Method for producing positive electrode materials for rechargeable lithium batteries

Abstract

The present invention provides a method for producing high-capacity cathode materials for use in rechargeable lithium batteries. Conventional methods for producing lithium mixed-metal oxide cathode materials typically produce large amounts of effluent that must be treated before discharge. The present method uses mixed metals as feedstocks for wet chemical reactions to create high-quality precursors that can be used to prepare high-quality cathode materials after lithiation. An important feature is that the precursor preparation method recycles most of the aqueous solutions used in the wet chemical reactions back into the reactor, so the overall method produces little or no effluent during the production of the cathode precursor material.

Description

[Technical field]

[0001] (CROSS REFERENCE TO RELATED APPLICATIONS) This application claims the benefit of priority to U.S. Provisional Application No. 62 / 899,677, filed September 12, 2019, the entirety of which is incorporated by reference herein for all purposes.

[0002] The present invention relates to a method for producing a cathode material for rechargeable lithium (Li) batteries, and the cathode material produced thereby. In particular, the method provided relates to the relatively emission-free production of such cathode materials when compared to current industrial methods. [Background technology]

[0003] Description of the Prior Art Rechargeable Li-ion batteries have been used as energy storage elements in several different types of devices. These devices include mobile phones, portable computers, wireless power tools, and hybrid and pure electric vehicles. In recent years, the demand for high-power Li-ion batteries has increased dramatically, especially with the rapid market growth of electric vehicles. The main components of a lithium-ion battery include an anode, a cathode, and an electrolyte. During charge-discharge cycles, lithium ions shuttle between the anode active material and the cathode active material via the electrolyte. Due to its limited specific capacity and high manufacturing and raw material costs, the cathode active material is usually the most expensive component in a Li-ion battery. Therefore, the selection of the cathode active material is a key step to improve the performance and reduce the cost of Li-ion batteries.

[0004] Currently, lithium mixed metal oxides, most of which contain nickel, cobalt, manganese, and / or aluminum along with other necessary dopants, are the primary components used in the manufacture of high performance active cathode materials. Demand for and production of such materials continues to increase significantly.

[0005] Current industrial methods for producing these high performance cathode materials, such as lithium mixed metal oxides, include two main steps. The first step is the precursor production step, and the second step is the lithiation step. The precursor step begins with the use of mixed metal sulfates that are dissolved in water to form an aqueous solution. However, these methods can emit undesirable emissions. Summary of the Invention

[0006] The above-mentioned advantages, as well as other objects and aims inherent therein, are provided at least in part or in whole by the method of the present invention, as set forth hereinafter.

[0007] One embodiment of the present invention is a method for producing cathode materials for batteries, such as lithium ion batteries, that reduces the amount of toxic or hazardous emissions from currently known methods for making lithium mixed metal oxides. It would therefore be desirable to provide a suitable method that generates little or no emissions. In one embodiment, the method provides a system in which essentially the entire liquid portion from the reaction is fully recycled or can be recycled back into the reaction system without significant treatment. Moreover, the method may require little or no need to evaporate water and / or decompose organics or nitrates during a final high temperature treatment / calcination process.

[0008] One embodiment is a method for producing a positive electrode active material, the method comprising the steps of: providing an aqueous solution having a pH greater than 7; adding a first metal to the aqueous solution to form a reaction solution, wherein the first metal is selected from the group consisting of nickel, manganese, cobalt, aluminum, magnesium, and combinations thereof; adding an oxidant and a second metal to a reaction solution to form a product solution, where the second metal is selected from at least two elements from the group consisting of nickel, manganese, cobalt, aluminum, magnesium, zirconium, yttrium, titanium, vanadium, molybdenum, and combinations thereof, where the product solution comprises a cathode active material precursor, and where the cathode active material precursor product comprises a first metal and a second metal, where the first metal and the second metal are not the same; and isolating the positive electrode active material precursor from at least a portion of the product solution, thereby forming a filtrate.

