Multi-element doped positive electrode material

Abstract

A lithium iron manganese phosphate (LMFP)-based vehicle battery cell, a battery for an electric vehicle, and a method are provided. The battery cell includes a positive current collector and a positive electrode having a multi-element doped active material. The active material includes an LMFP having the molecular formula LiMnaFebMgcTidCoeNbfYgPO4 formed with multi-element doping, where a value is equal to or greater than 0.5, b value is equal to or greater than 0.1, c value is equal to or greater than 0.0005 and equal to or less than 0.1, d value is equal to or greater than 0.0005 and equal to or less than 0.1, e value is equal to or less than 0.05, f value is equal to or less than 0.02, and g value is equal to or less than 0.05.

Description

Technical Field

[0001] This disclosure relates to battery packs, and more specifically, to a doped positive electrode disposed within a battery pack. Background Technology

[0002] Electric and hybrid electric vehicle technologies are realized through the development and deployment of rechargeable secondary batteries that power the vehicle's powertrain. Secondary batteries include lithium-ion batteries, which typically consist of a positive electrode, a negative electrode, a separator, and an electrolyte. The positive electrode provides the source of lithium ions and determines the battery's capacity and average voltage. When energy is needed, the negative electrode stores and releases the lithium ions received from the positive electrode. The separator prevents the positive and negative electrodes from coming into contact to avoid short circuits, and the electrolyte provides the medium through which lithium ions pass between the positive and negative electrodes. The energy density, or areal capacity, of a secondary battery can be increased by adding more active materials to the positive and negative electrodes, as well as by increasing the density of the positive and negative electrodes.

[0003] The positive and negative electrodes are formed by coating the current collector with active positive and active negative electrode materials, respectively. The coating typically includes active materials, binders, additives, and / or solvents. At least in the case of the positive electrode, the active material disposed on the current collector is responsible for the electrochemical reactions that store and release energy during battery operation.

[0004] One of the main challenges is the mechanical and chemical stability of the cathode active material during repeated charge and discharge cycles. Cathode degradation leads to reduced capacity, decreased efficiency, and shortened battery life. Another challenge is the need for higher energy density and faster charging capabilities. Current collectors must be optimized to ensure efficient electron transport and minimize energy loss.

[0005] Therefore, while existing lithium cathode chemistry has achieved its intended purpose, new and improved cathode chemistry is still needed to provide improved electronic and ionic conductivity as well as better cyclability. Summary of the Invention

[0006] According to several aspects of this disclosure, a vehicle battery cell based on lithium manganese iron phosphate (LMFP) is provided. The LMFP-based vehicle battery cell includes a positive current collector and a positive electrode, the positive electrode comprising a multi-element doped active material disposed on the surface of the positive current collector. The active material comprises a material with the molecular formula LiMn formed using multi-element doping. a Fe b Mg c Ti d Co e Nb f Y g Lithium manganese iron phosphate (LMFP) with PO4. Molecular formula LiMn a Fe bMg c Ti d Co e Nb f Y g In PO4, the value of a is equal to or greater than 0.5, the value of b is equal to or greater than 0.1, the value of c is equal to or greater than 0.0005 and equal to or less than 0.1, the value of d is equal to or greater than 0.0005 and equal to or less than 0.1, the value of e is equal to or less than 0.05, the value of f is equal to or less than 0.02, and the value of g is equal to or less than 0.05.

[0007] According to another aspect of this disclosure, the value of a is between 0.5 and 0.8.

[0008] According to another aspect of this disclosure, the value of b is equal to or greater than 0.2 and equal to or less than 0.5.

[0009] According to another aspect of this disclosure, the value of c is between 0.01 and 0.05.

[0010] According to another aspect of this disclosure, the d value is between 0.005 and 0.03.

[0011] According to another aspect of this disclosure, the e value is between 0.005 and 0.03.

[0012] According to another aspect of this disclosure, the f value is between 0.0001 and 0.01.

[0013] According to another aspect of this disclosure, the g value is between 0.0005 and 0.02.

