Abstract
The invention relates to electrodes comprising doped nickelate-containing compositions comprising a first component-type comprising one or more components with an O3 structure of the general formula: A.sub.aM.sup.1vM.sup.2wM.sup.3xM.sup.4yM.sup.5zO.sub.2 wherein A comprises one or more alkali metal selected from sodium, lithium and potassium M.sup.1 is nickel in oxidation state 2+, M.sup.2 comprises one or more metals in oxidation state 4+, M.sup.3 comprises one or more metals in oxidation state 2+, M.sup.4 comprises one or more metals in oxidation state 4+, and M.sup.5 comprises one or more metals in oxidation state 3+ wherein 0.85a1; 0<v<0.5; at least one of w and y is >0; x0; z0; and wherein a, v, w, x, y and z are chosen to maintain electroneutrality; together with one or more component-types selected from a second component-type comprising one or more components with a P2 structure of the general formula: A.sub.a<M.sup.1vM.sup.2wM.sup.3x<M.sup.4y<M.sup.5zO.sub.2 wherein A comprises one or more alkali metal selected from sodium, lithium and potassium; M.sup.1 is nickel in oxidation state 2+, M.sup.2 comprises one or more metals in oxidation state 4+, M.sup.3 comprises one or more metals in oxidation state 2+, M.sup.4 comprises one or more metals in oxidation state 4, and M.sup.5 comprises one or more metals in oxidation state 3+ wherein 0.4a<1; 0<v<0.5; at least one of w and y is >0; x0, preferably x>0; z>0; and wherein a, v, w, x, y and z are chosen to maintain electroneutrality; and a third component-type comprising one or more components with a P3 structure of the general formula: A.sub.aM1.sub.vM2.sub.wM.sup.3.sub.xM.sup.4.sub.yM.sup.5.sub.zO.sub.2 wherein A comprises one or more alkali metals selected from sodium, lithium and potassium; M.sup.1 is nickel in oxidation state 2+, M.sup.2 comprises one or more metals in oxidation state 4+, M.sup.3 comprises one or more metals in oxidation state 2, M.sup.4 comprises one or more metals in oxidation state 4+, and M.sup.5 comprises one or more metals in oxidation state 3+ wherein 0.4a<1, 0<v<0.5, At least one of w and y is >0; x0; z0; and wherein a, v, w, x, y and z are chosen to maintain electroneutrality.
Claims
1. An electrode comprising a mixed-phase doped nickelate-containing composition comprising a first component type comprising one or more compounds with an O3 structure together with one or more component types selected from a second component-type comprising one or more components with a P2 structure, and a third component type comprising one or more components with a P3 structure, represented by a weighted average formula:
A.sub.aM.sup.1.sub.VM.sup.2.sub.WM.sup.3.sub.XM.sup.4.sub.yM.sup.5.sub.ZO.sub.2 wherein: A comprises one or more alkali metals selected from sodium, lithium and potassium; M.sup.1 is nickel in oxidation state 2+; M.sup.2 comprises one or more metals in oxidation state 4+; M.sup.3 comprises one or more metals in oxidation state 2+; M.sup.4 comprises one or more metals in oxidation state 4+; and M.sup.5 comprises one or more metals in oxidation state 3+; wherein 0.4 a<1; 0 <v<0.5; at least one of w and y is >0; x0; z0; wherein a, v, w, x, y and z are chosen to maintain electroneutrality.
2. An electrode according to claim 1 wherein the mixed phase doped nickelate-containing composition comprises either i) a single compound comprising discrete areas containing one or more components with an O3 structure, together with discrete areas of components with one or both of P2 and P3 structures, ii) a physical mixture comprising one or more compounds with an O3 structure together with one or more compounds with a P2 and/or a P3 structure, or iii) a mixture of i) and ii).
3. An electrode according to claim 1 wherein in the mixed-phase doped nickelate-containing composition x is >0.
4. An electrode according to claim 1, wherein in the mixed-phase doped nickelate-containing composition M.sup.2 comprises one or more metals selected from manganese, titanium and zirconium; M.sup.3 comprises one or more metals selected from magnesium, calcium, copper, zinc and cobalt; M.sup.4 comprises one or more metals selected from manganese, titanium and zirconium; and M.sup.5 comprises one or more metals selected from aluminium, iron, cobalt, molybdenum, chromium, vanadium, scandium and yttrium.
5. An electrode according to claim 1 wherein the mixed-phase doped nickelate-containing composition has a weighted average formula selected from:
O3/P2-Na.sub.0.833Ni.sub.0.317Mn.sub.0.467Mg.sub.0.l00Ti.sub.0.117O.sub.2,
O3/P2-Na.sub.0.750Ni.sub.0.296Mn.sub.0.508Mg.sub.0.079Ti.sub.0.117O.sub.2,
O3/P2-Na.sub.0.85Ni.sub.0.4Mn.sub.0.5Mg.sub.0.025Ti.sub.0.07502,
O3/P2-Na.sub.0.95Ni.sub.0.3167Mn.sub.0.3167Mg.sub.0.1583Ti.sub.0.2083O.sub.2,
O3/P2-Na.sub.0.8Ni.sub.0.2667Mn.sub.0.2667Mg.sub.0.1333Ti.sub.0.3333O.sub.2,
O3/P2-Na.sub.0.75Ni.sub.0.25Mn.sub.0.25Mg.sub.0.125Ti.sub.0.375O.sub.2,
O3/P2-Na.sub.0.7Ni.sub.0.2333Mn.sub.0.2333Mg.sub.0.1167Ti.sub.0.4167O.sub.2.
6. An application device comprising the electrode according to claim 1.
7. An application device comprising an electrode according to claim 6, wherein the device is selected from an energy storage device, a battery, a rechargeable battery, an electrochemical device, an electrochromic device and a Na-ion cell.
8. A process for preparing the doped nickelate-containing composition according to claim 1 comprising forming a physical mixture of the one or more components of the first component-type, with the one or more components of one or both of the second and third component-types.
9. A process for preparing the doped nickelate-containing composition according to claim 1, comprising the steps of: i) mixing together starting materials selected from precursors for the one or more components of the first and second and/or third component-types, optionally in combination with one or more ready-made components of one or more of the first, second and third component types; ii) pressing the mixed starting materials into a pellet; and iii) heating the resulting pelletised mixture under a suitable atmosphere, and at a temperature for example of between 400 C. and 1500 C. until the doped nickelate-containing reaction product forms.
