Tdk Corporation

Hiroyuki Miyabara

Atsushi Sano

Hiroki Kitamura

Hideaki Seki

Masaki Sobu

Kiyoto Fukushima

Tetsuo Takaishi

Shigeharu Watase

Yukiko Hirabayashi

Yoshio Kawakami

Junpei Shitaba

Yasuhiko Emori

A positive electrode active material for lithium ion secondary battery includes: active material particles including one or more compounds including Li and a transition metal; and a coating layer coating at least a part of a surface of the active material particles. The coating layer includes at least one of graphene or multilayer graphene The coating layer has a Raman spectrum with a G band (a peak of 1530 cmto 1630 cm), a D band (a peak of 1300 cmto 1400 cm), and a 2D band (a peak of 2650 cmto 2750 cm). At least the intensity of the 2D band normalized by the intensity of the G band (2D/G) satisfies 0.05&#x2264;2D/G.

Positive electrode active material including lithium transition metal particles with graphene coating layer positive electrode and lithium ion secondary battery including the same

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

[Problem] To provide a lithium ion secondary battery having excellent high-rate discharge characteristics. [Solution] Excellent high-rate discharge characteristics are obtained by a lithium ion secondary battery in which a compound represented by Li(NiCoAl)O(where 0.95&#x2266;a&#x2266;1.05, 0.5&#x2266;x&#x2266;0.9, 0.05&#x2266;y&#x2266;0.2, and 0.7&#x2266;x+y&#x2266;1.0) is used as a positive electrode active material in a positive electrode, the positive electrode has an electrode density of 3.75 to 4.1 g/cm, and the positive electrode has a BET specific surface area of 1.3 to 3.5 m/g as an electrode.

Lithium ion secondary battery

Disclosed is a magnetic recording medium comprising a nonmagnetic support and a paint film layer which is provided on the support and has a lamination structure consisting of two or more layers, wherein the top surface magneticlayer of the layers constituting the paint film layer contains abrasive particles having a Mohs hardness of not less than 6 in an amount of 3 to 16 parts by weight based on 100 parts by weight of a ferromagnetic powder and has a thickness of not more than 0.5 .mu.m, a ratio of a mean particle diameter of the abrasive particles to the thickness of the top surface magnetic layer is in the range of 1.0 to 1.8, and a content of the abrasive particles each having a size larger than the thickness of the top surface magnetic layer in the particle size distribution of the abrasive particles is in the range of 50 to 90% by weight. The magnetic recording medium having such constitution is excellent in running endurance and running properties and shows high electromagnetic conversion characteristics.

Magnetic recording medium having a magnetic layer containing abrasive

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Tokyo, Japan

Hiroyuki Miyabara