bluuebunny/crossref_metadata_2025 huggingface dataset:
Quantitative Analysis of H+ Transportation of Nafion film on Different Substrate using Planar Inter Digitated Electrodes
Authors: Bhardwaj Rahul , Suwansoontorn Athchaya , Hirose Daisuke , Takamura Yuzuru , Abbaszadehami Mehran , Karan Kunal , Nagao Yuki
Published: November 2022

Introduction: Ionomer thin-film gained attraction because of their thickness- and morphology-dependent changes in ionic conductivity. In a fuel cell catalyst layer, ionomer thin films coating the carbon-supported Pt-based catalysts (Pt/C) is distributed in spatially heterogeneous manner with variation in thickness and connectivity. Thus, it is difficult to clarify the quantitative attribution of the true source of effective proton resistance among Pt and carbon-support. To evaluate the quantitative attribution of proton conductivity of a thin-film ionomer on relevant substrates (e.g., carbon), we have fabricated specially designed interdigitated electrodes (IDEs) to accommodate different substrates upon which ionomer film is coated. In this work, we present the Nafion (~55 nm) proton (H+) transportation over carbon and quartz substrate in N2 atmosphere. Also, we will discuss the true attribution of substrate-dependence to estimate the Nafion’s thin film conductivity.

Experimental: Interdigitated electrodes (IDEs) with and without carbon pad were fabricated in clean room facilities. To prepare IDEs, the patterned carbon structure was developed and pyrolyzed at 1000 ºC in 2% H2/N2 gas before the Pt deposition. 1.2% Nafion dispersion was spin coated and dried at 40ºC under vacuum before electrochemical impedance spectroscopy (EIS) measurement in N2 atmosphere. Relative humidity (RH) dependence of in-plane H+ resistance was obtained and discussed through EIS measurements.

Results and Discussion: Figure 1 (a) and (b) shows the side view of IDEs with (Pt_C_IDE) and without carbon pad (Pt_Q_IDE), and also Nafion’s (~55 nm) H+ resistance obtained from EIS measurement at various RH in N2 atmosphere. Nyquist plot (not shown) exhibited significant difference and ascribed film resistance (Mean value) for ionomer at carbon substrate was significantly lower (one order of magnitude) compared to that at the quartz substrate, as shown in Fig. 1 (c).

In case of H+ resistance using Pt IDE with carbon (Pt_C_IDE), approximately 90% of the IDE area between the electrodes is carbon and the rest is quartz. Therefore, the method of estimation of Nafion’s thin film conductivity from impedance response must be reviewed carefully and will be discussed later in detail.

References:

[1] Y. Nagao Sci. Tech. Adv. Mater, 21, 79 (2020).

[2] X. Gao, K. Yamamoto et al.
Solid State Ionics, 357, 115456 (2020).

[3] U. N. Shrivastava, D. Khattar et al.
J. Electrochem. Soc., 167, 134520 (2020).

Figure 1
Chemically Tuning Ionomer Thin Film Properties for Improved Electrode Function
Authors: Bird Ashley , Kusoglu Ahmet
Published: November 2022

Ion-conducting polymers (ionomers) are an important component of the heterogenous electrodes (catalyst layers, CL) in proton exchange membrane fuel cells (PEMFCs). In the CL, the nano-thin ionomer layer facilitates mass transport to and from the catalyst sites. Emerging chemistries have the potential to improve this mass transport by inserting additional acid groups to each sidechain or by modifying the backbone. This work aims to understand the impact of ionomer chemistry on the structure-property relationships relevant to fuel cells. Ionomer thin films (<100 nm) cast on planar supports model the CL ionomer. Film nanomorphology is characterized via in situ grazing-incidence x-ray scattering (GIXS); application-relevant properties, including hydration and proton conductivity, are probed via spectroscopic ellipsometry and electrochemical impedance spectroscopy, respectively. While both sidechain and backbone modifications lead to improvements in proton conductivity, the sidechain-modified ionomers show greater hydration and nanophase separation, and the backbone-modified ionomers show reduced hydration and nanophase separation, demonstrating the interplay between morphology, hydration, and film function. These results show that chemistry is a useful tool to tune thin film properties and provide insight to guide future ionomer design.
Chemical Stability Enhancement of Aromatic Proton Exchange Membranes Using a Damage Repair Mechanism
Authors: de Wild Tym , Nemeth Tamas , Nauser Thomas , Schmidt Thomas J. , Gubler Lorenz
Published: November 2022

Harmful radical species (HO•, HOO•) are formed during fuel cell operation. Out of these species, the highly electrophilic hydroxyl radical is the most reactive (1.8 – 2.7 V vs. NHE). Consequently, the most electron-rich constituents, aromatic rings, are preferentially attacked and undergo rapid degradation. Hydroxyl radical formation rates depend on operating conditions and cell parameters, but even with low formation rates the damage accumulates over time and can lead to thinning or embrittlement of the membrane, and will cause irreversible damage to the cell. Due to these effects, long-term operation becomes challenging. Therefore, membranes with enhanced radical stability are increasingly desirable. In our previous work, we have shown, using kinetics measurements, that it should be possible for Ce(III) to act as a repair agent for formed damaged intermediates (cf. Figure).[1] In our follow-up work we demonstrate that Ce(III) can indeed reduce degradation rates.[2] These experiments were performed in a fuel cell setup using accelerated stress tests at open circuit voltage (OCV), a cell temperature of 80 °C, 100% RH and high H2 and O2 partial pressures of 2 bar. In-situ measurements and post-test analyses unequivocally show that bound Ce(III) can mitigate degradation of poly(α-methylstyrene sulfonate)-based membranes. We believe that this approach could also be applicable for other aromatic-based polymers if a sufficiently long-lived intermediate is formed upon radical attack.