Description
BRIEF DESCRIPTION OF THE DRAWINGS
(1) The present invention will now be described with reference to the following figures in which:
(2) FIG. 1(A) is the XRD profile for the known compound P2-Na.sub.0.67Ni.sub.0.33Mn.sub.0.67O.sub.2 (comparative material) used in Example 1;
(3) FIG. 1(B) shows the cell voltage profile (i.e. Na-ion Cell Voltage [V] versus Cumulative Cathode Specific Capacity [mAh/g]) for the first 4 charge/discharge cycles of the Hard Carbon/Na.sub.0.67Ni.sub.0.33Mn.sub.0.67O.sub.2 cell;
(4) FIG. 1(C) shows the Constant current cycling (CC/CV) of full Na-ion Cell comprising hard carbon (Carbotron P(J) Kureha) and P2-Na.sub.0.67Ni.sub.0.33Mn.sub.0.67O.sub.2 in the voltage range 1.0-4.2V at 30 C. in 0.5M NaClO.sub.4, with propylene carbonate (PC) and glass filter paper (GF/A) used as a separator;
(5) FIG. 2(A) is the XRD profile for the compound P2-Na.sub.0.67Ni.sub.0.3Mn.sub.0.6Mg.sub.0.033Ti.sub.0.067O.sub.2 (comparative material) used in Example 2;
(6) FIG. 2(B) shows the cell voltage profile (i.e. Na-ion Cell Voltage [V] versus Cumulative Cathode Specific Capacity [mAh/g]) for the first 4 charge/discharge cycles of the Hard Carbon/P2-Na.sub.0.67Ni.sub.0.30Mn.sub.0.60Mg.sub.0.033Ti.sub.0.067O.sub.2 cell;
(7) FIG. 2(C) shows the Constant current cycling (CC/CV) of full Na-ion Cell comprising hard carbon (Carbotron P(J) Kureha) and P2-Na.sub.0.67Ni.sub.0.3Mn.sub.0.6Mg.sub.0.033Ti.sub.0.067O.sub.2 in the voltage range 1.0-4.2V at 30 C. in 0.5M NaClO.sub.4, propylene carbonate (PC) and GF/A;
(8) FIG. 3(A) is the XRD profile for the compound P2-Na.sub.0.67Ni.sub.0.267Mn.sub.0.533Mg.sub.0.067Ti.sub.0.133O.sub.2 (comparative material) used in Example 3;
(9) FIG. 3(B) shows the cell voltage profile (i.e. Na-ion Cell Voltage [V] versus Cumulative Cathode Specific Capacity [mAh/g]) for the first 4 charge/discharge cycles of the Hard Carbon/P2-Na.sub.0.67Ni.sub.0.267Mn.sub.0.533Mg.sub.0.067Ti.sub.0.33O.sub.2 cell;
(10) FIG. 3(C) shows the Constant current cycling (CC/CV) of full Na-ion Cell comprising hard carbon (Carbotron P(J) Kureha) and P2-Na.sub.0.67Ni.sub.0.267Mn.sub.0.533Mg.sub.0.067Ti.sub.0.133O.sub.2 in the voltage range 1.0-4.2V at 30CC in 0.5M NaClO.sub.4, propylene carbonate (PC) and GF/A;
(11) FIG. 4(A) is the XRD profile for the compound P2-Na.sub.0.67Ni.sub.0.25Mn.sub.0.667Mg.sub.0.083O.sub.2 (comparative material) used in Example 4;
(12) FIG. 4(B) shows the cell voltage profile (i.e. Na-ion Cell Voltage [V] versus Cumulative Cathode Specific Capacity [mAh/g]) for the first 4 charge/discharge cycles of the Hard Carbon/P2-Na.sub.0.67Ni.sub.0.25Mn.sub.0.667Mg.sub.0.083O.sub.2 cell
(13) FIG. 4(C) shows the Constant current cycling (CC/CV) of full Na-ion Cell comprising hard carbon (Carbotron P(J) Kureha) and P2-Na.sub.0.67Ni.sub.0.25Mn.sub.0.67Mg.sub.0.083O.sub.2 in the voltage range 1.0-4.2V at 30 C. in 0.5M NaClO.sub.4-, propylene carbonate (PC) and GF/A;
(14) FIG. 5(A) is the XRD profile for the compound P2-Na.sub.0.67Ni.sub.0.283Mn.sub.0.567Mg.sub.0.05Ti.sub.0.1O.sub.2 (comparative material) used in Example 5;
(15) FIG. 5(B) shows the cell voltage profile (i.e. Na-ion Cell Voltage [V] versus Cumulative Cathode Specific Capacity [mAh/g]) for the first 4 charge/discharge cycles of the Hard Carbon/P2-Na.sub.0.67Ni.sub.0.283Mn.sub.0.567Mg.sub.0.05Ti.sub.0.10O.sub.2 cell;
(16) FIG. 5(C) shows the Constant current cycling (CC/CV) of full Na-ion Cell comprising hard carbon (Carbotron P(J) Kureha) and P2-Na.sub.0.67Ni.sub.0.283Mn.sub.0.567Mg.sub.0.05Ti.sub.0.1O.sub.2 in the voltage range 1.0-4.2V at 30 C. in 0.5M NaClO.sub.4-, propylene carbonate (PC) and GF/A;
(17) FIG. 6(A) is the XRD profile for the material O3-Na.sub.0.95Ni.sub.0.3167Mn.sub.0.3167Mg.sub.0.1563Ti.sub.0.2083O.sub.2 (comparative material) used in Example 6;
(18) FIG. 6(B) shows the cell voltage profile (i.e. Na-ion Cell Voltage [V] versus Cumulative Cathode Specific Capacity [mAh/g]) for the first 4 charge/discharge cycles of the Hard Carbon/O3-Na.sub.0.95Ni.sub.0.3167Mn.sub.0.3167Mg.sub.0.1583Ti.sub.0.2083O.sub.2 cell;
(19) FIG. 6(C) shows the Constant current cycling (CC/CV) of full Na-ion Cell comprising hard carbon (Carbotron P(J) Kureha) and O3-Na.sub.0.95Ni.sub.0.3167Mn.sub.0.3167Mg.sub.0.1563Ti.sub.0.2083O.sub.2 in the voltage range 1.0-4.2V at 30 C. in 0.5M NaClO.sub.4, propylene carbonate (PC) and GF/A;
(20) FIG. 7(A) shows the cell voltage profile (i.e. Na-ion Cell Voltage [V] versus Cumulative Cathode Specific Capacity [mAh/g]) for the first 4 charge/discharge cycles of the Hard Carbon/(75 mass % P2-Na.sub.0.67Ni.sub.0.283Mn.sub.0.567Mg.sub.0.05Ti.sub.0.10O.sub.2 and 25 mass % O3-Na.sub.0.95Ni.sub.0.3167Mn.sub.0.3167Mg.sub.0.183Ti.sub.0.2083O.sub.2) cell;
(21) FIG. 7(B) shows the Constant current cycling (CC/CV) of full Na-ion Cell comprising hard carbon (Carbotron P(J) Kureha) and a doped nickelate-containing composition of the present invention comprising a physical mixture of P2-Na.sub.0.67Ni.sub.0.283Mn.sub.0.567Mg.sub.0.05Ti.sub.0.1O.sub.2 (75%) and O3-Na.sub.0.95Ni.sub.0.3167Mn.sub.0.3167Mg.sub.0.1563Ti.sub.0.2083O.sub.2 (25%) in the voltage range 1.0-4.2V at 30 C. in 0.5M NaClO.sub.4 propylene carbonate (PC) and GF/A, as used in Example 7;
(22) FIG. 8(A) shows the cell voltage profile (i.e. Na-ion Cell Voltage [V] versus Cumulative Cathode Specific Capacity [mAh/g]) for the first 4 charge/discharge cycles of the Hard Carbon/(50 mass % P2-Na.sub.0.67Ni.sub.0.283Mn.sub.0.567Mg.sub.0.05Ti.sub.0.10O.sub.2 and 50 mass % O3-Na.sub.0.95Ni.sub.0.3167Mn.sub.0.3167Mg.sub.0.1583Ti.sub.0.2083O.sub.2) cell;
(23) FIG. 8(B) shows the Constant current cycling (CC/CV) of full Na-ion Cell comprising hard carbon (Carbotron P(J) Kureha) and a doped nickelate-containing composition of the present invention comprising a physical mixture of P2-Na.sub.0.67Ni.sub.0.283Mn.sub.0.567Mg.sub.0.05Ti.sub.0.1O.sub.2 (50%) and O3-Na.sub.0.95Ni.sub.0.3167Mn.sub.0.3167Mg.sub.0.1563Ti.sub.0.2083O.sub.2 (50%) in the voltage range 1.0-4.2V at 30 C. in 0.5M NaClO.sub.4, propylene carbonate (PC) and GF/A, as used in Example 8;
(24) FIG. 9(A) is the XRD profile for the doped nickelate-containing composition of the present invention with the weighted average formula: O3/P2-Na.sub.0.833Ni.sub.0.317Mn.sub.0.467Mg.sub.0.1Ti.sub.0.117O.sub.2, as used in Example 9;
(25) FIG. 9(B) shows the cell voltage profile (i.e. Na-ion Cell Voltage [V] versus Cumulative Cathode Specific Capacity [mAh/g]) for the first 4 charge/discharge cycles of the Hard Carbon/mixed phase O3/P2-Na.sub.0.833Ni.sub.0.317Mn.sub.0.467Mg.sub.0.100Ti.sub.0.117O.sub.2 cell;
(26) FIG. 9(C) shows the Constant current cycling (CC/CV) of full Na-ion Cell comprising hard carbon (Carbotron P(J) Kureha) and a doped nickelate-containing composition of the present invention with the weighted average formula: O3/P2-Na.sub.0.833Ni.sub.0.317Mn.sub.0.467Mg.sub.0.1Ti.sub.0.117O.sub.2 in the voltage range 1.0-4.2V at 30 C. in 0.5M NaClO.sub.4, propylene carbonate (PC) and GF/A;
