bluuebunny/crossref_metadata_2025 huggingface dataset:
Enhanced Oxygen Evolution Reaction Activity of Iridium Nanostructure Supported on Mesoporous Tantalum Oxide By the SMSI Effect
Authors: Baik Chaekyung , Cha Jeong In , Pak Chanho
Published: November 2022

The proton exchange membrane water electrolysis (PEMWE), which transforms the surplus electric energy into a form of transportable hydrogen energy, has been attracting significant attention. PEMWE has the benefits of fast response, high current operation, and gas purity compared to alkaline water electrolysis. Thus PEMWE is more suitable for hydrogen production using fluctuated renewable energies. Since iridium oxide (IrO2) catalysts are stable and fairly active in the water oxidation reaction, researchers have been focusing on increasing the activity and stability of iridium-based catalysts while reducing Ir loading level by developing binary oxide or dispersing on metal oxides [1,2]. To replace carbon support in PEMWE anode, metal oxide supports that are stable to harsh OER conditions such as titanium, neodymium, and tantalum oxides were studied for enhancing electrical conductivity with high surface area [2,3]. In this study, mesoporous Ta2O5 with a high surface area (> 100m2/g) was synthesized through the soft-template method. The Ir nanoparticles were supported on porous Ta2O5 by the formic reduction method. The self-assembling characteristic of the reduction method is attributed to the Ir coated structure of Ta2O5. XPS analysis showed the oxidation states of Ir(0) with Ta(IV) with peak shift owing to strong metal-support interaction (SMSI). The uniform Ir dispersion on the support improved electrical conductivity and electrochemically active surface area (ECSA). The electron transfers from Ta to Ir maintained high Ir3+ composition during the OER. The improved OER activity (288 mV/cm2) and mass activity (898 A/g at 1.55 V) indicates that Ta2O5 support efficiently can reduce the Ir loading levels and it was also demonstrated in MEA performance under PEMWE conditions.

References

[1] C. Ma, W. Sun, W. Qamar Zaman, Z. Zhou, H. Zhang, Q. Shen, L. Cao and J. Yang, ACS Appl. Mater. Interfaces, 12, 34980-34989 (2020).

[2] H.-S Oh, H.N. Nong, T. Reier, A. Bergmann, M. Gliech, J. Gerreira de Araújo, E. Willinger, R. Schlogl, D. Teschner, P. Strasser, J. Am. Chem. Soc., 138, 12552-12563 (2016).

[3] E. Oakton, D. Lebedev, M. Povia, D.F. Abbott, E. Fabbri, A. Fedorov, M. Nachtegaal, C. Copéret, T.J. Schmidt, ACS Catal., 7, 2346-2352 (2017).
High Resolution Characterization of Proton Exchange Membrane Water Electrolysis Anodes
Authors: Ferner Kara , Park Janghoon , Kang Zhenye , Mauger Scott A , Ulsh Michael , Bender Guido , Litster Shawn
Published: November 2022

The current use of expensive and geographically-limited precious metal catalysts, typically iridium, in proton exchange membrane water electrolyzer (PEMWE) anodes is necessary to accelerate the sluggish oxygen evolution reaction (OER). However, high loadings of iridium catalyst drastically increase the capital costs of PEM electrolysis, while low loadings of iridium lead to a significant decline in the efficiency of hydrogen production. Thus, PEMWE anode fabrication methods must be optimized to achieve the highest performance with lower iridium loadings. Using high resolution characterization methods, we show nanoscale differences in anode morphology between different IrO2 anode fabrication methods, such as spray coated versus blade coated anodes. We also explore the evolution of the electrode morphology throughout its fabrication and testing lifetime. The characterization methods used in this work include high resolution nanoscale X-ray computed tomography (nano-CT) as well as plasma-focused ion beam cross-sectioning and scanning electron microscopy (pFIB-SEM). Additionally, we present quantitative data such as solid particle and pore size distributions as well as pore network extractions derived from our image-based characterizations to elucidate the morphological differences between IrO2 anodes.

This conference presentation was developed based upon funding from the Alliance for Sustainable Energy, LLC, Managing and Operating Contractor for the National Renewable Energy Laboratory for the U.S. Department of Energy.
Ruthenium-Zirconium Oxides As Highly Stable Oxygen Evolution Electrocatalysts
Authors: Albiter Luis A , Bailey Kathleen O. , Godinez Salomon Jose Fernando , Rhodes Christopher P.
Published: November 2022

The further development and utilization of proton exchange membrane water electrolyzers (PEMWEs) is hindered by the cost, activity, and stability of the oxygen evolution reaction (OER) electrocatalyst. Iridium oxide (IrOx) is currently the go-to OER electrocatalyst, as it has been shown to have relative high activity and stability when compared to other OER active catalysts. However, iridium is one of the rarest elements in the Earth’s crust and therefore cost is a major limitation of iridium-based electrocatalysts. Ruthenium oxide (RuO2) is a highly active OER catalyst; although, it is highly unstable in acidic media and undergoes catalyst degradation over time. We investigated modifying RuO2 by substituting zirconium, which is highly stable in acidic conditions, to provide an electrocatalyst with increased stability. Our study explored the effect of low and moderate zirconium concentrations within RuO2 (Ru1-xZrxO2) on the structure, morphology, OER activity, and stability. The structure and morphology were characterized by X-ray diffraction and scanning electron microscopy. Preliminary results from XRD showed no observable phase separation at low Zr concentrations, and peak shifts were indicative of the incorporation of the larger Zr ion into the crystal structure of rutile RuO2. The OER activities and stabilities of Ru1-xZrxO2 were measured using a rotating disk electrode configuration and compared with RuO2. Our preliminary results show that the OER activity and stability are strongly affected by the addition of Zr and there may be an optimal concentration range for obtaining a balance between OER activity and stability. Our work furthers the understanding of how to develop OER electrocatalysts with increased stability while maintaining a high OER activity, which is crucial to the large-scale adoption of PEMWE’s.
Effects of Titanium Substitution within Ruthenium Oxide on Structure, Oxygen Evolution Activity and Stability
Authors: Rhodes Christopher P. , Godinez Salomon Jose Fernando , Albiter Luis A , Bailey Kathleen O. , Naymik Zachary G. , Ospina Acevedo Francisco A , Balbuena Perla B.
Published: November 2022

