bluuebunny/crossref_metadata_2025 huggingface dataset:
Interaction Mechanism Between SEI Lithium Salts and Glymes or Surfactant as Additive in Li-Ion Batteries
Authors: Chretien Fabien , Jones Jennifer , Damas Christine , Lemordant Daniel , Galiano Hervé , Willmann Patrick , Anouti Mérièm
Published: February 2020

Lithium-ion batteries (LIB) are undoubtedly the most popular and mature electrochemical storage devices and, for future use, a higher degree of safety, a longer cycle life, and a higher specific energy are desirable. In order to achieve this goal, numerous publications have been devoted to new active materials and new electrolytes [1] but far less to interfaces. As a matter of fact the solid-electrolyte interphase (SEI) formed through the reductive decomposition of solvent molecules plays a crucial role in the performances of LIB. The robustness and efficiency of the SEI [2] therefore significantly affect the power capability, stability, safety and cycle life of a LIB.

In this study, we investigate the impact of several lithium salts, already present in the SEI like LiF, Li2O, LiOH, Li2CO3, LiOCH3 and LiOC2H5, on the cycling ability of a graphite or LiNiMnCoO2 electrodes [3] in Li half cells containing the standard (EC/PC/3DMC + 1 M LiPF6) electrolyte. These lithium salts are soluble (LiF), slightly soluble (LiOCH3 and LiOC2H5) or almost insoluble (Li2O, LiOH, Li2CO3) but present in solution as a colloidal suspension at saturation. Results show that these lithium salts, dissolved or in suspension in the electrolyte have a non-negligible impact on the electrode capacity during cycling, depending on the type of electrode and nature of the salt. Mineral salts like LiOH, Li2O and LiF (at high concentration) degrade battery performances by forming a resistive film at the electrode surface. On the contrary, LiOCH3 and Li2CO3 are beneficial to cycling performances owing to the formation of a Li conductive coating. In order to avoid the negative impact of dissolved LiF, glymes like diglyme (G2), triglyme (G3) and tetraglyme (G4) have been added as these compounds are known to complex strongly Li+ ions. A complementary approach has been the use of fluorinated surfactant additives able to modify the interfacial material/electrolyte free energy. Electrochemical characterization by galvanostatic cycling and cyclic voltammetry, combined with XPS and SEM surface characterization have been performed to evaluate the impact of each additive and to clarify its mechanism of action. Results show that the addition of glymes limits the negative effect of SEI lithium salts, while the surfactant improves the wettability of the electrodes leading to better cycling performances.

[1] J.B. Goodenough, Y. Kim, Chemistry of Materials, 22 (2010) 587-603.

[2] P. Verma, P. Maire, P. Novák, Electrochimica Acta, 55 (2010) 6332-6341.

[3] Fabien Chrétien, Jennifer Jones, Christine Damas, Daniel Lemordant, Patrick Willmann, M. Anouti, Journal of Power Sources, 248 (2014) 969-977.
Chinese Shadowboxing-Inspired Rigid-Flexible Cellulose-Based Solid Polymer Electrolyte for High Performance Lithium Battery
Authors: Cui Guanglei , Zhang Jianjun , Liu Zhihong
Published: February 2020

Classical lithium ion batteries based on liquid electrolyte have been developed rapidly. They have brought us

much economic benefit, but it also exited massive potential safety risk. All-solid-state polymer electrolyte

would be a perfect way to solve this problem effectively. Solid polymer electrolyte especially poly (ethylene

oxide) (PEO) running above 80 oC often results in poor mechanical strength and narrower electrochemical

stability window. It is a compelling challenge to exploit solid polymer electrolyte for lithium battery with both

high ionic conductivity and superior mechanical performance. Herein, we reported a new class of Chinese

shadowboxing-inspired rigid-flexible polymer electrolyte based on soft segment PEO and robust cellulose

supporting matrix. Such solid polymer electrolyte solves most of abovementioned disadvantages, with

superior mechanical strength, high ionic conductivity of all-solid-state polymer electrolyte

(1.3×10-4 S cm-1), improved thermal resistance (up to 180 oC) compared with PEO polymer electrolyte.

We believe this would offer a kind of new concept for designing and exploiting rigid-flexible solid

polymer electrolyte by selecting and adjusting various components according to different requirements for

rechargeable metallic lithium batteries (for example lithium-sulfur batteries and lithium-air batteries)

that will overcome the bottlenecks in developing future polymer lithium battery technology that powers

consumer electronics and hybrid electric vehicles.
Mathematical Model for Moderately Dilute Electrolytes of Lithium Ion Battery
Authors: Ranom Rahifa , Richardson Giles , Foster Jamie Michael
Published: February 2020

We formulate a model for transport (of both Li+ ions and a generic N- ion species) in a moderately dilute electrolyte - i.e. an electrolyte in which ionic concentrations (of Li+ and N-) are small compared to that of the solvent (so that solvent need not be treated explicitly), but are not sufficiently dilute to be treated with the Nernst-Planck theory. We approximate Nernst-Planck theory by assuming that the local concentrations of the various ion species are balanced (charge neutral) except in regions local to the electrolyte-electrode interface where the (de-) intercalation reaction occurs. The resulting model is similar in form to that presented by Newman [Adv. Lith. Batt. 2002], but contains considerably fewer physical parameters, namely: (i) the effective electrolyte diffusivity, (ii) the transference number and (iii) the electrolyte conductivity. This reduction in the number of parameters is possible due to our `averaged’ description of the porous electrode and thus facilitates a more straightforward comparison with experiment. We present numerical simulations of the model and these are shown to agree favourably with experimentally obtained characteristics of a graphite half-cell.
Nasicon-Type Li-on Conductor for All-Solid-State Li-Ion Batteries
Authors: Lu Li , Zhu Yaqi , Zhang Yunfeng
Published: February 2020

