STABILIZED LITHIUM, MANGANESE AB2O4 SPINEL FOR RECHARGEABLE LITHIUM ELECTROCHEMICAL SYSTEMS THROUGH A AND B SITE DOPING, METHOD OF PREPARING THE SAME, AND LI ELECTROCHEMICAL CELL CONTAINING THE SAME

Abstract

A process for preparing a stable Li.sub.xK.sub.yMn.sub.2-zMe.sub.zO.sub.4 is provided. The general formula of the potassium A site and Group VIII Period 4 (Fe, Co and Ni) B site modified lithium manganese-based AB.sub.2O.sub.4 spinel is Li.sub.xK.sub.yMn.sub.2-zMe.sub.zO.sub.4 where Me is Fe, Co, or Ni. In addition, a Li.sub.xK.sub.yMn.sub.2-zMe.sub.zO.sub.4 cathode material for electrochemical systems is provided. Furthermore, a lithium or lithium-ion rechargeable electrochemical cell is provided, incorporating the Li.sub.xK.sub.yMn.sub.2-zMe.sub.zO.sub.4 cathode material in a positive electrode.

Claims

1. A method of preparing a homogeneously dispersed potassium-modified lithium manganese-based Li.sub.xK.sub.yMn.sub.2-zMe.sub.zO.sub.4 spinel cathode material, the method comprising: mixing a manganese source and a Group VIII Period 4 source to form a first mixture; calcining the first mixture to produce a manganese mixed metal-based metal oxide; mixing the manganese mixed metal-based metal oxide, a lithium source, and a potassium source to produce a second mixture; and calcining the second mixture to produce the homogeneously dispersed potassium-modified lithium manganese-based Li.sub.xK.sub.yMn.sub.2-zMe.sub.zO.sub.4 spinel cathode material, wherein Me is selected from a group consisting of iron, cobalt, and nickel.

2. The method according to claim 1, wherein the lithium source is selected from a group consisting of lithium carbonate, lithium hydroxide, lithium oxide, and lithium peroxide, wherein the potassium source is selected from a group consisting of potassium carbonate, potassium hydroxide, potassium oxide, and potassium peroxide, and wherein the manganese source is selected from a group consisting of manganese acetate and manganese nitrate.

3. The method according to claim 1, wherein x ranges from 0.05 to 1.95, wherein y ranges from 0.05 to 0.2, and wherein z ranges from 0.005 to 0.6.

4. The method according to claim 1, further comprising: mixing ammonium hydroxide with the first mixture to form an intermediate gel; and drying the intermediate gel, wherein the manganese source is manganese acetate, and wherein the Group VIII Period 4 source is selected from a group consisting of iron acetate, cobalt acetate, and nickel acetate.

5. The method according to claim 4, wherein the first mixture is calcined at a time ranging from 0.5 hours to 2 hours and at a temperature ranging from 300 C. to 450 C., and wherein the second mixture is calcined at a time ranging from 12 hours to 72 hours and at a temperature ranging from 600 C. to 1200 C.

6. The method according to claim 1, further comprising: mixing the first mixture with a chelating agent to form an intermediate mixture; and calcining the intermediate mixture to produce an ash, wherein the manganese source is manganese nitrate, and wherein the Group VIII Period 4 source is selected from a group consisting of iron nitrate, cobalt nitrate, and nickel nitrate.

7. The method according to claim 6, wherein the intermediate mixture is calcined for a time ranging from 1 hour to 4 hours and at a temperature ranging from 350 C. to 800 C., and wherein the second mixture is calcined for a time ranging from 12 hours to 72 hours and at a temperature ranging from 600 C. to 1200 C.

8. A homogeneously dispersed, potassium-modified lithium manganese-based Li.sub.xK.sub.yMn.sub.2-zMe.sub.zO.sub.4 spinel cathode material, prepared by a process comprising: mixing a manganese source and a Group VIII Period 4 source to form a first mixture; calcining the first mixture to produce a manganese mixed metal-based metal oxide; mixing the manganese mixed metal-based metal oxide, a lithium source, and a potassium source to produce a second mixture; and calcining the second mixture to produce the homogeneously dispersed potassium-modified lithium manganese-based Li.sub.xK.sub.yMn.sub.2-zMe.sub.zO.sub.4 spinel cathode material, wherein Me is selected from a group consisting of iron, cobalt, and nickel.

9. The homogeneously dispersed, potassium-modified lithium manganese-based Li.sub.xK.sub.yMn.sub.2-zMe.sub.zO.sub.4 spinel cathode material cathode material according to claim 8, wherein the lithium source is selected from a group consisting of lithium carbonate, lithium hydroxide, lithium oxide, and lithium peroxide, wherein the potassium source is selected from a group consisting of potassium carbonate, potassium hydroxide, potassium oxide, and potassium peroxide, and wherein the manganese source is selected from a group consisting of manganese acetate and manganese nitrate.

10. The homogeneously dispersed, potassium-modified lithium manganese-based Li.sub.xK.sub.yMn.sub.2-zMe.sub.zO.sub.4 spinel cathode material cathode material according to claim 8, wherein x ranges from 0.05 to 1.95, wherein y ranges from 0.05 to 0.2, and wherein z ranges from 0.005 to 0.6.

