106results about How to "Improve rate characteristics" patented technology

Provided is a cathode active material for a lithium secondary battery, which can achieve both of excellent rate characteristic and practically sufficient durability (cycle characteristic) in the lithium secondary battery. The cathode active material for a lithium secondary battery includes therein pores. A particle or film of the cathode active material for a lithium secondary battery has formed therein a large number of pores. The inner wall of each of such pores is coated with a conductive film.

Disclosed is an anode active material, comprising: (a) a carbonaceous material; and (b) a carbide coating layer partially or totally formed on a surface of the carbonaceous material, the carbide coating layer comprising at least one element selected from the group consisting of metals and metalloids. An anode obtained by using the anode active material and an electrochemical device comprising the anode are also disclosed. The carbonaceous material comprises a coating layer of metal-/metalloid-carbide obtained by treating it at high temperature under inert atmosphere, wherein the coating layer has increased interfacial boding force to the carbonaceous material and thus shows minimized reactivity to lithium. The carbonaceous material as anode active material can minimize the irreversible anode capacity needed for the formation of an SEI film during the first charge/discharge cycle, thereby providing high capacity, high efficiency and significantly improved anode qualities.

A non-aqueous electrolyte secondary battery comprising: a positive electrode comprising a positive electrode current collector and a positive electrode material mixture layer formed thereon; a negative electrode comprising a negative electrode current collector and a negative electrode material mixture layer formed thereon; and a non-aqueous electrolyte, characterized in that at least one of said positive and negative electrodes has a positive temperature coefficient of resistance; and said non-aqueous electrolyte contains an additive which is stable in the normal operating voltage range of said battery and is able to polymerize at the voltage exceeding the maximum value of said operating voltage range.

The present invention provided a positive electrode active material for a lithium secondary battery including lithium cobalt oxide particles. The lithium cobalt oxide particles include lithium deficient lithium cobalt oxide having Li/Co molar ratio of less than 1, belongs to an Fd-3m space group, and having a cubic crystal structure, in surface of the particle and in a region corresponding to a distance from 0% to less than 100% from the surface of the particle relative to a distance (r) from the surface to the center of the particle. In the positive electrode active material for a lithium secondary battery according to the present invention, the intercalation and deintercalation of lithium at the surface of a particle may be easy, and the output property and rate characteristic may be improved when applied to a battery.

A lithium ion secondary battery comprising a positive electrode, a non-aqueous electrolyte, a separator and a negative electrode comprising a carbon material capable of charging and discharging lithium ions, said negative electrode containing at least one type of graphite material which satisfies the following conditions (a) and (b): (a) a graphite material falling within a defined region in the relation between its particle size and specific surface area; (b) in Raman spectroscopic analysis, the ratio of the strength of the peak existing in the region of 1,350-1,370 cm-1 (IB) to the strength of the peak existing in the region of 1,570-1,620 cm-1 (IA), which is represented by an R value (IB/IA), is 0.001 to 0.2. This battery has high capacity and is also excellent in rapid charge/discharge characteristics, flatness of charge/discharge potential and cycle performance.

A non-aqueous secondary battery includes a positive electrode 1, a negative electrode 2, a separator 3, and a non-aqueous electrolyte solution, wherein the non-aqueous electrolyte solution contains an aromatic compound in an amount of 2 to 15% by mass with respect to a total mass of the electrolyte solution, the separator 3 has a MD direction and a TD direction, a heat shrinkage at 150° C. in the TD direction of 30% or less, a thickness of 5 to 20 mum, and an air permeability of 500 seconds/100 ml or less. Because of this, a non-aqueous secondary battery can be obtained, which is excellent in safety and high rate characteristics and is operated stably even at a high temperature. Furthermore, by allowing the non-aqueous secondary battery of the present invention to be contained in electronic equipment, the reliability of the electronic equipment can be enhanced. Furthermore, a prismatic or laminate-shaped non-aqueous secondary battery is pressed in its direction to be contained in electronic equipment, whereby the safety of the electronic equipment can be enhanced.

The present invention provides a positive electrode active material for a lithium secondary battery including a core including first lithium cobalt oxide, and a surface modifying layer positioned on a surface of the core. The surface modifying layer includes a lithium compound discontinuously distributed on the surface of the core, and second lithium cobalt oxide distributed while making a contact with or adjacent to the lithium compound, with a Li/Co molar ratio of less than 1. The positive electrode active material according to the present invention forms a lithium deficient structure in the positive electrode active material of lithium cobalt oxide and changes two-dimensional lithium transport path into three-dimensional path. The transport rate of lithium ions may increase when applied to a battery, thereby illustrating improved capacity and rate characteristic without decreasing initial capacity.

The present invention relates to a rechargeable lithium ion battery having an electrode plate with a high active material density and high electrolyte permeability. Upon producing the rechargeable lithium ion battery, hollow resin particles that can be collapsed by rolling are incorporated in a positive electrode mixture layer or a negative electrode mixture layer before the electrode mixture layer is rolled. The hollow resin particles are collapsed in the course of rolling the positive electrode mixture layer or the negative electrode mixture layer, so that the active material density can be easily increased. Further, the collapsed resin particles form unevenness on the surface of the electrode plate and also form open pores in the electrode plate, so that electrolyte permeability can be enhanced. As a result, the discharge capacity and rate characteristics of rechargeable lithium ion batteries can be increased.

