Battery Porous Layer Bursting Strength Control

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Solution Overview

Problem

Conventional separators with porous layers in nonaqueous electrolyte secondary batteries, such as lithium-ion batteries, have insufficient initial battery characteristics due to inadequate heat resistance and uneven stress distribution, leading to increased AC resistance during charge and discharge.

Innovation Solution

A nonaqueous electrolyte secondary battery porous layer with a standard deviation of bursting strength between 0.6 and 11.0, incorporating nitrogen-containing aromatic resins like aramid resins and heat-resistant inorganic fillers, is developed to provide moderate unevenness in elasticity, allowing for effective ion permeation and stress distribution.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Temperature

If a porous layer containing heat-resistant component is used in separator, then heat resistance is improved, but initial battery characteristic deteriorates

Engineering Contradiction:

Improveheat resistanceVSAvoidinitial battery characteristic

Core Design Contradiction:

TemperatureVSReliability

Solution Approach 1:

The invention changes the physical parameter of bursting strength standard deviation to a specific range (0.6-11.0) to optimize the porous layer's performance. This parameter control allows the separator to maintain heat resistance while improving initial battery characteristics by regulating the uniformity of stress distribution in the porous structure.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The invention uses composite materials by combining heat-resistant components with other materials to form a porous layer with optimized bursting strength characteristics. This composite approach enables the separator to simultaneously achieve heat resistance and improved initial battery performance through controlled stress distribution.

Inventive Principle:

Principle #40Composite materials

2Temperature

If porous layer with heat-resistant component is used, then heat resistance is improved, but AC resistance increase ratio worsens

Engineering Contradiction:

Improveheat resistanceVSAvoidAC resistance increase ratio

Core Design Contradiction:

TemperatureVSObject-affected harmful factors

Solution Approach 1:

By controlling the standard deviation of bursting strength within the specific range of 0.6-11.0, the invention optimizes the porous layer's mechanical uniformity. This parameter control reduces local expansion during battery operation, thereby decreasing the AC resistance increase ratio while preserving heat resistance properties.

Inventive Principle:

Principle #35Parameter changes

3Temperature

If conventional porous layer is used, then heat resistance is improved, but stress distribution uniformity deteriorates

Engineering Contradiction:

Improveheat resistanceVSAvoidstress distribution uniformity

Core Design Contradiction:

TemperatureVSStability of the object's composition

Solution Approach 1:

The invention optimizes stress distribution uniformity by controlling the standard deviation of bursting strength to fall within 0.6-11.0. This parameter regulation ensures more uniform stress distribution across the porous layer while maintaining heat resistance, preventing localized weak points that would cause uneven stress concentration.

Inventive Principle:

Principle #35Parameter changes

Data Source

PatentUS11594785B2Nonaqueous electrolyte secondary battery porous layer

Publication Date: 2023.02.28 SSLM

AI summary

The present invention provides a nonaqueous electrolyte secondary battery porous layer which improves an initial battery characteristic immediately after initial charge and discharge of a nonaqueous electrolyte secondary battery. In the nonaqueous electrolyte secondary battery porous layer in accordance with an aspect of the present invention, a standard deviation of bursting strength is 0.6 or more and 11.0 or less.