[0014] According to another aspect of this disclosure, the positive electrode comprises a carbon coating of 0.5-10 wt%.

[0015] According to another aspect of this disclosure, the primary particle size of the positive electrode is between 10 and 1000 nanometers, and the secondary particle size of the positive electrode is between 0.5 and 20 micrometers.

[0016] According to another aspect of this disclosure, the tap density of the positive electrode is between 0.3 and 2.0 g / cm³.

[0017] According to another aspect of this disclosure, the specific surface area of ​​the positive electrode is between 3 and 50 square meters per gram.

[0018] According to several aspects of this disclosure, a battery for an electric vehicle is provided. The battery includes a battery cell comprising a positive electrode comprising a multi-element doped active material disposed on a positive current collector surface, a negative electrode disposed on a negative current collector surface, a separator disposed between the positive and negative electrodes, and an electrolyte configured to carry ions between the positive and negative electrodes. The active material comprises a material having the molecular formula LiMn formed using multi-element doping. a Feb Mg c Ti d Co e Nb f Y g Lithium manganese iron phosphate (LMFP) with PO4. Molecular formula LiMn a Fe b Mg c Ti d Co e Nb f Y g In PO4, the value of a is equal to or greater than 0.5, the value of b is equal to or greater than 0.1, the value of c is equal to or greater than 0.0005 and equal to or less than 0.1, the value of d is equal to or greater than 0.0005 and equal to or less than 0.1, the value of e is equal to or less than 0.05, the value of f is equal to or less than 0.02, and the value of g is equal to or less than 0.05.

[0019] According to another aspect of this disclosure, the positive electrode comprises a carbon coating of 0.5-10 wt%.

[0020] According to another aspect of this disclosure, the primary particle size of the positive electrode is between 10 and 1000 nanometers, and the secondary particle size of the positive electrode is between 0.5 and 20 micrometers.

[0021] According to another aspect of this disclosure, the tap density of the positive electrode is between 0.3 and 2.0 g / cm³.

[0022] According to another aspect of this disclosure, the specific surface area of ​​the positive electrode is between 3 and 50 square meters per gram.

[0023] According to several aspects of this disclosure, a method for forming a positive electrode for a battery cell in an electric vehicle battery pack is provided. The method includes: forming a precursor; adding at least one dopant element to the precursor; grinding the precursor and the at least one dopant element; adding a carbon precursor to a slurry; and calcining the slurry to form an active positive electrode material. The precursor includes manganese(II) sulfate (MnSO4), ferric(II) sulfate (FeSO4), and phosphoric acid (H3PO4). The at least one dopant element includes at least one selected from a hydrated mixed metal phosphate compound (HMnFePO4·H2O), lithium carbonate (Li2CO3), titanium oxide, magnesium oxide, cobalt oxide, yttrium oxide, or niobium oxide, wherein the slurry is formed.

[0024] According to another aspect of this disclosure, the carbon precursor is glucose.

[0025] According to another aspect of this disclosure, the calcined slurry includes calcination at a temperature between about 600-800°C.

[0026] The above-described features and advantages, as well as other features and advantages, of the currently disclosed systems and methods will become apparent when considered in conjunction with the accompanying drawings and the specific implementation including the claims and embodiments. Attached Figure Description

[0027] This disclosure will be more fully understood through detailed description and accompanying drawings, in which:

[0028] Figure 1 This is a perspective view illustrating an embodiment of a vehicle according to the present disclosure having an electric motor powered by a battery pack having a positive electrode based on lithium manganese iron phosphate.

[0029] Figure 2 Based on this disclosure Figure 1 The diagram shows a cross-sectional view of a battery cell in a vehicle battery pack, wherein the battery cell includes a positive electrode based on lithium manganese iron phosphate.

