Abstract
A process for preparing a stable Li.sub.xMn.sub.2-yMe.sub.yO.sub.4-zCl.sub.z material with a MO.sub.b or MMn.sub.aO.sub.b charge transfer catalyst coating is provided, where Me is Fe, Co, or Ni and M is Bi, As, or Sb. In addition, a Li.sub.xMn.sub.2-yMe.sub.yO.sub.4-zCl.sub.z material with a MO.sub.b or MMn.sub.aO.sub.b charge transfer catalyst coating is provided. Furthermore, a lithium or lithium ion rechargeable electrochemical cell is provided, which includes a cathode material (in a positive electrode) containing a Li.sub.xMn.sub.2-yMe.sub.yO.sub.4-zCl.sub.z material with a MO.sub.b or MMn.sub.aO.sub.b charge transfer catalyst coating.
Claims
1. A method of preparing a coated homogeneously dispersed chlorine-modified lithium manganese-based AB.sub.2O.sub.4 spinel cathode material, the method comprising: mixing a lithium source, a chlorine source, and a manganese source to form a first mixture; calcining the first mixture to produce a homogeneously dispersed chlorine-modified lithium manganese-based AB.sub.2O.sub.4 spinel cathode material; mixing the homogeneously dispersed chlorine-modified lithium manganese-based AB.sub.2O.sub.4 spinel cathode material, a charge transfer catalyst salt, and a chelating agent to produce a second mixture; heating the second mixture to produce a gel; igniting the gel to form an ash; and calcining the ash to produce the coated homogeneously dispersed chlorine-modified lithium manganese-based AB.sub.2O.sub.4 spinel cathode material comprising a charge transfer catalyst coating, wherein the charged transfer catalyst coating comprises a compound that is selected from a group consisting of MO.sub.b and MMn.sub.aO.sub.b, and wherein M is selected from a group consisting of bismuth, arsenic, and antimony.
2. The method according to claim 1, wherein the lithium source is selected from a group consisting of lithium carbonate, lithium hydroxide, lithium oxide, lithium peroxide, and lithium nitrate, wherein the chlorine source is selected from a group consisting of lithium perchlorate, lithium chloride, manganese chloride, iron chloride, cobalt chloride, and nickel chloride, wherein the manganese source is selected from the group consisting of manganese oxide, (MnMe.sub.f)O.sub.2, (MnMe.sub.f).sub.2O.sub.3, (MnMe.sub.f).sub.3O.sub.4, (MnMe.sub.f)O, and manganese nitrate, and wherein Me is selected from a group consisting of iron, cobalt, and nickel, and the ratio of Mn to Me is 1 to 0.0-0.43.
3. The method according to claim 1, wherein a ranges from 0 to 10.
4. The method according to claim 1, wherein b ranges from 0 to 22.
5. The method according to claim 1, further comprising: heating the first mixture to form an intermediate gel, and igniting the intermediate gel, wherein the first mixing step further comprises mixing a Group VIII Period 4 element source and the chelating agent.
6. The method according to claim 1, wherein the calcining steps comprise calcining the first mixture at 350° C. to 800° C. for 1 to 4 hours and calcining the ash at 350° C. to 800° C. for 1 to 4 hours.
7. The method according to claim 1, wherein the charge transfer catalyst salt is a compound selected from a group consisting of bismuth nitrate, arsenic nitrate, and antimony nitrate, and wherein the chelating agent is a compound selected from a group consisting of glycine, cellulose, citric acid, a cellulose-citric acid mixture, and urea.
8. The method according to claim 5, wherein the Group VIII Period 4 element source is selected from a group consisting of iron nitrate, cobalt nitrate, and nickel nitrate.
9. A homogeneously dispersed, chlorine-modified lithium manganese-based AB.sub.2O.sub.4 spinel cathode material comprising: Li.sub.xMn.sub.2-yMe.sub.yO.sub.4-zCl.sub.z, and a charge transfer catalyst coating comprising a compound that is selected from a group consisting of MO.sub.b and MMn.sub.aO.sub.b, wherein Me is selected from a group consisting of iron, cobalt, and nickel, wherein M is selected from a group consisting of bismuth, arsenic, and antimony, and wherein the Li.sub.xMn.sub.2-yMe.sub.yO.sub.4-zCl.sub.z is O-site modified.
10. The homogeneously dispersed, chlorine-modified lithium manganese-based AB.sub.2O.sub.4 spinel cathode material cathode material according to claim 9, wherein x ranges from 0.05 to 1.9, and wherein z ranges from 0.005 to 0.25.
11. The homogeneously dispersed, chlorine-modified lithium manganese-based AB.sub.2O.sub.4 spinel cathode material according to claim 10, wherein y ranges from 0.005 to 0.6, and wherein the Li.sub.xMn.sub.2-yMe.sub.yO.sub.4-zCl.sub.z is B-site modified.
12. The homogeneously dispersed, chlorine-modified lithium manganese-based AB.sub.2O.sub.4 spinel cathode material according to claim 9, wherein a mole percentage of the charge transfer catalyst coating ranges from 0.5 mole percent to 25 mole percent.
13. The homogeneously dispersed, chlorine-modified lithium manganese-based AB.sub.2O.sub.4 spinel cathode material according to claim 9, wherein a ranges from 0 to 10.
14. The homogeneously dispersed, chlorine-modified lithium manganese-based AB.sub.2O.sub.4 spinel cathode material according to claim 9, wherein b ranges from 0 to 22.
15. A lithium electrochemical cell comprising: an anode; and a cathode comprising a homogeneously dispersed chlorine-modified lithium manganese-based AB.sub.2O.sub.4 spinel cathode material comprising: Li.sub.xMn.sub.2-yMe.sub.yO.sub.4-zCl.sub.z; and a charge transfer catalyst coating comprising a compound that is selected from a group consisting of MO.sub.b and MMn.sub.aO.sub.b, wherein Me is selected from a group consisting of iron, cobalt, and nickel, wherein M is selected from a group consisting of bismuth, arsenic, and antimony, and wherein the Li.sub.xMn.sub.2-yMe.sub.yO.sub.4-zCl.sub.z is O-site modified.
16. The lithium electrochemical cell according to claim 15, wherein x ranges from 0.05 to 1.9, and wherein z ranges from 0.005 to 0.25.
17. The lithium electrochemical cell according to claim 15, wherein y ranges from 0.005 to 0.6, and wherein the Li.sub.xMn.sub.2-yMe.sub.yO.sub.4-zCl.sub.z is B-site modified.
