Fluid Pressing for Pouch Cells With Uniform Charging Pressure
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Solution Overview
Problem
Existing battery cell pressing devices fail to apply uniform pressure consistently, leading to degraded battery performance and reduced lifespan, especially when using anodes with substantial volume fluctuations like silicon and lithium metal.
Innovation Solution
A battery cell pressing device that uses a fluid to isotropically press the battery cell, ensuring uniform pressure application during charging and discharging, thereby preventing deterioration in performance and lifetime.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a fixture is used to press the battery cell during activation, then the battery cell can be pressed, but the pressure is not uniform leading to degraded performance
Solution Approach 1:
The patent employs a fluid (gas or liquid) contained in a flexible bag to apply pressure to the battery cell. The fluid transmits pressure isotropically (uniformly in all directions) to the battery cell, ensuring consistent pressure distribution across the entire cell surface. This hydraulic/pneumatic approach replaces mechanical fixtures and resolves the pressure uniformity issue that was degrading battery performance.
Solution Approach 2:
The patent changes the physical state and properties of the pressing medium from solid mechanical fixtures to a fluid medium. By utilizing the compressibility and flow properties of the fluid, the system achieves uniform pressure application that adapts to the battery cell's shape and volume changes during charging/discharging cycles, thereby improving manufacturing precision and battery reliability.
2Duration of action of moving object
If non-uniform pressure is applied during activation, then the battery cell can be pressed, but the lifespan is reduced
Solution Approach 1:
The fluid-based pressing system uses the incompressible nature of liquid or compressible nature of gas to distribute pressure uniformly throughout the battery cell. The flexible bag containing the fluid conforms to the battery cell's geometry, ensuring that pressure is applied evenly across all surfaces. This uniform pressure distribution prevents localized stress concentrations that would otherwise reduce battery lifespan, while maintaining the necessary pressing force for activation.
Solution Approach 2:
The patent creates an equipotential pressure field around the battery cell by using a fluid medium that transmits pressure equally in all directions (Pascal's principle). This ensures that every point on the battery cell surface experiences the same pressure magnitude, eliminating pressure gradients and non-uniform stress distributions that would compromise battery lifespan.
3Reliability
If uniform pressure is applied during charging/discharging, then performance is optimized, but requires sophisticated pressing mechanism
Solution Approach 1:
The patent uses a relatively simple hydraulic/pneumatic system consisting of a fluid reservoir, flexible bag, and pressure control mechanism to achieve uniform pressure application. This approach is simpler than complex mechanical pressing systems with multiple actuators and sensors, while still delivering the reliable uniform pressure needed to optimize battery performance during charging and discharging cycles.
Solution Approach 2:
The flexible bag containing the fluid automatically adapts its shape and pressure distribution to match the battery cell's geometry and volume changes. The system self-regulates to maintain uniform pressure without requiring complex control mechanisms, sensors, or active adjustment systems, thereby reducing device complexity while maintaining optimal battery performance.
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 device effectively maintains battery performance and extends the battery's lifespan by ensuring consistent, uniform pressure is applied during the activation and charging/discharging processes.
Implementation Method 1
the fluid isotropically presses the battery cell during at least one of charging and discharging of the battery cell
Data Source
AI summary
A battery cell pressing system may include a sealed case having an internal chamber, the sealed case including at least one window to allow visual inspection of the internal chamber; a pouch-type battery cell disposed within the internal chamber of the sealed case; a fluid filling the internal chamber and surrounding the pouch-type battery cell; a fluid entrance in fluid communication with the internal chamber; a pressing member configured to adjust a pressure of the fluid within the internal chamber such that the pressure at which the fluid presses the pouch-type battery cell is approximately 1 MPa to 10 MPa; a heater configured to heat the fluid within the internal chamber; and a pressure measuring member configured to measure the pressure within the internal chamber. The fluid isotropically presses the pouch-type battery cell during at least one of charging and discharging of the pouch-type battery cell.