Stacked battery structure for vehicle battery units

Abstract

A lithium manganese iron phosphate (LMFP) based vehicle battery cell is provided. The vehicle battery cell includes a positive current collector, a positive electrode disposed on a surface of the positive current collector, a negative current collector, and a negative electrode disposed on a surface of the negative current collector. The positive electrode has an active material including at least one of lithium manganese iron phosphate (LMFP) or lithium nickel cobalt manganese aluminum oxide (NCMA). The negative electrode has an active material including graphite. The negative current collector and negative electrode are disposed proximate to the positive current collector and positive electrode, and the negative electrode and positive electrode are separated by a separator.

Description

Technical Field

[0001] This disclosure relates to vehicle battery packs and battery cells, and more specifically, to the design of lithium-ion battery cells within a battery pack. Background Technology

[0002] Electric and hybrid electric vehicle technologies are achieved through the development and deployment of rechargeable secondary batteries that power the vehicle's powertrain. Secondary batteries, including lithium-ion batteries, typically consist of a positive electrode, a negative electrode, a separator, and an electrolyte. The positive electrode provides the lithium-ion source and determines the battery's capacity and average voltage. The negative electrode stores and releases the lithium-ions received from the positive electrode when energy is needed. The separator prevents the positive and negative electrodes from contacting each other to prevent short circuits, while the electrolyte provides the medium for lithium-ion passage 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 positive and negative active 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 issues is the mechanical, thermal, and chemical stability of the positive and / or negative electrode active materials during repeated charge and discharge cycles. Degradation of the positive electrode leads to reduced capacity, decreased efficiency, and shortened battery life. Another issue is the need for higher energy density and faster charging capabilities. Both the positive and negative electrodes must be optimized to ensure efficient electron transport and minimize energy loss.

[0005] Therefore, while existing lithium cathode and anode chemicals have achieved their intended purpose, new and improved chemicals are needed to provide improved mechanical, thermal, and chemical stability. 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 vehicle battery cell includes a positive current collector, a positive electrode disposed on the surface of the positive current collector, a negative current collector, and a negative electrode disposed on the surface of the negative current collector. The positive electrode has an active material including at least one of lithium manganese iron phosphate (LMFP) or lithium nickel cobalt manganese aluminum oxide (NCMA). The molecular formula of lithium manganese iron phosphate (LMFP) is LiMn. x Fe 1-x-y M yPO4, wherein M includes at least one of titanium (Ti), magnesium (Mg), aluminum (Al), calcium (Ca), niobium (Nb), cobalt (Co), or yttrium (Y), and x = 0.5-0.9, y = 0-0.3. The molecular formula of lithium nickel cobalt manganese aluminum oxide (NCMA) is LiNiCoMnAlO2. The negative electrode has an active material including graphite. The negative electrode current collector and the negative electrode are positioned close to the positive electrode current collector and the positive electrode, and the negative electrode and the positive electrode are separated by a separator.

[0007] According to another aspect of this disclosure, the energy density of the vehicle battery cell is 460-580 Wh / L.

[0008] According to another aspect of this disclosure, the vehicle battery cell is at least one of a prismatic cell or a pouch cell.

[0009] According to another aspect of this disclosure, the positive current collector is aluminum.

[0010] According to another aspect of this disclosure, the active material of the positive electrode comprises a mixture of LMFP and NCMA, wherein LMFP constitutes more than 50% of the mixture.

[0011] According to another aspect of this disclosure, the molecular formula of the active material of the positive electrode is LiMn. 0.75 Fe 0.25 PO4.

[0012] According to another aspect of this disclosure, the capacity load of the positive electrode is approximately 3.3 mAh / cm². 2 ).

[0013] According to another aspect of this disclosure, the porosity of the positive electrode is 35% ± 8%.

[0014] According to another aspect of this disclosure, the negative electrode is formed from at least one of artificial graphite (AG) or natural graphite (NG).

[0015] According to another aspect of this disclosure, the negative electrode is formed from a mixture of about 50% artificial graphite (AG) and about 50% natural graphite (NG).

[0016] According to another aspect of this disclosure, the negative current collector is formed of copper.

[0017] According to another aspect of this disclosure, the vehicle battery cell based on lithium manganese iron phosphate (LMFP) includes a binder.

