bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effect of Short-Chain Polymer Binders on Mechanical and Electrochemical Performance of Silicon Anodes
Authors: Sun Fei , Zurita Lizbeth , Wheeler Dean 
Published: December 2024

Polymer binders are crucial components in providing both mechanical support and chemical stability to the structure of porous Li-ion electrodes. Particularly in silicon anodes, active material undergoes substantial volume expansion of up to 280%. As is shown in Figure 1, due to the restriction of the current collector, these silicon materials tend to expand vertically and so this requires substantial rearrangement of particles and plastic deformation.
However, conventional binders such as polyacrylic acid (PAA) and polyimide (PI), while providing satisfactory initial capacity, suffer from mechanical rigidity due to their long polymer chains, leading to diminished long-term performance.
Our research attempts to address this limitation by exploring the use of short-chain polymer binders, which may offer improved flexibility to accommodate the substantial volume changes of silicon particles. Although our previous work indicated that shorter polymer chains might compromise the adhesion to the copper current collector, we have developed a multilayer anode (MLA) structure featuring an adhesion layer to mitigate this issue. As is shown in Figure 2, this adhesion layer, placed between the silicon-containing bulk layer and the copper current collector, is designed to enhance the interface stability without sacrificing the mechanical compliance provided by short-chain polymers.
Our experiments demonstrate that cells combining both long and short-chain PAA binders outperformed those with conventional PAA alone, delivering initial capacity of 2200 mAh/g at a 0.1C rate, compared to 1700 mAh/g for pristine PAA cells. At the early stages of development of the MLA-style anode with an adhesion layer, there was not an observed increase in performance, though experiments are ongoing, and we will report on latest results.
We believe that the introduction of a strategic blend of different molecular weight binders can offer a promising solution to some of the challenges faced by silicon-based anodes.

Figure 1
Stretchable Li Ion Battery Electrodes Using Ga-Based Liquid Metal and Ionic Liquids
Authors: Fujimoto Hikaru , Usami Natsuka , Kanto Moeka , Ota Hiroki , Watanabe Masayoshi , Ueno Kazuhide 
Published: December 2024

Liquid metal has low melting point, high thermal and electronic conductivity, and fluidity. In addition to having above properties, eutectic gallium-indium (Ga-In) are characterized by low volatility and low toxicity compared to a typical liquid metal such as Hg1). Ionic liquids have attracted considerable attention owing to unique properties such as high ionic conductivity, low volatility, and thermal stability. In previous works, we reported ion gels, composed of polymer networks swollen with ionic liquid, as highly ion-conducting, self-standing and flexible gel electrolytes 2). In this study, to prepare a stretchable electrode having high electronic and ionic conductivity as well as high stretchability and flexibility, we combine liquid metal Ga-In and Li4Ti5O12 (LTO) with the ion gel. Ga-In is expected to function as a “deformable current collector” while LTO serves as the active material in a stretchable electrode. This composite stretchable electrode (metal gel electrode3)) has a potential to be used for stretchable Li ion batteries in wearable devices. To meet the requirements of stretchable batteries used in the wearable devices, we studied effects of ionic liquid and polymer structures on the electrochemical properties and stretchable properties of the prepared metal gel electrodes.

Acknowledgements

This study was supported in part by Core Research for Evolutionary Science and Technology (CREST) of the Japan Science and Technology Agency (JST).

References

1) N. Kazem, et al, Adv. Mater., 2017, 29, 1-14.
2) M. A. B. H. Susan, et al, J. Am. Chem. Soc., 2005, 127, 4976.
3) J. Asada, et al, Macromol. Chem. Phys., 2021, 223, 2100319.
Evaluation and Regulation of Interfacial Reaction of Cathode for Lithium-Sulfur Batteries to Improve Electrochemical Performance
Authors: Lee Seungmin , Hu Enyuan 
Published: December 2024

In the pursuit of high-energy-density batteries, sulfur (S)-based materials have emerged as promising cathode materials due to high-capacity (1,672 mAh g-1 for lithium-sulfur) [1]. However, their degradation caused by the dissolution of reaction intermediates during electrochemical cycling, has led to diminished electrochemical performance. To address this issue, various surface treatments, including the formation of chemical/physical protective layers and doping with heteroatoms, have been explored [1-2]. Despite these efforts, real-time evaluation of the degradation and the effectiveness of such surface modifications on electrochemical performance remains challenging due to the difficulty in distinguishing between degradation and electrochemical reactions.
In this context, our aim is to evaluate the degradation of high-capacity S-based cathodes using electrochemical techniques in real-time. Specifically, we distinguish the chemical reactions from the electrochemical reactions based on the numerical analysis and further quantify the degradation. Furthermore, we apply our evaluation method to assess the effectiveness of surface treatments on electrode materials.

