A review of state-of-health estimation for lithium-ion battery packs

With the rapid advancement of lithium-ion battery technology, the estimation of the state of health (SOH) of lithium-ion battery packs plays a crucial role in enhancing the safety and reliability of their operation. However, few researchers have reviewed SOH estimation for lithium-ion battery packs so far. In order to fill this gap, this paper will review and discuss the past proposed methods on SOH estimation for lithium-ion battery packs. This paper first introduces the working principle of lithium-ion battery packs and their degradation mechanisms at chemical and mechanical levels during continuous charging and discharging, and describes the impact of internal inconsistencies in battery packs on overall performance degradation. This is followed by a systematic summary of existing degradation state identification and SOH estimation methods and an analysis of the limitations of these methods in practical applications. Lastly, the difficulties currently encountered in estimating the SOH of Li-ion battery packs are discussed, along with potential directions for future research. It is hoped that this paper will be a useful reference for scholars working in relevant fields.