Deposition Of Metallic Lithium Research Articles

A metallic lithium anode for solid-state batteries with low volume change by utilizing a modified porous carbon host

Lithium metal is a promising negative electrode material for solid-state batteries (SSBs). However, uncontrolled lithium deposition and stripping cause several issues during cycling. Herein, the microporous carbon YP-50F and its modifications obtained by thermal ethene-based chemical vapor deposition (CVD) are investigated as 3D host to accommodate and control the deposition of metallic lithium. In half-cells vs. lithium, the CVD-YP composite electrode with Li6PS5Cl electrolyte shows significantly higher initial coulombic efficiency (79.5 %) than the pristine carbon (55.3 %) due to the reduction of side reactions. The metallic character of the deposited lithium is evidenced by 7Li Nuclear Magnetic Resonance spectroscopy. However, full cells with nickel-rich NCM (LiNi0.9Co0.05Mn0.05O2) positive electrode and CVD-YP composite negative electrode show reasonable performance over 50 cycles without occurrence of (micro-) short-circuits (in contrast to 2D reference electrodes). In addition, small prototype pouch cells are investigated and the thickness change during (dis)charging is less than one third compared to a bare lithium metal electrode. This demonstrates low breathing behavior of the CVD-YP electrode and confirms the reversible storage of metallic lithium within the 3D carbon-based composite electrode.

Prediction of Lithium Deposition By Electrochemical Noise Method in Li-Ion Batteries

Electrochemical noise measurement methods have established a significant presence in corrosion literatures and through these measurements, it becomes feasible to discern the corrosion mode and make a clear distinction between localized and uniform corrosion types, particularly when examined alongside post-mortem studies.In recent years, the increase in the use of lithium-ion batteries demands that the tests to be performed on the batteries are faster, easier, cheaper and, if possible, non-destructive and non-perturbing. While some electrochemical noise studies on batteries have commenced, the existing literature on this subject is limited and questionable. Electrochemical noise measurement, in Lithium based batteries has the potential to serve as a non-invasive diagnostic tool for assessing battery health. One of our previous studies has demonstrated an increased voltage noise in non-rechargeable batteries with Li/MnO2 chemistry upon exposure to a short circuit, indicating detectable morphological changes in metallic lithium due to non-homogenous depletion of lithium anode through electrochemical noise measurement.In Lithium-Ion batteries, lithium deposition refers to the undesired formation of metallic lithium, commonly in the form of dendrites, on the battery’s anode during charge and discharge cycles. This phenomenon is a consequence of uneven lithium-ion plating and stripping, leading to localized overplating. This growth of lithium dendrites poses significant risk, including internal short circuits, compromised battery integrity, and the potential for thermal runaway. These issues can result in reduced battery performance, safety concerns, and shortened cycle life. Effectively addressing lithium deposition is essential for enhancing the safety and reliability of lithium-ion batteries in various applications.Similarly to our previous publication, the electrochemical noise method shows promise as a non-invasive approach to investigate the understand deposition of metallic lithium by monitoring the voltage noise during charge and discharge cycling of batteries. For this purpose, NMC/Graphite pouch and coin cells are employed. In this presentation, we will delve into the details of electrochemical noise in lithium-based batteries, discussing the method’s reliability in assessing lithium deposition in NMC/Graphite lithium-ion batteries and presenting preliminary results. Figure 1

Influence of Particle Size and Morphology on Electrochemical Properties of Glass Particle-Based Separators for Lithium-Ion Batteries

