bluuebunny/crossref_metadata_2025 huggingface dataset:
Electrochemical Fabrication and Characterization of Alloy Anode Materials
Authors: Yeon Geonheum , Kim Sunjung
Published: February 2020

Studies on secondary batteries with increased specific capacity and more stable charge-discharge performance have been actively conducted. Sn anode has a higher specific capacity than conventional carbon anode; however, the large volume change and cracking of the Sn anode occurs due to de-lithiation reaction during repetitive charge-discharge process. On the other hand, the Ni anode material is highly resistant to cracking during charge-discharge process. Therefore, in this study, the electrochemical formation of porous Sn-Ni alloy anode material is investigated using a polyurethane template of three-dimensional open-cell structure for lithium ion batteries having high specific capacity and improved structural reliability.
Lithium Nickel Manganese Oxide-Carbon Composite Nanoparticles Synthesized By a Flame Spray Pyrolysis Process
Authors: Ramadhan Zeno Rizqi , Kim Yong Hyun
Published: February 2020

The nanoparticles based on either nickel-manganese oxide or carbon-coated LiNi0.5Mn1.5O4 are synthesized by flame spray pyrolysis technology with controlled particle sizes. The structural properties of nanoparticles are characterized by x-ray diffraction and high resolution electron microscopy. It is observed that the higher surface tension of precursors in the flame spray pyrolysis setup increases the particle sizes. The post annealing treatment significantly enhances the crystallinity of nanoparticles due to the favorable oxidation process and the structure conversion from NiMn2O4 to NiMnO3. In addition, the solid state reaction of as-prepared NiMn2O4 results in the LiNi0.5Mn1.5O4 nanoparticles which can be applied to cathode materials in Li-Ion batteries. The carbon-coated LiNi0.5Mn1.5O4 nanoparticles are also made by additional carbonization reaction. The control of surface tension of precursors in the flame spray pyrolysis process is expected to result in the small size of nanoparticles for cathode materials in high cyclic stability and high capacity Li-ion batteries.
Influence of Defect Reaction on Electrical/Electrochemical Behaviors of Oxide Electrodes for Li Batteries
Authors: Fung Kuan-Zong , Chang Li-Fu , Tsai Shu-Yi , Huang Bo-Yuan
Published: February 2020

Functional oxides are known to show interesting electrical properties by introduction of desired defect structures. Electrode performance in Li batteries is also highly dependent on its defect reaction through synthesis and/or charging-discharging cycles. For examples, the reversible capacity of layered cathode such as LiCoO2 is limited by its highly defective layered structure when state of charge greater than 50%. On the other hand, capacity of spinel or olivine cathodes shows higher delithiation rate due to better structural stability. In this study, the behavior of Li-rich layered oxide cathode and Li4Ti5O12 (LTO) are investigated and illustrated based on their defect reactions.

For examples, the as-received zero-stain anode oxide Li4Ti5O12 shows conductivity as low as 10-9 S/cm and then causes high interface polarization and low rate capability. With proper processing under low pO2, the electron conduction and electrochemical properties of LTO was significantly improved. Such property enhancement may be well illustrated by defect reaction under low pO2 environment. In other words, lattice oxygen near surface of LTO tends to be removed under very low pO2. Consequently, positively charged oxygen vacancy is formed and then charge-compensated by the creation of two negatively charged electrons. These electrons are eventually associated with tetravalent Ti ions. The fast electron pathway is established by the coexistence of Ti+3 and Ti+4 in Ti cation sublattice.

Furthermore, Li-rich layer-structured cathode formulated as xLi2MnO3-(1-x)LiMO2(M = Mn, Ni, Co, etc.) during 1st charging process was found to exhibit oxygen oxidation, vacancy formation. In the following discharging, the manganese reduction (or activation) occurred. As a result, a reversible capacity as high as 250 mAh/g was observed (Fig. 1(a)). Such redox reactions may be illustrated by defect chemistry. In other words, during 1st charging, electrons and oxygen was extracted from lattice oxygen with the formation of oxygen vacancies. In the next discharging process, electrons was accepted by cathode oxides accompanied by valence changing of Mn+4 to Mn+3.

It is known that typical electrochemical reactions are highly dependent up movement of electrons and ions. With understanding of defect reaction during materials processing and charging/discharging, advanced electrode materials with much improved electrochemical and/or stability may be developed.
Low-Cost Alternatives to Pedot:PSS As Conducting Binders
Authors: Kuss Christian
Published: February 2020

Pedot:PSS is a molecular level composite material of conjugated polymer (Pedot) and anionic polyelectrolyte, or polyanion (PSS). It is popular in organic electronics and as transparent conductor, because it is water dispersible, conductive and film-forming upon drying. For the same reasons, Pedot:PSS has previously been suggested as binder in lithium-ion batteries. However, its high cost is prohibitive for routine battery applications. This presentation discusses our exploration of chemically similar, but lower-cost molecular polymer composites of conjugated polymers and polyanions, to be used as lithium- and sodium-ion battery binders. Within these composites, the conjugated polymer serves to deliver electronic conductivity, whereas the polyanion allows dispersion of the composite, and provides strong adhesion to battery particles. We perform the oxidative polymerization in the presence of the polyanion, at which the polyanion backbone serves as polymerization template. In this way, the latter becomes a permanently intertwined polymeric dopant within the conjugated polymer.

