bluuebunny/crossref_metadata_2025 huggingface dataset:
Study on the Cathode Material Composed of LiCo1/3Ni1/3Mn1/3O2 and LiMn2O4
Authors: Qiu Jingyi , Yu Zhongbao , Li Meng , Zhan Shang
Published: February 2020

Electric vehicles and energy storage will become the main application fields of next generation lithium-ion batteries, which require excellent performances such as high safety, large capacity and high power density for lithium-ion batteries. However, currently single cathode materials for lithium-ion batteries, such as LiCoO2、LiMn2O4、LiFePO4、LiCo1/3Ni1/3Mn1/3O2,could not meet these requests at the same time. Mixing different structures of cathode materials together is one practical way to improve performances of materials by complementary advantages of each other.

This work is to improve electronic conductivity and capacity of LiMn2O4 by adding LiCo1/3Ni1/3Mn1/3O2 in, and meanwhile the existence of LiMn2O4 could lower danger bringing from LiCo1/3Ni1/3Mn1/3O2. Different proportional mixtures with LiCo1/3Ni1/3Mn1/3O2 and LiMn2O4 were used as cathode materials for lithium ion battery. The results of charge-discharge tests show that the cyclic performance becomes better with the increase of LiCo1/3Ni1/3Mn1/3O2 until the proportion is higher than 5:5. The battery has better cyclic capability and kkk impedance when the proportion of LiCo1/3Ni1/3Mn1/3O2 and LiMn2O4 is 5:5,Itsinitial discharge specific capacity is 154.4 mAh/g, after 60 times charge-discharge, specific capacity is 143.0mAh/g, the capacity retention rate is92.62%; And the average voltage is 3.92 V(vs. Li + / Li),significantly higher than the discharge voltage platform of LiCo1/3Ni1/3Mn1/3O2 which is 3.80 V (vs. Li + / Li).
Electrochemical and Magnetic Properties of Li1-XCo1-XFexPO4 High Voltage Cathodes
Authors: Nakamura Tatsuya , Oka Yoshihiro , Hanafusa Reiko
Published: February 2020

Li1-xCo1-xFexPO4 particles with x<0.10 were prepared by the sol gel method. The gel precursors were thermally decomposed at 350°C and then annealing at 550°C in air. They all were single phase of orthorhombic olivine compounds and the lattice parameters almost obeyed the Vegard’s law. The Moessbauer spectrum at 300K showed a paramagnetic doublet with d=0.44mm/sec and De=0.76mm/sec, and these parameters are characteristic to high spin-state Fe3+ in FePO4. The antiferromagnetic Neel temperature shifted higher with an increase in X, due to strong exchange coupling via Fe3+. The effective magnetic moment derived form the Curie-Weiss law was raised with the Fe3+ substitution. It was confirmed from these experimental facts that they are the solid solution compounds between LiCoPO4 and FePO4. The electrochemical cycling of these cathode materials was evaluated with Li coin cell at the range from 3.5 to 5.0V under the CC-CV mode. They exhibited the charge/discharge plateau approximately at 4.9/4.7V. The initial discharge capacity increased (from 125 to 140mAh/g) with x up to 0.05 and then decreased (to 130mAh/g). On the other hand, the capacity retention after 20th cycles was significantly improved with the substitution. Hence, a partial substitution with Fe3+ may enhance the electrochemical activity of LiCoPO4 high voltage cathode compound. Now, detail studies on the charge-discharge mechanism, such as the structural variation and the electronic state change of transition metals, are being carried out. These results will be presented and discussed at the conference. This work has been carried out under the support of Advanced Low Carbon Technology Research and Development Program (ALCA).
Approach of “Electrodes to Electrodes”: Challenges for Recycling Advanced Lithium-Ion Batteries for e-Mobility
Authors: Tedjar Farouk
Published: February 2020

Lithium ion sector is the most dynamic among the battery segment. several omposition of li-ion batteries are now on the market while basic composition is moving from lithium cobalt oxides / carbon portable segment to several kinds of cathodes materials, electrolytes and anodes materials. This means that we are in the need of new flexible processes while maintaining high recycling rate linked mainly to:

1- Process in safe way high capacity batteries

2- Achieve resource conservation in general and lithium in particular

3- Provide process with low environment impact mainly on fluoride/solvent emissions while having improved carbon print avoiding any CO2 production.

A new process will be presented . Work are coming our from several R&D programs such as:

1-National French Networks Project ELLISUP and PROCYON

2- 7th FP European Cluster AMELIE, SOMABAT, MARS-EV

New process obtained during those projects will be presented.

Approach of “electrodes to electrodes” will be considered.
Effect of the Iron Doping on the Crystal Structure and Electrochemical Performances of LiCoPO4
Authors: Di Lecce Daniele , Brutti Sergio , Panero Stefania
Published: February 2020

Current research in lithium-ion battery field focuses on the improvement of energy density and power performances. One way to increase the battery energy is the use of high voltage cathode materials with a large charge capacity and cycling capability. The LiCoPO4 olivine is an interesting candidate as high-voltage cathode for lithium cells due to its high working potential cells (4.8 V vs. Li/Li+), still within the working limits of the carbonate-based liquid electrolytes, its flat voltage profile and a theoretical capacity of about 167 mAh g-1. However the poor electronic conductivity and the low Li-ion diffusion coefficient limit its practical application [1].

Herein we present our recent results about the study of the synthesis of lithium cobalt phosphate materials and the effect of the iron doping on its structural features and electrochemical properties in lithium cell. In particular X-ray diffraction experiments have been carried out at the MCX beamline in the ELETTRA facility in order to elucidate the role played by iron doping on the lattice structure and local ordering of the cation sublattice. Furthermore a careful analysis of the performances in lithium cells have been carried out by comparing materials prepared in different experimental conditions with and without iron doping, in order to decouple the concurrent effects that drive the ability of this material to reversibly cycle lithium (e.g. particle size, lattice disorder, iron doping).

