Characterizing aging effects of lithium ion batteries by impedance spectroscopy

In this paper we introduce a pseudo two-dimensional (P2D) model for a common lithium-nickel-cobalt-manganese-oxide versus graphite (NCM/graphite) cell with solid electrolyte interphase (SEI) growth as the dominating capacity fade mechanism on the anode and active material dissolution as the main aging mechanism on the cathode. The SEI implementation considers a growth due to non-ideal insulation properties during calendar as well as cyclic aging and a re-formation after cyclic cracking of the layer during graphite expansion. Additionally, our approach distinguishes between an electronic (σ SEI ) and an ionic (κ SEI ) conductivity of the SEI. This approach introduces the possibility to adapt the model to capacity as well as power fade. Simulation data show good agreement with an experimental aging study for NCM/graphite cells at different temperatures introduced in literature. © The Author Lithium-ion batteries are one of the most promising candidates for energy storage in future stationary storage systems and electric vehicles.1-3 Enormous research efforts have been conducted to get a thorough understanding of the system "lithium-ion cell" and to further develop it for higher energy and power density, higher safety standards as well as longer cycle life. 4 The aging behavior of lithium-ion batteries has been a focus issue of battery research since the introduction of lithium-ion cells by Sony in 1991. 5 Reviews by Agubra et al., 6,7 Arora et al., 8 Aurbach et al., 9,10 Birkl et al., 11 Broussely et al., 12 Verma et al. 13 and Vetter et al. 14 are just a few examples of the extensive literature regarding aging behavior. Commonly accepted and experimentally verified aging phenomena as mentioned in the previously cited literature are electrolyte decomposition leading to solid electrolyte interphase (SEI) and cathode electrolyte interphase (CEI) growth, solvent co-intercalation, gas evolution with subsequent cracking of particles, a decrease of accessible surface area and porosity due to SEI growth, contact loss of active material particles due to volume changes during cycling, binder decomposition, current collector corrosion, metallic lithium plating and transition-metal dissolution from the cathode. The listed aging mechanisms can be assigned to three different categories that are a loss of lithium-ions (LLI), an impedance increase and a loss of active material (LAM). 12,[15][16][17][18] The LLI is synonymous to a decrease in the amount of cyclable lithium-ions as they are trapped in a passivating film on either of the electrodes or in plated metallic lithium. Due to the growth of the passivating layers and/or the formation of rock-salt in the cathode (residue of the cathode active material after transition-metal dissolution), kinetic transport of lithium-ions through those inactive areas is limited and results in an impedance rise. An LAM can be caused by the dissolution of transition-metal-ions from the cathode bulk material, changes in the electrode composition and/or changes in crystal structure of the a...

mentioning

confidence: 99%

A SEI Modeling Approach Distinguishing between Capacity and Power Fade

Kindermann

Keil

Frank

et al. 2017

“…For this reason the impedance spectra can provide information that can be used to develop improved state of health (SOH) models and to describe how the battery voltage (or current) responds to changes in the current (or voltage). 2,3 It is usually very time consuming to measure impedance spectra on batteries because some of the investigated electrochemical processes occur very slowly. This is in particular true for single-sine methods where the impedance is measured at single frequency at a time.…”

mentioning

confidence: 99%

Measurements of Electric Performance and Impedance of a 75 Ah NMC Lithium Battery Module

Jensen

Engelbrecht

Bernuy-López

2012

Detailed characterization of battery modules is necessary to construct reliable models that incorporate performance related aspects of the modules such as thermodynamics, electrochemical reaction kinetics and degradation mechanisms. Charge-discharge curves, temperature and battery impedance measurements can provide information about these aspects. Charge-discharge curves can be used to measure the battery open circuit voltage and the internal resistance. Temperature measurements provide information about the thermodynamic reactions and impedance spectra yield detailed information about the reaction kinetics. In this paper we present the measurement methods used to examine the internal resistance, the capacity and the impedance of a 75 Ah NMC battery module. In order to measure the impedance of the battery module and of the individual cells in the module, we combine the single sine technique and the Laplace transformed excitation signal technique which each have pros and cons. By combining the two impedance measurement techniques we are able to reduce the measurement time by a factor of 20 relative to ordinary single-sine measurements. Further we use the impedance measurements to calculate the overvoltage as a function of state of charge and the difference between charging overvoltage and discharging overvoltage and compare it with measurements.

“…3,8,17,18,25,32 In this paper, the focus is on capacity fade since it is very important for the range of EVs, and could be important in the future for hybrids if the operating SOC window for these batteries widens. Since aging related mechanisms are shown to be coupled to mechanical effects, 33 studies, 11,16,28 perhaps due to the lower bulk stresses on the battery.…”

Section: Methodsmentioning

confidence: 99%

“…The power capability and capacity are both important factors used to determine the state of health (SOH). The SOH of a battery is usually quantified using either resistance growth 3,8,17,18,25,32 or capacity loss. 9,13,35,36 This paper focuses on the capacity fading dimension of SOH.…”

mentioning

confidence: 99%

Battery Capacity Fading Estimation Using a Force-Based Incremental Capacity Analysis

Samad

Kim

Siegel

et al. 2016

Traditionally health monitoring techniques in lithium-ion batteries rely on voltage and current measurements. A novel method of using a mechanical rather than electrical signal in the incremental capacity analysis (ICA) method is introduced in this paper. This method derives the incremental capacity curves based on measured force (ICF) instead of voltage (ICV). The force is measured on the surface of a cell under compression in a fixture that replicates a battery pack assembly and preloading. The analysis is performed on data collected from cycling encased prismatic Lithium-ion Nickel-Manganese-Cobalt Oxide (NMC) cells. For the NMC chemistry, the ICF method can complement or replace the ICV method for the following reasons. The identified ICV peaks are centered around 40% of state of charge (SOC) while the peaks of the ICF method are centered around 70% of SOC indicating that the ICF can be used more often because it is more likely that an electric vehicle (EV) or a plug-in hybrid electric vehicle (PHEV) will traverse the 70% SOC range than the 40% SOC. In addition the Signal to Noise ratio (SNR) of the force signal is four times larger than the voltage signal using laboratory grade sensors. The proposed ICF method is shown to achieve 0.42% accuracy in capacity estimation during a low C-rate constant current discharge. Future work will investigate the application of the capacity estimation technique under charging and operation under high C-rates by addressing the transient behavior of force so that an online methodology for capacity estimation is Lithium-ion (Li-ion) batteries have been one of the most popular choices for use as power sources in electric vehicles (EVs) and hybrid electric vehicles (HEVs). Their popularity stems from their high energy and power densities and their ability to achieve long driving ranges. However, their performance suffers from aging and degradation 1,29,33 that should be recognized and accounted for to achieve efficient long term performance. Thus significant research has been focused on trying to understand the aging mechanisms in Li-ion cells and connect them with measurable and identifiable features in an effort to improve the utilization and reliability of these cells through the battery management system (BMS). The power capability and capacity are both important factors used to determine the state of health (SOH). The SOH of a battery is usually quantified using either resistance growth 3,8,17,18,25,32 or capacity loss. 9,13,35,36 This paper focuses on the capacity fading dimension of SOH.Several methods haven been introduced in literature for the evaluation of the aging in battery. Traditional and conventional methods rely on voltage measurements. In Cyclic Voltammetry (CV), the electrode potential is ramped linearly versus time.12 And the resulting current is plotted vs voltage. Peaks in the CV indicate reactions and, a shift in their location is correlated with aging. The probability density function (PDF) method applies a histogram to the charge/discharge voltage data o...