bluuebunny/crossref_metadata_2025 huggingface dataset:
Acid Stable Bismuth Vanadate for Photo Electrochemical Chlorine Production
Authors: Rassoolkhani Alan , Cheng Wei , Nguyen Kevin , Young Graham , Tentinger Scott , McKee Austin , Hemingway Monica , Mubeen Syed
Published: February 2020

Despite significant attention, water oxidation remains one of the largest bottlenecks for solar water splitting. This reaction produces a gas of minimal economic value while introducing kinetic losses to the system. While most research focuses on improving the kinetics minimal efforts have been undertaken to conduct other oxidation chemistries. Here we report the use of bismuth vanadate (BiVO4) for photoelectrochemical production of chlorine gas, an oxidation product possessing superior kinetics and higher economic value than the oxygen that results from standard solar water splitting. In order to prevent photo corrosion while operating in the acidic electrolyte (pH 1) an amorphous tungsten oxide protective layer was electrochemically deposited on the nanoporous BiVO4. These devices were able to demonstrate three hours of stable photocurrent while producing chlorine and hydrogen gas. Light absorbers that are stable in acidic solutions have widespread applications as the same solution is ideal for earth abundant materials that carry out the hydrogen evolution reaction taking place at the counter electrode.
Application of Phase Change Material to Increase Solar Panel Efficiency
Authors: Rose Kyle Duane , Aggarwal Mohan
Published: February 2020

Research has shown that heat is the number one deterrent to power production and efficiency of solar panels. To remedy this problem we used special techniques to apply a phase change material (PCM), non-intrusively to the back of our test panels. This process provided the ability to extract heat utilizing conduction mechanism with a diathermic material.

The method used for this research was quantitative data collection. This methodology involves use of existing historical documents such as climate, temperature, and insolation data along with currently measured data for analysis.

The results showed with the PCM applied to our test panels remained cooler than the controlled panels until the PCM absorbed its capacity of heat energy. The test panel’s temperature was cooler than the control panel. Power production, and efficiency showed a noticeable increase. Future research will utilize passive thermoelectric devices to convert the waste heat to useful energy. Furthermore working fluids such as glycol, and antifreeze of various concentrations to remove heat energy from the saturated PCM once the heat capacity has been reached. The application of PCM applied to the backside of a standard solar panel lowers the temperature and improves the panel’s energy conversion and efficiency. Author acknowledges some work which was accomplished with the partial support of NSF APEX project DRL 1238192.
17.6%-Efficient Radial Junction Solar Cells Using Silicon Nano/Micro Hybrid Structure
Authors: Hwang Inchan , Lee Kangmin , Seo Kwanyong
Published: February 2020

We develop a unique nano- and microwire hybrid structure by selectively modifying only the tops of microwires using metal-assisted chemical etching. The proposed nano/micro hybrid structure not only minimizes surface recombination but also absorbs 97% of incident light under AM 1.5G illumination, demonstrating outstanding light absorption compared to that of planar (59%) and microwire arrays (85%). The proposed hybrid solar cells with areas of 1 cm2 exhibit power conversion efficiencies (Eff) of up to 17.6% under AM 1.5G illumination. In particular, the solar cells show a high short-circuit current density (Jsc) of 39.5 mA·cm-2 because of the high light-absorbing characteristics of the nanostructures. This corresponds to an approximately 61.5% and 16.5% increase in efficiency compared to that of a planar silicon solar cell (Eff = 10.9%) and a microwire solar cell (Eff = 15.1%), respectively. Therefore, we expect the proposed hybrid structure to become a foundational technology for the development of highly efficient radial junction solar cells.
High Resolution TEM Study on Phase Transformations in Redox Active Silver Nanoparticles
Authors: Singh Poonam , Carpenter Ray , Buttry Daniel A
Published: February 2020

In the last two decades, nanoparticles (NPs) have been intensively studied because of the wide range of applications in catalysis, sensor, energy storage, electronics etc. The recent interest in fabricating core-shell nanoparticles is very fascinating and the substantial development of these nanoparticles for a variety of applications has only been enabled because of various characterization efforts. In spite of this, it is still very challenging to understand the growth mechanism that governs the formation of core-shell nanoparticles. A previous contribution from our group focused on electrochemical studies confirming the phase transformation of chemically synthesized capped silver nanoparticles to Ag2O or AgCl NPs. However, it is also important to understand the nucleation and growth mechanism of these nanoparticles, especially forming core shell or the complete recrystallization of NPs. In the current work, we are focused on microscopic studies in correlation with electrochemical results to understand the nucleation mechanism of silver nanoparticles.

Silver nanoparticles (Ag NPs) capped with adenosine triphosphate (ATP), synthesized via wet chemical method and assembled in single layer-by-layer (LbL) film have been characterized using voltammetry and high resolution transmission electron microscopy (HRTEM). The ex-situ voltammetry and HRTEM analysis confirms the phase transformation of AgNPs to Ag2O or AgCl NPs. Atomic resolution image by high-angle annual dark field scanning transmission electron microscopy (HAADF STEM) confirms the partial or complete oxidation of NPs which is consistent with the electrochemical results. The growth mechanism/pathways focused on core-shell nucleation and point nucleation for phase transformation of Ag NPs embedded in LbL film has been discussed.

