Anodes for lithium-based energy storage devices, and methods for making same
A method of making an anode for use in an energy storage device includes providing a current collector having an electrically conductive layer and a metal oxide layer overlaying over the electrically conductive layer. The metal oxide layer has an average thickness of at least 0.01 μm. A continuous porous lithium storage layer is deposited onto the metal oxide layer by a CVD process. The anode is thermally treated after deposition of the continuous porous lithium storage layer is complete and prior to battery assembly. The thermal treatment includes heating the anode to a temperature in a range of 100° C. to 600° C. for a time period in a range of 0.1 min to 120 min. The anode may be incorporated into a lithium ion battery along with a cathode. The cathode may include sulfur or selenium and the anode may be prelithiated.
1. A method of making an anode for use in an energy storage device, the method comprising:
providing a current collector comprising an electrically conductive layer and a metal oxide layer overlaying over the electrically conductive layer, wherein the metal oxide layer has an average thickness of at least 0.01 μm;
depositing a continuous porous lithium storage layer onto the metal oxide layer by a CVD process; and
thermally treating the anode after deposition of the continuous porous lithium storage layer is complete and prior to battery assembly,
wherein the thermally treating includes heating the anode to a temperature in a range of 100° C. to 600° C. for a time period in a range of 0.1 min to 120 min.
2. The method of claim 1 , wherein the thermally treating is conducted in an environment having a partial pressure of oxygen and water each less than 1 Torr.
3. The method of claim 2 , wherein the thermally treating is conducted under argon, nitrogen, or vacuum.
4. The method of claim 1 , wherein the temperature range is 350° C. to 600° C.
5. The method of claim 4 , wherein the time period is in a range of 0.1 min to 30 min.
6. The method of claim 1 , wherein the CVD process is a PECVD process.
7. The method of claim 6 , wherein the continuous porous lithium storage layer has a total content of silicon, germanium, or a combination thereof of at least 40 atomic %.
8. The method of claim 6 , wherein the continuous porous lithium storage layer comprises at least 85 atomic % amorphous silicon having a density in a range of 1.1 g/cm 3 to 2.2 g/cm 3 .
9. The method of claim 1 , wherein the electrically conductive layer comprises nickel or copper.
10. The method of claim 9 , wherein the metal oxide layer comprises a transition metal oxide.
11. The method of claim 10 , wherein the transition metal oxide is an oxide of nickel or titanium.
12. The method of claim 1 , wherein the electrically conductive layer comprises copper and the metal oxide layer comprises an oxide of titanium having a thickness in a range of 0.01 μm to 0.20 μm.
13. The method of claim 1 , further comprising depositing a layer of lithium metal over the continuous porous lithium storage layer before the thermally treating step.
14. The method of claim 1 , further comprising at least partially prelithiating the anode after thermally treating to form a lithiated storage layer.
15. The method of claim 1 , wherein the thermally treating comprises transfer of the anode to an oven, exposure of the anode to a source of IR radiation, or contact of the anode with a heated surface.
16. The method of claim 1 , wherein the thermally treating:
(i) increases the electrical conductivity of the continuous porous lithium storage layer;
(ii) increases the adhesion of the continuous porous lithium storage layer to the current collector; or
(iii) forms an anode having a higher charge capacity in a lithium-ion battery cell than an equivalent anode not receiving the thermally treating step;
(iv) forms an anode capable of faster charging in a lithium-ion battery cell than an equivalent anode not receiving the thermally treating step; or
(v) any combination of (i), (ii), (iii), or (iv).
17. A lithium-ion battery comprising a cathode and an anode, wherein the anode is made by the method of claim 1 .
18. The lithium-ion battery of claim 17 wherein the cathode comprises sulfur, selenium, or both sulfur and selenium, and the anode is at least partially prelithiated to form a lithiated storage layer.
19. The lithium-ion battery of claim 18 , wherein the lithiated storage layer includes lithium in a range of 50% to 100% of the theoretical lithium storage capacity of the continuous porous lithium storage layer.
20. The lithium-ion battery of claim 17 , wherein the battery is characterized by a charging rate of least 1 C and a charge capacity of at least 2.0 mAh per square centimeter of anode.