Kabushiki Kaisha Toyota Jidoshokki

National Institute of Advanced Industrial Science and Technology

Ist Corporation, Limited

Takuhiro Miyuki

Tetsuo Sakai

Junichi Niwa

Akira Kojima

Toshikatsu Kojima

Kazuhito Kawasumi

Hitotoshi Murase

Masakazu Murase

Mitsuharu Tabuchi

Masataka Nakanishi

Masanori Morishita

Yuya Sato

Yasue Okuyama

Kazuaki Hokano

Yuusuke Eda

Kazuki Sawa

Yoshihito Nimura

Provided is a novel lithium silicate-based material useful as a positive electrode material for lithium ion secondary battery. The lithium silicate-based compound is represented by LiFeSiO. The lithium silicate-based compound is a compound including: lithium (Li); iron (Fe); silicon (Si); and oxygen (O), and expressed by a composition formula, LiFeSiO(&#x2212;0.25&#x2266;&#x3b4;&#x2266;0.25, 0&#x2266;c&#x2266;0.5). The lithium silicate-based compound, of which iron (Fe) is trivalent, exerts a remarkable chemical stability as compared to LiFeSiO.

Lithium silicate-based compound, positive electrode active material for lithium ion secondary battery, and lithium ion secondary battery using the same

A production process for lithium-silicate-based compound according to the present invention is characterized in that: a lithium-silicate compound being expressed by Li2SiO3 is reacted with a transition-metal-element-containing substance including at least one member being selected from the group consisting of iron and manganese at 550&#xb0; C. or less within a molten salt including at least one member being selected from the group consisting of alkali-metal nitrates as well as alkali-metal hydroxides in an atmosphere in the presence of a mixed gas including carbon dioxide and a reducing gas. In accordance with the present invention, it is possible to produce lithium-silicate-based materials, which are useful as a positive-electrode active material for lithium-ion secondary battery, and the like, at low temperatures by means of relatively easy means.

Production process for lithium-silicate-based compound

The present invention is one which provides a production process for lithium-silicate-system compound, the production process being characterized in that: a lithium-silicate compound being expressed by LiSiOis reacted with a substance including at least one member of transition-metal elements that is selected from the group consisting of iron and manganese at 400-650&#xb0; C. in a molten salt of a carbonate mixture comprising lithium carbonate and at least one member of alkali-metal carbonates that is selected from the group consisting of potassium carbonate, sodium carbonate, rubidium carbonate and cesium carbonate in a mixed-gas atmosphere including carbon dioxide and a reducing gas; and a positive-electrode active material for lithium-ion secondary battery that comprises a lithium-silicate-system compound being obtained by the aforesaid process.

Production process for lithium-silicate-system compound

A lithium silicate-based compound according to the present invention is expressed by a general formula, LiAMnCoMSiOCl(In the formula: 'A' is at least one element selected from the group consisting of Na, K, Rb and Cs; 'M' is at least one member selected from the group consisting of Mg, Ca, Al, Ni, Fe, Nb, Ti, Cr, Cu, Zn, Zr, V, Mo and W; and the respective subscripts appear to be as follows: 0&#x2266;&#x201c;a&#x201d;&#x3c;0.2; 0&#x2266;&#x201c;b&#x201d;&#x3c;1; 0&#x3c;&#x201c;x&#x201d;&#x3c;1; 0&#x2266;&#x201c;y&#x201d;&#x2266;0.5; &#x2212;0.25&#x2266;&#x201c;&#x3b1;&#x201d;&#x2266;1.25; and 0&#x2266;&#x201c;&#x3b2;&#x201d;&#x2266;0.05). The lithium silicate-based compound is used as a positive-electrode active material for secondary battery whose discharge average voltage is higher, and which is able to sorb and desorb lithium ions.

Lithium silicate-based compound and production process for the same, positive-electrode active material and positive electrode for use in lithium-ion secondary battery as well as secondary battery

Provided is a sulfur-modified polyacrylonitrile manufacturing method that is characterized in that a starting base powder that comprises sulfur powder and polyacrylonitrile powder is mixed and the mixture is heated in a non-oxidizing environment while outflow of sulfur vapor is prevented. Also provided are a cathode for lithium batteries that uses, as the active substance, the sulfur-modified polyacrylonitrile manufactured with the method, and a lithium secondary battery that includes the cathode as a component element. This enables the practical use of an inexpensive sulfur-based material as the cathode material for lithium secondary batteries, and in particular, a sulfur-based cathode material that enables higher output and has excellent cycle life characteristics, as well as other characteristics, and secondary lithium batteries using the same can be obtained.

Sulfur-modified polyacrylonitrile, manufacturing method therefor, and application thereof

To provide a sulfur-system positive electrode for lithium-ion battery, sulfur-system positive electrode which is good in the cyclability and the other characteristics, and a lithium-ion secondary battery including that positive electrode. In a positive electrode for lithium-ion secondary battery, the positive electrode having: a current collector; and an electrode layer that is formed on a surface of the current collector, and which includes a binder resin, an active material and a conductive additive, the positive electrode is characterized in that the active material includes a sulfur-modified polyacrylonitrile that is produced by heating a raw-material powder including a sulfur powder and a polyacrylonitrile powder in an enclosed nonoxidizing atmosphere; and the binder resin includes a polyimide resin and/or a polyamide-imide resin.

Positive electrode for lithium-ion secondary battery and lithium-ion secondary battery comprising that positive electrode

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Ikeda, Japan

Takuhiro Miyuki