Variable volume containment for energy storage devices
A stacked energy storage device (ESD) has at least two cell segments arranged in a stack. Each cell segment may have a first electrode unit having a first active material electrode, a second electrode unit having a second active material electrode, and an electrolyte layer between the active material electrodes. Variable volume containment may be used to control the inter-electrode spacing within each cell segment. In some embodiments, one or more dynamic flexible gaskets may be included in each cell segment to seal the electrolyte within the cell segment and to deform in preferred directions. In some embodiments, hard stops may set the inter-electrode spacing of the ESD.
1. An energy storage device (ESD) comprising:
at least two bi-polar electrode units provided in a stacking direction, wherein each electrode unit comprises:
a conductive substrate;
a positive active material electrode layer on a first surface of the conductive substrate; and
a negative active material electrode layer on a second surface of the conductive substrate;
an electrolyte layer provided between the electrode units;
a flexible gasket positioned about the electrolyte layer wherein the gasket is mechanically deformable in a predetermined direction along at least the stacking direction and along an axis normal to the stacking direction; and
a rigid component positioned about the flexible gasket, wherein the rigid component and the flexible gasket are separated by a gap, and wherein the flexible gasket is configured to mechanically deform into the gap.
2. The ESD of claim 1 wherein the flexible gasket maintains the inter-electrode spacing of the positive active material electrode layer and the negative active material electrode layer during operation of the ESD.
3. The ESD of claim 1 wherein the flexible gasket minimizes the movement of the positive active material electrode layer and the negative active material electrode layer relative to one another.
4. The ESD of claim 1 further comprising:
a plurality of springs, the springs configured to deflect in response to an increase in the pressure within the ESD.
5. The ESD of claim 1 further comprising a separator within the electrolyte layer, the separator electrically isolating a respective positive active material electrode layer from a respective negative active material electrode layer.
6. The ESD of claim 1 further comprising a hard stop positioned radially outwardly from the gasket.
7. The ESD of claim 6 wherein the hard stop comprises an inner rim with a shelf on which the respective outer edge of the plurality of electrodes is aligned.
8. The ESD of claim 7 wherein the shelf on the inner rim sets the spacing between adjacent electrodes of the ESD.
9. The ESD of claim 6 wherein the hard stop further comprises:
a plurality of studs; and
a plurality of stud holes, the plurality of stud holes adapted to engage a respective stud on an adjacent hard stop.
10. The ESD of claim 9 wherein the studs are adapted to engage the stud holes to align adjacent hard stops without the use of tools.
11. The ESD of claim 9 wherein the plurality of studs align a substrate flange of the substrate to the hard stop by keeping the substrate centered on an axis colinear with the stacking direction of the stack assembly.
12. The ESD of claim 6 wherein the hard stop comprises an outer rim having a set of holes for a plurality of compression bolts, the holes aligning the stack of electrodes during assembly and providing stability during operation of the ESD.
13. The ESD of claim 1 wherein the predetermined direction is in a stacking direction that is normal to the surface of the electrodes.
14. The ESD of claim 1 wherein the predetermined direction is radially outwardly from a stacking direction.
15. The ESD of claim 1 wherein the predetermined direction is in an off-axes direction.
16. The ESD of claim 1 wherein the flexible gasket has a plurality of predetermined directions.
17. The ESD of claim 1 wherein the deformation of the gasket reduces internal stresses within each cell of the ESD by equalizing pressure within the ESD while maintaining optimal inter-electrode spacing.
18. The ESD of claim 1 wherein the electrolyte layer is sealed by the conductive substrates of the electrode units and the flexible gasket positioned about the electrolyte layer.
19. The ESD of claim 1 wherein the rigid component is one of a hard stop, containment vessel, or wrapper.