References:

[1] T. de Wild et al., J. Electrochem. Soc.
2021, 168, 054514.

[2] T. de Wild et al., J. Power Sources, submitted

Figure 1
Predicting Fuel Cell Ink Aggregation
Authors: Srivastav Harsh , Weber Adam Z. , Radke Clayton J.
Published: November 2022

Polymer-electrolyte fuel cells (PEFCs) provide multisector decarbonization solutions including in transportation, manufacturing, and long-term energy storage. They have become increasingly popular in these areas due to their high efficiency, power density, and low (or zero) emissions compared to traditional fossil-fuel dependent processes. The PEFC catalyst layer is the most complex and key part of the cell, and is critical for optimizing PEFC performance. Several studies have explored the structure/function relationships of PEFC catalyst layers, yet the physics and interactions controlling its in-situ formation remain a mystery. PEFC catalyst layers are traditionally fabricated out of a catalyst supported on a carbon nanoparticle with an ionomer, traditionally perfluorosulfonic acids (PFSAs) such as Nafion, as a binder, which stabilizes the carbon suspensions in the ink dispersion. Recent studies demonstrated the importance of pH as an experimental parameter for both comparison and characterization of such systems.1

In this talk, we explore the interactions in the colloidal inks through detailed mathematical modeling. We propose a kinetics-based model representing species aggregation with pointwise interacting spheres that vary in charge through buried side chains for predicting the aggregation behavior of Nafion and carbon in solutions under varying conditions, such as solvent, Nafion wt% and carbon wt%. To demonstrate the accuracy and robustness of the model, we compare the results against a range of pH conditions and size distributions. The insights from the model help establish design criteria and guide future ink and process conditions.

Acknowledgements

This study was conducted under the Million Miles Fuel Cell Truck Consortium (M2FCT) funded by the Hydrogen and Fuel Cell Technologies Office in the Energy Efficiency and Renewable Energy Office of the U.S. Department of Energy under contract DE-AC02-05CH11231.

References

S. A. Berlinger, B. D. McCloskey, and A. Z. Weber, J. Phys. Chem. B, 122, 7790–7796 (2018).
Effect of Cobalt Cation Concentration on PEMFC Electrode Performance
Authors: Lee ChungHyuk , Wang Xiaohua , Peng Jui kun , Katzenberg Adlai , Ahluwalia Rajesh , Kusoglu Ahmet , Komini Babu Siddharth , Spendelow Jacob S. , Mukundan Rangachary , Borup Rod L.
Published: November 2022

Metal alloy catalysts, such as Pt-Co, reduce the activation energy of oxygen reduction reaction, leading to improved proton exchange membrane fuel cell (PEMFC) performance. However, leaching of non-noble elements contaminates the ionomer and membrane, which has a negative impact on the durability of PEMFCs [1,2]. For the commercial success of metal alloy catalysts, understanding the mechanisms of how cation contamination affects PEMFC performance is crucial. Here, we investigate the effect of cobalt cation contamination effects through intentional doping of decal electrodes. Electrochemical testing results are coupled with membrane conductivity and water uptake measurements, as well as impedance modeling to identify the mechanisms of performance loss. Our results provide a comprehensive understanding of how cation contamination affects performance, which can inform mitigation strategies and new materials development that can enable the use of metal alloy catalysts in PEMFCs.

Acknowledgement

This work was supported by the Hydrogen and Fuel Cell Technologies Office (HFTO), Office of Energy Efficiency and Renewable Energy, US Department of Energy (DOE) through the Million Mile Fuel Cell Truck (M2FCT) consortia, technology managers G. Kleen and D. Papageorgopoulos. Financial support for this work from the Laboratory Directed Research and Development (LDRD) program at Los Alamos National Laboratory (LANL) is gratefully acknowledged (Projects 2020200DR and 20210915PRD2). ChungHyuk Lee acknowledges the support of the Natural Sciences and Engineering Research Council of Canada (NSERC).

References

Cai et al., ECS Trans., 69, 1047 (2015)

P. Braaten et al., J. Electrochem. Soc., 166, F1337 (2019)

Figure 1
Highly Durable and Active Electrocatalysts Using Pt Nanorod Catalysts Supported on Nb Doped SnO2 for Polymer Electrolyte Fuel Cells
Authors: Kakinuma Katsuyoshi , Shi Guoyu , Uchida Makoto , Iiyama Akihiro
Published: November 2022

In proton exchange membrane fuel cells (PEMFCs) operating with the use of Pt/carbon (Pt/C) cathode catalysts, severe corrosion of the carbon support has been recognized at high potentials. The improvement of the catalyst durability with high activity is required for heavy use applications. Alternative candidate catalysts with high durability and high activity are Pt catalysts supported on non-carbon ceramic supports [1,2]. Our group confirmed that Pt catalysts supported on SnO2 (Pt/M-SnO2, M = Nb, Ta) without carbon additive were superior in durability (startup/shutdown, load cycling) and oxygen reduction reaction (ORR) activity to those of commercial Pt catalysts, e.g., supported on either graphitized carbon black (Pt/GCB, TEC10EA30E, TKK) or carbon black (Pt/CB, TEC10E50E, TKK), by evaluation of membrane-electrode assemblies (MEA) [3-9]. The non-carbon support of SnO2 nanoparticles has a unique carbon-like microstructure consisting of a fused-aggregate network structure, which enhances the electronically conducting pathways via the aggregated microstructure and gas diffusion pathways via the open pores in the microstructure. We have also proposed ways to design the Pt nanorod supported on the Nb-SnO2 based on the catalyst design concept (Fig. 1)[10]. The cell performance using the Pt/SnO2 cathode catalyst layers at operating temperatures from 80oC to 120oC is quite promising for the development of high-power density (Fig. 2) with simultaneous high durability.

