bluuebunny/crossref_metadata_2025 huggingface dataset:
Advanced Performances of Full Concentration Gradient Li[Ni0.65Co0.08Mn0.27]O2 Cathode Materials for Lithium Ion Batteries
Authors: Jun Do-Wook , Park Kang-Joon , Lim Byung-Beom , Yoon Chong seung , Sun Yang-Kook
Published: February 2020

Full concentration gradient (FCG) cathode material which consists of Ni-rich core Li[Ni0.89Co0.01Mn0.10]O2 and Ni-less outer layer Li[Ni0.61Co0.09Mn0.30]O2 was synthesized by co-precipitation method.1,2 A gradually changing concentration gradients for Ni, Co, and Mn extended from the core to the surface within a single cathode particle with an average composition of Li[Ni0.65Co0.08Mn0.27]O2. We have evaluated electrochemical and thermal properties of the FCG cathode material and compared it with the conventional cathode (CC) material, Li[Ni0.65Co0.08Mn0.27]O2 without the concentration gradient. The BET surface area measurement demonstrated the presence of high-density primary particles in the FCG cathode material. The FCG cathode exhibited higher discharge capacity, excellent cycle retention and superior thermal stability compared to the CC Li[Ni0.65Co0.08Mn0.27]O2 cathode material.1

References

1. H.-J. Noh, Z. Chen, C. S. Yoon, J. Lu, K. Amine, and Y.-K. Sun, Chem. Mater., 25, 2109 (2013).

2. M. H. Lee,Y. J. Kang, S. T.Myung, andY. K. Sun, Electrochim. Acta. 50, 939 (2004).
Electrospun Hollow Glassy Carbon-Reduced Graphene Oxide Nanofibers with Encapsulated ZnO Nanoparticles : A Free-Standing Anode for Li-Ion Batteries
Authors: Shilpa Shilpa , Basavaraja Basavanakote M , Majumder Subhasish B , Sharma Ashutosh
Published: February 2020

Although zinc oxide (ZnO) has a high theoretical capacity for lithium storage, its poor cyclability due to the huge volume changes during charge–discharge cycles result in particle pulverization and detachment from the current collector.  In this work, a novel anode architecture for Li-ion batteries is  fabricated by encapsulating ZnO nanoparticles in the hollow core of glassy carbon–reduced graphene oxide (C–rGO) electrospun composite nanofibers. A one-step, co-axial electrospinning method is used to synthesize a mat of core–shell structured composite nanofibers composed of rGO embedded in poly(acrylonitrile) (shell) and a ZnO nanoparticle precursor with a carrier polymer (core). Subsequent calcination and carbonization produce a mechanically stable anode material, which is used directly as a free-standing anode without any binder and current collector.  The ZnO–C–rGO nanofiber composite was characterized by SEM, TEM, RAMAN and XRD techniques. The electrochemical performance of the composite was studied by galvanostatic charge–discharge measurements at different current densities, slow scan cyclic voltammetry (CV) and impedance measurements. Incorporation of an rGO network in the glassy nanofiber shell enhances both the capacity and electrical conductivity of the mat electrode resulting in faster electron kinetics, and thus, an improved rate capability. The interior void spaces combined with the mechanical strength and flexibility of the C–rGO shell act as a structural buffer effectively relieving the volumetric stresses generated during charge–discharge cycles. The synergistic effect of the metal oxide, rGO and the core–shell design results in a high capacity of 815mAh/g at a current density of 50mA/g with a capacity retention of almost 80% after 100 cycles, thus demonstrating significant potential as an anode substitute for next generation Li-ion batteries.
(Invited) Li Intercalation into Multi-Layers Transition Metal Carbides and Carbonitrides "Mxenes" in Li-Ion Batteries
Authors: Naguib Michael
Published: February 2020

Two-dimensional, 2D, transition metal carbides and carbonitrides, so called MXenes, consist of nearly closed packed layers of early transition metals “M” with “X” atoms (X stands for carbon or nitrogen) filling the octahedral sites with a nominal composition of Mn

+1
Xn
where n = 1, 2, or 3. Depending on the value of n, the thickness of the Mn

+1
Xn
change; if n = 1 the MXene layer consists of a single block of octahedra (3 atoms thick). If n = 2 the MXene layer consists of 2 octahedra blocks; if n = 3, consists of 3 blocks of octahedra. The surface of as-synthesized MXenes is terminated by a mixture of moieties viz. O, OH, and F (this mixture is referred hence after by Tx). To date, the following MXenes were successfully synthesized: Ti2CTx, Nb2CTx, V2CTx, (Ti0.5,Nb0.5)2CTx, Ti3C2Tx, (V0.5,Cr0.5)3C2Tx, Ti3CNTx, Ta4C3Tx, and Nb4C3Tx.

