bluuebunny/crossref_metadata_2025 huggingface dataset:
The Role of Entropy on the Electrochemistry of Entropy-Stabilized Oxides and Their Lithium Storage Mechanism
Authors: Tegomoh Modeste N'neckmdem , Lorie Lopez Jose , Cui Zhihao , Grandinetti Philip J. , Co Anne C.
Published: September 2023

Metals and semimetals oxides have been investigated as an alternative Li-ion battery anode due to their higher energy storage density relative to the state-of-the-art graphite electrodes. Entropy-stabilized oxides have recently gained significant interest due to their high energy and power density, but their mechanism of lithium storage is still poorly understood, in part owing to the difficulty in characterizing the chemical structure at the nanoscale. It has been hypothesized that entropy plays a significant role on the electrochemistry of this class of material. This work aims at investigating the role of entropy in this class of materials, and their Li storage mechanism using solid-state NMR spectroscopy.
Low Temperature Niobium Tungsten Oxides as Anodes for Fast Charging Li-Ion Batteries
Authors: Nagendran Supreeth , Grey Clare P.
Published: September 2023

The development of fast-charging Li-ion batteries is one of the important steps in building electric vehicles that need high power and fast charging. The reduction in the particle size to the nanometre length scale drastically improves the charging rate by increasing the surface area but lowers the volumetric energy density and can potentially result in more rapid degradation of the electrolyte via electrode-catalysed reactions. Recent reports show that niobium tungsten oxides (NbWOs) with µm sized particles serve as good anode materials for Li-ion batteries having high volumetric capacity with good cyclability at high rates while avoiding solid electrolyte interphase formation (SEI). The high rate performance of NbWOs is attributed to the topochemical charge storage mechanism that exhibits (i) minimal, highly reversible structural changes during the charge-discharge cycles, (ii) high Li-ion diffusion coefficients due to the presence of fast conducting tunnels, and (iii) high electronic conductivity upon lithiation.1,2 The NbWOs are known to crystallize into two families of different crystal structures depending on the composition and synthesis conditions. The NbWOs phases can either have tungsten bronze-type structures or block-type structures (commonly referred to as Wadsley-Roth phases). Different NbWO phases are reported in the literature3 which could serve as potential anode materials with better performance.

In this work, a series of new NbWO phases have been synthesized at reduced annealing temperatures and the structure of these phases has been established using X-ray and neutron diffraction data. The electrochemical properties of NbWO/Li half cells were examined through a series of galvanostatic (dis)charge tests at varying current rates ranging from 0.2 C to 20 C. The NbWO phases delivers a high reversible capacity of 200 and 130 mAh/g at 0.2C and 10 C respectively vs. Li metal. Here we use operando powder X-ray diffraction to investigate the structural changes occurring at the anode during the charge-discharge process in the newly synthesised NbWO phases.

Reference
s
:

1 K. J. Griffith, K. M. Wiaderek, G. Cibin, L. E. Marbella and C. P. Grey, Nature, 2018, 559, 556–563.

2 C. P. Koçer, K. J. Griffith, C. P. Grey and A. J. Morris, Chem. Mater., 2020, 32, 3980–3989.

3 N. C. Stephenson, Acta Crystallogr. Sect. B Struct. Crystallogr. Cryst. Chem., 1968, 24, 637–653.

Figure 1
Revisiting Anode Fast-Charging Capability with Solid Electrolyte Interface Using Cryogenic Transmission Electron Microscopy
Authors: Yu Yikang , Koh Hyeongjun , Yang Zhenzhen , Stach Eric A. , Xie Jian
Published: September 2023

The Li+ ion diffusion through the solid electrolyte interphase (SEI) has been widely considered as one of the limiting steps for the Li fast (de)intercalation process. However, a comprehensive understanding of the kinetic limitation of SEI on anode fast-charging remains elusive. Using H-phase (monoclinic) Nb2O5 (H-Nb2O5) as the anode material, we comprehensively studied the fast charging behaviors on both “inorganic SEI free” and “inorganic-rich SEI” anodes with cryogenic transmission electron microscopy (cryo-TEM) and X-ray photoelectron spectroscopy (XPS). The results reveal that there is a negligible difference on the electrochemical performance including fast-charging capability and cycling stability between these H-Nb2O5 anodes in spite of significant discrepancy of SEI structure (e.g. thickness and chemical component). Further, it was observed using cryo-TEM that the discrete decoration of the individual inorganic particles (e.g. Li2O) and amorphous LiNxOy species in the direct SEI does not constitute a dense solid layer. From this study, we conclude a pore diffusion mechanism is dominated across the whole direct SEI layer with those porous organic components, which is extremely faster than the lithium ion knock-off diffusion in the inner inorganic components. Thus, the SEI structures have much less influence on the limitation of the lithium ion transport kinetics than those as commonly accepted if an inner dense inorganic layer is not formed. Our results provide a refreshed understanding on the fundamentals of the lithium ion transport in SEI, and will guide future design of battery materials for fast-charging.
Microwave-Assisted Sol-Gel Synthesis of High-Voltage Ruthenium-Doped LiFePO4 Cathodes for Solid-State Lithium-Ion Batteries
Authors: Rodmyre Collin , Zheng Fan , Smirnova Alevtina
Published: September 2023

