Flexible High Lithium-Ion Conducting PEO-Based Solid Polymer Electrolyte with Liquid Plasticizers for High Performance Solid-State Lithium Batteries.

Lithium-ion secondary batteries (LIB) with high energy density have attracted much attention for electric vehicle (EV) applications. However, LIBs have a safety problem because these batteries contain a flammable organic electrolyte. As such, all-solid secondary batteries that are not flammable have been extensively reported recently. In this study, we have focused on polymer electrolytes, which is flexible and is expected to address the safety problem. However, the conventional polymer electrolytes have low electrial conductivity at room temperature. Various attempts have been made to solve this problem, such as the addition of inorganic fillers and ionic liquids; however, these composite polymer electrolytes have not yet reached a practical level of lithium-ion conductivity. In this study, high electrical conductivity and lithium dendrite formation-free PEO based composite electrolytes are developed with both a filler of Li6,4La3Zr1.4Ta0.6O12 and liquid plasticizers of tetraethylene glycol dimethyl ether and 1,2 dimethoxyethane. The proposed flexible polymer electrolyte shows a high electrical conduciviy of 6.01×10-4 S cm-1 at 25 °C.

Tunnel-Structured Phosphate Exhibiting High Proton Conductivity and Thermal Stability over a Wide Intermediate Temperature Range.

For the practical application of fuel cells in vehicles, it is a challenge to develop a proton solid electrolyte that coexhibits thermal stability and high proton conductivity at wide intermediate temperatures. Here, we report on the tunnel structured phosphate KNi1-xH2x(PO3)3·yH2O, which exhibits high proton conductivity at room temperature up to 500 °C, with the conductivity value reaching 1.7 × 10-2 S cm-1 at 275 °C for x = 0.18. This material, composed of the smallest cations that form the tunnel framework with face-shared (KO6) and (NiO6) chains and PO4 tetrahedral chains, retained the rigid framework up to 600 °C. Two oxygen sites of water molecules located adjacent to each other along the PO4 tetrahedral chains in the tunnel provided the proton conduction pathway. The sample maintained a conductivity of 5.0 × 10-3 S cm-1 for 10 h at 150 °C while changing the measurement atmosphere to a N2 gas flow, a 4% H2-96% Ar gas flow, and an O2 gas flow. The conductivity value at x = 0.18 obtained from the DC measurement was in the order of 10-6 S cm-1, close to the instrument's measurement limit. These results demonstrate that tunnel phosphate has potential as a proton solid electrolyte for next-generation fuel cells.

Mechanistic study of Al2O3 coating effects on lithium deposition and dissolution reaction.

Lithium metal anodes show great promise for use in next-generation secondary batteries, but they suffer from lithium dendrite growth, as well as other issues, which cause safety problems and result in a loss of capacity with time. The use of artificial inorganic solid electrolyte interphase (SEI) layers, such as those comprising Al2O3, is a promising way to mitigate these disadvantages, but the mechanism behind these observed improvements remains poorly understood. Therefore, in this study, using pulsed laser deposition (PLD), the surface of a Cu electrode was coated with a physicochemically stable and mechanically strong Al2O3 thin film, and the effects of the film coating on the lithium deposition and dissolution behaviour were investigated. When the morphology of the deposits was evaluated by scanning electron microscopy, small lithium nuclei (approximately 0.2 µm in diameter) were observed to be deposited uniformly over the entire surface of the uncoated Cu electrode in the initial electrodeposition, and these grew into needle-like crystals from the nuclei. After 60 min of electrodeposition, the needle-like precipitates had aggregated and grown into three-dimensional structures with dendritic form. In contrast, on the surface of the Cu electrode modified with Al2O3 by PLD for 1 h, lithium clusters of about 50 µm in diameter were found to be aggregated and precipitated in the initial stages of electrodeposition. Notably, this is the first report of lithium deposition on Al2O3 thin films. With further cycling, the precipitates grew into two-dimensional flat plates. Analysis of the SEI film formed during the first deposition reaction revealed that the Al2O3 coating reduced the thickness of the SEI compared to that of the uncoated electrode. Therefore, the Al2O3 coating suppressed the decomposition of the electrolyte with the Cu electrode. The use of Al2O3 coatings results in (i) the growth of two-dimensional lithium clusters with an island shape on the Al2O3 thin film, and these could ensure a uniform electron conduction path to the electrode; in addition, (ii) the inhibited electrolyte decomposition caused by the low-surface-area lithium clusters and the low electronic conductivity of the Al2O3 thin film. These improve the coulombic efficiency and cycling behaviour.

A Review on Li+ /H+ Exchange in Garnet Solid Electrolytes: From Instability against Humidity to Sustainable Processing in Water.

