Method for preparing lithium metal phosphate
View Patent ↗Disclosed is a method for preparing a lithium metal phosphate represented by the following Formula 1 by using a mixture of a metal (M) with a metal oxide containing the same metal: Li x M y PO 4 [Formula 1] wherein M is a transition metal element selected from Group 3 to 12 elements in the Periodic Table, Mg, Al, Ga and B; 0.05≦x≦1.2; and 0.8≦y≦1.2. Also, an electrode comprising the lithium metal phosphate as an electrode active material, and a secondary battery comprising the electrode are also disclosed.
1. A method for preparing a lithium metal phosphate represented by the following Formula 1 by using a mixture of a metal (M) with a metal oxide containing the same metal:
Li x M y PO 4 [Formula 1]
wherein M is a transition metal element selected from Group 3 to 12 elements in the Periodic Table, Mg, Al, Ga and B; 0.05≦x≦1.2; and 0.8≦y≦1.2; and wherein the metal and the metal oxide are subjected to mechanical milling to provide a metal oxide only having an oxidation number of +2, and the metal oxide is used as the starting material for preparing the lithium metal phosphate.
2. The method according to claim 1 , which comprises the steps of:
(a) mixing a metal, a metal oxide containing the same metal, a lithium salt and a phosphate salt; and
(b) heat treating and firing the mixture obtained from step (a).
3. The method according to claim 2 , which further comprises a step of adding a carbonaceous material to the mixture obtained from step (a), followed by mixing.
4. The method according to claim 2 , wherein the lithium salt is selected from the group consisting of lithium chloride (LiCl), lithium carbonate (Li 2 CO 3 ), lithium hydroxide (LiOH), lithium phosphate (Li 3 PO 4 ) and lithium nitrate (LiNO 3 ).
5. The method according to claim 2 , wherein the phosphate salt is selected from the group consisting of (NH 4 )H 2 PO 4 , (NH 4 ) 2 HPO 4 (NH 4 ) 3 PO 4 , H 3 PO 4 , P 2 O 5 , P 4 O 10 , Li 3 PO 4 and FePO 4 .nH 2 O.
6. The method according to claim 3 , wherein the carbonaceous material is selected from the group consisting of carbon black, sucrose, pitch, cellulose acetate, organic acids, resin and resorcinol formaldehyde.
7. The method according to claim 2 , wherein the heat treating step is carried out at a temperature of 450˜850° C.
8. The method according to claim 2 , wherein the heat treating step is carried out under an inert atmosphere.
9. The method according to claim 1 , wherein the metal in the metal oxide has an oxidation number of +3 alone or an oxidation number of +3 and +2.
10. The method according to claim 1 , wherein metal M is Fe or Mn.