Battery Electrode Coating to Limit Edge Thickening and Spread

Solution Overview

Problem

The edge portions of positive and negative active material layers in power storage devices can become thicker or spread out, leading to defects and increased planar size, which can damage the layers during manufacturing.

Innovation Solution

The electrode design includes an active material layer with a body and an edge portion, using carboxymethyl cellulose ammonium (NH4-CMC) and carbon nanotubes, and a specific viscosity control process to manage thickness and dimensions, preventing excessive spreading.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Quantity of substance

If the active material layer is made thicker to increase charge storage capacity, then the amount of active material increases, but the edge portion becomes excessively thick and may spread out during manufacturing

Engineering Contradiction:

Improveamount of active materialVSAvoidthickness uniformity of edge portion

Core Design Contradiction:

Quantity of substanceVSManufacturing precision

Solution Approach 1:

The patent applies local quality by creating a gradient structure where the active material layer has different thickness characteristics in different regions. The edge portion is designed with a controlled thickness gradient that transitions from the body thickness to a thinner edge region, preventing excessive thickness accumulation at the edges while maintaining high charge storage capacity in the central body region.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent changes the thickness parameter of the active material layer by specifying that the edge portion thickness is controlled to be 104% or less of the body thickness. This parameter control prevents the edge portion from becoming excessively thick during the coating and drying processes, thereby maintaining manufacturing precision while allowing the body to have sufficient thickness for charge storage.

Inventive Principle:

Principle #35Parameter changes

2Quantity of substance

If the active material layer is made larger in planar size to increase capacity, then more active material is available, but the edge portion spreads out and increases the overall planar dimensions beyond predetermined sizes

Engineering Contradiction:

Improveamount of active materialVSAvoidplanar size of active material layer

Core Design Contradiction:

Quantity of substanceVSLength of stationary object

Solution Approach 1:

The patent applies local quality by creating a gradient structure where the active material layer has different thickness characteristics in different regions. The edge portion is designed with a controlled thickness gradient that transitions from the body thickness to a thinner edge region, preventing excessive thickness accumulation at the edges while maintaining high charge storage capacity in the central body region.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent applies preliminary action by pre-controlling the thickness of the edge portion during the coating process. By ensuring the edge portion thickness is 104% or less of the body thickness before drying and manufacturing completion, the patent prevents subsequent spreading that would otherwise occur during compression and assembly operations.

Inventive Principle:

Principle #10Preliminary action

3Strength

If the edge portion thickness is increased to prevent damage during compression, then the active material layer becomes more robust, but the planar size increases and defects occur

Engineering Contradiction:

Improverobustness of active material layerVSAvoidplanar size control

Core Design Contradiction:

StrengthVSManufacturing precision

Solution Approach 1:

The patent changes the thickness parameter of the active material layer by specifying that the edge portion thickness is controlled to be 104% or less of the body thickness. This parameter control prevents the edge portion from becoming excessively thick during the coating and drying processes, thereby maintaining manufacturing precision while allowing the body to have sufficient thickness for charge storage.

Inventive Principle:

Principle #35Parameter changes

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 reduces defects and maintains the integrity of the active material layers, ensuring consistent manufacturing and improved performance of the power storage device.

Implementation Method 1

In the active material layer, a content amount of the CMC derived from carboxymethyl cellulose ammonium (NH4-CMC) is 0.3 mass percent or greater and 0.6 mass percent or less. In the active material layer, a content amount of the carbon nanotube is 0.005 mass percent or greater and 0.08 mass percent or less.

Methodology Applied

Scientific EffectViscosity control:

Data Source

PatentUS20260024773A1Electrode for power storage device, and method for producing composite material for active material layer

Publication Date: 2026.01.22 TOYOTA INDUSTRIES CORP

AI summary

An active material layer of an electrode contains an active material, carbon nanotubes, and CMC derived from carboxymethylcellulose ammonium (NH4-CMC). The content of CMC derived from NH4-CMC in the active material layer is 0.3-0.6 mass %. The content of carbon nanotubes in the active material layer is 0.005-0.08 mass %. The active material layer includes a main body portion and an edge portion surrounding the main body portion. The maximum thickness of the edge portion is 104% of the thickness of the main body portion. In a plan view of the electrode in the thickness direction of the active material layer, the maximum dimension of the edge portion from the boundary between the main body portion and the edge portion to the tip of the edge portion is 5 mm.