Garnet-based Li-ion conductors are one of the most promising oxide-ceramic solid electrolytes for next-generation Li batteries. However, they undergo a Li+ /H+ exchange (LHX) reaction with most protic solvents used in component manufacturing routes and even with moisture in ambient air. These protonated garnets show a lower Li-ionic conductivity, and even if only the surface is protonated, this degraded layer hinders the Li-ion exchange with, for example, a metallic Li anode. Furthermore, the resulting unstable surface properties during the processing in air lead to challenges with respect to reproducibility of the final component performance, limiting their commercial applicability. However, in recent years, the knowledge about the underlying chemical mechanisms has led to the development of mitigation strategies and enabled a push of this promising material class towards sustainable and scalable fabrication routes. This Minireview covers the following four aspects, which are relevant for a comprehensive understanding of these developments: (1) reports of LHX phenomenon in garnets exposed to air and solvents; (2) recent understandings of the fundamentals and properties of LHX; (3) strategies to prevent LHX and to recover garnets; and (4) sustainable application of LHX for material processing and energy-related devices.

Bifunctional 1-Boc-3-Iodoazetidine Enhancing Lithium Anode Stability and Rechargeability of Lithium-Oxygen Batteries.

Lithium anode protection is an effective strategy to prohibit the continuous loss of redox mediators (RMs) resulting from the unfavorable "shuttle effect" in lithium-oxygen batteries. In this work, an in situ Li anode protection method is designed by utilizing an organic compound, 1-Boc-3-iodoazetidine (BIA), as both a RM and an additive, to form a lithium anode protective layer. The reaction between Li metal and BIA can form lithium iodide (LiI) and lithium-based organometallic. LiI can effectively reduce the charging overpotential. Meanwhile, the in situ-formed anode protection layer (lithium-based organometallic) can not only effectively prevent RMs from being reduced by the lithium metal, but also inhibit the growth of lithium dendrites. As a result, the lithium-oxygen battery with BIA shows a long cycle life of 260 cycles with a notably reduced charging potential. In particular, the battery with BIA achieves an excellent lifespan of 160 cycles at a large current density of 2000 mA g-1.

Arrangement of water molecules and high proton conductivity of tunnel structure phosphates, KMg1-x H2x (PO3)3·yH2O.

A fast proton conductor was investigated in a mixed-valence system of phosphates with a combination of large cations (K+) and small cations (Mg2+), which resulted in a new phase with a tunnel structure suitable for proton conduction. KMg1-x H2x (PO3)3·yH2O was synthesized by a coprecipitation method. A solid solution formed in the range of x = 0-0.18 in KMg1-x H2x (PO3)3·yH2O. The structure of the new proton conductor was determined using neutron and X-ray diffraction measurements. KMg1-x H2x (PO3)3·yH2O has a tunnel framework composed of face-shared (KO6) and (MgO6) chains, and PO4 tetrahedral chains along the c-direction by corner-sharing. Two oxygen sites of water molecules were detected in the one-dimensional tunnel, one of which exists as a coordination water of K+ sites. Multi-step dehydration was observed at 30 °C and 150 °C from thermogravimetric/differential thermal analysis measurements, which reflects the different coordination environments of the water of crystallization. Water molecules are connected to PO4 tetrahedra by hydrogen bonds and form a chain along the c-axis in the tunnel, which would provide an environment for fast proton conduction associated with water molecules. The KMg1-x H2x (PO3)3·yH2O sample with x = 0.18 exhibited high proton conductivity of 4.5 × 10-3 S cm-1 at 150 °C and 7.0 × 10-3 S cm-1 at 200 °C in a dry Ar gas flow and maintained the total conductivity above 10-3 S cm-1 for 60 h at 150 °C under N2 gas atmosphere.

Lithium metal deposition/dissolution under uniaxial pressure with high-rigidity layered polyethylene separator.

The effects of mechanical uniaxial pressure and deflection of the separator on the electrochemical deposition of lithium metal were investigated. Instead of dendritic lithium growth without pressure, a much more dense and compact deposition can be achieved when pressure is applied to the cells during the lithium deposition process. This morphology is due to the formation of granular lithium followed by the generation of new lithium nuclei on the cathode surface. The improved lithium plating/stripping behavior in the cells under mechanical pressure yielded a 10% higher coulombic efficiency than cells without pressure. However, the cycle life is shortened with pressures higher than 1.39 MPa; therefore, there is an upper limit for improvement of the electrochemical characteristics near 1.39 MPa. The morphology of electrodeposited lithium becomes flatter with a large amount of electrodeposition under pressure when the number of polyethylene separators is increased to five due to the increase in the stiffness of the layered separators. Furthermore, high coulombic efficiency cycling by pressurization was increased to twice that for one separator sheet. Application of the optimal strength pressure and use of more inflexible separators are thus effective methods to control the microscopic morphology of electrodeposited lithium and improve the cycle performance of the lithium metal anode.

