bluuebunny/crossref_metadata_2025 huggingface dataset:
Electrochemical Properties of CO2 Laser Radiated Carbon-Based Electrodes for Supercapacitors
Authors: Yu Hye-Ryeon , Choi Yu-Song , Cheong Hae-Won
Published: February 2020

Supercapacitor have been widely researched in order to apply many fields such as a hybrid electric vehicles, high pulse power sources, and emergency power sources requiring high power instantly. However, supercapacitor has low energy density compared to batteries. In order to increase the energy density of supercapacitor, electrode is the very important. Until now, porous carbons, which have low energy density (5~10 Wh kg-1) are the widely used for electrode materials. Recently, many reports have been released using a surface treated carbon or graphene, RGO and CDC, etc. However, these ways have much time and costs in order to compensate the energy. In this study, the CO2 laser treated carbon electrode is investigated for high-performance supercapacitors. First of all, in order to investigate the effect of CO2 laser radiation on energy density and microstructure, carbon electrode was fabricated as a mixture of active material, conductive material, and PVDF binder. The mixed slurry with NMP was coated onto an aluminum plate and dried at 100 oC for 12h. And then CO2 laser was radiated onto the surface of the carbon electrode. A 2032coin cell was assembled with the TEABF4 as electrolyte and separator. The microstructure difference was investigated with SEM and cyclic voltammetry tests also were carried out in the potential range of 0 to 2.7 V for comparison to CO2 laser radiated and un-radiated carbon electrode.
Three-Dimensional Graphene Sponge with Hierarchically Porous Structure for Electrochemical Supercapacitors
Authors: Shan Changsheng , Wang Hsing-Lin
Published: February 2020

Supercapacitors is an electrochemical energy storage device typically used as sustainable power supply (such as electric vehicles and mobile electronic devices) due to their higher power density than batteries, higher energy density than conventional dielectric capacitors, and long life cycles. [1,2] Graphene, a two-dimensional (2D) one-atom-thick single layer of sp2-bonded carbon, is considered as an ideal electrode material in supercapacitors because of its superior electrical conductivity and exceptionally large specific surface area. Graphene sheets, unless well separated from each other, tend to form irreversible agglomerates through strong π-π stacking and van der Waals interaction.[3] Meanwhile, the electrochemical binders and additives are normally required to make graphene-based electrodes, which would have an adverse effect on the specific capacitance of the resulting electrodes. To tackle these challenges, three dimensional (3D) graphene networks with highly electrical conductivity and large specific surface area, short diffusion pathways for electrolyte ions and fast transport channels for electrons are very promising supercapacitor materials. To these aims, we have developed ways to synthesize a novel macroporous/nanoporous graphene sponge with tunable pore sizes. This 3D porous graphene sponge has i) an interconnected electrolyte-filled macroporous network that enables increase of contact surface between 3D network and electrolytic solution, and rapid ion transport, ii) short ion and electron transport lengths due to nanoporous structures, iii) a large electrode specific surface area and (iv) high electron conductivity in the electrode assembly. The structure characterization and capacitive properties of the 3D macroporous/nanoporous graphene sponge was investigated and discussed, indicating 3D porous graphene sponge as an ideal electrode materials for supercapacitors.

Keywords：Graphene, 3D porous materials, supercapacitors, electrochemical energy

 References:

 Li, C.; Zhang, X., Wang, K; Zhang, H. T.; Sun X. Z.; Ma Y. W.; New Carbon Materials, 2015, 30(3): 193–206.

 Winter, M.; Brodd. R. J.; Chem Rev, 2004, 104(10): 4245-4269.

Li, D.; Muller, M. B.; Gilje, S.; Kaner, R. B.; Wallace, G. G. Nat. Nanotechnol. 2008, 3, 101–105.
Investigating the Electrochemical Behaviour of Different Carbons in Non-Aqueous Solvents Using Step Potential Electrochemical Spectroscopy
Authors: Donne Scott W , Dupont Madeleine F , Roland Aude
Published: February 2020

Supercapacitors are high-capacity electrochemical capacitors that bridge the gap between electrolytic capacitors and rechargeable batteries. They are a promising energy storage technology for addressing many of the problems associated with the transition to renewable energy technologies from fossil fuel based energy. Supercapacitors use electrostatic double-layer capacitance or electrochemical pseudocapacitance but in reality it’s often a combination of both. The common electrochemical methods used to characterize supercapacitor electrode materials are not able to separate the contribution from these different phenomena. However, using the step potential electrochemical spectroscopy (SPECS) method we will be able to develop a model of specific capacitance behaviour in link with the porosity and the morphology of the active material used for the synthesis of the electrode.

The SPECS experiment involves applying a small (±25 mV) potential step to the working electrode followed by a long equilibration time (300 s). This process is repeated over and entire charge-discharge cycle. By scanning at such a slow rate, the electrode has time to equilibrate at each potential, and the maximum charge storage capabilities of the electrode can be accessed. Each of the different charge storage processes occurring at the electrode has a unique time- dependent current response, and hence each potential step profile can be fitted to a model describing each of these processes. From this, values for series resistance (RS), double layer capacitance (CDL), diffusion limited capacitance (CD) and residual capacitance (CR) can be extracted. When the potential is stepped over an entire capacitor cycling range, contributions from each process can be determined at each point in the cycle.

In this work, nine different kinds of carbon structures were studied with the SPEC method and the results had shown how it was possible to link the carbon structure and the morphology with the storage behaviour. The morphology of these materials were very different and consequently the specific area and the diffusion of the electrolyte inside were impacted.

