Zigzag-Cut Metal Foil Current Collector for Silicon Anode Bonding

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Solution Overview

Problem

Existing lithium secondary batteries face issues with uneven active material coating due to differing surface roughness of electrolytic copper foils, leading to decreased capacity and unstable electrode behavior, and silicon-based anode active materials experience significant volume changes causing separation from the current collector, resulting in reduced battery lifespan and efficiency.

Innovation Solution

A metal foil for current collectors is designed with a zigzag arrangement of cutting lines, satisfying specific relational expressions for distance and overlap, allowing for a mesh-type current collector with enhanced bonding strength and volume change tolerance, manufactured through eco-friendly processes.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If electrolytic copper foil is used as anode current collector, then manufacturing cost is reduced, but surface roughness difference between opposite surfaces causes uneven active material coating and decreased battery performance

Engineering Contradiction:

Improvemanufacturing costVSAvoidsurface roughness uniformity

Core Design Contradiction:

Ease of manufactureVSManufacturing precision

Solution Approach 1:

The patent applies asymmetry by intentionally creating different surface roughness characteristics on opposite surfaces of the copper foil through selective mechanical processing. One surface is processed to have higher roughness while the other maintains lower roughness, allowing each surface to be optimized for its specific function - one for better active material bonding and the other for uniform coating application.

Inventive Principle:

Principle #4Asymmetry

2Duration of action of moving object

If silicon-based anode active material is used, then charge/discharge cycle characteristics are improved, but significant volume change of 300% or more causes peeling and separation from current collector, reducing battery lifespan

Engineering Contradiction:

Improvecharge/discharge cycle characteristicsVSAvoidbonding strength between active material and current collector

Core Design Contradiction:

Duration of action of moving objectVSStrength

Solution Approach 1:

The patent applies local quality by creating different surface roughness characteristics on different regions (opposite surfaces) of the current collector. This allows each surface to have locally optimized properties - one surface with higher roughness provides enhanced mechanical interlocking and bonding strength for the silicon-based active material, while the other surface maintains lower roughness for uniform coating application.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent applies beforehand cushioning by pre-processing one surface of the copper foil to have higher roughness before active material deposition. This pre-created surface topology provides mechanical interlocking capability that cushions and absorbs the stress from the 300% volume change of silicon-based active material during charging and discharging, preventing peeling and separation.

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

3Strength

If mesh-type current collector is manufactured, then bonding strength with active material is enhanced, but slight differences in active material coating amounts on opposite surfaces may affect battery characteristics

Engineering Contradiction:

Improvebonding strength with active materialVSAvoidcoating amount uniformity

Core Design Contradiction:

StrengthVSManufacturing precision

Solution Approach 1:

The patent applies local quality by creating different surface roughness characteristics on different surfaces of the mesh-type current collector. This allows each surface to have locally optimized properties for its specific function, so even if coating amounts differ slightly, each surface performs optimally for its role in the battery structure.

Inventive Principle:

Principle #3Local quality

Data Source

PatentEP4641681A1Metal foil for current collector, current collector for secondary battery manufactured using same, and secondary battery comprising same

Publication Date: 2025.10.29 VOLTA ENERGY SOLUTIONS SARL

Figure 1~2
Figure 3

AI summary

The present invention relates to a metal foil for current collectors, a current collector for batteries, and a secondary battery including the same, the metal foil for current collectors including: a first cut portion including a plurality of first cutting lines spaced apart from each other in a first direction; and a second cut portion including a plurality of second cutting lines spaced apart from each other in the first direction, wherein the first cut portion and the second cut portion are each provided in plural, and are alternately disposed parallelly while being spaced apart from each other in a second direction perpendicular to the first direction, the plurality of first cutting lines and the plurality of second cutting lines are spaced apart from each other in a zigzag arrangement such that end portions of respective cutting lines overlap each other to have an overlap portion, and the metal foil satisfies predetermined relational expressions 1 and 2.