Nickel-containing positive electrode slurries with reduced or eliminated gelation and high energy density positive electrodes for electrochemical cells

Abstract

The present application relates to nickel-containing positive electrode slurries with reduced or eliminated gelation and high energy density positive electrodes for electrochemical cells. The electrode precursor or slurry according to various aspects of the present disclosure comprises a blended electroactive material and a binder solution. The blended electroactive material comprises a first electroactive material and a second electroactive material. The first electroactive material contains nickel. The first electroactive material is selected from LiNi wherein x is greater than 0.6. x Co y Mn z O 2 , LiNi where x is greater than 0.6 x Co y Al z O 2 , LiNi where x is greater than 0.6 x Co y Mn z Al α O 2 , or any combination thereof. The second electroactive material comprises an olivine-type phosphate compound of less than or equal to about 30% by weight of the blended electroactive material. The binder solution comprises a polymer binder and a solvent containing N-methyl-2-pyrrolidone. In various aspects, the present disclosure provides a high nickel content positive electrode formed from the slurry. In various aspects, the present disclosure provides an electrochemical cell including the positive electrode and a lithium metal negative electrode.

Description

Technical Field

[0001] The present application relates to nickel-containing positive electrode slurries with reduced or eliminated gelation and high energy density positive electrodes for electrochemical cells. Background Art

[0002] This section provides background information related to the present disclosure which is not necessarily prior art.

[0003] The present disclosure relates to nickel-containing positive electrode slurries with reduced or eliminated gelation and high energy density positive electrodes for electrochemical cells.

[0004] High energy density electrochemical cells such as lithium-ion batteries can be used in a variety of consumer products and vehicles, such as electric or hybrid electric vehicles. As technological advances continue to be made in battery power and life, battery-powered vehicles show promise as a transportation option. Summary of the invention

[0005] This section provides a general summary of the disclosure, and is not a comprehensive disclosure of its full scope or all of its features.

[0006] In various aspects, the present disclosure provides an electrode precursor in the form of a slurry for making a high nickel content positive electrode for an electrochemical cell. The electrode slurry comprises a blended electroactive material and a binder solution. The blended electroactive material comprises a first electroactive material and a second electroactive material. The first electroactive material contains nickel. The first electroactive material is selected from LiNi wherein x is greater than 0.6 x Co y Mn z O2, LiNi where x is greater than 0.6 x Co y Al z O2, LiNi where x is greater than 0.6 x Co y Mn z Al α O2, or any combination thereof. The second electroactive material comprises less than or equal to about 30% by weight of an olivine phosphate compound of the blended electroactive material. The binder solution comprises a polymer binder and a solvent containing N-methyl-2-pyrrolidone.

[0007] In one aspect, the first electroactive material is selected from LiNi wherein x is greater than or equal to 0.8 x Co y Mn zO2, LiNi where x is greater than or equal to 0.8 x Co y Al z O2, LiNi where x is greater than or equal to 0.8 x Co y Mn z Al α O2, or any combination thereof.

[0008] In one aspect, the first electroactive material is selected from LiNi wherein x is greater than or equal to 0.85 x Co y Mn z O2, LiNi where x is greater than or equal to 0.85 x Co y Al z O2, LiNi where x is greater than or equal to 0.85 x Co y Mn z Al α O2, or any combination thereof.

[0009] In one aspect, the first electroactive material includes NMC 811, NMCA, or both NMC 811 and NMCA.

[0010] In one aspect, the second electroactive material comprises Li-M 1 -M 2 -PO4, where M 1 is the first transition metal and M 2 A second transition metal different from the first transition metal.

[0011] In one aspect, the second electroactive material comprises LiFe x M 1-x -PO4, wherein M is a transition metal and x is greater than 0 to less than 1.

[0012] In one aspect, the second electroactive material comprises LMFP.

[0013] In one aspect, the blended electroactive material comprises less than or equal to about 20 weight percent of the second electroactive material.

[0014] In one aspect, the paste further comprises a conductive material.

[0015] In one aspect, the polymer binder is selected from polyvinylidene fluoride, polyacrylic acid, styrene butadiene rubber, polytetrafluoroethylene, or any combination thereof.

[0016] In one aspect, the electrode slurry has a pH of less than or equal to about 12.5.

[0017] In various aspects, the present disclosure also provides a positive electrode for an electrochemical cell. The positive electrode comprises a blended electroactive material and a polymer binder. The blended electroactive material comprises a first electroactive material and a second electroactive material. The first electroactive material contains nickel. The first electroactive material is selected from LiNi wherein x is greater than 0.6 x Co y Mn z O2, LiNi where x is greater than 0.6 x Co y Al z O2, LiNi where x is greater than 0.6 x Co y Mn z Al α O2, or any combination thereof. The second electroactive material comprises less than or equal to about 30% by weight of the blended electroactive material of the olivine-type phosphate compound.

[0018] In one aspect, the positive electrode defines an average thickness of greater than or equal to about 75 μm to less than or equal to about 100 μm.

[0019] In one aspect, the positive electrode is substantially free of acetic acid.