11. The homogeneously dispersed, potassium-modified lithium manganese-based Li.sub.xK.sub.yMn.sub.2-zMe.sub.zO.sub.4 spinel cathode material cathode material according to claim 8, wherein the process further comprises: mixing ammonium hydroxide with the first mixture to form an intermediate gel; and drying the intermediate gel, wherein the manganese source is manganese acetate, and wherein the Group VIII Period 4 source is selected from a group consisting of iron acetate, cobalt acetate, and nickel acetate.

12. The homogeneously dispersed, potassium-modified lithium manganese-based Li.sub.xK.sub.yMn.sub.2-zMe.sub.zO.sub.4 spinel cathode material cathode material according to claim 11, wherein the process further comprises: calcining the first mixture for a time ranging from 0.5 hours to 2 hours and at a temperature ranging from 300 C. to 450 C.; and calcining the second mixture for a time ranging from 12 to 72 hours and at a temperature ranging from 600 C. to 1200 C.

13. The homogeneously dispersed, potassium-modified lithium manganese-based Li.sub.xK.sub.yMn.sub.2-zMe.sub.zO.sub.4 spinel cathode material cathode material according to claim 8, wherein the process further comprises: mixing the first mixture with a chelating agent to form an intermediate mixture; and calcining the intermediate mixture to produce an ash, wherein the manganese source is manganese nitrate, and wherein the Group VIII Period 4 source is selected from a group consisting of iron nitrate, cobalt nitrate, and nickel nitrate.

14. The homogeneously dispersed, potassium-modified lithium manganese-based Li.sub.xK.sub.yMn.sub.2-zMe.sub.zO.sub.4 spinel cathode material cathode material according to claim 13, wherein the process further comprises: calcining the intermediate mixture at a time ranging from 0.5 hours to 2 hours and at a temperature ranging from 300 C. to 450 C., and calcining the second mixture at a time ranging from 12 hours to 72 hours and at a temperature ranging from 600 C. to 1200 C.

15. A lithium electrochemical cell comprising: an anode; and a cathode comprising a homogeneously dispersed potassium-modified lithium manganese-based Li.sub.xK.sub.yMn.sub.2-zMe.sub.zO.sub.4 spinel cathode material prepared by a process comprising: mixing a manganese source and a Group VIII Period 4 source to form a first mixture; calcining the first mixture to produce a manganese mixed metal-based metal oxide; mixing the manganese mixed metal-based metal oxide, a lithium source, and a potassium source to produce a second mixture; and calcining the second mixture to produce the homogeneously dispersed potassium-modified lithium manganese-based Li.sub.xK.sub.yMn.sub.2-zMe.sub.zO.sub.4 spinel cathode material, wherein Me is selected from a group consisting of iron, cobalt, and nickel.

16. The lithium electrochemical cell according to claim 15, wherein the lithium source is selected from a group consisting of lithium carbonate, lithium hydroxide, lithium oxide, and lithium peroxide, wherein the potassium source is selected from a group consisting of potassium carbonate, potassium hydroxide, potassium oxide, and potassium peroxide, and wherein the manganese source is selected from a group consisting of manganese acetate and manganese nitrate.

17. The lithium electrochemical cell according to claim 15, wherein x ranges from 0.05 to 1.95, wherein y ranges from 0.05 to 0.2, and wherein z ranges from 0.005 to 0.6.

18. The lithium electrochemical cell according to claim 15, wherein the process further comprises: mixing ammonium hydroxide with the first mixture to form an intermediate gel; drying the intermediate gel; calcining the first mixture at a time ranging from 0.5 hours to 2 hours and at a temperature ranging from 300 C. to 450 C.; and calcining the second mixture at a time ranging from 12 to 72 hours and at a temperature ranging from 600 C. to 1200 C., wherein the manganese source is manganese acetate, and wherein the Group VIII Period 4 source is selected from a group consisting of iron acetate, cobalt acetate, and nickel acetate.

19. The lithium electrochemical cell according to claim 15, wherein the process further comprises: mixing the first mixture with a chelating agent to form an intermediate mixture; calcining the intermediate mixture at a time ranging from 0.5 hours to 2 hours and at a temperature ranging from 300 C. to 450 C. to produce an ash; and calcining the second mixture at a time ranging from 12 hours to 72 hours and at a temperature ranging from 600 C. to 1200 C., wherein the manganese source is manganese nitrate, and wherein the Group VIII Period 4 source is selected from a group consisting of iron nitrate, cobalt nitrate, and nickel nitrate.

20. The lithium electrochemical cell according to claim 15, wherein the cathode material further comprises a conductive carbon and a binder, wherein the conductive carbon is a compound selected from a group consisting of carbon black, graphite, carbon nanofibers, and carbon nanoparticles, and wherein the binder is a compound selected from the group consisting of polytetrafluoroethylene, polyvinylidene fluoride, and latex.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0024] The accompanying drawings, which are included to provide further understanding of the present disclosure, and are incorporated in and constitute a part of the specification, illustrate exemplary embodiments of the present disclosure, and together with the description serve to explain the principles of the present disclosure. The present disclosure will now be described further with reference to the accompanying drawings as follows:

[0025] FIG. 1 is a flowchart illustrating process steps in an exemplary embodiment of the present disclosure.