18. The lithium electrochemical cell according to claim 15, wherein a mole percentage of the charge transfer catalyst coating ranges from 0.5 mole percent to 25 mole percent.
19. The electrochemical cell according to claim 15, wherein a ranges from 0 to 10.
20. The electrochemical cell according to claim 15, wherein b ranges from 0 to 22.
Description
BRIEF DESCRIPTION OF THE DRAWINGS
[0022] 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:
[0023] FIG. 1 is a flowchart illustrating process steps in an exemplary embodiment of the present disclosure, which yields a charge transfer catalyst coated chlorine “O” site modified AB.sub.2O.sub.4 spinel material.
[0024] FIG. 2 is a flowchart illustrating process steps in an exemplary embodiment of the present disclosure, which yields a charge transfer catalyst coated “B” and “O” site modified AB.sub.2O.sub.4 spinel material.
[0025] FIG. 3 is a graph showing x-ray diffraction data for an exemplary formulation mixture according to exemplary embodiments of the present disclosure compared to an undoped spinel material used as a reference standard.
[0026] FIG. 4 is a graph showing x-ray diffraction data for a narrow region for an exemplary formulation mixture according to exemplary embodiments of the present disclosure, compared to LiMn.sub.2O.sub.4 and Bi.sub.2Mn.sub.4O.sub.10 as reference standards.
[0027] 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 Si, P, S, Bi, Cl, Pd, and Mn as reference standards.
[0028] FIG. 6 is a graph showing x-ray fluorescence data for an exemplary formulation mixture according to exemplary embodiments of the present disclosure, compared to Si, P, S, Bi, Cl, Pd, and Mn as reference standards.
[0029] FIG. 7 is a graph showing thermogravimetric analysis results for an exemplary formulation mixture according to exemplary embodiments of the present disclosure.
[0030] FIG. 8 is a backscattered scanning electron microscope (SEM) image of the particles of an exemplary formulation mixture according to exemplary embodiments of the present disclosure.
[0031] FIG. 9 is a graph illustrating specific discharge capacity over 500 cycles for a lithium cell containing a charge transfer catalyst coated “O” site modified lithium manganese-based AB.sub.2O.sub.4 spinel cathode material according to an exemplary embodiment of the present disclosure.
[0032] FIG. 10 is a graph showing discharge capacity over 600 cycles for a lithium cell containing a charge transfer catalyst coated “O” site modified lithium manganese-based AB.sub.2O.sub.4 spinel cathode material according to an exemplary embodiment of the present disclosure.
[0033] FIG. 11 is a graph illustrating the charge and discharge curves for cycles 25, 505, and 565 for a lithium cell containing a charge transfer catalyst coated “O” site modified lithium manganese-based AB.sub.2O.sub.4 spinel cathode material according to an exemplary embodiment of the present disclosure.
[0034] FIG. 12 is a graph showing discharge capacity to 225 cycles comparing two lithium cells, one containing a Li.sub.xMn.sub.2O.sub.4 spinel and another containing a charge transfer catalyst coated “O” site modified lithium manganese-based AB.sub.2O.sub.4 spinel cathode material according to an exemplary embodiment of the present disclosure.
[0035] FIG. 13 is a graph of differential capacity comparing three lithium cells, one containing a Li.sub.xMn.sub.2O.sub.4 spinel, another containing an “O” site modified lithium manganese-based AB.sub.2O.sub.4 spinel cathode material, and a third containing a charge transfer catalyst coated “O” site modified lithium manganese-based AB.sub.2O.sub.4 spinel cathode material according to an exemplary embodiment of the present disclosure.
[0036] FIG. 14 is a bar graph illustrating the percent of original discharge capacity at cycle 150 versus cycle 5 for five different lithium cells, one containing an “O” site modified lithium manganese-based AB.sub.2O.sub.4 spinel cathode material, one containing Li.sub.xMn.sub.2-yMe.sub.yO.sub.4-zCl.sub.z, where Me is Fe, Co, or Ni, with X mol % MO.sub.b or MMn.sub.aO.sub.b coating cathode material according to an exemplary embodiment of the present disclosure, and the other three containing a charge transfer catalyst coated “O” site modified lithium manganese-based AB.sub.2O.sub.4 spinel cathode material according to an exemplary embodiment of the present disclosure.
[0037] FIG. 15 is a bar graph illustrating the percent of original discharge capacity at cycle 140 versus cycle 5 for four different lithium cells, each containing varying mole percentages of the MO.sub.b or MMn.sub.aO.sub.b coating.
[0038] FIG. 16 is a graph showing the discharge capacity over 150 cycles for three lithium cells of the same chemistry containing Li.sub.xMn.sub.2-yMe.sub.yO.sub.4-zCl.sub.z, where Me is Fe, Co, or Ni, with X mol % MO.sub.b or MMn.sub.aO.sub.b coating cathode material according to an exemplary embodiment of the present disclosure.
[0039] FIG. 17 is a graph illustrating the charge/discharge curve comparison between cycle 5 and cycle 145 for lithium cell 1 containing Li.sub.xMn.sub.2-yMe.sub.yO.sub.4-zCl.sub.z, where Me is Fe, Co, or Ni, with X mol % MO.sub.b or MMn.sub.aO.sub.b coating cathode material according to an exemplary embodiment of the present disclosure.
[0040] FIG. 18 is a graph illustrating the charge/discharge curve comparison between cycle 5 and cycle 145 for lithium cell 2 containing Li.sub.xMn.sub.2-yMe.sub.yO.sub.4-zCl.sub.z, where Me is Fe, Co, or Ni, with X mol % MO.sub.b or MMn.sub.aO.sub.b coating cathode material according to an exemplary embodiment of the present disclosure.
[0041] FIG. 19 is a graph illustrating the charge/discharge curve comparison between cycle 5 and cycle 145 for lithium cell 3 containing Li.sub.xMn.sub.2-yMe.sub.yO.sub.4-zCl.sub.z, where Me is Fe, Co, or Ni, with X mol % MO.sub.b or MMn.sub.aO.sub.b coating cathode material according to an exemplary embodiment of the present disclosure.
[0042] FIG. 20 is a graph illustrating the charge/discharge curve comparison between cycle 5 and cycle 220 for lithium cell 4 containing a charge transfer catalyst coated “O” site modified lithium manganese-based AB.sub.2O.sub.4 spinel cathode material according to an exemplary embodiment of the present disclosure.