The development of acidic oxygen evolution reaction (OER) electrocatalysts with high activity, extended durability, and lower costs furthers the development and utilization of proton-exchange membrane (PEM) water electrolyzers. Although iridium-based catalysts are currently the primary OER catalysts used within PEM electrolyzers, ruthenium has a higher activity, lower cost, and higher global supply compared to iridium; however, ruthenium-based catalysts generally have lower stability compared to iridium-based catalysts. Within acidic OER catalysts, stability remains a significant challenge for non-iridium materials, particularly under the highly corrosive environment of highly acidic conditions and high anodic potentials encountered during PEM water electrolysis. As an approach to obtain high OER activity and improved stability, we investigated the effect of titanium substitution within rutile ruthenium oxide as a model system of oxide structure that combines a highly OER active, unstable element (Ru) with a highly stable but OER-inactive element (Ti). Titanium-substituted ruthenium oxides, Ru1-xTixO2, at different Ti substitution ratios were synthesized via wet-chemistry and subsequent thermal treatments. X-ray diffraction analysis and high resolution transmission electron microscopy images support Ti is substituted within the RuO2 structure. X-ray photoelectron spectroscopy of core and valence bands shows Ti substitution alters the surface electronic structure. From rotating disk electrode measurements, Ti substitution lowers the OER mass activity, OER specific activity, and electrochemical surface area. In addition to affecting OER activity, Ti substitution increases the OER stability and lowers Ru dissolution. Density functional theory (DFT) calculations of the titanium-substituted ruthenium oxides show that effects of Ti substitution on the reaction energies and activation energies are highly dependent on the site. Theoretical analysis supports that specific sites may predominately act as catalytic sites for the OER, while other sites influence metal dissolution. Further understanding how the structure of bimetallic oxides influences OER activity and stability provides a pathway to electrocatalysts with higher activity, improved stability, and lower cost.
Stochastic Generation of Electrolyzer Catalyst Layers
Authors: Seip Tess , Lee Keonhag Keonhag , Shaigan Nima , Dinu Marius , Fatih Khalid , Bazylak Aimy
Published: November 2022

Developing clean energy technologies, such as polymer electrolyte membrane electrolysis (PEMWE), is essential to mitigate the negative impacts of climate change. However, one persistent barrier to PEMWE uptake is high catalyst costs, which can account for up to 47% of total stack costs [1]. This makes the catalyst a key target for cost savings via material optimization, as the mechanisms linking structure, mass transport, and charge transport remain relatively ambiguous in the literature [2], [3]. Previous studies have explored stochastic material generation and pore network modelling in the porous transport layer (PTL), but such analysis has yet to be performed for the bulk catalyst layer [4].

In this study, we introduced a method for replicating the complex pore structure observed in commercially available catalyst materials using stochastic generation techniques. This method creates catalyst structures by using a desired pore size distribution (PSD) as an input, identifying and generating the macro- and microporous regions of the PSD, and then combining the two regions using a custom divider. Statistical analysis (two sample t-test and two sample K-S test) was used to determine the similarity of generated structures to previously imaged commercial catalyst materials. Moreover, pore network modelling techniques were applied to the generated structures to evaluate electrical and mass transport properties. Through these methods, we show that both transport properties and PSD characteristics of generated materials were within experimentally measured ranges, and altering elements of the PSD can result in order of magnitude changes in electrical conductivity, proton conductivity, and through plane permeability.

The methodology presented in this work can be used to evaluate transport properties of various catalyst and catalyst-layer designs with novel pore size distributions. The local transport properties obtained can provide estimates for catalyst properties seldom reported in the literature, facilitating the design and informing the fabrication of next generation, ultra low loading catalyst materials.

[1] A. Mayyas, M. Ruth, et al., Manufacturing Cost Analysis for Proton Exchange Membrane Water Electrolyzers, United States (2019).

[2] Z. Taie, X. Peng, et al., ACS Appl. Mater. Interfaces, 12, 47, 52701–52712 (2020).

[3] J. Lopata, Z. Kang, et al., J. Electrochem. Soc., 167. 064507 (2020).

[4] J. K. Lee, C. H. Lee, and A. Bazylak, J. Power Sources, 437, 226910 (2019).
The Impacts of Membrane Pinholes on Performance and Hydrogen Crossover in PEM Water Electrolysis
Authors: Liu Chang , Wrubel Jacob A , Padgett Elliot , Bender Guido
Published: November 2022

Polymer electrolyte membrane (PEM) water electrolysis is a promising energy storage technology to produce highly pure hydrogen with high efficiency 1. However, to implement it on a larger scale, it is essential to understand the effects of defects and the required tolerances and quality controls during manufacturing or subsequent handling. Inhomogeneities in membrane electrode assembly (MEA) component materials caused by the manufacturing process or subsequent handling can lead to performance loss and failure 2. Defects such as membrane pinholes, cuts, tears, abrasions, or perforations can all potentially impact MEA performance. In terms of impact, a loss of integrity of the membrane can allow bulk gas transport (crossover) and/or electrical shorting 3.

