Lube-Tech
A major innovation in terms of battery safety There was frequent dialogue with automobile manufacturers during the development of this fluid. This dialogue also highlighted the research into enhanced safety, another key factor when it comes to the design of battery packs where the biggest fear is the propagation of thermal runaway (a sharp increase in the temperature of the electrochemical cell temperature (>400°C) that can start a battery pack fire) [13].
Significant attention was paid to securing a thorough grasp of the issue of thermal runaway in battery packs and the extent to which the use of a dielectric fluid can help. Again, specific test procedures were conceived to improve the ability of TotalEnergies fluids to resist temperature leaps of the kind that are observed in this sort of situation. The engineers in charge of the project focused on the fluid’s resistance to high temperatures aimed at preventing secondary accidents resulting from inflammation and the propagation of thermal runaway to neighbouring cells (a description of the scientific approach taken to this work is described in an SAE paper [11].
Furthermore, in-house tests permitted the development of a fluid with a particularly high resistance to high temperatures with no detriment to its outstanding thermal properties, as illustrated in Table 3 below.
Figure 8: Top: damage test rig involving driving a nail through cell #2. Bottom: results.
Table 2: Characteristics of Quartz (chk) EV Battery fluid– Cell Shield.
The table in Figure 8 (right) presents the results. In the case where the cells were surrounded by air, there was propagation of thermal runaway. This was not the case when the cells were immersed in a dielectric fluid. A difference was observed between the use of a conventional hydrocarbon fluid (PAO2) and the specifically-developed fluid which did not catch fire. The use of this specific fluid consequently marks an
LUBE MAGAZINE NO.168 APRIL 2022 31
PUBLISHED BY LUBE: THE EUROPEAN LUBRICANTS INDUSTRY MAGAZINE
No.139 page 6
In order to demonstrate the performance of this fluid, a module consisting of nine Samsung 21700 5A.h cells was subjected to a damage test, whereby a nail was driven through cell #2 (Figure 8) to ascertain whether the thermal runaway would spread, as well as the fluid’s behaviour in this sort of situation.
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