Lithium Ion Conducting Glass Ceramics Research Articles

A Redox‐Based Ion‐Gating Reservoir, Utilizing Double Reservoir States in Drain and Gate Nonlinear Responses

Herein, physical reservoir computing with a redox‐based ion‐gating reservoir (redox‐IGR) comprising LixWO3 thin film and lithium‐ion conducting glass ceramic (LICGC) is demonstrated. The subject redox‐IGR successfully solves a second‐order nonlinear dynamic equation by utilizing voltage pulse driven ion‐gating in a LixWO3 channel to enable reservoir computing. Under the normal conditions, in which only the drain current (ID) is used for the reservoir states, the lowest prediction error is 8.15 × 10−4. Performance is enhanced by the addition of IG to the reservoir states, resulting in a significant lowering of the prediction error to 5.39 × 10−4, which is noticeably lower than other types of physical reservoirs (memristors and spin torque oscillators) reported to date. A second‐order nonlinear autoregressive moving average (NARMA2) task, a typical benchmark of reservoir computing, is also performed with the IGR and good performance is achieved, with a normalized mean square error (NMSE) of 0.163. A short‐term memory task is performed to investigate an enhancement mechanism resulting from the IG addition. An increase in memory capacity, from 2.35 without IG to 3.57 with IG, is observed in the forgetting curves, indicating that enhancement of both high dimensionality and memory capacity is attributed to the origin of the performance improvement.

Gate-controlled magnetic transitions in Fe3GeTe2 with lithium ion conducting glass substrate* *Project supported by the National Basic Research Program of China (Grant Nos. 2019YFA0308402 and 2018YFA0305604), the National Natural Science Foundation of China (Grant Nos. 11934001, 11774010, and 11921005), and Beijing Municipal Natural Science Foundation, China (Grant No. JQ20002).

Since the discovery of magnetism in two dimensions, effective manipulation of magnetism in van der Waals magnets has always been a crucial goal. Ionic gating is a promising method for such manipulation, yet devices gated with conventional ionic liquid may have some restrictions in applications due to the liquid nature of the gate dielectric. Lithium-ion conducting glass-ceramics (LICGC), a solid Li+ electrolyte, could be used as a substrate while simultaneously acts as a promising substitute for ionic liquid. Here we demonstrate that the ferromagnetism of Fe3GeTe2 (FGT) could be modulated via LICGC. By applying a voltage between FGT and the back side of LICGC substrate, Li+ doping occurs and causes the decrease of the coercive field (H c) and ferromagnetic transition temperature (T c) in FGT nanoflakes. A modulation efficiency for H c of up to ∼ 24.6% under V g = 3.5 V at T = 100 K is achieved. Our results provide another method to construct electrically-controlled magnetoelectronics, with potential applications in future information technology.

Enhanced Durability of a Lithium Ion Secondary Battery Using Solid Electrolyte LICGCTM

Lithium Ion Conducting Glass Ceramic (LICGCTM) with a NASICON type structure was developed using industrial glass melting methods and functions as a solid lithium ion electrolyte.1-3) The ionic conductivity of the glass ceramic with Li1+x+yAlxTi2–xSiyP3–yO12 specific composition has values equal to or greater than 1×10-3 Scm-1 at room temperature. The NASICON type structure of LICGCTM was formed and crystalized in the starting bulk amorphous glass during heat treatment. The resulting glass ceramic has high chemical resistance and does not lose weight in boiling distilled water. The ionic conductivity of this electrolyte does not deteriorate, even if soaked in an aqueous of Li salt solution4-5. These characteristics indicate LICGCTM might be used to partially replace organic electrolytes and to enhance the properties of lithium ion secondary batteries.The effects of using LICGCTM in powder form as a cathode additive for lithium ion secondary batteries were investigated by OHARA is presented in this paper. LICGCTM powder of a controlled particle size, 0.4μm(D50), was prepared to fit into the inter-particle gaps of active materials generally used in a cathode. The cathode slurry was prepared by mixing standard cathode component materials (active material, carbon, binder) with LICGCTM powder and NMP. The slurry was then coated onto Al foil to form the cathode. The electrochemical performance of the NMC cathode, when evaluated in a half cell, indicated a capacity increase of 21% at 3C discharge and a reduced charging time of 20% at CC-CV condition, compared to a standard cathode with equal capacity. A full cell was fabricated using the cathode containing the LICGCTM powder additive and a carbon anode. The DC resistance of the full cell at DOD50 was decreased by more than 20%. We confirmed that LICGCTM powder when used as a cathode additive is effective in enhancing the performance of lithium ion secondary batteries. OHARA proceeded to evaluate battery retention capacity at 60℃. At this temperature, the charge and discharge cycle numbers of a lithium ion battery containing 1% LICGCTM powder in the NMC cathode increased by 4 times, at the point where the retention capacity is typically decreased by 10%, and the battery capacity at 300 cycles was increased by 14%. In the case of a lithium ion battery containing 1% LICGCTM powder additive in the LCO cathode at 60℃, the retention capacity was increased by 13% at 300 cycles. It was determined the 1% LICGCTM powder additive in the cathode inhibits the generation of the resistive layer and X-ray absorption spectroscopy (XAS, Ritsumeikan Univ. SR center) indicated the improved surface state of the LCO active material resulted in longer battery lifetime. OHARA’s results indicate that cathodes containing LICGCTM glass ceramic electrolyte powder can significantly improve battery retention capacity, by controlling the degradation of the cathode, when charging and exposed at high temperature.

