Recent development of sulfide solid electrolytes and interfacial modification for all-solid-state rechargeable lithium batteries

AbstractRecent development of inorganic sulfide solid electrolytes and all-solid-state rechargeable lithium batteries with them is reviewed. Electrical conductivity, electrochemical stability and chemical stability of these sulfide electrolytes are reported. Formation of favorable solid–solid contacts between electrode and electrolyte is important in all-solid-state batteries. Useful techniques to achieving intimate electrode–electrolyte interfaces are proposed. Application of sulfur positive electrode and lithium metal negative electrode with large theoretical capacity to all-solid-state lithium batteries is demonstrated

Kinetics of Interfacial Lithium-ion Transfer between a Graphite Negative Electrode and a Li₂S-P₂S₅ Glassy Solid Electrolyte

All-solid-state lithium-ion batteries that use sulfide solid electrolytes have attracted much attention due to their high safety and wide electrochemical window. In this study, highly oriented pyrolytic graphite (HOPG) and 75Li₂S-25P₂S₅ (mol%) glass were used as a model graphite negative electrode and a sulfide solid electrolyte, respectively. Interfacial lithium-ion transfer between 75Li₂S-25P₂S₅ glass and the HOPG electrode was studied by AC impedance spectroscopy measurements. The activation energy of the interfacial lithium-ion transfer was estimated to be around 37 kJ mol⁻¹, which was much smaller than that at the interface between organic liquid electrolytes and HOPG electrode, indicating that the lithium-ion transfer at the interface between 75Li₂S-25P₂S₅ glass and HOPG electrode proceeded quite rapidly. Furthermore, surface deposition of TiO₂ and surface oxidation on HOPG electrodes were performed using the atomic layer deposition (ALD) method. Interfacial lithium-ion transfer between 75Li₂S-25P₂S₅ glass and ALD-modified-HOPG electrodes was also investigated. The activation energies of the interfacial lithium-ion transfer were slightly higher than that of HOPG, but the resistance of the charge-transfer process was lower, indicating that the affinity of the HOPG electrode for the glass electrolyte was improved by surface modification

Unique Li deposition behavior in Li₃PS₄ solid electrolyte observed via operando X-ray computed tomography

The problem of lithium dendrites must be addressed for practical lithium metal all-solid-state batteries. Herein, three-dimensional morphological changes within Li₃PS₄ electrolyte away from the anode were observed using operando X-ray computed tomography. We revealed that the electronic conduction of decomposition and the electrolyte/void interface cause the lithium deposition within the Li₃PS₄

A reversible oxygen redox reaction in bulk-type all-solid-state batteries

An all-solid-state lithium battery using inorganic solid electrolytes requires safety assurance and improved energy density, both of which are issues in large-scale applications of lithium-ion batteries. Utilization of high-capacity lithium-excess electrode materials is effective for the further increase in energy density. However, they have never been applied to all-solid-state batteries. Operational difficulty of all-solid-state batteries using them generally lies in the construction of the electrode-electrolyte interface. By the amorphization of Li₂RuO₃ as a lithium-excess model material with Li₂SO₄, here, we have first demonstrated a reversible oxygen redox reaction in all-solid-state batteries. Amorphous nature of the Li₂RuO₃-Li₂SO₄ matrix enables inclusion of active material with high conductivity and ductility for achieving favorable interfaces with charge transfer capabilities, leading to the stable operation of all-solid-state batteries

