bluuebunny/crossref_metadata_2025 huggingface dataset:
Fluorination Promotes Lithium Salt Dissolution in Borate Esters for Lithium Metal Batteries
Authors: Ma Peiyuan , Amanchukwu Chibueze
Published: August 2024

Lithium metal batteries promise higher energy densities than current lithium-ion batteries but require novel electrolytes to extend their cycle life. To promote electrolyte stability against lithium metal and improve the reversibility of lithium deposition/stripping, several electrolyte design strategies have been pursued. For example, high concentration electrolytes (HCEs) and localized high concentration electrolytes (LHCEs) produce solvation structure rich in salt aggregates and ion pairs, which can increase lithium metal cycling Coulombic efficiency to as high as 99.5%. Recently, molecular design of fluorinated ether solvents also leads to high lithium metal Coulombic efficiency of up to 99.9% in single-solvent-single-salt ~ 1 M electrolytes. In addition, fluorinated acetals, fluorinated carbonates, and fluorinated sulfonamides are also reported to enable efficient lithium metal cycling. Among those novel electrolytes, fluorinated solvents or diluents are frequently used because fluorinated moieties are known to yield LiF as a preferable component in solid electrolyte interphase (SEI). However, fluorinated groups are believed to weaken ion solvation as most fluorinated solvents show poorer solvation ability or lower ionic conductivity compared to their nonfluorinated counterparts. The trade-off between SEI passivation and ion solvation limits further optimization of fluorinated electrolytes.

In this work, we synthesize tris(2-fluoroethyl) borate (TFEB) as a new fluorinated borate ester solvent. Interestingly, moderately fluorinated TFEB shows unexpectedly high lithium salt solubility (~1 M LiFSA) while the nonfluorinated triethyl borate (TEB) and heavily fluorinated tris(2,2,2-trifluoroethyl) borate (TTFEB) can hardly dissolve lithium salt. Through density functional theory (DFT) calculations and ab-initio molecular dynamics (AIMD) simulations, we show that the partially fluorinated -CH2F group in TFEB acts as primary coordination site that promotes lithium salt dissolution. The electrochemical property of TFEB electrolyte is then compared to the methoxy polyethyleneglycol borate esters reported in literature. Owing to the fluorinated solvent structure, TFEB electrolyte passivates lithium metal with LiF-rich SEI and supports compact lithium deposition morphology, high lithium metal Coulombic efficiency, and stable cycling of lithium metal/LiFePO4 cells. This work ushers in a new electrolyte design paradigm where partially fluorinated moieties enable salt dissolution and can serve as primary ion coordination sites for next-generation electrolytes.

Figure 1
(Invited) Structural Lithium-Ion Battery Based on LiFePO4/Reduced Graphene Oxide Composite Cathode and Graphene Anode Prepared via Electrophoretic Deposition on Carbon Cloth
Authors: Okoroanyanwu Uzodinma , Pande Varun , Senger Claire , Watkins James J.
Published: August 2024

Structural lithium-ion batteries based on binder-free LiFePO4/reduced graphene oxide composite cathode electrode and graphene anode electrode are prepared respectively via electrophoretic co-deposition of LiFePO4, reduced graphene oxide, and carbon black on carbon cloth substrate for the cathode, and graphene oxide and carbon black on carbon cloth substrate for the anode. Following deposition, the electrode materials were dried. The graphene oxide of the anode was reduced to graphene via rapid thermal annealing. Possessing excellent stiffness, strength-to-weight ratio, and good electrical conductivity, the carbon cloth substrate serves multifunctional roles in the battery: as structural reinforcement and mechanical load bearing element and as current collector. Given its good electrical conductivity, high aspect ratio, and high surface area, reduced graphene oxide improves electrical conductivity within the cathode and provides sites for hosting LiFePO4; this enhances reversible Li ion extraction from the host during cycling. Graphene with its good electrical conductivity and high aspect ratio provides sites for insertion of Li ions in the anode; this enhances the aerial lithiation capacity of the battery system. Carbon black enhances conductivity within the two electrodes and reduces interfacial impedance. The electrochemical properties of the electrodes are strongly correlated to their microstructure and phase composition. Electrochemical characterization of the electrodes and their performance in half-cell and full cell configurations are evaluated. Additionally, Li-ion diffusivity within the materials is evaluated with three independent electroanalytical methods, including potentiostatic and galvanostatic and intermittent titration techniques, and electrochemical impedance spectroscopy.
Realizing of Earth-Abundant, Mn-Rich Cathodes for Lithium-Ion Batteries
Authors: Chen Jiajun , Gutierrez Arturo , Balasubramanian Mahalingam , Croy Jason R.
Published: August 2024

The development of sustainable materials for lithium-ion batteries (LIB) is of critical importance, especially considering the significant, ever-growing demand for energy storage technologies. Lithium- and manganese-rich (LMR) oxides are of great interests because of their inherently high capacities/energies and the potential economic benefits associated with earth-abundant manganese-based compositions. However, despite their attractive properties, LMR commercialization has been hindered by several challenges.

In this presentation we will explore these challenges across length-scales, spanning from the atomic to the cell level, and consider the correlated effects observable in electrochemical cells. Detailed synthesis studies will be presented concerning morphological control of LMR cathode precursors; complex local structure will be discussed and linked to properties that are unique to this class of cathodes; and finally, techno-economic modeling will be used to evaluate the potential of an LMR system – developed at Argonne National Laboratory – for practical implementation in large-format EV cells.

