LFP Cathode Solvent Absorption for Stronger Current Collector Adhesion

Solution Overview

Problem

Lithium iron phosphate positive electrodes with small particle sizes face challenges in adhesion strength due to low intercalation/de-intercalation rates, leading to capacity reduction and potential short circuits, and existing solutions increase production costs or decrease energy density.

Innovation Solution

A manufacturing method for lithium iron phosphate positive electrodes that involves forming a positive electrode active material layer on a current collector and absorbing an organic solvent, such as N-Methyl-2-pyrrolidone or propylene carbonate, to enhance adhesion strength without increasing drying time or binder content.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Speed

If the particle size of lithium iron phosphate is reduced to improve intercalation/de-intercalation rate, then charging/discharging performance is improved, but adhesion strength with current collector decreases

Engineering Contradiction:

Improveintercalation/de-intercalation rateVSAvoidadhesion strength

Core Design Contradiction:

SpeedVSStrength

Solution Approach 1:

The patent applies local quality by creating a binder-rich interface layer at the contact region between the active material layer and current collector. This localized modification ensures small particles maintain strong adhesion at the critical interface without requiring overall particle size increase, thus preserving high intercalation/de-intercalation rates while improving adhesion strength.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent changes the binder content parameter specifically at the interface region between the active material layer and current collector. By increasing binder content locally at this interface rather than uniformly throughout the electrode, the patent achieves improved adhesion strength for small particles while maintaining the overall electrode performance and energy density.

Inventive Principle:

Principle #35Parameter changes

2Strength

If binder content is increased to improve adhesion strength, then electrode adhesion is improved, but resistance characteristics and energy density decrease

Engineering Contradiction:

Improveadhesion strengthVSAvoidenergy density

Core Design Contradiction:

StrengthVSLoss of energy

Solution Approach 1:

The patent applies local quality by creating a binder-rich interface layer at the contact region between the active material layer and current collector. This localized modification ensures small particles maintain strong adhesion at the critical interface without requiring overall particle size increase, thus preserving high intercalation/de-intercalation rates while improving adhesion strength.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent changes the binder content parameter specifically at the interface region between the active material layer and current collector. By increasing binder content locally at this interface rather than uniformly throughout the electrode, the patent achieves improved adhesion strength for small particles while maintaining the overall electrode performance and energy density.

Inventive Principle:

Principle #35Parameter changes

3Strength

If drying time is increased to improve binder migration control, then adhesion strength is improved, but production cost increases

Engineering Contradiction:

Improveadhesion strengthVSAvoiddrying time

Core Design Contradiction:

StrengthVSLoss of time

Solution Approach 1:

The patent applies preliminary action by pre-forming a binder-rich interface layer during the coating process itself, before the drying step. This is achieved by controlling binder migration during coating to accumulate binder at the current collector interface. As a result, sufficient adhesion strength is achieved without requiring extended drying times, thereby reducing production costs.

Inventive Principle:

Principle #10Preliminary action

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 method improves adhesion strength between the electrode active material and current collector, preventing defects like capacity reduction and short circuits, while maintaining energy density and reducing production costs.

Implementation Method 1

a step of absorbing an organic solvent into the positive electrode active material layer

Methodology Applied

Scientific EffectAbsorption: Absorption (physical)

Data Source

PatentUS20240097126A1Method For Manufacturing Cathode For Lithium Secondary Battery, Cathode Manufactured Using Same, And Lithium Secondary Battery Comprising Same

Publication Date: 2024.03.21 LG ENERGY SOLUTION LTD

AI summary

A manufacturing method of a positive electrode for a lithium secondary battery includes: a step of preparing a positive electrode in which a positive electrode active material layer including a lithium iron phosphate formed on a current collector; and a step of adsorbing an organic solvent to the positive electrode active material layer, the organic solvent including one or more of N-methyl-2-pyrrolidone (NMP), acetone, ethanol, propylene carbonate, ethylmethyl carbonate, ethylene carbonate, and dimethyl carbonate.