National Institute of Advanced Industrial Science and Technology

Other

Agency of Industrial Science and Technology Ministry of International

Agency of Industrial Science & Technology, Ministry of International Trade & Industry

Nat'l Institute of Advanced Industrial Science . . .

Tomonari Takeuchi

Kuniaki Tatsumi

Hiroyuki Kageyama

Hikari Sakaebe

Mitsuharu Tabuchi

Atsushi Sakuda

Tetsuo Sakai

Kazuaki Ado

Hiromitsu Misawa

Toshikatsu Kojima

Tatsuya Nakamura

Osamu Nakamura

Hiroshi Senoh

Noboru Taguchi

Yoko Nabeshima

Yuko Oka

Elisabeth Betourne

The present invention provides an organic sulfur material comprising carbon, hydrogen, and sulfur as constituent elements, and having peaks in the vicinity of 480 cm, 1250 cm, 1440 cm, and 1900 cmin a Raman spectrum detected by Raman spectroscopy. The peak in the vicinity of 1440 cmis the most intense peak. This organic sulfur material, which is produced by using a liquid organic starting material, achieves high capacity. This organic sulfur material preferably does not have peaks in the vicinity of 846 cmor 1066 cm.

Carbon sulfur material and method for producing same

A composite containing phosphorus, lithium, iron, sulfur, and carbon as constituent elements wherein lithium sulfide (LiS) is present in an amount of 90 mol % or more, and wherein the crystallite size calculated from the half-width of a diffraction peak based on the (111) plane of LiS as determined by X-ray powder diffraction measurement is 80 nm or less. The composite exhibits a high capacity (in particular, a high discharge capacity) useful as an electrode active material for a lithium-ion secondary battery (in particular, a cathode active material for a lithium-ion secondary battery), without the need for stepwise pre-cycling treatment.

Lithium-iron-phosphorus-sulfur-carbon composite and method for producing same

The main object is to provide a novel material with excellent charge and discharge characteristics, such as a high utilization rate of a positive electrode, a high capacity, and good cycle characteristic, in which the material is a compound containing as the major component lithium sulfide useful as a cathode active material for lithium secondary batteries. The invention provides a lithium sulfide-iron-carbon composite containing lithium, iron, sulfur and carbon as constituent elements, with lithium sulfide (LiS), as the main phase, having a crystallite size of 50 nm or less as calculated from the half width of the diffraction peak based on the (111) plane of LiS as determined by X-ray powder diffraction.

Lithium sulfide-iron-carbon complex

The sulfide of the present invention comprises an amorphous (lithium) niobium sulfide having an average composition represented by formula (1): LiNbS(wherein 0&#x2264;k1&#x2264;5; 3&#x2264;n1&#x2264;10; and when n1&#x2265;3.5, k1&#x2264;0.5), or an amorphous (lithium) titanium niobium sulfide having an average composition represented by formula (2): LiTiNbS(wherein 0&#x2264;k2&#x2264;5; 0&#x3c;m2&#x3c;1; 2&#x2264;n2&#x2264;10; and when n2&#x2265;3.5, k2&#x2264;1.5). The sulfide of the present invention is a material that is useful as a cathode active material for lithium batteries, such as lithium primary batteries, lithium secondary batteries, and lithium ion secondary batteries, and has a high charge-discharge capacity, high electrical conductivity, and excellent charge-discharge performance.

Amorphous (lithium) niobium sulfide or (lithium) titanium niobium sulfide

The present invention provides a novel lithium titanium sulfide, lithium niobium sulfide, or lithium titanium niobium sulfide that contains a sulfide containing lithium, titanium and/or niobium, and sulfur as constituent elements, and that has excellent charge-discharge performance (especially excellent charge-discharge capacity and charge-discharge potential) useful as a cathode active material or the like for lithium batteries, such as metal lithium secondary batteries or lithium-ion secondary batteries. Particularly preferred are, for example, (1) lithium titanium sulfide containing lithium, titanium, and sulfur as constituent elements and having a cubic rock salt crystal structure, (2) lithium niobium sulfide containing lithium, niobium, and sulfur as constituent elements and having a diffraction peak at a specific position in an X-ray diffractogram, and (3) lithium titanium niobium sulfide containing lithium, titanium, niobium, and sulfur as constituent elements and having a diffraction peak at a specific position in an X-ray diffractogram.

