bluuebunny/crossref_metadata_2025 huggingface dataset:
Novel Diagnostic Methods Via Instrumented Lithium Batteries
Authors: Bhagat Rohit , Fleming Joe , McTurk Euan , Seth Sampan , Dashwood Richard , Greenwood David , Ferrari Stefania
Published: February 2020

Defect propagation and material degradation affect both the performance and safety of energy storage systems. Both processes may accompany operation over time, be nucleated during manufacturing, or be initiated rapidly by external stimuli. This raises particular concerns in lithium-ion cell technologies, where the consequences of faults can be dramatic. However, to date, we have limited capability to detect and/or predict these critical lifetime- and reliability-determining events, especially during operation under real-world operating conditions.

In this paper we present our work related to embedding sensors within and around commercially available pouch and cylindrical format cells. The types of sensors include reference electrodes for measuring half cell voltages during operation, optical fibres to measure mechanically and thermally induced strain, and magnetoresistive sensors to measure the local magnetic field resulting from the flow of charge. Embedding of these sensors is not trivial as the performance of the cell must be unaffected by the modifications. Furthermore, the embedded sensors must survive the cells internal environment. Methodologies for embedding sensors in pouch and cylindrical cells are discussed.

These instrumented cells collectively provide a powerful suite of in-situ and in-operando diagnostics for assessing performance, detecting defect propagation and materials degradation. These diagnostic methods are of great academic interest allowing ageing and failure mechanisms to be studied in greater detail. Furthermore, such diagnostic methods would also be useful in industry allowing systems reliant on lithium battery technology to be characterised in relation to battery operation. Here we present examples of the use of instrumented cells to understand the changes occurring within the cells when operated outside manufacturers’ guidelines and under abuse conditions. Data showing progression of failure is also presented.
Diagnostic Examination of NCM523//Graphite Cells Cycled at High Voltages
Authors: Abraham Daniel P , Gilbert James A
Published: February 2020

High energy materials are needed to increase the energy density of Li-ion batteries for vehicular applications. Layered-oxides are promising high energy positive-electrode materials; however, the performance of cells containing these oxides degrades faster when cycled to high potentials (> 4.3 V). In order to understand the origin of this performance loss, we conducted extensive tests with 2032-type coin cells and reference electrode (RE) cells; the results of these tests will be reported during this presentation.

The coin cells in this study contain 1.6 cm2 area Li1.03(Ni0.5Co0.2Mn0.3)0.97O2-based (NCM523) positive and a graphite-based negative electrode (Gr); the electrolyte is 1.2M LiPF6 in EC:EMC (3:7 w/w) electrolyte (Gen 2). The reference electrode cells contain 20.3 cm2 area NCM523-positive and Gr-negative electrodes, two Celgard 2325 separators enveloping a LixSn RE, and a Li-metal RE external to the electrode sandwich. Cell cycling includes formation cycles followed by aging cycles; pulse-power and AC impedance measurements are made periodically throughout the cycling.

The Li-metal RE provides information on the positive and negative electrode potentials during full cell cycling; such information cannot be obtained from the coin cell data. For example, during cell formation, when the full cell is cycled between 3.0 and 4.4 V, the positive electrode cycles between 3.67 and 4.46 V vs. Li/Li+ and the negative electrode cycles between 0.67 and 0.06 V vs. Li/Li+. The electrode cycling potential ranges change during cell aging. Furthermore, electrode impedances measured with the LixSn RE also change during aging. We will highlight the reasons for these changes during the presentation.

In addition to the electrochemistry results we will discuss data obtained by various diagnostic techniques that include the following: Scanning electron microscopy, Raman spectroscopy, and X-ray diffraction. Our mechanistic understanding of the capacity fade and impedance rise of the NCM523//Gr cells will be discussed through these various data.
(Invited) Investigation of the Reaction & Degradation Mechanism of Iron Based Cathodes for Sodium-Ion Batteries Using X-Ray Absorption and Time-Resolved X-Ray Diffraction Techniques
Authors: Ali Ghulam , Kim Dong-Hyun , Lee Ji-Hoon , Chung Kyung Yoon
Published: February 2020

Because of the growing level of energy consumption, numerous efforts have been made to develop high performance rechargeable batteries to use for large scale applications such as electrical energy storage systems (ESS). Lithium ion batteries have been the most popular and widely used batteries in portable devices like cell phones, laptops, etc. However, it has some constraints to be used for large scale applications as the cost for the raw materials for lithium is expensive. There have been ongoing studies searching for alternative shuttle ions and sodium can be one of the possible substitutes since it is more abundant and cheaper. The development of high performance cathode materials is required for the realization of sodium-ion batteries (SIBs) as the reduction potential of sodium is lower and its ionic radius is larger compare to lithium. Because of larger ionic radius, the de/intercalation of sodium causes to large volume contraction/expansion of the host materials which could affect the rate capability and long cycle life. The structural analysis during electrochemical reaction can provide better insight to understand the material’s behavior. Furthermore, thermal analysis is one of the critical issues for the electrodes and causes to the failure of the battery system.  