Acknowledgments

This work was partially supported by funds for the project “Electrolytes, Catalysts and Catalyst layers with Extraordinary Efficiency, power and Durability for PEFCs-2030 (ECCEED’30) from the New Energy and Industrial Technology Development Organization (NEDO) of Japan, and JSPS KAKENHI Grant Number (20H02839) from the Ministry of Education, Culture, Sports, Science and Technology.

References

A. Masao, S. Noda, F. Takasaki, K. Ito, K. Sasaki, Electrochem. Solid-State Lett., 12, B119 (2009).

E. Fabbri, A. Rabis, R. Kötz, T.J. Schmidt, Phys. Chem. Chem. Phys., 16, 13672 (2014).

K. Kakinuma, M. Uchida, T. Kamino, H. Uchida, M. Watanabe, Electrochim. Acta, 56, 2881 (2011).

Y. Senoo, K. Kakinuma, M. Uchida, H. Uchida, S. Deki, M. Watanabe, RSC Adv., 6, 321800 (2014).

Y. Chino, K. Taniguchi, Y. Senoo, K. Kakinuma, M. Watanabe, M. Uchida, J. Electrochem. Soc., 162, F736 (2015).

K. Kakinuma, R. Kobayashi, A. Iiyama, M. Uchida, J. Electrochem. Soc., 165, J3083 (2018).

K. Kakinuma, K. Suda, R. Kobayashi, T. Tano, C. Arata, I. Amemiya, S. Watanabe, M. Matsumoto, H. Imai,

Iiyama, M. Uchida, ACS Appl. Mater. Interfaces
11, 34957 (2019).

K. Kakinuma, M. Hayashi, T. Hashimoto, A. Iiyama, M. Uchida, ACS Appl. Energy Mater., 3, 6922 (2020).

G. Shi, T. Tano, D.A. Tryk, A. Iiyama, M. Uchida, K.Kakinuma, ACS Catal., 11, 5222 (2021).

Figure 1
Oxygen Reduction Reaction on Fe-N-C Catalysts: A Computational Spectroscopy Study
Authors: Gallenkamp Charlotte , Ni Lingmei , Krewald Vera , Kramm Ulrike I.
Published: November 2022

The oxygen reduction reaction (ORR) plays an important role in proton exchange fuel cells (PEFCs). In PEFCs, ORR is the cathodic half-cell reaction complementary to the oxidation of the fuel, but since ORR has slow kinetics, it requires high amounts of catalyst. State-of-the-art ORR catalysts are based on the expensive metal platinum. Even though the amount of platinum needed for ORR in PEFCs has been reduced significantly over the last decade, it is still the major contributor to the cost of PEFCs, thus hindering the commercialization and accessibility of this technology.[1]

Iron and nitrogen doped carbon (Fe-N-C) catalysts have gained a lot of research attention due to their high ORR activity, which makes them potential substitutes for platinum-based catalysts. In Fe-N-C catalysts, iron is thought to be atomically dispersed as pseudo-molecular active centres with four- or fivefold nitrogen coordination spheres which are embedded in graphene layers. Since Fe-N-C catalysts are typically prepared via pyrolysis, they have a highly amorphous structure and can contain multiple iron phases, which makes them difficult to characterize structurally and spectroscopically. Consequently, there is still a scientific debate on the exact nature of the active site, in terms of iron spin and oxidation states and its precise coordination environment.[2-4]

Fe-57 Mössbauer spectroscopy can provide direct insights on iron spin and oxidation states and is used successfully to characterise the amorphous Fe-N-C catalysts. Until recently, the interpretation of Mössbauer spectra was limited to comparisons with small reference complexes which lack the extended π-systems of Fe-N-C catalysts.[2] Since synthesis of such extended π-systems as references is difficult, we have developed a library of computational models that encompasses different structural motifs and electronic structures. With increasing use of in situ and operando experiments on Fe-N-C catalysts, the interest in computational models for the interpretation of experimental Mössbauer spectra has grown.[4-6] In this contribution, we present our density functional theory results for different molecular Fe-N-C models with extended π-systems and discuss their electronic structures and spectroscopic properties.

[1] L. Osmieri, et al. Current Opinion in Electrochemistry
2021, 25, 100627.

[2] U. I. Kramm, et al. Advanced Materials
2019, 31, 1805623.

[3] S. Wagner, et al. Angewandte Chemie International Edition
2019, 58, 10486.

[4] L. Ni, C. Gallenkamp, et al. Advanced Energy & Sustainability Research
2021, 2, 2000064.

[5] J. Li, et al. Nature Catalysis, 2021, 4, 10.

[6] X. Liu, et al. Chem
2020, 6, 3440.
Elucidating Activity-Stability Trade-Off to Design Highly Durable Fe-N-C Catalysts
Authors: Zeng Yachao , Li Chenzhao , Zachman Michael J. , Cullen David A. , Xie Jian , Myers Deborah J. , Wu Gang
Published: November 2022

In this work, we developed a Fe2O3@ZIF-8 composite precursors and combined with a novel thermal activation treatment under an Ar/H2 mixture atmosphere (i.e., forming gas), which successfully prepares a highly active Fe-N-C catalyst. 57Fe Mossbauer spectroscopy analysis experimentally verified that the catalyst only contains S1 sites. The highly active Fe-N-C catalyst achieved exceptional ORR initial activity in acids, exceeding that of a Pt/C baseline catalyst (60 µgPt cm−2) in rotating disk electrode (RDE) tests. The MEA tests further verified that the Fe-N-C catalyst's activity is competitive with Pt/C cathode (0.1 mgPt cm−2) in the kinetic range. Notably, the catalyst demonstrated remarkable activity of 50.8 mA cm−2 (@0.9 ViR-free) under H2-O2 conditions, exceed the U.S. DOE target. As expected, the catalyst degraded significantly during the stability ASTs.