The work presented herein represents research and development efforts led by Argonne National Laboratory within the Vehicle Technologies Office, Earth-abundant Cathode Active Materials (EaCAM) consortium. This effort endeavors to bridge the knowledge gap across various length-scales, from atomic-level intricacies to broader cell-level implications, to innovate, and enhance the sustainability of energy storage technologies.
Model-Based Interpretation of Thermal-Gradient Effects in Li-Ion Cells
Authors: Evans Tyler A. P. , Ishtiaque MD Mahdi Ul , Harkaway Andrew , Pint Cary L. , Kingston Todd A. , Kee Robert J.
Published: August 2024

The present study develops a combined experimental and modeling approach to study temperature gradients in Li-ion batteries. Although through-plane temperature differences may be small (ΔT ≈ 1-10 °C), large interelectrode thermal gradients (∇T ≈ 1,000-10,000 °C/m) can be present and have been found to significantly affect Li-ion battery performance and degradation [1,2]. Figure 1 illustrates a thin pouch cell (order of 300 microns thick) sandwiched between cool and warm plates. The cell uses a graphite anode and a NMC622 cathode. By maintaining the temperature of the cool and warm blocks, a thermal gradient can be enforced across the cell. Depending on how the cell is positioned, the cell’s cathode or anode can be on the cool or warm side. Experiments include overpotential analysis and galvanostatic intermittent titration technique (GITT) at different states of charge. Results show different behaviors as the thermal gradient is applied and the directionality of the thermal gradient changes.

This presentation presents a pseudo-two-dimensional (P2D) model [3] that has been modified to represent the experimental conditions, including the thermal gradients. The model considers the temperature dependencies of thermodynamic properties, electrolyte conductivities, electrode diffusion coefficients, intercalation rates, etc. [4]. The model captures some, but not all, of the measured behaviors. Thus, an important objective is to investigate physical and chemical behaviors that are not included in typical P2D models. For example, off-diagonal Onsager contributions could be significant in the presence of high temperature gradients. The results predict how thermal gradients can contribute to Li-ion concentration fluxes (Soret contribution), and thus affect battery performance. The scientific intent is to understand the thermal gradient behaviors and thus assist battery design guidelines and battery-management control considerations.

Acknowledgments

The authors thank the Office of Naval Research (Dr. Michele Anderson) for financial support (ONR award numbers: N00014-23-1-2694 and N00014-22-1-2411) of this work.

References

[1] C. Fear et al., Journal of Energy Storage Materials, 35, 500-511 (2021)

[2] R. Carter et al., Cell Reports Physical Science, 2, 100351 (2021)

[3] T.F. Fuller et al., J. Electrochem. Soc., 141, 1 (1994)

[4] A.M. Colclasure et al.,
J. Electrochem. Soc.,
166, A1412 (2019)

Figure 1
Dual-Salts Electrolyte with Fluoroethylene Carbonate Additive for High-Voltage Li-Metal Batteries
Authors: Qin Zhizhen , Wu Baolin , Danilov Dmitri L. , Eichel Rüdiger A , Notten Peter H.L.
Published: August 2024

The combination of Li-metal anode and high-voltage cathode is regarded as a solution for the next-generation high-energy-density secondary batteries. However, a traditional electrolyte is either incompatible with the lithium-metal anode or vulnerable to high voltage. This work reports a 1 M dual-salts Localized-High-Concentration-Electrolyte with Fluoroethylene carbonate (FEC) additive. It enables stable cycling of Li||LiNi0.8Co0.1Mn0.1O2 (NMC811) battery, which shows 81.5% capacity retention after 300 cycles with a charge/discharge current density of 1 C and a voltage range of 2.7-4.4 V. Scanning electron microscopy (SEM) images show that this electrolyte not only largely reduced Li dendrites and ‘dead’ Li on anode surface but also well protected the microstructure of NMC811 cathode. Possible components of both solid-electrolyte interlayer (SEI) and cathode-electrolyte interlayer (CEI) were characterized by energy-dispersive X-ray spectroscopy (EDX). The result illustrates that FEC protected Li salts from decomposition on the anode side and suppressed the decomposition of solvents on the cathode side.

Figure 1
Design and Preparation of One-Dimensional Cathode By Electrophoretic Deposition Method for Flexible Knitted Batteries
Authors: Zhalgas Nuray , Bakenov Zhumabay , Mentbayeva Almagul , Tatykayev Batukhan
Published: August 2024

Rechargeable batteries are highly promising energy storage systems that can convert and store electrical energy. Effective energy storage systems should have high energy density, high power, safety, environmentally friendliness, and long cycle life. To meet the aforementioned objectives, researchers have attempted to use different morphologies of nanomaterials as electrodes to improve the electrochemical performance of batteries. Among the materials available, one-dimensional structures have unique properties over traditional ones and extensive applications in wearable devices due to their flexibility [1]. Flexible batteries have several advantages such as mechanical flexibility, good energy storage capabilities, affordability, and environmental safety [2]. They knitted or sewed into textiles, folded into random forms, and wrapped around body parts like the neck or wrist [3]. However, there is little research that covers Li-ion batteries that have a one-dimensional flexible structure.

Achieving simultaneous high electronic/ionic conductivity and electrochemical stability is difficult in a homogeneous single-component electrode material. Consequently, the development of precisely defined functional one-dimensional (1D) hetero-nanostructures that effectively integrate the advantages and address the limitations of various electrochemically active materials becomes critical [1].