[1] S.Brutti, S.Panero, Recent Advances in the Development of LiCoPO4 as High Voltage Cathode Material for Li-Ion Batteries in “Nanotechnology for Sustainable Energy”, ACS Symposium Series, Vol. 1140, Chapter 4, pp 67–99
A Novel Electrolyte Additive for High-Voltage LiNi0.5Mn1.5O4 Positive Electrode
Authors: Lee Tae Jin , Yoon Taeho , Jung Jiwon , Lee Jaegil , Chae Oh B. , Ryu Ji Heon , Oh Seung M.
Published: February 2020

The Ni-doped manganese spinel (LiNi0.5Mn1.5O4, LNMO) has been projected as a high-voltage positive electrode for lithium-ion batteries (LIBs). The high working voltage (> 4.6 V vs. Li/Li+) with an outstanding structural stability must be beneficial with respect to energy density and cycle life, but this advantage is offset by the instability of cell constituents. For instance, the commonly used electrolytes are decomposed and surface films deposit.1 Once surface films deposit, polarization increases to eventually cause a capacity fading.2,3

In order to mitigate the electrolyte decomposition/film growth, LNMO electrode should be passivated. A simple approach is the addition of film-forming agents, which decompose to form a protective layer to suppress additional electrolyte decomposition.

As a film-forming agent for LNMO electrodes, tris(pentafluorophenyl)silane (TPFPS) was tested in this work. Addition of TPFPS (0.1 wt. %) into the conventional electrolyte (1.3 M LiPF6in EC:EMC:DEC = 3:2:5 in vol. ratio) improves both the cycle performance and coulombic efficiency at 25°C and 60°C (Fig. 1a and 1b). TPFPS is oxidatively decomposed (< 4.7 V) prior to the electrolyte (Fig. 1c). The surface film derived from the additive shows a good passivating ability. The film growth and polarization increase are not serious. In contrast, the surface film derived from the additive-free electrolyte is poorly passivating. Surface film steadily grows due to continued electrolyte decomposition, which eventually leads to capacity fading due to ever-increasing electrode polarization (Fig. 1d).

References

1. J. B. Goodenough and Y. Kim, Journal of Power Sources, 196, 6688 (2011).

2. D. Aurbach, B. Markovsky, Y. Talyossef, G. Salitra, H.-J. Kim and S. Choi, Journal of Power Sources, 162, 780 (2006).

3. T. Yoon, S. Park, J. Mun, J. H. Ryu, W. Choi, Y.-S. Kang, J.-H. Park and S. M. Oh, Journal of Power Sources, 215, 312 (2012).

Fig. 1. Cycle performance and coulombic efficiency at 25°C (a) and 60°C (b). The differential capacity plot in the 1stcharging (c) and electrochemical impedance data obtained after 200 cycles (d).
Novel Ladder-like Polysilsesquioxane Hybrid Polymer Electrolytes for Lithium Ion Batteries
Authors: Lee Jin Hong , Lee Albert Sung Soo , Hwang Seung Sang , Hong Soon Man , Koo Chong Min
Published: February 2020

A novel inorganic-organic hybrid crosslinker was prepared through synthesis of a fully condensed, high molecular weight, ladder-like structured poly(methacryloxypropyl)silsesquioxane (LPMASQ) in one-pot with a facile, base-catalysed system. The fully condensed LPMASQ revealed good thermal (~380 °C), and electrochemical stability (~5.0 V), and good solubility in various organic solvents due to the absence of uncondensed silanol groups as well as the presence of hundreds of methacryl pendant groups in each macromolecule. LPMASQ fully gelated a 1 M LiPF6 (EC/DEC, 3/7, v/v) electrolyte solution through fast thermal and photo curing even at very low concentration of 2 wt %. This observation was attributed to the polymeric nature of LPMASQ containing over one hundred methacryl moieties on the rigid double-stranded siloxane backbone. To the best of our knowledge, formation of gel polymer electrolyte with 2 wt % gelator is the smallest gelation concentration that ever reported. This leads to the high ionic conductivity (~6.0 mS cm–1), excellent Coulombic efficiency and battery cell performance, comparable with those of neat liquid electrolyte. The small crosslinker content, thermal and electrochemical stability, fast thermal and photo curing and facile processing of the LPMASQ based GPEs, as well as excellent Li battery cell performances strongly hold great promise for future industrial battery applications.
Relation Between Pore Size Distribution and Discharge Capacity in Carbons Used As Li-O2 Cathodes with an Ionic Liquid-Based Electrolyte
Authors: Tonti Dino , Olivares-Marín Mara , Palomino Pablo , Enciso Eduardo
Published: February 2020

A method for relating the experimental pore size distribution with the discharge capacity of carbons used in Li-O2 cells was developed.

Four porous carbons with similar composition and specific area, but with pores peaking in different points of the mesoporous region (i.e. average pore diameter in the range of 5 - 55 nm) were obtained from a resorcinol-formaldehyde route. These were used as cathodes for Li-O2 batteries using an ionic liquid electrolyte (LiTFSI in PYR14TFSI) at room temperature and 60 ºC. Discharge capacities were related to the experimental pore size distribution determined from N2 adsorption.

The method consisted in testing a linear fit between discharge capacity and the volume occupied by the discharge products. These are assumed distributed in a layer of constant thickness on the pore walls. In addition, the model assumes that pores below a threshold size do not participate to the capacity, because their access becomes clogged much faster than for large pores. Thus, the occupied volume is calculated from the experimental cumulative pore volume and the two parameters, layer thickness and threshold pore size.