The effects of different non-aqueous electrolytes were also studied under the same conditions to understand how the performances are affected by the ion size variation in order to have a better idea of the storage mechanism at the interface.
High Energy-Density Hybrid Supercapacitors: Combining High-Voltage Window Ionic Liquids with MnO2-Nanomaterials
Authors: Lindberg Simon , Nitze Florian , Matic Aleksandar
Published: February 2020

Hybrid supercapacitors, utilizing faradaic as well as electrochemical reactions for energy storage, have attracted considerable attention during the last years as the need for fast charging and reliable energy storage is ever increasing in today’s society. However, issues still remain that prevents utilizing the full potential of hybrid supercapacitors. The highest hurdle is that the energy density (gravimetric and volumetric) of hybrid supercapacitors is still too low compared to batteries[1]. Additionally, hybrid supercapacitors suffer from poor cycle lifetime, compared to traditional supercapacitors.

A promising approach to increase the energy density of hybrid supercapacitors is the use of electrolytes, which are stable in a larger potential window compared to aqueous electrolytes. This enables higher total operating voltages, which is especially important, since the energy density has a quadratic dependency on the voltage.

However, so far hybrid supercapacitors, using MnO2 or RuO2 as electrochemically active component, have mostly been designed using aqueous electrolytes[1], thereby missing the possibility to benefit from the higher operating voltage of non-aqueous electrolytes. In our work, we aim at increasing both the operating voltage and the capacitance of hybrid supercapacitors, which together would enable higher energy density.

We investigate how different solvents, mainly based on ionic liquids interact with carbon based electrodes containing MnO2 nanoparticles[2] as electrochemically active species. We reveal how different proton characteristics (protic and aprotic) of the ionic liquids influence the performance. For instance, we compare the performance of the protic ionic liquid 1-ethylimidazolium bis(trifluoromethanesulfonyl) (EI-TFSI) and the aprotic 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl) (EMI-TFSI). To further investigate the role of protons and to increase their availability, we add different additives, such as water to the ionic liquid electrolytes. We discuss the fundamental mechanisms, i.e. the role of protons, the role of additional cations, and the influence of the voltage window on the performance of the system (capacitance, energy density, and stability).

Our study provides insight that can help to achieve a better understanding of the requirements on the electrolyte for hybrid supercapacitors. It shows that the MnO2 nanomaterial requires protons to work efficiently. Using protic electrolytes, such as water and EI-TFSI, a contribution from MnO2 can be observed, whereas there is no additional electrochemical contribution in the aprotic electrolyte. However, by adding water, and thereby available protons, to the aprotic ionic liquid we are able to increase the proton concentration and activity of the MnO2 material.

[1]Chem. Soc. Rev., 2015, 44, 7484—7539

[2]J. Phys. Chem. C 2011, 115, 5413–5421
Preparation of Sioc Li-Ion Capacitor By TEOS Based Sol-Gel Method with Different Silicones Precursors
Authors: Li Bochen , Funahashi Chikara , Saito Takeyasu , Okamoto Naoki , Ide Isamu , Onishi Yoshikazu , Nishikawa Masanobu
Published: February 2020

Since the development of Li ion battery, carbonous materials e.g. graphite had been widely used in commercial lithium-ion batteries. However, the practical capacity of graphite reached an almost theoretical limit. Therefore, promising anode materials, such as Sn, Si etc. have been considered to replace the graphite though they are not stable during charge-discharge cycles. It was recently reported that amorphous SiOC anode performs high capacity and superior cycling durability. SiOC material has high chemical stability and mechanical strength. In this study, we used a TEOS based sol-gel method with different silicones precursorsto synthesize SiOC directly on the Cu foil as a simple and cheap way.

　The silicones used in this study were PDMS(dimethylpolysiloxane), silanol- terminated PDMS, Cyclotetrasiloxane, polyether-modified silicone, alkyl-modified silicone and phenol-modified silicone. They were mixed respectively with TEOS (Tetraethyl orthosilicate), which was considered to perform a sol-gel reaction, and water in ethanol. The mole ratio of the TEOS/ silicone / H2O was 1:1:4, and the volume ratio of the mixture and ethanol was 1:1. 10 μl of HCl(37wt%) was added as catalyst before stirring. The sol solution was spin-coated onto the Cu foil. We evaluated these kinds of anode by battery charge-discharge test. Pore distribution and composition was measured by small angle X-ray scattering (SAXS) and X-ray photoelectron spectrometry, respectively.

　Amorphous SiOC thin films with all precursors showed a high cycling durability. The SiOC film from PDMS sol solution which was heated to 50ºC for 30 minutes during stirring achieved a best specific discharge capacity of about 1050 mAh/g even after 100 cycles, others are distributed from 150-400mAh/g. The SAXS of this sample shows a stronger peak of micropores(pore size <6 nm)than other samples. As a contest, we repeated the experiment without TEOS, and it became pyrolysis of silicones. The anodes made during the contest experiment showed low cycling durability but higher average specific capacity.
Optical Properties of Transferred Graphene Nanostructures
Authors: Rotkin Slava V.
Published: February 2020