In particular, hydrogen crossover is a crucial issue for PEM water electrolysis in terms of safe operation and efficiency losses, especially at increased hydrogen pressures. Crossover reduces the overall efficiency of the system and poses flammability hazards under certain conditions 4. Pinholes that form during the manufacturing process or during operation through degradation of the membrane lead to dramatically increased hydrogen crossover.

In this study, the impacts of membrane pinholes on the performance and hydrogen crossover of PEM water electrolyzer cells are studied. Pinholes with different sizes are artificially introduced to the MEA to investigate the effects on the initial cell performance and hydrogen crossover rate under various backpressure and current density conditions.

Reference

Liu, C.; Shviro, M.; Gago, A. S.; Zaccarine, S. F.; Bender, G.; Gazdzicki, P.; Morawietz, T.; Biswas, I.; Rasinski, M.; Everwand, A., Exploring the Interface of Skin‐Layered Titanium Fibers for Electrochemical Water Splitting. Adv Energy Mater
2021,
11 (8), 2002926.

Ulsh, M.; DeBari, A.; Berliner, J. M.; Zenyuk, I. V.; Rupnowski, P.; Matvichuk, L.; Weber, A. Z.; Bender, G., The development of a through-plane reactive excitation technique for detection of pinholes in membrane-containing MEA sub-assemblies. Int J Hydrogen Energ
2019,
44 (16), 8533-8547.

Phillips, A.; Ulsh, M.; Mackay, J.; Harris, T.; Shrivastava, N.; Chatterjee, A.; Porter, J.; Bender, G. J. F. C., The effect of membrane casting irregularities on initial fuel cell performance. 2020,
20 (1), 60-69.

Martin, A.; Trinke, P.; Stähler, M.; Stähler, A.; Scheepers, F.; Bensmann, B.; Carmo, M.; Lehnert, W.; Hanke-Rauschenbach, R. J. J. o. T. E. S., The Effect of Cell Compression and Cathode Pressure on Hydrogen Crossover in PEM Water Electrolysis. 2022,
169 (1), 014502.
Para-polybenzimidazole Membranes for HCl Electrolysis at High (T < 160 oC) Temperatures
Authors: Likit-anurak Kris , Mukhin Nikolai Yurii , Brannon Jamie Katherine , Hepstall Aubrey Madelleine , Murdock Laura , Benicewicz Brian , Shimpalee Sirivatch , Meekins Benjamin
Published: November 2022

Chlorine (Cl2) is a fundamental feedstock material for the chemical industry, and chlorine-derived products contribute more than $46 billion to the US economy annually. Chlorine plays a major role in many applications such as clean drinking water, pharmaceuticals, and crop protection chemicals. Most chlorine is produced from electrolysis of brine1. Chlorine can also be produced from hydrochloric acid by electrolysis. There are two primary techniques to recycle HCl to Cl2 via electrolysis--a diaphragm cell, which has the advantage of generating H2 as the product, and Proton Exchange Membrane (PEM) electrolyzer, which has the benefit of a higher conversion rate and lower energy consumption2,3. PEM electrolyzers are limited by the Nafion membrane separator, which requires hydration to conduct protons efficiently and is limited to temperatures of ≤ 120 °C. para-Polybenzimidazole (PBI; brand name Celtec-P) membranes are known as high temperature (T ≤ 230 °C) polymer separators that do not require hydration to maintain efficient proton conductivity and can operate in strong acid conditions4–6.

In this work, we demonstrate a completely anhydrous HCl electrolysis system using a Celtec-P membrane that operates at temperatures up to 160 °C and has apparent conversion efficiencies up to 93% at 1.8V. We also discuss the results of an experimentally validated computational fluid dynamics (CFD) model and how this model can be used to elucidate and overcome potential electrolyzer limitations.

Reference

Pamphlet 1 Chlorine Basic, 8th ed., p. 62, The Chlorine Institute, (2014).

Industrial Solutions HCl Electrolysis Chlorine Recovery for Greater Sustainability. Thyssenkrupp AG. Accessed December 20, 2021. https://ucpcdn.thyssenkrupp.com/_legacy/UCPthyssenkruppBAISUhdeChlorineEngineers/assets.files/products/hydrochloric_acid_recycling/thyssenkrupp_hcl_electrolysis_brochure_web_1.pdf.

“Industrial Technologies Program: Advance Chlor-Alkali Technology.” Office of Energy Efficiency and Renewable Energy,U.S. Department of Energy, January 2006. https://www1.eere.energy.gov/manufacturing/industries_technologies/imf/pdfs/1797_advanced_chlor-alkali.pdf.

T. R. Garrick et al., J. Electrochem. Soc., 164, F1591–F1595 (2017).

L. Xiao et al., Chem. Mater., 17, 5328–5333 (2005).

J. A. Mader and B. C. Benicewicz, Macromolecules, 43, 6706–6715 (2010).
Internal Mass Transport Induced Voltage Losses during Water Electrolysis on Interconnected Nickel Nanowire Mesh Electrodes
Authors: Blom Martijn J.W. , Steegstra Patrick , Vereecken Philippe M.
Published: November 2022

Nickel nanowire mesh electrodes offer great potential for water electrolysis in alkaline environment, given their high internal surface area, mechanical strength, and alkaline resistance. Here we use a nickel nanowire mesh with a specific area of 26 m2/cm3, resulting in ~100-fold area enhancement for a 4µm thick nanowire mesh, compared to planar nickel. This highly benefits geometric current density, potentially into a regime where mass transport is the main limiting factor. Therefore, we performed a systematic study of electrode behaviour under various mass transport conditions to decouple kinetic and mass transfer related contributions to electrode voltage losses.

