bluuebunny/crossref_metadata_2025 huggingface dataset:
Photoluminescence Properties of Pr3+-Activated Ca-Based Perovskites Prepared By Amorphous Complex Method Using Aqueous Metal Complex Solutions
Authors: Sato Yasushi , Ohashi Yuta , Iguchi Yuta , Watanabe Tomohiro , Sugino Ayami , Kakihana Masato
Published: February 2020

Ca-based perovskite phosphors activated by rare-earth ions have attracted considerable attention recently as prospective materials for various optoelectronic applications. Crystal structure of Ca-based perovskites is highly distorted from the ideal cubic perovskites as SrTiO3. Thus, strong ff-emissions of rare-earth ions should be derived from low site-symmetry of Ca site. In addition, photoluminescence properties of these phosphors are dependent on not only crystal structure of the host materials, but also preparation condition of the samples. Conventional solid-state reaction (SSR) method is not fit for the synthesis of phosphors with complicated compositions because the degree of cation mixing is relatively low due to slow interdiffusion of the cations. In this study, we investigated the preparation of Pr3+-activated Ca-based perovskite phosphors via an aqueous-solution process using metal complex solutions in order to improve the photoluminescence properties of these phosphors. Pr3+-activated CaTiO3 and CaSnO3 phosphors were prepared by amorphous metal complex (AMC) method using stable water-soluble Ti4+ and Sn4+ complexes coordinated to lactic acid. Especially, we developed a new stable water-soluble Sn4+ complex synthesized from SnCl4·nH2O. Photoluminescence properties of Pr3+-activated CaTiO3 and CaSnO3 under UV irradiation were significantly sensitive for the small deviation of the cation ratios of Ti/Ca and Sn/Ca. When the cation ratios in both the phosphors were less than 1.00, ff-emissions from the phosphors prepared by AMC method were low, compared with the phosphors prepared by SSR method. In contrast, when the cation ratios were precisely controlled from 1.00 to 1.05, ff-emissions of the phosphors prepared by AMC method were higher than those prepared by SSR method. Especially, Pr3+-activated CaSnO3 prepared by AMC method at the optimum condition showed high emission intensity under UV irradiation that was 1.9 times higher than those by SSR method (Fig .1). This work was partially supported by Grant-in-Aid for Scientific Research (C) (no. 15K06445) from MEXT, Japan. This work was also partially supported by the cooperative research program of the “Network Joint Research Center for Materials and Devices”.

Figure 1
(Invited) Development of High Temperature Materials and Technologies for Electrochemical Storage and Conversion
Authors: Soloveichik Grigorii L.
Published: February 2020

The Advanced Research Projects Agency (ARPA-E) funds high risk, high reward transformational research to reduce energy related emissions, reduce imports of energy from foreign sources, improve energy efficiency across all economic sectors, and ensure US technological lead in advanced energy technologies, including electrochemical energy storage and transformation for grid scale and automotive applications.

High temperature electrochemical technologies and supporting materials (membranes, current collectors, seals, etc.) play an important role in electrochemical (batteries with molten electrodes and molten salt electrolytes) and chemical (electrosynthesis of fuels) energy storage and energy conversion (intermediate and high temperature solid oxide and proton conducting fuel cells and electrolyzers). In addition, high temperature electrochemical technologies to process and recycle metals such as aluminum, titanium, and magnesium are important for advanced manufacturing. The use of high temperatures allows for utilization of ion conducting materials, electrolytes and electrocatalysts, which cannot be utilized at ambient conditions due to low conductivity or activity respectively. Current challenges in high temperature electrochemistry are increasing ionic conductivity of liquid and solid electrolytes to decrease working temperatures and expand material compatibility, improving activity and selectivity of electrocatalysts to decrease energy consumption and costs, increasing power density of stacks to decrease the capital costs, and optimizing the balance of system, which is extremely important for smaller scale devices.

ARPA-E funded and currently funds multiple projects targeting high temperature electrochemical processes and development of materials compatible with these processes through OPEN, IDEAS and focused programs. The Modern Electro/Thermochemical Advances in Light Metals Systems (METALS) targets technologies that may provide inexpensive light metal materials for lightweight vehicles and aircraft. The Reliable Electricity Based on Electrochemical Systems (REBELS) program is focused at intermediate temperature fuel cells that operate between 200-500oC and includes cell capable to produce liquid fuels along with electricity to support the distributed energy generation for more reliable and flexible smart grid. The Renewable Electricity to Fuels through Utilization of Energy-dense Liquids (REFUEL) program seeks to fund the development of intermediate and high temperature electrosynthesis and fuel cells technologies to produce and utilize carbon-neutral fuels. This presentation will also highlight high temperature battery technologies using molten metal anodes funded by ARPA-E.
Meso-Scale Model of Li2O2 Formation in Li-O2 Batteries: Compactness of Thin Film and Its Link to Charge Transport Mechanism
Authors: Yin Yinghui , Zhao Ruijie , Deng Yue , Franco Alejandro A.
Published: February 2020

Owing to its high theoretical capacity, Li-O2 batteries have attracted much attention during the past decades. However, in the state-of-art, the discharge capacity of a Li-O2 cell is far behind the theoretical value. The insulating nature of the discharge product Li2O2 can be one of the main issues and the maximum distance for electron tunneling through this thin film is less than 10 nm according to first-principle calculation.1 Nevertheless, the experimental finding of 40 nm Li2O2 film by Yang et al. breaks the limitation electron tunneling, which may imply that there may be other factors accounting for the thick Li2O2 film.2

In the present work, we simulated the growth of Li2O2 thin film during the discharge process of a Li-O2 battery and studied the influences of catalyst and LiO2 diffusion rate with a meso-scale model. On the basis of kinetic Monte Carlo method, this model combined a stochastic description of mass transport and a detailed elementary reaction We found that : (1) the interplay between diffusion kinetics and reaction kinetics influenced strongly the ordering of the Li2O2 thin film. With the presence of catalyst, the formed Li2O2 showed a lower degree of ordering and is more likely to be amorphous owning to the fast kinetics; (2) the mobility of LiO2 ion pair, which depends largely on the nature of the electrolyte, also has impacts on the homogeneity of the compactness of Li2O2 thin film. These results are of high importance to develop a better understanding on the role of catalyst and reaction kinetics in the Li-O2batteries.