Here, we report the synthesis, electrochemical properties and investigate the reaction mechanism of iron fluoride hydrate and iron phosphate cathodes for SIBs. The crystal structure of iron fluoride hydrate is refined and the results show pyrochlore structure (with space group of Fd3m) with hydrate contents residing in zigzag positions. Thermal stability of the as prepared iron fluoride hydrate is determined using thermogravimetric analysis coupled with temperature-dependent TR-XRD. A nanocomposite of iron fluoride hydrate encapsulated within reduced graphene oxide sheets is prepared as cathode for the high performance SIBs. The nanocomposite delivers a high discharge capacity of ~260 mAh/g at current density of 0.05 C (1C=220 mAh/g) and it retains a discharge capacity of 230 mAh/g over 100 cycles, demonstrating a good cycle stability. The ex situ TEM and XANES have employed to determine the reaction mechanism. The surface of the olivine iron phosphate is modified with a polymer (thiophene) to improve the electrochemical performance. The coating with thiophene not only increases the electrical conductivity but also prevent the degradation of the material. The coated electrode exhibits high electrochemical performance and delivers a discharge capacity of 142 mAh g-1 with capacity retention of 94% after 100 cycles. The reaction mechanism of the coated electrode has been investigated using x-ray absorption spectroscopy. Thermal analysis of the cycled electrode is conducted using temperature-dependent TR-XRD.
Coupling Surface Imaging, FIB, and Spectroscopies to Understand Silicon Anodes Lithiation and Ageing Mechanisms
Authors: Bordes Arnaud , De Vito Eric , Haon Cédric , Montani Alexandre , Boulineau Adrien , Marcus Philippe
Published: February 2020

To follow growing energy demand of new devices, batteries energy density needs to be improved. Silicon-based anode is a serious option since it offers a specific capacity almost ten times higher than carbonaceous materials. Even so silicon anodes suffer from a drastic capacity fading making it unusable after few cycles. A fine understanding of the lithiation mechanism of silicon could participate to the elaboration of more robust architectures.

In this work1, composite silicon electrodes have been electrochemically cycled vs Li. After a transfer from a glove box to a ToF-SIMS by using an air-tight vessel, chemical mapping of the inside of silicon grains can be done by achieving an in-situFIB cut.

The first lithiation has been extensively studied. By stopping lithiation at different stages it is possible to follow the evolution of the core-shell structure (ie LiSi alloy shell and pure Si core) as shown in fig.1. This method also permits to observe the Si particles, considering their position within the depth of the electrode. To complete this study, cross analysis with Auger spectrometer, SEM and TEM have been performed, allowing to quantify Li presence in the LixSi alloy and better understand the pure Si core morphology. At the end, a complete mechanism for silicon particles is proposed.

In a following step, Si electrodes have been observed after 3, 5 and 10 cycles (limited capacity of 1000 mAh.g-1) in both lithiated and delithiated states. After three cycles the core-shell structure is still visible in lithiated state. After 10 cycles the presence of Si particles containing lithium at the end of the charge are observed and associated to particle getting out of the conductive grid and trapping lithium. This phenomena are detrimental to battery lifespan and participate in the failure of limited cycling strategies.

(1) Bordes, A.; De Vito, E.; Haon, C.; Boulineau, A.; Montani, A.; Marcus, P., Multiscale Investigation of Silicon Anode Li Insertion Mechanisms by Time-of-Flight Secondary Ion Mass Spectrometer Imaging Performed on an in Situ Focused Ion Beam Cross Section. Chem. Mater. 2016.

Figure 1
Polyoxometalate Modified Biomass Carbon Composites for Supercapacitor Electrodes
Authors: Genovese Matthew , Lian Keryn
Published: February 2020

Polyoxometalates (POMs), nanoscale transition metal-oxide clusters, have emerged as promising building blocks for the fabrication of pseudocapacitive electrodes.[i] These POM clusters undergo fast reversible electron transfer reactions and have multiple stable redox states, ideal characteristics for energy storage applications.[ii] In order to leverage these properties for use in electrochemical capacitor (EC) electrodes, these POM clusters must be immobilized on a stable carbon substrate to create a composite electrode. There is synergy in this combination as the POMs contribute faradaic redox processes, while the carbon provides stability, high conductivity, and electrochemical double layer capacitive (EDLC) contributions.

Porous carbon derived from biomass is an excellent potential substrate for these POM-carbon composites owing to its low cost, simple synthesis procedure, and high specific surface area. Here, we will report on our synthesis of porous carbon substrates derived from pine cone biomass via a two-stage carbonization and chemical activation procedure. These pine cone carbon samples are highly porous with specific surface areas over 2500 m2 g-1. In a sulfuric acid electrolyte, the high surface area of these samples results in a double layer capacitance of 265 F g-1. In order to further enhance this already large capacitance, the biomass carbons were modified with Keggin POM clusters, PMo12O40
3- and PW12O40
3- via a single step chemisorption.

We have discovered that the intrinsic porosity and surface conditions of the pine cone biomass carbon are particularly well suited to the immobilization of Keggin POMs. Additionally, by adjusting the activation conditions, the carbon porosity can be tuned to further enhance POM chemisorption. The result is biomass carbon hybrids with exceptionally high loading of POM clusters. The redox activity of these immobilized POMs leads to significantly enhanced area and volume specific capacitance compared to the bare carbon substrate (Figure 1). In this talk, we will present the full characterization of the POM-biomass carbon hybrids as well as discuss the activation conditions and resulting substrate porosity necessary for superior POM adsorption. The POM chemistry that results in the optimal pseudocapacitive performance will also be presented and discussed.

