Multi-Layer Electrode with Trapezoidal Concave Portions

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Solution Overview

Problem

Lithium secondary batteries face challenges in achieving high-rate charge-discharge characteristics and adhesion between the current collector and active material layers, leading to interfacial resistance issues and reduced battery performance.

Innovation Solution

The electrode design includes multiple active material layers with convex and concave portions, specifically with a trapezoidal cross-section concave portions, to enhance adhesion and electrolyte impregnation, reducing interfacial resistance and improving ionic conductivity.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If a single active material layer is used, then the structure is simple, but adhesion between current collector and active material is insufficient and interfacial resistance is high

Engineering Contradiction:

Improveadhesion between current collector and active materialVSAvoidstructure complexity

Core Design Contradiction:

StrengthVSDevice complexity

Solution Approach 1:

The electrode structure is segmented into multiple active material layers (first active material layer and second active material layer) stacked on the current collector. This segmentation increases the total adhesion area between the active material and current collector, resolving the adhesion issue while maintaining structural organization through defined layering.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The invention transitions from a single-layer two-dimensional structure to a multi-layer three-dimensional stacked structure. By adding the vertical dimension with multiple layers, the adhesion area is significantly increased without proportionally increasing horizontal space occupation, effectively resolving the adhesion problem.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

2Reliability

If flat active material layers are used, then manufacturing is simple, but electrolyte impregnation is insufficient and ionic conductivity is low

Engineering Contradiction:

Improveionic conductivityVSAvoidmanufacturing simplicity

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The active material layers incorporate convex portions and concave portions creating a porous three-dimensional structure. This porosity enables better electrolyte penetration and impregnation throughout the layer, improving ionic conductivity while the porous structure can be formed through standard manufacturing processes.

Inventive Principle:

Principle #31Porous materials

Solution Approach 2:

The flat surfaces are replaced with curved and irregular surfaces featuring convex and concave portions. This curvature increases the surface area and creates pathways for electrolyte penetration, improving ionic conductivity without requiring complex manufacturing steps beyond standard coating and drying processes.

Inventive Principle:

Principle #14Spheroidality (Curvature)

3Strength

If binder content is increased, then adhesion improves, but active material desorption increases and battery performance deteriorates

Engineering Contradiction:

Improveadhesion between layersVSAvoidbattery performance

Core Design Contradiction:

StrengthVSProductivity

Solution Approach 1:

The binder distribution is segmented and optimized across different layers. The first binder is specifically placed at the interface between the current collector and first active material layer, while the second binder is placed at the interface between the two active material layers. This targeted segmentation provides necessary adhesion without excessive binder content that would hinder performance.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different binder contents and types are applied locally at different interfaces rather than uniformly throughout. The first binder (polyvinylidene fluoride-based) is used at the current collector interface, while the second binder (carboxymethyl cellulose-based) is used between active material layers, optimizing adhesion locally without compromising overall battery performance.

Inventive Principle:

Principle #3Local quality

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 improves charge-discharge characteristics at high rates, enhances adhesion, and inhibits active material desorption, resulting in better battery performance and extended lifetime.

Implementation Method 1

the first active material layer or the second active material layer includes convex portions and concave portions, and the concave portions have a triangular cross section or a trapezoidal cross section

Methodology Applied

Scientific EffectAdhesion: Adhesive

Implementation Method 2

Methodology Applied

Scientific EffectCapillary action: Capillary Action

Data Source

PatentUS11430988B2Electrode and secondary battery including the same

Publication Date: 2022.08.30 SAMSUNG SDI CO LTD

AI summary

An electrode and a secondary battery, the electrode including a conductive substrate; and a plurality of active material layers on the conductive substrate, wherein the plurality of active material layers includes a first active material layer and a second active material layer; the first active material layer is on the substrate, the second active material layer is on the first active material layer; the first active material layer includes a first active material and a first binder; the second active material includes a second active material and a second binder; the first active material layer or the second active material layer includes convex portions and concave portions, and the concave portions have a triangular cross section or a trapezoidal cross section.