Secondary Battery Assembly Heating for Electrode-Separator Adhesion
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Solution Overview
Problem
Existing methods for manufacturing secondary batteries, such as lithium ion batteries, face challenges in achieving sufficient adhesive strength between the electrode and separator, which can lead to irregular charging and discharging reactions and reduced high-rate characteristics due to compromised air permeability when pressurizing the electrodes and separator.
Innovation Solution
A manufacturing method involving a high temperature treatment step under restraining pressure of at least 0.35 MPa and temperature of at least 80°C, where the battery assembly is bound to satisfy the condition A ≥ B > C, ensuring the peel strength at the interfaces between the separator and electrodes, thereby enhancing adhesive strength without excessive air permeability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If press pressure is strengthened to enhance adhesive strength between electrode and separator, then adhesive strength is improved, but air permeability of separator is increased which hinders ion transfer and reduces high rate characteristics
Solution Approach 1:
The invention changes the temperature parameter to 80°C or higher during the pressing process, which fundamentally alters the adhesive properties of the separator. At this elevated temperature, the separator material becomes more compliant and forms stronger bonds with electrodes, achieving adequate adhesion without requiring excessive press pressure that would compromise air permeability and ion transfer capabilities.
2Strength
If press pressure is strengthened to enhance adhesive strength between electrode and separator, then adhesive strength is improved, but distance between electrodes increases locally causing irregularity of charging and discharging reaction
Solution Approach 1:
By implementing temperature control at 80°C or higher during pressing, the invention enables the separator material to become sufficiently pliable to conform to electrode surfaces and fill gaps uniformly. This thermal parameter change allows achieving uniform electrode spacing and consistent adhesive strength across the entire battery assembly without localized deformations or spacing irregularities.
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 method improves the adhesion between the electrode and separator, maintaining favorable battery performance characteristics like high-rate capabilities and input/output characteristics while preventing peeling and maintaining ion transfer efficiency.
Implementation Method 1
the adhesive strength between the electrode and the separator can be improved... the battery assembly is bound with the adhesive included in the adhesion layer of the separator swollen
Implementation Method 2
the adhesive included in the adhesion layer of the separator swollen... a preferable anchor effect is exhibited between the electrode and the separator
Implementation Method 3
a high temperature treatment step of restraining the battery assembly under a restraining pressure of at least 0.35 MPa or more, and retaining the battery assembly so as to be at least 80°C or more
Data Source
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AI summary
A method for manufacturing a secondary battery herein disclosed includes: an assembly preparing step of accommodating an electrode body and an electrolyte into a battery case, and preparing a battery assembly; and a high temperature treatment step of restraining the battery assembly under a restraining pressure of at least 0.35 MPa or more, and retaining the battery assembly so that the temperature of the battery assembly may become at least 80°C or more. Herein, the high temperature treatment step is carried out so as to satisfy a formula (1): A ≥ B > C; where A (N/m) represents a peel strength at an interface between a separator and a negative electrode active material layer, B (N/m) represents a peel strength at an interface between the negative electrode active material layer and a negative electrode current collector, and C (N/m) represents a peel strength in the negative electrode active material layer.