Technical Viability of Battery Second Life: A Study From the Ageing Perspective

Reusing electric vehicle batteries once 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 degradation behavior of second life batteries remains unknown and represents one of the biggest gaps in the literature. This paper aims at evaluating the effects of lithium-ion nickel manganese cobalt/carbon (NMC/C) 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 were assessed both at the cell level and at stack level. Homogeneous and heterogeneous stacks were analyzed in order to evaluate the impact of cell-to-cell history and SOH differences over the battery performance and degradation behavior. Results obtained showed a strong influence of the first life battery ageing history upon the second life battery performance and degradation. Thereby, proper monitoring and battery selection appears crucial to certify the technical viability of battery second life.