Lithium Ion Conductive Solid Electrolyte Research Articles

Aqueous lithium-ion battery of Li4Ti5O12/LiMn2O4 using a lithium-ion conductive solid electrolytes separator

This study investigated the electrochemical properties and performance of an aqueous lithium-ion battery of Li4Ti5O12/LiMn2O4 (LTO/LMO) using a lithium-ion conductive solid electrolyte (SE) composed of NASICON-type Li–Al–Ti–P–O glass ceramic as a separator and a high concentration LiCl-based aqueous electrolyte in order to enhance charge-discharge and cycle life performance. The evolution of H2 gas at the LTO anode during charging was found to be kinetically suppressed by using the SE separator and Zn coating on the LTO anode. As a result, the amount of H2 gas was less than 2.6% that of the porous separator. The SE separator enabled the aqueous electrolyte on the LMO cathode and LTO anode sides to maintain an acidic and a basic solution, respectively, which widened the electrochemical window. Aqueous LTO/LMO batteries using the SE separator exhibited an average voltage of 2.4 V and a high anode capacity of 170 mAh g−1 during charge-discharge cycling test at a rate of 1 C between 2.1 and 2.6 V. It was demonstrated that the battery using a Li2SO4-based aqueous electrolyte in the LMO cathode had good cycle performance and maintained a high coulombic efficiency of 99% after 100cycles.

X-Ray CT 3D Structure Measurement and Performance Evaluation of All Solid-State Lithium-Ion Battery Anode

X-ray CT and battery performance measurements of LiIn-SE-Anode (SE + Graphite) half cell are conducted to elucidate the relationship between electrode performance and 3D internal structure. LGPS that is one of the highest lithium-ion conductive solid electrolyte are used in this study. Fig.1 illustrates an experimental setup in this study. The anode half sell is installed in high pressure X-ray CT measurement jig. The X-ray CT are conducted with In-situ high pressure condition (100MPa) to measure the volume ratio of SE and graphite and tortuosity of SE network those can be changed with decompression. The battery performance are measured by a potentiogalvanostat with CC charging and discharging and an electrochemical impedance spectroscopy (EIS) are conducted to measure the overpotential in the cell. The performance measurement and EIS are conducted for the same X-ray CT measured anode half sell, therefore, the battery performance can be directory discussed with 3D structure.Figure 2 illustrates the ratio of actual capacity to theoretical capacity as a function of electrode thickness and volume ratio of active material (graphite). The highest capacity ratio is obtained for thin electrode (30um) and low active material volume ratio (50%) and is decreased by increase in the electrode thickness and the active material ratio.Table.1 shows the electrode structure parameters measured by the X-ray CT and high-frequency and low-frequency resistance measured by the EIS. The high frequency resistance of the anode half-cell is originated from overpotential of lithium ion transportation in SE network and activation overpotential on graphite and that of low-frequency resistance is diffusion of Li-ion in graphite particle. From table.1, in the case with graphite ratio of 50%, both high frequency and low frequency resistance are increased with increase in the electrode thickness. It is considered that the low frequency resistance is increased with the increase of SE network resistance by increase in the length of the lithium-ion transportation length. The increase of the electrode thickness decreases the lithium ion flux for each graphite particle and the diffusion in the graphite is suppressed and the low frequency resistance is increased. The increase of graphite volume ratio dramatically decreases the ratio of actual capacity to theoretical capacity as shown in fig.2. The tortuosity of SE network that has a positive correlation to the resistance of the SE network is increased with the increase in the graphite volume ratio. It can be a reason of the increase of the high frequency resistance. Moreover, the specific surface area between SE and graphite is decreased with the increase in graphite volume ratio. It means the graphite is condensed in the electrode and the contact surface of the graphite to SE is decreased and the diffusion length of lithium ion in the graphite is increased. This suppression of the lithium ion diffusion in graphite particle is corresponds to the increase of the low frequency resistance as shown in table 3.From the mentioned above, it can be said that the battery performance improvement with high volume ratio of graphite for would be achieved with the improvement of the dispersiveness of graphite and ion conductivity of the solid electrolyte. Figure 1

Single Lithium-Ion Conducting Solid Polymer Electrolyte with Superior Electrochemical Stability and Interfacial Compatibility for Solid-State Lithium Metal Batteries.