[0020] In one aspect, the first electroactive material is selected from LiNi wherein x is greater than or equal to 0.8 x Co y Mn z O2, LiNi where x is greater than or equal to 0.8 x Co y Al z O2, LiNi where x is greater than or equal to 0.8 x Co y Mn z Al α O2, or any combination thereof.

[0021] In one aspect, the second electroactive material comprises Li-M 1 -M 2 -PO4, where M 1 is the first transition metal and M 2 A second transition metal different from the first transition metal.

[0022] In one aspect, the first electroactive material comprises NMC 811 and the second electroactive material comprises LMFP.

[0023] In one aspect, the positive electrode further comprises a conductive material.

[0024] In one aspect, the polymer binder is selected from polyvinylidene fluoride, polyacrylic acid, styrene butadiene rubber, polytetrafluoroethylene, or any combination thereof.

[0025] In various aspects, the present disclosure also provides an electrochemical cell comprising a positive electrode, a negative electrode and an electrolyte. The positive electrode comprises a blended electroactive material and a polymer binder. The blended electroactive material comprises a first electroactive material and a second electroactive material. The first electroactive material contains nickel. The first electroactive material is selected from LiNi wherein x is greater than 0.6. x Co y Mn z O2, LiNi where x is greater than 0.6 x Co y Al z O2, LiNi where x is greater than 0.6 x Co y Mn z Al α O2, or any combination thereof. The second electroactive material comprises an olivine-type phosphate compound of less than or equal to about 30 weight % of the blended electroactive material. The negative electrode comprises lithium metal. The electrolyte is between the positive electrode and the negative electrode.

[0026] Further areas of applicability will become apparent from the description provided herein.The description and specific examples in this summary are intended for purposes of illustration only and are not intended to limit the scope of the present disclosure. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] The drawings described herein are for illustrative purposes only of selected embodiments and not all possible implementations, and are not intended to limit the scope of the present disclosure.

[0028] Figure 1 is a schematic diagram of an electrochemical cell for cycling lithium ions;

[0029] Figure 2 is a schematic diagram of a high nickel content positive electrode slurry according to various aspects of the present disclosure;

[0030] Figure 3 According to various aspects of the present disclosure Figure 2 A schematic cross-sectional view of a high nickel content positive electrode formed by a slurry;

[0031] Figures 4A-4C is a photograph of an electrode slurry according to certain aspects of the present disclosure; Figure 4A Including NMC 622; Figure 4B including NMC 811; and Figure 4C Including NCMA;

[0032] Figure 5A-5Bis a graph depicting the pH of electrode slurries having different electroactive material blends according to various aspects of the present disclosure; Figure 5A Related to cathode materials in deionized (DI) water; and Figure 5B Involving cathode materials in DI water and NMP solvents;

[0033] Figures 6A-6D are scanning electron microscope (SEM) images of electrodes having different electroactive material blends and / or preparation methods according to various aspects of the present disclosure; Fig. 6A An electrode having an electroactive material comprising 100 wt % NMC811 prepared in air is depicted; Figure 6B An electrode with an electroactive material comprising 100 wt % NMC 811 prepared in a glove box is depicted; Figure 6C prepared in air and having an electroactive material comprising 80 wt % NMC 811 and 20 wt % LMFP; and Fig.6D prepared in air and having an electroactive material comprising 50 wt % NMC 811 and 50 wt % LMFP;

[0034] Figure 7 is a graph depicting energy density as a function of electroactive material blends according to various aspects of the present disclosure;

[0035] Figures 8A-8C relates to single-sided electrode thickness as a function of electroactive material blends according to various aspects of the present disclosure; Fig. 8A is a graph depicting single-side electrode thickness as a function of electroactive material blend; Figure 8B is a SEM image of an electrode having 100 wt % NMC 811 as the electroactive material; and Figure 8C is a SEM image of an electrode having a blended electroactive material comprising 70 wt % NMC 811 and 30 wt % LMFP; and

[0036] Figures 9A-9B Performance of electrochemical cells according to various aspects of the present disclosure; Fig. 9A is a graph depicting capacity conservation; and Fig. 9B is a graph depicting the voltage lines for charging and discharging.

[0037] Corresponding reference numerals indicate corresponding parts throughout the several views of the drawings. DETAILED DESCRIPTION

[0038] Exemplary embodiments are provided so that the present disclosure will be thorough and will fully convey its scope to those skilled in the art. Many specific details, such as examples of specific compositions, components, devices and methods, are set forth to provide a full understanding of the embodiments of the present disclosure. It will be apparent to those skilled in the art that specific details need not be used, that the exemplary embodiments may be embodied in many different forms, and that none of them should be considered to limit the scope of the present disclosure. In some exemplary embodiments, well-known methods, well-known device structures, and well-known technologies are not described in detail.

