New bismuth ion conducting solid electrolyte

A new trivalent bismuth ion conducting solid electrolyte, (Bi_xGe_1 − x)_{4/(4 − x)}Ta(PO₄)₃, was successfully developed by selecting the NASICON-type GeTa(PO₄)₃ as the mother solid. Although bismuth has two kinds of valence states of + 3 and + 5, it was clear that pure trivalent Bi³⁺ ion conduction, without any electronic conduction by a valence change of bismuth in the oxygen pressure range over 10^− 3 Pa, was realized by selecting the crystal structure and constituents of the solid.     

Self supported nickel antimonides based electrodes for Li ion battery

Self-supported nickel antimonides/Ni architectured electrodes were prepared by solid state reaction from Ni thin film, Ni foam and Ni nanorods. This specific design is expected to optimize both NiSb_x/Ni-current collector and NiSb_x/electrolyte interfaces of the electrode in the Li ion battery. This new electrode preparation process is based on solid state reaction of antimony with the nickel architectured substrate. Preliminary electrochemical tests of the as-obtained self supported antimonide electrodes show improvement in the capacity retention of the NiSb_x active material.     

An intermediate temperature solid oxide fuel cell utilizing superior oxide ion conducting electrolyte, doubly doped LaGaO3 perovskite

LaGaO₃-based perovskite oxide doped with Sr and Mg exhibits high ionic conduction over a wide oxygen partial pressure. In this study, the stability of the LaGaO₃ based oxide was investigated. It became clear that LaGaO₃ based oxide is very stable for reduction and oxidation. SOFCs utilizing LaGaO₃-based perovskite type oxide for electrolyte were further studied for the decreased temperature solid oxide fuel cells. The power generation characteristics of cells were strongly affected by the electrode, both anode and cathode. It became clear that Ni and LnCoO₃ (Ln: rare earth) are suitable for anode and cathode, respectively. Rare earth cations in the Ln-site of Co-based perovskite cathode also have a great effect on the power generation characteristics. In particular, high power density could be attained in the temperature range from 973 to 1273 K by using doped SmCoO₃ for the cathode. The electrical conductivity of SmCoO₃ increases with increasing Sr amount doped for the Sm site and attained the maximum at Sm_0.5Sr_0.5CoO₃. The cathodic overpotential and the internal cell resistance exhibit almost opposite dependence on the amount of doped Sr. Consequently, the power density of the cell reaches a maximum when Sm_0.5Sr_0.5CoO₃ is used for cathode. On this cell, the maximum power density is as high as 0.58 W/cm² at 1073 K, although a 0.5 mm thick electrolyte is used. Therefore, this study reveals that the LaGaO₃ based oxide for electrolyte and the SmCoO₃ based oxide for cathode are promising for solid oxide fuel cells at intermediate temperature. Paper presented at the 97th Xiangshan Science Conference on New Solid State Fuel Cells, Xiangshan, Beijing, China, June, 14–17, 1998.     

Field enhanced Li ion conduction in nanoferroelectric modified polymer electrolyte systems

Nanocomposite polymer electrolyte (NCPE) films based on polyethylene oxide (PEO) complexed with lithium perchlorate (LiClO₄) and nanosized ferroelectric ceramic fillers such as BaTiO₃, SrTiO3 have been prepared using solution cast technique. The films showed very good mechanical stability when exposed to ambient atmospheres for prolonged periods. Lithium ion transport studies revealed that the conductivity is predominantly ionic. The effect of electric field on ionic conductivity of NCPE films was investigated. One order enhancement in conductivity due to the field was observed at 323 K. NCPE films exhibited conductivity of 3.46?×?10^?5 Scm^?1 at 323 K. NCPE films were characterized using differential scanning calorimetry (DSC) and X-ray diffraction (XRD) technique. The DSC and XRD studies revealed reduced crystallinity which confirmed the higher amorphous phase and hence the improved ionic conductivity.     

Reflectivity measurements of superionic conductors for Li ion secondary battery materials

The reflection measurements of superionic conductors LiCoO₂ and Li_1-xCoO₂, which are already in use for the positive electrode material of 4 V rechargeable lithium batteries, have been performed in the millimeter wave region from 6 to 60 cm⁻¹ using the electron storage ring facilities of Institute of Molecular Science in Okazaki. The increase of the reflectivity has been observed in the low wavenumber region below 10 cm^-1 above 300 K in Li_1-xCoO₂ for the first time, while the reflectivity of LiCoO₂ has almost the constant value in all observed temperature region between 77 to 380 K. The results will be discussed in connection with our previous results of LiNiO₂.     