(27) FIG. 10(A) is the XRD profile for the doped nickelate-containing composition of the present invention with the weighted average formula: O3/P2-Na.sub.0.753Ni.sub.0.296Mn.sub.0.509Mg.sub.0.079Ti.sub.0.117O.sub.2, as used in Example 10;
(28) FIG. 10(B) shows the cell voltage profile (i.e. Na-ion Cell Voltage [V] versus Cumulative Cathode Specific Capacity [mAh/g]) for the first 4 charge/discharge cycles of the Hard Carbon/mixed phase O3/P2-Na.sub.0.753Ni.sub.0.296Mn.sub.0.509Mg.sub.0.079Ti.sub.0.117O.sub.2 cell
(29) FIG. 10(C) shows the Constant current cycling (CC/CV) of full Na-ion Cell comprising hard carbon (Carbotron P(J) Kureha) and a doped nickelate-containing composition of the present invention with the weighted average formula: O3/P2-Na.sub.0.75Ni.sub.0.296Mn.sub.0.508Mg.sub.0.079Ti.sub.0.117O.sub.2 in the voltage range 1.0-4.2V at 30 C. in 0.5M NaClO.sub.4, propylene carbonate (PC) and GF/A;
(30) FIG. 11(A) is the XRD profile for the doped nickelate-containing composition of the present invention with the weighted average formula: O3/P2-Na.sub.0.9Ni.sub.0.3167Mn.sub.0.3167Mg.sub.0.1583Ti.sub.0.2083O.sub.2, as used in Example 11;
(31) FIG. 11(B) shows the cell voltage profile (i.e. Na-ion Cell Voltage [V] versus Cumulative Cathode Specific Capacity [mAh/g]) for the first 4 charge/discharge cycles of the Hard Carbon/mixed phase O3/P2-Na.sub.0.95Ni.sub.0.3167Mn.sub.0.3167Mg.sub.0.1583Ti.sub.0.2083O.sub.2 cell;
(32) FIG. 11(C) shows the Constant current cycling (CC/CV) of full Na-ion Cell comprising hard carbon (Carbotron P(J) Kureha) and a doped nickelate-containing composition of the present invention with the weighted average formula: O3/P2-Na.sub.0.95Ni.sub.0.3167Mn.sub.0.3167Mg.sub.0.1583Ti.sub.0.2083O.sub.2 in the voltage range 1.0-4.2V at 30 C. in 0.5M NaClO.sub.4, propylene carbonate (PC) and GF/A;
(33) FIG. 12(A) is the XRD profile for the doped nickelate-containing composition of the present invention with the weighted average formula: O3/P2-Na.sub.0.75Ni.sub.0.296Mn.sub.0.508Mg.sub.0.079Ti.sub.0.117O.sub.2, as used in Example 12;
(34) FIG. 12(B) shows the cell voltage profile (i.e. Na-ion Cell Voltage [V] versus Cumulative Cathode Specific Capacity [mAh/g]) for 4 charge/discharge cycles of the Hard Carbon/mixed phase O3/P2-Na.sub.0.75Ni.sub.0.296Mn.sub.0.079Ti.sub.0.117O.sub.2 cell;
(35) FIG. 12(C) shows the Constant current cycling (CC/CV) of full Na-ion Cell comprising hard carbon (Carbotron P(J) Kureha) and a doped nickelate-containing composition of the present invention with the weighted average formula: O3/P2-Na.sub.0.75Ni.sub.0.296Mn.sub.0.508Mg.sub.0.079Ti.sub.0.117O.sub.2 in the voltage range 1.0-4.2V at 30 C. in 0.5M NaClO.sub.4, propylene carbonate (PC) and GF/A;
(36) FIG. 13 shows the X-ray diffraction pattern of the weighted average formula P3/P2-Na.sub.0.666Ni.sub.0.3Mn.sub.0.6Mg.sub.0.033Ti.sub.0.067O.sub.2(sample number S0842);
(37) FIG. 14 shows the X-ray diffraction pattern of the weighted average formula P3/P2-Na.sub.0.6667Ni.sub.0.2500Mn.sub.0.5833Mg.sub.0.0833Ti.sub.0.0833O.sub.2 (sample number S1430A);
(38) FIG. 15 shows the X-ray diffraction pattern of the weighted average formula O3/P2/P3-Na.sub.0.8292Ni.sub.0.2886Mn.sub.0.4622Mg.sub.0.126Ti.sub.1233O.sub.2 (sample number S1458B); and
(39) FIG. 16 shows the X-ray diffraction pattern of the weighted average formula O3/P2/P3-Na.sub.0.8188Ni.sub.0.2860Mn.sub.0.4561Mg.sub.0.1234Ti.sub.0.1346O.sub.2 (sample number S1459B).
DETAILED DESCRIPTION
(40) Any convenient process may be used to make the doped nickelate-containing compositions of the present invention and as described above they may be prepared directly using a chemical reaction between one or more ready-made components of one or more first, second and third component-types. Alternatively, precursors for the one or more components of the first, second and third component types can be caused to react together. Further alternatively a combination of one or more ready-made components for the first, second and third component-types, together with one or more precursors therefor, may be used
(41) A convenient chemical reaction may use the following general method:
(42) General Method:
(43) 1) Intimately mix together the starting materials (these can be the precursors for the one or more components of the one or more first, second and third component-types, or the ready-made components thereof, or any combination of the precursors and ready-made components) in the correct stoichiometric ratio and press into a pellet; 2) Heat the resulting mixture in a furnace under a suitable atmosphere comprising for example ambient air, nitrogen or an inert atmosphere (e.g. argon) (the gases may be flowing), at a furnace temperature for example of between 400 C. and 1500 C. until reaction product forms; and 3) Allow the product to cool, optionally grinding it to a powder.
(44) Alternatively, the doped nickelate-containing compositions may be made with no chemical reaction between the first, second and third component-types, by physically admixing the components (i.e. the ready-made components) of the first, second and third component-types described above. Each of the separate components may be pre-made using the general method described above, and used directly as made from step 2) or step 3) by admixing to produce the doped nickelate-containing compositions used in the electrodes of the present invention.
(45) Table 1 below lists the starting materials and heating conditions used to prepare the doped nickelate-containing compositions.
(46) TABLE-US-00001 TABLE 1 Example No. Doped nickelate-containing Starting Furnace (Sample No.) Composition Materials Conditions 1 P2Na.sub.0.67Ni.sub.0.33Mn.sub.0.67O.sub.2 0.333 Na.sub.2CO.sub.3 900 C., air, (X1657) (Known material) 0.333 NiCO.sub.3 8 hours 0.667 MnO.sub.2 2 P2Na.sub.0.67Ni.sub.0.3Mn.sub.0.6Mg.sub.0.033Ti.sub.0.067O.sub.2 0.333 Na.sub.2CO.sub.3 900 C., air, (X1659) (comparative example) 0.300 NiCO.sub.3 8 hours General formula: 0.600 MnO.sub.2 Na.sub.(2/3)Ni.sub.(1/3)xMn.sub.(2/3)yMg.sub.xTi.sub.yO.sub.2, 0.033 Mg(OH).sub.2 where x = 1/30 and y = 1/15 0.067 TiO.sub.2 3 P2Na.sub.0.67Ni.sub.0.267Mn.sub.0.533Mg.sub.0.067Ti.sub.0.133O.sub.2 0.333 Na.sub.2CO.sub.3 900 C., air, (X1663) (Comparative example) 0.267 NiCO.sub.3 8 hours General formula: 0.533 MnO.sub.2 Na.sub.(2/3)Ni.sub.(1/3)xMn.sub.(2/3)yMg.sub.xTi.sub.yO.sub.2, 0.067 Mg(OH).sub.2 where x = 1/15 and y = 2/15 0.133 TiO.sub.2 4 P2Na.sub.0.67Ni.sub.0.25Mg.sub.0.083Mn.sub.0.667O.sub.2 0.333 Na.sub.2CO.sub.3 900 C., air, (X1684) (Comparative example) 0.250 NiCO.sub.3 10 hours General formula: 0.083 Mg(OH).sub.2 Na.sub.(2/3)Ni.sub.(1/3)xMg.sub.xMn.sub.(2/3)O.sub.2, 0.667 MnO.sub.2 where x = 1/12 5 P2Na.sub.0.67Ni.sub.0.283Mn.sub.0.567Mg.sub.0.05Ti.sub.0.1O.sub.2 0.333 Na.sub.2CO.sub.3 900 C., air, (X1713) (Comparative example) 0.283 NiCO.sub.3 10 hours General formula: 0.567 MnO.sub.2 Na.sub.(2/3)Ni.sub.(1/3)xMn.sub.