Acknowledgement

We acknowledge the support from National Science Foundation (NSF) for this work.

References

1. P. Singh, K.L.Parent and D.A.Buttry, J. Am. Chem. Soc., 134
 
(12), 5610–5617 (2012).

2. M. Tang, W.C.Carter, J.F.Belak and Y.Chiang, Electrochim. Acta,
56, 969–976 (2010).

3. A.H.Latham, M.J.Wilson, P.Schiffer and M.E.Williams, J. Am. Chem. Soc.,
128, 12632-12633

(2006).

4. J. Ghilane, F. Fan, A.J.Bard and N. Dunwoody, Nano Lett., 7(5), 1406-1412 (2007).

5. E.V. Shevchenko, M.I.Bodnarchuk, M.V. Kovalenko, D.V.Talapin, R.K.Smith, S.Aloni,

W.Heiss and A.P.Alivisatos, Adv. Mater.
20, 4323–4329 (2008).
Synthesis of Ferromagnetic Cobalt Nanofibers By Electrospinning
Authors: Kessler Joseph Edward , Rugge Christopher Paul , Rosales Espitia Nataly , Myung Nosang Vincent
Published: February 2020

The increase in coercivity of materials composed of fine powders (10 nm to 100 nm) of important ferromagnetic materials, such as cobalt or iron, is well understood where the flux-closure configuration is energetically unfavorable[3].[4]. Thus, it is not too surprising that 1-D nanofiber structures of cobalt synthesized by electrospinning display enhanced coercivity over current bulk methods[1]. The exclusively high surface area-to-volume ratio of nanostructures and the rotation being opposed by the shape anisotropy of the demagnetization energy play a key role in achieving high coercivity[3]. Likewise, the synthesis method using electrospinning offers many advantages: ease of control over nanofiber dimensions, repeatability, scalability, and ease of assembly[2]. Electrospinning was used to fabricate nanofibrous cobalt structures by electrospinning a cobalt acetate (CoAc2)/poly (vinyl pyrrolidone) (PVP) composite solution followed by reduction in hydrogen environment. Two separate 2-level, full-factorial, design of experiments (DOEs) were conducted to control and optimize the process to minimize fiber diameter and eliminate beading defects. A 3-factor DOE was run on solution properties (viscosity, surface tension, electrical conductivity) and a 2-factor DOE was run on electrospinning parameters (voltage, flow rate). Solution viscosity was found to be the main factor in controlling fiber diameter. The high and low values in viscosity were achieved by changing both the molecular weight of PVP and the weight percentage of PVP in the solution. In the second DOE, the applied potential had a larger effect on fiber diameter than the flow rate. However, both were found to be significant factors and a balance between these two parameters is needed to prevent clogging of the needle as a function of evaporation rate. The as-spun nanofiber mats were subsequently annealed in pure H2 gas to produce pure cobalt nanofibers. Scanning electron microscopy (SEM), energy-dispersive x-ray spectroscopy (EDS), and X-ray powder diffraction (XRD) were all used to characterize fiber diameter, morphology, and crystal structure. The smallest, average, as-spun fiber diameter achieved was 126 nm with minimal beading. We will be investigating the magnetic properties of these cobalt nanofibers as a function of fiber size using a vibrating sample magnetometer.

References:

[1] - H. Wu et al., Chem. Mater. 19, 3506 (2007)

[2] - Ramakrishna S., Kazutoshi, F., Teo, W., Lim, T., Ma, Z., 2005, An Introduction to Electrospinning and Nanofibers, World Scientific Publishing Co., Singapore.

[3] Charles Kittel, Introduction to solid state physics, third edition, p. 495- 496

[4] L.Neel, Compt. Rend. 224, 1488(1947), C.Kittel, phys. Rev. 70, 965 (1946).
Hybrid Film Deposition for High-Aspect-Ratio Structures with Functional Surfaces
Authors: Kim Jeong Hwan , Lee Seong Woong , Yoon Jae-Sung , Yoo Yeong-Eun
Published: February 2020

Thin film deposition is one of the most significant issues in the fabrication of nano structures. Especially it is difficult to achieve conformal films on high-aspect ratio nanostructures, such as nanoholes and nanochannels. Though there are various thin film deposition processes, atomic layer deposition (ALD) has attracted due to its extreme surface conformality and excellent thickness controllability. Because ALD is a chemical gas phase thin film deposition method based on sequential and self-saturating surface reactions, it can be used for coating of nano structures with high-aspect ratio.

Sputtering process is one of the popular film deposition techniques due to its relative simplicity of process and fast deposition speed. However, film depositions by sputtering technique are less conformal compared to those by ALD, because of ions directionality sputtered by plasma. Therefore it is difficult to form films on the surfaces perpendicular to substrate by sputtering process.

However, if ALD and sputtering processes are combined, hybrid thin films deposition which different films are deposited on selectively different surfaces (eg. surfaces perpendicular and parallel to substrate).