References

[1] Viswanathan, V.; Thygesen, K. S.; Hummelshøj, J. S.; Nørskov, J. K.; Girishkumar, G.; McCloskey, B. D.; Luntz, A. C. J. Chem. Phys.
2011, 135 (21), 214704.

[2] Yang, C.; Wong, R. A.; Hong, M.; Yamanaka, K.; Ohta, T.; Byon, H. R. Nano Lett.
2016, 16 (5), 2969–2974.

[3] Blanquer, G.; Yin, Y.; Quiroga, M. A.; Franco, A. A. J. Electrochem.
Soc.
2016, 163(3), A329–A337.

[4] Yin, Y,; Zhao, R.; Deng. Y and Franco, A. A. J. Phys. Chem.Lett. (Submitted)
Magnesium Ethylenediamine Borohydride As Solid-State Electrolyte for Magnesium Batteries
Authors: Roedern Elsa , Kühnel Ruben-Simon , Remhof Arndt , Battaglia Corsin
Published: February 2020

Efficient magnesium electrolytes are crucial in order to realize rechargeable magnesium batteries, which are an important contender for post-lithium-ion-battery technology.1,2 Due to the divalent positive charge carried by the Mg2+ ion, magnesium mobility is difficult to achieve and so far Mg ion conductivity in inorganic solids has only been reported for few systems and typically, conductivities above 10-5 Scm-1
are only reached above 400 °C, see Figure 1.

In this work, we demonstrate that partially chelated ethylenediamine magnesium borohydride complexes show promise as solid-state Mg conductors with unprecedented high conductivity of up to 6x10-5 Scm-1already at 70 °C. The compounds are easily prepared by a mechanochemical reaction and allow for reversible Mg plating/stripping at 60 °C, which is recognized to be a major challenge in magnesium ion batteries.

While the electrochemical stability, limited by the ethylenediamine ligand, must be improved to reach competitive energy densities, our results demonstrate that partially chelated Mg2+complexes represent a promising platform for the development of an all-solid-state magnesium battery.

 References

1 D. Aurbach, G. S. Suresh, E. Levi, A. Mitelman, O. Mizrahi, O. Chusid and M. Brunelli, Adv. Mater., 2007, 19, 4260–4267.

2 H. D. Yoo, I. Shterenberg, Y. Gofer, G. Gershinsky, N. Pour and D. Aurbach, Energy Environ. Sci., 2013, 6, 2265.

3 S. Ikeda, M. Takahashi, J. Ishikawa and K. Ito, Solid State Ionics, 1987, 23, 125–129.

4 N. Imanaka, Y. Okazaki and G. Adachi, J. Mater. Chem., 2000, 10, 1431–1435.

5 N. Imanaka, Y. Okazaki and G. Adachi, Ionics, 2001, 7, 440–446.

6 S. Higashi, K. Miwa, M. Aoki and K. Takechi, Chem. Commun., 2014, 50, 1320–2.

Figure 1
Unraveling the Potassium Ion Storage Mechanism in Graphite Foam
Authors: Liu Ji Lei
Published: February 2020

The growing demands for electric automotive and regenerative energy storage applications, and the increasing caring for climate change and pollution, drive the search for high-performance electrochemical power sources that are also safe to operate, economically viable and environmentally friendly. Compared to LIBs and NIBs, very little is known about the electrochemical storage mechanism of KIBs. Here in operando studies including in-situ Raman and in-situ XRD characterizations, ex-situ XPS analysis and ab initio calculations are carried out for correlating the real-time electrochemical K+ intercalation process with structure/component evolution. Our results reveal three distinct intercalation stages are involved for K+ storage in few-layered graphene, corresponding to the formation of different GIC stages (e.g., KC36, KC24 and KC8). The K+ diffusion coefficients are found to be GIC stage dependent based on GITT and EIS results, corroborating the diversity in K+ intercalation pathways. The establishment of clear property-structure relations in this work promotes better understanding of the K+ storage mechanism in graphite and opens up a new exciting direction for designing new materials for K-ion Batteries.
Strain Engineering to Control the Electrochemistry of Battery Electrodes
Authors: Muralidharan Nitin , Brock Casey , Walker Greg , Pint Cary L.
Published: February 2020

