Folded Current Collector Unit Cell for Thin Sealed Battery Joints

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Solution Overview

Problem

Existing thin battery designs face challenges in maximizing energy density per unit area and per unit volume due to the thickness increase caused by folded portions and sealed areas.

Innovation Solution

A unit cell design featuring a first current collector layer, a first electrode active material layer, an electrolyte layer, a second electrode active material layer, and a second current collector layer, where the electrolyte and second electrode layers have a peripheral and inner region, and the second current collector is folded to enclose these layers, joined via an insulating sealing member to the first current collector, forming a joint portion that minimizes thickness.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the second current collector layer is folded to enclose the electrolyte layer and second electrode active material layer, then the sealing reliability is improved, but the thickness of the joint portion increases

Engineering Contradiction:

Improvesealing reliabilityVSAvoidthickness of joint portion

Core Design Contradiction:

ReliabilityVSLength of stationary object

Solution Approach 1:

The insulating sealing member is inserted into the joint portion formed by the folded second current collector layer and first current collector layer. This nesting approach allows the sealing function to be integrated within the existing folded structure rather than adding external sealing components, thereby improving sealing reliability while minimizing thickness increase.

Inventive Principle:

Principle #7Nested doll (Nesting)

Solution Approach 2:

The insulating sealing member is designed as a thin film structure that can be inserted into the joint portion. This thin film approach provides effective sealing while maintaining minimal thickness addition to the overall unit cell structure.

Inventive Principle:

Principle #30Flexible shells and thin films

2Reliability

If the insulating sealing member is used to join the current collector layers, then the electrical insulation is improved, but the area occupied by the sealing member increases

Engineering Contradiction:

Improveelectrical insulationVSAvoidarea occupied by sealing member

Core Design Contradiction:

ReliabilityVSArea of stationary object

Solution Approach 1:

The insulating sealing member is applied locally only at the joint portion where the first and second current collector layers are joined, rather than covering the entire electrode area. This localized application provides necessary electrical insulation at the critical joint region while minimizing the overall area occupied by the sealing member, thereby improving energy density per unit area.

Inventive Principle:

Principle #3Local quality

3Quantity of substance

If the sealed portion is made as small as possible, then the energy density is improved, but the sealing effectiveness may be compromised

Engineering Contradiction:

Improveenergy densityVSAvoidsealing effectiveness

Core Design Contradiction:

Quantity of substanceVSReliability

Solution Approach 1:

The insulating sealing member is nested within the joint portion formed by the folded current collector structure. This integration allows the sealing function to be achieved within the existing structural footprint without requiring additional external sealing space, thereby maintaining small sealed portion area while ensuring effective sealing.

Inventive Principle:

Principle #7Nested doll (Nesting)

Solution Approach 2:

The insulating sealing member is designed as a thin film that can provide effective sealing with minimal thickness and area. This thin film approach allows the sealed portion to remain compact, maximizing energy density while maintaining sealing effectiveness through the insulating properties of the sealing member material.

Inventive Principle:

Principle #30Flexible shells and thin films

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

This design enhances energy density per unit area by reducing the area occupied by the insulating sealing member and improves energy density per unit volume by minimizing the thickness of the joint portion, thus optimizing the overall energy storage capacity.

Implementation Method 1

joined via an insulating sealing member to the first current collector, forming a joint portion

Methodology Applied

Scientific EffectAdhesion: Adhesive

Data Source

PatentUS20250046925A1Unit cell

Publication Date: 2025.02.06 TOYOTA JIDOSHA KK

AI summary

A unit cell in which a first current collector layer, a first electrode active material layer, an electrolyte layer, a second electrode active material layer, and a second current collector layer are laminated in this order, wherein the first electrode active material layer is laminated only on the inner region, and the second current collector layer is folded so as to enclose the electrolyte layer and the second electrode active material layer, and is joined to the first current collector layer via an insulating sealing member on the peripheral region to form a joint portion, thereby sealing the first electrode active material layer, the electrolyte layer, and the second electrode active material layer with the first current collector layer, the insulating sealing member, and the second current collector layer.