Secondary Battery Tab Length Layout for Higher Energy Density
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Solution Overview
Problem
Existing secondary battery manufacturing methods face challenges in achieving high energy density and reliability while ensuring stable and efficient production.
Innovation Solution
The design incorporates an electrode assembly with differently sized tabs and current collectors, where the lengths of the tabs form conductive paths to terminals, and spacers are used to secure the assembly within a case with openings sealed by plates, allowing for efficient electrolyte injection and improved energy density.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the electrode assembly is accommodated in a case with openings at both ends and terminals are attached to cap plates sealing the openings, then the battery structure is simple and easy to manufacture, but the energy density cannot be sufficiently improved and manufacturing reliability needs improvement
Solution Approach 1:
The patent transitions from a conventional side-terminal configuration to an end-terminal configuration where terminals are positioned at the ends of the cylindrical case. This dimensional change allows for more efficient space utilization within the battery, enabling higher energy density while maintaining manufacturing simplicity through the standardized cap plate sealing approach.
2Reliability
If tab lengths are optimized with L2/L1>1.2 ratio between positive and negative electrode tabs, then energy density and reliability are improved, but manufacturing complexity increases due to precise length control requirements
Solution Approach 1:
The patent establishes a specific parameter range for tab length ratios (L2/L1>1.2) where L1 is the maximum length of negative electrode tabs and L2 is the maximum length of positive electrode tabs. This parameter optimization improves battery reliability by ensuring proper electrical connection and stress distribution, while the ratio-based specification provides clear manufacturing guidance that balances precision requirements with manufacturability.
3Quantity of substance
If different electrode tab lengths are used with maximum value L1 of first lengths and maximum value L2 of second lengths satisfying L2/L1>1.2, then energy density is improved, but device complexity increases due to asymmetric tab configuration
Solution Approach 1:
The patent deliberately employs asymmetric electrode tab lengths with the positive electrode tabs (L2) being longer than the negative electrode tabs (L1) by a ratio greater than 1.2. This asymmetric configuration optimizes energy density by improving electrical contact and current distribution. The asymmetry is managed through standardized manufacturing processes that control the length ratio, preventing excessive complexity while achieving performance benefits.
Data Source
AI summary
In a secondary battery, a first electrode tab group includes a plurality of first electrode tabs having first lengths different from each other, each of the first lengths being a length from a root of the first electrode tab group to a first joining portion, a second electrode tab group includes a plurality of second electrode tabs having second lengths different from each other, each of the second lengths being a length from a root of the second electrode tab group to a second joining portion, and a maximum value L1 of the first lengths in the first electrode tab group and a maximum value L2 of the second lengths in the second electrode tab group satisfy a relation of L2/L1>1.2.