Strain engineering has transformed applications in the semiconductor electronics industry, but has not been widely explored as a tool for electrochemical applications. Our early studies have demonstrated for the first time that mechanical strain applied across interfaces of engineered 2-D nanomaterials or externally applied to pseudocapacitive electrodes can result in deviations in the energetics and kinetics of Faradaic charge storage reactions [1-2]. Here, we present results that extend this idea to vanadium pentoxide (V2O5) due to its well-known capability to function as a cathode for the intercalation of lithium ions. To characterize the role of strain in modulating the lithium insertion properties, we use atomic layer deposition (ALD) to prepare ultrathin coatings of crystalline V2O5 on the surface of superelastic NiTi shape memory alloy surfaces. As a key challenge in characterizing the role of strain is the ability to assess electrochemical properties in a fixed strain state, we exploit the capability of NiTi to "lock-in" strain in the elastic regime, which extends up to ~ 15% strain. This enables us to directly measure the average strain transferred to the V2O5 material, and correlate this to the observed electrochemical properties. Through electrochemical tests, we observe over 50 mV shift in the electrochemical potential that is correlated to strain, and over 2X change in the diffusion coefficient of lithium ions. We further build a semi-quantitative model for strain modulated battery performance that is supported by density functional theory calculations. Overall, this work demonstrates new degrees of freedom to design or engineer electrodes for energy storage by using pre-strained or strain-engineered electrode materials.

References:

[1]. N. Muralidharan, R. Carter, L. Oakes, A.P. Cohn, and C.L. Pint*, "Strain engineering to modify the electrochemistry of energy storage electrodes," Sci. Rep. 6, 27542 (2016).

[2]. L. Oakes, R. Carter, T. Hanken, A.P. Cohn, K. Share, B. Schmidt, and C.L. Pint*, "Interface strain in vertically stacked two-dimensional heterostructured carbon-MoS2 nanosheets controls electrochemical reactivity," Nat. Commun. 7, 11796 (2016).
A Better Understanding of Batteries: Manufacturing and Simulation of Li-Ion Cells
Authors: Chepyala Seshuteja , Moss Pedro L. , Weatherspoon Mark H.
Published: February 2020

High energy lithium (Li) batteries are fast becoming a promising energy market for applications in the automotive and portable power industries. In the search for better specific energy and lower cost to manufacture the batteries, novel methods are being researched to overcome the design and operational entices before becoming commercially viable. One of these methods to achieve the above said goals is to manufacture the cells and compare the manufactured cell with its model.

This paper proposes battery cell manufacturing and laboratory level testing combined with advance modeling techniques to obtain a correlation for the cell life and stability characteristics data obtained by both simulation and manufactured cell. The batteries are made in the laboratory using the proven and tested methods and the cells are assembled after performing detailed analysis on the surface area and BET analysis of the electrodes. The cells are modeled in COMSOL Multiphysics to estimate the cycle life and stability and to check whether the simulated data is the same as the estimated data. This latter model is then used to check the performance of the cell. The COMSOL simulations are done for different cells and the data is compared with their respective manufactured cell data. The cells are prepared using various available electrode materials and extensive study is carried out regarding the assembly and manufacturing.

Preliminary tests of cathode electrode half cells using lithium iron phosphate (LFP) have achieved good results and the theoretical and practical specific capacities are similar as shown in Figure 1. We are able to achieve the specific capacity of LFP half-cell close to 135mAh (densified) as compared to the theoretical capacity of 155mAh. The cells should show similar charge discharge performance when modeled in COMSOL and achieve the similar results when the cells are tested. The results are discussed and recommendations made on battery dimensioning using the specifications observed.

Figure 1
Towards a More Realistic Model: Variational Multiscale Modeling of Lithium-Ion Battery
Authors: Moradi Mohammadmoein , Liu Lin
Published: February 2020

Batteries are one of the important energy storage sources for a changing world. Applications of battery use as an energy supply and storage device have been extended from small portable electronic devices to big transportation vehicles. Modeling and simulation of lithium ion batteries have been carried out across various disciplines to investigate different aspects of such batteries, from electrochemical performance to design optimization simulations. Electrochemical based energy storage devices, such as Li-ion battery, are one of the physical systems which are representing multiscale phenomena. In order to get a more realistic model, the effect of microscale phenomena of a battery system should be accounted for in the total response of the system. Multiscale modeling methods have been proposed for the analysis of systems representing multiscale phenomena. The missing part in the simulation of battery systems is to correlate ongoing phenomena across their different spatial scales, which is necessary to be accounted for the goal of having a more realistic model. Several methods of multiscale modeling have been proposed and employed previously. Examples include homogenization, multiscale residential segregation, variational multiscale modeling (VMM) and recently, variational multiscale enrichment. This study intends to employ VMM for the analysis of a Li-ion battery. The main advantage of VMM is that this method is computationally less expensive compared with the conventional methods. The main idea of implementing VMM is to decompose the response fields linearly into macro- and microscale components. VMM evaluates the microscale response semi-analytically through variational projection. With the determined microscale response, the VMM resolves the heterogeneity of the microstructure of the battery and obtains more accurate results. Validation of the model will be obtained against experimental and numerical results of Li-ion battery studies that are ongoing in our group.
Pre-Lithiation Treatment of Carbon Anodes Loaded with Different Li-Source Structures
Authors: Shellikeri Annadanesh , Watson Venroy George , Adams Daniel Lawrence , Kalu Egwu Eric , Zheng Jim P.
Published: February 2020

Lithium ion capacitors (LICs) have come to fill the gap between traditional Electric double layer capacitors (EDLCs) and Lithium ion batteries 1. But the carbon anodes, which exhibit a significant loss in their initial capacity due to consumption of Li ions in the device in forming the passivating SEI layer, have the potential to diminish this advantage, if unaddressed. Hence, one of the keys to the development of these devices is the pre-lithiation treatment which is conducted on the carbon negative electrodes. The lithiation process can be accomplished through several methods 2, including electrochemically driven lithiation, lithiation using external short in half cell configuration, lithiation by use of a back-side sacrificial lithium in combination with electrode with through holes and a separator or by direct-contact of lithium source and the negative electrode. This latter method of direct-contact is an efficient way of the lithiation since it doesn’t require any re-arrangement or any special structural needs for the electrodes.

