Battery Electrode Assembly Pressing for Electrolyte Impregnation
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Solution Overview
Problem
The existing methods for producing non-aqueous electrolyte secondary battery electrode assemblies face challenges in achieving optimal electrode formability and electrolyte impregnation, as high-temperature hot pressing can lead to excessive adhesion between electrode plates and separators, causing electrolyte solution impregnation degradation and pore collapse in porous films.
Innovation Solution
A method involving the preparation of positive and negative electrode plates with a separator having an adhesive layer, pressed at a temperature not exceeding the glass transition point of the adhesion resin and at pressures between 8 to 20 MPa, ensuring proper adhesion and maintaining porosity in porous films, thereby enhancing electrode assembly formability and electrolyte impregnation characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If hot pressing is performed at a relatively high temperature (60 to 120°C), then adhesion force between the electrode plate and the separator is enhanced, but adhesion force becomes too great causing degradation of impregnation of the non-aqueous electrolyte solution
Solution Approach 1:
The patent applies parameter changes by controlling the pressing temperature to be below the glass transition temperature of the adhesion resin, and by controlling the adhesion resin content to be 3 mass% or less. This resolves the contradiction by finding optimal parameter values that provide sufficient adhesion force while preventing excessive adhesion that would block electrolyte impregnation.
2Ease of manufacture
If the stack is pressed at a relatively high temperature, then electrode assembly formability is enhanced, but pores in the porous film collapse causing degradation of impregnation of the non-aqueous electrolyte solution
Solution Approach 1:
The patent resolves this contradiction by changing the temperature parameter to be below the glass transition temperature of the adhesion resin. This maintains sufficient formability through controlled adhesion while preventing pore collapse that would occur at higher temperatures, thereby preserving electrolyte impregnation capability.
3Strength
If adhesion resin content is increased, then adhesion force is enhanced, but liquid-injection characteristics and liquid-impregnation characteristics are degraded
Solution Approach 1:
The patent applies parameter changes by optimizing the adhesion resin content to be 3 mass% or less. This parameter optimization provides sufficient adhesion force for electrode assembly formation while preventing excessive resin content from blocking the pores and degrading liquid impregnation characteristics.
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 approach allows for improved electrode assembly formability and effective impregnation of the non-aqueous electrolyte solution, reducing the risk of electrolyte solution degradation and maintaining porosity in porous films, thus enhancing the liquid-injection and liquid-impregnation characteristics of the battery.
Implementation Method 1
the adhesion resin becomes adhesive upon heating and is provided on at least one side of the base material
Implementation Method 2
pressing the stack at a temperature not higher than a glass transition point of the adhesion resin
Data Source
AI summary
The present disclosure relates to a method of producing an electrode assembly for a non-aqueous electrolyte secondary battery, comprising a pressing step that involves pressing a stack including a positive electrode plate, a negative electrode plate, and a separator, in which the separator comprises a base material and an adhesive layer, and the adhesive layer is placed on at least one side of the base material and includes an adhesion resin, at a temperature not higher than a glass transition point of the adhesion resin and at a pressure from 8 to 20 MPa to obtain an electrode assembly for a non-aqueous electrolyte secondary battery, wherein an area ratio of the adhesive layer to the base material in a plan view of the separator is from 10 to 70%.