In this poster, I will present the results of hybrid films deposition on nano holes/channels structures with high-aspect ratio. For different functionalities (hydrophilicity and hydrophobicity) of surfaces, Al2O3 and Pt films were grown on nanochannel structures. Al2O3 films deposition on the vertical surfaces (inner surfaces of nanochannels) was controlled precisely in nanometer scale by using ALD process. Pt films were formed on horizontal surfaces (outer surfaces of nanochannels) by using DC magnetron sputtering.
Carbon Materials Converted from PIM-1
Authors: Kim Byoung Gak , Jeon Jun Woo , Yoo Young Jae , Kim Yong Seok
Published: February 2020

As an effort to prepare carbon nanosheet and carbon film through catalyst- and transfer free process, several research groups have reported carbonization of polymers and small molecules such as polyacrylonitrile (PAN) and a small molecular pitch extracted from petroleum. Carbon nanosheets converted from PAN or pitch were obtained through two steps: cyclization and carbonization. Because the quality of the carbon materials sensitively depends on the cyclization conditions such as temperature, ramping rate, and oxygen contents, there is a great need for a cyclization-free process.

 Recently, we developed a cyclization-free carbonization process (one-step process) using PIM-1 (polymer of intrinsic microporosity). Various nano-structured PIM-1s were formed by using different methods such as electrospray, ultrasonic spray pyrolysis(USP), electrospining and spin coating methods, which were carbonized at 800~1200 oC without any catalyst. All carbonized PIM-1 maintained their original shape and their Raman spectra showed G graphitic carbon peak at 1590 cm-1 and D disordered carbon peak at 1330 cm-1. Especially, it is confirmed that carbonized PIM-1 prepared by spin coating had properties similar to graphene and could be used as the electrodes of ITO-free OSCs. Carbon nanosheets converted from PIM-1 showed a high efficiency of 1.922 % and electrical conductivity of 500 S/cm.

In this presentation, shape and dimension control of carbon materials and direct use as electrodes of organic solar cells and supercapacitors will be discussed more in detail.
H2TiO3 Composite Nanofibers for Lithium Recovery from Spent Lithium-Ion Secondary Batteries
Authors: Chung Wook-Jin , Nisola Grace Masbate , Lawagon Chosel Pepito , Gebreegziabher Hana , Albarico Jed , Lee Seong Poong
Published: February 2020

Lithium recovery attempts from spent lithium-ion batteries (LIBs) often employed complex methods utilizing toxic chemicals. In this study, a relatively facile and environmentally benign lithium recovery process was developed using H2TiO3 (HTO) as a highly selective lithium-ion adsorbent. This lithium ion sieve (LIS) has a chemically stable structure and remarkably higher theoretical Li+ capacity (126.47 mg/g) than manganese-based LIS. The low titanium dissolution of HTO upon acid pickling makes it an ideal LIS for lithium recovery. However, in its powder form, HTO application in actual systems is limited due to difficulty in its handling. The HTO particles must be incorporated in a suitable support for its feasible utilization. Herein, electrospun nanofibers with unique dimensional properties were utilized to serve as three-dimensional frameworks for HTO.

Different types of polymeric (PAN, PSf, PVC, and PVDF) nanofibers with varied HTO loading were prepared by electrospinning method. The composite nanofibers were characterized by SEM, UTM mechanical test and applied for lithium adsorption. It was determined that PAN composite nanofibers with 100 wt.% HTO loading showed the highest adsorption capacity (31.4 mg g-1) and superior mechanical property. It retained up to 93.6% of the adsorption capacity of the pure H2TiO3 powder (33.6 mg g-1). The PAN-HTO nanofiber was then employed to recover Li+ from spent LIBs. The spent batteries were dismantled and sonicated in deionized water to elute Li+ from the waste. The resulting solution was then filtered through the PAN-HTO nanofiber membrane to capture the Li+. The captured Li+ were easily retrieved by mild acid treatment of the spent PAN-HTO nanofiber, which was also regenerated for reuse. Overall, the results of the study showed the feasibility of using PAN-HTO nanofiber for continuous and efficient recovery of lithium ions from spent LIBs. This research was supported by Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Education (2009-0093816) and Ministry of Science, ICT and future Planning (2015R1A2A1A15055407).
Characteristics of SrxY1-XTiyNi1-YO3-d anode in Humidified Methane Fuel for Intermediate-Temperature Solid Oxide Fuel Cells
Authors: Yun Jeong Woo , Park Eun Kyung
Published: February 2020

Solid oxide fuel cells (SOFCs) are a promising alternative energy conversion device because of high energy efficiency and fuel flexibility. Nickel/yttria-stabilized zirconia (Ni/YSZ) cermet has been widely used as an anode material in SOFCs. The Ni/YSZ anode, however, may not be appropriated for direct use of commercial hydrocarbon fuels because of carbon deposition and sulfur poisoning on the Ni phase.

In this study, yttrium and nickel co-doped strontium titanium oxide SrxY1-xTiyNi1-yO3-δ (SYTN) was investigated as an alternative anode material for SOFCs. To improve the ionic conductivity of the Sr0.92Y0.08TiO3-δ (SYT) anode, Ti4+ at the B-site was substituted to Ni2+, leading to introduction of oxygen vacancies in the SYT. The stability of the SYTN anode at high temperatures and reducing atmospheric conditions was as good as the SYT anode. The SYTN exhibits excellent phase stability during the cell fabrication processes, SOFC operation, and good electrical conductivity at 700~900 oC in methane. The SYTN anode was compatible with YSZ at the SOFC operating condition. The electrochemical reactions of the SYT anode in both hydrogen and methane were limited by relatively slow reactions, such as non-charged processes including oxygen surface exchange and solid surface diffusion. To improve such poor electrochemical activities, the surface of the SYTN anode was modified by the SDC coating. The polarization resistance and the cell performance in hydrogen and methane were significantly improved by the SDC modification. The SDC-coated SYT anode cell was successfully operated with methane for more than 300 hours without any degradation of the cell performance.
The Effect of the Amount of Intercalated Li-Ions on the Electrochemical Performances and the Color Changes in the Electrochromic Layer
Authors: Han Taeyeong , Lee Hoogil , Kim Seokwoo , Ryou Myung-Hyun , Lee Yong Min
Published: February 2020