Unlike conventional 3D transition metal carbides and nitrides which are known to be inert for Li, MXenes were found to be electrochemically active as host materials for Li-ions. The latter intercalate/de-intercalate reversibly between the MXenes layers during the electrochemical cycling in Li batteries. This was confirmed by in situ XRD studies during electrochemical lithiation and de-lithiation. When they were tested as electrode materials for Li-ion batteries (LIBs), each MXene showed its own electrochemical voltage window. In principle, some MXenes could function as cathodes and some as anodes for LIBs. MXenes electrodes exhibited an excellent capability to handle high cycling rates with good capacity. This was explained by a low Li diffusion barrier in case of MXene compared to other electrode materials such as graphite. MXenes powders can be cold pressed into freestanding thick discs resulting in electrodes with high areal capacities exceeding 5 mAh/cm2. Most of the research conducted –experimentally- on MXenes as electrodes for LIBs was limited to the as-synthesized MXene without further control of the surface termination. However, ab initio calculations predict that controlling the surface termination could enhance the performance. Herein the progress in the synthesis of MXenes and controlling their surface termination, in addition to their performance as electrode materials in LIBs will be discussed.
(Invited) Side Reactions and Cycling Efficiency with Silicon Electrode Surfaces
Authors: Vaughey John T. , Dogan Fulya , Hubaud Aude A. , Schroeder David J.
Published: February 2020

Energy storage materials – lithium-based portable energy storage technologies are an area of research that was born in the late 1960s / early 1970s, went global in the 1990s with portable consumer electronics, and is now being adapted to a variety of markets including electrification of vehicles, space flight, and grid storage.  While showing promise, these new applications may have different requirements (e.g. power, cost, volume) than ones optimized for consumer markets. 

To increase energy density, many researchers are exploring ways to incorporate silicon into a battery.  Elemental silicon has many properties that make it a top candidate to replace graphitic carbon in next generation lithium-ion batteries.  It has (1) very high gravimetric capacity (~3600 mAh/g), (2) high volumetric capacity (~7400 mAh/L), and (3) low insertion cell voltage.  It also has many problems that must be overcome including (1) high volume expansion on lithiation, (2) an unstable SEI layer, and (3) instability of the fully charged anode to the electrolyte.  Although significant effort has been focused on silicon-based electrodes, e.g. understanding the role of morphology, particle size, or local structure – our work has been concentrated on electrode level interactions.  Using the knowledge gained from the materials level studies we are addressing what happens when the silicon is made into an electrode and exposed to the contents of an electrochemical cell [1-3]. 

Previous work by the Edstrom group [4-5] has shown that the normal passivation layer of silicon, namely silica, is in fact electrochemically active on the first charging cycle.  On first lithiation it reacts to form Li4SiO4.  This phase does not directly participate in the electrochemistry after this point, but does interact chemically with its environment to effect cycle efficiency and SEI stability [6].  In this talk we will discuss how, upon formation, it interacts with its environment and track these changes by FTIR, 29Si NMR, 7Li NMR, and PXRD with eventual formation of Li6Si2O7 and Li2SiO3.

[1] C. Joyce, L.Trahey, S.A. Bauer, F. Dogan, and J, T. Vaughey Journal of The Electrochemical Society, 159,A909-A914 (2012).

[2] F. Dogan, C. Joyce, and J. T. Vaughey Journal of The Electrochemical Society, 160,  A312-A319 (2013).

[3] F. R. Brushett, L.Trahey, X. Xiao, J. T. Vaughey ACS Appl. Mater. Interfaces , 6, 4524−4534 (2014).

[4] B. Philippe, R. DedryveÌre, M. Gorgoi, H. Rensmo, D. Gonbeau, K. Edström
 
J. Am. Chem. Soc.,
135, 9829−9842 (2013).

[5] ] B. Philippe, R. DedryveÌre, M. Gorgoi, H. Rensmo, D. Gonbeau, K. Edström  
Chem. Mater.,
25,394−404 (2013).

[6] A. A. Hubaud, Z. Z.  Yang , D. J. Schroeder, F. Dogan, L. Trahey, J. T. Vaughey  Journal of Power Sources
282, 639-644 (2015)

Figure 1
Interfacial Effects of Electrochemical Lithiation of Epsilon-VOPO4 and Evolution of the Electronic Structure
Authors: Quackenbush Nicholas F. , Wangoh Linda , Wen Bohua , Zhang Ruibo , Chung Youngmin , Chernova Natasha , Chen Zehua , Sallis Shawn , Lin Yuh-Chieh , Ong Shyue Ping , Whittingham M. Stanley , Piper Louis F.J.
Published: February 2020

The epsilon polymorph of vanadyl phosphate ε-VOPO4 is a promising cathode material for high-capacity Li ion batteries, owing to its demonstrated ability to reversibly incorporate more than one lithium per redox center, with a total theoretical capacity of 331 mAh/g. As in the case of the olivines, the problem of the inherently low electronic conductivity of ε-VOPO4 is overcome by the use of nano-sized particles within the cathode. At these dimensions the electrochemical reaction can be largely affected by the interfacial chemistry at the nanoparticle surface. An investigation of these surface reactions is critical for obtaining a complete understanding of the mechanism by which lithium intercalates and how it relates to the electrochemical performance.

         We performed x-ray photoelectron spectroscopy using both soft (XPS) and hard (HAXPES) x-rays to chemically distinguish and depth-resolve the interfacial phase transitions as a function of electrochemical discharge. Core level analysis supports a straightforward two-phase reaction as the first lithium is intercalated. In contrast, the insertion of the second lithium is more complicated with evidence of a significant radial lithium gradient, due to a possible to a disruption of the kinetics.  From inspection of the valence band region, we were able to monitor the reversible evolution of ε-VOPO4 to Li2VOPO4 at the surface of our nanoparticles.  These assignments were supported by hybrid density functional theory of the three phases.  The origin of the radial gradient is likely associated with the presence of stable intermediate phases during the second reaction and warrants further attention.  This work was supported as part of NECCES, an Energy Frontier Research Center funded by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences under Award Number DE-SC0001294.