[0039] The terms used herein are intended only to describe specific exemplary embodiments and are not intended to be limiting. Unless the context clearly indicates otherwise, the singular forms "one", "a kind of" and "the" as used herein may be intended to also include plural forms. The terms "comprise", "include", "contain" and "have" are inclusive, thus illustrating the presence of the described features, elements, compositions, steps, integers, operations and / or components, but do not exclude the presence or addition of one or more other features, integers, steps, operations, elements, components and / or their collections. Although the open term "comprise" should be understood as a non-limiting term for describing and claiming the various embodiments described herein, in some aspects, the term may be alternatively understood as a more restrictive and limited term, such as "consisting of" or "consisting essentially of". Thus, for any given embodiment of a narration composition, material, component, element, feature, integer, operation and / or process step, the present disclosure also particularly includes an embodiment consisting of or essentially consisting of such a composition, material, component, element, feature, integer, operation and / or process step. In the case of "consisting of," alternative embodiments exclude any additional compositions, materials, components, elements, features, integers, operations and / or process steps, while in the case of "consisting essentially of," any additional compositions, materials, components, elements, features, integers, operations and / or process steps that materially affect the basic and novel characteristics are excluded from such embodiments, but any compositions, materials, components, elements, features, integers, operations and / or process steps that do not materially affect the basic and novel characteristics may be included in the embodiments.

[0040] Any method steps, processes, and operations described herein are not to be construed as necessarily requiring their performance in the particular order discussed or illustrated, unless specifically identified as a certain order of performance. It is also to be understood that additional or alternative steps may be used unless otherwise stated.

[0041] When a part, element or layer is referred to as being "on," "engaged," "connected," or "coupled" to another element or layer, it may be directly on, engaged, connected, or coupled to another part, element or layer, or there may be intermediate elements or layers. Conversely, when an element is referred to as being directly on, "directly engaged," "directly connected," or "directly coupled" to another element or layer, there may be no intermediate elements or layers. Other words used to describe the relationship between elements should be interpreted in a similar manner (e.g., "between" vs. "directly between," "adjacent" vs. "directly adjacent," etc.). As used herein, the term "and / or" includes any and all combinations of one or more of the associated enumerated items.

[0042] Although the terms first, second, third, etc. can be used to describe various steps, elements, components, regions, layers and / or sections in this article, these steps, elements, components, regions, layers and / or sections should not be limited by these terms unless otherwise specified. These terms can only be used to distinguish a step, element, component, region, layer or section from another step, element, component, region, layer or section. Unless clearly stated in the context, terms such as "first", "second" and other numerical terms do not imply order or sequence when used in this article. Therefore, the first step, element, component, region, layer or section discussed below can be referred to as the second step, element, component, region, layer or section without departing from the teaching of exemplary embodiments.

[0043] For ease of description, spatial or temporal relative terms may be used herein, such as "before", "after", "inside", "outside", "below", "beneath", "lower", "upper", etc. to describe the relationship of one element or feature relative to other elements or features shown in the figures. Spatial or temporal relative terms may be intended to include different orientations of a device or system in use or operation in addition to the orientation shown in the figures.

[0044] Throughout this disclosure, numerical values ​​represent approximate measured values ​​or range limits to include slight deviations from given values ​​and embodiments with roughly listed values ​​and embodiments with exactly listed values.Except in the examples provided at the end of the detailed description part, all numerical values ​​of parameters (such as amounts or conditions) in this specification (including the appended claims) should be understood to be modified by the term "about" in all cases, regardless of whether "about" actually appears before the numerical value. "About" means that the numerical value allows certain slight imprecision (some close to the exact value; roughly or reasonably close to the value; almost). If the imprecision provided by "about" is not understood in this art with this common meaning, then "about" used herein at least refers to the variation that may be caused by the common method of measuring and using such parameters.For example, "about" can include less than or equal to 5%, optionally less than or equal to 4%, optionally less than or equal to 3%, optionally less than or equal to 2%, optionally less than or equal to 1%, optionally less than or equal to 0.5% and optionally less than or equal to 0.1% variation in some aspects.

[0045] Additionally, disclosure of ranges includes disclosure of all values ​​within the entire range and further subdivided ranges, including endpoints and subranges given within those ranges.

[0046] Example embodiments will now be described more fully with reference to the accompanying drawings.

[0047] The present technology relates to rechargeable lithium-ion batteries, which can be used in vehicle applications. However, the present technology can also be used in other electrochemical devices that circulate lithium ions, such as handheld electronic devices or energy storage systems (ESS).

[0048] General electrochemical cell function, structure and composition

[0049] Electrochemical cells typically include a first electrode, such as a positive electrode or cathode, a second electrode, such as a negative electrode or anode, an electrolyte, and a separator. Typically, in a lithium-ion battery pack, the electrochemical cells are electrically connected in a stack to increase the total output. Lithium-ion electrochemical cells work by reversibly transferring lithium ions between a negative electrode and a positive electrode. A separator and an electrolyte are disposed between the negative electrode and the positive electrode. The electrolyte is suitable for conducting lithium ions and may be in the form of a liquid, gel, or solid. The lithium ions move from the positive electrode to the negative electrode during charging of the battery and move in the opposite direction when the battery is discharged.

[0050] Each of the negative and positive electrodes within the stack is typically electrically connected to a current collector (e.g., a metal such as copper for the negative electrode and aluminum for the positive electrode). During use of the battery, the current collectors associated with the two electrodes are connected by an external circuit that allows an electric current generated by the electrons to pass between the negative and positive electrodes to compensate for the transport of lithium ions.

