Evaluation of lithium-ion battery second life performance and degradation

Reusing electric vehicle batteries once they have been retired from the automotive application is stated as one of the possible solutions to reduce electric vehicle costs. Many publications in the literature have analyzed the economic viability of such a solution, and some car manufacturers have recently started running several projects to demonstrate the technical viability of the so-called battery second life. Nevertheless, the performance and degradation of second life batteries remain an unknown topic and one of the biggest gaps in the literature. The present work aims at evaluating the effects of lithium-ion (Li-ion) battery State of Health (SOH) and ageing history over the second life performance on two different applications: a residential demand management application and a power smoothing renewable integration application. The performance and degradation of second life batteries are assessed both at the cell level and at stack level. Homogeneous and heterogeneous stacks are analyzed in order to evaluate the impact of cell-to-cell history and SOH differences over the stack level battery cell performance and degradation behaviour.