Figure 1
The Use of Reduced Cost and Purity Precursors in the Melt Preparation of LiFePO4
Authors: Talebi-Esfandarani Majid , Rousselot Steeve , Gauthier Michel , Sauriol Pierre , Liang Guoxian , Dollé Mickeal
Published: February 2020

Different synthetic routes, such as solid state, sol-gel, hydrothermal, co-precipitation, and microwave preparations, have been used for preparing LiFePO4; (LFP) a key cathode material in lithium-ion battery applications. Usually it is necessary to use costly precursors with a high purity, such as FePO4 or FeC2O4, for the synthesis of LFP. In most methods secondary phases formed during synthesis, give rise to lower subsequent electrochemical capacities in the final product. The melt synthesis is an alternative, rapid and low-cost process proposed by Gauthier et
al., and can be a promising method for the large scale preparation of LFP. This process combines ideal-liquid phase reaction with short dwell times and fast reaction kinetics in a reducing atmosphere. Our team made an effort to reduce the high manufacturing cost of LFP by using a melt synthesis, enabling the utilisation of lower purity and lower cost raw materials; namely iron ore concentrate as a source of iron. In this work, different synthesis conditions (such as iron precursors, stoichiometric ratios, and solidification processes) are optimized to obtain a low cost carbon-coated LFP with a high purity and excellent electrochemical properties.
(Invited) Mechano-Electro-Chemical Coupling in Lithium Intercalation Compounds
Authors: Qi Yue , James Christine
Published: February 2020

Mechano-Electro-Chemical (MEC) Coupling in intercalation compounds can be considered in multiple ways.  Large stresses caused by electrochemically induced stoichiometry changes can lead to local stress and mechanical degradation.  On the other hand, MEC coupling may also provide new opportunities to characterize materials by measuring the stress/strain generated by the stoichiometry change.

One typical challenge in modeling the MEC coupling is the lack of proper material properties as a function of the state of charge (SOC). To address this challenge, we developed “atomically informed” battery mechanics models by integrating density functional theory (DFT) predicted mechanical properties into continuum models to predict diffusion induced deformation and stress evolution and make direct comparisons with experiments. It was found that lithiation induced stiffening occurs in layered compounds, however the averaged Young’s moduli change very minimally at a function of SOC in the spinel and olivine structures. Depends on the tendency of Li to segregate to or deplete from the fractured surface, the work of decohesion of electrodes can decrease or increase with SOC, and crack instability may also occur due to phase transitions within the decohering region.

Measuring the strain due to stoichiometry change can be further complicated by the coupling of different vacancy species. For example, in Li-excess layered compounds (xLi2MnO3∙(1-x)LiMO2, where M=Ni, Co and/or Mn), it is widely agreed that oxygen vacancies can be introduced to the Li2MnO3 phase during the initial charging cycles. With DFT and Ab initio molecular dynamics calculations, we demonstrate that correlations exist between oxygen vacancy and the formation and migration of Li vacancies. As Li vacancies tend to form and cluster around oxygen vacancies, the oxygen vacancies hinder the diffusion of the Li ions. On the other hand, the nonstoichiometry strains are correlated between the two species, making the MEC coupling analysis more complex in these intercalation compounds.
Bulk Structure and Surface Properties of Lithium- and Manganese-Rich Layered Oxides and Their Impact on Electrochemical Performance
Authors: Chen Guoying , Kuppan Saravanan , Shukla Alpesh Khushalchand
Published: February 2020

Lithium- and manganese-rich layered oxides, Li1+x
M1-x
O2 (M=Mn, Ni, Co), are promising cathode materials for lithium-ion batteries due to their high capacities, typically more than 250 mAh/g. Despite the intense research and development in the past decade, their commercial adoption remains hindered by severe shortcomings including a large first-cycle irreversible capacity loss, [1] voltage and capacity fade, [2] DC resistance rise at low state of charge (SOC) and transition metal dissolution. [3] Studies have attributed these issues to the structural changes occurring during first-cycle activation and prolonged cycling, yet the crystal structure of the pristine oxides is still a matter of debate.  Fundamental studies on the conventionally synthesized, aggregated secondary particles often lead to ambiguous results due to the structural complexity in this class of materials.  In this presentation, we report the synthesis of well-formed, discrete layered Li1+x
M1-x
O2 crystals with various morphologies and surface properties using a molten salt method. Complementary microscopy and spectroscopy techniques at multi-length scale, including aberration corrected (scanning) transmission electron microscopy, electron energy loss spectroscopy and X-ray energy dispersive spectroscopy, were used to reveal the structural make-up of the bulk as well as the surface of the primary particles.  Surface sensitive soft X-ray absorption spectroscopy was further used to reveal the roles of key surface properties, particularly surface composition, surface area and surface crystalline orientation, in the material challenges facing Li1+x
M1-x
O2 cathodes.  Future directions and research to enable this class of materials will also be discussed.

References:

1. Z. Lua and J. R. Dahn, Understanding the Anomalous Capacity of Li/Li[Ni
x
Li(1/3-2x/3)Mn(2/3-x/3)]O2 Cells Using In Situ X-Ray Diffraction and Electrochemical Studies, J. Electrochem. Soc., 149, A815 (2002).

2. J. R. Croy, S.-H. Kang, M. Balasubramanian, and M. M. Thackeray, Li2MnO3-Based Composite Cathodes for Lithium Batteries: A Novel Synthesis Approach and New Structures, Electrochem. Communications, 13, 1063 (2011).

3. S.-H. Kang and M. M. Thackeray, Enhancing The Rate Capability of High Capacity xLi2MnO3 .(1-x)LiMO2 (M = Mn, Ni, Co) Electrodes by Li–Ni–PO4 Treatment, Electrochem. Communications, 11, 748 (2009).

