Tdk Corporation

Masaki Sobu

Atsushi Sano

Akinobu Nojima

Yasuhiro Ikeda

Tomohiko Kato

Katsunori Osanai

Tetsuo Takaishi

Tatsuya Kato

Hideki Hirata

Masahiro Nakano

Hiroki Kitamura

Masanori Kosuda

Hideaki Seki

Hiroshi Takasaki

Yasuhiro Takagi

Shigeki Ohtsuka

Hiroyuki Miyabara

Yoshikazu Kihara

Yukiko Hirabayashi

Yasunaga Kagaya

Tomoshi Nakamoto

Hiroshi Shinngai

Yukio Hirokawa

A negative electrode active material with sufficiently high discharge capacity at a high rate, and a negative electrode and a lithium ion secondary battery using the negative electrode active material. A negative electrode active material according to the invention includes a negative electrode active material particle containing silicon and silicon oxide, wherein a surface layer part of the negative electrode active material particle is a layer with lower density than a core part of the negative electrode active material particle. With such a structure of the negative electrode active material, the sufficiently high discharge capacity at a high rate can be obtained.

Negative electrode active material, and negative electrode and lithium ion secondary battery using the negative electrode active material

A negative electrode active material is provided for a lithium ion secondary battery having high initial charging/discharging efficiency. The negative electrode active material containing silicon and silicon oxide has two phases with different compositions therein. One of the two phases has a lower silicon element concentration than the other phase, and is a fibrous phase forming a network structure in a cross section of primary particle of the negative electrode active material. Use of the negative electrode active material enables a sufficient increase in initial charging/discharging efficiency.

Provided are a negative electrode active material for a lithium ion secondary battery, which has sufficiently high discharge capacity at a high rate. The negative electrode active material containing silicon and silicon oxide includes primary particles having two phases of different compositions therein. One of the two phases has a higher silicon element concentration than the other phase, and is a fibrous phase forming a network structure in a cross section of the primary particle. Use of the negative electrode active material enables a sufficient increase in discharge capacity at a high rate.

A positive electrode active material contains a compound represented by a chemical formula LiVOPO. A crystal system of the compound is an orthorhombic system, and the amount of tetravalent V of the compound is 27.7 mass % or more and 28.2 mass % or less.

Positive electrode active material and lithium-ion secondary battery

A lithium ion secondary battery with a high electrode density and an excellent rate discharge characteristic. The positive electrode includes a positive electrode active material of a compound represented by Li(NiCoAl)O(0.95&#x2266;a&#x2266;1.05, 0.5&#x2266;x&#x2266;0.9, 0.05&#x2266;y&#x2266;0.2), and carbon adhered to the surface of the material, in the Raman spectrum using a laser of 532 nm, the positive electrode includes a peak P(D band) at 1200&#x2dc;1450 cm, a peak P(G band) at 1450&#x2dc;1700 cmand a peak Pat 400&#x2dc;600 cm, and when the intensities are normalized by regarding the maximum intensity as 1 and the minimum intensity as 0 in the wavenumber domain of 200&#x2dc;1800 cm, Raman intensity of the minimum (V band) between the two peaks of said peak Pand said peak Pis 0.6 or less, and Raman intensity of said peak Pis 0.1 or more and 0.5 or less.

Positive electrode and lithium ion secondary battery using thereof

To provide an active material with high capacity, high initial charge-discharge efficiency, and high average discharge voltage. An active material according to the present invention includes a first active material and a second active material, wherein the ratio (&#x3b4;) of the second active material (B) to the total amount by mole of the first active material (A) and the second active material (B) satisfies 0.4 mol %&#x2266;&#x3b4;&#x2266;18 mol % [where &#x3b4;=(B/(A+B))&#xd7;100].

Active material, electrode using same, and lithium ion secondary battery

An active material having high capacity and excellent charging/discharging cycle durability at high potential is provided. The active material has a layered structure and is represented by the following composition formula (1):LiNiCoMnMOFP&#x2003;&#x2003;(1)wherein the element M is at least one element selected from the group consisting of Al, Si, Zr, Ti, Fe, Mg, Nb, Ba and V, and 1.9&#x2266;(a+b+c+d+y)&#x2266;2.1, 1.0&#x2266;y&#x2266;1.3, 0&#x3c;a&#x2266;0.3, 0&#x2266;b&#x2266;0.25, 0.3&#x2266;c&#x2266;0.7, 0&#x2266;d&#x2266;0.1, 0.07&#x2266;z1&#x2266;0.15, 0.01&#x2266;z2&#x2266;0.1, and 1.9&#x2266;(x+z1)&#x2266;2.1 are satisfied.