[0009] Another embodiment provides a chemical method for producing lithium mixed metal oxides as active cathode materials for use in rechargeable lithium batteries. The method involves two major steps: a wet chemical method to fabricate the precursors, and a solid-state reaction called "lithiation" to produce the final cathode material.

[0010] One embodiment of the present invention provides a method for producing lithium mixed metal oxides as active cathode materials for use in the manufacture of lithium ion batteries using two main steps: a precursor preparation step and a lithiation step, wherein:

[0011] (A) In the precursor preparation step, selected metals in their metallic form are added to a stirred reaction system containing a mixture of solid metal particles and mixed metal hydroxide particles in aqueous solution along with a selected oxidant or oxidants, and selected metal nitrates and nitic acid, which are also introduced into the reactor, to effect oxidation of the metal particles under alkaline conditions, where the overall oxidation reaction is represented by the following equation: xMe+yMe´(NO3) n +zHNO3+(0.25xm-2yn-2z)O2+(0.5xm+2yn+z)H2O→Me x Me´ y (OH) (xm+yn) +(yn+z)NH3 where Me represents at least one metal in metallic form selected from the group consisting of nickel, manganese, cobalt, aluminum, and magnesium; Me' represents at least one metal in its ionic form selected from the group consisting of nickel, manganese, cobalt, aluminum, magnesium, zirconium, yttrium, titanium, vanadium, and molybdenum; Me x Me´ y (OH) (xm+yn) represents the precursor product; x and y are the molar fractions of metals Me and Me', respectively; m is the molar weighted average chemical value of mixed metals Me in the precursor product; n is the molar weighted average chemical value of mixed metals Me' in ionic form in the reactant; z is the molar fraction of HNO3 introduced into the reaction system; xm≧8yn+8z, x+y=1, 1≧x>0, y≧0, z≧0. Wherein, the slurry obtained from the oxidation reaction is taken out of the reactor, the unreacted raw metals are removed from the slurry and recycled to the reaction system with or without a reactivation treatment using nitric acid and / or a combination of nitric acid and ammonia / ammonium, followed by solid-liquid separation, where the recovered solid material is used as the precursor product and the liquid material is directly recycled to the reaction system without any treatment. And

[0012] (B) In the lithiation step, the recovered precursor product is mixed with a lithium-containing compound and optionally other dopants to produce a final mixture, which is then calcined to obtain the active cathode material.

[0013] In one embodiment, the raw materials, which may be mostly in metallic form, are introduced into the reaction system. The reaction system typically comprises at least one stirred mixing tank and a reactor, which may be equipped with a magnetic separation device to remove and recycle the unreacted raw materials. To keep the raw materials active during the reaction, a reactivation step may be provided before recycling the unreacted raw materials. Oxidizing agents such as oxygen and / or nitrates are introduced into the reaction system to cause oxidation of the metals. After the reaction, a solid-liquid separation operation is performed. The liquid portion may be recycled to the reaction system and the solid portion is recovered as the precursor material. An artificial solution having essentially the same or similar composition as the filtrate may be prepared and used to start the reaction until a suitable filtrate is produced from the filtration system and then recycled to the reaction system.

[0014] In the lithiation step, the precursor material prepared above is mixed with a lithium-containing compound and optionally other dopants, followed by a calcination process, followed by additional surface treatments if necessary, to obtain the final active cathode material.

[0015] Thus, embodiments of the present invention provide a system and method for making lithium mixed metal oxides with little or no emissions production, i.e., the system may allow for the complete recycling of essentially the entire liquid portion from the reaction back into the reaction system without any treatment.

[0016] In an additional aspect, the method of the present invention can be carried out in a batch process, but can also be carried out in an essentially continuous process, as described below.