[0026] FIG. 2 is a flowchart illustrating process steps describing one aspect of the embodiment. These process steps include hydrothermal preparation of the Mn.sub.2-zMe.sub.zO.sub.x intermediate followed by a solid state reaction forming the desired Li.sub.xK.sub.yMn.sub.2-zMe.sub.zO.sub.4 material, where Me is Fe, Co or Ni.

[0027] FIG. 3 is a flowchart illustrating process steps in another aspect of the exemplary embodiment of the present disclosure. These process steps include glycine nitrate flame preparation of the Mn.sub.2-zMe.sub.zO.sub.x intermediate followed by a solid state reaction forming the desired Li.sub.xK.sub.yMn.sub.2-zMe.sub.zO.sub.4 material, where Me is Fe, Co or Ni.

[0028] FIG. 4 is a graph showing x-ray diffraction data for an exemplary formulation mixture according to exemplary embodiments of the present disclosure compared to the standard data for intensity and location for a LiMn.sub.2O.sub.4 spinel.

[0029] FIG. 5 is a graph showing x-ray fluorescence data for an exemplary formulation mixture according to exemplary embodiments of the present disclosure compared to known references K, Mn, Co, Ni, and Pd. For this graph, the traces represent z=0, Me=Co and Me=Ni.

[0030] FIG. 6 is a graph of differential specific capacity at a 2.0 mA charge and discharge rate illustrating a lithium cell containing stabilized lithium manganese-based AB.sub.2O.sub.4 spinel cathode with potassium doped A site and cobalt doped B site modifications according to an exemplary embodiment of the present disclosure.

[0031] FIG. 7 is a graph of charge and discharge curves at a 2.0 mA charge and discharge rate illustrating a lithium cell containing stabilized lithium manganese-based AB.sub.2O.sub.4 spinel cathode with potassium doped A site and cobalt doped B site modifications according to an exemplary embodiment of the present disclosure.

[0032] FIG. 8 is a graph of differential specific capacity at a 2.0 mA charge and discharge rate illustrating a lithium cell containing stabilized lithium manganese-based AB.sub.2O.sub.4 spinel cathode with potassium doped A site and cobalt doped B site modifications according to an exemplary embodiment of the present disclosure.

[0033] FIG. 9 is a graph of charge and discharge curves at a 2.0 mA charge and discharge rate illustrating a lithium cell containing stabilized lithium manganese-based AB.sub.2O.sub.4 spinel cathode with potassium doped A site and cobalt doped B site modifications according to an exemplary embodiment of the present disclosure.

[0034] FIG. 10 is a graph illustrating specific discharge capacity over 100 cycles for a lithium cell containing stabilized lithium manganese-based AB.sub.2O.sub.4 spinel cathode with potassium doped A site and cobalt doped B site modifications according to an exemplary embodiment of the present disclosure.

[0035] FIG. 11 is a graph of differential specific capacity at a 2.0 mA charge and discharge rate illustrating a lithium cell containing stabilized lithium manganese-based AB.sub.2O.sub.4 spinel cathode with potassium doped A site and cobalt doped B site modifications according to an exemplary embodiment of the present disclosure.

[0036] FIG. 12 is a graph of select discharge curves comparing varying discharge rates for a lithium cell containing stabilized lithium manganese-based AB.sub.2O.sub.4 spinel cathode with potassium doped A site and cobalt doped B site modifications according to an exemplary embodiment of the present disclosure.

[0037] FIG. 13 is a graph of differential specific capacity comparing varying discharge rates for a single lithium cell containing stabilized lithium manganese-based AB.sub.2O.sub.4 spinel cathode with potassium doped A site and cobalt doped B site modifications according to an exemplary embodiment of the present disclosure.

[0038] FIG. 14 is a graph illustrating capacity over 146 cycles for a lithium cell containing stabilized lithium manganese-based AB.sub.2O.sub.4 spinel cathode with potassium doped A site and cobalt doped B site modifications according to an exemplary embodiment of the present disclosure.

[0039] FIG. 15 is a graph of differential specific capacity at a 2.0 mA charge and discharge rate after high rate discharge cycles illustrating a lithium cell containing stabilized lithium manganese-based AB.sub.2O.sub.4 spinel cathode with potassium doped A site and cobalt doped B site modifications according to an exemplary embodiment of the present disclosure.

[0040] FIG. 16 is a graph illustrating the discharge/charge/discharge curve for cycle 147 and 148 for a lithium cell containing stabilized lithium manganese-based AB.sub.2O.sub.4 spinel cathode with potassium doped A site and cobalt doped B site modifications according to an exemplary embodiment of the present disclosure.

[0041] FIG. 17 is a graph illustrating the differential specific capacity at a 1.0 mA charge and discharge rate of a lithium cell containing stabilized lithium manganese-based AB.sub.2O.sub.4 spinel cathode with potassium doped A site and nickel doped B site modifications according to an exemplary embodiment of the present disclosure.