Novel lithium selective composite membranes: synthesis, characterization and validation tests in dialysis

With the general growing demand for Lithium compounds, notably for use in Lithium ion batteries, the selective extraction of this metal from various different sources is generating a lot of attention. A number of different methods have been used to recover and/or separate this element, often involving membranes technologies. In an attempt to overcome issues raised by the high rigidity of ceramic membranes and the poor selectivity performance of polymer membranes, we have tried to combine the Li selectivity of Lithium Ion Conducting Glass Ceramic (LICGC) and the flexibility of polymers. We are therefore proposing new malleable composite membranes made using a blending technique where the LICGC powder is incorporated into a flexible copolymerized anion-exchange membrane. We have attempted to demonstrate the homogeneity of the inorganic particle dispersion in the six prepared Lithium Composite Membranes (LCMs) as well as their thermal stability and mechanical properties. We have also investigated the effects of membrane composition on the physicochemical characteristics (water sorption, contact angle and conductivity) of the membranes. The selectivity of these LCMs for Li+ was tested under dialysis conditions using Na+ and K+ as the competitive cations, and the results were compared to those obtained with control membranes containing no LICGC particles. For the best membrane LCM5, the Li+/Na+ selectivity coefficient reaches 376 when using only Na+ as competitive ion. Whilst, when using both Na+ and K+, this selectivity (Li+/Na+) decrease to 278 and the Li+/K+ selectivity coefficient is found to be 364.

Lithium-protective hybrid lithium-air batteries with CFx, MoS2, and WS2 composite electrodes

Numerous studies have addressed the commercial viability of lithium–air batteries (LABs). However, the high reactivity of Li with air moisture and CO2 has hindered the broad applicability of LABs. In this study, lithium-protective hybrid lithium–air batteries (HLABs) were fabricated with Super P (SP) and composites of fluorinated carbon (CFx), MoS2, and WS2 as the cathodes. Subsequently, their potential use as a power source for the next generation of defense technologies was investigated. It was observed that a single cell HLAB with the SP-CFx composite cathode exhibited a specific capacity of 893 mAhg−1cathode. In comparison, a Tomcell with the SP cathode demonstrated a specific capacity of 465 mAhg−1cathode when discharged. The cells with SP-MoS2 and SP-WS2 cathode yielded specific capacities of 357 and 386 mAhg−1cathode, respectively. The improved performance of the SP-CFx cell can be attributed to synergistic effects of lithium–air cell and lithium battery reactions between CFx and SP. To assess all functionalities of the SP-CFx HLAB, lithium-protective HLABs were fabricated and discharged in air. To operate the lithium–air battery in air, pure lithium metal was sealed with solid electrodes (lithium-ion conducting glass–ceramics (LICGC)) and a buffer electrolyte (1 M LiFTSI in TEGDME) was applied. The SP-CFx cell was discharged for 25 days in air, greatly exceeding the 72 h requirement for the next-generation soldier power systems. These results demonstrate significant potential for HLABs to be used as a pioneering power source in next-generation energy-independent tactical defense units.