The demand for high voltage and high-capacity energy systems has grown due to increased use of portable electronics, electric vehicles, and grid energy storage systems. LiFePO4 (LFP) shows great promise as a cathode material due to its low cost, structural stability, safety characteristics, and low environmental impact. However, LFP cathodes possess a low Li-ion diffusion coefficient and poor electrical conductivity compared to oxide-based cathodes that are used currently. To make LFP competitive with oxide-based cathodes, LFP was modified to improve its characteristics. Doping of materials is a highly effective method for improving electrochemical characteristics in LFP cathodes. Ruthenium-doping of iron sites within LFP has shown positive effects in the promotion of Li-ion diffusion, reduction in band gap energies, and improved electrical conductivity. Previous studies have shown that ruthenium-doping at 0.01 moles has an increased specific capacity of 162 mAh g-1, better cycling characteristics, and reduced resistance compared to pristine LFP.1 Ruthenium doping levels above 0.02 moles have shown a decrease in specific capacity, cycling characteristics, and an increased resistance due to the formation of ruthenium oxide that disrupts the crystal lattice of LFP. In this study, LiFe1-xRuxPO4 (x= 0.01, 0.0075, and 0.005) and pristine LFP were prepared via microwave-assisted sol-gel synthesis to explore the effects of lower levels of ruthenium-doping on LFP electrochemical characteristics. Microwave synthesis was employed for reduced sintering time, beneficial effects on microstructure, and decreased cost. Samples were characterized via scanning electron microscopy, in-situ/ex-situ X-ray diffraction, energy dispersive X-ray spectroscopy, electrochemical impedance spectroscopy, and cyclic voltammetry.

The authors acknowledge financial support from the NSF IUCRC program for the “Center for solid-state electric power storage” (#2052631) and support from the South Dakota Board of Regents for the “Governor’s Research Center (GRC) for electrochemical energy storage”.

1.) Gao, Y.; Xiong, K.; Zhang, H.; Zhu, B. Effect of RU Doping on the Properties of Lifepo4/c Cathode Materials for Lithium-Ion Batteries. ACS Omega
2021, 6 (22), 14122–14129.
Unveiling the Roles of Key Dopant Elements in Tuning Electrochemical, Thermal, and Air Stabilities of High-Nickel Layered Oxide Cathodes
Authors: Cui Zehao , Manthiram Arumugam
Published: September 2023

High-nickel (Ni) layered oxides, LiNixM1–xO2 (M = Mn, Co, Al, etc.), are regarded as promising cathode candidates for next-generation lithium-based batteries in electric vehicles. Current successfully adopted LiNi0.8Mn0.1Co0.1O2 and LiNi0.8Co0.15Al0.05O2 cathodes with an energy density of nearly 750 Wh kg–1 will be inadequate for easing the driving range anxiety of customers in the foreseeable future. Increasing the Ni content further to > 90% is deemed as a feasible solution as it can simultaneously provide more energy density and reduce the raw material cost. Unfortunately, as the Ni content increases, structural, interfacial, thermal, and air stabilities of high-Ni cathodes become significantly worse, hindering their practical applications.1 In this regard, a rational compositional design with a precise use of dopant elements and their concentrations is needed to achieve the best stabilities of a high-Ni cathode. Evidently, this cannot be realized without a clear understanding of the roles of key dopant elements, such as Co, Mn, and Al, in tuning the stabilities of high-Ni cathodes.

In this work, three cathode materials with a 5% single-element doping, viz., LiNi0.95Co0.05O2 (NC), LiNi0.95Mn0.05O2 (NM), and LiNi0.95Al0.05O2 (NA), along with undoped LiNiO2 (LNO) are synthesized in-house to systematically examine the influences of Co, Mn, and Al on cycle, thermal, and air stabilities of high-Ni cathodes. From the aspect of cycle stability, it is unveiled that a critical role of dopants is regulating the state-of-charge and, more importantly, the extent of H2-H3 phase transition, which have a dominate role in dictating the cycle stability. In addition, Co offers important benefits of reducing irreversible capacity/energy loss and facilitating Li+ diffusivity. With respect to thermal stability, although Co, Mn, and Al doping can all mitigate the heat release of thermal runaway reactions, only Al doping can effectively delay the onset of thermal runaway reactions. Furthermore, Al doping can also delay the onset of outgassing (mainly O2 and CO2) at deep charge due to its ability to perturb long-range metal-metal interaction and make the metal-O bonds more ionic and stronger.2 Finally, in terms of air stability, compared to Co and Al, Mn doping can more effectively reduce the formation and accumulation of surface residual Li species (LiOH and Li2CO3) due to a higher concentration of stable Ni2+ in NM counterbalancing Mn4+. Our systematic investigation into the roles of key dopant elements can help precisely predict the most effective high-Ni cathode compositions according to the specific application requirements.