[0018] According to another aspect of this disclosure, the vehicle battery cell based on lithium manganese iron phosphate (LMFP) includes carbon additives.

[0019] According to several aspects of this disclosure, a battery for an electric vehicle is provided. The battery includes a battery cell. The battery cell includes a positive current collector, a plurality of positive electrodes including active material disposed on the surface of the positive current collector, a negative current collector, a negative electrode having an active material including graphite disposed on the surface of the negative current collector, a separator located between the positive and negative electrodes, and an electrolyte configured to carry ions between the positive and negative electrodes. The active material includes materials having the molecular formula LiMn. x Fe 1-x- y M y At least one of lithium manganese iron phosphate (LMFP) with the molecular formula LiNiCoMnAlO2 or lithium nickel cobalt manganese aluminum oxide (NCMA), wherein M includes at least one of titanium (Ti), magnesium (Mg), aluminum (Al), calcium (Ca), niobium (Nb), cobalt (Co) or yttrium (Y), wherein x = 0.5-0.9 and wherein y = 0-0.3.

[0020] According to another aspect of this disclosure, the energy density of the battery cell is 460-580 Wh / L.

[0021] According to another aspect of this disclosure, the molecular formula of the active material of the positive electrode is LiMn. 0.75 Fe 0.25 PO4.

[0022] According to another aspect of this disclosure, the active material of the positive electrode comprises a mixture of LMFP and NCMA, wherein LMFP constitutes more than 50% of the mixture.

[0023] According to another aspect of this disclosure, the negative electrode is formed from at least one of artificial graphite (AG) or natural graphite (NG).

[0024] According to another aspect of this disclosure, the negative electrode is formed from a mixture of about 50% artificial graphite (AG) and about 50% natural graphite (NG).

[0025] According to several aspects of this disclosure, a vehicle battery cell based on lithium manganese iron phosphate (LMFP) is provided. The vehicle battery cell includes a positive current collector, a positive electrode disposed on the surface of the positive current collector, a negative current collector, and a negative electrode disposed on the surface of the negative current collector. The positive electrode has a molecular formula of LiMn. x Fe 1-x-y M yThe active material of lithium manganese iron phosphate (LMFP) of PO4, wherein M includes at least one of titanium (Ti), magnesium (Mg), aluminum (Al), calcium (Ca), niobium (Nb), cobalt (Co), or yttrium (Y), wherein x = 0.5-0.9, and wherein y = 0-0.3. The active material may also include lithium nickel cobalt manganese aluminum oxide (NCMA) with the molecular formula LiNiCoMnAlO2. The active material may also include carbon additives and / or binders. The negative electrode has an active material including graphite and at least one of carbon additives or binders. The negative electrode current collector and the negative electrode are positioned close to the positive electrode current collector and the positive electrode, and the negative electrode and the positive electrode are separated by a separator.

[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.

[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 chemical composition 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 the vehicle's battery pack, wherein the battery cell includes a positive electrode based on lithium manganese iron phosphate. Detailed Implementation

[0030] 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 technical field, background art, 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.

[0031] 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.

[0032] This paper discloses the battery cell structure, lithium manganese iron phosphate (LMFP) cathode, and anode. The optimized structure and LMFP cathode active material disclosed in this paper provide high thermal stability and low cost. Compared with conventional LFP cathode materials, the optimized LMFP cathode active material has a higher energy density, reaching 460-580 Wh / L, an improvement of 10-38%.

[0033] Reference Figure 1 This illustration 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 (e.g., boats) or air vehicles (e.g., drones or passenger aircraft). Furthermore, the battery pack 12 can be used as a stationary power source separate 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.

[0034] 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 variety of applications (e.g., in relation to components used in motorcycles, mopeds, locomotives, aircraft, ships, and other vehicles), as well as other applications using 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 turbine systems, power lines, and fuel-based generators (e.g., gasoline, propane, kerosene, or diesel generators) as well as standard engines.

[0035] Figure 2 It shows Figure 1 A 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. Although battery cell 20 is shown as a prismatic battery cell, it may also include, for example, a pouch cell. Alternatively, battery cell 20 may be a cylindrical cell.

[0036] Settings Figure 1Each battery cell 20 within the battery pack 12 shown has a housing 18 (or casing or battery case) 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 of 0.001 mm to 1 mm. The current collectors 32, 34 may be made of copper (e.g., 6 μm foil) or aluminum (e.g., 12 μm foil) and are connected to the electrode stacks 22 to transmit current to an external circuit (not shown).