Molten Lithium Battery for Space Applications

Solid-state electrolytes (SEs) have gained much interest lately as a potential for mitigating the various issues inherent in a most energy dense lithium metal (anode) based batteries such as lithium ion, lithium sulfur (Li-S), and lithium oxygen. Notable high energy next generation cathodes such as sulfur have their own issues with a liquid electrolyte based system, where the polysulfides discharge product dissolve into the electrolyte causing both: a loss of cathode active material and an unwanted shuttling of the polysulfides over the polymer separator to the lithium anode limiting their practical use. Moreover, the formation of lithium dendrites in lithium batteries is yet another challenging issue that not only limits battery cycle-life but also poses safety risks. The use of SEs can potentially address most of the issues related to next generation lithium batteries such as Li-S batteries, but getting rid of dendrite issues may not be addressed completely. One way to eliminate the dendrite issue is to use molten lithium as an anode.The National Aeronautics and Space Administration (NASA) has an ambitious plan to explore one of the most challenging planets in our solar system: Venus. The surface temperature of Venus can reach as high as 465°C and at same time, the Venus atmosphere is filled with corrosive gases such as carbon dioxide, sulfur dioxide, carbon monoxide, etc. A battery for such a challenging space mission can be built only if battery components (especially the electrolyte) is stable beyond 500°C and must be stable with molten lithium and sulfur electrodes for at least hours or days if not months—longer is better. Last but not the least, yet another challenge is containment of gaseous sulfur inside the battery container at such a high temperature. The potential to replace sulfur with selenium may mitigate the issue but at cost of reduced energy density.Under a NASA funded project, the University of Dayton Research Institute (UDRI) is developing molten lithium sulfur (Li-S) or lithium-selenium (Li-Se) batteries with the help of a high temperature solid ceramic electrolyte (SCE) that can enable a operating temperature >465°C for several hours. UDRI has been working on a high temperature SCE such as phosphate-based Li1+ xAlxGe2- x(PO4)3 (LAGP) ceramic electrolyte material1 that is stable beyond 500°C and also shows broad electrochemical window (up to 5V) that is sufficient for a molten Li-S or Li-Se battery operation; provided LAGP is stable with Li and S or Se in such harsh conditions and temperature. Unfortunately, LAGP is not stable with Li (forms a highly resistive interface layer between LAGP and electrode) and its stability with sulfur or Se, needs to be determined.Under the NASA project, UDRI has been developing interface materials between LAGP and electrodes for Li-S and Li-Se cells that can be stable at wide temperature range (room temperature to 500°C). The presentation will include progress on high temperature (up to 465°C) i) SCE, ii) SCE/Li interface materials, iii) SCE/S interface material, iv) SCE/Se interface material, v) impedance and open circuit voltage of Li-S or Li-Se cells at 465°C, and vi) cycle-life of Li-S or Li-Se cells at 465°C. To the authors knowledge, there is no such report (molten Li-S or Li-Se cells that can function at 465°C) that exists in literature.B. Kumar, D. Thomas, J. Kumar, “Space-Charge-Mediated Superionic Transport in Lithium Ion Conducting Glass–Ceramics,” J. Electrochem. Soc. 156, A506 (2009)

Lithium-ion conducting glass ceramics for electrostatic gating

We explore solid electrolytes for electrostatic gating using field-effect transistors (FETs) in which thin WSe2 crystals are exfoliated and transferred onto a lithium-ion conducting glass ceramic substrate. For negative gate voltages (VG < 0), the devices work equally well as ionic liquid gated FETs while offering specific advantages, whereas no transistor action is seen for VG > 0. For VG < 0, the devices can nevertheless be driven into the ambipolar injection regime by applying a large source-drain bias and strong electroluminescence is observed when direct band-gap WSe2 monolayers are used. Detecting and imaging the emitted light is much simpler in these FETs as compared to ionic liquid gated transistors, because the semiconductor surface is exposed (i.e., not covered by another material). Our results show that solid electrolytes are complementary to the existing liquid gates, as they enable experiments that are not possible when the semiconductor is buried under the liquid itself.

Electrochemical Synthesis of Ammonia from Water and Nitrogen: A Lithium-Mediated Approach Using Lithium-Ion Conducting Glass Ceramics.

Lithium-mediated reduction of dinitrogen is a promising method to evade electron-stealing hydrogen evolution, a critical challenge which limits faradaic efficiency (FE) and thus hinders the success of traditional protic-solvent-based ammonia electro-synthesis. A viable implementation of the lithium-mediated pathway using lithium-ion conducting glass ceramics involves i) lithium deposition, ii) nitridation, and iii) ammonia formation. Ammonia was successfully synthesized from molecular nitrogen and water, yielding a maximum FE of 52.3 %. With an ammonia synthesis rate comparable to previously reported approaches, the fairly high FE demonstrates the possibility of using this nitrogen fixation strategy as a substitute for firmly established, yet exceedingly complicated and expensive technology, and in so doing represents a next-generation energy storage system.