[0051] The electrodes are typically incorporated into a variety of commercial battery designs, such as square cells, wound cylindrical cells, coin cells, pouch cells, or other suitable battery shapes. The battery may include a single electrode structure of each polarity or a stacked structure having multiple positive and negative electrodes assembled in parallel and / or series electrical connection. In particular, the battery may include a stack of alternating positive and negative electrodes, wherein a separator is disposed between the alternating positive and negative electrodes. Although the positive electrode electroactive material can be used in a battery for one-time or single charge use, the resulting battery typically has the desired cycling properties for secondary battery uses based on multiple cycles of the battery.

[0052] Figure 1 An exemplary schematic diagram of a lithium-ion battery 20 is shown in FIG. The lithium-ion battery 20 includes a negative electrode 22, a positive electrode 24, and a porous separator 26 (e.g., a microporous or nanoporous polymer separator) disposed between the negative electrode 22 and the positive electrode 24. An electrolyte 30 is disposed between the negative electrode 22 and the positive electrode 24 and in the pores of the porous separator 26. The electrolyte 30 may also be present in the negative electrode 22 and the positive electrode 24, such as in the pores.

[0053] The negative electrode current collector 32 may be located at or near the negative electrode 22. The positive electrode current collector 34 may be located at or near the positive electrode 24. Although not shown, the negative electrode current collector 32 and the positive electrode current collector 34 may be coated on one or both sides. In some aspects, the current collector may be coated with an electroactive material / electrode layer on both sides. The negative electrode current collector 32 and the positive electrode current collector 34 collect free electrons from an external circuit 40 and transfer free electrons to the external circuit 40, respectively. The interruptible external circuit 40 includes a load device 42 connecting the negative electrode 22 (via the negative electrode current collector 32) and the positive electrode 24 (via the positive electrode current collector 34).

[0054] The porous separator 26 works as both an electrical insulator and a mechanical support. More specifically, the porous separator 26 is disposed between the negative electrode 22 and the positive electrode 24 to prevent or reduce physical contact, and thus prevent or reduce the occurrence of a short circuit. In addition to providing a physical barrier between the two electrodes 22, 24, the porous separator 26 can also provide a path of least resistance for the internal passage of lithium ions (and associated anions) during lithium ion cycling to facilitate the operation of the lithium ion battery 20.

[0055] The lithium-ion battery 20 can generate current during discharge through a reversible electrochemical reaction that occurs when the negative electrode 22 contains a relatively larger amount of cyclable lithium when the external circuit 40 is closed (to electrically connect the negative electrode 22 and the positive electrode 24). The chemical potential difference between the positive electrode 24 and the negative electrode 22 drives electrons generated by oxidation of lithium (e.g., intercalated / alloyed / plated lithium) at the negative electrode 22 to flow to the positive electrode 24 through the external circuit 40. Lithium ions, which are also generated at the negative electrode, simultaneously transfer to the positive electrode 24 through the electrolyte 30 and the porous separator 26. The electrons flow through the external circuit 40 and the lithium ions migrate through the porous separator 26 in the electrolyte 30 to be intercalated / alloyed / plated into the positive electroactive material of the positive electrode 24. The current through the external circuit 40 can be controlled and directed through the load device 42 until the lithium in the negative electrode 22 is depleted and the capacity of the lithium-ion battery 20 is reduced.

[0056] The lithium-ion battery 20 can be charged or recharged at any time by connecting an external power source (e.g., a charging device) to the lithium-ion battery 20 to reverse the electrochemical reactions that occurred during the battery discharge. The connection of the external power source to the lithium-ion battery 20 forces the lithium ions at the positive electrode 24 to move back to the negative electrode 22. The electrons, which flow back to the negative electrode 22 through the external circuit 40, and the lithium ions, which are carried by the electrolyte 30 through the separator 26 back to the negative electrode 22, recombine at the negative electrode 22 and replenish lithium for consumption during the next battery discharge cycle. In this way, each discharge and charge event is considered a cycle in which lithium ions circulate between the positive electrode 24 and the negative electrode 22.

[0057] The external power source that can be used to charge the lithium-ion battery pack 20 can vary depending on the size, configuration, and specific end use of the lithium-ion battery pack 20. Some notable and exemplary external power sources include, but are not limited to, an AC power source, such as an AC wall outlet or a motor vehicle alternator. A converter can be used to change AC to DC to charge the battery pack 20.

[0058] In many lithium-ion battery configurations, each of the negative electrode current collector 32, the negative electrode 22, the separator 26, the positive electrode 24, and the positive electrode current collector 34 is prepared as a relatively thin layer (e.g., a thickness of from a few microns to 1 mm or less) and is assembled into layers connected in an electrical series and / or parallel arrangement to provide suitable electrical energy and power packaging. In addition, the lithium-ion battery 20 may include various other components that are known to those skilled in the art, although not shown here. For example, as a non-limiting example, the lithium-ion battery 20 may include a housing, a gasket, an end cap, a tab, a battery terminal, and any other conventional components or materials that may be located within the battery 20 (including between or around the negative electrode 22, the positive electrode 24, and / or the separator 26). As described above, the size and shape of the lithium-ion battery 20 may vary depending on the specific application for which it is designed. Battery-powered vehicles and handheld consumer electronic devices are two examples in which the lithium-ion battery 20 will most likely be designed to different sizes, capacities, and power output specifications. The lithium-ion battery pack 20 may also be connected in series or in parallel with other similar lithium-ion cells or battery packs to produce a greater voltage output, energy, and / or power required by the load device 42 .