[0043] FIG. 21 is a graph illustrating the charge/discharge curve comparison between cycle 5 and cycle 220 for lithium cell 5 containing a charge transfer catalyst coated “O” site modified lithium manganese-based AB.sub.2O.sub.4 spinel cathode material according to an exemplary embodiment of the present disclosure.
[0044] FIG. 22 is a graph illustrating the charge/discharge curve comparison between cycle 5 and cycle 220 for lithium cell 6 containing a charge transfer catalyst coated “O” site modified lithium manganese-based AB.sub.2O.sub.4 spinel cathode material according to an exemplary embodiment of the present disclosure.
[0045] FIG. 23 is a graph illustrating the discharge curve comparison between cycle 5 and cycle 155 for a lithium cell containing a charge transfer catalyst coated “O” site modified lithium manganese-based AB.sub.2O.sub.4 spinel cathode material according to an exemplary embodiment of the present disclosure.
[0046] FIG. 24 is a graph illustrating the discharge/charge/discharge curve for cycle 152 and cycle 153 for a lithium cell containing a charge transfer catalyst coated “O” site modified lithium manganese-based AB.sub.2O.sub.4 spinel cathode material according to an exemplary embodiment of the present disclosure.
[0047] FIG. 25 is a graph showing the comparison of hysteresis upon charge and discharge of two lithium cells, one containing an “O” site modified lithium manganese-based AB.sub.2O.sub.4 spinel cathode material, and another containing a charge transfer catalyst coated “O” site modified lithium manganese-based AB.sub.2O.sub.4 spinel cathode material according to an exemplary embodiment of the present disclosure.
[0048] FIG. 26 is a graph showing the comparison of electrochemical impedance spectroscopy (EIS) of two lithium cells, one containing an “O” site modified lithium manganese-based AB.sub.2O.sub.4 spinel cathode material, and another containing a charge transfer catalyst coated “O” site modified lithium manganese-based AB.sub.2O.sub.4 spinel cathode material according to an exemplary embodiment of the present disclosure.
DETAILED DESCRIPTION
[0049] 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.xMn.sub.2O.sub.4-zCl.sub.z, with X mol % MO.sub.b, or MMn.sub.aO.sub.b coating where M is a charge transfer catalyst metal Bi, As, or Sb via a method comprising an initial solid state milling and calcining process followed by a nitrate flame process with a calcining reaction to add the charge transfer catalyst coating. In Step S11, manganese oxide, lithium perchlorate, and lithium carbonate are mixed together and ground in Step S12. Lithium hydroxide, lithium oxide, or lithium peroxide may be substituted for lithium carbonate. This mixture is then calcined in Step S13 in a furnace for 600° C. for 2 hours. Alternatively, suitable calcination temperatures and times range from 350° C. to 800° C. (for 1 to 4 hours), from 400° C. to 600° C. (for 1.5 to 3 hours), or from 500° C. to 600° C. (for 2 to 2.5 hours). The resulting “O” site modified Li.sub.xMn.sub.2O.sub.4-zCl.sub.z yields material with x ranging from 0.05 to 1.9, 0.8 to 1.3, or 0.9 to 1.1; and z ranging from 0.005 to 0.25, 0.005 to 0.05, or 0.015 to 0.035.
[0050] In Step S14 of FIG. 1, the charge transfer catalyst salts and a chelating agent are dissolved in distilled or deionized water and nitric acid, and this solution is added to the calcined mixture. Suitable charge transfer catalyst salts include but are not limited to bismuth nitrate, arsenic nitrate, and antimony nitrate. Suitable chelating agents include, but are not limited to, glycine, cellulose, citric acid, a cellulose-citric acid mixture, and urea. Suitable volumetric quantities of nitric acid range from 5 vol % to 20 vol % in distilled or deionized water. In Step S15, the resultant mixture is heated to create a gel. Heating may be accomplished using a hot plate. In Step S16, the gel is heated further until auto ignition occurs. The resultant ash is ground and calcined in a furnace for 600° C. for 2 hours in Steps S17 and S18, respectively. Grinding may be accomplished using a mortar and pestle or any other conventional grinding methods. Suitable alternative calcination temperatures and times range from 350° C. to 800° C. (for 1 to 4 hours), from 400° C. to 600° C. (for 1.5 to 3 hours), or from 500° C. to 600° C. (for 2 to 2.5 hours). In the MO.sub.b, or MMn.sub.aO.sub.b coating, X ranges from 0.5 to 25, 1 to 20, or 3 to 15. In the final “O” site modified Li.sub.xMn.sub.2O.sub.4-zCl.sub.z material with the MO.sub.b or MMn.sub.aO.sub.b coating, x ranges from 0.05 to 1.9, 0.8 to 1.3, or 0.9 to 1.1. In addition, z ranges from 0.005 to 0.25, 0.005 to 0.05, or 0.015 to 0.035. Moreover, a ranges from 0 to 10; b ranges from 0 to 22, or b is greater than 0 but less than or equal to 22.
[0051] FIG. 2 is a flowchart illustrating process steps in an exemplary embodiment of the present disclosure. More specifically, FIG. 2 shows exemplary steps according to the present disclosure for the preparation of Li.sub.xMn.sub.2O.sub.4-zCl.sub.z or Li.sub.xMn.sub.2-yMe.sub.yO.sub.4-zCl.sub.z, where Me is Fe, Co, or Ni, with X mol % MO.sub.b or MMn.sub.aO.sub.b coating, where M is a charge transfer catalyst metal Bi, As, or Sb, via a method comprising an initial Li.sub.xMn.sub.2-yMe.sub.yO.sub.4-zCl.sub.z formulation and calcining process, followed by a nitrate flame process with a calcining reaction to add the charge transfer catalyst coating.
[0052] In Step S21, a lithium source, a manganese source, a metal source (where the metal is Fe, Co, or Ni), and a chlorine source are mixed together and ground in Step S22. This mixture is then calcined in Step S23 in a furnace for 600° C. for 2 hours. Alternatively, suitable calcination temperatures and times range from 350° C. to 800° C. (for 1 to 4 hours), from 400° C. to 600° C. (for 1.5 to 3 hours), or from 500° C. to 600° C. (for 2 to 2.5 hours). This process is followed by a nitrate flame process with a calcining reaction to add the charge transfer catalyst coating (Steps 24-28).