The proposed methodology involves the electrophoretic deposition of lithium iron phosphate on conductive nickel wire, providing a one-dimensional cathode structure. As an anode, nickel-tin is deposited on nickel wire by electrochemical deposition. The deposition method allows greater precision and control over the deposition of active material on the current collector and also has possible applications on different structures such as 1D and 3D. Also, the electrolyte was obtained by layer-by-layer method, by dipping the cathode and anode, separately, in polymers to coat the cathode material as an electrolyte-separator film. The full cell was assembled and the better results will be presented in the meeting.

Acknowledgments

This research was funded by the Science Committee of the Ministry of Education and Science of the Republic of Kazakhstan (Grant No. АР19679855).

References

[1] L Mai et al., Acc. Chem. Res. 51(2018) 950–959

[2] S. Zhai et al., J. Mater. Chem. A. 9(2021) 26573-26602

[3] K.Wang et al., ACS Applz. Mater. Interfaces. 10(2018) 24573–24582
AI-Powered 3D Image Reconstruction for Analyzing Lithium Ion Battery Microstructures at the Nanoscale
Authors: Kelly Stephen T , Trenikhina Yulia , Harris William
Published: August 2024

A clean energy future will rely heavily on lithium-ion batteries to shift away from carbon-based energy sources. These devices are closed off from the outside world and operate under highly non-ambient conditions (e.g., liquid electrolytes, air-free environments). Their performance is largely driven by the 3D microstructures of the internal components and their evolutions. For example, breached layers in batteries due to lithium dendrite growth can lead to catastrophic failures and safety concerns. As such, imaging the internal microstructures and processes is important for observing and measuring device construction details and understanding how defects are distributed and change performance during operation. In particular, 3D imaging allows for analysis of features and parameters that can only be fully understood in 3D, like porosity and tortuosity, and can also provide realistic microstructural input for 3D modelling and simulation approaches.

Within this scope, X-ray microscopy provides a unique method to image electrochemical devices because of the non-destructive nature of the technique. Modern x-ray microscopes enable 3D imaging even at the nanoscale, bringing capabilities once reserved for the synchrotron into the laboratory. Advances in tomographic image reconstruction have allowed researchers to increasingly maximize the impact of x-ray microscopy data through higher image quality and enabling faster data acquisition schemes. Recently, artificial intelligence (AI) has been incorporated into these algorithms, dramatically increasing the performance and capability of the technique. Here, we apply multiple novel reconstruction technologies that leverage AI to dramatically improve the performance of laboratory-based nanoscale x-ray microscopes, showing examples of improvements in imaging lithium-ion battery electrode materials.

We show how AI-powered tomographic reconstruction can reveal new levels of detail in lithium-ion battery materials and enable up to 10 times faster data collection across the micrometer and nanometer length-scales. These capabilities shift the paradigm in volume analysis for electrochemical devices and give researchers unprecedented insight into the detailed microstructures that drive device performance, enabling new levels of understanding and helping to power the drive to a clean energy future.
A TEM Study of Structural Degradation in LiFePO4 Batteries after Hybrid Vehicle Use
Authors: Ramirez-Meyers Katrina , Dickey Elizabeth C
Published: August 2024

Establishing a robust, efficient circular economy for batteries hinges on understanding how they decay over time under various conditions. This understanding is crucial to maximize material use before recycling or disposal. A key aspect of this endeavor is the study of lithium iron phosphate (LiFePO4), a pivotal battery technology whose structural integrity over time remains a subject of inquiry.1 Known aging mechanisms in LiFePO4 (LFP) batteries include electrode degradation, SEI growth, and electrolyte decomposition.1 These processes extend to the cathode, where degradation can manifest as Fe dissolution, Li inventory loss, Fe/Li anti-site defects, and LFP amorphization.1–3 However, these mechanisms are typically studied in lab-aged cells under controlled conditions, leaving a gap in our understanding of their behavior in real-life, commercialized applications.

Our research aims to bridge this gap by characterizing the degradation mechanisms of LFP cathode material in various states of health (SOH) after use in a hybrid vehicle. We sourced our cathode samples from 26650 cells extracted from a BAE ESS-A123 hybrid bus battery pack. After selecting cells with drastically different SOHs based on previous analyses,4 we employed transmission electron microscopy (TEM) for detailed characterization.

In this talk, we will share insights gained from high-resolution TEM characterization, alongside chemical analysis using energy-filtered TEM and electron energy loss spectroscopy (EELS). Our focus will be on changes in the olivine structure, including lattice parameter alterations, Li and Fe migration, and Fe oxidation. By combining cell-level SOH analyses with TEM characterization, we will highlight how electrochemical test results correlate with material degradation mechanisms, enhancing our understanding of battery health, longevity, and diagnostics.

Wang, L. et al. Insights for understanding multiscale degradation of LiFePO4 cathodes. eScience
2, 125–137 (2022).

Li, X. et al. First Atomic-Scale Insight into Degradation in Lithium Iron Phosphate Cathodes by Transmission Electron Microscopy. J. Phys. Chem. Lett.
11, 4608–4617 (2020).

Xu, P. et al. Efficient Direct Recycling of Lithium-Ion Battery Cathodes by Targeted Healing. Joule
4, 2609–2626 (2020).