The fit quality was mapped as a function of these parameters. No constraints or other fixed parameters were used. Best fits, with a coefficient of determination R2>0.95 were obtained when the layer thickness was of the order of 7 nm, which is consistent with the thickness of an insulating passivation layer. The method also allowed estimating the penetration depth of the discharge reaction in the electrode thickness, which in our electrochemical test conditions resulted of the order of 20 nm at RT and 40 nm at 60 ºC.

The extension of applicability of this method will be discussed.

Acknowledgement

The research leading to these results has received funding from the European Union’s Seventh Framework Programme under EC-GA No. 265971 ‘LABOHR’, and from the Spanish Government under contract MAT2012-39199-C02-01. M.O. acknowledges CSIC for a JAE-DOC research contract.
Temperature-Dependent Hysteresis Behavior Modeling of the Open Circuit Potential and Impedance of LiFePO4 Batteries
Authors: Miller Steven Paul , Ostanek Jason K. , Heinzel John M , Shrestha Biju , Wetz David
Published: February 2020

Lithium Iron Phosphate (LFP) batteries present many challenges for accurate behavioral modeling during charge and discharge processes, as the two-phase interactions between cathode particles create multiple stable, degenerate distributions of lithium across the electrode. These degenerate distributions can cause the battery’s equilibrium open circuit potential (VOC) and equivalent series resistance (ESR) to vary at a given temperature and state of charge (SOC) depending on recent history, such as if the battery was most recently charged or discharged, a phenomenon known as hysteresis. A behavioral two-capacitor model was developed that incorporates temperature-dependent hysteresis between charge and discharge (affecting both VOC and ESR) and mimics temperature-dependent and SOC-dependent kinetics and impedance. The model includes a coupled finite volume thermal transport model with heat generation calculated due to a combination of Ohmic heating and entropic heating. The model was validated against high C-rate cyclic charge and discharge, as well as intermittent discharge and charge profiles at temperatures ranging from zero to 50°C. It is seen that for temperatures near 0°C, new physics come into play during recharge and that VOC hysteresis between charge and discharge increases as temperature decreases.
Excellent Cycle Performance of Pouch Cells at a High Rate Investigated By a Combination of Synchrotron Based X-Ray Diffraction and Absorption Spectroscopy
Authors: Fey George Ting Kuo , Lin Yi-Chuan , Wu Pin Jiun , Huang Kai Pin , Pai Chih Tung
Published: February 2020

Lithium-ion batteries are widely developed for vehicle applications and energy storage systems owing to their high power density, long cycle life, and lack of memory effect. The cycling stability of a Li-ion battery plays an important role in its practical application, especially for use in electric vehicles, which is generally affected by the types of electrode materials [1], binder properties [2], and electrolyte compositions [3].

Li-ion cells based on LiFePO4cathodes have been considered as one of the most promising candidates for large-scale application due to its low cost, low toxicity, good electrochemical and excellent thermal stability. However, the tendency for capacity degradation behaviour of LFP cells is still seen as a problem for practical application.

The capacity fading mechanism of a laminated pouch type 1.0 Ah cell consisting of a graphite anode and an olivine LiFePO4 cathode during a long-term cycling test was studied in this report. The LiFePO4cathodes have a mole ratio of iron to phosphorus in the range of 0.93 to 0.99. As shown in Fig. 1, the LFP cell with a Fe/P ratio of 0.99 has the best cyclic performance at the charge/discharge rate of 2 C/5 C. The cycle life curves of the pouch cell show the number of cycles increases to 2269 cycles with the capacity retention (C.R.) of 80% as the Fe/P ratio increases from 0.93 to 0.99.

To investigate the aging mechanism of the LiFePO4 cathode and graphite anode, changes in the crystalline structure through the charge/discharge reactions were analysed by the synchrotron based X-ray diffraction (XRD) experiments. After long-term cycling tests, the appearance of LiOH and LiOH．H2O phases in the cycled anodes reveals that some Li ion released from the LiFePO4 phase during the charge process did not come back to the FePO4 phase, as shown in Fig. 2. Due to fewer lithium ions, some of the cathode material lost electrochemical activity and this brought down the reversible capacity significantly. In addition, the anode with the Fe/P ratio of 0.95 after 506 cycles has relatively stronger peaks than those of the other samples in Fig. 2(b). It indicates that the decrease in the Fe concentration of stoichiometric LiFePO4resulted in a shortage of lithium ion for the cathode material, and consequently the capacity fading rate accelerated.

In this study, a combination of X-ray diffraction (XRD), X-ray absorption spectroscopy (XAS), and electrochemical testing are used to understand the physical and electrochemical characterizations of the graphite anode and the LiFePO4cathode with the different Fe/P mole ratios during long-term cycling tests.

References

[1] X. Han, M. Ouyang, L. Lu, J. Li, Y. Zheng, Z. Li, Journal of Power Sources,251 (2014) 38-54.

[2] Z. Zhang, T. Zeng, C. Qu, H. Lu, M. Jia, Y. Lai, J. Li, Electrochimica Acta,80 (2012) 440–444.

[3] S.S. Zhang, Journal of
Power Sources, 162 (2006) 1379-1394.
Improved Performance of Graphite/ LiNi0.5Mn1.5O4 Cells Cycled to High Voltage (4.8 V) with Electrolyte Additives
Authors: Lucht Brett L. , Garsuch Arnd , Xu Mengqing , Dong Yingnan
Published: February 2020

There is significant interest in the development of higher energy lithium ion batteries (LIB) for electric vehicles. One method of improving the energy density of lithium ion batteries is to increase the operating voltage of the cells by increasing the working potentials of positive electrode employing for example lithium nickel manganese spinel LiNi0.5Mn1.5O4as the active material. However, cycling of lithium-ion cells to high voltages (~5.0 V vs lithium reference electrode, LRE) proceeds with relatively low (99% and less) coulombic efficiency. Among the primary contributors to the poor cycling efficiency are the electrochemical oxidation reactions of the electrolytes at the high positive potentials of positive electrode.