[0030] Figure 3 This illustrates the method for forming, according to the present disclosure, as follows Figure 2 A flowchart illustrating the method for obtaining the positive electrode of a battery cell in an electric vehicle battery pack. Detailed Implementation

[0031] The following description is merely exemplary in nature and is not intended to limit this disclosure, its application, or its uses. Furthermore, it is not intended to be bound by any express or implied theory presented in the foregoing background, summary of the invention, or the following detailed description. It should be understood that throughout the drawings, corresponding reference numerals denote similar or corresponding parts and features.

[0032] Reference will now be made in detail to several embodiments of the present disclosure illustrated in the accompanying drawings. Wherever possible, the same or similar reference numerals are used in the drawings and description to refer to the same or similar parts or steps. The drawings are simplified and not drawn to exact scale. The following description is merely exemplary in nature and is not intended to limit the present disclosure, its application, or its uses.

[0033] This paper discloses lithium manganese iron phosphate (LMFP) cathode active materials. LMFP cathode active materials are achieved through multi-element doping. Single-element doping was used to dop the LMFP cathode active materials, and the optimal doping amount of each element was determined using a half-coin cell. At a 1C charging rate, all doped LMFP cathode active materials exhibited improved charging capabilities, including lower charging voltage and higher constant current (CC) capacity ratio. For example, magnesium (Mg), cobalt (Co), niobium (Nb), titanium (Ti), and yttrium (Y) doped cathode active materials exhibited higher discharge voltage and improved cycle life. The optimized LMFP cathode active materials disclosed herein provide a higher constant current charge ratio during charging. Compared to conventional LMFP cathode materials, the optimized LMFP cathode active materials exhibit improved discharge rate performance, higher discharge voltage, and enhanced 1C / 1C cycle stability.

[0034] Reference Figure 1 This diagram shows a perspective view of a vehicle 10 having a battery pack 12 according to the present disclosure. The battery pack 12 is shown together with the exemplary vehicle 10. The vehicle 10 is an electric vehicle or a hybrid vehicle having wheels 14 driven by at least one electric motor / inverter 16. The electric motor / inverter 16 receives power from the battery pack 12. Although the vehicle 10 is shown as a passenger road vehicle, it should be understood that the battery pack 12 can be used with a variety of other types of vehicles. For example, the battery pack 12 can be used in marine vehicles such as boats or air vehicles such as drones or passenger planes. Furthermore, the battery pack 12 can be used as a stationary power source separate from and independent of the vehicle. The battery pack 12 includes a housing 18 for carrying and supporting a plurality of battery cells 20. In embodiments, the battery pack 12 may have fifty or more battery cells 20.

[0035] As used herein, the term "vehicle" is not limited to automobiles. While this document primarily describes the technology in conjunction with electric vehicles and hybrid electric vehicles, the technology is not limited to electric vehicles and hybrid electric vehicles. These concepts can be used in a wide variety of applications, such as those related to components used in motorcycles, mopeds, locomotives, aircraft, ships and other vehicles, as well as other applications utilizing batteries, such as for portable power stations (e.g., portable power stations for powering remote work sites), emergency backup power, and permanent power stations associated with buildings and equipment, all of which can be powered by, for example, solar or wind power systems, power lines, and fuel-based generators (e.g., gasoline, propane, kerosene or diesel generators) and Stirling engines.

[0036] Figure 2 It shows Figure 1A battery cell 20 is shown within the battery pack 12. The battery pack 12 and battery cell 20 are understood as rechargeable batteries that can discharge under load and recharge under external power. Battery cell 20 can be, for example, a pouch cell or a prismatic cell. Alternatively, battery cell 20 can be a cylindrical battery cell.

[0037] Settings Figure 1 Each battery cell 20 within the battery pack 12 shown has a housing 18 or casing and at least one electrode stack 22, the electrode stack 22 further including a positive electrode 24, a negative electrode 26, an electrolyte 28, and / or a separator 30. Each battery cell 20 may have tens or hundreds of electrode stacks 22. Each electrode stack 22 is connected to current collectors 32, 34. The electrode stacks are placed within the housing 18, which is filled with the electrolyte 28. The electrolyte 28 transports ions between the positive electrode 24 and the negative electrode 26. The current collectors 32, 34 are thin metal plates or foils disposed on the sides of the electrode stacks 22 and / or the housing 18, and typically have a thickness between 0.1 mm and 1 mm. The current collectors 32, 34 may be made of copper or aluminum and are attached to the electrode stacks 22 to transmit current to an external circuit (not shown).

