Low energy milling method, low crystallinity alloy, and negative electrode composition
View Patent ↗A method of making nanostructured alloy particles includes milling a millbase in a pebble mill containing milling media. The millbase comprises: (i) silicon, and (ii) at least one of carbon or a transition metal, and wherein the nanostructured alloy particles are substantially free of crystalline domains greater than 50 nanometers in size. A method of making a negative electrode composition for a lithium ion battery including the nanostructured alloy particles is also disclosed.
1. A method of making nanostructured alloy particles, the method comprising: providing a millbase comprising: (i) silicon, and (ii) at least one of carbon or a transition metal; milling the millbase in a pebble mill containing milling media to provide the nanostructured alloy particles, wherein the nanostructured alloy particles are substantially free of crystalline domains greater than 50 nanometers in size and wherein the pebble mill has a theoretical critical speed and wherein the pebble mill has a rotational speed in a range of from 50 to 120 percent of the theoretical critical speed.
2. The method of claim 1 , wherein a volume ratio of the milling media to the millbase is greater than 5:1.
3. The method of claim 1 , wherein the nanostructured alloy particles are amorphous.
4. The method of claim 1 , wherein a volume ratio of the pebble mill to the milling media and the millbase combined is 2:1 or less.
5. The method of claim 1 , wherein the milling media have a maximum impact energy in a range of from 0.01 to 0.3 joules.
6. The method of claim 1 , wherein the pebble mill has a containment wall having a temperature, and wherein the temperature is maintained at or below 100 degrees Celsius.
7. The method of claim 1 , wherein the nanostructured alloy particles comprise silicon, tin, and a transition metal.
8. The method of claim 1 , wherein the millbase comprises ferrosilicon.
9. The method of claim 1 , wherein (ii) comprises carbon.
10. The method of claim 1 , wherein the pebble mill has a ceramic containment wall.
11. The method of claim 1 , the pebble mill further contains a milling aid comprising a saturated higher fatty acid or a salt thereof.
12. The method of claim 11 , wherein the milling aid comprises stearic acid.
13. The method of claim 1 , wherein the nanostructured alloy particles are adapted for use as an active material in a negative electrode composition in a lithium ion battery.
14. A method of making a negative electrode composition for a lithium ion battery, the method comprising:
(a) making nanostructured alloy particles by a method comprising providing a millbase comprising:
(i) silicon; and
(ii) at least one of carbon or a transition metal;
and milling said millbase in a pebble mill containing milling media, wherein the nanostructured alloy particles are substantially free of crystalline domains greater than 50 nanometers in size; wherein the pebble mill has a theoretical critical speed and wherein the pebble mill has a rotational speed in a range of from 50 to 120 percent of the theoretical critical speed; and
(b) dispersing the nanostructured alloy particles in a polymeric binder to provide the negative electrode composition.
15. The method of claim 14 , wherein the nanostructured alloy particles are amorphous.
16. The method of claim 14 , wherein the nanostructured alloy particles comprise silicon, tin, and a transition metal.
17. The method of claim 14 , wherein the nanostructured alloy particles comprise silicon, tin, and iron.
18. The method of claim 14 , wherein the nanostructured alloy particles contain carbon.
19. The method of claim 14 , wherein the pebble mill has a ceramic containment wall.
20. The method of claim 14 , the pebble mill further contains a milling aid comprising a saturated higher fatty acid or a salt thereof.
21. The method of claim 20 , wherein the milling aid comprises stearic acid.