We are presenting data on the electrochemical stability of these binders within typical battery environments and the dependence of electronic conductivity on composition and synthesis methods. Moreover, composite battery electrodes have been fabricated and electrode micro-structure and cycling performance data are presented. Examples are selected based on low-cost polymers of Pyrrole and Aniline, combined with non-traditional polyanion binders, such as Carboxymethyl Cellulose and Alginate.

The target of this work is to improve cycling performance of high-capacity, high-volume-change intercalation materials. In traditional composite lithium and sodium intercalation electrodes, such intercalation materials exhibit very little adhesive strength with the typical carbon conductive additive. By combining the adhesive and conductive additive within a single molecular composite binder, the conductor adheres directly to the intercalation material, accommodating volume changes more easily and improving lifetime of high capacity materials.
Electrochemical Cycling Induced Amorphization of Cobalt (II, III) Oxide (Co3O4) for High Surface Area Electrode of Water Oxidation
Authors: Gupta Prashant Kumar , Saha Sulay , Kishor Koshal , Gyanprakash Maurya , Pala Raj Ganesh
Published: February 2020

Electrocatalyst’s activity critically depends on the chemical coordination structure around the active sites. Amorphous materials are having different local short-range structure than their counter crystalline materials which can be tuned by the synthesis process. Traditional synthesis of amorphous materials, involving multi-temperature quench processing, is unsuitable as it results in less porosity and surface area. In this context, room temperature synthesis of high surface area amorphous materials with high activity are desirable. Here we have demonstrated the synthesis of high surface area amorphous Co3O4 at room temperature via electrochemical ion intercalation/deintercalation and surface oxidation/reduction cycles and their performance in electrocatalytic oxygen evolution reaction (OER). In Li-ion intercalation/deintercalation (Li/D-Li) cycles in Co3O4 expansion and contraction of the structure induces amorphization of Co3O4 by the pulverization of crystal structure in non-aqueous medium. While during the fast surface oxidation/reduction (Ox/Red) the crystalline nuclei formation and its growth in oxide state is hindered thereby leading to formation of metastable amorphous structure in aqueous medium. The OER specific activity for Li/D-Li-Co3O4 is ~35 times, which is superior to Ox/Red- induced amorphization which is ~25 times higher than their crystalline Co3O4. The superior OER metrics with Li/D-Li-Co3O4 is attributed to Li-ion intercalations inside Co3O4 structure which generates higher bulk-oxygen vacancies upon Li/D-Li- leading to higher conductivity and reduction in overall charge-transport resistance through electrocatalyst. On the other hand, Ox/Red- induced amorphization is restricted to surface or near-surface only with formation of small amount of metallic Co which hampers in increase of active sites for OER. However, in general both amorphization process leads to increase in Co (II) sites which is responsible for increased OER activity over crystalline Co3O4. Additionally, the above study demonstrates the utility of multicycle lithiation/de-lithiation over surface oxidation/reduction technique for obtaining amorphous OER electrocatalysts
Insights into Electrolyte Decomposition Phenomena Utilizing Solid Phase Microextraction - Gas Chromatography - Mass Spectrometry in Combination with an in Situ Lithium Ion Cell
Authors: Horsthemke Fabian , Winkler Volker , Friesen Alex , Winter Martin , Nowak Sascha
Published: February 2020

In the last decades, the interest in lithium ion battery (LIB) technology has been rising steadily and thereby the system became an important field for scientific research. Numerous techniques for post mortem analysis of battery materials have been reported in literature - ranging from surface investigation e.g. scanning electron microscopy (SEM) to the analysis of the emerging passivation layers or the investigation of the liquid electrolytes. The analysis of the LIB electrolytes is of special interest due to their instability at typical electrode potentials. Thereby the aging phenomena in the electrolyte, which is in contact with all parts of the LIB, are a good indicator for the cell status. However, the state-of-the-art sample preparation for electrolyte analysis requires the mechanical opening of the cell and subsequent electrolyte extraction.[1] Thus, the cells are destroyed during the sample preparation and it is not possible to achieve data for multiple different states-of-health (SOHs) of one specific cell. The gas chromatography - mass spectrometry (GC-MS) provides the option to analyze the gases above a heated sample making the typically applied carbonate solvents accessible. However, the sample heating is not compatible with the commonly applied conducting salt (LiPF6) and thereby introducing additional aging phenomena. Therefore, an automated sample pretreatment was considered, which was developed in the work group of Pawliszyn.[2] The Solid phase microextraction (SPME) in combination with GC-MS provides several benefits with regard to the LIB environment - namely the headspace sampling option, the preconcentration of volatile organic compounds at room temperature and the small amount of removed sample.[3]

This work reports on the development of a round cell (18650 format) for in situ investigations of the electrolyte. Proof of principle experiments have been executed with different setups relying on passive diffusion or utilizing a peristaltic pump for enhanced analyte uptake. Emerging decomposition products and consumed film forming additives have been analyzed at different SOHs. The cell response to the sampling procedure was investigated by C-rate tests, which did not show significant changes. Furthermore, the cell setup provides the possibility to investigate the electrolyte during charge / discharge operation, which might prove or disprove assumed changes in the electrolytes during cell operation.