[i] M. Genovese, K. Lian. Current Opinion in Solid State and Materials Science. 19 (2015) 126-127

[ii] B.B Xu, L. Xu, G.G. Gao, W.H. Guo, S.P. Liu. J. Colloid Interface Sci. 330 (2009) 408

Figure 1
(Invited) Ultracapacitive Energy Storage Using 2D Nanomaterials Under Extreme Conditions
Authors: Park Ho Seok
Published: February 2020

With increasing demand for high performance energy storage devices, the feasibility of reliable and functional energy storage devices that well operates under extreme conditions is of prime importance for expanding applicative fields as well as for understanding materials’ intrinsic and extrinsic properties and device physics.1-4 In this talk, I will introduce the control in the physical structure and chemical composition of 2D nanomaterials for ultracapacitive energy storage devices under limited circumstances, where conditions are classified into thermodynamic (e.g. pressure, volume and temperature) and kinetic (e.g. high rate and frequency) variables.1-10 In addition, a fundamental foundation via in-situ spectroscopic techniques will be presented to understand charge storage phenomenon of new materials and devices occurring on a nanoscale under various circumstances.8-10

Keywords: Supercapacitor, 2D nanomaterials, Graphene, Pseudocapacitors, Flexible energy storage.

Ref.

[1] Ho Seok Park*, et al.
Adv. Funct. Mater.
, 2016, 26, 903–910.

[2] Ho Seok Park*, et al.
Adv. Energy Mater.
, 2015, 1500959.

[3] Ho Seok Park*, et al.
ACS Nano.
, 2015, 9, 8569-8577.

[4] Ho Seok Park*, et al.
Adv. Funct. Mater.
, 2015, 25(7) 1053-1062.

[5] Ho Seok Park*, et al.
ACS Nano
, 2011, 5 (9) 7205-7213.

[6] Ho Seok Park*, et al.
ACS Nano
, 2011, 5 (6) 5167–5174.

[7] Ho Seok Park*, et al.
ChemSusChem
, 2014, 7(4) 1094-1101.

[8] Ho Seok Park*, et al.
Nano Energy
, 2015, 15, 576-586. 

[9] Ho Seok Park*, et al.
Nano. Lett.
, 2015, 15 (4), 2269-2277.

[10] Ho Seok Park*, et al.
Adv. Energy Mater.
, 2016, 6, 1501115.
Chemically Deposited NiCo2O4 Thin Films for High-Performance Supercapacitors
Authors: Deokate Ramesh J. , Kalubrame Ramchandra S. , Lokhande Chandrakant D
Published: February 2020

Changes in climatic conditions resulting from the consumption of fossil fuels and their limited availability have affected the global ecology and economy. The shift towards a more sustainable energy economy has illustrated the need for the development of low cost and environmentally friendly energy storage systems. Supercapacitors, also known as ultracapacitors or electrochemical capacitors, warrant broad important applications in electric vehicles and mobile power sources due to the unique combination of their properties, such as rapid charge–discharge behavior and higher specific power density than batteries and fuel cells while possessing higher energy densities than conventional double layer capacitors.

NiCo2O4-based materials have been intensively investigated for pseudocapacitors due to their high theoretical specific capacitance, good chemical and thermal stability, natural abundance, environmental benignity and low cost. In the present work, Nickel cobalt oxide (NiCo2O4) thin films have been systematically prepared using spray pyrolysis method for its application in supercapacitors. Briefly, we prepared two different aqueous solutions of 0.1 M nickel chloride and cobalt chloride by dissolving in de-ionized water (DIW), respectively. In the spray pyrolysis process, aqueous solutions of nickel and cobalt precursor mixed with volume ratio 1:2 were sprayed over the FTO substrates maintained at various temperatures in the form of mist using air-blast spray pyrolysis unit. The sprayed mist undergoes thermal decomposition to form the NiCo2O4 thin films. The electrochemical performance of the NiCo2O4 thin film was measured in a 2M KOH electrolyte with potential window 0 to 0.5 V. Galvanostatic charge– discharge (GCD) studies were also carried out.

The field-emission scanning electron microscopy (FE-SEM) image shown in Fig. 1, reveal that compact and uniform thin films of cubic nickel cobaltite with particle size 10-20 nm has been obtained by the oxidation of Ni and Co precursors. Moreover, it is observed that nanostructured NiCo2O4 thin film deposited at 350 0C exhibit the best charge storage property with high specific capacitance of 752 F g−1 and excellent cycle stability over 1000 cycles. The high specific capacitance, remarkable rate capability and excellent cycling stability of the composites mean that they show promise for application in supercapacitors.

Figure 1
Effect of Porous Structure of Electrodes on the Properties of AC/AC Edlc with Organic Electrolyte
Authors: Köse Kadir Özgün , Aydinol Mehmet Kadri
Published: February 2020

Electrochemical double layer capacitors (EDLC) are energy storage devices that utilize ion adsorption at the double layer. Their typical electrodes are porous, conductive materials, such as activated carbon. In the present study, activated carbon is derived from pine cone (pinus pinea). The activation process is carried out with the aid of activating agents ZnCl2 and H3PO4. The effects of impregnation ratio (mass of activating agents/mass of precursor), and activation temperature on the resulting porosity, pore size distribution and texture of the activated carbon are examined. Surface area and pore volume are measured by N2 adsorption at 77 K. Textural properties are characterized by HRTEM. To achieve high energy density, organic electrolyte (acetonitrile) is used with TEABF4 dissolved in it. Galvanostatic charge-discharge, cyclic voltammetry and electrochemical impedance spectroscopy are applied to assess electrochemical behavior. The effect of porous structure on the energy and power characteristics of the EDLC is determined and by manipulating the activation process of AC, the properties of EDLC are optimized.
Manganese Dioxide Electrode: Attempts to Increase the Electrochemical Utilization
Authors: Gambou-Bosca Axel , Bélanger Daniel
Published: February 2020

