Doped manganese-rich cathode active material and method thereof

Abstract

Doped manganese-rich cathode active materials and methods of manufacture are described. The doped manganese-rich cathode active materials enable energy storage devices with improved performance, including, but not limited to, improved cycle life and capacity retention.

Description

[Technical Field]

[0001] [CROSS-REFERENCE TO RELATED APPLICATIONS] All applications for which a foreign or domestic priority claim is identified in the Application Data Sheet or PCT application filed with this application are incorporated herein by reference under 37 CFR 1.57 and Rules 4.18 and 20.6. This application claims priority to U.S. Provisional Patent Application No. 63 / 478,465, filed January 4, 2023, entitled "DOPED MANGANESE-RICH CATHODE ACTIVE MATERIALS AND METHODS THEREOF," which is incorporated herein by reference in its entirety.

[0002] The present disclosure relates generally to energy storage devices, and specifically to cathode active materials for lithium-ion batteries and processes for forming the same. [Background technology]

[0003] Electrochemical energy storage systems are widely used to power electronic, electromechanical, electrochemical, and other useful devices. Lithium-ion batteries are one of the most common examples of electrochemical energy storage systems, and their popularity is due to their higher energy density compared to other electrochemical energy storage systems. Over the past decade, the use of lithium-ion batteries has expanded from consumer electronics to other areas, including the automotive industry. Lithium-ion batteries consist of four main components: a cathode electrode, an anode electrode, an electrolyte, and a separator. At least part of the success of lithium-ion batteries can be attributed to the development of high-energy-density electrodes.

[0004] Currently, only a few cathode active materials are known or under consideration for use in cathode electrodes for lithium-ion batteries, for example in the automotive industry. Examples of cathode active materials include manganese-rich cathode active materials such as LiMn2O4. LiMn2O4 is a low-cost, high-voltage, and environmentally friendly cathode active material with moderate energy density. These attractive properties make spinel-type LiMn2O4 a good candidate for large-scale batteries for electric vehicle (EV) and hybrid electric vehicle (HEV) applications. However, LiMn2O4 is not currently widely used as a cathode active material in batteries requiring long cycle life due to capacity loss caused by Mn dissolution and subsequent cell degradation, especially at high temperatures. Capacity may decrease after less than 50 cycles. Therefore, there is a need for improved manganese-rich cathode active materials with improved cycle life. Summary of the Invention

[0005] For purposes of summarizing the present disclosure and the advantages achieved over the prior art, certain objectives and advantages of the present disclosure are described herein. Not all such objectives or advantages may be achieved in any particular embodiment. Thus, for example, those skilled in the art will recognize that the present invention may be embodied or implemented to achieve or optimize one advantage or advantages as taught herein without necessarily achieving other objectives or advantages as may be taught or suggested herein.

[0006] In a first aspect, a doped cathode active material is provided. The doped cathode active material has the formula Li (1+a) M b Mn (2-c) M´ c O (4-d) X e(wherein M is a metal dopant, M' is a Group 13 dopant, X is an anion dopant, a is a value between 0 and 0.2, b is a value between 0.01 and 0.1, c is a value between 0 and 0.2, d is a value between 0 and 0.04, and e is a value between 0.001 and 0.04).

[0007] In some embodiments, M is selected from the group consisting of K, Na, Mg, Sr, and combinations thereof. In some embodiments, X is a halogen dopant. In some embodiments, X is selected from the group consisting of F, Cl, SO4, and combinations thereof. In some embodiments, M' is selected from the group consisting of B, Al, and combinations thereof. In some embodiments, M' is selected from the group consisting of B, Al, and combinations thereof. c Al x B y where c=x+y. In some embodiments, the compound has the formula Li (1+a) Na b Mn (2-c) Al x B y O (4-d) F e In some embodiments, the compound has the formula Li 1.05 Na 0.05 Mn 1.82 Al 0.15 B 0.03 O 3.98 F 0.02 It has.

[0008] In some embodiments, a cathode electrode film is provided that includes the doped cathode active material and a binder. In some embodiments, the cathode electrode film is disposed on a current collector to form a cathode electrode. In some embodiments, the energy storage device includes a cathode electrode, a separator, an anode electrode, an electrolyte, and a housing, wherein the cathode electrode, separator, and anode electrode are located within the housing. In some embodiments, the energy storage device is a battery.

[0009] In a second aspect, a process for forming a doped cathode active material is provided. In some embodiments, the process includes combining a manganese source, a dopant material, and a lithium source to form a doped cathode active material mixture, and heating the doped cathode active material mixture to form the doped cathode active material. In some embodiments, the combining includes mixing a manganese source, a dopant material, and a lithium source.

[0010] In some embodiments, the lithium source is selected from the group consisting of LiOH, Li2CO3, LiF, LiCl, and combinations thereof. In some embodiments, the manganese source is selected from the group consisting of Mn3O4, MnF2, and combinations thereof. In some embodiments, the dopant material is selected from the group consisting of a Group 13 dopant source, a metal dopant source, an anion dopant source, and combinations thereof. In some embodiments, the anion dopant source is selected from the group consisting of MnF2, MgF2, MgCl2, AlF3, SrF2, NaF, NaCl, LiF, LiCl, KCl, K2SO4, and combinations thereof. In some embodiments, the metal dopant source is selected from the group consisting of KCl, K2SO4, NaF, NaCl, Na2CO3, MgF2, MgCO3, Mg(OH)2, SrF2, MgCl2, and combinations thereof. In some embodiments, the Group 13 dopant source is selected from the group consisting of H3BO3, Al(OH)3, and combinations thereof. In some embodiments, the dopant material comprises H3BO3, Al(OH)3, MnF2, and Na2CO3.

[0011] In some embodiments, the doped cathode active material mixture is heated to about 700° C. to 900° C. In some embodiments, the doped cathode active material mixture is heated in ambient air for about 4 to 6 hours.

[0012] In another aspect, a process for forming a doped cathode active material is provided. In some embodiments, the process includes combining a manganese source, a first dopant material, and a lithium source to form a first doped cathode active material mixture, heating the first doped cathode active material mixture at a first temperature, combining the heated first doped cathode active material mixture with a second dopant material to form a second doped cathode active material mixture, and heating the second doped cathode active material mixture at a second temperature different from the first temperature to form the doped cathode active material. In some embodiments, combining the manganese source, the first dopant material, and the lithium source includes mixing the manganese source, the first dopant material, and the lithium source. In some embodiments, combining the heated first doped cathode active material mixture with the second dopant material comprises mixing the heated first doped cathode active material mixture with the second dopant material, hi some embodiments, the process further comprises sieving the heated second doped cathode active material mixture.

