Researchers in Germany have presented a systematic approach to quantify EV battery degradation across various charging strategies. They conducted battery aging experiments under designed conditions reflecting the characteristics of real-world driving and V2X applications, including Vehicle-to-Home (V2H) and Vehicle-to-Grid (V2G) applications.

They also carried out a comprehensive parameter study to explore the intricate relationships between V2X applications and battery degradation. A paper on their work is published in eTransportation.

Gong et al.

The Vehicle-to-Everything (V2X) concept enables vehicles to connect with various entities, including other vehicles, pedestrians, infrastructure elements, and the electric grid. Within the context of this paper, V2X pertains specifically to concepts and technologies that unlock the potential of EVs by enabling bidirectional energy exchange between EVs and the power grid. Beyond the reduction in energy costs for EV owners, the implications of V2X extend to substantial benefits for grid infrastructure. These include more efficient management of electrical resources, increased use of renewable energy sources, and the potential to alleviate costs for future grid infrastructure expansion.

In accordance with the targeted beneficiaries, V2X can be categorized into three domains: Vehicle-to-Home (V2H), which uses EV batteries as mobile energy storage to supply household power; Vehicle-to-Building (V2B), involving EVs in building energy systems for load balancing, peak demand reduction, incorporation of renewable energy sources, and the optimization of energy utilization patterns; Vehicle-to-Grid (V2G), where EVs supply energy to the grid and engage in ancillary services, and arbitrage in energy markets.

V2X exhibits the potential to prolong the lifespan of an EV battery compared to conventional unidirectional charging methods by allowing controlled charging and discharging. Battery aging is influenced by a variety of factors, including battery chemistry, charge and discharge rates, state-of-charge (SOC), cell temperature, depth-of-discharge (DOD), the number of charge–discharge cycles. Additionally, based on recent findings, the current mode is also recognized to be critical for battery aging. Different dynamic loadings, constant current, multi-state current, and pulse current are influencing factors in cyclic battery aging.

… While existing studies offer insights into either battery aging or revenue potential in V2X applications, they lack specific calibration for V2X-based EV operations and often rely on limited scenarios. This paper is motivated by the need for a specific approach that simulates different V2X charging strategies and accurately assesses their impact on battery health. Therefore, a comprehensive method is presented, which is aimed at realistically simulating V2X applications and understanding the effects of both unidirectional and bidirectional V2X charging strategies on EV battery degradation.

—Gong et al.

The experimental results showed that the aging spread between all V2X and reference scenarios of 3.09% SOH after 20 months is lower than the spread caused by cell-to-cell manufacturing variation under identical conditions reported in the literature.

The results of the parameter study reveal that adopting V2X applications, in addition to primary mobility prospects, does not significantly increase battery degradation and can even reduce capacity loss compared to the conventional uncontrolled charging strategy if properly configured.

Resources

• Jingyu Gong, David Wasylowski, Jan Figgener, Stephan Bihn, Fabian Rücker, Florian Ringbeck, Dirk Uwe Sauer (2024) “Quantifying the impact of V2X operation on electric vehicle battery degradation: An experimental evaluation,” eTransportation doi: 10.1016/j.etran.2024.100316