ELECTRODE MATERIALS COMPRISING A LAYERED SODIUM METAL OXIDE, ELECTRODES COMPRISING THEM AND THEIR USE IN ELECTROCHEMISTRY

Abstract

The present technology relates to electrode materials comprising an electrochemically active material, wherein the electrochemically active material comprises a P2-type or a O3-type layered sodium metal oxide. The electrochemically active material is of formula Na.sub.xMO.sub.2, wherein 0.5≤x≤1.0 and M is selected from Co, Mn, Fe, Ni, Ti, Cr, V, Cu, Sb and their combinations. Also described are electrodes, electrochemical cells and batteries comprising the electrode materials.

Claims

1. An electrode material comprising an electrochemically active material, said electrochemically active material comprising a layered sodium metal oxide of formula Na.sub.xMO.sub.2, wherein x is a number such that 0.5×1.0 and M is selected from Co, Mn, Fe, Ni, Ti, Cr, V, Cu, Sb and their combinations.

2. Electrode material according to claim 1, wherein the electrochemically active material comprises a layered sodium metal oxide selected from: a P2-type layered sodium metal oxide of formula Na.sub.xMO.sub.2, wherein x is a number such that 0.5×0.8 and M is selected from Co, Mn, Fe, Ni, Ti, Cr, V, Cu and their combinations; and an O3-type layered sodium metal oxide of formula Na.sub.xMO.sub.2, wherein x is a number such that 0.8×1.0 and M is selected from Co, Mn, Fe, Ni, Ti, Cr, V, Cu, Sb and their combinations.

3. Electrode material according to claim 1, wherein the electrochemically active material comprises a layered sodium metal oxide of formula Na.sub.xM′.sub.1-yM.sub.yO.sub.2, wherein x and M are as defined in claim 1, y is a number such that 0≤y≤1.0 and M′ is different from M and is selected from Co, Mn, Fe, Ni, Ti, Cr, V, Cu, Sb and their combinations.

4. Electrode material according to claim 1, wherein the electrochemically active material comprises a layered sodium metal oxide of formula Na.sub.xM′.sub.1-yMn.sub.yO.sub.2, wherein x is as defined in claim 1, y is a number such that 0≤y≤1.0 and M′ is selected from Co, Fe, Ni, Ti, Cr, V, Cu, Sb and their combinations.

5. Electrode material according to claim 1, wherein the electrochemically active material comprises a layered sodium cobalt oxide of formula Na.sub.xCoO.sub.2, wherein x is as defined in claim 1.

6. Electrode material according to claim 1, wherein the electrochemically active material comprises a layered sodium manganese oxide of formula Na.sub.xMnO.sub.2, wherein x is as defined in claim 1.

7. Electrode material according to claim 1, wherein the electrochemically active material comprises a layered sodium metal oxide of formula Na.sub.x(NiCo).sub.1-yMn.sub.yO.sub.2, wherein x is as defined in claim 1 and y is a number such that 0≤y≤1.0.

8. Electrode material according to claim 1, wherein the electrochemically active material comprises a layered sodium metal oxide of formula Na.sub.xCo.sub.1-yMn.sub.yO.sub.2, wherein x is as defined in claim 1 and y is a number such that 0≤y≤1.0.

9. Electrode material according to claim 1, wherein the electrochemically active material comprises a layered sodium metal oxide of formula Na.sub.xNi.sub.1-yMn.sub.yO.sub.2, wherein x is as defined in claim 1 and y is a number such that 0≤y≤1.0.

10. Electrode material according to claim 1, wherein the electrochemically active material comprises a layered sodium metal oxide of formula Na.sub.x(CoTi).sub.1-yMn.sub.1-yO.sub.2, wherein x is as defined in claim 1 and y is a number such that 0≤y≤1.0.

11. Electrode material according to claim 1, further comprising an electronically conductive material preferably selected from carbon black, acetylene black, graphite, graphene, carbon fibers, carbon nanofibers, carbon nanotubes, and their combinations.

12. (canceled)

13. Electrode material according to claim 11, wherein the electronically conductive material comprises carbon fibers, preferably the carbon fibers are vapor grown carbon fibers (VGCFs), or wherein the electronically conductive material comprises carbon black, preferably the carbon black is Super P™ carbon or Ketien™ carbon.

14-17. (canceled)

18. Electrode material according to claim 1, further comprising a binder preferably selected from the group consisting of a polymeric binder of polyether type, a fluorinated polymer, and a water-soluble binder.

19. (canceled)

20. Electrode material according to claim 18, wherein the binder is a fluorinated polymer, preferably the fluorinated polymer is polyvinylidene fluoride (PVdF).