Lithium-ion batteries (LIBs) are one of the most important and common energy storage technologies for mobile devices as well as electric vehicles due to their high specific energy density [1]. However, there are still safety concerns in case of overcharge or mechanical damage. The separator as the passive safety-relevant component is placed between the two electrodes to prevent internal short-circuits. Nevertheless, accidental or inhomogeneous deposition of metallic lithium (Li plating) can lead to dendrite growth, which is one of the most common failure mechanisms. If only one dendrite penetrates the separator and forms a conductive path between the two electrodes, a short circuit in the battery leads to its failure [2].Despite the inherent rigidity of glass materials, previous studies demonstrated the successful application of glass-based separators in LIBs [3, 4]. To meet the requirements of modern battery production, a colloidal water-based system of glass particles and binder is used to manufacture flexible separators. Compared to state-of-the-art polymer-based separators, those flexible glass particle-based separators are superior in many of the required properties such as higher temperature resistance and dimensional stability up to 600 °C [3].However, the size and morphology of the utilized particles have a significant impact on the manufacturing process, e.g. affect slurry processability and separator formation, and consequently on the electrochemical performance. The effects of these parameters have already been studied for spherical or arbitrarily-shaped particles [5, 6].In the present work, platelet-shaped particles are utilized to manufacture glass-based separators. To further improve the operational safety of lithium-ion batteries, the benefit of platelet-shaped particles is compared to the use of arbitrarily-shaped particles. The use of these so-called glass flakes serves the purpose of forming an effective barrier against growing lithium dendrites by establishing a self-stabilizing structure. This barrier prevents or at least effectively delays penetration of the separator.For platelet-shaped particles, thickness and edge length of a particle differ significantly. Particles with a too high aspect ratio (edge length to thickness) block the Li+ diffusion pathway, affecting performance and stability of the final cell. Preliminary tests have shown that increasing the thickness of the glass flakes leads to a slight improvement of ionic conductivity, while increasing the edge length results in a strong reduction of ionic conductivity. However, separators containing particles with higher aspect ratio are expected to show increased piercing resistance. Thus, a trade-off between processability, electrochemical performance and safety barrier function against Li-dendrite growth and penetration is evaluated to understand the influence of particle morphology on the properties of separators using these particles.The microstructure of separators containing the different particle morphologies is examined using scanning electron microscopy (SEM) and correlated with the results of further characterization methods such as electrochemical impedance spectroscopy (EIS) and galvanostatic cycling.

Two Birds with One Stone: Micro/Nanostructured SiOx Cy Composites for Stable Li-Ion and Li Metal Anodes.

Developing stable silicon-based and lithium metal anodes still faces many challenges. Designing new highly practical silicon-based anodes with low-volume expansion and high electrical conductivity, and inhibiting lithium dendrite growth are avenues for developing silicon-based and lithium metal anodes, respectively. In this study, SiOx Cy microtubes are synthesized using a chemical vapor deposition method. As Li-ion battery anodes, the as-prepared SiOx Cy not only combines the advantages of nanomaterials and the practical properties of micromaterials, but also exhibits high initial Coulombic efficiency (80.3%), low volume fluctuations (20.4%), and high cyclability (98% capacity retention after 1000 cycles). Furthermore, SiOx Cy , as a lithium deposition substrate, can effectively promote the uniform deposition of metallic lithium. As a result, low nucleation overpotential (only 6.0mV) and high Coulombic efficiency (≈98.9% after 650 cycles, 1.0mA cm-2 and 1.0 mAh cm-2 ) are obtained on half cells, as well as small voltage hysteresis (only 9.5mV, at 1.0mA cm-2 ) on symmetric cells based on SiOx Cy . Full batteries based on both SiOx Cy and SiOx Cy @Li anodes demonstrate great practicality. This work provides a new perspective for the simultaneous development of practical SiOx Cy and dendrite-free lithium metal anodes.

Operando nuclear magnetic resonance spectroscopy: Detection of the onset of metallic lithium deposition on graphite at low temperature and fast charge in a full Li-ion battery

Lithium-ion batteries are at the core of the democratisation of electric transportation and portative electronic devices. However, fast and/or low temperature charge induce performance loss, mainly through lithium plating, a degrading mechanism. In this report, 7Li operando Nuclear Magnetic Resonance spectroscopy is used to detect the onset of metastable lithium deposits in an NMC622/graphite cell at 0 °C and fast charge. An operando setup, compatible with low temperatures, was developed with special attention to the pressure applied on the electrodes/separator stack and noise reduction to enable early detection and good time-resolution. Direct detection of metallic lithium enables drawing correlations between lithium plating and electrochemical data.