Manganese dioxide has been the subject of intense research in recent years since it has been demonstrated that they are characterized by pseudocapacitor properties. Furthermore, hybrid electrochemical capacitor using a negative carbon electrode and positive manganese dioxide electrode together with an aqueous electrolyte allows to prepare a device with a higher cell voltage than either carbon/carbon or manganese dioxide/manganese dioxide symetrical electrochemical capacitor. Unfortunately, the high theoretical specific capacity of a manganese electrode cannot be obtained when thick and industrially relevant electrodes are investigated. In fact, no more than 20% of the manganese dioxide-based electrode material is electrochemically addressable. In this talk, attempts to increase the electrochemical utilization of manganese dioxide will be presented. Our recent studies focussing on the effect of carbon additives, shape of manganese dioxide particles, electrode formulation and electrolyte, including water-in-salt electrolyte, on the performance of manganese dioxide electrode tested in the three-electrode configuration (single electrode characterization) and as a full system will be investigated (1-4).

1. A. Gambou Bosca, D. Bélanger, Effect of the formulation of the electrode on the pore texture and electrochemical performance of the manganese dioxide-based electrode for application in a hybrid electrochemical capacitor. Journal of Materials Chemistry A., 2014, 2, 6463-6473.

2. A. Gambou Bosca, D. Bélanger, Chemical mapping and electrochemical performance of manganese dioxide/activated carbon based composite electrode for asymmetric electrochemical capacitor. Journal of the Electrochemical Society. 2015, 162, A5115-A5123.

3. A. Gambou Bosca, D. Bélanger, Electrochemical accessibility of porous submicron MnO2 spheres as active electrode materials for electrochemical capacitors, Electrochimica Acta, accepted.

4. A. Gambou Bosca, D. Bélanger, Electrochemical Characterization of MnO2-Based Composite in the Presence of Salt-in-Water and Water-in-Salt Electrolytes as Electrode for Electrochemical Capacitors, J. Power Sources, submitted.
Simple and Versatile Fabrication of 3D Micro-Supercapacitors Using Pneumatic Printing Combined with Intense Pulsed White Light
Authors: Song Chiho , Kim Hak-Sung , Ahn Heejoon
Published: February 2020

Recently, rapid developments of compact mobile and wearable electronics and micro-medical devices are accelerating an increasing demand for miniaturized energy storages such as micro-supercapacitors. Graphene, a representative two-dimensional carbon material, has attracted enormous interest due to its excellent electrical, mechanical, physical and chemical properties. In particular, many efforts have been made to fabricate graphene-based micro-supercapacitors due to its large specific surface area and superior electrical conductivity. However, many of the attempted fabrication processes have drawbacks, such as complicated multiple-step procedures to create micron-sized interdigitated electrodes and usage of harmful or toxic chemicals during the etching process. In addition, high-temperature treatment is demanded to obtain high-quality graphene materials which is suitable for high-performance graphene-based micro-supercapacitors. Therefore, simple, cost effective and energy efficient strategies are still required for the fabrication of graphene-based micro-supercapacitors. Here, we report a simple, agile and facile method for the fabrication of three-dimensionally printed micro-supercapacitors with high-aspect-ratio electrode micro-arrays using a pneumatic printing technique in conjunction with an intense pulsed white light (IPWL) technology. By using this combined method, micron-sized electrode patterns can be easily printed on diverse substrates, and graphene- or metal oxide-based three dimensional micro-patterns can be fabricated within milliseconds by irradiating the IPWL on graphene oxide or metal oxide precursor patterns, which is exceptionally faster and easier than other graphene reduction and metal oxide formation methods. The as-prepared micro-patterns are further utilized as micro-supercapacitor electrodes, and their electrochemical properties and supercapacitive performance are investigated by means of cyclic voltammetry, galvanostatic charge/discharge and electrochemical impedance spectroscopy.
High Voltage Lithium Ion Capacitor for Elevated Temperature Applications; Built on Activated Carbon and Litfsi Dissolved in Alkylcarbonates Compound
Authors: Salari Maryam , Grinstaff Mark W
Published: February 2020

The increased number of lithium ion batteries and supercapacitor technologies utilized in everyday products demands more reliable and safer technologies enabling high energy densities with faster response times over extended range of temperatures. This work presents a method to fabricate a thermally resistance lithium ion supercapacitor (LIC); a strategy for realization of a safer supercapacitor for elevated temperature applications. Specifically, we report and discuss the performance of symmetric activated carbon electrodes supercapacitors with LiFTSI in a glycerol carbonate compared to that in EC/DMC electrolytes. The gravimetric analysis based on the total weight of electroactive materials gave a specific capacitance of 162 F/g at 1 mV s-1, energy density of 14.2 Wh kg-1 at 2 A/g and power density of 7.5 KW kg-1 at 10 A/g at a temperature of 100 ºC. Cyclic voltammetry (CV), charge discharge (CD), and electrochemical impedance spectroscopy (EIS) were performed to investigate the electrochemical properties of the fabricated coin cells.

Fig.1 Chronological map cycling behavior of AC electrodes in glycerol carbonate electrolyte at a current density of 2 A/g over a applied potential of a 2.5 V, obtained through various thermal ageing process as well as cycling procedures.