References

[1] S. Lee, K. Eom et al., Electrochimica Acta, 2022, 412, 140092
[2] S. Lee, K. Eom et al., Journal of Power Sources, 2023, 582, 233517
Accelerating the Electrochemical Formation of the δ Phase in Manganese-Rich Rocksalt Cathodes
Authors: Holstun Tucker , Mishra Tara , Huang Liliang , Yang Xiaochen , Ceder Gerbrand 
Published: December 2024

Recently, advancements in Mn-based disordered rocksalt (DRX) cathodes have demonstrated not only high energy density but also an electrochemical transformation to a spinel-like phase, now referred to as the δ phase1,2,3. The δ phase possesses a unique domain structure, a flattened voltage profile and improved rate capability. However, two important challenges remain: the necessity to mill the material to reduce particle size after synthesis, and the prolonged cycling required to complete the transformation to spinel-like partial order. To address these challenges, we present the development of an electrochemical formation method that enables rapid and in-situ formation of this partially disordered spinel phase from a DRX cathode, including in micron-sized single crystals.
To gain a deeper understanding of this transformation process, we carry out a systematic study to determine whether the transformation to the δ phase can be accelerated through a precycling formation process. By employing this novel electrochemical approach to purposefully stimulate the transformation, we successfully reduce the time required from several weeks to as little as one day for Mn-rich DRX. Extended cycling and synchrotron X-ray diffraction confirm that these materials exhibit both equivalent performance and resulting structure to those obtained through conventional cycling over a much longer duration. Further characterization of this material using HAADF and 4-D STEM reveals the complex local structure of the spinel-like partial ordering. It is hoped that such a practical electrochemical formation method allows for an acceleration of research on these earth-abundant and energy-dense materials.

Li, L.; Lun, Z.; Chen, D.; Yue, Y.; Tong, W.; Chen, G.; Ceder, G.; Wang, C. Fluorination-Enhanced Surface Stability of Cation-Disordered Rocksalt Cathodes for Li-Ion Batteries. Adv Funct Mater 2021, 31 (25), 2101888. https://doi.org/10.1002/adfm.202101888.

Ahn, J.; Giovine, R.; Wu, V. C.; Koirala, K. P.; Wang, C.; Clément, R. J.; Chen, G. Ultrahigh-Capacity Rocksalt Cathodes Enabled by Cycling-Activated Structural Changes. Adv. Energy Mater. 2023. https://doi.org/10.1002/aenm.202300221.

Cai, Z.; Ouyang, B.; Hau, H.-M.; Chen, T.; Giovine, R.; Koirala, K. P.; Li, L.; Ji, H.; Ha, Y.; Sun, Y.; Huang, J.; Chen, Y.; Wu, V.; Yang, W.; Wang, C.; Clément, R. J.; Lun, Z.; Ceder, G. In Situ Formed Partially Disordered Phases as Earth-Abundant Mn-Rich Cathode Materials. Nat. Energy 2023, 1–10. https://doi.org/10.1038/s41560-023-01375-9.
Solubility-Enhanced Iron Complex Posolytes for Redox Flow Batteries
Authors: Okazawa Atsushi , Kakuchi Takayuki , Akahori Keisuke , Kawai Kosuke , Okubo Masashi 
Published: December 2024