[1] Mönnighoff, X. et al., Journal of Power Sources
2017,
352, 56-63.

[2] C. L. Arthur and J. Pawliszyn, Analytical Chemistry, 1990, 62, 2145-2148.

[3] Horsthemke, F. et al., RSC Advances
2017,
7 (74), 46989-46998.
Rational Design and in-Situ Electrochemical Characterization of Low Dimensional Nanomaterials and Devices for Energy Storage
Authors: Zhao Yunlong
Published: February 2020

Developing high performance energy storage devices such as metal ion batteries and supercapacitors are important for portable electronics, vehicle electrification and smart grid, while developing techniques for electrochemical monitoring that offer higher spatial and temporal resolution would open up new ways to study electrochemical interfaces and reaction kinetics for further developing novel energy storage devices. In this talk, I will introduce our recently developed materials optimization strategies and techniques to address their critical performance parameters related to energy density, power density, cycle, calendar life, and realize electrochemical monitoring, which includes (1) development of wafer-scale large-scale, shape & strain-controlled deterministic one-dimensional material assembly technique[1], which can be used for fabrication of single crystal nano-/microscale electrochemical devices array for in-situ electrochemical probing[2]; (2) synthesis and in-situ TEM characterization of self-adaptive strain-relaxed structure with high-stretchy protective shells through homogeneously crumpling of 3D graphene electrode showing high specific capacity, fast charge-discharge rate and long cycling stability for high-energy lithium battery materials[3]; and (3) operando observation of coupled discontinuous–continuous transitions in a series of ion-stabilized intercalation cathode[4], showing that the continuous transition at the intralayer could inhabit the irreversible ion intercalation and the consequent irreversible phase transition, while the discontinuous transitions at the interlayer of layered cathode provides the rapid adjustments in diffusion channels for the fast charge and discharge[5].

Reference:

Y. Zhao, J. Yao, C.M. Lieber, et al. Shape-controlled deterministic assembly of nanowires. Nano Letters
2016, 16.4, 2644.

L. Mai, M. Yan, Y. Zhao. Track batteries degrading in real time. Nature
2017, 546.7659, 469

Y. Zhao, J. Feng, X. Liu, et al. Self-adaptive strain-relaxation optimization for high-energy lithium storage material through crumpling of graphene. Nature Communications
2014, 5.

Y. Zhao, C. Han, et al. Stable alkali metal ion intercalation compounds as optimized metal oxide nanowire cathodes for lithium batteries. Nano Letters
2015, 15.3, 2180.

G. Zhang, T. Xiong, Y. Zhao. Operando observation of coupled discontinuous–continuous transitions in ion-stabilized intercalation cathode. Submitted.
Symmetric Cell Study of Ferri/Ferrocyanide Stability As a Flow Battery Active Material
Authors: Fell Eric M. , De Porcellinis Diana , Wong Andrew A. , Goulet Marc-Antoni , Aziz Michael J.
Published: February 2020

The attraction of aqueous organic redox flow batteries (AORFBs) lies in the potential for low mass-production cost and long lifetime of the organic reactants. To reach a cell potential greater than 1.0 V, several AORFBs have employed the ferri/ferrocyanide redox couple as a positive electrolyte (posolyte) in an alkaline full cell. Recent works [1,2] have reported significant amounts of capacity fade of this redox couple at high pH, attributed to an apparent chemical decomposition associated with cyanide ligand dissociation and subsequent irreversible hydroxylation of the iron complex.

An in-depth analysis of the chemical and electrochemical stability of ferri/ferrocyanide is performed utilizing a volumetrically unbalanced, compositionally-symmetric cell method [3]. The dependence on pH of the apparent interaction of carbonaceous electrodes with active species will be reported, and keys to suppressing electrolyte degradation will be discussed. The accuracy of electrochemical techniques (e.g. high-precision coulometry) and chemical characterization (e.g. NMR, UV-vis) to understand ferri/ferrocyanide degradation will also be compared. Collectively, these results will highlight opportunities for improving energy storage systems.

[1] J. Luo, A. Sam, B. Hu, C. DeBruler, X. Wei, W. Wang, and T.L. Liu, “Unraveling pH dependent cycling stability of ferricyanide/ferrocyanide in redox flow batteries”, Nano Energy
42, 215 (2017).

[2] J. Luo, B. Hu, C. Debruler, Y. Bi, Y. Zhao, B. Yuan, M. Hu, W. Wu, and T.L. Liu, “Unprecedented Capacity and Stability of Ammonium Ferrocyanide Catholyte in pH Neutral Aqueous Redox Flow Batteries”, Joule, in press (2018).

[3] M-A. Goulet, M.J. Aziz, “Flow Battery Molecular Reactant Stability Determined by Symmetric Cell Cycling Methods”, Journal of the Electrochemical Society
165, A1466 (2018).
Understanding Electrocatalytic Pathways in Complex Organic and Inorganic Composites in Aqueous and Non Aqueous Environments
Authors: Mukerjee Sanjeev , Jia Qingying
Published: February 2020

There are very few techniques that lend themselves to rigorous requirements, where the individual role of different transition metal components of nano-phasic materials can be investigated in both amorphous and crystalline forms. We have validated a new analytical technique along with theoretical calculations, which enables the amount and specific adsorption site of species such as H, OH, O, CO, other C1 moieties and even anions such as bisulfate to be determined in situ on a metal surfaces using synchrotron XANES data. This technique, commonly called the ‘Delta Mu (∆μ) Technique’ can be taken in situ in both electrochemical cells and operating fuel cells, and can be obtained from a wide variety of transition metal surfaces and alloys,[3] including non-Pt based metal electrocatalysts with element specificity. EXAFS data taken concurrently provide information on the changes in short range atomic order around the absorber atom thereby providing structural information such as bond distances and coordination numbers (thereby information on average cluster size, homogeneity and surface segregation etc.).

