LITHIUM SECONDARY BATTERY

• US 20150207183A1
• Filed: 01/21/2015
• Published: 07/23/2015
• Est. Priority Date: 01/23/2014
• Status: Abandoned Application

• Current Assignee: Toyota Jidosha Kabushiki Kaisha (Toyota Motor Corporation)
• Original Assignee: Toyota Jidosha Kabushiki Kaisha (Toyota Motor Corporation)
• Inventors: ABE, Machiko
• Application Number:
  US14/601,704
• Publication Number:
  US 20150207183A1
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: H01M 10/052 Li-accumulators
• CPC Class Codes: H01M 10/0567 characterised by the additives
• CPC Class Codes: H01M 10/0587 of accumulators having only wound construction elements, i.e. wound positive electrodes, wound negative electrodes and wound separators
• CPC Class Codes: H01M 10/4235 Safety or regulating additives or arrangements in electrodes, separators or electrolyte H01M10/4242 takes precedence
• CPC Class Codes: H01M 2200/20 Pressure-sensitive devices
• CPC Class Codes: H01M 2300/0025 Organic electrolyte
• CPC Class Codes: H01M 50/578 in response to pressure
• CPC Class Codes: Y02E 60/10 Energy storage using batteries
• CPC Class Codes: Y02P 70/50 Manufacturing or production processes characterised by the final manufactured product
• CPC Class Codes: Y02T 10/70 Energy storage systems for electromobility, e.g. batteries

Abstract

A lithium secondary battery is provided, which exhibits a large overcharge tolerance even after rapid charge-discharge cycling. The lithium secondary battery is constituted by a battery case hosing electrode assembly having a positive electrode and a negative electrode, and also housing a nonaqueous electrolyte solution including a supporting salt. The nonaqueous electrolyte solution contains, in addition to the supporting salt, at least 2 wt % of a gas-forming agent that decomposes to form a gas when the battery reaches an overcharged state and, as a surfactant, at least 1 wt % of a polyethylene glycol fatty acid ester. The battery case is equipped with a current interrupt device that is actuated by a rise in pressure within the battery case.

Claims

1. A lithium secondary battery comprising a battery case housing an electrode assembly having a positive electrode and a negative electrode, and also housing a nonaqueous electrolyte solution including a supporting salt, wherein

the nonaqueous electrolyte solution contains, in addition to the supporting salt, at least 2 wt % of a gas-forming agent that decomposes to form a gas when the battery reaches an overcharged state, and, as a surfactant, at least 1 wt % of a polyethylene glycol fatty acid ester, and

the battery case is equipped with a current interrupt device that is actuated by a rise in pressure within the battery case.

2. The lithium secondary battery according to claim 1, wherein the content of the polyethylene glycol fatty acid ester is not more than 3 wt %.

3. The lithium secondary battery according to claim 1, wherein the content of the gas-forming agent is not more than 5 wt %.

4. The lithium secondary battery according to claim 1, wherein the polyethylene glycol fatty acid ester is polyethylene glycol distearate.

5. The lithium secondary battery according to claim 1, wherein

the electrode assembly is a wound electrode assembly comprising a positive electrode, a negative electrode and a separator, each having an elongated shape, that have been placed over one another and wound together in a lengthwise direction thereof,

in a width direction defined as a direction along a winding axis of the wound electrode assembly from a first edge portion of the wound electrode assembly toward a second edge portion thereof, the ratio Mb/Ma of the amount (Mb) of the gas-forming agent included at an edge portion of the positive electrode to the amount (Ma) of the gas-forming agent included at a center portion of the positive electrode is less than 2, and

in the width direction, the ratio Qb/Qa of the amount per unit volume (Qb) of the supporting salt included at an edge portion of the negative electrode to the amount per unit volume (Qa) of the supporting salt included at a center portion of the negative electrode is 2 or more.