Abstract: According to one embodiment, a memory system includes a nonvolatile memory and a memory controller. The nonvolatile memory includes blocks each including memory cells. The memory controller is configured to control access to the nonvolatile memory. The memory controller is configured to: set a first block, among the plurality of blocks, to be written in a first mode, the first mode being a mode in which data of a first number of bits is written into the memory cell, and set a plurality of second blocks, among the plurality of blocks, to be written in a second mode, the second mode being a mode in which data of a second number of bits is written into the memory cell, the second number being larger than the first number; acquire access information related to the second blocks; and change a writing mode of the first block which has been set in the first mode to the second mode when a first condition of the second blocks based on the access information is satisfied.

Abstract: An organic sulfur material comprising carbon, hydrogen, oxygen, and sulfur as constituent elements, and having peaks in the vicinity of 482 cm?1, 846 cm?1, 1066 cm?1, 1279 cm?1, and 1442 cm?1 in a Raman spectrum detected by Raman spectroscopy, the peak in the vicinity of 1442 cm?1 being most intense, has a high capacity and high heat resistance, although a liquid organic starting material is used.

Abstract: An object of the present invention is to provide a novel sulfur-based positive-electrode active material which can largely improve cyclability of a lithium-ion secondary battery, a positive electrode comprising the positive-electrode active material and a lithium-ion secondary battery comprising the positive electrode. The sulfur-based positive-electrode active material is one comprising: a carbon skeleton derived from a polymer composed of a monomer unit having at least one hetero atom-containing moiety, and sulfur incorporated into the carbon skeleton as the carbon skeleton is formed from the polymer by heat treatment.

Abstract: 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?1, 1250 cm?1, 1440 cm?1, and 1900 cm?1 in a Raman spectrum detected by Raman spectroscopy. The peak in the vicinity of 1440 cm?1 is 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 cm?1 or 1066 cm?1.

Abstract: An object of the present invention is to provide a novel positive electrode which is produced using a rubber being an inexpensive material and is capable of enhancing a charge and discharge capacity and cyclability of a lithium-ion secondary battery, and the lithium-ion secondary battery composed of the positive electrode. In the lithium-ion secondary battery, the positive electrode comprises a current collector and an electrode layer formed on a surface of the current collector, the electrode layer comprises an active material, an electrically-conductive additive and a thermosetting resin binder subjected to thermosetting, and the active material comprises a sulfur-based positive-electrode active material prepared by heat-treating a starting material comprising a rubber and sulfur under a non-oxidizing atmosphere.

Abstract: An object of the present invention is to provide a novel sulfur-based positive-electrode active material which can largely improve cyclability of a lithium-ion secondary battery, a positive electrode comprising the positive-electrode active material and a lithium-ion secondary battery comprising the positive electrode. The sulfur-based positive-electrode active material is one comprising: a carbon skeleton derived from a polymer composed of a monomer unit having at least one hetero atom-containing moiety, and sulfur incorporated into the carbon skeleton as the carbon skeleton is formed from the polymer by heat treatment.

Abstract: An object of the present invention is to provide a novel positive electrode which is produced using a rubber being an inexpensive material and is capable of enhancing a charge and discharge capacity and cyclability of a lithium-ion secondary battery, and the lithium-ion secondary battery composed of the positive electrode. In the lithium-ion secondary battery, the positive electrode comprises a current collector and an electrode layer formed on a surface of the current collector, the electrode layer comprises an active material, an electrically-conductive additive and a thermosetting resin binder subjected to thermosetting, and the active material comprises a sulfur-based positive-electrode active material prepared by heat-treating a starting material comprising a rubber and sulfur under a non-oxidizing atmosphere.

Abstract: An object of the present invention is to provide a positive-electrode active material comprising a carbon-sulfur structure which has Raman shift peaks at around 500 cm?1, at around 1,250 cm?1 and at around 1,450 cm?1 in a Raman spectrum, and by using the positive-electrode active material, it is possible to greatly improve cycling characteristics of a lithium-ion secondary battery.

Abstract: 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?1, 1250 cm?1, 1440 cm?1, and 1900 cm?1 in a Raman spectrum detected by Raman spectroscopy. The peak in the vicinity of 1440 cm?1 is 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 cm?1 or 1066 cm?1.

Abstract: An organic sulfur material comprising carbon, hydrogen, oxygen, and sulfur as constituent elements, and having peaks in the vicinity of 482 cm?1, 846 cm?1, 1066 cm?1, 1279 cm?1, and 1442 cm?1 in a Raman spectrum detected by Raman spectroscopy, the peak in the vicinity of 1442 cm?1 being most intense, has a high capacity and high heat resistance, although a liquid organic starting material is used.

Abstract: To provide a lithium ion secondary battery capable of suppressing thermal run-away when internal short circuiting occurs. The lithium ion secondary battery includes: a positive electrode including a current collector, a positive electrode active material layer that is formed on the current collector and that contains a lithium-containing complex oxide having a layered rock salt structure and being represented by general formula: LiaNibCocMndDeOf (0.2?a?1; b+c+d+e=1; 0?e<1; D is at least one element selected from Li, Fe, Cr, Cu, Zn, Ca, Mg, S, Si, Na, K, and Al; 1.7?f?2.1), and a thermal run-away suppressing layer formed on the positive electrode active material layer and containing a lithium transition metal silicate; and a negative electrode including a negative electrode active material. A ratio of the mass of the lithium-containing complex oxide with respect to the mass of the lithium transition metal silicate in the positive electrode is not lower than 1.5.