Lithium titanium sulfide, lithium niobium sulfide, and lithium titanium niobium sulfide

The present invention provides a process for producing a lithium sulfide-carbon composite, the process comprising placing a mixture of lithium sulfide and a carbon material having a specific surface area of 60 m/g or more in an electrically-conductive mold in a non-oxidizing atmosphere, and applying a pulsed direct current to the mold while pressurizing the mixture in a non-oxidizing atmosphere, thereby subjecting the lithium sulfide and the carbon material to heating reaction; and a lithium sulfide-carbon composite obtained by this process, the composite having a carbon content of 15 to 70 weight %, and a tap density of 0.4 g/cmor more when the carbon content is 30 weight % or more, or a tap density of 0.5 g/cmor more when the carbon content is less than 30 weight %. The present invention can improve the electronic conductivity of lithium sulfide, which is expected to be put into practical use as a high-capacity positive electrode active material, so as to further enhance the performance of lithium sulfide as a positive electrode active material for lithium ion secondary batteries.

Lithium sulfide-carbon complex, process for producing the complex, and lithium ion secondary battery utilizing the complex

The present invention provides a process for producing a composite of metal sulfide and metal oxide obtained by dispersing a metal sulfide, which is nickel sulfide, copper sulfide, iron sulfide or a mixture thereof, in a metal salt-containing aqueous solution, and depositing metal salt on the metal sulfide by drying the aqueous solution; and heat-treating the metal sulfide comprising a metal salt deposited thereon at 400 to 900&#xb0; C. in a sulfur-containing atmosphere. Also disclosed is a composite obtained by the aforementioned process, comprising a metal sulfide having a surface partially covered with a metal oxide. The composite of the present invention has improved cycle characteristics while maintaining a high charge/discharge capacity and excellent electrical conductivity inherently possessed by metal sulfide, which is usable as a material having a high theoretical capacity and excellent electrical conductivity when used as a positive-electrode material for a lithium secondary battery.

Composite of metal sulfide and metal oxide and process for producing the composite

The present invention provides a production process of a metal sulfide, which includes placing a metal component and sulfur in a conductive container, and applying a pulsed direct current to the container in a non-oxidizing atmosphere to cause the metal component to react with sulfur, and also provides a metal sulfide obtained by the process and represented by a composition formula: MS, wherein M is at least one member selected from the group consisting of Ni, Cu, Fe, and Co, and 1&#x3c;x&#x2266;2. The present invention is capable of easily producing a metal sulfide with a high proportion of sulfur atoms, which is expected to exhibit excellent properties as a positive-electrode active material for a high capacity lithium secondary battery.

Process for producing metal sulfide

The present invention provides a lithium manganese-based composite oxide represented by the compositional formula: Li(MnFeTi)O, wherein 0&#x3c;x&#x3c;&#x2153;, 0&#x2266;m&#x2266;0.75, 0.01&#x2266;n&#x2266;0.75, and 0.01&#x2266;m+n&#x3c;1, and comprising a crystal phase of layered rock-salt type structure. The composite oxide is capable of maintaining an average discharge voltage of 3 V or more over long charge/discharge cycles. The composite oxide can be prepared using lower-cost starting materials, and exhibits improved charge/discharge characteristics over conventional low-cost positive electrode materials.

Lithium manganese-based composite oxide and method for preparing the same

The invention provides a lithium-manganese-based composite oxide containing Ti and Ni, which is represented by the compositional formula: Li(MnNiTi)O, wherein 0&#x3c;x&#x2266;0.33, 0.05&#x3c;m&#x3c;0.3, and 0.3&#x3c;n&#x3c;0.5, and includes a crystal phase of layered rock-salt type structure. The composite oxide is a novel material that is capable of maintaining an average discharge voltage of 3 V or more over long charge/discharge cycles, while providing a discharge capacity equal to or higher than those of lithium-cobalt-oxide-based positive electrode materials, and that can be prepared using starting materials that are inexpensive and less limited as natural resources, while exhibiting improved charge/discharge characteristics over known low-cost positive electrode materials.

Lithium-manganese-based composite oxide containing titanium and nickel

Tin-containing granular magnetic oxide particles and process for producing the same

A sintered lithium titaniumphosphate is produced by subjecting the powder of a mixture consisting of a Li source, a Ti source, and a P source to spark plasma sintering under an increased pressure.

Method for production of sintered lithium titaniumphosphate and sintered pellets obtained by the method

A high sodium ion conducting inorganic composite solid electrolyte obtained by mixing Na.sub.4 Zr.sub.2 Si.sub.3 O.sub.12 with titanium oxide and sintering the resultant mixture and a method for the production of a high sodium ion conducting inorganic composite solid electrolyte, consisting essentially of the steps of mixing Na.sub.4 Zr.sub.2 Si.sub.3 O.sub.12 with titanium oxide and sintering the resultant mixture.

Growing community of inventors

Ikeda, Japan

Tomonari Takeuchi