All-solid-state lithium batteries are regarded as the next-generation power sources because of its superior safety and long cycle lives. But its development is prevented by the lack of solid electrolyte materials with high conductivity and high electrochemical stability. [1]

In past decades, a new family of lithium-ion conductors with Nasicon-type structure has attracted lots of interests due to its high bulk conductivity. However, several drawbacks prevent them from practical application such as low grain boundary conductivity and low electrochemical stability. [2]

To solve these problems, the present study is focused on optmizing the preparation process of an electrolyte material based on NASICON-type structure. A melting quench method has been adopted to eliminate the grain boundary resistance of Nasicon-type electrolyte Li1.5Al0.5Ge1.5P3O12 (LAGP) and the amorphous sheets are heat treated at different temperatures to investigate the relationship between microstructure and ionic conductivity. The highest total conductivity of 2.907x10-3S/cm at 27℃ has been achieved by crystallizing the glass at 800℃ for 8h and its activation energy is measured to be 0.27eV. Systematic characterizations on crystal structure and grain size are conducted to lead to further understandings on mechanism of lithium-ion transportation and grain growth kinetic.

References

[1] Thokchom, J.S., N. Gupta, and B. Kumar, Superionic Conductivity in a Lithium Aluminum Germanium Phosphate Glass-Ceramic. Journal of the Electrochemical Society, 2008. 155(12): p. A915-A920.

[2] Zhang, M., et al., Preparation and Electrochemical Properties of Li1+xAlxGe2-x(PO4)(3) Synthesized by a Sol-Gel Method. Journal of the Electrochemical Society, 2012. 159(7): p. A1114-A1119.
Mechanically Clamped Liquid-PEO Based Block Copolymer Electrolytes for Solid-State Lithium-Ion Batteries
Authors: Rolland Julien , Brassinne Jérémy , Bourgeois Jean-Pierre , Vlad Alexandru , Gohy Jean Francois
Published: February 2020

During the past two decades, many efforts were devoted to increase the performance of Li-ion batteries[1]. Currently, Li-ion technology using carbonate based liquid electrolyte exhibits the best performances but it’s also famous for safety reason: leakages of corrosive products, explosion hazard and narrow stability window. Solid-state electrolytes are the perfect solution to develop safer lithium devices[2]. By combining lightweight, easy implementation, flexibility and mechanical strength, solid polymer electrolyte appears to be the most attractive alternative. Among various polymers developed, only polyethylene oxide (PEO) is known to solvate a substantial amount of lithium salt. However, relevant ionic conductivities are obtained mainly above the melting point (>65°C), which render this material unpractical for most of applications[3].

Herein, we disclose the design of a mechanically clamped liquid PEO based electrolyte integrating both, high ionic conductivity and mechanical strength at room temperature[4]. Through macromolecular engineering, a bi-functionnal block copolymer is designed combining an anchoring polystyrene (PS) block attached to a polymethacrylate oligoethylene glycol (POEGMA) ionic conductive block. By tuning the relative size of the two blocks, the mechanical properties were finely adjusted to offer excellent mechanical strength. Only minority PS block was necessary to generate glassy PS-nanodomains that provide a robust mechanical anchor to the electrolyte confirmed by rheological measurements (Fig. 1a). The ionic conductivities appear to be barely affected by the PS block, with conductivities approaching 10-5 S/cm, similar to pure POEGMA system at room temperature. To meet the highest performances for mechanically clamped electrolyte, the size of the oligomeric side chain was finely tuned to offer the conductivities above 10-5S/cm.

Furthermore, the bi-functional electrolyte was found to exhibit a wide electrochemical stability window, above 5 V vs. Li/Li+, which renders this material applicable to high voltage cathode batteries. The bi-functional electrolyte also displays a more stable behavior at anodic potentials allowing the formation of a stable electrode interphase after only few cycles (Fig. 1b). Finally, a prototype LiFePO4/PS-b-POEGMA/Li battery is realized demonstrating the applicability of the mechanically clamped liquid PEO based electrolyte for all-solid-state Li-ion batteries.

References

[1] Armand, M., Tarascon, J. M. Building better batteries Nature
451, 652–657 (2008).

[2] Murata, K., Izuchi, S., Yoshihisa, Y. An overview of the research and development of solid polymer electrolyte batteries. Electrochim. Acta 45, 1501-1508 (2000).

[3] Bouchet, R., et al. Single-ion BAB triblock copolymers as highly efficient electrolytes for lithium-metal batteries Nature Materials
12, 452-457 (2013).

[4] Rolland, J., et al. submitted.
New Insights into SEI Formation in Lithium Ion Batteries: Inhomogeneous Distribution of Irreversible Charge Losses Across Graphite Electrodes
Authors: Klink Stefan , Weide Philipp , Muhler Martin , Schuhmann Wolfgang , La Mantia Fabio
Published: February 2020

The development of lithium ion batteries with long cycle life requires a good control of degradation mechanisms and irreversible charge losses (ICL). The most prominent example in this respect is the use of electrolyte additives such as vinylene carbonate (VC) to improve the physical properties of the Solid Electrolyte Interphase (SEI) [1].