An electrochemical flow cell was designed to measure the nanowire mesh electrode performance under optimal mass transport conditions. The cell provided electrolyte flow through the nanomesh, enabling convective supply of reagent into the nanopores as well as convective removal of reaction products. Facilitated by the inherent strength of the nanowire mesh, superficial flow velocities up to 1 cm/s could be obtained, with which geometric current densities as high as 320 mA/cm2 could be measured in the kinetically limited (flowrate independent) regime.

Internal mass transport limitations were isolated by use of an inverted rotating disk electrode (iRDE). Koutecky-Levich analysis was performed to compensate for external mass transfer contributions on both nanowire mesh electrodes and planar electrodes. The nanowire mesh as iRDE resembles operating conditions in an electrolyzer, whereas the planar electrode provides a well-defined benchmark area for the electrode surface activity.

For both the oxygen evolution reaction as the hydrogen evolution reaction, mass transport limitations were studies as function of current density and electrolyte (NaOH) concentration. Nanowire mesh electrode operation in the presence of internal mass transport limitations was compared to the non-limited condition and planar benchmark, from which the electrode effectiveness factor could be calculated. A 1-d simplified model of the electrode was used to explain the observed phenomena and to provide guidance for design optimization.
Electronic Structure Modulation of Sulfur-Retaining Nickel-Based Electrocatalyst to Improve the Oxygen Evolution Reaction
Authors: Han Man Ho , Oh Hyung-Suk
Published: November 2022

Water electrolysis is considered as a key energy source to produce hydrogen for achieving a clean and sustainable society. Improving the sluggish kinetics of the oxygen evolution reaction (OER) is focused to overcome the limit efficiency of water electrolysis. Transition metals, especially Ni, are one of the most promising materials for the alkaline OER because of good catalytic activities, stabilities and cost efficiency. Ni based materials, such as Ni oxyhydroxides, hydroxides, phosphides and sulfides, are intensively developed for use as OER catalysts. Recently, the sulfurization of transition metals is introduced as an effective method to improve the intrinsic electrocatalytic activities. The role of S has been summarized in 2 ways. S accelerates the regeneration of transition metals in alkaline media that S is dissolved and exchanged with O species. Mullins et al. reported Nickel oxide derived from Ni-S. It exhibits amorphous and large active surface morphology which is favorable OER. The other role is that remaining S modulates the electronic structures of Ni catalysts reducing the energy barrier for the OER. Wu et al. developed ultrathin Fe-doped Ni3S2 for overall water splitting. Based on density functional theory calculations, the Fe-doped Ni3S2 surface exhibits an optimized energy for water adsorption and dissociation, which enhances the intrinsic activity for the OER. However, in-situ/operando experimental studies regarding the effects of residual S are rare.

Herein, we report the role of the remaining S in Ni catalysts that exhibit longer Ni-O bonding in the NiOOH phase produced in-situ. C-supported Fe- and Co-doped nickel sulfide catalysts (NiFeCo-S/C) is prepared using a simple impregnation method with heating under an H2S atmosphere. We tested the electrochemical properties of the NiFeCo-S/C in alkaline media of 1 M KOH. It achieved current density of 10 mA cm-2 with only overpotential of 267.2 mV. Also, it maintained the OER activities for 24 h at current densities of 10 and 50 mA cm-2, respectively. Moreover, the prepared catalyst was analyzed the change of electronic structure and bonding group using in-situ/operando X-ray absorption spectroscopy (XAFS) and surface-enhanced Raman spectroscopy (SERS) under OER condition. Based on these results, we could elucidate the effects of the remaining S during the OER.

Figure 1
3D Metal-Organic Framework Based Layered Double Hydroxide Core Shell Structure for Enhanced Oxygen Evolution Reaction
Authors: Liu Ziqi , Lee Min Hwan , Garcia ThomasJae
Published: November 2022

Electrochemical water splitting, an effective approach of generating high purity hydrogen in a clean way, is composed of two half reactions: hydrogen evolution reaction (HER) and oxygen evolution reaction (OER).[1] OER is the main rate-limiting half reaction for water splitting due to its sluggish four-electron transfer process.[2]
,
[3] An efficient electrocatalyst is indispensable to minimize the activation barrier for the reaction and achieve a high efficiency.

Recently, two-dimensional (2D) layered double hydroxides (LDHs) have shown promises as one of the most effective electrocatalysts towards OER. However, the confined nanostructure with poor electronic conductivity inhibits their further enhanced catalytic performance towards OER. Herein, a 3D core-shell LDH structure is synthesized through a facile one-step reaction strategy, in which the terephthalic acid and urea is employed as the organic ligand for the metal organic framework (MOF) precursor and surface coordination buffer between LDH and MOF. Benefiting from the hierarchical 3D microstructure with uniformly nanosheets grown on the surface, the as prepared electrocatalyst exhibits rich edge active sites and enormous electrochemical surface area. The representative sample (namely, CoNi-LDH@BDC) achieves an excellent OER activity with a low overpotential of 280 mV at 100 mA cm-2 and robust cyclic stability. In addition, quasi-operando studies using X-ray absorption and X-ray photoelectron spectroscopy further elucidate that the Co-Ni dual metal sites act as the main active site while Ni of high valence state is a favorable site to oxygen for the O-O bond formation. The prominent OER performance is also attributed to the synergistic effect between different transition metal atoms.

References

[1] L. Yu, H. Zhou, J. Sun, F. Qin, F. Yu, J. Bao, Y. Yu, S. Chen, Z. Ren, Energy Environ. Sci.
2017, 10, 1820.

[2] Y. Wang, C. Xie, Z. Zhang, D. Liu, R. Chen, S. Wang, Adv. Funct. Mater.
2018, 28, 1703363.

[3] L. Zhuang, L. Ge, Y. Yang, M. Li, Y. Jia, X. Yao, Z. Zhu, Adv. Mater.
2017, 29, 1606793.

