Pouch Battery Case Structure for Smaller Bat Ears and Higher Energy Density
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Solution Overview
Problem
Pouch-type secondary batteries face limitations in increasing energy density relative to volume and achieving an elegant outer appearance, leading to reduced marketability due to constraints in moldability and curvature radius of the battery case, as well as limitations in manufacturing sharp shapes and reducing the size of the bat ear.
Innovation Solution
A pouch-type secondary battery design featuring a battery case with a cup part that includes a folding part with a bat ear of 1.5 mm or less in length, an angle greater than 151 degrees between the folding part and the bat ear, and a moisture barrier layer with a specific thickness and grain size, along with a sealant layer and elongation assistance layer, to enhance moldability and reduce the size of the bat ear.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the moisture barrier layer uses aluminum alloy with large crystal grain size and thin thickness, then the manufacturing cost is reduced, but the moldability is deteriorated
Solution Approach 1:
The patent changes the grain size parameter of the aluminum alloy from large to fine (10 μm to 13 μm) while maintaining thin thickness (50 μm to 80 μm), resolving the contradiction between material thickness and moldability by optimizing the microstructural parameters of the material
Solution Approach 2:
The patent uses a composite pouch film structure with multiple layers including the aluminum alloy moisture barrier layer, sealant layer, and surface protection layer, where each layer contributes different properties to achieve both thin overall thickness and good moldability
2Quantity of substance
If the cup part is molded deeply, then the battery capacity is increased, but the curvature radius and clearance of the edge are limited
Solution Approach 1:
The patent changes the material parameters (fine grain size, controlled thickness) of the pouch film to enable deep molding of the cup part while maintaining appropriate curvature radius and clearance, thus increasing battery capacity without compromising shape quality
3Quantity of substance
If the volume ratio of electrode assembly to cup part is increased, then the energy density is improved, but the size of bat ear is reduced
Solution Approach 1:
The patent optimizes the geometric parameters of the cup part and bat ear through improved moldability, achieving a higher volume ratio of electrode assembly to cup part while maintaining the bat ear size at 1.5 mm or less, thus increasing energy density
4Quantity of substance
If the bat ear size is reduced, then the energy density relative to volume is increased, but the manufacturing precision is challenged
Solution Approach 1:
The patent uses fine grain size aluminum alloy with controlled thickness to improve moldability and manufacturing precision, enabling accurate control of the bat ear dimension at 1.5 mm or less while maximizing energy density
Solution Approach 2:
The patent applies pressure control during the molding process to achieve precise shaping of the small bat ear structure, using hydraulic or pneumatic pressing to maintain dimensional accuracy
Data Source
AI summary
A pouch-type secondary battery according to an embodiment of the present invention for achieving the above object includes: an electrode assembly in which electrodes and separators are stacked; a pouch-type battery case comprising a first case and a second case, wherein at least one the first case and the second case comprises a cup part configured to accommodate the electrode assembly; a folding part coupling the first case to the second case; and a protrusion protruding from a portion of each of opposing ends of the folding part, wherein the protrusion has a length of 1.5 mm or less.