[0017] In another embodiment, the present invention also provides a cathode material precursor product, where suitable cathode material precursors are produced, and these precursors are produced in a stable, continuous process in a one-step reaction system in the manner described herein. This embodiment also includes the final cathode active material when produced by the methods described herein with respect to the present invention, and cathodes produced therefrom.

[0018] In a third aspect, the present invention also provides a battery, wherein the positive electrode of the battery is manufactured by the chemical method described above with respect to the embodiments of the present invention. [Brief description of the drawings]

[0019] Embodiments will now be demonstrated using the following non-limiting examples and with reference to the accompanying drawings.

[0020] [Figure 1] FIG. 1 is an SEM image of a sample recovered from Example 1, which uses nitrate and acetate as anions in the reaction system.

[0021] [Diagram 2] FIG. 13 is an SEM image of a sample recovered from Example 2, which uses only nitrate as the anion in the reaction system.

[0022] [Diagram 3] 1 is a graph of Oxidation-Reduction Potential (ORP) as a function of time for the results of Example 3. The graph shows the Oxidation-Reduction Potential (ORP) as a function of time after introducing metal powders into the filtrate, curve 1 for an inactive metal powder and curve 2 for the same metal powder as curve 1 but reactivated by using ammonium nitrate.

[0023] It should be expressly understood, however, that the examples and figures are for illustrative purposes only and are not intended to necessarily limit the scope of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0024] The embodiments relate to a method for the manufacture of positive electrode materials for energy storage devices, particularly lithium ion batteries, where the method improves and / or solves the emissions issues typically associated with lithium metal oxide fabrication. Thus, the described method produces little or no emissions, and essentially the entire liquid portion from the reaction may be fully recycled back into the reaction system without any significant treatment. Such a system is further advantageous since it requires little or no need to evaporate water and / or decompose organics or nitrates during a final high temperature treatment / calcination process.

[0025] It is well known that metal oxides or hydroxides can be formed from corrosion processes, for example, metal oxidation in aqueous solutions or hydrous conditions. This principle may be used in a first step to produce precursor materials from pure metals, where the metal corrosion / oxidation reaction and the co-precipitation reaction occur simultaneously in the same reactor. The overall reaction is shown in the following equation: xMe+yMe´(NO3) n +zHNO3+(0.25xm-2yn-2z)O2+(0.5xm+2yn+z)H2O→Me x Me´ y (OH) (xm+yn) +(yn+z)NH3 where Me represents at least one metal, preferably in metallic form, selected from the group consisting of nickel, manganese, cobalt, aluminum, and magnesium; Me' represents at least one metal, preferably in ionic form, selected from the group consisting of nickel, manganese, cobalt, aluminum, magnesium, zirconium, yttrium, titanium, vanadium, and molybdenum; Me x Me´ y (OH) (xm+yn)represents the precursor product; x and y are the molar fractions of metals Me and Me', respectively, where m is the molar weighted average chemical value of the mixed metals Me in the precursor product, n is the molar weighted average chemical value of the mixed metals Me' in ionic form in the reactant, and z is the molar fraction of HNO3 introduced into the reaction system, where xm≧8yn+8z, x+y=1, 1≧x>0, y≧0, and z≧0.

[0026] Oxygen may be used as an oxidizing agent since, when used, it typically does not produce any significant by-products during the reaction. Oxygen may be provided either as a pure oxygen source and / or as oxygen contained in other gases, such as oxygen in air.

[0027] Some metal nitrates may be included for use with elements that do not readily react with oxygen or for elements that are not easily handled during processing operations such as during stirring for uniform mixing or during magnetic separation of their metallic forms.

[0028] Nitric acid can be used as an additional oxidizing agent and for baffle purposes to slow down the co-precipitation reaction of metal nitrates. Nitrate acid or its combination with ammonia can also be used to reactivate recycled raw materials. Ammonia is the only by-product when nitrate and nitric acid are used. However, the produced ammonia is in gas form and does not remain in the reaction system during operation. Therefore, in the above wet chemical method for making precursors, no additional or new chemicals are added to the liquid after solid-liquid separation occurs. Therefore, the liquid can be directly recycled to the reaction system at least up to 75%, more preferably at least up to 90%, and even more preferably up to 100%, without any adverse effect on the overall reaction.