In this part of the presentation among other things we will show in-situ XAS study of group of (Metal-Nitrogen-Carbon) MNC catalysts from perspective of metal center. We will demonstrate the presence of ORR active bio-mimetic porphyrin-like FeNx functionalities, as well as other forms of the metal which indicate no catalytic activity. The XAS in-situ studies will be combined with electroanalytical evaluations using cyclic voltammetry (CV) and square wave voltammetry (SWV). Further the factors governing the ORR activity at MNC centers, such as the Lewis basicity of the carbon support and the accompanying changes in the redox potential of the metal center will be discussed. This part of the presentation will bring together electrochemistry and XAS spectroscopy (including ∆μ) on effect of pH (inner and outer sphere charge transfer) and aqueous vs. non-aqueous electrolyte (concerted vs. non-concerted charge transfer).
Study of Sulfur-Based Electrodes By Operando Acoustic Emission
Authors: Lemarie Quentin , Idrissi Hassane , Alloin Fannie , Maire Eric , Thivel Pierre-Xavier , Roué Lionel
Published: February 2020

The acoustic emission (AE) technique has been widely used since the 70’s for detecting anomalies such as leakages and cracks on large structure (e.g. bridges, pressure containers, and pipe lines). The analysis of the AE signals (transient elastic waves) can also be used to characterize the degradation mechanisms (crack growth, friction, delamination, matrix cracking, corrosion, etc) of various materials subjected to a stress by mechanical, pressure or thermal means. Recently, AE technique has also been used to evaluate the degradation of metal hydride electrodes for Ni-MH [1] and Si-based electrodes for Li-ion batteries [2,3]. Cracking of the active material and gas evolution are the main sources of AE signals identified in these studies.

In the present study, the AE technique is used for studying upon cycling the mechanical degradation of S-based electrodes for Li/S batteries. The AE signals were recorded by a piezoelectric transducer fixed on the back of the working electrode. S-based electrodes made with two different binders (PVdF vs. CMC) and two different current collectors (standard Al foil vs. porous 3D carbon paper) were studied. In all cases, AE signals were mainly detected during the first plateau of the first discharge, suggesting that the electrode degradation mostly occurs during the initial dissolution of the S8 particles. AE signals were also detected during a few subsequent cycles when CMC binder is used. This is attributed to a better propagation of the AE signals through the electrode thanks to an improved adhesion of the electrode to the current collector in comparison to PVdF binder. This is confirmed by further mechanical resistance testing (peel and scratch tests). The use of a carbon paper as a current collector combined to CMC binder greatly improves the electrochemical performance of the S electrode by preventing the collapse of the electrode upon cycling. This electrode also presents an increased amount of AE signals, suggesting that the carbon fibres of the C paper act as an AE waveguide.

This study demonstrated that AE could be used as an efficient tool to monitor the morphological degradation of S-based electrodes upon their cycling and offers relevant information for optimizing their formulation and architecture.

A. Etiemble, H. Idrissi, P. Bernard, L. Roué. New insights into the pulverization of
LaNi5-based alloys with different Co contents from electrochemical acoustic emission measurements. Electrochim. Acta 186 (2015) 112-116

A. Tranchot, A. Etiemble, P-X. Thivel, H. Idrissi., L. Roué. In-situ acoustic emission study of Si-based electrodes for Li-ion batteries, J. Power Sources 279 (2015) 259-266.

A. Tranchot, P-X. Thivel, H. Idrissi, L. Roué. Influence of the Si particle size on the mechanical stability of Si-based electrodes evaluated by in-operando dilatometry and acoustic emission. J. Power Sources 330 (2016) 253-260.

Figure 1
Zinc Oxide Nanoparticles Anchored Graphitic Carbon Nanofibers: Strategies for Improving Supercapacitive Performance
Authors: Dillip G.R. , Bai Fan , Joo Sang W.
Published: February 2020

Graphitic carbon nanofibers (CNFs) decorated with ZnO nanoparticles (NPs) were synthesized by chemical co-precipitation method. This report demonstrates an effective strategy to intrinsically improve the conductivity and supercapacitive performance of the hybrids by inducing oxygen vacancies. Oxygen deficiency-related defect analyses were performed qualitatively as well as quantitatively using Fourier transform infrared spectroscopy, energy dispersive X-ray spectroscopy, and X-ray photoelectron spectroscopy. All of the analyses clearly indicate an increase in oxygen deficiencies in the hybrids with an increase in the vacuum-annealing temperature. At a current density of 3 A g-1, the hybrid electrode exhibited higher energy density (119.85 Wh kg-1) and power density (19.225 kW kg-1) compared to a control ZnO electrode (48.01 Wh kg-1 and 17.687 kW kg-1). The enhanced supercapacitive performance is mainly ascribed to the good interfacial contact between CNF and ZnO, high oxygen deficiency, and fewer defects in the hybrid. Our results are expected to provide new insights into improving the electrochemical properties of various composites/hybrids.