An object of the present invention is to provide a multi-component system (cobalt-nickel-manganese three-component system) cathode active material for a lithium secondary battery which has improved characteristic as compared with conventional lithium secondary batteries and a layered rock salt structure. A plate-like particle or a film for a lithium secondary battery cathode active material is represented by the following general formula:

Li_p(Co_x,Ni_y,Mn_z)O₂  General formula

• • (wherein 0.97≦p≦1.07, 0.1<x≦0.4, 0.3<y≦0.5, 0.1<z≦0.5, x+y+z=1)

The particle or the film contains cobalt and lithium and has a layered rock salt structure. The (003) plane is oriented so as to intersect the plate surface of the particle or film.

A lithium ion secondary battery includes a positive electrode capable of absorbing and desorbing lithium ion, a negative electrode capable of absorbing and desorbing lithium ion, a porous film interposed between the positive electrode and the negative electrode, and a non-aqueous electrolyte: the porous film being adhered to a surface of at least one of the positive electrode and the negative electrode; the porous film including a filler and a resin binder; the resin binder content in the porous film being 1.5 to 8 parts by weight per 100 parts by weight of the filler; and the resin binder including an acrylonitrile unit, an acrylate unit, or a methacrylate unit.

An object of the present invention is to provide a separator maintaining high rate characteristics and enabling suppression of short circuit. The object is achieved by a separator comprising a substrate having an inner surface and an outer surface, and inorganic particles presented on the outer surface and the inner surface of the substrate, wherein the substrate has a porosity of 55% or more and a mean flow pore size of 30 μm or less, the inorganic particles have an average particle size of 1.0 to 4.0 μm, and the inorganic particles comprises 40% by volume or less of particles having a particle size of 1.0 μm or less and 30 to 75% by volume of particles having a particle size of 2.0 μm or more.

Disclosed is a positive electrode active material for a nonaqueous electrolyte secondary battery containing at least a lithium-transition metal composite oxide of a spinel structure, in which at least one kind of element which may become tetravalent exists on at least a surface of the lithium-transition metal composite oxide, and concentration of the element which may become tetravalent on the surface of the lithium-transition metal composite oxide is higher than concentration of the element which may become tetravalent inside the lithium-transition metal composite oxide. A use of this positive electrode active material can improve cycle characteristics and high rate characteristics without reducing the charge-discharge capacity of the lithium-transition metal composite oxide.

Disclosed are an electrode active material including lithium metal oxide particles and a polydopamine layer formed on a surface of each of the lithium metal oxide particles, and a lithium secondary battery including the same.

An object of the present invention is to provide a lithium secondary battery which has improved capacity, durability, and rate characteristic as compared with conventional lithium secondary batteries. A plate-like particle or a film for a lithium secondary battery cathode active material is represented by the following general formula:

General formula: Li_p(Ni_x,Co_y,Al_z)O₂

(wherein 0.9≦p≦1.3, 0.6<x≦0.9, 0.1<y≦0.3, 0≦z≦0.2, x+y+z=1)

The particle or the film contains cobalt and lithium and has a layered rock salt structure. The (003) plane is oriented so as to intersect the plate surface of the particle or film.

Materials having charge-storing properties and made variously of dipyridine-fused benzoquinones of formula (1) below or derivatives thereof, dipyridine-fused benzoquinones of formula (4) below or derivatives thereof, or dipyridine-fused benzoquinone skeleton-containing polymers are provided.

In the formulas, Ar¹ and Ar² are each independently a pyridine ring that forms together with two carbon atoms on a benzoquinone skeleton, or a derivative thereof. When used as electrode active materials, these charge storage materials are capable of providing high-performance batteries possessing a high capacity, high rate characteristics and high cycle characteristics.

An active material contains a triclinic LiVOPO₄ crystal particle, while the crystal particle has a spherical form and an average particle size of 20 to 200 nm.

An object of the present invention is to provide a current collector which includes an aluminum alloy foil for electrode current collector, with high electrical conductivity and high strength after a drying process performed after application of an active material. According to the present invention, provided is a current collector including a conductive substrate and a resin layer provided on one side or both sides of the conductive substrate, wherein: the conductive substrate is an aluminum alloy foil containing 0.03 to 1.0 mass % (hereinafter mass % is referred to as %) of Fe, 0.01 to 0.3% of Si, 0.0001 to 0.2% of Cu, with the rest being Al and unavoidable impurities, an aluminum alloy foil after a final cold rolling having a tensile strength of 180 MPa or higher, a 0.2% yield strength of 160 MPa or higher, and an electrical conductivity of 58% IACS or higher; an aluminum alloy foil after performing a heat treatment at 120° C. for 24 hours, at 140° C. for 3 hours, or at 160° C. for 15 minutes after the final cold rolling having a tensile strength of 170 MPa or higher, and a 0.2% yield strength of 150 MPa or higher; the resin layer includes a resin containing an acryl-based resin, a soluble nitrocellulose-based resin or a chitosan-based resin, and a conductive material; and a water contact angle of the resin layer surface measured by θ/2 method in a thermostatic chamber at 23° C. is 30 degrees or more and 105 degrees or less when the resin is the acryl-based resin, 100 degrees of more and 110 degrees or less when the resin is the soluble nitrocellulose-based resin, and 20 degrees or more and 50 degrees or less when the resin is the chitosan-based resin.