bluuebunny/crossref_metadata_2025_split huggingface dataset:
Electrical Explosion Synthesis of Si/C Nanocomposites for Li Secondary Batteries
Authors: Kim Doohun , Ha Yoon-Cheol , Cho Chuhyun , Doh Chil-Hoon 
Published: February 2020

A novel technique of electrical explosion has been used for nanomaterial synthesis by a single-step process [1-5]. However, it was known that in principle the electrical explosion of Si is not possible due to the fact that applying a high voltage on Si wire having relatively high electrical resistance leads to a current flow through surface plasma formed along the wire which disables the resistive heating of Si. In this presentation, we will show the successful application of electrical explosion to silicon nanoparticle synthesis and the electrochemical properties of Si/C nanocomposites derived from the nanoparticles.
The electrical explosion of Si was successfully applied using a liquid media to suppress the unfavorable surface plasma generation. The physical and chemical properties of the produced materials were analyzed by XRD, FE-SEM, HR-TEM and the performances of the Si/C composites as an anode for Li ion batteries were investigated by electrochemical charge/discharge measurements. The Si/C composites obtained under the explosion in hexane and ethanol consist of a core-shell structure with a compact graphitic carbon on the Si particle surface which cause detrimental effects against Li ion diffusion. However, we found that Si explosion in methanol minimized the formation of the carbon phase on the surface of nano-sized Si. The Si/C nanocomposite after a simple pyrolysis with carbon precursor showed a high capacity with an excellent cycle performance.
References

[1] Cho, C., Choi, Y.W., Kang, C., Lee, G.W. Effects of the medium on synthesis of nanopowders by wire explosion process (2007) Applied Physics Letters, 91 (14), p. 141501.
[2] Cho, C., Ha, Y.-C., Kang, C., Jin, Y.-S., Rim, G.-H. Preparation of a nickel nanopowder by wire explosion in liquid media (2010) Journal of the Korean Physical Society, 57 (61), pp. 1807-1810.
[3] Ha, Y.-C., Cho, C. Production of highly-dispersed nano-sized Sn powders in a liquid medium by using a high-energy electrical explosion (2010) Journal of the Korean Physical Society, 57 (61), pp. 1574-1576.
[4] Cho, C., Ha, Y.-C., Kang, C., Jin, Y.-S., Rim, G.-H. Electrical explosion of silicon rod in distilled water (2011) Japanese Journal of Applied Physics, 50 (10 PART 1).
[5] Ha, Y.-C., Kang, C., Cho, C., Kim, Y.-U., Park, C.-M., Sohn, H.-J. Wire explosion synthesis of a Sn/C nanocomposite as an anode material for Li secondary batteries (2011) Journal of the Korean Physical Society, 59 (61), pp. 3458-3462.
Modeling of the Thermal Behavior of an Ultracapacitor
Authors: Kim Changmin , YI Jaeshin , Lee Jeongbin , Shin Chee Burm , Min Kyung-Seok , Lee Ha-Young 
Published: February 2020

Ultracapacitors, also known as supercapacitors, have the potential to meet the increasing power requirements of energy-storage systems for automotive applications. As compared to batteries, ultracapacitors offer a higher power density, higher efficiency, and longer shelf and cycle life. Because the performance of an ultracapacitor depends on temperature, it is important to calculate accurately the thermal behavior of an ultracapacitor for the efficient and reliable systems integration in automotive applications.
In this work, modeling is performed to study the thermal behavior of 2.7V/650F ultracapacitor from LS Mtron Ltd. The validation of the modeling approach is provided through the comparison of the modeling results with the experimental measurements.
In Fig. 1, the variation of surface temperature with time from the experiment during the charge-discharge cycles with constant current of 180 A is compared with that from modeling. Fig. 2 shows the comparison between the surface temperature distributions based on the experimental IR image and the modeling after 30 min during cycles. Model predictions reasonably reproduce the experimental data.
Combination of Electrochemical-Calorimetric Studies on Cylindrical Lithium Ion Cells and Thermal Modelling By Comsol Multiphysics Software
Authors: Ziebert Carlos , Ossipova Anna , Rohde Magnus , Seifert Hans Jürgen 
Published: February 2020

