Manufacturing process and apparatus for electrically insulating layers of electrochemical cell laminates
View Patent ↗A manufacturing process and an apparatus to carry out the process are disclosed which eliminate or at least significantly reduce the occurrence of damaging localized short circuits in the production of electrochemical generators. The process and apparatus include cauterization by oxidation of the anode edges of multiple electrochemical cell laminates thereby rendering the anode edges electrically insulated from adjacent cathodes and/or current collectors.
1. A process for assembling an alkali metal polymer electrochemical generator, said process comprising:
stacking a plurality of electrochemical cell laminates to form a bundle having a pair of sides, each of said electrochemical cell laminates including:
a) an alkali metal anode;
b) an electrolyte separator;
c) a cathode;
d) a cathode current collector;
covering said bundle at least in part with a protective layer for sealing said bundle with the exception of at least one side of said bundle;
applying reactive fluid onto said at least one side of said bundle such as to oxidize an exposed edge of at least one of said alkali metal anodes and thereby dissolve a portion of said exposed edge, said exposed edge receding away from said at least one side of said bundle for preventing electrical contact between said alkali metal anodes and adjacent cathodes or cathode current collectors.
2. A process as defined in claim 1 wherein said protective layer is a protective casing having at least one opening for alignment with said at least one side.
3. A process as defined in claim 1 wherein said fluid is applied in the form of a jet spray.
4. A process as defined in claim 1 , wherein said alkali metal anode comprises lithium metal or lithium metal alloys.
5. A process as defined in claim 1 , wherein said fluid is selected from the group consisting of water, distilled water, alcohol, methanol, halogenated compounds, sulphured compounds and oxygenated compounds.
6. A process as defined in claim 5 , wherein said fluid is water or distilled water.
7. A process as defined in claim 5 , wherein said fluid is methanol.
8. A process as defined in claim 1 , further comprising drying said at least one side of said bundle using an air stream jet.
9. A process as defined in claim 1 , further comprising monitoring the voltage of said bundle throughout said process.
10. A process as defined in claim 1 , wherein said process is carried out in a ventilated area to evacuate said fluid and particles from the oxidized portion of said exposed edge.
11. A process for electrically insulating an electrochemical bundle, the bundle including a stack of electrochemical cell laminates, each laminate including an alkali metal anode, an electrolyte separator, a cathode and a cathode current collector, said process comprising:
covering the bundle at least in part with a protective layer for sealing the bundle with the exception of at least one side of the bundle;
applying reactive fluid onto the at least one side of the bundle such as to oxidize an exposed edge of at least one of the alkali metal anodes for preventing electrical contact between the at least one alkali metal anode and adjacent cathodes or cathode current collectors;
drying the at least one side of the bundle.