(2/3)yMg.sub.xTi.sub.yO.sub.2, 0.050 Mg(OH).sub.2 where x = 1/20 and y = 1/10 0.100 TiO.sub.2 6 O3Na.sub.0.95Ni.sub.0.3167Mn.sub.0.3167Mg.sub.0.1583Ti.sub.0.2083O.sub.2 0.475 Na.sub.2CO.sub.3 900 C., air, (X1714) (Comparative example) 0.3167 NiCO.sub.3 10 hours General formula: 0.3167 MnO.sub.2 Na.sub.1xNi.sub.(1x)/3Mn.sub.(1x)/3Mg.sub.(1/6)(1/6)xTi.sub.(1/6)+(5/6)xO.sub.2, 0.1583 Mg(OH).sub.2 where x = 0.05 0.2083 TiO.sub.2 7 Physical mixture: 75 wt. % X1713 Hand-mixed (X1713/ P2Na.sub.0.67Ni.sub.0.283Mn.sub.0.567Mg.sub.0.05Ti.sub.0.1O.sub.2 and 25 wt. % X1714 using pestle X1714) O3Na.sub.0.95Ni.sub.0.3167Mn.sub.0.3167Mg.sub.0.1583Ti.sub.0.2083O.sub.2 & mortar P2:O3 75:25 8 Physical mixture: 50 wt. % X1713 Hand-mixed (X1713/ P2Na.sub.0.67Ni.sub.0.283Mn.sub.0.567Mg.sub.0.05Ti.sub.0.1O.sub.2 and 50 wt. % X1714 using pestle X1714) O3Na.sub.0.95Ni.sub.0.3167Mn.sub.0.3167Mg.sub.0.1583Ti.sub.0.2083O.sub.2 & mortar P2:O3 50:50 9 Weighted average formula: 0.4167 Na.sub.2CO.sub.3 900 C., air, (X1682) P2/O3Na.sub.0.833Ni.sub.0.317Mn.sub.0.467Mg.sub.0.100Ti.sub.0.117O.sub.2 0.3167 NiCO.sub.3 10 hours General formula: 1 x 0.467 MnO.sub.2 NaNi.sub.0.33Mn.sub.0.33Mg.sub.0.167Ti.sub.0.167O.sub.2: x 0.1 Mg(OH).sub.2 Na.sub.0.67Ni.sub.0.33Mn.sub.0.67Mg.sub.0.033Ti.sub.0.067O.sub.2, where x = 0.5 0.1167 TiO.sub.2 10 Weighted average formula: 0.3675 Na.sub.2CO.sub.3 900 C., air, (X1692) P2/O3Na.sub.0.750Ni.sub.0.296Mn.sub.0.508Mg.sub.0.079Ti.sub.0.117O.sub.2 0.295 NiCO.sub.3 10 hours General formula: 1 x 0.509 MnO.sub.2 NaNi.sub.0.33Mn.sub.0.33Mg.sub.0.167Ti.sub.0.167O.sub.2: x 0.079 Mg(OH).sub.2 Na.sub.0.67Ni.sub.0.283Mn.sub.0.567Mg.sub.0.05Ti.sub.0.1O.sub.2, where x = 0.75 0.117 TiO.sub.2 11 Weighted Average formula: 0.475 Na.sub.2CO.sub.3 900 C., air, (X1696C) P2/O3Na.sub.0.95Ni.sub.0.3167Mn.sub.0.3167Mg.sub.0.1583Ti.sub.0.2083O.sub.2 0.3167 NiCO.sub.3 4 minutes General formula: 0.3167 MnO.sub.2 Na.sub.1Ni.sub.(1)/3Mn.sub.(1)/3Mg.sub.(1/6)(1/6)Ti.sub.(1/6)+(5/6)O.sub.2, 0.1583 Mg(OH).sub.2 where = 0.05 0.2083 TiO.sub.2 Very small amount of P2 phase present due to short dwell time 12 Weighted average formula: 0.3750 Na.sub.2CO.sub.3 900 C., air, (X1700) P2/O3Na.sub.0.75Ni.sub.0.296Mn.sub.0.508Mg.sub.0.079Ti.sub.0.117O.sub.2 0.2958 NiCO.sub.3 10 hours General formula: 0.5083 MnO.sub.2 1 x NaNi.sub.0.33Mn.sub.0.33Mg.sub.0.167Ti.sub.0.167O.sub.2: 0.0792 Mg(OH).sub.2 xNa.sub.0.67Ni.sub.0.283Mn.sub.0.567Mg.sub.0.05Ti.sub.0.1O.sub.2, 0.1167 TiO.sub.2 where x = 0.75 13 Weighted average formula: 0.333 Na.sub.2CO.sub.3 800 C., air, (S0842) P3/P2Na.sub.0.666Ni.sub.0.3Mn.sub.0.6Mg.sub.0.033Ti.sub.0.067O.sub.2 0.06 6 hours General formula: (2NiCO.sub.33Ni(OH).sub.24H.sub.2O) Na.sub.(2/3)Ni.sub.((1/3))Mn.sub.((2/3))Mg.sub.Ti.sub.O.sub.2 0.6 MnO.sub.2 0.033 Mg(OH).sub.2 0.067 TiO.sub.2 14 Weighted average formula: 0.3334 Na.sub.2CO.sub.3 800 C., air, (S1430A) P3/P2Na.sub.0.6667Ni.sub.0.2500Mn.sub.0.5833Mg.sub.0.0833Ti.sub.0.0833O.sub.2 0.0500 6 hours General formula: 2NiCO.sub.33Ni(OH).sub.24H.sub.2O Na.sub.(1)Ni.sub.(1/4+1/3)Mn.sub.(2/31/12)o+7/9 0.5833 MnO.sub.2 Mg.sub.(1/4+1/6)Ti.sub.(13/125/18)O.sub.2 0.0833 Mg(OH).sub.2 Where = 0.3333 0.0833 TiO.sub.2 15 Weighted average formula: 0.4146 Na.sub.2CO.sub.3 750 C., air, (S1458B) P3/P2/O3Na.sub.0.8292Ni.sub.0.2886Mn.sub.0.4622Mg.sub.0.126Ti.sub.0.1233O.sub.2 0.0577 6 hours General formula: 2NiCO.sub.33Ni(OH).sub.24H.sub.2O 1 x Na.sub.0.95Ni.sub.0.3167Mn.sub.0.316, Mg.sub.0.1583Ti.sub.0.2083O.sub.2: x 0.4622 MnO.sub.2 Na.sub.0.7083Na.sub.0.2604Mn.sub.0.6076Mg.sub.0.0937Ti.sub.0.0382O.sub.2, 0.1260 Mg(OH).sub.2 where x = 0.5 0.1233 TiO.sub.2 16 Weighted average formula: 0.4094 Na.sub.2CO.sub.3 750 C., air, (S1459B) P3/P2/O3Na.sub.0.8188Ni.sub.0.2860Mn.sub.0.4561Mg.sub.0.1234Ti.sub.0.1346O.sub.2 0.0572 6 hours General formula: 2NiCO.sub.33Ni(OH).sub.24H.sub.2O 1 x Na.sub.0.95Ni.sub.0.3167Mn.sub.0.3167Mg.sub.0.1583Ti.sub.0.2083O.sub.2: x 0.4561 MnO.sub.2 Na.sub.0.6875Ni.sub.0.2552Mn.sub.0.5955Mg.sub.0.0885Ti.sub.0.0608O.sub.2, 0.1234 Mg(OH).sub.2 where x = 0.5 0.1346 TiO.sub.2
(47) Product Analysis Using XRD
(48) Analysis by X-ray diffraction techniques was conducted using a Siemens D5000 powder diffractometer to confirm that the desired target doped nickelate-containing compositions had been prepared, to establish the phase purity of the product material and to determine the types of impurities present. From this information it is possible to determine the lattice parameters of the unit cells.
(49) The general XRD operating conditions used to analyse the materials are as follows:
(50) Slits sizes: 1 mm, 1 mm, 0.1 mm
(51) Range: 2=5-60
(52) X-ray Wavelength=1.5418 (Angstroms) (Cu K)
(53) Speed: 1.0 seconds/step
(54) Increment: 0.025
(55) Electrochemical Results
(56) The target doped nickelate-containing compositions were tested using a Na-ion test cell using a hard carbon anode. Cells may be made using the following procedures:
(57) A Na-ion electrochemical test cell containing the active material is constructed as follows:
(58) Generic Procedure to Make a Hard Carbon Na-ion Cell
(59) The positive electrode is prepared by solvent-casting a slurry of the active material, conductive carbon, binder and solvent. The conductive carbon used is Super P (Timcal). PVdF is used as the binder, and N-methyl-2-pyrrolidone (NMP) is employed as the solvent. The slurry is then cast onto aluminium foil and heated until most of the solvent evaporates and an electrode film is formed. The electrode is then dried under dynamic vacuum at about 120 C. The electrode film contains the following components, expressed in percent by weight: 80% active material (doped nickelate-containing composition), 6% Super P carbon, and 6% PVdF binder.
(60) The negative electrode is prepared by solvent-casting a slurry of the hard carbon active material (Carbotron P/J, supplied by Kureha), conductive carbon, binder and solvent. The conductive carbon used is Super P (Timcal). PVdF is used as the binder, and N-Methyl-2-pyrrolidone (NMP) is employed as the solvent. The slurry is then cast onto aluminium foil and heated until most of the solvent evaporates and an electrode film is formed. The electrode is then dried further under dynamic vacuum at about 120 C. The electrode film contains the following components, expressed in percent by weight: 89% active material, 2% Super P carbon, and 9% PVdF binder.
(61) Cell Testing
(62) The cells are tested as follows, using Constant Current Cycling techniques.
(63) The cell is cycled at a given current density between pre-set voltage limits. A commercial battery cycler from Maccor Inc. (Tulsa, Okla., USA) is used. On charge, alkali ions are extracted from the cathode active material. During discharge, alkali ions are re-inserted into the cathode active material.
(64) Discussion of the Results
EXAMPLE 1: P2-Na0.67Ni0.33Mn0.67O2
(65) FIG. 1(A) shows the X-ray diffraction pattern of the known material Na.sub.0.67Ni.sub.0.33Mn.sub.0.67O.sub.2 (sample number X1657). The pattern shows that this material conforms to a layered P2-type structure.