Lithium metal batteries are being explored in meeting ever-increasing energy density needs. Because of serious dendritic lithium issues in liquid-state electrolytes, it is generally thought that solid-state electrolytes are potential alternatives for lithium metal batteries. Herein, we design a new single lithium-ion conducting lithium poly[(cyano)(4-styrenesulfonyl)imide] (LiPCSI) to replace the conventional dual-ion conducting salt for use in solid polymer electrolytes (SPEs) that successfully suppress the growth of lithium dendrites. Owing to highly delocalized anion moiety and oxidation-resistant cyano group, the tailored PEO8-LiPCSI SPE exhibits extremely high Li+ transference number (0.84) as well as oxidation potential (5.53 V vs Li+/Li). The symmetric Li/PEO8-LiPCSI/Li cell runs for 1000 h at 60 °C without a short circuit. The rechargeable solid-state Li/PEO8-LiPCSI/LiFePO4 cell discharges a capacity of 141 mAh g-1 with retention over 85% during 80 cycles. These merits enable the proposed PEO8-LiPCSI SPE to be very promising for solid-state lithium metal battery applications.

Prototype Aqueous Lithium-Ion Battery with a Lithium-Ion Conductive Solid Electrolyte Separator

Lithium-ion batteries (LIBs) with a non-aqueous electrolyte are capable of high energy density, high power output, and long cycle performance. These batteries are regarded as the most promising sources of power for electric vehicles (EVs), hybrid electric vehicles (HEVs), and grid storage. However, current LIBs pose a safety risk due to their flammable organic electrolytes. In contrast, lithium-ion batteries with aqueous electrolytes are safer and cost less than current LIBs, but the electrochemical stability window of aqueous electrolytes is narrower than that of the organic electrolytes used in LIBs. The stable operating voltage window of an aqueous electrolyte is approximately 1.23 V thermodynamically, beyond which the electrolysis of H2O occurs along with the evolution of H2 or O2 gas. As illustrated by a Pourbaix diagram, the overall electrochemical stability window of aqueous electrolytes is constant and independent of the pH of the electrolytes. In this study, we report the widening of the overall electrochemical stability window with two electrolytes having different pH values. We utilized a lithium-ion conductive solid electrolyte to separate the electrolytes into the cathode and anode sides of an aqueous lithium-ion battery in order to suppress the evolution of oxygen and hydrogen. In particular, we fabricated an aqueous lithium-ion cell with a lithium-ion conductive solid electrolyte as the separator between two inorganic lithium salt layers. A spinel lithium manganese oxide (LMO) was used as the cathode active material while a spinel lithium titanate oxide (LTO) with a Li+ insertion potential of 1.55 V vs. Li was used as the anode active material, leading to less hydrogen evolution compared with the graphite anodes used in current LIBs. A lithium-ion ceramic plate (LICGC™, Ohara Inc.) with a thickness 150 µm and conductivity 10-4 S/cm at 25°C was used as the separator. The plate was able to separate the different electrolytes into the cathode and anode sides. Then, 2 mol/L Li2SO4 and 12 mol/L LiCl, both of which have higher conductivity than the organic electrolytes of current LIBs, were used as the cathode and anode electrolytes, respectively. The cell was constructed with an LMO cathode electrode (10 mm in diameter, 0.1 mm thick), an LTO anode electrode (approximately the same dimensions as the cathode), the solid electrolyte separator (2.5 ´ 2.5 cm, 150 µm thick), and an aqueous solution with 2 mol/L Li2SO4 and 12 mol/L LiCl as the cathode and anode electrolyte, respectively. The charge/discharge current density was 0.282 mA/cm2 at the 1C rate. Figure 1 shows the charge and discharge curves of the LMO/LTO cell at the 20th cycle (25°C). The aqueous test cell exhibited an average discharge voltage of over 2.4 V and a coulombic efficiency of over 94%. Figure 2 shows the cycling stability and coulombic efficiencies of aqueous LMO/LTO cells at the 1C rate. To prevent drying of the electrolyte in a long-term experiment, 12 mol/L LiCl was used as electrolytes for both the cathode and anode. The retention of discharge capacity and coulombic efficiency was approximately 100% after 1000 cycles. The coulombic efficiency of the initial cycle, in which the pH of the 12 mol/L LiCl electrolyte was neutral (measured with pH test paper), was relatively low. During the 20th cycle, which had relatively low coulombic efficiency, the anode electrolyte changed from acidic to basic and hydrogen evolution with electrolysis of water was suppressed. After the 20th cycle, the electrolyte pH at the anode electrode surface was close to 14, whereas the entire electrolyte pH was close to neutral. The pH of the local electrolyte, situated between the anode electrode surface and the solid electrolyte separator, changed from acidic to basic, resulting in the suppression of oxygen and hydrogen gas generation without changing the pH of the cathode electrolyte. The initial coulombic efficiency was dependent on the anode electrolyte pH due to the lower coulombic efficiency of the anode compared with the cathode. Additional electrochemical tests will be reported in the future. Figure 1