[0038] During discharge, when a load is applied to battery cell 20, Li + Ions move from the negative electrode 26 to the positive electrode 24 through the electrolyte 28 and membrane 30. Equivalent electrons e - Energy is supplied to the battery load by moving energy from the positive terminal 24 to the negative terminal 26 via the battery circuit. During charging and when an external voltage is applied, Li... + Ions move from the positive electrode 24 to the negative electrode 26 through the electrolyte 28 and the membrane 30, and can be embedded in the negative electrode 26.

[0039] Each battery cell has 20 cells, for example Figure 2 The illustrated battery cell 20 typically includes a positive current collector 32, a positive electrode 24 disposed on the positive current collector 32, a negative current collector 34, a negative electrode 26 disposed on the negative current collector 34, a separator 30 disposed between the positive electrode 24 and the negative electrode 26, and an electrolyte 28. While the illustrated battery cell 20 includes one negative electrode 26 (and one negative current collector 34) and one positive electrode (and one positive current collector 32), the battery cell 20 may optionally include two or more positive electrodes 24 (and positive current collectors 32) and one or more negative electrodes 26 (and negative current collectors 34). In other alternative embodiments, the battery cell 20 may include one or more positive electrodes 24 (and positive current collectors 32) and two or more negative electrodes 26 (and negative current collectors 34). In any of the above designs, one or more separators 30 are interleaved between the positive electrode 24 and the negative electrode 26 to prevent contact between the positive electrode 24 and the negative electrode 26.

[0040] In the various types of battery cells 20 described above, the positive current collector 32 and the negative current collector 34 are formed of conductive materials. In an embodiment, the positive current collector 32 comprises aluminum. Alternatively or additionally, the positive current collector 32 may comprise copper-clad aluminum and / or stainless steel. The negative current collector 34 may comprise one or more of copper, nickel, stainless steel, and titanium. Current collectors 32 and 34 are shown in the form of foil; however, it should be understood that other forms, such as mesh or composite materials, may be presented. In an embodiment, the foil positive current collector 32 and the foil negative current collector 34 are impermeable. The positive current collector 32 may have a thickness in the range of 5 micrometers to 50 micrometers (inclusive), for example, in the range of 5 micrometers to 25 micrometers. The negative current collector 34 has a thickness in the range of 4 micrometers to 50 micrometers (inclusive), for example, in the range of 4 micrometers to 25 micrometers, or a specific example of 13 micrometers.

[0041] The positive electrode 24 includes a positive electrode active material that provides lithium ions (Li ions). + The source can undergo reversible insertion or intercalation of lithium ions, thereby determining, for example, the battery capacity and average voltage. In some embodiments, the active material comprises at least one of lithium iron phosphate (LFP) and / or lithium manganese iron phosphate (LMFP). In embodiments, the positive electrode active material is present in the range of 82 wt% to 97.5 wt% (inclusive of all values ​​and ranges) of the total weight of the positive electrode 24, for example, in the range of 91 wt% to 96 wt% of the total weight of the positive electrode 24. The total weight of the positive electrode is 100 wt%. In embodiments, the positive electrode active material is provided in powder form.

