A fast method for evaluating stability of lithium ion batteries at high C-rates

Evaluating the stability of a lithium ion battery (LiB) typically involves the measurement of a few hundred charge and discharge cycles during the development stage before mass production. However, such a test method requires at least two to four months of the test period and requires repeated tests upon any change in the battery designs or chemistries. As a result, this lengthy evaluation process significantly delays the overall product development. For this reason, Samsung develops a fast evaluation method to test the stability of LiBs using a set of symmetric charge and discharge pulses at high C-rates. This set causes side reactions within the cell, which in turn lowers the state-of-charge and coulombic efficiencies (CE) of the cell compared to that before applying the pulses. By comparing the CE of the cycles with and without the pulses, the stability of LiBs in fast charge and discharge conditions are quantitatively evaluated. It is believed that the method presented in this work can reduce the evaluation time significantly, from several months to less than three days, which is beneficial to general battery research activities by significantly reducing time, resources, and cost. [Display omitted] •A test method is introduced to evaluate stabilities of lithium ion batteries.•The method involves charge and discharge pulses where the net capacity is zero.•The symmetric pulses cause side reactions if a battery is not stable.•The amount of side reactions is quantitatively extracted as a coulombic efficiency.