We investigate this direct-contact lithiation process in different carbon anodes using various lithium source structures, which can have a major impact on the lithiation times and the properties of the SEI formed, further impacting the electrode processing costs. The results of this study in half-cell configuration and the performance in LIC configuration will be presented, while elaborating on the lithiation rates, efficiency and structural characteristics. Our preliminary results show that the amount and the rates of lithiation greatly vary in different anodes (graphite- Gr, hard carbon - HC, resp.), depending on the type of lithium source structures employed (4 types). Figure 1 compares the lithiation in anodes loaded with two such lithium sources (Stabilized Lithium Metal Powder – SLMP, Lithium Foil Strips - FS), during the first 24 hours duration of electrolyte soaking. The presence and absence of staging mechanism is distinctly evident in the graphite and hard carbon anodes, respectively, mainly due to different interplanar spacing in them. The different rates of lithiation is also evident from the varying amounts of remnant loaded lithium source.

Cao WJ, Shih J, Zheng JP, Doung T. Development and characterization of Li-ion capacitor pouch cells. J. Power Sources 257, 388–393 (2014)

G. Gourdin, P.H. Smith, T. Jiang, T.N. Tran, D. Qu, Lithiation of amorphous carbon negative electrode for Li ion capacitor, J. Electroanalytical Chemistry, 688, p. 103 (2013)

Figure 1
Improving the Performance of LiFePO4 Cathode Material By: Finding out an Effective Mixing Ratio for Cathode Slurry and Implementing Calendaring Process
Authors: Khanam Jobeda Jamal , Moss Pedro L. , Weatherspoon Mark H.
Published: February 2020

The olivine structured lithium iron (II) phosphate (LiFePO4) is a promising cathode material for use in lithium-ion batteries. It has a high operating voltage (~3.4 V vs Li/Li), nontoxic and environmentally benign [1]. Although It has high specific theoretical capacity (~ 170 mAh g− 1), at high ‘C’ rates the discharge capacity decreased exponentially. To get optimum and consistent discharge capacity at different ‘C’ rates, the conductivity has to be improved. Different percentage of PVDF and carbon black were used to prepare slurry mixture of LiFePO4 and then coated on bare aluminum and carbon coated aluminum foil to make the cathode electrodes. Coin cells were made and tested at 1/10 C, 1/5 C, ½ C and 1C rates. Also to compare the effect of binder on cell performance, distinct percentages of water based binder were used. For this experiment each sample cathode electrode were calendared to different densities. A comparison of uncalendered and calendared cathode electrode (with carbon-coated current collector and also non-carbon coated current collector) were made. Before calendaring, material density was 0.8424 gcm-3 at 146 µm thickness of cathode electrode and after calendaring, density increased to 1.59 g/cm-3at 97 µm thickness. Discharge capacity at different “C” rates shows that the calendared electrode provide consistent and better discharge capacity performance than the uncalendered electrode. Electrochemical impedance spectroscopy (EIS) test shows the calendaring of electrode exhibits a large decrease in contact resistance.

Reference:

[1] Seung-Ah Hong,Su Jin Kim, Kyung Yoon Chung, Myung-Suk Chun, Byung Gwon Lee, Jaehoon Kim, “Continuous synthesis of lithium iron phosphate (LiFePO4) nanoparticles in supercritical water: Effect of mixing tee”, The Journal of Supercritical Fluids, Elsevier, 2013.
Gas-Assisted Electrospraying Slurries of Silicon Fibers with Graphene Oxide for Binder-Free Electrode Fabrication
Authors: Carlin Joseph Michael , Fei Ling , Joo Yong Lak
Published: February 2020

The development of lithium-ion anode materials with both high capacity and high cyclic retention has been a large research challenge in recent years. With increasing power demands, new materials need to maintain performance at high charge and discharge rates. To meet these needs, a multilayered silicon fiber/ reduced graphene oxide (RGO) slurry was directly fabricated onto current collectors with a gas-assisted electrospraying method. The sprayed solution is a slurry of silicon fibers and graphene oxide (GO) sheets in water. The silicon fibers used were made via a magnesium reduction of silica fibers formed from electrospinning. Electrospinning was used due to its advantage in forming micron to sub-micron materials, both uniformly and scalable. The GO sheets used are commercially available, single layer, exfoliated sheets 25 microns in length. The gas-assisted spraying method has several advantages over the conventional slurry-cast approach in that it uses no binder, no toxic solvents, sprays dry onto the current collector, and is also industrially scalable. Once sprayed, the electrodes were thermally annealed in a nitrogen atmosphere to form the Si/RGO composite. The fabricated electrodes feature layers of silicon fibers wrapped by RGO sheet forming a conductive network while also accommodating the mechanical stress from silicon volume expansion. The electrochemical performance of the Si/RGO electrodes shows high capacity retention and can maintain performance at rates up to 1 A/g. Reversible capacities in half cells can reach more than 1600 mAh/g at 0.1 A/g and 800 mAh/g at the high rate of 1 A/g (based on combined Si/RGO mass). The gas-assisted electrospraying method is a simple, scalable approach to wrap silicon in RGO for high performance lithium-ion anodes.
Insights into the Ultra-Fast Li Storage Properties of Organic Polymers
Authors: Liang Yanliang , Hao Fang , Facchetti Antonio , Yao Yan
Published: February 2020