[0053] In one embodiment, suitable lithium sources include, but are not limited to, lithium carbonate, lithium hydroxide, lithium oxide, lithium peroxide, and lithium nitrate. The manganese source and the metal source may be derived from a single source, which is a metal oxide such as (MnMe.sub.f)O.sub.2, (MnMe.sub.f).sub.2O.sub.3, (MnMe.sub.f).sub.3O.sub.4, or (MnMe.sub.f)O, where Me is Fe, Co, or Ni, and the Mn to Me ratio is 1 to 0.0-0.43. For example, the metal oxide may be MnO.sub.2 or (Mn.sub.0.95Fe.sub.0.05).sub.2O.sub.3. Suitable chlorine sources include, but are not limited to, lithium perchlorate, lithium chloride, manganese chloride, iron chloride, cobalt chloride, and nickel chloride. These materials are mixed together and ground using conventional grinding methods. Suitable conventional grinding methods include, but are not limited to, using a mortar and pestle. This mixture is then calcined in Step S23 in a furnace for 600° C. for 2 hours. Alternatively, suitable calcination temperatures and times range from 350° C. to 800° C. (for 1 to 4 hours), from 400° C. to 600° C. (for 1.5 to 3 hours), or from 500° C. to 600° C. (for 2 to 2.5 hours).
[0054] In Step S24 of FIG. 2, the charge transfer catalyst salts and a chelating agent are dissolved in distilled or deionized water and nitric acid, and this solution is added to the calcined mixture. Suitable charge transfer catalyst salts include, but are not limited to, bismuth nitrate, arsenic nitrate, and antimony nitrate. Suitable chelating agents include, but are not limited to, glycine, cellulose, citric acid, a cellulose-citric acid mixture, and urea. Suitable volumetric quantities of nitric acid range from 5 vol % to 20 vol % in distilled or deionized water. In Step S25, the resultant mixture is heated to create a gel. Heating may be accomplished using a hot plate. In Step S26, the gel is heated further until auto ignition occurs. The resultant ash is ground and calcined in a furnace for 600° C. for 2 hours in Steps S27 and S28, respectively. A mortar and pestle may be used for grinding. Suitable alternative calcination temperatures and times range from 350° C. to 800° C. (for 1 to 4 hours), from 400° C. to 600° C. (for 1.5 to 3 hours), or from 500° C. to 600° C. (for 2 to 2.5 hours). In the final “B” and “O” site modified Li.sub.xMn.sub.2-yMe.sub.yO.sub.4-zCl.sub.z material, where Me is Fe, Co, or Ni with a MO.sub.b or MMn.sub.aO.sub.b charge transfer catalyst coating, x ranges from 0.05 to 1.9, 0.8 to 1.3, or 0.9 to 1.1, y ranges from 0.00 to 0.60, 0.005 to 0.3, or 0.03 to 0.3, and z ranges from 0.005 to 0.25, 0.005 to 0.05, or 0.015 to 0.035. In the MO.sub.b, or MMn.sub.aO.sub.b coating, X ranges from 0.5 to 25, 1 to 20, or 3 to 15. Regarding the charge transfer catalyst coating, a ranges from 0 to 10; and b ranges from 0 to 22, or b is greater than 0 but less than or equal to 22.
[0055] In an exemplary embodiment, the lithium source is lithium nitrate, the manganese source is manganese nitrate, the metal source is a Group VIII Period 4 element (Fe, Co, or Ni) nitrate, and the chlorine source is a chlorine-containing salt. These materials are mixed together in Step 21. Suitable alternative lithium sources include, but are not limited to, lithium carbonate, lithium hydroxide, or lithium chloride. Suitable alternative manganese sources include, but are not limited to, manganese chloride, manganese hydroxide, manganese carbonate. Suitable chlorine-containing salts include, but not limited to, lithium chloride, manganese chloride, iron chloride, cobalt chloride, and nickel chloride. In this embodiment, a chelating agent is added to the mixture and the resulting mixture is dissolved in distilled or deionized water. Suitable chelating agents include, but are not limited to, glycine, cellulose, citric acid, a cellulose-citric acid mixture, and urea. In this embodiment, two additional steps occur before the grinding step: First, the solution is heated until the water fully evaporates and a gel is formed. Heating may be accomplished on a hot plate. Second, the gel is heated further until auto ignition occurs and forms an ash. The ash is collected and ground in Step S22. A mortar and pestle may be used for grinding. It is to be understood by one of ordinary skill in the art that grinding may be accomplished by other means. This mixture is then calcined in Step S23 in a furnace for 600° C. for 2 hours. Alternatively, suitable calcination temperatures and times range from 350° C. to 800° C. (for 1 to 4 hours), from 400° C. to 600° C. (for 1.5 to 3 hours), or from 500° C. to 600° C. (for 2 to 2.5 hours).
[0056] In Step S24 of FIG. 2, the resultant calcined mixture, a charge transfer catalyst salt, and a chelating agent are dissolved in distilled or deionized water and nitric acid to form a solution. Suitable charge transfer catalyst salts include but are not limited to bismuth nitrate, arsenic nitrate, and antimony nitrate. Suitable chelating agents include, but are not limited to, glycine, cellulose, citric acid, a cellulose-citric acid mixture, and urea. Suitable volumetric quantities of nitric acid range from 5 vol % to 20 vol % in distilled or deionized water. In Step S25, the resultant mixture created in Step S24 is heated to form a gel. Heating may be accomplished on a hot plate. In Step S26, the gel is heated further until auto ignition occurs. The resultant ash is ground and calcined in a furnace for 600° C. for 2 hours in Steps S27 and S28, respectively. Alternatively, suitable calcination temperatures and times range from 350° C. to 800° C. (for 1 to 4 hours), from 400° C. to 600° C. (for 1.5 to 3 hours), or from 500° C. to 600° C. (for 2 to 2.5 hours). In the final “B” and “O” site modified Li.sub.xMn.sub.2-yMe.sub.yO.sub.4-zCl.sub.z material where Me is Fe, Co, or Ni with a MO.sub.b or MMn.sub.aO.sub.b coating, x ranges from 0.05 to 1.9, 0.8 to 1.3, or 0.9 to 1.1, y ranges from 0.00 to 0.60, 0.005 to 0.3, or 0.03 to 0.3, and z ranges from 0.005 to 0.25, 0.005 to 0.05, or 0.015 to 0.035. In the MO.sub.b, or MMn.sub.aO.sub.b coating, X ranges from 0.5 to 25, 1 to 20, or 3 to 15. Regarding the MO.sub.b, or MMn.sub.aO.sub.b coating, a ranges from 0 to 10; and b ranges from 0 to 22, or b is greater than 0 but less than or equal to 22.