Ameliorating Phosphonic-Based Nonflammable Electrolytes Towards Safe and Stable Lithium Metal Batteries.

High-energy-density lithium metal batteries with high safety and stability are urgently needed. Designing the novel nonflammable electrolytes possessing superior interface compatibility and stability is critical to achieve the stable cycling of battery. Herein, the functional additive dimethyl allyl-phosphate and fluoroethylene carbonate were introduced to triethyl phosphate electrolytes to stabilize the deposition of metallic lithium and accommodate the electrode-electrolyte interface. In comparison with traditional carbonate electrolyte, the designed electrolyte shows high thermostability and inflaming retarding characteristics. Meanwhile, the Li||Li symmetrical batteries with designed phosphonic-based electrolytes exhibit a superior cycling stability of 700 h at the condition of 0.2 mA cm-2, 0.2 mAh cm-2. Additionally, the smooth- and dense-deposited morphology was observed on an cycled Li anode surface, demonstrating that the designed electrolytes show better interface compatibility with metallic lithium anodes. The Li||LiNi0.8Co0.1Mn0.1O2 and Li||LiNi0.6Co0.2Mn0.2O2 batteries paired with phosphonic-based electrolytes show better cycling stability after 200 and 450 cycles at the rate of 0.2 C, respectively. Our work provides a new way to ameliorate nonflammable electrolytes in advanced energy storage systems.

A direct method to quantify lithium plating on graphite negative electrode of commercial Li-ion cells

The deposition of metallic lithium is a degradation mechanism, also known as lithium plating, that might occur at the negative electrode surface of Li-ion battery cell, especially during fast charging, low temperature charging and high state of charge. The loss of cyclable lithium may lead to irreversible capacity fade and might also bring significant safety hazards. In this context, the experimental quantification of plated lithium on the negative electrode surface could be used to accurately validate electrochemical and physical models that might be used to predict plated lithium without cell opening. Also, the determination of plated Li may help in the evaluation of the safety and aging of commercial cells from different manufacturers for a specific application. This work shows a fast and cost-effective method that can be used to quantify plated lithium on commercial Li-ion battery graphite electrodes.

Comprehensive analysis of lithium-ion cells and their aging trajectory toward nonlinear aging

More than 30 years after the market introduction of lithium-ion batteries, research still struggles to understand the complex interplay of different aging mechanisms that can lead to a sudden drop in usable capacity. Understanding this nonlinear aging behavior is important to develop optimal strategies regarding the cell design and operation. In this work, we present an extensive analysis of a cycle aging test comprising 62 commercial large-scale pouch-bag type cells in a constant force bracing. The dataset includes eight cells, which exhibit nonlinear aging. Nondestructive methods, such as differential voltage analysis, reveal that the capacity loss is limited by the loss of lithium inventory, which is not homogeneous within the cell . With destructive post-mortem analysis we observe that aging is focused toward the center of the anode. Occurring lithium-plating seems to intensify with aging at high temperatures. Our results point toward a two-step mechanism, where elevated temperatures drive SEI-growth at the electrodes’ center, which, in turn, impair mass transfer kinetics and lead to the deposition of metallic lithium. Ultimately, our work can help to identify the most relevant mechanisms and interactions that provoke nonlinear aging.

