bluuebunny/crossref_metadata_2025 huggingface dataset:
Enhancing Supercapacitor Performance with Microemulsion-Based Electrolytes
Authors: Imel Adam , Arif Zulqarnain Z. , Barth Brian , Goenaga Gabriel , Zawodzinski Thomas A.
Published: December 2024

Supercapacitors (SCs) are energy storage devices between conventional capacitors and batteries, providing essential technology for rapid energy storage and discharge. Used in applications like laptops, automotive braking systems, and hybrid vehicles, SCs offer high power densities and long cycle lives, though their energy densities are typically moderate. Enhancing SC energy density requires using non-aqueous electrolytes to extend the voltage window and increasing the active surface area of the electrodes to boost capacitance. However, non-aqueous electrolytes often struggle with ion solubility, which is crucial for forming the electric double layer that enables rapid charging and discharging. Our studies into microemulsions as novel electrolytes show potential in decoupling conductivity from soluble oil, addressing ion solubility issues, and potentially unlocking further performance enhancements.

Microemulsions are promising electrolytes for energy storage, forming thermodynamically stable, homogeneous solutions of polar and non-polar molecules. These solutions stabilize oil and water mixtures, allowing non-polar oil to adsorb to hydrophobic carbon electrodes while maintaining high conductivity from an aqueous salt solution. Importantly, microemulsion components are environmentally and biologically safe.

This presentation explores the impact of surfactants and microemulsions on electric double-layer supercapacitor performance. We employ scanning electron microscopy to monitor the porous carbon layer on the grafoil substrate. Techniques like electrochemical impedance spectroscopy, cyclic voltammetry, and constant current charge and discharge provide comprehensive insights into SC performance. Our findings indicate that choosing surfactant, cosurfactant, and oil is crucial for maximizing SC performance.
(Invited) Preparation of Boron-Doped Nanodiamond and Its Application to Aqueous Electrochemical Capacitors
Authors: Kondo Takeshi
Published: December 2024

Boron-doped diamond (BDD) is known to be a functional electrode material that can be used in various electrochemical applications such as sensitive electroanalysis and efficient electrolysis, based on the unique electrochemical properties including wide potential window and low background current, as well as extreme physical/chemical stabilities. Usually, BDD electrodes are prepared by deposition of a polycrystalline BDD thin film on a conductive substrate. In this form, the specific surface area is too small to be used as an electrochemical capacitor. Thus, we have developed boron-doped nanodiamond (BDND) powder as a conductive diamond powder with a large specific surface area. BDND exhibits wider potential window in aqueous electrolytes than activated carbon (AC). Therefore, the BDND is expected to be used for an electrode material of aqueous EDLC with a large cell voltage.

Nanodiamond powder (primary particle size: 4 nm) was used as a substrate material for BDND. BDD was deposited on the agglomerate of dry nanodiamond powder via microwave plasma-assisted chemical vapor deposition (CVD). The as-deposited BDND was then treated by air oxidation at 425 °C to minimize sp2 carbon components to obtain BDND. Test electrode was prepared by casting an ink containing BDND on a glassy carbon disk electrode as a current collector. For an EDLC pouch cell, BDND paste containing PVDF binder was applied on the both sides of a titanium sheet current collector to form an electrode. Two electrodes with a separator in between was put in a plastic bag and aqueous electrolyte was poured in the bag to form a pouch cell.

The BDND was found to show a relatively large specific surface area of 650 m2 g−1 and good conductivity of ~1 S cm−1. CV in 1 M H2SO4 at the BDND test electrode in a three-electrode configuration showed a wide potential window of 3 V, which was significantly wider than that of an AC test electrode (1.5 V). In a symmetric two-electrode system, cell voltage of a CV in 1 M H2SO4 was found to be larger at the BDND electrode (1.8 V) than at the AC electrode (0.8 V). Therefore, wide potential window of the BDND was confirmed to be useful for creation of an aqueous EDLC with a large cell voltage. In addition, the use of saturated NaClO4 as an electrolyte was shown to be effective for an extremely large cell voltage of 2.8 V, which can further enlarge the energy and power densities of an aqueous EDLC. CV of BDND/saturated NaClO4 system exhibited a high energy density of 20 Wh kg−1 and a high power density of 104 W kg−1. Similar charge-discharge properties were also shown at EDLC pouch cells with BDND/concentrated NaClO4 system.
Impact of Cell Format, Engineering Design and Non-Active Components on EDLC Prototype Device Performance
Authors: Roberts Alexander John , Somyanonthanakun Wuttichai , Greszta Agata
Published: December 2024

With the increasing interest and research focus on energy storage devices such as supercapacitors, a huge amount of current research looks at the discovery and development of new active materials, with their testing and assessment typically performed at the lab coin cell level. It is often the case that when reporting a new supercapacitor material, parameters such as energy and power densities are quoted based on these coin cell results with no regard for the different formulation and properties of electrodes needed in production, with ‘parasitic’ but necessary mass, volume and performance contributions of essential cell components such as current collectors, cans, separator, electrolyte etc. being ignored. This results in predictions and comparisons, often made with commercially available products, that significantly overestimate the potential of new materials in commercially relevant devices.

The reality is that the results obtained from coin cell tests on early stage formulations of electrodes, whilst essential for material screening and understanding of the underlying science, do not give a clear indication of performance in an eventual commercial device. As a material is incorporated into prototype devices that come closer to commercial devices, the role and effects of non-active materials, cell format and also cell engineering have increasingly significant effects on performance and lifetime.

