Novel methods to initiate, analyse, and mitigate battery failure

As lithium-ion cells increase in energy and power density, and with their expanding range of applications, there is a need for underpinning research to support their continued safe operation. One key concern is sidewall rupture, an important failure mode identified in cylindrical Li-ion cells. This failure mode has been linked to thermal runaway propagation (a process in which a cell enters an uncontrollable, self-heating state, which can spread to adjacent cells, potentially leading to fire).

To improve the understanding of the science of battery safety, SafeBatt researchers at WMG, University of Warwick, developed a novel experimental method to determine the conditions under which sidewall rupture occurs. The team has identified experimental parameters that successfully initiate this failure mode in 75% of cases. The method has been exploited in novel experiments to investigate the effect of sidewall rupture on thermal runaway propagation in adjacent cells. Results have shown that the occurrence of sidewall rupture is indeed coincident with increased propensity for thermal runaway propagation. The team subsequently investigated mitigation techniques and published new methods to assess the performance of passive barriers in containing sidewall rupture in multi-cell systems.

WMG researchers have also developed ‘smart cells’ to aid the development of early thermal runaway detection and mitigation strategies. These innovations include novel instrumentation techniques that measure a cell’s internal temperature and pressure during thermal runaway, as well as methods to collect internal gases generated in the pre-venting stage of thermal runaway.

These findings can be exploited by industry to develop safer battery systems and create new simulation models to predict thermal runaway behaviour.

Image: An X-ray computed tomography radiograph of the instrumented smart cell, with the temperature sensor visible in the central cavity of the cell.

Case study published December 2024.