Positive Electrode Safety Layer for Penetration-Resistant Li Batteries

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Rechargeable lithium batteries are prone to internal heat generation and ignition due to short circuits caused by sharp object penetration or exposure to high temperatures, which can lead to safety hazards.

Innovation Solution

A positive electrode design incorporating a safety functional layer with a lithium iron phosphate-based compound and an endothermic material, including a composite of metal hydroxide and phosphorus-based flame retardant, to reduce current and absorb heat, respectively, thereby preventing ignition.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a conventional positive electrode structure is used, then the battery structure is simple, but the battery is prone to internal heat generation and ignition under sharp object penetration or high temperature exposure

Engineering Contradiction:

Improvesafety under penetration or high temperatureVSAvoidpositive electrode structure

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The positive electrode is segmented into multiple functional layers: a current collector, a safety functional layer containing lithium iron phosphate-based compound, and a positive electrode active material layer. This segmentation allows each layer to perform its specific function (current collection, safety protection, and electrochemical activity) independently, improving reliability without excessive complexity.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

A safety functional layer is introduced as an intermediary between the current collector and the positive electrode active material layer. This intermediate layer contains lithium iron phosphate-based compound that provides thermal stability and prevents direct contact between the current collector and active material under extreme conditions, thereby preventing internal heat generation and ignition.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Object-affected harmful factors

If the positive electrode active material layer is placed directly on the current collector, then the electrode structure is simple, but short circuit occurs causing internal heat generation when sharp objects penetrate

Engineering Contradiction:

Improveinternal heat generation from short circuitVSAvoidpositive electrode layer structure

Core Design Contradiction:

Object-affected harmful factorsVSDevice complexity

Solution Approach 1:

The safety functional layer is placed beforehand between the current collector and the positive electrode active material layer to cushion against potential short circuits. This layer acts as a protective barrier that prevents direct contact between conductive components when sharp objects penetrate the battery, thereby preventing internal heat generation before it can occur.

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

Solution Approach 2:

The lithium iron phosphate-based compound in the safety functional layer has inherent thermal stability and electrical resistance properties. Under normal conditions, it provides structural support, but under penetration conditions, these same properties prevent short circuits and heat generation, converting the potential harm of structural collapse into a beneficial protective effect.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

3Object-affected harmful factors

If high temperature exposure is endured without protection, then the battery structure remains simple, but the positive electrode active material structure collapses generating oxygen radicals

Engineering Contradiction:

Improveoxygen radical generation and electrolyte decompositionVSAvoidpositive electrode protective structure

Core Design Contradiction:

Object-affected harmful factorsVSDevice complexity

Solution Approach 1:

The safety functional layer changes the thermal parameters of the positive electrode system by introducing lithium iron phosphate-based compound with high thermal stability. This material maintains its structural integrity at elevated temperatures, preventing the collapse of the positive electrode active material structure and the subsequent generation of oxygen radicals that would decompose the electrolyte.

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 design effectively suppresses heat generation and ignition in lithium batteries, ensuring safety under conditions of sharp object penetration or high temperature exposure.

Implementation Method 1

a first safety functional layer including a lithium iron phosphate-based compound

Methodology Applied

Scientific EffectElectrical Resistance: Electrical Resistance

Implementation Method 2

a second safety functional layer including an endothermic material

Methodology Applied

Scientific EffectEndothermic Reaction: Endothermic Reaction

Data Source

PatentUS20250329747A1Positive electrodes for reachargeable lithium batteries and rechargeable lithium batteries including the same

Publication Date: 2025.10.23 SAMSUNG SDI CO LTD

AI summary

Disclosed are a positive electrode for a rechargeable lithium battery, and a rechargeable lithium battery including the positive electrode, the positive electrode including a positive electrode current collector; a safety functional layer on the positive electrode current collector, and a positive electrode active material layer on the safety functional layer, wherein the safety functional layer includes a first safety functional layer including a lithium iron phosphate-based compound and a second safety functional layer including an endothermic material.