Impedance-based health indicators determination for degradation diagnosis and fault identification of lithium-ion batteries under extreme operating conditions

Abstract

Research is underway on ex-situ and in-situ methods for diagnosing the degradation of performance in lithium-ion batteries (LIBs) under various environmental conditions. Incremental capacity analysis (ICA) and electrochemical impedance spectroscopy (EIS) are a non-destructive in-situ method for determining battery health during operation. An electric vehicle (EV) operates for a long time under various environment and load conditions, so it is required to additionally investigate the battery degradation under extreme operating conditions. ICA-based and impedance-based health indicator (HI) are generally known to be capable of diagnosing a battery degradation mode (DM). Most of the EIS and ICA literatures are conducted at operating conditions, so it is questionable whether DM can be classified under extreme condition such as mechanical and high temperature conditions. This paper extracts impedance-based and ICA-based HI for diagnosing the soundness of lithium-ion batteries and proposes the optimal HI that can classify DM under extreme operating conditions. The degradation procedure was performed under extreme operating conditions, such as 60 °C temperature and vibration. The validity of the HIs was verified by comparing ICA-based and impedance-based HIs through environmental tests.