This talk reports on recent progress in optical characterization of transferred graphene samples. After moving graphene, typically grown by CVD on Cu substrates, onto different substrates, not only its mechanical properties and continuity can be altered. Strain and unintentional doping could emerge that are resolvable by means of hyperspectral microscopy and statistical post-processing of the hyperspectral data. More standard optical techniques, such as transmission or reflection, can be also applied to investigate such samples. Simple optical models were developed to quantitatively interpret the optical data. Coupling of graphene surface modes to the polaritons of the substrate is another phenomenon deserving attention. Hybridization of the 2D modes by graphene and polaritons produces a tangled response, qualitatively different in different frequency ranges of the probe.
Towards the Manipulation of Defects and Dopants to Functionalise Graphene - a DFT Based Study and Development of New Theoretical Methods
Authors: Hildebrand Mariana , Sainsbury Toby , Rungger Ivan , Harrison Nicholas
Published: February 2020

Graphene is a material, which is exhibiting a rising research interest over the last few years due to its unique properties and various possible applications. Possible applications range from optical sensing and drug delivery up to fuel and solar cells as well as composite materials. Based on experimental findings, first principle theory of electronic structure calculations (DFT) shall be used to examine the effects of p/n-doping and defects on the material’s properties as to find a way of band gap tuning and to understand the underlying mechanisms of it. Not only graphene shall be examined in this context but also hexagonal Boron-Nitride Nanosheets (h-BNNs). Especially a radical functionalisation of h-BNNs with oxygen, nitrene and carbene is of interest. Based on DFT, IR spectra, Raman spectra and structural properties shall be computed and compared with experimental results. Density of States and Band structures shall be calculated as to understand the electronic properties of the examined materials. These results shall build the basis for working on further questions and to develop methods beyond DFT as to find a better description of the systems of interest. Further questions of interest are for example how the radicals adsorb on the h-BNNs, how magnetic impurities or the adsorption of magnetic materials change the properties of graphene or h-BNNs and how environmental effects influence the adsorption of different molecules on graphene. Methods describing dynamical correlations (e.g. Dynamic Mean Field Theory) are of interest in the context of working with strongly correlated materials. Furthermore, coarse grained methods offer a better description of dispersion forces and can be used to receive a better description of environmental effects. In this context, the development of double hybrid functionals may be of interest as well since they also tend to give a better description of dispersion forces. Another point of interest is the examination of charge transport properties with graphene-based electrodes, for example with methods based on the Landauer-formalism.
Study of the Active Centers and Reaction Mechanism of Fe/IRMOF-3 Derived Porous Carbons As Fe-N-C Electrocatalysts in Oxygen Reduction Reaction
Authors: Sun Hui , Su Haixia , Ma Xingyu , Zhang Xin
Published: February 2020

By doping iron into isoreticular metal organic framework-3 (IRMOF-3) as a precursor and then annealing at 900 ºC under inert gas atmosphere, we have successfully prepared high efficient electrocatalyst of x%Fe/IRMOF-3-900 (x ranges from 1% to 10%) with porous carbon sphere structure. The electrocatalytic properties of the x%Fe/IRMOF-3-900 towards oxygen reduction reaction (ORR) are investigated by using rotating ring disk electrode (RRDE). The results demonstrate that the 1%Fe/IRMOF-3-900 exhibits the highest ORR activity: the onset and half-wave potentials are measured at 1.02 V and 0.88 V vs. RHE, respectively, together with electron transfer number of 3.90 at 0.4 V, kinetic current density of 4.5 mA cm−2 at 0.88 V, and excellent longtime stability in alkaline solution. Such high ORR activity is superior to many MOFs derived noble metal free electrocatalysts reported so far, and attributed to that the 1%Fe doped could retain the well-defined cubic morphology of the IRMOF-3, resulting in high surface area and large total pore volume, high nitrogen content and high density of electrocatalytic active N-species. The ORR active centers of the Fe-N-C catalysts and reaction mechanism also have been studied by DFT calculation and simulation. This study provides a new strategy for preparation of non-precious metal ORR catalysts using the MOF as a precursor.

Figure 1
The Role of Superficial Graphene in Electroforming Process
Authors: Ryo Hokyun , Bae Sukang , Kim Tae-Wook , Ha Jun-Seok , Lee Sang Hyun
Published: February 2020

Electroforming is a specialized process in electrochemical fabrication of metal parts. Electroplating is typically concerned with coating a metallic layer to provide some functionality and/or protect the surface of article. On the other hands, the electroforming purposes on the metallic structures which are created on a cathode mandrel or template by electroplating process.[1] Precision manufacturing including three-dimensional structures and microstructures is possible by a high degree of control in electroforming. One of the most important steps in the electroforming process is the separation of a fabricated deposit from the template without deformation or damage, which strongly depends on the interfacial properties between the deposit and template.

Graphene composed of a layer of sp2-bonded carbon atoms has a high electrical conductivity and a low surface energy due to a lack of dangling bonds on the surface.[2] In this study, we demonstrated that graphene layer is a good superficial layer for electroforming process. Mono-layered or multi-layered graphene were synthesized on Cu or Ni foils using chemical vapor deposition (CVD). The graphene was fully covered the surface of metal foils which used templates for electroforming. During electrochemical deposition, the graphene completely prevented strong bonding between the metal ions in electrolyte and metal atoms on the foils. The adhesion between an electroplated metal and graphene is much less than that between graphene and the metal foil that was used for CVD. The difference in adhesive force enables effective delamination of the deposited metal. The surface morphology of the deposited metal layer was similar to the graphene/metal foil template. In addition, we also confirmed that the technique could be utilized to fabricate various microstructures as well as flexible electronics.