[0057] The exemplary process described above results in the formulation of a family of “B” and “O” site modified Li.sub.xMn.sub.2-yMe.sub.yO.sub.4-zCl.sub.z, where Me is Fe, Co or Ni with X mol % MO.sub.b or MMn.sub.aO.sub.b coating. The general formula for the lithium electrochemical cell cathode prepared is Li.sub.xMn.sub.2-yMe.sub.yO.sub.4-zCl.sub.z with X mol % MO.sub.b or MMn.sub.aO.sub.b coating, where M is iron, cobalt or nickel, x≈1 and proves to be reversible between 4.5 and 2.0 volts. This reversible region for x in a lithium electrochemical cell comprised of the present disclosure ranges from 0.05 to 1.9 and y ranges from 0.0 to 0.6 and z ranges from 0.005 to 0.25.
[0058] FIGS. 3 and 4 show the X-ray diffraction pattern of an exemplary formulation mixture according to exemplary embodiments of the present disclosure compared to known reference standards. The figures show the final Li.sub.xMn.sub.2O.sub.4-zCl.sub.z with 15 mol % Bi of the form Bi.sub.2Mn.sub.4O.sub.10 coating material according to the present disclosure. The bismuth to manganese ratio is 0.149, or approximately 15 mol %. Included in FIG. 4 is the standard data for intensity and location from the International Center for Diffraction Data for Bi.sub.2Mn.sub.4O.sub.10 (JCPDS catalog number 027-0048) and LiMn.sub.2O.sub.4 spinel (JCPDS catalog number 018-0736). FIGS. 5 and 6 show the X-ray fluorescence (XRF) pattern for an exemplary formulation mixture of the present disclosure. Included in FIGS. 5 and 6 is the data describing the final Li.sub.xMn.sub.2O.sub.4-zCl.sub.z with 3 mol % and 15 mol % Bi material, respectively (which equates to bismuth to manganese ratios of 0.0379 and 0.149), as well as intensity and energy level for the system components. These components include the palladium X-ray source and silicon, sulfur, and phosphorus from the sample holder. XRF is performed on every sample for determining the mol % of M contained within the material.
[0059] FIG. 7 shows the thermogravimetric analysis results of Li.sub.xMn.sub.2O.sub.4-zCl.sub.z spinel with X mol % Bi added at Step S17 prior to calcination according to exemplary embodiments of the present disclosure. In the exemplary image shown in FIG. 7, bismuth to manganese ratio is 0.135, or approximately 13 mol %. Between 30 and 120° C., the mass loss can be attributed to the dehydration of the physically absorbed water molecules. From 200 to 300° C., a mass loss is observed and can be attributed to the melting and denitration of remaining nitrates in the precursor via NO.sub.2 evolution. In the 300 to 400° C. range, the mass loss could be due to residual glycine decomposition into CO.sub.2, N.sub.2, and H.sub.2O in combination with formation of the spinel. Between 400 and 500° C., a slight mass increase occurs due to oxidation. Above 500° C., the mass loss is most likely due to chlorine evolution.
[0060] FIG. 8 shows a backscattered SEM image of the final Li.sub.xMn.sub.2O.sub.4-zCl.sub.z spinel with 15 mol % Bi coating according to an exemplary embodiment of the present disclosure. This image was taken with the following SEM settings: 5.0 kV, 6.1 mm×20.0 k SE(U,HA). The contrast is due to the Z scatter of the contained elements showing a majority gray structure with submicron second phase Bi.sub.2Mn.sub.4O.sub.10 in a pale gray dispersed on the surface. In the exemplary image shown in FIG. 8, bismuth is the charge transfer catalyst coating on the modified lithium manganese-based AB.sub.2O.sub.4 spinel cathode material.
[0061] In order to evaluate the electrochemical properties of the present Li.sub.xMn.sub.2O.sub.4-zCl.sub.z or Li.sub.xMn.sub.2-yMe.sub.yO.sub.4-zCl.sub.z, where Me is Fe, Co, or Ni with X mol % MO.sub.b or MMn.sub.aO.sub.b coating in an electrochemical system, laboratory coin cells were fabricated using conventional methods described in detail below. Experimental cells may also be fabricated using other methods known in the art, incorporating the charge transfer catalyst coated Li.sub.xMn.sub.2O.sub.4-zCl.sub.z or the charge transfer catalyst coated Li.sub.xMn.sub.2-yMe.sub.yO.sub.4-zCl.sub.z, where Me is Fe, Co, or Ni, lithium manganese-based AB.sub.2O.sub.4 spinel material described in the present disclosure. The experimental cells were composed of a lithium anode separated from a polytetrafluoroethylene (commercially available under the trade name TEFLON, manufactured by DuPont) 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.xMn.sub.2-yMe.sub.yO.sub.4-zCl.sub.z, carbon, and polytetrafluoroethylene 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, polyvinylidene fluoride (PVDF), and latex. The cathode may contain by weight 40%-95% Li.sub.xMn.sub.2-yMe.sub.yO.sub.4-zCl.sub.z with X mol % MO.sub.b or MMn.sub.aO.sub.b (where X ranges from 0.5 to 25.0, 1 to 20, or 3 to 15), 1%-40% of conductive carbon, and 1%-20% binder.
[0062] 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.H.sub.2O), 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 volts. The cells were discharged at 1.0, 2.0, 4.0, 6.0, 8.0, or 16.0 mA to 2.0, 2.25 or 3.0 or 3.5 volts. Additionally, pulse tests were performed upon discharge at 8.0 mA for 1 minute followed by a 3 minute rest. 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.
[0063] The data shows stable Li.sub.xMn.sub.2O.sub.4-zCl.sub.z or Li.sub.xMn.sub.2-yMe.sub.yO.sub.4-zCl.sub.z with X mol % MO.sub.b or MMn.sub.aO.sub.b (where M is Bi, As, or Sb) charge transfer catalyst coating was formulated, fabricated, and characterized as a positive electrode suitable for lithium and lithium ion rechargeable electrochemical cells and batteries. The general formula for the present spinel material is Li.sub.xMn.sub.2-yMe.sub.yO.sub.4-zCl.sub.z with X mol % MO.sub.b or MMn.sub.aO.sub.b where Me is Fe, Co, or Ni; M is Bi, As, or Sb; and X ranges from 0.5 to 25.0, 1 to 20, or 3 to 15. Moreover, x ranges from 0.05 to 1.9, 0.8 to 1.3, or 0.9 to 1.1; y ranges from 0.00 to 0.60, 0.005 to 0.3, or 0.03 to 0.3, and z ranges from 0.005 to 0.25, 0.005 to 0.05, or 0.015 to 0.035. In addition, a ranges from 0 to 10; and b ranges from 0 to 22, orb is greater than 0 but less than or equal to 22.
