Jelly-Roll Battery Fixing Tape That Releases to Fill Cell Gaps
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Solution Overview
Problem
Secondary batteries with jelly-roll type electrode assemblies face issues of electrode movement and increased battery resistance due to empty spaces within the battery cell, which affect the stability and performance of the battery.
Innovation Solution
A secondary battery design featuring an electrode assembly with alternately stacked electrodes and separators, wrapped with a fixing tape that weakens its fixing force when impregnated with electrolyte, allowing the assembly to expand and prevent movement within the battery case, thereby reducing resistance by ensuring the negative electrode contacts the inner surface of the case.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a fixing tape made of PET or PP material is used to prevent the jelly roll from loosening, then the jelly roll is protected from external damage, but the jelly roll moves inside the cell if there is an empty space inside the cell
Solution Approach 1:
The fixing tape's material properties are changed to enable it to weaken its fixing force when impregnated with electrolyte. This parameter change allows the tape to initially hold the wound structure during manufacturing, then release to allow expansion and eliminate empty spaces that cause movement.
Solution Approach 2:
The fixing tape transitions from a static fixed state during manufacturing to a dynamic state where it can release its holding force. This dynamic behavior allows the electrode assembly to expand and fill empty spaces, preventing movement while maintaining protection.
2Stability of the object's composition
If the electrode assembly is tightly wound to maintain structural integrity, then the assembly is protected from unwinding, but empty spaces remain inside the battery cell causing movement and increased resistance
Solution Approach 1:
The fixing tape is applied in advance to maintain the wound structure during manufacturing and assembly. This preliminary action ensures structural integrity is maintained until the tape automatically releases upon electrolyte impregnation, at which point the assembly can expand to eliminate empty spaces.
Solution Approach 2:
The fixing tape acts as an intermediary that temporarily maintains structural integrity during manufacturing but automatically releases when impregnated with electrolyte. This mediator enables the transition from a tightly wound state to an expanded state that eliminates empty spaces and reduces resistance.
3Strength
If the fixing tape maintains strong fixing force to prevent unwinding, then the electrode assembly structure is maintained, but the assembly cannot expand to fill empty spaces
Solution Approach 1:
The fixing force parameter of the tape is designed to change automatically when impregnated with electrolyte. The tape transitions from a high fixing force state during manufacturing to a low fixing force state during operation, enabling both structural maintenance and expansion capability.
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 electrode assembly movement and reduces battery resistance by allowing the assembly to expand and fill the space within the battery case, enhancing the stability and performance of the secondary battery.
Implementation Method 1
the fixing tape is configured to be weakened in fixing force for suppressing unwinding when being impregnated in the electrolyte
Data Source
AI summary
A secondary battery includes an electrode assembly in which electrodes and separators are alternatively stacked to be wound, a battery case in which the electrode assembly and an electrolyte are accommodated, and a fixing tape adhering on an outer surface of the electrode assembly to prevent the electrode assembly from being unwound. The fixing tape is weakened in fixing force for suppressing unwinding when being impregnated in the electrolyte so that the winding of the electrode assembly is substantially released to expand in an initial space between the battery case and the electrode assembly. A method for manufacturing the same is also provided.