References

W. Li, E. M. Erickson, and A. Manthiram, Nat. Energy, 5, 26 (2020).

A. Manthiram, Nat. Commun., 11, 1550 (2020).
Impact of Morphology of Polycrystalline and Single Crystal Nickel Rich Cathode Particles on Performance
Authors: Tewari Deepti , Barai Pallab , Park Min Je , Siu Carrie , Shin Youngho , Srinivasan Venkat
Published: September 2023

High nickel cathode material (NMC 811) is great candidate for high performance batteries. It has high specific capacity and lower utilization of cobalt. The morphology of the cathode particles is studied in a comprehensive manner, from the impact of synthesis parameters on primary particle size, to experimental characterization and replicating the key morphological features in computational model to elucidate the morphological features critical to the performance. The polycrystalline micron sized secondary particle is comprised of thousands of nanometers sized primary particles. The single crystal is generally 2 to 3 microns in size. The “single crystal” cathode particle may be cluster of few single crystals. The length scales of primary and secondary particles as well as internal porosity of polycrystalline cathode particles changes the characteristic diffusion length as well as surface area available for electrochemical reaction. Similarly, for single crystal, the size and the degree of clustering changes the diffusion characteristics and surface area. These variations are reflected in specific capacities obtained at different C-rates. Gaining an in-depth understanding of correlation of morphological features to performance would be helpful in directing the synthesis process.

Figure 1
Measuring Lithium Concentration Gradients during Fast Charging in an Optically Accessible Li-Ion Cell and Comparing to a 1D Numerical Model
Authors: Meyer Lydia , Evans Tyler , Kee Robert J. , Porter Jason Morgan
Published: September 2023

Lithium-ion transport limitations hinder the fast charging capabilities of Li-ion batteries. At fast charging rates, insufficient transport can result in lithium concentration polarization, cell damage, and capacity loss. The magnitude of the lithium concentration polarization has been estimated with pseudo-2D (P2D) models, but has yet to be validated under fast charge conditions. In this research, we designed and built an optically accessible Li/Li symmetric cell and measured lithium concentration polarization in situ using FTIR. This novel cell design enabled the rapid collection of IR spectral images between electrodes at small timescales. From these in situ measurements, we can measure dynamic lithium concentration polarization at timescales relevant to fast charging. The IR imaging method was demonstrated in a Li/Li symmetric cell with an electrolyte of 1M LiPF6 in 50/50 ethylene carbonate/ethyl methyl carbonate (vol./vol) revealing lithium concentration gradients of over 2mM/mm. Results were compared with 1D numerical models utilizing concentration-dependent lithium transport properties. The comparison between our experimental and computational results gives insight into the limitations of models to adequately simulate transport in highly polarized cells. This test also showed promise for accurately measuring lithium transport properties in future experiments.
Elimination of Rate-Induced Graphite Exfoliation and Li Plating in Benchmark-Exceeding Battery Electrolytes
Authors: Gao Hongpeng , Holoubek John , Yan Qizhang , Yin Yijie , Bao Wurigumula , Liu Haodong , Baskin Artem , Cai Guorui , Li Weikang , Tran Duc , Liu Ping , Meng Shirley , Chen Zheng
Published: September 2023

Lithium-ion batteries (LIBs) face untenable reductions in cycle life under extreme fast-charging (XFC) conditions, which primarily originate from a variety of kinetic limitations between the graphite anode and the electrolyte. Through quantitative Li+ loss accounting and comprehensive materials analyses, it is directly observed that the operation of LIB pouch cells at 4 C||C/3 (charging||discharging) results in Li plating, disadvantageous solid-electrolyte-interphase formation, and solvent co-intercalation leading to interstitial decomposition within graphite layers. By employing a designed ester-based electrolyte, the capacity retention of these cells improved from 55.9% to 88.2% after 500 cycles when operated at the aforementioned conditions. These metrics are the result of effective mitigation of these failure modes due to superior Li+ transport and desolvation characteristics demonstrated through both experimental and computational characterizations. This work reveals the vital nature of electrolyte design to XFC performance.

Figure 1
Nanocomposite Engineering of High-Capacity Partially Ordered Cathode Materials for Li-Ion Batteries
Authors: Lee Jinhyuk , Seo Dong-Hwa , Lee Eunryeol
Published: September 2023

Understanding the local cation order in the crystal structure and its correlation with cycling performances has promoted the development of high-energy Mn-rich cathode materials for Li-ion batteries, such as Li- and Mn-rich layered cathodes (LMR, e.g., Li1.2Ni0.2Mn0.6O2) that are considered as nanocomposite layered materials with C2/m Li2MnO3-type medium-range order (MRO). Also, Li diffusivity in high-capacity Mn-based disordered rock-salt (DRX) cathodes (e.g., Li1.2Mn0.6Nb0.2O2) was found to be influenced by the short-range order (SRO) of cations, highlighting the criticality of engineering the local cation order in designing high-energy materials. In this presentation, we will discuss the nanocomposite, heterogeneous nature (like MRO found in LMR) of ultrahigh-capacity partially ordered cathodes (e.g., Li1.68Mn1.6O3.7F0.3) made of distinct domains of spinel-, DRX- and layered-like phases, which is different from conventional single-phase DRX cathodes. This multi-scale understanding of ordering informs engineering the nanocomposite material via Ti doping, altering the intra-particle characteristics to increase the content of the rock-salt phase and heterogeneity within a particle. This strategy greatly improves the reversibility of Mn- and O-redox processes to enhance the cycling stability of the partially ordered DRX cathodes (nearly ~30 % improvement of capacity retention). Overall, our work sheds light on the importance of nanocomposite engineering to develop ultrahigh-performance, low-cost Li-ion cathode materials.
A Low-Temperature Boron-Based Composite Coating for Ni-Rich Li-Ion Battery Cathode with Enhanced Cycle Life and Safety
Authors: Chen Hsi , Chen Yan-Cheng , Lee Jyh-Fu , Chen Jin-Ming , Sheu Hwo-Shuenn , Pao Chih-Wen , Chen Jeng-Lung , Wu Nae-Lih (Nick)
Published: September 2023

