Structured silicon anode
A battery can be fabricated from a substrate including silicon. This allows the battery to be produced as an integrated unit. The battery includes a anode formed from an array of spaced elongated structures, such as pillars, which include silicon and which can be fabricated on the substrate. The battery also includes a cathode which can include lithium.
1. An electrode for a battery comprising a plurality of silicon-comprising elongated structures extending from a substrate and arranged to engage with a lithium-based cathode and a lithium-based electrolyte, wherein the elongated structures have a length greater than 1 micron.
2. An electrode as claimed in claim 1 wherein the elongated structures have a gravimetric capacity of at least 780 mAh/g for the first 10 cycles.
3. An electrode as claimed in claim 1 wherein the elongated structures have a gravimetric capacity of at least 620 mAh/g for the first 50 cycles.
4. An electrode as claimed in claim 1 wherein the elongated structures have a volumetric capacity of at least 1800 mAh/cm 3 for the first 10 cycles.
5. An electrode as claimed in claim 1 wherein the elongated structures have a volumetric capacity of at least 1450 mAh/cm 3 for the first 50 cycles.
6. An electrode as claimed in claim 1 wherein the electrode is arranged to tolerate the conditions occasioned by the volume changes caused by charging/discharging.
7. An electrode as claimed in claim 1 wherein the elongated structures do not exceed a fractional coverage of 0.5 of the substrate.
8. An electrode as claimed in claim 1 wherein the elongated structures have a diameter of up 1.0 micron.
9. A lithium-ion battery electrode comprising:
a plurality of spaced elongated structures each attached at one end to a substrate and extending away therefrom,
wherein the elongated structures comprise silicon.
10. A lithium-ion battery electrode as claimed in claim 9 wherein the elongated structures have a gravimetric capacity of at least 620 mAh/g for the first 50 cycles.
11. A lithium-ion battery electrode as claimed in claim 9 wherein the elongated structures have a volumetric capacity of at least 1450 mAh/cm 3 for the first 50 cycles.
12. An energy storage device comprising: a plurality of silicon-comprising elongated structures extending from a substrate; and a cathode, wherein the elongated structures are arranged to tolerate the conditions occasioned by the volume charges caused by charging/discharging with lithium, wherein the elongated structures do not exceed a fractional coverage of 0.5 of the substrate.
13. An energy storage device as claimed in claim 12 wherein the elongated structures have a gravimetric capacity of at least 620 mAh/g for the first 50 cycles.
14. An energy storage device as claimed in claim 12 further comprising a lithium-containing electrolyte which comprises at least one of a lithium salt in a solvent or a polymer electrolyte.
15. An electrode as claimed in claim 9 wherein the electrode is arranged to tolerate the conditions occasioned by the volume changes caused by charging/discharging.
16. An electrode as claimed in claim 9 wherein the elongated structures do not exceed a fractional coverage of 0.5 of the substrate.
17. An electrode as claimed in claim 9 wherein the elongated structures have a diameter of up to 1.0 micron.
18. An electrode as claimed in claim 9 wherein the elongated structures have a length greater than 1 micron.
19. An electrode as claimed in claim 9 wherein the elongated structures have an aspect ratio (length to diameter ratio) in the range 1 to 100.
20. An electrode as claimed in claim 12 wherein the elongated structures have a diameter of up to 1.0 micron.
21. An electrode as claimed in claim 1 further comprising a lithium-containing electrolyte which comprises at least one of a lithium salt in a solvent or a polymer electrolyte.