[0042] FIG. 18 is a graph of the charge and discharge curves for a 1.0 mA charge and discharge rate of a lithium cell containing stabilized lithium manganese-based AB.sub.2O.sub.4 spinel cathode with potassium doped A site and nickel doped B site modifications according to an exemplary embodiment of the present disclosure.

[0043] FIG. 19 is a graph illustrating the differential specific capacity at a 1.0 mA charge and discharge rate of a lithium cell containing stabilized lithium manganese-based AB.sub.2O.sub.4 spinel cathode with potassium doped A site and nickel doped B site modifications according to an exemplary embodiment of the present disclosure.

[0044] FIG. 20 is a graph of the charge and discharge curves for a 1.0 mA charge and discharge rate of a lithium cell containing stabilized lithium manganese-based AB.sub.2O.sub.4 spinel cathode with potassium doped A site and nickel doped B site modifications according to an exemplary embodiment of the present disclosure.

[0045] FIG. 21 is a graph illustrating the differential specific capacity at a 1.0 mA charge and discharge rate of a lithium cell containing stabilized lithium manganese-based AB.sub.2O.sub.4 spinel cathode with potassium doped A site and iron doped B site modifications according to an exemplary embodiment of the present disclosure.

[0046] FIG. 22 is a graph of the charge and discharge curves for a 1.0 mA charge and discharge rate of a lithium cell containing stabilized lithium manganese-based AB.sub.2O.sub.4 spinel cathode with potassium doped A site and iron doped B site modifications according to an exemplary embodiment of the present disclosure.

DETAILED DESCRIPTION

[0047] The present disclosure provides a method of preparing the aforementioned potassium A site and Group VIII Period 4 (Fe, Co and Ni) B site modified lithium manganese-based AB.sub.2O.sub.4 spinel cathode material via a multi-step method comprising an initial precursor synthesis of a manganese mixed metal oxide through hydrothermal synthesis or nitrate flame synthesis, followed by a solid state reaction with the precursor and alkali compounds.

[0048] In this embodiment, a stable lithium manganese-based AB.sub.2O.sub.4 spinel material is synthesized using a solid state synthesis process where a precursor mixed metal oxide is synthesized through a hydrothermal or a nitrate flame process and calcined, producing a Li.sub.xK.sub.yMn.sub.2-zMe.sub.zO.sub.4 where Me is Fe, Co or Ni, cathode material that may be employed as a positive electrode for lithium and lithium-ion rechargeable electrochemical cells and batteries. The general formula for the material is Li.sub.xK.sub.yMn.sub.2-zMe.sub.zO.sub.4 for lithium and lithium-ion electrochemical couples, where x=0.05 to 1.95, y=0.05 to 0.2, and z=0.005 to 0.6; or where x=0.75 to 1.25, y=0.0 to 0.25, and z=0.0 to 0.6; or where x=0.95 to 1.15, y=0.09 to 0.125, and z=0.0 to 0.6. Me is a Group VIII Period 4 element (iron, cobalt or nickel) and the reversible region for x for the Li/Li.sub.xK.sub.yMn.sub.2-zMe.sub.zO.sub.4 electrochemical couple ranges from 0.05 to 1.9.

[0049] One aspect of this embodiment includes dissolving manganese acetate and a Group VIII Period 4 element (iron, cobalt or nickel) acetate in water, initiating a hydrothermal synthesis process. Once dissolved, ammonium hydroxide is added to form a gel. The gel is then dried (which can be accomplished in a drying oven) and calcined in air at a temperature of at least 300 C. for a maximum of 2 hours. Suitable calcination temperatures and times include (but are not limited to) 300 C. to 450 C. (for 0.5 to 2 hours), from 350 C. to 450 C. (for 0.5 to 1 hour), or from 350 C. to 400 C. (for 1 to 2 hours). The results of the hydrothermal synthesis is a MnMeO.sub.x mixed metal oxide compound. The MnMeO.sub.x compound is then mixed with a lithium containing salt. Suitable lithium containing salts include, include (but are not limited to) lithium carbonate, lithium hydroxide, lithium oxide, and lithium peroxide, and a potassium containing salt. Suitable potassium containing salts include (but are not limited to) potassium carbonate, potassium hydroxide, potassium oxide, and potassium peroxide. This mixture is then calcined at a temperature of at least 600 C. for at least 12 hours to produce a potassium A site and Group VIII Period 4 (Fe, Co and Ni) B site modified lithium manganese-based AB.sub.2O.sub.4 spinel cathode material. Suitable calcination temperatures and times include (but are not limited to) 600 C. to 1200 C. (for 12 to 72 hours), from 800 C. to 1200 C. (for 12 to 48 hours), or from 600 C. to 800 C. (for 24 to 72 hours).