[0037] 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 the separator 30. Equivalent electrons (e-) move from the positive electrode 24 to the negative electrode 26 through the battery circuit, thus providing energy to the battery load. When charging and with an external voltage 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.

[0038] Each battery cell 20 (e.g.) Figure 2 The battery cell shown typically includes a positive electrode 24 disposed on a positive current collector 32, a negative electrode 26 disposed on a negative current collector 34, a separator 30 disposed between the positive electrode 24 and the negative electrode 26, and an electrolyte 28. Although the battery cell 20 shown depicts one negative electrode 26 (and one negative current collector 34) and one positive electrode 24 (and one positive current collector 32), the battery cell 20 may alternatively 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 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.

[0039] 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, or titanium. Current collectors 32 and 34 are shown in the form of foil; however, it should be understood that other forms may be presented, such as mesh, wire, or composite materials. 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 of 5 micrometers to 50 micrometers (inclusive of all values ​​and ranges therein, e.g., 5 micrometers to 25 micrometers). The negative current collector 34 may have a thickness of 5 micrometers to 50 micrometers (inclusive of all values ​​and ranges therein, e.g., 5 micrometers to 25 micrometers).

[0040] The positive electrode 24 includes a positive electrode active material that provides a lithium-ion (Li+) source and allows for reversible insertion or intercalation of lithium ions, thereby determining, for example, the battery's capacity and average voltage. In embodiments, the active material includes lithium manganese iron phosphate (LMFP) and / or lithium nickel cobalt manganese aluminum oxide (NCMA). The positive electrode active material may include lithium manganese iron phosphate (LMFP) because LMFP batteries are known for their thermal stability and safety, because iron and manganese are more abundant and cheaper than other materials (e.g., nickel and cobalt), reducing the overall cost of the battery, and because LMFP batteries have good energy density and a long lifespan. The positive electrode active material may include lithium nickel cobalt manganese aluminum oxide (NCMA) because NCMA batteries have a high nickel content, which increases energy density, because NCMA reduces reliance on potentially expensive cobalt, and because the addition of aluminum enhances thermal stability and overall battery safety. The positive electrode active material may include LMFP and NCMA in different mass ratios. For example, the first positive electrode active material may include a design with 100% wt% LMFP. In another embodiment, the second positive electrode active material may include a design having an LMFP mass ratio greater than 50%wt and the balance being NCMA (e.g., 70%wt of LMFP and 30%wt of NCMA, 80%wt of LMFP and 20%wt of NCMA, etc.).

[0041] In this embodiment, the positive electrode active material is present at 82% to 97.5% by weight (inclusive of all values ​​and ranges therein, e.g., 91% to 96% by weight of the total weight of the positive electrode 24) of the total weight of the positive electrode 24. The total weight of the positive electrode is 100% by weight. In this embodiment, the positive electrode active material is provided in powder form.

[0042] The molecular formula of lithium manganese iron phosphate (LMFP) is LiMn. x Fe 1-x-y M yPO4, wherein M includes at least one of titanium (Ti), magnesium (Mg), aluminum (Al), calcium (Ca), niobium (Nb), cobalt (Co), or yttrium (Y), wherein x = 0.5-0.9 and y = 0-0.3. In a specific embodiment, lithium manganese iron phosphate (LMFP) has the molecular formula LiMn. 0.75 Fe 0.25 PO4, where x = 0.75. It should be understood that LMFP may have other molecular formulas corresponding to the previously disclosed range.

[0043] When using LMFP, the positive electrode active material may also include coated carbon. For example, the coated carbon may be about 1-5% wt, and preferably about 1.5-2.5% wt. In this document, the term "about" will be understood by those skilled in the art. Alternatively, the term "about" should be understood to mean ±0.1% wt. Additionally, LMFP may have a carbon content of about 5-30 m² / g (m² / g). 2 The specific surface area (BET(Brunaer-Emmett-Teller)) per g. In this document, the term "about" will be understood by those skilled in the art. Alternatively, the term "about" should be understood to mean ±1m². 2 / g. LMFP can have approximately 0.5-2 grams per cubic centimeter (g / cm³). 3 The tap density is preferably about 0.6-1.2 g / cm³. 3 In this document, the term "about" will be understood by those skilled in the art. Alternatively, the term "about" is understood to mean ±0.1 g / cm³. 3 LMFPs can have an average particle size of 10 nanometers to 1,000 nanometers (including all values ​​and ranges therein, such as 50 nanometers to 300 nanometers).