Global warming and the energy crisis have been accelerated the necessity to develop the energy saving system and to increase energy efficiency are for many researchers. For instance, smart window consisting of glass, electrochromic layer, and electrolyte is one of the promising candidates to fulfill this goal. The color change of this smart window should be delicately controlled responding to the capriciousexternal environment condition. Although many researchers have been mainly focused on the physical properties of active materials such as crystalline and morphological structures to modulate optical density of the smart window[1,2], the color difference of smart window according to amount of intercalated Li-ions in electrochromic layer has never been considered thus far.

Hence, we investigated the effects of the color changes of electrochromic layer corresponding to the different amount of intercalated Li-ions. We employed three-electrode type unit cells consisting of working electrode (WO3/ITO), reference electrode (Ag/AgCl with 3M KCl), counter electrode (Pt) and electrolyte (1M LiClO4 in PC) throughout this study. We monitored the correlation between the voltage changes and the transmittance of electrochromic devices as applying a constant current as a function of the amount of the intercalated Li-ion. Furthermore, the crystalline structure of active materials was also investigated using an X-ray diffraction (XRD) technique.

Acknowledgements

This work was supported by the *Energy Technology Program of the Korea Institute of Energy Technology Evaluation and Planning(KETEP) granted financial resource from the Ministry of Trade, Industry & Energy, Republic of Korea (No. 20142010102980)

References

[1] Christopher S. Blackman and Ivan P. Parkin, Chem. Mater. 2005, 17, 1583-1590

[2] By Se-Hee Lee, Rohit Deshpande, Phil A. Parilla, Kim M. Jones, Bobby To, A. Harv Mahan,

and Anne C. Dillon, Adv. Mater. 2006, 18, 763–766
Crystalline Cd3As2
Authors: Kouklin Nikolai , Hosseini Tahereh , Yavarishad Niloufar
Published: February 2020

Thermo-electric generators (TEGs) directly convert thermal into electrical energy and are the prime candidates for application in low-grade thermal energy/heat waste recovery. TEGs possess several critical advantages as they remain silent, highly reliable and lightweight, which make them uniquely suited for niche deployments in transportation, space satellites, electronics cooling and thermo-voltaic cells. With the efficiency in a few percent range, the efficiency-to-cost ratio remains poor, with the bottleneck traced back to the thermo-electric (TE) materials. PbTe and Bi2Te3, two key TE materials that are in commercial operation, have room temperature ZT of less than 1, whereas ZT exceeding 3 is required for a TEG to be economically viable.

Until recently, the enhancement of ZT was mainly attained by introducing phonon scattering interfaces and rattling centers to slow heat transport. With thermal conductivity already approaching the fundamental limit of amorphous materials, further gain in ZT can be only realized by improving the thermo-electric power factor, S2, typically via costly band structure engineering or by means of quantum confinement.

In this work, we instead focus on Cd3As2, a high performance 3D Dirac semimetal. Compared to other semimetals, Cd3As2 possess Dirac fermions that disperse linearly in k3-space and in turn, one of the largest electron mobilities known for crystalline materials, i.e. ~104-105cm2V-1s-1. The carrier back-scattering remains suppressed and the electrical transport is dominated by high-energy carriers that favorably affect the thermopower of Cd3As2. Since the power factor scales with the carrier mobility, μ, and weighted density-of-states effective mass, i.e. S2 ~ μ, and the lattice thermal conductivity is within amorphous limit for this material, Cd3As2 shows a strong potential for demonstrating high, device-favorable S and in turn ZT.

A reduced temperature vapor-based crystallization pathway was developed to produce free standing, stochiometric 2D cm-size crystals in Cd3As2. In contrast to previous findings, the Seebeck coefficient is seen to initially rise linearly with T to reach a peak within ~ 300-400 K range which is followed by a decline with the shift in the trend attributed to the increase in the role of the ambipolar heat transfer as temperature increases.The primary mechanism of the minority carrier generation in our samples is attributed to phonon-assisted interband electronic transitions involving E and A1 bands. Possessing a very high room-temperature thermopowers of ~613 uV/K and amorphous limit thermal conductivity, bulk Cd3As2 is identified as another high promise phonon-glass electron-crystal TE material for development of next generation a high efficiency thermo-electric generators and refrigerators operating under normal conditions.

