Solvent-free electrochemical cells with conductive pressure sensitive adhesives attaching current collectors
Provided are electrochemical cells and methods of manufacturing these cells. An electrochemical cell comprises a positive electrode and an electrolyte layer, printed over the positive electrode. In some examples, each of the positive electrode, electrolyte layer, and negative electrode comprises an ionic liquid enabling ionic transfer. The negative electrode comprises a negative active material layer (e.g., comprising zinc), printed over and directly interfacing the electrolyte layer. The negative electrode also comprises a negative current collector (e.g., copper foil) and a conductive pressure sensitive adhesive layer. The conductive pressure sensitive adhesive layer is disposed between and adhered to, directly interfaces, and provides electronic conductivity between the negative active material layer and the negative current collector. In some examples, the conductive pressure sensitive adhesive layer comprises carbon and/or metal particles (e.g., nickel, copper, indium, and/or silver). Furthermore, the conductive pressure sensitive adhesive layer may comprise an acrylic polymer, encapsulating these particles.
1. An electrochemical cell comprising:
a positive electrode;
an electrolyte layer, printed directly over and directly contacting the positive electrode; and
a negative electrode, comprising a negative active material layer, a negative current collector, and a conductive pressure sensitive adhesive layer, wherein:
the negative active material layer is printed directly over and directly contacting the electrolyte layer,
the conductive pressure sensitive adhesive layer directly interfaces, adheres to each of the negative active material layer and the negative current collector, supports the negative active material layer and the negative current collector relative to each other, and provides electronic conductivity between the negative active material layer and the negative current collector, and
the conductive pressure sensitive adhesive layer comprises a polymer base and a conductive filler,
wherein particles of the conductive filler are encapsulated by the polymer base within the conductive pressure sensitive adhesive layer;
a first packaging layer and a second packaging layer, enclosing the positive electrode, the electrolyte layer, and the negative electrode, wherein at least one of the first packaging layer and the second packaging layer is flexible and conforms to the positive electrode, the electrolyte layer, and the negative electrode,
wherein the at least one of the first packaging layer and the second packaging layer is polyester.
2. The electrochemical cell of claim 1 , wherein the conductive pressure sensitive adhesive layer has a thickness of less than 100 micrometers.
3. The electrochemical cell of claim 1 , wherein the conductive filler in the conductive pressure sensitive adhesive layer has a concentration of less than about 50% by volume.
4. The electrochemical cell of claim 1 , wherein the polymer base is an acrylic polymer or polyisobutylene (PIB).
5. The electrochemical cell of claim 1 , wherein the conductive filler comprises carbon particles.
6. The electrochemical cell of claim 5 , wherein the conductive filler further comprises metal particles.
7. The electrochemical cell of claim 6 , wherein the metal particles comprise one or more of nickel, copper, and silver.
8. The electrochemical cell of claim 6 , wherein the metal particles comprise one or more of indium and bismuth.
9. The electrochemical cell of claim 1 , wherein the conductive filler comprises metal particles.
10. The electrochemical cell of claim 1 , wherein particles of the conductive filler have a mean particle size of between about 1 micrometer and 35 micrometers.
11. The electrochemical cell of claim 1 , wherein the negative active material layer comprises zinc.
12. The electrochemical cell of claim 1 , wherein the negative current collector comprises copper.
13. The electrochemical cell of claim 1 , wherein the second packaging layer is flexible and adhered to the negative current collector.
14. The electrochemical cell of claim 1 , wherein each of the positive electrode, the electrolyte layer, and the negative electrode comprises an ionic liquid.
15. The electrochemical cell of claim 1 , wherein the electrochemical cell is substantially free from organic solvents.
16. The electrochemical cell of claim 1 , wherein the negative current collector is a printed layer, comprising a polymer binder and a conductive additive, selected from the group consisting of silver, brass, indium, carbon, nickel, and copper.
17. The electrochemical cell of claim 1 , wherein the negative active material layer consists essentially of an elemental metal.