Electrochemical modelling of Li-ion battery pack with constant voltage cycling

Ashwin, T.R.; McGordon, Andrew; Jennings, Paul

doi:10.1016/j.jpowsour.2016.11.092

Cited by 50 publications

(18 citation statements)

References 26 publications

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“…At the pack level, variations in cell performance or interconnect resistances can lead to heterogeneous current distributions in parallel strings [13][14][15][16][17] and subsequent acceleration of the degradation compared to the equivalent single cell performance [18][19][20][21]. The root cause of this heterogeneous current distribution and hence accelerated degradation can be attributed to effects such as uneven thermal conditions, columbic efficiency variations and self-discharge rates, amongst others [21][22][23][24].…”

Section: Introductionmentioning

confidence: 99%

The effect of cell-to-cell variations and thermal gradients on the performance and degradation of lithium-ion battery packs

et al. 2019

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The performance of lithium-ion battery packs are often extrapolated from single cell performance however uneven currents in parallel strings due to cell-to-cell variations, thermal gradients and/or cell interconnects can reduce the overall performance of a large scale lithium-ion battery pack. In this work, we investigate the performance implications caused by these factors by simulating six parallel connected batteries based on a thermally coupled single particle model with the solid electrolyte interphase growth degradation mechanism modelled. Experimentally validated simulations show that cells closest to the load points of a pack experience higher currents than cells further away due to uneven overpotentials caused by the interconnects. When a cell with a four times greater internal impedance was placed in the location with the higher currents this actually helped to equalise the cell-to-cell current distribution, however if this was placed at a location furthest from the load point this would cause a ~6% reduction in accessible energy at 1.5 C. The influence of thermal gradients can further affect this current heterogeneity leading to accelerated aging. Simulations show that in all cases, cells degrade at different rates in a pack due to the uneven currents, with this being amplified by thermal gradients. In the presented work a 5.2% increase in degradation rate, from-7.71 mWh/cycle (isothermal) to-8.11 mWh/cycle (non-isothermal) can be observed. Therefore, the insights from this paper highlight the highly coupled nature of battery pack performance and can inform designs for higher performance and longer lasting battery packs.

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Section: Introductionmentioning

confidence: 99%

The effect of cell-to-cell variations and thermal gradients on the performance and degradation of lithium-ion battery packs

et al. 2019

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“…The constant current constant voltage (CC/CV) charging algorithm is widely adopted in charging Li-ion batteries because of its simplicity and easy implementation [37]- [39]. Under the CC/CV algorithm, the battery is initially charged with constant current until the battery voltage reaches a preset maximum charging voltage, then the charging voltage is held constant until the current is reduced to a preset minimum value [40].…”

Section: A Constant-current Constant Voltage Related Charging Methodsmentioning

confidence: 99%

“…These electrochemical-based models have significant advantages over those equivalent circuit models because of their physical based equations [51], [59], [60]. The Partial-Two-Dimensional (P2D) model is unquestionably rigorous and accurate [37], [61]. The Single-Particle-Model (SPM) is useful in realizing quick responses but it is unsuitable for simulating high (dis)charge rates [20], [62], [63].…”

Section: A Commonly-used Battery Modelmentioning

confidence: 99%

Classification and Review of the Charging Strategies for Commercial Lithium-Ion Batteries

et al. 2019

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The growing demand for lithium-ion (Li-ion) battery in electric vehicles has expedited the need for new optimal charging approaches to improve the speed and reliability of the charging process without deteriorating battery performances. Many efforts have been deployed to develop optimal charging strategies for commercial Li-ion batteries over the last decade. The active optimal charging strategies have great potential to meet the requirement. This paper is a review of the studies on constructing the optimal charging algorithms for Li-ion batteries. The battery models on which these protocols rest are stated, the generalized structures are examined, the advantages and the drawbacks of the mathematical controller algorithms are discussed, and their applications are presented. Suggestions for overcoming the shortcomings of the proposed strategies are proposed. Challenges and future directions in the development of optimal charging strategies for commercial Li-ion batteries are also discussed.INDEX TERMS Fast charging, optimal charging strategies, lithium-ion battery.

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“…In spite of the wide usage of the CC‐CV charging protocol, no reduced‐order physics‐based model is available for predicting the SoC during CC‐CV charging conditions. Most of the existing physics‐based modeling efforts to simulate the CV charging mode rely on the P2D model, 12,13 which is a detailed model and hence computationally expensive compared to the reduced‐order model presented in this study. Other less computationally expensive efforts include a few modeling efforts that rely on monitoring input current such that CV mode is approximately replicated 14 …”

Section: Introductionmentioning

confidence: 99%

A reduced‐order electrochemical model for coupled prediction of state of charge and state of health of lithium ion batteries under constant current‐constant voltage charging conditions

Dingari¹,

Mynam²,

Rai³

2020

Energy Storage

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Accurate and fast prediction of the remaining useful life of lithium (Li) ion batteries is an important requirement for successful electrification of automobiles. Consequently, there is a growing interest in the development of reduced-order models. The existing reduced-order electrochemical models can be used to predict battery performance (state of charge [SoC], terminal voltage) when the current through the battery is known a priori. Therefore these models cannot be used for studying the constant voltage (CV) mode of the constant current-CV (CC-CV) charging protocol, which is a common battery charging mechanism. In this work, we propose a reduced-order electrochemical model to estimate the battery SoC under CC-CV charging conditions, along with an analytical expression to approximate the CV mode charging time. We further propose a framework that accounts for the influence of the battery state of health (SoH) on the battery SoC during an operating cycle and vice-versa. The proposed framework for estimating the battery SoC and SoH in a coupled manner shows good comparison with a first principles electrochemical model for CC-CV charging conditions. This model can be used to study battery ageing and it can find applications in real-time state estimation, charge protocol optimization, and battery design. K E Y W O R D S lithium ion battery, remaining useful life, state of charge, state of health

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Electrochemical modelling of Li-ion battery pack with constant voltage cycling

Cited by 50 publications

References 26 publications

The effect of cell-to-cell variations and thermal gradients on the performance and degradation of lithium-ion battery packs

The effect of cell-to-cell variations and thermal gradients on the performance and degradation of lithium-ion battery packs

Classification and Review of the Charging Strategies for Commercial Lithium-Ion Batteries

A reduced‐order electrochemical model for coupled prediction of state of charge and state of health of lithium ion batteries under constant current‐constant voltage charging conditions

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