The invention relates to a cathode material of lithium cobalt oxide for a lithium ion secondary battery and preparation methods and applications thereof. A cathode material comprises a core material and a coating layer, wherein the core material is Li.sub.xCo.sub.(1−y)A.sub.yO.sub.(2+z), wherein 1.0≦x≦1.11, 0≦y≦0.02, −0.2<z<0.2, and A is one or two or more selected from the group consisting of Al, Mg, Y, Zr and Ti, wherein the coating layer is Li.sub.aM.sub.bB.sub.cO.sub.d, wherein M is a lithium ion active metal element and one or two or more selected from the group consisting of Co, Ni, Mn and Mo, and B is an inactive element, and one or two or more selected from the group consisting of Al, Mg, Ti, Zr and Y, and 0.95<b+c<2.5, and the molar ratio of Li to the active metal element M is 0<a/b<1. The battery prepared by the cathode material has advantages of high capacity, high compacted density and excellent cycling stability etc., under high voltage.

The invention relates to a cathode material of lithium cobalt oxide for a lithium ion secondary battery and preparation methods and applications thereof. A cathode material comprises a core material and a coating layer, wherein the core material is Li.sub.xCo.sub.(1−y)A.sub.yO.sub.(2+z), wherein 1.0≦x≦1.11, 0≦y≦0.02, −0.2<z<0.2, and A is one or two or more selected from the group consisting of Al, Mg, Y, Zr and Ti, wherein the coating layer is Li.sub.aM.sub.bB.sub.cO.sub.d, wherein M is a lithium ion active metal element and one or two or more selected from the group consisting of Co, Ni, Mn and Mo, and B is an inactive element, and one or two or more selected from the group consisting of Al, Mg, Ti, Zr and Y, and 0.95<b+c<2.5, and the molar ratio of Li to the active metal element M is 0<a/b<1. The battery prepared by the cathode material has advantages of high capacity, high compacted density and excellent cycling stability etc., under high voltage.

Disclosed herein are a multilayer electrode and a lithium secondary battery including the same. The multilayer electrode includes an electrode current collector for transmitting electrons between an external wire and an electrode active material and three or more electrode mixture layers sequentially applied to the electrode current collector, wherein each of the electrode mixture layers includes an electrode active material and a conducting agent, and wherein the content of the conducting agent of one of adjacent electrode mixture layers that is relatively close to the current collector in the direction in which the electrode mixture layers are formed is higher than that of the conducting agent of the other of the adjacent electrode mixture layers that is relatively distant from the current collector.

A method for manufacturing a nonaqueous electrolyte secondary battery according to an embodiment of the present invention is a method for manufacturing a nonaqueous electrolyte secondary battery including a positive electrode plate and a negative electrode plate provided with a negative electrode mixture layer containing graphite and a silicon material and includes a step of applying positive electrode mixture slurry containing a lithium-transition metal composite oxide and polyvinylidene fluoride to a positive electrode current collector, a step of forming a positive electrode mixture layer by drying the positive electrode mixture slurry, and a step of heat-treating the positive electrode mixture layer. The temperature of heat treatment is preferably 160° C. to 350° C.

A method for manufacturing a nonaqueous electrolyte secondary battery according to an embodiment of the present invention is a method for manufacturing a nonaqueous electrolyte secondary battery including a positive electrode plate and a negative electrode plate provided with a negative electrode mixture layer containing graphite and a silicon material and includes a step of applying positive electrode mixture slurry containing a lithium-transition metal composite oxide and polyvinylidene fluoride to a positive electrode current collector, a step of forming a positive electrode mixture layer by drying the positive electrode mixture slurry, and a step of heat-treating the positive electrode mixture layer. The temperature of heat treatment is preferably 160° C. to 350° C.

Provided are a method for designing an electrode for a lithium secondary battery comprising measuring the electrical conductivity of an electrode with an alternating current to determine whether an electrical path in the electrode has been appropriately formed, and a method for manufacturing an electrode for a lithium secondary battery comprising the same. According to the present invention, it is possible to determine the content of a conductive agent in the electrode using the same.

Provided are a method for designing an electrode for a lithium secondary battery comprising measuring the electrical conductivity of an electrode with an alternating current to determine whether an electrical path in the electrode has been appropriately formed, and a method for manufacturing an electrode for a lithium secondary battery comprising the same. According to the present invention, it is possible to determine the content of a conductive agent in the electrode using the same.

There is provided a secondary battery including a cathode, an anode including an anode active material layer and a coating film, and an electrolytic solution. The anode active material layer includes a titanium-containing compound, and a surface of the anode active material layer is coated with the coating film. The electrolytic solution includes one or more of unsaturated cyclic carbonate esters. Porosity of a portion of the anode active material layer measured with use of a mercury intrusion technique is within a range from 30% to 50% both inclusive. The portion of the anode active material layer is cut together with a portion of the coating film from a surface of the coating film to a depth of 10 μm.

To increase capacity per weight of a power storage device, a particle includes a first region, a second region in contact with at least part of a surface of the first region and located on the outside of the first region, and a third region in contact with at least part of a surface of the second region and located on the outside of the second region. The first and the second regions contain lithium and oxygen. At least one of the first region and the second region contains manganese. At least one of the first and the second regions contains an element M. The first region contains a first crystal having a layered rock-salt structure. The second region contains a second crystal having a layered rock-salt structure. An orientation of the first crystal is different from an orientation of the second crystal.

To increase capacity per weight of a power storage device, a particle includes a first region, a second region in contact with at least part of a surface of the first region and located on the outside of the first region, and a third region in contact with at least part of a surface of the second region and located on the outside of the second region. The first and the second regions contain lithium and oxygen. At least one of the first region and the second region contains manganese. At least one of the first and the second regions contains an element M. The first region contains a first crystal having a layered rock-salt structure. The second region contains a second crystal having a layered rock-salt structure. An orientation of the first crystal is different from an orientation of the second crystal.