 Acknowledgment

This work was supported by the Assistant Secretary for Energy Efficiency and Renewable Energy, Office of FreedomCAR and Vehicle Technologies of the U.S. Department of Energy under Contract No. DE-AC02-05CH11231.
Impact of Electrolyte on the Cycling of Si-Based Materials
Authors: Chevrier Vincent L , Aiken Connor , Petibon Remi , Ma Xiaohua , Le Dinh Ba , Dahn Jeff R , Eberman Kevin W , Krause Larry J
Published: February 2020

Alloy-based negative electrodes have been considered the “next-generation negative electrode” expected to replace graphite for many years. However, few exist in the marketplace. Manufacturing alloy-based cells with acceptable cycling poses a major challenge, indeed many components of the cell must be adapted in order to obtain successful cycling. 3M has a long history of alloy research for negative electrodes and has developed commercially viable Si-based alloys.

                Si-based negative electrode materials undergo massive volume changes during cycling. Pure Si expands by approximately 280% while 3M’s active/inactive Si alloys expand on the order of 135%. The expansion and contraction of the particles has important consequences on the surface stability of these materials. Furthermore, the choice of electrolyte has profound impacts on the cycling of cells containing Si-based materials. In this presentation we will show the impact of electrolyte reactivity on the physical and chemical characteristics of the particles, the composition of the electrolyte and the cycling performance of the cells.

Cross section SEM studies of cycled 3M Si alloy and pure Si show the dimensional changes occurring in Si-based materials with cycling due to electrolyte reactivity. After 100 cycles, an SEI is found on the 3M active/inactive alloy, while the pure nano Silicon dramatically increases in size. Figure 1 shows cross section images of the electrodes containing only binder and either 3M Si alloy or pure Si. While electrolyte reactivity can occur with minimal fade in half cells, capacity fade will occur in full cells.

Fluoroethylene carbonate (FEC) has long been known to be an important electrolyte for Si-based materials. Furthermore, full cells containing Si-based materials can sometimes undergo sudden failure with cycling. GC/MS studies of electrolytes from cycled full cells containing Si-based materials will be presented showing the relationship between electrolyte composition and sudden failure. These results highlight the importance of full cell design optimization for the implementation of Si-based materials in commercially-relevant full cells.

Figure 1
Failure Mechanisms of Siox- Vs. Sife- Graphite Composite Anodes in Li-Ion Batteries
Authors: Sim Soojin , Cho Jaephil
Published: February 2020

Mobile IT battery market is encountered to development of anode materials with high capacity and long cycle life due to increasing consumers’ demands for longer operation time. To meet this requirement, change of cathode material can be considered at first, but any candidates cannot beat LiCoO2. Accordingly, it is natural to consider the capacity increase of the anode materials beyond 390mAh/g. To achieve this target, the mixture of graphite and Si materials should be modulated with controllable volume expansion of the composite.

Herein, we assembled full lithium ion cells containing SiOx- and SiFe- graphite (SiOx-G, SiFe-G) composite anodes with reversible capacity of 450mAh/g. Using these two materials, we carried out further experiments to elucidate the capacity fading mechanisms using XPS, XRD, HR-TEM, EDS etc. Preliminary result showed that electrolyte decomposition degree with each anode materials upon increasing cycle number significantly affected its structural stability.
Pre-Lithiated Silicon As the Anode Material for the Next Generation of Lithium Ion Batteries
Authors: Yang Yongan , Li Xuemin
Published: February 2020

It is widely believed that next generation of lithium ion batteries (LIBs) needs non-graphite anodes.  Among all anode materials scrutinized to date, silicon (Si) is one of the most promising ones, because of its exceptionally high charge capacity, earth abundance, low cost, and well-developed industrial infrastructure.  However, silicon suffers from a poor cyclability due to the volume fluctuation induced electrode damage during the lithiation/delithiation cycles.  To date, many strategies have been attempted to tackle this problem.  Pre-lithiated silicon (lithium silicide, LixSi) holds the promise for alleviating the poor-cyclability problem, as the pre-occupied space by Li can provide adequate volume for the subsequent lithiation/delithiation processes.  However, LixSi has high reactivity, the challenge in electrode fabrication is to prevent surface damage prior to battery assembly.

In this presentation, we will report our tactics of overcoming the challenge, starting from materials synthesis, structural characterizations, surface modification, and performance assessments.  Compared with the un-lithiated Si electrodes, the LixSi electrodes show much better charge capacity, cyclability, and rate capability.
A Stable Nanostructured Li-Deficient Oxide Thin-Film Electrode for Advanced Lithium-Ion Batteries
Authors: Tan Guoqiang , Wu Feng , Lu Jun , Amine Khalil
Published: February 2020

Recently, lithium-ion batteries have been used heavily in consumer electronics worldwide, and their use is expanding to electric vehicles and other high power transportation applications as their prices continue to decline. However, one of the main issues for the transportation application is the need to develop high-performance cathode materials. Here we report a novel nanostructured cathode material based on air-stable Li-deficient oxide thin film (Li0.28Co0.29Ni0.30Mn0.20O2) for high-energy density lithium-ion batteries. This film is preparedvia a method combining radio frequency magnetron sputtering and in-situ post-annealingusing a crystalline and stoichiometric LiCo1/3Ni1/3Mn1/3O2 target. ThisLi-deficient oxide thin film has a polycrystallinenanostructure, high tap density, and higher energy and power densitiescompared to the initial stoichiometric LiCo1/3Ni1/3Mn1/3O2. It surprisingly delivers large reversible capacity (216 mA h g−1), good cycle performance and superior rate capability. Such a materialis a promising cathode candidate for high-energy lithium-ion batteries,especially thin-film batteries.
Aerospace Applications of Conductive Polymers
Authors: Kinlen Patrick , Schuette Waynie
Published: February 2020

