Carbon coated lithium manganese phosphate cathode material
The present invention concerns a carbon coated lithium metal phosphate material containing a manganese oxide layer between the LiMnPO4 material or the C/LiMn 1-x Z x PO 4 material, where Z=Fe, Co, Ni, Mg, Ca, Al, Zr, V, Ti and x=0.01-0.3, and the carbon layer.
1. An electroactive carbon coated material having the chemical formula C/LiMnPO 4 or C/LiMn 1-x Z x PO 4 , where Z=Fe, Co, Ni, Mg, Ca, Al, Zr, V, Ti and x=0.01-0.3, characterized in that it comprises a manganese oxide interface layer between the LiMnPO 4 material or the LiMn 1-x Z x PO 4 material, and the carbon layer.
2. The electroactive carbon coated material according to claim 1 wherein the manganese oxide layer is either Mn 3 O 4 (hausmannite), β-MnO 2 (pyrolusite), MnO (manganosit), MnOOH (groutit), or Mn1.85O.6H 2 O (birnessite).
3. The electroactive carbon coated material according to claim 1 or 2 wherein the concentration of manganese oxide is 0.01-5%.
4. A rechargeable battery comprising the material of claim 1 .
5. An electrochemical device comprising: (a) an anode, a cathode, and an electrolyte in contact with and separating the anode and cathode; (b) a cathode current collector in electronic communication with the cathode; and (c) an anode current collector in electronic communication with the anode, wherein at least one of the anode and cathode is comprised of the electroactive carbon coated material of claim 1 .
6. A process for manufacturing an electroactive carbon coated material comprising milling particles off LiMnPO 4 or C/LiMn 1-x Z x PO 4 with carbon under an air atmosphere to form the electroactive carbon coated material which has the chemical formula C/LiMnPo 4 , where Z=Fe, Co, Ni, Mg, Ca, Al, Zr, V, Ti and x=0.01-0.3, that is comprised of a manganese oxide interface layer between the LiMnPO 4 material or the LiMn 1-x Z x PO 4 material, and the carbon layer.
7. The process according to claim 6 wherein said milling is carried out under wet conditions.
8. The process according to claim 7 wherein said milling is followed by a heat treatment from 130° C. to 300° C., preferably from 200° C. to 250° C.
9. The process according to claim 6 , wherein the manganese oxide layer is prepared by oxidizing LiMnPO 4 .
10. The process of claim 6 , wherein the milling is high energy milling.
11. The process of claim 7 , wherein the water content is 0.5-20%.
12. The process of claim 6 , wherein the process is carried out with addition of a LiOH.solution.