Figure 1
Battery Reliability, Safety, and Failure Modes and Effects Analysis
Authors: Liaw Bor Yann
Published: February 2020

On the subject of battery safety, current ability in the industry to deal with safety hazards in any incidents is based on empirical experiences patched up with specific solutions. Such a solution is not systematic (i.e. case-by-case), thus often costly and conflicting with the desire for better battery performance due to the restrictive nature of the solution (i.e. trade-offs between safety constraints and performance limits). Even worse, these solutions do not provide a systematic approach and accumulative engineering expertise to allow a more sustainable pathway to solve any future encountered issues efficiently and effectively. There is little emphasis on the inter-relationships among battery variability, durability, reliability, and safety. A more resilient approach such as failure modes and effects analysis (FMEA) to address these issues is not often discussed in such a broad basis of interrelationships. Most of the literature does not consider these issues in a coherent and consistent framework to find a common solution. Such a lack of recognition of these interrelationships may be the largest technical barrier to prevent the advent of battery technology to provide a reliable battery system for electrification of transportation and modernization of infrastructure in a modern electrical grid. Finding better materials and battery cell designs is not sufficient to make the battery products viable in the market place. We might not have realized that FMEA is the prevailing approach to make battery durable, reliable, and safe, just like it has helped the aviation and other industry to succeed in providing the services to our daily life.

In this presentation, emphasis on this thought process will be discussed and explained and the usefulness of failure modes and effects analyses and a feasible approach will be proposed with a few preliminary illustrations demonstrated. The author would like to bring the research community to pay attention to this need and using this symposium as a platform to pave the way for future consensus on how to address battery safety issues with increasing ability from the research capability to enhance battery durability, reliability and ability to address abuse tolerance in battery systems.
Quantifying the Effect of Lithium-Ion Electrode Manufacturing Defects on Electrochemical Performance
Authors: David Lamuel , Kalnaus Sergiy , Mohanty Debasish , Sheng Yangping , Li Jianlin , Daniel Claus , Wood David L
Published: February 2020

Understanding the effect of electrode manufacturing defects on lithium-ion battery (LIB) performance is key to reduce the scrap rate. In this regard, it is vital to quantify the effect of various defects that are generated during electrode coating process (Layered NMC532 cathode in this study) on LIB performance. Previously, we have shown the comparative effects of different defect types such as agglomeration, pinholes, metal particle contamination and non-uniform coating on LIB performance in full coin cells.1 In this study, we have quantified the effect of these defects in 1.5 Ah pouch cells in order to investigate the effect in pilot-scale LIB format(s). The results showed that the electrodes with more coated/non coated interfaces had faster capacity fade than baseline electrodes at high current densities. Pouch cells with electrode agglomerates and pinholes were also fabricated and a comparative study was performed. In order to further validate our latest experimental findings, we have adopted mathematical simulation methods to explore the effects of microstructural inhomogeneities on cell electrochemistry. The conclusions from this study provide the importance of monitoring and early detection of the electrode defects during the coating process to minimize cell rejection rates prior to fabrication and formation cycling.
(Invited) Hybrid Supercapacitors: Their Evolution to Second and Third Generations
Authors: Naoi Katsuhiko , Naoi Wako
Published: February 2020

To meet growing demands for electric automotive and regenerative energy storage applications, researchers all over the world have sought to increase the energy density of electrochemical capacitors. Hybridizing battery capacitor electrodes can overcome the energy density limitation of the conventional electrochemical capacitors because they employ both the system of a battery-like (redox) and a capacitor-like (double-layer) electrode, producing a larger working voltage and capacitance. However, to balance such asymmetric systems, the rates for the redox portion must be substantially increased to the levels of double-layer process, which presents a significant challenge. An in situ material processing technology called “ultracentrifugation (UC)” has been used to prepare a novel ultrafast Li4Ti5O12 (LTO) nanocrystal electrode for capacitive energy storage.

The present paper describes an extremely high-performance supercapacitor that utilizes highly optimized “nano-nano-LTO/carbon composites” prepared via the UC treatment. The UC-treated LTO nanocrystals are grown as either nanosheets or nanoparticles, and both have hyperlinks to two types of nanocarbons: carbon nanofibers and supergrowth (single-walled) carbon nanotubes. Using this ultrafast material, we assembled a hybrid device called a “nanohybrid capacitor” that consists of a Li-intercalating LTO electrode and a non-Faradaic AC electrode employing an anion adsorption desorption process. The “nanohybrid capacitor” cell has demonstrated remarkable energy, power, and cycleability performance as an electrochemical capacitor electrode.

The new-generation “nanohybrid capacitor” technology produced more than triple the energy density of a conventional electrochemical capacitor. Moreover, the synthetic simplicity of the high-performance nanostructures makes it possible to scale them up for large-volume material production and further applications in many other electrochemical energy storage devices.

References

[1] K. Naoi, Fuel Cells, 10, 825 (2010), [2] K. Hata, D.N. Futaba, K. Mizuno, T. Namai, M. Yumura, S. Iijima, Science, 306, 1362 (2004), [3] K. Naoi, S. Ishimoto, J. Miyamoto, W. Naoi, Energy & Environmental Science, 5, 9363 (2012), [4] K. Naoi, W. Naoi, S. Aoyagi, J. Miyamoto, T. Kamino, Accounts Chemical Research, 46,1075(2013).
Aqueous-Based Polymer Electrolytes for Solid Energy Storage Systems
Authors: Lian Keryn , Li Jak , Virya Alvin , Foong Yee Wei , Wu Haoran , Gao Han
Published: February 2020

The rapid growth in printable and wearable electronics has significantly increased the demand for high performance thin, flexible, and light-weight power sources. Solid-state energy storage devices, batteries and supercapacitors, enabled by polymer electrolytes are ideal solutions for such applications. In order to facilitate and promote high throughput and low cost (materials and processes) solid energy storage devices for wearable electronics, the polymer electrolytes should be highly conductive, easy to process, and possess good chemical and environmental stability in ambient conditions.