The failure mechanism of graphite /LiNi0.5Mn1.5O4 cells cycled at 25 oC and 55 oC (1.2 M LiPF6 in 3:7 EC/EMC) have been analyzed by electrochemical methods and ex-situ surface analysis of the electrodes. Graphite /LiNi0.5Mn1.5O4 cells cycle well at 25 oC , but have rapid capacity fade upon cycling at 55 oC. Independent electrochemical analysis of anodes and cathodes extracted from cells cycled at 55 oC suggest that both electrodes have significant capacity loss, although the cathode capacity can be recovered with longer charging times. Ex-situ surface analysis of the cathode with SEM reveals that the bulk cathode particles and the cathode laminate are retained while XPS confirms the presence of a cathode electrolyte interface composed of the decomposition products of the electrolyte. Ex-situ analysis of the anode reveals a thick anode solid electrolyte interphase (SEI), anode delamination, and the presence of Mn. The results suggest that both the anode and the cathode contribute to performance loss in graphite/LiNi0.5Mn1.5O4cells.

We are using this mechanistic information about capacity fade in graphite/LiNi0.5Mn1.5O4 cells to develop novel additives to improve the performance of LiNi0.5Mn1.5O4 cycled to high voltage (4.8 V vs Li). The additives include Lewis basic species which inhibit the thermal decomposition of LiPF6 and cathode film forming additives. Preliminary investigations suggest that incorporation of the novel additives into graphite/ LiNi0.5Mn1.5O4 cells significantly improves the capacity retention upon cycling at high voltage (4.8 V vs Li) and moderately elevated temperature (55 oC). Ex-situ surface analysis of the electrodes after cycling suggest that the additives modify the surface of the LiNi0.5Mn1.5O4cathode via the formation of a stable cathode electrolyte interface (CEI). The presence of the CEI inhibits the oxidation of the electrolyte and dissolution of Mn and Ni from the surface of the cathode particles. The additives, also stabilize the SEI on the anode by preventing Mn deposition on the anode surface and damage of the anode SEI.

The details of our experimental results and our mechanistic interpretation will be presented.
Reversible H+/Li+ Ion Exchange and Structure Stability of Garnet-Type Nb-Doped Li7La3Zr2O12 in Water
Authors: Liu Cai , Wen Zhaoyin , Shen Chen , Zhang Gao xiao
Published: February 2020

The lithium garnet-type oxide is considered as a promising candidate of solid electrolytes to be applied in all solid lithium batteries for its high ion conductivity, chemical stability vs. metal lithium and wide electrochemical potential window. In order to further improve the ion conductivity, dopants like Nb and Ta have been adopted and much progress has been achieved. The total lithium-ion conductivity of Nb-doped Li7La3Zr2O12 was as high as 0.8mS/cm. In this work, its reversible H+/Li+ion exchange reaction and the structural stability in aqueous solutions are systematically investigated.

Cubic garnet phase Li6.25La3Zr1.75Nb0.25O12 (LLNZO) was prepared by a conventional solid-state reaction process at 950oC. The H+/Li+ion exchange reaction of the LLNZO powder was performed in distilled water and the pH value was recorded simultaneously. The process was carried out continuously for 4 times. The lithium content and crystal structure of the garnet powder were measured by ICP and XRD.

The pH value of the distilled water increased quickly after the cubic garnet powder was added in it and finally reached a constant value. The garnet powder was then filtered and the dispersion was repeated with fresh water for deeper ion exchange. The products with different H+/Li+ ion exchange rate were obtained via this way for further dynamics analysis of ion exchange process. The remaining lithium content of the garnet powder was gradually declined after the ion exchange happened. FTIR spectra was tested to identify the ion exchange. It was found that the cubic garnet phase was maintained even the ion exchange rate of lithium ion was up to 74.8% and was confirmed by the high resolution lattice imaging and XRD analysis. The stoichiometry of garnet-type Li6.25-xHxLa3Zr1.75Nb0.25O12, as well as the crystal lattice parameters, was evolved with the H+/Li+ ion exchange reaction in aqueous solutions. It is noticeable that the reverse ion exchange of H+ by Li+was achieved by controlling the reaction temperature, pressure, the lithium concentration and the pH of the solutions. The successful re-exchange indicated the high stability of the Nb doped cubic garnet phase.

Fig.1 XRD results of Li6.25La3Zr1.75Nb0.25O12powder and products from distilled water treatment

Fig.2 The evolution of the constant pH value and remaining lithium content versus water treating stages

Fig.3 TEM and electron diffraction images of Li6.25La3Zr1.75Nb0.25O12with 74.8% lithium ion exchange

Reference

(1) Truong, L. and V. Thangadurai (2011). Chemistry of Materials 23(17): 3970-3977.

(2) Shimonishi, Y., A. Toda, et al. (2011). Solid State Ionics 183(1): 48-53

(3) Ishiguro, K., Y. Nakata, et al. (2013). Journal of the Electrochemical Society 160(10): A1690-A1693.
Electrolyte for Vanadium Redox Flow Batteries: The Role of Complexing Counter Ion
Authors: Roznyatovskaya Nataliya , Noack Jens , Fischer Peter , Tübke Jens , Pinkwart Karsten
Published: February 2020

Flowable electrochemical systems, such as redox flow batteries are alternative technologies for grid-scale applications, although their high operational and initial costs, safety concerns and limited cycle-life still prevent them from free entrance to the market. All-vanadium redox flow battery (V-RFB) employs two redox couples of V(IV)/(V) and V(II)/(III) in highly acidic media with sulphate or mixed counter anions [1]. The operation of V-RFB based on sulphuric acid electrolyte is limited by low thermal stability of catholyte, i.e. by processes of dimerization or polymerization of V(V) species, which are poorly understood and low kinetics of vanadium electrode reactions at carbon electrodes.