This work investigates how cell format, cell engineering and non-active components can affect commercially relevant prototype device performance when the active material and electrode formulation are kept constant. Through the construction and testing of pouch and 18650 cylindrical prototype cells, the effect of cell format is discussed in terms of power, energy and ESR, with further insight given in how the results at coin cell level scale to both formats and various sized pouch cells. The potential for improving performance at device level through non-active materials is demonstrated by changing the current collector in pouch cells, with a comparison between battery grade, carbon coated and etched aluminium foils, showing a significant difference in cell lifetime and ESR and surprisingly, >50% difference in cell energy density at high power density. An example of how cell engineering design can effect performance is also presented, with the variation of number and position of tabs in 18650 cylindrical EDLCs, also comparing to an in-house developed tab-less cell design.
Optimization of Solid Electrolytes for Enhanced Battery-Supercapacitor Hybrid Devices: A Leap Toward High-Capacity Retention and Extended Lifespan
Authors: Gomez Rojas Omar , Sugimoto Wataru
Published: December 2024

Battery-supercapacitor hybrid devices (BSHDs) are meant to fulfil the gap existing between conventional batteries and traditional supercapacitors by exhibiting high-energy and high-power densities, added to excellent cycling stabilities. Nonetheless, effectively integrating the diverse energy storage mechanisms of batteries and supercapacitors remains a significant challenge. Various approaches have been proposed to mitigate these issues ranging from developing advanced microstructures to engineering the interface between electrode|current collector or electrode|electrolyte.1

Previously, our team documented the fabrication of BSHDs capable of undergoing 3,000 charge-discharge cycles while maintaining 81% of their initial capacity.2 This work presents an upgraded iteration of BSHDs which maintains over 95% of the initial capacity and notably increasing the lifespan to over 10,000 cycles. The device in question is composed by a protected graphite anode and a solid electrolyte, composed by either an alginate polymer network or commercially available glass microfiber, with an ionic liquid (PP13-FSI; 1-Methyl-1-propylpyrrolidinium Bis(fluorosulfonyl)imide) as the ion conductive electrolyte. The improvement was achieved by conducting a thorough analysis and optimization of the solid electrolyte in response to the device’s performance during lithium-intercalation, i.e. introducing charge to the anode by forming a stable solid-electrolyte interface (SEI), added to the capability of such said anode as counter electrode during the operation of an activated carbon capacitor.

This work therefore discusses the duality between the maximum capacity obtained during the SEI formation process vs the capacity and anode potential retention during the operation of the BSHD, deep diving into the relationship of, inter alia, the thickness of the SEI formed, the increase or decrease of the ion-desolvation resistances, ionic conductivities, and activation energies versus the overall performance of the device.

References:

1F. Xing, Z. Bi, F. Su, F. Liu, Z.-S. Wu, Adv.
Energy Mater. 2022, 12, 2200594

2S. Makino a, R. Yamamoto, S. Sugimoto, W. Sugimoto, J
.
Power Sources 2016, 326, 711-716.

Figure 1
(Invited) Using Electrochemical Microscopy for Determining Ion Transfer Rates and Interphase Stability at the Electrode-Electrolyte Interface in Aqueous Batteries
Authors: Gossage Zachary Tyson , Ito Nanako , Hosaka Tomooki , Komaba Shinichi
Published: December 2024

A variety of new electrolyte systems are emerging for improving batteries toward safer, higher abundance, and higher performing technologies. This includes notable interest in improving aqueous batteries through the development of highly concentrated electrolytes, e.g. water-in-salt electrolytes (WISEs). Generally, WISEs are safe, non-flammable electrolytes that contain a large amount of electrolyte salt (several molar). This can lead to an electrochemical stability window over 3 V while at the same time showing relatively high ionic conductivities compared with organic electrolytes. Therefore, the application of WISEs in high-power devices (batteries, electrochemical capacitors) is promising. Recently, our group and others have been developing WISE-based batteries containing alkali metal cations (Li+, Na+, K+), alkaline earth metal cations (Mg2+, Ca2+), mixed salts, and others.1,2 Such systems can show lifetimes >1000 cycles, but their energy and power densities, as well as retention are still lacking compared with commercial LIBs.3 WISE chemistries are still emerging, and more knowledge is needed to approach improved performance.

Here, we focus on improving our analysis and understanding of the interphase chemistry, i.e. the solid-electrolyte interphase or SEI, that occurs within WISEs. The SEI is thought to play a significant role in ion transfer, and therefore it can have a direct effect on the rate performance of the battery. Unfortunately, the highly concentrated environment makes analysis of interfacial ion transfer quite difficult. Here, we will discuss new analytical approaches based on scanning electrochemical microscopy (SECM) that are under development in our lab to quantify ion transfer rates and dynamics within these concentrated battery systems (Figure 1). We show new concepts based on redox mediators which enable such analyses for relevant cations (e.g. K+, Li+, etc.) as shown in Figure 1b,c. Aside from ion transfer, the SEI should also prevent continuous electrolyte decomposition, including H2 evolution, during operation. Our group has shown that SECM is a powerful in situ method for observing SEI development and properties in such highly concentrated electrolytes. We found the SEI in a highly concentrated K+ electrolyte showed similar passivating properties to the SEI found in common organic electrolytes, but the coverage across the electrode and stability needed to be improved.4 We will discuss progress on SEI structures in other concentrated WISEs, and recent strategies to improve the SEI performance.