Ramirez-Meyers, K., Rawn, B. & Whitacre, J. F. A statistical assessment of the state-of-health of LiFePO4 cells harvested from a hybrid-electric vehicle battery pack. J. Energy Storage
59, 106472 (2023).
Advancements in Alumina Ultrathin Coatings for Enhanced Electrochemical Performance of Ni-Rich NMC811 Thick Electrodes
Authors: Prempluem Surat , Sangsanit Thitiphum , Homlamai Kan , Anansuksawat Nichakarn , Sawangphruk Montree
Published: August 2024

Lithium-ion batteries, renowned for their high energy density, face a significant challenge in the development of stable, high-performing, and cost-effective cathode materials. Ni-rich cathodes, while promising, suffer from instability issues such as microcracking, high surface reactivity, phase transformation, and thermal runaway. This study introduces a breakthrough: the application of an alumina (Al2O3) ultrathin coating to enhance the stability of Ni-rich thick electrodes. The uniform distribution of the Al2O3 coating across the electrode acts as a protective barrier, effectively reducing oxygen lattice release and microcracking. Our findings reveal that this atomic layer deposition (ALD) technique markedly boosts the cycling stability of the electrodes. Coated electrodes maintained high specific capacity after long cycling, significantly outperforming uncoated electrodes, which retained only small capacity. This innovative approach shows great potential for the development of high-performance and stable lithium-ion batteries.

Figure 1
Modifying Li-Rich Cathodes and Investigation into Fully Earth-Abundant Cathode Materials
Authors: Mallick Subhadip , Kwok Chun Yuen , Pollock Christopher , Dixit Marm , Gutierrez Arturo , Balasubramanian Mahalingam , Croy Jason R.
Published: August 2024

The growing demand for electric vehicles and grid storage devices entails the search for materials to further enable these technologies. In this regard, the development of cost-effective, and energy-efficient lithium-ion battery cathodes is of the essence. In recent times, Ni-rich NMC oxides (LiNi
x
Mn
y
Co
z
O2, x+y+z = 1) have emerged as the latest and most advanced materials for use as Li-ion cathodes. However, increasing concerns over sustainability, supply chain issues, and cost-effectiveness of critical elements like Co and Ni have accelerated the search for earth-abundant, Mn and Fe-rich cathode materials.1

Lithium and manganese rich oxide materials (LMR), with general formula xLi2MnO3 • (1-x)LiMO2, can achieve higher energy densities compared to conventional NMC oxides, and thus represent attractive alternatives.2-3 Although issues like voltage fade and hysteresis are concerns with respect to practical application of LMR cathodes and have been well studied, the anomalous increase of area specific impedance (ASI) at low states of charge (SOC), has been comparatively overlooked. This presentation will discuss recent attempts to modify the low SOC ASI behavior of LMR materials by targeted substitution using Sn4+ as an example.

The second part of this presentation will focus on investigations into the synthesis, structure, and electrochemical properties of layered-rock salt composites: xLi2MnO3 • (1-x)LiFeO2. Electrochemical performance of Mn-Fe rich systems is also fundamentally linked to the debated and conflicting theories of oxidation state, local structure, and migration behavior of the Fe3+/4+ red-ox couple. X-ray spectroscopic techniques have been used to address this issue. A composition-structure-property relationship is established within these systems and novel approaches are underway to further improve their electrochemical performance.

References

Communications Materials
2020, 1 (1), 99.

Accounts of Chemical Research
2015, 48 (11), 2813-2821.

Journal of The Electrochemical Society
2023, 170 (3), 030509.
A New High-Valent Fe Redox Couple in Intercalation Electrodes
Authors: Mu Edward Weian , Ramachandran Hari , Lomeli Eder , Braun Augustin , LIU Jue , Jiang Zhelong , Busse Grace , Park Jungjin , Goto Masato , Shimakawa Yuichi , Solomon Edward I. , Yang Wanli , Devereaux Thomas P. , Gent William E. , Chueh William C.
Published: August 2024

The overwhelming majority of layered oxide cathode materials are based on the redox activity of expensive and scarce transition metals like Co and Ni. While the Fe-redox based material LiFePO4 has become increasingly attractive due to its low cost, its low gravimetric energy density and relatively low operating voltage limit its use cases. A high-voltage Fe-based layered oxide cathode would provide high energy density utilizing the redox-activity of the most abundant transition metal in Earth’s crust, but such a material that provides stable and reversible electrochemical performance remains elusive. Indeed, high-voltage Fe-redox in oxides is plagued by cation disorder and oxygen dimerization, which leads to capacity fading and large voltage hysteresis (> 1 V).[1]

In contrast, the layered oxide cathode Li4FeSbO6 (equivalently, Li[Li1/3Fe1/3Sb1/3]O2, abbreviated LFSO) exhibits <0.2 V of hysteresis, and a discharge plateau at 4.2 V versus Li/Li+ with two-electron capacity.[2] Both the exceptional electrochemical reversibility of this material and its phase separating nature upon (de)intercalation raise questions about the origin of these properties that are unusual for layered Fe oxide cathodes. In this work, we will discuss our efforts to probe the electronic structure of LFSO with Fe L–edge x–ray absorption (XAS) and 57Fe Mössbauer spectroscopy, as well as O K–edge resonant inelastic x–ray scattering spectroscopy (RIXS). The combination of these element-specific and valence-state sensitive techniques, in conjunction with charge-transfer multiplet and density functional theory calculations, allows us to reveal the electronic structure changes at Fe and O as a function of state of charge for the first time. Correlating these electronic structure changes with synchrotron diffraction measurements, we reveal a unique redox compensation mechanism that readily rationalizes the exceptional electrochemical reversibility, unlocking a new direction for high-voltage, Fe-based redox systems.