(1) Mefford, J. T.; Hardin, W. G.; Dai, S.; Johnston, K. P.; Stevenson, K. J. Nat. Mater.
2014, 13, 726-732.

(2) G.R. Dillip, A.N. Banerjee, V.C. Anitha, B. Deva Prasad Raju, S.W. Joo, and B.K. Min, ACS Appl. Mater. Interfaces 8, 5025 (2016).

(3) G.R. Dillip, A.N. Banerjee, V.C. Anitha, S.W. Joo, B.K. Min, S.Y. Sawant, and M.H. Cho, ChemPhysChem 16, 3214 (2015).
(Invited) Interfacial Stability and Conductivity of Solid Electrolytes: Insights Gained from in Situ and Functional Electron Microscopy
Authors: Chi Miaofang
Published: February 2020

In spite of different chemistries, many novel battery configurations, e.g., Li- air, Li-S, aqueous, and all-solid-state Li batteries, etc., share the same concept of using solid electrolyte materials to enable the use of lithium metal. An ideal solid electrolyte material must be highly ionically conductive and exhibit desirable stabilitywith metallic lithium. Over the past several decades, new solid electrolyte materials were developed that demonstrated high conductivity. However, the interfaces, including both internal grain boundaries within solid electrolytes and external interfaces between solid electrolytes and electrode, often show unexpected resistivity, degraded cyclability and vulnerability to dendrite propagation, presenting the current major limitations in realizing the practical application of solid electrolytes. Understanding what is happening at these interfaces at sufficient spatial, temporal and chemical resolutions are critical but challenging, due to spatial confinement and structural complications. Our research focuses on utilizing and developing advanced in situ and functional scanning transmission electron microscopy (STEM) to elucidate fundamental issues that lead to limited performance of interfaces in solid electrolytes, and to provide insights into the design and the engineering of high-performance interfaces. In this presentation, I will give several examples to demonstrate some of our recent studies in (i) elucidating the preferred dendrite-propagation at grain boundaries in the garnet-structured Al-Li7La3Zr2O12(LLZO); (ii) evaluating ion mobilities of H+and Li+ions individually in LLZO critical to its applications as a protection layer in aqueous batteries; and (iii) understanding the interfacial resistivity of LIPON with Li metal anode. Our results not only provide valuable insights into the understanding and the design of interfaces in Li-metal batteries, but also offer unique characterization methods that are generally applicable into the fundamental studies of solid-solid interfaces that involve mobile charge species and/or extremely chemically-active metallic lithium.

Acknowledgement

Research sponsored by the Materials Sciences and Engineering Division, Office of Basic Energy Sciences, U.S. Department of Energy. Microscopy performed as part of a user project at Oak Ridge National Laboratory’s Center for Nanophase Materials Sciences (CNMS), which is a U.S. DOE User Facility.
2 V Class Aqueous Sodium-Ion Batteries with Low Temperature Cycling Capabilities
Authors: Reber David , Kühnel Ruben-Simon , Battaglia Corsin
Published: February 2020

The inherent safety and potential cost-efficiency of rechargeable batteries based on aqueous electrolytes, led to their development as a large-scale energy storage option for grid applications enabling wide spread integration of renewables. In this field cost and safety are more important than energy density, which is why water based systems are a promising candidate. In recent reports, highly-concentrated electrolytes have been employed to extend the narrow electrochemical stability window of water (thermodynamically ~1.23 V) and stability windows beyond 3 V have been reported for lithium based systems [1]. Using 35 molal aqueous sodium bis(fluorosulfonyl)imide (NaFSI) solutions, we recently translated the concept to sodium-ion batteries and reported a stability window of 2.6 V on stainless steel current collectors [2]. However, all so called water-in-salt electrolytes reported to date suffer from crystallization at room temperature, which leads to premature cell failure.

We developed a ternary aqueous sodium-ion electrolyte based on NaFSI which is kinetically robust against crystallization and allows long term cycling at temperatures down to at least -10 °C. Addressing the raw materials supply chain as important challenge for scaling, we developed a 2 V class aqueous sodium-ion battery employing only abundant raw materials, namely NaTi2(PO4)3 [3] and Na3(VOPO4)2F [4] on the anode and cathode side, respectively. With 64 Wh kg-1, based on the active masses of both electrodes, this battery displays an energy density that is almost twice as high as that of previously reported aqueous sodium-ion batteries [5]. The cell displays excellent cycling stability at 30 °C with capacity retention of 85% after 100 cycles at C/5 and 77% after 500 cycles at 1C. At -10 °C, we obtain capacity retention of 74% after 500 cycles at C/5.

References:

Suo, L. et al. "Water-in-salt" electrolyte enables high-voltage aqueous lithium-ion chemistries. Science
350, 938 (2015).

Kühnel, R. S.; Reber, D.; Battaglia, C., A High-Voltage Aqueous Electrolyte for Sodium-Ion Batteries. ACS Energy Lett.
2, 2005 (2017).