To increase S1 sites and address the stability issues, we further developed in-situ CVD methods to treat Fe2O3@ZIF-8 precursors under forming gas flow but with additional N/C precursors that was put at the upstream sides of the tube furnace. Therefore, additional nitrogen and carbon sources are added to the Fe2O3@ZIF-8 precursors during the thermal activation of catalysts. As a results, we can populate the intrinsically stable S2 sites to design highly durable Fe-N-C catalyst. The resulting catalyst presented outstanding stability in both RDE and fuel cell tests. The E
1/2 gained 21 mV after 100,000 cycles of accelerated degradation test (ADT), achieving 0.869 VRHE at the end of the test, which is close to Pt/C (60 µgPt cm−2) in acid electrolyte. The current density of MEA at 0.8 V retained unchanged, and the peak power density increased from 454.0 to 512.0 mW cm−2 in H2-fuel cell after 30,000 cycles of AST.
(Invited) Durability and Accelerated Aging of Anion-Conducting Membranes and Ionomers
Authors: Nellithala Dheeraj , Shah Parin , Kohl Paul
Published: November 2022

Low-temperature, polymer-based fuel cells and water electrolyzers using anion conductive polymers have several potential advantages over acid-based polymer electrolyzers. However, the long-term durability of the ion conducting polymer has not been investigated to the same extent as proton conducting polymers. Further, accelerated aging test conditions with known acceleration factors have not been developed.

In this study, a family of poly(norbornene) polymers used in fuel cells and electrolyzers was aged under a variety of conditions to determine the aging rate and acceleration factors. In particular, the relationship between temperature, alkalinity, and time were investigated.
(Invited) Novel Materials and Operando Methods for Alkaline Electrocatalysis
Authors: Abruna Hector
Published: November 2022

This presentation will deal with the development of new materials and operando methods for electrocatalysis in alkaline media. The presentation will begin with a brief overview of the methods employed with emphasis on the use of X-ray based methods and transmission electron microscopy (TEM) under active potential control. The utility of these methods will be illustrated with selected examples focusing on non-precious metal oxides and nitrides as electrocatalysts for the oxygen reduction reaction (ORR), and Ni based systems for the HOR. Fuel cell (MEA) testing of integrated systems employing non-precious metal electrocatalysts will also be discussed. The presentation will conclude with an assessment of future directions.
Nanostructured Materials as a Dopant to Enhance Polymer Electrolyte Membranes for Alcohol Fuel Cell Application
Authors: Msomi Phumlani Fortune
Published: November 2022

A series of polymer electrolyte based on hydrocarbon polymers and Nafion doped with different nanomaterials were prepared and investigated. Nanomaterials based on graphene oxide, ZiF-8, TiO2, nanofibers and zirconium were used to enhance properties of different hydrocarbons and Nafion and tested for their basic properties. The water uptake, swelling ratio, ion exchange capacity, ion conductivity (IC) and thermal stability of the AEMs increased with increasing content of nanostructured materials. The presence of the nanostructured materials can lead to an increase in the interfacial area of the organic-inorganic phases, which creates a significant volume fraction of the interfacial polymer. The large free volume created is beneficial for the water molecule storing and conducting moieties mobility. The nanostructures materials can also act as Lewis acid sites to store and provide extra water to the membrane and has the ability to reduce the crystalline nature of the membrane and therefore increasing the ionic conductivity and lead to an alkaline stable and durable polymer electrolyte.
(Invited) Dynamic Electrochemical Responses of "Dead Li" during Battery Operations
Authors: Liu Fang , Cui Yi
Published: November 2022

The increasing demand for next-generation energy storage systems necessitates the development of high-performance lithium batteries. Unfortunately, current Li anodes exhibit rapid capacity decay and a short cycle life, owing to the continuous generation of solid electrolyte interface and isolated Li (i-Li). The formation of i-Li during the nonuniform dissolution of Li dendrites leads to a substantial capacity loss in lithium batteries under most testing conditions. Because i-Li loses electrical connection with the current collector, it has been considered electrochemically inactive or ‘dead’ in batteries. Contradicting this commonly accepted presumption, here we show that i-Li is highly responsive to battery operations, owing to its dynamic polarization to the electric field in the electrolyte. Simultaneous Li deposition and dissolution occurs on two ends of the i-Li, leading to its spatial progression toward the cathode (anode) during charge (discharge). Revealed by our simulation results, the progression rate of i-Li is mainly affected by its length, orientation, and the applied current density. Moreover, we successfully demonstrate the recovery of i-Li in Cu–Li cells with >100% Coulombic efficiency and realize LiNi0.5Mn0.3Co0.2O2 (NMC)–Li full cells with extended cycle life.
Electrode Potential Influences The Reversibility of Lithium Metal Anodes
Authors: Ko Seongjae , Obukata Tomohiro , Shimada Tatau , Takenaka Norio , Nakayama Masanobu , Yamada Yuki , Yamada Atsuo
Published: November 2022