[0013] In some embodiments, the first dopant material is selected from the group consisting of a Group 13 dopant source, an anion dopant source, and combinations thereof. In some embodiments, the second dopant material comprises a metal dopant source. In some embodiments, the second temperature is lower than the first temperature. In some embodiments, the first temperature is between about 700°C and 900°C. In some embodiments, the second temperature is between about 600°C and 800°C. In some embodiments, the heated second doped cathode active material mixture is sieved to form a second doped cathode active material mixture. [Brief explanation of the drawings]

[0014] These and other features, aspects, and advantages of the present disclosure will be described with reference to drawings of specific embodiments, which are intended to illustrate particular embodiments and are not intended to limit the invention.

[0015] [Figure 1] 2 is a flow diagram illustrating an example of a single-step calcination method for producing a doped cathode active material, according to some embodiments.

[0016] [Figure 2] 2 is a flow diagram illustrating an example of a two-step calcination method for producing a doped cathode active material, according to some embodiments.

[0017] [Figure 3A] 1 is a plot showing the cycling performance of a full cell having a cathode including a doped manganese-rich cathode active material formed by a single-step calcination method, according to some embodiments.

[0018] [Figure 3B] 1 is a plot showing normalized cycling performance of a full cell having a cathode including a doped manganese-rich cathode active material formed by a single-step calcination method, according to some embodiments.

[0019] [Figure 4A] 1 is a plot showing the cycling performance of a full cell having a cathode including a doped manganese-rich cathode active material formed by a two-step calcination process, according to some embodiments.

[0020] [Figure 4B] 1 is a plot showing normalized cycling performance of a full cell having a cathode including a doped manganese-rich cathode active material formed by a two-step calcination process, according to some embodiments.

[0021] [Figure 5A]1 is a plot showing the cycling performance of full cells having cathodes including a doped manganese-rich cathode active material according to some embodiments and a control cathode active material.

[0022] [Figure 5B] 1 is a plot showing normalized cycling performance of full cells having cathodes including a doped manganese-rich cathode active material according to some embodiments and a control cathode active material. Detailed Description of the Invention

[0023] Various embodiments of doped manganese-rich cathode active materials with improved capacity retention and extended cycle life and methods for preparing the doped manganese-rich cathode active materials are provided herein. Doping of the manganese-rich cathode active material can help reduce manganese dissolution from manganese-rich cathode active materials, such as spinel-type lithium manganese oxide ("LiMn2O4"), and reduce subsequent cell degradation and capacity fade. In some embodiments, the improved doped manganese-rich cathode active materials described herein can help reduce manganese dissolution from the doped manganese-rich cathode active material, thereby improving the cycle life and capacity retention of energy storage devices.

[0024] In certain embodiments, the doped manganese-rich cathode active material can include a dopant material. In some embodiments, the dopant material is selected from metal dopants (M), Group 13 dopants (M'), anion dopants (X), and combinations thereof. In some embodiments, the dopant material includes a metal dopant selected from sodium (Na), magnesium (Mg), potassium (K), strontium (Sr), and combinations thereof. In some embodiments, the dopant material includes a selected metal dopant selected from fluorine (F), chlorine (Cl), sulfate (SO4), 2-) and combinations thereof. In some embodiments, the anion dopant is a halogen dopant. In some embodiments, the dopant material includes selected Group 13 dopants of boron (B), aluminum (Al), and combinations thereof. In certain embodiments, the doped manganese-rich cathode active material has the general formula Li (1+a) M b Mn (2-c) M´ c O (4-d) X e or LiM b Mn2M´ c O4X e where M is a metal dopant, M' is a Group 13 dopant element, and X is an anion dopant. "a," "b," "c," "d," and "e" are values ​​that produce a charge-neutral dopant material.

[0025] Such doped manganese-rich cathode active materials are described and can be prepared by the processes described herein.

[0026] A. Doped Manganese-Rich Cathode Active Material High manganese content (“manganese-rich”) cathode active materials (e.g., spinel-type lithium manganese oxide, LiMn2O4) can include dopants to improve cathode electrode performance. In some embodiments, the manganese-rich cathode active material includes LiMn2O4. In some embodiments, the doped manganese-rich cathode active material includes lithium (Li), manganese (Mn), an anion dopant, and oxygen (O). In some embodiments, the doped manganese-rich cathode active material includes lithium (Li), manganese (Mn), a metal dopant (M), and oxygen (O). In some embodiments, the doped manganese-rich cathode active material includes lithium (Li), manganese (Mn), a metal dopant (M), an anion dopant, and oxygen (O). In some embodiments, the doped manganese-rich cathode active material further includes a Group 13 dopant.

[0027] In some embodiments, the doped manganese-rich cathode active material has the general formula Li (1+a) M b Mn (2-c) M´ c O (4-d) X e´ where M is a metal dopant, M' is a Group 13 dopant, X is an anion dopant, and "a," "b," "c," "d," and "e" are values ​​that produce a charge-neutral dopant material.

[0028] In some embodiments, "a" is at, near, up to, or near 0, 0.001, 0.005, 0.01, 0.02, 0.03, 0.04, 0.05, 0.06, 0.07, 0.08, 0.09, 0.1, 0.11, 0.12, 0.13, 0.14, 0.15, 0.16, 0.17, 0.18, 0.19, 0.2, 0.21, 0.22, 0.23, 0.24, 0.25, 0.26, 0.27, 0.28, 0.29, or 0.3, or any range of values ​​therebetween. For example, in some embodiments, "a" is a number between 0 and 0.3, between 0 and 0.02, between 0.001 and 0.2, or between 0.01 and 0.02.

[0029] In some embodiments, the metal dopant (M) comprises a metal dopant selected from sodium (Na), magnesium (Mg), potassium (K), strontium (Sr), and combinations thereof. In some embodiments, "b" is at, near, up to, or near 0, 0.001, 0.005, 0.01, 0.02, 0.025, 0.03, 0.04, 0.05, 0.06, 0.07, 0.08, 0.09, 0.0995, 0.1, 0.11, 0.12, 0.13, 0.14, or 0.15, or any range of values ​​therebetween. For example, in some embodiments, "b" is a number between 0 and 0.15, between 0.001 and 0.10, between 0.01 and 0.05, between 0.005 and 0.25, or between 0.02 and 0.1.