[4] R. Frydendal, E. A. Paoli, B. P. Knudsen, B. Wickman, P. Malacrida, I. E. L. Stephens, I. Chorkendorff, ChemElectroChem
2014, 1, 2075.

[5] Y. Lee, J. Suntivich, K. J. May, E. E. Perry, Y. Shao-Horn, Synthesis and activities of rutile IrO 2 and RuO 2 nanoparticles for oxygen evolution in acid and alkaline solutions, Vol. 3, American Chemical Society, 2012, pp. 399–404.

[6] M. Gao, W. Sheng, Z. Zhuang, Q. Fang, S. Gu, J. Jiang, Y. Yan, J. Am. Chem. Soc.
2014, 136, 7077.
Dual-Layer Sulfur Cathode Integrating Sulfur Composite Electrode and Binder-Free Sulfur Thin Film for High Loading Li-S Batteries
Authors: Kim Hye Ran , Shim Jae Rin , Ryoo San Deul , Jung Yongju
Published: November 2022

The Lithium-sulfur (Li-S) battery is one of the most promising future electrochemical energy storage systems owing to the intrinsic advantages of sulfur such as its high energy density, low cost, and innocuous nature. For several decades, many research teams have tried to develop high performance Li-S batteries. Recently, various approaches for high sulfur loading have been demonstrated to achieve high energy density Li-S batteries. Many types of porous carbon materials (e.g., graphene, mesoporous carbons, hollow carbon spheres, and carbon nanotubes) have been used as a sulfur host. In many cases, however, the large-scale implementation to Li-S batteries has been discouraged due to the non-scalable synthesis process of these carbon materials. To improve the energy density of a sulfur cathode, we demonstrate a dual-layer sulfur cathode composed of a S-filled carbon electrode and a sulfur deposit film. First, a sulfur electrode was fabricated by uniformly embedding sulfur within the porous network of a carbon film. Then, an ultra-thin sulfur layer was constructed on the surface of the sulfur electrode through physical vapor deposition (PVD) of elemental sulfur
Lithium Metal Polymer Batteries: Towards Operation at Ambient Temperature
Authors: Pinchart Camille , Zanotti Jean-Marc , Berrod Quentin , Judeinstein Patrick , Ramos Raphael , Modesto Nino
Published: November 2022

A canonical electrolyte for lithium metal polymer batteries is PEO (Polyethylene Oxide) doped with lithium salts1. Its ionic conductivity is closely related to the local dynamics (Å, ps) of the polymer chains acting as a solid solvent. For good conductive performances, these batteries must be maintained above the melting point of the bulk PEO (TM
=60°C).

In order to lower this operating temperature, we propose to use one-dimensional nanoscale confinement to downshift the melting point of the confined electrolyte according to ΔTM ≈ 1/d where d is the pore diameter (Gibbs-Thomson effect)².

Porous polymer composite membranes based on vertically aligned Carbon NanoTubes (VA-CNTs)3
,4 seem to be able to meet this ambitious target. The pores are cylindrical (diameter 4nm, length 100µm) and have the particularity of being all macroscopically oriented and parallel.

The effect we are seeking is driven by the curvature of the confining pore. It is then critical to ensure that only the interior of the CNTs is the permeable part of the membrane. We have followed by neutron imaging the time dependence of the penetration of the electrolyte within the membrane. We evidence a critical feature we target: only the interior of the CNTs are the permeable moieties of the membrane.

As for the PEO dynamics under confinement, the electrolyte’s multiscale transport properties and ionic conductivity are characterized by PFG-NMR at the micrometer scale and Electrochemical Impedance Spectroscopy (EIS) at the macroscopic scale. We report a conductivity gain of one order of magnitude under VA-CNT confinement.

Nevertheless, on a multitude of non-connected CNT pores, conductivity fluctuations are not in phase: by such classical spectroscopic techniques, only an averaged conductivity is measured. To complement the spectroscopic approach, we also probe the system by the Voltage Clamp (also called Single Pore) technique. The analysis of the conductivity noise going through a single CNT pore can indeed reveal whether the conductivity under confinement5 is due to an anomalous mobility and/or charge fluctuations.

(1) Xue, Z. et al., Poly(Ethylene Oxide)-Based Electrolytes for Lithium-Ion Batteries. J. Mater. Chem. A
2015, 3 (38), 19218–19253.

(2) Alba-Simionesco, C. et al., M. Effects of Confinement on Freezing and Melting. J. Phys.: Condens. Matter
2006, 18 (6), R15–R68.

(3) Berrod, Q. et al., Enhanced Ionic Liquid Mobility Induced by Confinement in 1D CNT Membranes. Nanoscale
2016, 8 (15), 7845–7848.

(4) Zanotti, J.-M. et al., Nanocomposite membranes for electrochemical devices. Patent WO2016151142 A1.(2016)

(5) Tasserit, C. et al., Pink Noise of Ionic Conductance through Single Artificial Nanopores Revisited. Phys. Rev. Lett.
2010, 105 (26), 260602.

Figure 1
Effect of Carbon Nanotubes on the Electrochemical Performance of Li Powder Composite Anodes
Authors: Dzakpasu Cyril Bubu , Ryou Myung-Hyun , Lee Yong Min
Published: November 2022

To achieve the high energy density of lithium secondary batteries, the Li metal anode with a high theoretical capacity (3860 mAh g-1) and the lowest electrochemical potential (-3.04 vs. SHE) has attracted attention. However, Li metal is plagued with challenges such as irregular dendritic growth during cycling and low Coulombic efficiency (CE), which hinder its commercialization as an anode. Li metal powder (LMP) offers a solution to these problems by enlarging the surface area resulting in a lower effective current density. However, the commercial LMP passivated by Li2CO3 layer on the surface could hinder the electrical contact between individual LMPs as well as LMP and Cu current collector. Consequently, a series of LMP particle contact failures result in dead regions within the LMP electrode where the Li source cannot be fully activated.