Charging Optimization of Lithium-Ion Batteries Based on Charge Transfer Limitation and Mass Transport Limitation

Fast charging of lithium-ion batteries is essential to alleviate range anxiety and accelerate the commercialization of electric vehicles. However, high charging currents seriously deteriorate battery life due to the danger of metallic lithium deposition on the anode and the accompanying degradation reactions. In this work, a reduced-order electrochemical-thermal coupled model with typical side reactions is applied to capture the dependent variables related to the behavior of lithium plating. To completely suppress lithium plating, two novel charging algorithms are designed based on the constraints of the minimum lithium plating overpotential in the anode and the maximum surface concentration at the anode/separator interface, respectively. The definitions of the sensitive parameters in the two algorithms are weighed, and the current rates of 0 to 100% state of charge at different temperatures are optimized. Then, the fast charging strategies under the specific temperatures are optimized according to the sequence of preventing the minimum lithium plating overpotential, saturated surface concentration and cut-off voltage from exceeding the preset values. Finally, the proposed charging strategies and the conventional charging protocols are performed in cyclic aging tests at different temperatures, which verified that the proposed charging strategies can significantly shorten the charging time and delay battery aging.

A flexible solid-state lithium battery with silver nanowire/lithium composite anode and V2O5 nanowires based cathode

Lithium-ion batteries have been widely used in portable electronic devices, electric vehicles and other fields in daily life, which has stimulated the exploration of new electrode materials with high energy density and long cycle life. So far, V2O5 have attracted much attention due to its high capacity and excellent layered structure, but its cycle stability is still a problem which was caused by poor structural stability and relatively low electronic conductivity. Here, a flexible solid-state lithium battery is fabricated with V2O5 nanowire-carbon nanotubes (CNT) composite paper as cathode, silver nanowire/lithium composite as anode. The discharge capacity of the full cell reaches 222.2 mAh g−1 at 0.1 C. It can be stably cycled for more than 500 cycles at 0.5 C and exhibits an average discharge capacity of 120.9 mAh g−1. By analysis of the lithium metal surface of the symmetric cell after cycling using SEM, it demonstrates that the silver nanowire/lithium composite anode can induce uniform deposition of metallic lithium into the main frame while inhibiting the growth of Li dendrites. This work provides a guide for designing flexible solid-state lithium batteries.

Insights into the Lithium Nucleation and Plating/Stripping Behavior from Ionic Liquid-Based Battery Electrolytes

Lithium-metal batteries are anticipated to become the next-generation battery technology, allowing for substantially higher energy densities. To maximize the energy density, however, a “zero excess” of lithium in the cell is a must, e.g., by initially storing all electrochemically active lithium in the positive electrode.1 Nevertheless, this requires the fully reversible deposition of metallic lithium, i.e., a Coulombic efficiency of essentially 100%.2 Herein, the investigation of the lithium nucleation and plating/stripping from ionic liquid-based electrolytes composed of N-butyl-N-methyl pyrrolidinium bis(fluorosulfonyl)imide (PYR14FSI) and lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) on nickel current collectors is reported, involving a comprehensive set of electrochemical techniques coupled with operando and in situ atomic force microscopy and ex situ X-ray photoelectron spectroscopy. It was found that the morphology of the deposited lithium, the chemical composition of the interphase formed on the nickel current collector, and the reversibility of the lithium plating and stripping is highly dependent on the ratio of the ionic liquid and the lithium salt. Moreover, the addition of suitable film-forming additives allows for lower overpotentials and greater reversibility by tuning the interphase composition. The results are anticipated to contribute to the development of advanced electrolyte systems for “zero excess” lithium-metal batteries.(1) Nanda, S., Gupta, A., and Manthiram, A. Anode-Free Full Cells: A Pathway to High-Energy Density Lithium-Metal Batteries. Adv. Energy Mater. 2021, 11, 2000804. DOI: 10.1002/aenm.202000804(2) Hobold, G.M., Lopez, J., Guo, R. et al. Moving beyond 99.9% Coulombic efficiency for lithium anodes in liquid electrolytes. Nat. Energy 2021, 6, 951–960. DOI: 10.1038/s41560-021-00910-w

Electrochemical-driven green recovery of lithium, graphite and cathode from lithium-ion batteries using water