[0029] The ammonia gas produced can be recovered as a useful chemical or chemical precursor for other industries, such as the fertilizer industry.

[0030] To obtain high quality products with consistent properties, the reactions described herein may be operated in a continuous mode where the reaction reaches a steady state condition. This provides better control of the resulting chemical composition. In one approach, an artificial solution having the same or similar composition as the liquid in the reaction system is prepared and used to start the reaction, and this artificial solution is used until the liquid produced from the solid-liquid separation operation resembles the artificial solution.

[0031] The pH of the reaction slurry may be in the range of 7.5 to 13, or alternatively in the range of 8 to 12. The pH of the solution may be adjusted by adding any of the acids selected from sulfuric acid, nitric acid, or acetic acid, and / or by adding an alkaline substance selected from lithium hydroxide or oxide, sodium hydroxide or oxide, potassium hydroxide or oxide, and ammonia. The pH adjustment may be performed by adding an acid such as sulfuric acid or nitric acid, and / or by adding an alkaline substance such as lithium hydroxide or sodium hydroxide to the reaction mixture. It is noted that lower pH values ​​may reduce the quality of the co-precipitation product, while higher pH values ​​may cause passivation of the metal during the corrosion reaction.

[0032] The reaction temperature may range from 20°C to the boiling point of the reaction slurry, including from 20°C to 100°C.

[0033] Maintaining acceptable electrical conductivity of the reaction system may also be important to control the corrosion reaction. Therefore, the reaction slurry may also contain dissolved salts to form an electrolyte for electrical conductivity. The salts may include salts such as sulfates, acetates, nitrates, and chlorates, and cations selected from sodium, lithium, potassium, and ammonium. The salts may be reusable in the recycled liquid recovered after separation of the liquid and solids.

[0034] To make a final lithiated material with good performance, e.g., high capacity, the precursor material may have small primary particles, i.e., high BET (Brunauer-Emmett-Teller) surface area, in each secondary particle. If nitrates are used as oxidizing agents and / or doping elements are required, nitrates should generally be present in the reaction system. Thus, chemical reactions involving dissolution and precipitation of metals should proceed well with only nitrates as anions in the reaction system. However, the BET surface area of ​​the precursor material is usually quite low with only nitrates in the reaction system. To increase the BET surface area, at least one additional selected anion and / or additive can be applied to the reaction system, which may change the pattern of precursor particle growth. These additional anions may be selected from borates, bromides, iodides, chlorides, sulfates, formates, or acetates, etc. One may select chemicals that are decomposable during the high temperature lithiation process, such as acetates, taking into account the potential for increased impurity levels in the final product when more anions and / or additives are introduced into the reaction system.

[0035] Ammonium should generally be present in the reaction system as the cation. However, other cations can also be applied to the reaction system to adjust the pH and conductivity. Considering that impurity levels in the final product may increase if more cations are introduced into the reaction system, lithium ions may be selected as the cation that is the predominant element in the final product. The aqueous solution may include at least one additional cation besides ammonium, such as sodium, potassium, and lithium. Lithium ions may be selected as the cation that is the predominant element in the final product.

[0036] The reaction slurry may also typically contain dissolved complexing agents, such as a mixture of ammonia and ammonium, that can chelate with metal ions in the aqueous solution. The overall function of these complexing or chelating agents is to control the properties of the co-precipitation product and to make the metal active for the corrosion reaction.

[0037] The process for producing the positive electrode material may also include a step in which unreacted raw metals recovered from the slurry, for example by a magnetic separation step, may be reactivated by grinding and / or washing, for example by using nitrate acid or a combination thereof with ammonia.