Until now, the SEI was considered to be formed homogeneously throughout the thickness of the electrode. Unfortunately, standard analytical techniques are either surface sensitive or they probe the entire averaged properties of the electrode and hence cannot proof otherwise. Porous electrodes, however, are characterized by a distribution of charge-transfer currents across the electrode due to a mass-transport limitation of educts diffusing from outside the electrode [2]. A multi-layered working electrode (MWE) was therefore developed to resolve electrochemical reactions in this vertical dimension. It was observed that the intercalation of lithium ions into graphite proceeds stage-by-stage and layer-by-layer from top to bottom [3].

For the reduction of electrolyte constituents in small quantities such as additives or contaminants, however, the case is different. The surface layer of the MWE suffers from a higher irreversible reduction current due to an additional influx of reactants from the separator. Since these reactants are fully depleted from the electrolyte during first charge, graphite particles close to the electrode surface effectively act as “electrochemical sieve” for contaminants and additives. X-ray photoelectron spectroscopy (XPS) studies confirm that this sieving effect results in a different SEI on the electrode surface as compared to the electrode bulk. The results presented here are to the best of our knowledge the first direct experimental proof that ICL and SEI are not evenly distributed across graphite electrodes.

[1] P. Verma, P. Maire, P. Novák; Electrochim. Acta
2010, 55, 6332–6341.

[2] J. Euler and W. Nonnenmacher; Electrochim. Acta, 1960, 2, 268.

[3] S. Klink, W. Schuhmann, F. La Mantia; ChemSusChem, 2014, submitted
Material Development of the Lgps Based Solid Electrolytes — Structure, Conductivity and Battery Characteristics
Authors: Kanno Ryoji , Kato Yuki , Ohmin Kwon , Suzuki Kota , Hirayama Masaaki , Yonemura Masao
Published: February 2020

Lithium superionic conductors, which can be used as solid electrolytes, promise the potential to replace organic liquid electrolytes and thereby improve the safety of next-generation high-energy batteries. Although the advantages of non-flammable solid electrolytes are widely acknowledged, their low ionic conductivities and low chemical and electrochemical stabilities prevent them from being used in practical applications. The new lithium superionic conductor, Li10GeP2S12 (LGPS) exhibits an extremely high bulk conductivity of over 10-2 S cm-1 at room temperature (27 °C), and is a potential electrolyte candidate for an all solid-state battery [1]. In order to explore the material variety of the LGPS based electrolytes, solid solutions of the pseudo binary Li4GeS4 – Li3PS4 system were investigated. In addition, the new material systems were synthesized with the cation and/or anion substitutions (Si, Ge, Sn, O etc). The solid solution was synthesized for the LGPS parent phase in the binary system, and the conductivity varied with the lithium composition. The structures were determined by X-ray and neutron diffraction analyses, and the relationship between the ionic conduction and structures was clarified. The ionic conductivity and electrochemical stability varied with the compositions examined by the cation and/or anion substitutions. Battery performances using these LGPS systems were investigated. Based on the materials varieties and the battery performances using the LGPS electrolytes, the advantages of the all solid-state batteries will be discussed.

Reference

[1] N. Kamaya et al., Nat Mater, 10, 682-686 (2011).
Voltage and Impedance Analysis for the Indirect Detection and Characterization of Lithium Plating in Commercial Lfp//Graphite Li-Ion Cells
Authors: Danzer Michael A. , Petzl Mathias
Published: February 2020

Lithium plating is one of the most critical ageing mechanisms of lithium ion batteries; it reduces the cell’s lifetime due to a loss of cyclable lithium and it reduces the safety due to the presence of metallic lithium in the cell. The deposition of metallic lithium occurs on the negative graphite electrode during charging preferentially at low temperatures, high currents, and high states of charge (SOC).

A novel approach enables the indirect detection of lithium plating through the analysis of voltage plateaus at discharge immediately after the charging process. Using the method of differential voltage analysis (DVA) [1] the charge amount corresponding to lithium stripping – as the reverse reaction to plating – is calculated [2].

A characterization of the cell behavior and a deeper analysis of the processes that take place at and after plating are performed using electrochemical impedance spectroscopy (EIS). Subsequent impedance spectra measured over a time span of one hour after metallic lithium was deposited on the negative electrode reveal fundamental changes in the polarization of the cell (see Fig. 1). After plating, the graphite electrode exhibits an impedance behavior which is typical for lithium metal electrodes [3]. The mid-frequency impedance arc increases with time (see Fig. 2) and approximates the size of the arc of the spectrum without plated lithium. The low polarization in this frequency range immediately after plating indicates the presence of new electrode surface area [4]. Whereas the increase in polarization over time reveals the formation of additional surface films. The approximation of the impedance arc over time towards the size of the arc without deposited lithium points to the development of a stable surface film. Nonetheless, the absence of the low frequency tail indicates that the electrode still behaves like a lithium metal electrode without solid state diffusion of lithium ions in graphite.

Further model-free analysis of the measured impedance spectra using the distribution of relaxation times (DRT) enables the identification of the underlying processes due to the relevant time constants [5]. It is shown that Li-ion migration through surface films is the rate-determining process in case of a plated graphite electrode.

References

[1]I. Bloom, A. N. Jansen, D. P. Abraham, J. Knuth, S. A. Jones, V. S. Battaglia, und G. L. Henriksen, J Power Sources, 139 (1–2) 2005, 295–303.