[1] J. A. MacGeough, M. C. Leu, K. P. Rajurkar, A. K. M. De Silva and Q. Liu, CIRP Ann.-Manuf. Technol., 2001, 50, 499–514.

[2] J. Rafiee, X. Mi, H. Gullapalli, A. V. Thomas, F. Yavari, Y. F. Shi, P. M. Ajayan and N. A. Koratkar, Nat. Mater., 2012, 11, 217–222.
Corrosion Behavior of Sn-1Ag-0.5Cu Solder Alloy with the Addition of Fe and Bi
Authors: Subri Nor Wahida , Ali Bakhtiar , Subri Mohd Faizul Mohd , Sukiman Nazatul Liana
Published: February 2020

The needs for lead free solders have risen over concerns about the toxicity of Pb particularly to the public health and the environment. In line with current technological developments, the use of electronics has expanded to various applications such as industrial and automotive applications. This demands a higher reliability and durability of the device in more challenging operating environments that includes corrosive medium and moisture. In this work, we prepared Sn-1Ag-0.5Cu (SAC105) lead-free solder alloys with the addition of iron (Fe) and bismuth (Bi) and extensively investigated their corrosion behavior and microstructures. To characterize the corrosion behavior, combinations of physical (weight loss) and electrochemical tests (potentiodynamic polarization and impedance spectroscopy) were carried out in 0.1M NaCl solution, for various periods of time. In order to mechanistically understand the corrosion behavior of the solder alloys, an understanding of the microstructure is important as the alloying elements dictate the type of microstructure that is present within an alloy. The microstructural characterization and damage accumulation were executed by means of field emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM). The correlation between electrochemical measurements and microstructural characterizations were made to clarify and quantify the overall performance of the SAC105 with addition of Fe and Bi.
Corrosion Resistance of Laser Powder Bed Fusion Built Fe-Cr-Mn-Si-W-Mo-B-C Alloy
Authors: Oh JI-Won , Na Hyunwoong , Choi Hanshin
Published: February 2020

Metal additive manufacturing technology of layer-wise stacking of 2 dimensional patterns is emerging in engineering components manufacturing. Nevertheless, limited materials selectivity is a critical hurdle for industrial adoption. Hard engineering components are good market penetration point because product design is limited by machining cost. Near net shaped product with complex design will be advantageous though net shape products cannot be manufactured by current state AM technology. In this context, applicability of a Fe base powder with multiple components for laser powder bed fusion AM was assessed. Powder layer was pre-placed on STS build platform and layer thickness was set to be 25 um. 2 dimensional patterns were overlaid according to continuous irradiation mode with outer contour formation. Laser input parameters were selected from pre-screening step with 5x5x3 mm3 model. After that, 10x10x10 mm3 samples were prepared with laser powder and laser scan rate changing. According to laser parameters, phase compositions and microstructures were reported. Optimum process window for the powder feedstock is reported. With respects to formation of defects such as distortion, interlayer debonding, cracking, and pores, solidification crack, non-uniformity of powder layer, and primitive bead characteristics were considered. In addition, effects of phase composition on corrosion behavior were investigated by anodic polarization.
Influences of Inert Particles on Corrosion Behavior of Carbon Steel Under Sodium Chloride Droplet
Authors: Wang Yanhua , Zhong Lian
Published: February 2020

In ambient atmosphere, the surface of structural materials are usually covered by a layer of solid matter, containing soluble species and inert particles. The soluble species are highly hygroscopic and corrosive to steel, the inert particles can also affect corrosion by changing the mass transfer process. In this paper, the influence of inert particles on the droplet corrosion of carbon steel was studied by using the array electrode technique, potentiodynamic polarization technique and the electrochemical impedance spectroscopy. The current map exhibited the typical Evans distributions, with the anodes at the centre and the cathodes at the peripheral, which was not affected by the deposition of the inert particles. However, the spreadability of droplets increased with the increase of the amount of inert particles, which resulted in the expansion of corrosion activity area. In addition, the impedance spectra showed two capacitive loops with the deposition of inert particles, and the capacitive loop in the high frequencies was attributed to the blocking effect of the inert particles. The corrosion behavior of carbon steel was affected by these two aspects, the spreadability of droplets and the blocking effect of the inert particles. With the increase of the amount of particles, the average current value decreased firstly and then increased. There was a critical value in the deposition amount of the inert particles. When the amount was lower than the critical value, it could hinder corrosion. While, when the amount was higher than the critical value, it would accelerate corrosion owing to the expansion of droplets. The underlying mechanism was analyzed and a model was proposed.

Figure 1
The Contribution of Hydrogen to the Loss of Mechanical Properties of a 7046 Aluminium Alloy Pre-Exposed in a Chloride Media
Authors: Oger Loïc , Blanc Christine , Peguet Lionel , Odemer Gregory , Andrieu Eric
Published: February 2020

