bluuebunny/crossref_metadata_2025_split huggingface dataset:
Synthesis and Electrochemical Characterization of LiMn2-xFeXO4 Cathode Materials for LI Ion Rechargeable Batteries
Authors: Singhal Rahul , Katiyar Rajesh K. , Katiyar Ram , Chiovoloni Sam , Lemaire Peter 
Published: February 2020

High energy density batteries are essential for portable electronic devices e.g. Laptops, mobile phones, iPads, toy etc. Besides this, high energy density batteries are also required for power tools and hybrid electric vehicles. Commercially available lead-acid batteries are toxic and have low energy density and not suitable for electronic devices. Advanced Li-ion batteries possess high specific energy as compared to existing rechargeable battery technologies. Commercially available Li ion rechargeable batteries having LiCoO2 as cathode materials are toxic and expensive due to the presence of cobalt. Additional disadvantage of LiCoO2 based batteries is their low operating voltage (3 V), which restricts their application for hybrid electric vehicles and power tools. It has already been reported that the charge-discharge characteristics and cycleability of LiMn2O4 can be improved by substituting the Mn3+ ion with transition metals e.g. Cr, Co, Ni, Cu etc. To increase the energy density of the Li ion rechargeable batteries we will be exploring the cathode materials, working in higher operating voltage (~5V) range.
We have synthesized LiMn2-xFexO4 cathode materials for Li ion rechargeable batteries. The concentration of Fe varies from 0.1 to 0.5 with an increment of 0.1. The cathode materials were synthesized by sol-gel method and calcined at various temperature in the range of 800 oC to 950 oC. The synthesized materials were physically characterized by X-ray diffraction (XRD), differential thermal scanning calorimetry (DSC), micro-Raman spectroscopy and scanning electron microscopy. We obtained phase pure Fd3m structure in all synthesized compounds. The electrochemical characterization were carried out in a coin cell configuration using cyclic voltammetry, charge-discharge characteristics, impedance spectroscopy and cycleability. Cyclic voltametric studies reveal the reversible electrochemical properties of LiMn2-xFexO4 cathode materials. The detailed results and discussion on physical and electrochemical properties of LiMn2-xFexO4 cathode materials will be presented in the ECS 229th meeting.
Synthesis and Conductivity of Directly Cross-Linked Poly(vinyl alcohol)/ Bis (2 chloroethyl) Ether-1,3-Bis[3-(Dime- thylamino) Propyl]Urea Copolymer Composite
Authors: Qiao Jinli 
Published: February 2020

The alkaline membrane fuel cells (AMFCs), which use the anion-exchange membranes to display the proton-exchange membranes with OH- anions instead of H+ ions, have aroused new interest due to their faster electrokinetics, lower fuel crossover, reduced CO poisoning, and use of non-precious metal catalysts 1,2.In the development of AEMFCs, the conductivity of alkaline anion-exchange membranes (AEMs) is considered to be the most challenge, since the mobility of OH- is only 1/4 of that of the H+ transportation (membranes that conduct H+ cations), the membranes that can have high OH- conductivity are highly desired for making a breakthrough in AEMFCs performances3,4. However, these polymers were generally of high price and their quaternization is complex process.
In this work, we report a novel alkaline anion-exchange membrane prepared from poly(vinyl alcohol)/Bis(2-chloroethyl)ether-1,3-bis[3-(dimethylamino)propyl]urea copolymer (PUB) composite on the basis of direct chemical cross-linking method5 .By incorporation of PUB, the OH- conductivity of the PVA/PUB membrane was found to be greatly improved and reached high up to 5.56×10-
3S cm-1 .
The membranes were prepared by a simple solution-casting method, where PVA (99% hydrolyzed, average molecular weight Mw=86,000-89,000; Aldrich) was fully dissolved in water to make a 10% solution at 70oC. PUB (62% as active ingredients in H2O; Aldrich) and glutaraldehyde (GA) solution(25% mass) was directly added by addition of a drop of HCl to get a homogeneous appearance at room temperature, and stir for 30 min. The anion conductivity of PVA/PUB/GA composite membrane is studied using AC impedance technique.
Figure 1 composite membrane picture of PVA/PUB. It is obvious that the membrane is standing and flexible.
Figure 2 shows the ionic conductivity of the membrane (PVA:PUB:GA=1:0.25:0.05 and PVA:PUB:GA=1:0.25:0.1 by mass) as a function of content of GA. The sOH
- values increased with increasing GA contents and reached 5.56×10-3 S cm-1 when polymer composition is PVA:PUB:GA=1:0.5:0.1 by mass.
References
1. J. Zhou, M. Ünlü, I. Anestis-Richard, P.A. Kohl, J. Membrane Science, 350 (2010)286.
2.J. L. Qiao, J. Fu, R. Lin, J. X. Ma, J. S. Liu, “Alkaline solid polymer electrolyte membranes based on structurally modified PVA/PVP with improved alkali stability,”Polymer, Vol. 51, pp. 4850-4859(2010).
3. Jinli Qiao, Jing Zhang, Jiujun Zhang, Journal of Power Sources 237 (2013) 1e4.
4.Y. Wan, B. Peppley, K A.M Creber, V. Tam Bui, J. Power Sources. Soc. 195, 3785 (2010).
5.J. L. Qiao, J. Fu, L. L. Liu, L. Xu, Y. Y. Liu, J. W. Sheng, Int. J. Hydrogen Energy 37, 4580 (2012).

