Wound Secondary Battery Core Structure for Electrode Buckling Control

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Solution Overview

Problem

Secondary batteries exhibit insufficient cycle characteristics due to electrode buckling and breakage during charging and discharging, particularly in lithium secondary batteries where lithium metal deposition leads to significant volume changes and stress on the negative electrode.

Innovation Solution

Incorporating a core member into the hollow part of the electrode group and using a resin film to support the active material layer, which mitigates stress and stabilizes the electrode shape, thereby improving cycle characteristics.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Stability of the object's composition

If a core member is disposed in a hollow part of a wound electrode group, then electrode buckling and breakage are suppressed, but cycle characteristics remain insufficient

Engineering Contradiction:

Improveelectrode shape stabilityVSAvoidcycle characteristics

Core Design Contradiction:

Stability of the object's compositionVSReliability

Solution Approach 1:

The patent applies a resin film as a flexible support structure between the positive and negative electrodes. This resin film acts as a flexible shell that maintains electrode shape stability while accommodating volume changes during charging and discharging, thereby improving cycle characteristics without causing electrode buckling or breakage

Inventive Principle:

Principle #30Flexible shells and thin films

Solution Approach 2:

The patent uses a composite structure combining a core member with a resin film. The core member provides structural support while the resin film adds flexibility and stress distribution capabilities. This composite approach resolves the contradiction by combining the shape-stabilizing effect of the core with the cycle-life-improving effect of the flexible resin film

Inventive Principle:

Principle #40Composite materials

2Quantity of substance

If lithium metal is deposited on the negative electrode during charging, then battery capacity is increased, but electrode stress and volume changes cause breakage

Engineering Contradiction:

Improvelithium metal deposition amountVSAvoidelectrode strength

Core Design Contradiction:

Quantity of substanceVSStrength

Solution Approach 1:

The resin film is placed beforehand between the positive and negative electrodes to provide cushioning and stress distribution. This pre-positioned flexible layer absorbs and distributes the stress generated during lithium metal deposition and electrode volume changes, preventing electrode breakage while allowing high lithium metal content

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

Solution Approach 2:

The patent changes the mechanical properties parameter of the electrode structure by introducing a flexible resin film with appropriate elasticity and tensile strength. This parameter change allows the electrode structure to accommodate large volume changes during lithium metal deposition without losing structural integrity

Inventive Principle:

Principle #35Parameter changes

Data Source

PatentUS20250219093A1Secondary battery

Publication Date: 2025.07.03 PANASONIC INTELLECTUAL PROPERTY MANAGEMENT CO LTD

AI summary

A secondary battery includes: a wound electrode group including a pair of electrodes and a separator disposed between the pair of electrodes; a core member disposed in a hollow part of the electrode group; and a non-aqueous electrolyte. At least one of the pair of electrodes includes an active material layer and a resin film supporting the active material layer.