[0064] The rate capability of the Li.sub.xMn.sub.2O.sub.4-zCl.sub.z or Li.sub.xMn.sub.2-yMe.sub.yO.sub.4-zCl.sub.z with X mol % MO.sub.b or MMn.sub.aO.sub.b charge transfer catalyst coated cathode material is demonstrated with greater than 90% of specific discharge capacity through 200 cycles from 4.5 to 3.0 Vat 8 mA/cm.sup.2 (120 mA/g, with a C-rate of approximately 1C) and greater than 75% of specific discharge capacity through 140 cycles at 16 mA/cm.sup.2 (240 mA/g, approximately 2C rate). The specific capacity for the Li.sub.xMn.sub.2O.sub.4-zCl.sub.z or Li.sub.xMn.sub.2-yMe.sub.yO.sub.4-zCl.sub.z with X mol % MO.sub.b or MMn.sub.aO.sub.b charge transfer catalyst coating cathode material ranged from 50 to 80 mAh/g when coupled with lithium and cycled between 4.5 and 3.0 volts. This is less than conventional lithium manganese-based AB.sub.2O.sub.4 spinel materials fabricated over a 48 to 72-hour time span due to the addition of the very heavy charge transfer catalyst materials. The specific capacity for the Li.sub.xMn.sub.2O.sub.4-zCl.sub.z or Li.sub.xMn.sub.2-yMe.sub.yO.sub.4-zCl.sub.z with X mol % MO.sub.b or MMn.sub.aO.sub.b charge transfer catalyst coating cathode material was 130 to 170 mAh/g when coupled with lithium and cycled between 4.5 and 2.0 volts. In the MO.sub.b, or MMn.sub.aO.sub.b coating, X ranges from 0.5 to 25, 1 to 20, or 3 to 15.
[0065] FIGS. 9-11 show discharge capacity and galvanostatic (charge/discharge) plots for lithium electrochemical cells fabricated with Li.sub.xMn.sub.2O.sub.4-zCl.sub.z with X mol % MO.sub.b or MMn.sub.aO.sub.b charge transfer catalyst coating cathode material, synthesized using the method described in the present disclosure. In the exemplary plots shown in FIGS. 9-11, bismuth is the charge transfer catalyst coating on the modified lithium manganese-based AB.sub.2O.sub.4 spinel cathode material. The bismuth to manganese ratio in FIGS. 9-11 is 0.0379, or approximately 3 mol %.
[0066] FIGS. 9 and 10 show exemplary discharge capacities through 500 and 600 cycles, respectively, with select charge and discharge curves displayed in FIG. 11 for lithium electrochemical cells fabricated with Li.sub.xMn.sub.2O.sub.4-zCl.sub.z with X mol % MO.sub.b or MMn.sub.aO.sub.b charge transfer catalyst coating cathode material, synthesized using the method described in the present disclosure. All cycles were cycled between 4.5 V to 3.0 V. Cycles 1-12 were charged and discharged at 1.1 mA/cm.sup.2, cycles 13-20 were charged at 2 mA/cm.sup.2 and discharged at 8 mA/cm.sup.2, cycles 21-30 were charged and discharged at 2 mA/cm.sup.2, cycles 31-500 were charged at 2 mA/cm.sup.2 and discharged at 8 mA/cm.sup.2, cycles 501-550 were charged at 2 mA/cm.sup.2 and pulse discharged at 8 mA/cm.sup.2 for 1 minute and rested for 3 minutes, and cycles 551-600 were charged and discharged at 2 mA/cm.sup.2. Good capacity retention is demonstrated at extended cycling at a high rate, 8 mA/cm.sup.2 (1C rate, 104 mA/g). FIG. 11 shows after extended cycling at a high rate, 90% of the discharge capacity can be recovered with pulse discharging at 8 mA/cm.sup.2 for 1 minute and rest for 3 minutes at cycle 505, which is equivalent to the 2 mA/cm.sup.2 discharge at cycle 565, as compared with the early cycling at the same 2 mA/cm.sup.2 rate at cycle 25.
[0067] FIG. 12 shows the discharge capacity per cycle comparing two chemistries, one being Li.sub.xMn.sub.2O.sub.4 synthesized using Steps S21-S23 without “B” or “O”-site modification before the addition of the charge transfer catalyst, and Li.sub.xMn.sub.2O.sub.4-zCl.sub.z with X mol % MO.sub.b or MMn.sub.aO.sub.b charge transfer catalyst coating cathode material, synthesized using the method described in the present disclosure. In the exemplary plots shown in FIG. 12, bismuth is the charge transfer catalyst coating on the modified lithium manganese-based AB.sub.2O.sub.4 spinel cathode material. The bismuth to manganese ratio is 0.0379, or approximately 3 mol %. All cycles were cycled between 4.5 V to 3.0 V. The Li.sub.xMn.sub.2O.sub.4 synthesized using Steps S21-S23 without “B” or “O”-site modification before the addition of the charge transfer catalyst was cycled at 1 mA/cm.sup.2 for cycles 1-126, cycles 127-146 were charged at 2 mA/cm.sup.2 and discharged at 8 mA/cm.sup.2, cycles 147-166 were charged at 2 mA/cm.sup.2 and discharged at 4 mA/cm.sup.2, cycles 167-206 were charged at 2 mA/cm.sup.2 and discharged at 6 mA/cm.sup.2, and cycles 207-226 were charged and discharged at 2 mA/cm.sup.2. The Li.sub.xMn.sub.2O.sub.4-zCl.sub.z with X mol % MO.sub.b or MMn.sub.aO.sub.b charge transfer catalyst coating cathode material was charged and discharged at 1.1 mA/cm.sup.2 for cycles 1-12, cycles 13-20 were charged at 2 mA/cm.sup.2 and discharged at 8 mA/cm.sup.2, cycles 21-30 were charged and discharged at 2 mA/cm.sup.2, cycles 31-225 were charged at 2 mA/cm.sup.2 and discharged at 8 mA/cm.sup.2. The high rate capability with the addition of the charge transfer catalyst coating is demonstrated in FIG. 12 by the very small loss in discharge capacity from lower rates (1-2 mA/cm.sup.2) to the higher 8 mA/cm.sup.2 rate for the Li.sub.xMn.sub.2O.sub.4-zCl.sub.z with X mol % MO.sub.b or MMn.sub.aO.sub.b charge transfer catalyst coating cathode material versus a greater than 10% difference in discharge capacity the Li.sub.xMn.sub.2O.sub.4 synthesized using Steps S21-S23 without “B” or “O”-site modification before the addition of the charge transfer catalyst material.