Alkali environments in tellurite glasses

Neutron diffraction measurements are reported for five binary alkali tellurite glasses, xM2O · (100 − x)TeO2 (containing 10 and 20 mol% K2O, 10 and 19 mol% Na2O, and 20 mol% 7Li2O), together with 23Na MAS NMR measurements for the sodium containing glasses. Differences between neutron correlation functions are used to extract information about the local environments of lithium and sodium. The Na–O bond length is 2.37(1) Å and the average Na–O coordination number, nNaO, decreases from 5.2(2) for x = 10 mol% Na2O to 4.6(1) for x = 19 mol% Na2O. The average Li–O coordination number, nLiO, is 3.9(1) for the glass with x = 20 mol% Li2O and the Li–O bond length is 2.078(2) Å. As x increases from 10 to 19 mol% Na2O, the 23Na MAS NMR peak moves downfield, confirming an earlier report of a correlation of peak position with sodium coordination number. The close agreement of the maximum in the Te–O bond distribution for sodium and potassium tellurite glasses of the same composition, coupled with the extraction of reasonable alkali coordination numbers using isostoichiometric differences, gives strong evidence that the tellurium environment in alkali tellurites is independent of the size of the modifier cation used

Photocatalytic O-2 evolution from water over Zn-Cr layered double hydroxides intercalated with inorganic anions

Zn-Cr layered double hydroxides (LDHs) intercalated with inorganic anions (CO32-, Cl-, SO42- and NO3-) were synthesized by the co-precipitation method and the anion exchange process. The photocatalytic activity of the LDHs was studied by O-2 evolution from aqueous solution of AgNO3 as a sacrificial agent. All the prepared LDHs showed photocatalytic activity under either UV and/or visible light irradiation. Besides, the interlayer anions affected the photocatalytic activity of the LDHs. After irradiation, Ag particles were formed on the LDHs by accepting the electrons generated during the photocatalytic reaction

All-solid-state electrochemical capacitors using MnO2/carbon nanotube composite electrode

MnO2/carbon nanotube (CNT) composite was prepared by a solution process. In the obtained MnO2-CNT composite, MnO2 particles were well-dispersed on CNTs. The specific capacitance of the MnO2-CNT composite in an aqueous electrolyte was higher than that of MnO2 and CNT. All-solid-state electrochemical capacitors (ECs) were fabricated using the MnO2-CNT composite as a positive electrode, activated carbon powder as a negative electrode, and phosphosilicate gel as an electrolyte. The obtained all-solid-state ECs operated at the temperature range between -30 degrees C and 100 degrees C. The specific discharge capacitance and the rate ability of the capacitors were improved by elevating temperature. In addition, the fabricated all-solid-state ECs exhibited excellent cycle performance at the temperature range between -30 degrees C and 100 degrees C for 20,000 cycles. These results indicate that all-solid-state ECs using MnO2 are promising energy storage devices with excellent stability and high reliability at the wide range of temperatures. (C) 2013 Elsevier Ltd. All rights reserved

Synthesis of monodispersed silica nanoparticles with high concentration by the Stober process

Silica nanoparticles with high concentration were prepared by the sol-gel process based on the Stober method using tetraethoxysilane as a starting material. It was found that silica sol with about 4 wt% in concentration and with a diameter of about 10 nm was obtained by controlling the reaction conditions in the Stober process. By removing the solvent under a reduced pressure, the particle concentration was increased up to 15 wt% without aggregation

Substituent effects on the glass transition phenomena of polyorganosilsesquioxane particles prepared by two-step acid–base catalyzed sol–gel process

Polyorganosilsesquioxanes (RSiO3/2) (R: organic group) particles with different organic groups such as alkyl and aryl groups were prepared using a two-step acid–base catalyzed sol–gel process. Spherical particles were formed at room temperature using the two-step acid–base catalyzed sol–gel process in which trifunctional organoalkoxysilanes with R = methyl, n-propyl, n-butyl, phenyl, and benzyl were used as starting materials. Polyorganosilsesquioxanes with longer alkyl groups or phenethyl group prepared by the two-step acid–base catalyzed sol–gel process were oily material at room temperature. Polyorganosilsesquioxanes with shorter alkyl or aryl groups exhibited the glass transition. In contrast, polyorganosilsesquioxanes with longer alkyl groups showed no glass transition behavior. The occurrence of glass transition phenomena of polyorganosilsesquioxanes was concluded to be strongly dependent on the chain length of organic substituents