Crosslinked Anode Binder Composition for Silicon Expansion Control

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Solution Overview

Problem

Existing lithium secondary batteries using silicon-based negative electrode active materials face significant volume expansion during charging and discharging, leading to disconnected conductive paths and deteriorated battery performance, which current binder polymers fail to adequately address.

Innovation Solution

A thermally crosslinkable negative electrode binder solution comprising an epoxy resin with four or more epoxy functional groups and a water-soluble macromolecular polymer containing a carboxyl group is used, allowing crosslinking during the electrode manufacturing process to suppress volume change and maintain electrode thickness.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If silane-modified polyethylene crosslinking reaction is promoted in the extruder using a crosslinking catalyst master batch, then crosslinking reaction efficiency is improved, but resin aggregates are generated and homogeneity of physical properties deteriorates

Engineering Contradiction:

Improvecrosslinking reaction efficiencyVSAvoidhomogeneity of physical properties

Core Design Contradiction:

ProductivityVSManufacturing precision

Solution Approach 1:

The crosslinking process is divided into two separate stages: first, silane grafting occurs during extrusion to modify the polyethylene; second, the actual crosslinking reaction occurs after molding through moisture exposure or heat treatment. This segmentation prevents resin aggregation during extrusion while achieving the desired crosslinked structure in the final product, thereby maintaining both production efficiency and material homogeneity.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The silane modification is performed as a preliminary action during the extrusion process, preparing the polyethylene for subsequent crosslinking without completing the full crosslinking reaction at that stage. This preliminary grafting allows the resin to remain processable during molding, while the crosslinking structure develops later under controlled conditions, ensuring uniform physical properties.

Inventive Principle:

Principle #10Preliminary action

2Quantity of substance

If anode potential is lowered to increase lithium ion insertion capacity, then battery capacity is improved, but lithium metal deposition occurs during charging

Engineering Contradiction:

Improvelithium ion insertion capacityVSAvoidlithium metal deposition

Core Design Contradiction:

Quantity of substanceVSReliability

Solution Approach 1:

The anode is designed with heterogeneous structure consisting of different regions: conductive carbon matrix providing electron transport pathways, and lithium ion insertion/extraction sites providing ionic pathways. This local differentiation allows the anode to accommodate lithium ions at multiple potentials, preventing uniform lithium metal deposition while maintaining high capacity. The separated pathways for electrons and lithium ions reduce the driving force for unwanted lithium plating.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

Silane-modified crosslinked polyethylene acts as an intermediary material that mediates between lithium ion insertion and electron conduction. The crosslinked network structure provides controlled lithium ion pathways while the silane groups enhance electrolyte wettability and ion transport. This intermediary structure regulates lithium ion flow, preventing direct electron transfer that would cause lithium metal deposition, while still enabling high lithium ion capacity.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Ease of manufacture

If conventional polyethylene is used as binder, then manufacturing simplicity is maintained, but lithium ion permeability is insufficient

Engineering Contradiction:

Improvemanufacturing simplicityVSAvoidlithium ion permeability

Core Design Contradiction:

Ease of manufactureVSReliability

Solution Approach 1:

The polyethylene binder undergoes chemical modification through silane grafting and crosslinking, fundamentally changing its physical and chemical parameters. The crosslinked network structure creates interconnected pores and channels that dramatically improve lithium ion permeability. Meanwhile, the silane groups enhance electrolyte affinity and ion transport properties. These parameter changes are achieved through standard extrusion and molding processes, maintaining manufacturing simplicity while transforming the binder's performance characteristics.

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

The solution effectively minimizes electrode thickness changes and enhances capacity retention by stabilizing the negative electrode structure, improving the lifespan and performance of lithium secondary batteries.

Implementation Method 1

silane-modified polyethylene crosslinking reaction

Methodology Applied

Scientific EffectCrosslinking reaction: Chemical Bonding

Implementation Method 2

insertion and extraction of lithium ions

Methodology Applied

Scientific EffectLithium ion insertion and extraction: Electrochemiluminescence

Implementation Method 3

conductive master batch

Methodology Applied

Scientific EffectConduction: Conduction (electrical)

Data Source

PatentEP4365983B1Anode composition, anode for lithium secondary battery comprising same, and lithium secondary battery comprising anode

Publication Date: 2026.04.15 LG ENERGY SOLUTION LTD

Figure 1~2

AI summary

Disclosed is to a negative electrode composition, a negative electrode for a lithium secondary battery including the same, and a lithium secondary battery including a negative electrode.