Positive electrode material for lithium-ion secondary batteries, positive electrode for lithium-ion secondary batteries, and method for manufacturing a positive electrode material for lithium-ion secondary batteries

Abstract

To improve both film formability and battery characteristics when the coating weight of a positive electrode active substance layer containing olivine-type lithium manganese iron phosphate is increased.SOLUTION: A positive electrode material for a lithium-ion secondary battery includes a granulated body 10 having: a core 11 composed of olivine-type lithium manganese iron phosphate represented by the general formula LiMnxFeyPO4 (x and y are numerical values satisfying x+y=1, 0<x<1, and 0<y<1 ); and a carbon coating 12 formed on a surface of the core 11. The core 11 has a structure in which primary particles of olivine-type lithium manganese iron phosphate are aggregated. The particle size of the primary particles is 100 nm or less. A pore volume in a pore size range of 2 nm or more and 300 nm or less in the granulated body 10 is 0.2 cm3 / g or less, and a carbon content of the granulated body is 1.8 mass% or more and 3.0 mass% or less.SELECTED DRAWING: Figure 1

Claims

1. General formula LiMn ｘ Fe ｙ PO ４ The granulated material comprises a core composed of olivine-type manganese iron lithium phosphate (where x and y are numerical values ​​satisfying x + y = 1, 0 < x < 1, and 0 < y < 1), and a carbon coating formed on the surface of the core. The core has a structure in which primary particles of the olivine-type manganese iron lithium phosphate are aggregated, The particle size of the primary particles is 100 nm or less. The pore volume in the granular material with a pore diameter of 2 nm to 300 nm is 0.2 cm³. ３ / g or less, The carbon content of the granulated material is 1.8% by mass or more and 3.0% by mass or less, and this is a positive electrode material for a lithium-ion secondary battery.

2. A positive electrode current collector having a first surface, The positive electrode current collector comprises a positive electrode active material layer formed on the first surface of the positive electrode current collector, The positive electrode for a lithium-ion secondary battery comprises the positive electrode active material layer described in claim 1.

3. The basis weight of the positive electrode active material layer is 30 mg / cm². ２ 100mg / cm or more ２ The positive electrode for a lithium-ion secondary battery according to claim 2, which is as follows:

4. General formula LiMn ｘ Fe ｙ PO ４ (x and y are numerical values that satisfy x + y = 1, 0 < x < 1, and 0 < y < 1.) By pulverizing the particles of olivine-type lithium manganese iron phosphate represented by the formula in the presence of an aqueous solvent, a carbon source, and a carboxylic acid, a step of preparing a slurry containing the pulverized product of the olivine-type lithium manganese iron phosphate is carried out. A step of obtaining aggregates of the pulverized material by spray-drying the slurry, The process includes a step of carbonizing the carbon source contained in the aggregate by calcining the aggregate, A method for producing a positive electrode material for a lithium-ion secondary battery, wherein the content of the carboxylic acid in the slurry is 2 parts by mass or more and 10 parts by mass or less per 100 parts by mass of the olivine-type lithium iron manganese phosphate.

5. The method for producing a positive electrode material for a lithium-ion secondary battery according to claim 4, wherein the carboxylic acid is citric acid.

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