LiFePO4-Coated Separator for Thermal Stability in Lithium Batteries

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Solution Overview

Problem

Lithium batteries face challenges in achieving high discharge capacity, energy density, and cycle characteristics, particularly due to issues with thermal stability and short-circuiting, which are exacerbated by the melting of organic particles in the separator at high temperatures, leading to rapid temperature increases and instability.

Innovation Solution

A separator is designed with a substrate having a first layer of LiFePO4 particles and a second layer of organic particles with a melting point between 100°C to 130°C, which enhances thermal stability and penetration stability by blocking pores and suppressing side reactions, thereby improving the battery's thermal and life characteristics.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Stability of the object's composition

If organic particles are used in the separator to block pores and improve thermal stability, then thermal stability is improved, but at high temperatures the organic particles melt causing rapid temperature increase and instability

Engineering Contradiction:

Improvethermal stabilityVSAvoidstability at high temperature

Core Design Contradiction:

Stability of the object's compositionVSReliability

Solution Approach 1:

The patent changes the chemical composition parameters of the separator by incorporating LiFePO4 particles with specific crystal structure and surface properties. This modifies the thermal behavior of the separator system, allowing it to maintain stability at temperatures where conventional organic particles would melt and fail.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent creates a composite separator structure combining LiFePO4 particles with organic binder materials. This composite approach leverages the high thermal stability of LiFePO4 (inorganic component) while maintaining the pore-blocking and adhesive properties of organic materials, resolving the contradiction between thermal stability and high-temperature reliability.

Inventive Principle:

Principle #40Composite materials

2Stability of the object's composition

If the separator uses conventional organic particles for pore blocking, then pore blocking capability is improved, but adhesion between separator and electrodes deteriorates

Engineering Contradiction:

Improvepore blocking capabilityVSAvoidadhesion between separator and electrode

Core Design Contradiction:

Stability of the object's compositionVSStrength

Solution Approach 1:

The patent develops a composite coating layer containing LiFePO4 particles combined with organic binder materials. The LiFePO4 particles provide excellent pore blocking capability due to their size and distribution, while the organic binder component ensures strong adhesion to electrode surfaces, simultaneously achieving both requirements.

Inventive Principle:

Principle #40Composite materials

Solution Approach 2:

The patent creates a coating layer with non-uniform distribution of LiFePO4 particles, concentrating them in regions where pore blocking is most critical while maintaining adequate organic binder content in areas requiring strong adhesion. This local optimization allows different regions of the separator to excel at different functions.

Inventive Principle:

Principle #3Local quality

3Stability of the object's composition

If LiFePO4 particles are added to the separator to improve thermal stability, then thermal stability is improved, but device complexity increases

Engineering Contradiction:

Improvethermal stabilityVSAvoidseparator structure complexity

Core Design Contradiction:

Stability of the object's compositionVSDevice complexity

Solution Approach 1:

The patent merges the thermal stabilization function with the existing separator coating layer by incorporating LiFePO4 particles into the coating formulation. This integration approach adds thermal stability functionality without creating a completely separate structural component, thereby limiting the increase in device complexity.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The patent modifies the compositional parameters of the existing separator coating by adding LiFePO4 particles at controlled concentrations and sizes. This parameter-based approach allows systematic optimization of thermal stability while maintaining compatibility with existing separator manufacturing processes and structures.

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 proposed separator structure improves thermal stability, reduces the risk of short-circuits, and enhances the battery's overall performance by maintaining stability and extending its life characteristics, even under normal operating conditions.

Implementation Method 1

a second layer, the first layer having LiFePO4 (LFP) particles, and the second layer having organic particles with a melting point (Tm) in a range of about 100° C. to about 130° C.

Methodology Applied

Scientific EffectMelting: Melting

Data Source

PatentUS11527801B2Separator including substrate, first layer with lithium iron phosphate particles, and second layer with organic particles, and lithium battery including the same

Publication Date: 2022.12.13 SAMSUNG SDI CO LTD

AI summary

A separator includes a substrate, a first layer on the substrate, the first layer including LiFePO4 (LFP) particles, and a second layer on the substrate, the second layer including organic particles having a melting point in a range of about 100° C. to about 130° C.