References

[1] Kwok, C. Y. et al.
Chem. Mater.
2023. https://doi.org/10.1021/acs.chemmater.3c02111.

[2] McCalla, E. et al.
J. Am. Chem. Soc.
2015, 137 (14), 4804–4814.
Influence of Carbon Types on the Electrochemical Performance of Disordered Rocksalt Cathodes
Authors: Patil Shripad , Koirala Krishna Prasad , Crafton Matthew J , Yang Guang , Tsai Wan-Yu , McCloskey Bryan D. , Wang Chongmin , Nanda Jagjit , Self Ethan
Published: August 2024

Disordered rocksalt (DRX) materials have recently emerged as a promising class of cobalt-free high-capacity cathodes. However, due to their poor electronic conductivity, they require a high carbon content in the composite cathodes (20-30 wt%) to achieve their full potential, which has a detrimental effect on its cell-level energy density. To assess strategies to mitigate this issue, this study investigates the effect of three types of carbon (Super C65, synthetic graphite, and ketjenblack; chosen based on varying physical properties) and their loadings (10-20 wt%) on the electrochemical performance of DRX cathodes (Patil et al., 2023). Overall, DRX cathodes containing graphite additive demonstrated superior cycling performance (∼260 mA h/g with 85% capacity retention after 50 cycles) and rate capability (∼135 mA h/g at 1000 mA/g) when compared to the traditional carbon blacks. Using a variety of characterization methods such as surface area estimation using BET method, transmission electron microscopy, inductively coupled plasma-optical emission spectroscopy, Raman spectroscopy, and differential electrochemical mass spectrometry, the superior performance of graphite based DRX cathodes is largely attributed to (i) protection of DRX particle surfaces from parasitic reactions owing to a conformal graphitic coating (ii) homogenous distribution of graphite and DRX in the composite electrode providing a robust electronic network. This study provides important insights into how carbon microstructure and processing influences performance of DRX cathodes and paves the path for further development towards reduction of carbon content in composite DRX cathodes.

Reference:

Patil, S., Koirala, K.P., Crafton, M.J., Yang, G., Tsai, W.-Y., McCloskey, B.D., Wang, C., Nanda, J., Self, E.C., 2023. Enhanced Electrochemical Performance of Disordered Rocksalt Cathodes Enabled by a Graphite Conductive Additive. ACS Appl. Mater. Interfaces 15, 39253–39264. https://doi.org/10.1021/acsami.3c05619
(Invited) MAX Phase Oxidation As a Novel Approach to Highly Reversible Oxide Nanocomposite Electrodes for Lithium-Ion Batteries
Authors: Ruffo Riccardo , Ostroman Irene , Vallana Nicholas , Ferrara Chiara , Gentile Antonio , Marchionna Stefano
Published: August 2024

Among the materials utilized for the negative electrodes in Li-ion batteries, there is notable interest in oxides that can undergo reactions with Li+ through processes like intercalation, conversion, or alloying. These oxides exhibit high specific capacities but face challenges related to inadequate mechanical stability. A novel approach to constructing nanocomposites involves the partial oxidation of the tin-containing MAX phase within the Ti3Al(1-x)SnxO2 composition. By employing this strategy, and optimizing the Sn amount and the oxidation process, we have developed composite electrodes comprising Sn/TiOx and MAX phase, demonstrating exceptional durability with over 600 cycles in half cells. These electrodes exhibit charge efficiencies exceeding 99.5% and specific capacities comparable to graphite, surpassing those of lithium titanate (Li4Ti5O12) or MXene-based electrodes. These remarkable electrochemical performances extend to full cell configurations when combined with a low cobalt content layered oxide. The success of these electrodes is elucidated through a thorough chemical, morphological, and structural investigation, revealing the intimate contact between the MAX phase and oxide particles. Throughout the oxidation process, electroactive nanoparticles of TiO2 and Ti(1-y)SnyO2 emerge on the surface of the unreacted MAX phase, which serves both as a conductive agent and a buffer to maintain the mechanical integrity of the oxide during lithiation and de-lithiation cycles.
Fundamental Understanding of Halide Solid Electrolytes for All-Solid-State Batteries
Authors: Yang Shuhao , Chen Guoying
Published: August 2024

Due to their superior oxidative stability, high ionic conductivity and excellent chemical compatibility with uncoated 4 V-class cathode active materials, halide compounds, particularly those with a general formula of Li3MCl6 (M = Sc, Zr, In, Y, Er, and Yb etc.), have attracted much attention as solid electrolytes (SEs) for all-solid-state batteries (ASSBs).1,2 While a great deal of effort has been devoted to the discovery of new halide SEs,3–5 fundamental understanding of their properties, such as the mechanism of ionic conductivity, chemical stability, and the interfacial reactivities at the cathode and the anode are still lacking. Here we use Li3YCl6 (LYC) as an example to investigate the key parameters that impact their performances in ASSBs. Hopping frequency analysis is used to understand how synthesis methods and chemical compositions affect mobile carrier concentration and ionic conductivity in the Li–Y–Cl series.6 Synchrotron X-ray absorption (XAS) and diffraction (XRD) are used to investigate electrochemical and interfacial chemistry of LYC in full ASSB cells with an uncoated nickel-rich cathode, a Li metal anode or a lithium-metal alloy anode. Our strategies in developing halide SEs for higher capacity and high energy density ASSBs will be presented.