In this study, commercial cylindrical 18650 lithium ion cells with LiMn2O4 (LMO) cathodes were tested under isoperibolic and adiabatic conditions in an accelerating rate calorimeter (ES-ARC, Thermal Hazard technology with integrated battery cycler) to investigate the heat effects during cycling in more details. These experimental results were compared with simulations by FEM-based thermal modeling using COMSOL Multiphysics software.
The isoperibolic investigations were performed at specific temperatures in the range from 25 to 60 °C. The results show that the applied environmental temperature did not largely influence the battery thermal behavior. Generally, an overall exothermic behavior for discharging half cycles and an overall endothermic behavior for charging half cycles was observed. At 1 C rate the maximum temperature increase over three cycles was 4 °C almost independent of the environmental temperature. Additionally, the heat capacity and calorimeter constant were measured after calibration using cylindrical dummy cells made of AlMgSi0.5 (EN AW-6060 F22) with the same dimensions as the cells. By integrating over the heat dissipation rate and the enthalpy accumulation rate the total generated heat was determined ion dependence of discharge C-rate. Tests under adiabatic conditions, i.e. under negligible heat loss, more accurately simulate the actual operating environment if several cells are put in a battery pack and the neighboring cells hinder or prevent the heat transfer to the ambient. The cells were studied in the adiabatic mode at starting temperatures between 20 °C and 40 °C. The cell temperature was largely increasing at 1 C rate over three cycles by more than 40 °C rate before reaching the safety limit temperature of 75 °C.
For the modeling of the cells the existing lithium ion battery model in COSMOL Multiphysics was combined with the coupled thermal and electrochemical 2D-model proposed in [1]. As input data the available experimental cell data, cycling parameters and literature data have been used. A good qualitative agreement between the experimental and the simulation results was found both for isoperibolic and adiabatic conditions.
The next step will be the assignment of the heat effects found both in simulation and experiments to electrochemical processes and the different cell components. This could be done by separating the heat effects into reversible and irreversible parts and fitting their ratio in the simulation to the experiment. An improved understanding of the heat effects will help to improve the thermal management of the cells and prevent from thermal runaway.
[1] L. Cai, R.E. White, Journal of Power Sources 196 (2011) 5985-5989.
Non-Uniformity Behaviors of Commercial Large-Format Batteries: Performance and Durability
Authors: Bi Wu , Fau Christian , Feng Zhili , Ren Yang , An Ke 
Published: February 2020

Coin cells and small pouch cells are commonly fabricated in laboratory to study performance and degradation mechanisms of battery materials. However, for real world applications such as hybrid electric vehicles large-format Li-ion based batteries are used currently. Performance, durability, and safety are more complex in these large-format batteries than in small ones. For example, temperature spatial profile can be significantly varied in large-format batteries during high-rate charging and discharging periods. In addition, non-uniform battery material distribution, small local defects, and inappropriate cell assembly designs may magnify the non-homogeneous behaviors in large-format batteries. Better understanding of large-format commercial batteries is essential to ensure safety and performance reliability.
Both in-situ and ex-situ techniques utilizing synchrotron X-ray diffraction and Neutron diffraction are being developed at Argonne National Laboratory and Oak Ridge National Laboratory, respectively. Under various operating conditions, 3-D profiles of temperature, internal stress, and electrode SOC% can be collected on large-format Li-ion based prismatic cells. Both techniques, complementary to each other, will be briefly described. We will focus on discussing non-uniformity behaviors of local battery performance and changes of local material structure and chemistry before and after storage tests and charge-discharge cycles. These results will be correlated to the diffraction data, to understand the effects of non-uniform profiles of temperature, internal stress, and electrode SOC% on battery life-time durability. Important implications on battery quality, safety, and controls will also be mentioned.

Acknowledgement

This project is partially funded by US-CHINA Clean Energy Research Center (CERC)-Clean Vehicles Consortium.
Molten Air - a New Class of Rechargeable Batteries
Authors: Stuart Jessica , Lau Jason , Cui Baochen , Licht Stuart 
Published: February 2020

A new class of high-energy batteries, the molten air battery, is presented. These batteries use a molten electrolyte, are quasi-reversible (rechargeable), and have amongst the highest intrinsic battery storage capacities available.
In today’s society there exists a need for higher energy capacity, cost effective batteries for a range of electronic, transportation and large-scale power storage devices. The molten air battery overcomes these problems. For example, these batteries address the “range anxiety” of electric vehicles as a result of energy density limitations, and offer increased energy storage capacity for the electric grid.
The electron charge transfer chemistry of the molten air battery is demonstrated through three examples. These examples utilize metal, carbon and vanadium diboride as reactive material each containing the respective intrinsic volumetric energy capacities of 10,000 Wh liter-1 for Fe to Fe(III), 19,000 Wh liter-1 for C to CO2
- and 27,000 Wh liter-1 for VB2 to B2O3 + V2O5, compared to 6,200 Wh liter-1 for the lithium air battery.
The Effect of SnO2-Sb Interlayer on the Physicochemical Properties of Electrodeposited Ti/PbO2 Electrodes
Authors: Bi Hailian , Yu Changzhou , Cao Peng 
Published: February 2020