Organic materials have long been recognized as resource-abundant, sustainable, and potentially low-cost electrode materials that will handily satisfy the ever-growing demand for batteries. Although once had the reputation as being less stable and kinetically slow compared with their traditional inorganic counterparts, organic materials have been steadily improving on performance to be competent electrode candidates in recent years. We have recently reported a π-conjugated redox polymer with high cycling stability, high capacity utilization, and ultra-fast Li storage kinetics. The polymer delivers 80% of its theoretical capacity at a rate of 50C even with a high active mass ratio of 80 wt.% at practical mass loading, which is unusual for organic electrode materials. There is no established theory as for how such performance can be achieved and optimized via molecular design and microstructure engineering. We set out to scrutinize the charge storage mechanism of polymer electrodes and investigate the influence of molecular electronic structure and electrode microstructure on electrochemical performance. We have designed and synthesized a series of polymers with similar molecular structure but varying degree of conjugation in the backbone. The polymers are evaluated as Li storage electrode materials. The morphology and its evolution, charge transfer process, and state-of-charge-dependent electron and ion transport of the polymer electrodes are monitored and correlated to the cell performance. We found that regardless of the degree of conjugation, the redox reaction and the bulk ionic diffusion in the polymers proceed at comparable rates. We developed a procedure to directly measure the electrical conductivity of electrochemically lithiated polymers. This conductivity increases by 100-fold as the π-conjugation degree of the polymers increases. The structural order and morphology of the polymers differ widely with the conjugation length, leading to significantly different microstructure. The electrochemical surface area of the polymer electrode is continuously altered by the π-conjugation degree, which in turn impacts the ion transport model in the electrode. Overall, our study establishes general analysis tools that elucidate the underlying charge storage mechanism of polymer electrode materials. The results shown here provide guidance for further advancing high-energy/power energy battery based on organic materials.
A Li2s@SiO2 Modified Separator to Suppress Polysulfide Shuttle Effect and Li Dendrite Growth for Li-S Batteries
Authors: Ren Yuxun , Jiang Haoran , Zhou Xuelong , Zeng Yikai , Liu Ming , Zhao Tianshou
Published: February 2020

Abstract

High-energy Li-S batteries hold the promise of prolonging the electric vehicles’ mileage, but have been largely impeded by the polysulfide shuttle effect. It is recently reported that the uniform Li2S passivation layer deposited on the Li anode formed by side reactions (Li+(Sx)2-→Li2S) can perform a role in inhibiting polysulfide corrosion, however the Li dendrite growth usually leads to the collapse of the passivation layer and aggravates the side reactions [1, 2].

In this work, we propose to separate the Li2S passivation layer from the Li dendrites, which is realized by fabricating a SiO2 nanosphere layer impregnated with Li2S. With such a pre-passivation strategy, the Li-S batteries exhibit a substantial prolonged cycle life (4 mg cm-2 sulfur loading, > 3.6 mAh cm-2, 84% capacity retention) for the reasons: (i) the impregnated Li2S within the SiO2 spheres chemically anchor the polysulfides and thus largely suppress the polysulfide crossover; (ii) the mechanically strong SiO2 layer is capable of effectively mitigating the Li dendrite growth. The achieved results suggest that our strategies of building up a passivation layer separated from the Li anode is facile and effective, and can be readily for use in battery production.

Key words: Li-S battery; passivation layer; shuttle effect; Li dendrite.

References

[1] W. Li, H. Yao, K. Yan, G. Zheng, Z. Liang, Y.-M. Chiang, Y. Cui, Nature communications, 6 (2015).

[2] C. Yan, X.-B. Cheng, C.-Z. Zhao, J.-Q. Huang, S.-T. Yang, Q. Zhang, Journal of Power Sources, 327 (2016) 212-220.
Well Dispersed RuO2 Nanoparticle on NiCo2O4 Nanosheet Architectures As Efficient Bifunctional Catalysts for Lithium-oxygen Batteries
Authors: Zou Lu , Jiang Yuexing , Chi Bo , Cheng Junfang
Published: February 2020

The rechargeable nonaqueous Li-O2 battery holds promise to a perfect substitutes for lithium-ion battery for the theoretically high specific energy density (∼3505 Wh·kg-1). 1However, the great challenges facing the Li-O2 battery is still left so far. One of which is a huge energy loss for achieving a reversible Li-O2 electrochemical process, oxygen evolution reaction (OER) and oxygen reduction reaction (ORR) kinetics are critical to the realization of highly efficient lithium-oxygen batteries. 2, 3Rational design of bifunctional catalysts with fast oxygen reduction reaction (ORR) and oxygen reduction reaction (ORR) are valid to work out current problems.4

Here, we first exploit a particular structure of RuO2 nanoparticle and NiCo2O4 nanosheet composite, which RuO2 nanoparticle is uniformly coated on the surface of NiCo2O4 by a simple solution method. We demonstrate that the special design of RuO2/NiCo2O4 nanosheet composite provide excellent bifunctional electrocatalytic activities in Lithium-O2 battery. The air electrodes using RuO2/NiCo2O4 composite show enhanced overpotential characteristics and stable cyclability in our study, demonstrating high potential as efficient OER and ORR catalysts.

Referrences

1. D. Xu, Z. L. Wang, J. J. Xu, L. L. Zhang and X. B. Zhang, Chemical communications, 48, 6948 (2012).

2. B. D. McCloskey, A. Speidel, R. Scheffler, D. C. Miller, V. Viswanathan, J. S. Hummelshoj, J. K. Norskov and A. C. Luntz, The journal of physical chemistry letters, 3, 997 (2012).