Li-metal batteries are considered an ultimate energy-storage device since a Li metal anode presents high capacity and low redox potential.1 However, a poor Coulombic efficiency (CE) during a plating/stripping of Li metal, has hampered their commercialization. To overcome this issue, a diverse type of electrolytes, which forms a robust solid electrolyte interphase (SEI) on the Li-metal surface, has been introduced over the past decade.2 However, a correlation between the CE and SEI chemistry is still vague since it is mostly established on the basis of indirect experimental methodologies. Indeed, a huge change in CEs has been reported even in the presence of similar functional-SEIs, indicating that there is another essential factor that governs the CE.3

Fundamentally, the redox potential of Li metal is located far outside the thermodynamic potential window of organic electrolytes, thus inevitably inducing reductive degradation of the electrolyte. Importantly, the Li metal is known as a quasi-reference electrode, which indicates its redox potential strongly depends on the chemical potential of Li+ in the electrolyte. Thus, if the redox potential of Li metal is upshifted to narrow the gap from the potential window of the electrolyte, the CE should be increased with thermodynamically mitigated electrolyte decomposition.

Based on this assumption, the Li redox potential (V vs. electrolyte-independent redox system, ferrocene Fc/Fc+) was evaluated and plotted versus the average CEs of Li plating/stripping reactions in 74 different electrolytes. The result presents that the average CE is increased as an increase of the redox potential of Li metal that varies over 0.6 V depending on the electrolytes, demonstrating that the degree of the reductive degradation of electrolyte is governed by the redox potential of Li metal in the given electrolyte. The mechanism behind the redox potential variation of Li metal was studied with both machine-learning analysis and Raman spectroscopy. Obviously, the coordination states of Li+ and FSI- shows a high relevance for the Li redox potential. Specifically, as an increase of Li+-FSI- ion-pairing, the redox potential of Li metal is upshifted gradually.

In conclusion, we postulate that a large variation of Li electrode potential (>0.6 V), which is deeply linked to the coordination condition of Li+ and FSI- in the electrolyte, is a simple yet overlooked ‘hidden factor’ that dominates Li-metal battery performance. This rationale will provide a new chance to design a stable Li-metal batteries.

Reference

1. D. Lin et al., Nat. Nanotechnol., 12, 194–206 (2017).

2. S.C. Kim et al., J. Am. Chem. Soc., 143, 18703−18713 (2021).

3. G. M. Hobold et al., Nat. Energy, 6, 951–960 (2021).
Mechanistic Understanding of Lithium Plating/Stripping Processes on the 3D Conductive Host Based on Vertically Aligned Carbon Nanofibers for Li Metal Anode
Authors: Rajendran Sabari , Li Jun
Published: November 2022

The highest theoretical capacity (3860 mAh/g) and lowest redox potential (-3.04 V vs standard hydrogen electrode) makes lithium metal as a promising anode for next generation high energy density batteries.1 Despite theoretical advantages, there are challenges in commercializing Li metal anodes such as low coulombic efficiency, dendrite formation and poor cycling life. Dendrite formation can cause short circuit and thermal runaway, which is a safety concern. Among the various ways to mitigate the Li dendrite formation, using three-dimensional (3D) current collectors with lithiophilic properties and low tortuous pore architecture is an effective way. It would decrease the local current density owing to high active surface area while accommodating the large volume change during prolonged charge/discharge cycles.

Vertically aligned carbon nanofibers (VACNF) have been demonstrated as a promising candidate as a lithiophilic 3D host for lithium metal anodes as they possess unique conically stacked lithiophilic graphitic edges with O containing functional groups and high N doping (~6.5 at%).2 However, a fundamental, deeper understanding of the Li plating/stripping processes on such 3D electrodes has not been developed yet. Here in, we investigate the lithium nucleation and growth processes and its morphological changes using ex-situ structural characterization techniques such as SEM and cryo-TEM. The composition of the solid electrolyte interface is investigated using XPS. In-situ Raman spectroscopic studies provided further information about the changes that occur in the VACNFs during Li plating/stripping processes and Li intercalation/deintercalation processes. Ion-beam sputtering of an ultrathin gold layer onto the VACNFs was found to further improve the lithiophilicity of the 3D electrode and lead to more reversible Li metal plating/stripping. The new insights on the electrodeposition of lithium in 3D electrodes and its relationship with the enhanced cycle life acquired using various analytical tools will be discussed.

Reference:

(1) Manthiram, A.; Chung, S.-H.; Zu, C. Lithium–Sulfur Batteries: Progress and Prospects. Advanced Materials
2015, 27 (12), 1980–2006.

(2) Chen, Y.; Elangovan, A.; Zeng, D.; Zhang, Y.; Ke, H.; Li, J.; Sun, Y.; Cheng, H. Vertically Aligned Carbon Nanofibers on Cu Foil as a 3D Current Collector for Reversible Li Plating/Stripping toward High-Performance Li–S Batteries. Advanced Functional Materials
2020, 30 (4), 1906444.
Electrochemical-Mechanical Coupling at Li Metal / Solid Electrolyte Interfaces and the Safety of Li Metal Solid-State Batteries
Authors: Albertus Paul , Johnson Nathan B , Bhargava Bhuvsmita , Song Yueming , Carmona Eric A , Larson Karl
Published: November 2022

Using Li and Na metal with a solid electrolyte in high-energy and safe batteries for consumer applications is of great interest, but our understanding of the behavior of this interface, as well as the expected safety of high-energy cells built with Li or Na metal and a solid electrolyte, requires improvement. In this talk I will describe (1) our work in both modeling and measuring electrochemical-mechanical coupling at a Li or Na metal / solid electrolyte interface, as well as (2) modeling and experimental work on Li metal solid state battery safety.