[0068] FIG. 13 is a differential capacity graph of cycles 130 through 140 illustrating exemplary cycle life traces for three separate lithium cells, one being Li.sub.xMn.sub.2O.sub.4-zCl.sub.z synthesized using Steps S11-S13 before the addition of the charge transfer catalyst, one being Li.sub.xMn.sub.2O.sub.4 synthesized using Steps S21-S23 without “B” or “O” site modification before the addition of the charge transfer catalyst, and Li.sub.xMn.sub.2O.sub.4-zCl.sub.z with X mol % MO.sub.b or MMn.sub.aO.sub.b charge transfer catalyst coating cathode material, synthesized using the method described in the present disclosure. In the exemplary plot shown in FIG. 13, bismuth is the charge transfer catalyst coating on the modified lithium manganese-based AB.sub.2O.sub.4 spinel cathode material. The bismuth to manganese ratio is 0.03, or approximately 3 mol %. Differential capacity traces provides 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. During cycles 130-140, all cells were cycled between 4.5 V to 3.0 V with a charge rate of 2 mA/cm.sup.2 and discharge rate of 8 mA/cm.sup.2. This figure shows that only with the addition of the charge transfer catalyst coating is the electrochemistry more reversible (corresponding peaks are closer together) and the electrochemical activity is completed faster, almost entirely before 3.5 V upon discharge as shown by the narrower peaks.
[0069] FIG. 14 is a bar graph of the percent of discharge capacity at cycle 150 discharged from 4.5 to 3.0 V at 8 mA/cm.sup.2 versus cycle 5 discharged at 1 (9 mol % Bi) mA/cm.sup.2 or 2 mA/cm.sup.2 (no Bi, 3 mol % Bi, 9 mol % Bi with 6% Co, and 15 mol % Bi) for five separate chemistries, one being Li.sub.xMn.sub.2O.sub.4-zCl.sub.z synthesized using Steps S11-S13 before the addition of the charge transfer catalyst, and four different Li.sub.xMn.sub.2-yMe.sub.yO.sub.4-zCl.sub.z with X mol % MO.sub.b or MMn.sub.aO.sub.b charge transfer catalyst coating cathode materials, synthesized using the method described in the present disclosure. In the exemplary plot shown in FIG. 14, bismuth is the charge transfer catalyst coating on the modified lithium manganese-based AB.sub.2O.sub.4 spinel cathode material and one embodiment includes Me=Co, where y=0.06. The bismuth to manganese ratio is 0.0379, 0.0959, 0.0848, 0.149 or approximately 3, 9, 8, and 15 mol %. The high rate capability is demonstrated in all four charge transfer catalyst embodiments showing approximately 80% capacity retention or greater for an 8 mA/cm.sup.2 discharge at extended cycling compared to less than 70% capacity retention for the same synthesis only without the addition of the charge transfer coating described in Steps S14-18 of FIG. 1 and Steps S24-28 of FIG. 2.
[0070] FIG. 15 is a bar graph of the percent of discharge capacity at cycle 140 discharged from 4.5 to 3.0 V at 16 mA/cm.sup.2 versus cycle 5 discharged 2 mA/cm.sup.2 for four separate embodiments, one being Li.sub.xMn.sub.2O.sub.4-zCl.sub.z synthesized using Steps S11-S13 before the addition of the charge transfer catalyst, and three different Li.sub.xMn.sub.2-yMe.sub.yO.sub.4-zCl.sub.z with X mol % MO.sub.b or MMn.sub.aO.sub.b charge transfer catalyst coating cathode materials, synthesized using the method described in the present disclosure. In the exemplary plot shown in FIG. 15, bismuth is the charge transfer catalyst coating on the modified lithium manganese-based AB.sub.2O.sub.4 spinel cathode material and one embodiment includes Me is cobalt and y=0.06. The bismuth to manganese ratio is 0.0379, 0.0848, 0.149 or approximately 3, 9, and 15 mol %. The high rate capability is demonstrated in all three charge transfer catalyst chemistries showing approximately 52-75% capacity retention for a 16 mA/cm.sup.2 discharge at extended cycling compared to less than 40% capacity retention for the same synthesis only without the addition of the charge transfer coating described in Steps S14-18 of FIG. 1 and Steps S24-28 of FIG. 2.
[0071] FIGS. 16-19 show discharge capacity per cycle and the galvanostatic charge/discharge cycle plots for 3 exemplary electrochemical cells with Li.sub.xMn.sub.2-yMe.sub.yO.sub.4-zCl.sub.z with X mol % MO.sub.b or MMn.sub.aO.sub.b charge transfer catalyst coating cathode material, synthesized using the method described in the present disclosure. In the exemplary plots shown in FIGS. 16-19, bismuth is the charge transfer catalyst coating on the modified lithium manganese-based AB.sub.2O.sub.4 spinel cathode material and cobalt is the “B” site modifier where y=0.06. The bismuth to manganese ratio is 0.0848, or approximately 9 mol %. The cells were cycled from 4.5V to 3.0V. Cell 1 was charged and discharged at 1 mA/cm.sup.2 for cycles 1-10, cycles 11-20 were charged at 2 mA/cm.sup.2 and discharged at 4 mA/cm.sup.2, cycles 21-140 were charged at 4 mA/cm.sup.2 and discharged at 8 mA/cm.sup.2, and cycles 141-150 were charged and discharged at 2 mA/cm.sup.2. Cell 2 was charged and discharged at 2 mA/cm.sup.2 for cycles 1-10, cycles 11-140 were charged at 2 mA/cm.sup.2 and discharged at 8 mA/cm.sup.2, and cycles 141-150 were charged and discharged at 2 mA/cm.sup.2. Cell 3 was charged and discharged at 2 mA/cm.sup.2 for cycles 1-10, cycles 11-20 were charged at 2 mA/cm.sup.2 and discharged at 8 mA/cm.sup.2, cycles 21-140 were charged at 2 mA/cm.sup.2 and discharged at 16 mA/cm.sup.2, and cycles 141-150 were charged and discharged at 2 mA/cm.sup.2. In FIG. 16, cell 3 shows excellent capacity retention at the very high 16 mA/cm.sup.2 discharge rate (2C, 234 mA/g) over cycles 21-140. This comports with the 8 mA/cm.sup.2 discharge rate capacities of the other two cells across the same cycle region. In FIGS. 17-19, the charge and discharge curves for the 2 mA/cm.sup.2 cycling at cycle 145 and cycle 5 are nearly identical after extended cycling at high rates for all three cells. FIG. 19 shows how quickly the electrochemistry can be performed at the very high 16 mA/cm.sup.2 discharge rate capacity, with essentially no damage to the crystal before and after the high rate cycling in the charge transfer catalyst coated AB.sub.2O.sub.4 spinel material.