[0030] In some embodiments, the Group 13 dopant (M') is selected from the group consisting of boron (B), aluminum (Al), and combinations thereof. In some embodiments, the Group 13 dopant M' c Al x B y (where c = x + y). In some embodiments, "x" is at, near, up to, or near 0, 0.001, 0.005, 0.01, 0.02, 0.04, 0.06, 0.08, 0.10, 0.12, 0.14, 0.16, 0.18, 0.20, 0.22, 0.24, 0.26, 0.28, or 0.3, or any range of values ​​therebetween. For example, in some embodiments, "x" is a number between 0 and 0.3, between 0.001 and 0.2, or between 0.05 and 0.02. In some embodiments, "y" is at, near, up to, or near about 0, 0.001, 0.005, 0.01, 0.02, 0.03, 0.04, 0.05, 0.06, 0.07, 0.08, 0.09, 0.0995, or 0.1, or any range of values ​​therebetween. For example, in some embodiments, "y" is a number between 0 and 0.1, 0.001 and 0.05, or 0.002 and 0.05. In some embodiments, "c" is at, near, 0, 0.001, 0.005, 0.01, 0.02, 0.05, 0.1, 0.15, 0.2, 0.25, 0.3, 0.35, or 0.4, or any range of values ​​therebetween. For example, in some embodiments, "c" is a number between 0.001 and 0.4, between 0.001 and 0.03, or between 0.001 and 0.02.

[0031] In some embodiments, "d" is at, near, at, or at most about 0, 0.0001, 0.001, 0.005, 0.01, 0.015, 0.02, 0.025, 0.03, 0.035, 0.04, or any range of values ​​therebetween. For example, in some embodiments, "d" is a number between 0 and 0.04, between 0.0001 and 0.03, or between 0.01 and 0.04, or between 0.01 and 0.03. In some embodiments, the anion dopant (X) is fluorine (F), chlorine (Cl), sulfate (SO4), or any other suitable anion dopant. 2- ), and combinations thereof. In some embodiments, the anion dopant is a halogen dopant. In some embodiments, the halogen dopant is selected from the group consisting of fluorine (F), chlorine (Cl), and combinations thereof. In some embodiments, "e" is at, near, up to, or near 0, 0.0001, 0.001, 0.005, 0.01, 0.015, 0.02, 0.025, 0.03, 0.035, 0.04, or any range of values ​​therebetween. For example, in some embodiments, "e" is a number between 0.0001 and 0.04, between 0.0001 and 0.03, or between 0.01 and 0.04, or between 0.01 and 0.03.

[0032] In some embodiments, the doped manganese-rich cathode active material has the formula Li (1+a) Na b Mn (2-c) Al x B y O (4-d) F e or LiNa b Mn2Al x B y O4F e The values ​​of "a," "b," "c," "x," "y," "d," and / or "e" are as discussed herein. In some embodiments, the doped manganese-rich cathode active material is 1.05 Na 0.05 Mn 1.82 Al 0.15 B 0.03 O3.98 F 0.02 This includes compounds having a chemical formula therein or thereabouts.

[0033] B. Forming a Doped Manganese-Rich Cathode Active Material The doped manganese-rich cathode active material is formed by thermal reaction (e.g., calcination) of precursor components including a lithium source, a dopant material, and a manganese source in various ordering and processing steps. In some embodiments, a one-step calcination method or a two-step calcination method is utilized to form the doped manganese-rich cathode active material disclosed herein.

[0034] In some embodiments, the method further comprises sieving after heating. In some embodiments, the process further comprises breaking down the doped manganese-rich cathode active material described herein. In some embodiments, breaking down comprises a step selected from the group consisting of crushing, grinding, and combinations thereof. In some embodiments, the process comprises treating the doped manganese-rich cathode active material described herein. In some embodiments, treating comprises a step selected from the group consisting of sieving, washing, filtering, drying, coating, and combinations thereof. In some embodiments, the manganese source is selected from the group consisting of manganese oxide, MnF2, and combinations thereof. In some embodiments, the manganese source comprises a manganese oxide such as Mn3O4. In some embodiments, the lithium source comprises a lithium salt. In some embodiments, the lithium salt is selected from the group consisting of LiOH, HO, Li2CO3, and combinations thereof. In some embodiments, the lithium source is Li2CO3.

[0035] In some embodiments, the dopant material is selected from the group consisting of a Group 13 dopant source, a metal dopant source, an anion dopant source, and combinations thereof. In some embodiments, the dopant material is a combination of a Group 13 dopant source, a metal dopant source, and an anion dopant source. In some embodiments, the anion dopant source is selected from the group consisting of MnF2, MgF2, MgCl2, AlF3, SrF2, NaF, NaCl, LiF, LiCl, KCl, K2SO4, and combinations thereof. In some embodiments, the anion dopant source is a halogen dopant source. In some embodiments, the halogen dopant source is selected from the group consisting of MnF2, MgF2, MgCl2, AlF3, SrF2, NaF, NaCl, LiF, LiCl, KCl, and combinations thereof. In some embodiments, the halogen dopant source is MnF2. In some embodiments, the metal dopant source is selected from the group consisting of KCl, K2SO4, NaF, NaCl, Na2CO3, MgF2, MgCO3, Mg(OH)2, SrF2, MgCl2, and combinations thereof. In some embodiments, the metal dopant source is Na2CO3. In some embodiments, the Group 13 dopant source is selected from the group consisting of H3BO3, Al(OH)3, and combinations thereof. In some embodiments, the Group 13 dopant source is H3BO3 and Al(OH)3.

[0036] In some embodiments, the molar ratios of the metal dopant source, the Group 13 dopant source, and the anion dopant source in the precursor component mixture before the final calcination step are calculated based on the intended formula of the cathode active material. In some embodiments, the precursor component mixture before the final calcination step is a doped cathode active material mixture from a single calcination process, as discussed herein. In some embodiments, the precursor component mixture before the final calcination step is a second doped cathode active material mixture before the second calcination step in a two-step calcination process, as discussed herein.