The V(IV) and V(V) ions are known to be complexated by sulphate anions in acidic media [2], V(V) seems to be stabilized in concentrated sulphuric acid [3]. In this work the non-complexing perchlorate anion has been used to avoid the competition for vanadium ion coordination. Several catholytes including 0.5M of V(IV)/V(V) have been prepared in 1M sulphuric acid from vanadyl sulphate salt and in 1M perchloric acid by ion exchange reaction and electrooxidation at graphite felt electrode. The V(IV)/V(V) electrode reactions have been investigated by cyclic voltammetry at pre-oxidized glassy carbon electrode (Figure 1). The V(IV) oxidation and V(V) reduction are found to proceed more reversibly in sulphate-containing electrolyte. The oxidative conversion of V(IV) have been characterized in-situ in visible and near-infrared range during spectoelectrochemical measurement in three-electrode cell at reticulated glassy carbon electrode.

Both of the studied systems have been compared as electrolytes in the 40 cm2 cells using carbon felt electrodes and Nafion separator membrane. The charge-discharge tests performed at current densities from 25 to 50 mA/cm2 revealed that both systems have comparable power densities during charge, however the sulphate-containing electrolyte has higher power density during discharge.

The test of thermal stability revealed the higher stability of the 0.5 M V(V) in sulphuric acid compared to equimolar V(V) solution in perchloric acid.

The results can be useful for careful adjustment of vanadium ion coordination in electrolyte for improved V-RFB. Being impractical as a neat electrolyte solution the vanadium-perchlorate system can be used to study the effect of other, i.e. strongly complexing ligands and can serve as a reference system.

1. P. Leung et al. RSC Adv ,2, 10125 (2012)

2. N. Kausar, R. Howe, M. Skyllas-Kazacos, J. App. Electrochem
., 31, 1327 (2001)

3. J. Krakowiak, D. Lundberg, I. Persson, Inorg. Chem
., 51, 9598 (2012)

  Figure 1: Cyclic voltammogramms in Vanadium (IV) and (V) solution with various counter ions.

Figure 1
Novel Synchrotron-Based Experimental and Analytical Approaches for Energy Materials Characterisation
Authors: Chapman Karena W , Borkiewicz Olaf J , Wiaderek Kamila M , Chupas Peter J
Published: February 2020

To develop an understanding of the fundamental phenomena that govern battery performance and failure, one must be able to probe and ultimately decouple electronic, chemical and structural transformations that span broad length and time scales, from atoms to electrodes. This presents a significant characterization challenge. Often characterization tools typically provide incomplete insights, only addressing a fraction of the relevant length/time scales or some aspects of the chemical, structural, or electronic states. Only through the development and application of a suites of complementary tools sensitive to aspects of structure, chemistry, electronic state and dynamics on appropriate scales, can we develop the comprehensive understand electrode performance needed to design improved systems. Synchrotron light sources support a broad spectrum of advanced scattering, spectroscopic and imaging-based characterization tools that can probe many different facets of battery operation at the atomic, particle and electrode level. Through the development of new synchrotron-based experimental and analytical approaches, we have been able to gain new insights into the structure of promising electrodes and electrolytes, with chemical sensitivity, across multiple length scales.
N, N-Diethyltrimethylsilylamine (DETMSA) As Electrolyte Additive for Si Based High Energy Lithium-Ion Batteries
Authors: He Meinan , Hu Libo , Wang Yan , Xu Kang , Zhang Zhengcheng
Published: February 2020

Silicon is a highly promising high capacity anode material for high energy lithium-ion batteries for electric vehicle application. Great progress has been made especially in the area of material level on the nano scale.1 However, the electrolyte research tailored to further improve the performance of the Si anode is limited.2 In this paper, we present a new electrolyte additive N, N-diethyltrimethylsilylamine (DETMSA) which showed great improvement over the conventional carbonate electrolyte using the fluoroethylene carbonate as additive. Our experiment data showed that with addition of 0.5 wt. % of DETMSA to the baseline electrolyte 1.2 M LiPF6 EC/EMC+10% FEC, the Li/Si-graphite cell gained a 10% improvement in capacity retention increase with high coulombic efficiency at room temperature. The functioning mechanism of the new electrolyte additive for Si anode was investigated by the XPS, SEM/EDX and FT-IR. 3

References:

 

He, M., Sa, Q., Liu, G., & Wang, Y. (2013). Caramel Popcorn Shaped Silicon Particle with Carbon Coating as a High Performance Anode Material for Li-Ion Batteries. ACS applied materials & interfaces, 5(21), 11152-11158.

Zhang, S. S. (2006). A review on electrolyte additives for lithium-ion batteries.Journal of Power Sources, 162(2), 1379-1394.

