Thin film electrochemical cell with a polymer double seal
A double-sealed thin film electrochemical pouch cell, comprising a cathode current collector, a cathode, an electrolyte, an anode, and an anode current collector, which is double-sealed by a first inner laminate layer forming a primary seal covered by a second outer polymer layer forming a secondary seal. The second outer polymer layer comprises embedded particles to increase the thermal conductivity of the second outer polymer layer.
1. A thin film electrochemical pouch cell comprising:
an electrode assembly comprising a cathode current collector, a cathode, an electrolyte, an anode, and an anode current collector;
a first polymer layer forming a primary seal area substantially enclosing the electrode assembly; and
a second polymer layer forming a secondary seal area covering at least a portion of the first polymer layer,
wherein the secondary seal area extends along the primary seal area, and
wherein the second polymer layer is a heat-dissipating polymer layer that comprises embedded particles to increase a thermal conductivity of the second polymer layer.
2. The cell according to claim 1 , wherein the first polymer layer comprises a metal-polymer laminate foil having at least one metal layer and at least one polymer layer.
3. The cell according to claim 2 , wherein the at least one metal layer comprises aluminium.
4. The cell according to claim 1 , wherein the second polymer layer comprises one of polypropylene and polyurethane.
5. The cell according to claim 1 , wherein the first polymer layer and the second polymer layer are comprised of two different polymer materials.
6. The cell according to claim 5 , wherein the first polymer layer forming the primary seal area is selected to provide diffusive resistance to a first species and the second polymer layer forming the secondary seal area is selected to provide diffusive resistance to a second species.
7. The cell according to claim 1 , wherein the cell is selected from one of a lithium ion cell, a primary battery cell and a secondary battery cell.
8. The cell according to claim 1 , further comprising one of a sealed reservoir and a vacuum gap spaced between the first polymer layer and the second polymer layer.
9. The cell according to claim 1 , further comprising a third polymer layer sealed overtop the second polymer layer.
10. The cell according to claim 1 , wherein the electrode assembly is encased in the first polymer layer and the second polymer layer completely envelops the first inner polymer layer.
11. The cell according to claim 1 ,
wherein the cell is rectangular shaped and further comprises two electrically conductive tabs; and
wherein the two electrically conductive tabs are arranged on one of a same short edge of the rectangular cell, a same long edge of the rectangular cell and on diametrically opposing edges of the rectangular cell.
12. The cell according to claim 11 , wherein the first polymer layer is sealed along all outer perimeter edges.
13. The cell according to claim 1 , wherein the first polymer layer comprises a sheet folded over itself to encompass the electrode assembly and being sealed alone one or more outer perimeter edges.
14. The cell according to claim 1 , wherein said first polymer layer and second polymer layers are about 2 μm in thickness.
15. The cell according to claim 1 , wherein the embedded particles are composed of a ceramic material.
16. The cell according to claim 15 , wherein the ceramic material is one of aluminum nitride, boron nitride and graphite.
17. The cell according to claim 1 , wherein the embedded particles increase an electrical resistivity of the second polymer layer.
18. The cell according to claim 1 , wherein the embedded particles are present in concentrations greater than 5%.
19. The cell according to claim 1 , wherein an outer surface of the second polymer layer has an emissivity greater than about 0.9.
20. The cell according to claim 1 , wherein the embedded particles increase a surface roughness of the second polymer layer.
21. The cell according to claim 1 , wherein the second polymer layer is a non-uniform polymer layer, the non-uniform polymer layer being applied to selected regions covering the first polymer layer to promote heat transfer in the selected regions.
22. The cell according to claim 21 , wherein the selected regions are spaced away from the electrically conductive tabs.
23. The cell according to claim 22 , wherein the non-uniform polymer layer comprises at least one of a variation in thickness of the non-uniform polymer layer and a variation in coverage over the first polymer layer.
24. A battery comprising a plurality of cells, wherein each of the plurality of cells is a thin film electrochemical pouch cell comprising:
an electrode assembly comprising a cathode current collector, a cathode, an electrolyte, an anode, and an anode current collector;
a first polymer layer forming a primary seal area substantially enclosing the electrode assembly; and
a second polymer layer forming a secondary seal area covering at least a portion of the first polymer layer;
wherein at least one of the plurality of cells comprises a non-uniform second polymer layer having a variation in one of thickness and coverage over the first polymer layer to promote uniform temperature distribution across the battery,
wherein the second polymer layer is a heat-dissipating polymer layer that comprises embedded particles to increase a thermal conductivity of the second polymer layer, and
wherein the secondary seal area extends along the primary seal area.
25. The battery according to claim 24 , wherein a heat-dissipating label is located on the outer surface of the battery.
26. The battery according to claim 11 , wherein the two electrically conductive tabs are arranged on one of a same short edge of the rectangular cell and a same long edge of the rectangular cell.