Figure 1
Facile Synthesis of Nanostructured Co3O4 thin Films at Low Temperature for High-Performance Pseudocapacitors
Authors: Tian Kuan , Wei Lu , Guo Xin
Published: February 2020

Co3O4 as a low cost, environmental friendly and nice corrosion resistant electrode material for pseudocapacitors, owns a high theoretical specific capacitance up to 3650 F g-1. However, the actual specific capacitance of Co3O4
is much lower than its theoretical value according to the present literatures. In order to improve the electrochemical performance of Co3O4 electrodes, various binder-free and self-supported Co3O4 thin films with distinct nanostructures were prepared by facile chemical bath deposition at low temperature (Figure.1). The diverse morphologies of Co3O4 thin films (3D thorn-like structure, porous nanoplates, nanoparticles and ultrathin nanosheets) were controlled by the different anions (SO4
2-, NO3
-, Cl- and CH3COO-) of cobalt sources used in synthesis procedure. Among them, the cobalt acetate derived Co3O4 thin film electrodes (A-Co3O4) exhibit the best electrochemical performances in 2 M KOH electrolyte (Figure. 2), such as a high specific capacitance (1545 F g-1) and nice cycling stability (84.6 % retention after 1000 charge-discharges at a high current density of 4 A g-1).

Figure 1
CVD Assembly of 3D Graphene and Their Contribution for Lithium-Sulfur Batteries with High Energy Density and Long Lifespan
Authors: Zhang Qiang , Huang Jia-Qi , Peng Hong-Jie , Cheng Xin-Bing
Published: February 2020

Among various promising candidates with high energy densities, lithium-sulfur (Li-S) batteries with a high theoretical capacity and energy density are highly attractive;1-2 while the commercial application of Li-S batteries still faces some persistent obstacles, such as the low electrical conductivity of sulfur and lithium sulfide and the dissolution of polysulfides. The introduction of 3D graphene into the field of Li-S batteries sheds a light on the efficient utilization of sulfur by improving the conductivity of the composites and restraining the shuttle of polysulfides. In this presentation, the concept for the rational design of 3D graphene is explained. The advances in the use of 3D graphene in the cathode, separator, and anode is explained.3-12 New insights on the relationship between the 3D graphene structure and the electrochemical performance are presented.

References

Wang JG, Xie KY, Wei BQ.
Nano Energy
2015, 15, 413.

Manthiram A, Chung SH, Zu CX.
Adv Mater
2015, 27, 1980.

Zhao MQ, Zhang Q, Huang JQ, et al.
Nature Commun
2014, 5, 3410.

Cheng XB, Huang JQ, Zhang Q, et al.
Nano Energy
2014, 4, 65.

Huang JQ, Zhang Q, Peng HJ, et al.
Energy Environ Sci
2014, 7, 347.

Tang C, Zhang Q, Zhao MQ, et al.
Adv Mater
2014. 26, 6100.

Zhao MQ, Peng HJ, Tian GL, et al.
Adv Mater
2014, 26, 7051

Yuan Z, Peng HJ, Huang JQ, et al.
Adv Funct Mater
2014, 24, 6105.

Zhao MQ, Liu XF, Zhang Q, et al.
ACS Nano
2012, 6, 10759.

Cheng XB, Peng HJ, Huang JQ, et al.
ACS Nano
2015, 9, 6373.

Huang JQ, Zhuang TZ, Zhang Q, et al.
ACS Nano
2015, 9, 1506.

Peng HJ, Zhang Q.
Angew Chem Int Ed
2015, 54, 11018.
Improvement of Contact Resistance of Graphene Devices Via AuCl3 Doping
Authors: Choi Dong-Chul , Jung Jongwan
Published: February 2020

Graphene, an atomically thin semi-metal with sp2–bonded carbon atoms arranged in a honeycomb lattice is at center stage of intense research in the field of fundamental physics as well as in low-cost flexible transparent electronics, photovoltaics or microelectronics devices. For electronic devices application, the metal - graphene contact resistance is forefront obstacles hindering further progress of any graphene-based devices. The contact resistance degrades the on-state current of charge-based field-effect-transistor. Gold chloride (AuCl3) doping has been reported for reducing the sheet resistance of graphene films for transparent electrodes. In this work, we used the gold chloride (AuCl3) solution doping only to the metal-graphene contact area to reduce the contact resistance without changing graphene film properties. First, graphene film was grown using chemical vapor deposition (CVD) method. Active pattern was formed by lithography and reactive ion etching (RIE). The metal-graphene pad area was defined by lithography. The exposed graphene surface area for metal pads was dipped in AuCl3 solution. Here we changed the AuCl3 concentration to see the concentration effect. After that, Ti/Au pad metal was evaporated using thermal evaporator. AuCl3 doping was done only to metal-graphene contact interface. KPFM was employed to measure the surface potential of graphene. The Raman spectroscopy and XPS spectra were analyzed before/after the doping of AuCl3 solution on contact area. The contact resistance of un-treated graphene devices, 1773 Ohm.um decreased to 987 Ohm.um after 5mM-treatment, and decreased to 897 Ohm.um after 10mM-AuCl3 doping. At doping above 10mM doping, the contact resistance did not decreased further. We also characterized the contact resistance change with time. The contact resistance of AuCl3-treated graphene increased by ~13% after 2 months. On the contrary, the sheet resistance of AuCl3-treated graphene film(without any photomask) increased by ~50% after 1 month. The contact resistance increase is much less than the sheet resistance change. This could be explained by the fact that the metal pad covers the AuCl3.