21-22. (canceled)

23. Electrode material according to claim 18, wherein the binder is a polymeric binder of polyether type, preferably wherein the polymeric binder of polyether type is branched and/or crosslinked or wherein the polymeric binder of polyether type is based on polyethylene oxide (PEO).

24-25. (canceled)

26. An electrode comprising the electrode material as defined in claim 1 on a current collector, wherein the electrode is preferably a positive electrode.

27. (canceled)

28. An electrochemical cell comprising a negative electrode, a positive electrode and an electrolyte, wherein the positive electrode is as defined in claim 26.

29. Electrochemical cell according to claim 28, wherein the negative electrode comprises metallic lithium or metallic sodium.

30. (canceled)

31. Electrochemical cell according to claim 28, wherein the electrolyte is a liquid electrolyte comprising a salt in a solvent, or is a gel electrolyte comprising a salt in a solvent and optionally a solvating polymer, or is a solid polymer electrolyte comprising a salt in a solvating polymer, preferably wherein the salt is a lithium salt or a sodium salt.

32-35. (canceled)

36. A battery comprising at least one electrochemical cell as defined in claim 28, wherein said battery is preferably selected from a lithium ion battery and a sodium ion battery.

37-39. (canceled)

Description

BRIEF DESCRIPTION OF THE FIGURES

[0018] FIG. 1 is an X-ray diffraction pattern for a P2-type layered sodium cobalt oxide powder of formula Na.sub.0.5CoO.sub.2 obtained using the solid-state process.

[0019] FIG. 2 is an X-ray diffraction pattern for a mixed O3-type mixed layered sodium transition metal oxide powder of formula NaNi.sub.0.4Co.sub.0.2Mn.sub.0.4O.sub.2 obtained using the solid-state process.

[0020] FIG. 3 displays the charge and discharge profiles of Cell 1, the charge and discharge being performed at 0.1 C, and recorded vs Li/Li.sup.+ at a temperature of 25° C.

[0021] FIG. 4 displays the charge and discharge profiles of Cell 1 at different cycling rates, the charge and discharge being performed at 0.1 C, 0.2 C, 0.5 C, 1 C, 2 C and 4 C and recorded vs Li/Li.sup.+ at a temperature of 25° C.

[0022] FIG. 5 shows a graph representing the capacity (mAh/g) as a function of the number of cycles, i.e. an aging curve for Cell 1. The long cycling or cycling stability experiment was carried out at a constant charge/discharge current of 1 C and the results were recorded vs Li/Li.sup.+ at a temperature of 25° C.

[0023] FIG. 6 displays the charge and discharge profiles of Cell 2. The charge and discharge were performed at 0.3 C between 2.0 and 4.4 V vs Li/Li.sup.+ at a temperature of 50° C.

[0024] FIG. 7 displays the charge and discharge profiles of Cell 2. The charge and discharge were performed at 0.3 C between 2.0 and 4.4 V vs Li/Li.sup.+ at a temperature of 80° C.

[0025] FIG. 8 displays the charge and discharge profiles of Cell 3. The charge and discharge were performed at 0.1 C between 2.0 and 4.4 V vs Li/Li.sup.+ at a temperature of 25° C.

[0026] FIG. 9 displays the charge and discharge profiles of Cell 3 at different cycling rates, the charge and discharge being performed at 0.1 C, 0.2 C, 0.5 C, 1 C, 2 C and 4 C and recorded vs Li/Li.sup.+ at a temperature of 25° C.

[0027] FIG. 10 shows a graph representing the capacity (mAh/g) as a function of the number of cycles for Cell 3. The long cycling experiment was carried out at a constant charge/discharge current of 2 C and the results were recorded vs Li/Li.sup.+ at a temperature of 25° C.

[0028] FIG. 11 displays the initial charge and discharge curves of Cell 4. The charge and discharge were performed at 0.1 C between 2.0 and 4.4 V vs Li/Li.sup.+ at a temperature of 25° C.

[0029] FIG. 12 displays two charge and discharge profiles of Cell 5, specifically the first cycle and the fifth cycle. The charge and discharge were performed at 0.3 C between 2.0 and 4.0 V vs Li/Li.sup.+ at a temperature of 80° C.

[0030] FIG. 13 displays the charge and discharge profiles of Cell 6, the charge and discharge being performed at 0.1 C between 2.0 and 4.4 V vs Li/Li.sup.+ at a temperature of 25° C.

[0031] FIG. 14 displays the charge and discharge profiles of Cell 7, the charge and discharge being performed at 0.1 C between 2.0 and 4.4 V vs Li/Li.sup.+ at a temperature of 25° C.

[0032] FIG. 15 displays the charge and discharge profiles of Cell 8, the charge and discharge being performed at 0.1 C between 2.0 and 4.4 V vs Li/Li.sup.+ at a temperature of 25° C.