Automotive industry is increasingly affected by standards requiring a major cut of polluting emissions. Rolled sheets of Cu-free 7000-series alloys offer a very attractive compromise between mechanical properties, corrosion resistance, forming and weight. With the continuing need for further down-gauging and light-weighting in transportation sector, as well as other applications, these alloys are being considered for large volume use. Nevertheless, their susceptibility to hydrogen embrittlement (HE) and to stress corrosion cracking (SCC) is a limiting factor. The present work concerns HE susceptibility of a 7046-T4 aluminium alloy exposed to a 0.6M NaCl solution. First results showed a strong decrease of the ultimate elongation for tensile samples after exposure to the chloride solution Surface observations revealed that the alloy was mildly affected by corrosion in this environment: pits initiated rapidly around intermetallic particles but only few pits propagated after several days of exposure. Cross-section of pre-corroded samples showed no intergranular corrosion and the maximal depth for the corrosion defects was about 100 nm which was not enough to lead to a noticeable loss of mechanical properties. Therefore, it was assumed that the decrease of the mechanical properties was related to the penetration of hydrogen inside the materials and the results gave proofs that hydrogen could enter and embrittle the 7046 aluminium alloy even without an applied stress during its exposure to the corrosive solution. Global hydrogen content measurements by melting method confirmed this assertion. Furthermore, comparison of the fracture surface of a healthy specimen and that of a sample pre-exposed to the NaCl solution showed that the ductile fracture mode observed for a healthy specimen was partially replaced by cleavage and brittle intergranular rupture when the sample was pre-corroded. Both fracture modes could be attributed to different hydrogen contents and different trapping sites in the microstructure. The hydrogen localized in the grain boundaries was believed to lead to intergranular decohesion, while the reticular and trapped hydrogen presumably induced cleavage rupture by exacerbating the localization of the plasticity. In addition, tensile tests were performed on samples pre-hydrogenated in a pH 2 sulfuric acid solution with a cathodic potential applied. The aim was to precisely control the hydrogen amount introduced in the samples. The depth and the nature of the fracture mode were then analyzed and related to the hydrogen amount. In parallel, pre-hydrogenated coupons were analyzed by SIMS in order to measure the maximal depth affected by hydrogen and to localize the trapping sites in the microstructure. The coupling of these two methods allowed to conclude about the role of the hydrogen generated by corrosion and to propose a mechanism to explain the embrittlement.
Layer-By-Layer Assembly of Graphene Oxide/Polymer Coating Film to Improve Corrosion Resistance
Authors: Kim Young-Seok , Choi Woohyung , Lee Hyunjung , Oh Seungtaek
Published: February 2020

Corrosion is a phenomenon that occur rust on the surface of metal. This phenomenon occurs in the overall part of the industry, causing a variety of problems to weakening mechanical properties of the material. Corrosion is prevented to coating treatment. This treatment can prevent corrosion by blocking water or oxygen molecules. Researchers have done many studies to prevent corrosion. In order to improve corrosion protection properties, pigments, such as zinc powder, clay etc, have been incorporated into coating materials. Coatings that imbedded pigments have a excellent corrosion protection properties. Recently, nano-sized pigments have better protection properties than conventional micro-size pigments. In this study, we fabricate graphene oxide(GO)/polymer composite coating thin film by using Layer-by-Layer(LBL) method. GO is role of a pigment that limits molecules to induce corrosion by the diffusion pathway. We survey anti-corrosion properties such as Tafel-Plot and Electrochemical Impedance Spectroscopy(EIS) by using electrochemical measurement system.
Possibility of Composite Cathodes with Sacrificial Salts
Authors: Okada Shigeto , Tsunoe Daisuke , Kitajou Ayuko , Hori Hironobu , Dimov Nikolay , Barpanda Prabeer
Published: February 2020

Recently, Na3V2(PO4)2F3 [1] and alluaudite-type Na2Fe2(SO4)3 [2] have been reported as high voltage cathode materials for sodium-ion battery. Both of them, the rechargeable capacities are more than 100 mAh/g and the discharge voltages are almost 4 V against Na. So, the cathode performance of the Li counterparts against Li should be also interesting. Nevertheless, there is no report about the direct synthesis of Li3V2(PO4)2F3 and Li2Fe2(SO4)3. As for the alternatives, 3LiF-2VPO4 and Li2SO4-2FeSO4, which consist of the same compositions with Li3V2(PO4)2F3 and Li2Fe2(SO4)3
　were synthesized by ball-milling method at room temperature.

The 3LiF-2VPO4/C and Li2SO4-2FeSO4/C were prepared by three-step mechanical ball-milling. First, the mixture of LiF (Wako) and VPO4 with the molar ratio of LiF:VPO4 = 3:2 was placed in the teflon-lined stainless container with T3-ZrO2 balls. As for Li2SO4-2FeSO4/C, the molar ratio of Li2SO4 and FeSO4 was 1:2. These mixtures were ball-milled using a planetary mill (Fritsch, Pulverisette7) with a rotation speed of 600 rpm for 6 h. Second, the obtained mixtures were ball-milled with 5 wt% acetylene black (AB, Denki Kagaku) with a rotation speed of 600 rpm for 3 h and then the resulting mixtures were ball-milled again with 20 wt% AB. All the procedures were carried out under argon atmosphere. The title compounds prepared by mechanical ball-milling were characterized by powder X-ray diffractometer (Cu-Kα, 50kV, 300mA) and Field emission electron microscope (FE-TEM, JEM-2100F). Electrode pellets were manually prepared by mixing 3LiF-2VPO4/C and Li2SO4-2FeSO4/C with 5% polytetrafluoroethylene (PTFE) and punched together with Teflon binder (Polyflon PTFE F-104, Daikin Industry) into disks (ca. 20 mg in weight and 10 mm in diameter). The electrochemical performance of the obtained composite cathodes were evaluated versus Li metal (Honjo Metal Co., Ltd.) in 2032 coin-type cells using nonaqueous electrolyte (1M LiPF6/EC : DMC = 1 : 1 in volume, Tomiyama Pure Chemical Industries) and polypropylene separators (Celgard 3501).