A systematic study of glass stability, crystal structure and electrical properties of lithium ion-conducting glass-ceramics of the Li1+xCrx(GeyTi1-y)2-x(PO4)3 system

This study examines the effect of substituting Ti by Cr and Ge on the glass stability of the precursor glass and on the electrical properties of the lithium ion-conducting glass-ceramics of the Li1+xCrx(GeyTi1-y)2-x(PO4)3 (LCGTP) system. A set of compositions of this system is synthesized by the melt-quenching method followed by crystallization. The main results indicate that the glass stability of the precursor glasses increases when Ti is replaced by Ge and Cr. After crystallization, all the glass-ceramics present NASICON-type phase, and their lattice parameters decrease with Ge and increase with Cr content, making it possible to adjust the unit cell volume of the NASICON-like structure. Furthermore, the ionic conductivity and activation energy for lithium conduction in the glass-ceramics are notably dependent on the unit cell volume of the NASICON-like structure. The Li1.6Cr0.6(Ge0.2Ti0.8)1.4(PO4)3 glass-ceramic composition shows the highest overall ionic conductivity (2.9 × 10−4 Ω−1 cm−1) at room temperature and reveals remarkably high ionic conductivity (1.2 × 10−3 Ω−1 cm−1) and low activation energy (0.259 eV) regarding grain contribution. The main findings suggest that the proposed system is promising to develop fast Li ion-conducting glass-ceramics, offering a compromise between the glass stability of the precursor glass and the electrical properties of the resulting glass-ceramic.

Enhanced Electrochemical Performance of the Cathode for a Lithium Ion Secondary Battery Using Lithium Ion Conductive Glass-Ceramics

Ceramics powder such as SiO2 and Al2O3 are incorporated in to the polymer electrolyte to form the composite film for the sake of improving ionic conductivity, mechanical and thermal properties. Though these filler enhanced ionic conductivity of gel electrolyte due to the disruption of polymer matrix and increasing micro pores, these are not ionic conductive material. We found that the gel electrolyte film (Pvdf based polymer) was enhanced ionic conductivity by adding LICGCTM. We have developed lithium ion conducting glass-ceramics LICGCTM with a NASICON type structure for solid lithium ion electrolyte.1- 3) The ionic conductivity of the glass ceramics with a Li1+x+yAlxTi2-yGeyPO4 composition shows over 1×10-4 Scm-1 at room temperature. Such ceramics have a very stable in ionic conduction. In addition, the ionic conductivity does not decrease, even if it was soaked in an aqueous of Li salt solution4-5), and does not lose the weight in boiling distilled-water for 1 h. The glass-ceramics with the crystalline form of Li1+x+yAlxTi2–xSiyP3–yO12 with a NASICON-type structure by heat-treated glass with a specific composition1-2). This glass-ceramics has a high lithium-ion conductivity that is equal to or more than 10–3 Scm–1at room temperature. Furthermore, because it is very stable in the atmosphere and even to exposure to moist air, it is possible to use this material to apply a solid-electrolyte for a lithium ion secondary battery using organic liquid electrolyte. In this work, the effect of LICGCTM as additive for a lithium ion secondary battery was investigated. We synthesized LiCoO2 cathode with 5wt.% LICGCTM filler and evaluated it the charge and discharge property using a half cell. We confirm the rate performance at room temperature is enhanced at 0.2-3.0C comparing pristine LiCoO2 cathode. The rate performance was indicated 20 percent increasing at 2.0C rate as compared to pristine LiCoO2 cathode. The charging performance was also enhanced at higher rate at room temperature.