Herein, we report the effect of multiwalled CNTs on the electrochemical performance of Li metal powder-based anodes for Li metal batteries. The CNT-LMP anode exhibits a remarkable improvement in the electrochemical performance of coin cells compared to the bare LMP system. This improvement is attributed to the enhanced electrical connection between individual LMP particles, activation of full Li utilization, and the seeding effect of CNTs. Electrochemical properties were investigated using postmortem scanning electron microscopy and galvanostatic cycling techniques.
Multi-Functional AgNO3 Preplanted in Li Metal Powder Electrodes
Authors: Kang Dongyoon , Jin Dahee , Dzakpasu Cyril Bubu , Han Jiwon , Ryou Myung-Hyun , Lee Yong Min
Published: November 2022

Li metal powder (LMP) is very promising in practically fabricating thin Li electrodes for high-energy-density Li metal batteries (LMBs), because it allows not only conventional slurry coating but also co-use of functional additives. Also, the LMP has several times higher surface area than that of the Li foil with tens of micrometers, which reduces the local current density and suppresses Li dendritic growth. However, the uneven and resistive protection layer on the LMP surface could lead to the non-uniform composition in solid electrolyte interphase (SEI), thereby resulting in the localized Li nucleation and growth. Thus, the introduction of stabilizing additives for LMP is one of the most promising solutions to control the Li stripping/plating behavior.

Herein, we report a AgNO3-preplanted LMP electrode having stable long-term cycle performance. The AgNO3 in the slurry mixing and coating process can chemically form lithiophilic Ag particles on the LMP surface, which act as nucleation sites. In addition, since the metallic Ag particle is embedded within the LMP electrodes, it continuously contributes as the seeding points even under extreme volume expansion during cycling. Additionally, nitrates can help form Li3N-rich SEI with higher ionic conductivity and Young’s modulus. Finally, AgNO3-preplanted LMP electrode of 40 μm survives up to 500 cycles with 86.8% capacity retention at 1C/3C charging/discharging condition. Therefore, this superior cycle performance enables AgNO3-preplanted LMP electrodes to be an attractive anode candidate for LMBs.
Quantifying the Thermochemistry of Solid-State Lithium Metal Battery Reactions Using Differential Scanning Calorimetry
Authors: Bhargava Bhuvsmita , Johnson Nathan B , Chang Jonathan , Albertus Paul
Published: November 2022

It is commonly assumed that the introduction of solid-state electrolytes implies the improved safety of high-energy batteries due to the removal of the combustible organic solvents in present Li-ion cells. However, safety is a multifaceted issue that involves thermal runaway onset temperature, self-heating rates, total generated energy, maximum temperature, gas or other material releases from a cell, thermal runaway prevention mechanisms, etc.1 In addition, the use of lithium metal anodes (which melt at 180°C) for high energy density cells may introduce previously unconsidered safety issues not faced by Li-ion cells, in which no molten and reactive lithium metal is present during a thermal runaway. Quantitative heat flow data on reaction thermochemistry among solid-state battery cell components can be gathered using differential scanning calorimetry on milligram-scale samples that include the key components of a full cell stack. While a principal exothermic reaction observed in previous DSC work2 is the formation of Li2O from molten Li and O2 released upon metal oxide cathode decomposition, this work did not include current collectors or carbon and binder, which add further competing reactions such as the oxidation of binder, and lithium/current collector alloying. In addition, the measured heat flows in a DSC test that includes several cell components are critically dependent on the mass ratio of materials present in the cell, for example the electrode capacity ratio. In this talk we present our own DSC measurements on the onset temperatures, total heat release, and rate of heat release for numerous combinations of cell components (e.g., Li metal, solid electrolyte separators, cathode active materials, cathode inactive components) for prospective solid-state batteries.

References:

(1) Bates, A. M.; Preger, Y.; Torres-Castro, L.; Harrison, K. L.; Harris, S. J.; Hewson, J. Are Solid-State Batteries Safer than Lithium-Ion Batteries? Joule
2022, 6 (4), 742–755.

(2) Inoue, T.; Mukai, K. Are All-Solid-State Lithium-Ion Batteries Really Safe?−verification by Differential Scanning Calorimetry with an All-Inclusive Microcell. ACS Appl. Mater. Interfaces
2017, 9 (2), 1507–1515.
Composite Cathode with High Active Mass Loading for Sulfide-Based All-Solid-State Lithium Batteries
Authors: Hong Seung-Bo , Lee Young-Jun , Sim Hui-Tae , Lee Han-Jo , Kim Dong-Won
Published: November 2022

Due to the global warming and resulting environmental regulations, the use of rechargeable lithium batteries is rapidly growing. However, the current lithium-ion batteries (LIBs) employing liquid electrolytes have a safety concern, since the liquid electrolytes are highly flammable, which can lead to a fire or an explosion under abnormal conditions. Accordingly, all-solid-state lithium batteries are considered promising alternatives to current LIBs. Among various types of solid electrolytes, sulfide-based electrolytes exhibit high ionic conductivities at room temperature, comparable with those of liquid electrolytes. In order to improve the energy density of the solid-state batteries, it is essential to increase the loading of active mass in the composite cathode. In this study, we tried to increase the active mass loading by investigating the optimum conditions with respect to types of active materials. As a result, we could obtain good cycling performance of the sulfide-based all-solid-state lithium batteries employing the composite cathode with high active mass loading (> 4.5 mAh cm-2).
(Invited) Anode-Free Sodium Metal Batteries
Authors: Wang Yixian , Dong Hui , Katyal Naman , Henkelman Graeme , Watt John , Mitlin David
Published: November 2022