References:

(1) Manthiram, A.; Yu, X.; Wang, S. Lithium battery chemistries enabled by solid-state electrolytes. Nat. Rev. Mater.
2017, 2, 16103.

(2) Janek, J.; Zeier, W. G.; Challenges in speeding up solid-state battery development. Nat. Energy
2023, 8, 230−240.

(3) Combs, S. R.; Todd, P. K.; Gorai, P.; Maughan, A. E. Designing defects and diffusion through substitutions in metal halide solid electrolytes. J. Electrochem. Soc.
2022, 169, 040551.

(4) Kwak, H.; Wang, S.; Park, J.; Liu, Y.; Kim, K. T.; Choi, Y.; Mo, Y.; Jung, Y. S. Emerging halide superionic conductors for all-solid-state batteries: design, synthesis, and practical applications. ACS Energy Lett.
2022, 7, 1776–1805.

(5) Wang, C.; Liang, J.; Kim, J. T.; Sun, X. Prospects of halide-based all-solid-state batteries: from material design to practical application. Sci. Adv.
2022, 8, eadc9516.

(6) Yang, S.; Kim, S. Y.; Chen, G. Halide superionic conductors for all-solid-state batteries: effects of synthesis and composition on lithium-ion conductivity. Submitted.
(Invited) Nanosecond Electrical Discharges in Liquids: Applications in the Synthesis of Nanoparticles, Including Nanoalloys
Authors: Hamdan Ahmad
Published: August 2024

In recent decades, the field of nanotechnology has witnessed rapid growth, fueled by the exceptional physical, chemical, mechanical, and electrical properties of nanoscale materials. Nanomaterials have found applications across various domains, including catalysis, drug delivery, microelectronics, and more. Notably, plasma-based methods have emerged as promising avenues for nanomaterial synthesis, offering versatile approaches through both bottom-up and top-down techniques.

One particularly innovative area of research is the plasma-liquid system, which has demonstrated remarkable efficiency in nanomaterial synthesis. This system involves the generation of plasma in a gas phase in contact with a liquid or directly within the liquid, sometimes aided by the introduction of bubbles. This communication has two goals: 1) present an overview of the physics of different discharge mechanisms, with a particular focus on the intriguing phenomena occurring at the interfaces, and 2) show different cases where nanomaterials of interest are produced. For instance, we will show that in-liquid spark discharges prouce nanoparticles through electrode erosion, and notably, the properties of these materials are highly sensitive to both the nature of the electrode and the composition of the liquid. In the second part, we introduce an innovative plasma-liquid system where a discharge can be produced at or close the interface of two immiscible liquids. In specific cases where the system is composed of a conductive solution (e.g. salty water) and a hydrocarbon liquid, spark discharges can be generated between a pin in liquid hydrocarbon and the surface of the conductive solution. This unique configuration facilitates therefore an interaction between a high-density plasma (generated in liquid) and a solution containing metal ions. At this stage, many reactions may occur and lead to the reduction of ions to produce nanomaterials. We found that the particles collected from hydrocarbon liquid are different from those collected from the solution, in terms of composition and size distribution. This finding suggests the triggering of different chemical reactions in each liquid, involving thus species with short- as well as long-lifetime species. Consequently, we adopted this approach to synthesize metal nanoparticles as well as binary and ternary nanoalloys, expanding the scope of possibilities in nanomaterial synthesis.
(Invited) Mixing Elements in 2D Nanostructures Grown by Discharges in Liquids
Authors: Nomine A.V. , Gries Thomas , Noël Cédric , Ghanbaja Jaafar , Bruyère Stéphanie , Nominé Alexandre , Milichko Valentin , Belmonte Thierry
Published: August 2024

The synthesis of nanosheets through discharges in liquid nitrogen is observed for certain metals when employed as electrodes [1,2]. Various metals have been examined, with bismuth, lead, or zinc showing a propensity to form nanosheets. Other metals, such as silver or indium, also exhibit sheet formation but with smaller aspect ratios (width/thickness). Mixing metals is not only interesting to create alloys with new properties but also to understand how discharges work to enable the synthesis of these objects.

Recently, we demonstrated that these structures can be grown not only in liquid nitrogen but also in water. This is attributed to the discharge primarily originating from the metallic vapor emitted by the electrodes, a consistent process in both liquids, as confirmed by time-resolved optical emission spectroscopy.

We showcased that a pre-treatment, involving chemical etching by a Nital solution, significantly enhances the efficiency of nanosheet production, increasing it from almost zero to nearly 100%. We successfully identified the growth mechanism of nanosheets in the case of bismuth electrodes. These structures grow on the cathode with ion assistance, collecting in the bubble formed during the discharge. Upon the collapse of the bubble, they transfer into the liquid phase. Interestingly, the number density of nanoparticles produced under these conditions is either null or too weak to be evaluated.

It is feasible to incorporate two different elements into 2D nanostructures by utilizing two electrodes. We achieved a mixture of lead and bismuth oxide by using electrodes composed of the respective elements. This capability is likely associated with the similar melting points and miscibility of both elements. Nanosheets exhibit thicknesses around 5-10 nm for widths ranging in the tens of micrometers.

We anticipate that a more comprehensive understanding of the synthesis of these alloys will pave the way for the production of alloyed nanosheets incorporating other elements.