[0044] The molecular formula of lithium nickel cobalt manganese aluminum oxide (NCMA) is Li[Ni] x Co y Mn z Al w O2, where x, y, z, and w can vary. In one specific embodiment, the NCMA molecular formula can be Li[Ni] 0.8 Co 0.1 Mn 0.1 Al 0.05 O2. In another embodiment, x may be greater than 0.8 (e.g., x = 0.87). It should be understood that the molecular formula of NCMA may include other elemental proportions without departing from the scope of this disclosure. Additionally, NCMA may include a median particle size (D50) of about 2-15 micrometers (μm). In this document, the term “about” will be understood by those skilled in the art. Alternatively, the term “about” is understood to mean ±1 μm. NCMA may have a particle size of about 0.3-3 square meters per gram (m²). 2The specific surface area (BET(Brunaer-Emmett-Teller)) per g. In this document, the term "about" will be understood by those skilled in the art. Alternatively, the term "about" should be understood to mean ±0.1 m². 2 / g. LMFP can have approximately 0.5-2 grams per cubic centimeter (g / cm³). 3 The tap density is preferably about 0.6-1.2 g / cm³. 3 In this document, the term "about" will be understood by those skilled in the art. Alternatively, the term "about" is understood to mean ±0.1 g / cm³. 3 In the implementation, LMFP may have a pH of about 8-11 (e.g., dispersed at 10% wt). In this document, the term "about" will be understood by those skilled in the art. Alternatively, the term "about" should be understood to mean ±0.1.

[0045] The positive electrode active material may also contain carbon additives. For example, carbon additives may include one or more of carbon black, graphite, graphene, graphene oxide, graphene nanoplatelets, Super P, acetylene black, carbon nanofibers, carbon nanotubes, single-walled carbon nanotubes (SWCNTs), multi-walled carbon nanotubes (MWCNTs), and other electronically conductive additives.

[0046] The positive electrode active material may also contain carbon additives and / or binders. The binder is used to fix the positive electrode material in a compact and stable form within the battery cell. Some examples of binders that may be included in the positive electrode 24 include poly(vinylidene fluoride) (PVDF), poly(vinylidene fluoride-hexafluoropropylene) copolymer (PVdF-HFP), polytetrafluoroethylene (PTFE), sodium carboxymethyl cellulose (CMC), styrene-butadiene rubber (SBR), styrene-ethylene-butene-styrene copolymer (SEBS), etc.

[0047] For a single-sided coating of the positive electrode active material on positive electrode 24, both positive electrode 24 and the positive electrode active material can have approximately 5 mAh / cm². 2 (±3mAh / cm 2 The capacity load is 2 g / cm³ (for a battery with a C-rate of 0.1C at room temperature). Additionally, the positive electrode active material can have a capacity load of 2 g / cm³. 3 (±1g / cm 3 The compressed density is 35% (±8%) and the porosity is 35%.

[0048] The positive electrode active material may comprise about 90-97% wt of positive electrode active material, about 1-5% wt of carbon additive, and about 1-5% wt of binder formed using PVDF in an N-methyl-2-pyrrolidone (NMP) solvent. In this document, the term "about" will be understood by those skilled in the art. Alternatively, the term "about" should be understood to mean ±0.2% wt.

[0049] In a specific embodiment, the positive electrode 24 and the positive electrode active material are formed from 96.3% wt of an LMFP / NCMA mixture (LMFP mass ratio of 100% wt), 0.7% wt of Super P, 0.5% wt of MWCNT, and 2.5% wt of PVDF, wherein the molecular formula of LMFP is LiMn. 0.75 Fe 0.25 PO4. In this embodiment, the LMFP contains a median particle size (D50) of approximately 8 μm and a specific surface area (BET) of approximately 2.2 m². 2 / g of 2.2% wt coated carbon. In this embodiment, the capacity loading of the positive electrode is approximately 3.3 mAh / cm³. 2 The compressed density is 2.4 g / cm³. 3 The porosity is 28%.

