Porous Membrane for Li-Ion Battery Using Spherical Particles

Solution Overview

Problem

Conventional porous membranes for lithium ion secondary batteries using plate-shaped non-conductive particles face challenges in achieving uniformity, sliding property, and powder fall-off during production, leading to reduced battery performance and safety.

Innovation Solution

A porous membrane and slurry formulation using non-conductive particles with specific dimensions and a binder comprising (meth)acrylonitrile and (meth)acrylate monomer units, along with an aqueous polymer with sulfonic acid groups, which improves particle orientation, sliding property, and storage stability, preventing powder fall-off and enhancing battery safety.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If plate shape particles are used as non-conductive particles, then the porous membrane has better safety and elongation, but the viscosity of the slurry increases and the porous membrane becomes difficult to make thin

Engineering Contradiction:

ImprovesafetyVSAvoidmembrane thickness

Core Design Contradiction:

ReliabilityVSLength of moving object

Solution Approach 1:

The invention changes the shape parameter of non-conductive particles from plate shape to spherical shape, which fundamentally alters the slurry viscosity characteristics and enables thin membrane formation while maintaining safety through proper particle size selection (0.1-20 μm)

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The invention uses spherical particles that can be easily dispersed and processed, replacing the difficult-to-process plate shape particles, enabling more efficient manufacturing of thin membranes

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

2Reliability

If plate shape particles are used as non-conductive particles, then the porous membrane has better safety, but the porous membrane has low sliding property and powder fall-off occurs

Engineering Contradiction:

ImprovesafetyVSAvoidsliding property

Core Design Contradiction:

ReliabilityVSEase of operation

Solution Approach 1:

The invention changes the shape parameter of non-conductive particles from plate shape to spherical shape, which fundamentally alters the slurry viscosity characteristics and enables thin membrane formation while maintaining safety through proper particle size selection (0.1-20 μm)

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The invention uses spherical particles that can be easily dispersed and processed, replacing the difficult-to-process plate shape particles, enabling more efficient manufacturing of thin membranes

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

3Quantity of substance

If the porous membrane is made thin, then the battery capacity increases, but the uniformity of the porous membrane deteriorates

Engineering Contradiction:

Improvebattery capacityVSAvoidmembrane uniformity

Core Design Contradiction:

Quantity of substanceVSManufacturing precision

Solution Approach 1:

The invention changes the shape parameter of non-conductive particles from plate shape to spherical shape, which fundamentally alters the slurry viscosity characteristics and enables thin membrane formation while maintaining safety through proper particle size selection (0.1-20 μm)

Inventive Principle:

Principle #35Parameter changes

Data Source

PatentUS9293753B2Porous membrane for secondary battery, slurry for secondary battery porous membrane and secondary battery

Publication Date: 2016.03.22 ZEON CORP

AI summary

The porous membrane according to the present invention comprises non-conductive particles, a binder, and a water-soluble polymer, and is characterized in that: the three dimensions of the non-conductive particles, namely the length (L), thickness (t), and width (b), are such that the length (L) is 0.1 to 0 μm, the ratio (b/t) of the width (b) and the thickness (t) is 1.5 to 100; the binder is a copolymer containing (meth)acrylonitrile monomer units and (meth)acrylic acid ester monomer units; and the water-soluble polymer contains sulfonic acid groups, and has a weight average molecular weight of 1000 to 15000. The slurry for a porous membrane according to the present invention is characterized by being formed by dispersing the non-conductive particles, the binder, and the soluble polymer, in water. Thus, the present invention provides: a porous membrane that can be formed into a thin film, has an excellent sliding property, and generates few particles; and a slurry for porous membranes which is capable of producing porous membrane easily and quickly, and has excellent storage stability.