Direct printing of 3-d microbatteries and electrodes
Various embodiments disclosed relate to novel methods of fabricating 3-D Li ion batteries using direct nanoimprint lithography. The present invention includes methods of fabricating high surface area electrodes, including imprint patterning of high aspect ratio parallel grating style electrodes. The method includes coating a substrate with an ink containing nanoparticles and subsequently annealing the ink into a desired pattern.
1. A method of fabricating an electrode, comprising:
depositing an ink comprising electroactive nanoparticles, and optionally at least one conductive additive, on a substrate comprising an electrical contact to form a film;
stamping the film with a mold to form a patterned film;
annealing the patterned film to form an electrode;
planarizing the electrode by depositing at least one layer of a crosslinkable pre-polymer on the electrode, followed by curing to form a planarized layer; and
forming additional electrodes by performing additional cycles of the depositing, the stamping, the annealing, the planarizing, and the curing;
wherein in each successive cycle a substantially parallel grating pattern is formed substantially perpendicular to and overlapping a previously deposited and adjacent grating pattern, wherein the method forms a multilayer or stacked structure of the grating patterns with the grating patterns substantially perpendicular and alternating in orientation.
2. The method of claim 1 , wherein the ink comprises a dispersion of metal oxide nanoparticles.
3. The method of claim 2 , wherein the metal oxide nanoparticles comprise number-averaged and volume-averaged particle sizes of about 1 nm to about 25 nm.
4. The method of claim 2 , wherein the metal oxide nanoparticles are TiO 2 .
5. The method of claim 2 , wherein the metal oxide nanoparticles are crystalline.
6. The method of claim 2 , wherein metal oxide nanoparticles comprise about 1-25 wt % of the dispersion.
7. The method of claim 1 , wherein the patterned film comprises a shape selected from serpentine lines, parallel zig-zag lines, grid structures, concentric circles, regular polygons, or combinations thereof.
8. The method of claim 7 , wherein the electrode has the shape of the patterned film.
9. The method of claim 1 , wherein up to six total electrode layers are deposited to form a three-dimensional electrode.
10. The method of claim 9 , wherein a specific capacity of the three-dimensional electrode is proportional to the number of electrode layers.
11. A method of fabricating electrodes, comprising:
spin-coating an ink comprising about 3 wt % TiO 2 nanoparticles, comprising number-averaged and volume-averaged particle sizes of about 1 nm to about 25 nm, dispersed in an alcohol solvent on a gold contact formed on a silicon dioxide substrate to form a film;
stamping the film with a mold to form a film having a substantially parallel grating pattern, wherein the grating pattern has a spacing of about 1 and each grating has a height of about 0.01 μm to about 0.25 μm and a width of about 0.01 μm to about 0.25 μm;
annealing the patterned film to form an electrode layer;
planarizing the electrode by depositing at least one layer of a crosslinkable pre-polymer on the electrode layer, followed by curing to form a planarized layer; and
forming at least five additional electrodes by additional cycles of the spin-coating, the stamping, the annealing, the planarizing, and the curing;
wherein in each successive cycle the parallel grating pattern is formed substantially perpendicular to and overlapping a previously deposited and adjacent grating pattern, and wherein the method forms a multilayer or stacked structure of the grating patterns with the grating patterns substantially perpendicular and alternating in orientation.
12. A method of fabricating electrodes, comprising:
depositing a first ink comprising electroactive nanoparticles, and optionally at least one conductive additive, on a substrate to form a film;
stamping the film with a mold to form a stamped structure;
annealing the stamped structure to form a first electrode;
depositing on the first electrode at least one layer of a separator; and
backfilling the stamped structure with a second ink comprising electroactive nanoparticles to form a second electrode.
13. The method of claim 12 , wherein the depositing of the first ink on the substrate comprises spin-coating.
14. The method of claim 12 , wherein the first ink comprises a dispersion of metal oxide nanoparticles.
15. The method of claim 14 , wherein the metal oxide nanoparticles are LiMn 2 O 4 (LMO).
16. The method of claim 14 , wherein the metal oxide nanoparticles are Li 4 Ti 5 O 12 (LTO).
17. The method of claim 12 , wherein the depositing of the at least one layer of the separator on the first electrode comprises grafting a polymer onto the first electrode.