Wound Secondary Battery Tape Layout for Stable Electrode Spacing
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Solution Overview
Problem
Existing secondary batteries face challenges in maintaining operation reliability due to fluctuations in the distance between the positive and negative electrodes during charging and discharging, leading to variations in current density and potential issues like local current concentration and lithium metal precipitation.
Innovation Solution
A secondary battery design featuring an electrode wound body with a stacked configuration of electrodes and separators, covered by tapes with varying elongation percentages. The third tape, covering the intermediate side surface, has a higher elongation percentage than the first and second tapes, helping to maintain consistent electrode distances and reduce current density variations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the electrode wound body uses uniform tapes with the same elongation percentage, then the structure is simple and easy to manufacture, but the distance between electrodes fluctuates during charging and discharging causing current density variations and reliability issues
Solution Approach 1:
The patent applies local quality by using tapes with different elongation percentages at different locations along the electrode wound body. Specifically, the first and second tapes (at the ends) have a first elongation percentage, while the third tape (in the intermediate region) has a second elongation percentage that is higher than the first. This localized differentiation allows the intermediate region, which experiences different stress during expansion and contraction, to be compensated appropriately, thereby maintaining electrode distance consistency and improving operation reliability.
2Reliability
If the third tape has higher elongation percentage, then electrode distance consistency is maintained and current density variations are reduced, but the manufacturing precision requirements increase
Solution Approach 1:
The patent applies parameter changes by varying the elongation percentage parameter of the tapes based on their position. The first and second tapes have a first elongation percentage, while the third tape has a second elongation percentage that is specifically set to be higher. This parameter differentiation compensates for the non-uniform stress distribution during battery expansion and contraction, maintaining electrode distance consistency and suppressing degradation in cyclability characteristic.
3Reliability
If tapes with varying elongation percentages are used, then stress concentrations are reduced and electrode distance is maintained, but the device complexity increases
Solution Approach 1:
The patent applies local quality by using tapes with different elongation percentages at different locations along the electrode wound body. Specifically, the first and second tapes (at the ends) have a first elongation percentage, while the third tape (in the intermediate region) has a second elongation percentage that is higher than the first. This localized differentiation allows the intermediate region, which experiences different stress during expansion and contraction, to be compensated appropriately, thereby maintaining electrode distance consistency and improving operation reliability.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This design effectively suppresses degradation in battery performance, such as cyclability, by maintaining consistent electrode distances and reducing stress concentrations, thereby enhancing operation reliability.
Implementation Method 1
The third tape has an elongation percentage higher than both an elongation percentage of the first tape and an elongation percentage of the second tape
Data Source
AI summary
A secondary battery having higher operation reliability is provided. The secondary battery includes an electrode wound body, a first tape, a second tape, and a third tape. The electrode wound body has a first end face and a second end face that are opposed to each other in a first direction, and a side surface coupling the first end face and the second end face to each other. The first tape covers a first side surface part, of the side surface of the electrode wound body, that is positioned on a side of the first end face. The second tape covers a second side surface part, of the side surface of the electrode wound body, that is positioned on a side of the second end face. The third tape covers a third side surface part, of the side surface of the electrode wound body, that is positioned between the first side surface part and the second side surface part. The third tape has an elongation percentage higher than both an elongation percentage of the first tape and an elongation percentage of the second tape.