References

1 Hosaka, T., et al., J. Power Sources, 2022, 548, 232096.

2 Hosaka, T., et al., ACS Appl. Mater. Interfaces, 2022, 14(20), 23507.

3 Droguet, L., et al., Adv. Energy Mater., 2020, 10, 2002440.

4 Gossage, Z.T., et al., Angew. Chem. Int. Ed., 2023, 62, e2023074.

Figure 1
Enhanced Specific Capacitance of Lithium Ion Capacitors By Effective Surface Functionalization for Lithiophilic Activated Carbon
Authors: Do Kyungmin , Ryu Jihyeon , Choi Minhyeok , Eom Seung-Wook , Kim Ick-Jun , Yang Sunhye
Published: December 2024

Lithium Ion Capacitor (LIC) is a hybrid energy storage device that combines high power characteristics of Electric Double Layer Capacitors (EDLC) with high energy density features of Lithium Ion Batteries (LIB). In LICs, a graphite electrode from LIBs serves as the anode, while an activated carbon electrode from EDLCs functions as the cathode. This configuration results in higher energy density than EDLCs, improved power and cycling characteristics compared to LIBs. To supply lithium ions internally or externally as the energy source, LICs may employ techniques such as (1) Li pre-doping, (2) the use of sacrificial anodes made from Li transition metal oxides, or (3) electrodes embedded with lithium ions.

Significant research efforts are underway to enhance the resistance components and performance metrics, including energy density and output of LICs. Although methods like adding Li transition metal oxide, sintering salts, or blending with activated carbon are employed to increase internal capacity, challenges such as decreased energy density per unit weight, increased resistance from reaction by-products, or gas formation persist. During discharge, the desolvation energy of cations is higher than that of anions, and an increase in resistance components occurs at the 3 V point where ion exchange between lithium ions and anions happens.

This study focuses on minimizing resistance components in LICs by synthesizing a Li/activated carbon (Li/AC) hybrid material, which provides a Li source within the activated carbon matrix. Acid treatment introduces oxygen functional groups on the surface of the activated carbon, followed by the synthesis of lithium compounds using a Li precursor. The crystallization and growth conditions of Li ions were optimized using the thermal treatment temperatures established in previous studies. The study also conducted concentration-dependent synthesis experiments to optimize the molar concentration of the Li precursor solution. The manufactured Li/AC active materials were tested for charge and discharge cycles, Nyquist plots, and rate capability. To analyze these properties, techniques such as Brunauer Emmett Teller (BET) analysis, Transmission Electron Microscope (TEM), Scanning Electron Microscope (SEM), and Thermogravimetric Analyzers (TGA) were employed.
Redox Flow Deionization Using Prussian Blue and Functionalized Ion Exchange Membrane for Enhanced Selective Lithium Recovery
Authors: Cho Younghyun , Khoi Tran Minh , Huynh Van Phung , Tran Thu , Shin Jae Eun
Published: December 2024

Flow electrode capacitive deionization (FCDI) is a newly developed water treatment technology that offers better performance than the original, solid electrode capacitive deionization (CDI). By eliminating the need for discharging process, FCDI provides much higher desalination capacity with a continuous desalination operation. Along with applications for salt removal, selective removal and recovery of specific ions are also prominent features of FCDI technology. Characteristics of electrodes and ion exchange membranes play a crucial role in controlling the selectivity of ions in an FCDI system. In this study, we demonstrated selective and continuous ion recovery by combining redox-active Prussian blue as flow electrodes and functionalized ion exchange membranes in FCDI configuration. Prussian blue selectively absorbs monovalent Na+ ions from Na+/Ca2+ mixtures through intercalation reaction, in which a smaller Stokes radius of Na+ ion is more favored to fit in the crystal lattice. Furthermore, such selectivity is much more enhanced through functionalization of a cation-exchange membrane (CEM) with polymer multilayers. A layer-by-layer method was used to deposit poly(allylamine hydrochloride) (PAH) and poly(styrene sulfonate) (PSS) on the CEM. Results showed that polymer multilayers changed the CEM from divalent to monovalent ion-affinity due to different ion sizes and charge density. The combination of Prussian blue and functionalized CEM raised the selectivity for sodium around 17 times compared to a control system (0.2 to 3.35). Furthermore, our results showed a highest Li selectivity of 12.88 with an extremely low energy consumption of 0.57 Wh/molLi. We believe our approach can lead to new technologies that address the shortcomings of existing lithium recycling method and expand the application not only to lithium recycling, but also to future lithium production technologies and the removal of specific ions, such as toxin removal.
Highly Interconnected Macroporous Carbon Spheres for Ionogel-Based Stretchable Supercapacitors
Authors: Heo Incheol , Lee Seongchan , Yoo Won Cheol
Published: December 2024

Due to their exceptional properties such as lightweight, high electrical conductivity, specific surface area (SSA), adjustable pore structures, and desired surface characteristics, carbonaceous materials have substantial interest as electrode materials for supercapacitors (SCs). In attempts to achieve high energy density, ionic liquid (IL) electrolyte is has attracted great attention Because it can be used in a wide voltage range. However, initial attempts to incorporate IL into SCs encountered challenges, as the large and sluggish ions struggled to effectively access the narrow pores of conventional microporous carbons. In addressing these issues, we have synthesized interconnected meso/macroporous carbon spheres (MCSs) that were produced via co-assembly of polymer and silica sphere (20-70 nm). The interconnected large meso/macropores facilitated ion mass-transport and thereby efficient utilization of the carbon electrode's surface for capacitive energy storage. The MCS-based SCs demonstrated a high capacitance (328.93 F g-1) and ultrahigh energy density (182.7 Wh kg-1), and MCS/IL-based inogel SCs exhibited a remarkably high energy density of 0.111 mWh cm⁻
2 and a high-power density 8.89 m Wcm-2 demonstrated excellent mechanical durability 0% and 100% strain, with notable capacitive retention of 95.3% observed at 100% strain. Comparable to the best results reported to date. Therefore, the results obtained in this study provide morphological insights into the differences in electrochemical performance based on pore size and particle size. Additionally, these findings contribute to the design of carbon-based materials suitable for electrochemically robust yet dynamically sluggish ionic liquid electrolytes, aiming for high-performance deformable energy supply devices.
Micrometer Scale X-Ray CT Assisted Cathode Pore Space Designs for High Energy Fast Discharge Rate Lithium-Ion Battery
Authors: Pan Bonian , Whitacre Jay F , Wu Xinsheng , Lee Young-Geun
Published: December 2024