Li, Z.; Young, D.; Xiang, K.; Carter, W. C.; Chiang, Y.-M., Towards High Power High Energy Aqueous Sodium-Ion Batteries: The NaTi2(PO4)3/Na44MnO2 System. Adv. Energy Mater.
3, 290 (2013).

Qi, Y.; Mu, L.; Zhao, J.; Hu, Y. S.; Liu, H.; Dai, S., Superior Na-Storage Performance of Low-Temperature-Synthesized Na3(VO(1-x)PO4)2F(1+2x) (0≤x≤1) Nanoparticles for Na-Ion Batteries. Chem. Int. Ed.
54, 9911 (2015).

Kumar, P. R.; Jung, Y. H.; Wang, J. E.; Kim, D. K., Na3V2O2(PO4)2F-MWCNT nanocomposites as a stable and high rate cathode for aqueous and non-aqueous sodium-ion batteries. Power Sources
324, 421 (2016).
Nitrogen-Doped Graphene-Based Catalyst with Metal-Reduced Organicframework: Chemical Analysis and Structure Control
Authors: Zhuang Shiqiang , Singh Harsimranjit , Lee Eon Soo
Published: February 2020

Here we report an advanced nitrogen-doped graphene-based catalyst with metal-reduced organic framework structure (N-G/MOF) prepared by functionalizing ZIF-8 and nitrogen-functionalized graphene oxide using the nanoscale high energy wet ball milling method. The chemical structure control of N-G/MOF was studied by characterizing the variation of the chemical structure of synthesized samples throughout targeted grinding speeds. The results proved that the chemical interaction between ZIF-8 and N-G caused the reduction of nitrogen, oxygen and zinc atoms, and the variation of chemical bonding composition in N-G/MOF. The reduction rate of zinc was gradually increased with the increasing grinding speed and reached 82% of zinc loss at 650 RPM. The characterization of carbon and nitrogen bonding composition confirmed that the reduction of nitrogen, oxygen and zinc atoms was caused by the decomposition of C-N-Zn heteroatom contents in ZIF-8 and the O-containing functional groups in N-G which were influenced by the grinding speed. The decomposition of ZIF-8 not only affected the framework and the pore structure but also modified the chemical structure and the surface distribution of C-N-containing functional groups-constituted active sites. The variation of physical and chemical properties enhanced the electrochemical performance of N-G/MOF and made it comparable to the 10 wt% Pt/C catalyst.
Merging Flow and Non-Flow Batteries: K4fe(CN)6 Electrolyte – Ni(OH)2 Solid Material As Proof of Concept
Authors: Paez Teresa , Palma Jesus , Ventosa Edgar
Published: February 2020

Ferrocyanide (FCY) based alkaline redox-flow batteries are considered promising alternatives to traditional redox-flow batteries that are based on high cost and strategic metals and corrosive acidic media. FCY has been used as active species in the positive side of a variety of redox-flow batteries, e.g. anthraquinone/FCY[1] and phenazines/FCY[2]. However, in all these cases, the energy density is limited by the low solubility of FCY in alkaline media (0.4 M equivalent to 10 AhL-1). In contrast, electroactive solid species that are frequently used in non-flow batteries are able to store more charge per unit volume than soluble electroactive species, e.g. Ni(OH)2 has a volumetric capacity of 1180 Ah·L-1 that is two orders of magnitude higher than that of a FCY solution. However, solid materials cannot be used in flow batteries as there is no electrical contact between the electrode and the solid located in the external tank.

In this talk, we will show that soluble electroactive species can be also used as molecular wiring to transport charges to high-energy solid materials confined in the external reservoir.[3] We demonstrate that by adding solid material in the reservoir, volumetric capacities of >25 AhL-1 are achieved (40% utilization rate of Ni(OH)2). We apply the concept in two types of FCY flow batteries: quinone/FCY and phenazines/FCY. For the latter, energy densities of >15 WhL-1 are demonstrated representing the highest value for an alkaline flow battery. This work open up the field for a new generation of batteries, which benefits from the advatages of flow and non-flow configurations.

References

Lin, K. et al. Alkaline quinone flow battery. Nat. Energy
349, 1–4 (2015).

Hollas, A. et al. A biomimetic high-capacity phenazine-based anolyte for aqueous organic redox flow batteries. Nat. Energy
3, 508–514 (2018).

Ventosa, E.; Paez, T.; Palma, J, Redox flow battery for energy storage, European Patent Application,
EP18382971

Figure 1. a Scheme of a redox-flow battery based on the use of ferrocyanide-Ni(OH)2 in the positive container. b Reversible stored charge during the first 20 cycles of a 2,6-dihydroxi- anthraquinone // ferrocyanide flow battery in the absence (black circles) and in the presence (red circles) of solid Ni(OH)2 in the external positive container.

