Z-Fold Separator Assembly for High-Speed Battery Electrode Stacking

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Solution Overview

Problem

Existing methods for folding electrodes and separators into a z-shape in battery cells face challenges such as production errors due to electrode slippage and complex strut removal, especially when electrodes are not pre-laminated, limiting production speed and efficiency.

Innovation Solution

A device with clamping punches and transversely extending brackets, allowing for the folding of a longitudinally extending separator into a z-shape, with optional heating or cutting mechanisms to facilitate strut removal and electrode lamination, ensuring precise folding and high production speed.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If lateral pulling method is used to remove struts, then strut removal is achieved, but electrode slippage occurs leading to production errors

Engineering Contradiction:
Improvestrut removalVSAvoidproduction errors
Core Design Contradiction:
Ease of manufactureVSReliability

Solution Approach 1:

The separator is pre-laminated to the electrodes before strut removal, creating a stable composite structure that prevents electrode slippage during the subsequent strut removal process. This preliminary bonding action ensures that when struts are removed later, the electrodes remain firmly positioned and cannot shift or slip.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The process is divided into distinct sequential steps: first laminating the separator to electrodes, then removing struts, and finally cutting the separator. This segmentation allows each operation to be optimized independently, ensuring that strut removal occurs only after electrodes are securely bonded, thereby eliminating slippage issues.

Inventive Principle:
Principle #1Segmentation

2Stability of the object's composition

If sequential stacking or z-folding is used, then electrode bending is avoided, but production speed is limited

Engineering Contradiction:
Improveelectrode integrityVSAvoidproduction speed
Core Design Contradiction:
Stability of the object's compositionVSProductivity

Solution Approach 1:

The device employs dynamically movable rails that can shift position during the folding process, enabling continuous motion and high-speed operation. The rails move coordinately with the punches to maintain proper positioning throughout the rapid folding sequence, allowing production speeds to be dramatically increased while keeping electrodes straight.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The folding operation is performed continuously in a single rapid motion sequence rather than through multiple discrete steps. The punches and rails operate in coordinated continuous motion to complete the entire z-fold process in one go, eliminating idle time between operations and maximizing production throughput while maintaining electrode integrity.

Inventive Principle:
Principle #20Continuity of useful action

3Productivity

If winding process is used, then production speed is very high, but electrodes are bent causing quality issues

Engineering Contradiction:
Improveproduction speedVSAvoidelectrode integrity
Core Design Contradiction:
ProductivityVSStability of the object's composition

Solution Approach 1:

The invention replaces the winding mechanical system with a folding mechanism. Instead of rotating electrodes around a mandrel in a winding process, the device uses punched folds and movable rails to create z-shaped configurations through controlled bending of the separator-electrode composite, eliminating the need for electrode winding while maintaining high production speeds.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

4Shape

If struts are positioned alternately above and below separator, then z-shaped folding is achieved, but complex strut removal is required

Engineering Contradiction:
Improvez-shaped foldVSAvoidstrut removal complexity
Core Design Contradiction:
ShapeVSDevice complexity

Solution Approach 1:

The separator is pre-laminated to the electrodes before strut removal, creating a stable composite structure that simplifies the subsequent strut removal process. This preliminary bonding ensures that struts can be removed cleanly without causing electrode slippage or requiring complex handling procedures.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

Struts are completely extracted from the final product through a simplified removal process. The struts are pulled out through the laminated separator-electrode composite and then cut away, leaving no residual components. This extraction is simplified because the lamination provides a clean interface for strut removal without compromising electrode positioning.

Inventive Principle:
Principle #2Taking out (Extraction)

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

Enables high-speed production of z-shaped electrode-separator assemblies with reduced errors by ensuring secure electrode positioning and efficient strut removal, suitable for both laminatable and non-laminatable separators.

Implementation Method 1

the struts (6) are designed to be heated and/or that a cutting device is provided for cutting through the separator in the area of ​​the struts

Methodology Applied
Scientific EffectMelting: Melting

Implementation Method 2

In a further process step, the arrangement in the final position of the punches can be fixed to form a unit. For this purpose, the punches can be heated in a suitable embodiment as described above, so that the unit is formed by laminating the separator.

Methodology Applied
Scientific EffectLamination: Lamination

Data Source

PatentEP4434100B1Device for folding a separator in a z-shaped manner, and method for producing an electrode-separator assembly
Publication Date: 2025.12.31 MERCEDES BENZ GROUP AG
  • EP4434100B1 patent drawingFigure 1~3
  • EP4434100B1 patent drawingFigure 4~6

AI summary

The invention relates to a device (10) for folding a strip-shaped separator (1), which extends in the longitudinal direction (x), in a z-shaped manner for an electrode-separator assembly of an individual battery cell. The device according to the invention is characterized by two stamps (3) for clamping the separator (1) at the two ends thereof in the longitudinal direction (x), wherein brackets (5) are provided which are arranged between the two stamps (3) and have the same distance to each other in the longitudinal direction (x) that braces (6) have in a transverse direction (y) running transversely to the longitudinal direction (x) and which are received in rails (4) running in the longitudinal direction (x) in a movable manner along the longitudinal direction (1). The rails (4) are designed to be movable in a vertical direction (z) transversely to the longitudinal direction (x) and transversely to the transverse direction (y), and the braces (6) are arranged above and below the clamping position of the separator (1) in the vertical direction (z) in an alternating manner when viewed in the longitudinal direction (x). According to a first method, the separator (1) can be folded and then populated with the electrodes (2), and the electrode-separator assembly is thus produced. Alternatively, a semi-finished product can be produced from the separator (1) and the electrodes (2) laminated thereon, said semi-finished product then being correspondingly folded in a z-shaped manner by the device (10).