[0042] exist Figure 2 In the illustrated embodiment, the positive electrode active material is lithium manganese iron phosphate (LMFP), and it is multi-element doped. The molecular formula of multi-element doped lithium manganese iron phosphate (LMFP) is: LiMn a Fe b Mg c Ti d Co e Nb f Y gPO4, where a + b + c + d + e + f + g = 1. In an embodiment, the value of a is greater than or equal to 0.5, and the preferred range of the value of a is between 0.5 and 0.8. In an embodiment, the value of b is greater than or equal to 0.1, and the preferred range of the value of b is between 0.2 and 0.5. In an embodiment, the value of c is greater than or equal to 0.0005 and less than or equal to 0.1, and the preferred range of the value of c is between 0.01 and 0.05. In an embodiment, the value of d is greater than or equal to 0.0005 and less than or equal to 0.1, and the preferred range of the value of d is between 0.005 and 0.03. In an embodiment, the value of e is greater than or equal to 0 and less than or equal to 0.05, and the preferred range of the value of e is between 0.005 and 0.03. In an embodiment, the value of f is greater than or equal to 0 and less than or equal to 0.02, and the preferred range of the value of f is between 0.0001 and 0.01. In the embodiments, the g value is greater than or equal to 0 and less than or equal to 0.05, and the preferred range of the g value is between 0.0005 and 0.02. In a specific embodiment, the multi-element doped lithium manganese iron phosphate (LMFP) has the following molecular formula: Li(Mn) 0.7 Fe 0.3 ) 0.945 Mg 0.03 Ti 0.01 Co 0.01 Nb 0.00 1Y 0.004 PO4, but it should be understood that LMFP can have other molecular formulas that fall within the previously disclosed range.

[0043] Lithium manganese iron phosphate can have an average primary particle size ranging from 10 nm to 1000 nm (inclusive of all values ​​and ranges therein, e.g., 50 nm to 300 nm). Lithium manganese iron phosphate has an average secondary particle size between approximately 0.3 μm and 20 μm. The specific surface area of ​​lithium manganese iron phosphate is approximately 3 m² / g (m³). 2 / g) to 50 square meters / gram (m 2 The specific surface area of ​​lithium manganese iron phosphate is in the range of g / g, including all values ​​and ranges therein. In a specific embodiment, the specific surface area of ​​lithium manganese iron phosphate is from 8 m² / g to 25 m² / g. Furthermore, lithium manganese iron phosphate has a tap density in the range of 0.3 g / cm³ to 2.0 g / cm³ (inclusive) (e.g., 0.6 g / cm³ to 1.1 g / cm³). The moisture content of lithium manganese iron phosphate is less than 500 parts per million, for example, in the range of 350 to 450 parts per million. Furthermore, lithium manganese iron phosphate has a discharge capacity of 145 mAh / g at C / 5 (discharge for more than 5 hours), a discharge capacity of 140 mAh / g at C / 2 (discharge for more than 2 hours), and an initial cycle coulombic efficiency greater than 96%.

[0044] The surface area of ​​the positive electrode current collector 32 can be increased by adding a coating or etching. For example, the positive electrode current collector 32 may include a layer of carbon particles disposed on the surface of the positive electrode 24 in contact with the positive electrode. The carbon particles may have an average particle size in the range of 20 nanometers to 2000 nanometers (inclusive), as observed by scanning electron microscopy. Additionally, the carbon particles or carbon coating may comprise between 0.5 and 10 wt% of the positive electrode 24. The carbon coating is preferably between 1.0 and 2.5 wt%.

[0045] The negative electrode 26 comprises a material capable of undergoing reversible insertion or intercalation of lithium ions at a lower electrochemical potential than that of the positive electrode 24, such that an electrochemical potential difference exists between the negative electrode 26 and the positive electrode 24. The negative electrode 26 may comprise lithium metal; lithium alloys (e.g., lithium-silicon alloys, lithium-aluminum alloys, lithium-indium alloys, lithium titanate, and lithium-tin alloys); carbon-based materials (e.g., graphite, activated carbon, carbon black, and graphene); silicon; silicon-based alloys; silicon oxide; silicon-based composites; tin oxide; aluminum; indium; zinc; germanium; and titanium oxide; and any combination thereof. In embodiments, the negative electrode 26 may have a thickness ranging from 50 micrometers to 150 micrometers, including all values ​​and ranges therein. The negative electrode 26 may be applied to the negative electrode current collector 34 using a deposition process (e.g., a slurry-based process, a hot roll forming process, extrusion, or additive manufacturing) to form a coating on the negative electrode current collector 34. The combined negative electrode 26 and negative electrode current collector 34 provide a negative electrode.

