Synthetic vs. Real Driving Cycles: A Comparison of Electric Vehicle Battery Degradation

Abstract

Automobile dependency and the inexorable proliferation of electric vehicles (EVs) compels accurate predictions of cycle life across multiple usage conditions and for multiple lithium-ion battery systems. Synthetic driving cycles have been essential in accumulating data on EV battery lifetimes. However, since battery deterioration is path-dependent, the representability of synthetic cycles must be questioned. Hence, this work compared three different synthetic driving cycles to real driving data in terms of mimicking actual EV battery degradation. It was found that the average current and charge capacity during discharge were important parameters in determining the appropriate synthetic profile, and traffic conditions have a significant impact on cell lifetimes. In addition, a stage of accelerated capacity fade was observed and shown to be induced by an increased loss of lithium inventory (LLI) resulting from irreversible Li plating. New metrics, the ratio of the loss of active material at the negative electrode (LAMNE) to the LLI and the plating threshold, were proposed as possible predictors for a stage of accelerated degradation. The results presented here demonstrated tracking properties, such as capacity loss and resistance increase, were insufficient in predicting cell lifetimes, supporting the adoption of metrics based on the analysis of degradation modes.

Perspective on Commercial Li-ion Battery Testing, Best Practices for Simple and Effective Protocols

“…Example of studies with blended electrodes can be found in [70,73]. In our past IC studies [44,53,59,65,[70][71][72][73][74][75], we often used different FOIs and entry points for the IC analysis depending on the chemistry and the experimental trends. This highlights that a step-by-step instruction list on how to perform the analysis is not possible and that it should always be guided by a sensibility analysis to be repeated for every new study.…”

“…The definition of the duty cycle test is the most important part of any degradation or validation study. Battery degradation is path dependent [10,74,[76][77][78][79][80] meaning that different conditions are degrading battery differently, not just increasing or decreasing the rate. Therefore, to be representative of a given application, the duty cycle to be applied needs to be as close as possible to the real use, which is most likely stochastic [74,[76][77][78][79][80].…”

“…If datasets are available, fuzzy logic [81] and statistical analysis [82] are good options to define a representative usage cycle. Alternatively, literature might suggest adapted duty cycles, although they might not be fully representative [74].…”

Multicriteria Approach to Sustainable Transport Evaluation under Incomplete Knowledge: Electric Bikes Case Study

“…Hence, the space of the investigated problem is equal to 8. Based on [69][70][71][72][73][74][75][76][77][78][79][80], the following criteria are specified: [74,79].…”

Batteries and Supercapacitors Aging

“…Topics of interest include, but are not limited to: In response to this call of papers, 12 research papers [1][2][3][4][5][6][7][8][9][10][11][12] and one review article [13] from seven different countries have been published. Researchers from academic institutions from France [1,[3][4][5][6][7]9], Germany [2,9,10,12,13], United States [8,11], Russia [4], Spain [9], Belgium [9] and Ethiopia [13] participated, sometimes in collaboration with industrial partners of energy or automotive sectors.…”