(66) Referring to FIGS. 1(B)-(C):
(67) The data shown in FIGS. 1(B)-(C) are derived from the constant current cycling data for a Na.sub.0.67Ni.sub.0.33Mn.sub.0.67O.sub.2 cathode active material in a Na-ion cell (Cell#311044) where this cathode material was coupled with a Hard Carbon (Carbotron P(J)) anode material. The electrolyte used was a 0.5 M solution of NaClO.sub.4 in propylene carbonate. The constant current data were collected at an approximate current density of 0.125 mA/cm.sup.2 between voltage limits of 1.00 and 4.20 V. To ensure that the Na-ion cell was fully charged, the cell was potentiostatically held at 4.2 V at the end of the constant current charging process until the current density dropped to 10% of the constant current value. The testing was carried out at 30 C.
(68) During the cell charging process, sodium ions are extracted from the cathode active material, and inserted into the Hard Carbon anode. During the subsequent discharge process, sodium ions are extracted from the Hard Carbon and re-inserted into the cathode active material.
(69) FIG. 1(B) shows the cell voltage profile (i.e. Na-ion Cell Voltage [V] versus Cumulative Cathode Specific Capacity [mAh/g]) for the first 4 charge/discharge cycles of the Hard Carbon/Na.sub.0.67Ni.sub.0.33Mn.sub.0.67O.sub.2 cell. These data demonstrate that the level of voltage hysteresis (i.e. the voltage difference between the charge and discharge processes) is large indicating the relatively poor kinetic reversibility of the Na-ion extraction-insertion reactions in this cathode material.
(70) FIG. 1(C) shows the constant current cycle life profile (i.e. the relationship between Cathode Specific Capacity for Discharge [mAh/g] and cycle number for the Hard Carbon/Na.sub.0.67Ni.sub.0.33Mn.sub.0.67O.sub.2 cell. For cycle 1 the discharge specific capacity for the cathode is about 127 mAh/g. For cycle 20 the discharge specific capacity for the cathode is about 61 mAh/g. This represents a capacity fade of about 52% over 20 cycles or an average of 2.6% per cycle. The cathode material under test clearly demonstrates relatively poor capacity retention behaviour.
EXAMPLE 2: P2-Na0.67Ni0.3Mn0.6Mg0.033Ti0.067O2
(71) FIG. 2(A) shows the X-ray diffraction pattern of Na.sub.0.67Ni.sub.0.3Mn.sub.0.6Mg.sub.0.033Ti.sub.0.067O.sub.2(sample number X1659). The pattern shows that the sample conforms to a layered P2-type structure.
(72) Referring to FIGS. 2(B)-(C):
(73) The data shown in FIGS. 2(B)-(C) are derived from the constant current cycling data for a P2-Na.sub.0.67Ni.sub.0.30Mn.sub.0.60Mg.sub.0.033Ti.sub.0.067O.sub.2 cathode active material in a Na-ion cell (Cell#311051) where this cathode material was coupled with a Hard Carbon (Carbotron P(J)) anode material. The electrolyte used was a 0.5 M solution of NaClO.sub.4 in propylene carbonate (PC). The constant current data were collected at an approximate current density of 0.2 mA/cm.sup.2 between voltage limits of 1.00 and 4.20 V. To ensure that the Na-ion cell was fully charged, the cell was potentiostatically held at 4.2 V at the end of the constant current charging process until the current density dropped to 10% of the constant current value. The testing was carried out at 30 C.
(74) During the cell charging process, sodium ions are extracted from the cathode active material, and inserted into the Hard Carbon anode. During the subsequent discharge process, sodium ions are extracted from the Hard Carbon and re-inserted into the cathode active material.
(75) FIG. 2(B) shows the cell voltage profile (i.e. Na-ion Cell Voltage [V] versus Cumulative Cathode Specific Capacity [mAh/g]) for the first 4 charge/discharge cycles of the Hard Carbon/P2-Na.sub.0.67Ni.sub.0.30Mn.sub.0.60Mg.sub.0.033Ti.sub.0.067O.sub.2 cell. These data demonstrate that the level of voltage hysteresis (i.e. the voltage difference between the charge and discharge processes) is small, indicating the excellent kinetic reversibility of the Na-ion extraction-insertion reactions. In addition, the generally symmetrical nature of the charge/discharge voltage profile confirms the excellent reversibility of the extraction-insertion reactions.
(76) FIG. 2(C) shows the constant current cycle life profile (i.e. the relationship between Cathode Specific Capacity for Discharge [mAh/g] and cycle number for the Hard Carbon/P2-Na.sub.0.67Ni.sub.0.30Mn.sub.0.60Mg.sub.0.033Ti.sub.0.067O.sub.2 cell. For cycle 1 the discharge specific capacity for the cathode is about 117 mAh/g. For cycle 30 the discharge specific capacity for the cathode is about 106 mAh/g. This represent a capacity fade of about 9.4% over 30 cycles or an average of 0.3% per cycle. The cathode material under test clearly demonstrates excellent capacity retention behaviour.
EXAMPLE 3: P2-Na0.67Ni0.67Mn0.533Mg0.067Ti0.133O2
(77) FIG. 3(A) shows the X-ray diffraction pattern of Na.sub.0.67Ni.sub.0.267Mn.sub.0.533Mg.sub.0.067Ti.sub.0.33O.sub.2 (sample number X1663). The pattern shows that the sample conforms to a layered P2-type structure.
(78) Referring to FIGS. 3(B)-(C):
(79) The data shown in FIGS. 3(B)-(C) are derived from the constant current cycling data for a P2-Na.sub.0.67N.sub.0.267Ti.sub.0.133Mg.sub.0.067Mn.sub.0.533O.sub.2 cathode active material in a Na-ion cell (Cell#311058) where this cathode material was coupled with a Hard Carbon (Carbotron P(J)) anode material. The electrolyte used was a 0.5 M solution of NaClO.sub.4 in propylene carbonate (PC). The constant current data were collected at an approximate current density of 0.2 mA/cm.sup.2 between voltage limits of 1.00 and 4.20 V. To ensure that the Na-ion cell was fully charged, the cell was potentiostatically held at 4.2 V at the end of the constant current charging process until the current density dropped to 10% of the constant current value. The testing was carried out at 30 C.
(80) During the cell charging process, sodium ions are extracted from the cathode active material, and inserted into the Hard Carbon anode. During the subsequent discharge process, sodium ions are extracted from the Hard Carbon and re-inserted into the cathode active material.
(81) FIG. 3(B) shows the cell voltage profile (i.e. Na-ion Cell Voltage [V] versus Cumulative Cathode Specific Capacity [mAh/g]) for the first 4 charge/discharge cycles of the Hard Carbon/P2-Na.sub.0.67Ni.sub.0.267Ti.sub.0.133Mg.sub.0.067Mn.sub.0.533O.sub.2 cell. These data demonstrate that the level of voltage hysteresis (i.e. the voltage difference between the charge and discharge processes) is small, indicating the excellent kinetic reversibility of the Na-ion extraction-insertion reactions. In addition, the generally symmetrical nature of the charge/discharge voltage profile confirms the excellent reversibility of the extraction-insertion reactions.
(82) FIG. 3(C) shows the constant current cycle life profile (i.e. the relationship between Cathode Specific Capacity for Discharge [mAh/g] and cycle number for the Hard Carbon/P2-Na.sub.0.67Ni.sub.0.267Ti.sub.0.133Mg.sub.0.067Mn.sub.0.533O.sub.2 cell. For cycle 1 the discharge specific capacity for the cathode is about 105 mAh/g. For cycle 30 the discharge specific capacity for the cathode is about 101 mAh/g. This represents a capacity fade of about 3.8% over 30 cycles or an average of 0.13% per cycle. The cathode material under test clearly demonstrates excellent capacity retention behaviour.
EXAMPLE 4: P2-Na0.67Ni0.25Mg0.083Mn0.667O2
(83) FIG. 4(A) shows the X-ray diffraction pattern of Na.sub.0.67Ni.sub.0.25Mg.sub.0.083Mn.sub.0.667O.sub.2 (sample number X1684). The pattern shows that the sample conforms to a layered P2-type structure.
(84) Referring to FIGS. 4(B)-(C):
(85) The data shown in FIGS. 4(B)-(C) are derived from the constant current cycling data for a P2-Na.sub.0.67Ni.sub.0.25Mg.sub.0.083Mn.sub.0.667O.sub.2 cathode active material in a Na-ion cell (Cell#312020) where this cathode material was coupled with a Hard Carbon (Carbotron P(J)) anode material. The electrolyte used was a 0.5 M solution of NaClO.sub.4 in propylene carbonate. The constant current data were collected at an approximate current density of 0.125 mA/cm.sup.2 between voltage limits of 1.00 and 4.20 V. To ensure that the Na-ion cell was fully charged, the cell was potentiostatically held at 4.2 V at the end of the constant current charging process until the current density dropped to 10% of the constant current value. The testing was carried out at 30 C.
(86) During the cell charging process, sodium ions are extracted from the cathode active material, and inserted into the Hard Carbon anode. During the subsequent discharge process, sodium ions are extracted from the Hard Carbon and re-inserted into the cathode active material.