[0046] The separator 30 comprises a porous material formed of an electrically insulating material that prevents contact between the positive electrode 24 and the negative electrode 26 and potentially avoids short circuits in the battery circuitry. The separator 30 is sandwiched or at least partially enclosed between the positive electrode 24 and the negative electrode 26, allowing lithium ions and electrolyte 28 to pass through the pores of the separator 30. The separator 30 may comprise one or more of composite materials, polymeric materials, or nonwoven materials. In embodiments, the separator 30 comprises at least one of polyethylene, polypropylene, polyamide, polytetrafluoroethylene, polyvinylidene fluoride, and polyvinyl chloride. Furthermore, the separator 30 may be filled, i.e., include fillers dispersed therein, wherein the fillers comprise materials such as glass fibers. In additional or alternative embodiments, the separator 30 may comprise at least one of a thermally stable porous polymer coating and a ceramic coating such as an alumina coating. This coating is disposed on one or more surfaces of a porous polymer membrane selected from at least polyethylene and polypropylene. The separator 30 may comprise one or more layers, wherein each layer is formed of one or more of the aforementioned materials. The diaphragm 30 can be in the form of a membrane or a mesh, such as a woven mesh or a slit membrane. In an embodiment, the diaphragm 30 has a thickness ranging from 4 micrometers to 25 micrometers, including all values ​​and ranges therein.

[0047] Electrolyte 28 provides a medium between positive electrode 24 and negative electrode 26 through which lithium ions and electrolyte 28 pass. This medium can be liquid, gel, or solid and is capable of conducting lithium ions between positive electrode 24 and negative electrode 26. Electrolyte 28 permeates the pores of porous membrane 30 and wets or otherwise contacts the surfaces of positive electrode 24, negative electrode 26, and membrane 30. In embodiments, electrolyte 28 comprises one or more lithium salts dissolved in a non-aqueous organic solvent. The lithium salts may include one or more of the following: lithium hexafluorophosphate (LiPF6), lithium perchlorate (LiClO4), lithium tetrachloroaluminate (LiAlCl4), lithium iodide (LiI), lithium bromide (LiBr), lithium thiocyanate (LiSCN), lithium tetrafluoroborate (LiBF4), lithium tetraphenylborate (LiB(C6H5)4), lithium bis(oxalate)borate (LiB(C2O4)2) (LiBOB), lithium difluorooxalateborate (LiB... Lithium salts can be present in electrolyte 28 at concentrations ranging from 1M to 4M (inclusive of all values ​​and ranges, such as 2M or 3M). These lithium salts include lithium hexafluoroarsenate (LiAsF6), lithium trifluoromethanesulfonate (LiCF3SO3), lithium bis(trifluoromethane)sulfonylimide (LiN(CF3SO2)2), lithium bis(fluorosulfonylimide) (LiN(FSO2)2)(LiSFI), lithium (triethylene glycol dimethyl ether)bis(trifluoromethanesulfonylimide) (Li(G3)(TFSI)), or lithium bis(trifluoromethanesulfonyl)nitrogen hybrid (LiTFSA).

[0048] Non-aqueous aprotic organic solvents include one or more of various alkyl carbonates, such as cyclic carbonates (e.g., ethylene carbonate (EC), propylene carbonate (PC), butyl carbonate (BC), fluoroethylene carbonate (FEC)), linear carbonates (e.g., dimethyl carbonate (DMC), diethyl carbonate (DEC), methyl ethyl carbonate (EMC)), aliphatic carboxylic acid esters (e.g., methyl formate, methyl acetate, methyl propionate), γ-lactones (e.g., γ-butyrolactone, γ-valerolactone), chain ethers (e.g., 1,2-dimethoxyethane, 1,2-diethoxyethane, ethoxymethoxyethane), and / or cyclic ethers (e.g., tetrahydrofuran, 2-methyltetrahydrofuran, 1,3-dioxolane).