Abstract: An object of the present invention is to provide a novel positive electrode which is produced using a rubber being an inexpensive material and is capable of enhancing a charge and discharge capacity and cyclability of a lithium-ion secondary battery, and the lithium-ion secondary battery composed of the positive electrode. In the lithium-ion secondary battery, the positive electrode comprises a current collector and an electrode layer formed on a surface of the current collector, the electrode layer comprises an active material, an electrically-conductive additive and a thermosetting resin binder subjected to thermosetting, and the active material comprises a sulfur-based positive-electrode active material prepared by heat-treating a starting material comprising a rubber and sulfur under a non-oxidizing atmosphere.

Abstract: A lithium-ion secondary battery of the present invention comprises a positive electrode including a positive electrode active material composite formed by compositing a lithium silicate-based material and a carbon material, a negative electrode including a negative electrode active material containing a silicon, and an electrolyte. The lithium-ion secondary battery satisfies 0.8<B/A<1.2, where A is irreversible capacity of the positive electrode and B is irreversible capacity of the negative electrode.

Abstract: An object of the present invention is to provide a novel sulfur-based positive-electrode active material which can largely improve cyclability of a lithium-ion secondary battery, a positive electrode comprising the positive-electrode active material and a lithium-ion secondary battery comprising the positive electrode. The sulfur-based positive-electrode active material is one comprising: a carbon skeleton derived from a polymer composed of a monomer unit having at least one hetero atom-containing moiety, and sulfur incorporated into the carbon skeleton as the carbon skeleton is formed from the polymer by heat treatment.

Abstract: Provided are a positive electrode active material for a sodium ion secondary battery, and a positive electrode and a sodium ion secondary battery using the material. The positive electrode active material for a sodium ion secondary battery comprises a lithium sodium-based compound containing lithium (Li), sodium (Na), iron (Fe), and oxygen (O).

Abstract: An object of the present invention is to provide a positive-electrode active material comprising a carbon-sulfur structure which has Raman shift peaks at around 500 cm?1, at around 1,250 cm?1 and at around 1,450 cm?1 in a Raman spectrum, and by using the positive-electrode active material, it is possible to greatly improve cycling characteristics of a lithium-ion secondary battery.

Abstract: To provide a lithium ion secondary battery capable of suppressing thermal run-away when internal short circuiting occurs. The lithium ion secondary battery includes: a positive electrode including a current collector, a positive electrode active material layer that is formed on the current collector and that contains a lithium-containing complex oxide having a layered rock salt structure and being represented by general formula: LiaNibCocMndDeOf (0.2?a?1; b+c+d+e=1; 0?e<1; D is at least one element selected from Li, Fe, Cr, Cu, Zn, Ca, Mg, S, Si, Na, K, and Al; 1.7?f?2.1), and a thermal run-away suppressing layer formed on the positive electrode active material layer and containing a lithium transition metal silicate; and a negative electrode including a negative electrode active material. A ratio of the mass of the lithium-containing complex oxide with respect to the mass of the lithium transition metal silicate in the positive electrode is not lower than 1.5.

Abstract: Provided is a novel lithium silicate-based material useful as a positive electrode material for lithium ion secondary battery. The lithium silicate-based compound is represented by Li1.5FeSiO4.25. The lithium silicate-based compound is a compound including: lithium (Li); iron (Fe); silicon (Si); and oxygen (O), and expressed by a composition formula, Li1+2?FeSiO4+??c (?0.25???0.25, 0?c?0.5). The lithium silicate-based compound, of which iron (Fe) is trivalent, exerts a remarkable chemical stability as compared to Li2FeSiO4.

Abstract: A production process for lithium-silicate-based compound according to the present invention is characterized in that: a lithium-silicate compound being expressed by Li2SiO3 is reacted with a transition-metal-element-containing substance including at least one member being selected from the group consisting of iron and manganese at 550° C. or less within a molten salt including at least one member being selected from the group consisting of alkali-metal nitrates as well as alkali-metal hydroxides in an atmosphere in the presence of a mixed gas including carbon dioxide and a reducing gas. In accordance with the present invention, it is possible to produce lithium-silicate-based materials, which are useful as a positive-electrode active material for lithium-ion secondary battery, and the like, at low temperatures by means of relatively easy means.

Abstract: The present invention is one which provides a production process for lithium-silicate-system compound, the production process being characterized in that: a lithium-silicate compound being expressed by Li2SiO3 is reacted with a substance including at least one member of transition-metal elements that is selected from the group consisting of iron and manganese at 400-650° C. in a molten salt of a carbonate mixture comprising lithium carbonate and at least one member of alkali-metal carbonates that is selected from the group consisting of potassium carbonate, sodium carbonate, rubidium carbonate and cesium carbonate in a mixed-gas atmosphere including carbon dioxide and a reducing gas; and a positive-electrode active material for lithium-ion secondary battery that comprises a lithium-silicate-system compound being obtained by the aforesaid process.