The expected exponential increase in consumption of lithium-ion batteries (LIBs) would pose a unique challenge to the availability of near-critical resources like lithium and graphite in the upcoming decade. We present a lithium recovery process that utilizes a degradation mechanism, i.e., lithium plating, as a tool to concentrate metallic lithium at the anode/separator interface for convenient extraction at room temperature – using only water. Electrochemical characterization of fast charged (1–6 C) LIBs yielded a maximum capacity fade of 50% over ten cycles. The lithium plating was confirmed via voltage plateau analysis, coulombic efficiency, and DC resistance measurements. A maximum lithium plating condition was observed to exist between 4C and 5C, thereby limiting the energy consumption in the extraction process. Post-mortem film thickness measurement showed an incrementing film deposition with a maximum of 35 µm thickness. SEM and XPS analysis confirmed increasing concentration of a dense dendritic metallic lithium deposition on the anode/separator interface with C-rate. A green recovery process was adopted to extract the concentrated metallic lithium using distilled water. The lithium from the plated film, solid/electrolyte interface (SEI), electrolyte, anode, and cathode, was extracted as salts. A 37% improvement in lithium recoverability was achieved with fast charging under ambient conditions. XPS analysis showed ∼92% of lithium yield with no residual lithium in the graphite. In addition, the battery-grade graphite was recovered with 97% purity after heat treatment of the washed anode film, and concentrated transition metals oxides in the cathode to 93% purity for convenient extraction.

Coupling Lithium Plating with SEI Formation in a Pseudo-3D Model: A Comprehensive Approach to Describe Aging in Lithium-Ion Cells

The lifetime of a battery is affected by various aging processes happening at the electrode scale and causing capacity and power fade over time. Two of the most critical mechanisms are the deposition of metallic lithium (plating) and the loss of lithium inventory to the solid electrolyte interphase (SEI). These side reactions compete with reversible lithium intercalation at the graphite anode. Here we present a comprehensive physicochemical pseudo-3D aging model for a lithium-ion battery cell, which includes electrochemical reactions for SEI formation on graphite anode, lithium plating, and SEI formation on plated lithium. The thermodynamics of the aging reactions are modeled depending on temperature and ion concentration, and the reactions kinetics are described with an Arrhenius-type rate law. The model includes also the positive feedback of plating on SEI growth, with the presence of plated lithium leading to a higher SEI formation rate compared to the values obtained in its absence at the same operating conditions. The model is thus able to describe cell aging over a wide range of temperatures and C-rates. In particular, it allows to quantify capacity loss due to cycling (here in % per year) as function of operating conditions. This allows the visualization of aging colormaps as function of both temperature and C-rate and the identification of critical operation conditions, a fundamental step for a comprehensive understanding of batteries performance and behavior. For example, the model predicts that at the harshest conditions (< –5 °C, > 3 C), aging is reduced compared to most critical conditions (around 0–5 °C) because the cell cannot be fully charged.

Failure mechanism and voltage regulation strategy of low N/P ratio lithium iron phosphate battery

Generally, the ratio of negative to positive electrode capacity (N/P) of a lithium-ion battery is a vital parameter for stabilizing and adjusting battery performance. Low N/P ratio plays a positive effect in design and use of high energy density batteries. This work further reveals the failure mechanism of commercial lithium iron phosphate battery (LFP) with a low N/P ratio of 1.08. Postmortem analysis indicated that the failure of the battery resulted from the deposition of metallic lithium onto the negative electrode (NE), which makes the SEI film continuously form and damage to result the progressive consumption of electrolytes. The incremental capacity analysis method is applied to visually show the whole process of battery failure. According to the three-electrode test results, we adjusted the cut-off voltage of the full battery from 3.65 V to 3.5 V, which enhance the cut-off potential of NE from −0.1 V to −0.045 V to avoid the lithium metal deposition. Besides, the life and capacity retention of battery increases from 600 cycles (70.24%) to more than 2300 cycles (82.3%) without reducing the initial capacity at 1 C. This work reveals the relationship between cut-off voltage and N/P ratio, and provides guidance for battery design and use.

