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In support of GM's traction battery efforts, we derive and implement a method to describe the electrochemical performance of a battery cell through the combination of a modified Newman Pseudo 2-Dimensional model and a three-electrode experimental apparatus. To assess the capability of the method, we compare model results with experimental data for...
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... We model the thermodynamics of the intercalation electrode with the multi-site, multi-reaction (MSMR) model. [3][4][5][21][22][23][29][30][31][32]40,41 For the active material of each electrode, there are lithium mole fractions x j k with j N 1 ; ...
... Models are helpful in terms of calculating U n and assessing the potential for Li plating. An experimental procedure that has been used to assess the potential for Li plating is described schematically in Fig. 1 of Garrick et al. 41 and Fig. 7 of this work. The metallization of a thin (gold), porous current collector at y 1, ̅ = the addition of a thin separator, and the addition of a thin porous reference electrode enables the unobtrusive measurement of 1 2 Φ − Φ at y 1 ̅ = if the additional metallization layer, the thin separator, and the porous reference electrode are of insignificant resistance. ...
... Schematic illustration of reference electrode configuration used to determine if Li plating is occurring at the interface between the negative electrode and the separator.41 ...
Our focus is on large-format lithium-ion batteries, used in electric vehicles today and in the foreseeable future, which are charged at high rates. In order to fully charge the battery, we employ a protocol often referred to as cc-cv (constant current followed by constant voltage). We compare and contrast results for cocurrent and countercurrent tab locations. We show how the pseudo three-dimensional (P3D) model can be used to assess temperature and current distributions and determine if Li plating is expected. We demonstrate the advantages of countercurrent tab locations to (i) obtain more uniform current and temperature distributions and (ii) lower the propensity for Li plating. Sensitivity analyses include the influence of ambient temperature and cell length. The methodology laid out in this work can facilitate rational battery-cell design and robust operation, including high-rate charging.
... A three-electrode system is usually used in electrochemical analysis. The saturated calomel electrode (SCE) and general inert electrode are used as the reference and counter electrodes, respectively [16,17]. According to the principle of electrochemical detection, the absorption capability of the working electrode to target metal ions in a test solution greatly affects the performance of detection devices [18]. ...
Here, conductive carbon cloth (CC) and three-dimensional (3D) graphene hydrogel (GH) were combined to develop an electrochemical sensor for the detection of trace Cu²⁺. 3D GH/CC has low production cost and high sensitivity, accuracy, and stability, which are suitable for creation of small portable devices and large-scale commercial production. The limit of detection reached 1.87 nmol L⁻¹, and the linear ranges were from 0.1 µmol L⁻¹ to 10 µmol L⁻¹ and from 10 µmol L⁻¹ to 1000 µmol L⁻¹. Innovative interactive verification-based Cu²⁺ detection was carried out using two electrochemical detection methods, namely, anodic stripping voltammetry and electrochemical impedance spectroscopy, and with the mutual support of the two methods, the recovery rate of Cu²⁺ was estimated to 98%, which was improved considerably at medium and low concentrations in the actual water sample. The results showed that this preparation and detection method can be used as a new platform for the detection of trace Cu²⁺ and provide a new commercialized case for evaluating the composition and content of inorganic pollutants in water.
... The solid phase diffusion can also be linked to the MSMR model. 55 60 Garrick and colleagues 61 and Dix and colleagues. 62 It should be noted that the system described in this work is a single porous electrode model, while those referenced above are dual and three porous electrode models respectively. ...
... Equation 7 links the MSMR model parameters to the diffusion coefficient. Several researchers 59,85,86 have probed the impact of state-of-lithiation on the kinetics and diffusion of an active material, and previously, 61 one author utilized a method to explicitly fit the kinetics and diffusion of said active materials as a function of state-of-lithiation at incremental points. This approach allows one to populate a model utilizing a lookup function. ...
Graphite is a critical material used as the negative electrode in lithium-ion batteries. Both natural and synthetic graphites are utilized, with the latter obtained from a range of carbon raw materials. In this paper, efforts to synthesize graphite from coal as a domestic feedstock for synthetic graphite are reported. Domestic coal-derived graphite could address national security and energy issues by standing up domestic supply chains for battery critical materials. The performance in lithium-ion coin cells of this coal derived graphite is compared to a commercial battery-grade graphite. For the first time, a multi-species, multi-reaction modeling technique is applied to synthetic graphite derived from coal. Key thermodynamic, transport, and kinetic parameters are obtained for the coal derived graphite and compared to the same parameters for commercial battery-grade graphite. Modeling of synthetic graphites will allow for virtual evaluation of these materials toward production of domestically sourced graphite.
... However, this approach neglects the polarization of the electrolyte caused by high salt concentration gradients [66] during fast charging. According to the authors, this contribution plays a crucial role and should not be neglected, and instead an appropriate electrochemical model (e.g., Ref. [67]) should be used to calculate the anode surface potential if it is of interest. ...