[0037] In some embodiments, the molar ratio of lithium:manganese in the precursor component mixture before the final calcination step is at or near 1:1.6, 1:1.65, 1:1.7, 1:75, 1:1.8, 1:1.85, 1:1.9, 1:2, 1:2.05, 1:2.1, 2:2.15, 1:2.2, or any range of values ​​therebetween. In some embodiments, the precursor component mixture before the final calcination step comprises, comprises, comprises up to, comprises, or comprises near 20 wt%, 25 wt%, 30 wt%, 35 wt%, 40 wt%, 45 wt%, or 50 wt% lithium source, or any range of values ​​therebetween.

[0038] In some embodiments, the precursor component mixture before the final baking step comprises, comprises about, comprises up to, or comprises about 1 mol%, 2 mol%, 3 mol%, 4 mol%, 5 mol%, 6 mol%, 7 mol%, 8 mol%, 9 mol%, 10 mol%, 12 mol%, 15 mol%, 17 mol%, 20 mol%, 22 mol%, 25 mol%, 20 mol%, 27 mol%, 35 mol%, 40 mol%, 45 mol%, or 50 mol% dopant material, or any range of values ​​therebetween.

[0039] In some embodiments, the precursor component mixture prior to the final calcination step includes, includes, includes up to, or includes up to about 0.1 mol%, 0.125 mol%, 0.25 mol%, 0.5 mol%, 0.75 mol%, 1 mol%, 1 mol%, 2 mol%, 3 mol%, 4 mol%, or 5 mol% of an anion dopant source (e.g., a halogen dopant source), or any range of values ​​therebetween. For example, in some embodiments, the precursor component mixture prior to the final calcination step includes 0.1-5 mol%, 1-5 mol%, or 1-2 mol% of an anion dopant source. In some embodiments, the amount of anion dopant source (e.g., MnF) is adjusted to account for the amount of MnF added during the production of the doped manganese-rich cathode active material or during the lithiation and delithiation steps. 3+The amount of HCl is within a range that does not substantially promote the formation of HCl, but achieves improved performance and extended cycle life.

[0040] In some embodiments, the precursor component mixture prior to the final calcination step includes, comprises, comprises up to, or comprises up to about 0.1 mol%, 0.5 mol%, 1 mol%, 2 mol%, 3 mol%, 4 mol%, 5 mol%, 7 mol%, 9 mol%, or 10 mol% of the metal dopant source, or any range of values ​​therebetween. For example, in some embodiments, the precursor component mixture prior to the final calcination step includes 0.1-10 mol%, 1-10 mol%, or 1-5 mol% of the anion dopant source. In some embodiments, the amount of the metal dopant source, such as Na2CO3, is within a range that does not substantially decrease the specific capacity of the LiMn2O4 cathode active material while achieving improved electrochemical performance.

[0041] 1. One-step baking method FIG. 1 illustrates an example of a single-step calcination method 100 for producing a doped active material for an electrode, such as a cathode, of an energy storage device. In the single-step calcination method 100, according to some embodiments, in step 102, a manganese source, a dopant material, and a lithium source are combined to form a doped cathode active material mixture. In some embodiments, combining the manganese source, the dopant material, and the lithium source includes mixing the manganese source, the dopant material, and the lithium source. In step 104, the doped cathode active material mixture is heated at a specific temperature to produce a doped manganese-rich cathode active material. In some embodiments, the single-step calcination method 100 further includes treating the heated doped cathode active material mixture to produce the doped cathode active material. In some embodiments, treating the heated doped cathode active material mixture includes a step selected from the group consisting of sieving, washing, filtering, drying, coating, and combinations thereof. In some embodiments, the single-step calcination method 100 further includes breaking down the doped manganese-rich cathode active material. In some embodiments, breaking down the doped manganese-rich cathode active material includes a step selected from the group consisting of crushing, grinding, and combinations thereof.

[0042] In some embodiments, the doped cathode active material mixture is heated after formation. In some embodiments, heating is performed at, near, at least at, or at a temperature of 550°C, 600°C, 625°C, 650°C, 675°C, 700°C, 725°C, 750°C, 760°C, 780°C, 800°C, 820°C, 840°C, 850°C, 860°C, 880°C, 900°C, 950°C, or 1000°C, or any range of values ​​therebetween. For example, in some embodiments, the temperature is between 550°C and 1000°C, between 600°C and 900°C, between 700°C and 900°C, or between 750°C and 850°C. In some embodiments, heating of the doped cathode active material mixture is performed in an oxidizing atmosphere. In some embodiments, the oxidizing atmosphere is an oxygen-containing atmosphere, such as air or an oxygen-rich atmosphere. In some embodiments, the oxygen-rich atmosphere comprises at least 21% oxygen by volume, at least 23.5% oxygen by volume, or at least 25% oxygen by volume. In some embodiments, the heating is carried out in ambient air. In some embodiments, the heating is carried out for, near, at least, or near a duration of 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 20, or 50 hours, or any range of values ​​therebetween.

[0043] 2. Two-stage baking method FIG. 2 illustrates an example of a two-step calcination method 200 for producing a doped active material for an electrode, such as a cathode, of an energy storage device. In the two-step calcination method 200, according to some embodiments, in step 202, a manganese source, a first dopant material, and a lithium source are combined to form a first doped cathode active material mixture. In some embodiments, combining the manganese source, the first dopant material, and the lithium source includes mixing the manganese source, the first dopant material, and the lithium source. In step 204, the first doped cathode active material mixture is heated at a first temperature. In step 206, the heated first doped cathode active material mixture is then combined with a second dopant material to form a second doped cathode active material mixture. In some embodiments, combining the first doped cathode active material mixture and the second dopant material includes mixing the first doped cathode active material mixture with the second dopant material. In step 208, the second doped cathode active material mixture is heated at a second temperature to produce a doped cathode active material. In some embodiments, the two-step calcination method 200 further includes treating the heated second doped cathode active material mixture. In some embodiments, treating the heated second doped cathode active material mixture may include a step selected from the group consisting of sieving, washing, filtering, drying, coating, and combinations thereof. In some embodiments, the two-step calcination method 200 further includes crushing the doped manganese-rich cathode active material. In some embodiments, crushing may include a step selected from the group consisting of crushing, grinding, and combinations thereof.

[0044] In some embodiments, the first dopant material is selected from the group consisting of a Group 13 dopant source, an anion dopant source, and combinations thereof. In some embodiments, the second dopant material comprises a metal dopant source.