[0033] FIG. 16 displays the charge and discharge profiles of Cell 9, the charge and discharge being performed at 0.1 C between 2.0 and 4.5 V vs Li/Li.sup.+ at a temperature of 25° C.

[0034] FIG. 17 displays the charge and discharge profiles of Cell 10, the charge and discharge being performed at 0.1 C between 2.0 and 4.4 V vs Li/Li.sup.+ at a temperature of 25° C.

[0035] FIG. 18 displays the charge and discharge profiles of Cell 11, the charge and discharge being performed at 0.1 C between 2.0 and 4.4 V vs Li/Li.sup.+ at a temperature of 25° C.

[0036] FIG. 19 shows a graph representing the capacity (mAh/g) as a function of the number of cycles for Cell 11. The long cycling experiment was carried out at a constant charge/discharge current of 0.1 C and the results were recorded vs Li/Li.sup.+ at a temperature of 25° C.

DETAILED DESCRIPTION

[0037] The following detailed description and examples are presented for illustrative purposes only and should not be construed as further limiting the scope of the invention.

[0038] All technical and scientific terms and expressions used herein have the same definitions as those commonly understood by the person skilled in the art relating to the present technology. The definition of some terms and expressions used is nevertheless provided below.

[0039] When the term “approximately” or its equivalent term “about” are used herein, it means in the region of, or around. For example, when the terms “approximately” or “about” are used in relation to a numerical value, it modifies it above and below by a variation of 10% compared to the nominal value. This term can also take into account, for instance, the experimental error of a measuring device or rounding.

[0040] When a range of values is mentioned in the present application, the lower and upper limits of the range are, unless otherwise indicated, always included in the definition.

[0041] The present technology relates to the use of layered oxides of sodium and at least one metallic element as electrochemically active materials. The layered oxide of sodium and at least one metallic element has a P2-type or O3-type stacking.

[0042] In one example, the metallic element is a metal, for instance, a transition metal, a post-transition metal, a metalloid, an alkali metal, an alkaline earth metal, or combinations thereof. For example, the metal is selected from Co, Mn, Fe, Ni, Ti, Cr, V, Cu, Sb and a combination of at least two thereof.

[0043] In one example, the electrochemically active material comprises a layered sodium metal oxide of formula Na.sub.xMO.sub.2, wherein x is a number such that 0.5×1.0 and M is selected from Co, Mn, Fe, Ni, Ti, Cr, V, Cu, Sb and their combinations.

[0044] In another example, the electrochemically active material comprises a P2-type layered sodium metal oxide of formula Na.sub.xMO.sub.2, wherein x is a number such that 0.5×0.8 and M is selected from Co, Mn, Fe, Ni, Ti, Cr, V, Cu and their combinations.

[0045] In another example, the electrochemically active material comprises an O3-type layered sodium metal oxide of formula Na.sub.xMO.sub.2, wherein x is a number such that 0.8×1.0 and M is selected from Co, Mn, Fe, Ni, Ti, Cr, V, Cu, Sb and their combinations.

[0046] In another example, the electrochemically active material is a layered sodium cobalt oxide of formula Na.sub.xCoO.sub.2, wherein x is as defined herein. For example, the layered sodium cobalt oxide has a P2-type stacking. An example of a layered sodium cobalt oxide has the formula Na.sub.0.5CoO.sub.2.

[0047] In another example, the electrochemically active material is a layered sodium manganese oxide of formula Na.sub.xMnO.sub.2, wherein x is as defined herein.

[0048] An additional example of an electrochemically active material comprises a mixed layered oxide of formula Na.sub.xM′.sub.1-yM.sub.yO.sub.2, wherein x and M are as defined herein, y is a number such that 0≤y=1.0 and M′ and is selected from Co, Mn, Fe, Ni, Ti, Cr, V, Cu, Sb and their combinations, where M and M′ are different.

[0049] For example, the electrochemically active material comprises a mixed layered oxide of sodium, manganese and metal of formula Na.sub.xM′.sub.1-yMn.sub.yO.sub.2, wherein x and y are as defined herein and M′ is selected from Co, Fe, Ni, Ti, Cr, V, Cu, Sb and their combinations. For example, the electrochemically active material is selected from mixed layered oxides of formulae Na.sub.x(NiCo).sub.1-yMn.sub.yO.sub.2, Na.sub.xCo.sub.1-yMn.sub.yO.sub.2, Na.sub.xNi.sub.1-yMn.sub.yO.sub.2 and Na.sub.x(CoTi).sub.1-yMn.sub.1-yO.sub.2, wherein x and y are as defined. Non-limiting examples of electrochemically active material include Na.sub.0.5CoO.sub.2, Na.sub.0.67CoO.sub.2, Na.sub.0.67Co.sub.0.67Mn.sub.0.33O.sub.2, Na.sub.0.67Ni.sub.0.33Mn.sub.0.67O.sub.2, Na.sub.0.67Co.sub.0.6Mn.sub.0.4O.sub.2, Na.sub.0.67Co.sub.0.55Mn.sub.0.45O.sub.2, Na.sub.0.67Co.sub.0.5Mn.sub.0.5O.sub.2, Na.sub.0.67Co.sub.0.50Mn.sub.0.33Ti.sub.0.17O.sub.2, Na.sub.0.6MnO.sub.2, NaNi.sub.0.4Co.sub.0.2Mn.sub.0.4O.sub.2, and NaNi.sub.0.33Fe.sub.0.33Mn.sub.0.33O.sub.2.