Aqueous Lithium Rechargeable Battery with a Tin(II) Chloride Aqueous Cathode and a Water-Stable Lithium-Ion Conducting Solid Electrolyte

Electrical vehicles (EVs) have enjoyed extensive focus this decade as next-generation vehicles. However, high specific energy, high power density and low-cost batteries are essential for EVs to replace vehicles with internal combustion engines. Here, we propose a novel high specific energy and power density rechargeable aqueous lithium battery with an aqueous SnCl2 cathode and a lithium metal anode, where the lithium anode and the aqueous cathode are separated by a water-stable high lithium-ion conductivity solid electrolyte of Li1.4Al0.4Ge0.2Ti1.4(PO4)3. The theoretical specific energy density of this battery was 681 Wh kg−1, which is around 1.8 times higher than that of conventional lithium-ion batteries. The cell was successfully cycled at 1.5 mA cm−2 and 25°C for a specific areal capacity of 15 mAh cm−2.

Sol Gel vs Solid State Synthesis of the Fast Lithium-Ion Conducting Solid State Electrolyte Li7La3Zr2O12 Substituted with Iron

Two calcined products of Li6.4Fe0.2La3Zr2O12 can be synthesized via the solid state method and the sol gel method. Inhomogeneities of the iron distribution in the powder for the solid state method lead to a combination of cubic and tetragonal structure. By using the sol gel method the homogeneity can significantly been increased resulting in the desired pure phase cubic structured powders in I3d. By in situ dilatometer measurements the densification process can be comprehended for the first time for garnet type materials. The density can be significantly increased by the usage of the sol gel synthesis compared to the solid state synthesis with short sintering times of 2 h delivering pure phase pellets for both synthesis methods. Electrical impedance measurements revealed clearly divided semicircles for the bulk and the grain boundary contribution for the solid state synthesis, while the sol gel synthesis showed only one semicircle from the bulk contribution due to a large crystallite size. The total ionic conductivity for the pellet synthesized via the sol gel method is 1.82 mS/cm at 25°C which is the fastest found so far for garnet type or garnet related materials.

Electrochemical performance of bulk-type all-solid-state batteries using small-sized Li7P3S11 solid electrolyte prepared by liquid phase as the ionic conductor in the composite cathode

A high lithium-ion conductive solid electrolyte with Li7P3S11 phase and small particle size was prepared by a liquid phase process, and the solid electrolyte was used as the ionic conductor in the composite cathode for bulk-type all-solid-state batteries. The electrochemical performance of the all-solid-state cell using Li7P3S11 solid electrolyte prepared by liquid phase was studied and compared to that using Li7P3S11 solid electrolyte prepared by ball milling.Solid electrolytes prepared by the liquid phase and ball milling processes consisted mainly of the Li7P3S11 crystal phase and the local structure was composed by PS43−, P2S74− and P2S64− units. Both solid electrolytes exhibited a comparable high ionic conductivity over 10−3 Scm−1. A particle size around 500 nm was obtained by the liquid phase process, while a particle size larger than 10 μm was obtained by the ball milling process. The composite cathode using the solid electrolyte obtained by the liquid phase process displayed a better distribution of the solid electrolyte and the active material, verified by scanning electron microscopy and energy-dispersive X-ray spectroscopy.The all-solid-state cell using LiNi1/3Co1/3Mn1/3O2 and the solid electrolyte prepared by the liquid phase exhibited a better electrochemical performance than that using the solid electrolyte prepared by ball milling. The all-solid-state cells exhibited a first discharge capacity of 154 mAh g−1 and 46 mAh g−1, respectively. Furthermore, the structure of the solid electrolyte prepared by the liquid phase process, after charge-discharge measurements with charge-end voltages of 4.6 V vs Li, was investigated by using ex-situ Raman spectroscopy. Significant structural changes were not observed, indicating that Li7P3S11 is stable against charge-discharge processes.

