Pouch Lithium Battery Roll Pressing for Uniform Electrode Activation
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Solution Overview
Problem
Pouch-type lithium secondary batteries face issues with localized charging non-uniformity and lithium precipitation due to gas trapping in the electrode sliding portion, which is difficult to pressurize effectively with conventional flat pressure plates.
Innovation Solution
A roll-pressing activation method that uses pressure rollers to apply pressure from the center to the edge of the battery, ensuring the sliding portion is pressurized equally to prevent gas trapping, combined with a pre-aging process to stabilize the electrolyte impregnation and a formation process that includes controlled charging and surface pressure application.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If flat pressure plates are used to pressurize the battery during formation, then the battery structure is simple and easy to manufacture, but the sliding portion of the electrode cannot be pressurized effectively causing gas trapping
Solution Approach 1:
The patent replaces flat pressure plates with pressure rollers that have curved surfaces. These rollers can effectively pressurize the sliding portion of the electrode where the active material layer has an inclined shape, eliminating dead zones where gas could be trapped. The curved surface of the roller conforms to the inclined geometry of the sliding portion, ensuring uniform pressure distribution across the entire electrode surface including previously inaccessible areas.
2Productivity
If the electrode active material layer is applied as fluid slurry, then the electrode manufacturing is simple and efficient, but the slurry flows down forming an inclined sliding portion that is difficult to pressurize
Solution Approach 1:
The pressure rollers with curved surfaces are specifically designed to match the inclined geometry of the sliding portion formed by slurry flow. This allows the rollers to maintain consistent contact and apply uniform pressure across the inclined surface, preventing gas trapping and ensuring homogeneous electrode structure despite the inherent inclination caused by slurry application.
Solution Approach 2:
The patent introduces a pressurization parameter (pressure application) during the formation process that compensates for the non-uniform thickness caused by slurry flow. By applying controlled pressure through rollers, the system adjusts the physical state of the electrode during formation, ensuring proper electrolyte impregnation and eliminating defects in the sliding portion without changing the slurry application process itself.
3Device complexity
If gas is trapped in the sliding portion, then the battery can be manufactured with simple equipment, but localized charging non-uniformity and lithium precipitation occur
Solution Approach 1:
The curved surface of the pressure rollers eliminates dead zones and ensures complete contact with the electrode surface including the sliding portion. This geometric design prevents gas trapping by maintaining continuous pressure across all areas, thereby preventing localized charging non-uniformity and lithium precipitation without requiring complex additional equipment or process modifications.
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 roll-pressing method effectively prevents gas trapping and reduces the risk of localized charging non-uniformity and lithium precipitation, improving battery quality and performance by ensuring uniform pressure on all parts of the electrode.
Implementation Method 1
a roll-pressing process which pressurizes the lithium secondary battery using a pressure roller
Data Source
AI summary
An activation method for a lithium secondary battery having an electrode lead includes: a pre-aging process aging the lithium secondary battery at room temperature; a formation process charging the lithium secondary battery; and a roll-pressing process of pressurizing the lithium secondary battery using a pressure roller. The roll-pressing process includes pressing from a center of the lithium secondary battery toward an end of the lithium secondary battery where the electrode lead is located.