A positive electrode plate for secondary battery, a secondary battery, a battery module, a battery pack, and an apparatus are provided. Some embodiments provide a positive electrode plate for secondary battery, where the positive electrode plate includes a positive electrode current collector and a positive electrode active substance layer located on a surface of the positive electrode current collector, the positive electrode active substance layer includes a positive electrode active substance, the positive electrode active substance contains a first lithium-nickel transition metal oxide and a second lithium-nickel transition metal oxide, the first lithium-nickel transition metal oxide contains a first matrix and a first coating layer located on a surface of the first matrix, the first matrix is secondary particles, and the second lithium-nickel transition metal oxide is single crystal particles or particles with quasi-single crystal morphology.

Provided is a lithium ion secondary battery including Li.sub.4Ti.sub.5O.sub.12 particles in a negative electrode active material layer and having both high heat generation suppressing performance during overcharging, and high storage stability in a high SOC region. The lithium ion secondary battery herein disclosed includes a positive electrode, a negative electrode, and a nonaqueous electrolyte. The positive electrode has a positive electrode active material layer. The positive electrode active material layer includes Li.sub.3PO.sub.4 as a secondary material. The negative electrode has a negative electrode active material layer. The negative electrode active material layer includes Li.sub.4Ti.sub.5O.sub.12 as a secondary material. The Li.sub.3PO.sub.4 content in the positive electrode active material layer is 0.5 mass % or more and 5.0 mass % or less. The Li.sub.4Ti.sub.5O.sub.12 content in the negative electrode active material layer is 0.5 mass % or more and 5.0 mass % or less.

Provided is a lithium ion secondary battery including Li.sub.4Ti.sub.5O.sub.12 particles in a negative electrode active material layer and having both high heat generation suppressing performance during overcharging, and high storage stability in a high SOC region. The lithium ion secondary battery herein disclosed includes a positive electrode, a negative electrode, and a nonaqueous electrolyte. The positive electrode has a positive electrode active material layer. The positive electrode active material layer includes Li.sub.3PO.sub.4 as a secondary material. The negative electrode has a negative electrode active material layer. The negative electrode active material layer includes Li.sub.4Ti.sub.5O.sub.12 as a secondary material. The Li.sub.3PO.sub.4 content in the positive electrode active material layer is 0.5 mass % or more and 5.0 mass % or less. The Li.sub.4Ti.sub.5O.sub.12 content in the negative electrode active material layer is 0.5 mass % or more and 5.0 mass % or less.

A cathode for a lithium secondary battery according to embodiments of the present invention includes a cathode current collector, and a cathode active material layer formed on the cathode current collector. The cathode active material layer includes first lithium metal oxide particles each having a secondary particle shape in which primary particles are aggregated and second lithium metal oxide particles each having a single particle shape. A cross-section of the cathode active material layer from an SEM satisfies Equations 1 and 2.

A cathode slurry for a lithium secondary battery according to exemplary embodiments may include a cathode active material including lithium metal oxide particles, a binder, a dispersion medium, and at least one of a multivalent carboxylic acid compound and a salt of the multivalent carboxylic acid compound. A total amount of the multivalent carboxylic acid compound and the salt of the multivalent carboxylic acid compound in the cathode slurry may be 0.01 to 0.05 wt. parts based on 100 wt. parts of the lithium metal oxide particles.

A cathode slurry for a lithium secondary battery according to exemplary embodiments may include a cathode active material including lithium metal oxide particles, a binder, a dispersion medium, and at least one of a multivalent carboxylic acid compound and a salt of the multivalent carboxylic acid compound. A total amount of the multivalent carboxylic acid compound and the salt of the multivalent carboxylic acid compound in the cathode slurry may be 0.01 to 0.05 wt. parts based on 100 wt. parts of the lithium metal oxide particles.

In this disclosure, a battery is provided. The electrode includes an electrode current collector and an electrode active material layer, wherein the electrode active material layer includes a single crystal electrode active material and a polycrystalline electrode active material, and the single crystal electrode active material and the polycrystalline electrode active material are each a lithium transition metal composite oxide, and the electrode active material layer includes a first layer including a first surface opposite to the electrode current collector and a second layer including a second surface on the electrode current collector side, wherein the first layer includes the single crystal electrode active material as a main component of the electrode active material, and the second layer includes the polycrystalline electrode active material as a main component of the electrode active material.

In this disclosure, a battery is provided. The electrode includes an electrode current collector and an electrode active material layer, wherein the electrode active material layer includes a single crystal electrode active material and a polycrystalline electrode active material, and the single crystal electrode active material and the polycrystalline electrode active material are each a lithium transition metal composite oxide, and the electrode active material layer includes a first layer including a first surface opposite to the electrode current collector and a second layer including a second surface on the electrode current collector side, wherein the first layer includes the single crystal electrode active material as a main component of the electrode active material, and the second layer includes the polycrystalline electrode active material as a main component of the electrode active material.

A novel electrode is provided. A novel power storage device is provided. A conductor having a sheet-like shape is provided. The conductor has a thickness of greater than or equal to 800 nm and less than or equal to 20 μm. The area of the conductor is greater than or equal to 25 mm.sup.2 and less than or equal to 10 m.sup.2. The conductor includes carbon and oxygen. The conductor includes carbon at a concentration of higher than 80 atomic % and oxygen at a concentration of higher than or equal to 2 atomic % and lower than or equal to 20 atomic %.

A novel electrode is provided. A novel power storage device is provided. A conductor having a sheet-like shape is provided. The conductor has a thickness of greater than or equal to 800 nm and less than or equal to 20 μm. The area of the conductor is greater than or equal to 25 mm.sup.2 and less than or equal to 10 m.sup.2. The conductor includes carbon and oxygen. The conductor includes carbon at a concentration of higher than 80 atomic % and oxygen at a concentration of higher than or equal to 2 atomic % and lower than or equal to 20 atomic %.