Due to the continuously aggravating global warming crisis, the aim of reducing CO2 emissions by replacing fossil fuels with clean energy sources has raised the demand for electric vehicles (EVs) and driven research in pursuing high-energy rechargeable lithium-ion batteries (LIBs). For the cathode component, Ni-rich cathode materials such as LiNixCoyMn1-x-yO2 (NCM) have been widely adopted in commercial EVs due to their high specific capacity (~200 mAh/g) and high operating voltage (~ 4V vs. Li/Li+). However, Ni-rich cathode materials are still confronting challenges such as poor cycle stability and safety issues. To tackle these problems, a boron-based surface modification of Ni-rich cathode material (NCM) is achieved via a low-temperature process in this work. The coated NCM shows comparable rate capability but with substantially improved cycle stability. In terms of safety issues (thermal runaway process), the onset temperature of the thermal runaway process in presence of electrolyte is delayed by 40°C while the total heat release and the maximum heat flow are both decreased by over 40%. Post mortem and in situ X-ray characterizations using synchrotron radiation further illustrate the reasons of the enhanced cycle stability and safety. Results show that the boron-based composite coating is able to decrease the extent of reaction between NCM and the electrolyte during both cycling and the thermal runaway process. Our results demonstrate the use of a low-temperature boron-based composite coating as an effective surface modification method of Ni-rich cathode materials to achieve long-life and high-safety lithium-ion batteries.
SECM as a Direct Method to Track Changes in Silicon Passivation
Authors: McBrayer Josefine , Harrison Katharine L , Fenton Kyle , Minteer Shelley
Published: September 2023

Silicon is a promising next-generation anode to increase energy density over current state of the art graphite anodes. Despite much progress in improving the cycling of silicon electrodes, the calendar life is still problematic. In this work, scanning electrochemical microscopy (SECM) was used to track the reactivity of the surface of a silicon thin film over time to better understand the role of the solid electrolyte interphase (SEI) during calendar aging. The passivation of silicon was found to decrease with increasing time and potential relative to Li/Li+. Along with the decrease in passivation with time, the homogeneity of passivation decreases. Despite some local “hot spots” of reactivity, within resolution limits (tip radius of 12.5 μm), the changes in passivation seemed to be global SEI failure rather than local (for example, cracking). In all cases, the delithiated silicon was less passivated than the lithiated silicon. When delithiated up to 1.5 V versus Li/Li+ the surface was found to be more reactive than the pristine silicon surface. This could potentially be the result of destabilization of the surface by SEI oxidation. When the cell was only delithiated up to 0.75 V versus Li/Li+, the surface was still passivating, but still less so than the lithiated surface. This indicates that the potential of the anode should be kept at or below ∼ 0.75 V Li/Li+ for half cell and full cell cycling to prevent decreasing SEI passivation.

This research was supported by the U.S. Department of Energy’s Vehicle Technologies Office under the Silicon Consortium Project, directed by Brian Cunningham, and managed by Anthony Burrell. This work was conducted in part by the Alliance for Sustainable Energy, LLC, the manager and operator of the National Renewable Energy Laboratory for the U.S. Department of Energy (DOE) under Contract No. DE-AC36-08GO28308. Sandia National Laboratories is a multimission Laboratory managed and operated by National Technology & Engineering Solutions of Sandia, LLC, a wholly owned subsidiary of Honeywell International Inc., for the U.S. Department of Energy’s National Nuclear Security Administration under contract DE-NA0003525.
(Energy Technology Division Research Award) Multiphysics, Multiscale Modeling of Electrochemical Energy-Conversion Technologies
Authors: Weber Adam Z.
Published: September 2023

As electrochemical technologies become increasingly important in our energy paradigm, there is a need to examine them holistically. For commercialization and optimization, one requires a detailed understanding of the underlying physics and phenomena. Furthermore, for such technologies to become practical, they need to operate at high current densities to minimize various cell costs. This operating space necessitates the need for efficient transport of reactants and removal of products from the reaction site, where it is increasingly recognized how critical this local environment and transport are to performance. Mathematical modeling is ideally suited to understand these various interactions and provide insights and optimization strategies. In this talk, various porous electrodes will be examined in terms of their intrinsic transport phenomena. Technologies to be discussed include proton-exchange-membrane fuel cells and electrolyzers and gas-diffusion electrodes for CO2 reduction.