Figure 1
Li Salt Rich Separator for Li-Ion Batteries
Authors: Mourzagh Djamel 
Published: February 2020

In order to reduce the duration of the electrolyte filling step, Solvay proposes a new concept of separator embedding itself Li salt thanks to a Li salt rich film coated on (Patent Solvay).
The objective of the present study was to quantify the impact (benefits and drawbacks) of a Li salt containing PVdF based film deposited by coating onto a conventional polyolefin based separator. The thin coated layer is composed of Solef® PVdF containing LiTFSI salt in appropriate amount. The separator selected for the study was the Celgard® 2320.
After having developed the method for manufacturing such a coated separator, electrical evaluations were conducted in representative intermediate capacity-level Li-ion cells, trials with pilot coating machines were also performed to demonstrate the feasibility of coating a separator at industrial level and the impact of the storage were also studied.
Evaluation of Silicon-Based Full Cells and the Importance of Scale-up
Authors: Karulkar Mohan , Wen Hao , Blaser Rachel , Kudla Robert 
Published: February 2020

USABC long-term EV targets highlight the need for higher energy density in automotive batteries [1]. Many promising high energy materials have been demonstrated in academia, but there is a gap between academic and industrial research. This is partly due to the incompatibility of automotive targets with academic research metrics. Some common metrics are shared between the two arenas, but there remain others that do not translate due to scale. Bench-top experiments are helpful for identifying promising materials, but key automotive metrics like volume change are impractical to measure in bench-scale cells. Thus, scale-up of benchtop research is critical to fully addressing automotive needs.
This talk will detail various metrics that lend themselves to scale-up. Specifically, we will discuss Ford’s efforts to quantify volume change in Silicon-based anodes. Previously, Ford has reported on electrochemical performance of silicon-based cells [2], and here we will tie those results in with volume expansion for different cell configurations. We will also combine the results with our ongoing Automotive Target Modelling efforts [3]. Finally, this talk will provide an overview of the user-based battery fabrication facilities available at the University of Michigan Battery Lab.
[1] “USABC Goals for Advanced Batteries for EVs - CY 2020 Commercialization,” http://www.uscar.org/commands/files_download.php?files_id=364 (2014)
[2] M. Karulkar, R. Blaser, R. Kudla, J. Power Sources, 273, 1194-1201 (2015).
[3] M. Karulkar, “Battery Metrics and Real World Automotive Target Modelling,” 227th Electrochemical Society Meeting, Paper MA2015-01 33, Chicago, IL (2015).
Macroscale Vs. Microscale Simulation of Porous Battery Electrodes
Authors: Higa Kenneth , Wu Shao-Ling , Parkinson Dilworth Y. , Fu Yanbao , Battaglia Vince , Srinivasan Venkat 
Published: February 2020