(87) FIG. 4(B) shows the cell voltage profile (i.e. Na-ion Cell Voltage [V] versus Cumulative Cathode Specific Capacity [mAh/g]) for the first 4 charge/discharge cycles of the Hard Carbon/P2-Na.sub.0.67Ni.sub.0.25Mg.sub.0.083Mn.sub.0.667O.sub.2 cell. These data demonstrate that the level of voltage hysteresis (i.e. the voltage difference between the charge and discharge processes) is small, indicating the excellent kinetic reversibility of the Na-ion extraction-insertion reactions. In addition, the generally symmetrical nature of the charge/discharge voltage profile confirms the excellent reversibility of the extraction-insertion reactions.
(88) FIG. 4(C) shows the constant current cycle life profile (i.e. the relationship between Cathode Specific Capacity for Discharge [mAh/g] and cycle number for the Hard Carbon/P2-Na.sub.0.67Ni.sub.0.25Mg.sub.0.083Mn.sub.0.667O.sub.2 cell. For cycle 1 the discharge specific capacity for the cathode is about 96 mAh/g. For cycle 30 the discharge specific capacity for the cathode is about 95 mAh/g. This represents a capacity fade of about 1.0% over 30 cycles or an average of 0.03% per cycle. The cathode material under test clearly demonstrates excellent capacity retention behaviour.
EXAMPLE 5: P2-Na0.67Ni0.283Mn0.567Mg0.05Ti0.1O2
(89) FIG. 5(A) shows the X-ray diffraction pattern of Na.sub.0.67Ni.sub.0.283Mn.sub.0.567Mg.sub.0.05Ti.sub.0.1O.sub.2(sample number X1713). The pattern shows that the sample conforms to a layered P2-type structure.
(90) Referring to FIGS. 5(B)-(C):
(91) The data shown in FIGS. 5(B)-(C) are derived from the constant current cycling data for a P2-Na.sub.0.67Ni.sub.0.283Mn.sub.0.567Mg.sub.0.05Ti.sub.0.10O.sub.2 cathode active material in a Na-ion cell (Cell#401018) where this cathode material was coupled with a Hard Carbon (Carbotron P(J)) anode material. The electrolyte used was a 0.5 M solution of NaClO.sub.4 in propylene carbonate. The constant current data were collected at an approximate current density of 0.125 mA/cm.sup.2 between voltage limits of 1.00 and 4.20 V. To ensure that the Na-ion cell was fully charged, the cell was potentiostatically held at 4.2 V at the end of the constant current charging process until the current density dropped to 10% of the constant current value. The testing was carried out at 30 C.
(92) During the cell charging process, sodium ions are extracted from the cathode active material, and inserted into the Hard Carbon anode. During the subsequent discharge process, sodium ions are extracted from the Hard Carbon and re-inserted into the cathode active material.
(93) FIG. 5(B) shows the cell voltage profile (i.e. Na-ion Cell Voltage [V] versus Cumulative Cathode Specific Capacity [mAh/g]) for the first 4 charge/discharge cycles of the Hard Carbon/P2-Na.sub.0.67Ni.sub.0.283Mn.sub.0.567Mg.sub.0.05Ti.sub.0.10O.sub.2 cell. These data demonstrate that the level of voltage hysteresis (i.e. the voltage difference between the charge and discharge processes) is small, indicating the excellent kinetic reversibility of the Na-ion extraction-insertion reactions. In addition, the generally symmetrical nature of the charge/discharge voltage profile confirms the excellent reversibility of the extraction-insertion reactions.
(94) FIG. 5(C) shows the constant current cycle life profile (i.e. the relationship between Cathode Specific Capacity for Discharge [mAh/g] and cycle number for the Hard Carbon/P2-Na.sub.0.67Ni.sub.0.283Mn.sub.0.567Mg.sub.0.05Ti.sub.0.10O.sub.2 cell. For cycle 1 the discharge specific capacity for the cathode is about 97 mAh/g. For cycle 30 the discharge specific capacity for the cathode is about 92 mAh/g. This represents a capacity fade of about 5.2% over 30 cycles or an average of 0.17% per cycle. The cathode material under test clearly demonstrates excellent capacity retention behaviour.
EXAMPLE 6: O3-Na0.95Ni0.3167Mn0.3167Mg0.1583Ti0.2083O2
(95) FIG. 6(A) shows the X-ray diffraction pattern of the known material Na.sub.0.55Ni.sub.0.3167Mn.sub.0.3167Mg.sub.0.1583Ti.sub.0.2083O.sub.2(sample number X1714). The pattern shows that the sample conforms to a layered O3-type structure.
(96) Referring to FIGS. 6(B)-(C):
(97) The data shown in FIGS. 6(B)-(C) are derived from the constant current cycling data for a O3-Na.sub.0.95Ni.sub.0.3167Mn.sub.0.3167Mg.sub.0.1583Ti.sub.0.2083O.sub.2 cathode active material in a Na-ion cell (Cell#401020) where this cathode material was coupled with a Hard Carbon (Carbotron P(J)) anode material. The electrolyte used was a 0.5 M solution of NaClO.sub.4 in propylene carbonate. The constant current data were collected at an approximate current density of 0.125 mA/cm.sup.2 between voltage limits of 1.00 and 4.20 V. To ensure that the Na-ion cell was fully charged, the cell was potentiostatically held at 4.2 V at the end of the constant current charging process until the current density dropped to 10% of the constant current value. The testing was carried out at 30 C.
(98) During the cell charging process, sodium ions are extracted from the cathode active material, and inserted into the Hard Carbon anode. During the subsequent discharge process, sodium ions are extracted from the Hard Carbon and re-inserted into the cathode active material.
(99) FIG. 6(B) shows the cell voltage profile (i.e. Na-ion Cell Voltage [V] versus Cumulative Cathode Specific Capacity [mAh/g]) for the first 4 charge/discharge cycles of the Hard Carbon/O3-Na.sub.0.95Ni.sub.0.3167Mn.sub.0.3167Mg.sub.0.1583Ti.sub.0.2083O.sub.2 cell. These data demonstrate that the level of voltage hysteresis (i.e. the voltage difference between the charge and discharge processes) is small, indicating the excellent kinetic reversibility of the Na-ion extraction-insertion reactions. In addition, the generally symmetrical nature of the charge/discharge voltage profile confirms the excellent reversibility of the extraction-insertion reactions.
(100) FIG. 6(C) shows the constant current cycle life profile (i.e. the relationship between Cathode Specific Capacity for Discharge [mAh/g] and cycle number for the Hard Carbon/O3-Na.sub.0.95Ni.sub.0.3167Mn.sub.0.3167Mg.sub.0.1583Ti.sub.0.2083O.sub.2 cell. For cycle 1 the discharge specific capacity for the cathode is about 145 mAh/g. For cycle 15 the discharge specific capacity for the cathode is about 134 mAh/g. This represents a capacity fade of about 7.6% over 15 cycles or an average of 0.51% per cycle. The cathode material under test demonstrates reasonable capacity retention behaviour.
EXAMPLE 7: 75 Mass % P2-Na0.67Ni0.283Mn0.567Mg0.05Ti0.10O2 and 25 Mass % O3-Na0.95Ni0.3167Mn0.3167Mg0.1583Ti0.2083O2
(101) Referring to FIGS. 7(A)-(B).
(102) The data shown in FIGS. 7(A)-(B) are derived from the constant current cycling data for a physically mixed active cathode comprising (75 mass % P2-Na.sub.0.67Ni.sub.0.283Mn.sub.0.567Mg.sub.0.05Ti.sub.0.10O.sub.2 and 25 mass % O3-Na.sub.0.95Ni.sub.0.3167Mn.sub.0.3167Mg.sub.0.1583Ti.sub.0.2083O.sub.2) in a Na-ion cell (Cell#401021) where this cathode material was coupled with a Hard Carbon (Carbotron P(J)) anode material. The electrolyte used was a 0.5 M solution of NaClO.sub.4 in propylene carbonate. The constant current data were collected at an approximate current density of 0.125 mA/cm.sup.2 between voltage limits of 1.00 and 4.20 V. To ensure that the Na-ion cell was fully charged, the cell was potentiostatically held at 4.2 V at the end of the constant current charging process until the current density dropped to 10% of the constant current value. The testing was carried out at 30 C.
(103) During the cell charging process, sodium ions are extracted from the cathode active material, and inserted into the Hard Carbon anode. During the subsequent discharge process, sodium ions are extracted from the Hard Carbon and re-inserted into the cathode active material.
(104) FIG. 7(A) shows the cell voltage profile (i.e. Na-ion Cell Voltage [V] versus Cumulative Cathode Specific Capacity [mAh/g]) for the first 4 charge/discharge cycles of the Hard Carbon/(75 mass % P2-Na.sub.0.67Ni.sub.0.283Mn.sub.0.567Mg.sub.0.05Ti.sub.0.10O.sub.2 and 25 mass % O3-Na.sub.0.95Ni.sub.0.3167Mn.sub.0.3167Mg.sub.0.1583Ti.sub.0.2083O.sub.2) cell. These data demonstrate that the level of voltage hysteresis (i.e. the voltage difference between the charge and discharge processes) is small, indicating the excellent kinetic reversibility of the Na-ion extraction-insertion reactions. In addition, the generally symmetrical nature of the charge/discharge voltage profile confirms the excellent reversibility of the extraction-insertion reactions.