[0050] The electrochemically active material can optionally be doped with other elements or impurities included in smaller amounts, for example, to modulate or optimize its electrochemical properties. In some cases, the electrochemically active material can be doped by the partial substitution of the metal (M) by other ions. For example, the electrochemically active material can be doped with a transition metal (e.g. Fe, Co, Ni, Mn, Ti, Cr, Cu, V) and/or a metal other than a transition metal (e.g. Mg, Al, Sb).

[0051] The electrochemically active material described herein is preferably substantially free of lithium. For example, the electrochemically active material comprises less than 2 wt. %, less than 1 wt. %, less than 0.5 wt. %, less than 0.1 wt. %, less than 0.05 wt. % or less than 0.01 wt. % of lithium. The electrochemically active material can therefore potentially reduce production costs compared to the corresponding P2-type or O3-type lithium metal oxide structures. The electrochemically active material can also retain the same structure as the corresponding P2-type or O3-type lithium metal oxide structures and have similar electrochemical performances.

[0052] The present technology also relates to electrode materials comprising the electrochemically active material as defined herein. In one example, the electrode material as described herein may further comprise an electronically conductive material. Non-limiting examples of electronically conductive materials include carbon black, Ketjen™ carbon, Super P™ carbon, acetylene black, Shawinigan carbon, Denka™ carbon black, graphite, graphene, carbon fibers (e.g. vapor grown carbon fibers (VGCFs)), carbon nanofibers, carbon nanotubes, or a combination of at least two thereof. According to one example, the electronically conductive material is Ketjen™ carbon. According to one alternative, the electronically conductive material is Super P™ carbon. According to another alternative, the electronically conductive material is VGCFs.

[0053] The electrode material as described herein can also further comprise a binder. For example, the binder is selected for its compatibility with the various elements of the electrochemical cell. Any known compatible binder is contemplated. For instance, the binder is selected from a polymeric binder of polyether type, a fluorinated polymer, and a water-soluble binder (hydrosoluble). According to one example, the binder is a fluorinated polymer such as polyvinylidene fluoride (PVdF) or polytetrafluoroethylene (PTFE). According to another example, the binder is a water soluble binder such as styrene-butadiene rubber (SBR), acrylonitrile-butadiene rubber (NBR), hydrogenated NBR (HNBR), epichlorohydrin rubber (CHR), or acrylate rubber (ACM), and optionally comprising a thickening agent such as carboxymethyl cellulose (CMC), or a polymer such as poly(acrylic acid) (PAA), poly(methacrylic acid) (PMMA) or a combination thereof. According to one example, the binder is a polymeric binder of polyether type. For example, the polymeric binder of polyether type is linear, branched and/or crosslinked and is based on poly(ethylene oxide) (PEO), poly(propylene oxide) (PPO) or a combination of the two (such as an EO/PO copolymer), and optionally comprises crosslinkable units. In one variant of interest, the binder is PVdF or a polyether type polymer as defined herein.

[0054] The electrode material as described herein may further optionally comprise additional components or additives such as inorganic particles, glass or ceramic particles, ionic conductors, salts (for example, lithium salts) and other similar additives.

[0055] The present technology also relates to an electrode comprising the electrode material as herein defined on a current collector (for example, aluminum, copper). Alternatively, the electrode may be self-supported. In one variant of interest, the electrode is a positive electrode.

[0056] The present technology also relates to an electrochemical cell comprising a negative electrode, a positive electrode and an electrolyte, wherein the positive electrode is as defined herein.

[0057] In one example, the electrochemically active material of the negative electrode or of the counter-electrode can be selected from all known compatible materials. For example, the electrochemically active material of the negative electrode can be selected for its electrochemical compatibility with the electrochemically active material as defined herein. For example, the electrochemically active material of the negative electrode may comprise an alkali metal film, for example, a metallic lithium film, a metallic sodium film, or a film of an alloy comprising at least one of these.

