Positive electrode for lithium ion secondary batteries and lithium ion secondary battery including the same

Patent metadata

Field	Value
Publication number	US-9735420-B2
Application number	US-201414782492-A
Country	US
Kind code	B2
Filing date	Apr 23, 2014
Priority date	Apr 26, 2013
Publication date	Aug 15, 2017
Grant date	Aug 15, 2017

Abstract

A positive electrode for lithium ion secondary batteries includes a collector and a positive electrode active material layer formed on at least one surface of the collector. The positive electrode active material layer contains a lithium-containing metal oxide having a unit cell represented by the following formula and a conductive material and has voids with a volume of 0.82×10 −3 cm 3 /cm 2 to 7.87×10 −3 cm 3 /cm 2 per unit area of the collector:

LiFe 1-x Zr x P 1-y Si y O 4   (1)

where 0<x<1 and 0<y<1. The unit cell has lattice constants satisfying 10.326≦a≦10.335, 6.006≦b≦6.012, and 4.685≦c≦4.714. The sum of the volume of the lithium-containing metal oxide and the volume of the conductive material is 1.61×10 −3 cm 3 /cm 2 to 6.46×10 −3 cm 3 /cm 2 per unit area of the collector.

First claim

The invention claimed is:

1. A positive electrode for lithium ion secondary batteries, comprising a collector and a positive electrode active material layer formed on at least one surface of the collector,
wherein the positive electrode active material layer contains a lithium-containing metal oxide having a unit cell represented by the following formula and a conductive material and has voids with a volume of 0.82×10 −3 cm 3 /cm 2 to 7.87×10 −3 cm 3 /cm 2 per unit area of the collector; the unit cell has lattice constants satisfying 10.326≦a≦10.335, 6.006≦b≦6.012, and 4.685≦c≦4.714; the sum of the volume of the lithium-containing metal oxide and the volume of the conductive material is 1.61×10 −3 cm 3 /cm 2 to 6.46×10 −3 cm 3 /cm 2 per unit area of the collector:
LiFe 1-x Zr x P 1-y Si y O 4   (1)

where 0<x<1 and 0<y<1.

2. The positive electrode for lithium ion secondary batteries according to claim 1 , wherein the volume of the lithium-containing metal oxide is 1.40×10 −3 cm 3 /cm 2 to 5.80×10 −3 cm 3 /cm 2 per unit area of the collector.

3. The positive electrode for lithium ion secondary batteries according to claim 1 , wherein the volume of the conductive material is 0.16×10 −3 cm 3 /cm 2 to 0.67×10 −3 cm 3 /cm 2 per unit area of the collector.

4. The positive electrode for lithium ion secondary batteries according to claim 1 , wherein the volume of the lithium-containing metal oxide and the volume of the conductive material have a ratio of 1:0.06 to 1:0.23.

5. The positive electrode for lithium ion secondary batteries according to claim 1 , wherein the sum of the volume of the lithium-containing metal oxide and the volume of the conductive material accounts for 40% to 65% of the volume of the positive electrode active material layer.

6. The positive electrode for lithium ion secondary batteries according to claim 1 , wherein x and y are within the range 0.015≦x≦0.095 and the range 0.025≦y≦0.19, respectively.

7. The positive electrode for lithium ion secondary batteries according to claim 1 , wherein x and y have a ratio of 1:1 to 1:2.

8. The positive electrode for lithium ion secondary batteries according to claim 6 , wherein the positive electrode active material layer further contains a binder and a thickening agent; the binder is an acrylic resin; the thickening agent is carboxymethylcellulose; the conductive material is acetylene black; and the volume of the positive electrode active material, the volume of the acetylene black, the volume of the acrylic resin, and the volume of the carboxymethylcellulose are 5 mg/cm 2 to 19.8 mg/cm 2 , 0.3 mg/cm 2 to 1.19 mg/cm 2 , 0.35 mg/cm 2 to 1.38 mg/cm 2 , and 0.003 mg/cm 2 to 0.012 mg/cm 2 , respectively, per unit area of the collector.

9. A lithium ion secondary battery comprising the positive electrode according to claim 1 , a negative electrode, and a separator located between the positive electrode and the negative electrode.

Assignees

• Sharp Kk

Inventors

• Asako Isao
• Nishimura Naoto
• Yoshie Tomohisa
• Matsuyama Takahiro
• Esaki Shougo
• Nishinaka Shumpei
• Kamimura Yuichi

Classifications

• H01M4/625

  Carbon or graphite · CPC title

• H01M4/136 Primary

  Electrodes based on inorganic compounds other than oxides or hydroxides, e.g. sulfides, selenides, tellurides, halogenides or LiCoFy · CPC title

• H01M10/0525

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

• H01M2004/021

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

• H01M4/525

  of mixed oxides or hydroxides containing iron, cobalt or nickel for inserting or intercalating light metals, e.g. LiNiO2, LiCoO2 or LiCoOxFy · CPC title