Revisiting Discharge Mechanism of CFx as a High Energy Density Cathode Material for Lithium Primary Battery

AbstractLithium/fluorinated graphite (Li/CFx) primary batteries show great promise for applications in a wide range of energy storage systems due to their high energy density (&gt;2100 Wh kg–1) and low self‐discharge rate (&lt;0.5% per year at 25 °C). While the electrochemical performance of the CFx cathode is indeed promising, the discharge reaction mechanism is not thoroughly understood to date. In this article, a multiscale investigation of the CFx discharge mechanism is performed using a novel cathode structure to minimize the carbon and fluorine additives for precise cathode characterizations. Titration gas chromatography, X‐ray diffraction, Raman spectroscopy, X‐ray photoelectron spectroscopy, scanning electron microscopy, cross‐sectional focused ion beam, high‐resolution transmission electron microscopy, and scanning transmission electron microscopy with electron energy loss spectroscopy are utilized to investigate this system. Results show no metallic lithium deposition or intercalation during the discharge reaction. Crystalline lithium fluoride particles uniformly distributed with &lt;10 nm sizes into the CFx layers, and carbon with lower sp2 content similar to the hard‐carbon structure are the products during discharge. This work deepens the understanding of CFx as a high energy density cathode material and highlights the need for future investigations on primary battery materials to advance performance.

Formation of lithiated gold and its use for the preparation of reference electrodes \u2014 an EQCM study

Lithiated gold wires can be used to build reference electrodes with outstanding potential stabilities over several days and even over the course of one year. These electrodes are well suited for investigations in the context of lithium-ion batteries (LIBs). In this work, a detailed procedure for the preparation of such electrodes with tailored mechanical properties, which can be fitted gastight into electrochemical cells using commercially available fittings, is given. The electrochemical lithiation process is studied using the electrochemical quartz crystal microbalance (EQCM) technique, and the differences in lithiation of wire type and thin film type gold electrodes are discussed. All experiments were carried out with two different electrolytes, namely, a LiPF6 and a lithium bis(trifluoromethane sulfonyl) imide (LiTFSI)-based electrolyte, and we conclude that for a higher lithiation rate and long-term stability, the use of LiTFSI-based electrolyte in the preparation phase is beneficial. The EQCM data provides a better insight in the analysis of film formation processes, like the buildup of the solid electrolyte interphase (SEI) during the lithiation, the rate of deposition of metallic lithium, or additional information on the kinetics of Li-Au alloy formation.

Fast-charging capability of lithium-ion cells: Influence of electrode aging and electrolyte consumption

Fast charging of electric vehicles is becoming more and more important for achieving customer acceptance of electromobility. During fast charging, the maximum charging rate of the lithium-ion cells used in the traction batteries of electric vehicles has to be controlled properly to avoid the deposition of metallic lithium on the surface of the negative electrode, known as lithium plating. However, cycle life tests have shown that after a few hundred cycles at a moderate aging rate, the fast-charging capability of lithium-ion cells decreases and a sudden, rapid loss of capacity is observable. Therefore, to achieve a long service life and, concurrently, short charging times, it is crucial to analyze the non-plating critical charging rate depending on the mode of battery degradation.In this paper, we separately investigate the influence of the main aging factors, such as electrode aging and electrolyte consumption, on the fast-charging capability of large-format automotive lithium-ion pouch cells. The pouch cells are cycled to different states of health and a post-mortem local degradation analysis is performed. Using three-electrode test cells, the non-plating critical charging curves are determined for the aged electrode material and for test cells assembled with different amounts of electrolyte. Our findings reveal that for the investigated lithium-ion pouch cells the fast-charging capability is reduced over cycling not by the aging of the electrodes but by the consumption of electrolyte.