3. S. S. Zhang, D. Foster and J. Read, Journal of Power Sources, 195, 1235 (2010).

4. V. Viswanathan, K. S. Thygesen, J. S. Hummelshoj, J. K. Norskov, G. Girishkumar, B. D. McCloskey and A. C. Luntz, The Journal of chemical physics, 135, 214704 (2011).
Carbon Nanotube (CNT) Foams As Sulfur Hosts for High Performance Lithium Sulfur Battery
Authors: Shen Chao , Xie Jianxin , Zhang Mei , Zheng Jim P. , Hendrickson Mary A. , Plichta Edward J.
Published: February 2020

The current Li-ion battery based on lithiation chemistry has a theoretical specific capacity of 372 mAh g-1. A battery chemistry beyond lithium ion vision is in urgent need to meet the ever-increasing energy storage demand. Lithium sulfur (Li-S) battery with a theoretical specific capacity of 1672 mAh g-1, is a promising candidate for next generation rechargeable lithium battery due to its high energy density, low raw material cost and environmental friendliness1. Despite these advantages, the current Li-S battery suffers from major problems including limited discharge capacity, poor cycle life and low coulombic efficiency, which severely hinder its commercialization.

In this work, freestanding, three-dimensional macroporous carbon nanotube (CNT) foams were used as sulfur hosts. To synthesize CNT foams, poly(methyl methacrylate) (PMMA) microspheres were used as a template and Polyac-rylonitrile (PAN) was used as a precursor to create crosslinks among CNTs2,3. The sulfur was then infiltrated into the foam by melting diffusion method. The porosity and sulfur loading of the CNT/S composite can be easily tuned during synthesis. The as-obtained cathodes showed a stable electrochemical performance with an initial specific capacity varied from 1337 to 1016 mAh g-1 at 0.2 C under sulfur loading of 1-3 mg cm-1. The cell under sulfur loading of 2 mg cm-1 retained a capacity of 812 mAh g-1 after 100 cycles. The incomplete sulfur utilization and gradual capacity decay during cycles are mainly associated with the growth of insulating end product Li2Sx (x≤2) and the dissolution of soluble intermediate product Li2Sx (4≤x≤8). Several approaches to overcome the issues and further improve the electrochemical performance were studied, including surface modification of CNT for better polysulfide anchoring, optimizing cathode pore structure by mixing CNT with microporous carbon, applying an interlayer as an upper current collector and enforcing an all-solid-state reaction by partial recharging within the second discharge plateau. The results of these studies will be presented and discussed in the meeting.

1. A. Manthiram, Y. Fu, S. Chung, C. Zu, and Y. Su, Chem. Rev., 114, 11751–11787 (2014).

2. Y. Cui and M. Zhang, ACS Appl. Mater. Interfaces, 5, 8173–8178 (2013).

3. Y. Cui and M. Zhang, J. Mater. Chem. A, 1, 13984-13988 (2013).
R&D for Lithium/Sulfur Batteries with Super High Energy Density
Authors: Zhang Hongzhang
Published: February 2020

The lithium/sulfur (Li/S) battery has been attracting increasing attention due to their higher theoretical specific energy density (2,600 Wh kg−1). However, the practical energy density of the Li/S battery (soft package) is still low, accompanied other unsolved problems as poor cycle life, low safety as well as worse rate capability. In order to solve these problems, much research effort has been engaged in developing better cathode materials (carbon/sulfur), cathode structure, electrolyte and separators.

By improving the performance of key materials and structure (including the C/S composite, separators and electrolyte), the energy density of the Li/S battery has been improved to over 90
0 Wh/kg and 1000 Wh/L. For another thing, the Li/S cathode could reach over 100 cycles with capacity retention of 70% (still over 800 mAh/g (S)) with energy density of 300 Wh/kg. In this presentation, the design and preparation of key materials (especially cathode and electrolyte) for soft package batteries will be presented. The key issues and solutions that affect the cycle life and energy density of Li/S batteries would be discussed in detail.

Figure 1
Li2s Nanoparticles for for a Better Understanding of the First Charge Working Mechanism of Li-Ion/Sulfur Batteries: An Operando XAS/Xes Coupled with XRD Analysis
Authors: Robba Alice , Bouchet Renaud , Barchasz Céline , Colin Jean-Francois , Elkaïm Erik , Kvashnina Kristina , Vaughan Gavin , Kavcic Matjaz , Alloin Fannie
Published: February 2020

With their high theoretical energy density (~2600 Wh.kg-1), lithium/sulfur (Li/S) batteries are highly promising, but these systems are still poorly understood due to the complex mechanisms/equilibria involved. Replacing S8 by Li2S as the active material allows the use of safer negative electrodes, like silicon, instead of lithium metal. S8 and Li2S have different conductivity and solubility properties, resulting in a profoundly changed activation process during the first cycle. Particularly, during the first charge a high polarization and a lack of reproducibility between tests are observed [1] (Figure 1a). Differences observed between raw Li2S material (micron-sized) and that electrochemically produced in a battery (nano-sized) may indicate that the electrochemical process depends on the particle size [2].

