Electrode Tap Receptor Sealing for Deep Pouch Lithium Cells
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Solution Overview
Problem
Pouch-type lithium secondary batteries face limitations in molding depth, leading to cracks in the pouch film, exposure of the metallic layer, reduced lifespan, and unnecessary space in sealed portions, which affects capacity and reliability.
Innovation Solution
A lithium secondary battery design incorporating an electrode tap receptor with a gas barrier layer, which houses the electrode tap and includes features like multiple layers, insulation films, and an electrolyte storage part, allowing for sealing without protruding sealing parts, thus preventing gas permeability and enhancing durability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the pouch film is molded deeper to house large sized battery cells, then the battery capacity increases, but cracks easily occur in the pouch film and the metallic layer is exposed
Solution Approach 1:
The pouch film is constructed as a multi-layer composite structure with a polymer base layer and a metal layer (aluminum or stainless steel) laminated together. This composite structure provides both the flexibility needed for deep molding and the mechanical strength to prevent cracks and exposure, allowing large battery cells to be housed without compromising pouch integrity.
2Reliability
If the case is molded to seal the electrode assembly, then the sealing reliability improves, but unnecessary space is formed in the sealed portion
Solution Approach 1:
The sealing structure is divided into multiple segments: the case body, the protrusion portion extending from the case, and the insertion portion of the electrode assembly. This segmentation allows the sealing surfaces to contact precisely at the protrusion portion without requiring excessive case volume, eliminating unnecessary space while maintaining sealing reliability.
Solution Approach 2:
The sealing approach transitions from volumetric sealing to surface-based sealing by creating a protrusion portion that extends in a specific direction from the case. This dimensional change allows sealing to occur at the interface between the protrusion and the electrode assembly without requiring the case to enclose unnecessary space.
3Quantity of substance
If the battery thickness is increased to achieve high capacity, then the energy density improves, but the pouch film molding depth limitation is exceeded
Solution Approach 1:
The multi-layer composite pouch film structure provides enhanced mechanical strength and flexibility, enabling it to accommodate increased battery thickness for high capacity without exceeding molding depth limitations. The metal layer reinforcement allows the pouch to maintain integrity at greater thicknesses.
Solution Approach 2:
The electrode assembly is segmented with the electrode tap protruding through the pouch film at a specific location, allowing the bulk of the electrode assembly to be housed within the depth limitations while the tap extends outward. This segmentation enables high capacity design within the constrained molding depth.
Data Source
AI summary
The present invention provides a lithium secondary battery which includes an electrode assembly to which an electrode tap is attached, an electrode tap receptor configured to house a portion of the electrode assembly such that a portion of the electrode tap protrudes to an outside, and a case configured to surround the electrode assembly and seal the electrode assembly together with the electrode tap receptor, wherein the electrode tap receptor includes a gas barrier layer.