Typical porous composite electrodes are enormously complicated, disordered arrangements of active material, binder, conductive material, and pore space. In spite of this complexity, battery simulations based on the porous electrode model pioneered by John Newman have provided a wealth of insight into battery operation at low computational cost. This is made possible by the use of spatial averaging to produce vastly simplified spatial domains on which averaged governing equations can be rapidly solved. With these simplifications, the porous electrode model can provide information about the average spatial variation of quantities such as lithium ion concentration and electrochemical potential.
However, results from simulations based on the porous electrode model are known to diverge from experimental results under relatively demanding operating conditions (see, for instance, [1]) that can arise during typical electric vehicle use. This might be the consequence of the spatial averaging approach of the porous electrode method, as electrode microstructure might have a significant influence on transport processes and cell performance. In order to explore this possibility, we have performed traditional porous electrode model simulations and corresponding electrochemical simulations based on the microscale electrode structure.
Nickel manganese cobalt oxide (NMC) electrodes were fabricated and incorporated into half-cells, from which discharge curves were obtained. Electrode parameters were used to construct simulations based on the porous electrode model, and an optimization scheme was used to minimize discrepancies between simulation and experimental results.
Samples of the same uncycled NMC electrode material were then imaged at the X-ray microtomography beamline of the Advanced Light Source (ALS). Three-dimensional reconstructions were transformed into spatial domains, on which direct numerical simulations were performed to obtain discharge curves. These simulations preserved spatial detail but involved much higher computational costs than those based on the porous electrode model.
We will present results from these microscale and macroscale simulations, exploring reasons for discrepancies between the two models and discussing present shortcomings with respect to experimental results.
[1] M. Doyle, J. Newman, A. S. Gozdz, C. N. Schmutz, and J.-M. Tarascon, J. Electrochem. Soc. 1996, vol. 143, issue 6, pp. 1890-1903
An Innovative Polymer Design for Polysulphides Shuttle Effect in Lithium-Sulphur Batteries
Authors: Ling Min , Yang Changan , Zhao Hui , Jia Zhe , Wang Huali , Fang Shan , Liu Gao 
Published: February 2020

Lithium sulphur batteries hold great potential due to its around 5 fold energy density promotion compare to conventional lithium ion batteries. However, wide-scale has been impeded by rapid capacity fading mainly caused by shuttle effect in consequence of intermediate polysulphides diffusion. Herein, we propose a scalable bottom-up polymer approach to immobilize intermediate polysulphides. The evolution of the chemical bonding was studied in detail. The electrochemical results show a high initial capacity of ca. 1500 mAh/g and 900 mAh/g after 100 cycles specifically at 0.05 C to magnify the shuttle effect. Moreover, a high areal capacity of ca. 6 mAh/cm2 is achieved, which demonstrate the excellent capability to trap soluble polysulphide intermediates.
Atomic Layer Deposited Fluoride Coatings for Li-Ion Battery Cathodes
Authors: Jackson David H. K. , Laskar Masihhur , Fang Shuyu , Xu Shenzhen , Ellis Ryan G. , Li Xiaoqing , Dreibelbis Mark , Babcock Susan E. , Mahanthappa Mahesh K. , Morgan Dane , Hamers Robert J. , Kuech Thomas F. 
Published: February 2020

Atomic layer deposition (ALD)1, 2 of AlF3 coatings for the Li-ion battery cathode LiNi0.5Mn0.3Co0.2O2 (NMC)3, 4 was investigated using a combination of trimethylaluminum and TaF5 precursors. ALD growth mode was dictated by a competition between temperature-limited desorption of Ta reaction byproducts and temperature-driven conversion of these byproducts into nonvolatile TaC. At T ≥ 200°C, decomposition to TaC occurred, leading to continuous deposition and high concentrations of TaC in the resulting films. A self-limited ALD growth mode was found to occur when deposition temperature was reduced to 125 °C, and the TaF5 exposures were followed by an extended purge. During ALD growth, vapor-surface ligand exchange reactions lead to formation of Ta(CH3)xF5-x and AlF3. Ta(CH3)xF5-x desorbs from the surface or it decomposes via an intermolecular α-hydrogen abstraction,5,6 eventually forming TaC. The extended purge times and lower temperatures reduce decomposition, while also allowing more time for Ta(CH3)xF5-x desorption. NMC cathode powders were coated using these optimized conditions, and coin cells employing these coated cathode particles were characterized using electrochemical impedance spectroscopy and by cycle performance testing, which demonstrated significant improvements in charge capacity fade at high discharge rates as compared to uncoated materials (Figure 1). These improvements at high C-rates are attributed to the reduction of undesirable electrode-electrolyte reactions by protection of the cathode surface with the ALD coating through which fast Li-ion transport occurs.7-9

