Hybrid battery and supercapacitor storage energy management for electric vehicles in low temperatures: Challenges, insights and future prospects

Hybrid battery-supercapacitor energy storage systems (HBSCESSs) have emerged to enhance electric vehicle (EV) performance under harsh environmental conditions. Cold temperatures severely impair battery performance, resulting in loss of capacity, increased internal resistance, reduced power capabilities and poor starting performance. While considerable research has addressed energy management strategies (EMSs), limited work has focused on consolidated EMSs tailored for cold start in EV-oriented HBSCESSs. This paper provides a comprehensive review to critically assess HBSCESS's energy management for EVs in cold climates. It discusses starting performance metrics, including cranking power capability, voltage regulation, startup time, and battery safety limitations. Subsequently, state-of-the-art EMS methods, including classical and rule-based, frequency-based, optimisation-driven, and artificial intelligence-based, are presented and discussed in terms of how they operate and help address cold-start failures. Special attention is given to how power delivery is managed, thermal effects are accounted for, and supercapacitor features are used to support low-temperature start reliability. The paper further identifies research gaps, including validation under low-temperature conditions, thermal-energy management coupling, and real-time realisability. Lastly, future research directions are proposed to enhance cold-start performance, system efficiency, and lifetime enhancement. This review provides a formal, mechanism-based foundation for developing HBSCESS design and control in next-generation EVs in cold climates.