Wound Electrode Assembly Insulation Against Battery Internal Shorts
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Solution Overview
Problem
Rechargeable batteries face internal short circuits due to external impacts, caused by contact between positive and negative electrode active materials and Joule heating, exacerbated by thin separators.
Innovation Solution
A rechargeable battery design featuring a wound electrode assembly with insulating tapes, specifically a first insulating tape made of high-heat-resistant materials like polyamide, polyimide, or ceramic, positioned at the winding start and center of the electrode assembly to prevent contact between electrodes, and a fixing tape at the winding end to secure the assembly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the separator thickness is decreased to increase battery capacity, then the battery capacity increases, but the risk of internal short circuit increases due to separator shrinkage and contact between electrodes
Solution Approach 1:
An insulating tape is introduced as an intermediary component between the positive and negative electrodes at the winding start portion. This tape prevents direct contact between electrodes even when the separator shrinks under external impact, thereby maintaining electrical insulation while allowing the use of thin separators for high capacity.
Solution Approach 2:
The insulating tape is positioned at the winding start portion before any potential short circuit can occur. This preliminary protective measure ensures that even if the separator shrinks later due to impact or temperature changes, the electrodes are already protected from contact at the most vulnerable location.
2Quantity of substance
If the electrode active material density is increased to improve capacity, then the battery capacity increases, but the temperature rises rapidly due to Joule heating and reduced safety margin
Solution Approach 1:
The insulating tape acts as a thermal barrier between the high-density active materials of positive and negative electrodes. This intermediary layer reduces direct thermal coupling, allowing higher active material density while mitigating the rapid temperature increase from Joule heating.
3Quantity of substance
If the plate thickness is decreased to increase capacity, then the battery capacity increases, but the mechanical strength and safety against external impact decrease
Solution Approach 1:
The insulating tape is applied at the winding start portion as a preliminary reinforcement before the electrode assembly is subjected to external impacts. This pre-positioned protective element maintains structural integrity and prevents electrode contact even when thin plates are used for high capacity.
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
The solution effectively prevents internal short circuits from external impacts by providing thermal insulation and mechanical protection, enhancing the safety and reliability of the battery.
Implementation Method 1
a first insulating tape which is positioned at a winding start portion of the electrode assembly and attached to the non-coated portion of the first electrode so as to at least cover a center of a first curved portion which is curvedly formed as the electrode assembly is wound
Implementation Method 2
a separator interposed between the first electrode and the second electrode
Implementation Method 3
a temperature is rapidly increased due to contact between a positive electrode plate and a negative electrode active material caused by Joule heating
Data Source
AI summary
A rechargeable battery according to an exemplary embodiment of the present invention includes: an electrode assembly which is wound and includes a first electrode, a second electrode, and a separator interposed between the first electrode and the second electrode; a casing which accommodates the electrode assembly; a first electrode tab which is connected to a non-coated portion of the first electrode; a second electrode tab which is connected to a non-coated portion of the second electrode; and a first insulating tape which is positioned at a winding start portion of the electrode assembly and attached to the non-coated portion of the first electrode so as to at least cover a center of a first curved portion which is curvedly formed as the electrode assembly is wound.