This research was supported by the MOTIE (10052928) and KSRC (Korea Semiconductor Research Consortium) support program for the development of future semiconductor devices.
Hybrid Structure of Atomically Thin Carbon Nanosheet/Au Particles and Its Application As Organic Solar Cells
Authors: Lee Sungho , Jo Seung Mu , Joh Han-Ik
Published: February 2020

Graphene with two-dimensional structure has attracted a significant interest due to its unique properties such as remarkable optical transmittance, electrical conductivity, and electron mobility. There are two representative methods to prepare the large-area graphene with properties suitable for organic electronics: chemical vapor deposition and solid carbon coating. In the former method, the graphene is synthesized using gasified carbon species (i.e. methane) deposited onto metal film as a catalyst at temperature as high as 800 oC. In the latter method, solid carbon sources such as polymer, graphite, and self-assembled monolayer are coated on the metal film, followed by thermal treatment at similar temperature to the former method. The graphene prepared by the methods exhibits superior properties to chemically converted graphene. However, the graphene grown on the metal substrate has to transfer on the other proper substrates such as Si wafer to apply for the electrodes of the organic electronics. The transfer process brings about the artificial defects, such as wrinkles, cracks, and vacancy, on the graphene, resulting in degradation of the graphene properties. In this study, we have introduced a novel and simple approach to prepare an atomically thin carbon nanosheet (CNS) similar to graphene properties. In addition, we have modulated the electronic properties the CNSs using chloride-based metal precursor. The CNSs were prepared using polyacrylonitrile (PAN) polymer spin-coated onto the quartz substrates. The polymer films were oxidized at 250 oC for 2 h in order to induce formation of ladder structure. The oxidized films were then heat-treated at 1150 oC under a H2/Ar mixture to promote inter- and intra-molecular bonding and remove heteroatoms bonded to the carbon atom. The structural and morphological properties of the CNS were analyzed by HR-TEM, Raman spectroscopy, XPS, and AFM. The CNS prepared using 0.5 wt% PAN solutions showed about 0.4 nm of thickness, 1600 S/cm of electrical conductivity, and 92% of transmittance. The CNS was mostly composed of sp2 carbon with a small amount of impurities such as oxygen and nitrogen analyzed by XPS. The metal ions in the precursors are easily reduced into the metal particles without post-treatment due to the electron transfer from the CNSs to the metal ions. The WFs of the CNSs doped with AuCl3, ZnCl2, and CoCl2 exhibit significantly higher values of 4.91, 4.77, and 4.69 eV, respectively, compared to the pristine CNSs (4.60 eV). The metal particles on the CNSs locally influence the electronic modification of the CNSs, leading to transparent conducting electrodes with high WFs and a high power conversion efficiency of ~ 2.01%. Therefore, we suggested that the CNS modified by metal precursor is a promising candidate as transparent and conductive electrodes for organic devices. The specific properties and the possibility of utilization of the CNS will be discussed.
3D Porous Hollow Microspheres of Activated Carbon from Nature through Nanotechnology for Electrochemical Double-Layer Capacitors
Authors: Wei Lu , Tian Kuan , Zhang Xingyan , Jin Yiyi , Guo Xin
Published: February 2020

Porous activated carbons have attracted considerable attention as electrode material in energy storage devices, as they have high specific surface area and good conductivity. However, common processes to synthesize activated carbon nanostructured electrodes only offer limited control on their morphology and structure. In this work，three-dimensional (3D) porous hollow microspheres of activated carbon were fabricated from various pollen grains (camellia, Schisandra chinensis, lotus, rape and motherwort) through a facile, green and economic route (Figure 1). The sustainable and abundant carbon sources of pollens allow for mass production of nanostructured activated carbon microspheres (ACMs) with good electrochemical performances. Thus obtained ACMs retain the 3D hierarchical penetrable architecture of pollen grains, with vertically arranged nanorod-framework constructed shell and high volume of micropores/mesopores. Such activated carbon electrodes show remarkable electrical double-layer storage performances (Figure 2), such as a high specific capacitance (250 F g-1 in an organic electrolyte), superior rate capability (210 F g-1 retained at a very high current density up to 40 A g-1), and good cycling stability (91.8% retention after 10,000 charge/discharge cycles).

Figure 1
Graphene Conductivity Control By Friction Induced Charge Trapping
Authors: Kim Seongsu , Kim Tae Yun , Lee Kang Hyuck , Falconi Christian , Kim Sang-Woo
Published: February 2020

Generally, t
he
resistivity
of
chemical vapor deposition (CVD) based large-area
graphene films is much
high
er
than that of
single crystalline
mechanically exfoliated graphene
. Therefore, the performance of CVD graphene based electronic devices has various limitations. Here
we
introduce a novel method for reducing the electrical resistivity of CVD graphene through triboelectrification. T
riboelectri
c
charges, generated by the friction
between a Pt
tip
and graphene
, reduced the resistance of CVD graphene film/SiO2 system
dramatically
.
The
charges
were localized only in the friction area and survived
more than 12 hours. The graphene film on the localized charges has an ~
80% reduced resistance without damage and without resort to any chemical surface treatments.
T
he localization of triboelectric charges was successfully achieved in a monolayer CVD graphene film/SiO2 system,
but the charges
were not localized when we used mechanically
exfoliated graphene flake or highly ordered pyrolytic graphite (HOPG) film.
Moreover, the resistance of the graphene film on the localized charges can be modified by controlling the localized charge density
and polarity
.
Electrochemical Properties of Fe-Based Amorphous Metallic Coatings in Aqueous Media
Authors: Kim Seunghyun , Kim Jeong Won , Kim Ji Hyun
Published: February 2020

