Apparatus and method for processing a coated sheet
Apparatus and method are described that are useful in preparing a tabbed electrode sheet for use in assembling an electrochemical storage device. To provide clean surfaces for attaching conductive tabs, portions of a coated electrode sheet are selectively removed by contacting the sheet with heat and solvent, and mechanically removing electrode material in solvent-exposed areas.
1 . An apparatus for selectively removing portions of a coated sheet, the apparatus comprising:
(a) a heating station having a heated surface for receiving a coated electrode sheet;
(b) a solvent applicator positioned to deliver solvent to one or more selected portions of a coated electrode sheet; and
(c) a scraper positioned to contact a coated electrode sheet and remove electrode coating from portions of the coated electrode sheet exposed to heat and solvent.
2 . The apparatus of claim 1 , wherein the solvent applicator comprises a liquid pump and a solvent absorbent wick or pad.
3 . The apparatus of claim 1 , wherein the solvent applicator comprises a spray dispenser or roller.
4 . The apparatus of claim 1 , wherein the heated surface is a plate secured to a base.
5 . The apparatus of claim 4 , further comprising a cartridge heater housed in the body of the base.
6 . The apparatus of claim 1 , wherein the scraper comprises a blade or brush.
7 . The apparatus of claim 1 , further comprising a temperature control circuit.
8 . The apparatus of claim 1 , further comprising a thermocouple positioned adjacent to the heated surface.
9 . The apparatus of claim 1 , further comprising a spool positioned to take up a scraped coated sheet.
10 . The apparatus of claim 1 , further comprising a tab applicator positioned to attach conductive tabs to scraped portions of a coated sheet at an exit end of the apparatus.
11 . The apparatus of claim 10 , wherein the tab applicator includes a welder.
12 . A method for selectively removing portions of a coated sheet, the method comprising:
(a) heating a region of a coated sheet, the sheet comprising a conductive substrate and an electrode layer;
(b) applying solvent to one or more selected portions of the electrode layer in a region of the coated sheet that is heated, wherein solvent is applied before, after, or simultaneously with heating; and
(c) removing the solvent-exposed portions of the electrode layer to expose the underlying conductive substrate.
13 . The method of claim 12 , wherein a region of the coated sheet is heated to a temperature of about 100° C. or greater.
14 . The method of claim 12 , wherein the solvent is heated.
15 . The method of claim 12 , wherein the solvent is applied from a solvent-saturated wick or pad.
16 . The method of claim 15 , wherein the solvent-saturated wick or pad is heated to a temperature of about 100° C. or greater.
17 . The method of claim 12 , wherein the solvent is applied by spraying or rolling.
18 . The method of claim 12 , wherein a dwell time is established during which the heat and solvent fluxes flow in opposite directions.
19 . The method of claim 18 , wherein the dwell time is from about 0.1 second to about 5 seconds.
20 . The method of claim 12 , wherein the electrode layer comprises a binder and the solvent dissolves or swells the binder.
21 . The method of claim 12 , wherein the solvent-exposed portion of the electrode layer is removed by mechanical abrasion.
22 . The method of claim 21 , wherein mechanical abrasion comprises brushing or scraping.
23 . The method of claim 12 , further comprising winding the coated sheet onto a spool.
24 . The method of claim 12 , further comprising attaching a conductive tab to the exposed conductive substrate.
25 . The method of claim 24 , wherein the tab is attached by welding, riveting or crimping.