For PEMFCs, such mass transport is dominated by transport of oxygen molecules to the reaction site within the catalyst layer. For electrolysis applications, similar gas-diffusion-electrode (GDE) architectures are being investigated and the various tradeoffs endemic in such structures will be discussed such as reactant water transport. In this talk, we will explore the various tradeoffs endemic in GDE architectures for various electrochemical reactions including CO2 and CO reduction and O2 and H2 consumption and evolution. For all technologies, such tradeoffs are quantified through multiphysics modeling and key diagnostics of the cells including breakdowns of the various limiting phenomena at both the micro and macroscales, where the local conditions and environment around the reaction center impact reactivity in both transient and steady state conditions, enabling metastable states. It will be shown how transport phenomena dominate a lot of the performance and selectivity of the catalysts, which is critical to understand to improve overall performance. In addition, we will explore how different integration schemes can greatly impact overall response, which can overshadow any intrinsic changes due to different electrocatalyst materials, thereby providing different design rules. A key focus of this talk will be in exploring and describing the various transport and competing phenomena within the electrochemical cells and how to describe them physically and numerically
(Invited) Multiscale Diffusion-Reaction Heat Transfer Analysis for Predicting Thermal Runaway in Li-Ion Cells and Battery Packs
Authors: Jain Ankur
Published: September 2023

Thermal runaway in Li-ion cells and battery packs remains a topic of much importance for ensuring the safety of electrochemical energy conversion and storage systems. Thermal runaway also indirectly affects performance, as conservative overdesign to reduce the risk of thermal runaway affects system-level performance metrics such as energy storage density. Given the considerable challenges in experimental investigation of thermal runaway, theoretical models to predict thermal runaway characteristics of a cell or battery pack are critically needed. Such models can help guide the design of experiments, and ensure that practical systems are reasonably safe without being needlessly overdesigned.

This talk will summarize ongoing work on theoretical analysis of multilayer diffusion-reaction heat transfer problems for predicting thermal runaway in Li-ion cells and battery packs. Following a linearization of heat generation terms, the governing energy conservation equation is solved in a multilayer geometry representative of a Li-ion cell comprising multiple electrode and separator layers, or of a battery pack containing several cells. It is mathematically shown that under certain conditions, this problem may admit a finite number of imaginary eigenvalues, which are shown to cause thermal runaway. It is shown that the occurrence of imaginary eigenvalues is governed by a delicate balance between heat generation, thermal conduction within the multilayer body and heat removal from the boundaries, based on which, an explicit threshold condition for thermal runaway is derived. This threshold condition is interpreted in the context of parameter values relevant to Li-ion cells. For example, it is shown that boundary cooling is severely limited in its role to prevent thermal runaway, whereas improving thermal transport within the cell is likely to be a lot more effective. This theoretical model is also extended to a two-layer problem comprising a finite layer adjoined by a semi-infinite body that may model immersion cooling of a Li-ion cell or battery pack. It is shown that while this diffusion-reaction problem is, in principle, unconditionally unstable, the finite time period of any discharge process may allow the temperature field to still remain within a safe envelope, if designed appropriately. Based on this mathematical model, scenarios related to immersion cooling of pouch cells are investigated.

The theoretical work described in this talk is broadly relevant to several diffusion-reaction systems. In the particular context of Li-ion cells, these results may form the foundation of techniques to proactively predict and prevent thermal runaway in Li-ion cells and battery packs.
(Keynote) Electrode Stimulation: Ohmic Microscopy and the Monopolar Electrode
Authors: Scherson Daniel , Heer Arvind , Mantelli Harlan , Georgescu Nicholas , Han Qi
Published: September 2023

In a recent communication (1), we described a novel method of controlling the electrostatic potential in the solution neighboring a working electrode, we have dubbed the
monopolar electrode
, ME, polarized at a constant potential, EME, using a potentiostat. This tactic involved passing current between a second or
stimulating electrode
, SE, placed in front, and at a relatively small distance from the ME, and a distant auxiliary electrode, AE. Depending on the polarity of the current flowing through the SE, the electrostatic potential just outside the ME could be modified so as to increase or decrease the surface overpotential, and, thus modulate the rates of redox reactions at the ME|electrolyte interface. This presentation will review critical aspects of ohmic microscopy, and illustrate with two examples the
electrode stimulation
effect, using a ring disk electrode, RRDE, in which current flowing through the disk acting as the SE, is employed to induce reactions on the ring, acting as the ME, namely: i. the oxidation of adsorbed carbon monoxide on Pt using a Pt|glassy carbon RRDE and ii. the reduction of selenite to elemental Se on Au in aqueous 0.1 M HClO4 using a Au|Au RRDE. In both these cases, the
stimulation
current was generated by scanning the potential of SE within its double layer region, so as to minimize any changes in the actual composition of the solution adjacent to the ME, while monitoring the current flowing through the ME, IME
. Under these conditions, the electrostatic potential in solution follows the primary current density. The efficiency of the
stimulation
process was determined by coulometric analysis of the CO oxidation current and in the case of selenite via a coulometric analysis of the current due to the oxidation of elemental Se produced by the reduction of selenite. The stimulation

efficiency, in this latter case, could be accurately determined from a coulometric analysis of the peak for Se oxidation observed by subsequently scanning the ME linearly toward positive potentials to yield selenite. Excellent quantitative agreement was obtained between IME
and EME
as a function of Idisk
and theoretical simulations employing COMSOL using parameters extracted from independent measurements performed under otherwise identical experimental conditions. This overall approach will open new prospects for gaining insight into the rates of surface diffusion and other interfacial dynamics phenomena.

