Proposed Standards and Methods for Leak Testing Lithium-Ion Batteries with Empirically Derived Rejection Limits 2020-01-0448
Lithium-ion batteries are a highly suitable energy source for many applications, particularly in the automotive sector due to their high energy density and low self-discharge rate. During the production of battery cells, rapid detection of leaks is absolutely essential to achieve necessary lifetime and safety requirements. This applies particularly to small leaks that cannot be detected electrically immediately after the cell has been manufactured. Remarkably, for pouch cells there has been no reliable method available to detect small leak channels. This paper examines a spectrum of leak scenarios for cylindrical, prismatic and pouch lithium-ion batteries. Rejection limits for lithium-ion batteries have not been codified. Fact-based rejection limits now have been empirically established.
This presentation will discuss how small leaks—down to the 10e-6 mbar l/s range—can be detected reliably and quantitatively on potentially leaking battery cells through detection of escaping liquid electrolyte vapors, typically DMC (dimethyl carbonate). The test system is applicable to non-rigid pouch cells and rigid prismatic or cylindrical cells, which permits non-destructive testing of any lithium-ion battery cell.