Pouch Battery Case Asymmetry Prevents Metal Exposure

Solution Overview

Problem

Pouch-type lithium secondary batteries face issues with metal layer exposure, leading to potential shorts and corrosion, which can cause swelling, performance loss, and increased production costs due to the need for additional insulation.

Innovation Solution

The battery design includes bonding surfaces of different widths on the upper and lower case portions, with a wing part and extension part that are folded to prevent metal layer exposure, thereby preventing shorts and corrosion.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the case is sealed by bonding upper and lower case portions with the same width, then the sealing process is simple, but the metal layer is exposed at the free ends causing shorts and corrosion

Engineering Contradiction:

Improveprevention of metal layer exposureVSAvoidcase structure complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent applies asymmetry by designing the lower case portion with a greater width than the upper case portion. This width difference creates an overlapping structure where the lower case portion extends beyond the upper case portion, effectively covering the metal layer at the free ends and preventing exposure, while maintaining a relatively simple sealing process.

Inventive Principle:

Principle #4Asymmetry

2Reliability

If additional insulation processes are added to prevent metal layer exposure, then short and corrosion are prevented, but production costs increase

Engineering Contradiction:

Improveprevention of short and corrosionVSAvoidproduction cost

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The patent applies self-service by designing the case structure itself to provide the insulation function. The asymmetric width design causes the lower case portion to overlap and cover the metal layer, making the case structure itself serve as the insulation barrier, thereby eliminating the need for additional insulation processes and reducing production costs.

Inventive Principle:

Principle #25Self-service

3Weight of moving object

If the case is made of composite film with metal layer for lightweight and small-sized devices, then formability is excellent, but the metal layer is exposed at free ends leading to corrosion and swelling

Engineering Contradiction:

Improvebattery weightVSAvoidprevention of corrosion and swelling

Core Design Contradiction:

Weight of moving objectVSReliability

Solution Approach 1:

The patent applies asymmetry by designing the lower case portion with a greater width than the upper case portion. This width difference creates an overlapping structure where the lower case portion extends beyond the upper case portion, effectively covering the metal layer at the free ends and preventing exposure, while maintaining a relatively simple sealing process.

Inventive Principle:

Principle #4Asymmetry

Data Source

PatentUS8790817B2Pouch-type lithium secondary battery

Publication Date: 2014.07.29 SAMSUNG SDI CO LTD

AI summary

A pouch-type lithium secondary battery including: an electrode assembly; and a case to house the electrode assembly, including first and second case portions. The first case portion includes a receiving part to receive the electrode assembly, and a wing part extending from the receiving part. The second case portion includes an outer part that is sealed to the wing part, and an extension part that extends from the outer part and is folded toward the wing part.