Cylindrical Cell Lithium Anode Press-Contacting Without Edge Overlap

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Solution Overview

Problem

The prior art process for swaging lithium sheets onto the inner surface of a cylindrical casing tube results in the sheets being in contact at the overlap, leading to deformation and potential tearing due to lithium's sticky nature, which can cause unpredictable cell discharge.

Innovation Solution

The process involves using a cylindrical mandrel and forming tools to wrap and swage lithium sheets onto the casing tube without them ever touching, maintaining a gap of 0.5° to 1° between adjacent edges, ensuring they are pressed into direct contact with the tube surface without deformation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If lithium sheets are wrapped around an expandable tool and pressed onto the casing tube, then the lithium sheets can be contacted to the inner surface of the casing, but the sheets may deform or tear at the overlap due to lithium's sticky nature

Engineering Contradiction:
Improveuniformity of lithium sheet contactVSAvoidintegrity of lithium sheet
Core Design Contradiction:
Manufacturing precisionVSStrength

Solution Approach 1:

The invention uses two separate lithium sheets instead of one continuous sheet wrapped around the tool. Each sheet is independently contacted to the casing tube inner surface, eliminating the overlap region where deformation and tearing would occur. The sheets are positioned to be spaced apart by a small distance, ensuring they never contact each other during the swaging process.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The invention removes the problematic overlap region from the process by not wrapping the lithium sheet around itself. Instead of creating a 360-degree wrap with an overlap, the process extracts the harmful overlap portion and uses multiple separate sheets that are individually contacted to the casing surface.

Inventive Principle:
Principle #2Taking out (Extraction)

2Area of stationary object

If a single lithium sheet is wrapped around the expandable tool to cover the entire circumference, then complete coverage is achieved, but the sheets must overlap and contact each other causing deformation

Engineering Contradiction:
Improvecoverage area of lithium anodeVSAvoidshape uniformity of lithium sheet
Core Design Contradiction:
Area of stationary objectVSShape

Solution Approach 1:

The circumferential coverage is achieved through segmentation by using multiple separate lithium sheets (at least two sheets) that are individually contacted to the casing tube. The sheets are positioned adjacent to each other with small spacing, collectively providing substantial circumferential coverage without requiring overlap.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The invention accepts that there will be small gaps between adjacent lithium sheets (spaced apart by a small distance) rather than achieving complete continuous coverage. This partial coverage approach eliminates the need for overlap and the associated deformation problems, prioritizing sheet integrity over complete seamless coverage.

Inventive Principle:
Principle #16Partial or excessive action

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

This method prevents deformation and tearing of lithium sheets, ensuring a uniform and stable anode structure for the electrochemical cell, enhancing the reliability of cell discharge.

Implementation Method 1

The process involves using a cylindrical mandrel and forming tools to wrap and swage lithium sheets onto the casing tube without them ever touching, maintaining a gap of 0.5° to 1° between adjacent edges, ensuring they are pressed into direct contact with the tube surface without deformation

Methodology Applied
Scientific EffectMechanical Force: Mechanical Force

Data Source

PatentEP4318746A1Process for press-contacting a lithium anode onto the inner surface of a cylindrical cell casing
Publication Date: 2024.02.07 GREATBATCH LTD
  • EP4318746A1 patent drawingFigure 1
  • EP4318746A1 patent drawingFigure 2
  • EP4318746A1 patent drawingFigure 3~4

AI summary

An electrochemical cell has a cylindrically-shaped casing tube with at least first and second lithium sheets swaged onto its inner surface. The first lithium sheet has respective spaced apart first right and left edges, and the second lithium sheet has spaced apart second right and left edges. The first and second right edges and the first and second left edges of the swaged first and second lithium sheets are adjacent to but spaced apart from each other by about 0.5° to about 1° about the inner circumference of the cylindrically-shaped casing tube. A novel process for swaging the first and second lithium sheets onto the inner surface of the casing tube is also described.