[0050] In a second specific embodiment, the positive electrode 24 and the positive electrode active material are formed from 96.3% wt of an LMFP / NCMA mixture (70% wt of LMFP and 30% wt of NCMA by mass ratio (e.g., a 7 / 3 ratio)), 0.7% wt of Super P, 0.5% wt of MWCNT, and 2.5% wt of PVDF, wherein the LMFP has the molecular formula LiMn 0.75 Fe 0.25 PO4, and NCMA contains nickel (Ni) in a ratio of 0.87. In this embodiment, the capacity loading of the positive electrode is approximately 3.5 mAh / cm³. 2 The compressed density is 2.6 g / cm³. 3 The porosity is 28%.

[0051] In the third specific embodiment, the positive electrode 24 and the positive electrode active material are formed from 96.3% wt of an LMFP / NCMA mixture (80% wt of LMFP and 20% wt of NCMA by mass ratio (e.g., 8 / 2 ratio)), 0.7% wt of Super P, 0.5% wt of MWCNT, and 2.5% wt of PVDF, wherein the LMFP has the molecular formula LiMn 0.75 Fe 0.25 The PO4 and NCMA contain nickel (Ni) in a ratio of 0.87. In this embodiment, the capacity loading of the positive electrode is approximately 3.45 mAh / cm³. 2 The compressed density is 2.5 g / cm³. 3 The porosity is 28%.

[0052] The negative electrode 26 comprises a material capable of reversible insertion or intercalation of lithium ions at a lower electrochemical potential than that of the positive electrode 24, resulting in an electrochemical potential difference 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 of 50 micrometers to 150 micrometers (inclusive). The negative electrode 26 may be applied to the negative electrode current collector 34, forming a coating on 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). The combined negative electrode 26 and negative electrode current collector 34 provide a negative electrode.

[0053] The negative electrode 26 includes a negative electrode active material. The negative electrode active material may include man-made graphite (AG graphite) and / or naturally occurring graphite (NG graphite), at least one binder, and / or at least one carbon additive. AG graphite, also known as synthetic graphite, includes carbon in an artificial form, produced by high-temperature processing of carbon materials (e.g., petroleum coke and coal tar pitch). NG graphite may include crystalline carbon in a naturally occurring form found in metamorphic and igneous rocks. In embodiments, the negative electrode active material may include 100% wt of AG graphite, 100% wt of NG graphite, or a mixture of AG graphite and NG graphite in any proportion (e.g., 75% wt of AG graphite / 25% wt of NG graphite, 50% wt of AG graphite / 50% wt of NG graphite, 25% wt of AG graphite / 75% wt of NG graphite, etc.).

[0054] The negative electrode active material may include one or more adhesives selected from styrene-butadiene rubber (SBR), sodium carboxymethyl cellulose (CMC), polyacrylic acid (PAA), and / or carboxymethyl cellulose (CM). It should be understood that the adhesives in the negative electrode active material may include other suitable adhesives.

[0055] The negative electrode active material may include at least one carbon additive. For example, the carbon additive may include one or more of carbon black, graphite, graphene, graphene oxide, graphene nanoplatelets, Super P, acetylene black, carbon nanofibers, carbon nanotubes, single-walled carbon nanotubes (SWCNTs), multi-walled carbon nanotubes (MWCNTs), and other electronically conductive additives.

[0056] In the embodiments, the negative electrode 26 may include about 90-99% wt of negative electrode active material, about 1-6% wt of binder, and about 0-3% wt of carbon additive. In this document, the term "about" will be understood by those skilled in the art. Alternatively, the term "about" should be understood to mean ±0.2% wt.

[0057] In a specific embodiment, the negative electrode 26 and the negative electrode active material are formed from a 97.44% wt AG graphite / NG graphite mixture (mass ratio of 1:1 (e.g., 50% wt AG graphite / 50% wt NG graphite)), wherein the AG graphite has a median particle size (D50) of 12.5 μm and a specific surface area (BET) of 1.26 m². 2 The median particle size (D50) of NG graphite is 11 μm, and the specific surface area (BET) is 1.5 m² / g. 2 / g. In this embodiment, the negative electrode active material also includes a binder containing 1.64% wt CMC and 0.92% wt SBR. When the positive electrode active material mixture contains 100% wt LMFP, the negative electrode 26 has approximately 3.63 mAh / cm³. 2 Capacity load and 1.5g / cm 3 The compression density. When the positive electrode active material mixture contains 70% wt LMFP and 30% wt NCMA, the negative electrode 26 has a compression density of approximately 3.85 mAh / cm³. 2 Capacity load and 1.5g / cm 3 The compression density. When the positive electrode active material mixture contains 70% wt LMFP and 30% wt NCMA, the negative electrode 26 has a compression density of approximately 3.8 mAh / cm³. 2 Capacity load and 1.5g / cm 3 The compression density.