Historically, the aerospace industry has driven major developments in polymer and material science. Technology has evolved from wood and coated fabric to metals to advanced polymer composite systems in response to demands of both the commercial and defense aerospace industries. Future systems will require event more advanced technologies such as those afforded by electroactive and conductive polymers (EAPs). The unique properties of these materials provide the ability to construct intelligent systems which produce a defined, predictable response to an input. For example, as a corrosion protection coating, an EAP would sense corrosion at the molecular level and release a corrosion inhibitor before major damage could occur. A self-detoxifying system would sense a toxin and respond by releasing bactericide to kill it. As depicted below, material advancements being sought for future aerospace systems include:

Controllable optical absorption and emission across a wide spectral range

Tunable conductivity from 10-5 to >10,0000 S/cm for antistatic and shielding

Controlled, on demand release of active molecules for self-repair, detoxification and corrosion protection

High power energy storage and capture

This presentation will explore some of the issues involved with developing and transitioning EAP technology into current and future aerospace products.
Proton-Conducting Polymer Electrolytes for Solid Flexible Supercapacitors
Authors: Gao Han , Lian Keryn
Published: February 2020

Polymer electrolytes, acting as separator and ionic conductor, are key enablers for the next generation flexible supercapacitors. An ideal high-performance polymer electrolyte should exhibit: (i) high ionic conductivity; (ii) good ion accessibility at the electrode\electrolyte interface; (iii) wide electrochemical stability window; and (iv) high environmental and temperature stability. Although the conductivity of polymer electrolytes is typically a few orders of magnitude lower than that of their liquid counterparts, deploying them in the form of thin film can mitigate this issue and provide high rate and power performance in a supercapacitor device.

A typical solid polymer electrolyte consists of an ionic conductor, a polymer matrix, and additives. Heteropolyacids (HPAs) are excellent solid-state proton conductors at room temperature [1]. One of the common HPAs is silicotungstic acid (SiWA, H4SiW12O40•nH2O).

We have developed a polymer-in-salt electrolyte system for supercapacitors using SiWA and polyvinyl alcohol (PVA). A systematic approach has been used to improve the performance of SiWA-PVA polymer electrolytes through additives and polymer structural modifications. The electrolytes showed excellent proton conductivity, stability, and film flexibility that enables thin and light weight solid supercapacitors (Fig. 1). They also outperformed Nafion® in terms of environmental stability at ambient conditions [2].

These SiWA-based polymer electrolytes have demonstrated high rate performance in both electrochemical double layer capacitors and pseudo-capacitors [3-5]. The solid polymer electrolyte-based devices were able to charge and discharge up to 100 Vs-1, with a time constant of 10 ms [3-5]. To further expand the potential window of the SiWA-based electrolyte, and thus increase the energy density, alternative HPAs have been synthesized. In this talk, proton conductivity and structural properties of the developed polymer electrolytes will be discussed. Device performance of different HPA-based solid supercapacitors will be presented and compared.

References:

U. B. Mioè et al., Solid State Ionics, 176, 3005-3017 (2005).

H. Gao et al., Electrochem. Commun., 17, 48-51 (2012).

H. Gao and K. Lian, J. Mater. Chem., 22, 21272-21278 (2012).

H. Gao and K. Lian, J. Power Sources, 196, 8855-8857 (2011).

H. Gao et al., J. Power Sources, 222, 301-304 (2013).

  Fig. 1. Photographs of (a) a HPA-based polymer electrolyte film and (b) an assembled flexible solid supercapacitor.

Figure 1
Bio-Templated and Bio-Tethered Materials for a Flexible Lithium Ion Battery
Authors: Allen Mark A , Riley Scott J. , Barannikova Evgenia , Winton Alexander
Published: February 2020

Nature has a diverse toolkit that can be utilized to address a broad array of important chemistry related problems.  These tools include DNA, lipids, polysaccharides, and proteins, each of which have been used for direct applications from sensors to electronics.  Proteins represent nature’s most diverse polymer with a range of functionality determined by 20 naturally encoded amino acids.  The structure and chemical functionality of each amino acid determine the properties of the polypeptide that they compose.  In this presentation I will discuss the use of biomolecules in order to self-organize flexible electrodes for lithium ion batteries.  

The focus of my group is to identify functional polypeptides for the purpose of improving technologically relevant materials.  Our lab uses a technique called phage display in order to identify solid binding polypeptides that are specific for binding to and the mineralization of electroactive materials and use these materials to prepare new lithium ion batteries. Peptides that are identified are then genetically combined with other polypeptides in order to generate multi-functional polypeptides that can then be used to lash together myriad materials into a hierarchically assembled structure.  This current work focuses on making these materials more flexible through the addition of bio-molecules.
Developing Emulsion-Templated Silicon/Carbon Anodes with Reduced Graphene Oxide for Lithium Ion Batteries
Authors: Zhang Yuzi , Pan Yue , Chen Yanjing , Chen Chu , Lucht Brett L , Bose Arijit
Published: February 2020