Redox flow batteries (RFBs) are promising stationary energy storage devices for renewables. Commercial RFBs possess potential disadvantages such as cost and resource constraint due to the use of vanadium. Therefore, organic compounds and metal coordination complexes have drawn much attention as redox active materials for RFB electrolytes. We focus on less expensive terpyridine iron complexes that have higher redox potential of approximately 1 V (vs. SHE) as an active material for both aqueous and non-aqueous RFB posolytes.[1] However, terpyridine iron complexes generally possess low solubility in nonaqueous and aqueous solvents. In this study, we improved the solubility of the complexes by multi-componentization based on asymmerizing molecular structures and using the diverse ion effect as shown in Figure 1, and then explored an application as active materials in posolytes.
Symmetric terpyridine-iron complexes, [Fe(R-tpy)2](PF6)2 (R-tpy: substituted terpyridine ligand), were synthesized by simple mixing with R-tpy ligands and an iron source in high yields of 96-98%. Cyclic voltammogram of a butoxy-substituted complex, [Fe(BuOtpy)2]2+ (1BuO), shows redox potentials of 0.57 V (vs Fc/Fc+) in CH3CN. The Fe2+/Fe3+ redox couple shifts to a higher potential compared to 0.72 V (vs Fc/Fc+) for the parent complex, [Fe(tpy)2]2+ (1H), because of the electron-donating substituent on the ligand. The solubility of 1BuO·(PF6)2 in CH3CN was estimated as 0.13 M by a UV-Vis method using a calibration curve, which is comparable to that of 1H·(PF6)2 (0.16 M). Such a low solubility of 1BuO·(PF6)2 is due to a stronger lattice energy derived from a tight packing between the iron complex cations and PF6
−. The mixing of 1H and 1BuO produced a mixture containing a new asymmetric complex [Fe(BuOtpy)(tpy)]2+. The solubility of the mixture increased to 0.49 M, which enhances a theoretical volumetric capacity of posolytes three times than those of the single-component ones (Figure 2). Further solubility improvement was achieved using complexes substituted with poly(ethylene glycol)-type chains.

Reference

[1] A. Okazawa, T. Kakuchi, M. Okubo, APL Mater.
11, 110901 (2023).

Figure 1
Investigation of Hydrogen Isotope Conductivity through Single- and Multi-Layer Graphene
Authors: Temme Robert , Abel Bernd 
Published: December 2024

Since its discovery, the outstanding properties of graphene regarding electrical and thermal conductivity as well as mechanical stability have increased the interest of the scientific community in this versatile material. The intensive investigations on the material uncovered even more unique properties that were previously thought to be physically impossible. In 2014 Hu et al. had shown that pristine graphene, which was prior thought to be an impermeable barrier, could be penetrated by ions.[1] Especially ions of hydrogen isotopes seem to be able to penetrate graphene at a fast rate. This permeation is supposed to cause a separation where protium passes more easily than the other isotopes which is still thoroughly discussed in recent literature. Contrary to single layer graphene, the permeability through multiple layers of graphene as an A-B-stacking seems to be less discussed nor investigated. Theoretical calculations of Eren et al. proposed a possible and fast interstitial movement of ions through multi-layered 2D-materials.[2] Within this work we were able to prove that in fact, several layers of graphene could be penetrated by protons and deuterons. By utilizing impedance spectroscopy, it was possible to show that the ions pass through the graphene layers. The currents produced in this electrochemical ion pump exceeded 500 mA/cm2 and showed that the graphene added almost no additional resistance. Combining impedance spectroscopy with mass spectrometry, we were also able to analyze whether isotope separation occurred for protons and deuterons. With electrochemical measurements we validated conduction of ions through graphene but were unable to find any separation. Therefore, our results are challenging a lot of recent results in this field.
References:
[1]- Hu, S., Lozada-Hidalgo, M., Wang, F. et al. Proton transport through one-atom-thick crystals. Nature 516, 227–230 (2014). doi.org/10.1038/nature14015
[2]- Eren, Ismail, Yun An, and Agnieszka B. Kuc. "Hydrogen Transport Between Layers of Transition Metal‐Dichalcogenides." Advanced Materials Interfaces 11.4 (2024): doi.org/10.1002/-admi.202300798
Improving Corrosion Resistance By Anodizing of Aluminum Vapor-Deposited Magnesium
Authors: Araki Takuma , Tomita Shunsuke , Kikuchi Tatsuya 
Published: December 2024

