Battery Laminate Adhesion Without Functional Layer Re-Dissolution
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Solution Overview
Problem
Non-aqueous secondary batteries with water-soluble polymer-containing functional layers and adhesive layers face reduced peel strength and functional layer performance due to the use of hydrophilic solvents in adhesive layer compositions, leading to suboptimal electrical characteristics.
Innovation Solution
A laminate for non-aqueous secondary batteries is designed with a functional layer containing functional particles and a water-soluble polymer, where the water-soluble polymer forms a film with a water drop contact angle of 30° to 75°, and an adhesive layer with organic particles having a core-shell structure, which enhances adhesion and electrical characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If an adhesive layer composition containing a hydrophilic solvent is applied onto a functional layer containing a water-soluble polymer to form an adhesive layer, then adhesion between electrode and separator is improved, but the water-soluble polymer re-dissolves causing reduced peel strength and functional layer performance
Solution Approach 1:
The patent changes the chemical parameters of the adhesive layer composition by specifying pH control (pH 2-6) and solvent composition (mixed solvent system with hydrophilic and hydrophobic solvents in specific ratios). These parameter changes prevent re-dissolution of the water-soluble polymer while maintaining adhesion, resolving the contradiction between improved adhesion and maintained peel strength.
Solution Approach 2:
The patent uses a composite adhesive layer composition containing multiple solvents (hydrophilic and hydrophobic in specific ratios), binders with specific glass transition temperatures, and optional additives. This composite material approach creates an adhesive layer that provides both strong adhesion and prevents polymer re-dissolution, simultaneously achieving improved adhesion and maintained reliability.
2Strength
If the water-soluble polymer in the functional layer is made more hydrophilic to improve adhesion, then bonding between electrode and separator is enhanced, but the functional layer becomes overly soluble causing loss of function
Solution Approach 1:
The patent controls the pH parameter of the adhesive layer composition (pH 2-6) to prevent re-dissolution of the water-soluble polymer. This parameter control allows the functional layer to maintain its solubility characteristics for adhesion while preventing excessive solubility that would cause functional layer failure.
Solution Approach 2:
The patent introduces a mixed solvent system (hydrophilic and hydrophobic solvents) as an intermediary medium. This intermediary composition allows controlled interaction with the water-soluble polymer to achieve adhesion without causing complete re-dissolution and functional layer failure.
3Strength
If adhesive layer composition with high hydrophilic solvent content is used to maximize adhesion, then bonding strength increases, but functional layer re-dissolution occurs leading to reduced electrical characteristics
Solution Approach 1:
The patent specifies precise parameter ranges for the adhesive layer composition: pH 2-6, hydrophilic solvent 10-80 wt%, hydrophobic solvent 20-90 wt%, and binder glass transition temperature 0-100°C. These controlled parameters ensure optimal bonding strength while preventing functional layer re-dissolution and maintaining electrical characteristics.
Solution Approach 2:
The patent employs a composite adhesive layer composition with balanced proportions of hydrophilic and hydrophobic solvents, multiple binder types, and optional additives. This composite formulation achieves high bonding strength while preventing excessive solubility that would compromise functional layer integrity and electrical 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
The solution effectively suppresses reductions in peel strength and ensures the functional layer exerts its expected function, while improving the electrical characteristics of non-aqueous secondary batteries by maintaining adhesion and ion diffusivity.
Implementation Method 1
a film obtained by shaping of the water-soluble polymer contained in the functional layer has a water drop contact angle of 30° to 75°
Implementation Method 2
adhesive layer compositions prepared by dissolving or dispersing adhesives into hydrophilic solvents such as water
Implementation Method 3
dry the adhesive layer composition applied to form an adhesive layer on the surface of the electrode and/or separator
Data Source
Figure 1
AI summary
Disclosed is a laminate for non-aqueous secondary battery which includes a water-soluble polymer-containing functional layer and an adhesive layer adjacently disposed on the functional layer, and which can suppress reductions in peel strength of a battery member including the laminate while allowing the functional layer to exert its expected function. The disclosed laminate includes a functional layer containing functional particles and a water-soluble polymer, and an adhesive layer adjacently disposed on the functional layer, wherein a film obtained by shaping of the water-soluble polymer has a water drop contact angle of 30° to 80°.