Evaluating the Degradation Mechanism and State of Health of LiFePO4 Lithium-Ion Batteries in Real-World Plug-in Hybrid Electric Vehicles Application for Different Ageing Paths

Zhang, Chi; Yan, Fuwu; Du, Changqing; Kang, Jianqiang; Turkson, Richard Fiifi

doi:10.3390/en10010110

Cited by 20 publications

(13 citation statements)

References 38 publications

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“…If a DoD of 100% at each cycle implies a division by two of the lifespan, that corresponds to ρ = -1. Typically, ρ is close to -0.25 [36,37].…”

Section: B Aging Integrationmentioning

confidence: 99%

Insert Switches Inside to Increase Battery Lifespan

Savard¹,

Venet²,

Niel³

et al. 2020

EJERS

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This paper shows the possible gain on time before the end of useful time brought by switches addition in a multicell battery. In a first time, it presents a battery electric model. A battery includes many identical electrical energy cells that electrically interact. From a behavioral standpoint, cell performance is measured by fundamental parameters: State of Charge (SoC) and State of Health (SoH). To simulate cell electrical behavior, the Thevenin model or the Nernst model are often used. However, these models do not take into account the cells aging or the possible interactions on aging. A cell ages mainly in two ways: cyclic and calendar. This aging impacts both the elements of the equivalent electrical model and the fundamental parameters (SoC and SoH). Thus, the conventional electric model of a cell does not accurately reflect the cell aging. In this paper, another formal model based on the fundamental curve that relates electrical and behavioral parameters is proposed. It integrates aging into the equivalent electric model estimation. In a second time, in order to validate this model, this cell model is used to simulate parallel-series association. To improve battery lifespan, in addition to the usual balancing techniques, it may be relevant to require some traditional reliability and operating safety solutions. This requires to add switches inside battery. The presented simulation shows adding switches solution is currently not deployed. This is justified in this paper by examining the impact provide on lifespan improvement on an example, which is pretty weak. But it also shows that however, by managing active cells in a different way, adding switches and spare cells can really reach this improvement.

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“…If a DoD of 100% at each cycle implies a division by two of the lifespan, that corresponds to ρ = -1. Typically, ρ is close to -0.25 [36,37].…”

Section: B Aging Integrationmentioning

confidence: 99%

Insert Switches Inside to Increase Battery Lifespan

Savard¹,

Venet²,

Niel³

et al. 2020

EJERS

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show abstract

“…Incremental capacity analysis (ICA) is a method that is being pervasively used in battery SOH diagnosis in recent years, after its first proposal by Balewski & Brenet [18] and propagated by Dubarry et al [19,20]. The ICA technique is performed by differentiating the capacity Q with respect to the voltage V, therefore the voltage plateaus that reflects the thermodynamics of battery will be transformed into dQ/dV peaks, which are convenient for degradation analysis [21,22]. dQ/dV is also called the incremental capacity (IC).…”

Section: Introductionmentioning

confidence: 99%

Incremental Capacity Analysis on Commercial Lithium-Ion Batteries using Support Vector Regression: A Parametric Study

Feng

Weng

et al. 2018

Energies

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Incremental capacity analysis (ICA) has been used pervasively to characterize the degradation mechanisms of the lithium-ion batteries, and several online state-of-health estimation algorithms are built based on ICA. However, the stairs and the noises in the discrete sampled voltage data obstruct the calculation of the capacity differentiation over voltage (dQ/dV), therefore we need methods to fit the sampled voltage first. In this paper, the support vector regression (SVR) algorithm is used to smooth the sampled voltage curve using Gaussian kernels. A parametric study has been conducted to show how to enhance the performances of the SVR algorithm, including (1) speeding up the algorithm by downsampling; (2) avoiding overfitting and under-fitting using proper standard deviation σ in the Gaussian kernel; (3) making precise capture of the characteristic peaks. A novel method using linear approximation has been proposed to help judge the accuracy of the SVR algorithm in tracking the ICA peaks. And advanced SVR algorithms using double σ and using cost function that directly regulates the differentiation result have been proposed. The advanced SVR algorithm can make accurate curve fitting for ICA with overall error less than 1% (maximum 3%) throughout cycle lives, for four kinds of commercial lithium-ion batteries with LiFePO4 and LiNixCoyMnzO2 cathodes, making it promising to be further applied in online SOH estimation algorithms.

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“…To achieve this, Trip 2 and the Night Park were simulated for all possible values of as initial state. The cost terms were then evaluated and mapped onto ( ) to evaluate (14). As an example, Figure 9 shows the resulting maps for a cabin temperature of 60 °C at the end of Day Park.…”

Section: Optimal Control Of Key-off Cooling In View Of the Daily Dutymentioning

confidence: 99%

“…Lithium-ion cells, which are believed to be the most promising choice for automotive applications [11,12] have ageing mechanisms that are sensitive to real world usage conditions [13]. Cycling ageing (ageing due to the conditions of charge-discharge cycles) accelerates at high temperature, as well as with a high degree of discharge, and high charge-discharge rates [14,15]. The vehicle was assumed to operate in Phoenix, AZ, USA, which has hot climate conditions.…”

Section: Introductionmentioning

confidence: 99%

Improving the Performance Attributes of Plug-in Hybrid Electric Vehicles in Hot Climates through Key-Off Battery Cooling

et al. 2017

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Ambient conditions can have a significant impact on the average and maximum temperature of the battery of electric and plug-in hybrid electric vehicles. Given the sensitivity of the ageing mechanisms of typical battery cells to temperature, a significant variability in battery lifetime has been reported with geographical location. In addition, high battery temperature and the associated cooling requirements can cause poor passenger thermal comfort, while extreme battery temperatures can negatively impact the power output of the battery, limiting the available electric traction torque. Avoiding such issues requires enabling battery cooling even when the vehicle is parked and not plugged in (key-off), but the associated extra energy requirements make applying key-off cooling a non-trivial decision. In this paper, a representative plug-in parallel hybrid electric vehicle model is used to simulate a typical 24-h duty cycle to quantify the impact of hot ambient conditions on three performance attributes of the vehicle: the battery lifetime, passenger thermal comfort and fuel economy. Key-off cooling is defined as an optimal control problem in view of the duty cycle of the vehicle. The problem is then solved using the dynamic programming method. Controlling key-off cooling through this method leads to significant improvements in the battery lifetime, while benefiting the fuel economy and thermal comfort attributes. To further improve the battery lifetime, partial charging of the battery is considered. An algorithm is developed that determines the optimum combination of key-off cooling and the level of battery charge. Simulation results confirm the benefits of the proposed method.

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Evaluating the Degradation Mechanism and State of Health of LiFePO4 Lithium-Ion Batteries in Real-World Plug-in Hybrid Electric Vehicles Application for Different Ageing Paths

Cited by 20 publications

References 38 publications

Insert Switches Inside to Increase Battery Lifespan

Insert Switches Inside to Increase Battery Lifespan

Incremental Capacity Analysis on Commercial Lithium-Ion Batteries using Support Vector Regression: A Parametric Study

Improving the Performance Attributes of Plug-in Hybrid Electric Vehicles in Hot Climates through Key-Off Battery Cooling

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