Empirical Electrical and Degradation Model for Electric Vehicle Batteries

Abstract

Battery degradation is one of the key barriers to the correct deployment of electric vehicle technology. Therefore, it is necessary to model, with sufficient precision, the State of Health (SoH) of batteries at every moment to know if they are useful as well as to develop operating strategies aimed at lifetime maximization. This paper presents a commercial electric vehicle with a nickel-cobalt-manganese (NCM) battery cell model that is composed of electrical and degradation submodels given by cycling aging. The studied cell is an LG Chem E63 cell, which is used in Renault Zoe electric vehicles. This degradation model is based on experimental results that are interpolated in the Hermite Cubic Interpolation Polynomial (PCHIP), with the exception of the number of cycles, whose impact is determined by a potential law. Temperature and Crate are found to be the most influential factors in the aging of these batteries. The degradation model developed presents an RMSE of 1.12% in capacity fade and 2.63% in power fade. Furthermore, an application of the model is presented, in which high demanding (highway), average demanding (mixed), and low demanding (urban) driving environments are analyzed in terms of degradation.

Cycle-Life Curves Determination and Modelling of Commercially Available Electric Vehicle Batteries

“…Based on the results of some experimental tests, the degradation model considered battery degradation by cycling in capacity fade terms [15]. Later, this degradation model was used to characterise the EoL of these cells, which is the aim of this paper.…”

Optimisation model with degradation for a battery energy storage system at an EV fast charging station

“…The degradation model distinguishes between calendar aging, which is due to a non-avoidable capacity decrease with time, and cyclic aging, which is degradation from the BESS's operation, charging, and discharging [11]. The level and pace of BESS degradation depend on temperature, time t, C-rate C r , and full equivalent cycles (F EC) [12].…”

Mining Electric Vehicle Adoption of Users

“…Saldaña [37], similar to Vidal [42], also alluded to the essential nature of knowing the rate of battery degradation. Furthermore, he stated that battery endurance depends not only on electrochemical factors such as the temperature to which the batteries are subjected, on operational aspects such as the degree to which EV users allow their packs to discharge, but also on the total number of charging/discharging cycles that are completed throughout the useful life of the car.…”

“…Based on our literature review, a gap in state of the art was identified: few articles [6,37,66,67] referred to the degradation of batteries from the point of view of electric vehicles user behavior. In most cases, articles only mentioned the point of view of Electrochemistry.…”