[2] M. Petzl und M. A. Danzer, J Power Sources, DOI 10.1016/j.jpowsour.2013.12.060, 2013.

[3] D. Aurbach, J Power Sources, 89 (2), 2000, 206–218.

[4] N. Schweikert, A. Hofmann, M. Schulz, M. Scheuermann, S. T. Boles, T. Hanemann, H. Hahn, und S. Indris, J Power Sources, 228, 2013, 237–243.

[5] J. P. Schmidt, T. Chrobak, M. Ender, J. Illig, D. Klotz, und E. Ivers-Tiffée, J Power Sources, 196 (12), 2001, 5342–5348.
A New Analytical Instrument Combining XRPD, Mössbauer Spectrometry and Electrochemical Analyses
Authors: Sougrati Moulay-Tahar , Leriche Jean-Bernard , Stievano Lorenzo , Fullenwarth Julien , Fraisse Bernard , Jumas Jean-Claude
Published: February 2020

The research of new electrode materials of high performance for Li-ion batteries requires a better understanding of the electrochemical reaction that take place during the charge/discharge process.

For this objective in situ measurements have been developed using complementary tools such as X-Ray Powder Diffraction (XRPD) and Transmission Mössbauer Spectrometry (TMS) allowing both structural and electronic characterization of materials under the conditions of the electrochemical cycling (operando mode). Up to now these measurements are carried out separately, ie, using a cell to record the X-ray diffraction data and another cell for the Mössbauer data. To overcome the drawback of working on two different cells, a new setup [1] combining XRPD and TMS has been designed allowing an alternative way for recording of these two kinds of data simultaneously. Thus a conventional TMS spectrometer has been associated to a X-Ray Diffractometer of θ-θ geometry (Figure 1) using a specific electrochemical cell derived initially designed for in situ analyse of Li-ion batteries [2].

Figure 1: 1st
prototype of the setup combining XRPD diffractometer and TMS spectrometer.

On this prototype the electrochemical cell is fixed, thanks to the θ-θ geometry of the diffractometer. Connected to a potentiostat which is used to control electrochemical cycling. This cell allows measurements in both reflection mode (XRPD) and transmission mode (TMS). Since Mössbauer detector is saturated by the diffused X-rays, an software has been developed to allow collecting alternatively XRD patterns and Mössbauer spectra. The duration of the collection of each kind of data can be adjusted as a function of the investigated material.

Several examples are presented to illustrate the capabilities of this setup and how it can be used to illucidate complex mechanisms governing the electrochemical behaviour of Li- and Na-ion new electrode materials containing Fe or Sn.

References

[1] J.-C. Jumas, L. Stievano, M.T. Sougrati, J. Fullenwarth, B. Fraisse, J.-B. Leriche, Brevet Français, 12 58086 (2012), PCT/FR2013/051981 (2013)

[2] J.B. Leriche, S. Hamelet, J. Shu, M. Morcrette, C. Masquelier, G. Ouvrard, M. Zerrouki, P. Soudan, S. Belin, E. Elkaïm, F. Baudelet, J. Electrochem. Soc., 157 (2010) A606.

Acknowledgements

The Mössbauer platform has been implemented at the University of Montpellier with supports from the EC (NoE ALISTORE SES6-CT-2003-503532), Région Languedoc Roussillon (Contracts n° 2006-Q086 and 2008-094192). The author is grateful to these institutions and to CNRS and RS2E (FR 3459) for financial supports.
A Novel Conceptual Mg Battery with High Rate Capability
Authors: Zhang Ruigang , Ling Chen , Mizuno Fuminori
Published: February 2020

Lithium ion batteries (LIBs) are quickly becoming the mainstream power sources for environmentally friendly vehicles such as hybrid vehicles (HV), plug-in hybrid vehicles (PHV) and electric vehicles (EV) due to their high energy density. On the other hand, a battery system with even higher energy density is required for the long-range PHV and EV applications, and therefore, post lithium ion batteries (PLIB) such as Li-sulfur batteries and Li-air batteries have been getting more attention in recent years. Rechargeable magnesium batteries are also a candidate for the PLIB thank to the natural abundance of magnesium and the absence of dendrite formation when magnesium metal is used as the anode. In addition, the magnesium batteries are expected to have high energy density because of its divalent nature. However, there is not much progress on the development of novel cathodes since an innovation of Chevrel phase materials such as MgxMo3S4. The difficulty lies in the strong polarization character of the small and divalent Mg2+ and consequently the intercalation and diffusion of Mg2+ ions is somewhat difficult and complicated.

Here, we report an interesting approach to find another redox reaction on the cathode side that replaces the classic intercalation reaction and balances the electron transfer.  The charge transfer is achieved through the simultaneous transport of dual ions in the electrolyte during the electrochemical cycling. Reversibility on the interesting chemistry was confirmed by multiple techniques, such as X-ray diffraction, X-ray photoelectron spectroscopy, Scanning electron microscopy and so on. Figure 1 shows one of the conceptual Mg batteries comprising a Mg metal anode, a AgCl cathode and a Grignard-based electrolyte.  As can be seen, fairly flat discharge-charge curves are repeatedly observed.  Also, even at a rate of 10 C, the cell works very well and maintains over 100 mAh/g which is over 50 % of the capacity observed at 0.1 C. The significant change in cathode material design gave us a new finding of an impressive Mg battery with high rate capability.

