CHARGING METHOD AND CHARGING/DISCHARGING METHOD OF LITHIUM ION SECONDARY BATTERY

• US 20100207583A1
• Filed: 03/26/2009
• Published: 08/19/2010
• Est. Priority Date: 06/12/2008
• Status: Abandoned Application

• Current Assignee: Panasonic Corporation (Panasonic Holdings Corporation)
• Original Assignee: Panasonic Corporation (Panasonic Holdings Corporation)
• Inventors: Tanaka, Ryoichi, Nagasaki, Akira, Hina, Yasuhiko
• Application Number:
  US12/680,095
• Publication Number:
  US 20100207583A1
• Time in Patent Office: Days
• US Class Current: 320/134
• CPC Class Codes: H01M 10/0525 Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
• CPC Class Codes: H01M 10/44 Methods for charging or discharging circuits for charging H02J7/00
• CPC Class Codes: H01M 4/525 of mixed oxides or hydroxides containing iron, cobalt or nickel for inserting or intercalating light metals, e.g. LiNiO2, LiCoO2 or LiCoOxFy
• CPC Class Codes: H02J 7/0071 with a programmable schedule
• CPC Class Codes: Y02E 60/10 Energy storage using batteries

Abstract

The present invention relates to a charging method of a lithium ion secondary battery including, as a positive electrode active material, a lithium-containing composite oxide containing nickel and cobalt and having a layered crystal structure. The charging method includes a first step of charging the battery at a first current of 0.5 to 0.7 It until the charge voltage of the battery reaches a first upper limit voltage of 3.8 to 4.0 V; a second step of charging the battery, upon completion of the first step, at a second current smaller than the first current until the charge voltage of the battery reaches a second upper limit voltage greater than the first upper limit voltage; and a third step of charging the battery, upon completion of the second step, at the second upper limit voltage. This provides a charging method of a lithium ion secondary battery, the method capable of achieving both a shortened charging time and an improvement in charge/discharge cycle life characteristics.

Claims

1. A charging method of a lithium ion secondary battery including, as a positive electrode active material, a lithium-containing composite oxide containing nickel and cobalt and having a layered crystal structure, the method comprising:

a first step of charging said battery at a first current of 0.5 to 0.7 It until the charge voltage of said battery reaches a first upper limit voltage of 3.8 to 4.0 V;

a second step of charging said battery, upon completion of said first step, at a second current smaller than said first current until the charge voltage of said battery reaches a second upper limit voltage greater than said first upper limit voltage; and

a third step of charging said battery, upon completion of said second step, at said second upper limit voltage.

2. The charging method of a lithium ion secondary battery in accordance with claim 1, said lithium-containing composite oxide is represented by the general formula:

LiNi_xCo_yM_(1-x-y)O₂, where M is at least one element selected from the group consisting of Group 2 elements, Group 3 elements, Group 4 elements, and Group 13 elements in the long form of the periodic table, and x and y satisfy 0.3≦

x<

1.0 and 0<

y<

0.4.

3. The charging method of a lithium ion secondary battery in accordance with claim 1, wherein said second upper limit voltage is 4.0 to 4.2 V.

4. The charging method of a lithium ion secondary battery in accordance with claim 1, wherein said second current is 0.3 to 0.5 It.

5. A charging/discharging method of a lithium ion secondary battery comprising a step of repeating a cycle of charging said battery according to the method of claim 1 and subsequent discharging, wherein said first current is decreased at a predetermined rate every cycle.

6. A charging/discharging method of a lithium ion secondary battery comprising a step of repeating a cycle of charging said battery according to the method of claim 1 and subsequent discharging, wherein said first current is decreased by a predetermined value at intervals of a predetermined number of cycles.