Zhang, S., Ding, M. S., Xu, K., Allen, J., & Jow, T. R. (2001). Understanding solid electrolyte interface film formation on graphite electrodes. Electrochemical and Solid-State Letters, 4(12), A206-A208.
Scandium-Doped LSM Anode for Steam Electrolysis in a Proton-Conducting Solid Oxide Electrolyzer
Authors: Chen Shigang , Xie Kui , Wu Yucheng
Published: February 2020

Perovskite La0.8Sr0.2MnO3-δ has been widely used as anode for proton conducting solid oxide steam electrolyzer; however, the insufficient catalytic activity still restricts the activity for electrochemical oxidation of steam. In this work, Sc-doped anode material La0.8Sr0.2Mn1-xScxO3-δ (x=0, 0.02, 0.05, 0.08, 0.1) with the aim of enhancing anode performance is studied. Combined characterization using XRD, TEM, XPS, SEM and EDS confirmed the successful partial replacement of Mn by Sc in B site. The doping of Sc remarkably improves ionic conductivity while accordingly decreases the mixed conductivity due to the increase of oxygen vacancies indicated by TGA and XPS. Electrochemical measurements and ionic conductivity measurements demonstrate LSMS0.05 has the most optimized polarization properties. With LSMS0.05 anode, the Faradic efficiency is maximized to 80% and accordingly enhanced by 25% compared with the electrolyzer with LSM anode for high temperature steam electrolysis by exposing anode to 5%H2O/air.
Series-Connected Substrate-Integrated Lead-Carbon Hybrid Ultracapacitors with Voltage-Management Circuit
Authors: Banerjee Anjan , Srinivasan Ramesh , Shukla Ashok Kumar
Published: February 2020

Cell voltage for a fully-charged substrate-integrated lead-carbon hybrid ultracapacitor is about 2.3 V. Therefore, for applications requiring higher dc voltage, several of these ultracapacitors need to be connected in series. However, voltage distribution across each series-connected ultracapacitor tends to be uneven due to tolerance in capacitance and parasitic parallel-resistance values. Accordingly, voltage-management circuit is required to protect constituent ultracapacitors from exceeding their rated voltage. A design of the 12 V substrate-integrated lead-carbon hybrid ultracapacitor by series-connected six 2 V cells with co-located terminals is presented in Figure 1 (a). The schematic diagram of voltage-management cell-balancing circuit for the ultracapacitor is shown in Figure 1 (b). The ultracapacitor with the voltage-management circuit is tested, and the data are summarized in Figure 2. It is clearly seen that in steady state, the voltage tends to distribute uniformly across the individual ultracapacitor in the series arrangement.

Figure 1
Influence of CO2 on the Cathode Performance and Stability of La1-XSrxCo0.2Fe0.8O3-Î´ in Solid Oxide Fuel Cells
Authors: Cetin Deniz , Yu Yang , Luo Heng , Lin Xi , Pal Uday Bhanu , Basu Soumendra Nath , Gopalan Srikanth
Published: February 2020

La1-xSrxCo0.2Fe0.8O3-δ is a high performance cathode material due to its mixed ionic and electronic conducting behavior that has widely been in used in solid oxide fuel cells (SOFCs). It has been shown that Sr segregates out of the lattice to the surface of the material and creates new phases in forms of SrO and SrCO3. Even though these surface phases are known to be insulators, their effects on oxygen surface exchange, oxygen transport, and on the overall cell performance remain as open questions.

In order to address the above issues, electrochemical impedance spectroscopy (EIS) was used to study cathode performance on cells of the configuration La1-xSrxCo0.2Fe0.8O3-δ (LSCF)/ gadolinium-doped ceria (GDC) barrier electrolyte layer/ yttria-stabilized zirconia (YSZ) electrolyte/porous (La0.8Sr0.2)0.95MnO3-YSZ counter electrode. LSCF performance was investigated in a dual atmosphere set up in CO2–free air and in the presence of CO2 at the intermediate operational temperature range of 600-800°C as a function of time.
Electrochemistry and Transport of Redox Active Polymers Across a Porous Separator: Towards a Size-Selective Strategy for Non-Aqueous Redox Flow Batteries
Authors: Gavvalapalli Nagarjuna , Hui Jingshu , Lichtenstein Timothy , Cheng Kevin , Moore Jeffrey S , Rodríguez-López Joaquín
Published: February 2020

Non-aqueous redox flow batteries (NRFBs) are a potentially viable alternative to their aqueous counterparts. NRFBs offer a wider range of redox active species and electrolytes available for their design, thus increasing the chance that highly soluble and stable redox couples can be used. However, the lower ionic conductivity observed in NRFBs due to the use of organic electrolytes in combination with ion-exchange membranes, which are often not designed for these environments, have slowed down their wide-scale implementation. Separating the redox active species in the electrolyte compartments by size-exclusion without greatly impeding the transport of supporting electrolyte is a potentially powerful alternative to the use of poorly-performing ion-exchange membranes. We will present our advances towards implementing such strategy using viologen-based redox active polymers (RAPs) together with a commercial off-the-shelf porous separator such as Celgard™ [1]. These RAPs, with molecular weight between 21 and 318 kDa exhibited size-dependent transport across the porous separator, while retaining many of the attractive properties of a non-aqueous redox couple: high solubility (up to 2.7 M in acetonitrile), facile electron transfer even at high concentration, 94-99% charge/discharge efficiency, and cyclability without evidence of decomposition. Preliminary testing using a stirred cell showed the possibility of integrating RAPs and porous separators into a working device that achieved close to nominal open circuit voltage, stable charge/discharge over several hours and crossover on the order of only 2%. These characteristics, as well as size-dependent transport measurements strongly suggest that porous separators can be used to allow an unimpeded transfer of supporting electrolyte while discriminating the RAP component. Advances in the synthesis of RAPs with other functionalities and their evaluation in flow conditions will be presented.   

