Jelly-Roll Electrode Assembly With Variable Bonding to Relieve Stress
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Solution Overview
Problem
Lithium-ion batteries face safety concerns due to stress concentration and deformation issues in complex-shaped batteries, leading to potential hazards like electrolyte retention problems and lithium plating, which existing bonding technologies fail to adequately address.
Innovation Solution
A jelly-roll type electrode assembly with a separation layer having varying bonding forces across different regions, allowing for a higher bonding force in straight regions and a lower bonding force in rollback regions to prevent stress concentration and deformation, achieved through the use of binders of different viscosities and polymer fibers with controlled content and diameter.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If bonding layers of consistent viscosities are disposed between the separator and electrode plate throughout, then bonding force is uniformly increased, but stress concentration occurs in certain regions leading to safety issues
Solution Approach 1:
The patent applies local quality by using bonding layers with different viscosities in different regions of the electrode assembly. Specifically, the first region (non-rollback region) uses a bonding layer with first viscosity, while the second region (rollback region) uses a bonding layer with second viscosity that is different from the first viscosity. This local differentiation allows each region to have optimized bonding characteristics suitable for its specific structural requirements, preventing stress concentration while maintaining adequate bonding force.
2Reliability
If the battery structure is made complex to meet various performance requirements, then energy density and safety requirements can be addressed, but stress distribution becomes uneven causing deformation during cycling
Solution Approach 1:
The patent addresses structural stability by implementing local quality in the bonding layer design. Different viscosity bonding layers are applied to different regions (first region vs. second region) to account for the uneven stress distribution caused by complex battery structures. This localized optimization maintains structural integrity during cycling by allowing each region to accommodate stress appropriately, preventing overall deformation while meeting performance requirements.
Data Source
AI summary
A jelly-roll type electrode assembly includes an electrode plate and a separation layer disposed on at least one surface of the electrode plate. A bonding force of the separation layer to a surface of the electrode plate in a first region of the jelly-roll type electrode assembly is greater than a bonding force of the separation layer to the surface of the electrode plate in a second region of the jelly-roll type electrode assembly. In this way, the bonding force of the separation layer to the surface of the electrode plate in the first region in the jelly-roll type electrode assembly is relatively high. When the electrode plate in the second region is stressed, a slight slip can occur between layers to release the stress, alleviating deformation of the electrochemical device caused by stress concentration.