These materials showed an excellent reversible capacity corresponding to 2 Li reaction. The energy density of the obtained 3LiF-2VPO4
and Li2SO4-2FeSO4/C were 680 Wh/kg and 420 Wh/kg, respectively. In addition, the feasibility of these composite cathodes with sacrificial salts were also confirmed by the Li-ion type cell with graphite anode.

The initial discharge and charge efficiencies were more than 80% as shown in Fig. 1 and 2. They suggest that the cell reactions in the Li ion-type cells were actually attributed to the insertion and extraction of Li ions come from sacrificial salts such as LiF and Li2SO4.

References

[1] K. Chihara, A. Kitajou, I.D. Gocheva, S. Okada, and J. Yamaki, J. Power Sources, 227(2013) 80.

[2] P. Barpanda, G. Oyama, S. Nishimura, S. C. Chung, and A. Yamada, Nature Commun., 5, (2014) 4358.

Figure 1
Li-S Batteries at a Crossroads
Authors: Nazar Linda F
Published: February 2020

This talk will provide an overview of Li-S batteries, including conventional liquid cells and the important advances that have been made in understanding the chemistry and improving upon it, and will address new opportunities in solid state sulfur cells.
On the Road Towards Ca-Based Batteries
Authors: Ponrouch Alexandre , Tchitchekova Deyana , Frontera Carles , Bardé Fanny , Palacin M Rosa
Published: February 2020

The development of a rechargeable battery technology using light electropositive metal anodes would bring in a breakthrough in energy density, especially if it involves multivalent charge carriers. While effective electrolytes have been developed for magnesium which has enabled to achieve proof-of-concept for magnesium batteries, the electrodeposition of calcium was thought to be impossible and research restricted to non rechargeable systems. Calcium is an especially attractive alternative as it is the fifth most abundant element on earth crust and its standard reduction potential is only 170 mV above that of lithium, enabling significantly larger cell potential than that achievable with magnesium or aluminium.

The talk will revisit these aspects discussing the feasibility of reversible calcium plating/stripping using conventional alkylcarbonate electrolytes which impacts the prospects of developing a new calcium based rechargeable battery technology.
Lithium-Ion Battery Technology for Low-Voltage Hybrids
Authors: Jeong Wonhee
Published: February 2020

Lithium-ion batteries are lightweight power sources with high recuperation capability, which could be a potent battery technology for emerging low-voltage hybrid markets. Based on lithium-ion battery technology, automotive manufacturers have investigated various 12V and 48V systems with different dimension and performance requirements. Depending on their needs for a pack location and system design, OEMs’ interest in cell chemistry varies from conventional carbonaceous anode-based battery to LTO anode-based one to LFP cathode-based one. In this talk, current lithium-ion battery solutions to various low-voltage needs will be discussed with a focus on technical challenges in cell design. Also, we will explore future lithium-ion battery technology required for 12V and 48V lithium-ion batteries.
Stabilizing High-Voltage Layered Oxide Cathode Materials for Li/Na Ion Batteries
Authors: Yang Yong
Published: February 2020

Li-ion battery systems have started to extend its roles from portable electronics, power tools to automobile applications such as hybrid and plug-in electric vehicles. However, it is necessary to enhance their electrochemical performance such as energy density and cycle life, for promoting their competition capability as vehicle power system. Obviously, electrode materials, especially positive electrode materials either working voltage or reversible capacity determine the energy density of the Li-ion batteries at mostly[1,2].

        In the presentation, some new research progress of stabilizing high-voltage layered oxide cathode materials for Li/Na ion batteries in this group will be reported.   Our strategies include two directions[3,4]: one is to improve the interface stability by using high voltage electrolyte additives or surface coating, another is to stabilize the lattice structure by using suitable element doping. 

       For example, when extending the working voltage of LiCoO2 from 4.2V to 4.4V or even more, we must develop some new electrolyte recipes to stabilize corresponding electrode/electrolyte interface at high voltage.  Our recent results[5] show that a synergistic effects of suberonitrile-LiBOB binary additives in high-voltage cathode system, i.e.  they could improve the cyclic performance of 4.5V LiCoO2 effectively. The corresponding working mechanism of the binary additives will be presented.

       As to develop high energy density Na-ion battery, it is important to develop high-voltage cathode material. It is found that [6,7]  the introduction of Zn2+ in the Na-Ni-Mn-O system can effectively overcome the drawback of voltage decay when charged to a higher cutoff voltage (>4.0 V), and significantly improve capacity retention compared to the unsubstituted material during cycling. In addition, a smoother charge/discharge profile can be observed between 3.0 and 4.0 V for Zn-substituted samples, demonstrating that Na+/vacancy ordering can be suppressed during sodium insertion/extraction. Na0.66Ni0.26Zn0.07Mn0.67O2 can deliver an initial capacity of 132 mAh g–1 at 12 mA g–1 with a high average voltage of 3.6 V and a capacity retention of 89% after 30 cycles. We have used a series of techniques such as in-situ XRD, in-situ XAS,  ex-situ solid state NMR and HRTEM techniques to investigate the structural changes during cycling process and working mechanism of Zn2+ in the corresponding Na0.66Ni0.26Zn0.07Mn0.67O2 cathode materials.
Direct Experimental Observation of the Interfacial Instability of the Fast Ionic Conductor Li10GeP2S12 at the Lithium Metal Anode
Authors: Wenzel Sebastian , Zeier Wolfgang G. , Janek Jürgen
Published: February 2020

High capacity and low potential anode materials like lithium metal are preferred for high energy densities in all solid-state batteries. Due to the highly reducing potential of lithium metal, the electrochemical and thermodynamic stability of a solid ion conductor at the interface plays a crucial role for the performance of all solid-state batteries.

