Current Collector Fracture Structure for Battery Cell Flame Discharge
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Solution Overview
Problem
Thermal runaway in secondary batteries can lead to uncontrolled heating, causing damage to battery cells and potentially leading to chain reactions, including pinhole formation and flame obstruction, which can spread to adjacent cells.
Innovation Solution
A battery cell design with a current collector featuring a fracture portion at the boundary between the support and tab coupling portions, including notch lines and through holes, allowing flames to be smoothly discharged during thermal runaway, preventing damage to the beading portion and pinhole formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a current collector without fracture portions is used to maintain structural strength, then the mechanical strength of the current collector is improved, but flame discharge is blocked during thermal runaway causing pinhole formation and cell damage
Solution Approach 1:
The current collector is segmented by introducing fracture portions (notch lines) that divide the structure into regions with different strengths. The support portion maintains high strength for mechanical support, while the tab coupling portion has reduced strength to serve as a flame discharge path during thermal runaway, preventing pinhole formation in the beading portion.
Solution Approach 2:
Different regions of the current collector are given different local properties: the support portion has high mechanical strength for structural integrity, while the tab coupling portion has deliberately reduced strength through fracture portions to allow controlled flame discharge. This local differentiation resolves the contradiction between overall strength and localized flame discharge capability.
2Reliability
If the current collector structure is made robust to prevent damage, then the reliability of the battery cell is improved, but thermal runaway flames cannot be discharged smoothly causing uncontrolled heating
Solution Approach 1:
The fracture portions convert the harmful effect of thermal runaway flames into a beneficial controlled discharge mechanism. Instead of allowing uncontrolled heating that damages the cell, the weakened tab coupling portion is designed to fracture and redirect flames through safe paths, transforming a potential failure mode into a protective feature that maintains battery reliability.
3Stability of the object's composition
If the tab coupling portion is made stronger to maintain structural integrity, then the mechanical stability is improved, but the beading portion becomes vulnerable to damage during thermal runaway
Solution Approach 1:
The fracture portions are pre-designed in the tab coupling portion before thermal runaway occurs. This preliminary structural weakness ensures that when thermal runaway happens, the flame will naturally discharge through the predetermined weak path rather than damaging the beading portion, preventing harmful effects before they can occur.
Data Source
AI summary
A battery cell includes: an electrode assembly including a first electrode and a second electrode with a separator interposed therebetween, and the first electrode, second electrode and separator are wound around a winding axis, wherein the first electrode includes a first uncoated portion, which is not coated with an active material layer; a battery housing having an opening and that accommodates the electrode assembly through the opening; and a current collector including a support portion, a tab coupling portion, and a housing coupling portion. A fracture portion is provided at a boundary between the support portion and the tab coupling portion.