Phosphorus-Containing Binder for Battery Electrode Adhesion

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Solution Overview

Problem

Conventional binders for secondary battery electrodes, such as PVdF and SBR, fail to provide sufficient adhesion strength and cycle stability, especially when dealing with electrode active materials that undergo significant volume expansion during charging and discharging, leading to decreased battery capacity and lifespan.

Innovation Solution

A binder comprising a copolymer with 79-98% ethylenically unsaturated carbonic acid ester monomer, 1-20% vinyl or nitrile monomer, and 1-20% phosphorus-containing monomer with a P=O bond and reactive double bonds, which enhances adhesion strength and cycle properties through chemical bonding with the electrode material.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional binders like PVdF or SBR are used, then the electrode structure is maintained, but adhesion strength is insufficient and cycle stability deteriorates when electrode active materials undergo volume expansion

Engineering Contradiction:

Improvecycle stabilityVSAvoidadhesion strength

Core Design Contradiction:

ReliabilityVSStrength

Solution Approach 1:

The patent modifies the chemical composition parameters of the binder by incorporating phosphorus-containing monomers with P=O bonds and reactive double bonds into a copolymer structure. This chemical parameter change enables the binder to achieve both strong adhesion to electrode active materials and flexibility to accommodate volume expansion during cycling, resolving the contradiction between adhesion strength and cycle stability.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent creates a composite polymer binder system by combining multiple monomer components: ethylenically unsaturated carbonic acid ester monomer (79-98%), vinyl or nitrile monomer (1-20%), and phosphorus-containing monomer (1-20%). This composite material approach integrates the advantages of each component to achieve superior adhesion strength and cycle stability simultaneously.

Inventive Principle:

Principle #40Composite materials

2Quantity of substance

If materials with high discharge capacity like silicon or tin are used to improve battery capacity, then volume expansion increases during charging and discharging, but this causes isolation of anode material from electrode material

Engineering Contradiction:

Improvedischarge capacityVSAvoidadhesion stability

Core Design Contradiction:

Quantity of substanceVSReliability

Solution Approach 1:

The phosphorus-containing binder creates a flexible interface layer between the electrode active material and current collector. The P=O bond provides strong adhesion while the polymer matrix offers flexibility to accommodate the significant volume expansion of high-capacity materials like silicon and tin during lithiation, preventing material isolation and maintaining electrical contact throughout cycling.

Inventive Principle:

Principle #30Flexible shells and thin films

3Strength

If the binder provides strong adhesion to prevent separation, then volume expansion control is improved, but the binder may cover active material surfaces and deteriorate inherent battery performance

Engineering Contradiction:

Improveadhesion strengthVSAvoidbattery capacity

Core Design Contradiction:

StrengthVSQuantity of substance

Solution Approach 1:

The binder exhibits local quality differentiation through its molecular structure: the P=O bond provides strong adhesion at the interface with electrode active materials, while the polymer chains maintain appropriate flexibility and porosity in the bulk phase. This localized functionality ensures strong binding where needed without excessive coverage that would block active material surfaces and reduce battery capacity.

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

The binder significantly improves adhesion strength and cycle properties, maintaining at least 90% capacity after 50 cycles by inhibiting volume expansion and interface variation, thereby extending battery lifespan and performance.

Implementation Method 1

Methodology Applied

Scientific EffectChemical bonding: Chemical Bonding

Data Source

PatentEP2526582B1Binder for secondary battery providing excellent adhesion strength and cycle property

Publication Date: 2015.04.22 LG CHEM LTD

AI summary

Provided is a binder for secondary battery electrodes comprising a copolymer consisting of 79 to 98% by weight of at least one selected from the group consisting of (a) an ethylenically unsaturated carbonic acid ester monomer and (b) a vinyl monomer and a nitrile monomer, (c) 1 to 20% by weight of an ethylenically unsaturated carbonic acid monomer, and (d) 1 to 20% by weight of a phosphorus (P)-containing monomer including a P=O bond and one or more reactive double bonds in a molecular structure thereof, based on the total weight of the binder. The binder fundamentally improves stability of an electrode in the process of fabricating the electrode, thus providing secondary batteries with superior cycle properties.