[0059] Thus, the lithium-ion battery pack 20 can generate current to a load device 42 that can be operatively connected to an external circuit 40. While the load device 42 can be any number of known electrical energy supply devices, some specific examples of power-consuming load devices include, as non-limiting examples, electric motors for hybrid or all-electric vehicles, laptop computers, tablet computers, mobile phones, and cordless power tools or appliances. The load device 42 can also be a power generation device that charges the lithium-ion battery pack 20 for stored energy. In certain other variations, the electrochemical cell can be a supercapacitor, such as a lithium-ion-based supercapacitor.

[0060] Electrolytes

[0061] Any suitable electrolyte 30 capable of conducting lithium ions between the negative electrode 22 and the positive electrode 24, whether in solid, liquid or gel form, can be used in the lithium ion battery 20. In some aspects, the electrolyte 30 can be a non-aqueous liquid electrolyte solution that includes one or more lithium salts dissolved in an organic solvent or an organic solvent mixture. Many non-aqueous liquid electrolyte 30 solutions can be used in the lithium ion battery 20. In some variations, the electrolyte 30 can include an aqueous solvent (i.e., a water-based solvent) or a mixed solvent (e.g., an organic solvent containing at least 1% by weight water).

[0062] Suitable lithium salts generally have inert anions. Non-limiting examples of lithium salts that can be dissolved in an organic solvent to form the non-aqueous liquid electrolyte solution include lithium hexafluorophosphate (LiPF6); lithium perchlorate (LiClO4); lithium tetrachloroaluminate (LiAlCl4); lithium iodide (LiI); lithium bromide (LiBr); lithium thiocyanate (LiSCN); lithium tetrafluoroborate (LiBF4); lithium difluorooxalatoborate (LiBF2(C2O4))(LiODFB), lithium tetraphenylborate (LiB(C6H5)4 ); lithium bis(oxalate)borate (LiB(C2O4)2) (LiBOB); lithium tetrafluorooxalatephosphate (LiPF4(C2O4)) (LiFOP), lithium nitrate (LiNO3), lithium hexafluoroarsenate (LiAsF6); lithium trifluoromethanesulfonate (LiCF3SO3); lithium bis(trifluoromethanesulfonimide) (LITFSI) (LiN(CF3SO2)2); lithium fluorosulfonyl imide (LiN(FSO2)2) (LIFSI); and combinations thereof. In certain variations, the electrolyte 30 may include a 1.2M concentration of the lithium salt.

[0063] These lithium salts can be dissolved in various organic solvents, such as, for example, organic ethers or organic carbonates. Organic ethers can include dimethyl ether, glycol dimethyl ether (ethylene glycol dimethyl ether or dimethoxyethane (DME, such as 1,2-dimethoxyethane)), diethylene glycol dimethyl ether (diethylene glycol dimethyl ether or bis (2-methoxyethyl) ether), triethylene glycol dimethyl ether (tri(ethylene glycol) dimethyl ether), other chain structure ethers, such as 1,2-diethoxyethane, ethoxymethoxyethane, 1,3-dimethoxypropane (DMP), cyclic ethers, such as tetrahydrofuran, 2-methyltetrahydrofuran, and combinations thereof. In some variations, the organic ether compound is selected from tetrahydrofuran, 2-methyltetrahydrofuran, dioxolane, dimethoxyethane (DME), diglyme (diethylene glycol dimethyl ether), triglyme (tri(ethylene glycol) dimethyl ether), 1,3-dimethoxypropane (DMP) and combinations thereof. The carbonate-based solvent may include various alkyl carbonates, such as cyclic carbonates (e.g., ethylene carbonate (EC), propylene carbonate (PC), butylene carbonate) and acyclic carbonates (e.g., dimethyl carbonate (DMC), diethyl carbonate (DEC), ethyl methyl carbonate (EMC)). The ether-based solvent includes cyclic ethers (e.g., tetrahydrofuran, 2-methyltetrahydrofuran, 1,3-dioxolane) and chain structure ethers (e.g., 1,2-dimethoxyethane, 1,2-diethoxyethane, ethoxymethoxyethane).

[0064] In various embodiments, in addition to those described above, suitable solvents may be selected from propylene carbonate, dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate, γ-butyrolactone, dimethyl sulfoxide, acetonitrile, nitromethane, and mixtures thereof.

[0065] When the electrolyte is a solid electrolyte, it may include a composition selected from the group consisting of LiTi2(PO4)3, LiGe2(PO4)3, Li7La3Zr2O 12 ,Li3xLa 2 / 3 -xTiO3, Li3PO4, Li3N, Li4GeS4, Li 10 GeP2S 12 , Li2S-P2S5, Li6PS5Cl, Li6PS5Br, Li6PS5I, Li3OCl, Li 2.99 Ba 0.005 C10 or any combination thereof.