(105) FIG. 7(B) shows the constant current cycle life profile (i.e. the relationship between Cathode Specific Capacity for Discharge [mAh/g] and cycle number for the Hard Carbon/(75 mass % P2-Na.sub.0.67Ni.sub.0.283Mn.sub.0.567Mg.sub.0.05Ti.sub.0.10O.sub.2 and 25 mass % O3-Na.sub.0.95Ni.sub.0.3167Mn.sub.0.3167Mg.sub.0.1583Ti.sub.0.2083O.sub.2). For cycle 1 the discharge specific capacity for the cathode is about 113 mAh/g. For cycle 15 the discharge specific capacity for the cathode is about 110 mAh/g. This represents a capacity fade of about 2.7% over 30 cycles or an average of 0.09% per cycle. The cathode material under test clearly demonstrates excellent capacity retention behaviour.
EXAMPLE 8: 50 Mass % P2-Na0.67Ni0.283Mn0.567Mg0.05Ti0.10O2 and 50 Mass % O3-Na0.95Ni0.3167Mn0.3167Mg0.1583Ti0.2083O2
(106) Referring to FIGS. 8(A)-(B):
(107) The data shown in FIGS. 8(A)-(B) are derived from the constant current cycling data for a physically mixed active cathode comprising (50 mass % P2-Na.sub.0.67Ni.sub.0.283Mn.sub.0.567Mg.sub.0.05Ti.sub.0.10O.sub.2 and 50 mass % O3-Na.sub.0.95Ni.sub.0.3167Mn.sub.0.3167Mg.sub.0.583Ti.sub.0.2083O.sub.2) in a Na-ion cell (Cell#401023) where this cathode material was coupled with a Hard Carbon (Carbotron P(J)) anode material. The electrolyte used was a 0.5 M solution of NaClO.sub.4 in propylene carbonate. The constant current data were collected at an approximate current density of 0.125 mA/cm.sup.2 between voltage limits of 1.00 and 4.20 V. To ensure that the Na-ion cell was fully charged, the cell was potentiostatically held at 4.2 V at the end of the constant current charging process until the current density dropped to 10% of the constant current value. The testing was carried out at 30 C.
(108) During the cell charging process, sodium ions are extracted from the cathode active material, and inserted into the Hard Carbon anode. During the subsequent discharge process, sodium ions are extracted from the Hard Carbon and re-inserted into the cathode active material.
(109) FIG. 8(A) shows the cell voltage profile (i.e. Na-ion Cell Voltage [V] versus Cumulative Cathode Specific Capacity [mAh/g]) for the first 4 charge/discharge cycles of the Hard Carbon/(50 mass % P2-Na.sub.0.67Ni.sub.0.283Mn.sub.0.567Mg.sub.0.05Ti.sub.0.10O.sub.2 and 50 mass % O3-Na.sub.0.95Ni.sub.0.3167Mn.sub.0.3167Mg.sub.0.1583Ti.sub.0.283O.sub.2) cell. These data demonstrate that the level of voltage hysteresis (i.e. the voltage difference between the charge and discharge processes) is small, indicating the excellent kinetic reversibility of the Na-ion extraction-insertion reactions. In addition, the generally symmetrical nature of the charge/discharge voltage profile confirms the excellent reversibility of the extraction-insertion reactions.
(110) FIG. 8(B) shows the constant current cycle life profile (i.e. the relationship between Cathode Specific Capacity for Discharge [mAh/g] and cycle number for the Hard Carbon/(50 mass % P2-Na.sub.0.67Ni.sub.0.23Mn.sub.0.567Mg.sub.0.05Ti.sub.0.10O.sub.2 and 50 mass % O3-Na.sub.0.05Ni.sub.0.3167Mn.sub.0.3167Mg.sub.0.583Ti.sub.0.2083O.sub.2). For cycle 1 the discharge specific capacity for the cathode is about 123 mAh/g. For cycle 15 the discharge specific capacity for the cathode is about 118 mAh/g. This represents a capacity fade of about 4.1% over 30 cycles or an average of 0.14% per cycle. The cathode material under test clearly demonstrates excellent capacity retention behaviour.
EXAMPLE 9: P2/O3-Na0.833Ni0.317Mn0.467Mg0.100Ti0.117O2
(111) FIG. 9(A) shows the X-ray diffraction pattern of the weighted average formula Na.sub.0.833Ni.sub.0.317Mn.sub.0.467Mg.sub.0.100Ti.sub.0.117O.sub.2 (sample number X1682). The pattern shows the presence of both P2-type and O3-type structures.
(112) Referring to FIGS. 9(B)-(C):
(113) The data shown in FIGS. 9(B)-(C) are derived from the constant current cycling data for a mixed phase O3/P2-Na.sub.0.833Ni.sub.0.317Mn.sub.0.467Mg.sub.0.100Ti.sub.0.117O.sub.2 cathode active material in a Na-ion cell (Cell#312017) where this cathode material was coupled with a Hard Carbon (Carbotron P(J)) anode material. The electrolyte used was a 0.5 M solution of NaClO.sub.4 in propylene carbonate. The constant current data were collected at an approximate current density of 0.125 mA/cm.sup.2 between voltage limits of 1.00 and 4.20 V. To ensure that the Na-ion cell was fully charged, the cell was potentiostatically held at 4.2 V at the end of the constant current charging process until the current density dropped to 10% of the constant current value. The testing was carried out at 30 C.
(114) During the cell charging process, sodium ions are extracted from the cathode active material, and inserted into the Hard Carbon anode. During the subsequent discharge process, sodium ions are extracted from the Hard Carbon and re-inserted into the cathode active material.
(115) FIG. 9(B) shows the cell voltage profile (i.e. Na-ion Cell Voltage [V] versus Cumulative Cathode Specific Capacity [mAh/g]) for the first 4 charge/discharge cycles of the Hard Carbon/mixed phase O3/P2-Na.sub.0.833Ni.sub.0.317Mn.sub.0.467Mg.sub.0.100Ti.sub.0.117O.sub.2 cell. These data demonstrate that the level of voltage hysteresis (i.e. the voltage difference between the charge and discharge processes) is small, indicating the excellent kinetic reversibility of the Na-ion extraction-insertion reactions. In addition, the generally symmetrical nature of the charge/discharge voltage profile confirms the excellent reversibility of the extraction-insertion reactions.
(116) FIG. 9(C) shows the constant current cycle life profile (i.e. the relationship between Cathode Specific Capacity for Discharge [mAh/g] and cycle number for the Hard Carbon/mixed phase O3/P2-Na.sub.0.833Ni.sub.0.317Mn.sub.0.467Mg.sub.0.100Ti.sub.0.117O.sub.2 cell. For cycle 1 the discharge specific capacity for the cathode is about 124 mAh/g. For cycle 30 the discharge specific capacity for the cathode is about 127 mAh/g. The cathode specific capacity has improved by around 2.4% over the first 30 cycles. The cathode material under test clearly demonstrates outstanding capacity retention behaviour.
EXAMPLE 10: P2/O3-Na0.750Ni0.296Mn0.509Mg0.079Ti0.117O2
(117) FIG. 10(A) shows the X-ray diffraction pattern of the weighted average formula Na.sub.0.750Ni.sub.0.296Mn.sub.0.509Mg.sub.0.079Ti.sub.0.117O.sub.2(sample number X1692). The pattern shows the presence of both P2-type and O3-type structures.
(118) Referring to FIGS. 10(B)-(C):
(119) The data shown in FIGS. 10(B)-(C) are derived from the constant current cycling data for a mixed phase O3/P2-Na.sub.0.753Ni.sub.0.296Mn.sub.0.509Mg.sub.0.079Ti.sub.0.117O.sub.2 cathode active material in a Na-ion cell (Cell#401003) where this cathode material was coupled with a Hard Carbon (Carbotron P(J)) anode material. The electrolyte used was a 0.5 M solution of NaClO.sub.4 in propylene carbonate. The constant current data were collected at an approximate current density of 0.125 mA/cm.sup.2 between voltage limits of 1.00 and 4.20 V. To ensure that the Na-ion cell was fully charged, the cell was potentiostatically held at 4.2 V at the end of the constant current charging process until the current density dropped to 10% of the constant current value. The testing was carried out at 30 C.
(120) During the cell charging process, sodium ions are extracted from the cathode active material, and inserted into the Hard Carbon anode. During the subsequent discharge process, sodium ions are extracted from the Hard Carbon and re-inserted into the cathode active material.