[0050] In another aspect of this embodiment, a method of preparing a homogeneous Li.sub.xK.sub.yMn.sub.2-zMe.sub.zO.sub.4 lithium manganese-based AB.sub.2O.sub.4 spinel cathode material includes dissolving the option of a nitrate of a Group VIII Period 4 element, and a manganese nitrate to form an aqueous solution. Then, the aqueous solution is mixed with a chelating agent to produce a mixture. Suitable chelating agents include (but are not limited to) glycine, cellulose, citric acid, a cellulose-citric acid mixture, and urea. The mixture is then heated to produce an ash, and the ash is ground. Then, the ground ash is calcined for a time period no greater than 4 hours at a temperature of at least 350 C. (for example, at 350 C. to 800 C. (for 1 to 4 hours), at 400 C. to 600 C. (for 1.5 to 3 hours), or at 500 C. to 600 C. (for 2 to 2.5 hours)) to produce the Group VIII Period 4 element-doped manganese oxide precursor, which is then mixed with a lithium containing salt and a potassium containing salt. This mixture is then calcined at at least 600 C. for at least 12 hours to produce a potassium A site and Group VIII Period 4 (Fe, Co and Ni) B site modified lithium manganese-based AB.sub.2O.sub.4 spinel cathode material. Suitable calcination temperatures and times include (but are not limited to) 600 C. to 1200 C. (for 12 to 72 hours), from 800 C. to 1200 C. (for 12 to 48 hours), or from 600 C. to 800 C. (for 24 to 72 hours).

[0051] FIG. 1 is a flowchart illustrating process steps in an exemplary embodiment of the present disclosure. More specifically, FIG. 1 shows exemplary steps according to the present disclosure for the preparation of Li.sub.xK.sub.yMn.sub.2-zMe.sub.zO.sub.4, where Me is Fe, Co or Ni and where an intermediate manganese mixed metal based metal oxide is formulated.

[0052] In Step S11, a manganese source and an iron, cobalt, or nickel source are dissolved in water. In Step S12, the water in the mixture is evaporated. In Step S13, the residual is ground to form a product. In Step S14, product is calcined to form the mixed metal based metal oxide, MnMe.sub.zO.sub.d. In Step S15, the MnMe.sub.zO.sub.d is mixed with a potassium source such as potassium carbonate, potassium hydroxide, potassium peroxide, or potassium oxide, and with a lithium source such as lithium carbonate, lithium hydroxide, lithium peroxide, or lithium oxide. The mixture is then ground in Step S16. In Step S17 the material is calcined to form the Li.sub.xK.sub.yMn.sub.2-zMe.sub.zO.sub.4 in Step S18.

[0053] FIG. 2 describes one aspect of an embodiment of the process. In this aspect, the intermediate manganese mixed metal based metal oxide is formulated through a hydrothermal process, followed by a solid state milling and calcining process. In this aspect, in Step S11, the manganese source referred to in S11 of FIG. 1 is manganese acetate. The iron, cobalt, or nickel source is iron acetate, cobalt acetate, or nickel acetate. The manganese source and the iron, cobalt, or nickel source may be reacted in stoichiometric ratio. The water used to dissolve the reactants can be distilled water. Ammonium hydroxide is added in Step S11a to the aqueous metal acetate solution to form a gel.

[0054] In Step S12, the water is evaporated, drying the gel to form a residual. In Step S13, the residual is ground. In Step S14, the ground residual is calcined in air at a temperature of at least 300 C. for a maximum of 2 hours to form a manganese mixed metal oxide. Suitable calcination temperatures and times include (but are not limited to) calcining at 300 C. to 450 C. (for 0.5 to 2 hours), 350 C. to 450 C. (for 0.5 to 1 hour), or 350 C. to 400 C. (for 1 to 2 hours).

[0055] In Step S15, the resultant manganese mixed metal oxide from Step S14 is mixed with lithium hydroxide and potassium hydroxide. Lithium carbonate, lithium oxide, or lithium peroxide may be substituted for lithium hydroxide in Step S15. Potassium carbonate, potassium oxide, or potassium peroxide can be substituted for potassium hydroxide in Step S15. In Step S16, the mixture is ground. A high energy mixer mill may be used to accomplish the grinding step. The ground mixture from Step S16 is then calcined in Step S17 in a furnace at at least 600 C. for at least 12 hours. Alternatively, suitable calcination temperatures and times include calcining at 600 C. to 1200 C. (for 12 to 72 hours), at 800 C. to 1200 C. (for 12 to 48 hours), or at 600 C. to 800 C. (for 24 to 72 hours).

[0056] In Step S18, the resulting A and B site modified Li.sub.xK.sub.yMn.sub.2-zMe.sub.zO.sub.4 yields material with x ranging from 0.05 to 1.95, y=0.05 to 0.2, and z=0.005 to 0.6. Alternative ranges include x=0.75 to 1.25, y=0.0 to 0.25, and z=0.0 to 0.6, as well as x=0.95 to 1.15, y=0.09 to 0.125, and z=0.0 to 0.6.

