Noboru Aotani

Solid state lithium battery with oxysulfide glass

Abstract Oxysulfide glass, Li3PO4-Li2S-SiS2, shows a high ionic conductivity of 1.4 × 103 S/cm at ambient temperature and a wide electrochemical window. It is chemically and electrochemically stable against lithium metal. LixCoO2 and In-Lix were found to be good candidates for the electrode materials in solid state batteries with the glass for their electrode reactions with high reversibility. The solid state battery constructed with the materials reveals excellent cycling property, high rate capability up to almost 1 mA/cm2, and extremely small residual current.

Synthesis and electrochemical properties of lithium ion conductive glass, Li3PO4Li2SSiS2

Abstract As a continuation of our previous study, further experiments were performed on Li 3 PO 4 Li 2 S SiS 2 lithium ion conductive glass. In the present study, we employed a twin roller for quenching process instead of liquid nitrogen. We found that the glass forming region expands by twin roller technique and conductivity up to 1.5 × 10 −3 S/cm was achieved. Structural analysis on the glass revealed that Li 3 PO 4 doping changes the glass structure of Li 2 S SiS 2 , thereby enhancing the electrical conductivity.

Application of Li3PO4-Li2S-SiS2 glass to the solid state secondary batteries

Our previous study showed that lithium ion conductive glass, Li 3 PO 4 -Li 2 S-SiS 2 , has high ionic conductivity and high stability against electrochemical oxidation. Such stability will enable solid state batteries to be operated at high voltages. We constructed solid state batteries with LiCoO 2 as a positive electrode and indium as a negative electrode material, and investigated their performance. The operation voltage of In/LiCoO 2 cell was 3.5 V, which was a high voltage for a solid state battery. The cell showed its high charge-discharge efficiency and good cycling performance, and it was available at high current density ( > 500 μA/cm 2 ). Its residual current under charging at constant voltage was extremely small so that it has high overcharge prevention.

Electrochemical behavior of LixMO2 (M = Co, Ni) in all solid state cells using a glass electrolyte

Abstract Electrochemical behavior of transition metal oxides, Li x MO 2 ( M = Co , Ni ) was examined in all solid state cells using a lithium ion conductive glass, Li 3 PO 4 -Li 2 S-SiS 2 , as the electrolyte and Li metal as the negative electrode. Complex impedance analysis showed that the electrochemical reaction rate at Li x CoO 2 electrode was mainly controlled by diffusion for x > 0.95 and by charge transfer for x

Electrochemical behaviors of Li+ ion conductor, Li3PO4-Li2S-SiS2

Abstract There are gret interests on sulfide glasses because of their high lithium ion conductivity. We synthesized a new lithium ion conductive solid electrolyte, Li3PO4-Li2S-SiS2 to obtain a solid temperature was 7.6 × 10−4 S/cm, and proved to be stable against electrochemical reduction. We also investigated the electrochemical behaviors of spherical graphite with this electrolyte as a preliminary study for solid-state batteries and proved that spherical graphite seems a good candidate for negative electrode material in the solid-state batteries.

Rechargeable solid state battery with lithium conductive glass, Li3PO4Li2SSiS2

Abstract We performed the preliminary study on the development of a rechargeable solid state lithium battery. We have used lithium ion conductive glass, Li 3 PO 4 Li 2 SSiS 2 , as an electrolyte, which exhibits high ionic conductivity. Investigation on TiS 2 /Li cells suggested that Li + ion diffusion in the positive electrode controlled the charge-discharge capacity of the cell. The rate capability of the battery is considered to be improved by using Ag 2 S as a positive electrode material. Electrode properties of spherical graphite revealed that the graphite is a good candidate for negative electrode material in the solid state battery.