(121) FIG. 10(B) shows the cell voltage profile (i.e. Na-ion Cell Voltage [V] versus Cumulative Cathode Specific Capacity [mAh/g]) for the first 4 charge/discharge cycles of the Hard Carbon/mixed phase O3/P2-Na.sub.0.753Ni.sub.0.296Mn.sub.0.509Mg.sub.0.079Ti.sub.0.117O.sub.2 cell. These data demonstrate that the level of voltage hysteresis (i.e. the voltage difference between the charge and discharge processes) is small, indicating the excellent kinetic reversibility of the Na-ion extraction-insertion reactions. In addition, the generally symmetrical nature of the charge/discharge voltage profile confirms the excellent reversibility of the extraction-insertion reactions.
(122) FIG. 10(C) shows the constant current cycle life profile (i.e. the relationship between Cathode Specific Capacity for Discharge [mAh/g] and cycle number for the Hard Carbon/mixed phase O3/P2-Na.sub.0.753Ni.sub.0.296Mn.sub.0.509Mg.sub.0.079Ti.sub.0.117O.sub.2 cell. For cycle 1 the discharge specific capacity for the cathode is about 103 mAh/g. For cycle 30 the discharge specific capacity for the cathode is about 104 mAh/g. The cathode specific capacity has improved by around 1% over the first 30 cycles. The cathode material under test dearly demonstrates outstanding capacity retention behaviour.
EXAMPLE 11: P2/O3-Na0.95Ni0.3167Mn0.3167Mg0.1583Ti0.2083O2
(123) FIG. 11(A) shows the X-ray diffraction pattern of the weighted average formula Na.sub.0.95Ni.sub.0.3167Mn.sub.0.3167Mg.sub.0.1583Ti.sub.0.2083O.sub.2 (sample number X1696C). The pattern shows the presence of both P2-type and O3-type structures.
(124) Referring to FIGS. 11(B)-(C):
(125) The data shown in FIGS. 11(B)-(C) are derived from the constant current cycling data for a mixed phase O3/P2-Na.sub.0.95Ni.sub.0.3167Mn.sub.0.3167Mg.sub.0.1583Ti.sub.0.2083O.sub.2 cathode active material in a Na-ion cell (Cell#401003) where this cathode material was coupled with a Hard Carbon (Carbotron P(J)) anode material. The electrolyte used was a 0.5 M solution of NaClO.sub.4 in propylene carbonate. The constant current data were collected at an approximate current density of 0.125 mA/cm.sup.2 between voltage limits of 1.00 and 4.20 V. To ensure that the Na-ion cell was fully charged, the cell was potentiostatically held at 4.2 V at the end of the constant current charging process until the current density dropped to 10% of the constant current value. The testing was carried out at 30 C.
(126) During the cell charging process, sodium ions are extracted from the cathode active material, and inserted into the Hard Carbon anode. During the subsequent discharge process, sodium ions are extracted from the Hard Carbon and re-inserted into the cathode active material.
(127) FIG. 11(B) shows the cell voltage profile (i.e. Na-ion Cell Voltage [V] versus Cumulative Cathode Specific Capacity [mAh/g]) for the first 4 charge/discharge cycles of the Hard Carbon/mixed phase O3/P2-Na.sub.0.95Ni.sub.0.3167Mn.sub.0.3167Mg.sub.0.1583Ti.sub.0.2083O.sub.2 cell. These data demonstrate that the level of voltage hysteresis (i.e. the voltage difference between the charge and discharge processes) is small, indicating the excellent kinetic reversibility of the Na-ion extraction-insertion reactions. In addition, the generally symmetrical nature of the charge/discharge voltage profile confirms the excellent reversibility of the extraction-insertion reactions.
(128) FIG. 11(C) shows the constant current cycle life profile (i.e. the relationship between Cathode Specific Capacity for Discharge [mAh/g] and cycle number for the Hard Carbon/mixed phase O3/P2-Na.sub.0.95Ni.sub.0.3167Mn.sub.0.3167Mg.sub.0.1583Ti.sub.0.2083O.sub.2 cell. For cycle 1 the discharge specific capacity for the cathode is about 134 mAh/g. For cycle 30 the discharge specific capacity for the cathode is about 129 mAh/g. This represent a capacity fade of about 3.7% over 30 cycles or an average of 0.12% per cycle. The cathode material under test clearly demonstrates excellent capacity retention behaviour.
EXAMPLE 12: P2/O3-Na0.75Ni0.296Mn0.508Mg0.079Ti0.117O2
(129) FIG. 12(A) shows the X-ray diffraction pattern of the weighted average formula Na.sub.0.75Ni.sub.0.296Mn.sub.0.508Mg.sub.0.079Ti.sub.0.117O.sub.2 (sample number X1700). The pattern shows the presence of both P2-type and O3-type structures.
(130) Referring to FIGS. 12(B)-(C):
(131) The data shown in FIGS. 12(B)-(C) are derived from the constant current cycling data for a mixed phase O3/P2-Na.sub.0.75Ni.sub.0.296Mn.sub.0.508Mg.sub.0.079Ti.sub.0.117O.sub.2 cathode active material in a Na-ion cell (Cell#401014) where this cathode material was coupled with a Hard Carbon (Carbotron P(J)) anode material. The electrolyte used was a 0.5 M solution of NaClO.sub.4 in propylene carbonate. The constant current data were collected at an approximate current density of 1.00 mA/cm.sup.2 between voltage limits of 1.00 and 4.20 V. To ensure that the Na-ion cell was fully charged, the cell was potentiostatically held at 4.2 V at the end of the constant current charging process until the current density dropped to 10% of the constant current value. The testing was carried out at 30 C.
(132) During the cell charging process, sodium ions are extracted from the cathode active material, and inserted into the Hard Carbon anode. During the subsequent discharge process, sodium ions are extracted from the Hard Carbon and re-inserted into the cathode active material.
(133) FIG. 12(B) shows the cell voltage profile (i.e. Na-ion Cell Voltage [V] versus Cumulative Cathode Specific Capacity [mAh/g]) for 4 charge/discharge cycles of the Hard Carbon/mixed phase O3/P2-Na.sub.0.75Ni.sub.0.296Mn.sub.0.508Mg.sub.0.079Ti.sub.0.117O.sub.2 cell. These data demonstrate that the level of voltage hysteresis (i.e. the voltage difference between the charge and discharge processes) is small, indicating the excellent kinetic reversibility of the Na-ion extraction-insertion reactions. In addition, the generally symmetrical nature of the charge/discharge voltage profile confirms the excellent reversibility of the extraction-insertion reactions.
(134) FIG. 12(C) shows the constant current cycle life profile (i.e. the relationship between Cathode Specific Capacity for Discharge [mAh/g] and cycle number for the Hard Carbon/mixed phase O3/P2-Na.sub.0.75Ni.sub.0.296Mn.sub.0.508Mg.sub.0.079Ti.sub.0.117O.sub.2 cell. For cycle 1 the discharge specific capacity for the cathode is about 103 mAh/g. For cycle 200 the discharge specific capacity for the cathode is about 93 mAh/g. This represent a capacity fade of about 9.7% over 200 cycles or an average of 0.05% per cycle. The cathode material under test clearly demonstrates excellent capacity retention behaviour.
EXAMPLE 13: P3/P2-Na0.666Ni0.3Mn0.6Mg0.033Ti0.067O2
(135) FIG. 13 shows the X-ray diffraction pattern of the weighted average formula Na.sub.0.666Ni.sub.0.3Mn.sub.0.6Mg.sub.0.033Ti.sub.0.067O.sub.2 (sample number S0842). The pattern shows the presence of both P3-type and P2-type structures.
EXAMPLE 14: P3/P2-Na0.6667Ni0.2500Mn0.5833Mg0.0833Ti0.0833O2
(136) FIG. 14 shows the X-ray diffraction pattern of the weighted average formula Na.sub.0.6667Ni.sub.0.2500Mn.sub.0.5833Mg.sub.0.0833Ti.sub.0.0833O.sub.2 (sample number S1430A). The pattern shows the presence of both P3-type and P2-type structures.
EXAMPLE 15: P3/P2/O3-Na0.8292Ni0.2886Mn0.4622Mg0.126Ti0.1233O2
(137) FIG. 15 shows the X-ray diffraction pattern of the weighted average formula Na.sub.0.8292Ni.sub.0.2886Mn.sub.0.4622Mg.sub.0.126Ti.sub.0.1233O.sub.2 (sample number S1458B). The pattern shows the presence of P3-type, P2-type and O3-type structures.
EXAMPLE 16: P3/P2/O3-Na0.8188Ni0.2860Mn0.4561Mg0.1234Ti0.1346O2
(138) FIG. 16 shows the X-ray diffraction pattern of the weighted average formula Na.sub.0.8188Ni.sub.0.2860Mn.sub.0.4561Mg.sub.0.1234Ti.sub.0.1346O.sub.2 (sample number S1459B). The pattern shows the presence of P3-type, P2-type and O3-type structures.