A hydrated strontium cobalt oxyhydroxide Ruddlesden-Popper phase as an oxygen electrocatalyst for aqueous lithium-oxygen rechargeable batteries.

This study investigates oxygen electrocatalytic activities of perovskite-related compounds using a rotating disk electrode technique in an aqueous solution containing lithium chloride and lithium hydroxide. A hydrated oxyhydroxide Ruddelesden-Popper phase, Sr3Co2O5(OH)2·2H2O, exhibits excellent performance especially in the oxygen evolution reaction.

Destabilized Passivation Layer on Magnesium-Based Intermetallics as Potential Anode Active Materials for Magnesium Ion Batteries.

Passivation of magnesium metal anode is one of the critical challenges for the development of magnesium batteries. Here we investigated the passivation process of an intermetallic anode: Mg3Bi2 synthesized by solid-state and thin film process. The Mg3Bi2 composite electrode shows excellent reversibility in magnesium bis(trifluoromethansulfonylamide) dissolved in acetonitrile, while Mg3Sb2, which has same crystal structure and similar chemical properties, is electrochemically inactive. We also fabricated the Mg3Bi2 thin film electrodes, which show reversibility with low overpotential not only in the acetonitrile solution but also glyme-based solutions. Surface layer corresponding to the decomposed TFSA anion is slightly suppressed in the case of the Mg3Bi2 thin film electrode, compared with Mg metal. Comparative study of hydrolysis process of the Mg3Bi2 and the Mg3Sb2 suggests that the both intermetallic anodes are not completely passivated. The bond valence sum mapping of the Mg3Bi2 indicates that the fast Mg2+ diffusion pathway between 2d tetrahedral sites is formed. The electrochemical properties of the Mg3Bi2 anode is mainly due to the less passivation surface with the fast Mg2+ diffusion pathways.

High-Energy-Density Rechargeable Lithium-Nickel Chloride Aqueous Solution Batteries.

High-energy-density rechargeable batteries with performance beyond that of lithium-ion batteries are required for next-generation electric vehicles. We propose a novel rechargeable battery with a lithium anode and a NiCl2 aqueous cathode that is separated Li1.4Al0.4Ge0.2Ti1.4(PO4)3 as a water-stable lithium-ion-conducting solid electrolyte. The cell was discharged up to 93% of the theoretical cathode capacity at 0.5 mA cm-2 and 25 °C. The calculated energy density, based on the weights of NiCl2 and Li, and the average discharge voltage of 2.4 V at 0.5 mA cm-2, was 852 Wh kg-1, which is more than twice as high as that of conventional lithium-ion batteries. The cell was successfully cycled for 50 cycles without any degradation of the charge and discharge voltages at 0.5 mA cm-2 and 25 °C for 5 h charge and 5 h discharge, where the utilization of NiCl2 was 80%.

A reversible dendrite-free high-areal-capacity lithium metal electrode.

Reversible dendrite-free low-areal-capacity lithium metal electrodes have recently been revived, because of their pivotal role in developing beyond lithium ion batteries. However, there have been no reports of reversible dendrite-free high-areal-capacity lithium metal electrodes. Here we report on a strategy to realize unprecedented stable cycling of lithium electrodeposition/stripping with a highly desirable areal-capacity (12 mAh cm-2) and exceptional Coulombic efficiency (>99.98%) at high current densities (>5 mA cm-2) and ambient temperature using a diluted solvate ionic liquid. The essence of this strategy, that can drastically improve lithium electrodeposition kinetics by cyclic voltammetry premodulation, lies in the tailoring of the top solid-electrolyte interphase layer in a diluted solvate ionic liquid to facilitate a two-dimensional growth mode. We anticipate that this discovery could pave the way for developing reversible dendrite-free metal anodes for sustainable battery chemistries.

Lithium ion diffusion measurements on a garnet-type solid conductor Li6.6La3Zr1.6Ta0.4O12 by using a pulsed-gradient spin-echo NMR method.

The garnet-type solid conductor Li7-xLa3Zr2-xTaxO12 is known to have high ionic conductivity. We synthesized a series of compositions of this conductor and found that cubic Li6.6La3Zr1.6Ta0.4O12 (LLZO-Ta) has a high ionic conductivity of 3.7×10(-4)Scm(-1) at room temperature. The (7)Li NMR spectrum of LLZO-Ta was composed of narrow and broad components, and the linewidth of the narrow component varied from 0.69kHz (300K) to 0.32kHz (400K). We carried out lithium ion diffusion measurements using pulsed-field spin-echo (PGSE) NMR spectroscopy and found that echo signals were observed at T≥313K with reasonable sensitivity. The lithium diffusion behavior was measured by varying the observation time and pulsed-field gradient (PFG) strength between 313 and 384K. We found that lithium diffusion depended significantly on the observation time and strength of the PFG, which is quite different from lithium ion diffusion in liquids. It was shown that lithium ion migration in the solid conductor was distributed widely in both time and space.