Composite Inorganic-Organic Electrolytes for Use in All-Solid-State Li Batteries

In order to make safe and efficient lithium /lithium ion batteries (LIBs) or sodium/sodium batteries (SIBs) in the future, particularly for large scale energy storage and for electric (EV) or hybrid (HEV) electric vehicle applications, a key component is a solid separator between the anode and cathode, since it would allow the safer use of Lio or Nao, which would markedly increase energy density and specific capacit(by 10 fold for a given cathode material) compared with Li+ intercalation anodes. The use of Li0 is essential to achieve the theoretically predicted high specific energy in Li-O2and Li-S batteries. Currently, there are two main approaches to the development of solid separators, namely the synthesis and use of (i) ceramic materials, sometimes referred to as lithium ion conducting glass ceramic (LICGC), and (ii) solid polymer electrolytes (SPEs) with dissolved bi-ionic LiX or with pendant anions (referred to as polymer SICs)1. The advantages of ceramic electrolytes (high conductivity (s), tLi += 1) and polymer electrolytes (flexibility, adhesion to electrode, electrode stability) would be ideal in a hybrid separator, but ionic ceramics and organic polymers are inherently incompatible, so there is typically a high interfacial resistance between them. For pure inorganic and organic electrolytes, sLICGC >> spolymer, so that increased volume fractions of the LICGC are desirable. At small volume fractions of the LICGC, the conductivity increases are only comparable to those obtained by adding inert inorganic fillers such as SiO2, TiO2 and Al2O3 to polymers (usually PEO/LiX), where composite ionic conductivity increases by suppression of the PEO crystallinity or by decreasing the affinity of the anion for the Li cation. At large volume fractions of LICGC, stotal → sLICGC is almost never realized and the polymer appears to act as a binder for the grains with conductivities 10-100 fold less than the LICGC. This decrease has been attributed to an inability of the Li+ (or Na+) ions to cross the ceramic-polymer interface (resulting in high interfacial resistance), with one factor a lack of intimate interfacial contact between the phases. In order to solve the high interfacial resistance problem, we have investigated a general approach (as shown Figure 1) to form an interface that would be applicable to a wide range of hybrid systems, and one that would also prevent LICGC corrosion by Li0. Briefly, we sputter coated a 200 nm thick SiO2 coating onto a commercial LICGC, and silanated it with polyethylene glycol (PEG)-silane in the presence of LiTFSI. SEM (Figure 1 Bottom A and B) images of the SiO2 layer clearly show a conformal coating of the SiO2 on the LICGC, while the top viewsof this coating suggest that it is deposited with ~ 100 nm grains between which are channels. After silanization, there are covalently attached PEG chains to the SiO2 and a smooth “polymer” coating is also formed from hydrolysis and cross-linking of the PEG-silane (Figure 1 Bottom C). The covalently attached PEG chains permit Li+ion diffusion through the interface. (O/Li = 12/1). The formed composite inorganic-organic electrolyte has low interfacial resistance (as shown in Figure 2). The thin film coating allows the hybrid composite membrane to adhere to Li0 metal, prevents corrosion of the LICGC by the Li0 metal, and is stable with Lioelectrodes. A film made with the PEG-silane in the presence of LiTFSI was a self-standing soft rubber. In summary, we have developed a general approach to form an interface between ceramic and solid polymer electrolytes which ultimately improves the stability of ceramic electrolytes with Lio electrodes and decreases the interfacial resistance between the polymer and ceramic. Acknowledgements: The financial support of the National Science Foundation, Award CBET 1437814 is gratefully acknowledged. References (1) Fergus, J. W. Journal of Power Sources 2010, 195, 4554. (2) Chinnam, P. R.; Wunder, S. L. ACS Energy Letters 2017, 2, 134-138 Figure 1

A new NASICON lithium ion-conducting glass-ceramic of the Li1 + xCrx(GeyTi1 − y)2 − x(PO4)3 system

We propose a new lithium ion-conducting glass-ceramic based on the Li1+xCrx(GeyTi1−y)2−x(PO4)3 (LCGTP) system. A specific composition (x=y=0.4) of this system was synthesized by the melt-quenching method, followed by crystallization. The crystallization behavior of the precursor glass was examined by differential scanning calorimetry(DSC) and infrared spectroscopy (IR). The main results indicate that the LCGTP precursor glass presents homogeneous nucleation and considerable glass stability, which allows solid electrolytes to be obtained by the glass-ceramic route. After heat treatment, this glass crystallizes in a NASICON LiTi2(PO4)3-type phase, demonstrating that the proposed system can accommodate Cr, Ti and Ge in an octahedral site. Different heat treatment temperatures were employed to obtain these glass-ceramics. Ionic conductivity was measured by electrochemical impedance spectroscopy (EIS). The sample heat-treated at 900°C for 12h showed the highest ionic conductivity at room temperature (6.6×10−5Ω−1cm−1). This specific glass-ceramic presented a remarkably low activation energy (0.274eV) related to grain contribution, which culminated in a grain conductivity of 8.5×10−4Ω−1cm−1 at room temperature. In addition, a correlation was found between the cell volume and the activation energy for lithium conduction. The samples' microstructures were examined by scanning electron microscopy (SEM) and were also correlated to their ionic conductivity. This set of results suggests that the proposed system is promising for the development of fast lithium ion-conducting glass-ceramics with further compositional optimization.