Transport properties and battery discharge characteristics of the Ag+ ion conducting composite electrolyte system (1−x)[0.75AgI: 0.25AgCl]: xFe2O3

Ion transport and battery discharge characteristic studies are reported for a new Ag⁺ ion conducting two-phase composite electrolyte system (1−x)[0.75AgI: 0.25AgCl]: xFe₂O₃, where 0 ≤ x ≤ 0.5 in molar weight fraction. An alternative single-phase host-matrix ‘annealed [0.75AgI: 0.25AgCl] mixed system/ solid solution’ has been used in place of the traditional host, AgI. Submicron size particles (<1 μm) of Fe₂O₃ has been used as second phase dispersoid. The composition 0.8[0.75AgI: 0.25AgCl]: 0.2Fe₂O₃, exhibiting the highest room temperature conductivity has been referred to as the optimum conducting composition (OCC). The reason for an enhancement of an order of magnitude in the conductivity from that of the pure host has been identified through direct determination of ionic mobility (μ) and mobile ion concentration (n) using transient ionic current (TIC) technique. The XRD study confirmed the coexistence of the constituent phases. The ionic transference number is found to be very close to unity. This reveals the fact that the silver ions are the sole charge carriers in the system. The results are discussed in the light of space-charge models proposed for the two-phase composite electrolyte systems. Solid state batteries, fabricated using OCC as electrolyte, Ag-metal as anode and mixtures of iodine & graphite, viz. (C+I₂), (C+KI₃), (C+(CH₃)₄NI₃), (C+(C₂H₅)₄NI₃), etc. as cathodes, were discharged under different load conditions. The battery with (C+I₂) cathode performed satisfactorily specially under low current drain states. Paper presented at the 2nd International Conference on Ionic Devices, Anna University, Chennai, India, Nov. 28–30, 2003.     

Fast Cu+ ion conducting phosphate iodide-glasses

The glass-forming region in the ternary system CuI-Cu₂O-P₂O₅, from which Cu²⁺ ion formation has been excluded, is described and compared with that in the corresponding Ag⁺-based system. The glasses are characterized by T_g values some 50°C higher than in the silver systems. Frequency independent (dc) conductivities along the join CuI+CuPO₃ have been determined over a wide range, and found to be characterized by both higher activation energies and pre-exponential constants than the silv?r glasses. The combination leads to higher conductivities in the Cu⁺-based glasses in the composition range 20–30 mole% CuI at room temperature and above.     

Mathematical modeling of field-assisted Li ion conduction in nanocomposite solid polymer electrolyte systems

Ionics - Nanocomposite solid polymer electrolyte films were prepared to study the effect of electric field on the ionic conductivity. The studies were carried out by varying the electric field from...     

Graphene oxide doped poly(vinylidene fluoride-co-hexafluoropropylene) gel electrolyte for lithium ion battery

Gel poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) polymer electrolytes doped with graphene oxide (GO) (GO/PVDF-HFP) were designed and fabricated through a phrase inversion method and followed by LiPF₆ solution uptake. It was demonstrated that the as-prepared GO/PVDF-HFP polymer electrolytes have uniform porous morphologies, and their crystalline state, thermal stability, interfacial resistance, and electrolyte uptake and retention capabilities can be tuned by varying the GO contents. Further, it was found that the GO can prominently enhance the ionic conductivity of the GO/PVDF-HFP polymer electrolyte. The electrochemical property measurements show that the lithium ion batteries using as-prepared GO/PVDF-HFP polymer electrolytes afford admirable charge/discharge rate and cycle stability.     

Faujasite zeolites as solid electrolyte for low temperature fuel cells

In this work, the potential use of faujasite zeolites as a solid electrolyte material was evaluated with a particular focus on their endurance in acid environment, and on the influence played by the zeolites' chemical and textural properties on the degree of hydration and proton conductivity. Three faujasites with different initial Si/Al ratio were exposed to 6 mol dm⁻³ HCl solution and the exposure time was varied up to 7000 h for selected samples. Faujasite dealumination is a very fast process occurring mainly within 24 h of exposure. X-ray diffraction patterns show the faujasite structure was preserved, although N₂ sorption measurements indicate a possible partial collapse of the pore structure for samples dealuminated for 4500 and 7000 h.The proton conductivity of the faujasites is in the order of 10⁻⁸ S cm^-1 at 10% relative humidity, 10⁻⁶ S cm^-1 at 90% relative humidity, and 10⁻⁴ S cm^-1 for samples immersed in liquid water. The correlation between the proton conductivity and the zeolites' properties shows the predominant influence of the Al content at low relative humidity, and of the water content and micropore and mesopore volumes at high relative humidity. In particular, the expected increase of the proton conductivity with the mesopore volume at high relative humidity and for samples saturated with water was not observed.     

Ionic conductivity and battery characteristic studies on PEO+NaClO3 polymer electrolyte

Solid polymer electrolyte films based on poly (ethylene oxide) PEO complexed with NaClO₃ have been prepared by a solution-cast technique. The solvation of Na⁺ ion with PEO is confirmed by XRD and IR studies. Measurements of the a.c. conductivity in the temperature range 308 – 378 K and the transference numbers have been carried out to investigate the charge transport in this polymer electrolyte system. Transport number data show that the charge transport in this polymer electrolyte system is predominantly due to ions. The highest conductivity (2.12.10⁻⁴ S/cm) has been observed for the 70:30 composition. Using the polymer electrolyte solid state electrochemical cells have been fabricated. The various cell parameters are evaluated and reported.     