The electrochemical-mechanical coupling topic (1) will focus on the influence on the current distribution of expected mechanical loadings at a metal/solid electrolyte influence, taking into account the expected plastic deformation of the metal electrode. We find that the mechanical boundary conditions, and inclusion of plastic deformation of a metal electrode such as Na or Li, strongly influences the resulting impact on the interfacial current distribution. Our approach and recent experimental work for parameterizing and validating electrochemical-mechanical coupling will also be presented. Here, we focus on interfacial characterization and methods to study thin films of solid state battery materials under well-defined mechanical loads.

The solid-state battery topic (2) will focus on a quantitative understanding of temperature rise in Li metal solid state batteries, based on the thermochemistry of the reactions that occur upon heating due to an external source (e.g., an oven test) or an internal short. Previously reported differential scanning calorimetry experiments as well as those we collect provide heat flows vs. temperature for the reactions among cell components (e.g., Li metal, cathode powder, solid electrolyte, cathode binder and conductive additive, current collectors). This data serves as a basis for modeling temperature rise in large-format cells. We find that oxygen release from metal oxide cathodes that reacts with molten Li in the cell can drive significant temperature rise, and discuss methods to improve the safety of Li metal solid state batteries.
High-Energy and Long-Lasting Lithium Metal Batteries Employing Garnet-Type Solid Electrolytes with Tailored Lithium Metal Compatibility
Authors: Kim Sewon , Kim Jusik , Im Dongmin , Kang Kisuk
Published: November 2022

One of the viable options to significantly augment the energy density of lithium-ion batteries (LIBs) is to adopt lithium metal anode in the cell, which offers the highest theoretical capacity (3,860 mAh g-1) among anode materials.1 However, the practical obstacles such as dendrite growth, low Coulombic efficiency, and safety issues still remain unresolved, despite the extensive efforts to employ the lithium metal anode in LIBs.2 Recent progress in solid-state electrolyte development has granted a new promising opportunity for the utilization of lithium metal anodes, whose mechanical rigidity and non-flammable nature are supposed to effectively suppress lithium dendrite short-circuiting, thereby securing battery safety. Nevertheless, there has been no report thus far that demonstrates acceptable levels of electrochemical performance of solid-state lithium metal batteries for real-world applications.3,4

In our research, a lithium-metal-battery employing tailored garnet-type Li7-xLa3-aZr2-bO12 (LLZO) solid-electrolytes that can meet the lifespan requirements of both electric vehicles and stationary applications has been achieved, affording remarkable stability and energy density over 2,000 cycles. It is demonstrated that the compatibility between LLZO and lithium metal is crucial for the long-term stability, which can be accomplished by regulating bulk dopants and the corresponding dopant-specific interfacial treatment using protonation/etching. The appropriate selection of dopant and dopant-specific protonation/etching agent for LLZO leads to (i) the formation of a stable passivation layer at the interface with lithium metal, (ii) effective release of residual stress in LLZO, and (iii) intact contact at the interface.

The lithium-metal cell with 2 mAh cm-2 cathode (12 mg cm-2) delivers a cumulative capacity of over 4,000 mAh cm-2 at 3 mA cm-2, which to the best of our knowledge, is the highest long-term cycle value reported for lithium metal batteries with LLZO electrolytes. Moreover, even with the thin 110-µm-LLZO electrolyte and 20-µm lithium metal, a high-loading-capacity cell (3.2 mAh cm-2) exhibits a superior cycle life (>600 cycles) at 2 mA cm-2 without short-circuiting, affording a basis for the high-energy-cell design with ultra-thin electrolyte. In addition, an all-solid-state-battery, excluding the ionic liquid electrolyte, was successfully demonstrated using the composite cathode, which could cycle over 1,000 times at a high current density of 3 mA cm-2 without short-circuiting. To the best of our knowledge, this is the first all-solid-state battery that can operate over 1,000 cycles, enabled by the garnet-type electrolytes and cathode with a commercially acceptable capacity.

These findings are expected to open a new avenue for developing long-lasting solid-state lithium metal batteries by highlighting the efficacy of the coupled bulk and interface doping of solid electrolytes.
Structural Analysis of LiCoPO4 Electrode/Nasicon-Type Li1.3Al0.3Ti1.7(PO4)3 Solid Electrolyte Interface
Authors: Ichihara Fumihiko , Niitsu Kodai , Miyoshi Shogo , Mitsuishi Kazutaka , Masuda Takuya
Published: November 2022

All-solid-state lithium-ion batteries (ASSLIBs) with oxide-based solid electrolytes are a promising candidate for next generation of rechargeable batteries, due to their reliability and high-energy density. The formation of well-defined electrode/solid electrolyte interfaces with an excellent ionic conductivity by co-sintering is one of the key challenges to develop oxide-based ASSLIBs.1 Electrode materials and solid electrolytes often react with each other to form a resistive substance at their interface during co-sintering.2-4 Thus, optimization of the co-sintering conditions is important to control the interfacial structure which governs the ionic conductivity. However, the effect of the interfacial structure on the ionic conductivity remains unclear.

In this study, we co-sintered the composites of LiCoPO4 (LCP) electrode material and Li1.3Al0.3Ti1.7(PO4)3 (LATP) oxide-based solid electrolyte and investigated the interfacial structure by using X-ray diffraction (XRD), X-ray absorption fine structure (XAFS) and scanning transmission electron microscopy combined with electron energy loss spectroscopy and an energy-dispersive X-ray spectroscopy (STEM-EELS/EDX).

