Nonaqueous electrolyte secondary battery

Patent metadata

Field	Value
Publication number	US-10910633-B2
Application number	US-201816483837-A
Country	US
Kind code	B2
Filing date	Jan 26, 2018
Priority date	Feb 14, 2017
Publication date	Feb 2, 2021
Grant date	Feb 2, 2021

Abstract

A nonaqueous electrolyte secondary battery in which low-crystalline carbon-covered graphite is used as negative electrode active material, wherein a cobalt-containing lithium transitional metal oxide is used for: a first positive electrode active material in which the volume per unit mass of pores having a pore size of 100 nm or less is 8 mm 3 /g or greater; and a second positive electrode active material in which the volume per unit mass of pores having a pore size of 100 nm or less is 5 mm 3 /g or less.

First claim

The invention claimed is:

1. A non-aqueous electrolyte secondary battery comprising:
a positive electrode having a positive electrode mixture layer containing a first positive electrode active material and a second positive electrode active material;
a negative electrode having a negative electrode mixture layer containing a low-crystallinity carbon-coated graphite as a negative electrode active material; and
a non-aqueous electrolyte containing a lithium salt having an oxalate complex as an anion, wherein
the first positive electrode active material is a cobalt-containing lithium transition metal oxide, and has a pore volume, of pores each having a pore diameter of 100 nm or less, per mass of 8 mm 3 /g or more;
the second positive electrode active material has a pore volume, of pores each having a pore diameter of 100 nm or less, per mass of 5 mm 3 /g or less;
the pore volume, of pores each having a pore diameter of 100 nm or less, per mass of the first positive electrode active material is 4 or more times the pore volume, of pores each having a pore diameter of 100 nm or less, per mass of the second positive electrode active material;
the content of the first positive electrode active material is 30 mass % or less based on the total amount of the first positive electrode active material and the second positive electrode active material; and
the lithium salt having an oxalate complex as an anion is represented by the general formula: Li[M(C 2 O 4 ) x R y ], wherein M is B or P, R is a group selected from a halogen, an alkyl group or a halogen-substituted alkyl group, x is a positive integer, and y is 0 or a positive integer.

2. The non-aqueous electrolyte secondary battery according to claim 1 , wherein
the first positive electrode active material is a lamellar lithium transition metal oxide represented by the general formula: Li 1+x Co a M b O 2+c , wherein x, a, b and c meet the conditions: a+b=1, −0.2≤x≤0.4, 0<a≤1 and −0.1≤c≤0.4, and M is a metal element including at least one element selected from the group consisting of Ni, Mn and Al; and
the second positive electrode active material is a lamellar lithium transition metal oxide represented by the general formula: Li 1+x M a O 2+b , wherein x, a and b meet the conditions: a=1, −0.2≤x≤0.4 and −0.1≤b≤0.4, and M is a metal element including at least one element selected from the group consisting of Ni, Co, Mn and Al.

3. The non-aqueous electrolyte secondary battery according to claim 1 , wherein a molar ratio of cobalt to the total molar amount of metal elements excluding lithium in the first positive electrode active material is higher than a molar ratio of cobalt to the total molar amount of metal elements excluding lithium in the second positive electrode active material.

4. The non-aqueous electrolyte secondary battery according to claim 1 , wherein an average particle diameter of primary particles in the first positive electrode active material is 500 nm or less, and is smaller than an average particle diameter of primary particles in the second positive electrode active material.

5. The non-aqueous electrolyte secondary battery according to claim 1 , wherein the concentration of the lithium salt having an oxalate complex as an anion in the non-aqueous electrolyte is 0.01 mol/L to 0.2 mol/L.

6. The non-aqueous electrolyte secondary battery according to claim 1 , wherein the lithium salt having an oxalate complex as an anion is lithium bis(oxalato)borate (Li[B(C 2 O 4 ) 2 ]).

Assignees

• Panasonic Ip Man Co Ltd

Inventors

• Ko Takashi
• Niina Fumiharu
• Yanagida Katsunori
• Baba Yasunori
• Morikawa Yuki

Classifications

• H01M4/505

  of mixed oxides or hydroxides containing manganese for inserting or intercalating light metals, e.g. LiMn2O4 or LiMn2OxFy · CPC title

• H01M4/587

  for inserting or intercalating light metals · CPC title

• H01M4/364

  as mixtures · CPC title

• H01M4/133 Primary

  Electrodes based on carbonaceous material, e.g. graphite-intercalation compounds or CFx · CPC title

• H01M10/0525

  Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries · CPC title