Safety evaluation of lithium-ion batteries

摘要

Little data exists in the public domain fi)r lithium-ion batteries that have encountered prolonged cycling and operation at high rates and high temperatures.Six UR18650 lithium-ion cells were continuously charged/discharged at a constant temperature of 50°C at currents of 3.2A, 2.6A or l.3A charge and discharged at 1.3W to a capacity cutoff of 65mAh. No cells showed any venting, fire or bulging during orafter the tests.The amount of hydrogen, was measured by placing chips scraped from the negative electrode in water. The amount of hydrogen from the "as received" and cells after completion of cycling was less than 15 I/kg/hr. However, the amount of hydrogen evolved fromthe negative electrode of fully charged cells was as high as 87.4 l/kg/hr.Two fully charged cells were subjected to the DoT nail penetration test. No venting, fire or explosion we observed.