Preparation of lithium ion conductive Li6PS5Cl solid electrolyte from solution for the fabrication of composite cathode of all-solid-state lithium battery

An argyrodite type Li6PS5Cl was prepared by the solution process using a mixture of solvents with a fast evaporation rate. The crystal phase and ionic conductivity of the Li6PS5Cl solid electrolyte were examined by X-ray diffraction and electrochemical impedance spectroscopy, respectively. Li6PS5Cl derived from solution process shows an argyrodite structure with an ionic conductivity of 6 × 10-5 S cm−1 at room temperature. Composite cathode was directly prepared by dispersing LiNi1/3Mn1/3Co1/3O2 (84 wt%) and a conductive additive (2 wt%) into a Li6PS5Cl precursor solution (14 wt%), with subsequent heating at 150 °C. Morphology of the composite cathode was evaluated by scanning electron microscopy and energy-dispersive X-ray spectroscopy. The formation of Li6PS5Cl-layer on the active material particles was observed. A bulk-type all-solid-state cell was fabricated with composite cathode derived from the solution process, achieving an initial discharge capacity of 160 mAh g−1 and capacity retention of ~80% after 20 cycles with a capacity efficiency of 100%.

Synthesis and Properties of a Photopatternable Lithium-Ion Conducting Solid Electrolyte.

One of the important considerations for the development of on-chip batteries is the need to photopattern the solid electrolyte directly on electrodes. Herein, the photopatterning of a lithium-ion conducting solid electrolyte is demonstrated by modifying a well-known negative photoresist, SU-8, with LiClO4 . The resulting material exhibits a room temperature ionic conductivity of 52 µS cm-1 with a wide electrochemical window (>5 V). Half-cell galvanostatic testing of 3 µm thin films spin-coated on amorphous silicon validates its use for on-chip energy-storage applications. The modified SU-8 possesses excellent mechanical integrity, is thermally stable up to 250 °C, and can be photopatterned with micrometer-scale resolution. These results present a promising direction for the integration of electrochemical energy storage in microelectronics.

Preparation and Electrochemical Evaluation of LiCoO2 Film Prepared with Cold Spraying for Development of Lithium-Ion Battery

Compared with liquid organic electrolytes, lithium ion conductive solid electrolytes offer improved safety, reliability and leakage-free properties, as well as the advantageous wider electrochemical voltage ranges and the possibility for structural batteries. For this reason, all-solid-state Lithium-Ion Batteries (LIBs) have attracted great interest in recent years. In this regard, electrode deposition technology is expected to play an important role in the development of all-solid-state LIBs. We propose a new method for preparing a cathode film using a cold spray technique. In this study, LiCoO2 films were deposited using a cold spray technique. From SEM observations, the average thickness of the LiCoO2 films was estimated to be approximately 20 micrometers. Cyclic voltammetry showed the LiCoO2 film prepared with cold spraying to be electrochemically active. While the electric capacity of the LiCoO2 cathode film decreased monotonically until 70th cycle, it tended to give a relatively constant value after the 70th cycle. The cold spraying method may provide a useful route for the development of all-solid-state LIBs.

Local Structure and Composition Variation at Surface of Lithium-Ion Conducting Solid Electrolyte