[1] Gavvalapalli, N.; Hui, J.; Cheng, K.; Lichtenstein, T.; Shen, M.; Moore, J.S.; Rodríguez-López, J. J. Am. Chem. Soc. 2014, 136, 16309-16316
Fabrication and Study of All-Solid-State Li-Ion Batteries Based on Self-Organized Titania Nanotubes
Authors: Djenizian Thierry , Plylahan Nareerat , Letiche Manon , Barr Maissa
Published: February 2020

The electrochemical storage performances of devices are seriously compromised when decreasing the size of the components down to the micrometer scale. This is particularly true for the development of microbatteries which are rapidly reaching their performance limit in terms of energy density and power density because of its two-dimensional geometry thin film technology impeding fast electron/ion transport in the electrodes and higher interfacial charge transfer resistances. To overcome these issues, all-solid-state 3D microbatteries have attracted interest while remaining a technological challenge since they require the marriage between materials science, electrochemistry, and microfabrication processes. In this context, titania nanotubes (TiO2NTs) have been extensively studied as a 3D negative electrode for lithium-ion batteries (LIBs). These self-supported nanostructured electrode show a suitable nanotubular morphology to fabricate microbatteries with high energy and power densities (1-4).

In this work, the Li+ insertion into anatase TiO2nts using PEO-based polymer as electrolyte has been studied by cyclic voltammetry (CV) and chronoamperometry (CA). The electrochemical characterizations reveal that that the Li+ storage is dominated by the bulk diffusion (into the lattice) with the contribution of the pseudo-capacitive effect at the surface. Beside the mechanistic investigations, we report the fabrication of the first all-solid-state Li-ion batteries based on titania nanotubes as negative electrode, PMMA-(PEO)5  as polymer electrolyte and LiNi0.5Mn1.5O4 as positive electrode (Fig. 1). The electrochemical performance of this new thin film microbattery will be presented and discussed (Fig. 2).

References

1. B. L. Ellis, P. Knauth, and T. Djenizian, Adv. Mater, 26, 3368, (2014).

2. T. Djenizian, I. Hanzu, P. Knauth, J. Mater. Chem.,  21, 9925, (2011).

3. N. Plylahan, M. Letiche, M. Barr, and T. Djenizian, Electrochem. Commun., 43, 121 (2014).

4. N. Plylahan, M. Letiche, M. Barr, B. Ellis, S. Maria, T. Phan, E. Bloch, P. Knauth, and T. Djenizian, J. Power Sources, 273, 1182 (2015).

Figure 1
Rational Design of Nanocatalysts for Fuel Cell Reactions
Authors: Guo Shaojun
Published: February 2020

Engineering nanocrystals with size, shape, composition and structure control for enhancing oxygen reduction reaction (ORR) and small molecule oxidation reactions is highly desirable for promoting the development of fuel cell devices. In this presentation, I will focus on my recent advances in rational design and controlled synthesis of high-quality multicomponent nanocrystals for enhancing ORR and small molecules oxidation reactions. I will start with three examples on how to engineer FePt NWs, FePtPd/FePt core/shell nanowires (NWs) and graphene-FePt nanoparticles (NPs) composite for getting advanced Pt-based catalysts for ORR with extremely high activity and stability. After that, I will move to non-Pt catalysts such as graphene-Co/CoO NPs and M/CuPd NPs (M=Ag, Au), which exhibit comparable and even higher ORR activity and stability than commercial Pt catalyst. Finally, I will show two interesting examples on how to engineering trimetallic NPs and NWs for enhancing methanol and formic acid oxidation reactions.
Polarization Analysis Based on Realistic Lithium Ion Battery Electrode Microstructure Using Numerical Simulation
Authors: Yan Bo , Lim Cheolwoong , Song Zhibin , Kim Youngsik , Zhu Likun
Published: February 2020

The performance of lithium ion battery (LIB) is limited by the inner polarization and it is important to understand the factors that affect the polarization [1]. This study focuses on the polarization analysis based on realistic 3D electrode microstructures. A c++ software was developed to rebuild and mesh the microstructure of cathode and anode electrodes through Nano-CT and Micro-CT scanned images respectively. As a result, the LIB model was composed of electrolyte, cathode and anode active materials and current collectors. By employing 3D finite volume method (FVM), another c++ code was developed to simulate the discharge and charge processes by solving coupled model equations. The simulation revealed the distribution of physical and electrochemical variables such as concentration, voltage, current density, reaction rate, et al. In order to explore the correlation of local effects and electrode structural heterogeneity, the cathode electrode were divided equally into 8 sub-divisions, of which the porosity, tortuosity, specific surface area were calculated. We computed the polarizations in the sub-divisions due to different sub-processes, i.e., the activation of electrochemical reactions and charge transport of species. As shown in Fig. 1, the tortuosity is very irregular because of unevenly distributed cathode particle size and packing pattern with low porosity. There are no exact and direct relations among porosity, tortuosity and specific surface area. Fig. 2 shows that the polarizations are related to the porosity in sub-divisions. The knowledge from the study will help to figure out the mechanism of polarization and power loss in LIB, which could be useful to improve LIB design and manufacturing.

Acknowledgments: This work was supported by US National Science Foundation under Grant No. 1335850.

References:

1. A. Nyman, T. G. Zavalis, R. Elger, M. Behm and G. Lindbergh, Journal of The Electrochemical Society, 157, A1236 (2010).

Figure 1
(Invited) Improvement of Electron Transfer Rate at Metal/Organic Interfaces Using Pd Atomic Layers
Authors: Ikeda Katsuyoshi
Published: February 2020

Chemical modification of a metal electrode is one of promising methods to realize various electrochemical functions.  For example, photocurrent generation may be achieved by surface modification of a metal electrode with chromophores.  Electrocatalytic activity may be enhanced by immobilization of catalyst molecules on a metal surface.  However, these molecule-induced functionalities are strongly affected by metal/organic interface properties.  In particular, the electronic conductance at metal/organic interfaces may be one of essential issues to limit the efficiency of the electrochemical functions.  In this work, the electron transfer kinetics at metal/organic interfaces was experimentally investigated using Cobalt porphyrin (CoTPP) modified Au electrodes.  To control the connection between Au and CoTPPs, bridge monolayers were formed on the electrode using various thiol- or isocyanide-molecules, and CoTPPs were then immobilized on top of the bridge layers.  The electron transfer rate for oxygen reduction reaction (ORR) on CoTPPs was thoroughly investigated for various modified electrodes using the rotating disk electrode (RDE) method. 