On Leakage Current Measured at High Cell Voltages in Lithium-Ion Batteries

In this study, parasitic side reactions in lithium-ion batteries were examined experimentally using a potentiostatic hold at high cell voltage. The experimental leakage current measured during the potentiostatic hold was compared to the Tafel expression and showed poor agreement with the expected transfer coefficient values, indicating that a more complicated expression could be needed to accurately capture the physics of this side reaction. Here we show that cross-talk between the electrodes is the primary contribution to the observed leakage current after the relaxation of concentration gradients has ceased. This cross-talk was confirmed with experiments using a lithium-ion conducting glass ceramic (LICGC) separator, which has high conductance only for lithium cations. The cells with LICGC separators showed significantly less leakage current during the potentiostatic hold test compared to cells with standard microporous separators where cross-talk is present. In addition, direct-current pulse power tests show an impedance rise for cells held at high potentials and for cells held at high temperatures, which could be attributed to film formation from the parasitic side reaction. Based on the experimental findings, a phenomenological mechanism is proposed for the parasitic side reaction which accounts for cross-talk and mass transport of the decomposition products across the separator.

Engineered Interfaces in Hybrid Ceramic–Polymer Electrolytes for Use in All-Solid-State Li Batteries

Composites of inorganic lithium ion conducting glass ceramics (LICGCs) and organic polymers may provide the best combination of properties for safe solid separators in lithium or lithium ion batteries to replace the currently used volatile liquid electrolytes. A key problem for their use is the high interfacial resistance that develops between the two, increasing the total cell impedance. Here we show that the application of a thin conformal SiO2 coating onto a LICGC followed by silanization with (CH3CH2O)3–Si–(OCH2CH2)–OCH3 in the presence of LiTFSI results in good adhesion between the SiO2 and the LICGC, a low resistance interface, and good wetting of Li0. Further, the cross-linked polymer formed on the surface of the silanated SiO2 interface formed from excess (CH3CH2O)3–Si–(OCH2CH2)–OCH3 prevents corrosion of the LICGC by Li0 metal. The use of SiO2 as a “glue” enables compatibilization of inorganic ceramics with other polymers and introduction of interfacial pendant anions.

Spark Plasma Sintering Study on the Super Ionic Glass Ceramic Conductor: Li7P3S11

Solid-state electrolytes that can perform on par with conventional liquid electrolytes are highly sought after for use in all solid-state batteries. An all solid-state battery promises to operate without the possibility of catastrophic failure and have substantially longer self-life than conventional batteries. The Li7P3S11 glass-ceramic is one class of solid electrolytes that could meet the sought after power and reliable performances. We demonstrate a rapid synthesis and densification of the supersonic conductor electrolyte Li7P3S11via spark plasma sintering (SPS) technique. Dense solid-state electrolytes have been formed with a room temperature ionic conductivity is comparable to conventional liquid electrolyte. Hayashi, A., Ishikawa, Y., Hama, S., Minami, T. & Tatsumisago, M. Fast Lithium-Ion Conducting Glass-Ceramics in the System Li[sub 2]S-SiS[sub 2]-P[sub 2]S[sub 5]. Electrochem. Solid-State Lett. 6, A47 (2003).Seino, Y., Ota, T. & Takada, K. A sulphide lithium super ion conductor is superior to liquid ion conductors for use in rechargeable batteries. Energy … 7, 627 (2014).Hayashi, A., Minami, K., Mizuno, F. & Tatsumisago, M. Formation of Li+ superionic crystals from the Li 2S-P2S5 melt-quenched glasses. J. Mater. Sci. 43, 1885–1889 (2008).Minami, K., Hayashi, A. & Tatsumisago, M. Crystallization Process for Superionic Li7P3S11 Glass-Ceramic Electrolytes. J. Am. Ceram. Soc. 94, 1779–1783 (2011).Minami, K., Hayashi, A. & Tatsumisago, M. Crystallization Process for Superionic Li7P3S11 Glass-Ceramic Electrolytes. J. Am. Ceram. Soc. 94, 1779–1783 (2011).Eom, M., Kim, J., Noh, S. & Shin, D. Crystallization kinetics of Li2S–P2S5 solid electrolyte and its effect on electrochemical performance. J. Power Sources 284, 44–48 (2015). Acknowledgments This work was supported by the National Science Foundation under grant number ACI-1053575.

