Electrode structures
A structure for use in an energy storage device, the structure comprising a backbone system extending generally perpendicularly from a reference plane, and a population of microstructured anodically active material layers supported by the lateral surfaces of the backbones, each of the microstructured anodically active material layers having a void volume fraction of at least 0.1 and a thickness of at least 1 micrometer.
1. An electrochemical stack for use in an energy storage device, the stack comprising, in a stacked arrangement, a population of cathode structures comprising cathode current collectors and cathodically active material layers, separator layers, and a population of anode structures comprising backbone anode current collectors disposed between anodically active material layers, the separator layers being disposed between the cathodically active material layers of members of the population of cathode structures and anodically active material layers of members of the population of anode structures,
the backbone anode current collectors having an electrical conductance that is substantially greater than the electrical conductance of the anodically active material layers,
the direction of stacking of the cathode current collectors, cathodically active material layers, separator layers, backbone anode current collectors, and anodically active material layers being parallel to the reference plane, the carrier ions having a direction of travel between the cathodically active material layers and the anodically active materials that is generally parallel to the reference plane as the secondary battery is charged and discharged,
the members of the population of anode structures each comprise anodically active material layers having a height, H A , of from 1000 micrometers to 10,000 micrometers measured in a direction orthogonal to the reference plane, a front surface, a back surface adjacent the backbone anode current collector of the anode structure member, a thickness, T, measured from the front surface to the back surface, and a void volume fraction of at least 0.1, wherein the front and back surfaces are substantially perpendicular to the reference plane, the thickness, T, is at least 1 micrometer and measured in a direction parallel to the reference plane, and the anodically active material layers comprise a fibrous or a porous anodically active material, and wherein the lineal distance, D L , between at least two members of the population of anodically active material layers, measured in a direction parallel to the reference plane, is greater than the maximum value of H A for the population.
2. The electrochemical stack of claim 1 , wherein the carrier ions are lithium ions.
3. The electrochemical stack of claim 1 , wherein each member of the population of anode structures has a height, H A of at least 100 micrometers but less than 5,000 micrometers.
4. The electrochemical stack of claim 1 , wherein each member of the population of anode structures comprises a porous silicon layer having a void volume fraction of at least 0.1 but less than 0.8.
5. The electrochemical stack of claim 1 , wherein each member of the population of anode structures comprises a porous silicon layer having a void volume fraction of at least 0.25 but less than 0.6.
6. The electrochemical stack of claim 1 , wherein each member of the population of anode structures comprises a porous silicon layer having a thickness T of from 1 to 200 micrometers.
7. The electrochemical stack of claim 1 , wherein each member of the population of anode structures comprises a porous silicon layer having a thickness T of from 10 to 80 micrometers.
8. The electrochemical stack of claim 1 , wherein the number of anode structures in the electrochemical stack is at least 10.
9. The electrochemical stack of claim 1 , wherein the number of anode structures in the electrochemical stack is at least 20.
10. The electrochemical stack of claim 1 , wherein the number of anode structures in the electrochemical stack is at least 100.
11. The electrochemical stack of claim 1 , wherein the backbone anode current collector is in contact with the back surface of the anodically active material layer for each member of the population of anode structures.
12. The electrochemical stack of claim 1 , wherein backbone anode current collector of each member of the population of anode structures comprises a metal.
13. The electrochemical stack of claim 12 , wherein the metal comprises at least one metal selected from the group consisting of aluminum, copper, nickel, cobalt, titanium and tungsten.
14. The electrochemical stack of claim 1 , wherein a ratio of the electrical conductance of the backbone anode current collector to the electrical conductance of the anodically active material layer is at least 100:1 for each member of the population of anode structures.
15. The electrochemical stack of claim 1 , wherein each member of the population of anode structures comprises a porous silicon layer that is a microporous material having pore dimensions of less than 10 nm.
16. The electrochemical stack of claim 1 , wherein each member of the population of anode structures comprises a porous silicon layer that is a mesoporous material having a pore dimension of from 10 nm to 50 nm.
17. The electrochemical stack of claim 1 , wherein each member of the population of anode structures comprises a porous silicon layer that is a macroporous material having a pore dimension of greater than 50 nm.
18. A secondary battery comprising at least two of the electrochemical stacks of claim 1 , wherein the electrochemical stacks are stacked relative to each other in a direction that is orthogonal to the reference plane.
19. An electrochemical stack for use in an energy storage device, the stack comprising, in a stacked arrangement, a population of cathode structures comprising cathode current collectors and cathodically active material layers, separator layers comprising microporous separator material, and a population of anode structures comprising backbone anode current collectors disposed between anodically active material layers, the separator layers being disposed between the cathodically active material layers of members of the population of cathode structures and anodically active material layers of members of the population of anode structures,
the backbone anode current collectors having an electrical conductance that is substantially greater than the electrical conductance of the anodically active material layers,
the direction of stacking of the cathode current collectors, cathodically active material layers, separator layers, backbone anode current collectors, and anodically active material layers being parallel to the reference plane, the carrier ions having a direction of travel between the cathodically active material layers and the anodically active materials that is generally parallel to the reference plane as the secondary battery is charged and discharged,
the members of the population of anode structures each comprise anodically active material layers having a height, H A , of from 1000 to 10,000 micrometers measured in a direction orthogonal to the reference plane, a front surface, a back surface adjacent the backbone anode current collector of the anode structure member, a thickness, T, measured from the front surface to the back surface, and a void volume fraction of at least 0.1, wherein the front and back surfaces are substantially perpendicular to the reference plane, the thickness, T, is at least 1 micrometer and measured in a direction parallel to the reference plane, and the anodically active material layers comprise a fibrous or a porous anodically active material, and wherein the lineal distance, D L , between at least two members of the population of anodically active material layers, measured in a direction parallel to the reference plane, is greater than the maximum value of H A for the population, and
wherein anodically active material layers of the members of the population of anode structures are surrounded with insulating material including the separator layer.