Figure 1: Averaged gravimetric capacity of coin cells versus discharge cycle number during a rate test. Black squares (■) fluoride ALD coated, red circles (●) uncoated.

References

1. R. L. Puurunen, Journal of Applied Physics, 2005, 97, 52.
2. S. M. George, Chemical Reviews, 2010, 110, 111-131.
3. Z. H. Lu, D. D. MacNeil and J. R. Dahn, Electrochemical and Solid State Letters, 2001, 4, A200-A203.
4. N. Yabuuchi and T. Ohzuku, Journal of Power Sources, 2003, 119, 171-174.
5. R. R. Schrock, Journal of Organometallic Chemistry, 1976, 122, 209-225.
6. Y. D. Wu, K. W. K. Chan and Z. Xue, Journal of the American Chemical Society, 1995, 117, 9259-9264.
7. K. S. Lee, S. T. Myung, D. W. Kim and Y. K. Sun, Journal of Power Sources, 2011, 196, 6974-6977.
8. S. Q. Hao and C. Wolverton, Journal of Physical Chemistry C, 2013, 117, 8009-8013.
9. S. Z. Xu, R. M. Jacobs, H. M. Nguyen, S. Q. Hao, M. Mahanthappa, C. Wolverton and D. Morgan, Journal of Materials Chemistry A, 2015, 3, 17248-17272.

Figure 1
Solid Electrolyte Interphase Formation Mechanism on Silicon Revealed By in-Situ Attenuated Total Reflection-Infrared
Authors: Shi Feifei , Ross Philip N 
Published: February 2020

Si has been widely recognized as one of the most promising anode materials for its high energy density; however, critical drawbacks such as large irreversible capacity decay and poor reliability/durability over extended cycles have significantly constrained its commercialization in many long duration, heavy duty applications. Aforementioned drawbacks are partially due to loss of electrolyte by reduction at electrode surface (formation of Solid Electrolyte Interphase (SEI)) and the chemical/mechanical instability of SEI through cycling. For a better understanding on the mechanism of Si electrode failure during battery cycling, we design and develop a novel in-situ ATR-FTIR spectra-electrochemical cell, and study the SEI chemistry using this in-situ ATR-FTIR technique.
In this work, we investigate the chemical composition of SEI on single crystal silicon electrode (100), which was selected as an ideal model surface. By tuning the probing depth in vibrational spectra of molecules near the electrode surface, we specifically address the dependence of SEI chemical composition on applied potential and penetration depth from interface to bulk. The experimental observation indicates that soluble species like DEDOHC is formed at silicon surface covered by native oxide, which is related to the chemical instability of SEI and contributes to the early failures of Si anode. In contrast, the main component of SEI on Li15Si4 is LiEDC, which is responsible for the passivation of freshly cracked surface during the long-term cycling. Si-F species are visible at inner interphase, while the organic product mainly locates at the outer portion of SEI. These clues pave the SEI formation paths on silicon anode, showing how the chemical side reactions couples with mechanical degradation. These failure modes understanding would also benefit other alloy host electrodes, which suffer from multiple fold degradation.
Acknowledgement:
This work was supported by the Assistant Secretary for Energy Efficiency and Renewable Energy, Office of Freedom CAR and Vehicle Technologies of the U.S. Department of Energy under contract No. DE-AC02-OSCH11231.
Coupling of Electrochemical Charging with Mechanical Expansion and Degradation in Nanostructured MnO2 Cathodes
Authors: Ignatova Tetyana , Rajapakse Arith J. , Collins Philip G. 
Published: February 2020