Figure 1
Development of Garnet-Type Li Ion Electrolytes for All-Solid-State Li Ion Batteries
Authors: Narayanan Sumaletha , Thangadurai Venkataraman , Tong Xia , Hitz Gregory , Wachsman Eric D.
Published: February 2020

The high energy density Li ion batteries require a replacement of currently used organic polymer electrolyte with highly conducting solid-state materials in terms of safety reasons. Solid electrolytes exhibiting high total Li ion conductivity, negligible electronic conductivity and wide electrochemical window (up to 6 V/Li/Li+) are preferable for application in solid-state Li ion batteries [1,2]. Garnet-like oxides, with general formula, Li5La3M2O12 (M = Nb, Ta) are emerged as a promising class of Li+ conductors among several other solid-state materials [1]. The increase in Li content has proven to be increasing the Li ion conductivity of garnets and Li7La3Zr2O12 have a highest conductivity of the order of 10-4 Scm-1 at ambient condition [3]. In this talk, we report the effect of excess Li added during synthesis to avoid Li volatilization on the ionic conductivity of garnet-type materials and discuss the recent developments on optimization of ionic conductivity of garnets.

References

1.         V. Thangadurai, H. Kaack and W. J. F. Weppner, J. Am. Ceram. Soc., 86, 437 (2003).

2.         J. B. Goodenough and K.-S. Park, J. Amer. Chem. Soc., 135, 1167 (2013).

3.         R. Murugan, V. Thangadurai and W. Weppner, Angew. Chem. Int. Ed. Engl., 46, 7778 (2007).
Structural and Electrochemical Characterization of New Hexagonal Form of NaMn2O4 Cathodes for Sodium Ion Batteries
Authors: Jampani Hanumantha Prashanth , Datta Moni Kanchan , Bandi Ramalingam , Elumalai Viswanathan , Manivannan A. , Achary Damodaran Krishnan , Kumta Prashant N
Published: February 2020

Introduction

Lithium ion batteries have thus far been the torchbearers in the field of electrochemical energy storage for mobile applications. The large scale commercialization of lithium ion batteries, however has the associated ‘cost of business’ including possible socio-economic concerns to various lithium rich nations such as Bolivia(1). There has therefore been a gradual realization in the battery community at large for the need to switch to more abundant raw-material based chemistries. Sodium and magnesium batteries are the fore-runners therein(2). In order for the smooth transition and for Na-ion to compete with the Li-ion batteries, considerable improvements in cathode and anode energy density, cyclability and rate capability are still required.

Nanocrystalline NaMn2O4 has been synthesized by a high energy mechano-chemical milling process (HEMM) using Na2O2 and Mn2O3 as starting materials for use as cathodes for sodium ion batteries. As previously reported by this group(3), the material exhibits a new close packed hexagonal crystalline form, different from the commonly known stable orthorhombic or monoclinic structures in the Na–Mn–O system, identified for the first time.

In this work, we study the stabilization of the hexagonal phase and its evolution to an orthorhombic phase upon heat treatment. Using in-depth solid-state NMR studies in conjunction with detailed electrochemical evaluation, the nature of the charge-storage behavior of this phase is evaluated herein. Figure 1 depicts the evolution of the hexagonal NaMn2O4 to a conventional orthorhombic phase upon heat-treatment. Alteration in sodium co-ordination chemistry and its effect on insertion/deinsertion and capacity will be presented and discussed.

Captions

Figure 1: Evolution of structure of hexagonal NaMn2O4 into the more known orthorhombic phase upon heat-treatment as observed using scanning electron microscopy.

References

1.         R. Aguilar-Fernandez, Estimating the Opportunity Cost of Lithium extraction in the Salar de Uyuni, Bolivia, in, Duke University (2009).

2.         B. L. Ellis and L. F. Nazar, Current Opinion in Solid State and Materials Science, 16, 168 (2012).

3.         M. K. Datta, R. Kuruba, P. H. Jampani, S. J. Chung, P. Saha, R. Epur, K. Kadakia, P. Patel, B. Gattu, A. Manivannan and P. N. Kumta, Materials Science and Engineering: B, 188, 1 (2014).

Figure 1
Microwave-Assisted Synthesis of Graphene-Coated Mn-Doped Lithium Iron Phosphate (LFMP/G) for Electrochemical Capacitor
Authors: Rossouw Claire Angela , Zheng Haitao , Raju Kumar , Mathe Mkhulu K. , Ozoemena Kenneth I.
Published: February 2020

Lithium Iron Phosphate (LFP) material is widely used to power commercial products such as torches, automotive vehicles and certain laptops. The material is relatively cheap, safe to use and longer life times than some of the other battery chemistry materials; however it suffers from poor electronic conductivity. In order to improve the electronic conductivity of LFP, the material can be doped with transition metals such as manganese (Mn) and coated with a carbon source such as graphene [1]. Various methods can be used to synthesize LFP materials with microwave synthesis being one of the examples [2]. Microwave irradiation allows for rapid synthesis. The experimental processes involved a one-pot design where all the starting materials were added together and underwent ultra-sonication, microwaving, washing, drying and annealing at 700°C.  During the microwave irradiation process it was seen that crystalline LFP material was formed with a coating of graphene to form LFP/G and some of the material was doped with Mn to form LFMP/G. The LFP/G and doped LFMP/G material was made up into asymmetrical electrochemical capacitors (AEC). The LFP/G AEC had a much faster charge and discharge response time at 7mA relative to the LFMP/G AEC, however the LFMP/G AEC could be charged and discharged to higher voltages. The LFP/G AEC provided 1.43 mFcm-2 at a current density of 8.85 mAcm¯² over 30 h, whereas the LFMP/G provided 4.63 mFcm-2at a current density of 12.4 mAcm¯² over 50 h. Both capacitors showed very little internal resistance once the testing was completed.