[0057] FIG. 3 describes another aspect of an embodiment of this process. In this aspect, the intermediate manganese mixed metal based metal oxide is formulated via a method comprising an initial flame synthesis process producing an intermediate mixed metal oxide followed by Steps S15-S18 of FIG. 1, which are described above. In this embodiment, in Step S11, the manganese source is manganese nitrate; the iron, cobalt, or nickel source is iron nitrate, cobalt nitrate, or nickel nitrate; and a chelating agent is added to the aqueous mixture. Suitable chelating agents include (but are not limited to) glycine, cellulose, citric acid, a cellulose-citric acid mixture, and urea. In Step S12, the water in the mixture is evaporated to form a gel, the gel is ignited in Step S12a to form a residual. In Step S13, the residual is ground. In Step S14, the ground dried ash is calcined in air for a time period no greater than 4 hours at a temperature of at least 350 C. (for example, at 350 C. to 800 C. (for 1 to 4 hours), at 400 C. to 600 C. (for 1.5 to 3 hours), or at 500 C. to 600 C. (for 2 to 2.5 hours)) to form a manganese mixed metal oxide. Steps S15-S18 of FIG. 1 (described above) are then followed to yield the resulting A and B site modified Li.sub.xK.sub.yMn.sub.2-zMe.sub.zO.sub.4 yields material with x ranging from 0.05 to 1.95, y=0.05 to 0.2, and z=0.005 to 0.6. Alternative ranges include x=0.75 to 1.25, y=0.0 to 0.25, and z=0.0 to 0.6, as well as x=0.95 to 1.15, y=0.09 to 0.125, and z=0.0 to 0.6.

[0058] FIG. 4 shows the X-ray diffraction pattern of exemplary formulation mixtures according to exemplary embodiments of the present disclosure compared to the standard data for intensity and location from the International Center for Diffraction Data for LiMn.sub.2O.sub.4 spinel (JCPDS catalog number 018-0736). The figures show the X-ray diffraction pattern for Li.sub.xK.sub.yMn.sub.2-zMe.sub.zO.sub.4 material, where Me is Fe, Co or Ni, according to the present disclosure.

[0059] FIG. 5 shows the X-ray fluorescence pattern of exemplary formulation mixtures according to exemplary embodiments of the present disclosure compared to reference standards K, Mn, Co, Ni, and Pd. The figure shows the X-ray diffraction pattern for Li.sub.xK.sub.yMn.sub.2-zMe.sub.zO.sub.4 where Me is absent, Co or Ni material according to the present disclosure.

[0060] FIGS. 6 and 7 show the differential capacity and galvanostatic (charge/discharge) plots for lithium electrochemical cell 1, which was fabricated with Li.sub.xK.sub.yMn.sub.2-zCo.sub.zO.sub.4 where x=1, y=0.1, and z=0.2 synthesized using the method described in the present disclosure. In lithium electrochemical cells, the active material is bound to an aluminum current collector with either Teflon or pVdF mixed with conductive carbon. The conductive carbon serves as an aid for electron transfer. The experimental cells were composed of a lithium anode separated from a Teflon bonded cathode with a nonwoven glass separator. Other suitable anode materials include, but are not limited to, lithium metal, lithium aluminum alloy, lithium silicon alloy, graphite and graphite derivatives, tin oxide, and lithium phosphate. The cathode was fabricated by combining Li.sub.xK.sub.yMn.sub.2-zMe.sub.zO.sub.4, carbon, and Teflon in a 75:15:10 weight percent basis, respectively. Suitable conductive carbon materials include, but are not limited to, conductive carbon black (commercially available from various sources, including Cabot Corporation, under the trade name VULCAN XC72 or VULCAN XC72R), graphite, carbon nanofibers, and carbon nanoparticles (commercially available under the trade name PURE BLACK, manufactured by Superior Graphite Co.). Suitable binders include, but are not limited to, polytetrafluoroethylene (commercially available under the trade name TEFLON, manufactured by DuPont), polyvinylidene fluoride (PVDF), and latex. The cathode may contain by weight 40%-95% of Li.sub.xK.sub.yMn.sub.2-zMe.sub.zO.sub.4, 1%-40% of conductive carbon, and 1%-20% binder.

[0061] The cathode mix was rolled to 0.06 cm and dried in a vacuum oven. The cathode mass was approximately 0.1 g. The cathode and 0.075 cm thick lithium foil was cut using a 1.58 cm diameter (1.96 cm.sup.2) hole punch. A 0.01 cm nonwoven glass separator was used for the separator and as a wick. The electrolyte used was 1 M LiPF.sub.6 in proportional mixtures of dimethyl carbonate and ethylene carbonate. Other suitable electrolytes include, but are not limited to, lithium hexafluoroarsenate monohydrate (LiAsF.sub.6), lithium perchlorate (LiClO.sub.4), lithium tetrafluoroborate (LiBF.sub.4), and lithium triflate (LiCF.sub.3SO.sub.3). The cells were cycled with an ARBIN Model MSTAT4 Battery Test System. The charge profile consisted of a constant current charge at 1.0 or 2.0 mA to 4.5, 4.75, 5.0 or 5.2 volts. The cells were discharged at 1.0 or 2.0 mA to 2.0, 2.25 or 3.5 volts. A rest period of 15 minutes between cycles allowed for the cells to equilibrate. Prior to cycling, cell impedance was recorded with a Solartron, SI1260 Frequency Response Analyzer with a Solartron, SI1287 Electrochemical Interface using Scribner Associates, Inc., ZPlot and ZView software. The data is used as a quality control tool and for comparative use between variant chemistries.