[0058] 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, thereby preventing potential short circuits in the battery circuit. The separator 30 is sandwiched or at least partially surrounded 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. Additionally, the separator 30 may be filled, i.e., include a filler dispersed therein, wherein the filler comprises a material such as glass fiber. In additional or alternative embodiments, the separator 30 may comprise at least one of a thermally stable porous polymer coating and a ceramic coating (e.g., an alumina coating). The coating may be disposed on one or more surfaces of the porous polymer membrane, wherein the polymer membrane may be selected from at least one of 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 may be in the form of a membrane or a mesh, such as a woven mesh or a cut membrane. In embodiments, and when the diaphragm 30 includes coatings and / or multiple layers, the diaphragm 30 may be single-sided or double-sided, having the same or different coatings, such as polymer layer / diaphragm / polymer layer, polymer layer + ceramic layer / diaphragm / polymer layer + ceramic layer, polymer layer / ceramic layer / diaphragm / ceramic layer / polymer layer, polymer layer / diaphragm / ceramic layer / polymer layer. Some examples of a single-sided diaphragm 30 may include a polymer layer disposed on the diaphragm 30, a polymer layer + ceramic layer disposed on the diaphragm 30, and / or a polymer layer disposed on a ceramic layer on the diaphragm 30. It should be understood that the diaphragm may include layers and / or coatings of various other configurations.

[0059] In one embodiment, the diaphragm 30 has a thickness of about 20 micrometers (μm) ± 15 μm (inclusive of all values ​​and ranges therein). In another embodiment, the coating (e.g., a polymer coating) may have a thickness from about 1 μm to 10 μm. The term "about" will be understood by those skilled in the art throughout this document. Alternatively, the term "about" may refer to 0.5 μm. In one specific embodiment, the diaphragm 30 has a thickness of 12 μm, a porosity of 47%, and a multilayer coating of 2 μm boehmite and 10 μm polyethylene.

[0060] Electrolyte 28 provides a medium between the positive electrode 24 and the 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 the positive electrode 24 and the negative electrode 26. Electrolyte 28 permeates the pores of the porous membrane 30 and wets or otherwise contacts the positive electrode 24, the negative electrode 26, and the surface of the membrane 30.

[0061] In the implementation scheme, the electrolyte 28 comprises one or more lithium salts dissolved in a non-aqueous organic solvent. 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(trifluoromethane)borate (LiBOB)(LiB(C2O4)2), lithium difluorooxalate borate (LiBF2(C2O4))), lithium hexafluoroarsenate (LiAsF6), lithium trifluoromethanesulfonate (LiCF3SO3), lithium bis(trifluoromethane)sulfonylimide (LiN(CF3SO2)2), lithium bis(fluorosulfonyl)imide (LiN(FSO2)2)(LiSFI), lithium bis(triethylene glycol dimethyl ether)bis(trifluoromethane ... Lithium(G3)(TFSI) and / or lithium(trifluoromethanesulfonyl)azanide (LiTFSA) may be present in the electrolyte 28 at a concentration (moles of salt per liter of solvent (M)) from 0.5 M to 2.16 M (inclusive of all values ​​and ranges therein, such as 1 M or 2 M). The electrolyte may include a solvent (e.g., carbonate) and may include one or more additives (e.g., fluoroethylene carbonate (FEC), vinylene carbonate (VC), 1,3,2-dioxazothiophene-2,2-dioxide (DTD), tris(trimethylsilyl)phosphite (TMSPi), lithium difluoro(oxalate)borate (LiDFOB), tris(trimethylsilyl)borate (TMSPB), etc.).

[0062] The electrolyte 28 may also 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).