Recently, lithium ion conducting solid electrolytes attract many interests because of their potential application to all-solid-state batteries (ASSBs), which are supposed to be one of candidates of next-generation energy storage devices with high safety and reliability [1-3]. With great efforts of development of solid electrolytes, several materials with high lithium ionic conductivity have been reported, which facilitated hope of realization of ASSBs [2,4-8]. Now, researchers face several problems on application of solid electrolytes to ASSBs. Most of those problems are related to interfaces of between solid electrolytes and active materials, for example, contact areas, interdiffusion of elements on assembly and/or electrochemical processes of ASSBs. To solve these issues, much attention has been paid to design and fabrication techniques. In addition to the problems on the fabrication, several reports point out intrinsic phenomena related change in ion concentration at interfaces of solid electrolytes [1, 9, 10]. We have so far studied the local structure at the interfacial region by fabricating nano-composites of active materials and solid electrolytes, and confirmed that the interfacial region with distorted lattice ranges for at least 20-50 nm in thickness [9, 10]. Although more researches with variety of experimental analysis are required for further comprehension of the interfacial phenomena, difficulty in the analysis of solid/solid interface limits experimental tools. It is known that surface of solid electrolytes is also related to interfacial resistance. Kliewer proposed cation depletion at surface of ionic crystals when free energy of defect formation is lower for cation than for anion [11]. In addition, we observed that ball-milling of a poor ionic conductor (Li2SiO3, LSO) resulted in increase in ionic conductivity without change in activation energy [9, 12]. In this study, three different surface-sensitive techniques, grazing incidence X-ray diffraction (GIXD), attenuated total reflectance Fourier transform infrared (ATR-FTIR), and X-ray photoelectron spectroscopy (XPS), were employed to analyze the local structure and composition around the surface region of a lithium ion conducting solid electrolyte sheet (NASICON-type in the system of Li-Al-Ti-Ge-Si-P-O, Ohara Inc. abbreviated as LICGC). It was revealed that the local structure and composition changed depending on depth from the top surface of the sheet. At the very surface, there was a layer with expanded lattice (Figure 1) and high Li composition (Figure 2). And with increasing the depth from the surface, lattice shrank sharply, and then expanded again gradually. The change in the lattice seemed to be accompanied by Li and Al composition. It was supposed that the change in the Li composition and structure is induced by combination of chemical reaction, segregation, and defects distribution [13].

Lithium - Redox Battery Using a Solvate Ionic Liquid

Redox flow batteries have been expected as the large scale storage battery. Redox flow batteries utilize the oxidation and reduction of two soluble redox couples for charging and discharging without the solid phase reaction. Therefore, the cycle lives of the redox flow batteries are expected to be much longer than those of rechargeable lithium batteries using insertion-type active materials. Currently, vanadium redox flow batteries have been put into practical use to stabilize the supply of renewable energy. Vanadium redox flow batteries have low energy density compared to other batteries. Since aqueous solution is used for the electrolyte, the electrochemical window of the water limits the cell voltage. Although there has been various studies using an organic electrolyte in order to enlarge the cell voltage, the flammability and volatility of the organic solvents can be disadvantageous from the point of view of safety. 1) Recently, aprotic ionic liquids have attracted attention as nonaqueous electrolytes. Especially, aprotic ionic liquids containing bis(trifluoromethylsulfonyl)amide (TFSA-) have been studied extensively in the electrochemical field because they show favorable features such as incombustibility, involatility and wide electrochemical potential window. We have already reported the redox reactions of various metal complexes in the ionic liquids and their applicability to redox flow batteries. 2) However, there are a few reports regarding the redox battery using the ionic liquids probably due to lack of the suitable ion exchange membrane that can move the career ion in the ionic liquids. In the present study, a new redox battery, namely “lithium-redox battery”, was proposed using a redox reaction of an iron complex for a cathode reaction, dissolution and deposition of lithium for an anode reaction, and LiTFSA – tetraglyme (G4) solvate ionic liquid for an electrolyte. In addition, lithium ion conductive solid electrolyte (LICGCTM) was used as the diaphragm, which prevents penetration of the redox species and enables transfer of lithium ions. Tris(2,2'-bipyridine)iron(II) complex ([Fe(bpy)2]2+) was found to be soluble and stable in the solvate ionic liquid. The redox reaction between [Fe(bpy)3]2+ and [Fe(bpy)3]3+ was confirmed to be reversible by cyclic voltammetry. The formal potential of [Fe(bpy)3]3+/2+ was 4.1 V vs. Li|Li(I). Reversible charge-discharge cycling of the lithium redox battery having an average cell voltage of 3.9 V was possible for 30 cycles with a coulombic efficiency of more than 95%. References 1) Y. Matsuda, K. Tanaka, M. Okada, Y. Takasu, and M. Morita, J. Appl. Electrochem., 18, 909 (1988). 2) Y. Katayama, M. Yoshihara, and T. Miura, J. Electrochem. Soc., 162, H501 (2015).