[0062] The cell was cycled between 4.5 to 3.5 V at a charge and discharge rate of 2 mA. Differential capacity traces provide information regarding the underlying thermodynamics and kinetics of an electrochemical cell. The differential capacity data use galvanostatic control of the electrochemical system being tested, and plots the capacity increase (charge) or decrease (discharge) as a function of potential. FIG. 6 illustrates the reproducible thermodynamics of the Li.sub.xK.sub.yMn.sub.2-zCo.sub.zO.sub.4 chemistry where x=1, y=0.1, and z=0.2 over repeated cycles. FIG. 7 illustrates a select charge and discharge curve.

[0063] FIGS. 8 and 9 show the differential capacity and galvanostatic (charge/discharge) plots for lithium electrochemical cell 2, which was fabricated with Li.sub.xK.sub.yMn.sub.2-zCo.sub.zO.sub.4 where x=1, y=0.1, and z=0.1 synthesized using the method described in the present disclosure. The cell was cycled between 4.5 to 3.5 V at a charge and discharge rate of 2 mA. Differential capacity traces provide information regarding the underlying thermodynamics and kinetics of an electrochemical cell. The differential capacity data uses galvanostatic control of the electrochemical system being tested, and plots the capacity increase (charge) or decrease (discharge) as a function of potential. FIG. 8 illustrates the reproducible thermodynamics of the Li.sub.xK.sub.yMn.sub.2-zCo.sub.zO.sub.4 chemistry where x=1, y=0.1, and z=0.1 over repeated cycles. FIG. 9 illustrates a select charge and discharge curve.

[0064] FIGS. 10 and 11 show the discharge capacity and specific differential capacity plots for lithium electrochemical cell 3, which was fabricated with Li.sub.xK.sub.yMn.sub.2-zCo.sub.zO.sub.4 where x=1, y=0.1, and z=0.2 synthesized using the method described in the present disclosure. FIG. 10 shows exemplary discharge capacities through 110 cycles with select cycle life traces displayed in FIG. 11 for lithium electrochemical cells fabricated with Li.sub.xK.sub.yMn.sub.2-zCo.sub.zO.sub.4 where x=1, y=0.1, and z=0.2 synthesized using the method described in the present disclosure. All cycles were cycled between 4.5 V to 3.5 V at a charge and discharge rate of 2 mA. This chart demonstrates excellent capacity retention through 110 cycles.

[0065] FIG. 11 is a differential capacity graph through 100 cycles illustrating exemplary cycle life traces for cycles 20, 40, 60, 80, and 100 for lithium electrochemical cells fabricated with Li.sub.xK.sub.yMn.sub.2-zCo.sub.zO.sub.4 where x=1, y=0.1, and z=0.2 synthesized using the method described in the present disclosure. All cells were cycled between 4.5 V to 3.5 V at a charge and discharge rate of 2.0 mA. Differential capacity traces provide information regarding the underlying thermodynamics and kinetics of an electrochemical cell. The differential capacity data uses galvanostatic control of the electrochemical system being tested, and plots the capacity increase (charge) or decrease (discharge) as a function of potential. This figure shows the stability of the Li.sub.xK.sub.yMn.sub.2-zCo.sub.zO.sub.4 chemistry where x=1, y=0.1, and z=0.2, as the measured differential capacity at each 20 cycle increment remains consistent.

[0066] FIGS. 12 and 13 show discharge capacity and select differential capacity traces for lithium electrochemical cells fabricated with Li.sub.xK.sub.yMn.sub.2-zCo.sub.zO.sub.4 where x=1, y=0.1, and z=0.2 synthesized using the method described in the present disclosure. FIG. 12 shows exemplary discharge capacities through 146 cycles with select differential capacity curves displayed in FIG. 13. Cells were cycled between 4.5 V and 3.5 volts for discharge currents between 2.0 mA and 8.0 mA and 4.5 and 3.0 for discharge currents greater than 8.0 mA. Cycles 1-10 were charged and discharged at 2.0 mA, cycles 11-30 were charged at 2.0 mA and discharged at 4.0 mA, cycles 31-36 were charged at 2.0 mA and discharged at 8.0 mA, cycles 37-46 were charged at 2.0 mA and discharged at 12.0 mA, cycles 57-66 were charged and discharged at 2.0 mA, cycles 67-76 were charged at 2.0 mA and discharged at 12.0 mA, cycles 77-86 were charged and discharged at 2.0 mA, cycles 87-96 were charged at 2.0 mA and discharged at 16.0 mA, cycles 97-106 were charged and discharged at 2.0 mA, cycles 107-116 were charged at 2.0 mA and discharged at 20.0 mA, cycles 117-126 were charged and discharged at 2.0 mA, cycles 127-136 were charged at 2.0 mA and discharged at 20.0 mA, cycles 137-146 were charged and discharged at 2.0 mA. FIG. 12 shows that the cells retained their full capacity even after high rate discharges of 12.0, 16.0, and 20.0 mA. FIG. 13 illustrates the maintenance of the base thermodynamics of the cell after these high rate discharges, demonstrating the stability of the Li.sub.xK.sub.yMn.sub.2-zCo.sub.zO.sub.4 chemistry where x=1, y=0.1, and z=0.2, as the measured differential capacity after each high rate discharge remains consistent.

