Double Check-Valve Terminal Venting for Moisture-Blocked Cells
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Solution Overview
Problem
Lithium-ion batteries face issues with gas generation due to reactions between electrolyte solvents and high energy materials, leading to internal pressure increases and potential can deformation, while existing solutions like gas permeable membranes and sealing valves are costly and inefficient, and may allow moisture ingress.
Innovation Solution
An electrochemical cell design featuring a gastight can with a plunger and dual O-rings forming an intermediate chamber, allowing controlled gas release and preventing moisture entry, with force balances shifting to manage pressure and gas exit based on operational states.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a gas permeable membrane is used to prevent water ingress, then moisture protection is improved, but device complexity and cost increase
Solution Approach 1:
The patent extracts the gas venting function from a separate membrane-based system and integrates it into the existing sealing valve structure. The sealing valve is modified to include a gas-permeable path while maintaining its liquid-blocking capability, eliminating the need for an additional gas permeable membrane and reducing overall device complexity.
Solution Approach 2:
The sealing valve is designed to perform multiple functions: it seals against both gas and liquid under normal conditions, but allows gas to pass through when pressure differential exceeds a threshold. This multi-functionality eliminates the need for separate gas and liquid management components, reducing device complexity while maintaining reliability.
2Reliability
If a mechanical vent is added to prevent water entry, then moisture protection is improved, but energy density decreases due to additional space requirements
Solution Approach 1:
The patent merges the gas venting function with the existing sealing valve structure. The sealing valve is redesigned to include internal channels or pores that allow gas passage while maintaining liquid sealing, combining multiple functions into a single component and eliminating additional space requirements.
Solution Approach 2:
The gas-permeable path is nested within the existing sealing valve structure. The venting channels are integrated into the valve body or plunger, allowing gas to pass through the existing component geometry without adding external volume or reducing the active cell space.
3Stress or pressure
If a sealing valve is used to release excess gas, then pressure control is improved, but moisture ingress risk increases when cell pressure decreases
Solution Approach 1:
The sealing valve is designed with dynamic sealing characteristics where the seal engagement varies with pressure differential. Under positive internal pressure, the valve opens to release gas. When internal pressure drops below external pressure, the valve automatically closes and the O-ring sealing mechanism engages to prevent moisture ingress, providing adaptive protection.
Solution Approach 2:
The O-ring sealing elements are pre-positioned and pre-compressed in the valve structure. When the plunger returns to its initial position after gas release, the O-rings are already in place to immediately seal the passage, preventing moisture ingress before it can occur during the pressure equalization process.
4Quantity of substance
If high energy materials are used in electrodes, then energy density is improved, but gas generation increases due to electrolyte reactions
Solution Approach 1:
The patent converts the harmful effect of gas generation into a beneficial pressure-driven venting mechanism. The gas generation from high-energy electrode materials creates internal pressure that automatically triggers the sealing valve to open, releasing the gas and preventing can deformation. The harmful gas generation is thus transformed into the driving force for the pressure control system.
Solution Approach 2:
The system implements a pressure feedback mechanism where internal pressure from gas generation automatically controls the valve state. When pressure exceeds the threshold set by the O-ring compression force, the valve opens to release gas. When pressure drops, the valve closes. This automatic feedback loop manages gas accumulation without external control while maintaining safety.
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
Effectively manages internal pressure without compromising battery life or energy density, reducing the risk of moisture ingress and maintaining a stable internal environment.
Implementation Method 1
the lower O-ring being compressed between a first surface of the terminal and a first surface of the plunger and adapted for applying a first force on the plunger per unit of length of the lower O-ring so as to form a lower sealing valve between the interior volume and the chamber
Implementation Method 2
the plunger being movable axially with respect to the terminal between: an equilibrium position, intended to be occupied when the first pressure, the second pressure and the outside pressure are equal to each other
Data Source
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AI summary
An electrochemical cell (10) comprising: - a can (12), - an electrical terminal (18) defining an axis (X) and forming a housing (20, - a plunger (24), - an upper O-ring (26) and a lower O-ring (28) located on an upper extremity (30) of the plunger along the axis and on a lower extremity (32), and surrounding the axis, the terminal, the plunger, the upper O-ring and the lower O-ring delimiting an intermediate chamber (60). The lower O-ring forms a lower sealing valve between an interior volume (14) and the chamber. The upper O-ring forms an upper sealing valve between the chamber and an exterior volume (16). The plunger is movable axially with respect to the terminal between an equilibrium position and two working positions in order to let excess gas moving from the interior volume to the exterior volume via the chamber while preventing moisture from doing the opposite.