Ionic liquid impregnated lithium ion conductive solid electrolytes based on poly(acetyl ethylene glycol methacrylate–co-methyl acrylate)

Poly(ethylene glycol)methacrylate (PEGMA) was modified with acetyl chloride to afford acetyl-poly(ethylene glycol)methacrylate (AEGMA) containing PEG and carbonyl groups at the pendant position. AEGMA was further reacted with methyl acrylate (MAc) to synthesize poly(AEGMA–co-MAc) copolymer containing additional carbonyl groups. When lithium salts such as lithium perchlorate (LiCLO4) and lithium bis(trifluoromethanesulfony)imides (LITFSI) were introduced into the poly(AEGMA–co-MAc) membrane, the ionic conductivity increased with increasing lithium salt concentration up to 15wt%, followed by a decrease because when the lithium ion concentration was above its saturation level, the excess lithium salts aggregated together exerting a negative effect on ion transport. The maximum ionic conductivity of the copolymer system containing lithium salt was 1.1×10−4Scm−1 at 15wt% MAc and 15wt% of LiTFSI concentration. When room temperature ionic liquid (RTIL), PYR14-TFSI in addition to LiTFSI salt was introduced to the poly(AEGMA–co-MAc)–LiTFSI, the ionic conductivity increased monotonically with increasing salt/RTIL concentration. The maximum ionic conductivity of 1.2×10−3Scm−1 was obtained at 70wt% 0.5M LiTFSI/PYR14-TFSI concentration.

Recent Progress in Interfacial Nanoarchitectonics in Solid-State Batteries

Employing solid electrolytes in lithium-ion batteries is anticipated to be a solution to some issues originated from their organic electrolytes. However, solid-state lithium batteries had not been practicable, because ionic conductivities of lithium-ion conductive solid electrolytes had been very low. Therefore, many studies aiming at the development of solid-state lithium batteries have been focused on enhancement of ionic transport in solids. They have succeeded in enhancing the conductivity to be comparable to or even higher than that of liquids. At this stage, rate-determining step of the battery reactions is sometimes ionic transport at interface rather than bulk in the battery components. Since anomalous ionic conduction at the interface takes place in space-charge layers with ca. 10 nm in thickness, it will be controlled by “nanoarchitectonics”. This paper reviews some interfacial nanoarchitectures that control the interfacial ionic conduction to enhance the performance of solid-state lithium batteries.

Water-stable lithium ion conducting solid electrolyte of iron and aluminum doped NASICON-type LiTi2(PO4)3

High lithium ion conductivity solid electrolytes of Li1.4FexAl0.4 - xTi1.6(PO4)3 (x = 0−0.4) with the NASICON-type structure were synthesized by using a sol−gel precursor. The highest electrical conductivity was obtained for Li1.4Fe0.25Al0.15Ti1.6(PO4)3 sintered at 1040 °C for 7 h in air. The total, grain boundary, and bulk conductivities of the pellet were 1.01 × 10-3, 2.17 × 10-3 and 1.81 × 10-3 S cm-1 at 25 °C, respectively. The contribution of electron (or hole) conductivity to the total conductivity was negligibly small. Li1.4Fe0.25Al0.15Ti1.6(PO4)3 was unstable in water, but stable in saturated LiOH and LiCl aqueous solutions.

Interface behavior between garnet-type lithium-conducting solid electrolyte and lithium metal

Abstract Al 2 O 3 was doped (0.5, 1.0. and 2.0 wt.%) into the garnet-type lithium ion-conducting solid electrolyte with a nominal composition of Li 7 La 3 Zr 2 O 12 (LLZ) by solid state reaction at 1180 °C. The effect of the Al 2 O 3 content in LLZ on the interface behavior with lithium metal was investigated. The lowest interface resistance was observed for 0.5 wt.% Al 2 O 3 -doped LLZ, which had the highest relative density of 93.7%. The Li/Al 2 O 3 -doped LLZ/Li cell showed a short circuit after a limited polarization period. Short circuiting is considered to be due to lithium dendrite formation. The longest period until short circuit was 1000 s of polarization at 0.5 mA cm − 2 and room temperature for the 0.5 wt.% Al 2 O 3 doped LLZ.