The interface structure between the Au electrode and the molecular layers was controlled with and without forming Pd monoatomic layers (Fig. (a)).  The Pd overlayer on Au surface (Au/PdML) was prepared by the underpotential deposition (UPD) method.  The Au and Au/PdML electrodes were self-assembly covered with various diisocyanide molecules such as TPDI (4,4’-terphenyl diisocyanide).  CoTPPs were attached on these molecular layers.  Figure (b) shows Tafel plots for ORR on CoTPPs on SAM-covered Au or Au/PdML electrode.  Electron transfer rate on the Au/PdML was much faster than that on the Au while the Tafel slop was not affected by the presence of Pd overlayer.  This result indicates that the performance of chemically functionalized electrodes can be improved by the metal/organic interface control.

Figure 1
New Push-Pull, Multicomponent Phthalocyanine-Based Photsensitizers for DSSCs
Authors: de la Torre Gema , Torres Tomas , Fazio Ettore , López-Pérez Ana
Published: February 2020

In the last few years, phthalocyanines (Pcs) have attracted strong interest in the field of dye-sensitized solar cells (DSSCs).1 A3B phthalocyanines such as TT40,2 functionalized with non-aggregating bulky substituents at three isoindole rings (i.e. A) and a highly directional carboxylic acid linker at the other isoindole (i.e. B), have reached photovoltaic power conversion efficiencies over 6% in hybrid devices with mesoporous TiO2. Although Pcs are more stable and strongly absorbing than porphyrin (Por) analogues, the latter have shown much more efficient as dyes for DSSCs, especially those with a “push-pull” substitution pattern, such as SM315.3 In the search for new hints for the rational molecular design and optimization routes, we aim to explore if this “push-pull “ pattern also applies to Pcs as a tool to achieve efficient sensitization of TiO2. Therefore, we have synthesized donor-π-acceptor Zn(II)Pcs such as 2, holding one electron-donor, aminophenyl–type unit and a carboxyethynyl moiety as acceptor and anchoring group, starting from ABAB Pc 1 recently reported by us.4 This Pc consist of two opposite isoindoles functionalized with bulky bis(trifluoromethyl)phenyl groups, which afford solubility to the molecule and hamper its aggregation, and two faced isoindoles containing iodine atoms, which can be used  for further chemical transformation into the target donor-π-acceptor system 2.  Additionally, we have undertaken the preparation of Zn(II)Por-Zn(II)Pc dyads 3, which absorb a broad part of the visible spectrum and show cascade-charge transfer capabilities, for the sensitization of TiO2.  In these ensembles, the Zn(II)Por unit, functionalized with three arylamino moieties, features as the ultimate electron donor unit, and the carboxy Zn(II)Pc is responsible of the direct  injection of electrons to the semiconducting film.

1 Martinez-Diaz, M. V.; de la Torre, G.; Torres, T.  Chem. Commun.
, 2010, 46, 7090.

2 Ragoussi, M.-E. ; Cid, J.-J. ; Yum, J.-H. ; de la Torre, G. ; Di Censo, D. ; Grätzel, M. ; Nazeeruddin, M. K.; Torres, T. Angew.
Chem. Int. Ed.
2012, 51, 4375.

3 Mathew, S.;  Yella, A.;  Gao, P.;  Humphry-Baker, R.;  Curchod, B. F. E.;  Ashari-Astani, N.; Tavernelli, I.;  Rothlisberger, U.;  Nazeeruddin, M. K. ; Grätzel, M.;  Nature Chem.
2014, 6, 242.

4 Fazio, E. Jaramillo-Garcia, J.; de la Torre, G.; Torres, T. Org. Lett., 2014, 16, 4706.

Figure 1
Structure and Function Relationships of Heme-Based Gas Sensors and Heme-Redox Sensors
Authors: Shimizu Toru
Published: February 2020

The heme-iron complex acts as the gas (O2, NO and CO)-sensing site in a heme-based gas sensor. This function is distinct from those of well-known heme proteins in which the heme-iron complex is the functional active center (e.g., the O2-carrying hemoglobin; the electron transfer mediator, cytochrome c; and the monooxygenase, cytochrome P450). The heme-based gas sensor, in contrast, is composed of an N-terminal heme-bound gas-sensing domain and a C-terminal functional domain. The association/dissociation of a gaseous molecule to/from the heme-iron complex of a gas sensor triggers the functional domain to regulate various physiologically important functions (e.g., guanylate cyclase activity, phosphodiesterase activity, histidine kinase activity, methyl-accepting chemotaxis, and transcription). There are also heme-redox sensors; they have the same domain arrangement as the heme-based gas sensors, and are regulated by the heme-iron redox state. Many of the molecular mechanisms underlying the intra- and inter-molecular signal transductions of gas and redox sensors have been elucidated. I summarize our existing knowledge of the heme-based gas (O2, NO and CO) sensors and heme-redox sensors. I then delineate the structure/function relationships and common characteristics of the bacterial, archaeal and mammalian heme-based gas sensors and heme-redox sensors.

Acknowledgements: This work was in part supported by Supported in part by Grants-in-Aid from Shantou University Medical College and from the National Natural Science Foundation of China (NSFC) (No. 31170736)

References:  Martínková, M. et al.
J. Biol. Chem
. 288, 27702-27711 (2013); Shimizu, T.
Biosensors

3, 211-237 (2013); Igarashi, J. et al.
Handbook of Porphyrin Science
(Kadish, K. M. et al. Eds.) Vol. 15, Chap. 73, pp.399-460 (2011).