The increasing demand for hybrid electric vehicles (HEVs) necessitates batteries capable of higher discharge rates. This study focuses on the design of cathode pore structures in lithium-ion batteries, aiming to enhance bulk ion transport and thereby achieving higher spatial energy density at higher discharge rates, a critical requirement for hybrid EVs. We report here novel cathode pore space designs using well understood NCM 811 high energy density cathode material to address this need. These designs include a double layer structure with varying porosity, a femto-second laser etched directional pore structure, and how different electrolyte interacts with each of these systems. These tailored structures are hypothesized to facilitate improved ion transport, reducing local stress, and thus contributing to enhanced battery performance and extended battery lifespan. To validate our designs, we employed micrometer-scale X-ray computed tomography (CT) and pore network modelling for structural characterization, quantifying the pore structure mathematically. The performance of these cathodes was evaluated using a suite of electrochemical techniques, including cyclic voltammetry and Electrochemical Impedance Spectroscopy (EIS), which reveals their impact on cell level performance. Our findings contribute to the ongoing efforts to optimize lithium-ion battery technology for hybrid EVs, offering insights into the potential of tailored cathode structures to improve battery performance. Further research is needed to refine these designs and assess their scalability and feasibility for commercial applications.
Development of a High-Capacity MXene Electrode for All-Solid-State Batteries
Authors: Fujita Masaki , Peeters Mathieu , Kawai Kosuke , Nomura Yuki , Okubo Masashi
Published: December 2024

The global market of energy storage devices is growing for the large-scale applications such as electric vehicles and stationary power supplies. Lithium-ion batteries (LIBs) now dominate the market owing to their large energy density and long cycle life. However, the flammable organic electrolytes of LIBs pose intrinsic risks of fire and explosion accidents. Replacing the organic electrolytes with nonflammable inorganic solid electrolytes should solve the safety issue of LIBs, which accelerates development of all-solid-state batteries (ASSBs).

Conventional electrode materials show large volume changes upon (de)lithiation, causing interfacial failure between electrode materials and solid electrolytes in ASSBs.Consequently, lithium-ion flux is excessively concentrated on remaining solid-solid interfaces or loses accessibility to electrode materials. Although spinel-type Li4Ti5O12 shows a small volume change upon (de)lithiation, the specific capacity is not satisfactory (< 170 mAh g–1), which results in low energy densities. Therefore, electrode materials that show a small volume change with a large specific capacity is required to develop ASSBs with long cycle life and high energy density.

Since the first report in 2011, layered transition-metal carbide/nitride (MXene) has been investigated as electrode materials for energy storage devices.1 MXene, which is represented with a general chemical formula M
n

+1X
n
T
x
(M = Ti, V, Nb, etc.; X = C and N; T = F, OH, O, etc.; n = 1–4), shows small volume change upon (de)lithiation with large specific capacities (~200 mAh g–1) at a low operation voltage (~1.0 V vs Li/Li+).2,3 The strain-free property of MXene is beneficial to improve the cycle life of all-solid-state batteries. In this presentation, we develop a high-capacity Ti2CT
x
MXene as an anode material for ASSBs. Li3PS4 glass is used as a solid electrolyte because its high ionic conductivity (~2×10–4 S cm–1) and high ductility.

Ti2CT
x
was synthesized by removing Al layers from Ti2AlC using a LiF/HCl etchant. Li3PS4 glass electrolyte was synthesized by mechanochemical milling. The Ti2CT
x
|Li3PS4 glass electrode delivers a specific capacity of 340 mAh g–1 at a specific current of 20 mA g–1 in a voltage range from –0.6 to 2.4 V vs. InLi. After the 80th cycle, 74% of the first discharge capacity is retained (239 mAh g–1) with a coulombic efficiency of 99.4% (Fig. 1). Electrochemical impedance spectroscopy indicates that a stable solid-solid interface forms between Ti2CTx and Li3PS4 glass, which is beneficial for the long cycle life.

Reference

X. Wang, S. Kajiyama, H. Iinuma, E. Hosono, S. Oro, I. Moriguchi, M. Okubo, A. Yamada, Nat. Commun. 6, 6544 (2015).

M. Okubo, A. Sugahara, S. Kajiyama, A. Atsuo, Acc. Chem. Rev. 51, 591–599 (2018).

K. Kawai, M. Fujita, R. Iizuka, A. Yamada, M. Okubo, 2D Mater. 10, 014012 (2023).

Figure 1
Mechanism of Charge Transfer Via Dielectric Interfaces in Li Ion Battery
Authors: Higaki Yusuke , Teranishi Takashi , Kondo Shinya , Kishimoto Akira , Sasaoka Chinatsu , Hirabaru Hikaru , Katayama Shingo
Published: December 2024

