Kabushiki Kaisha Toyota Jidoshokki

National Institute of Advanced Industrial Science and Technology

Akira Kojima

Tetsuo Sakai

Toshikatsu Kojima

Takuhiro Miyuki

Yuta Ikeuchi

Masakazu Murase

Takayuki Hirose

Hitotoshi Murase

Manabu Miyoshi

Junichi Niwa

Kazuhito Kawasumi

Mitsuharu Tabuchi

Masataka Nakanishi

Masanori Morishita

Tatsuya Eguchi

Hitoshi Aikiyo

Yuya Sato

Yasue Okuyama

Kazuaki Hokano

Hideki Goda

Kazuhiro Izumoto

To provide a lithium ion secondary battery capable of suppressing thermal run-away when internal short circuiting occurs. The lithium ion secondary battery includes: a positive electrode including a current collector, a positive electrode active material layer that is formed on the current collector and that contains a lithium-containing complex oxide having a layered rock salt structure and being represented by general formula: LiNiCoMnDO(0.2&#x2266;a&#x2266;1; b+c+d+e=1; 0&#x2266;e&#x3c;1; D is at least one element selected from Li, Fe, Cr, Cu, Zn, Ca, Mg, S, Si, Na, K, and Al; 1.7&#x2266;f&#x2266;2.1), and a thermal run-away suppressing layer formed on the positive electrode active material layer and containing a lithium transition metal silicate; and a negative electrode including a negative electrode active material. A ratio of the mass of the lithium-containing complex oxide with respect to the mass of the lithium transition metal silicate in the positive electrode is not lower than 1.5.

Lithium ion secondary battery having positive electrode that comprises thermal run-away suppressing layer on positive electrode active material layer

A lithium-ion secondary battery of the present invention comprises a positive electrode including a positive electrode active material composite formed by compositing a lithium silicate-based material and a carbon material, a negative electrode including a negative electrode active material containing a silicon, and an electrolyte. The lithium-ion secondary battery satisfies 0.8&#x3c;B/A&#x3c;1.2, where A is irreversible capacity of the positive electrode and B is irreversible capacity of the negative electrode.

Lithium-ion secondary battery and method for producing the same

Provided are a positive electrode active material for a sodium ion secondary battery, and a positive electrode and a sodium ion secondary battery using the material. The positive electrode active material for a sodium ion secondary battery comprises a lithium sodium-based compound containing lithium (Li), sodium (Na), iron (Fe), and oxygen (O).

Positive electrode active material for sodium ion secondary battery, positive electrode, and sodium ion secondary battery

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

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.

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Kariya, Japan

Akira Kojima