Extra throughput versus days lost in V2G services: Influence of dominant degradation mechanism

Electric vehicle (EV) batteries are often underutilized. Vehicle-to-grid (V2G) services can tap into this unused potential, but increased battery usage may lead to more degradation and shorter battery life. This paper substantiates the advantages of providing load-shifting V2G services when the battery is aging, primarily due to calendar aging mechanisms (active degradation mechanisms while the battery is not used). After parameterizing a physics-based digital-twin for three different dominant degradation patterns within the same chemistry (NMC), we introduce a novel metric for evaluating the benefit and associated harm of V2G services: and show its strong relationship to the ratio of loss of lithium inventory (LLI) due to calendar aging to the total LLI (). Our results which focus systematically on degradation mechanisms via lifetime simulation of digital-twins significantly expand prior work that was primarily concentrating on quantifying and reducing the degradation of specific cells by probing their usage and charging patterns. Examining various cell chemistries and conditions enables us to take a broader view and determine whether a particular battery pack is appropriate for load-shifting V2G services. Our research demonstrates that the decision ”to V2G or not to V2G” can be made by merely estimating the portion of capacity deterioration caused by calendar aging. Specifically, TvD is primarily influenced by the importance of aging while EV is at rest and the environmental temperature where the car is parked, while the usage intensity and charging patterns of EVs play a lesser role.

电动汽车（EV）电池往往未得到充分利用。车网互动（V2G）服务可以挖掘这种未被利用的潜力，但电池使用增加可能会导致更多的损耗和更短的电池寿命。本文证实了在电池老化时提供移峰填谷型V2G服务的优势，这主要是由于日历老化机制（电池未使用时的主动退化机制）。在对同一化学成分（镍锰钴，NMC）内三种不同的主要退化模式的基于物理的数字孪生进行参数化之后，我们引入了一种新的指标来评估V2G服务的益处和相关危害：并且展示了它与因日历老化导致的锂库存损失（LLI）与总LLI的比率之间的紧密关系。我们通过数字孪生的寿命模拟系统地关注退化机制的研究结果，极大地扩展了先前主要通过探究特定电池的使用和充电模式来量化和减少其退化的工作。对各种电池化学成分和条件的研究使我们能够有更广阔的视角，并确定特定的电池组是否适合移峰填谷型V2G服务。我们的研究表明，“是否进行V2G”的决策可以仅仅通过估计由日历老化导致的容量退化部分来做出。具体而言，TVD主要受电动汽车静止时老化的重要性以及汽车停放的环境温度的影响，而电动汽车的使用强度和充电模式的影响较小。