Preparing anodes for lithium ion cells from aluminum anode active material particles
Improved anodes and cells are provided, which enable fast charging rates with enhanced safety due to much reduced probability of metallization of lithium on the anode, preventing dendrite growth and related risks of fire or explosion. Anodes and/or electrolytes have buffering zones for partly reducing and gradually introducing lithium ions into the anode for lithiation, to prevent lithium ion accumulation at the anode electrolyte interface and consequent metallization and dendrite growth. Various anode active materials and combinations, modifications through nanoparticles and a range of coatings which implement the improved anodes are provided.
1. A method comprising:
replacing a native oxide on a surface of aluminum particles by a lithium-containing layer thereby forming anode active material particles, and
preparing an anode from the anode active material particles, and
preparing a lithium ion cell using the prepared anode.
2. The method of claim 1 , further comprising configuring the lithium-containing layer to provide a buffering zone that receives lithium ions from an interface of the anode active material particles with an electrolyte, partially reduces the received lithium ions, and enables the partially reduced lithium ions to move into an inner zone of the anode active material particles for lithiation therein.
3. The method of claim 1 , further comprising consolidating the anode active material particles to form the anode without forming an oxidation layer on the aluminum particles.
4. The method of claim 1 , wherein the lithium-containing layer comprises any of lithium polyphosphate, lithium poly(acrylic acid), lithium carboxyl methyl cellulose, poly(lithium-4-styrenesulfonate) and lithium alginate.
5. The method of claim 1 , wherein the lithium-containing layer comprises a lithium-aluminum compound having a formula Li x Al y .
6. The method of claim 5 , wherein the lithium-aluminum compound comprises Li 9 Al 4 .
7. The method of claim 1 , wherein the anode active material particles are 20-500 nm in diameter and the lithium-containing layer is 2-200 nm thick.
8. The method of claim 1 , further comprising coating the anode active material particles by a polymer which is conductive and/or lithiated.
9. The method of claim 1 , further comprising coating the anode active material particles by a 1-10 nm thick surface layer of any of: amorphous carbon, graphene, graphite, a transition metal and/or a lithium polymer.
10. The method of claim 1 , further comprising carrying out the anode preparation by forming a slurry with the active material particles, a solvent, and at least one additive selected from the group consisting of conductive particles, binder and plasticizer; and removing the solvent and consolidating the slurry to form the anode.
11. The method of claim 1 , wherein the anode active material particles further comprise at least one of Si, Ge, Sn, B, W, alloys and mixtures thereof.