A novel aqueous lithium-oxygen cell based on the oxygen-peroxide redox couple.

The electrochemical process of an aqueous Li-O2 cell is investigated. Li2O2 is detected as a discharge product of an aqueous Li-O2 cell using a catalyst-free carbon-based electrode. The electrolyte solution saturated with lithium hydroxide prevents hydrolysis of the Li2O2. Since the electron transfer process is based on the oxygen-peroxide redox couple, the galvanostatic charging-discharging profile shows stable cycling with an extremely low charging overpotential of <0.1 V at 1.0 mA cm(-2).

Combined usage of intercostal nerve block and tumescent anaesthesia: an effective anaesthesia technique for breast augmentation.

Patients are occasionally unhappy with the size, shape, and positioning of breast implants. An option to improve their satisfaction with breast augmentation includes directly involving them in the process with awake surgery done under nerve block and tumescence. This study describes the resultsof using such an awake anaesthesia technique in 35 patients. After the intercostal nerves dominating the Th3 to Th6 regions were anaesthetized using 0.5% bupivacaine, a tumescent solution consisting of lidocaine, epinephrine, and saline was injected around the mammary gland, and breast augmentation was conducted using silicon implants. The majority of patients (31/35) reported no pain during the procedure and all patients were able to choose and confirm their final implant size and positioning. In all cases, blood loss was less than 10 ml. No patient experienced pneumothorax or toxicity of local anaesthetics. Combined usage of the intercostal nerve block and tumescent anaesthesia effectively reduces pain during breast augmentation. Keeping patient conscious enables meeting their requests during operation, contributing to increased satisfaction. For these advantages, combined usage of the intercostal nerve block and tumescent anaesthesia is recommended as a useful anaesthetic technique for breast augmentation.

Interface Properties between Lithium Metal and a Composite Polymer Electrolyte of PEO18Li(CF3SO2)2N-Tetraethylene Glycol Dimethyl Ether.

The electrochemical properties of a composite solid polymer electrolyte, consisting of poly(ethylene oxide) (PEO)-lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) and tetraethylene glycol dimethyl ether (TEGDME) was examined as a protective layer between lithium metal and a water-stable lithium ion-conducting glass ceramic of Li1+x+y(Ti,Ge)2-xAlxP3-ySiyO12 (LTAP). The lithium ion conductivity and salt diffusion coefficient of PEO18LiTFSI were dramatically enhanced by the addition of TEGDME. The water-stable lithium electrode with PEO18LiTFSI-2TEGDME, as the protective layer, exhibited a low and stable electrode resistance of 85 Ω·cm2 at 60 °C, after 28 days, and low overpotentials of 0.3 V for lithium plating and 0.4 V for lithium stripping at 4.0 mA·cm-2 and 60 °C. A Li/PEO18LiTFSI-2TEGDME/LTAP/saturated LiCl aqueous solution/Pt, air cell showed excellent cyclability up to 100 cycles at 2.0 mAh·cm-2.

Morphological analysis of the upper eyelid tarsus in Asians.

PURPOSE: The present study aims to evaluate morphologic variations of the upper tarsus in Asians. METHODS: Measurements of superior-inferior and medial-lateral lengths were performed on 54 embalmed cadavers. The superior-inferior length of the tarsus was measured at the central and lateral parts. On the basis of the measured values, shapes of the tarsi were evaluated and categorized. RESULTS: The tarsi were classified into 3 morphologic categories-the sickle, triangular, and trapezoid types. The upper margins of the sickle, triangular, and trapezoid type tarsi present round, triangular, and flat lines, respectively. Among the 54 examined specimens, 29 (55.6%), 16 (29.6%), and 9 (16.7%) belonged to the sickle, triangular, and trapezoid groups, respectively. CONCLUSIONS: The upper eyelid tarsi present morphologic variations with the Asian population. In performing surgical correction of blepharoptosis or surgical production of double-folds, this individual variation should be taken into consideration.

A novel high energy density rechargeable lithium/air battery.

A novel rechargeable lithium/air battery was fabricated, which consisted of a water-stable multilayer Li-metal anode, acetic acid-water electrolyte, and a fuel-cell analogous air-diffusion cathode and possessed a high energy density of 779 W h kg(-1), twice that of the conventional graphite/LiCoO(2) cell.