Figure 1
Ultrathin Carbon Shell Entrapped Metal Co/Coo for High-Performance Electrochemical Supercapacitor
Authors: Gao Zhida , Lu Yongxin , Sun Xuezhi , Song Yanyan
Published: February 2020

Nowdays, a series of transition-metal oxides (TMOs) such as MnO2, MoO3, Co3O4, CoO, and NiO have been widely studied as supercapacitive materials because of their low cost and high theoretical specific capacitance. As a low-oxidized cobalt compound, to date, CoO has been successfully applied as Li-ion battery anodes and showed satisfactory Li-ion storage capacities. The theoretical specific capacitance of CoO reaches 4292 F g-1. This value is higher than that of NiO (2573 F g-1), MnO2 (1370 F g-1), and Co3O4 (3560 F g-1). However, the practical application of CoO is severely hindered by its easily oxidized character (CoO is oxidized to Co3O4 after exposure in air) and the poor electrical conductivity (intrinsic semiconducting or insulating property). The poor conductivity is also one of the main reasons that limit the application of other TMOs in constructing high performance supercapacitors. To overcome these challgenges, we report a metallic Co doped CoO-based energy storage material by elaborately tailoring both the electrical conductivity and material configuration. The cobalt-doped CoO (denoted as CoO/Co) heterostructure is designed to improve the electrical conductivity. The metallic Co, acting as a current “expressway,” effectively improves the electrical conductivity of the composite, thus accelerating the electron transport. Additonally, an ultrathin layer of amorphous carbon is generated on the surface of heterostructure to prevent further oxidation of CoO/Co. This amorphous carbon shell serves as a surface stabilizer to hinder further oxidation of Co/CoO, thus sustaining good stability of supercapacitor. As a result, the as-prepared composite exhibits an excellent supercapacitor performance of 2165.7 F g-1 at a scanning rate of 10 mV s-1. An asymmetric supercapacitor cell fabricated using the c and active carbon achieves a maximum energy density of 146.3 Wh kg-1 at a power density of 1800 W kg-1, and the maximum of 27000 W kg-1 can be obtained with a remaining energy density of 63.0 Wh kg−1. Even more importantly, such a composite also showed a good cycling ability and improved long-term storage stability. As this supercapacitive material can be prepared with a high yield by a facial low-cost route, it is highly expected that it could be a promising material for electrochemical energy storage in practical applications.
Modelling and Optimization of Electrodes Utilization in Symmetric Electrochemical Capacitors for High Energy and Power
Authors: Ike Innocent Sunday , Sigalas Iakovos Jack , Iyuke Sunny E
Published: February 2020

Expressions and guidelines for determination of electrode's effective thickness, optimum charging current density and electrode utilization in device of certain electrode's and electrolyte's effective conductivity were developed, and systematically used to study the performance of electrochemical capacitors (ECs). Effective thickness of electrode increases along with increase in effective conductivity of electrolyte and decreases as charging current density is increase. It was seen that every current density applied to device of specific electrode's and electrolyte's effective conductivity has corresponding effective thickness of electrode, and when charged at current density higher than its maximum current density, materials (electrodes) utilization were less than 100%. Also, when device with electrode's thickness higher than the effective thickness was charged at its maximum current density, materials (electrodes) utilization reduced below 100%. Materials utilization decreases along with increase in charging current density and electrode thickness, but increases as effective conductivity of electrode and electrolyte were increase. Therefore, optimum/effective thickness of electrode and optimum current density must be employed in charging device of given electrode's and electrolyte's effective conductivity for maximum materials utilization and performance (with minimum or no potential drop). Optimum current density beyond which energy density decays increases along with increase in electrode's and electrolyte's effective conductivity and decrease in electrode thickness. Use of optimum current density and effective electrode's thickness to maximize energy and power densities is inevitable, because increase in current density results in increase in power density and decrease in energy density.

Key words: Electrode thickness; Current density; Effective conductivity; Modelling and simulation; Electrode utilization; and Potential drop.
(Invited) Redox Contributions to the Behaviour of Electrochemical Capacitors
Authors: Donne Scott W
Published: February 2020

The use of electrochemical capacitors is expanding rapidly in the electronics industry due to their excellent performance characteristics, including high specific power and cyclability. However, their specific energy, and hence cost per unit energy, is somewhat limited, thus prompting significant global research to address this shortcoming.

Energy storage in these systems is a combination of electrical double layer formation, or charge separation at the electrode-electrolyte interface, and pseudo-capacitance, which is based on facile redox reversible reactions at this interface. One of the key characteristics of these systems is the relative contributions that these processes make to overall charge storage.

Much ado has been made about the contributions that redox processes made to pseudo-capacitive electrode performance. Many apparently similar materials such as RuO2, MnO2 and NiOOH contribute charge through redox processes at the electrode surface; however, their performance can be quite different depending on the electrode material itself and the conditions under which it is cycled. The typical response for an electrochemical capacitor electrode is a box-like voltammogram; however, materials such as these have a basis of such behaviour, but may also include distinct redox peaks within the voltammogram.

Here we will examine the role that the redox mechanism for these pseudo-capacitive materials has on electrode performance, as well as investigate its impact on electrode properties, in particular crystal size. Outcomes will allow further differentiation of materials used in electrochemical capacitors.
Electrochemical Analysis of Garnet-Type Solid Electrolytes – Effect of Dopants on Li-Conductivity and Dendrites Formation
Authors: Pesci Federico M , Brugge Rowena H , Cavallaro Andrea , Aguadero Ainara
Published: February 2020

The development of solid state lithium-metal batteries (SSLB) is a key requirement to enable the use of energy storage systems with high energy and power densities in the automotive sector. Garnet-type solid electrolytes are considered suitable electrolytes candidates for SSLB due to their stability against lithium metal and high ionic conductivity at room temperature (10-3 S cm-1). Currently their use is limited because of their short life-time due to high interfacial resistance between electrode and electrolyte, and to the formation of lithium dendrites.1 A better understanding of the transport properties and the mechanism of dendrites formation in garnet type electrolytes is therefore required in order to develop solid electrolytes with a long enough life-time to be employed in commercial systems.