In this presentation, we will discuss in detail our findings on the various microwave-based synthetic strategies adopted for the LFP/G and LFMP/G and their electrochemical properties for the development of efficient cathode materials for lithium ion batteries and asymmetric electrochemical capacitors.

References

(1)     I. Bilecka, A. Hintennach, I. Djerdj, P. Novàk, M. Niederberger, J. Mater. Chem.19 (2009) 5125.

(2)     D. Jugović, D. Uskoković, J. Power Sources 190 (2009) 538.

Figure 1
Study on Degradation and Failure in Lithographically Patterned Gold/Manganese Dioxide Core/Shell Nanowires Based Supercapacitors
Authors: Thesma Chandran Girija , Le Thai Mya , Penner R.
Published: February 2020

Nanostructured manganese oxide (MnO2) is one of the widely studied materials for electrochemical capacitors because of the high specific surface area and excellent electrochemical properties leading to improved rate capability and enhanced energy/power densities. Most of the research on MnO2 is aimed at improving the capacitance whereas only a few studies are focused on cycling stability of these electrodes. In this work, degradation in capacitance of arrays of gold core nanowire encapsulated within a hemicylindrical shell of MnO2 will be studied. The horizontal nanowire systems provide an excellent platform for analyzing nanowire performance, such as investigations of the mechanisms contributing to degradation and failure in these systems. Ex-situ Raman spectroscopy, X-ray photoelectron spectroscopy and Grazing incidence X-ray diffraction  measurements will be performed on the core/shell nanowires to examine various parameters such as nanowire defects, MnO2 dissolution, mechanical electrode failure behind degradation .
Calendar and Charge-Discharge Cycle-Life Studies of Supercapacitors for Vehicular Applications
Authors: EL Mejdoubi Asmae , Oukaour Amrane , Sabor Jalal , Gualous Hamid
Published: February 2020

Supercapacitors, also called Electric Double Layer Capacitors (EDLCs), have received an increasing interest from the power electronics community due to their high power density and compact size. These advantages make them good candidates for high-performance applications, such as electric/hybrid vehicles and railway transportation. Because supercapacitors have a long cycle life, calendar and charge-discharge cycle life prediction is of primary importance for vehicular applications. Based on the Arrhenius model, the supercapacitors’ aging is accelerated by the elevated temperature. Therefore, the charge-discharge impact on the cycle life is not considered. In this paper, the correlation between calendar and charge-discharge aging is established and the obtained cycle life prediction model was validated by experimental results. The tests were conducted on the supercapacitors BCAP0350F of Maxwell Technology and they were performed at various conditions of temperature and bias voltage.
Carbon Nanostructures (CNS): Highly Conductive Matrix for Lithium Ion Battery Electrodes
Authors: Singh Boor , Shah Tushar , Hashaikeh Raed
Published: February 2020

Traditional conductive carbon and polymer binder plays an important role for fabrication of lithium ion battery electrodes. Conductive carbon provides conductive pathways between the electrode particles specially for low electrical conductivity electrode materials and current collector,at the same time, the binder helps to provide mechanical integrity for electrode material. In this work, carbon nanostructres are presented as a highly conductive matrix material for fabrication of electrode without using any polymer binder. CNS consists of highly crosslinked and covalently bonded carbon nanotubes and forms a free standing films after reassembling from a CNS dispersed solution. CNS have high surface area, high electrical conductivity, low cost   and environmently benign synthesis process. CNS/LiFePO4 cathode is fabricated using a facile process using water/ethanol mixture. No organic solvent is used for electrode fabrication. Scanning electron micrograms of the CNS/LiFePO4 electrode shows that LiFeO4 electrode particles are entraped by the entangled carbon nanostructures and provide high electrical conductivity pathways. LiFePO4/CNS electrode shows high electrical conductivity of 9.1 S/cm compared to the 0.4 S/cm for conventional LiFePO4/Carbon electrode. Cyclic voltammetry results show that CNS/LiFePO4 has low polarization potential compared to C/LiFePO4. This is attributed due to highly conductive pathways offered by the CNS. Charge-discharge performance of the CNS/LiFePO4 in half cell demonstrated improved capacity retention at high discharge rates.
Computational Analysis of Battery Performance Working at Low Temperature
Authors: Bae Seongjun , Song Hyeon don , Nam Inho , Kim Gil-Pyo , Park Soomin , Yoo Young Geun , Park Jongseok , Yi Jongheop
Published: February 2020