[0058] The electrolyte is also selected for its compatibility with the various elements of the electrochemical cell. Any type of compatible electrolyte is contemplated. According to one example, the electrolyte is a liquid electrolyte comprising a salt in a solvent. According to one alternative, the electrolyte is a gel electrolyte comprising a salt in a solvent and optionally a solvating polymer. According to another alternative, the electrolyte is a solid polymer electrolyte comprising a salt in a solvating polymer.

[0059] The salt is preferably an ionic salt such as a lithium salt or a sodium salt. Non-limiting examples of lithium salts include lithium hexafluorophosphate (LiPF.sub.6), lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), lithium bis(fluorosulfonyl)imide (LiFSI), lithium 2-trifluoromethyl-4,5-dicyanoimidazolate (LiTDI), lithium 4,5-dicyano-1,2,3-triazolate (LiDCTA), lithium bis(pentafluoroethylsulfonyl)imide (LiBETI), lithium tetrafluoroborate (LiBF.sub.4), lithium bis(oxalato)borate (LiBOB), lithium nitrate (LiNO.sub.3), lithium chloride (LiCI), lithium bromide (LiBr), lithium fluoride (LiF), lithium perchlorate (LiClO.sub.4), lithium hexafluoroarsenate (LiAsF.sub.6), lithium trifluoromethanesulfonate (LiSO.sub.3CF.sub.3) (LiTf), lithium fluoroalkylphosphate Li[PF.sub.3(CF.sub.2CF.sub.3).sub.3] (LiFAP), lithium tetrakis(trifluoroacetoxy)borate Li[B(OCOCF.sub.3).sub.4] (LiTFAB), lithium bis(1,2-benzenediolato(2-)-O,O′)borate [B(C.sub.6O.sub.2).sub.2] (LiBBB), and their combinations. According to a first variant of interest, the lithium salt is LiPF.sub.6. According to a second variant of interest, the lithium salt is LiFSI. According to a third variant of interest, the lithium salt is LiTFSI. Non-limiting examples of sodium salts include the salts described above where the lithium ion is replaced by a sodium ion.

[0060] The solvent, if present in the electrolyte, can be a polar aprotic non-aqueous solvent. Non-limiting examples of solvents include cyclic carbonates such as ethylene carbonate (EC), propylene carbonate (PC), butylene carbonate (BC) and vinylene carbonate (VC); acyclic carbonates such as dimethyl carbonate (DMC), diethyl carbonate (DEC), ethylmethyl carbonate (EMC) and dipropyl carbonate (DPC); lactones such as γ-butyrolactone (γ-BL) and γ-valerolactone (γ-VL); acyclic ethers such as 1,2-dimethoxyethane (DME), 1,2-diethoxyethane (DEE), ethoxymethoxyethane (EME), trimethoxymethane and ethylmonoglyme; cyclic ethers such as tetrahydrofuran, 2-methyltetrahydrofuran, 1,3-dioxolane and dioxolane derivatives; and other solvents such as dimethylsulfoxide, formamide, acetamide, dimethylformamide, acetonitrile, propylnitrile, nitromethane, phosphoric acid triesters, sulfolane, methylsulfolane, propylene carbonate derivatives and mixtures thereof.

[0061] An electrolyte example comprises lithium hexafluorophosphate (LiPF.sub.6) dissolved in a non-aqueous solvent mixture such as a mixture of ethylene carbonate and diethyl carbonate (EC/DEC) ([3:7] by volume) or a mixture of ethylene carbonate and dimethyl carbonate (EC/DMC) ([4:6] by volume).

[0062] When the electrolyte is a gel electrolyte or a polymer gel electrolyte, the gel polymer electrolyte can include, for example, a polymer precursor and a salt (for example, a salt as defined above), a solvent and a polymerization and/or crosslinking initiator if necessary. Non-limiting examples of gel electrolytes include, without limitation, the gel electrolytes described in PCT patent application published under numbers WO2009/111860 (Zaghib et al.) and WO2004/068610 (Zaghib et al.).

[0063] The electrolyte can also be a solid polymer electrolyte (SPE) comprising a salt in a solvating polymer. Any type of known compatible SPE is contemplated. For instance, the SPE is selected for its compatibility with the various elements of the electrochemical cell. For example, the SPE is selected for its compatibility with lithium and/or sodium. SPEs can generally include a salt as well as one or more solid polar polymer(s), optionally crosslinked. Polyether-type polymers, such as those based on poly(ethylene oxide) (PEO) can be used, but several other compatible polymers are also known for the preparation of SPEs and are also contemplated. According to an example, the polymer may be further crosslinked. Examples of such polymers include branched polymers, for example, star-shaped polymers or comb-shaped polymers such as those described in PCT patent application published under number WO2003/063287 (Zaghib et al.).