[0049] In addition, the electrolyte 28 may include a variety of additives, such as, but not limited to, ethylene carbonate, ethylene-ethylene carbonate, propane sulfonate, 1,3,2-dioxane-2,2-dioxide (DTD), LiPF2O2, and / or combinations thereof. Other additives may include diluents that do not coordinate with lithium ions but can reduce the viscosity of the electrolyte 28, such as bis(2,2,2-trifluoroethyl) ether (BTFE), and / or flame retardants, such as triethyl phosphate.

[0050] Reference Figure 3 This illustrates a method 100 for forming a positive electrode 24 of a battery cell 20 in an electric vehicle battery pack 12, according to the present disclosure. The method begins at block 102.

[0051] Box 102 depicts the formation of a precursor. The precursor comprises an active material, wherein the active material includes at least manganese(II) sulfate (MnSO4), ferric(II) sulfate (FeSO4), and phosphoric acid (H3PO4). Each component of the precursor may be added one at a time or in groups. For example, in one embodiment, dry materials (e.g., fillers, binders, etc.) may be mixed together, and then wet materials (e.g., fillers, binders, etc.) may be added to the dry materials and further mixed. An active material may be added to the mixture, and water may be added to adjust the solids content. These steps may be rearranged. A planetary mixer may be used to mix the precursor and form a slurry. Alternatively or additionally, other mixers may be used. Mixers are capable of speeds up to 10,000 rpm (including all values ​​and ranges from 10 rpm to 10,000 rpm).

[0052] Box 104 depicts the addition of at least one dopant element to a precursor. The at least one dopant element includes a hydrated mixed metal phosphate compound (HMnFePO4·H2O), lithium carbonate (Li2CO3), titanium (e.g., TiO2), magnesium (e.g., MgO), niobium (Nb2O5), yttrium (Y2O3), or cobalt (e.g., Co3O4). The dopant element can be added in dry or wet form and can be further mixed into the precursor slurry to form a second slurry. A planetary mixer can be used to mix the dopant element. Alternatively, other mixers can be used. The mixer is capable of speeds up to 10,000 rpm (including all values ​​and ranges from 10 rpm to 10,000 rpm).

[0053] Box 106 depicts the grinding of the precursor and at least one dopant element. Grinding provides improved surface area and improved uniformity to the positive electrode active material comprising the precursor and at least one dopant element, which can enhance the battery capacity and cycle life of electric vehicles. Various grinding techniques can be used, including, for example, ball milling, which involves mixing and grinding the positive electrode active material in a rotating cylinder with hard balls. Another example of grinding may include high-energy grinding, which uses higher speeds and energy to obtain fine particles. Method 100 then moves to box 108.

[0054] Box 108 depicts the addition of a carbon precursor to the slurry. The carbon precursor may include, for example, glucose. Other examples of carbon precursors may include carbon black and / or carbon nanotubes. The carbon precursor may be added in dry or wet form and may be distributed throughout the slurry. The slurry may be further mixed using a ball mill and / or a high-shear mixer to ensure a homogeneous mixture. Mixing the slurry prevents agglomeration and ensures good dispersion of the carbon precursor. In some cases, during this step, the slurry may also be coated onto the positive electrode 24 and / or the current collector 32 and dried to remove any present solvent, thereby forming a solid positive electrode active material. In some cases, the positive electrode active material may be calendered, which includes compressing the positive electrode active material to improve interparticle contact and enhance the mechanical properties of the positive electrode active material. Method 100 then proceeds to box 112.

[0055] Box 110 depicts the calcination slurry. Calcination of the slurry involves heating the slurry to a high temperature to obtain the chemical and physical properties required for the cathode active material. During calcination, several reactions may occur. First, lithium compounds can react with metal oxides to form the final lithium metal oxide structure. Additionally, the cathode active material may undergo oxidation, which is crucial for achieving the correct valence state of the relevant metal. Furthermore, high-temperature calcination facilitates the formation of the desired crystalline phase, which is essential for the electrochemical performance of the cathode active material.

