Secondary Battery Electrode Assembly With Low-Binder Ceramic Separator
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Solution Overview
Problem
Existing secondary batteries face challenges with increased resistance and decreased cell stiffness due to excessive binder use in ceramic coating layers, leading to misalignment of electrodes and reduced energy density.
Innovation Solution
A method for manufacturing a secondary battery involving an electrode assembly with alternately laminated electrodes and separators, using a gel polymer electrolyte composition with specific inorganic particle and binder ratios, and an adhesive containing a first oligomer compound to enhance adhesion and cure the electrolyte, thereby reducing resistance and improving stiffness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the binder content in the ceramic coating layers is reduced to prevent excessive resistance, then resistance decreases, but cell stiffness deteriorates due to poor adhesion between electrode and separator
Solution Approach 1:
The invention changes the chemical composition parameters of the adhesive from conventional binders to oligomer compounds with specific functional groups. This parameter change enables effective adhesion between electrode and separator while using minimal amounts (0.1-5 wt%), thus reducing resistance loss without compromising cell stiffness.
Solution Approach 2:
The invention uses a composite adhesive system comprising oligomer compounds with specific functional groups that combine the benefits of low resistance with strong adhesion properties. This composite material approach allows the adhesive to perform multiple functions: bonding electrode to separator, maintaining cell stiffness, and minimizing resistance.
2Reliability
If a large amount of binder is used in the ceramic coating layers to ensure adhesion between electrode and separator, then adhesion improves, but resistance increases and energy density decreases
Solution Approach 1:
The invention replaces conventional high-binder-content ceramic coating layers with a minimal adhesive application. The adhesive is applied in such small amounts (0.1-5 wt% of total separator weight) that it acts as a localized bonding agent rather than a bulk material, significantly reducing resistance while maintaining adhesion.
Solution Approach 2:
The invention fundamentally changes the adhesive material parameters from conventional binders to oligomer compounds with specific functional groups. This parameter change enables the adhesive to achieve superior bonding efficiency, providing reliable adhesion with minimal material content, thus reducing resistance without compromising reliability.
3Strength
If the thickness of the separator is increased to improve mechanical strength, then cell stiffness improves, but energy density of the battery decreases
Solution Approach 1:
The invention uses a thin adhesive film (oligomer compound) instead of thick conventional binders to achieve the necessary mechanical strength. This thin film approach maintains cell stiffness while minimizing the separator thickness, thereby preserving battery energy density.
Solution Approach 2:
The invention employs a composite structure where the oligomer-based adhesive provides mechanical reinforcement without adding significant thickness. The composite nature of the adhesive (combining oligomer chains with functional groups) enables high strength-to-thickness ratio, maintaining cell stiffness while minimizing energy density loss.
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 method results in a secondary battery with reduced resistance and enhanced mechanical durability by minimizing binder content in ceramic coating layers and utilizing a gel polymer electrolyte to compensate for stiffness loss, ensuring proper electrode alignment and improved energy density.
Implementation Method 1
curing the gel polymer electrolyte composition
Implementation Method 2
an adhesive is applied to the surface of at least one among the electrodes and the separator, thereby allowing the electrodes and the separator to adhere to each other
Data Source
AI summary
According to an aspect of the present invention, there is provided a method for manufacturing a secondary battery, the method including: preparing an electrode assembly in which electrodes and a separator are alternately laminated, and an adhesive is applied to the surface of at least one among the electrodes and the separator, thereby allowing the electrodes and the separator to adhere to each other; accommodating the electrode assembly in a battery case; injecting a gel polymer electrolyte composition into the battery case to impregnate the electrode assembly with the gel polymer electrolyte composition; and curing the gel polymer electrolyte composition, wherein the adhesive includes a first oligomer compound, the separator includes a porous substrate and ceramic coating layers disposed on both surfaces of the porous substrate, the ceramic coating layers include 92-100 wt % (exclusive of 100) of inorganic particles and 0-8 wt % (exclusive of 0) of a binder, and the gel polymer electrolyte composition includes a lithium salt, an organic solvent, a polymerization initiator, and a second oligomer compound.