Figure 1(a) shows the XRD patterns of the LCP/LATP composites before and after sintering at 800°C. The diffraction patterns are almost identical to each other and all the diffraction peaks are attributed to the LCP and LATP with an exception of AlPO4 impurity. However, the Co K-edge XANES is slightly changed after sintering as shown in Figure 1(b). These results suggest that a small amount of LCP and LATP react with each other. Figure 1(c) shows a typical STEM image of the LCP/LATP composites after sintering at 800°C. According to EDX analysis, light and dark gray domains correspond to LCP and LATP, respectively. Apart from LCP and LATP, there are two types of LCP/LATP interfaces: interface A and B. Line profile STEM-EELS/EDX analysis revealed that LCP and LATP directly bound to each other at the interface A. On the other hand, a thermally reacted thin layer, possibly cobalt oxide (CoO) and/or cobalt phosphide (Co2P), is formed at interface B. The effect of such thermally reacted interlayer on the ionic conductivity will be discussed in detail.

References:

R. Chen, Q. Li, X. Yu, L. Chen and H. Li, Chemical Reviews, 2020, 120, 6820-6877.

M. Gellert, E. Dashjav, D. Grüner, Q. Ma and F. Tietz, Ionics, 2017, 24, 1001-1006.

C.-Y. Yu, J. Choi, V. Anandan and J.-H. Kim, The Journal of Physical Chemistry C, 2020, 124, 14963-14971.

L. Miara, A. Windmuller, C. L. Tsai, W. D. Richards, Q. Ma, S. Uhlenbruck, O. Guillon and G. Ceder, ACS Applied Materials and Interfaces, 2016, 8, 26842-26850.

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Understanding and Evaluating the Design Space for Practical Solid-State Batteries
Authors: Dixit Marm , Amin Ruhul , Parejiya Anand , Essehli Rachid , Muralidharan Nitin , Belharouak Ilias
Published: November 2022

Solid-state batteries are promising alternatives for high-energy and -power-density rechargeable battery applications. It is vital to design and engineer SSB cells that can compete and improve on the current Li-ion battery counterparts. However, limited approaches exist today to assess and extrapolate the impact of battery designs and choices of cell components on the cell-level energy density of a solid-state battery. Herein, we introduce the Solid-State Battery Performance Analyzer and Calculator (SolidPAC), an interactive experimental toolkit to enable the design of a solid-state battery for user-specified application requirements. The toolkit is flexible enough to assist the battery community in quantifying the impact of materials chemistry and fractions, electrode thicknesses and loadings, and electron flows on cell energy density and costs and in utilizing inverse engineering concepts to correlate the cell energy density output to materials and cell design inputs. In addition to this, we will discuss a geometric modeling of composite cathode architectures to assess its impact on cell-level energy densities. Impact of packing architecture on processing parameters of a given cathode composition and thickness, as well as on achievable energy density is evaluated for a range of commonly used solid electrolyte and cathode materials. Overall, the proposed framework offers a facile exploratory methodology for establishing initial metrics for scalable processing of practical and competent SSBs.
Solid-State Electrolyte Fracture in Lithium Metal Batteries
Authors: Carmona Eric A , Albertus Paul
Published: November 2022

Next generation batteries utilizing solid-state electrolytes to enable use of lithium metal electrodes are of significant interest due to increased energy density and the potential safety enhancements. Despite their high yield strength, high room temperature ionic conductivity, and lack of reactivity with metallic lithium, these ceramic solid electrolytes are still prone to dendrite formation and subsequent cell failure above critical current densities. One experimentally observed dendrite formation and propagation mechanism requires mechanical failure of the electrolyte via fracture. Ceramic solid electrolyte’s do not undergo ductile deformation, leaving fracture as the primary means of stress relaxation. The electrolyte’s propensity to fracture is dependent on its material properties (i.e. fracture toughness), electrode mechanical properties, and the cell operating conditions (e.g. applied current density, stack pressure, temperature). This talk will focus on electrochemical-mechanical coupling (including thermodynamic and kinetic couplings of mechanical forces with electrochemical behavior) and the relationship between the current distribution, developed stresses, and solid-electrolyte fracture initiation at Li protrusions. The effect of current focusing on stress-driven fracture, plastic deformation of lithium, and the influence of mechanical boundary conditions will be described.
Antimony Telluride Nanocomposite As a High Performance Anode for Rechargeable Potassium-Ion Batteries
Authors: Verma Rakesh , Moon Chae-Eun , Park Chan-Jin
Published: November 2022

The development of high-capacity and low-cost energy storage systems are a top priority in electric vehicles and smart grids. Room temperature potassium-ion batteries (PIBs), which have the advantages of high theoretical capacity, abundant earth reserves, and low potassium costs, have recently emerged as an appealing alternative to traditional lithium-ion batteries (LIBs). In particular, finding advanced anode materials with suitable operation potential and high capacity is of significance for next-generation PIBs. In this regard, Sb-based materials have recently gained popularity as promising anode materials for batteries in terms of their suitable working potential, high density, and theoretical capacity. Among them, Sb2Te3 has a much higher density (6.66 g/cm3) than other Sb-based materials such as Sb2O3, Sb2S3, and Sb2Se3. This suggests that Sb2Te3 can have a high theoretical capacity. In addition, Te exhibits a higher conductivity than S or Se. Accordingly, the Sb2Te3 is appealing as an ideal anode for PIBs. Unfortunately, the Sb2Se3 has poor cycling stability and rate performances, which is primarily owing to the large volume change during alloying and dealloying.