We have developed a series of aqueous-based polymer electrolytes that are proton-conducting, hydroxide ion-conducting or neutral salt ion-conducting to match various cell chemistries. These aqueous-based polymer electrolytes can be applied via casting or printing methods and can potentially be implemented in roll-to-roll operations. One example is the polyacrylamide (PAM) system, in which ionic conducting species together with additives were blended into aqueous polymer matrix. In this work, three ionic conducting systems based on silicotungstic acid (SiWA) as proton-conductor [1], tetraethylammonium hydroxide (TEAOH) as anion conductor [2] and LiCl as neutral ion conductor were investigated. These three electrolytes all exhibited ionic conductivities > 10-2mS/cm and maintained stable performance under ambient conditions (room temperature and 45% relative humidity). Figure 1 shows a comparison of these 3 polymer electrolytes in terms of their ionic conductivity as a function of storage time. In this talk, an overview of these three polymer electrolytes will be provided. Materials and electrochemical characterizations of the polymer electrolytes as well as their performance in electrochemical double layer capacitors will be discussed and compared.

References:

[1] H. Gao and K. Lian, "Proton-Conducting Polymer Electrolytes and Their Applications in Solid Supercapacitors: A Review", RSC Advances, 2014, 4, 33091-33113.

[2] H. Gao, J. Li, and K. Lian, "Alkaline Quaternary Ammonium Hydroxides and their Polymer Electrolytes for Electrochemical Capacitors", RSC Advances, 2014, 4, 21332-21339.

Figure 1
Electrochemical Characteristics of Graphite Felt Electrode By Surface Modification for Vrfbs
Authors: Noh Tae-Hyoung , Kim Min-Young , Lee Moo-Sung , Park Hong-Sik , Kim Ho-Sung
Published: February 2020

Recently, there has been a lot of research in vanadium redox flow battery (VRFB) which is used as a large scale energy storage system and power supplier. Especially, graphite electrodes play an important role because they do directly act as electrochemical reaction in cell. In this study, commercial graphite felts were prepared by heat treatment in the range of 400 to 600 °C, controlling the condition of heat treatment such as air purity, heating processing time. As a result, the surface morphology and oxide of electrode were observed by SEM and XPS. Moreover, electrochemical evaluations such as CV (Cyclic Voltammetry) and impedance were performed in three electrode cell at room temperature, in which the kinetic properties of electrode were different with the condition of surface modification. Furthermore, small VRFB full cells constructed with the graphite felt showed the properties of charge and discharge profile corresponding to the above analysis and electrochemical test. Therefore, we will introduce the effect of heat treatment on the graphite felt electrode and its correlation in electrochemical reaction in more detail.
The Role of Lithium Superoxide in Li-O2 Batteries
Authors: Curtiss Larry
Published: February 2020

There has been much interest in rechargeable aprotic lithium-oxygen (Li-O2) batteries because their energy density can be significantly higher than that of the conventional Li-ion batteries. However, many challenges remain for Li-O2 batteries before they can become a reality.  Understanding the growth and nucleation mechanisms of the discharge product is one of the keys to addressing these challenges because it controls the resulting morphology and composition of the discharge product. The efficiency and reversibility are dependent on the type of morphology and composition that is formed during discharge. In this paper experimental and computational results will be reported that have shed light on the growth and nucleation mechanism in Li-O2 batteries. Specifically, the role of lithium superoxide (LiO2) in the nucleation and growth mechanism during discharge and how to suppress the disproportionation reaction of LiO2 to lithium peroxide (Li2O2) will be discussed. The implications of these new results for reducing charge overpotentials in Li-O2 batteries and in the design of new cathode materials will be discussed.
Making the Invisible Visible - Advanced Diagnosis Methods for Lithium Ion Rechargeable Battery Materials
Authors: Meng Ying Shirley
Published: February 2020

Scanning electron microscopy and electron energy loss spectroscopy (STEM/EELS) offers unprecedented spatial resolution, which has enabled nanoscale imaging and chemical analysis of battery materials - their surfaces, grain boundaries and phase boundaries. Combining the state-of-the-art in situ operando analytical electron microscopy with first principles (FP) computational data analysis, we reveal some insights that could not be possible to see in the past.  On the other hand coherent x-ray diffractive imaging (CXDI), a lensless form of microscopy capable of discerning electron density and strain with 20 nm resolution, can be used to map the strain evolution of a single cathode particle in a functional battery material as it is cycled in-situ. The evolution of compressive/tensile strain reveals a number of interesting phenomena. For instance, strain can be quantitatively correlated to the Lithium amount in the initial cycles, eventually becoming uncorrelated upon long-term cycling. We demonstrate that CXDI is a powerful diagnostic tool to reveal correlation between strain and electrochemistry at the single particle level and offers valuable information for electrode/battery modeling and future battery design. By combining electron based and X-ray based novel imaging techniques, we showcase the state-of-the-art diagnostic tools developed for probing functional battery materials in operando.
Electrolytes for Li-Ion Batteries: Limitations, Challenges and Opportunities
Authors: Cekic-Laskovic Isidora , Nowak Sascha , Schappacher Falko , Winter Martin
Published: February 2020