Acknowledgements

This work was supported by a grant from NSF, CHE-1412060

References

Han, Q.; Georgescu, N. S.; Gibbons, J.; Scherson, D. Acta
2019, 325, 134957.
(Invited) Multi-Scale Battery Modelling: Understanding Coupled Electrochemical and Mechanical Effects
Authors: Wu Billy , Ai Weilong , Kirkaldy Niall , Bonkile Mayur , Jiang Yang , Naylor-Marlow Max , Patel Yatish , Liu Xinhua , Wang Huizhi , Martinez-Paneda Emilio , Offer Gregory James
Published: September 2023

Lithium-ion batteries are a key enabler for a low-carbon future, however their performance and lifetime are influenced by complex and coupled electrochemical, thermal and mechanical factors across different length and time scales. In this talk, we explore the key degradation modes which limit battery lifetime and how multi-scale models can help describe these effects towards improved cell designs and device control. At the particle level, we explore how phase field fatigue models of cathode particles can be used to understand crack growth, leading to loss of active material [1]. Here, non-linear crack growth is observed due to the fatigue of material properties and crack merger, leading to a transition from slow to rapid crack growth rate. Use of these models can identify critical C-rates and particle sizes which mitigate cracking.

At the continuum scale, we then investigate how these stresses evolve during cycling, with stress heterogeneities arising initially at the electrode-separator interface, but later propagating to the electrode-current collector interface [2]. We then extend this study to composite anodes of graphite and silicon, where highly non-linear behaviour is observed [3]. Here, the graphite phase provides the majority of the reaction current density at high state-of-charge operation, with this then shifting to the silicon phase at low state-of-charge operation, with hysteresis effects observed due to the silicon. This behaviour is attributed mostly to the different open circuit potentials of the two different phases. Finally, we explore how these effects propagate to the battery pack scale and highlight the divergence of material level performance from their real-world implementation [4].

References

[1] A coupled phase field formulation for modelling fatigue cracking in lithium-ion battery electrode particles. W Ai, B Wu, E Martínez-Pañeda. Journal of Power Sources. 2022.

[2] Electrochemical Thermal-Mechanical Modelling of Stress Inhomogeneity in Lithium-Ion Pouch Cells. W Ai, L Kraft, J Sturm, A Jossen, B Wu. Journal of the Electrochemical Society. 2019.

[3] A composite electrode model for lithium-ion batteries with silicon/graphite negative electrodes. W Ai, N Kirkaldy, Y Jiang, G Offer, H Wang, B Wu. Journal of Power Sources. 2022.

[4] The effect of cell-to-cell variations and thermal gradients on the performance and degradation of lithium-ion battery packs. X Liu, W Ai, M Naylor Marlow, Y Patel, B Wu. Applied Energy. 2019.

Figure 1
(Invited) Three-Dimensional Modeling of Dendrite Formation during Rapid Charging
Authors: Shimpalee Sirivatch , Lopata Joseph Steven , Garrick Taylor R. , Teel Hunter
Published: September 2023

Dendrites commonly form during rapid charging of lithium-ion batteries when plating is favored over intercalation. If not mitigated, the potential exists for dendrites to growth through the separator and short the anode and cathode. One metric for diagnosing plating conditions in a computational model is the minimum local potential at the anode, where plating is seen to be thermodynamically favorable below 0.0 V with respect to Li metal.[1, 2] Three-dimensional (3D) models can offer insight to predict the possibility of local lithium plating and can be used as a tool to detect possible global lithium plating onset, so it follows that 3D microstructure models can be used to predict dendrite formation and propagation as well. The volume of fluid (VoF) method, which is commonly used to model the flow of immiscible fluids, can be used to divide the electrolyte region into a liquid phase and a dendrite phase.[3]

This strategy is implemented in a 3D microstructure model of a lithium-ion battery to observe the growth of dendrites at the anode during rapid charging. Under onset conditions at the solid/electrolyte interface (SEI), the solid metal phase is deposited at the SEI. Upon growth, the overall electrolyte resistance at the tip of the metal phase is reduced, leading to dendrite growth. The 3D model provides valuable insight into various conditions that may cause plating, if dendrites are formed due to plating, and whether the dendrites formed may proceed to a shorting even

Reference

T. R. Garrick, J. Gao, X. Yang and B. J. Koch, J Electrochem Soc, 168, 010530 (2021).

U. Janakiraman, T. R. Garrick and M. E. Fortier, J Electrochem Soc, 167, 160552 (2020).

T. Jang, L. Mishra, S. A. Roberts, B. Planden, A. Subramaniam, M. Uppaluri, D. Linder, M. P. Gururajan, J.-G. Zhang and V. R. Subramanian, J Electrochem Soc, 169, 080516 (2022).
(Invited) Dendrite Formation in Lithium Electrodeposition – Insights from Experiments and Modeling
Authors: Maraschky Adam M. , Wasalathanthri Ruwani , Akolkar Rohan
Published: September 2023

High-energy density batteries are essential for powering future electric vehicles and electric aircrafts. The Li-metal anode offers the highest theoretical specific energy among practically available anode materials; however, a major hurdle in the progress towards rechargeable Li-metal batteries is the dendritic electrodeposition of Li metal during the battery charging process. The physicochemical mechanisms behind Li dendrite formation have been a topic of rich and fervent research, but many questions remain presently unanswered. Among these, a key question of significance to battery charging is: at what time instant is Li dendritic growth initiated? In the present talk, this question will be addressed through a combination of experiments and modeling. Chronopotentiometry during galvanostatic Li electrodeposition coupled with in situ optical microscopy reveals that the first emergence of Li dendrites corresponds to the time instant when the surface overpotential reaches a maximum.1 Electrochemical impedance spectroscopy shows that the increase in the surface overpotential preceding this maximum is due to gradual growth of the solid electrolyte interphase (SEI). This SEI layer growth induces Li+ concentration depletion at the electrode-SEI interface, promoting amplification of surface asperities and thus dendrites that rupture the SEI. A transport model incorporating Li+ diffusion across a growing SEI layer is developed, and shown to predict Li dendrite onset times that are in good agreement with experimental observations over a wide range of current densities, temperature, and initial SEI thicknesses.2 A key conclusion of our work is that liquid-phase mass transport limitations, often characterized by the Sand’s equation, do not reliably predict the onset of Li dendrites.3 Rather, transport characteristics and associated instabilities within solid-phase surface films on Li are predominantly responsible for dendrite formation. Our work provides clues for how dendrite formation could be arrested for enabling rechargeable Li-metal anodes for use in next-generation batteries.