In this study, using a simple hydrothermal strategy, we synthesized a carbon-coated Sb2Te3 nanocomposite (Sb2Te3@C). In the novel design, the Sb2Te3@C nanocomposite is compactly encapsulated by a uniform carbon layer, which effectively relieves structural stress leading to preventing structural pulverization and stabilize the solid electrolyte interface layer. As expected with this optimal design, the Sb2Te3@C nanocomposite electrode performed nicely suitable for PIBs. In addition, the effect of the alloying/dealloying process on the crystal structure of Sb2Te3@C was investigated using in- situ/ex-situ XRD patterns recorded at various stages of discharge and charge to clarify the alloying mechanism. Furthermore, a full cell made up of a Sb2Te3@C anode and a potassium Prussian blue type cathode also exhibited successful operation.
Stabilizing LATP Electrolyte Interface of All-Solid-State Lithium Ion Batteries Consisting of High-Voltage Cathode
Authors: Kang DongJae , Lim Hyung-Tae
Published: November 2022

NASICON-type Li1.3Al0.3Ti1.7(PO4)3 (LATP) solid electrolyte has been investigated because of its stability in the air and water and wide electrochemical window, which make it a suitable electrolyte material to be used with a high-voltage cathode material. However, LATP solid electrolyte has interfacial problems, as in LiCoO2/LATP results in a limited contact area and Li/LATP suffers from structural collapse due to side reactions.

In the present study, we inserted PEO polymer electrolyte to suppress the Li/LATP interface side reactions and mitigate the LiCoO2/LATP interfacial resistance. We prepared symmetric & full cells with PEO coated on both sides of electrolyte. The symmetric cell consisted of Li/PEO/LATP/PEO/Li and full cell consisted of Li/PEO/LATP/PEO/LiCoO2. The symmetric cell exhibited stable cycling behavior at current density 0.1mA/cm2 for 2000h at 60℃. The full cell charge capacity showed 151.71mAh/g in voltage range of 3.0~4.2V at 60℃ at 0.1C rate. Therefore, PEO protecting layer is effective for stable cycling performance.

Keyword:

All-solid-state Batteries, LATP Solid Electrolyte, Li/LATP Interface, LiCoO2/LATP Interface, PEO polymer electrolyte
Sodium Ion Flexible Battery in Poly-Acrylic Acid with Vinyl Silica Nano Particle Gel Electrolyte
Authors: Kim Junsu , Park Jeonghee , Rana Harpalsinh , Kim Junsu
Published: November 2022

Sodium Ion flexible battery in Poly-Acrylic Acid with Vinyl Silica Nano Particle Gel Electrolyte

Sodium ion Battery(SIB) has much interesting due to abundance of sodium in earth's crust and low cost. To improve the performance of SIB with gel electrolyte, the poly-Acrylic Acid (PAA) cross-linked with Vinyl Silica Nano Particle (VSNP) was used as gel electrolyte hamper electrode material dissolution. The VSNP was used as cross-linker and synthesized by Sol-Gel method with Vinyltriethoxysilane (VTES) to improve the mechanical strength of gel. Fourier-Transform Infrared Spectroscopy (FTIR) and Scanning Electron Microscope (SEM) was used to analyze C=C bond and morphology of VSNP. PAA gel was polymerized by radical polymerizaiotn with VSNP cross-linker. To measure electrochemical property, SIHC was fabricated with Na3V2(PO4)3 (NVP) cathode material and Activated Carbon (YP50F) anode material. Electrochemical Impedance Spectroscopy (EIS) was used to analyze interfaces-contact with electrode and electrolyte. After measure electrochemical property, X-ray Diffraction was measured to characterize the NVP crystallinity. By this research, It can propose the way how apply to flexible sodium ion flexible battery and gel electrolyte
Compact Sulfurized-Polyacrylonitrile/Graphene Composite Cathode for High-Energy and Long-Life Li-S Batteries
Authors: Kim Hun , Choi Ha-Neul , Jeong Kyung-Min , Sun Yang-Kook
Published: November 2022

Next-generation batteries have been in the spotlight to meet the demand for batteries with higher energy densities than commercial lithium-ion batteries. Among them, lithium-sulfur batteries have been actively investigated owing to their attractive features; 1) Ultrahigh energy density, 2) Low cost of sulfur. Herein, we propose a compact, high-performance, 2D sulfurized-polyacrylonitrile/graphene (2D-SPAN/G) cathode for practical Li–S batteries. A 2D-SPAN/G cathode with a high active-mass (sulfur) loading of 10 mg cm−2 is successfully prepared via high-pressure pelletization. In the 2D-SPAN/G cathode, graphene nanosheets function as a robust and conductive scaffold, which uniformly encapsulates SPAN nanoparticles, providing structural integrity and enabling the high electrochemical utilization of sulfur. Combined with the stabilized lithium metal anode by using a modified electrolyte (consisting of 1 M LiPF6 and 0.05 M LiDFOB in EMC:FEC (3:1 (v/v))), and a 2D-SPAN/G cathode delivers a high areal capacity of 11 mAh cm−2 and demonstrats outstanding cycling stability over 300 cycles at a high current density of 4 mA cm−2. Moreover, the excellent electrochemical performance of a scaled-up, pouch-type Li–S battery featuring a 2D-SPAN/G cathode demonstrats the viability of the proposed cathode. The reversibility of the Li+-ion storage mechanism of the 2D-SPAN/G cathode is confirmed using operando Raman spectroscopy.

Reference
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[1] J.-Y. Hwang, S.-J. Park, C. S. Yoon and Y.-K. Sun, Energy Environ. Sci., 2019, 12, 2174–2184.

[2] H. Kim, S. Bang, K.-J. Min, Y.-G. Ham, S.-J. Park and Y.-K. Sun, ACS Appl. Mater. Interfaces, 2021, 13, 39435–39445.

[3] H. M. Kim, J.-Y. Hwang, D. Aurbach and Y.-K. Sun, J. Phys. Chem. Lett., 2017, 8, 5331–5337.