[0072] FIGS. 20-22 show the galvanostatic charge/discharge cycle plots for 3 exemplary electrochemical cells with Li.sub.xMn.sub.2O.sub.4-zCl.sub.z with X mol % MO.sub.b or MMn.sub.aO.sub.b charge transfer catalyst coating cathode material, synthesized using the method described in the present disclosure. In the exemplary plots shown in FIGS. 20-22, bismuth is the charge transfer catalyst coating on the modified lithium manganese-based AB.sub.2O.sub.4 spinel cathode material. The bismuth to manganese ratio is 0.149, or approximately 15 mol %. All cells were cycled from 4.5 to 3.0 V. Cell 4 was charged and discharged at 1 mA/cm.sup.2 for cycles 1-10, cycles 11-19 were charged at 2 mA/cm.sup.2 and discharged at 4 mA/cm.sup.2, cycles 20-39 were charged at 2 mA/cm.sup.2 and discharged at 16 mA/cm.sup.2, cycles 40-221 were charged at 2 mA/cm.sup.2 and discharged at 8 mA/cm.sup.2, and cycles 222-231 were charged and discharged at 1 mA/cm.sup.2. Cell 5 was charged and discharged at 1 mA/cm.sup.2 for cycles 1-10, cycles 11-21 were charged at 2 mA/cm.sup.2 and discharged at 4 mA/cm.sup.2, cycles 22-31 were charged at 2 mA/cm.sup.2 and discharged at 8 mA/cm.sup.2, cycles 32-241 were charged at 4 mA/cm.sup.2 and discharged at 8 mA/cm.sup.2, and cycles 242-251 were charged and discharged at 1 mA/cm.sup.2. Cell 6 was charged and discharged at 1 mA/cm.sup.2 for cycles 1-10, cycles 11-22 were charged at 2 mA/cm.sup.2 and discharged at 8 mA/cm.sup.2, cycles 23-242 were charged at 2 mA/cm.sup.2 and discharged at 16 mA/cm.sup.2, and cycles 243-252 were charged and discharged at 1 mA/cm.sup.2. FIGS. 20-22 demonstrate reasonable capacity retention at 1 mA/cm.sup.2 after greater than 200 cycles at high rates (16 and 8 mA/cm.sup.2) due to the addition of the charge transfer catalyst coating on the AB.sub.2O.sub.4 spinel material.
[0073] FIGS. 23 and 24 show galvanostatic charge and discharge curves for an exemplary electrochemical cell with Li.sub.xMn.sub.2O.sub.4-zCl.sub.z with X mol % MO.sub.b or MMn.sub.aO.sub.b charge transfer catalyst coating cathode material, synthesized using the method described in the present disclosure. In these figures, bismuth is the charge transfer catalyst coating on the modified lithium manganese-based AB.sub.2O.sub.4 spinel cathode material. The bismuth to manganese ratio is 0.0959, or approximately 9 mol %. The cell was cycled from 4.5 V to 3.0 V from cycles 1 through 150. The charge and discharge rate for cycles 1-10 was 2 mA/cm.sup.2, cycles 11-150 were charged at 2 mA/cm.sup.2 and discharged at 8 mA/cm.sup.2. For cycles 151 to 162, the charge and discharge rates were 2 mA/cm.sup.2, but the discharge potential oscillated back and forth from 3.0 V to 2.25 V to access the second lithium insertion. In FIG. 23, the high rate capability is demonstrated by negligible loss of capacity between the 2 mA/cm.sup.2 discharges at cycles 155 and 5 after the long cycling at elevated discharge rate 8 mA/cm.sup.2. In FIG. 24, the deep discharge to 2.25 V is shown achieving twice the capacity achieved in the 4.5 to 3.0 V discharge. This figure demonstrates that the charge transfer catalyst coated spinel material exhibits deep discharge capability as a result of the “O” site chlorine modifications through the continued charge and discharge in cycle 153, and the cycles up to 155, as shown in FIG. 23.
[0074] FIGS. 25 and 26 are charge/discharge hysteresis and electrochemical impedance spectroscopy (EIS) plots comparing two chemistries, one with Li.sub.xMn.sub.2O.sub.4-zCl.sub.z synthesized using Steps S11-S13 before the addition of the charge transfer catalyst, and another with Li.sub.xMn.sub.2O.sub.4-zCl.sub.z with X mol % MO.sub.b or MMn.sub.aO.sub.b charge transfer catalyst coating cathode material, synthesized using the method described in the present disclosure. In these figures, bismuth is the charge transfer catalyst coating on the modified lithium manganese-based AB.sub.2O.sub.4 spinel cathode material. The bismuth to manganese ratio is 0.149, or approximately 15 mol %. In FIG. 25, the first four cycles after the forming cycle (2-5) from 4.5 to 3.0 V with a charge/discharge rate of 2 mA/cm.sup.2 are displayed against a normalized capacity for comparison purposes. The material containing the bismuth charge transfer catalyst coating shows a far smaller hysteresis in cycling, indicating faster kinetics during electrochemical cycling. FIG. 26 is the electrochemical impedance measured at 3.6 V of open circuit voltage immediately following cell fabrication. This figure supports the enhanced kinetic properties of the bismuth charge transfer coating by demonstrating a far smaller charge transfer resistance upon cell fabrication.
[0075] 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.