Ceramic/polymer solid electrolyte based lithium water primary battery

A novel Li/H2O primary battery is reported. The battery consists of a thin film lithium metal anode evaporated on hybrid inorganic/organic lithium ion conductive solid electrolyte, H2O as the electroactive cathode material, and a Pt mesh current collector. The hybrid electrolyte consists of a two-phase ceramic, lithium aluminum titanium phosphate/aluminum phosphate (LATP/AlPO4), sealed with polyvinylidene fluoride. These cells display an open cell potential of 0.90V, a current output range between 0.78 and 0.50μA under constant 1MΩ load discharge, and specific energy of 2660Wh/kg. Battery life is shown to be proportional to the mass of the Li metal anode employed and has been demonstrated for up to 37.5h.

Multivariate Method-Assisted Ab Initio Study of Olivine-Type LiMXO4 (Main Group M2+–X5+ and M3+–X4+) Compositions as Potential Solid Electrolytes

Lithium-ion conductive solid oxide electrolytes are receiving increasing attention for the development of high-performance all-solid state rechargeable Li-ion batteries. In this study, we report an effective search method that uses a combination of ab initio calculations and multivariate analysis to find potential solid oxide electrolyte materials with low Li-ion hopping energies (EAs) among 66 olivine-type oxides with an ordered structure LiMXO4 (main group M2+–X5+, M3+–X4+). The ionic size of M, with its associated octahedral distortion leading to the appreciable local lattice distortion during the actual Li ion hop, made the most significant contribution to the variation in EA values. Promising M–X pairs (<0.30 eV) with experimental data in the Inorganic Crystal Structure Database include Mg–As (0.17 eV), Sc–Ge (0.22 eV), In–Ge (0.28 eV), and Mg–P (0.30 eV); Mg–As and Sc–Ge are reported here for the first time as battery materials. Promising theoretical compositions are also determined for Group 13 Al–...

Thermal behavior and lithium ion conductivity of L2O-Al2O3-TiO2-SiO2-P2O5 glass-ceramics

A lithium ion conductive solid electrolyte, L2O-Al2O3-TiO2-SiO2-P2O5 glass with NASICONtype structure have been synthesized and transformed into glass-ceramic through thermal-treatment at various temperatures from 700 to 1 000 °C for 12 h. The differential scanning calorimetry (DSC), X-ray diffraction (XRD), scanning electron microscopy (SEM) and complex impedance techniques were employed to characterize the samples. The experimental results indicated that the capability of glass forming in this system is superior to that of L2O-Al2O3-TiO2-P2O5. The glass has an amorphous structure and resultant glass-ceramic mainly consisting of LiTi2(PO4)3 phases. Impurity phases AlPO4, TiO2, TiP2O7 and unidentified phase were observed. With the enhanced heat-treatment temperature, grain grew gradually and lithium ion conductivity of glass-ceramics increased accordingly, the related impedance semicircles were depressed gradually and even disappeared, which could be analytically explained by the coordinate action of the ‘Constant phase element’ (CPE) model and the ‘Concept of Mismatch and Relaxation’ model (CMR). When the sample is devitrified at 1 000 °C, the maximum room temperature lithium ion conductivity comes up to 4.1×10−4 S/cm, which is suitable for the application as an electrolyte of all-solid-state lithium batteries.

Stabilizing lithium plating-stripping reaction between a lithium phosphorus oxynitride glass electrolyte and copper thin film by platinum insertion

Lithium (Li) plating-stripping reaction properties at the lithium phosphorus oxynitride glass electrolyte (LiPON)/copper thin film (Cu) interface is improved by the insertion of nano-thickness platinum (Pt) layer at the interface. The LiPON films are formed on mirror-polished lithium-ion conductive solid electrolyte sheets, and current collector thin films of Li, Cu–Pt multi layer, and Cu are formed on the LiPON films. The plating-stripping reactions at the LiPON/current collector films interface are carried out by galvanostatic and potential sweep measurements. Galvanostatic measurements reveal that Pt layer insertion reduces the overvoltage of the reaction and improves its coulomb efficiency. Also, cyclic voltammetry measurement suggests formation of Li–Pt alloys at higher voltages than 0 V (vs. Li/Li +) during the lithium plating process. Scanning electron microscopy observation clarifies that platinum insertion moderate non-uniform lithium plating reaction. Most probably, Li–Pt alloys increase the reaction sites, resulting in both the stabilization of current collector and the reduction of the overvoltage of the lithium plating-stripping reaction upon cycling. The results shown here will be useful in improving the anode reaction of the “Li-free” all-solid-state lithium batteries.