Sony Corporation

Other

Sumitomo Metal Industries, Inc.

Matsushita Electric Industrial Co., Ltd.

Honda Motor Co., Ltd.

Masaru Abe

Noriyuki Negi

Hideya Kaminaka

Kazuhito Kamei

Koji Moriguchi

Atsuo Omaru

Masayuki Nagamine

Mitsuhara Yonemura

Harunari Shimamura

Yoshiaki Nitta

Kazuhiro Okamura

Mitsuharu Yonemura

Kazuhiko Adachi

Takashi Katsurai

Tadao Nishiyama

A high-performance stainless steel sheet which has a high strength which is optimal for a gasket for use in high-performance engines of automobiles and motorcycles and which also has excellent workability and fatigue properties and a method for its manufacture are provided. At least in a region from the surface of the sheet up to 3 &#x3bc;m in the thickness direction, nitrogen compounds of at least 10 nm and at most 200 nm are present in an amount of at least 200 per 100 &#x3bc;m. The number of nitrogen compounds of at least 10 nm and at most 200 nm in a region from the sheet surface up to 3 &#x3bc;m in the thickness direction of the sheet is at least 2 times the number of nitrogen compounds of this size in the central portion of the sheet thickness.

Stainless steel sheet for a gasket

A graphite powder suitable for a negative electrode material of a lithium ion secondary battery which assures a high discharging capacity not lower than 320 mAh/g is to be manufactured at a lower cost. Specifically, a graphite powder containing 0.01 to 5.0 wt % of boron and having a looped closure structure at an end of a graphite c-planar layer on the surface of a powder, with the density of the interstitial planar sections between neighboring closure structures being not less than 100/&#x3bc;m and not more than 1500/&#x3bc;m, and with dbeing preferably not larger than 3.3650 &#x212b;, is manufactured by (1) heat-treating a carbon material pulverized at an elevated speed before or after carbonization for graphization at temperature exceeding 1500&#xb0; C. or by (2) heat-treating the carbon material pulverized before or after carbonization at a temperature exceeding 1500&#xb0; C. for graphization and subsequently further heat-treating the graphized material at a temperature exceeding a temperature of the oxidating heat treatment and the heat treatment in the inert gas.

Graphite powders suited for negative electrode material of lithium ion secondary battery

A graphite powder suitable for a negative electrode material of a lithium ion secondary battery which assures a high discharging capacity not lower than 320 mAh/g is to be manufactured at a lower cost. Specifically, a graphite powder containing 0.01 to 5.0 wt % of boron and having a looped closure structure at an end of a graphite c-planar layer on the surface of a powder, with the density of the interstitial planar sections between neighboring closure structures being not less than 100/&#x3bc;m and not more than 1500/&#x3bc;m, and with dbeing preferably not larger than 3.3650 &#x212b;, is manufactured by (1) heat-treating a carbon material pulverized at an elevated speed before or after carbonization for graphization at temperature exceeding 1500&#xb0; C. or by (2) heat-treating the carbon material pulverized before or after carbonization at a temperature exceeding 1500&#xb0; C. forgraphization and subsequently further heat-treating the graphized material at a temperature exceeding a temperature of the oxidating heat treatment and the heat treatment in the inert gas.

A negative electrode material for a nonaqueous electrolyte secondary battery having a high discharge capacity and a good cycle life is made from alloy particles having an average particle diameter of 0.1-50 &#x3bc;m and including Si phase grainsand a phase of a solid solution or an intermetallic compound of Si and other element selected from Group 2A elements, transition elements, Group 3B elements, and Group 4B elements from the long form periodic table (for example, an NiSiphaseand an [NiSi+NiSi] phase) at least partially enveloping the Si phase grains. 5-99 wt % of this material is Si phase grains. The alloy particles can be manufactured by rapid solidification (such as atomization or roller quenching) of a melt including Si and the other element, or by adhering the other element to Si powder by electroless plating or mechanical alloying and then performing heat treatment. Even if rapid solidification is carried out, a negative electrode material having a good discharge capacity and cycle life is obtained without heat treatment.

Process for manufacture of negative electrode material for a non-aqueous electrolyte secondary battery

A negative electrode material for a nonaqueous electrolyte secondary battery having a high discharge capacity and a good cycle life is made from alloy particles having an average particle diameter of 0.1-50 &mgr;m and including Si phase grains 40 and a phase of a solid solution or an intermetallic compound of Si and other element selected from Group 2A elements, transition elements, Group 3B elements, and Group 4B elements from the long form periodic table (for example, an NiSi phase 42 and an &lsqb;NiSi &plus;NiSi&rsqb; phase 41) at least partially enveloping the Si phase grains. 5-99 wt % of this material is Si phase grains. The alloy particles can be manufactured by rapid solidification (such as atomization or roller quenching) of a melt including Si and the other element, or by adhering the other element to Si powder by electroless plating or mechanical alloying and then performing heat treatment. Even if rapid solidification is carried out, a negative electrode material having a good discharge capacity and cycle life is obtained without heat treatment.

Negative electrode material for a non-aqueous electrolyte secondary battery and processes for its manufacture

A graphite powder suitable for a negative electrode material of a lithium ion secondary battery which assures a high discharging capacity not lower than 320 mAh/g is to be manufactured at a lower cost. Specifically, a graphite powder containing 0.01 to 5.0 wt % of boron and having a looped closure structure at an end of a graphite c-planar layer on the surface of a powder, with the density of the interstitial planar sections between neighboring closure structures being not less than 100/&mgr;m and not more than 1500/&mgr;m, and with d002 being preferably not larger than 3.3650 &angst;, is manufactured by (1) heat-treating a carbon material pulverized at an elevated speed before or after carbonization for graphization at temperature exceeding 1500&deg; C. or by (2) heat-treating the carbon material pulverized before or after carbonization at a temperature exceeding 1500&deg; C. for graphization and subsequently further heat-treating the graphized material at a temperature exceeding a temperature of the oxidating heat treatment and the heat treatment in the inert gas.

A graphite powder has surface closed-end structures in which the graphite c-plane layers of the graphite layer crystal lattices have closed-ends on the surface of the graphite powder by linking the ends of one or more pairs of the c-plane layers, leaving interstices which are open on the surface of the graphite. The number of open interstices is at least 100 and at most 1500 per micrometer in a c-axis direction of the graphite. Preferably, the graphite powder has a specific surface area of 1.0 m /g or less. Such a graphite powder can be prepared either by graphitizing a carbon material, which has been pulverized at a high speed under well-controlled conditions before and/or after the carbonization, or by subjecting a carbon material, which has been pulverized under well-controlled conditions before and/or after the carbonization, to graphitization and then to oxidative heat treatment at a temperature of 600-800&deg; C. and finally to heat treatment at a temperature of 800&deg; C. or higher in an inert gas. The graphite powder can be used to produce negative electrodes of lithium ion secondary batteries having a high discharge capacity of at least 320 mAh/g and a high charge/discharge coulombic efficiency of at least 90%.

Growing community of inventors

Hyogo, Japan

Masaru Abe