The faster kinetics of nanostructured charge-storage materials are often accompanied by accelerated degradation and failure, compromising the potential advantages of nanostructure and nanoporosity. Understanding and controlling the exact mechanisms of this degradation is a complex materials characterization challenge. The recent availability of in situ and in operando techniques allows new fundamental studies of these issues, including the failure of nanoscale porosity to fully accommodate the mechanical strains of charge insertion.
Here, we use atomic force microscopy in liquid electrolytes to experimentally measure the mechanical expansion of porous, nanostructured Li-ion cathodes during charge cycling. Using thin films of LixMnO2 on Pt collectors, we analyze expansion as a function of scan rate, voltage window, and porosity. Comparative measurements in aqueous and nonaqueous electrolytes confirm the role of Li-ion species in the results. The rate dependent measurements of expansion can be separated into diffusion-limited, bulk components driven by Mn3+/4+ charging and faster, surface processes, in the same way that these contributions to capacitance are normally separated. Consequently, we have extracted the electrochemical-mechanical coupling coefficients ∂V/∂Q for surface and bulk processes separately. While the bulk coupling coefficient provides an excellent match to values predicted from first-principles theory, the surface coupling is surprisingly large. In fact, surface capacitance is responsible for a majority of the mechanical expansion at high rates, even when most of this capacitance would normally be attributed to double-layer charging mechanisms. The result demonstrates the importance of Mn3+/4+ species at the electrolyte interface and the inability of these species to take advantage of the film’s nanoporosity for accommodating expansion. In other words, fast surface charging processes do not involve mechanical relaxation of the material into adjacent pores, but rather drive expansion of the solid matrix.
High Temperature Alkaline Electrolysis - Status and Potential
Authors: Chatzichristodoulou Christodoulos , Mogensen Mogens Bjerg 
Published: February 2020

Alkaline electrolysis is a proven technology with several large scale facilities for hydrogen production realized and operated reliably for decades. Nevertheless, its broader deployment is hindered by the relatively high cost for hydrogen production. To overcome this obstacle, it is necessary to improve cell efficiency, increase the production rate, and decrease capital cost. Since conventional alkaline electrolysis technology has reached maturation, only small incremental improvements can be expected. To achieve a drastic step forward, we have developed a new generation of alkaline electrolysis cells that can operate at elevated temperature and pressure, producing pressurized hydrogen at high rate (m3 H2/hm2 cell area) and high electrical efficiency.
The concept relies on the development of corrosion resistant high temperature diaphragms, based on mesoporous ceramic membranes where aqueous KOH is immobilized by capillary forces, in combination with gas diffusion electrodes that overcome mass transport limitations at large production rates. Raising the operating temperature offers a means to drastically improve performance, as both ionic transport and reaction kinetics are exponentially activated with temperature. Indeed, we have demonstrated alkaline electrolysis cells operating at 200-250 °C and 20-50 bar at very high efficiencies and power densities. This enables high production rates near the thermoneutral voltage, thereby overcoming the need for cooling.
This work will provide an overview of the exploratory technical studies undertaken so far. Two electrochemical test stations have been established to carry our experiments at elevated pressures (up to 99 bar) and temperatures (up to 300 °C). The conductivity of aqueous KOH was investigated at elevated temperatures to establish the optimum concentration at 200-250 °C. An optimum value of 0.84 S cm-1 was established at 200 °C for 45 wt% aqueous KOH immobilized in mesoporous SrTiO3. Gas diffusion electrodes were developed using metal foams loaded with different non-precious metal electrocatalysts in order to reduce the overpotentials for oxygen and hydrogen evolution. Small cells have been fabricated and operated at current densities of up to 1.75 A cm-2 and 3.75 A cm-2 at cell voltages of 1.5 V and 1.75 V at 200 °C at 20 bar, corresponding to electrical efficiencies of almost 99 % and 85 %, respectively. Long-term operation at 200 °C was successfully demonstrated for 400 h, suggesting relatively stable cell performance. Finally, low-cost production methods have been utilized for a first scale-up of the cell size from 1 cm2 to 25 cm2. Efforts are currently directed towards the investigation of the intrinsic activity of mixed oxides for the oxygen evolution reaction at elevated temperatures and pressures, and towards establishing the required infrastructure for testing of 25 cm2 cells.