Techniques in Hardware Implementation of Online Li-Ion Battery Cell Impedance Measurements

Lithium-ion (Li-ion) batteries have become increasingly dominant in the electrification of transportation in recent years. Despite this popularity, Li-ion batteries face several challenges such as safety hazards and environmental issues from the landfilling of battery waste. Safe and long-lasting battery operation can be achieved by continuously monitoring key state parameters such as the battery temperature and state-of-health (SOH). However, battery state estimation methods often require complicated and computationally heavy modeling techniques that can be difficult to implement at low cost. Studies have shown the potential of applying cost-effective online battery impedance measurement in the estimation of battery state parameters. An online battery impedance measurement setup can be implemented in several ways, each of which offers various practical advantages and disadvantages. This paper presents three methods of implementing an online impedance measurement for a Li-ion battery cell. Experimental measurement results from a commercial Li-ion battery cell are presented to demonstrate the effectiveness of each method. The advantages and disadvantages of each method are also discussed in detail. The work is a revised and extended version of a presentation at ECCE2023 [1].