Electromotive force measurements of LiCoO2 electrode on a lithium ion-conducting glass ceramics under mechanical stress

Two LiCoO2 dense film electrodes were prepared on both surfaces of a lithium ion-conducting glass ceramics, and electromotive force measurements were preformed between the film electrodes under mechanical compressive and tensile stresses by four-point bending tests. Electromotive force appeared immediately after applying the stress and disappeared after releasing the stress. The larger stress was applied, the larger electromotive force was observed. These results clearly demonstrated that the lithium chemical potential in the LiCoO2 electrode varies under mechanical stress. The influence of the mechanical stress on the lithium chemical potential was discussed based on the relation between the CoO2 interlayer distance and the lithium concentration in LiCoO2.

Study of the Interface Layer Between Lithium Metal and a Single Ion Conductor Ceramic, Based on Block Copolymer, for Lithium Air Batteries

The electrification of transport is a formidable challenge, however the energy storage possible in Li ion batteries is not sufficient to this purpose. A potential option is Lithium-air battery, first because of their very high energy densities and second because of their low costs. Two different approaches to the development of these batteries are possible: the anhydrous system which uses an organic electrolyte, and the aqueous system which uses an aqueous electrolyte [1]. An advantage of the aqueous system is its safety since toxic or inflammable solvents are not used. In order to protect the negative lithium electrode from the aqueous electrolyte, a thin ceramic water and gas tight membrane is used. The interface between the lithium metal and the ceramic membrane plays an important role in the cycling performance of the aqueous lithium air cell. Nonetheless, the poor or non-chemical stability of most ceramic electrolytes in contact with lithium metal limits the performance. A possible strategy to improve the interface between ceramic electrolyte and lithium metal might be by the use of polymer membranes [2]. This study reports the effect of a polymer membrane between a ceramic electrolyte and lithium metal. Block copolymer electrolytes, such as polystyrene-block-poly (ethylene oxide) copolymer electrolyte (SEO) mixed with lithium bis(trifluoromethanesulfonyl) imide (LiTFSI) salt, were used. The single ion conductor ceramic electrolyte was a Lithium Ion Conducting Glass Ceramic (LICGC) purchased from Ohara Corporation (1 inch X 1 inch 150µm thick). Impedance spectroscopy has been used, so as to study the lithium ion - lithium metal transfer from a lithium ion conducting polymer interface. Furthermore, in order to know if the sandwich polymer-ceramic cell showed an additional interfacial resistance, ionic conductivity experiments using electrochemical impedance spectroscopy were performed. Besides, polarization loss quantification at a lithium ion conducting polymer/single ion conductor interface was studied by DC current measurement by the Srinivasan et al method [3]. Finally, in order to confirm the intimacy of the ceramic and the polymer, the interface between the ceramic and the polymer was studied by synchrotron hard X-Ray micro tomography experiments on symmetric lithium-sandwich polymer-ceramic cells. P.G. Bruce, S. A. Freunberger, L. J. Hardwick, J-M. Tarascon, Nature Materials, 11, 19-29 (2012)G.M. Stone, S.A. Mullin, A.A. Teran, D.T. Hallinan, A.M. Minor, A. Hexemer, N.P. Balsara, Journal of the Electrochemical Society 159(3) A222-A227 (2012)Mehrotra, P. N. Ross, V. Srinivasan, Journal of the Electrochemical Society, 161 (10) A1681-A1690 (2014)

Invited Presentation: Lithium Dendrite Formation at the Interface Between Lithium Metal and PEO Complexed with Various Lithium Salts