Silicon (Si) is considered as one of the most promising candidates for next-generation lithium ion battery anodes owing to its superior theoretical capacity. However, Si suffers from a dramatic volume change during lithiation and delithiation, leading to pulverization and capacity decay. We report a simple oil-in-water emulsion-templating method to successfully fabricate high capacity and stable silicon/carbon anodes by directing Si and carbon to desired spatial locations. Because carbon does not contribute to capacity, we minimize the total amount of carbon in our anodes by using a mixture of carbon black (CB) and reduced graphene oxide (RGO) as the conducting phase. The low percolation threshold of the RGO reduces the anode impedance effectively. With 1 wt% RGO, the electrochemical half-cell tests using this structured Si/CB/RGO anodes show great improvements of capacity and retention after 50 cycles at a cycle rate of C/5 compared to the Si/CB control anodes. Emulsion-templating is a scalable colloidal principle based method for forming electrodes for rechargeable batteries.
(Invited) Novel Asymmetric Supercapacitor with Electrochemical Polymerized Conjugated Polymer and Vertically Aligned CNT
Authors: Zhu Yu
Published: February 2020

A novel phenanthridinone based conjugated monomers were directly polymerized by electrochemical polymerization on the ITO glass substrate. The resultant polymer contained removable side chains to generate the porous structure upon thermal annealing. The annealed polymer film was further doped to enhance the electrical conductivity. The area capacitance of the polymer thin film electrode reached 95 mF/cm2. This polymer film was used as the anode in the asymmetric supercapacitor and the vertically aligned carbon nanotubes were used as the cathode. The asymmetric supercapacitor device exhibited area based energy density over 300 μWh/cm2 and the capacitance retention reached 85% after 10000 cycles.

Figure 1
The Cycling Behaviour of MnO2 as Investigated By Synchrotron XRD, Stepped Potential Electrochemical Spectroscopy (SPECS) and Cycling on the Electrochemical Quartz Crystal Microbalance (EQCM)
Authors: Donne Scott W , Gibson Andrew J , Wood Ross , Dupont Madeleine F
Published: February 2020

Manganese oxides are promising materials for supercapacitor applications due to their low cost and relatively low toxicity, coupled with their high electrochemical activity [1].  MnO2 comes in many structural forms, with two main structural types to be discussed in this presentation.  The first being the layer structure which is favoured by many researchers as it is believed to be able to undergo repeated cycling. Layer structures involve the arrangement of component [MnO6] octahedra such that they form a coherent flat plane.  These flat planes are separated by charged species, with the number being dependent on the average oxidation state of the Mn in the layer.  Birnessite is a layered form of MnO2 with either sodium, potassium or water in the interlayer spacing.  Tunnel structures involve the arrangement of component [MnO6] octahedra in such a manner as to generate tunnels that run in one direction through the structure, with width and height equal to between one and three octahedra; the width and height do not need to be equal.  Ramsdellite and Pyrolusite are both tunnel structures, with tunnel dimensions being 2 x 1 and 1 x 1 respectively [2]. 

One possible problem with the long term utilisation of pseudo capacitors, such as metal oxides, is that they can undergo structural change during cycling.  This presentation will cover the cycling behaviour of Birnessite, Ramsdellite and Pyrolusite as examined by a number of different techniques.  SPECS experiments performed in-situ at the Australian Synchrotron to map structural changes with respect to the state of charge of a manganese oxide material.  In addition, data obtained on the mass changes during SPECS cycling of the three phases on the EQCM will be presented.  The mass change, when corroborated with the amount of charge passed, gives information about the type of ions being inserted into the structure.  In the case of these experiments, % values of K+ and H+ insertion have been obtained.  In addition, values for retention of these ions during repeated cycling have been elucidated, which will provide valuable information for researchers engaging in the intelligent design of electrochemical capacitors utilising MnO2.

References

1. Wei, W., et al., Manganese oxide-based materials as electrochemical supercapacitor electrodes. Chemical Society Reviews, 2011(40): p. 1697 - 1721.

2. Post, J.E., Manganese oxide minerals: crystal structures and economic and environmental significance. Proceedings of the National Academy of Science, USA, 1999: p. 3477.
Porous Titania conformal Coating on Carbon Nanotubes As Energy Storage Materials
Authors: Yan Litao , Zhou Meng , Chen Gen , Luo Hongmei
Published: February 2020

The controllable synthesis of strongly coupled inorganic materials/carbon nanotubes (CNTs) hybrids represents a long-standing challenge for developing advanced catalysts and energy-storage materials. Here we report a simple sol-gel method for facile synthesis of TiO2/CNTs hybrid. The porous anatase TiO2 nanoparticles are uniformly coated on the CNTs conducting network, which leads to remarkably improved electrochemical performances such as exceptional cycling stability, good high rate durability, and reduced resistance. This hybrid exhibits a reversible capacity as high as 200 mA∙h g-
1 at a current density of 0.1 A g-1 as an anode in lithium-ion battery (LIB). As a supercapacitor (SC), it shows a specific supercapacitance of 145 F g−
1 in 0.5 M H2SO4 electrolyte, higher than that of the previously reported TiO2 based supercapacitors. Moreover, this hybrid also exhibits excellent durability after 1000 cycles for both LIBs and SCs. Such superior performance and cycling durability demonstrate the reinforced synergistic effects between the porous TiO2 and interweaved CNTs network, indicating a great application potential for such hybrid materials in high power LIBs and SCs.
Active Material Arrangement and Its Effect on Electronic Conductivity in a Suspension Electrode
Authors: Hatzell Kelsey B. , Eller Jens , Gogotsi Yury
Published: February 2020

Flowable or suspension electrodes are multiphase electrode systems, where an active solid material is suspended in electrolytic medium. Suspension electrodes have been demonstrated for large-scale energy storage [1], water deionization [2-4], and energy generation applications [5].

