Negative Electrode Grooves Prevent Passivation Delamination

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Solution Overview

Problem

Lithium metal negative electrodes in secondary batteries face issues such as passivation layer delamination and lithium dendrite growth, leading to reduced lifespan, nonuniform current distribution, and potential internal short circuits due to high reactivity with electrolytes.

Innovation Solution

A negative electrode design featuring a collector with delamination prevention current collection grooves, where the active material is integrated on the inner surface of these grooves, creating a space for passivation layer formation that is supported by the groove walls, preventing delamination and collapse.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Quantity of substance

If lithium metal is used as negative electrode active material, then battery capacity and energy density are improved, but passivation layer delamination and lithium dendrite growth occur leading to reduced lifespan and safety issues

Engineering Contradiction:

Improvebattery capacityVSAvoidbattery lifespan

Core Design Contradiction:

Quantity of substanceVSReliability

Solution Approach 1:

The negative electrode is segmented into multiple recesses formed on the current collector surface. Each recess acts as an independent compartment that confines lithium deposition and passivation layer formation to specific localized areas, preventing uncontrolled dendrite growth and delamination across the entire electrode surface.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different regions of the negative electrode are given different functions: the recesses provide confined spaces for controlled lithium deposition and passivation layer formation, while the raised portions between recesses serve as current collection areas. This local differentiation optimizes both capacity utilization and structural stability.

Inventive Principle:

Principle #3Local quality

2Quantity of substance

If lithium metal is used as negative electrode active material, then battery capacity is improved, but internal short circuit risk increases due to dendrite growth

Engineering Contradiction:

Improvebattery capacityVSAvoidinternal short circuit risk

Core Design Contradiction:

Quantity of substanceVSObject-affected harmful factors

Solution Approach 1:

By dividing the negative electrode surface into multiple isolated recesses, the invention physically separates potential dendrite growth paths. Even if dendrites form in one recess, they are confined to that local area and cannot easily bridge across to the positive electrode, thereby reducing internal short circuit risk while maintaining high capacity.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The recess structure acts as an intermediary barrier between the lithium metal and the separator/positive electrode. This intermediate structure controls and directs lithium deposition patterns, preventing direct dendrite penetration through the separator that would cause internal short circuits.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Stability of the object's composition

If passivation layer is formed on lithium metal surface, then electrochemical stability is improved, but delamination and collapse occur during charging-discharging cycles

Engineering Contradiction:

Improveelectrochemical stabilityVSAvoidcycle stability

Core Design Contradiction:

Stability of the object's compositionVSDuration of action of stationary object

Solution Approach 1:

The passivation layer is segmented into multiple small, localized formations within individual recesses rather than forming a large continuous layer. This segmentation reduces mechanical stress and delamination risk during volume changes associated with charging-discharging cycles, improving cycle stability while maintaining electrochemical stability.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The recess structure provides a pre-designed accommodation space that anticipates and cushions the volume changes and stress development of the passivation layer during cycling. This beforehand cushioning prevents delamination and collapse by providing a compliant, structured environment that absorbs mechanical stresses.

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

4Ease of manufacture

If current collector surface is flat, then manufacturing is simple, but passivation layer delamination occurs during charging-discharging

Engineering Contradiction:

Improvecurrent collector processingVSAvoidpassivation layer adhesion

Core Design Contradiction:

Ease of manufactureVSReliability

Solution Approach 1:

The current collector surface is modified with curved recesses instead of remaining flat. These curved, three-dimensional structures provide better mechanical interlocking and adhesion for the passivation layer, preventing delamination during cycling. The curvature also promotes uniform stress distribution, further enhancing adhesion reliability.

Inventive Principle:

Principle #14Spheroidality (Curvature)

5Volume of moving object

If lithium metal is used without surface patterning, then battery size can be reduced, but nonuniform current distribution and dendrite formation occur

Engineering Contradiction:

Improvebattery sizeVSAvoidcurrent distribution uniformity

Core Design Contradiction:

Volume of moving objectVSStability of the object's composition

Solution Approach 1:

The negative electrode surface is segmented into multiple recesses that serve as discrete, uniform lithium deposition sites. This segmentation ensures that current is distributed evenly across all recesses, preventing localized hotspots and nonuniform deposition that would lead to dendrites, while the compact recess structure maintains small battery size.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different regions of the electrode are optimized for different functions: recesses are designed with specific dimensions and depths to control local current density and lithium deposition uniformity, while maintaining overall compact battery size. The local quality enhancement in recess areas compensates for the reduced total electrode area.

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 enhances battery lifespan by preventing passivation layer delamination, reducing resistance, and minimizing dendrite growth, thus avoiding internal short circuits and maintaining cycle efficiency.

Implementation Method 1

provides a electrochemical reaction position by which lithium ion is deposited or separated

Methodology Applied

Scientific EffectElectrochemical reaction:

Data Source

PatentEP3444874B1Negative electrode for secondary battery

Publication Date: 2023.08.09 LG ENERGY SOLUTION LTD

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AI summary

The present invention relates to a negative electrode for a secondary battery. The negative electrode for the secondary battery according to an embodiment of the present invention comprises a negative electrode collector and a negative electrode active material integrated with at least a portion of a surface of the negative electrode collector, wherein the negative electrode collector has a plurality of delamination prevention current collection grooves with which the negative electrode active material is integrated, and the negative electrode active material is disposed on an inner surface of each of the delamination prevention current collection grooves so that a space part in which a passivation layer is formed is defined during charging and discharging.