[0064] A gel electrolyte or a liquid electrolyte as defined above may also impregnate a separator such as a polymer separator. Non-limiting examples of separators include polyethylene (PE), polypropylene (PP), cellulose, polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVdF) and polypropylene-polyethylene-polypropylene (PP/PE/PP) membranes. For example, the separator is a commercial polymer separator of the Celgard™ type.

[0065] The electrolyte can also optionally include additional components or additives such as ionic conductors, inorganic particles, glass or ceramic particles, for example, nanoceramics (such as Al.sub.2O.sub.3, TiO.sub.2, SiO.sub.2 and other similar compounds) and other similar additives.

[0066] The present technology also generally relates to a battery comprising at least one electrochemical cell as defined herein. For example, said battery is selected from a lithium battery, a lithium-ion battery, a sodium battery and a sodium-ion battery. According to one variant of interest, the battery is a lithium battery or a lithium-ion battery.

EXAMPLES

[0067] The following examples are for illustrative purposes and should not be interpreted as further limiting the scope of the invention as contemplated. These examples will be better understood by referring to the accompanying Figures.

Example 1: Electrochemically Active Materials Synthesis

[0068] Layered oxides of formulae Na.sub.0.5CoO.sub.2, Na.sub.0.67CoO.sub.2, Na.sub.0.67Co.sub.0.67Mn.sub.0.33O.sub.2, Na.sub.0.67Ni.sub.0.33Mn.sub.0.67O.sub.2, Na.sub.0.67Co.sub.0.6Mn.sub.0.4O.sub.2, Na.sub.0.67Co.sub.0.55Mn.sub.0.45O.sub.2, Na.sub.0.67Co.sub.0.5Mn.sub.0.5O.sub.2, Na.sub.0.67Co.sub.0.50Mn.sub.0.33Ti.sub.0.17O.sub.2, Na.sub.0.6MnO.sub.2, NaNi.sub.0.4Co.sub.0.2Mn.sub.0.4O.sub.2 and NaNi.sub.0.33Fe.sub.0.33Mn.sub.0.33O.sub.2 were prepared using solid state reaction techniques. The respective precursors (Na.sub.2CO.sub.3 and metal oxides such as Mn.sub.2O.sub.3, Co.sub.2O.sub.3, NiO, Fe.sub.2O.sub.3 and TiO.sub.2) were weighted in order to obtain the desired stoichiometry. The samples were prepared by grinding and mixing the precursor powders. The ground and mixed precursor powders were then put in an oven and heated between 700° C. and 1000° C. under an air or an oxygen atmosphere for 5 to 24 hours.

Example 2: Characterization of Electrochemically Active Materials

a) Powder X-Ray Diffraction (XRD)

[0069] The atomic and molecular structure of the electrochemically active materials were studied by X-ray diffraction carried out on both P2-type and O3-type layered sodium metal oxide structures prepared in Example 1. FIG. 1 displays the X-ray diffraction pattern for a P2-type layered Na.sub.0.5CoO.sub.2 powder and FIG. 2 displays the X-ray diffraction pattern for an O3-type layered NaNi.sub.0.4Co.sub.0.2Mn.sub.0.4O.sub.2 powder.

Example 3: Electrochemical Properties

[0070] All cells were assembled in 2032 type coin cell casings with the components indicated in Table 1 and negative electrodes including metallic lithium film on aluminum current collectors. The cells comprising liquid electrolytes were assembled with Celgard™ separators impregnated with a 1 M solution of LiPF.sub.6 in an EC/DEC mixture ([3:7] by volume) or an EC/DMC mixture ([4:6] by volume). Cells comprising solid polymer electrolytes were assembled with an SPE comprising LIFSI or LITFSI.

