Agency of Industrial Science and Technology

National Institute of Advanced Industrial Science and Technology

Ministry of International Trade & Industry

Agency of Industrial Science and Technology Ministry of International

Agency of Industrial Science & Technology, Ministry of International Trade & Industry

Secretary, Agency of Industrial Science and Technology

Kazuaki Ado

Mitsuharu Tabuchi

Hiroyuki Kageyama

Soichiro Nobuoka

Hironori Kobayashi

Takashi Asai

Tomonari Takeuchi

Osamu Nakamura

Hikari Sakaebe

Kuniaki Tatsumi

Yoko Nabeshima

The present invention provides a lithium manganese-based composite oxide represented by the compositional formula: Li(MnFeTi)O, wherein 0&#x3c;x&#x3c;&#x2153;, 0&#x2266;m&#x2266;0.75, 0.01&#x2266;n&#x2266;0.75, and 0.01&#x2266;m+n&#x3c;1, and comprising a crystal phase of layered rock-salt type structure. The composite oxide is capable of maintaining an average discharge voltage of 3 V or more over long charge/discharge cycles. The composite oxide can be prepared using lower-cost starting materials, and exhibits improved charge/discharge characteristics over conventional low-cost positive electrode materials.

Lithium manganese-based composite oxide and method for preparing the same

The present invention provides a single-phase lithium ferrite based oxide which is suitable as a cathode material for a secondary battery, a process for preparing the oxide, and its uses, the oxide having a layered rock salt-type structure and comprising lithium ferrite (LiFeO )&minus;Li MO solid solution wherein M is at least one species selected from the group consisting of Mn, Ti and Sn, 0&lE;x<2, 0&lE;y&lE;1 such that the proportion of iron is &lE;Fe/(Fe&plus;M)&lE;0.9.

Single-phase lithium ferrite based oxide

A lithium cobalt oxide (LiCoO ) having a layered rock-salt type structure produced at low temperatures by hydrothermally treating at least one water-soluble cobalt salt in an aqueous solution containing a water-soluble lithium salt and an alkali metal hydroxide at 105 to 300&deg; C. in the presence of an oxidizing agent. An inexpensive salt of divalent cobalt is used as a starting material in this process. The lithium cobalt oxide thus obtained is useful as a cathode material for rechargeable lithium batteries.

Process for producing layered rock-salt type lithium cobalt oxide by hydrothermal oxidation

A sintered lithium titaniumphosphate is produced by subjecting the powder of a mixture consisting of a Li source, a Ti source, and a P source to spark plasma sintering under an increased pressure.

Method for production of sintered lithium titaniumphosphate and sintered pellets obtained by the method

Hydrothermal treatment of at least one manganese source material, for example, an oxide of manganese, such as Mn,O,, MnO, or MnO,, in an aqueous solution containing at least one water-soluble lithium salt, such as lithium hydroxide, lithium chloride, lithium nitrate, lithium fluoride, or lithium bromide, and an alkaline metal hydroxide, such as potassium hydroxide, at 130 to 300&deg; C. can realize the preparation of a lithium manganese oxide (LiMnO,) having a layered rock-salt structure in a single stage.

Process for preparing layered rock-salt type lithium manganese oxide by mixed alkaline hydrothermal method

A method of determining the charge and/or discharge capacities of non-aqueous batteries with an operating voltage of about 4 volts, is provided including determining an inverse molar susceptibility value at each of a plurality of different temperatures for a plurality of lithium manganese spinel oxide cathode materials having different respective Mn valencies; plotting the inverse molar susceptibility values against temperatures for each of the plurality of lithium manganese spinel oxide cathode materials; determining values of at least one of two paramagnetic parameters, Weiss temperature and effective magnetic moment, by obtaining the temperature dependence of the above inverse molar susceptibility from a plot derived from the Curie-Weiss law, the Weiss temperature corresponding to a temperature value extrapolated to a zero point of the inverse molar susceptibility and the effective magnetic moment being obtainable from the gradient value of the plot; producing plural rechargeable lithium batteries in which lithium manganese spinel oxides with well-defined Mn valencies are used as cathode materials, and finding at least one of the charge or discharge capacities around 4V for each of the batteries; providing at least one correlation curve between the above-found charge and/or discharge capacities and the above-found at least one paramagnetic parameter value; and obtaining charge and/or discharge capacities for a rechargeable lithium battery containing a lithium manganese spinel oxide whose charge and/or discharge capacities are being sought from the at lest one determined paramagnetic parameter value using the at least one correlation curve. A method of determining the charge and/or discharge capacities of non-aqueous batteries with an operating voltage of about 4 volts, is also provided which includes determining a spontaneous magnetization value for each of a plurality of lithium manganese spinel oxide cathode materials having a different respective Mn valency by determining a magnetization value of each of a plurality of magnetic fields at a constant temperature to obtain and thereafter use a correlation curve.

Method for predicting discharge capacity and operating voltage of

A process for preparing LiFeO.sub.2 having a layered rock salt type structure is characterized in that at least one member selected from the group consisting of water-soluble iron salts, iron hydroxides, iron oxide hydroxides, and metallic iron is subjected to a hydrothermal treatment in an aqueous solution containing lithium hydroxide and at least one of sodium hydroxide and potassium hydroxide at 130.degree. to 300.degree. C.

Process for preparing layered rock salt type lithium ferrite by mixed

Yellow iron oxide crystals having lengths in the range of 100 to 1000 nm and a major axis/motor axis length ratio in the range of 1.5 to 4.5 are produced by adding an aqueous ferric salt solution to an aqueous alkali solution, causing the two solutions to react with each other at a temperature in the range of -5.degree. to 30.degree. C. thereby inducing precipitation of iron hydroxide, allowing the precipitate to age, then subjecting the aged precipitate to a hydrothermal treatment thereby producing crystals and, when necessary, further allowing the crystals to grow.

Yellow iron oxide pigment and method for manufacture thereof

In the manufacture of iron oxide flakes by the steps of mixing an aqueous ferric salt solution with an aqueous alkali solution for thereby inducing an amorphous precipitate and subjecting the precipitate to a hydrothermal treatment, iron oxide flakes of an increased flake size are obtained by adding boric acid or a salt thereof to the mixture prior to the step of hydrothermal treatment.

Method for manufacture of iron oxide flakes

Synthetic yellow iron oxide (.alpha.-FeOOH) is dispersed in an aqueous 0 - 10N alkali solution and the resultant dispersion is subjected to a hydrothermal treatment at 100.degree.- 250.degree.C. This treatment improves the synthetic yellow iron oxide in that it converts imperfect crystals present in said iron oxide into perfect crystals, changes particles thereof from the shape of needles to that of rods, makes the particle size substantially uniform and heightens the resistivity thereof to heat by about 50.degree.C. The modified synthetic yellow iron oxide thus obtained is innoxious and can be used as a pigment in paints.

Growing community of inventors

Ikeda, Japan

Kazuaki Ado