Lead dioxide (PbO2) coated titanium (Ti) anodes have been extensively investigated owing to its well-proven advantages such as low cost compared to those based on precious metals, good electrical conductivity that is comparable to metals, ease of preparation, high oxygen evolution potential and good stability in corrosive media [1]. However, traditional PbO2 deposited Ti electrodes suffer from poor adhesion problem, due to the formation of an insulating TiO2 between the coating and Ti substrate during anodic polarization in aqueous media. SnO2, as an interlayer, has been recently applied on Ti substrate to prepare PbO2anodes to improve the stability and electro-catalytic activity. The application of such doped interlayer is reported to have increased electrode’s chemical stability, enhanced electro-catalytic activity and greatly prolonged service life of the electrodes [2, 3,4].
In the present work, we explored the electro-deposition process of PbO2 on the Ti substrate with a Sb-doped SnO2 interlayer, from a traditional acidic nitrate solution. By varying electro-deposition temperature, time and current density, we are able to synthesise PbO2 coatings with various morphologies (as can be seen in Figure 1.), microstructures and crystallite sizes. The surface morphology and phase structure were characterized by SEM and XRD. Voltammetric studies were performed using a conventional three-electrode cell system and a CHI604D (Chenhua, Shanghai) electrochemical workstation. It is found that an interlayer SnO2-Sb on Ti substrate can significantly promote the electro-deposition of PbO2 coatings. The preliminary results revealed that the electrochemical performance of deposited PbO2 largely depends on their morphologies and microstructures. The deposition temperature, deposition time and current density affect the PbO2 coatings in a synergic manner.
It is our purpose to establish a correlation between electrolyte temperature, deposition time, current density and phase structure, morphological features on the Ti/SnO2-Sb substrate. This information may shed light on a further understanding of electro-crystallisation and also provide a perspective on further possible improvement of the electrochemical performance of PbO2coatings in terms of service lifetime and electro-catalytic activity.

Keywords: Lead dioxide; Electro-deposition; Surface characterisation; SnO2 interlayer

References

[1] X. Li, D. Pletcher, F.C. Walsh, Chem. Soc. Rev., 40 (2011) 3879.
[2] S. Song, L. Zhan, Z. He, L. Lin, J. Tu, Z. Zhang, J. Chen, L. Xu, J. Hazard. Mater., 175 (2010) 614.
[3] Y. Wang, B. Gu, W. Xu, L. Lu, Rare Metal Mat. Eng., 36 (2007) 874.
[4] H. An, Q. Li, D. Tao, H. Cui, X. Xu, L. Ding, L. Sun, J. Zhai, 258 (2011) 218.
Computational Investigations of Charge Transport in Non-Aqueous Li-O
2
Batteries
Authors: Viswanathan Venkatasubramanian , Nørskov Jens , Luntz Alan C 
Published: February 2020

Despite their great promise, there are significant challenges to developing practical Li−air batteries. One is the electrical passivation of the cathode during discharge.[1,2] This occurs because insoluble and insulating Li2O2 produced during discharge builds up as a deposit on the cathode surface and ultimately inhibits charge transfer to the Li2O
2
−electrolyte interface where the electrochemistry occurs. This manifests itself as a “sudden death” (rapid drop in the output potential U) of the discharge at some maximum discharge capacity, Qmax.
In this talk, we will discuss the dependence of the maximum discharge capacity Qmaxon the current density, j.[3] We show that a wide range of experiments can be rationalized using a model that accounts for charge transport through tunneling and polarons. We further show that tunneling dominates at the current density of interest.
References
[1] P. Albertus, G. Girishkumar, and B. McCloskey, J. Electrochem. Soc. (2011) 158, A343-A351.
[2] V. Viswanathan, K. Thygesen, J.S. Hummelshøj, J. K. Nørskov, G. Girishkumar, B. D. McCloskey, and A. Luntz, J. Chem. Phys., (2011) 135, 214704.
[3] A. C. Luntz, V. Viswanathan, J. Voss, J. Varley, J. K. Nørskov, R. Scheffler and A. Speidel, J. Phys. Chem. Lett., (2013) 4, 3494-3499.
Fig 1: (a) Experimental Li−O2 galvanostatic discharge curves (U versus capacity) observed in a bulk electrolysis cell on a ∼1 cm2 area GC cathode with 1 M LiTFSI in DME as the electrolyte, ∼1 bar O2 pressure, and at T = 20 and 40 °C. The various curves for different discharge currents and T are labeled at the side. (b) Theoretical galvanostatic discharge curves (U versus the average thickness of the film d) under the same conditions as (a) and based on the simple model described in ref. [3].
Oxygen Bubble Nucleation Modeling in a PEM Electrolyzer Electrode
Authors: Arbabi Faraz , Montazeri Hanif , Abouatallah Rami , Wang Rainey , Bazylak Aimy 
Published: February 2020

