Sodium layered oxides as cathode materials for sodium ion batteries and method of manufacturing the same
AssigneesToyota Motor Europe, Centre National De La Recherche Scientifique
InventorsLaurent Castro, Jun Yoshida, Claude Delmas, Marie Guignard, Elodie Guerin
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Abstract
A composition of general formula (1): Nax[MnaNibCrc]O2+y (1), wherein: 0.6≤x≤0.8; −0.1≤y≤0.1; 0.55≤a≤0.7; 0.25≤b≤0.3; c≤0.05; and a+b+c≤1.0, an intermediate product for preparing a composition of general formula (1) and a process of synthesis, wherein the mixed sodium-transition metal oxide of general formula (1) may generally show an essentially or solely P2 structure, and may be used as a positive electrode material for a sodium ion secondary battery.
Claims12
A process for synthesizing a sodium-transition metal oxide having a P2-P3 mixture structure or a P2 structure, not including an O3 structure, comprising the steps of:
- (1) preparation of a mixed carbonate and/or hydroxide by reaction of sodium carbonate or sodium hydroxide with salts of chromium, nickel and manganese dissolved in water, followed by drying to remove water and obtain a dried mixed carbonate and/or hydroxide;
- (2) mixing of the dried mixed carbonate and/or hydroxide obtained in step (1) with further sodium carbonate and/or sodium hydroxide under an inert atmosphere, followed by calcination of the resulting mixture under an inert atmosphere, so as to obtain a sodium-transition metal oxide having essentially a P3-type structure;
- (3) mixing of the sodium-transition metal oxide having essentially a P3 structure obtained in step (2) with further sodium carbonate and/or sodium hydroxide, followed by calcination of the resulting mixture under an oxygen-containing atmosphere, so as to obtain a sodium-transition metal oxide having essentially a P2-type structure;
- (4) washing of the sodium-transition metal oxide having essentially a P2-type structure obtained in step (3) in order to remove sodium chromate.
A composition having a P2-P3 mixture structure or a P2 structure, not including an O3 structure, and having a general formula (1) below:
- Nax[MnaNibCrc]O2+y (1)
- wherein:
- 0.5≤x≤0.8;
- −0.1≤y≤0.1;
- 0.5≤a≤0.7;
- 0.2≤b≤0.3;
- 0<c≤0.3;
- and
- a+b+c≤1.0.
Dependencies are inferred from the claim text.