Coating as an effective corrosion barrier for various industrial application is one of the major research trend in electrochemistry. Many types of coating materials and techniques have been suggested and a high-velocity oxy-fuel (HVOF) technique has adequate potential. Fe-based amorphous metallic coating (AMC) is a non-crystalline alloy coating with spatially dispersed nanocrystalline structure. As they are known as an effective anti-corrosion and anti-wear resistance, some research groups have figured out their corrosion behavior in corrosive environments. In this study, we experimentally demonstrated the corrosion behavior of Fe-based AMC in seawater and alkaline medium environments using various electrochemical tests including linear sweep voltammetry (LSV) and electrochemical impedance spectroscopy (EIS). Fig. 1. Displays the powder morphology of Fe-based AMC feedstock material. Spherical shape with ca. 30 um size particles can be observed. The chemical composition is 54.05Fe-18.31Cr-11.34W-12.5Mo-2.8Mn. After the spray process, surface and cross section morphologies are analyzed by SEM (Fig. 2). Fig. 3. Displays the corrosion behavior of the substrates and the coatings in seawater and alkaline media, respectively. The results indicates that corrosion resistance of Fe-based AMC is not remarkable in both media. Fig. 4. Also displays the corrosion resistance is lower and double layer capacitance is higher compared to those of the substrates. Thus, likewise to other research results, the as-sprayed Fe-based AMC exhibits less corrosion resistance compared to carbon steels. However, their promising potential in high-temperature alkaline media and flowing conditions will be figured out as our future works.

Figure 1
Effects of Crystallinity of Spark Plasma Sintered Fe Base Nano-Composite Alloy
Authors: Na Hyunwoong , Oh JI-Won , Choi Hanshin
Published: February 2020

In powder metallurgy technology, bulk engineering components are manufactured by sintering powder feedstock at either solid state sintering or liquid phase sintering. Lots of researches have been conducted to optimize bulk materials properties via material design and process engineering: developments of sintering activators and novel sintering processes. Spark plasma sintering process belongs to pressurized sintering and it is advantageous for reducing sintering temperature and time owing to internal Joule heating of powders. As a result, growth of grain and/or precipitates which have critical influences on materials properties can be effectively suppressed. In the present study, a multi-component Fe base alloy which shows high hardness and wear resistance is sintered by SPS process. Powder characteristics, spark plasma sinterability, characterization of sintered bodies are reported. Considering large solidification temperature range of the alloy, effects of liquid phase fraction on density, microstructures, phase evolutions, and hardness were highlighted. Corrosion resistance of the alloy is largely dependent on the phase composition. Therefore, anodic polarization behaviors were investigated according to crystallinity of sintered bodies.
Hydration Structures and Water Chemistry at Zirconia-Water Interface
Authors: Hou Binyang , Park Changyong , Kim Seunghyun , Kim Taeho , Kim Ji Hyun , Kim Jongjin , Hong Seungbum , Bahn Chibum
Published: February 2020

The life cycle of zirconium cladding is a key safety factor and design parameter for higher fuel burnups in pressurized water reactors. The degradation of the metal alloy is primarily attributed to interactions of native oxide with water. Here we probe the detailed interfacial hydration structures at the 8 mol% yttria-stabilized cubic zirconia (YSZ) surfaces as a model system using synchrotron-based high-resolution X-ray reflectivity technique. Interfacial hydration structures in the major crystallographic orientations, (100), (110), and (111), were determined with sub-angstrom resolution and compared with each other to identify common features as well as different surface chemistry effects on the interfacial processes. All three surfaces terminate with significant number of point defects originating from the metal depletion and the intrinsic oxygen vacancies. Water molecules fill those vacancies, forming an ordered, layered structure on the top surface. Above the termination layer on each surface, two additional adsorbed layers form characteristic interfacial hydration structures. The first adsorbed layers likely include metal species based on the observed local densities, whereas the second layers consist of pure water. The current results provide valuable references for future studies of water chemistry effect on the interfacial hydration structure and the high temperature stability test of the zirconia in pressurized water conditions simulating realistic environment in pressurized water reactors of nuclear power plants.

We also studied the effect of zinc adsorption on the interfacial hydration structure in zinc acetate solutions. Zinc injection into the reactor coolant system has been known to be effective in reducing the radioactive wastes as well as stabilizing crud oxide layers of the cladding materials. Our X-ray reflectivity data qualitatively reveal that there are obvious hydration structure changes at (100) and (111) surfaces while (110) surface show little changes. The interfacial electron density profiles were derived from the structure factor analysis of the measured reflectivity data. The structure factor analysis indicated an inner-sphere adsorption of Zn2+ layer at YSZ (111)-water interface, while there appeared to be an outer-sphere adsorption of Zn2+ layer at YSZ (100)-water interface. We further confirmed the detailed element specific adsorption profile of Zn2+ ions on YSZ (110) and (111)-water interfaces with resonant anomalous X-ray reflectivity measurements.
"Solidifying” Batteries – Solid Electrolytes in Lithium (Ion) Batteries
Authors: Janek Jürgen
Published: February 2020

Solid electrolytes and solid state batteries are currently attracting serious interest as potential future components and storage devices. Solid electrolytes (polymer, ceramic or composites) are required to construct protected lithium anodes – in case that lithium metal anodes will become again part of lithium batteries. If the cathode is still employed in contact with a liquid electrolyte, a new interface between a liquid and a solid electrolyte forms which can be highly resistive. Solid state batteries without any liquid electrolytes are considered as ultimately stable and safe devices, but are expected to suffer from poor kinetics and high costs. The lecture will include answers to the following questions:

Are solid electrolytes necessarily worse lithium ion conductors than liquid electrolytes?

