Dual-Filler Battery Separator for Ion Shutdown Under Heat

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Solution Overview

Problem

Conventional separators for nonaqueous electrolyte secondary batteries often fail to sufficiently interrupt ion conduction between positive and negative electrodes during abnormal heat generation, leading to inadequate suppression of further heat generation.

Innovation Solution

A separator with a layered structure comprising a substrate, a first filler layer containing phosphate salt particles on one side, and a second filler layer containing inorganic particles with a higher melting point on the other side, is used. The first filler layer is directed towards the positive electrode side, with a BET specific surface area of the phosphate salt particles ranging from 5 m2/g to 100 m2/g.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a separator with a single filler layer containing inorganic particles is used, then the internal resistance of the battery is reduced and capacity is enhanced, but the separator cannot sufficiently interrupt ion conduction during abnormal heat generation

Engineering Contradiction:

Improveshutdown functionVSAvoidseparator structure

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The separator is divided into multiple functional layers: a substrate layer and two filler layers (first filler layer with phosphate salt particles on the positive electrode side, second filler layer with inorganic particles on the negative electrode side). This segmentation allows each layer to perform its specific function - the substrate provides structural support and baseline shutdown function, while the filler layers enhance ion conduction during normal operation and improve shutdown effectiveness during abnormal heat generation.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different filler materials are strategically placed at different locations within the separator structure. The first filler layer containing phosphate salt particles is positioned on the positive electrode side where it can effectively interrupt ion conduction during thermal runaway, while the second filler layer with high-melting-point inorganic particles is positioned on the negative electrode side to maintain structural integrity at high temperatures. This local differentiation optimizes the shutdown function at each interface.

Inventive Principle:

Principle #3Local quality

2Reliability

If the BET specific surface area of phosphate salt particles is increased to improve ion conduction interruption, then the shutdown function is enhanced, but the particle aggregation may occur reducing manufacturing precision

Engineering Contradiction:

Improveion conduction interruptionVSAvoidparticle distribution uniformity

Core Design Contradiction:

ReliabilityVSManufacturing precision

Solution Approach 1:

The BET specific surface area of the phosphate salt particles is precisely controlled within the range of 5 m²/g to 100 m²/g. This parameter optimization ensures that the particles have sufficient surface area to effectively interrupt ion conduction during thermal events while maintaining adequate dispersion characteristics that prevent aggregation during the coating and drying processes. The specific surface area range balances reactive surface area with manufacturability.

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

This configuration effectively interrupts ion conduction and suppresses exothermic reactions during abnormal heat events, preventing further heat generation in the battery.

Implementation Method 1

the phosphate salt particles contained in the first filler layer are melted and polymerized in an accelerated manner by heat

Methodology Applied

Scientific EffectMelting: Melting

Implementation Method 2

the phosphate salt particles contained in the first filler layer are melted and polymerized in an accelerated manner by heat

Methodology Applied

Scientific EffectPolymerization:

Implementation Method 3

a second filler layer disposed on the other side of the substrate and containing inorganic particles with a higher melting point than the phosphate salt particles

Methodology Applied

Scientific EffectThermal resistance:

Data Source

PatentUS12224452B2Nonaqueous electrolyte secondary battery including separator with filler layers on opposite sides of substrate

Publication Date: 2025.02.11 PANASONIC INTELLECTUAL PROPERTY MANAGEMENT CO LTD

AI summary

In a nonaqueous electrolyte secondary battery, a separator includes a substrate, a first filler layer disposed on one side of the substrate and containing phosphate salt particles, and a second filler layer disposed on the other side of the substrate and containing inorganic particles. The separator is disposed between a positive electrode and a negative electrode in such a manner that the side of the substrate which bears the first filler layer is directed to the positive electrode side.