A thermal and electrochemical properties research on gel polymer electrolyte membrane of lithium ion battery

N-methyl-N-propyl-piperidin-bis(trifluoromethylsulfonyl)imide/bis(trifluoromethylsulfonyl) imide lithium base/polymethyl methacrylate(PP₁₃TFSI/LiTFSI/PMMA) gel polymer electrolyte (GPE) membrane was prepared by in situ polymerization. The physical and chemical properties were comprehensively discussed. The decomposition characteristics were emphasized by thermogravimetric (TG-DTG) method in the nitrogen atmosphere at the different heating rates of 5, 10, 15 and 20 °C min⁻¹, respectively. The activation energy was calculated with the iso-conversional methods of Ozawa and Kissinger, Friedman, respectively, and the Coats-Redfern methods were adopted to employ the detailed mechanism of the electrolyte membrane. The equation f(α)=3/2[(1−α)^1/3−1] was quite an appropriate kinetic mechanisms to describe the thermal decomposition process with an activation energy (E_α) of 184 kJ/mol and a pre-exponential factor (A) of 1.894×10¹¹ were obtained.     

Arrowroot + NaI: a low-cost,fast ion conducting eco-friendly polymer electrolyte system

Ionics - Energy devices are the lifeline of today’s society, and hence, they are produced in large number resulting in tremendous increase of chemical garbage. Hence, the scientific community...     

Effect of plasticizer on microstructure and electrical properties of a sodium ion conducting composite polymer electrolyte

A plasticized composite polymer electrolyte (PCPE) based on Poly (ethylene oxide) + NaI with Na₂SiO₃ as the ceramics filler and Poly (ethylene glycol) as the plasticizer has been prepared by solution cast technique. Effect of plasticization on microstrucutre and electrical properties of the materials has been investigated. The changes in the structural and microstructural properties of the material have been investigated by XRD and SEM studies. The electrical conductivity estimated using a. c. impedance spectroscopy was found to be dependent on plasticizer concentration. An enhancement in the ionic conductivity value by three times has been recorded on addition of plasticizer when compared with that of unplasticized composite polymer electrolyte. The temperature dependence of conductivity of the polymer films is found to obey the Arrhenius behavior below and above the melting temperature of PEO. The electrical transport has been found to be a thermally activated process with ions being the predominant charge carrier.     

Magnesium ion conducting solid polymer blend electrolyte based on biodegradable polymers and application in solid-state batteries

Ionics - Magnesium ion conducting solid polymer blend electrolyte based on biodegradable polymers polyvinyl alcohol (PVA) and polyvinyl pyrrolidone (PVP) mixed with different molecular weight...     

Preparation and characterization of a lithium ion conducting electrolyte based on poly(trimethylene carbonate)

In this paper, the results of preliminary studies of two new solvent-free polymer electrolytes based on poly(trimethylene carbonate), p(TMC), with lithium trifluoromethanesulphonate, (triflate), and lithium perchlorate are described. Thin films of these electrolytes were obtained by evaporation of solvent from homogeneous mixtures of known masses of host polymer and salt. Electrolytes with compositions of n between 1.5 and 85, where n represents the molar ratio of (O=COCH₂CH₂CH₂O) units per lithium ion, have been prepared. These solvent-free electrolytes were characterized by measurements of total ionic conductivity, differential scanning calorimetry (DSC) and thermogravimetry (TGA). As expected from previous studies with these salts in poly(ethylene oxide), PEO, the triflate-based system showed superior thermal stability but with a lower total ionic conductivity than that of the perchlorate-containing electrolyte. The highest conductivity (approximately 3×10⁻⁴ Ω⁻¹ cm⁻¹) was found at 95°C with the electrolyte composition of (TMC)₂LiClO₄.     

High lithium ion conducting glass-ceramics in the system Li2S–P2S5

Highly ion-conductive Li₂S–P₂S₅ glass-ceramic electrolytes were prepared by controlling the compositions and heat treatment temperatures of the glasses. The 70Li₂S·30P₂S₅ (mol%) glass-ceramic heated at 360 °C showed the highest conductivity of 3.2 × 10^− 3 S cm^− 1 at room temperature and the lowest activation energy of 12 kJ mol^− 1 for conduction in the binary system Li₂S–P₂S₅. The outstanding property was attributed to both the precipitation of the new crystal as a metastable phase and the increase in crystallinity of the phase. With increasing heat treatment temperatures, the metastable phase changed into thermodynamically stable phases such as the Li₄P₂S₆ crystal by heat treatment up to 550 °C, resulting in low conductivities of the glass-ceramics. It was, thus, found that the formation of superionic metastable phases by heating the Li₂S–P₂S₅ glasses is responsible for the marked enhancement on the conducting properties of the glass-ceramics.