[0066] Porous separator

[0067] In certain variations, the porous separator 26 may include a microporous polymer separator comprising a polyolefin, including those prepared from homopolymers (derived from a single monomer component) or heteropolymers (derived from more than one monomer component), which may be linear or branched. In certain aspects, the polyolefin may be polyethylene (PE), polypropylene (PP), or a blend of PE and PP, or a multilayer structured porous membrane of PE and / or PP. Commercially available polyolefin porous separator 26 membranes include CELGARD 2500 (single-layer polypropylene separator) and CELGARD 2340 (three-layer polypropylene / polyethylene / polypropylene separator) available from CELGARD LLC.

[0068] When the porous separator 26 is a microporous polymer separator, it can be a single layer or a multi-layer laminate. For example, in one embodiment, a single layer of a polyolefin can form the entire microporous polymer separator 26. In other aspects, the separator 26 can be a fiber membrane with a large number of pores extending between the opposing surfaces and can have a thickness of, for example, less than 1 mm. However, as another example, multiple independent layers of the same or different polyolefins can be assembled to form the microporous polymer separator 26. Alternatively or in addition to the polyolefin, the microporous polymer separator 26 may also include other polymers, such as but not limited to polyethylene terephthalate (PET), polyvinylidene fluoride (PVDF), polyamide (nylon), polyurethane, polycarbonate, polyester, polyetheretherketone (PEEK), polyethersulfone (PES), polyimide (PI), polyamide-imide, polyether, polyoxymethylene (e.g., acetal), polybutylene terephthalate, polyethylene naphthalate, polybutylene, polymethylpentene, polyolefin copolymers, acrylonitrile-butadiene-styrene copolymers (ABS), polystyrene copolymers, polymethyl methacrylate (PMMA), polysiloxane polymers (e.g., polydimethylsiloxane (PDMS)), polybenzimidazole (PBI), polybenzoxazole (PBO), polyphenylene, polyarylene ether ketone (polyarylene ether ketone ... ketones), polyperfluorocyclobutane, polyvinylidene fluoride copolymers (e.g., PVdF-hexafluoropropylene or (PVDF-HFP)) and polyvinylidene fluoride terpolymers, polyvinyl fluoride, liquid crystal polymers (e.g., VECTRAN (Hoechst AG, Germany) and ZENITE (DuPont, Wilmington, DE)), polyaramids, polyphenylene ethers, cellulosic materials, mesoporous silica, or combinations thereof.

[0069] In addition, the porous separator 26 can be mixed with a ceramic material or its surface can be coated with a ceramic material. For example, the ceramic coating can contain aluminum oxide (Al2O3), silicon dioxide (SiO2) or a combination thereof. Various commercially available polymers and commercially available products for forming the separator 26 are contemplated, as well as many manufacturing methods that can be used to produce such a microporous polymer separator 26.

[0070] Solid electrolyte

[0071] In various aspects, the porous separator 26 and the electrolyte 30 may be replaced by a solid electrolyte (SSE) that functions as both an electrolyte and a separator. The SSE may be disposed between the positive electrode and the negative electrode. The SSE facilitates the transport of lithium ions while mechanically separating the negative and positive electrodes 22, 24 and providing electrical insulation between the negative and positive electrodes 22, 24. As non-limiting examples, the SSE may include LiTi2(PO4)3, Li 1.3 Al0.3 Ti 1.7 (PO4)3(LATP), LiGe2(PO4)3, Li7La3Zr2O 12 、Li3xLa 2 / 3 -xTiO3, Li3PO4, Li3N, Li4GeS4, Li 10 GeP2S 12 , Li2S-P2S5, Li6PS5Cl, Li6PS5Br, Li6PS5I, Li3OCl, Li 2.99 Ba 0.005 ClO or a combination thereof.

[0072] current collector

[0073] The negative electrode 22 and the positive electrode 24 are usually connected to the corresponding negative electrode current collector 32 and the positive electrode current collector 34 to facilitate the flow of electrons between the electrodes and the external circuit 40. The current collectors 32, 34 are conductive and can include metals, such as metal foils, metal grids or nets, or expanded metals. Expanded metal current collectors refer to metal grids with greater thickness, so that a greater amount of electrode material is placed in the metal grid. As non-limiting examples, conductive materials include copper, nickel, aluminum, stainless steel, titanium, alloys thereof, or combinations thereof.

[0074] The positive electrode current collector 34 may be formed of aluminum or any other suitable conductive material known to those skilled in the art. The negative electrode current collector 32 may be formed of copper or any other suitable conductive material known to those skilled in the art. The negative electrode current collector typically does not contain aluminum because aluminum reacts with lithium, causing large volume expansion and contraction. Drastic volume changes may result in rupture and / or pulverization of the current collector.

[0075] Positive and negative electrodes

[0076] The positive electrode 24 may be formed of or include a lithium-based active material that may undergo lithium insertion and extraction, alloying and alloy degradation, or plating and stripping while serving as a positive terminal for the lithium-ion battery 20. The positive electrode 24 may include a positive electroactive material. The positive electroactive material may include one or more transition metal cations, such as manganese (Mn), nickel (Ni), cobalt (Co), chromium (Cr), iron (Fe), vanadium (V), and combinations thereof.

[0077] The positive electrode electroactive material can be a powder composition. The positive electrode electroactive material can be blended with an optional conductive material (eg, conductive particles) and a polymer binder. The binder can hold the positive electrode electroactive material together and provide ionic conductivity to the positive electrode 24.