Sodium-ion batteries (SIBs) have been regarded as one of the most promising alternatives to lithium-ion batteries (LIBs) due to their analogous working mechanism but greater abundance. The cost-effectiveness of Na batteries is expected to overtake that of LIBs in terms of electromobile applications if their energy densities can reach 200 Wh kg-1. In an anode-free configuration, all active sodium is stored in the cathode while anode only contains current collector with zero excess sodium, therefore achieving maximized energy density, significantly reduced cost, and simplified manufacture procedures. However, the anode-free batteries often suffer rapid capacity decay due to the absence of a reservoir to replenish the Na loss during cycling. In this work, we employed repeated cold rolling and folding to fabricate a metallurgical composite of sodium-antimony-telluride Na2(Sb2/6Te3/6Vac1/6) dispersed in electrochemically active sodium metal, termed “NST-Na”. This new intermetallic has a vacancy-rich thermodynamically stable fcc structure and enables state-of-the-art electrochemical performance in widely employed carbonate and ether electrolytes. NST-Na achieves 100% depth-of-discharge (DOD) in 1 M NaPF6 in G2, with 15 mAh cm-2 at 1 mA cm-2 and CE of 99.4%, for 1000 hours of plating/stripping. Sodium metal batteries (SMB, NMB) with NST-Na and Na3V2(PO4)3 (NVP) or sulfur cathodes give significantly improved energy, cycling and CE (> 99%). Anode-Free battery with NST collector and NVP obtains 0.23% capacity decay per cycle. Imaging and tomography using (cryo-)FIB sectioning, (cryo-)SEM, and (cryo-)TEM imaging indicate that sodium metal fills the open space inside the self-supporting sodiophilic NST skeleton, resulting in dense (pore-free and SEI-free) metal deposits with flat surfaces. The baseline Na deposit consists of filament-like dendrites and Dead Metal, intermixed with pores and SEI. Density functional theory (DFT) calculations show that uniqueness of NST lies in the thermodynamic stability of Na atoms (rather than clusters) on its surface that leads to planar wetting, and in its own stability that prevents decomposition during cycling.

Figure 1
Surface-Substituted Prussian Blue Analog Cathode for Sustainable Potassium-Ion Batteries
Authors: Ge Junmin , Fan Ling , Rao Apparao M. , Zhou Jiang , Lu Bingan
Published: November 2022

While lithium-ion batteries still dominate energy storage applications, aqueous potassium-ion batteries have emerged as

a complementary technology due to their combined advantages in cost and safety. Realizing their full potential, however, is

not without challenges. One is that among the limited choices of cathode materials, the more sustainable Prussian blue analogs

suffer from fast capacity fading when manganese is present. Here we report a potassium manganese hexacyanoferrate

K1.82Mn[Fe(CN)6]0.96·0.47H2O cathode featuring an in situ cation engineered surface where iron is substituted for manganese.

With this engineered surface, the cathode design exhibits a discharge capacity of 160 mAh g−1 and 120 mAh g−1 at 300 mA g−1

and 2,500 mA g−1, respectively, and sustains 130,000 cycles (more than 500 days) with negligible capacity loss. Pairing the

current cathode with a 3,4,9,10-perylenetetracarboxylic diimide anode yields a full potassium-ion cell that delivers an energy

density as high as 92 Wh kg−1 and retains 82.5% of the initial capacity after 6,500 cycles at 1,500 mA g−1. The unprecedented

electrochemical performance is attributed to the suppressed manganese dissolution as a result of the shielding surface

layer. This work is expected to open an avenue for the rational design of high-performance cathode materials with redox-active manganese for rechargeable batteries.
High-Performance All-Solid-State Li-S Batteries Enabled by Reaction Kinetics Enhancement and Interface Stabilization
Authors: Zhu Hongli , Sun Xiao
Published: November 2022

Compared to the conventional lithium-sulfur (Li-S) batteries using liquid electrolytes, all-solid-state lithium-sulfur batteries (ASSLSBs) own the merits of eliminating polysulfide shuttle effects, potentially higher energy density, and superior safety. However, there are challenges of low utilization of sulfur caused by poor ion and electron conductions in the cathode, huge interfacial resistance due to the contact loss caused by huge volume change of sulfur during cycling, and sluggish reaction kinetics and higher thermodynamic barriers because of the one-step reaction from S8 to Li2S reactions. Also, the carbon additive could accelerate the decomposition of sulfide solid-state electrolyte (SSE) resulting newborn impedance. Therefore, it is significant to interface engineering the carbon additive through surface modification and functionalization to improve the electrochemical stability, charge transfer, and reaction kinetics in ASSLSBs.

Herein, for the first time, we designed a highly conductive carbon fiber decorated with vertically grown MoS2 nanosheets and applied it in ASSLSBs. The chemical and electrochemical compatibility among MoS2, sulfur, and sulfide SSE can greatly improve the stability of the cathode and therefore maintain pristine interfaces between the different compositions for stable ion and electron transport. The presence of electrical-conductive metallic 1T MoS2 and its uniform distribution on carbon fiber without aggregation benefit the electron transfer between carbon and sulfur. Meanwhile, the unique layered structure of MoS2 can be intercalated by a large amount of Li atoms and therefore facilitate both ionic and electronic conductivity. In consequence, the charge transfer and reaction kinetics were greatly enhanced, and the decomposition of SSEs was successfully relieved. As a result, our ASSLSB delivered an ultrahigh initial discharge capacity of 1456 mAh g-1 with ultrahigh initial coulombic efficiency and maintained high-capacity retention of 78 % at 0.1 C after 220 cycles. The batteries also obtained remarkable rate performance of 1069 mAh g-1 at 1 C. This study pioneered new idea that fabricating the high performance ASSLSBs through developing surface functionalized and stabilized conductive carbon additives with metal sulfides.
Chemo-Mechanics in All Solid State Composite Cathodes
Authors: Hatzell Kelsey
Published: November 2022

