Introduction

In high-reliability applications such as UPS systems, data centers, and telecom infrastructure, lithium battery performance depends not only on electrochemical materials but also on mechanical design.

As a professional lithium battery manufacturer, EverExceed focuses on optimizing both electrochemical performance and structural design. One critical factor is the preloading force applied to LiFePO4 battery cells, which plays a key role in improving performance, safety, and lifespan.

1. Optimizing Electrochemical Performance: Reducing Resistance and Polarization

Maintaining Interface Contact Stability

During charge and discharge cycles, LiFePO4 cells undergo slight volume changes. Without external constraint, gaps may form between electrodes and the separator, increasing lithium-ion transport distance.

Proper preloading force ensures tight contact between layers and maintains smooth ion transport pathways.

Reducing Internal Resistance

Close contact between components significantly reduces ohmic resistance and charge transfer resistance.

Experimental results show that under optimized preloading force (e.g., 1400N), battery impedance decreases, resulting in lower energy loss and reduced heat generation.

Enhancing High-Rate Performance

With faster ion transport and lower resistance, batteries perform more stably under high-rate charge and discharge conditions, avoiding rapid voltage drop caused by excessive polarization.

2. Maintaining Mechanical Stability: Suppressing Swelling and Deformation

Controlling Cell Expansion

During cycling, SEI layer growth and material degradation cause cell swelling.

Without preloading: cells expand freely, leading to structural loosening and misalignment

With preloading: expansion is controlled, maintaining structural integrity

Preventing Delamination

Long-term swelling may cause separation between active materials and current collectors (copper or aluminum foil).

This phenomenon, known as delamination, results in irreversible capacity loss.

Proper preloading force effectively prevents this structural damage.

3. Impact on Safety: Gas Management and Thermal Runaway

Gas Evolution Control

Under abuse conditions (overcharge, over-discharge, or high temperature), gas generation increases.

Positive effect: appropriate preloading may delay early deformation

Complex effect: excessive force (e.g., 9kN) may affect safety valve response and gas release behavior

This indicates that preloading force must be carefully optimized.

Thermal Propagation Mitigation

At the battery system level, preloading ensures close contact between cells and thermal management components (such as liquid cooling plates), enabling faster heat dissipation and delaying thermal runaway propagation.

4. Extending Cycle Life: A Comprehensive Benefit

Slower Aging Mechanism

Reduced resistance, stable structure, and improved thermal management collectively slow down battery degradation.

Higher Capacity Retention

Studies show that LiFePO4 batteries under proper mechanical constraint exhibit significantly lower capacity fade compared to unconstrained cells.

This is mainly due to:

• Reduced lithium plating

• More uniform lithium intercalation

• Suppressed material cracking

• Lower side reactions

5. EverExceed Engineering Advantages

At EverExceed, we integrate mechanical and electrochemical optimization into our lithium battery solutions for UPS and data center applications:

• Precision-controlled cell compression design

• Optimized module structure for uniform preloading force

• Advanced thermal management integration

• High-consistency LiFePO4 battery cells

These advantages ensure:

✔ Lower internal resistance

✔ Enhanced safety performance

✔ Longer cycle life

✔ Reliable operation in mission-critical environments

Conclusion

Preloading force is a critical yet often overlooked factor in lithium battery system design. It directly affects electrochemical performance, mechanical stability, safety behavior, and long-term reliability.

With advanced engineering and strict quality control, EverExceed delivers high-performance lithium battery systems tailored for UPS, data centers, and industrial energy storage applications.