In this work, alongside to an extended and systematic electrochemical characterisation of garnet-type electrolytes by Electrochemical Impedance Spectroscopy (EIS),2 we employed cubic Al- and Ga- doped Li7La3Zr2O12 (LLZO) as solid electrolytes in symmetrical cells and we investigated the formation of dendrites as a result of electrochemical cycling. We suggest that the presence of local chemical inhomogeneities promoted by the type of dopants used to stabilise the cubic phase might greatly affect the critical current density (CCD) for the dendrites formation and propagation.3 This is of fundamental importance for the development of solid state batteries based on LLZO.

1 A. Sharafi et al., J. Power Sources,
2016, 302, 135–139

2 F. M. Pesci et al., Manuscript in preparation

3 F. M. Pesci et al.
, J Mater. Chem. A,
2018
, 6, 19817-19827
Development of Organic Ionic Plastic Crystals As Solid-State Electrolytes
Authors: Pringle Jennifer M , Yunis Ruhamah , Al-Masri Danah , Forsyth Maria , Hollenkamp Anthony F.
Published: February 2020

The advantages of ionic liquids as electrolytes for electrochemical applications such as lithium batteries and dye-sensitized solar cells are now well recognized. Organic Ionic Plastic Crystals (OIPCs) are crystalline phases found in many of the same organic salt families as ILs but these materials have elevated melting points and exhibit various forms of disorder, which is the origin of their plastic mechanical properties. These plastic crystal materials are showing increasing promise as solid state electrolytes for various electrochemical applications.[1] We have also recently discovered that this disorder allows the use of OIPC-based membranes for light gas separation.[2]

OIPCs display one or more solid-solid phase transition before melting, which is associated with the onset of rotational or translational motions of the ions and thus a progressive transformation from an ordered crystalline phase to an increasingly disordered structure. This disorder is fundamentally responsible for the fast ion conduction of target ions, such as lithium or sodium, and core to their efficient performance as solid-state electrolytes.

Key to the development of OIPCs is expanding the range of cations and anions available, and understanding the resulting structure and dynamics. Here we discuss our development of new OIPC-based materials for energy applications, in particular lithium metal batteries, and insights into the mechanism of ion transport using techniques such as variable temperature solid state NMR. The recent development of new OIPCs using the N,N-diethylpyrrolidinium ([C2epyr]) cation will be discussed, in addition to the use of very high lithium content [C2epyr][FSI] / Li[FSI] ionic liquids and OIPCs as battery electrolytes.

References

[1] MacFarlane DR. Forsyth M, Howlett PC, Kar M, Passerini S, Pringle JM, Ohno H, Watanabe M, Yan F, Zheng W, Zhang S, Zhang J Nat. Rev. Mat., 2016, 15005.

[2] McDonald JL, MacFarlane DR, Forsyth M, Pringle JP, Chem. Commun., 2016, 52, 12940-12943

[3] Al-Masri D, Yunis R, Hollenkamp A, Pringle JM, Chem. Commun., 2018, 54, 3660-3663.
Nanocomposite Gel Polymer Electrolytes: Thermophysical, Electrical Properties and Electrochemical Applications
Authors: Deb Debalina , Bose Pallab , Bhattacharya Subhratanu
Published: February 2020

Flexible polymer-based electrolytes providing good electrode-electrolyte interfaces offer the most promising solution to address the all-solid-state battery requirements.1 However, substantially higher temperatures are required to achieve the optimal conductivity for a polymer electrolyte for electrochemical application, which is still an important bottleneck in lithium polymer batteries. To improve the performance of polymer electrolytes, ionic liquids (ILs) have been combined as a reinforcing agent with suitable polymer matrices. ILs add numerous advantages to the electrolyte such as high thermal stabilities, higher operating temperature range, moderate ion conductivity and safety. Moreover, due to non-reactivity with lithium, IL-based polymer electrolytes may also be used in secondary lithium-metal batteries, outperforming the conventional IL-free polymer electrolytes.

In this study, in order to improve the functionality and ion conductivity of polymer electrolyte further, a highly conducting ionic liquid-based nanofluid is used as the plasticizer. The ionanofluid is prepared and optimized by dispersing 5.0wt% of surface functionalized Al2O3 nanoparticles in 1-Decyl-3-methylimidazole bis(triﬂuoromethanesulfonyl) imide, [Deim][NTf2] IL to achieve the highest conductivity. In order to analyze the thermophysical and electrical properties, the as-prepared lithium bis(trifluoromethanesulfonyl) imide (LiTFSI) salt doped poly (ethylene oxide) based ionanofluid reinforced nanocomposite gel polymer electrolytes are subjected to different characterization techniques viz. XRD, DSC, FT-IR, SEM, HR-TEM and impedance spectroscopy. The highest conductivity for free-standing electrolyte with 30 wt% ionanofluid is obtained as ~2.5×10-3 S/ cm at 30 °C. The electrochemical properties of the optimized highest conducting electrolyte demonstrate its brilliant application potentiality as an electrolyte in secondary energy storage devices.