Lithium metal oxides with multiple phases and stable high energy electrochemical cycling
View Patent ↗Electrochemically active material comprising a lithium metal oxide composition approximately represented by the formula Li 1+b Co m Ni n Mn p O (2) , where −0.2≤b≤0.2, 0.2≤m≤0.45, 0.055≤n≤0.24, 0.385≤p≤0.72, and m+n+p is approximately 1 has been synthesized and assembled to batteries. The electrochemical performance of the batteries was evaluated. The lithium metal oxide composition in general comprises a first layered phase, a second layered phase and a spinel phase. A layered Li 2 MnO 3 phase is at least partially activated upon charging to 4.5V. In some embodiments, the material further comprises a stabilization coating covering the lithium metal oxide composition.
1. An electrochemically active material comprising a lithium metal oxide approximately represented by the formula Li 1+b Co m Ni n Mn p O (2) , where −0.2≤b≤0.2, 0.2≤m≤0.45, 0.055≤n≤0.24, 0.385≤p≤0.72, and m+n+p is approximately 1, wherein up to about 5 mole percent of the transition metals is substituted with a metal dopant, the active material exhibiting three peaks during an initial charge in a differential capacity plot and being a multiphased single material having a layered crystal phase and a spinel crystal phase.
2. The electrochemically active material of claim 1 wherein 0≤b≤0.15.
3. The electrochemically active material of claim 1 wherein 0.2≤m≤0.3, 0.07≤n≤0.24, 0.49≤p≤0.72.
4. The electrochemically active material of claim 1 wherein 0.2≤m≤0.45, 0.11≤n≤0.24, 0.385≤p≤0.64.
5. The electrochemically active material of claim 1 wherein 0.2≤m≤0.3, 0.14≤n≤0.24, 0.49≤p≤0.64.
6. The electrochemically active material of claim 1 wherein the composition is approximately free of dopants.
7. The electrochemically active material of claim 1 wherein lithium metal oxide comprises a phase that is activated upon charging to 4.5V.
8. The electrochemically active material of claim 1 further comprising a stabilization coating.
9. The electrochemically active material of claim 8 wherein the stabilization coating comprises a metal oxide.
10. The electrochemically active material of claim 8 wherein the stabilization coating comprises a metal halide.
11. The electrochemically active material of claim 1 wherein the material has a specific discharge capacity at a 75th cycle that decreases by no more than about 10% relative to the specific capacity at the 25th cycle when cycled from a 25th cycle to 75th cycle at a rate of C/3 from 4.6V to 2V against lithium.
12. The electrochemically active material of claim 1 wherein the material has an average voltage at a 75th cycle that decreases by no more than about 10% relative to the average voltage at the 25th cycle when cycled from a 25th cycle to 75th cycle at a rate of C/3 from 4.6V to 2V against lithium.
13. A lithium based battery comprising a positive electrode comprising the electrochemically active material of claim 1 , a negative electrode, a separator between the positive electrode and negative electrode and an electrolyte comprising lithium ions.
14. The lithium based battery of claim 13 wherein the negative electrode comprises an active material that intercalates or alloys with lithium.
15. The lithium based battery of claim 13 wherein the negative electrode comprises graphitic carbon.
16. The lithium based battery of claim 13 wherein the negative electrode comprises a silicon based composition.
17. The lithium based battery of claim 13 wherein the negative electrode comprises a lithium titanium oxide.
18. A method for synthesizing the electrochemically active material of claim 1 , the method comprising precipitating a precursor composition comprising the desired transition metal ratios and heating the composition in an atmosphere comprising oxygen to form the lithium metal oxide.
19. The method of claim 18 wherein the heating comprises two heating steps involving two different temperatures.
20. A method for synthesizing the electrochemically active material of claim 1 , the method comprising mixing solid precursor compositions comprising the transition metals in the mole ratio desired to form a precursor mixture and heating the mixture in an atmosphere comprising oxygen.