Hybrid Energy Storage System for the Life Extension of Lithium-ion Batteries in Electric Vehicles

In the quest to further improve the performance of battery electric vehicles (BEVs), one of the most critical objectives is to increase the reliability and efficiency of energy storage systems. In spite of their promising features, Lithium-ion batteries (LIBs) are beset by energy-power imbalances. To address the issue, this study presents the design and modelling of a hybrid energy storage system (HESS), comprising an energy-specific LIB in conjunction with a power-specific LIB. In this case, Nickel Manganese Cobalt (NMC) battery is selected as an energy LIB and Lithium Titanate Oxide (LTO) battery serves as a power LIB. The primary aim of this study is to examine the effectiveness of the HESS in mitigating the effects of aging on energy-specific battery as well as meeting the high power requirements of BEVs by integrating the complementary qualities of power and energy batteries. The aging of the energy battery is studied with the help of a developed electrothermal-aging model. The HESS demonstrates a reduction in electrical and thermal stress, which in turn reduces the fall in state of health (SOH) of the energy-specific LIB by 36% in comparison to a pure NMC battery-based energy storage system.