed in a dielectric oil. This is because immersive cooling is considered the most advanced and high-performance approach to thermal management and is a current focus for research. Problems with this include the cost and weight added to the system by the fluid. This trade-off will be examined by considering the possibility of partially filling the battery with fluid so that cells are only partially submerged, reducing fluid weight at the expense of some thermal homogeneity.

Opportunities may exist for synergy with the group working on Structural Batteries, depending on the size scale of the batteries which that group have succeeded in producing by this time. These opportunities will be explored as appropriate, as the relevance of this proposed doctoral research is particularly relevant to structural batteries owing to their increased value and added difficulty in recycling them. The work of the existing group to date has focussed primarily on producing working batteries. Degradation has not yet been investigated, and whilst recyclability has been embedded in materials selection no analysis has been performed in this space.

Electrochemical testing of cells will be possible with charging/discharging experiments and electrochemical impedance monitoring. Microstructural characterisation of the impact of degradation will form a key aspect of the doctoral study. This will involve the use of nanoindentation, electron and atomic force microscopy and/or Focused Ion Beam (FIB) to study internal changes to the microstructure through the preparation of microscale cross-sections and lamella. Synchrotron work (microtomography, X-ray diffraction, and/or spectroscopy) with in-situ electrochemical testing will reveal regions of heating/degradation, formation of stresses locally at anode or cathode, and opportunities for retaining battery performance. These insights will be used to generate enhanced models of degradation, providing crucial insights into predicted lifetimes and potential recycling opportunities associated with these systems at end of life.

 

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