Showa Denko K.k.

Joseph Gaze

Akihiko Shirakawa

Fumiyoshi Ono

Takao Noda

Yoshiaki Yamauchi

Hisayuki Miki

Hiromitsu Sakai

Mineo Okuyama

Hideki Tomozawa

Tetsuo Sakurai

Masato Kobayakawa

Akira Bandoh

Syunji Horikawa

An object of the present invention is to provide a low-resistance n-type Group III nitride semiconductor layered structure having excellent flatness and few pits. The inventive n-type group III nitride semiconductor layered structure comprises a substrate and, stacked on the substrate, an n-type impurity concentration periodic variation layer comprising an n-type impurity atom higher concentration layer and an n-type impurity atom lower concentration layer, said lower concentration layer being stacked on said higher concentration layer.

N-type group III nitride semiconductor layered structure

A cathode electroactive material for use in lithium ion secondary cells, process for producing the material, and lithium ion secondary cells using the cathode electroactive material, wherein the electroactive material predominantly comprises an Li&#x2014;Mn composite oxide particles with the spinel structure and particles of the electroactive material have an average porosity of 15% or less, the porosity being calculated by employing the following equation:Porosity (%)=()&#xd7;100(wherein A represents a total cross-section area of pores included in a cross-section of one secondary particle, and B represents the cross-section area of one secondary particle), a tapping density of 1.9 g/ml or more, a size of crystallites of 400 &#x212b;&#x2013;960 &#x212b;, a lattice constant of 8.240 &#x212b; or less. The cathode electroactive material of the present invention is formed of particles which are dense and spherical and exhibit excellent packing characteristics to an electrode, and exhibit high initial capacity and capacity retention percentage at high temperature.

Cathode electroactive material, production method therefor and secondary cell

A cathode electroactive material for use in lithium ion secondary cells, process for producing the material, and lithium ion secondary cells using the cathode electroactive material, wherein the electroactive material predominantly comprises an Li&#x2014;Mn composite oxide particles with the spinel structure and particles of the electroactive material have an average porosity of 15% or less, the porosity being calculated by employing the following equation:Porosity (%)=()&#xd7;100(wherein A represents a total cross-section area of pores included in a cross-section of one secondary particle, and B represents the cross-section area of one secondary particle), a tapping density of 1.9 g/ml or more, a size of crystallites of 400 &#x212b;-960 &#x212b;, a lattice constant of 8.240 &#x212b; or less. The cathode electroactive material of the present invention is formed of particles which are dense and spherical and exhibit excellent packing characteristics to an electrode, and exhibit high initial capacity and capacity retention percentage at high temperature.

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Chiba, Japan

Joseph Gaze