References:

A. Maraschky and R. Akolkar, “Mechanism Explaining the Onset Time of Dendritic Lithium Electrodeposition via Considerations of the Li+ Transport within the Solid Electrolyte Interphase”, J. Electrochem. Soc., 165 (14), D696-D703 (2018).

A. Maraschky and R. Akolkar, “Temperature Dependence of Dendritic Lithium Electrodeposition: A Mechanistic Study of the Role of Transport Limitations within the SEI”, J. Electrochem. Soc., 167, 062503 (2020).

R. Wasalathanthri and R. Akolkar, “Perspective—does the sand equation reliably predict the onset of morphological evolution in lithium electrodeposition?”, J. Electrochem. Soc., 169, 092519 (2022).
(Keynote) Electrode/Electrolyte Interfacial Phenomena: Impact on Battery Performance
Authors: Balbuena Perla B.
Published: September 2023

Electrode/electrolyte interfaces are present in electrocatalysis, batteries, and in many biological systems. The evolution of the multiphase/multicomponent interfacial system has significant influence on the behavior of the overall process in which the interfaces are inserted (e.g., electrocatalytic cell, battery, biological membrane). Theoretical and computational studies of electrochemical interfaces at the atomistic level pose significant challenges including the complexity of describing amorphous phases, dynamic and reacting interfaces, among others. Here we will discuss ion and electron transport near and at interfaces, as well as nucleation and growth of interphases, cross-talk events, and their role on the overall battery performance and degradation events for various Li-metal battery chemistries.
(Invited) Modeling the Dependence of the Lithium-Sulfur Battery Performance on the Materials and Cell Design Factors
Authors: Eroglu Damla
Published: September 2023

Lithium-sulfur (Li-S) batteries have attracted significant research interest in the last couple of decades due to their significantly high theoretical specific capacity in addition to the fact that the cathode active material sulfur is abundant and inexpensive and has a high capacity. However, several mechanisms hinder the Li-S battery performance; the depletion of the lithium metal or the electrolyte in the cell with cycling, the polysulfide shuttle mechanism due to the transport of the soluble reaction intermediates between the cathode and the anode, and the passivation of the cathode surface due to the precipitation of the insoluble product Li2S are some examples of these mechanisms that lead to fast capacity fade and thus limited cycle life of the Li-S batteries. As a result of the highly complicated reaction and degradation mechanisms in the cell, the performance of the Li-S battery significantly depends on the materials and cell design. Consequently, it is of significant importance to study this key relation. Herein, we develop electrochemical models to predict the impact of critical materials and cell design parameters: electrolyte-to-sulfur (E/S) ratio, carbon-to-sulfur (C/S) ratio, sulfur loading, and carbon and electrolyte properties, on the Li-S battery performance. We use zero-dimensional (concentration-independent) and one-dimensional (concentration-dependent) models to project the isothermal, constant-current discharge behavior of the Li-S cell. In our models, a novel definition for the electrochemically active area is proposed, which describes the cathode area as a function of the carbon amount and the porosity in the cathode. Experimental trends on the influence of cathode design parameters on the discharge performance are captured successfully. A mechanistic explanation of these trends is offered with the presented model by introducing the proposed electrochemically active area.
(Invited) Experimental and Data Analysis Platforms to Better Understand the Corrosion and Discharge of Powdered Zn
Authors: Lenhart Brian , Zuraw Michael , Mustain William Earl
Published: September 2023

Zinc anodes have been a cornerstone of many commercial and pre-commercial battery technologies including primary and secondary alkaline cells, Zn-air batteries and Zn-ion batteries. To maximize the performance of devices at both the lab and commercial scales, moderate surface area (mm-sized) Zn powder is used – either immobilized onto a diffusion electrode or incorporated into a slurry. Unlike nano-sized materials, micron-sized materials are poorly characterized by traditional electrochemical techniques like thin-film rotating disk electrodes, because the roughness introduced by the relatively large particles disrupts the ideal fluid flow near the surface, negating the mathematical description of the electrode behavior. This leads many researchers to try and characterize the Zn behavior in more application-like cells. The downside of doing this is that there is a strong influence of the counter electrode, electrolyte solution and the efficacy of the specific individual in assembling the cells. Therefore, there is a need to develop new platforms that have the ability to determine the electrochemical properties of powdered Zn – most notably achievable capacity and corrosion current – and to develop analytical models to describe their behavior.