[0038] Additionally, the method may also include a step in which solid particles having the same or similar composition as the precursor product, but having a smaller particle size than the precursor product, are introduced into the reaction system at the start of the reaction and / or during the reaction.

[0039] The embodiments of the methods described herein can therefore be used to produce compositionally similar particles of cathode material precursor with uniform elemental distribution within each particle, where metals are added in a stable, continuous manner in a single-stage reaction system. However, the methods can also be applied to produce particles with non-uniform elemental distribution within each particle, such as compositionally gradient or layered particles of cathode material precursor in a multi-stage reaction system by adding different metals at different times or in different stages. In such a multi-stage system, each stage can deposit layers of material with different compositions for different functions. For example, the core region of the cathode material particle can be nickel-rich for higher capacity, while the surface area can be manganese, cobalt, magnesium, tungsten, or aluminum-rich for a stable interface with the electrolyte found in lithium-ion batteries.

[0040] Thus, embodiments of the method provide a system in which metals are added sequentially, always in the same ratio, to produce a precursor with uniform elemental distribution within each particle, or metals are added sequentially in different ratios over time, to produce a precursor with non-uniform elemental distribution within each particle.

[0041] The final cathode active material produced in the present invention can then be finally obtained by mixing the precursor compound with a lithium-containing compound and carrying out a calcination reaction, which can optionally be followed by a surface treatment if necessary. This method is usually called lithiation, and this lithiation method is typically carried out as a solid-state reaction at temperatures between 600°C and 1100°C depending on the chemical composition of the final material. In the lithiation reaction step, oxidizing conditions may also be required as part of the method. Air, oxygen, and nitrates may be used as oxidizing agents.

[0042] For most applications, lithium hydroxide, with or without water of crystallization, and lithium carbonate may be used as the lithium source.

[0043] After lithiation, slight crushing / grinding may be required in a size reduction operation to break up loose agglomerates formed during the lithiation process. Optional surface treatment may then be necessary or desirable, such as washing to remove excess lithium hydroxide / carbonate and other impurities as well as coatings to stabilize the surface of the material.

[0044] In this manner, the cathode material may undergo further processing after calcination, including washing to remove excess lithium and other unwanted impurities, and coating the cathode material for better performance in battery manufacturing and / or battery applications. EXAMPLES

[0045] Example 1 According to the above manufacturing method, about 2.2 L of aqueous solution of water was prepared and transferred to a 3 liter reaction vessel equipped with a stirring and heating system. The aqueous solution contained about 1.0 M concentration of sodium acetate, 0.2 M concentration of sodium nitrate, and 0.1 M concentration of ammonium nitrate. The solution was heated to a temperature of about 60° C. while stirring at a stirring speed of about 800 rpm. The pH was adjusted and controlled at about 10 by adding 28% ammonia solution and sodium hydroxide. About 100 grams of metallic nickel was added to the reaction vessel. After about 30 minutes, about 50 grams of ball-milled metal hydroxide powder was added to the reaction vessel as seeds. The metal hydroxide powder with a size of D50 less than 1 μm contained mostly nickel, as well as small amounts of cobalt and manganese.

[0046] Nitric acid with a concentration of 68% was continuously introduced into the reaction vessel using a peristaltic pump, and 11 grams of metal powder with a ratio of Ni:Co:Mn of 90:5:5 was manually introduced into the reaction vessel every hour. The pumping rate of the nitric acid pump was about 2.8 mL / hour. The pumping rate was about 10% lower than the theoretical rate required to react all the metals. This was because the stirring device during the reaction sucked oxygen into the reaction system, which also participated in the reaction as another oxidizing agent.

[0047] Every 4 hours, approximately 200 mL of slurry was collected from the reaction vessel and the collected slurry was magnetically separated. The separated magnetic portion was returned to the reaction vessel. The non-magnetic solid portion was filtered and then washed with water. All of the filtrate was returned to the reaction vessel together with the wash water.

