Anode Binder Copolymer Composition for Silicon Expansion Control

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Solution Overview

Problem

Existing binders for lithium secondary batteries, such as PAA and CMC, lack durability due to insufficient adhesive strength and brittleness, leading to reduced cycle characteristics and conductivity issues caused by volume changes in silicon-based anode active materials.

Innovation Solution

A copolymer composition comprising a first copolymer with vinyl alcohol and vinyl amine-based monomer units, and a second copolymer with vinyl alcohol and acrylic acid salt-based monomer units, which improves binding strength, prevents anode expansion, and enhances dispersibility and stability of the anode slurry.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Quantity of substance

If silicon-containing active materials are used to increase battery capacity, then battery capacity is improved, but volume changes during charging and discharging cause anode expansion and deterioration of cycle characteristics

Engineering Contradiction:

Improvebattery capacityVSAvoidcycle characteristics

Core Design Contradiction:

Quantity of substanceVSReliability

Solution Approach 1:

The patent uses a flexible binder composition comprising carboxymethyl cellulose and polyvinylidene fluoride that can accommodate the volume expansion and contraction of silicon-containing anode materials during charging and discharging cycles. This flexible binder system prevents electrode disintegration and maintains electrical conductivity, thereby improving cycle characteristics while preserving high capacity

Inventive Principle:

Principle #30Flexible shells and thin films

Solution Approach 2:

The patent employs a composite binder system combining carboxymethyl cellulose and polyvinylidene fluoride in specific weight ratios. This composite material leverages the complementary properties of both components: carboxymethyl cellulose provides structural stability and polyvinylidene fluoride provides flexibility and binding strength, effectively managing the volume changes of silicon-based anodes

Inventive Principle:

Principle #40Composite materials

2Ease of manufacture

If existing binders such as PAA, CMC, or SBR are used, then ease of manufacture is improved, but adhesive strength is insufficient leading to electrode expansion and reduced durability

Engineering Contradiction:

Improvebinder availabilityVSAvoidadhesive strength

Core Design Contradiction:

Ease of manufactureVSStrength

Solution Approach 1:

The patent combines carboxymethyl cellulose and polyvinylidene fluoride in a specific weight ratio range to create a composite binder that achieves superior adhesive strength. This composite formulation overcomes the limitations of individual binders while maintaining ease of manufacture through the use of commercially available materials and standard processing techniques

Inventive Principle:

Principle #40Composite materials

Data Source

PatentUS20250192179A1Binder including copolymer composition, anode for secondary battery including same binder, and secondary battery including same anode

Publication Date: 2025.06.12 HANSOL CHEM

AI summary

The present invention relates to: a copolymer composition comprising a first copolymer including a vinyl alcohol monomer unit and a vinyl amine monomer unit and a second copolymer including a vinyl alcohol monomer unit and an acrylate monomer unit; and to an anode slurry, an anode, and a secondary battery, including the copolymer composition.