Lithium-ion batteries (LIBs) are utilized into the power source of the electric vehicles (EVs) due to their relatively high energy density (~200 Whkg-1), originating from high theoretical capacity of the bulk oxide electrodes. In order to deliver both excellent acceleration and better fuel efficiency, LIBs is required to achieve a good balance between high power density (low cell resistance) and high electric capacity. The high-rate capability of LIBs is generally limited by the slow charge transfer at the electrolyte–electrode interface. In particular, the slow Li diffusion through the solid electrolyte interfaces (SEIs), namely an undesirable byproduct, attributing to the electrolyte decomposition during cycling, severely increase the charge transfer resistance (R
ct) of the cell. Oxide-layer decoration of the active material, e.g., Al2O3, can act as barrier layers to prevent undesirable side reactions at the electrolyte–active material interface, thus preventing the evolution of mentioned native SEIs [1]. Nanoscale coating of such protection layers, regarded as an artificial SEI, also allows a faster Li transfer at the electrolyte–cathode interface, rather than the Li diffusion via native SEIs, resulting in better high-rate characteristics.

We have been proposing the partial surface decoration onto the active materials by dielectric nanoparticles as an artificial SEI, which enables faster charge transfer architecture via the surface Li diffusion of the dielectric layer [2]. For instance, incorporating BaTiO3 (BTO) nanoparticles into the surface of LiCoO2 (LCO) led to drastically enhanced high-rate capabilities. A series of experimental results and calculations utilizing density functional theory and molecular dynamics (DFT-MD) implied the improved activity at interfacial charge transfer is responsible for the faster Li adsorption and subsequent desolvation process at the dielectric surfaces. In this study, the dominant factors determining the adsorption and desolvation activities, which are strongly affecting high rate capability, were elucidated. The cell evaluations of the cathodes modified with various metal oxides SEIs, in addition to the conventional BTO based compounds, were performed as a function of the local chemical structure as well as the surface polarization between cation and neighborhood anions.

[1] L. Daheron, R. Dedryvere, H. Martinez, D. Flahaut, M. Menetrier, C. Delmas, and D. Gonbeau, Chem. Mater, 21, (2009), 5607–5616.

[2] T. Teranishi, K. Kozai, S. Yasuhara, S. Yasui, N. Ishida, K. Ishida, M. Nakayama, A. Kishimoto, Journal of Power Sources, 494, (2021) 229710.
Investigating the Morphological Evolution of Lithium Plating/Stripping in Concentrated Electrolyte by Operando X-Ray Computed Tomography
Authors: Liu Xiaoyu , Watanabe Toshiki , Orikasa Yuki , Yamada Yuki , Kanamura Kiyoshi , Uchimoto Yoshiharu
Published: December 2024

Lithium metal is expected to be next-generation anode because of its low redox potential (-3.04 V vs SHE.) and high specific capacity (3860 mAh g-1), which can achieve high energy density by matching with sulfur or oxygen cathode.1 However, Li metal anode is not viable until now due to the uncontrollable morphology and high activity during Li plating/stripping.2 Especially the growth of Li dendrites, the formation of dead Li, and the broken of unstable SEI (solid electrolyte interphase), result in significant safety risk and low coulombic efficiency. Therefore, to obtain the stable Li metal anode, it’s important to investigate the behavior of Li plating/stripping and the properties of SEI.

In recent years, concentrated electrolyte has received great attention as an effective means to improve the performance of lithium anode.3 With the development of these electrolytes, new insights into lithium morphology and SEI composition have also emerged. Compared with that in dilute electrolytes, the solvation structures of Li ions in concentrated electrolytes are changed, thus the SEI components are also changed from solvent derived to lithium salt anion derived.4 As a result, the morphology of Li and the performance of lithium metal anode are effectively improved.5 However, how these changes in solvation structure and SEI composition affect lithium morphology during cycling, which is helpful to gain more information about the basic Li behavior, remains unclear.

This study endeavors to elucidate the Li plating/stripping behaviors in concentrated electrolyte by operando X-ray computed tomography. The morphological evolution of Li on Cu current collector surface is investigated. In particular, the growth of Li dendrites and the formation of dead Li, as well as the evolution process between them, have received special attention. These results are helpful to understand basic Li plating/stripping behaviors during cycling and provide guidance to lithium metal anode improvement.

Acknowledgment

This work was financially supported by the JST, GteX Project (Grant Number: JPMJGX23S3).

References

[1] Y. Cui et al., Nat. Nanotechnol.
2017, 12 (3), 194-206.

[2] Q. Zhang et al., Chem. Rev.
2017, 117, 10403−10473

[3] G. M. Hobold et al., Nat. Energy,
2021, 6, 951-960.

[4] Y. Yamada et al., J. Am. Chem. Soc., 2014, 136, 5039.

[5] J. G. Zhang et al., Nat. Commun.,2015, 6(1), 6362.
Optimization of an Aqueous Zn-Mn Redox Flow Battery System
Authors: Natale Eleonora , Lissandrello Federico , Gibertini Eugenio , Magagnin Luca
Published: December 2024