[1] A. Hamdan, H. Kabbara, C. Noël, J. Ghanbaja, A. Redjaimia, T. Belmonte, “Synthesis of two-dimensional lead sheets by spark discharge in liquid nitrogen”, Particuology 40 (2018) 152–159

[2] H. Kabbara, J. Ghanbaja, C. Noël, T. Belmonte, “Nano-objects synthesized from Cu, Ag and Cu28Ag72 electrodes by submerged discharges in liquid nitrogen”, Materials Chemistry and Physics 217 (2018) 371–378
Atmospheric Pressure Plasma Treatment of Glass Surface and Its Influence on the Reliability of Adhesive Bonding
Authors: Kelar Tucekova Zlata , Kelar Jakub , Brodňanský Dávid , Fleischer Michal , Černák Mirko , Boutar Yasmina , Zikmundová Marketa , Sokol Zdeněk , Eliášová Martina
Published: August 2024

Glass load-bearing structural elements are currently used more often in civil engineering. However, due to the brittle fracture of glass, it is necessary to design these structures with sufficient reliability. Adhesive joints have a number of advantages over mechanical connectors of glass commonly used in construction. Adhesives can eliminate thermal bridges and provide a more uniform stress distribution along the connection without weakening the bonded material.

A variety of chemical methods have been developed for cleaning and activating glass surfaces prior to adhesive bonding. Recently, these methods have been substituted by glass surface cleaning and activation using ambient (humid) air plasma. Such an approach is considered much faster, technically simpler, and more environmentally friendly than the traditional chemical methods. For example, it eliminates the need for the so-called primer interlayer, where the primer is usually considered a heavy chemical with significant environmental impact.

The presented work is focused on the surface activation of glass by atmospheric pressure plasma to improve adhesion using specially selected transparent adhesives. We studied Diffuse Coplanar Surface Barrier Discharge (DCSBD) plasma treatment of different float-glass, heat-treated and tempered glass surfaces in ambient air. The DCSBD plasma effect was evaluated by surface free energy and peel-test adhesion measurements. The morphological changes on the glass surface were investigated by scanning electron and atomic force microscopy. The glass-to-glass adhesion at elevated temperatures was tested with respect to the artificial ageing of adhesive bonding due to the environment.

Acknowledgement: This research was supported by project LM2023039, funded by the Ministry of Education, Youth and Sports of the Czech Republic and supported by project No. GA23-06016S, funded by the Czech Science Foundation (GAČR).
Energy Efficiency of Steady DC and Half Sine Pulsed DC in the High Voltage Pre-Plasma and Plasma Alkaline Water Electrolysis
Authors: Nehra Raviraj SINGH , Kumar Ankit , Lakesar Shyam Sunder , Rajeev KP , Pala Raj Ganesh
Published: August 2024

The research addresses the contrasting views on the energy efficiency of alkaline water electrolysis using the regular DC vs the pulsed DC. We compare the high voltage steady DC electrolysis with the high voltage half-wave rectified (HWR) AC (or the half Sine pulsed DC, an unexplored form of the pulsed DC) across a wide range of voltage regimes, with a particular focus on the less explored Plasma electrolysis (PE) regime. In addition, the current-voltage characteristics are mapped across the voltage regimes (NE to PE) using a novel high-voltage 3-electrode circuit, which allows better control over the working electrode potential. The experimental design considers critical parameters such as energy efficiency, Faradaic efficiency, and current density, providing a comprehensive evaluation of the regular DC Vs. the half-wave rectified AC electrolysis.

Pulsed electrolysis can facilitate bubble removal and ensure timely replenishment of reactant during the low-bias phase and this is expected to diminish over potential losses due to mass transfer resistance. However, the preliminary energy efficiency assessment suggests that the regular DC is ~13% higher at 33 V bias and ~24% higher at 26.5 V bias than the half sine pulsed DC(50 Hz) electrolysis. This suggests that for these particular reaction conditions, the fluctuations in the current leading to reactive losses in the circuit and other internal losses overwhelm any enhancement in the mass transfer characteristic of pulsed electrolysis. The study also points to regimes where significant thermal decomposition results in a significant increase in the apparent Faradaic efficiency.
Electrocatalytic Conversion of Plasma-Activated CO2 Toward Multicarbon Products
Authors: Kim Ji-Yong , Anderson Kelby , Park Andy , Simon Julia , Winter Lea R
Published: August 2024

Renewable electricity-powered CO2 reduction reaction (CO2RR) toward chemicals and fuels has been gaining significant attention not only for achieving net-zero carbon emissions but also for enabling long-term energy storage. In electrochemical conversion, CO2 can be upgraded into single- or multicarbon products such as carbon monoxide, formate, and ethylene with remarkable selectivity. However, challenges still exist in terms of high overpotential, limited product range, and low production rates. Moreover, most reported CO2RR to multicarbon products which used Cu as catalysts have predominantly generated C2 products like ethylene or ethanol. However these systems require further performance improvement to target C3+ products which have higher energy density and market price. Another electrified conversion technique involves non-thermal plasma, which can activate CO2 into radical, ionized, and vibrationally excited species at atmospheric pressure and near-ambient temperature. However, plasma processes are non-selective, which poses limitations for controlling reaction pathways and necessitates H2 or light alkanes as co-reactants to produce hydrocarbons.

