Battery Cell Stack Pressing with Shape Memory Alloy Constant Force

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Solution Overview

Problem

Existing pressing devices for battery cell stacks do not exert a constant force on battery cells due to variations in thickness caused by factors like temperature, state of charge, and aging, leading to inefficient performance and degradation.

Innovation Solution

A pressing device using shape memory alloy pressure elements that expand or contract in response to changes in battery cell thickness, maintaining a constant force through superelastic behavior, and can be controlled to adjust the exerted force.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If spring-based tensioning devices are used to apply pressure on battery cells, then the device can accommodate cell thickness variations, but the exerted force becomes variable and proportional to spring expansion rather than constant

Engineering Contradiction:

Improveaccommodation of cell thickness variationsVSAvoidconstant force exertion

Core Design Contradiction:

Adaptability or versatilityVSForce

Solution Approach 1:

The patent changes the physical parameters of the pressure elements by using shape memory alloys with specific transformation temperatures (Af between -50°C and 100°C). By selecting alloys with different transformation temperatures, the system maintains constant force through phase transition at specific temperature ranges, resolving the contradiction between adaptability to thickness variations and maintaining constant force.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent uses shape memory alloys as composite material elements that combine elastic deformation with phase transition behavior. These materials exhibit superelasticity and shape memory effects, allowing the pressure elements to adapt to cell thickness changes while maintaining constant force through controlled phase transitions, thus resolving the force variability issue of conventional springs.

Inventive Principle:

Principle #40Composite materials

2Force

If the pressing device structure is made complex to maintain constant force, then force stability improves, but device complexity and manufacturing cost increase

Engineering Contradiction:

Improveforce stabilityVSAvoidpressing device structure

Core Design Contradiction:

ForceVSDevice complexity

Solution Approach 1:

The shape memory alloy pressure elements are passive components that automatically maintain constant force through their inherent phase transition properties. The system does not require external actuators, sensors, or control mechanisms to regulate force, as the material itself self-regulates force output based on temperature-dependent phase transitions, thereby reducing device complexity.

Inventive Principle:

Principle #25Self-service

Solution Approach 2:

The patent replaces complex mechanical force regulation systems (such as adjustable springs, actuators, or feedback mechanisms) with shape memory alloy elements that provide constant force through material phase transitions. This substitution of mechanical control systems with smart material behavior simplifies the overall device structure while maintaining force stability.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Force

If shape memory alloy pressure elements are used to maintain constant force, then force stability improves, but the temperature control requirement adds system complexity

Engineering Contradiction:

Improveconstant force maintenanceVSAvoidtemperature control above Af

Core Design Contradiction:

ForceVSTemperature

Solution Approach 1:

The shape memory alloy pressure elements serve multiple functions: they provide the pressing force, act as temperature sensors (through their phase transition behavior), and function as actuators (by changing shape with temperature). This multi-functionality reduces the need for separate temperature control and force application systems, offsetting the temperature management requirement with integrated functionality.

Inventive Principle:

Principle #6Universality (Multi-functionality)

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 improves battery cell performance and reduces degradation by maintaining a constant force throughout the life cycle, enhancing energy density and ease of implementation while being cost-effective.

Implementation Method 1

The pressure elements are manufactured from a shape memory alloy and kept at a temperature greater than the final transformation temperature of the austenitic phase (Af) of the shape memory alloy

Methodology Applied

Scientific EffectShape memory alloy: Shape Memory Alloy

Implementation Method 2

maintaining a constant force through superelastic behavior

Methodology Applied

Scientific EffectSuperelastic behavior: Pseudoelasticity

Data Source

PatentUS20260088332A1Pressing Device for a Battery Cell Stack

Publication Date: 2026.03.26 BATTBELT SL

AI summary

A pressing device for a battery cell stack including a plurality of battery cells. The pressing device including first and second pressure plates configured to be arranged at opposite ends of the battery cell stack. Pressure elements are fixed to the first and second pressure plates and are made from a shape memory alloy and kept at a temperature greater than the final transformation temperature of the austenitic phase of the alloy, such that the pressing device is expanded with an increase in the thickness of the battery cells and is compressed with a decrease in the thickness of the battery cells.