Influence of cathode composition on air-cooling efficiency of Lithium-ion cells

Lithium-Ion batteries, so far represent the technology that best fits the needs of electric mobility, due to a number of advantages with respect to other alternative solutions, such as higher energy and power densities and longer cycle life. However, there are safety concerns that still hinder their adoption in a wider range of applications: in the absence of efficient temperature control, at high operating temperatures a thermal runaway can occur, with possible destruction of the cell itself and the generation of other dangerous phenomena (fires and explosions). This problem is particularly important when a large number of cells are connected together in a whole pack, where the failure of a single cell can impact additional cells in its proximity with the possible generation of even more catastrophic consequences. In the present study, 3D simulations have been carried out to assess the cooling efficiency of an air flow, under various operating conditions, on several cylindrical Li-ion cells, characterized by different cathode compositions. Under the investigated configurations, it was found that, beyond a minimum value of the passing air velocity, it is possible to prevent a generalized thermal runaway keeping the cells within safe temperature conditions; however, the cathode material also plays a significant role, with some configurations showing a safer behaviour with respect to others, characterized by a more pronounced susceptibility to thermal instability.