[0056] In embodiments, calcining the slurry involves subjecting the positive electrode active material to high temperatures in a controlled atmosphere. It should be understood that the temperature of the calcination step can include a variety of temperatures. This can occur in a furnace and can involve heating the slurry / positive electrode active material to temperatures ranging from 500°C to 900°C. One specific embodiment includes calcining the positive electrode active material with a carbon coating at a temperature between about 600-800°C. In this context, those skilled in the art will understand the term "about". Alternatively, the term "about" should be understood to mean ±5°C. After calcination, the positive electrode active material can be slowly cooled to ambient temperature, which helps achieve the desired microstructure and phase stability. Then, if the positive electrode active material has not yet been coated onto the positive electrode 24, the positive electrode active material can undergo additional processing steps, such as grinding.

[0057] The lithium manganese iron phosphate (LMFP)-based vehicle battery cell 20 and battery pack 12 for electric vehicle 10 disclosed herein are advantageous and beneficial compared to the prior art. Multi-element doped LMFP cathode active materials exhibit improved charging capabilities, including lower charging voltage and higher constant current (CC) capacity ratio. The optimized LMFP cathode active material disclosed herein provides a higher constant current charge ratio during charging. Compared to conventional LMFP cathode materials, the optimized LMFP cathode active material exhibits improved discharge rate performance, higher discharge voltage, and enhanced 1C / 1C cycle stability.

[0058] This description is merely illustrative in nature and is in no way intended to limit this disclosure, its application, or its use. The broad teachings of this disclosure can be implemented in many forms. Therefore, while this disclosure includes specific embodiments, its true scope should not be so limited, as other modifications will become apparent upon examination of the drawings, description, and appended claims.

Claims

1. A lithium manganese iron phosphate (LMFP) based vehicle battery cell comprising: a positive current collector; a positive electrode comprising a multi-element doped active material disposed on a surface of the positive current collector, the active material comprising: Lithium manganese iron phosphate (LMFP) having the formula LiMnaMgbMcMdMgO4 a Fe b Mg c Ti d Co e Nb f Y g PO4, wherein a+b+c+d+e+f+g = 1, and wherein a is equal to or greater than 0.5; b is equal to or greater than 0.1; c is equal to or greater than 0.0005 and equal to or less than 0.1; d is equal to or greater than 0.0005 and equal to or less than 0.1; e is equal to or less than 0.05; f is equal to or less than 0.02; and g is equal to or less than 0.

05.

2. The lithium manganese iron phosphate (LMFP) based vehicle battery cell of claim 1, wherein, a is between 0.5 and 0.

8.

3. The lithium manganese iron phosphate (LMFP) based vehicle battery cell of claim 1, wherein, b is equal to or greater than 0.2 and equal to or less than 0.

5.

4. The lithium manganese iron phosphate (LMFP) based vehicle battery cell of claim 1, wherein, c is between 0.01 and 0.

05.

5. The lithium manganese iron phosphate (LMFP) based vehicle battery cell of claim 1, wherein, d is between 0.005 and 0.

03.

6. The lithium manganese iron phosphate (LMFP) based vehicle battery cell of claim 1, wherein, e is between 0.005 and 0.

03.

7. The lithium manganese iron phosphate (LMFP) based vehicle battery cell of claim 1, wherein, f is between 0.0001 and 0.

01.

8. The lithium manganese iron phosphate (LMFP) based vehicle battery cell of claim 1, wherein, g is between 0.0005 and 0.

02.

9. The lithium manganese iron phosphate (LMFP) based vehicle battery cell of claim 1, wherein, the positive electrode comprises between 0.5-10 weight percent (wt%) of a carbon coating.

10. The lithium manganese iron phosphate (LMFP)-based vehicle battery cell of claim 1, wherein, the primary particle size of the positive electrode is between 10-1000 nanometers, and wherein the secondary particle size of the positive electrode is between 0.5-20 microns.

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