TABLE-US-00001 TABLE 1 Cell configurations Electrode material composition Electron- ically con- Electrochemically ductive Elec- Cell active material material Binder trolyte Cell 1 Na.sub.0.67CoO.sub.2 10 wt.% PVdF Liquid (80 wt. %) (10 wt. %) Cell 2 Na.sub.0.67CoO.sub.2 24 wt. % SPE SPE (75 wt. %)  (1 wt. %) Cell 3 Na.sub.0.67Co.sub.0.67Mn.sub.0.33O.sub.2 10 wt.% PVdF Liquid (80 wt. %) (10 wt. %) Cell 4 Na.sub.0.67Ni.sub.0.33Mn.sub.0.67O.sub.2 10 wt. % PVdF Liquid (80 wt. %) (10 wt. %) Cell 5 Na.sub.0.67Ni.sub.0.33Mn.sub.0.67O.sub.2 24 wt. % SPE SPE (75 wt. %)  (1 wt. %) Cell 6 Na.sub.0.67Co.sub.0.6Mn.sub.0.4O.sub.2 10 wt. % PVdF Liquid (80 wt. %) (10 wt. %) Cell 7 Na.sub.0.67Co.sub.0.55Mn.sub.0.45O.sub.2 10 wt. % PVdF Liquid (80 wt. %) (10 wt. %) Cell 8 Na.sub.0.67Co.sub.0.5Mn.sub.0.5O.sub.2 10 wt. % PVdF Liquid (80 wt. %) (10 wt. %) Cell 9 Na.sub.0.67Co.sub.0.50Mn.sub.0.33Ti.sub.0.17O.sub.2 10 wt. % PVdF Liquid (80 wt. %) (10 wt. %) Cell Na.sub.0.6MnO.sub.2 10 wt. % PVdF Liquid 10 (80 wt. %) (10 wt. %) Cell NaNi.sub.0.4Co.sub.0.2Mn.sub.0.4O.sub.2 10 wt. % PVdF Liquid 11 (80 wt. %) (10 wt. %)
a) Electrochemical Behavior of P2-type Na.sub.0.67CoO.sub.2

[0071] This example illustrates the electrochemical behavior of a P2-type layered Na.sub.0.67CoO.sub.2 material as prepared in Example 1.

[0072] FIG. 3 displays the charge and discharge profiles of Cell 1. The charge and discharge were performed at 0.1 C, and recorded vs Li/Li.sup.+ at a temperature of 25° C. Cell 1 delivered a capacity of approximately 104 mAh/g.

[0073] FIG. 4 displays charge and discharge profiles for Cell 1 at different cycling rates. The charge and discharge were performed at 0.1 C, 0.2 C, 0.5 C, 1 C, 2 C and 4 C and recorded vs Li/Li.sup.+ at a temperature of 25° C. At a cycling rate of 4 C, Cell 1 delivered a capacity of approximately 92 mAh/g, effectively showing a capacity retention of 87% with increasing cycling rates from 0.5 C to 4 C.

[0074] FIG. 5 shows a graph representing the capacity (mAh/g) as a function of the number of cycles for Cell 1. The long cycling experiment was carried out at a constant charge/discharge current of 1 C. The results were recorded vs Li/Li.sup.+ at a temperature of 25° C. FIG. 5 shows a capacity retention of about 97% after 200 cycles.

[0075] The influence of binder selection and cycling temperature is demonstrated in FIGS. 6 and 7.

[0076] FIG. 6 displays the charge and discharge profiles of Cell 2. The charge and discharge were performed at 0.3 C between 2.0 and 4.4 V vs Li/Li.sup.+ at a temperature of 50° C. Cell 2 delivered a capacity of approximately 107 mAh/g.

[0077] FIG. 7 displays the charge and discharge profiles of Cell 2. The charge and discharge were performed at 0.3 C between 2.0 and 4.4 V vs Li/Li.sup.+ at a temperature of 80° C. Cell 2 delivered a capacity of approximately 107 mAh/g.

b) Electrochemical Behavior of P2-type Na.sub.0.67Co.sub.0.67Mn.sub.0.33O.sub.2

[0078] This example illustrates the electrochemical behavior of a P2-type layered Na.sub.0.67Co.sub.0.67Mn.sub.0.33O.sub.2 material as prepared in Example 1.

[0079] FIG. 8 displays the charge and discharge profiles of Cell 3. The charge and discharge were performed at 0.1 C between 2.0 and 4.4 V vs Li/Li.sup.+ at a temperature of 25° C. Cell 3 delivered a capacity of approximately 150 mAh/g.

[0080] FIG. 9 displays charge and discharge profiles of Cell 3 at different cycling rates. The charge and discharge were performed at 0.1 C, 0.2 C, 0.5 C, 1 C, 2 C and 4 C and recorded vs Li/Li.sup.+ at a temperature of 25° C. At a cycling rate of 4 C, Cell 3 delivered a capacity of approximately 121 mAh/g, effectively showing a capacity retention of 80% with increasing cycling rate from 0.1 C to 4 C.

[0081] FIG. 10 shows a graph representing the capacity (mAh/g) as a function of the number of cycles for Cell 3. The long cycling experiment was carried out at a constant charge/discharge current of 2 C. The results were recorded vs Li/Li.sup.+ at a temperature of 25° C. FIG. 10 shows a capacity retention of about 93.4% after 100 cycles.

c) Electrochemical Behavior of P2-type Na.sub.0.67Ni.sub.0.33Mn.sub.0.67O.sub.2

[0082] This example illustrates the electrochemical behavior of a P2-type layered Na.sub.0.67Ni.sub.0.33Mn.sub.0.67O.sub.2 material as prepared in Example 1.

