Silicon Anode Coating Layout for Volume Expansion Relief

Solution Overview

Problem

Silicon-based negative electrodes in lithium secondary batteries experience significant volume change during charging and discharging, leading to degradation and reduced performance, making it difficult to implement high-capacity batteries with excellent lifespan characteristics.

Innovation Solution

A lithium secondary battery design featuring a negative electrode with a coated portion and an uncoated portion positioned adjacent to the boundary between the current collector and tab, alleviating stress from volume expansion through strategic uncoated areas, allowing a high content of silicon-based active material.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Quantity of substance

If a high content of silicon-based negative electrode active material is used, then capacity is improved, but volume expansion during charging and discharging causes degradation and reduced lifespan

Engineering Contradiction:

ImprovecapacityVSAvoidlifespan characteristics

Core Design Contradiction:

Quantity of substanceVSReliability

Solution Approach 1:

The negative electrode is divided into a coated portion containing silicon-based active material and an uncoated portion without active material. This segmentation allows the electrode to accommodate volume expansion in the uncoated region while maintaining high capacity in the coated region, resolving the contradiction between capacity and lifespan

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different regions of the negative electrode are assigned different functions: the coated portion provides high capacity through silicon-based active material, while the uncoated portion provides stress relief and structural stability. This local differentiation allows simultaneous optimization of capacity and lifespan characteristics

Inventive Principle:

Principle #3Local quality

2Quantity of substance

If silicon-based negative electrode active material is used, then theoretical capacity is improved (3580 mAh/g vs 372 mAh/g for graphite), but volume change of ~400% causes deintercalation and performance degradation

Engineering Contradiction:

Improvetheoretical capacityVSAvoidstructural stability

Core Design Contradiction:

Quantity of substanceVSStability of the object's composition

Solution Approach 1:

The negative electrode is divided into a coated portion containing silicon-based active material and an uncoated portion without active material. This segmentation allows the electrode to accommodate volume expansion in the uncoated region while maintaining high capacity in the coated region, resolving the contradiction between capacity and lifespan

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The uncoated portion is positioned in advance to serve as a buffer zone that absorbs and cushions the volume expansion stress before it can cause deintercalation or structural failure, thereby maintaining compositional stability despite high silicon content

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

3Reliability

If volume expansion is accommodated in cell design, then degradation is reduced, but energy density per unit volume is significantly decreased

Engineering Contradiction:

Improveperformance degradation resistanceVSAvoidenergy density per unit volume

Core Design Contradiction:

ReliabilityVSQuantity of substance

Solution Approach 1:

Different regions of the negative electrode are assigned different functions: the coated portion provides high capacity through silicon-based active material, while the uncoated portion provides stress relief and structural stability. This local differentiation allows simultaneous optimization of capacity and lifespan characteristics

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

Instead of providing full coverage with active material, only a portion of the current collector is coated, leaving an uncoated portion to handle volume expansion. This partial action approach prevents degradation while minimizing the impact on energy density by limiting the non-active material area

Inventive Principle:

Principle #16Partial or excessive action

Data Source

PatentUS20260094802A1Lithium Secondary Battery Including Negative Electrode Having Improved Resistance to Degradation, and Method for Manufacturing Same

Publication Date: 2026.04.02 SK ON CO LTD

AI summary

The present invention relates to a lithium secondary battery having excellent lifespan characteristics by including a negative electrode improved in protection against degradation due to volume expansion of a negative electrode active material at the time of charging and discharging the lithium secondary battery, and a method of manufacturing the same.