[0078] The negative electrode 22 may include a negative electrode electroactive material that is a lithium host material capable of serving as a negative terminal of the lithium ion battery 20. Common negative electrode electroactive materials include lithium insertion materials or alloy host materials. Such materials may include carbon-based materials such as lithium-graphite intercalation compounds, lithium-silicon compounds, lithium-tin alloys, or lithium titanate Li. 4+x Ti5O 12 , where 0≤x≤3, such as Li4Ti5O 12 (LTO).

[0079] In certain aspects, the negative electrode 22 includes metallic lithium and the negative electrode 22 is a lithium metal electrode (LME). The lithium ion battery 20 can be a lithium metal battery or battery. Metallic lithium in the negative electrode for rechargeable batteries has various potential advantages, including having the highest theoretical capacity and the lowest electrochemical potential. Therefore, batteries incorporating lithium metal anodes can have higher energy density that can potentially double the storage capacity, allowing the battery to be half the size but still maintain the same amount of time as other lithium ion batteries.

[0080] In some variations, the negative electrode 22 may optionally include a conductive material, and one or more polymer binder materials to structurally hold the lithium material together. For example, in one embodiment, the negative electrode 22 may include an active material containing lithium metal particles blended with a binder material, the binder material being selected from: polyvinylidene fluoride, ethylene propylene diene monomer (EPDM) rubber, carboxymethyl cellulose (CMC), nitrile rubber (NBR), lithium polyacrylate (LiPAA), sodium polyacrylate (NaPAA), sodium alginate, lithium alginate, or a combination thereof. Suitable additional conductive materials may include carbon-based materials or conductive polymers. Carbon-based materials may include, for example, particles of KETJEN black, DENKA black, acetylene black, carbon black, etc. Examples of conductive polymers include polyaniline, polythiophene, polyacetylene, polypyrrole, etc. In some aspects, a mixture of conductive materials may be used. The negative electrode 22 may include about 50-100% by weight of an electroactive material (e.g., lithium particles or lithium foil), optionally greater than or equal to about 30% by weight of a conductive material, and a balance of binder.

[0081] Electrode manufacturing

[0082] In various aspects, the negative electrode 22 and the positive electrode 24 can be made by mixing the corresponding electroactive materials into a slurry having a polymer binder compound, a non-aqueous solvent, an optional plasticizer, and optionally conductive particles. The slurry can be mixed or stirred and then applied thinly to a substrate by a doctor blade and / or slot die coating. The substrate can be a removable substrate, or alternatively, the substrate can be a functional substrate, such as a current collector (e.g., a metal grid or mesh layer) bonded to one side of the electrode film. In one variation, heat or radiation can be applied to evaporate the solvent from the electrode film, leaving a solid residue. The electrode film can be further consolidated, where heat and pressure are applied to the film to sinter and calender it. In other variations, the film can be dried at a moderate temperature to form a self-supporting film. If the substrate is removable, the substrate is removed from the electrode film and the electrode film is further laminated to the current collector. For either type of substrate, the remaining plasticizer can be extracted before being incorporated into the battery cell. In various aspects, solid electrodes can be formed according to alternative manufacturing methods.

[0083] Optional electrode surface coating

[0084] In certain variations, the prefabricated negative electrode 22 and positive electrode 24 formed by casting the above-mentioned active material slurry can be directly coated via a vapor phase coating formation process to form a conformal inorganic-organic composite surface coating, as further described below. Thus, one or more exposed areas of the prefabricated negative electrode containing the electroactive material can be coated to minimize or prevent the reaction of the electrode material with the components within the electrochemical cell to minimize or prevent the formation of lithium metal dendrites on the surface of the negative electrode material when incorporated into the electrochemical cell. In other variations, multiple particles containing electroactive materials such as lithium metal can be coated with an inorganic-organic composite surface coating. Then, as described above, the coated electroactive particles can be used in an active material slurry to form a negative electrode.

[0085] High nickel content positive electrode

[0086] High nickel content positive electrode electroactive materials are promising in terms of energy density. However, these active materials may be susceptible to manufacturing challenges that lead to poor uniformity and morphology. More specifically, during electrode preparation, a slurry of high nickel content positive electrode electroactive materials, polymer binders, solvents, and optional conductive materials may have a high pH, ​​for example, above 12. At the high pH, ​​at least a portion of the polymer binder may desolvate, causing gelation and inhibiting the ability of the slurry to be coated on a current collector or otherwise formed into an electrode. Some electrode slurries may include a pH adjuster. For example, a negative electrode slurry may include acetic acid to reduce the pH. However, the inclusion of acetic acid in the positive electrode may damage the electroactive material, resulting in reduced performance.

[0087] In various aspects, the present disclosure provides an electrode precursor in the form of an electrode slurry for forming a high nickel content, high energy density positive electrode for an electrochemical cell. The electrode slurry comprises a first electroactive material, a second electroactive material, a polymer binder, and a solvent containing N-methyl-2-pyrrolidone (NMP). The first electroactive material contains nickel. The second electroactive material comprises an olivine-type phosphate compound with mixed cations. Compared with a slurry without an olivine-type phosphate compound, the olivine-type phosphate compound reduces the pH of the electrode slurry. The reduction in pH can reduce or prevent the gelation of the slurry. A high nickel content, high energy density positive electrode can be prepared from the slurry.

