What Is The Role Of A Customized In-Situ Pressure Measurement Fixture? Achieve Precise Battery Swelling Analysis

The primary role of a customized in-situ pressure measurement fixture is to replicate the rigid physical constraints of a real battery module by strictly limiting axial deformation. Through the use of fixed end plates and high-strength fastening bolts, the fixture creates a controlled mechanical environment that forces the battery to behave as it would within a commercial pack, rather than expanding freely.

Core Takeaway Accurate monitoring of battery degradation requires more than just a sensor; it requires a precise mechanical context. This fixture establishes the necessary hardware foundation to convert internal swelling forces into linear, accurate signals for long-term analysis.

Replicating the Module Environment

To understand the value of this fixture, one must first understand the mechanical reality of a prismatic battery module. In the real world, batteries are packed tightly and cannot expand freely.

Simulating Fixed Boundaries

The fixture utilizes fixed end plates secured by high-strength fastening bolts. This creates a rigid cage around the battery cell.

Restricting Axial Deformation

This rigid structure serves a specific purpose: to restrict axial deformation during cycling. By preventing the cell from swelling outward, the fixture mimics the mechanical compressive forces found inside an actual battery module.

Ensuring Data Precision

The challenge in pressure monitoring is not just restraining the battery, but measuring the force of that restraint accurately. The fixture employs a specific mechanism to solve this.

The Function of the Movable Plate

An integrated movable plate is positioned between the battery cell and the pressure sensor. This plate acts as a mechanical interface.

Uniform Force Transmission

The movable plate ensures that the expansion force generated during charging and discharging is transmitted uniformly to the sensor's receiving surface. Without this plate, force distribution could be uneven, leading to localized pressure spikes that skew the data.

Linearity and Accuracy

This setup guarantees that the conversion of internal pressure into external electronic signals maintains linearity and accuracy. It establishes a reliable baseline for long-term, real-time monitoring of mechanical degradation.

Understanding the Critical Requirements

While the concept is straightforward, the effectiveness of the fixture relies on the integrity of its components.

The Necessity of Stiffness

The "fixed" end plates and bolts must possess high strength. If the fixture itself deforms under the pressure of the swelling battery, the simulation is compromised, and the pressure readings will be artificially low.

The Role of the Interface

The movable plate is not a passive spacer. It is a critical component for signal conditioning. If the plate does not move smoothly or transmit force evenly, the relationship between the battery's internal state and the sensor's output will become non-linear.

Making the Right Choice for Your Goal

When designing or selecting a fixture for LFP prismatic battery analysis, consider your specific objective:

If your primary focus is Realistic Simulation: Prioritize the stiffness of the end plates and bolts to ensure axial deformation is restricted exactly as it is in the target module.
If your primary focus is Data Fidelity: Ensure the integrated movable plate is precision-engineered to transmit expansion forces uniformly to the sensor, preventing signal distortion.

The ultimate goal is to establish a hardware foundation that makes internal mechanical changes transparent and measurable.

Summary Table:

Feature	Role in Simulation	Benefit for Analysis
Fixed End Plates	Replicates rigid module boundaries	Restricts axial deformation for realistic swelling
High-Strength Bolts	Maintains structural integrity	Prevents fixture flex to ensure data consistency
Movable Plate	Acts as a mechanical interface	Ensures uniform force distribution to the sensor
Pressure Sensor	Real-time signal conversion	Provides linear and accurate long-term monitoring

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References

Shuaibang Liu, Xiaoguang Yang. Expansion Pressure as a Probe for Mechanical Degradation in LiFePO4 Prismatic Batteries. DOI: 10.3390/batteries11110391

This article is also based on technical information from Kintek Press Knowledge Base .