Model predictive fast charging control by means of a real-time discrete electrochemical model

Model-based fast charging control of Li-ion batteries requires real-time capable models with a spatial resolution to effectively prevent metallic lithium deposition. In a recent publication we showed that a discrete electrochemical modeling approach in form of a transmission line model is able to precisely describe the dynamic behavior of electrodes in time domain. The model is able to simulate and detect local lithium deposition and fulfills the requirement of real-time capability. On this basis, we study the feasibility of nonlinear model predictive control for fast charging of a graphite electrode. For this purpose, two different approaches for the cost function are introduced. The first approach controls the anode surface potential to a target value close to 0V vs. Li/Li+, to charge at the maximum rate and thus preventing Li deposition. The cost function can be rewritten explicitly to achieve a minimum computation time. The second approach weighs the charge current, which should be maximized, against the deposition current, which should be minimized. A trade-off between charging time and lithium deposition can be achieved allowing for varied priorities while finding the optimum charging trajectory for the targeted purpose.

Investigation of Li Metal Plating and Dissolution on Graphite Electrodes

Li plating, meaning the deposition of metallic Lithium on the negative electrode is considered as one of the major degradation mechanisms in Li-Ion batteries. Therefore, understanding the processes which occur between metallic Lithium and state-of-the-art electrode materials, mainly Graphite, is important to improve the life-time of Li ion cells.Lithium plating and stripping is explored using an electrochemical model, which explicitly includes the growth of plated lithium as a competing process to the direct intercalation lithium ions [1]. The model is combined with a thermodynamically consistent transport theory and implemented in the simulation framework Battery and Electrochemistry Simulation Tool (BEST). The extended framework is used to conduct a first study regarding the impact of an inhomogeneous SEI growth on the deposition of metallic lithium.Moreover, we will present recent work on simulations of model experiments investigating the dissolution of lithium deposits on Graphite electrodes [2]. Different electrolyte formulations and configurations of a lithium metal disk on the electrode are investigated to evaluate different lithium transport pathways. In each experiment some pathways are intentionally blocked, thus yielding interesting insights into the dissolution mechanism. Post-mortem analysis on the Graphite electrodes is performed using Raman spectroscopy and glow-discharge optical emission spectroscopy (GD-OES) revealing the spatial distribution of the lithium at the end of the dissolution experiment. At the same time measurements of the open circuit voltage are performed to monitor the progress of the dissolution process. Our simulations are in very good qualitative agreement with measured OCV curves and the observed lithium distributions.Therefore, the simulations provide additional “in-operando” insights to the plating as well as the dissolution of a metallic lithium phase. With the mechanistic insights optimization of the electrode and cell architecture can be deduced which help to improve the life-time of Li ion cells.[1] S. Hein, T. Danner, and A. Latz, “An electrochemical model of lithium plating and stripping in lithium-ion batteries,” ACS Appl. Energy Mater., vol. 3, no. 9, p. acsaem.0c01155, Jul. 2020.[2] C. Hogrefe et al., “Mechanistic Details of the spontaneous Intercalation of Li Metal into Graphite Electrodes,” J. Electrochem. Soc., Nov. 2020.

Model Based Investigation of Lithium Deposition Including an Optimization of Fast Charging Lithium Ion Cells

Simulating the properties of lithium ion cells during charging becomes more and more important to understand the ongoing effects during fast charging. In this work special emphasis is given to the modelling of metallic lithium deposition on the surface of negative electrode particles, so-called lithium plating, and the linked mechanical behaviour. The basis of the parametrization of the electrochemical model was a previously published experimental study on the pressure behaviour under lithium plating conditions. The developed and parametrized simple pseudo two-dimensional model reproduces the experimental study on lithium plating with a satisfying accuracy of simulated voltage and pressure trend. The model enables prediction of lithium deposition onset by matching measured pressure behaviour to the model. In addition to reproducing the cell behaviour, the model was used to optimize a measurement based fast charging protocol by using the negative electrode potential. The optimization of the fast charging protocol resulted in a 6.3% decreased charging time from 0 to 85%SoC while using a maximum C-rate of 3C. A verification of the model-based optimization has been shown by short experimental study.