Decarbonization of transportation systems will require a suite of battery technologies depending on the mode and scale. Solid state batteries are an energy dense and non-flammable alternative to conventional batteries and is currently being explored for passenger vehicles and portable electronics1,2. While there is considerable interest in understanding lithium metal anodes for solid state batteries, many significant challenges still exist in solid state cathodes. Solid state cathodes are composites and usually include a combination of active material, solid electrolyte and binder3. The composition, microstructure, and properties of the cathode has significant implications for rate performance, energy density, and lifetime of these systems. Here we examine composite solid state cathodes comprised of argyrodite Li6PS5Cl and LiNi0.8Co0.1Mn0.1O2. We examine how composition and structure influences performance with a specific lens on understanding how chemo-mechanical transformations and buried solid-solid interfaces evolved during cycle operation. In addition we show how external operating conditions (temperature/pressure) influence stress generation in these systems. In this talk we will discuss how we combine novel bench-top experiments with advanced operando x-ray characterization tools to quantify stress and correlate it to structure.

[1]Shen, F., Dixit, M. B., Zaman, W., Hortance, N., Rogers, B., & Hatzell, K. B. (2019). Composite electrode ink formulation for all solid-state batteries. Journal of The Electrochemical Society, 166(14), A3182.

[2]Hatzell, K. B., & Zheng, Y. (2021). Prospects on large-scale manufacturing of solid state batteries. MRS Energy & Sustainability, 8(1), 33-39.

[3]Ren, Y., Hortance, N., & Hatzell, K. (2022). Mitigating Chemo-Mechanical Failure in Li-S Solid State Batteries with Compliant Cathodes. Journal of The Electrochemical Society.
Coupled Effect of Pressure and Temperature on Interface Stability in Solid-State Batteries
Authors: Chatterjee Debanjali , Naik Kaustubh Girish , Vishnugopi Bairav Sabarish , Mukherjee Partha P.
Published: November 2022

Solid-State Batteries (SSBs) utilizing a lithium (Li) metal anode are promising candidates for next-generation energy storage systems, offering higher energy and power densities compared to conventional Li-ion batteries. However, preserving the interface stability in SSBs is a major challenge due to non-uniform electrodeposition and imperfect solid-solid contact between the metal anode and solid electrolyte. A commonly used approach to mitigate this is the application of stack pressure. The resulting internal stresses affect both transport in the solid electrolyte and reaction kinetics at the anode-SE interface. Thus, the anode/SE interfacial stability in SSBs involves an intricate kinetics-transport-mechanics interplay. In this work, we study the coupled effect of external pressure and temperature on stress-driven transport and reaction kinetics, and its implications on the stability of the Li-metal/SE interface during plating and stripping.
(Digital Presentation) A Polymerized-Ionic-Liquid-Based Polymer Electrolyte for >4 V Class Solid-State Lithium Metal Batteries
Authors: Fu Chengyin , Homann Gerrit , Grissa Rabeb , Rentsch Daniel , Zhao Wengao , Gouveia Tom , Falgayrat Anais , Lin Rongying , Fantini Sebastien , Battaglia Corsin
Published: November 2022

Polymer solid electrolytes for solid-state batteries typically suffer from low ionic conductivity and low oxidative stability. We report a polymer electrolyte based on a polymerized ionic liquid and an ionic liquid plasticizer offering simultaneously a high room-temperature ionic conductivity of 0.8 mS cm-1 and a high oxidative stability > 5.0 V vs Li+/Li. The electrolyte is compatible with lithium metal, exhibits high thermal stability up to 300 °C, is non-flammable upon direct flame exposure, shows decent lithium-ion transference number of 0.44, and possesses a low gravimetric density of only 1.6 g cm-3, important when targeting batteries with high gravimetric energy density. In symmetric lithium metal cells, the electrolyte enables stable lithium plating and stripping at 0.1 mA cm−2 with a capacity of 1 mAh cm−2 per half cycle for over 1700 h at 25 °C. Cells with a lithium metal anode cycled against a state-of-the-art high-energy uncoated layered LiNi0.8Mn0.1Co0.1O2cathode achieve an initial capacity of 162 mA h g-1 and a capacity retention of 72% after 600 cycles to an upper cut-off voltage of 4.4 V at 0.1 mA cm-2 and 25 °C. Cells with a high-voltage spinel LiMn1.5Ni0.5O4 cathode reach an initial capacity of 132 mAh g-1 and a capacity retention of 76% after 300 cycles to an upper cut-off voltage of 5 V at 0.1 mA cm-2 and 25 °C, confirming the high oxidative stability and technological potential of this electrolyte for high-voltage solid-state lithium metal batteries.
(Invited) Mechanistic Interrogation of Solid/Solid Interfaces
Authors: Mukherjee Partha P. , Vishnugopi Bairav Sabarish , Naik Kaustubh Girish
Published: November 2022

Solid-state batteries (SSBs) that pair a lithium metal anode with an inorganic solid electrolyte hold promise to simultaneously improve the energy density, power density and safety as compared to conventional lithium-ion batteries. However, the development of SSBs is confronted with challenges including electrochemical-transport-mechanics interplay and morphological instability at various solid-solid interfaces. Toward achieving practical SSBs, gaining a fundamental understanding of the mechanistic interactions and systematically correlating those to interface stability and performance is critical. In this presentation, we delineate the distinct asymmetry in the electrochemical-mechanical interaction, limiting mechanisms and interface response during operation. The mechanistic role of heterogeneities that underlie at solid-solid interfaces on the stress-transport-kinetics interplay will be discussed.