      Several material chemistries have been examined in a suspension form, and all systems rely on the use of carbon-based materials to form percolation networks for efficient electron transport. Suspension electrodes based on metal oxides typically demonstrate low electrical conductivities (~10-6 mS/cm) and require the addition of conductive additives to enable efficient charge storage and rate handling. Capacitive suspension electrodes, composed of activated carbon, are significantly more conducting than those based on metal oxides (~10-1-100 mS/cm). Nevertheless, both types of suspension electrodes display electrical conductivities significantly lower than their film counterparts, because of the presence of a highly resistive solution region. One solution to this challenge is the addition of more conducting materials (carbon black or activated carbon) or controlled arrangement of the active material. The former results in high viscosity material systems which are challenging to flow.

      The arrangement of the active and inactive material in a suspension electrode is expected to affect charge and ion percolation and material utilization in a suspension electrode. In this work we compare DC and AC electronic conductivity measurement techniques, and present work on visualization of the active material arrangement in a suspension electrode.

 

 

References:

[1]. K.B. Hatzell, M. Boota, E. C. Kumbur, and Y. Gogotsi. Journal of The Electrochemical Society 162, no. 5 (2015): A5007-A5012.

[2]  K.B.  Hatzell, M.C. Hatzell, K.M. Cook., M.  Boota,  G. M. Housel, A.McBride,  E.Caglan Kumbur. Y. Gogotsi, Environmental science & technology, (2015) 49(5), 3040-3047.

 [3] S.-I. Jeon, H.-R Park, J.-G. Yeo, S. Yang, C.H. Cho, M.H. Han, D.K. Kim, Energy & Environmental Science, 6 (2013) 1471-1475.

[4.] K.B. Hatzell, E. Iwama, A. Ferris, B. Daffos, K. Urita, T. Tzedakis, F. Chauvet, P.-L. Taberna, Y. Gogotsi, P. Simon, Electrochemistry Communications, 43 (2014) 18-21.

[5] M.C. Hatzell., K.B. Hatzell, and B.E. Logan. Environmental Science & Technology Letters 1.12 (2014): 474-478.
Supercapacitors Performance Evaluation
Authors: Zhang Sanliang
Published: February 2020

The performance of a supercapacitor can be characterized by a series of key parameters, including for instance the cell capacitance, operating voltage, equivalent series resistance, power density, energy density, and time constant. To accurately measure these parameters, a variety of methods have been proposed and used among academia and industry. As a result, some confusion has been caused due to the inconsistencies between different evaluation methods and practices. Such confusion hinders effective communication of new research findings, and creates a hurdle in transferring novel supercapacitor technologies from research labs to commercial applications.

Based on public sources, this review article is an attempt to inventory, critique and hopefully streamline the commonly used instruments, key performance metrics, calculation methods, and major affecting factors for supercapacitor performance evaluation. Thereafter the primary sources of inconsistencies are identified and the possible solutions are suggested correspondingly, with emphasis on device performance vs. material property and the rate dependency of supercapacitors. We hope, by using reliable, intrinsic and comparable parameters produced, the existing inconsistencies and confusion can be largely eliminated so as to facilitate further progress in the field.
Low-Temperature Chemical Passivation Routes for Integration of Supercapacitors Directly into Silicon Solar Cells
Authors: Westover Andrew S , Metke Thomas , Afolabi Jeremiah , Share Keith , Carter Rachel E. , Cohn Adam P , Oakes Landon , Pint Cary L.
Published: February 2020

Due to the intermittent nature of renewable energy sources such as solar and wind energy, systems designed to convert grid-scale power from these resources must be coupled with energy storage for off-grid operation.  Traditional routes to coupling energy storage with energy conversion systems consists of an energy storage device situated external to the energy conversion system.  However, direct integration of both systems offers numerous advantages, such as multipurposing of materials and storage directly at the point of generation to mitigate DC-AC inversion.  Our recent efforts have demonstrated the ability to utilize the excess silicon material in a polycrystalline solar cell for supercapacitor energy storage applications.  However, a key challenge that remains is to develop chemical passivation routes at low temperatures that can preserve the solar cell P-N junction and yield a passive silicon energy storage interface with a solid-state electrolyte.  We address this issue by exploring multiple routes for low-temperature passivation, specifically including (i) wet chemical passivation of porous silicon using thin film metal coatings, and (ii) electrochemical passivation of porous silicon using conductive polymer networks.  Our efforts demonstrate these passivation routes as being promising for the development of fully integrated energy storage and conversion systems applicable toward a range of applications ranging from grid-scale storage to remote energy transfer applications.
The Status of SOFC R&D in the Fuel Cell and Hydrogen Joint Undertaking Program
Authors: Atanasiu Mirela
Published: February 2020

