Separator for cylindrical cells

• US 20070082260A1
• Filed: 11/05/2003
• Published: 04/12/2007
• Est. Priority Date: 11/05/2003
• Status: Active Grant

• Current Assignee: Tesla Inc.
• Original Assignee: Hibar Systems Ltd. (Tesla Inc.)
• Inventors: Slivar, Djuro
• Granted Patent: US 8,389,148 B2
• Time in Patent Office: Days
• US Class Current: 429/133
• CPC Class Codes: H01M 10/283 Cells or batteries with two cup-shaped or cylindrical collectors H01M10/281 takes precedence
• CPC Class Codes: H01M 50/403 Manufacturing processes of separators, membranes or diaphragms
• CPC Class Codes: H01M 50/417 Polyolefins
• CPC Class Codes: H01M 50/429 Natural polymers
• CPC Class Codes: H01M 50/44 Fibrous material
• CPC Class Codes: H01M 50/449 having a layered structure
• CPC Class Codes: H01M 50/469 tubular or cylindrical
• CPC Class Codes: Y02E 60/10 Energy storage using batteries
• CPC Class Codes: Y02P 70/50 Manufacturing or production processes characterised by the final manufactured product
• CPC Class Codes: Y10T 29/49108 Electric battery cell making
• CPC Class Codes: Y10T 29/4911 including sealing
• CPC Class Codes: Y10T 29/49112 including laminating of indefinite length material
• CPC Class Codes: Y10T 29/49114 including adhesively bonding
• CPC Class Codes: Y10T 29/53135 Storage cell or battery
• CPC Class Codes: Y10T 29/53139 including deforming means

Abstract

Separator for cylindrical cell of the outwardly guided type, wherein a sheet material is wound around a mandrel, and starting from the winding step until the insertion of a separator into the cell, an outward support is used that renders the binding of neighboring turns of the separator winding unnecessary, and the separator sheet has an extended portion, with the extension being at least equal to the radius of the separator cylinder, and with this extended portion being wetted with distilled or de-ionized water until the material softens and the winding and the mandrel are rotated and the bottom part is folded back and heat fused to close the separator cylinder.

Claims

1. A cylindrical separator for cylindrical cells, comprising a cylindrical body constituted by a layered structure of a plurality of turns of a first sheet material wound around a mandrel, and a bottom part closing a first end of said cylindrical body and being formed of an extended portion of said body past said first end by guided wet forming when said cylindrical body being rotated while being on said mandrel, and said bottom part being pressed and heat fused.

2. The cylindrical separator as claimed in claim 1, wherein the first sheet material is a nonwoven, paper-like material.

3. The cylindrical separator as claimed in claim 1, wherein said cylindrical body being made from a plurality of sheets placed onto one another and wound together.

4. The cylindrical separator as claimed in claim 3, wherein said sheets comprise at least one layer of semi permeable membrane, such as a cellophane layer or grafted micro-porous polyolefin.

5. The cylindrical separator as claimed in claim 1, wherein said turns being not affixed to each other and said cylindrical body being encircled from outside by a cylindrical supporting member, said member being constituted during said winding and forming step by a winding nest and during and after placement into a cell by the cylindrical inner wall of the cell.

6. The cylindrical separator as claimed in claim 1, comprising a thermoplastic sealant arranged at the outer central zone of said bottom part.

7. A method for making the cylindrical separator as claimed in claim 1 comprising the steps of:

providing a sheet separator material of predetermined length and width, wherein the length defining the number of turns and the width being at least as long as the length of the cylindrical portion of the separator plus an extended portion being at least the half diameter of the separator;

winding said sheet material around a mandrel by rotating said mandrel in a first direction, wherein said mandrel extends till said extended portion of the separator;

supporting the outside of the winding by means of a winding nest;

applying a predetermined amount of water to said extended portion during any of the foregoing steps to soften said sheet material at the extended portion,

gradually folding said wetted extended portion when said separator and said mandrel being rotated to provide a closed end portion for the separator;

causing said mandrel and said separator to stop rotation;

heat fusing said wet portion; and

introducing said separator into the cylindrical cavity of a semi-finished cell by pushing said closed bottom portion by means of a pin forming part of said mandrel, wherein during said introduction step said outside support of the separator is gradually provided by the interior of said cell after the separator leaves said winding nest; and

withdrawing said mandrel from the interior of said separator.

8. The method as claimed in claim 7, wherein the cut length of the sheet material can be adjusted on-line.

9. The method as claimed in claim 7, wherein at least two sheet materials placed on one another being wound during said winding step.

10. The method as claimed in claim 7, wherein at least one sheet being a layer of a semi permeable membrane, such as a cellophane layer or grafted micro-porous polyolefin.

11. The method as claimed in claim 7, further comprising the step of slightly pressing said rotating separator on said mandrel from the outside by a belt moved with the required peripheral speed of the rotating separator through the whole period of rotation.

12. The method as claimed in claim 7, wherein during said folding step providing a support surface by using a head portion of said mandrel shaped to the required profile of said bottom portion of the separator.

13. The method as claimed in claim 7, wherein during said folding step moving the separator with the mandrel and with the winding nest along a path of a folding rail provided with a groove having a varying profile to force forming of said extended portion.

14. The method as claimed in claim 11, wherein said heat fusing step being carried out by a heated die shaped to the required profile of said separator bottom portion and being pressed against said head portion of said mandrel.

15. The method as claimed in claim 7, wherein said mandrel consisting of an outer sleeve and a pin arranged co-axially therein and during said introducing step said pushing being provided by said pin, and during said withdrawal step first said sleeve being withdrawn followed by the withdrawal of said pin.

16. The method as claimed in claim 7, further comprising the step of applying a thermoplastic sealant of predetermined volume on the central zone of said bottom portion following said heat fusing step.

17. The method as claimed in claim 7, wherein all of said steps being synchronized with elementary movements of a cell manufacturing line.