Over the past several years, our group has been developing new platforms to understand how Zn behaves during discharge and charge, including 1-D cells and cells that mimic the geometry of a primary alkaline battery [1]. However, those platforms have their limitations. In this talk, another new cell, coined the “gravity cell” will be discussed. The gravity cell has a small well where Zn (either as raw powder or in slurry form) is gravity deposited onto an indium foil current collector. Typically, a gel electrolyte is placed on top of the Zn bed, followed by liquid electrolyte, which also contains the counter and reference electrodes. The gravity cell is used to both discharge the Zn powder and to measure its corrosion characteristics. This can be done as a function of mass loading, which introduces limitations into the behavior as the Zn discharges from the Zn/gel interface towards the current collector. This type of discharge, limited by Ohmic resistance, requires new mathematical frameworks to extract the desired parameters. This talk will focus on the design of the cell as well as the derivation of the mathematical framework. Then, data will be shown using several types of Zn powder both in the presence and absence of surfactants that aim to reduce the corrosion rate.

References:

Faegh, T. Omasta, M. Hull, S. Ferrin, S. Shrestha, J. Lechman, D. Bolintineanu, M. Zuraw and W.E. Mustain, “Understanding the Dynamics of Primary Zn-MnO2 Alkaline Battery Gassing with Operando Visualization and Pressure Cells”, J. Electrochem. Soc., 165 (2018) A2528-A2535
Efficient Determination and Analysis of Model-Based Optimal Charging Protocols to Minimize Li-Ion Battery Degradation
Authors: Uppaluri Maitri , Subramaniam Akshay , Lim Jin-hyung , Subramanian Venkat R.
Published: September 2023

Alternate charging protocols for lithium-ion batteries have been proposed to reduce aging and improve their lifetime.1 Physics-based models capture the mass and charge transport of lithium ions within the cell by solving their corresponding governing equations. Optimal charging profiles can be derived from physics-based models by controlling the cell's internal state and restricting phenomena that lead to cell degradation.

Our previous efforts have shown that optimal charging profiles that restrict intercalation-induced stresses, lithium plating, and the SEI layer growth can be derived with reformulated physics-based models. 2
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4

Deriving optimal charging profiles in real-time can be performed through the optimization of reduced-order models. This work demonstrates several optimal charging profiles derived from the Tanks-in-Series model 5 to minimize various degradation mechanisms. We test these profiles under several cycling protocols and analyze the effect of each mechanism on capacity loss. We have also shown cases of deriving optimal profiles during the cycling period to update the profile based on the aging trajectory of the cell.

References

A. Tomaszewska et al., eTransportation, 1, 100011 (2019).

B. Suthar, V. Ramadesigan, S. De, R. D. Braatz, and V. R. Subramanian, Phys. Chem. Chem. Phys., 16, 277–287 (2014).

B. Suthar, P. W. C. Northrop, R. D. Braatz, and V. R. Subramanian, J. Electrochem. Soc., 161, F3144–F3155 (2014).

M. Pathak, D. Sonawane, S. Santhanagopalan, R. D. Braatz, and V. R. Subramanian, ECS Trans., 75, 51–75 (2017).

A. Subramaniam et al., J. Electrochem. Soc., 167, 013534 (2020).
Modeling and Analysis of Suspension-Based Electrolytes in Redox Flow Cells
Authors: Majji Madhu V. , Neyhouse Bertrand J. , Brushett Fikile R.
Published: September 2023

Electrochemical systems with flowable suspension electrolytes (FSEs) have potential to help address growing demands for large-scale energy storage in order to bridge the gap between energy demand and renewable energy generation. Redox flow batteries with FSEs, for example, have several advantages in addition to long-duration energy storage and independent scaling of power and energy offered by the traditional flow batteries.1 FSEs containing solid energy storage materials enable higher charge storage capacities and hence higher energy densities, as well as new operating modes such as dissolution from and precipitation onto suspended particles.2-3 However, these emerging electrolyte compositions challenge cell design and operation as new performance trade-offs arising from the complex interplay of non-Newtonian rheology, flow-dependent transport properties, and electrochemical phenomena, must be considered.4

In this presentation, we will introduce a one-dimensional model to study the performance of a representative FSE-containing redox flow cell as a function of various material properties and operating conditions. The model integrates porous electrode theory with non-Newtonian suspension rheology and flow-dependent charge and species transport to investigate connections between rheological and electrochemical phenomena. We expound key dimensionless groups that arise from non-dimensionalizing the governing equations and describe the relative magnitudes of interrelated processes. We discuss model predictions of the cell performance in the multivariable space of the dimensionless groups using computed cell overpotentials and power relative to the pumping power, and identify specific operating regimes. Ultimately, the analysis will offer design considerations for electrochemical systems with FSEs, allowing more informed materials selection, cell engineering, and system architectures.

Acknowledgments

This work was funded by the Skoltech – MIT Next Generation Program. B.J.N gratefully acknowledge the NSF Graduate Research Fellowship Program under Grant Number 1122374. Any opinion, findings, and conclusions or recommendations expressed in this material are those of the authors and do not necessarily reflect the views of the NSF.

References

M. L. Perry and A. Z. Weber, J. Electrochem. Soc., 163, A5064–A5067 (2016).

H. Parant et al., Carbon, 119, 10–20 (2017).

X. Wang, J. Chai, and J. “Jimmy” Jiang, Nano Materials Science, 3, 17–24 (2021).

N. C. Hoyt, R. F. Savinell, and J. S. Wainright, Chemical Engineering Science, 144, 288–297 (2016).