Magnesium can be widely available in various engineering applications, such as electronic components and vehicles, due to their light weight and high specific strength. However, magnesium easily corrodes in our environments, thus surface finishing is very important for improving corrosion resistance of magnesium. Although plasma electrolytic oxidation (PEO) is widely used for the corrosion protection of magnesium, this method requires higher voltages more than 200-300 V. In the present investigation, we describe a novel corrosion protection method of magnesium via vacuum vapor deposition of thin aluminum and subsequent anodizing.
Commercially available 99.95 wt% magnesium plates were electrochemically polished in a 0.5 M NaCl/diethylene glycol solution (308 K) at 75 V for 3 min. After electropolishing, a thin aluminum layer measuring up to 2 µm in thickness was coated onto the magnesium specimens by vacuum deposition. The aluminum-deposited magnesium specimens were anodized in a 0.3 M oxalic acid solution at a constant current of 30 Am-2 for up to 60 min to form anodic porous alumina. Finally, the anodized specimens were immersed in boiling water for 15 min to seal the pores. The surface and cross-section of the anodized specimens were examined by optical microscopy (OM) and scanning electron microscopy (SEM).
Figure 1 shows the voltage-time curves of the aluminum-deposited magnesium specimens during constant current anodizing in a 0.3 M oxalic acid solution at 30 Am-2. Here, the thickness of aluminum layer was adjusted to a) δ = 100 nm, b) 500 nm, c) 1 µm, and d) 2 µm. In the case of thinner aluminum thickness such as 100 nm and 500 nm, the voltages exhibit an almost steady value, and the dissolution of the bottom magnesium substrate was observed by SEM observations. This is due to the presence of microdefects reaching the magnesium substrate in the thin aluminum film. On the other hand, the voltages increase to approximately 30-35 V during anodizing using thick aluminum layer-deposited specimens, and an anodic porous alumina was formed. However, the voltage drastically decreased, and the magnesium substrate dissolved. Consequently, a corrosion-resistant porous alumina film could be successfully formed on the magnesium specimen by choosing the appropriate anodizing time.

Figure 1
High-Speed Manufacturing(<1 min) of Ultra-Thin Lithium Metal Anode for Safe and High-Energy Battery
Authors: Kim Jueun , Park Minjoon 
Published: December 2024

Lithium metal batteries (LMB) are gaining attention as next-generation batteries due to their unique high energy density and high output. However, practical difficulties in the commercialization of lithium metal anodes (LMA) persist due to several inherent challenges. Conventional methods for manufacturing lithium metal anodes, such as the physical rolling of lithium metal onto copper foil, have limitations in achieving sufficiently thin lithium layers due to the resistivity of copper foil. LMA thicker than 30 μm lead to a high N/P ratio in batteries, resulting in lithium wastage and the formation of uneven solid electrolyte interphase (SEI) layers during cycling, which increase dead lithium and degrade battery performance.
As an alternative, we propose a strategy to drastically reduce the manufacturing time of lithium metal anodes while forming a stable interface. By applying optimized pressure tailored for the pouch cell used during lithium electroplating, we reduce the lithium-ion diffusion distance and ensure uniform contact between the lithium deposition target and the lithium source. Simultaneously, optimizing the temperature increases lithium ion mobility, mitigating concentration gradients within the cell during reactions and minimizing the imbalance of electric fields at the electrode surface. Consequently, electrodeposition occurs with low nucleation overpotential, forming stable lithium nuclei, and enabling smooth subsequent fast deposition reactions. We confirmed the feasibility of increasing the current density up to a maximum of 400 mA cm⁻², approximately 400 times higher than values reported in previous literature, with a deposition time of 36 seconds for the formation of 4 mAh cm⁻². Using this strategy, LMA deposited at 60 mA cm⁻² for 4 minutes, assembled with lithium iron phosphate (LFP), demonstrated stable cell performance over 170 cycles.
Furthermore, to enhance the cycling reversibility of lithium metal electrodes, we coated copper foil with lithiophilic Silicon Nitride (SN) layers. By depositing lithium on SN-coated Cu foil under controlled temperature and pressure, we observed reduced nucleation overpotential, dramatic increases in the size of lithium grain boundaries, and decreased porosity. Increased grain boundary size reduces contact with the electrolyte, thereby reducing side reactions and enhancing cell cycle stability. We performed coulombic efficiency (CE) tests to evaluate the reversibility of lithium on SN@Cu, demonstrating stable operation at 3 mA cm⁻² for 200 cycles. Additionally, symmetrical cell tests conducted at a current density of 1 mA cm⁻² and a capacity of 1 mAh cm⁻² exhibited further improved performance for over 400 cycles. Based on these two strategies, we anticipate practical applications in LMBs.