Zinc-based negative electrodes are chosen for their cost-effectiveness, low equilibrium potential, and high electrochemical reversibility, making them widely utilized in redox flow batteries. To achieve a high cell voltage, zinc electrodes are usually paired with positive half-cells featuring high equilibrium potentials, such as Zn-air and Zn-Br systems [1]. The work investigates the feasibility of an alkaline redox flow battery with high energy density and operating voltage involving Zn/ Zn(OH)₄2- and MnO₄⁻/MnO₄²⁻ redox couples. The study focuses on the less-explored permanganate half-cell, which offers a high equilibrium potential (+0.55 V vs SHE) and excellent solubility in alkaline conditions (~3.6 M). These properties make it a promising candidate for positive electrolytes with high energy density [2]. In the study, the electrolytes of the two cells were optimized separately to increase conductivity and avoid side reactions. Cyclic voltammetry experiments at different scan rates confirm the excellent reversibility of electrochemical reactions in both the zinc and permanganate-based electrolytes, characterized by high faradic efficiency. Subsequently, a prototype flow battery is assembled and subjected to galvanostatic charge/discharge tests to assess stability and performance. The cell is evaluated at varying catholyte concentrations and different current densities to determine rate performance. The galvanostatic tests demonstrate remarkable cycling stability and notable cell potential compared to other aqueous systems. The battery exhibits high energetic efficiency (EE > 75%) and Coulombic efficiency (CE) and voltage efficiency (VE) both around 85%. Capacity tests at full charge reveal stable electrochemical reactions throughout the charging and discharging processes. Additionally, ex-situ UV-vis spectroscopy is employed to investigate the mechanism of the manganate/permanganate redox reaction and evaluate the permeability of permanganate ions through membranes during cycling. Overall, the study provides significant insights into the development of high-voltage aqueous batteries. The alkaline Zn-MnO₄⁻ flow battery described in this work emerges as a promising candidate for energy storage applications, offering enhanced stability, high energy efficiency, and energy density.

References:

[1] J. Ren, Z. Wang, B. Liu, al -, J.D. Milshtein, J.L. Barton, T.J. Carney, G. Wang, H. Zou, X. Zhu, M. Ding, C. Jia, Recent progress in zinc-based redox flow batteries: a review, J Phys D Appl Phys 55 (2021) 163001. https://doi.org/10.1088/1361-6463/AC4182.

[2] A.N. Colli, P. Peljo, H.H. Girault, High energy density MnO4
- /MnO4
2− redox couple for alkaline redox flow batteries, Chemical Communications 52 (2016) 14039–14042. https://doi.org/10.1039/C6CC08070G.
Development of Coal-Derived Graphite for Lithium-Ion Batteries
Authors: Paul Abigail , Baca Isabel , Magee Regan , Wilczewski Warren , Wichert Nathan , Wolfe Kody D , Lowe Jeffrey , Trembly Jason , Staser John A. , Garrick Taylor R.
Published: December 2024

The demand for graphite is expected to increase considerably as the demand for lithium-ion batteries grows. Much of the graphite used in the United States is imported from other countries.1 Because of this supply chain, there is a desire to develop a domestic supply of graphite. One potential feedstock that shows promise is coal because of its abundance and chemical structure. Coal-derived graphite has been successfully utilized in lithium-ion batteries.2

In this poster, the characterization and electrochemical performance of multiple coal-derived graphites will be presented. A focus will be placed on linking electrochemical performance to the microstructure of each material. Electrochemical performance data such as initial capacity loss, gravimetric capacity and columbic efficiency will be presented for both coin and pouch cells. The application of the Multi-Species, Multi-Reaction model on coal-derived graphite will also be presented.

References:

Mineral Commodity Summaries, (2021), p. 82–83.

A. Paul et al., Journal of The Electrochemical Society, 171, 039001 (2024)
Investigating Reduction Intermediates of Fluoroethylene Carbonate
Authors: Ramesh Sapna L , Krzyaniak Matthew D , Wasielewski Michael R , Lopez Jeffrey
Published: December 2024

Lithium-ion batteries are integral to the clean energy transition due to the important role of electric vehicles in lowering transportation sector emissions. As electrification continues to play a key role in mitigating climate change, there is a need for lithium-ion batteries with energy densities exceeding 500 Wh/kg. Among energy storage technologies, lithium metal batteries (LMBs) offer great potential due to lithium’s high theoretical specific capacity and low electrochemical potential, enabling batteries with energy densities surpassing current state of the art lithium-ion batteries.1 However, the highly reductive lithium metal anode reacts with the electrolyte during cycling, resulting in capacity loss and forming a solid electrolyte interphase (SEI). Electrolyte engineering has emerged as a successful strategy in tuning these reactions to form mechanically and chemically stable SEI, while preventing further parasitic reactions between the lithium metal anode and electrolyte.

In this work, we investigate the reduction mechanism of fluoroethylene carbonate (FEC), a highly effective electrolyte solvent in LMBs.2 We probe the mechanism by which FEC and other similar fluorinated solvents are reduced to form an SEI in order to identify key reduction intermediates that underpin the high performance of these electrolytes and their interphases. In the case of FEC, LiF is commonly identified as a crucial SEI component that results in a stable SEI, but recent research has demonstrated that a preformed SEI comprised solely of LiF breaks down during cycling, illustrating that bulk chemical and mechanical properties of individual SEI components may not translate to their function within the SEI.3 In this work, we employ electron paramagnetic resonance (EPR) spectroscopy to study radical reaction intermediates formed during FEC reduction within an electrochemical cell. We identify these reaction intermediates by employing a spin trap, which stabilizes these intermediates and enables their characterization at room temperature. Using this approach, we have identified two distinct radical species formed during FEC reduction. We further analyze these species with a combination of density functional theory (DFT) calculations and nuclear magnetic resonance (NMR) spectroscopy. Ultimately, this framework will expand the tools available to the field of electrolyte engineering to design stable and effective interphases for lithium metal batteries, enabling the next generation of electrolyte design.

References

K. G. Gallagher et al., Energy Environ. Sci., 7, 1555–1563 (2014).

X.-Q. Zhang, X.-B. Cheng, X. Chen, C. Yan, and Q. Zhang, Advanced Functional Materials, 27, 1605989 (2017).