We synergized plasma and electrocatalytic conversion to demonstrate a combined CO2RR process that overcomes the limitations of each individual method. Through the integration of a dielectric barrier discharge plasma and an electrochemical flow reactor, pre-activated CO2 was electrochemically converted on a Cu electrode to produce multicarbon products. The combination enhanced the faradaic efficiency and reaction rate of desirable products and opened new reaction pathways by increasing the activity of CO2 prior to adsorption. The production rates of ethanol, propanol, and acetaldehyde were significantly increased, and new products such as methanol, acetylene, and ethane that were formed only in the combined reaction were detected. The product distribution was studied according to plasma-activated states of CO2 and the electrochemical applied potential. To elucidate the synergistic effects in the combined system, the selectivity and production rates were compared with those in the plasma-only and electrochemical-only reactions. Further control experiments using ground-state reactants were conducted, and the excited states during plasma activation were identified by optical electron spectroscopy. This work represents not only electrocatalysis of pre-activated reactants for enhanced generation of multicarbon products during electrified conversion of CO2, but also demonstrates synergistic convergence of plasma and electrocatalysis for converting reactants possessing strong chemical bonds.
Towards a Mechanistic Understanding of Transition-Metal Dissolution Phenomenon in Lithium-Ion Batteries
Authors: Sahore Ritu , Unocic Raymond R , Dixit Marm , Li Mengya , Andrews Hunter , Manard Benjamin
Published: August 2024

Dissolution of transition metals (TMs) from the layered NMC-type cathodes (LiNixMnyCozO2) occurs during cycling of lithium-ion full cells and is known to accelerate their capacity fade. This is because the dissolved metals migrate to the graphite anode and deposit there, where they accelerate irreversible active-lithium loss to reductive side reactions. The dissolution is known to get aggravated by cycling the cells to a greater upper cut-off voltage (UCV), where larger amounts of metals are typically found to be accumulated at the anode after long term cycling. At higher UCV oxygen loss from the cathode lattice also gets accelerated causing changes in the layered crystal structure at the surface level to a rock-salt and spinel mixture which has a very high impedance for Li-ion transport. Several other phenomena get accelerated as well, such as proton generation, and solvent decomposition etc. However, a complete mechanistic understanding of the how these phenomena impact the TM dissolution is lacking. For example, it is unclear whether the dissolution can occur in the charged state when the metals are in the oxidized state despite the presence of large number of acidic species, especially since most of the dissolved metal species typically detected in the electrolyte are in lower oxidation state. In this study, this question was targeted by aging the full graphite//NMC cells via long potentiostatic holds at UCV with/without any discharge steps, and recording the dissolved metals deposited at the graphite after aging. It is shown that a much greater amounts are deposited at the anode when discharge steps are included. Atomic structural changes from TM dissolution at the cathode surface corresponding to the two aging protocols in the charged/discharged state will also be presented.

This work was supported by the Assistant Secretary for Energy Efficiency and Renewable Energy, Office of Vehicle Technologies of the U.S. Department of Energy (DOE) through Cathode-Electrolyte Interphase (CEI) Consortium. Part of the measurements was performed at the Center for Nanophase Materials Sciences (CNMS), which is sponsored at Oak Ridge National Laboratory by the Scientific User Facilities Division, Office of Basic Energy Sciences.
When and Where Lithium Plating Occurs, Its Correlation with Microstructure Heterogeneity, and the Mechanisms That Initiate and Self-Regulate Electrochemical Heterogeneity
Authors: Usseglio-Viretta Francois L. E. , Colclasure Andrew M. , Allen Jeffery M. , Finegan Donal P. , Graf Peter , Smith Kandler
Published: August 2024

A microstructure scale electrochemical LIB model was used to investigate lithium plating onset, material non-uniform utilization, and in-plane heterogeneities for an NMC-graphite full cell [1]. Model predicts active material particle surface roughness and size distribution (respectively, non-uniform curvature within and between particles) initiate in-plane heterogeneity, and that particle size heterogeneity at the separator interface controls the lithium plating preferential deposition (“Where”). These in-plane heterogeneities are then exacerbated by through-plane heterogeneities induced at fast charge as electrolyte depletion occurs and concentrates intercalation reaction near the anode-separator interface. Also, overall magnitude and occurrence of lithium plating is controlled by effective, or macroscale, microstructure parameters (“When”).

As local states of charge start to diverge between nearby active material regions, overpotential differences induced by OCP difference kick in and contribute to reduce these SOC local heterogeneities. However, for staged materials such as graphite, with OCP profile alternating between plateaus and varying regions, this balancing mechanism is, respectively, inactive and active. This leads to a dynamic, non-monotonic, in-plane heterogeneity time evolution for state of charge and Faraday current density, for which their respective in-plane heterogeneity magnitude alternates. Such behavior has been modeled both for the whole electrode at the microstructure scale and at the particle scale. In-plane heterogeneities are usually considered to be detrimental, as they result in material non-uniform utilization (i.e., under and over stressed regions) and earlier degradations. However, this work provides a more granular approach as it discriminates between a harmful in-plane heterogeneity (non-uniform curvature) that triggers SOC in-plane heterogeneity, and a beneficial in-plane heterogeneity (Faraday current density) that contributes to reduce SOC in-plane heterogeneity.

This work comprehensively explains the mechanisms that initiate, exacerbate, and regulate heterogeneity at the microstructure scale, while providing some design suggestions to reduce both in-plane and through-plane heterogeneities, as summarized in the graphical abstract.

[1] F. L. E. Usseglio-Viretta, A. M. Colclasure, J. Allen, D. P. Finegan, P. Graf, and K. Smith, Microstructure Scale Lithium-ion Battery Modeling, Part I: on lithium plating prediction and heterogeneity, in preparation.

Figure 1