Figure 1
Oxidation of Ni Foil at 873K between Ar-1%O2 and Ar-5%H2 Gas Atmospheres
Authors: Kawamura Kenichi , Inoue Soichiro , Koinuma Yudai , Namba Ken 
Published: December 2024

The thickness of the thermally grown oxide scale estimated from the diffusion coefficient is thinner than the experimental thickness. The reasons for this have been proposed to be the effects of grain boundaries, which are high-speed diffusion paths for oxide films, and the effects of cracks, but these have not yet been quantitatively addressed. In this study, we attempted to quantify physical defects such as cracks and pinholes in the oxide film.
One side of the Ni foil (100 μm thick) was oxidized with Ar-1%O2 and the other side was exposed with Ar-5%H2 at 873 K. At this time, the hydrogen that permeated through the Ni foil was converted into water and quantified using a dew point meter.
In single Ar-1%O2 atmosphere, the oxide film grew according to the parabolic law. On the other hand, when oxidizing one side with Ar-5%H2, not only the film growth was suppressed, but the scale thickness became almost constant after 500 ks. The amount of hydrogen permeation was almost unchanged depending on the presence or absence of the oxide film, indicating that the oxide scale contains physical defects that allow hydrogen to permeate.
Critical Roles of pH and Activated Carbon on the Speciation and Performance of an Archetypal Organometallic Complex for Aqueous Redox Flow Batteries
Authors: Holubowitch Nicolas , Burghoff Alexis 
Published: December 2024

A lack of suitable high-potential catholytes (posolytes) hinders the development of aqueous redox flow batteries (RFBs) for large-scale energy storage. Hydrolysis of the charged (oxidized) catholyte typically occurs when its redox potential approaches that of water, with a negative impact on battery performance. Here we elucidate and address such behavior for a representative iron-based organometallic complex, showing that the associated voltage and capacity losses can be curtailed by several simple means.1 We discovered that addition of activated carbon cloth (ACC) to the reservoir of low-cost, high-potential [Fe(bpy)3]2+/3+ catholyte-limited aqueous redox flow batteries (Fig. 1) extends their lifetime and boosts discharge voltage – two typically orthogonal performance metrics. Similar effects are observed when the catholyte’s graphite felt electrode is electrochemically oxidized (overcharged) and by modifying the catholyte solution’s pH, which was monitored in situ for all flow batteries. Modulation of solution pH alters hydrolytic speciation of the charged catholyte from the typical dimeric species, µ-O-[FeIII(bpy)2(H2O)]2
4+, converting it to a higher-potential µ-dihydroxo form, µ-[FeIII(bpy)2(H2O)(OH)]2
4+, at lower pH. The existence of free bpyH2
2+ at low pH is found to strongly correlate with battery degradation. Near-neutral-pH RFBs employing a viologen anolyte, (SPr)2V, in excess with the [Fe(bpy)3]2+/3+ catholyte containing ACC exhibited high-voltage discharge for up to 600 cycles (41 days) with no discernible capacity fade. Correlating pH and voltage data offers powerful fundamental insight into organometallic (electro)chemistry with potential utility beyond battery applications. The findings, with implications toward a host of other “near-neutral” active species, illuminate the critical and underappreciated role of electrolyte pH on intracycle and long-term aqueous flow battery performance.
(1) Burghoff, A.; Holubowitch, N. E. Critical Roles of pH and Activated Carbon on the Speciation and Performance of an Archetypal Organometallic Complex for Aqueous Redox Flow Batteries. J. Am. Chem. Soc.
2024, 146 (14), 9728-9740. DOI: 10.1021/jacs.3c13828.
Figure 1. pH monitored in situ during long-term green catholyte experiment with ACC additions. (a) Schematic of pH probe experimental setup; (b) raw data for voltage and catholyte pH vs. time; (c) voltage and pH around the first ACC addition (80 mg at t = 37 h); (d) voltage and pH around the second ACC addition (80 mg at t = 64 h).

Figure 1