M. He, R. Guo, G. M. Hobold, H. Gao, and B. M. Gallant, Proceedings of the National Academy of Sciences, 117, 73–79 (2020).
Highly-Coordinated Iron Complex with Multidentate Ligands for Aqueous Redox Flow Battery Electrolytes
Authors: Soshi Kodama , Kawai Kosuke , Atsushi Okazawa , Okubo Masashi
Published: December 2024

Redox flow batteries (RFBs) possess a longer cycle life than other secondary batteries owing to their limited electrode deterioration upon charge/discharge cycling. Commercial RFBs use vanadium ions as active materials, resulting in a high cost. Therefore, more abundant and less expensive iron-based complexes are desirable as catholyte active materials for RFBs. However, to develop stable iron-based aqueous electrolytes, precipitation of ferric hydroxides under a mild alkaline condition should be suppressed. One potential strategy is to use polydentate ligands that stabilizes the iron coordination structure owing to a chelating effect. For example, a heptadentated [Fe(DTPA)]2
− (DTPA: diethylenetriaminepentaacetate) shows an excellent cycle stability of 0.029% per cycle as an RFB posolyte.[2] In this study, we further improve the cycle stability of iron-based complexes using an octadentate tetraazacyclododecatetraacetate (DOTA) ligand.

The target complex, K[Fe(DOTA)], was prepared by adding FeCl3•6H2O to an aqueous solution of deprotonated DOTA. Single-crystal X-ray structural analysis reveals an eight-coordinated structure of the iron complex. Cyclic voltammetry shows a redox peak at 0.37 V (vs. SHE) for K[Fe(DOTA)], which is higher by 0.088 V than that for K2[Fe(DTPA)] and by 0.12 V than that for K[Fe(EDTA)] (Figure 1). Levich plots obtained by rotating desk electrode measurements reveal the diffusion coefficient of 9.9×10−7 cm2 s−1 and the electron transfer rate constant of 5.0×10−3 cm s−1 for K[Fe(DOTA)] , which are comparable to those of K2[Fe(DTPA)]. UV-Vis spectroscopy shows the aqueous solubility of 0.57 mol L−1 for K[Fe(DOTA)], which is lower than that of K2[Fe(DTPA)] (1.3 mol L−1). The low solubility of K[Fe(DOTA)] should arise from large lattice energy owing to its symmetric structure. Charge/discharge measurements using an H-type cell with 0.10 mol L−1 KCl aqueous solution reveal that K[Fe(DOTA)] exhibits a greater capacity retention rate of 99.973% per cycle than K2[Fe(DTPA)] (99.333%/cycle) (Figure 2).

Reference:

[1] H. J. Schugar, C. Walling, R. B. Jones, H. B. Gray, J. Am. Chem. Soc.
1967, 89, 3712.

[2] S. E. Waters, B. H. Robb, M. P. Marshak, ACS Energy Lett.
2020, 5, 1758.

Figure 1
Utilizing Advanced Spectroscopy Techniques to Investigate Mn-Ligand Bonding Environments in Disordered Rocksalt Oxyfluorides
Authors: Sunariwal Neelam , Kumar Khagesh , Cabana Jordi
Published: December 2024

Li-rich disordered rock-salt oxyfluorides (DRS) stand out as a promising class of cathode materials due to their exceptional electrochemical performance [1-3]. The substitution of oxygen (O) with fluorine (F) within DRS compounds has demonstrated a significant enhancement in reversible discharge capacity, making them highly desirable candidates for next-generation high-energy Li-ion batteries with enhanced capacity. Despite considerable research into the structural and electrochemical characteristics of these materials, the metal-fluorine (M-F) bonding in DRS oxyfluorides has received limited attention [4,5]. To address this gap in knowledge, we synthesized oxyfluorides based on manganese (Mn) with a composition of Li2MO2F. Employing advanced spectroscopy techniques, we sought to unravel the intricate details of Mn-F bonding in DRS materials. Specifically, we utilized Kβ X-ray emission spectroscopy (XES) to examine the Mn bonding environment and performed fluorine Resonant Inelastic X-ray Scattering (RIXS) measurements to gain insights into the F bonding perspective. Kβ XES has therefore been established as a probe of both metal and ligand properties and RIXS of F enables a direct investigation of Mn-F bonding dynamics by identifying alterations in emission features corresponding to various excitation energies in the F XAS pre-edge region upon charging [6-8]. Furthermore, Kβ XES analysis offers valuable information on the oxidation states and covalency trends of Mn-ligand interactions comparing with the end-member Mn oxides and fluorides.

References:

D. Chen, J. Ahn, and G. Chen, ACS Energy Lett., 6, 1358–1376 (2021).

X. Xu et al., J. Electrochem. Soc., 168, 080521 (2021).

D. A. Kitchaev et al., Energy Environ. Sci., 11, 2159–2171 (2018).

I. Roy et al., Chem. Mater.(2023), 35, 5, 2107–2113

N. Sunariwal et al., Adv. Funct. Mater.2024,34, 2312010

C. J. Pollock et al, J. Am. Chem. Soc. (2014), 136, 9453−9463

S. Limandri et al. Chemical Physics 367 (2010) 93–98

D. J. Higley et al., Communications Physics volume 5, Article number: 83 (2022)
Novel Polymeric Morphologies as Positive Electrodes in Lithium-Ion Batteries
Authors: Tharrington Cade T. , Petrecca Michael J. , Velev Orlin D. , Fedkiw Peter S.
Published: December 2024