The Fuel Cells and Hydrogen Joint Undertaking (FCH JU) was set up in 2008 to accelerate the development of fuel cells and hydrogen technologies in Europe towards commercialization from 2015 onwards. To reach this target the FCH JU intends to bring together resources under a cohesive public-private partnership to ensure commercial focus, to match RTD activities to industry's needs and expectations and to scale-up and intensify links between the Industry Community and the Research Community. The applications are open to all fuel cells technologies, SOFC being mostly developed for the stationary applications, including back-up powers and APUs for transportation (trucks, planes). There are different groups working in Europe and supported partially by the FCH JU on the SOFC technology. By supporting such a project portfolio, FCH JU is going to reach most of the objectives set-up at European level mainly in terms of potential reduction of costs through sufficient number of units demonstrated across Europe in transport and stationary applications. The EU public support will continue for the next period of 2014-2020 for activities with an advanced TRL, moving towards market penetration of the FCH technologies.
In-Situ Analysis of Co-Electrolysis Species Via Diffuse Reflectance Infrared Fourier Transform Spectroscopy (DRIFTS)
Authors: Tumilson Christopher , Cumming Denis J , Taylor S.F. Rebecca , Call Ann V , Hardacre Chris , Elder Rachael H
Published: February 2020

Syngas production through co-electrolysis of steam and carbon dioxide has been shown as an effective method of CO2 utilisation, however little is known about the complex surface reaction mechanisms involved.  Further understanding is needed in order to optimise SOC operation parameters and inform materials development.  Currently many investigative techniques are ex-situ, some of which are even destructive: e.g. SEM imagining of the microstructure.  To fully understand reaction intermediates, characterise electrochemical performance, and develop novel materials and microstructures for co-electrolysis SOCs; in-situ analysis methods are required.

The EPSRC funded research programme, 4CU aims to enhance the fundamental understanding of CO2 and its role in co-electrolysis by developing a suite of in-situ investigative methods for high temperature SOC operation.  Using Diffuse Reflectance Infrared Fourier Transform Spectroscopy (DRIFTS) we can monitor both adsorbed and gas phase species in-situ.  Variation of potential and temperature conditions allow for visualization of surface mechanisms associated with single atmosphere fuel cell operation.  This, along with dual atmosphere measurements, will be discussed.  This work illustrates the applicability of the new technique for SOCs operated in a range of atmospheres using Au, Pt and Ag electrodes.  The comparison of potential dependent DRIFTS combined with electrochemical measurements provides an important insight into the roles of oxygen ion and proton transport within the systems studied.

Figure 1
Long Term Stability Investigation of Solid Oxide Electrolysis Cell with Infiltrated Porous YSZ Air Electrode Under High Current
Authors: Veltzé Sune , Küngas Rainer , Ovtar Simona , Simonsen Søren Bredmose , Thydén Kar Tor Sune , Kiebach Wolff-Ragnar
Published: February 2020

The increased interest in stable and low cost electrodes for solid oxide cells (SOC) has driven the research of electrode preparation to infiltration of catalyst material into porous backbone material. The infiltration method enables a reduction of amount of catalyst material and increases its activity, due to high surface area of  catalyst nano particles. Advantage of infiltration is also separate production of electrolyte backbone structure with good ionic connectivity and mechanical properties.

With this study we present the results of a solid oxide cell with infiltrated porous yttria stabilised zirconia (YSZ) backbone air electrode and Ni/YSZ cermet fuel electrode. The SOC was tested at electrolysis conditions under high current (up to -1 A/cm2). The porous YSZ electrodes was infiltrated with gadolinium-doped ceria oxide (CGO), to act as a barrier layer between the catalyst and the backbone, and perovskite catalyst material. Cobalt doped lanthanum nickelate was used as the perovskite catalyst due to its excellent performance.  The cell was tested in steam electrolysis for at least 2000h. This initial test indicate that a stable air electrode was formed, and that the cell performance and stability matches that of a state-of-the-art SOC.
In-Situ Surface Analysis of SOFC Cathode Degradation Using High Temperature Environmental Scanning Electron Microscopy
Authors: Niania Mathew , Podor Renaud , Skinner Stephen J. , Kilner John A.
Published: February 2020

Solid Oxide Fuel Cell (SOFC) cathode materials rely on the catalytic processes at their surfaces to reduce and incorporate oxygen. For many common cathode materials surface passivation occurs through 'A site' segregation at common operating temperatures [1]. These processes have a negative effect upon the oxygen reduction rates and therefore overall cell performance. Quantifying the true extent these segregation effects have on the exchange properties has not been fully explored but it is clear that the properties of the surface are essential.

Many techniques have been employed to study cell properties in-situ, however, surface studies are typically restricted to post mortem or ex-situ analysis due to the necessity of a high vacuum. In this study High Temperature Environmental Scanning Electron Microscopy (HT-ESEM) has been employed to analyse the morphology changes of common SOFC cathode materials in-situ. Samples of La0.6Sr0.4Co0.2Fe0.8O3-x (LSCF) and La0.6Sr0.4CoO3-x (LSC) were annealed from room temperature to 1000oC at pressure ranges between 3 – 6mbar in atmospheres of Oxygen and Water. Using secondary electron imaging during the thermal annealing cycle morphological and compositional changes were able to be documented at temperature for the first time (Figure 1).

This technique has enabled detailed analysis of the surface degradation that occurs during SOFC fuel cell operation. Secondary phase precipitation rate and formation behaviour has been quantified over a range of temperatures and time scales furthering the understanding of SOFC cathode surfaces significantly.

[1] M. Kubicek, A. Limbeck, T. Fromling, H. Hutter, and J. Fleig, "Relationship between cation segregation and the electrochemical oxygen reduction kinetics of La0.6Sr0.4Co0.2Fe0.8O3 thin film electrodes" Journal of The Electrochemical Society, vol. 158, no. 6, pp. B727–B734, 2011.

Figure 1 - Showing in-situ growth of secondary phase particulates on a polished surface of LSCF

Figure 1