Preventing Thermal Runaway Propagation of 3.2 Ah Lithium-Ion Cell Battery Packs with Phase Change Composite Material: Investigating a Cell-Air-PCC (Air-Gap) Design

摘要

Nail penetration of a cell situated in a Lithium ion battery pack constructed of PCC material populated with commercial cells has been conducted. The thermal and voltage response of the trigger and neighboring cells was recorded. Characterization of a new design employing loosely-fitted cells with an air layer between each cell and the surrounding PCC was performed and compared to previous designs with tightly-fitted cells. Packs with tightly-fitted cells did not experience thermal runaway propagation however neighboring cells experienced temperatures previously observed to initiate thermal runaway. Severe thermal runaway propagation occurred in the loosely-fitted pack design resulting in excessive damage to the pack. Proposed mechanisms for propagation were cell ejecta ignition and radiation through the added air-film. Thermal and voltage responses, along with post-mortem analysis revealed several cell and pack safety mechanism failures that will be investigated in future work.