A demand for lithium ion batteries which able to operate under harsh condition (e.g. low temperature) is increasing due to its application for the electric vehicles. However, there are still technical bottlenecks for fabrication of a battery cell operating at low temperature. To solve this problem, various parameters and its effects for the kinetic mechanism during battery charge/discharge should be clarified. Computational approach is exploited to understand the relationship between performance of battery and kinetic parameters. In this study, we choose three independent parameters which affects to capacity and operating potential of the battery: the diffusion coefficient of lithium ion in active material, the lithiation constant at the surface of the active material and the particle radius of the active material. Based on pseudo-2D model, the capacity and the operating potential are calculated by varying diffusion coefficient, rate constant, and particle radius. Because diffusion coefficient and rate constant is dependent on temperature, the performance of battery drastically decline at certain temperature. From this theoretical basis, we calculate the particle radius of active material for maximizing the capacity and the optimal operating voltage at low temperature.
Nanocrystaline Beta-Ni(OH)2 Cathodes and Their Nanoelectrofuel Analogs for Flow Batteries
Authors: Li Yue , Aryal Shankar , Sen Sujat , Timofeeva Elena V. , Segre Carlo U , Ramani Vijay K
Published: February 2020

β-Ni(OH)2 is a discharged form of NiOOH which is common cathode for a family of nickel-based batteries including Ni/Cd, Ni/Fe, Ni/Zn, Ni/MH with theoretical capacity of 289 mAh/g. Previous studies have shown that introduction of nano-size β-Ni(OH)2 could dramatically increase the electrochemical performance, e.g. smaller polarization and better discharge capacity than commonly used micro-sized Ni(OH)2 mainly due to the enhancement of proton diffusion in nickel hydroxide electrode [1, 2]. Ni(OH)2 and NiOOH have been extensively studied before in bulk form including x-ray diffraction (XRD) and x-ray absorption fine structure (XAFS) techniques [3-6]. In situ EXAFS was used to study the progressive structure change during discharge and compare structures of Ni(OH)2in charged and discharged state [7, 8].

Our work focuses on the development of a suspension form of Ni(OH)2electrodes, also called nanoelectrofuels (NEFs). NEFs are stable dispersions of nano-scale battery active materials in the electrolytes that can be used in flow batteries as high energy density liquid energy storage. The main advantage of NEFs compared to traditional flow battery electrolytes is that high concentrations of active materials, and therefore energy density as concentration of nanoparticles in suspensions it is not limited by solubility of redox salts.

The presentation will discuss how different morphologies and crystallinities of β-Ni(OH)2 nanoparticles can be achieved through a simple one-step synthesis method; analysis with scanning electron microscopy (SEM), XRD, and thermogravimetric analysis (TGA) techniques; electrochemical characterization, including cyclic voltammetry, charge/discharge curves and life cycle analysis for different synthesis products in NEF formulations and compare their performance to the solid state analogs. In addition, we will present results from our in situ XAFS study of structural and electronic changes taking place during charge and discharge cycles in β-Ni(OH)2 cathodes.

References

[1] Guan X. Y, Deng J. C., Materials Letters, 61 (2007) 621-625.

[2] Han X. J., Xu P., Xu C. Q., Zhao L., Mo Z. B., Liu T., Electrochemica Acta, 50 (2005) 2763-2769.

[3] Pandya K. I., O’Grady W. E., Corrigan D. A., McBreen J., and Hoffman R. W., J. Phys. Chem., 94 (1990) 21-26.

[4] Ichiyanagi Y., Kondoh H., Yokoyama T., Okamoto K., Nagai K., Ohta T., Chemical Physical Letters, 379 (2003) 345-350.

[5] Morishita M., Kakeya T., Ochiai S., Ozaki T., Kawabe Y., Watada M., Sakai T., Journal of Power Sources, 193 (2009) 871-877.

[6] Capehart T. W., Corrigan D. A., Conell R. S., Pandya K. I., Hoffman R. W., Applied Physics Letters, 865 (1991) 58.

[7] Farley N. R. S., Gurman S. J., Hillman A. R., Electrochemica Acta, 46 (2001) 3119-3127.

[8] Farley N. R. S., Gurman S. J., Hillman A. R., J. Synchroton. Rad., 6 (1998) 198-200.
Degradation Study of Yttria Doped Barium Cerate (BCY) Electrolyte in Protonic Ceramic Fuel Cells Under Various Test Conditions
Authors: Kim Young Jin , Park Mi-Young , Lim Hyung-Tae
Published: February 2020

Acceptor-doped barium cerate has been considered as a potential electrolyte material in solid oxide fuel cell because of its high proton conductivity at temperatures below 7000C.  However, despite its superior transport property, barium cerate cannot be practically used in fuel cell due to its poor chemical stability in the atmosphere of water vapor and carbon dioxide. In the present work, we fabricated two kinds of BCY based anode supported cells, 1) BCY single layer cell and 2) BCY/BZY bi-layer cell, and their stability and degradation mechanism were investigated and compared, especially under severe operating conditions such as a negative voltage and low air flow rate. Constant current (CC) tests were conducted on the cells under various operating conditions such as positive vs. negative cell voltage and high vs. low fuel/air flow rate. Constant current (CC) tests were conducted on the BCY single layer and BCY/BZY bi-layer cells under a negative well as well a positive cell voltage as a function of air flow rate. Before and after the CC tests, I-V curve and impedance spectra were measured and compared to trace any increase in ohmic and/or non-ohmic resistance of the cells. Post-material analyses were conducted using scanning electron microscopy (SEM), X-ray diffraction (XRD) and energy dispersive spectroscopy (EDS) to find out any change in microstructure and phase after severe operations.
Preparation of Sn-Cu/Graphene Nanocomposite for High-Performance Lithium-Ion Batteries
Authors: Uysal Mehmet , Cetinkaya Tugrul , Algül Hasan , Tokur Mahmud , Kartal Muhammet , Alp Ahmet , Akbulut Hatem
Published: February 2020