Active material, manufacturing method for active material, and lithium ion secondary battery

A negative electrode active material mainly contains silicon and silicon oxide. In the negative electrode active material, an Ar-laser Raman spectrum thereof includes a peak A corresponding to 950&#xb1;30 cmand a peak B corresponding to 480&#xb1;30 cm, and an intensity ratio of the peak B to the peak A (B/A) is in the range of 1 to 10.

Negative electrode active material, electrode containing the same, and lithium ion secondary battery having the electrode

A rewritable phase-change optical recording medium is provided, which includes a substrate, a first information layer, a spacer layer, a second information layer, and a cover layer. The second information layer includes a recording film containing Sb as a main component and V or V and In as second components. When an amorphous mark formed in the recording film is irradiated with a reproduction beam, crystallization of the amorphous mark occurs only in a central portion in the width direction of the amorphous mark. The width direction is orthogonal to the scanning direction of the laser beam. The recording film is formed of a material that exhibits a change in degree of modulation of 5% or less when recorded information is repeatedly reproduced. The change in degree of modulation is a change from when the number of times of reproduction is 100,000 to when it is 400,000.

Rewritable phase-change optical recording medium

A surface acoustic wave element, a surface acoustic wave device, a duplexer, and a method of making a surface acoustic wave element which significantly restrain characteristics from deteriorating are provided. The surface acoustic wave element in accordance with the present invention comprises a piezoelectric substrate, and an IDT electrode formed on the piezoelectric substrate, whereas the piezoelectric substrate has a volume resistivity of not less than 3.6&#xd7;10&#x3a9;&#xb7;cm and not more than 1.5&#xd7;10&#x3a9;&#xb7;cm. This surface acoustic wave element comprises the piezoelectric substrate having a low volume resistivity, whereas the volume resistivity is reduced to 1.5&#xd7;10&#x3a9;&#xb7;cm or less. Therefore, discharging is restrained from occurring between IDT electrodes, whereby characteristics are significantly kept from deteriorating. Also, since the volume resistivity of the piezoelectric substrate is not less than 3.6&#xd7;10&#x3a9;&#xb7;cm, the IDT electrodes are significantly prevented from short-circuiting with each other.

Surface acoustic wave element, surface acoustic wave device, duplexer, and method of making surface acoustic wave element

A SAW device comprises a single crystal piezo-electric strate (made, for example, of LiTaOor LiNbO), and an interdigital transducer (IDT) formed of a material mainly containing Al and disposed on the piezo-electric substrate. The piezo-electric strate contains an additive (for example, Fe, Mn, Cu, Ti), and an orientation rotated by an angle in a range of 42&#xb0; to 48&#xb0; (more preferably 46&#xb0;&#xb1;0.3&#xb0;) from a Y-axis toward a Z-axis about an X-axis. The IDT presents a normalized thickness h/&#x3bb; (h: thickness of electrode, and &#x3bb;: spacing between digits of the IDT) of 7% to 11%. A more appropriate substrate cut angle can be shown for the SAW device which employs a piezo-electric substrate containing an additive, to improve the electric characteristics thereof.

Surface acoustic wave device

A surface acoustic wave element includes a thin film electrode composed of monocrystal aluminum disposed on a piezoelectric substrate. At least one metal of Cu, Ta, W, and Ti is segregated in the thin film electrode composed of monocrystal aluminum. In this surface acoustic wave element, segregation of Cu or the like occurs in the thin film electrode. Such segregation is effective to reduce the occurrence of cracks on the piezoelectric substrate during ultrasonic wave connection for flip chip mounting. That is, because the occurrence of cracks on the piezoelectric substrate is reduced, tolerance against the ultrasonic vibration is advantageously improved in the surface acoustic wave element.

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Tokyo, Japan

Masaki Sobu