Although lithium ion batteries are considered as system of choice for variety of mobile and stationary applications, fundamental knowledge is alarmingly required to uncover the underlying principles controlling the basic processes that determine and dictate their function, operation, performance limitations as well as failure. In this underpinning way, considerable improvements and new concepts in respect to the stable electrode active materials and electrolyte formulations can be achieved leading to electrochemical systems with long life, high energy density, high power and adequate safety at a competitive manufacturing cost. Due to the complexity of electrolyte formulation, determined by the physicochemical properties of its components, namely inorganic fluorinated salts, organic solvents and additives, the desired operation performance is always accompanied by inevitable side reactions. Recent advances in selected ex situ, online and in situ techniques, combined with theoretical approach, outline and provide deeper insight into the dynamic, complex and not well-understood cell chemistry. In this mechanistic game, victory is assured to those who are best able to piece together conclusions obtained from synthetic, structural, kinetic, spectroscopic as well as electrochemical studies and construct the mechanism capable of explaining the results. Thorough investigation and elucidation of those fundamental, mechanisms including chemical, physical, electrochemical and interfacial processes guide and strengthen the further advancement of the existing state of the art Li ion batteries and stimulate development of the next generation rechargeable batteries.

Since an electrolyte has a complex starting composition, analytical and electrochemical techniques have to be developed and applied for the numerous individual species that are present in the system. By means of developed analysis methods, decomposition products can be evaluated to determine operation and failure mechanisms as depicted in Figure 1.

Figure 1
Operando Diffraction During Li Battery Operation Using Neutron and Synchrotron X-Ray Radiations
Authors: Masquelier Christian , Bianchini Matteo , Suard Emmanuelle , Fauth François , Croguennec Laurence
Published: February 2020

Performing in situ and operando measurements on electrode materials for Li-ion and Na-ion batteries is of importance for their understanding and improvement. Electrode materials need to be studied in their environment (in situ) and in real time while they function (operando), since they normally operate in non-equilibrium conditions. Real-time experiments upon charge/discharge of the electrodes (i.e. upon lithium or sodium extraction/insertion from/into the electrodes) unveil dynamics that are not accessible by other means and allow a more complete understanding of the electrodes’ functioning. The use of different probes is an important requirement for the study of such reactions. The combined use of X-Ray Powder Diffraction (XRPD), Synchrotron radiation XRPD and Neutrons Powder Diffraction (NPD) allows observing any atomic element in any crystalline electrode. However, custom setups are required to carry out operandodiffraction experiments on batteries.

We will address the development of a sample environment suitable for both electrochemistry and neutron powder diffraction using an electrochemical cell featuring a (Ti,Zr) alloy and a deuterated version of the electrolyte [1]. The cell is able to function using massive electrodes (massive on the battery scale, but a small sample for neutrons) with good performances and able to give NPD patterns of high quality for data analysis. Importantly, we showed the possibility to succeed in reliable structural refinements (by the Rietveld method) and thus to observe structural modifications in details, from unit cell parameters to atomic coordinates and even site occupancy factors. We will discuss a few studies done with this setup, namely the observation of lithium extraction from different samples in the family of spinels Li1+xMn2-xO4. We performed NPD in real time on three samples (LiMn2O4, Li1.05Mn1.95O4 and Li1.10Mn1.90O4) and showed how the Li/Mn ratio influences the phase diagram of the material [2]. New insights obtained from high resolution – high flux Synchrotron X-Ray diffraction data will be presented, in particular the existence of a Li+ and Mn3+/Mn4+ ordering within the spinel-delithiated composition Li0.5Mn2O4[3].

Acknowledgements

This research is performed in the frame of the French network RS2E (http://www.energie-rs2e.com) and of the European network ALISTORE-ERI (http://www.alistore.eu).

References

[1] Bianchini et al., J. Electrochem. Soc., 160(11), A2176-A2183 (2013)

[2] Bianchini et al., J. Phys. Chem. C, 118(45), 25947-25955 (2014)

[3] Bianchini et al., Acta Cryst., B71, 688-701 (2015)
Next Generation Battery Technologies based on Reversible Lithium Metal Electrodes
Authors: Visco Steven J.
Published: February 2020

In the late 1980’s a number of companies were attempting to commercialize rechargeable lithium metal batteries. Unfortunately these batteries were plagued by safety problems associated with the stripping and plating of lithium metal in liquid electrolytes. This was followed in 1991 by the highly successful commercial launch of Li-ion batteries by Sony. Although Li-ion battery technology has seen steady incremental improvements since that time, the market demand for a disruptive battery technology is undeniable. Accordingly, over the past few decades there have been significant investments in R&D targeted at next generation batteries. In this presentation we will address strategies for realizing this goal through introduction of reversible lithium metal electrodes.
Understanding the Anomalously High Capacity of Li- and Mn-Rich Cathodes for Li-Ion Batteries
Authors: Yoon Won-Sub
Published: February 2020

