Bipolar Li-ion Battery Sealing Device
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Solution Overview
Problem
Conventional bipolar lithium-ion batteries face challenges in achieving perfect sealing against liquid electrolytes, leading to ionic short-circuits and increased internal electrical resistance due to the limitations of existing sealing solutions, which often compromise on chemical resistance, ease of use, and long-term durability.
Innovation Solution
A bipolar battery design incorporating a bipolar current collector with a heat-sensitive frame surrounded by two adhesive frames, allowing for precise heat-sealing to create a robust and impermeable seal that maintains electron conductivity and prevents electrolyte leakage, using materials like polyethylene for the heat-sensitive frame and double-faced acrylic for the adhesive frames.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional sealing solutions are used in bipolar lithium-ion batteries, then manufacturing is simpler, but sealing reliability against liquid electrolyte deteriorates leading to ionic short-circuits
Solution Approach 1:
The sealing structure is divided into multiple functional segments: a heat-sensitive frame providing chemical resistance and an adhesive frame providing mechanical bonding. This segmentation allows each component to specialize in its optimal function, resolving the contradiction between reliability and complexity by creating a modular system where simplicity of individual components compensates for the increased overall structure.
Solution Approach 2:
The invention uses composite sealing structures combining heat-sensitive material and adhesive material in distinct frames. This composite approach allows the sealing system to simultaneously achieve chemical resistance (from heat-sensitive material) and mechanical adhesion (from adhesive material), resolving the reliability-complexity contradiction by integrating multiple material properties into a coordinated system.
2Duration of action of stationary object
If heat-sealing is used to improve sealing durability, then long-term sealing is improved, but electrode and separator degradation occurs due to high temperature
Solution Approach 1:
The sealing function is segmented between a heat-sensitive frame that undergoes controlled thermal activation and an adhesive frame that provides stable bonding. This segmentation allows the heat-sensitive component to perform its sealing function at elevated temperatures without requiring the entire sealing structure to withstand prolonged high-temperature exposure, thus improving duration while reducing harmful thermal effects on electrodes and separators.
Solution Approach 2:
The heat-sensitive frame acts as an intermediary that mediates the sealing process by undergoing controlled thermal transformation. This intermediary component absorbs the thermal stress during sealing operations, protecting the adhesive frame and surrounding sensitive components (electrodes and separators) from direct exposure to degrading temperatures, thereby enabling durable sealing without harmful thermal effects.
3Reliability
If sealing structures are added to prevent electrolyte leakage, then reliability is improved, but internal electrical resistance increases
Solution Approach 1:
The sealing structures are applied locally at specific peripheral locations on the bipolar current collector rather than covering the entire surface. This local quality approach ensures that sealing functions are provided only where electrolyte containment is critical, while leaving the central conductive areas free of sealing materials that would increase electrical resistance, thus resolving the contradiction between electrolyte containment and electrical conductivity.
Solution Approach 2:
The composite sealing structure uses electrically insulating materials with high conductivity properties, and positions them in frames that minimize interference with current flow paths. The heat-sensitive and adhesive frames are configured to provide electrolyte containment while maintaining optimal electrical conductivity in the bipolar current collector, resolving the contradiction between reliable sealing and minimal internal resistance.
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 provides a durable, chemically resistant, and impermeable seal that maintains constant compartment thickness, preventing electrolyte escapes and ensuring optimal battery operation while minimizing internal resistance.
Implementation Method 1
allowing for precise heat-sealing to create a robust and impermeable seal
Implementation Method 2
two adhesive frames arranged individually on either side of the heat-sensitive frame in a radial direction
Data Source
AI summary
A bipolar battery having at least two electrochemical cells stacked one on top of the other, the bipolar collector including, at the periphery of same, on one of the faces of same, at least one first sealing device including one frame made from an electrically insulating and thermosensitive material, and two adhesive frames arranged individually to either side of the thermosensitive frame, the first or the second adjacent collector also including, at the periphery of same, on the covered face of same, at least one second sealing device including a frame made from an electrically insulating and thermosensitive material, and two adhesive frames arranged individually to either side of the thermosensitive frame, the first and second devices each forming a peripheral wall sealed to the electrolyte of the first or second cell, which surrounds same. Each sealed wall is obtained by heat-sealing at least one first and at least one second sealing device on the face of a current collector not provided with a sealing device.