Template electrode structures with enhanced adhesion characteristics
Provided herein are novel template electrode materials and structures for lithium ion cells. Related methods are also provided. According to various embodiments, an electrode can include a nanostructured template, an electrochemically active material layer coating the template, and a first intermediate layer between the nanostructured template and the electrochemically active material layer. In one arrangement, the nanostructured template includes silicide nanowires. The electrochemically active material may be any of silicon, tin, germanium, carbon, metal hydrides, silicides, phosphides, and nitrides. The first intermediate layer may facilitate adhesion between the nanostructured template and the electrochemically active material layer, electronic conductivity within the electrode, and/or stress relaxation between the nanostructured template and the electrochemically active material layer.
1. An electrode for use in a lithium ion cell, comprising:
a nanostructured template;
an electrochemically active material layer coating the template; and
a first intermediate layer between the nanostructured template and the electrochemically active material layer;
wherein the nanostructured template comprises silicide nanowires.
2. The electrode of claim 1 wherein the electrochemically active material comprises one or more materials selected from the group consisting of silicon, tin, germanium, carbon, metal hydrides, silicides, phosphides, nitrides, and oxy-nitrides.
3. The electrode of claim 1 wherein the first intermediate layer comprises one or more materials selected from the group consisting of titanium, copper, iron, nickel, and chromium.
4. The electrode of claim 1 , wherein the first intermediate layer has a thickness between about 2 nanometers and 2 micrometers.
5. The electrode of claim 1 wherein the first intermediate layer facilitates one or more of:
adhesion between the nanostructured template and the electrochemically active material layer;
electronic conductivity within the electrode; and
stress relaxation between the nanostructured template and the electrochemically active material layer.
6. The electrode of claim 5 wherein the first intermediate layer facilitates adhesion between the nanostructured template and the electrochemically active material layer by forming a compound and/or an alloy with materials in the electrochemically active material layer and/or in the nanostructured template.
7. The electrode of claim 5 wherein the first intermediate layer facilitates electronic conductivity within the electrode by reducing electronic resistance between the nanostructured template and the electrochemically active material layer.
8. The electrode of claim 5 wherein the first intermediate layer facilitates stress relaxation between the nanostructured template and the electrochemically active material layer because the first intermediate layer has elastic properties that allows it to absorb at least some of the stress from expansion and contraction of the electrochemically active material layer without transmitting all the stress to the nanostructured template.
9. The electrode of claim 1 , further comprising a substrate that is coated with a second intermediate layer, wherein at least the nanostructured template is in contact with the second intermediate layer.
10. The electrode of claim 9 wherein the second intermediate layer facilitates one or more of:
adhesion between the nanostructured template and the substrate;
electronic conductivity within the electrode; and
stress relaxation between the nanostructured template and the substrate.
11. The electrode of claim 9 wherein the second intermediate layer is the same as the first intermediate layer.
12. An electrode for use in a lithium ion cell, comprising:
a conductive substrate having a first surface;
a nanostructured template on the first surface;
an electrochemically active material layer coating the nanostructured template;
a first intermediate layer between the nanostructured template and the electrochemically active material layer; and
a second intermediate layer between the first surface of the conductive substrate and the nanostructured template;
wherein the nanostructured template comprises silicide nanowires.
13. The electrode of claim 12 , wherein the first surface comprises one or more selected from the group consisting of copper, metal oxides, stainless steel, titanium, aluminum, nickel, chromium, tungsten, metal nitrides, metal carbides, carbon, carbon fiber, graphite, graphene, carbon mesh, and conductive polymers.
14. The electrode of claim 12 wherein the conductive substrate comprises a base substrate and a thin metal foil that is attached to the base substrate, wherein the first surface comprises the thin metal foil.
15. The electrode of claim 14 wherein the thin metal foil has a composition that is different from the base substrate.
16. The electrode of claim 2 wherein at least a portion of the electrochemically active material layer further comprises a moderating additive that reduces swelling of the electrochemically active material layer upon lithiation.
17. The electrode of claim 16 wherein the moderating additive has a lithium capacity that is less than the lithium capacity of the electrochemically active material.
18. The electrode of claim 17 wherein the moderating additive has a concentration that varies throughout the electrochemically active material layer.
19. The electrode of claim 18 wherein the moderating additive is selected from the group consisting of oxygen, titanium, tin, germanium, nickel, copper, carbon, nitrogen, aluminum, and tungsten.
20. The electrode of claim 18 wherein the concentration of the moderating additive in the electrochemically active material is highest in regions of the electrochemically active material layer that are adjacent to a conductive substrate.