[0083] FIG. 11 displays the initial charge and discharge curves of Cell 4. The charge and discharge were performed at 0.1 C between 2.0 and 4.4 V vs Li/Li.sup.+ at a temperature of 25° C. Cell 4 delivered a capacity of approximately 182 mAh/g.

[0084] FIG. 12 displays two charge and discharge profiles of Cell 5, i.e., the first cycle and the fifth cycle. The charge and discharge were performed at 0.3 C between 2.0 and 4.0 V vs Li/Li.sup.+ at a temperature of 80° C. Cell 5 delivered a capacity of approximately 120 mAh/g.

d) Electrochemical Behavior of P2-type Na.sub.0.67Co.sub.0.6Mn.sub.0.4O.sub.2

[0085] This example illustrates the electrochemical behavior of a P2-type layered Na.sub.0.67Co.sub.0.6Mn.sub.0.4O.sub.2 material as prepared in Example 1.

[0086] FIG. 13 displays the charge and discharge profiles of Cell 6. The charge and discharge were performed at 0.1 C between 2.0 and 4.4 V vs Li/Li.sup.+ at a temperature of 25° C. Cell 6 delivered a capacity of approximately 142 mAh/g.

e) Electrochemical Behavior of P2-type Na.sub.0.67Co.sub.0.55Mn.sub.0.45O.sub.2

[0087] This example illustrates the electrochemical behavior of a P2-type layered Na.sub.0.67Co.sub.0.55Mn.sub.0.45O.sub.2 material as prepared in Example 1.

[0088] FIG. 14 displays the charge and discharge profiles of Cell 7. The charge and discharge were performed at 0.1 C between 2.0 and 4.4 V vs Li/Li.sup.+ at a temperature of 25° C. Cell 7 delivered a capacity of approximately 110 mAh/g.

f) Electrochemical Behavior of P2-type Na.sub.0.67Co.sub.0.5Mn.sub.0.5O.sub.2

[0089] This example illustrates the electrochemical behavior of a P2-type layered Na.sub.0.67Co.sub.0.5Mn.sub.0.5O.sub.2 material as prepared in Example 1.

[0090] FIG. 15 displays the charge and discharge profiles of Cell 8. The charge and discharge were performed at 0.1 C between 2.0 and 4.4 V vs Li/Li.sup.+ at a temperature of 25° C. Cell 8 delivered a capacity of approximately 114 mAh/g.

g) Electrochemical Behavior of P2-type Na.sub.0.67Co.sub.0.50Mn.sub.0.33Ti.sub.0.17O.sub.2

[0091] This example illustrates the electrochemical behavior of a P2-type layered Na.sub.0.67Co.sub.0.50Mn.sub.0.33Ti.sub.0.17O.sub.2 material as prepared in Example 1.

[0092] FIG. 16 displays the charge and discharge profiles of Cell 9. The charge and discharge were performed at 0.1 C between 2.0 and 4.5 V vs Li/Li.sup.+ at a temperature of 25° C. Cell 9 delivered a capacity of approximately 137 mAh/g.

h) Electrochemical Behavior of P2-type Na.sub.0.60MnO.sub.2

[0093] This example illustrates the electrochemical behavior of a P2-type layered Na.sub.0.60MnO.sub.2 material as prepared in Example 1.

[0094] FIG. 17 displays the charge and discharge profiles of Cell 10. The charge and discharge were performed at 0.1 C between 2.0 and 4.4 V vs Li/Li.sup.+ at a temperature of 25° C. Cell 10 delivered a capacity of approximately 73 mAh/g.

i) Electrochemical Behavior of O3-type NaNi.sub.0.4Co.sub.0.2Mn.sub.0.4O.sub.2

[0095] This example illustrates the electrochemical behavior of a O3-type layered NaNi.sub.0.4Co.sub.0.2Mn.sub.0.4O.sub.2 material as prepared in Example 1.

[0096] FIG. 18 displays the charge and discharge profiles of Cell 11. The charge and discharge were performed at 0.1 C between 2.0 and 4.4 V vs Li/Li.sup.+ at a temperature of 25° C. Cell 11 delivered a capacity of approximately 118 mAh/g.

[0097] FIG. 19 shows a graph representing the capacity (mAh/g) as a function of the number of cycles for Cell 11. The long cycling experiment was carried out at a constant charge/discharge current of 0.1 C. The results were recorded vs Li/Li.sup.+ at a temperature of 25° C. FIG. 19 shows a good capacity retention after 50 cycles.

[0098] Numerous modifications could be made to any of the embodiments described above without departing from the scope of the present invention as contemplated. The references, patents or scientific literature documents referred to in the present application are incorporated herein by reference in their entirety for all purposes.