[0045] In some embodiments, the first doped cathode active material mixture is heated after formation at a first temperature. In some embodiments, the first temperature is at, near, or at least near 550°C, 600°C, 625°C, 650°C, 675°C, 700°C, 725°C, 750°C, 760°C, 780°C, 800°C, 820°C, 840°C, 850°C, 860°C, 880°C, 900°C, 950°C, or 1000°C, or any range of values ​​therebetween. For example, in some embodiments, the first temperature is between 550°C and 1000°C, between 600°C and 900°C, between 700°C and 900°C, or between 750°C and 850°C. In some embodiments, heating the first doped cathode active material mixture is performed in an oxidizing atmosphere. In some embodiments, the oxidizing atmosphere is an oxygen-containing atmosphere, such as air or an oxygen-rich atmosphere. In some embodiments, the oxygen-rich atmosphere comprises at least 21% oxygen by volume, at least 23.5% oxygen by volume, or at least 25% oxygen by volume. In some embodiments, the heating of the first doped cathode active material mixture is carried out in ambient air. In some embodiments, the heating of the first doped cathode active material mixture is carried out for, near, at least, or at least near a duration of 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 20, or 50 hours, or any range of values ​​therebetween.

[0046] In some embodiments, the second doped cathode active material mixture is heated at a second temperature after formation. In some embodiments, the second temperature is at, near, or at least near 450°C, 500°C, 525°C, 550°C, 575°C, 600°C, 625°C, 650°C, 660°C, 680°C, 700°C, 720°C, 740°C, 750°C, 760°C, 780°C, 800°C, 850°C, or 900°C, or any range of values ​​therebetween. For example, in some embodiments, the first temperature is between 450°C and 900°C, between 600°C and 800°C, between 650°C and 750°C, or between 625°C and 720°C. In some embodiments, heating the second doped cathode active material mixture is performed in an oxidizing atmosphere. In some embodiments, the oxidizing atmosphere is an oxygen-containing atmosphere, such as air or an oxygen-rich atmosphere. In some embodiments, the oxygen-rich atmosphere comprises at least 21% oxygen by volume, at least 23.5% oxygen by volume, or at least 25% oxygen by volume. In some embodiments, the heating of the second doped cathode active material mixture is carried out in ambient air. In some embodiments, the heating of the second doped cathode active material mixture is carried out for, near, at least, or at least near a duration of 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 20, or 50 hours, or any range of values ​​therebetween.

[0047] In some embodiments, the second temperature is different from the first temperature. In some embodiments, the second temperature is lower than the first temperature. In some embodiments, the second temperature is about 50° C., about 100° C., about 150° C., or about 200° C. lower than the first temperature, or any value therebetween.

[0048] C. Energy Storage Devices The doped manganese-rich cathode active material can be used to fabricate electrodes for energy storage devices. In some embodiments, an electrode film (e.g., a doped manganese-rich electrode film) comprises the doped manganese-rich cathode active material. In some embodiments, an electrode comprises a current collector and an electrode film. In some embodiments, the electrode is a cathode electrode.

[0049] In some embodiments, an energy storage device includes an electrode described herein. In some embodiments, the energy storage device includes a separator, an anode electrode, a cathode electrode, and a housing, where the separator, anode electrode, and cathode electrode are disposed within the housing, and the separator is located between the anode electrode and the cathode electrode. In some embodiments, the energy storage device is formed by enclosing the separator, anode electrode, and cathode electrode within the housing, and enclosing the separator between the anode electrode and the cathode electrode. In some embodiments, the energy storage device is a battery. In some embodiments, the energy storage device is a lithium-ion battery.

[0050] In some embodiments, after formation of an energy storage device and cycling a certain number of cycles, the amount of Mn dissolution from the doped manganese-rich cathode active material disclosed herein is less than the amount of Mn dissolution from the control manganese-rich cathode active material. In some embodiments, the amount of Mn dissolution from the doped manganese-rich cathode active material disclosed herein is 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 70%, or 80% less than the amount of Mn dissolution from the control manganese-rich cathode active material, or any range of values ​​therebetween, at or near, or at least near, that percentage. In some embodiments, the control manganese-rich cathode active material can be an Al and B doped LiMnO material. In some embodiments, the control manganese-rich cathode active material can be a LiMnO material. 1.11 Mn 1.88 Al 0.088 B0.024 It has a formula of O4.

[0051] The amount of metal dopant source is within a range that does not substantially decrease the specific capacity of the LiMn2O4 cathode material, while achieving improved electrochemical performance. In some embodiments, such a metal dopant source may be Na2CO3.

[0052] Additionally, in some embodiments, at least some amount of the anion dopant remains as a robust coating on the surface of the formed doped manganese-rich cathode active material. In some embodiments, the amount of the anion dopant source is adjusted to a level that is sufficient to remove Mn, which may cause additional Mn dissolution via disproportionation reactions. 3+ In some embodiments, such an anion dopant source is MnF2, while not substantially promoting the formation of MnF2, and is within a range that achieves the intended flux and surface coating effects. [Example]

[0053] Illustrative embodiments of the present disclosure, including processes, materials and / or resulting products, are described in the following examples.

[0054] Example 1 - Doped Manganese-Rich Cathode Active Material Doped manganese-rich cathode active materials doped with various dopants were prepared by the one-step and two-step firing methods as disclosed herein.

[0055] In the one-step calcination method, Li2CO3, Mn3O4, Al(OH)3, H3BO3, MnF2, and Na2CO3 powders were mixed in a molar ratio of 0.525:0.61:0.03:0.01:0.025 to form a manganese-rich cathode active material mixture. The manganese-rich cathode active material mixture was heated to 800°C in air at a heating rate of 3°C / min and sintered at 800°C in air for 5 hours. The sintered manganese-rich cathode active material mixture was then cooled to room temperature and sieved to produce a doped manganese-rich cathode active material (MnF2 / Na2CO3-doped manganese-rich cathode active material). The produced MnF2 / Na2CO3-doped manganese-rich cathode active material contained Li 1.05 Na 0.05 Mn 1.82 Al 0.15 B 0.03 O 3.98 F 0.02 It has the formula:

[0056] Other doped manganese-rich cathode active materials, such as those using MgF, NaCO, Al(OH), HBO as dopant materials (MgF / NaCO doped manganese-rich cathode active material), or those using NaF, NaCO, Al(OH), HBO as dopant materials (NaF / NaCO doped manganese-rich cathode active material), were also prepared using the one-step calcination method as discussed above by replacing the anion dopant source MnF with MgF or NaF.

