Pressure-relief mechanism to improve safety in lithium-polymer battery cells

Abstract

The disclosed embodiments relate to a battery cell which includes a weakness for relieving pressure. This battery cell includes a jelly roll comprising layers which are wound together, including a cathode with an active coating, a separator and an anode with an active coating. The jelly roll also includes a first conductive tab coupled to the cathode and a second conductive tab coupled to the anode. The jelly roll is enclosed in a flexible pouch, wherein the first and second conductive tabs extend through seals in the pouch to provide terminals for the battery cell. This pouch includes a weakness which yields when internal pressure in the pouch exceeds a threshold to create a hole which releases the internal pressure.

Description

BACKGROUND[0001]1. Field[0002]The disclosed embodiments relate to techniques for improving safety in rechargeable lithium-polymer battery cells. More specifically, the disclosed embodiments relate to the design of a pressure-relief mechanism which improves the safety in lithium-polymer battery cells.[0003]2. Related Art[0004]Rechargeable batteries are presently used to provide power to a wide variety of portable electronic devices, including laptop computers, cell phones, PDAs, digital music players and cordless power tools. The most commonly used type of rechargeable battery is a lithium battery, which can include a lithium-ion or a lithium-polymer battery.[0005]A potential safety issue can arise if there is a gas buildup within a rechargeable lithium battery cell. This can occur, for example, if the cell is overcharged, if there is a short within the cell, or if the cell is left uncharged for a significant period of time. This type of gas buildup can potentially cause the battery ...

AI Technical Summary

Problems solved by technology

A potential safety issue can arise if there is a gas buildup within a rechargeable lithium battery cell.

This type of gas buildup can potentially cause the battery cell to swell or even to explode, which can seriously damage the portable electronic device, and may even start a fire.

However, there exist no comparable pressure-relief mechanisms for lithium-polymer batteries, which are becoming increasingly popular in portable electronic devices.

However, no pressure-relief mechanism has been developed for these pouches so far.

This pouch includes a weakness which yields when internal pressure in the pouch exceeds a threshold to create a hole which releases the internal pressure.

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