Electrode Drying Control for Crack-Free Lithium-Ion Rewinding
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Solution Overview
Problem
The existing methods for manufacturing lithium ion secondary batteries face challenges in minimizing electrode deformation and cracks due to shrinkage during the drying process, which can lead to wrinkles in uncoated portions when the electrodes are rewound.
Innovation Solution
A system and method for manufacturing lithium ion secondary batteries that involves maintaining the electrode in a specific shape during the initial stages of drying, utilizing a drying device with driving rolls and a drying nozzle that form gradients to control the drying process, and adjusting the air flow based on the degree of drying sensed by a sensor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the electrode is thickened to increase energy density, then the energy storage capacity is improved, but the electrode deformation and crack formation during drying worsens
Solution Approach 1:
The patent applies parameter changes by controlling the drying conditions (temperature, humidity, air flow rate) to match the specific characteristics of thick electrodes. The drying device adjusts these parameters dynamically during the drying process to prevent deformation while maintaining high energy density requirements.
Solution Approach 2:
The patent implements preliminary action by pre-setting the drying parameters before the actual drying process begins. The system pre-configures the drying device with appropriate temperature, humidity, and air flow settings based on the electrode thickness and coating characteristics, preventing deformation before it occurs.
2Strength
If high-performance binder is used to improve electrode adhesion, then the adhesion strength is improved, but the electrode shrinkage during drying worsens
Solution Approach 1:
The patent controls drying parameters (temperature, humidity, air flow) to compensate for the shrinkage effects of high-performance binders. By adjusting these parameters, the system maintains electrode dimensional stability while preserving the strong adhesion properties provided by the binder.
Solution Approach 2:
The drying device acts as an intermediary that mediates between the binder's adhesive properties and the electrode's dimensional stability. Through controlled environmental conditions, it balances the competing effects of strong adhesion and shrinkage resistance.
3Productivity
If the drying temperature is increased to speed up the drying process, then the productivity is improved, but the electrode crack formation worsens
Solution Approach 1:
The patent implements periodic action through multi-stage drying processes with varying temperature and humidity conditions. The drying device cycles through different parameter sets, allowing gradual moisture removal that maintains productivity while preventing thermal shock and crack formation in thick electrodes.
Solution Approach 2:
The drying process is segmented into multiple stages with progressively adjusted parameters. Instead of a single high-temperature step, the system divides drying into sequential phases, each optimized for specific moisture removal requirements, thereby maintaining productivity without causing cracks.
4Productivity
If the electrode is rewound immediately after drying, then the productivity is improved, but the wrinkle formation in uncoated portions worsens
Solution Approach 1:
The patent applies preliminary action by pre-cooling or pre-stabilizing the electrode after drying before it enters the rewinding process. This preliminary stabilization step prevents thermal expansion differences and moisture gradients that would cause wrinkles during rewinding, maintaining both productivity and surface quality.
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 effectively minimizes the occurrence of cracks and wrinkles in the electrodes by maintaining a specific shape during drying, ensuring smooth rewinding and reducing deformation.
Implementation Method 1
a drying nozzle drying the coated current collector moving through the driving rolls by air of a predetermined temperature and a predetermined amount
Implementation Method 2
a plurality of driving rolls supporting the coated current collector that moves in the drying device, and moving the current collector through a rotary motion
Data Source
AI summary
A system for manufacturing a lithium ion secondary battery includes an unwinder supplying a current collector to be coated to a predetermined position, a coating device coating a coating liquid on the current collector, a drying device drying the coated current collector, and a rewinder winding the coated current collector passing through the drying device at a predetermined position.