When a solid electrolyte is in contact with lithium metal, three different types of interfaces may occur:1 (I) A stable interface may form with electrolytes that are thermodynamically stable against Li contact. (II) A reaction occurs and a mixed ionic-electronic conducting (MCI) new interphase forms,2 which rapidly growths due to the electronic percolation pathways. (III) A reaction occurs and a solid electrolyte interphase (SEI) forms,3 which only conducts ions. While (I) may be preferred and (II) is exclusively detrimental, due to a proceeding reaction front, the impact of (III) on the battery performance depends on the type of forming SEI.

Here we will shortly introduce the types of possible interphases/interfaces and discuss the expected effects on the overall resistance and performance of an all-solid-state battery. Using time-resolved impedance spectroscopy and time-resolved cyclic voltammetry we introduce a guideline to characterize solid electrolytes for their stability against metal interfaces. The solid electrolyte Li10GeP2S12 will be shown as an example of an instability,4 as has been theoretically predicted.5,6 SEI formation occurs, affecting the overall cell resistance detrimentally.

Using a novel in situ X-ray photoelectron technique we study the resulting interphase formation when Li10GeP2S12 is in contact with Li. Using the observed chemical species, in combination with time-resolved electrochemical measurements, we suggest a reaction mechanism for the interphase formation as well as provide an understanding of the growth kinetics.

1Wenzel S., Leichtweiss T., Krüger D., Sann J., Janek J. Solid State Ion.
2015, 278, 98-105

2Hartmann P., Leichtweiss T., Busche M., Schneider M., Reich M., Sann J., Adelhelm P., Janek J. J. Phys.
Chem. C
2013, 117, 21064-21074

3 Wenzel S., Weber D., Leichtweiss T., Busche M., Sann J., Janek J. Solid State Ion.
2016, 286, 24-33

4Wenzel S., Randau S., Leichtweiss T., Weber D., Sann J., Zeier W.G., Janek J. submitted

5Zhu Y., He X., Mo Y. ACS Appl. Mater. Int.
2015, 7, 23685-23693

6Zhu Y., He X., Mo Y. J. Mater. Chem A
2016 DOI: 10.1039/C5TA08574H.
Synthesis and Characterization of Tin Oxide By Atomic Layer Deposition for Solid-State Batteries
Authors: Novikov Pavel Alexandrovich , Maximov Maxim Yurievich , Popovich Anatoliy Anatolevich , Nazarov Denis Vasilievich , Silin Alexey Olegovich , Rumyantsev Alexander Mikhaylovich , Zhang Yongguang
Published: February 2020

The SnO2 material has been considered as a promising lithium-ion battery anode candidate, and recently, the importance has been increased due to its high performance in sodium-ion batteries. Tin oxide (SnO2) has been studied as a promising alternative to the commercially used graphite anode material because of its much higher theoretical specific capacity 1491 mAh/g [1, 2].

Synthesis of tin oxide (IV) thin films was carried out in Picosun R-150 ALD reactor. Synthesis temperature of the process varied from 2500C to 3500C. As a source of tin was used Russian-made tetraethyltin (TET - Sn(C2H5)4, CAS № 597-64-8), purity 99.999%. Inductively coupled remote oxygen plasma and ozone was used as oxygen sources.

Thickness of thin films was measured using spectroscopic ellipsometry UVISEL 2 UV-Vis-NIR, and corresponded 75-80 nm. Surface morphology were obtained by scanning electron microscope Mira Tescan. Valence state of tin was studied by X-ray photoelectron spectroscopy (XPS). Electrochemical study of obtained thin-film electrodes was also carried out. The voltage of cycling was ranged from 0.01 V to 0.8 V. Current density was 25 µA/cm2. During cycling tests was shown that tin oxide has a stable discharge capacity about 900 mAh/g during 500 charge/discharge cycles, with efficiency about 99,5 %, fig.1. Capacity fluctuations likely to be associated with changes in ambient temperature.

Financial support was made by Ministry of Education and Science of Russian Federation. Unique identifier of the project is RFMEFI57814X0096.

[1] Jiajun Chen Materials 6 (2013), 156-183

[2] S.-Y. Lee et al. Nano Energy 19 (2016), 234–245

Figure 1
Deciphering the Structure of the Magnesium Aluminum Chloride Electrolyte in Bulk and Near the Anode Electrode
Authors: Canepa Pieremanuele , Gautam Gopalakrishnan Sai , Malik Rahul , Ceder Gerbrand
Published: February 2020

Electrical energy storage is a key technology for a clean energy economy, but currently requires significant improvement in energy density beyond the capabilities of traditional Li-ion batteries. Mg-ion batteries are an exciting alternative in terms of the amount of energy that can be delivered, safety, manufacturing and disposal costs, with limited environmental impact. The electrochemical functions of the Mg-ion battery rely on the choice of the electrolyte, which is limited by the distinct chemistry of Mg. To date, very few electrolytes can reversibly plate and strip Mg [1,2]. The magnesium aluminum chloride complex (MACC) electrolyte can reversibly plate and strip Mg with significantly higher voltage (3.1 V) as compared to other electrolytes, but there is a pressing need to address critical questions about the structural evolution of this electrolyte during electrochemical cycling [3]. While it is well established that Mg can be deposited reversibly from complex ethereal solutions of Mg-Al chloride complex reagents, the stripping/deposition mechanism at the anode is still debated [2,3]. In this poster we present a detailed atomistic DFT study of the electrolyte in bulk and when in contact with Mg-anode surfaces. These models are essential to clarify the structure of the electrolyte under various environmental conditions as well as to provide insight on the electron-transfer mechanism occurring at the electrode/solvent interface [4,5].