[0048] The above operation was repeated for three consecutive days. The final solid portion of the filtration process was dried at about 120°C for about 5 hours or more as the precursor of the present invention. This solid sample was sent for scanning electron microscope (SEM) and BET surface area test. Figure 1 shows the SEM image of the sample recovered on the precursor particles from the above reaction. The particles are smooth and spherical with fine secondary particles. The BET surface area is about 17m 2 / g.

[0049] Example 2 (Comparative) For comparison, a second experiment was carried out, in which the reaction conditions were similar to those described in Example 1. The only significant difference was that the aqueous solution contained only nitrates as anions in the reaction system, i.e., sodium nitrate at about 1.2 M concentration and ammonium nitrate at 0.1 M concentration. Figure 2 shows an SEM image on the precursor particles of the sample recovered from this example. The particles are spike-like with very coarse secondary particles. The BET surface area is only 3.3 m 2 / g. Such types of products are generally not considered suitable as precursors for making lithium metal oxide cathode materials.

[0050] Example 3 (Reactivation) Approximately 300 g of unreacted wet metal powder after magnetic separation was collected and exposed to air for 3 days. Approximately 100 g of the exposed metal powder was introduced directly into a 3 L vessel with stirring. The vessel contained approximately 2.5 L of filtrate recovered from the solid-liquid separation step of the process. The oxidation-reduction potential (ORP) was measured at different times than the metal powder being introduced. Typically, an ORP below a level of -300 mV indicates that the metal is active, and the test results are shown as curve 1 in Figure 3. The ORP was stable at approximately -120 mV, indicating that the metal powder was inactive.

[0051] In another test, about 100 g of the same exposed metal powder was introduced into 200 mL of 0.1 M NH4NO3 solution, the pH of which had been adjusted to about 10.5 by adding ammonia. After stirring for several minutes, the metal powder was transferred to a 3 L container with stirring. Again, the container contained about 2.5 L of filtrate recovered from the solid-liquid separation step of the process. The ORP was measured at different times than the metal powder being transferred. The test results are shown as curve 2 in Figure 3. The ORP rapidly decreased to -400 mV within 10 minutes, indicating that the inactive metal powder had been activated.

[0052] It is therefore apparent that there has been provided, in accordance with the present invention, a method, product, and battery that fully fulfills the aims, objects, and advantages set forth above. Thus, while particular embodiments of the invention have been described, it will be understood that alterations, modifications, and variations thereof may be suggested to those skilled in the art, and that the specification is intended to cover all such alterations, modifications, and variations that fall within the scope of the appended claims.

Claims

1. A method for producing a positive electrode active material precursor, comprising the steps of: Providing an aqueous solution having a pH greater than 7; adding a first metal to the aqueous solution to form a reaction solution, the first metal being selected from the group consisting of nickel, manganese, cobalt, aluminum, magnesium, and combinations thereof; forming a product solution comprising adding an oxidant and a second metal to the reaction solution, where the second metal is selected from at least two elements from the group consisting of nickel, manganese, cobalt, aluminum, magnesium, zirconium, yttrium, titanium, vanadium, molybdenum, and combinations thereof, the product solution comprising a cathode active material precursor, and the cathode active material precursor product comprises the first metal and the second metal, where the first metal and the second metal are not the same; and isolating the positive electrode active material precursor from at least a portion of the product solution, thereby forming a filtrate.

2. The method of claim 1 further comprising the step of adding mixed metal hydroxides to the aqueous solution.

3. The method of claim 1 , wherein the aqueous solution has a pH of about 7.5 to about 13.

4. 10. The method of claim 1, wherein the aqueous solution further comprises an acid selected from the group consisting of sulfuric acid, nitric acid, acetic acid, or combinations thereof.