[0063] Furthermore, the electrolyte 28 may include a variety of additives, such as, but not limited to, vinyl ethylene carbonate (VEC), propane sulfonate, lithium difluorophosphate (LiPF2O2), and / or combinations thereof. Other additives may include diluents (e.g., bis(2,2,2-trifluoroethyl) ether (BTFE)) and / or flame retardants (e.g., triethyl phosphate) that do not coordinate with lithium ions but can reduce the viscosity of the electrolyte 28.

[0064] In a specific embodiment, the electrolyte 28 comprises 1.2 M LiPF6, a solvent comprising 30% by volume ethylene carbonate (EC) and 70% by volume ethyl methyl carbonate (EMC), and an additive comprising 2% by wt fluoroethylene carbonate (FEC) and 1% by wt ethylene carbonate (VC). It should be understood that the electrolyte 28 may include other suitable components and / or combinations of components.

[0065] The battery pack 12 and battery cell 20 described herein may include an N / P ratio of 1-1.2 (e.g., the capacity ratio between the negative (negative) electrode and the positive (positive) electrode) and a voltage range of 2-4.5 volts (V). In a specific embodiment, the battery cell 20 may include a housing 18 of 250 x 220 x 28.8 mm, having a volumetric energy density (VED) of 460-580 Wh / L, a gravimetric energy density (GED) of 210-260 Wh / kg, and a GED / VED at 30% state of charge (SOC).

[0066] The vehicle battery cell 20 and battery pack 12 based on lithium manganese iron phosphate (LMFP) disclosed herein are superior to existing technologies. The optimized structure and LMFP cathode active material disclosed herein provide high thermal stability and low-cost products. Compared with conventional LMFP cathode materials, the optimized LMFP cathode active material has a higher energy density, reaching 460-580 Wh / L, an improvement of 10-38%.

[0067] 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 vehicle battery cell based on lithium manganese iron phosphate (LMFP), comprising: Positive current collector; A positive electrode, disposed on the surface of the positive electrode current collector, the positive electrode having an active material comprising at least one of the following: It has the molecular formula LiMn x Fe 1-x-y M y Lithium manganese iron phosphate (LMFP) of PO4, wherein M includes at least one of titanium (Ti), magnesium (Mg), aluminum (Al), calcium (Ca), niobium (Nb), cobalt (Co) or yttrium (Y), wherein x = 0.5-0.9 and wherein y = 0-0.3; or lithium nickel cobalt manganese aluminum oxide (NCMA) having the molecular formula LiNiCoMnAlO2; Negative electrode current collector; as well as A negative electrode is disposed on the surface of the negative electrode current collector, the negative electrode having an active material including graphite, wherein the negative electrode current collector and the negative electrode are disposed close to the positive electrode current collector and the positive electrode, and wherein the negative electrode and the positive electrode are separated by a membrane.

2. The vehicle battery cell based on lithium manganese iron phosphate (LMFP) according to claim 1, wherein, The energy density of the vehicle battery cell is 460-580 Wh / L.

3. The vehicle battery cell based on lithium manganese iron phosphate (LMFP) according to claim 1, wherein, The vehicle battery unit is at least one of a prismatic unit or a pouch unit.

4. The vehicle battery cell based on lithium manganese iron phosphate (LMFP) according to claim 1, wherein, The positive current collector is aluminum.

5. The vehicle battery cell based on lithium manganese iron phosphate (LMFP) according to claim 1, wherein, The active material of the positive electrode comprises a mixture of LMFP and NCMA, wherein LMFP is greater than 50% of the mixture.

6. The vehicle battery cell based on lithium manganese iron phosphate (LMFP) according to claim 1, wherein, The active material of the positive electrode has LiMn 0.75 Fe 0.25 The molecular formula of PO4.

7. The vehicle battery cell based on lithium manganese iron phosphate (LMFP) according to claim 1, wherein, The capacity load of the positive electrode is approximately 3.3 mAh / cm². 2 ).

8. The vehicle battery cell based on lithium manganese iron phosphate (LMFP) according to claim 1, wherein, The porosity of the positive electrode is 35% ± 8%.

9. The vehicle battery cell based on lithium manganese iron phosphate (LMFP) according to claim 1, wherein, The negative electrode is formed from at least one of artificial graphite (AG) or natural graphite (NG).

10. The vehicle battery cell based on lithium manganese iron phosphate (LMFP) according to claim 1, wherein, The negative electrode is formed from a mixture of approximately 50% artificial graphite (AG) and approximately 50% natural graphite (NG).

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