Lithium batteries with nano-composite positive electrode material
Provided is a positive electrode for a lithium ion battery, the electrode comprising a nano-crystalline layered-layered composite structure of a material having the general formula xLi 2 MO 3 (1−x)LiM′O 2 in which 0<x<1, where M′ is one or more ion with an average oxidation state of three and with at least one ion being Mn or Ni, and where M is one or more ions with an average oxidation state of four. Another aspect provides a positive electrode for a lithium ion battery, the electrode comprising a nano-crystalline layered-spinel composite structure of a material having the general formula xLi 2 MnO 3 . (1−x)LiMn 2−y M y O 4 in which 0.5<x<1.0, 0≤y<1, and where M is one or more metal cations. Also provided is the positive electrode which comprises a nano-coating of inert oxide, inert phosphate or inert fluoride on the nano-crystalline composite structure. Additional aspects provide a lithium ion battery comprising a negative electrode, an electrolyte and the positive electrode, as well as methods of preparing the positive electrode composite structure and the nano-coating of inert oxide, inert phosphate or inert fluoride.
1. A positive electrode for a lithium ion battery, the positive electrode comprises:
a nano-crystalline layered-layered composite structure having a general formula xLi 2 MO 3 .(1−x)LiM′O 2 , wherein the nano-crystalline layered-layered composite structure comprises a layered Li 2 MO 3 component and a layered LiM′O 2 component structurally integrated with each other wherein
0<x<1,
M′ comprises three or more ions with an average oxidation state of three and with at least three of the ions being Mn, Ni and Co or Ni, and
M comprises one or more ions with an average oxidation state of four; and
a nano-coating disposed on surfaces of the nano-crystalline layered-layered composite structure, wherein the nano-coating comprises an inert phosphate, inert fluoride or a combination thereof.
2. The positive electrode of claim 1 , wherein M comprises Mn.
3. The positive electrode of claim 1 , wherein the nano-crystalline layered-layered composite structure comprises a particle size of less than 1 micron.
4. The positive electrode of claim 3 , wherein the nano-crystalline layered-layered composite structure comprises a particle size ranging from about 10 nm to about 500 nm.
5. The positive electrode of claim 1 , wherein the inert phosphate comprises AlPO 4 .
6. The positive electrode of claim 1 , wherein the inert fluoride comprises AlF 3 .
7. The positive electrode of claim 1 , wherein the nano-coating comprises a thickness of 20 nm or less.
8. The positive electrode of claim 1 , is part of the lithium ion battery comprising a negative electrode and an electrolyte.
9. A method for making a positive electrode for a lithium ion battery comprising:
providing a nano-crystalline layered-layered composite structure having a general formula xLi 2 MO 3 .(1−x)LiM′O 2 , wherein the nano-crystalline layered-layered composite structure comprises a layered Li 2 MO 3 component and a layered LiM′O 2 component structurally integrated with each other, wherein
0<x<1,
M′ comprises three or more ions with an average oxidation state of three and with at least three of the ions being Mn, Ni and Co, and
M comprises one or more ions with an average oxidation state of four;
forming a nano-coating on the nano-crystalline composite structure, the nano-coating comprises inert phosphate, inert fluoride or a combination thereof.
10. The method of claim 9 , wherein providing the nano-crystalline layered-layered composite structure comprises forming the nano-crystalline layered-layered composite structure by co-precipitation.
11. The method of claim 9 wherein providing the nano-crystalline layered-layered composite structure comprises forming the nano-crystalline layered-layered composite structure by sol-gel synthesis.
12. The method of claim 9 wherein forming a nano-coating comprises:
applying an ammonium hydroxide precipitation from an aqueous solution; and
forming the nano-coating on the nano-crystalline layered-layered composite structure by calcination.
13. The method of claim 12 wherein the ammonium hydroxide precipitation from the aqueous solution comprises inert phosphate and/or inert fluoride.