Protected Lithium Electrode for Aqueous Lithium-Air Rechargeable BatteriesNobuyuki Imanishi Department of Chemistry, Mie University, Tsu , Japan The novelty of aqueous lithium air battery is the introduction of a protected lithium electrode using an impermeable lithium ion-conducting glass ceramics, Li1+x+y(Ti,Ge)1-xAlxP3-ySiyO12 (LTAP), which enables lithium metal anode feasible in the aqueous electrolyte with a narrow electrochemical window and boosts the specific energy density of this system coupling with a breathing air cathode [1]. The inherent drawback of LTAP is the high reduction tendency of its constituent, Ti4+ or Ge4+, in contact with lithium metal, which results in the generation of insulated reaction products. Several lithium-ion conducting interlayers have been proposed to address this issue, such as lithium nitride, lithium phosphorus oxynitride, polymer electrolytes as well as accustomed organic electrolytes. The two former materials are generally prepared by vapor deposition, which involves considerable cost and makes the preparation of large-sized cells difficult. In contrast, large-sized sheets of polymer electrolytes can be easily fabricated along with little concerns over lithium dendrites formation unlike the case for organic electrolytes.Protected lithium electrodes consisting of lithium metal anode, polymer electrolytes-based interlayers and LTAP are our proposed solution for the practical development of aqueous lithium air battery. However, two contradictory issues emerge; those are the lithium dendrite formation at the interface between lithium metal and polymer electrolyte interlayers and the rate capability of protected lithium electrodes.In our previous studies, the interfacial resistance between lithium metal and polymer electrolytes has been demonstrated a key factor in initiating lithium dendrite formation by addition of ionic liquids, oligomer ethers and/or nanofillers. All these additives can reduce the interfacial resistance substantially and prolong the onset time of lithium dendrite initiation. A prospective additive of tetraethylene glycol dimethyl ether was revealed to exhibit the onset time of ca. 13 h for protected lithium electrodes at 1.0 mA·cm-2. The anion of lithium salts complexed with polymer matrix was also identified to influence the dendrite initiation in our recent study, where bis (fluorosulfonyl) imide-FSI- exhibited the longest short-circuit time of symmetrical lithium pouch cell compared to other larger analogues.At high current densities, the onset time of lithium dendrite initiation is shortened and thus the capacity of protected lithium electrode that can deliver is limited. A protected lithium electrode capable of delivering a high areal capacity of 12 mAh·cm-2 or more at no less than 1.0 mA·cm-2 is critical to develop aqueous lithium air batteries for electric vehicle applications. However, the binary polymer electrolytes we are developing usually exhibit a low limiting diffusion current density and are prone to initiate lithium dendrite formation when the operating current density exceeds its inherent limiting diffusion current density due to the quick depletion of lithium cations and the accompanying instability of interface. Moreover, the low exchange current density for polymer electrolytes at the interface also limits the rate capability of protected lithium electrodes.Based on our previous findings, we are now envisaging a new concept for the lithium-ion conducting interlayer, such as solvent-in-salt systems and single-ion polymer electrolytes, to diminish the trade-off between the two aforementioned issues for protected lithium electrodes in the development of aqueous lithium air battery.[1] N. Imanishi and O. Yamamoto, Rechargeable lithium–air batteries: characteristics and prospects, Mater. Today, 17, 24 (2014).

Quantifying Polarization Losses in an Organic Liquid Electrolyte/Single Ion Conductor Interface

A novel way to quantify polarization losses at an organic liquid electrolyte/single ion conductor interface is presented. Different concentrations (0.2 M, 0.4 M, 0.6 M, 0.8 M, 1 M) of LiPF6 in EC:DEC (1:1), 1 M LiPF6 in DMSO, and 1 M LiPF6 in PC were used as organic electrolytes in the study. Lithium Ion Conducting Glass Ceramic (LICGC), commercially acquired from Ohara Corporation (1 in. × 1 in., 150 μm thick) was used as the single ion conductor (SIC). A custom Li-Li symmetric diffusion cell was designed for this study. For a given electrolyte of known composition, constant current cycling experiments were first performed in the absence of the SIC. Thereafter, SIC was incorporated in the cell such that it was sandwiched between two electrolyte chambers. The polarization loss from the cell was then extracted from these two sets of experiments after accounting for the Ohmic drop in the SIC and concentration polarization effects in the liquid electrolyte for a given current density, using a mathematical model. Results suggest that liquid electrolyte/SIC junction polarization could be significant. Such polarization losses will lead to a decrease in the cell voltage at high currents in next generation Li-S and Li-O2 cells.

Degradation of NASICON-Type Materials in Contact with Lithium Metal: Formation of Mixed Conducting Interphases (MCI) on Solid Electrolytes

We report on the transport properties of lithium ion conducting glass ceramics represented by the general composition Li1+x–yAlx3+My5+M2–x–y4+(PO4)3 with NASICON-type structure and their stability in contact with lithium metal. In particular, solid electrolyte phases with M = Ge, M = Ti, Ge, and M = Ti, Ta were investigated. AC impedance spectroscopy and DC polarization measurements were applied to determine the conductivity as a function of temperature, and to extract the partial electronic conductivity. The maximum total conductivity at room temperature was found to be about 4 × 10–4 S/cm for the solely Ge containing sample. We demonstrate that the combination of vacuum-based lithium thin film deposition and X-ray photoelectron spectroscopy (XPS) is well suited to study the reactivity of the solid electrolyte membranes in contact with lithium. As a major result, we show that none of the materials investigated is stable in contact with lithium metal, and we discuss the reactive interaction between solid electrolytes and Li metal in terms of the formation of a mixed (ionic/electronic) conducting interphase (MCI) following the well-known SEI concept in liquid electrolytes.