Secondary Battery Electrode Winding for Gas Release

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Solution Overview

Problem

Lithium ion batteries with current collector plates on both end surfaces face challenges in gas discharge during abnormal heat generation, leading to potential safety issues due to inadequate gas purging structures.

Innovation Solution

A secondary battery design where strip-shaped positive and negative electrodes with active material non-covered portions are wound with a separator, and the non-covered portions are bent and overlapped to form a flat surface with a groove, allowing for improved gas release by reducing the overlap area between current collector plates.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Power

If current collector plates are joined to both end surfaces of the wound electrode body, then high current output is achieved, but gas discharge ability deteriorates during abnormal heat generation

Engineering Contradiction:

Improvecurrent outputVSAvoidgas accumulation

Core Design Contradiction:

PowerVSObject-generated harmful factors

Solution Approach 1:

The current collector plate is segmented into multiple regions: a first current collector plate region that contacts the positive electrode and a second current collector plate region that contacts the negative electrode. These regions are spatially separated and positioned at different locations on the end surface, creating distinct functional zones that allow both high current collection and gas discharge pathways.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different regions of the current collector plate are assigned different functions: the first current collector plate region is optimized for current collection from the positive electrode, while the second current collector plate region is positioned to facilitate gas discharge. This local differentiation allows simultaneous optimization of both current output and safety functions.

Inventive Principle:

Principle #3Local quality

2Reliability

If current collector plates cover the end surface of the wound electrode body, then electrical connection is improved, but gas purging ability deteriorates

Engineering Contradiction:

Improveelectrical connectionVSAvoidgas retention

Core Design Contradiction:

ReliabilityVSObject-generated harmful factors

Solution Approach 1:

The current collector plate is divided into functionally distinct regions that perform different tasks. The first region ensures reliable electrical connection with the positive electrode, while the second region creates space and pathways for gas purging, thus resolving the conflict between connection reliability and gas release capability.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The solution moves from a two-dimensional coverage problem to a three-dimensional spatial arrangement. By positioning the first and second current collector plate regions at different locations and orientations on the end surface, the design creates three-dimensional gas channels while maintaining electrical connectivity.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

3Stability of the object's composition

If overlap area between positive and negative current collector plates is large, then structural stability is improved, but gas release properties deteriorate

Engineering Contradiction:

Improvestructural stabilityVSAvoidgas discharge ability

Core Design Contradiction:

Stability of the object's compositionVSObject-generated harmful factors

Solution Approach 1:

By segmenting the current collector plate into first and second regions with controlled overlap, the design achieves structural stability through the presence of both regions while limiting their overlap area to maintain gas discharge pathways. The segmented structure provides stability without requiring extensive overlap.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The design optimizes the overlap area parameter between the first and second current collector plate regions, maintaining it within a specific range that balances structural stability requirements with gas release requirements. This parameter optimization resolves the contradiction between stability and gas discharge.

Inventive Principle:

Principle #35Parameter changes

Data Source

PatentUS20220344724A1Secondary battery, electronic device, and power tool

Publication Date: 2022.10.27 MURATA MFG CO LTD

AI summary

Provided is a secondary battery, in the secondary battery, the positive electrode has a covered portion covered with a positive electrode active material layer and a positive electrode active material non-covered portion on a strip-shaped positive electrode foil, the negative electrode has a covered portion covered with a negative electrode active material layer and a negative electrode active material non-covered portion on a strip-shaped negative electrode foil, the positive electrode active material non-covered portion are joined to the positive electrode current collector plate at one end portion of the electrode winding body, the negative electrode active material non-covered portion is joined to the negative electrode current collector plate at the other end portion of the electrode winding body, the electrode winding body has a flat surface formed by bending any one or both of the positive electrode active material non-covered portion and the negative electrode active material non-covered portion.