Then the major focus of the presented work is to deepen the understanding of the Li2S material charge mechanism, and more precisely to characterize the effect of the initial Li2S particle size both on the mechanism and the electrode preparation process. To do so, Li2S nanoparticles were synthetized according to two ways: a liquid path synthesis [3] and a dissolution in ethanol, allowing Li2S nanoparticles/carbon composites to be made [4]. Preliminary chemical and electrochemical tests show that starting with Li2S nanoparticles could effectively suppress the high initial polarization (Figure 1b) but also influence the electrode slurry preparation. Indeed, it has been shown that classical formulation process - a slurry composed of Polyvinylidone Fluoride polymer dissolved in N-methyle-2-pyrrolidone - cannot be used with Li2S nanoparticles. This reveals a complete different Li2S material behavior regarding polymers and organic solvents when going at the nanometric scale. Then the coupling between two operando characterizations such as X-Ray Diffraction (XRD) and X-Ray Absorption and Emission Spectroscopy (XAS/XES) have been carried out in order to interpret the poorly understood first charge. The results allow to explain the electrochemical behaviors and particularly the polarization differences observed during the first charge between micrometric and nanometric Li2S-based electrodes.

References

[1] S. Waluś et al., Electrochim. Acta, 180, 2015, 178–186.

[2] S. Waluś et al., Adv. Energy Mater., 2015.

[3] G. J.A, K. Wong, and S. Jick, J.C.S Chem. Comm, 1978, 6–7.

[4] F. Wu, H. Kim, A. Magasinski, J. T. Lee, H.-T. Lin, and G. Yushin, Adv.
Energy Mater., 4, 2014.

Figure 1
Investigation into the Mechanism and Causes of Gassing in Li4Ti5O12 Based/ LiMn2O4 Li-Ion Battery Systems
Authors: Hoffmann Jennifer , Milien Mickdy S , Lucht Brett , Li Jing , Payne Martin , Sans John , Stephenson Scott
Published: February 2020

Li4Ti5O12 (LTO) as an anode material for lithium ion batteries has garnered attention as a possible alternative to graphite anodes in the hybrid and electric vehicle auto industry due to its increased safety properties, high rate capabilities, and exceptional cycling stability. The main concern arises in that cells using LTO anodes produce gas especially at elevated temperatures leading to swelling and hampered performance. Many mechanisms have been proposed as possible sources of the gas evolution such as breakdown of electrolyte salts, water, and LTO surface reactions, but no direct cause or solution has been agreed upon. In the open literature, efforts have been made to combat this with either coating on LTO materials2,4 or electrolyte technology without a full understanding of how the material behaves in the cell. In this work, we take the investigation further to pinpoint the causes and mechanisms of the gas evolution in LTO based cells through gas analysis, electrochemical performance, and surface analysis in multilayer pouch cells and full cell coin cells. These results will be discussed in detail with the intention of shedding light on the gas evolution issue with the hope of leading to optimized solutions to resolve the gassing issue.

References

Y. He, B. Li, M. Liu, C. Zhang, W. Lv, C. Yang, J. Li, H. Du, B. Zhang, Q. Yang, J. Kim, F. Kang, Sci. Rep. 2, 913 (2012).

L. Wang, K. Nakura, M. Imazaki, N. Kakizaki, K. Ariyoshi, and T. Ohzuku, J. Electrochem. Soc., 159, A1710 (2012).

J. Liu, P. Bian, J. Li, W. Ji, H. Hao, A. Yu, J. Pow. Sour., 286 (2015)

W. Li, X. Li, M. Chen, Z. Xie, J. Zhang, S. Dong, M. Qu, Elect. Acta., 139 (2014)

J. Gao, B.Gong, Q. Zhang, G. Wang, Y. Dai, W. Fan, Ionics, 21 (2015)

J. Liu, P. Bian, J. Li, W. Ji, H. Hao, A. Yu, J. Pow. Sour., 286 (2015)
Li/Ag2VO2PO4 Batteries: The Roles of Composite Electrode Constituents on Electrochemistry
Authors: Bruck Andrea , Bock David C , Pelliccione Christopher J , Zhang Yiman , Takeuchi Kenneth J , Marschilok Amy C , Takeuchi Esther S
Published: February 2020

Silver vanadium phosphorous oxide, Ag2VO2PO4, was used as a bimetallic cathode system to systematically study the impact of the constituents of a composite electrode, including polymeric and conductive additives, on the electrochemical polarization and the bimetallic discharge progression of the battery. Ag2VO2PO4 has been developed as a cathode material intended for use in batteries that power implantable cardiac defibrillators (ICDs). This application demands primary battery systems that are reliable over long periods of implantation and are able to deliver high current pulses to charge the capacitors of the device. With these requirements in mind, primary Li/ Ag2VO2PO4 batteries are particularly promising because of their high capacity (270 mAh/g), excellent rate capability with pulses >30 mA sq. 1/cm, and lower cathode dissolution compared to the commercially used Li/Ag2V4O11system.

Ag2VO2PO4 is especially well suited for studies of discharge progression in bimetallic cathode systems. Notably, it can be discharged as a pure electroactive material in the absence of a conductive additive as it generates an in situ conductive matrix via a reduction displacement reaction resulting in the formation of Ag0 nanoparticles. The electrochemical reduction of Ag+ and V5+ in Ag2VO2PO4 has previously been determined to take place sequentially at low rates, with reduction of Ag+ to Ag0 through a reduction-displacement reaction occurring first but with a small level of V5+ reduction occurring concurrently. The Ag0nanoparticles formed can be detected by diffraction based techniques and can be spatially resolved by in situ Energy Dispersive X-ray Diffraction (EDXRD) to assess the homogeneity of discharge.

EDXRD provides unique insight into the state of the electrode by enabling evaluation of discharged phases as a function of spatial location. Furthermore, the white beam energy of the synchrotron light source can penetrate the steel casing of the battery, providing in situ measurements of coin type cells without the need for specially designed X-ray windows.