The polymer electrolyte membrane (PEM) electrolyzer is a promising technology that reduces water into hydrogen and oxygen, from which the hydrogen is captured and stored for use in fuel cells. One of the challenging issues in PEM electrolyzers is flow inhibition of liquid water within the porous gas diffusion layer (GDL), due to the formation of oxygen bubbles (1). The bubbles block pores within the GDL, limiting the transport of liquid water to the catalyst layer, which in turn negatively affects the electrolyzer performance (2). Moreover, the presence of the oxygen bubbles can increase the solution resistance, inhibit electron transfer, and consequently increase ohmic losses, leading to efficiency reduction (1).
Investigation of the oxygen bubbles behavior generated at the anode side of the PEM electrolyzer in operational pressure and temperature can give us a more accurate insight for predicting its influence on the performance. A number of promising studies on bubble nucleation and detachment have been done over the past few years. Various numerical techniques were introduced and improved to increase the accuracy of the bubble interface tracking such as volume-of-fluid (VOF) (3), moment-of-fluid (MOF) (4), and level-set (LS) methods (5).
In this study, a numerical simulation has been performed to mimic the nucleation, growth and detachment of the oxygen bubbles in electrolyzers. Utilizing a state-of-the-art multiphase algorithm (6), a three-dimensional, two-phase computational algorithm was developed using the LS method to track the oxygen bubble interface expansion. To simulate the multiphase system more precisely, the thermodynamic free energy of the system has been taken into account by employing the Gibbs free energy function. The behavior of the oxygen bubble through the GDL as a function of the geometrical properties of the GDL was then studied and compared to the experimental results presented by Arbabi et al. (7).

Acknowledgements

The authors would like to gratefully acknowledge the financial support from the Natural Sciences and Engineering Research Council of Canada (NSERC).

References

1. H. Matsushima, T. Nishida, Y. Konishi, Y. Fukunaka, Y. Ito and K. Kuribayashi, Electrochimica Acta, 48, 4119 (2003).
2. H. Ito, T. Maeda, A. Nakano, C. M. Hwang, M. Ishida, A. Kato and T. Yoshida, International Journal of Hydrogen Energy, 37, 7418 (2012).
3. C. W. Hirt, J. L. Cook and T. D. Butler, Journal of Computational Physics, 5, 103 (1970).
4. V. Dyadechko and M. Shashkov, Journal of Computational Physics, 227, 5361 (2008).
5. S. Osher and J. A. Sethian, Journal of Computational Physics, 79, 12 (1988).
6. H. Montazeri and C. A. Ward, Journal of Computational Physics, 257, Part A, 645 (2014).
7. F. Arbabi, A. Kalantarian, R. Abouatallah, R. Wang, J. Wallace and A. Bazylak, ECS Transactions, 58, 907 (2013).
(Invited) Increased Oxide Ion Diffusivity and Surface Exchange on Pr2NiO4 Base Oxide by Au Dispersion
Authors: Hyodo Junji , Tominaga K. , Ju Young-Wan , Ida Shintaro , Ishihara Tatsumi 
Published: February 2020