[0067] FIGS. 14 and 15 show discharge plots and differential capacity plots for incremental increases in discharge rate for electrochemical cell 4 with Li.sub.xK.sub.yMn.sub.2-zCo.sub.zO.sub.4 where x=1, y=0.1, and z=0.2 synthesized using the method described in the present disclosure. All cells are cycled between 4.5 V and 3.5 V with a constant charge rate of 2.0 mA, and discharge rates of 2.0 mA, 4.0 mA, 8.0 mA, 12.0 mA, 16.0 mA, and 20.0 mA. FIG. 14 shows the achieved discharge capacity at the various rates and FIG. 15 shows the specific differential capacity of the same electrochemical cell with Li.sub.xK.sub.yMn.sub.2-zCo.sub.zO.sub.4 where x=1, y=0.1, and z=0.2, where the charge portion of the chart demonstrates the integrity of the thermodynamics of the cathode material.

[0068] FIG. 16 shows the galvanostatic charge and discharge curve for an exemplary electrochemical cell with Li.sub.xK.sub.yMn.sub.2-zCo.sub.zO.sub.4 where x=1, y=0.1, and z=0.2 synthesized using the method described in the present disclosure. The cell was cycled between 4.5 V to 3.5 V at 2 mA through cycle 146 according to the procedure outlined in FIG. 14. In cycle 147, the cell was discharged down to 2.5 V to demonstrate that the spinel material exhibits deep discharge capability as a result of the modifications with no negative effect on the cell after charged and discharged between 4.5 V and 3.5 V in cycle 148. The deep discharge to 2.5 V is shown achieving a 57% increase in capacity as compared to the 4.5 to 3.5 V discharge.

[0069] FIGS. 17 and 18 show the differential capacity and galvanostatic (charge/discharge) plots for lithium electrochemical cell 5, which was fabricated with Li.sub.xK.sub.yMn.sub.2-zNi.sub.zO.sub.4 where x=1, y=0.1, and z=0.2 synthesized using the method described in the present disclosure. The cell was cycled between 5.0 to 3.5 V at a charge and discharge rate of 1.0 mA. Differential capacity traces provide information regarding the underlying thermodynamics and kinetics of an electrochemical cell. The differential capacity data uses galvanostatic control of the electrochemical system being tested, and plots the capacity increase (charge) or decrease (discharge) as a function of potential. FIG. 17 illustrates the reproducible thermodynamics of the Li.sub.xK.sub.yMn.sub.2-zNi.sub.zO.sub.4 chemistry where x=1, y=0.1, and z=0.2 over repeated cycles. FIG. 18 illustrates a select charge and discharge curve, which shows an added high voltage thermodynamic plateau. This is a direct result of the nickel doped B site modification, and percentages of high vs. low voltage of the cell can be tailored by nickel content.

[0070] FIGS. 19 and 20 show the differential capacity and galvanostatic (charge/discharge) plots for lithium electrochemical cell 1, which was fabricated with Li.sub.xK.sub.yMn.sub.2-zNi.sub.zO.sub.4 where x=1, y=0.1, and z=0.4 synthesized using the method described in the present disclosure. The cell was cycled between 5.0 to 3.5 Vat a charge and discharge rate of 1.0 mA. Differential capacity traces provide information regarding the underlying thermodynamics and kinetics of an electrochemical cell. The differential capacity data uses galvanostatic control of the electrochemical system being tested, and plots the capacity increase (charge) or decrease (discharge) as a function of potential. FIG. 19 illustrates the reproducible thermodynamics of the Li.sub.xK.sub.yMn.sub.2-zNi.sub.zO.sub.4 chemistry where x=1, y=0.1, and z=0.4 over repeated cycles. FIG. 20 illustrates a select charge and discharge curve, which shows an added high voltage thermodynamic plateau. This is a direct result of the nickel doped B site modification, and percentages of high vs. low voltage of the cell can be tailored by nickel content.

[0071] FIGS. 21 and 22 show the differential capacity and galvanostatic (charge/discharge) plots for lithium electrochemical cells fabricated with Li.sub.xK.sub.yMn.sub.2-zFe.sub.zO.sub.4 where x=1, y=0.1, and z=0.24 synthesized using the method described in the present disclosure. The cell was cycled between 5.25 to 3.5 V at a charge and discharge rate of 1.0 mA. Differential capacity traces provide information regarding the underlying thermodynamics and kinetics of an electrochemical cell. The differential capacity data uses galvanostatic control of the electrochemical system being tested, and plots the capacity increase (charge) or decrease (discharge) as a function of potential. FIG. 21 illustrates the reproducible thermodynamics of the Li.sub.xK.sub.yMn.sub.2-zFe.sub.zO.sub.4 chemistry where x=1, y=0.1, and z=0.24 over repeated cycles. FIG. 22 illustrates a select charge and discharge curve, which shows an added high voltage thermodynamic plateau. This is a direct result of the nickel doped B site modification, and percentages of high vs. low voltage of the cell can be tailored by iron content.

[0072] The above disclosed subject matter is to be considered illustrative, and not restrictive, and the appended claims are intended to cover all such modifications, enhancements, and other embodiments which fall within the true spirit and scope of the present disclosure. Thus, to the maximum extent allowed by law, the scope of the present disclosure is to be determined by the broadest permissible interpretation of the following claims and their equivalents, and shall not be restricted or limited by the foregoing detailed description.