The reaction mechanism of a high capacity lithium- and manganese-rich metal oxide has been investigated. High-resolution synchrotron X-ray powder diffraction (HRPD) and X-ray absorption spectroscopy (XAS) were used, respectively, to evaluate the electrochemical charge and discharge reactions in terms of local and bulk structural changes, and variations in the oxidation states of the transition metal ions. Ni K-edge XAS data indicate the participation of nickel in reversible redox reactions, whereas Mn K-edge absorption spectra show that the manganese ions do not participate in the electrochemical reactions. Rietveld refinements of the oxygen occupancy during charge and discharge provide evidence of reversible oxygen contribution by the host structure; this unique oxygen participation is likely the main reason for the anomalously high capacity of these electrodes. The HRPD data also show that during the early cycles, characteristic peaks of the Li2MnO3 component disappear when charged to 4.7 V, but reappear on discharge to 2.5 V, consistent with a reversible lithium and oxygen extraction process. The results provide new insights into the charge compensation mechanisms that occur when high capacity, lithium- and manganese-rich electrode materials are electrochemically cycled – a topic that is currently being hotly debated in the literature.
Advanced Cathode Material with Full Concentration Gradient for High Energy Density Lithium- and Sodium-ion Batteries
Authors: Sun Yang-Kook
Published: February 2020

Rechargeable lithium- and sodium-ion batteries have great potential as a new large-scale power source for electric vehicles (EVs) and energy storage system due to their high energy density, high voltage, and long cycle life. However, commercialization of these batteries for the automobile and energy storage industries requires further improvements in energy density and safety. Here, we report a novel cathode material with concentration gradient of Ni, Co, and Mn ions throughout each secondary particle where the nickel concentration decreases linearly whereas the manganese concentration increases linearly from the centre to the outer layer of each particle. Using this functional full-gradient approach, we are able to harness the high energy density of the nickel-rich core and the high thermal stability and long life of the manganese-rich outer layers.
Materials Design for Battery Anodes: Silicon, Lithium Metal and Phosphorus
Authors: Cui Yi
Published: February 2020

Applications of energy storage in transportation and grid scale call for next generation of batteries with high energy, high power, long cycle life, good safety and low cost. In this talk, I will show how we design rationally materials at the nanoscale for next generation of battery anodes. Examples include 1) high capacity nanostructured Si anodes with stable SEI formation; 2) interfacial materials design and additive effects for lithium metal; 3) red and black phosphorus for lithium and sodium ion storage.
Ecologically Friendly Recycling of Lithium-Ion Batteries - the Lithorec Process
Authors: Kwade Arno , Diekmann Jan , Hanisch Christian
Published: February 2020

The increasing demand of lithium-ion batteries requires the recovery of active materials from spent lithium-ion batteries and production rejects in order to prevent a future shortage of lithium and other valuable raw materials. In contrast to existing recycling processes, the main goal of the LithoRec process is to achieve a high recycling yield and a low ecological impact as well as to efficiently recover all battery materials at battery grade quality. The project spams the entire recycling process starting from the discharging and disassembly stages, and following through with mechanical, chemical and thermal processing (e.g. crushing, grinding, classification, sorting, and extraction) used to separate the battery into recyclable fractions. In order to match the high purity standards of hydro-metallurgical processes for the production of battery active materials, the battery active materials have to be separated from the current collector foil very purely. For that purpose, a new patented separation process has been developed which shows a very high separation rate at high purity. The entire process was set up in pilot scale and operated with different spent battery systems. Results of this pilot trials will be discussed in the paper. Subsequently, new battery active materials have been produced and characterized in battery test cells.
New Polyimides As Electrode Materials for Li-Ion Batteries
Authors: Hernández Guiomar , Morozova Sofia M. , Shaplov Alexander S. , Lozinskaya Elena I. , Vygodskii Yakov S. , Shanmukaraj Devaraj , Armand Michel , Mecerreyes David
Published: February 2020

Currently, Li-ion batteries are based on inorganic oxides as cathodes, although they fail in terms of safety and sustainability. Recently redox-active polymers have attracted considerable attention as an alternative to inorganic cathode materials due to their low solubility in common electrolytes, film forming ability, excellent thermal stability and tunable redox properties. Among redox polymers, polyimides (PIs) are known for their ability to undergo reversible electrochemical reduction/oxidation as well as for offering high capacities.

To extensively explore the influence of chemical structure on the electrochemical properties of polymers a series of PIs based on three aromatic dianhydrides and various diamines incorporating ether segments, ionic fragments and additional lactone cycle were synthesized (Fig. 1). The expected improvement in the performance of the cells based on ionic PIs through the additional solvation of Li+ by ionic fragments was not reached feasibly because of the electrostatic repulsion effect. In contrast, the insertion of short ether moieties in PI’s backbone allows for the desired Li+ solvation, increase of their mobility and rise in the batteries capacity. Among synthesized series, PIs derived from 1,4,5,8-naphthalene tetracarboxylic acid dianhydride and 4,7,10-trioxa-1,13-tridecanediamine showed best battery performance: excellent charge/discharge efficiency, high specific capacity (up to 140 mAh g-1) and the capability to reversibly operate at relatively high rates (up to C/5).

This work was supported by the Russian Foundation for Basic Research (projects no. 14-29-04039_ofi_m and 16-03-00768_a) and by European Commission (project no. 318873 «IONRUN»). Electrochemical experiments were run at CIC Energigune through a collaboration with Polymat.

Figure 1