5. 10. The method of claim 1, wherein the aqueous solution further comprises an alkaline material selected from the group consisting of lithium hydroxide, lithium oxide, sodium hydroxide, sodium oxide, potassium hydroxide, potassium oxide, and ammonia.

6. The method of claim 1 , wherein the aqueous solution further comprises a conductive salt.

7. 7. The method of claim 6, wherein the conductive salt is selected from the group consisting of sulfates, acetates, nitrates, chlorates, and combinations thereof.

8. The method of claim 6 , wherein the conductive salt comprises a cation selected from the group consisting of sodium, lithium, potassium, ammonium, and combinations thereof.

9. The method of claim 1 , wherein the aqueous solution further comprises an additional anion.

10. 10. The method of claim 9, wherein the additional anion is selected from the group consisting of borate, bromide, iodide, chloride, sulfate, formate, acetate, and combinations thereof.

11. The method of claim 1 , wherein the aqueous solution comprises a cation.

12. 12. The method of claim 11, wherein the cation is selected from the group consisting of sodium, potassium, lithium, and combinations thereof.

13. The method of claim 1 , wherein the aqueous solution further comprises a complexing agent.

14. The method of claim 13 , wherein the complexing agent comprises ammonia and ammonium.

15. The method of claim 1 , wherein the step of forming the product solution further comprises agitating the reaction solution.

16. The method of claim 1 , wherein the product solution is formed continuously under substantially steady state conditions.

17. 10. The method of claim 1, wherein forming the product solution further comprises adding positive electrode active material precursor particles to the reaction solution.

18. The method of claim 1 further comprising the step of recombining the filtrate with the product solution.

19. 20. The method of claim 18, wherein at least 90% of the filtrate liquid is recombined with the product solution.

20. 20. The method of claim 18, wherein the filtrate is directly recombined with the product solution.

21. The method of claim 1 , wherein the oxidizing agent is selected from the group consisting of oxygen, nitric acid, and combinations thereof.

22. 10. The method of claim 1, further comprising isolating unreacted metals comprising the first metal and the second metal from the filtrate and treating the unreacted metals with an acid.

23. 23. The method of claim 22, wherein the acid is selected from the group consisting of nitric acid, ammonia, ammonium, and combinations thereof.

24. 23. The method of claim 22, further comprising the step of additionally processing the unreacted metal, wherein the additional processing is selected from the group consisting of grinding, washing, and combinations thereof.

25. 10. The method of claim 1 , wherein the positive electrode active material precursor comprises precursor particles having a substantially uniform distribution of metal elements within each particle.

26. 2. The method of claim 1, wherein the positive electrode active material precursor comprises precursor particles having a substantially non-uniform distribution of metal elements within each particle.

27. 27. The method of claim 26, wherein the substantially non-uniform distribution of metallic elements within each particle is selected from the group consisting of a gradient distribution, a layered distribution, and combinations thereof.

28. forming a final mixture comprising the isolated cathode active material precursor and a lithium-containing compound; 13. The method of claim 1, further comprising the step of calcining the final mixture, thereby forming a calcined final mixture comprising an active cathode material.

29. 30. The method of claim 28, wherein the final mixture further comprises a dopant.

30. 29. The method of claim 28, wherein the lithium-containing compound is selected from the group consisting of lithium hydroxide, lithium carbonate, and combinations thereof.

31. The method of claim 28, wherein the calcination is carried out at a temperature of about 600°C to about 1100°C.

32. 30. The method of claim 28, further comprising treating the positive electrode active material, wherein the treatment is selected from the group consisting of washing, coating, and combinations thereof.

33. 1. A method of forming an energy storage device, comprising: forming a positive electrode, the positive electrode formation comprising depositing the positive electrode active material of claim 28 on a current collector; and inserting the positive electrode, the negative electrode, and a separator into a housing, the separator being disposed between the negative electrode and the positive electrode.

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