Investigating electrical contact resistance losses in lithium-ion battery assemblies for hybrid and electric vehicles

► In this paper the energy loss due to electrical contact resistance (ECR) at the interface of electrodes and current-collector bars in Li-ion battery assemblies is investigated for the first time. ► A custom-designed testbed is developed to conduct a systematic experimental study. ECR at electrode connections of a sample Li-ion battery is measured, and a straightforward analysis to evaluate the relevant energy loss is presented. ► Effects of surface imperfection, contact pressure, joint type, collector bar material, and interfacial materials on ECR are highlighted. ► The obtained data show that the energy loss due to ECR can be as high as 20% of the total energy flow in and out of the battery under normal operating conditions. However, ECR loss can be reduced to 6% when proper joint pressure and/or surface treatment are used.