Three different electrode compositions were investigated: Ag2VO2PO4 only, Ag2VO2PO4 with binder, and Ag2VO2PO4 with binder and carbon. Constant current discharge, pulse testing and impedance spectroscopy measurements were used to characterize the electrochemical properties of the electrodes as a function of depth of discharge. In situ EDXRD was used to spatially resolve the discharge progression within the cathode by following the formation of Ag0. Ex situ X-ray Diffraction (XRD) and Extended X-ray Absorption Fine Structure (EXAFS) modeling were used to quantify the amount of Ag0 formed. Results indicated that the metal center reduced (V5+ or Ag+) were highly dependent on composite composition (presence of PTFE, carbon), depth of discharge (Ag0 nanoparticle formation), and spatial location within the cathode.
Study to Improve Electrolytes in Sodium Batteries
Authors: Walker Dejuante , Thai Edward , Higgwe Tamunotelema , Yu Ted H.
Published: February 2020

With increasing need for batteries and energy storage, sodium batteries are of increasing demand. Lithium batteries are very popular but focus is being placed on sodium due to its higher abundance and subsequently, its lower cost.  The human body also has a higher threshold for ingesting sodium than lithium as a nutrient, making it more biocompatible in ingestible battery1. The main focus of the study is to improve the electrolyte2,3. We test the electrolyte in a coin cell battery with sodium metal as the anode and the cathode. 

A variety of solvents, electrolytes, and additives are tested to optimize the electrolyte. Several different solvents were tested: ethylene carbonate (EC), propylene carbonate (PC), diethyl carbonate (DEC), dimethyl carbonate (DMC), dimethoxyethane (DME), and dioxolane.  These solvents were tested in different combinations with three electrolytes: sodium perchlorate (NaClO4), sodium bis(trifluoromethanesulfonyl)imide (NaTFSI), and sodium hexafluorophosphate (NaPF6). Lastly additives were tested in combination with above cases to test how they improve the electrolyte. The ionic liquid, 1-Butyl-1-methylpyrrolidinium bis(trifluoromethanesulfonyl)imide (Pyr14TFSI) and lithium nitrate (LiNO3) were tested as additives.

We look at the overpotential to gauge the effectiveness of the electrolytes by cycling symmetrical Na/Na cells. An example of the cycling with EC/PC/DEC and NaClO4 electrolyte is shown in the below Figure 1.

References:

1. L. Xin, X. Huang, H. Xu, Y. Zhang, J. Lam, J. Cheng and J. A. Rogers, Adv Mater
26, 3879-3884 (2014).

2. A. Ponrouch, D. Monti, A. Boschin, B. Steen, P. Johansson and M. R. Palacin, J. Mater. Chem. A, 3, 22 (2015).

3. Monti, Damien, Alexandre Ponrouch, M. Rosa Palacín, and Patrik Johansson. Journal of Power Sources, 324, 712-721 (2016).

Figure 1
Polymer-Sulfide Composite Solid State Electrolyte with Enhanced Interfacial Stability with Sodium Metal
Authors: Zhang Ye , Hu Pu , Yao Yan
Published: February 2020

Rechargeable sodium-ion batteries have received growing attention as promising alternatives to lithium-ion batteries for grid energy storage devices because of the abundance of Na resources as well as its high theoretical capacity of 1165 mAh g-1, and low electrochemical potential (-2.71 V vs. standard hydrogen electrode). However the safety issues still remain as the most critical challenges for its wide application. The rise of solid state electrolyte (SSE) with high Na-ion conductivity has brought about new opportunities for the development of sodium metal batteries. The recently reported Na-ion superior conductor Na3SbS4 (NSS) with a room temperature ionic conductivity of 1.2 mS cm-1 represents the highest Na-ion conductivity. However, NSS is unstable with Na metal and will decompose to Na2S upon cycling confirmed with synchrotron X-ray diffraction and XPS studies. The formation of Na2S leads to the increase of interfacial resistance and deteriorates the battery performance. To stabilize the interface between Na and electrolyte, we report a multilayer cellulose-supported PEO polymer(CPEO)/NSS electrolyte design which combines the high ionic conductivity of NSS and the high stability of CPEO layer, thus resulting in a stable electrochemical process of Na stripping/plating (Figure b). Symmetric cell with CPEO/NSS multilayer electrolyte demonstrate a stable areal specific resistance (ASR) of 2000 Ω cm2 for 130 cycles, while the battery with pristine NSS electrolyte shows an increasing ASR from 80 Ω cm2 to 4300 Ω cm2. The superior interfacial stability of multilayer electrolyte would be promising for designing all-solid-state sodium batteries.

Figure 1
Investigating SEI Formation on Lithium Metal Anodes
Authors: Jurng Sunhyung , Brown Zachary Lee , Lucht Brett L
Published: February 2020

The Li plating/stripping performance of LiFePO4/Cu cells has been investigated for carbonate solutions of three different lithium salts, LiPF6, LiBF4 or LiBOB. The coulombic efficiencies of these cells are higher in the early cycles, but drops gradually during cycling. The capacity retention and efficiency of the cells is best with LiBOB followed by LiBF4 while LiPF6 provides the poorest performance. The differences are likely due to changes to the solid electrolyte interphase (SEI) on the surface of the lithium metal electrodes. Ex-situ analysis of the electrodes has been conducted via a combination of XPS and FT-IR to develop a better understanding of the role of the SEI in cycling performance.