Growing demands for next-generation energy storage technology for utilization in consumer and grid energy storage applications have prompted a re-evaluation of lithium-ion batteries (LIBs), which are the preeminent electrochemical energy storage technology. Due to the cost and environmental impact of transition metals used in the positive electrode, researchers are investigating novel materials and processing techniques to introduce new chemistries and electrode architectures into LIBs. Herein, we propose a novel materials-processing platform to develop application-specific polymeric electrode architectures for next-generation LIBs. Organic radical polymers are of interest as an alternative positive electrode for LIBs. In particular, poly (2,2,6,6 tetramethyl-1-piperidinyloxy-4-yl methacrylate) (PTMA) has garnered attention for its relative ease of synthesis and its fast charge-discharge kinetics. However, before implementation as an electrode, PTMA requires a significant amount of conductive additive and binder to remedy its electronically insulating polymeric backbone and its solubility in organic electrolytes, all of which decreases the gravimetric performance of PTMA. The multiphasic processing platform presented here utilizes the precipitation of PTMA in turbulent solvent-nonsolvent induced phase separation to introduce a soft dendritic colloid (SDC) morphology. Characterized by fractal branching and nanofibrillar contact splitting, the morphology of PTMA SDCs rectifies the solubility and electronic conductivity limitations associated with PTMA electrodes by introducing improved surface area and self-adhesive properties. Rate capability and cycling stability improvements are expected from PTMA SDC electrodes compared to benchmark slurry cast PTMA electrodes due to more efficient contact with conductive additives and reduced electrolyte solubility in PTMA SDCs. This hypothesis is tested and reported upon here through electrochemical analysis via cyclic voltammetry and galvanostatic charge and discharge experiments of PTMA SDC and benchmark slurry cast PTMA positive electrodes in half-cell environments against reference lithium metal electrodes.
Soaking Tests to Understand and Mitigate Electrolyte Decomposition Products Etching on Li- and Mn- Rich Cathode Materials
Authors: Wang Bingning , Liao Chen , Garcia Juan , Iddir Hakim , Qin Yang , Zhu Qijia , Liu Qian , Tornheim Adam P.
Published: December 2024

A series of soaking experiments were conducted to investigate electrolyte decompositions etching on the 5 V cobalt-free spinel LiNi0.5Mn1.5O4 (LNMO) cathode, revealing that intense electrode/electrolyte reactions between LNMO and Gen2 electrolyte could lead to significant corrosion and delamination of electrode laminates.1 In this study, similar soaking tests are performed for 0.3Li2MnO3
·0.7LiMn0.5Ni0.5O2 (LMR-NM), a promising cathode material for next-generation high-energy-density and cobalt-free lithium-ion batteries, to assess its stability with respect to the electrolyte and its aging byproducts resulting from extended storage at elevated temperature.

The acidic electrolyte decomposition generated at 55 oC can result in undesirable transition metal (TM) dissolution, which is considered as a main cause for lithium inventory loss and cells degradation. However, lithium difluoro(oxalato)borate (LiDFOB) can act as a scavenger type additive by reacting with early-stage electrolyte decomposition products, forming a thermal stable salt of lithium tetrafluoro oxalato phosphate (LiF4OxP), and preventing further electrolyte decompositions.2 Additionally, modifications involving Co-doping and Al(NO3)3 surface coating for LMR-NM can also alleviate these electrode/electrolyte interactions. The role of cathode electrolyte interphase (CEI) in mitigating such etching is also examined.

Wang, Bingning, et al. "Understanding and Mitigating the Dissolution and Delamination Issues Encountered with High-Voltage LiNi0. 5Mn1. 5O4." Batteries9 (2023): 435.

Liu, Minghong, et al. "Improved electrolyte and its application in LiNi1/3Mn1/3Co1/3O2–Graphite full cells." Journal of Power Sources268 (2014): 37-44.
Innovative Dual Cross-Link Hydrogel for Enhanced Stability and Performance of Zinc-Ion Batteries
Authors: Wang Peng , Andrei Petru
Published: December 2024

Zinc-ion batteries (ZIBs) are emerging as promising contenders in the realm of energy storage due to their potential for cost-effectiveness, environmental sustainability, high safety. However, the formation of dendrites on Zn anodes, alongside hydrogen evolution and side reactions, represent notable disadvantages in the performance of zinc-ion batteries. These challenges hinder their long-term stability and efficiency, necessitating further research and development efforts to overcome them. Strategies to overcome challenges in zinc-ion batteries include improving Zn anode construction to mitigate dendrite formation and adjusting electrolyte composition to suppress hydrogen evolution and side reactions. Additionally, the use of solid-state or gel polymer electrolytes can enhance ion transport and reduce dendrite formation.

In this presentation, we introduce a rapid and effective method for constructing a dual cross-link hydrogel directly onto current collectors, such as Carbon Fiber Paper (CFP) and Carbon Nanotube (CNT) film, utilizing polyacrylamide and aramid nano fiber (ANF). The resulting hydrogel exhibits high ionic conductivity and improved mechanical properties, mitigating the formation of Zn dendrites and enhancing cycling stability in Zn/Zn symmetric cells (stable after 1000 hours of plating/stripping). Additionally, in-situ polymerization on cathode current collectors enhances electrolyte-cathode active material contact, particularly beneficial for porous cathodes like CFP. Furthermore, combined with in-situ electrochemical deposition of MnO2 active material, this approach facilitates the production of practical winding batteries using conventional winding machines. This research provides an efficient approach to assembling practical, flexible and stable AZIBs pouch cells with high capacity and cycling stability.