[0057] In the two-step calcination method, a lithium source, a manganese source, and a dopant material other than a metal dopant source were mixed in a molar ratio calculated based on the formula of the intended doped manganese-rich cathode active material to form a first mixture. The first mixture was heated to a first temperature of approximately 800°C at a heating rate of 3°C / min and sintered in air at the first temperature for approximately 5 hours. The sintered first mixture was then cooled to room temperature. The sintered first mixture was mixed with a metal dopant source, such as Na2CO3, in a molar ratio calculated based on the formula of the intended doped manganese-rich cathode active material to form a second mixture. The second mixture was heated to a second temperature of 700°C at a heating rate of 3°C / min and sintered in air at the second temperature for approximately 5 hours. The sintered second mixture was then cooled to room temperature and sieved.

[0058] In this example, LiCO 3、 MnO, Al(OH), HBO, and MnF were first mixed to form a first mixture, which was heated to 800°C at a heating rate of 3°C / min and sintered in air at 800°C for approximately 5 hours. The sintered first mixture was then mixed with NaCO to form a second mixture, which was heated to 700°C at a heating rate of 3°C / min and sintered in air at 700°C for approximately 5 hours. The sintered second mixture was then sieved to produce the MnF / NaCO-doped manganese-rich cathode active material.

[0059] Other doped manganese-rich cathode active materials, including NaF / Na2CO3-doped manganese-rich cathode active materials, were also prepared using the two-step calcination method by replacing the anion dopant source MnF2 with MgF2 or NaF.

[0060] The fabricated doped manganese-rich cathode active material is Li 1.05 Na 0.05 Mn 1.82 Al 0.15 B 0.03 O 3.98 F 0.02 It had the formula:

[0061] Example 2 - Single-Step Fired Active Material and Electrochemical Cell A doped manganese-rich cathode active material was prepared using a method similar to the one-step calcination method described in Example 1. A cathode electrode was fabricated by providing a doped manganese-rich cathode active material, which was mixed with polyvinylidene fluoride (PVDF) and Super-S carbon black in N-methyl-2-pyrrolidone (NMP) in a 95:2.5:2.5 wt.% ratio to form a slurry. The slurry was cast onto a piece of aluminum foil and then dried in an oven at 120°C for 3 hours. The dried slurry was then calendered at a pressure of 2000 atm to obtain a loading of 30 mg / cm. 2 A 5.3 x 5.3 cm pouch cell electrode was punched out of the bulk electrode material, and the electrode was dried in vacuum at 120°C for 14 hours.

[0062] The anode electrode was fabricated by mixing the anode active material, carboxymethyl cellulose (CMC), and styrene butadiene rubber (SBR) in a 97:1.5:1.5 wt.% ratio to form a slurry. The slurry was cast onto a piece of copper foil and then dried in an oven at 80°C for 3 hours. The dried slurry was then calendered at a pressure of 2000 atm to achieve a loading of 10 mg / cm. 2 A 5.5 x 5.5 cm pouch cell electrode was punched out of the bulk electrode material, and the electrode was dried under vacuum at 80°C for 14 hours.

[0063] Full cells (i.e., pouch cells) with cathode electrodes containing doped manganese-rich cathode active materials were fabricated and tested. The cathode electrodes for the full cells were fabricated in a manner similar to that described above. The full cells were fabricated by stacking the cathode electrode, separator, and anode electrode together to form an electrode stack. The electrode stack was placed in a pouch filled with lithium hexafluorophosphate electrolyte. The electrolyte was formed by dissolving 1.2 M lithium hexafluorophosphate electrolyte in a 3:7 EC / DMC solution.

[0064] The full cell was maintained at 55°C during testing. The full cell was first charged to 1.7 V at a constant C / 20 rate, held for 4 hours, then charged to 4.05 V at a constant C / 5 rate, rested for 12 hours, then charged to 4.2 V at a C / 20 rate, and discharged to 2.5 V at a C / 20 rate. The full cell is considered "formed" after these initial charge and discharge steps. A reference performance test (RPT) was then performed. The full cell was charged to 4.2 V at a C / 20 rate and then discharged to 2.5 V. The full cell was then charged to 4.2 V at a C / 2 rate. The direct current resistance (DCR) was then checked every 10% of the state of charge ("SOC") with a C / 2 discharge pulse, followed by a 5-minute rest period to 3.0 V for 30 seconds. The full cell was then cycled between 2.85 and 4.20 V at a constant C / 3 rate.

[0065] 3A and 3B are plots showing the actual and normalized cycling performance of full cells containing MgF / NaCO-doped, MnF / NaCO-doped, and NaF / NaCO-doped LiMnO cathode active materials prepared using the single-step calcination method disclosed herein. As can be seen in FIG. 3A, the initial average capacity of all doped LiMnO cathode active materials exceeds 345 mWh / g. The initial capacity of the MnF / NaCO-doped LiMnO cathode active material exceeds 365 mWh / g. As can be seen in FIGS. 3A and 3B, the energy retention of all doped LiMnO cathode active materials after 50 cycles exceeds 93%. The average energy retention of the NaF / NaCO-doped LiMnO cathode active material after 50 cycles exceeds 94%.

[0066] Example 3 - Two-Step Calcined Active Materials and Electrochemical Cells A doped manganese-rich cathode active material was prepared using a method similar to the two-step calcination method described in Example 1. A cathode electrode was fabricated using a method similar to that described in Example 2.

[0067] Full cells (i.e., pouch cells) having cathode electrodes comprising doped manganese-rich cathode active materials formed by the two-step calcination method were fabricated and tested using methods and test conditions similar to those described in Example 2.

[0068] Figures 4A and 4B are plots showing the actual and normalized cycling performance of full cells containing MgF / NaCO-doped, MnF / NaCO-doped, and NaF / NaCO-doped LiMnO cathode active materials prepared using the two-stage calcination method. As can be seen in Figure 4A, the initial average capacity of all doped LiMnO cathode active materials exceeds 340 mWh / g. The initial average energy of the MgF / NaCO-doped LiMnO cathode active material exceeds 355 mWh / g. As can be seen in Figures 4A and 4B, the average energy retention of all doped LiMnO cathode active materials after 30 cycles exceeds 96%. The average energy retention of the MnF / NaCO-doped LiMnO cathode active material after 30 cycles exceeds 96.5%.