[1] D. Aurbach, Z. Lu, A. Schechter, Y. Gofer, H. Gizbar, R. Turgeman, Y. Cohen, M. Moshkovich, and E. Levi, Nature
407, 724–727 (2002).

[2] N. Pour, Y. Gofer, D. T Major, and D. Aurbach, J. Am. Chem. Soc.
133, 6270–6278 (2011).

[3] R. E. Doe, R. Han, J. Hwang, A. J. Gmitter, I. Shterenberg, H. D. Yoo, N. Pour, and D. Aurbach, Chem. Commun.
50, 243–245 (2014).

[4] P. Canepa, G. S. Gautam, R. Malik, S. Jayraman, Z. Rong, K. R. Zavadil, K. Persson, G. Ceder, Chem. Mater.
27 (9), 3317–3325 (2015).

[5] P. Canepa, S. Jayaram, L. Cheng, N. N. Rajput, W. D. Richards, S. G. Gautam, L. A. Curtiss, K. A. Persson and G. Ceder, Energy Environ. Sci.

8, 3718–3730 (2015).
Integrated Design of Cathode and Separator for Lithium-Sulfur Battery
Authors: Pei Haijuan , Guo Rui , Li Yong , Liu Wen , Xie Jingying
Published: February 2020

Lithium–sulfur (Li–S) battery is considered to be one of the most promising candidates for high energy density applications especially in electric vehicles and hybrid electric vehicles, due to low cost, environment friendliness, availability of resource materials, large theoretical specific capacity and specific energy of 1672 mAh g-1 and 2600 Wh kg-1, respectively. However, the actual specific capacity and energy are both far less than the theoretical values, in common sense, which is due to the poor utilization of sulfur and polysulfides.

To improve the performance of the cell and reduce the mass of non-active material, an integrated cathode and separator has been developed for Li-S batteries. The elemental sulfur and various conductive carbons were casted onto the separator directly, instead of the routine Al current collector, which makes the batteries lighter and more flexible. As shown in Fig.1, the integrated cathode with sulfur in the middle of the carbons layer has a three-dimensional electric conduction structure. Fig.2 displays the cycle performance of the cells with the integrated structure and routine structure, evidencing that the Li-S cell with the integrated cathode structure shows better cycle performance.

Acknowledgements

This work is supported by Shanghai Science and Technology Committee Rising-Star Program (15QB1402000).

Figure 1
Transformation of Environmentally Threatening Prosopis Juliflora into Tubular Carbon As Excellent Electrodes for Li-Ion Capacitors
Authors: Palanichamy Sennu , Lee Gyung Hwan , Park Sung Ho , Lee Yun Sung
Published: February 2020

Sustainable renewable energy generation from sources that would otherwise be environmental pollutants and transportation of such energies for the desired applications would lead to significant global social and economic development. The commercially available energy storage devices such as supercapacitors and Li-ion batteries (LIB) energy and power densities are significantly lower than those necessary for applications in zero-emission transportation such as electric vehicles (EV, >150 Wh kg–1) & plug-in hybrid electric vehicles (P-HEV, 57 to 97 Wh kg–1).(1) The Li-ion hybrid electrochemical capacitor (Li-HEC) constructed with Li-ion insertion as anode and double-layer forming component as positive electrode, which provides the desired energy and power densities, respectively. (2, 3)

     Here, the environmentally threatening and invasive weed of Prosopis juliflora is converted as electrode materials. Prior to testing the P. juliflora AC as an electrode for charge storage, we have carried out a systematic study on the preparation of AC from P. juliflora
. Firstly, the influence of the pore forming agent, i.e., KOH, and its capacitive behavior has been evaluated in symmetric configuration. Subsequently, the energy density has been increased by introducing a homemade insertion type electrode Li4Ti5O12 with P. julifloraderived AC as the supercapacitor component in a Li-HEC assembly. In addition, extensive physico-chemical properties, including XRD, BET surface area, Raman analysis, XPS, and SEM studies, were conducted and are described in detail.

References:

1. E. J. Cairns and P. Albertus, Annual Review of Chemical and Biomolecular Engineering, 1, 299 (2010).

2.  V. Aravindan, J. Gnanaraj, Y.-S. Lee and S. Madhavi, Chemical Reviews, 114, 11619 (2014).

3. K. Naoi, S. Ishimoto, J.-i. Miyamoto and W. Naoi, Energy & Environmental Science, 5, 9363 (2012).

Figure 1. (a) SEM image of as prepared Prosopis juliflora carbon at 900 °C is naturally exist in tubular structure. (b) Plot of cyclic retention vs. cycle number and coulombic efficiency of KC21-900/LTO based Li-HEC at a current density of 1 A g–1. Here, the current density is based on the total mass loading of the electrode. Inset: typical charge-discharge curves for the first five cycles, (c) Ragone plot of KC21-900 based symmetric and Li-HEC configuration

Figure 1