Electrode Sheet Roll Pressing to Prevent Peeling and Roll Adhesion
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Solution Overview
Problem
In the production of electrode sheets, a part of the electrode layer may peel off from the current collecting foil, causing the binder resin and active material particles to adhere to the roll surface, or a peeled part of the electrode layer may lift up from the current collecting foil without adhering to the roll surface.
Innovation Solution
A method for producing an electrode sheet involves roll-pressing an uncompressed electrode sheet with specific temperature conditions for the rolls, where the first roll's outer peripheral surface temperature is set between the melting start temperature of the binder resin +5°C to +25°C, and the second roll's temperature is lower than the first roll's temperature and within or below the melting start temperature of the binder resin +5°C, to ensure proper bonding of active material particles to the current collecting foil without excessive adhesion to the rolls.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the roll-pressing temperature is increased to improve bonding strength, then the bonding between active material particles and current collecting foil is enhanced, but the binder resin and active material particles adhere to the roll surface causing peeling defects
Solution Approach 1:
The patent applies different temperatures to different parts of the rolling system: the first rolling unit (first roll) operates at a higher temperature (Ti+5°C to Ti+25°C) to ensure strong bonding at the interface between the electrode layer and current collecting foil, while the second rolling unit (second roll) operates at a lower temperature (≤Ti+5°C) to prevent adhesion to the roll surface. This local differentiation of temperature conditions resolves the contradiction between achieving strong bonding and preventing harmful adhesion.
Solution Approach 2:
The rolling process is divided into two distinct stages with two separate rolling units, each performing a different function: the first rolling unit provides heating and initial bonding, while the second rolling unit provides compression without excessive heating. This segmentation allows each unit to be optimized for its specific function, preventing the binder resin and active material particles from adhering to the roll surface while still achieving strong bonding.
2Ease of operation
If uniform temperature is applied to both rolls to simplify control, then the process is easier to manage, but bonding quality deteriorates due to either insufficient heating or excessive adhesion
Solution Approach 1:
Instead of applying uniform temperature to both rolls, the patent implements local quality by setting different temperature conditions for the first and second rolling units. The first roll is heated to Ti+5°C to Ti+25°C for optimal bonding, while the second roll is maintained at ≤Ti+5°C to prevent adhesion. This differentiated approach ensures high bonding quality while remaining operationally manageable through clear temperature specifications for each unit.
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 effectively prevents the electrode layer from peeling off during the roll-pressing process, ensuring strong bonding of the active material particles to the current collecting foil and preventing adhesion to the rolls, thereby producing a high-quality electrode sheet.
Implementation Method 1
heating the uncompressed electrode sheet in the roll gap so that the active material particles are bonded to each other through the binder resin and the active material particles are bonded to the second surface of the current collecting foil through the binder resin
Implementation Method 2
the first outer peripheral surface temperature set to fall within a temperature range from a melting start temperature of the binder resin +5° C. to the melting start temperature +25° C.
Implementation Method 3
compress the uncompressed electrode sheet in a thickness direction
Implementation Method 4
the active material particles are bonded to each other through the binder resin and the active material particles are bonded to the second surface of the current collecting foil through the binder resin
Data Source
AI summary
A method for producing an electrode sheet includes roll-pressing an uncompressed electrode sheet including a current collecting foil and an uncompressed electrode layer formed thereon and made from composite particles including active material particles and binder particles, by feeding the uncompressed electrode sheet to pass through a gap between first and second rolls to compress, and heating the sheet so that the active material particles are bonded to each other and also to the current collecting foil. A first outer peripheral surface temperature of the first roll contacting the foil falls within a temperature range from a binder-resin melting start temperature +5° C. to +25° C., and a second outer peripheral surface temperature of the second roll contacting the uncompressed electrode layer is lower than the first outer peripheral surface temperature and further falls within a temperature range not exceeding the melting start temperature +5° C.