[0069] Example 4 - Doped and Control Cathode Active Material Electrochemical Cells Doped manganese-rich cathode active materials were prepared using methods similar to those described in Example 1. The control cathode active material was Li 1.11 Mn 1.88 Al 0.088 B 0.024 The halogen-doped manganese-rich cathode active material and the control cathode active material were used to prepare cathode electrodes using a method similar to that described in Example 2.

[0070] Full cells (i.e., pouch cells) having cathode electrodes containing the doped manganese-rich cathode active material and the control cathode active material were fabricated and tested using methods and test conditions similar to those described in Example 2.

[0071] Figures 5A and 5B are plots showing the actual and normalized cycling performance of full cells containing MnF / NaCO-doped LiMnO cathode active material (labeled "in-house produced") and control cathode active material (labeled "commercially available"). As can be seen in Figures 5A and 5B, the energy retention of the cell with the MnF / NaCO-doped LiMnO cathode active material after 50 cycles is higher than that of the cell with the control cathode active material. Thus, the doped manganese-rich cathode active material exhibits improved energy retention and longer cycle life compared to the manganese-rich cathode active material without metal and anion dopants.

[0072] Example 5 - Measurement of manganese dissolution Doped manganese-rich cathode active materials were prepared using methods similar to those described in Example 1. The control cathode active material was Li 1.11 Mn 1.88 Al 0.088 B 0.024 The doped manganese-rich cathode active material and the control cathode active material were used to fabricate cathode electrodes using a method similar to that described in Example 2.

[0073] Full cells (i.e., pouch cells) having cathode electrodes containing the doped manganese-rich cathode active material and the control cathode active material were fabricated using a method similar to that described in Example 3. The full cells were formed at 55°C.

[0074] After formation, the full cells were disassembled, and the amount of Mn deposited on the anode was measured by inductively coupled plasma mass spectrometry (ICP-MS). The amounts of Mn on the anode of cells with different cathode active materials, normalized to the total amount of LMO in the pouch cells, are listed in Table 1. The amounts of Mn on the anode of cells with doped cathode active materials formed by the one-step calcination method using MgF2 and Na2CO3 as dopant sources, MnF2 and Na2CO3 as dopant sources, and NaF and Na2CO3 as dopant sources are 227, 161, and 167 ppm per gram of LiMn2O4, respectively. The amount of Mn on the anode of a cell having doped cathode active materials formed by the two-step calcination process using MgF and NaCO as dopant sources and using MnF and NaCO as dopant sources is 165 and 128 ppm per gram of LiMnO, respectively. In contrast, the amount of Mn on the anode of a cell using a control cathode active material is about 231 ppm per gram of LiMnO. Thus, Mn dissolution is significantly reduced using the doped cathode active materials disclosed herein.

[0075] The reduction in Mn content measured in the cell anode demonstrates reduced Mn dissolution from the spinel LiMn2O4 (LMO) cathode active material. This reduction in Mn dissolution from the spinel LiMn2O4 may help reduce the risk of cell formation and soft shorts during cycling. Reduced Mn dissolution may also help improve cycle life. [Table 1]

[0076] While specific embodiments have been described, these embodiments are presented by way of example and are not intended to limit the scope of the present disclosure. Indeed, the novel methods and systems described herein may be embodied in a variety of other forms. Furthermore, various omissions, substitutions, and modifications of the systems and methods described herein may be made without departing from the spirit of the present disclosure. The appended claims and their equivalents are intended to cover such forms or modifications as would fall within the scope and spirit of the present disclosure.

[0077] It should be understood that features, materials, properties, or groups described in connection with a particular aspect, embodiment, or example are applicable to any other aspect, embodiment, or example described in this section or elsewhere in this specification, except where incompatible therewith. All features disclosed in this specification (including the accompanying claims, abstract, and drawings), and / or all steps of any method or process so disclosed, may be combined in any combination, except combinations in which at least some of such features and / or steps are mutually exclusive. Protection is not limited to the details of any foregoing embodiment. Protection extends to any novel, or any novel combination of, features disclosed in this specification (including the accompanying claims, abstract, and drawings), or any novel, or any novel combination of steps of any method or process so disclosed.

[0078] Furthermore, certain features described in this disclosure in the context of separate embodiments can also be implemented in combination in a single embodiment. Conversely, various features described in the context of a single embodiment can also be implemented in multiple embodiments separately or in any suitable subcombination. Furthermore, while features may be described above as acting in a particular combination, one or more features from a claimed combination can, in some cases, be deleted from the combination, and the combination can be claimed as a subcombination or a variation of the subcombination.

[0079] Furthermore, while operations may be shown in the figures or described herein in a particular order, such operations need not be performed in the particular order shown, or in sequential order, or even all operations need to be performed to achieve desirable results. Other operations not shown or described may be incorporated into the example methods and processes. For example, one or more additional operations may be performed before, after, simultaneously with, or between any of the described operations. Furthermore, operations may be rearranged or reordered in other implementations. Those skilled in the art will appreciate that in some embodiments, the actual steps performed in the illustrated and / or disclosed processes may differ from those shown in the figures. Depending on the implementation, certain of the above steps may be omitted, and other steps may be added. Furthermore, the features and attributes of the specific embodiments disclosed above can be combined in different ways to form additional embodiments, all of which are within the scope of the present disclosure. Similarly, the separation of various system components in the above implementations should not be understood to require such separation in all implementations, and it should be understood that the described components and systems may generally be integrated together in a single product or packaged in multiple products. For example, any of the components of the energy storage systems described herein can be provided separately or integrated together (e.g., packaged together or mounted together) to form an energy storage system.

[0080] For purposes of this disclosure, certain aspects, advantages, and novel features are described herein. Not all such advantages may necessarily be achieved in accordance with any particular embodiment. Thus, for example, one skilled in the art will recognize that the present disclosure may be embodied or implemented to achieve one advantage or group of advantages as taught herein without necessarily achieving other advantages as may be taught or suggested herein.

[0081] Conditional language such as "can," "could," "might," or "may," unless specifically stated otherwise or understood otherwise within the context in which it is used, is generally intended to convey that certain embodiments include certain features, elements, and / or steps, while other embodiments do not. Thus, such conditional language does not generally imply that the features, elements, and / or steps are somehow required by one or more embodiments, or that one or more embodiments necessarily include logic for determining whether those features, elements, and / or steps should be included in or performed in any particular embodiment, with or without user input or prompting.

