Metal-containing compounds
The invention relates to a novel solid state process for the preparation of metal-containing compounds comprising the steps i) forming a reaction mixture comprising one or more metal-containing precursor compounds and optionally one or more non-metal-containing reactants, and ii) using one or more hypophosphite-containing materials as a reducing agent; wherein one or more of the hypophosphite-containing materials is used as an agent to reduce one or more of the metal-containing precursor compounds; and further wherein the process is performed in the absence of an oxidizing atmosphere. Materials made by such a process are useful, for example, as electrode materials in alkali metal-ion battery applications.
1. A solid state process for preparing a metal-containing compound comprising the formula:
A a M b (X c Y d ) e Z f
wherein:
A is an alkali metal selected from one or more of sodium and potassium;
M comprises one or more metals selected from the group consisting of titanium, vanadium, niobium, tantalum, hafnium, chromium, molybdenum, tungsten, manganese, iron, osmium, cobalt, nickel, palladium, platinum, copper, silver, gold, zinc, cadmium, aluminium, scandium, yttrium, zirconium, technetium, rhenium, ruthenium, rhodium, iridium, mercury, gallium, indium, tin, lead, bismuth, magnesium, calcium, beryllium, strontium barium, boron, silicon, germanium, arsenic, antimony and tellurium;
(X c Y d ) is at least one first anion and is a moiety selected from one or more of PO 4 and/or P 2 O 7 ; and
Z is at least one second anion
wherein a>0; b>0; c>0; d>0; e>0 and f≥0;
wherein a, b, c, d, e and f are chosen to maintain electroneutrality;
comprising the steps:
a) forming a mixture of starting materials in their solid form, comprising i) one or more M metal-containing precursor compounds, ii) one or more A metal-containing and hypophosphite-containing materials;
b) heating the mixture of starting materials from 150° C. to 1200° C. in the absence of an oxidizing atmosphere to form the metal-containing compound; and
c) recovering the metal-containing compound.
2. The solid state process according to claim 1 wherein Z is selected from one or more of the group consisting of halides, hydroxide-containing groups and mixtures thereof.
3. The solid state process according to claim 1 , the metal-containing compounds is selected from the group consisting of NaFePO 4 , NaMnPO 4 , NaCoPO 4 , NaNiPO 4 , Na 4 Fe 3 (PO 4 ) 2 P 2 O 7 , Na 3 V 2 (PO 4 ) 3 , Na 7 V 4 (P 2 O 7 ) 4 PO 4 , Na 7 V 3 (P 2 O 7 ) 4 , NaVPO 4 F, Na 3 V(PO 4 ) 2 , NaVOPO 4 , Na 8-2x Fe 4+x (P 2 O 7 ) 4 , Na 8-2x Mn 4+x (P 2 O 7 ) 4 , Na 2 MnP 2 O 7 , Na 2 FeP 2 O 7 , Na 2 CoP 2 O 7 , Na 4 Mn 3 (PO 4 ) 2 P 2 O 7 , Na 4 Co 3 (PO 4 ) 2 P 2 O 7 , Na 4 Ni 3 (PO 4 ) 2 P 2 O 7 , Na 2 FePO 4 F, Na 2 MnPO 4 F, Na 2 CoPO 4 F and Na 2 NiPO 4 F, wherein x is the range 0≤x≤4.
4. The process according to claim 1 , wherein the one or more of the metal-containing precursor compounds is reduced by the one or more A-metal containing and hypophosphite-containing materials.
5. The solid state process according to claim 1 , wherein M is one or more metals selected from the group consisting of manganese, iron, cobalt, nickel, copper, zinc, magnesium and calcium; (X c Y d ) is PO 4 ; a is 1; b is 1; c is 1; d is 4; and f is 0.
6. The solid state process according to claim 1 , wherein M is iron; (X c Y d ) is PO 4 ; a is 1; b is 1; c is 1; d is 4 and f is 0, and the one or more metal-containing precursor compounds is selected from the group consisting of Fe 2 O 3 , Fe 3 O 4 , FePO 4 .xH 2 O, FePO 4 , Fe 3 (PO 4 ) 2 , FeSO 4 .xH 2 O, Fe(NO 3 ) 3 , Fe(CH 3 CO 2 ) 2 , C 6 H 8 O 7 .xFe 3+ .yNH 3 (ammonium iron (III) citrate), C 6 H 5 FeO 7 (iron (III) citrate), and Fe(C 5 H 7 O 2 ) 3 (iron (III) 2,4-pentanedionate).
7. The solid state process according to claim 1 , wherein the one or more A-metal containing and hypophosphite-containing materials is sodium hypophosphite (NaH 2 PO 2 ).
8. The solid state process according to claim 1 , wherein the mixture further comprises one or more conductive materials.
9. The solid state process according to claim 1 , further comprising forming one or more conductive materials during the heating step (b).
10. The solid state process according to claim 9 , wherein at least one of the conductive materials formed during the heating step (b) comprises phosphorus.
11. The solid state process according to claim 10 , wherein at least one of the conductive materials formed during the heating step (b) comprises one or more of a transition metal phosphide, a non-transition metal phosphide, alkaline earth metal phosphide or a metalloid phosphide.
12. The solid state process according to claim 1 , wherein the mixture further comprises one or more non-metal-containing reactants.
13. The solid state process according to claim 1 , wherein the one or more A-metal containing and hypophosphite-containing materials is oxidized and incorporated into the metal-containing compound.