Are solid electrolytes necessarily more stable than liquid electrolytes?

What do we know about the interface between liquid and solid electrolytes?

Status quo of thin and thick film solid state batteries?

Important research tasks in the development of solid state batteries?
Highly Concentrated Electrolyte for 5 V Systems
Authors: Inaba Minoru , Masuhara Rin , Shimizu Yusuke , Hashinokuchi Michihiro , Doi Takayuki , Inoue Hidemi , Takahashi Katsuyuki , Nakagawa Hiroe , Inamasu Tokuo
Published: February 2020

Highly concentrated electrolytes have many unique properties,1-4 such as Li+-intercalation into graphite anode without EC,1,3 suppression of S8
2- ion dissolution in Li-S batteries, etc., and is attracting much attention of many researchers.  In highly concentrated electrolytes, all solvent molecules are strongly coordinated with Li+ ions, and hence the stability of the electrolytes against oxidation is improved significantly.  Yoshida et al. reported that LiCoO2, which is a 4 V-class cathode, can be charged and discharged in a LiTFSI/triglyme (1:1) electrolyte with good cycleability,3 though triglyme is an ether compound and usually cannot be used as solvent. 

5 V-calss cathodes, e.g. LiNi0.5Mn1.5O4 and LiCoPO4, are promising for the next-generation LIBs with high energy densities.  Unfortunately no electrolyte systems that tolerate the highly oxidative 5 V-class cathode have been reported so far.  In the present study, we investigated the effect of concentration on the stability of highly concentrated electrolytes, LiPF6/PC and LiBF4/PC, against a 5 V-class cathode, LiNi0.5Mn1.5O4 to realize 5 V-class LIBs with high energy densities.

Figure 1 compares charge/discharge curves of a 5 V class spinel LiNi0.5Mn1.5O4 in standard (0.83 mol kg-1, Li/PC = 1/11.8) and highly concentrated (4.9 mol kg-1, Li/PC = 1/2) LiBF4/PC at 30°C.  The charge/discharge rate of C/10 was employed to emphasize electrolyte decomposition. Thought the LiNi0.5Mn1.5O4 can be charged and discharged in both electrolytes, the irreversible capacity (Qirr) in 1 M LiBF4/PC was high (76 mAh g-1) because of vigorous electrolyte decomposition.  In contrast, Qirr was significantly reduced in the concentrated electrolyte, which indicated that stability against oxidation was improved in the highly concentrated electrolyte.  Similar tendency was also observed in highly concentrated LiPF6/PC electrolytes, though polarization on charging and discharging were much higher.

A fresh half-cell was fully charged to 5.0 V, and kept at 60°C for 3 days in LiPF6/PC electrolytes.  The amount of Mn deposited on lithium counter electrode was evaluated by ICP as a measure of dissolved Mn ions. The amount of dissolved Mn ions decreased with increasing Li/PC ratio, which indicated that the use of highly concentrated electrolytes is also effective for suppressing Mn ion dissolution.

This work was supported by a Kyoto Area Super Cluster Program, Japan Science and Technology Agent (JST), Japan.

References:[1] S.-K. Jeong et al., J. Power Sources, 175, 540 (2008).; [2] K. Dokko, et al., J. Electrochem. Soc., 160, A1304 (2013).; [3] K. Yoshida, et al., J. Am. Chem. Soc., 133,13121 (2011).; [4] Y. Yamada, et al., ACS Appl. Mater. Interfaces, 6, 10892 (2014).

Figure 1
Interfacial Behaviors of Metal Lithium Anode in Solid Lithium Batteries
Authors: Li Wenjun , Li Qun , Liu Xiaosong , Guo Xiangxin , Fu Zhengwen , Chen Jian , Cui Guanglei , Hu Yongsheng , Gu Lin , Li Hong
Published: February 2020

Energy storage devices with energy density over 350 Wh/kg or 1000Wh/L are highly desirable. Rechargeable solid metal lithium battery is one of the possible solutions. The cathode could be lithium intercalation compounds, sulfides and air. The electrolyte could be polymer and inorganic solid electrolyte with and without liquid additive. Achieving excellent cyclic performance and high safety at reasonable rate and wide temperature range are two main challenges, which are related to the homogeneity of the deposition and depletion of metal lithium, electrochemical or chemical reaction of lithium with contacted gas, liquid and solid, change of the interfacial contact and the morphology change of metal lithium during charging and discharging. In this talk, a joint efforts for investigating metal lithium anodes in various rechargeable solid lithium batteries with and without liquid additive are reported and summarized. 

Acknowledgement

Financial supports from "Strategic Priority Research Program" of the Chinese Academy of Sciences (XDA09010200), “973” project of MOST (2012CB932900), NSFC project (51325206, Y5JC011E21), and Beijing S&T Project (Z13111000340000) are appreciated.