[0082] Conjunctive language such as the phrase "at least one of X, Y, and Z," unless specifically stated otherwise, is understood otherwise by the context in which it is generally used to convey that an item, term, etc. can be either X, Y, or Z. Thus, such conjunctive language does not generally imply that a particular embodiment requires the presence of at least one of X, at least one of Y, and at least one of Z.

[0083] As used herein, language of degree, such as the terms "approximately," "about," "generally," and "substantially," refers to a value, amount, or characteristic that is close to a stated value, amount, or characteristic that still performs a desired function or achieves a desired result. For example, the terms "approximately," "about," "generally," and "substantially" can refer to an amount that is less than 10%, less than 5%, less than 1%, less than 0.1%, and less than 0.01% of the stated amount, depending on the desired function or desired result.

[0084] The scope of the present disclosure is not limited by the specific disclosure of embodiments in this section or elsewhere herein, but may be defined by the claims, as presented in this section or elsewhere herein, or as presented in the future. Claim language is to be interpreted broadly based on the language used in the claims, and not limited to the examples set forth herein or during prosecution of an application; examples are to be construed as non-exclusive.

[0085] While specific embodiments have been described, these embodiments are presented by way of example only and do not limit the scope of the present disclosure. Indeed, the novel methods and systems described herein may be embodied in a variety of other forms. Furthermore, various omissions, substitutions, and modifications of the systems and methods described herein may be made without departing from the spirit of the present disclosure. The appended claims and their equivalents are intended to cover such forms or modifications as fall within the scope and spirit of the present disclosure. Accordingly, the scope of the present invention is defined solely by reference to the appended claims.

Claims

1. Chemical formula Li （１＋ａ） M ｂ Mn （２－ｃ） M´ ｃ O （４－ｄ） X ｅ (in the formula, M is a metal dopant; M' is a Group 13 dopant; X is an anion dopant; a is a value between 0 and 0.2; b is a value between 0.01 and 0.1; c is a value between 0 and 0.2; d is a value between 0 and 0.04, and e is a value between 0.001 and 0.

04.

2. 10. The doped cathode active material of claim 1, wherein M is selected from the group consisting of K, Na, Mg, Sr, and combinations thereof.

3. 3. The doped cathode active material of claim 1, wherein X is a halogen dopant.

4. X is F, Cl, SO ４ 3. The doped cathode active material of claim 1, wherein the doped cathode active material is selected from the group consisting of:

5. 5. The doped cathode active material of claim 1, wherein M' is selected from the group consisting of B, Al, and combinations thereof.

6. M' ｃ Al ｘ B ｙ 6. The doped cathode active material of claim 1, wherein c=x+y.

7. The compound has the formula Li （１＋ａ） Na ｂ Mn （２－ｃ） Al ｘ B ｙ O （４－ｄ） F ｅ 7. The doped cathode active material of claim 6, having the formula:

8. The compound has the formula Li １．０５ Na ０．０５ Mn １．８２ Al ０．１５ B ０．０３ O ３．９８ F ０．０２ 8. The doped cathode active material of claim 7, having the formula:

9. A cathode electrode film comprising the doped cathode active material of claim 1 and a binder.

10. A cathode electrode comprising the cathode electrode film of claim 9 disposed on a current collector.

11. The cathode electrode according to claim 10; A separator; an anode electrode; Electrolytes, Housing and 1. An energy storage device comprising: The energy storage device, wherein the cathode electrode, the separator, and the anode electrode are located within the housing.

12. The energy storage device of claim 11 , wherein the energy storage device is a battery.

13. combining a manganese source, a dopant material, and a lithium source to form a doped cathode active material mixture; heating the doped cathode active material mixture to form a doped cathode active material; forming a doped cathode active material comprising:

14. The lithium source is LiOH, Li ２ CO ３ 14. The process of claim 13, wherein the cation is selected from the group consisting of LiF, LiCl, and combinations thereof.

15. The manganese source is Mn ３ O ４ , MnF ２ 15. The process of claim 13 or 14, wherein the hydroxyl group is selected from the group consisting of:

16. 16. The process of any one of claims 13 to 15, wherein the dopant material is selected from the group consisting of a Group 13 dopant source, a metal dopant source, an anion dopant source, and combinations thereof.

17. The anion dopant source is MnF ２ , MgF ２ , MgCl ２ , AlF ３ , SrF ２ , NaF, NaCl, LiF, LiCl, KCl, K ２ SO ４ 17. The process of claim 16, wherein the hydroxyl group is selected from the group consisting of:

18. The metal dopant source is KCl, K ２ SO ４ , NaF, NaCl, Na ２ CO ３ , MgF ２ , MgCO ３ , Mg(OH) ２ , SrF ２ , MgCl ２ 18. The process of claim 16 or 17, wherein the hydroxyl group is selected from the group consisting of:

19. The Group 13 dopant source is H ３ BO ３ , Al(OH) ３ 19. The process of any one of claims 16 to 18, wherein the hydroxyl group is selected from the group consisting of:

20. The dopant material is H ３ BO ３ , Al(OH) ３ , MnF ２ and Na ２ CO ３ 20. The process of any one of claims 13 to 19, comprising:

21. The process of any one of claims 13 to 20, wherein the doped cathode active material mixture is heated to about 700°C to 900°C.

22. The process of any one of claims 13 to 21, wherein the doped cathode active material mixture is heated in ambient air for about 4 to 6 hours.

23. forming a doped cathode active material; combining a manganese source, a first dopant material, and a lithium source to form a first doped cathode active material mixture; heating the first doped cathode active material mixture at a first temperature; combining the heated first doped cathode active material mixture with a second dopant material to form a second doped cathode active material mixture; heating the second doped cathode active material mixture at a second temperature different from the first temperature to form the doped cathode active material; A process including:

24. 24. The process of claim 23, wherein the first dopant material is selected from the group consisting of a Group 13 dopant source, an anion dopant source, and combinations thereof.

25. 25. The process of claim 23 or 24, wherein the second dopant material comprises a metal dopant source.

26. 26. The process of any one of claims 23 to 25, wherein the second temperature is lower than the first temperature.

27. 27. The process of any one of claims 23 to 26, wherein the first temperature is between about 700°C and 900°C.

28. 28. The process of any one of claims 23 to 27, wherein the second temperature is between about 600°C and 800°C.

29. 29. The process of any one of claims 23 to 28, further comprising the step of sieving the heated second doped cathode active material mixture.

Images