Reliable experimental methods for measuring local potentials in lithium-ion battery cells are challenging but vital for a deep understanding of internal processes at the individual electrode level, and to parameterize and validate electrochemical models. Different three-electrode setups and reference electrodes (REs) have been developed in recent years. Some are based on custom laboratory setups or are small, e.g., coin cell sized. This work addresses internal potentials and half-cell impedances in the widely used single-layer pouch cell format and proposes a novel multi-reference electrode cell design, enabling spatially resolved measurements. For the first time, it is shown how multiple 25 and 50 μm thin gold wire REs, together with a larger LTO-RE, can be used to study occurring inhomogeneities, considering the geometrical anode overhang. Special attention is given to the subtleties of the measurements and their interpretation. Multiple REs allow plausibility checks and confirm stability for both types during a continuous measurement period of more than 7,500 h (>10 months), demonstrating suitability, e.g., for long-term cycling measurements. Results from electrochemical impedance spectroscopy and half-cell potential measurements at low currents of C/100 and during fast charging at up to 3C highlight the versatility of the easily reproducible cell design.
... The pulse characterization allows us to estimate electrochemical phenomena as needed and is in line with our previous work at the electrode level. 79 ...
Automotive manufacturers are working to improve cell and pack design by increasing their performance, durability, and range. One of the critical factors to consider as the industry moves towards materials with higher energy density is the ability to consider the irreversible volume change characteristic of the accelerated SEI layer growth tied to the large volume change and particle cracking typically associated with active material strain. As the time from initial design to manufacture of electric vehicle is decreased in order to rapidly respond to consumer demands and widespread adoption of electric vehicles, the ability to link aging and volume change to end of life vehicle requirements using virtual tools is critical. In this study, apply a mechano-electrochemical model to determine the irreversible volume change at the electrode and cell level, allowing for virtual design iterations to predict the volume change at battery cell aged states.
... The fundamental governing equations and construction of the electrochemical model used in this study have been described in previous work 4,15 . In the continuum model approach, mass transport and the potential in the cathode particles and anode particles are described by Fickian diffusion and Ohm's law, respectively. ...
Lithium-ion battery cell modeling using physics-based approaches such as porous electrode theory is a powerful tool for battery design and analysis. Cell metrics such as resistance and thermal performance can be quickly calculated in a pseudo-two-dimensional (P2D) framework. For engineering of electric vehicle batteries, speed and fidelity of electrochemical models is paramount in a competitive landscape. Physics-based models allow for high fidelity but require detailed knowledge of the cell component material properties. Acquiring these material characteristics typically requires time-consuming and expensive experiments limiting the ability to quickly screen through cell designs. One approach to circumvent costly experiments is to use molecular dynamics to calculate electrolyte transport properties. We demonstrate how cell modeling using simulated transport properties enables predictions of cell level metrics, allowing for experiment-free component screening. We also show how the variation in transport property predictions from molecular dynamics affects the final cell level performance predictions.
... The fundamental governing equations and construction of the electrochemical model used in this study has been described in previous work [74,75] . In the continuum model approach, mass transport and the potential in the cathode particles and anode particles are described by Fickian diffusion and Ohm's law, respectively. ...
In support of GM’s traction battery efforts, we derived and implemented a method to describe the electrochemical performance of a battery cell considering the nuances of the electrode microstructure at the anode and the cathode and the corresponding impact on the electrochemical transport in the solid and liquid phases. To assess the capability of the method, we compared model results from the microstructure framework with the commonly used continuum-level porous electrode model, commonly referred to as the pseudo-2-dimensional model, or the Newman model. The microstructure modeling framework was applied to simulate the electrochemical and transport processes within the battery cell to predict the concentration gradients, local state-of-charge distributions, reaction distributions, and the overall terminal voltage of the system. In this report, we provide a commentary on the validity and practicality of the microstructure approach to drive battery cell design.
The lithium-ion concentration of a solid phase is essential to solve the electrochemical model of a lithium-ion battery. Based on the analytic solution of a convolution infinite series, a new algorithm is proposed to efficiently and accurately solve the partial differential equation for the lithium-ion diffusion behavior of electrode particles. Under galvanostatic profiles, the analytic solution is an infinite time series transformed into a converged sum function by using the monotone convergence theorem. Under dynamic profiles, the infinite series solution is simplified to a finite discrete convolution of both the input and the sum function. Meanwhile, the discrete step is determined by the amplitude-frequency characteristic curve, and the sum function is truncated by its characteristic monotonic decay approaching zero over time. Compared with using a professional finite element analysis software, it takes less time to use this discrete convolution algorithm, and it yields less error. And, it has the least solution time with medium accuracy in comparison with two commonly used approximations. Not only that, the proposed algorithm has only two parameters to be determined with little computation, thus promoting the electrochemical models built in battery management systems.
