Nonaqueous electrolyte secondary battery

Patent metadata

Field	Value
Publication number	US-2020014023-A1
Application number	US-201816483837-A
Country	US
Kind code	A1
Filing date	Jan 26, 2018
Priority date	Feb 14, 2017
Publication date	Jan 9, 2020
Grant date	—

Abstract

A nonaqueous electrolyte secondary battery in which low-crystalline carbon-covered graphite is used as a 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

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 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 mon 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

• H01M2004/021

  Physical characteristics, e.g. porosity, surface area · CPC title

• H01M4/364

  as mixtures · CPC title

• H01M10/0568

  characterised by the solutes · CPC title

• H01M4/583

  Carbonaceous material, e.g. graphite-intercalation compounds or CFx · CPC title

• H01M4/131 Primary

  Electrodes based on mixed oxides or hydroxides, or on mixtures of oxides or hydroxides, e.g. LiCoOx · CPC title