Sn-Cu-graphene composites have been synthesized through a facile one pot co-precipitation method. The Graphene and copper could provide additional mechanical strength to prevent the crack and pulverization of the electrode structure during repeated volume expansion and contraction, which helps to maintain the integrity of the Sn electrodes and the electrically conductive network, and eventually leads to better cycling performance. Graphene can enhance mechanical properties, prevent the aggregation between Sn-Cu nanoparticles, and provide enough void space to buffer volume change of Sn-Cu. The surface morphology of the produced core-shell Sn-Cu/Graphene composite powders was characterized using scanning electron microscopy (SEM), transmission electron microscopy (TEM) and energy dispersive spectroscopy (EDS) and Raman spectroscopy X-ray diffraction (XRD) analysis was performed to investigate the structure of the Sn-Cu/Graphene composite powders. The lithium storage capability of the composites electrode is evaluated by cyclic voltammetry and galvanostatic charge-discharge tests. The resistivities of the produced Sn-Cu/Graphene composite electrodes were studied using electrochemical impedance spectroscopy (EIS).  The results show that the Sn-Cu composites embedded in graphene exhibit superior lithium storage performance compared to pure Sn, Sn-Cu, Sn-Graphene, Graphene composites due to the buffering effects of Cu and the excellent confinement and conductivity of graphene.
Capacity Fade Mechanisms of NaTi2(PO4)3 When Used As an Aqueous Anode
Authors: Mohamed Alexander I
Published: February 2020

The capacity fade of NaTi2(PO4)3 when used as an anode material in aqueous electrolytes was investigated using electrochemical methods including electrochemical impedance spectroscopy (EIS) and galvanostatic intermittent titration technique (GITT), as well as transmission electron microscopy (TEM) and x-ray diffraction (XRD). Both EIS and GITT indicated a continual increase in resistance of the synthesized material with little change in the diffusion rate of the sodium ion into the structure. XRD showed no change in crystallinity of the material after cycling. Morphological characterization using TEM showed an amorphous sodium phosphate layer formed between the in-situ carbon coating and the NaTi2(PO4)3 particles during synthesis when titania particles >100nm were used in the precursor powder. This layer was not present when smaller titania particles were used. Additionally, TEM showed the in-situ carbon coating became detached from the active material upon cycling. We believe this detachment of the conductive coating is the primary cause of capacity fade during cycling when the small titania particles are used in the synthesis. A better understanding of the detachment mechanism is needed to improve the cycle stability of NaTi2(PO4)3 materials in aqueous solutions.
Modeling and Simulation of Heat of Mixing in Lithium Ion Batteries
Authors: Song Zhibin , Yan Bo , Lim Cheolwoong , Zhu Likun
Published: February 2020

Heat generation is a major safety concern in the design and development of lithium ion batteries (LIBs) for large scale applications, such as electric vehicles. The total heat generation in LIBs includes entropic heat, enthalpy, reaction heat, and heat of mixing (1-3). The heat of mixing will be released during relaxation of Li ion concentration gradient. For instance, after the drivers turn off their vehicles, the generation of entropy, enthalpy and reaction heat in LIBs will stop, but the heat of mixing is still being generated. Thomas and Newman derived  methods to compute heat of mixing in LIB cells and investigated the heat of mixing on a Li|LiPF6 in ethylene carbonate:dimethyl carbonate|LiAl0.2Mn1.8O4-δF0.2 cell (4). The objective of this study is to investigate the influence of heat of mixing on the LIBs with different materials, porosities, particle sizes, and charge/discharge rate and to understand whether it is necessary to consider heat of mixing during the design and development of LIBs.  

In this study, a mathematical model was built to simulate heat generation of LIBs using COMSOL Multiphysics. The LIB model was based on Newman’s model. LiCoO2 was applied as the cathode materials, and LiC6 was applied as the anode material. The results of heat of mixing were compared with the other heat sources to investigate the weight of heat of mixing in the total heat generation. Table 1 shows the heat of mixing, irreversible heat, and reversible heat in anode and cathode electrodes at 5 min during a 2 C discharge process. As shown in Table 1, the heat of mixing in cathode is smaller than the heat of mixing in anode, mainly due to the lower Li ion diffusivity and larger particle size of LiC6. The heat of mixing is not as much as the irreversible heat and reversible heat, but it cannot be neglected for this operating condition. The heat of mixing in different LIB cells and under different operating conditions will be reported.

The mathematical model equation(1):

Show in Image 1.

Acknowledgments: This work was supported by the American Chemical Society
Petroleum Research Fund.

Table 1. Comparison of the heat of mixing within active material particles with irreversible and reversible heat sources at 5 min during a 2 C discharge process.

 
Cathode(LiCoO2)
Anode(LiC6)

Heat of mixing
3.92 J/m2

293.60 J/ m2

Irreversible heat
460.97 J/m2

1354.86 J/m2

Reversible heat
1370 J/m2

-813 J/m2

 References:

1.            K. E. Thomas and J. Newman, Journal of the Electrochemical Society, 150, A176 (2003).

2.            B. Yan, C. Lim, L. Yin and L. Zhu, Journal of the Electrochemical Society, 159, A1604 (2012).

3.            K. Kumaresan, G. Sikha and R. E. White, Journal of the Electrochemical Society, 155, A164 (2008).

4.            K. E. Thomas, C. Bogatu and J. Newman, Journal of the Electrochemical Society, 148, A570 (2001).

Figure 1