Doped sodium manganese oxide cathode material for sodium ion batteries
A sodium transition metal cathode material for a rechargeable sodium battery having a P2 layered bronze crystal structure, comprising at least 55 mol % manganese, wherein the manganese valence state is at least 3.75. The material undergoes a structural transformation to a secondary cathode material by extraction of sodium during the 1 st charge of a rechargeable sodium battery comprising the sodium cathode material. The material has either a composition Na x MO 2 where M=Mn 1-y-z Li y A z where z<0.2 and y<0.33 and 0.66<x<0.95, and wherein A consists of either one of more elements of the group Ti, Fe, Ni, Mg and Co, or a composition NaxMO2 where M=Li a Mn 1-a-b-c Mg b A c where 0<a<0.2, c<0.2 and 0.2<a+b<0.46 and 0.66<x<0.95, and wherein A consists of either one of more elements of the group Ti, Fe, Ni and Co.
1. A sodium transition metal cathode material for a rechargeable sodium battery, having a P2 layered bronze crystal structure and having a composition Na x MO 2 , M comprising at least 55 mol % manganese, wherein the manganese valence state is at least 3.75, wherein 2/3<x<0.95, wherein M=Mn 1-y-z Li y A z , with 0≤z<0.2 and 0<y<0.33, wherein A is Mg or A is Ni and Mg.
2. The sodium cathode material of claim 1 , wherein A is Mg.
3. The sodium cathode material of claim 1 , wherein 0<z.
4. The sodium cathode material of claim 1 , wherein 0.70<x<0.95.
5. The sodium cathode material of claim 1 , having a specific surface area (BET) between 0.2 and 5 m 2 /g and a particle size distribution with 1 μm<D50<30 μm.
6. A cathode for a rechargeable sodium battery, wherein the cathode comprises the sodium cathode material according to claim 1 .
7. The sodium cathode material of claim 1 , wherein A is Mg and wherein 0<z.
8. A sodium transition metal cathode material for a rechargeable sodium battery, having a P2 layered bronze crystal structure and having a composition Na x MO 2 , M comprising at least 55 mol % manganese, wherein the manganese valence state is at least 3.75, wherein the material has a composition Na x MO 2 with 2/3<x<0.95, wherein M=Li a′ Mn 1-a′-b′-c′ Mg b′ A′ c′ with 0≤a′<0.2, b′>0, c′<0.2 and 0.2<a′+b′<0.46, and wherein A′ is selected from the group consisting of one or more elements of Ti, Cr, Fe, Ni and Co.
9. The sodium cathode material of claim 8 , wherein 0.70≤x≤0.85 and 0.23≤b′≤0.28.
10. The sodium cathode material of claim 8 , wherein c′>0.
11. The sodium cathode material of claim 8 , having a specific surface area (BET) between 0.2 and 5 m 2 /g and a particle size distribution with 1 μm<D50<30 μm.
12. A cathode for a rechargeable sodium battery, wherein the cathode comprises the sodium cathode material according to claim 8 .
13. A sodium transition metal cathode material for a rechargeable sodium battery, having a P2 layered bronze crystal structure and having a composition Na x MO 2 , wherein M comprises at least 55 mol % manganese, wherein the manganese valence state is at least 3.75, wherein M=Mg y″ Mm 1-y″ , wherein 0.67<x<0.95 and [(x−0.25)/1.75]≤y″≤[(x+0.05)/2.05].
14. The sodium cathode material according to claim 13 having a particle size distribution with 3 μm<D50<15 μm.
15. The sodium cathode material of claim 14 , having a BET specific surface area between 0.2 and 5 m 2 /g.
16. A cathode for a rechargeable sodium battery, wherein the cathode comprises the sodium cathode material according to claim 13 .
17. The sodium cathode material of claim 8 , wherein c′=0.
18. The sodium cathode material of claim 9 , wherein c′=0.