Mass transport property in nano-size structure controlled materials are attracting much interest because such effects have a possibility to improve the performance of the electrochemical solid state devices such as Solid Oxide Fuel Cells (SOFCs). There are many approaches and ideas for the improvement of oxide ion conductivity in electrolyte by nano size effects. In this study, we demonstrated the 3 dimension (3D) tensile strain in Pr2NiO4, mixed conductor, was successfully introduced by dispersing Au particles in grain. The maximum lattice distortion estimated from X-ray diffraction measurement was 0.23 % at 2 mol% Au dispersion. Au dispersed Pr2NiO4 shows a large positive effect on oxide ion diffusivity and surface exchange coefficient.
The doubled oxygen permeation flux was achieved with dispersing 2 mol% Au in PNCG at 873 K, indicating the tensile strain in PNCG lattice positively works for the oxygen permeation property. Since oxygen permeation is controlled by interstitial oxygen concentration and its mobility, further details study on effects of tensile strain on oxygen diffusivity were studied by using 18O tracer diffusion. The depth profiles of x mol% Au/PNCG (x=0, 1, 2, 3) are studied with SIMS analysis, and the estimated oxygen tracer diffusivity (D*) and the surface exchange coefficient (k*) are much increased with dispersing Au, and the enhancement in D value was well agreed with that in oxygen permeation rate. Redox titration measurement suggests that 3D tensile strain increased amount of excess oxygen. Interstitial oxygen in Pr2NiO4 is introduced in Rock salt layer of K2NiF4 structure, and this is origin for the fast oxygen diffusivity and high surface activity for oxygen dissociation.
Recently, there is much attention of surface composition in oxide ionic conductors using the low-energy ion scattering (LEIS) technique to understand the surface reaction and degradation. LEIS analysis was also performed on Au dispersed Pr2NiO4 and it was found that surface of Pr2NiO4 was enriched with Pr. However, Pr segregation was prevented by introduction of Au and so tensile strain also positively works for preventing Pr segregation. On the other hand, surface oxygen content is also decreased by Au dispersion and so surface oxygen vacancy seems to be much enriched. Therefore, increased surface exchange coefficient by Au dispersion could be assigned to the high concentration of oxygen vacancy on surface of Pr2NiO4 dispersed with Au.
In summary, although Au dispersion was not uniform, effect of tensile strain on oxide ion mobility could be observed in Pr2NiO4 by Au dispersion. Furthermore, tensile strain affected the surface composition, which may enhance the k* values. If the better dispersion state with fine particles could be achieved, there is a possibility to develop the higher oxide ionic conductor with uniform strained material.
The Effect of Sulfurization on the CuIn(Se,S)2 Photovoltaic Cell Synthesized By Electrodeposition
Authors: Kwon Youngim , Yoo Bongyoung 
Published: February 2020

Photovoltaic is one of the most fascinating ways for direct solar energy conversion. The demand for photovoltaic is mainly covered by crystalline silicon; substantial cost reductions are necessary for large scale applications. A big challenge for thin film PV is the development of large area semiconductor thin films. The main candidate semiconductor materials for thin film solar cells at present are amorphous silicon, CdTe and Cu(In,Ga)(Se,S)2.
Generally, even though physical vapor deposition (PVD) methods have been widely used for making the CIGS thin film 1-3, its high process cost because of the vacuum system and difficulty on the large scale up still remained to overcome for mass production.
Non-vacuum methods, such as hydrazine-based solution process, paste coating, and electrodeposition have been studied to achieve the low cost process with high efficiency 4-7. Electrodeposition could substitute for PVD methods because it has several advantages in cost competitiveness, easily scaled up, convenience control in room temperature and atmosphere pressure. Recently, the efficiency of CIGS solar cell manufactured by electrodeposition method exceeds 11% 8.
In this study, the effects of sulfurization temperature on CuIn(Se,S)2 (CISeS) thin film solar cell have been investigated. Unlike well-known CIGS absorber, we adjusted the bandgap by controlling the ratio of Se and S, which could simplify the deposition process for obtaining absorber layer. 1㎛-CuInSe2 layer was deposited on Mo/SLG (soda lime glass) at room temperature by electrodeposition method. To form CuIn(Se,S)2 thin film, thin films were annealed in 5% H2S-95% Ar atmosphere at 425-600℃. As the sulfurization temperature increased, the grain growth of CISeS films was improved and the ratio of Se/S decreased, then the optical bandgap was close to ideal value for solar cell (~1.4eV). However, MoS2layers appeared at high temperature (≥500℃) and the film morphology was getting more porous with increasing temperature. As a result, the conversion efficiency decreased as the sulfurization temperature increased, and the maximum value of the conversion efficiency was 2.32% at 425℃.
To improve the cell efficiency, the effects of sulfurization time on grain growth have been investigated. CuInSe2 thin films were annealed in 5% H2S-95% Ar atmosphere at 425℃ for 20-60min. When the sulfurization time increased, the crystallinity of CuIn(Se,S)2 film improved. As a result, the conversion effieciency increased to 3.48% without anti-reflection coating layer.