[0088] Reference Figure 2 , an electrode slurry 110 according to various aspects of the present disclosure is provided. The electrode slurry 110 includes a blended electroactive material, which includes a first electroactive material 112 and a second electroactive material 114. As used herein, "blended" means including at least two different electroactive materials and does not require the two electroactive materials to be uniformly mixed. The slurry 110 may optionally further include a conductive material 116. The slurry 110 also includes a binder solution 118, and the binder solution 118 includes a polymer binder 120 ( Figure 3 ) and NMP solvent. In certain aspects, slurry 110 is substantially free of acetic acid.

[0089] In certain aspects, slurry 110 comprises a blended electroactive material having a dry weight of greater than or equal to about 80 wt % to less than or equal to about 98 wt %. In certain aspects, slurry 110 comprises a conductive material 116 having a dry weight of greater than or equal to about 0.5 wt % to less than or equal to about 5 wt %. In certain aspects, slurry 110 comprises a polymer binder having a dry weight of greater than or equal to about 0.5 wt % to less than or equal to about 5 wt %.

[0090] The blended electroactive material may include less than or equal to about 30 wt %, optionally less than or equal to about 25 wt %, optionally less than or equal to about 20 wt %, or optionally less than or equal to about 15 wt % of the second electroactive material. The blended electroactive material may include greater than 0 wt %, optionally greater than or equal to 5 wt %, optionally greater than or equal to 10 wt %, optionally greater than or equal to 15 wt %, optionally greater than or equal to 20 wt %, or optionally greater than or equal to 25 wt % of the second electroactive material. In certain aspects, the blended electroactive material consists essentially of the first electroactive material and the second electroactive material.

[0091] The pH of the slurry 110 decreases as the amount of the second electroactive material in the blended electroactive material increases (see Example 2). In certain aspects, the pH of the slurry is less than or equal to about 12.5, optionally less than or equal to about 12, optionally less than or equal to about 11.5, optionally less than or equal to about 11, optionally less than or equal to about 10.5, optionally less than or equal to about 10. Typically, the positive electrode formed from the slurry (see, e.g., Figure 3 The positive electrode 130) has an energy density that increases as the amount of the first electroactive material increases.

[0092] The first electroactive material 112 contains nickel. In certain aspects, the first electroactive material 112 is a high nickel content positive electroactive material. The high nickel content positive electroactive material may include Li, O2, and a nickel compound. The nickel compound may include, for example, Ni, Co, and Mn and / or Al. The nickel compound may include greater than or equal to about 60 mol%, optionally greater than or equal to about 60 mol%, optionally greater than or equal to about 65 mol%, optionally greater than or equal to about 70 mol%, optionally greater than or equal to about 75 mol%, optionally greater than or equal to about 80 mol%, optionally greater than or equal to about 85 mol%, or optionally greater than or equal to about 90 mol% nickel.

[0093] In certain aspects, the first electroactive material 112 is selected from: LiNi x Co y Mn z O2 (NCM) (e.g. LiNi 0.8 Co 0.1 Mn 0.1 O2(NMC 811), LiNi 0.9 Co 0.05 Mn 0.05 O2); LiNi x Co y Al z O2 (NCA) (e.g. LiNi 0.8 Co 0.15 Al 0.05 O2); LiNi x Co y Mn z Al α O2 (NCMA) (e.g. Li[Ni 0.89 Co 0.05 Mn 0.05 Al 0.01 ]O2); or any combination thereof. In some aspects, the first electroactive material 112 has a high nickel content and includes LiNi x Co y Mn zO2, wherein x is greater than 0.6 (optionally greater than or equal to about 0.7, optionally greater than or equal to about 0.75, optionally greater than or equal to about 0.8, optionally greater than or equal to about 0.85, or optionally greater than or equal to about 0.9); LiNi x Co y Al z O2, wherein x is greater than 0.6 (optionally greater than or equal to about 0.7, optionally greater than or equal to about 0.75, optionally greater than or equal to about 0.8, optionally greater than or equal to about 0.85, or optionally greater than or equal to about 0.9); LiNi x Co y Mn z Al α O2, wherein x is greater than 0.6 (optionally greater than or equal to about 0.7, optionally greater than or equal to about 0.75, optionally greater than or equal to about 0.8, optionally greater than or equal to about 0.85, or optionally greater than or equal to about 0.9); or any combination thereof. In one example, the first electroactive material 112 includes NMC 811, NMCA, or both NMC 811 and NMCA.

[0094] The second electroactive material 114 includes an olivine-type phosphate compound having mixed cations. The second electroactive material 114 may have a Li-M 1 -M 2 -PO4 form, where M 1 is the first transition metal and M 2 is a second transition metal different from the first transition metal. In some aspects, the second electroactive material 114 comprises LiFe x M 1–x PO4, where M is a transition metal and 0<x<1. For example, the second electroactive material 114 may include lithium manganese iron phosphate (LMFP), such as LiMn x Fe 1-x PO4, where 0<x<1. LiMn, where 0<x<1 x Fe 1-x Examples of PO4 include, for example, LiMn 0.7 Fe 0.3 PO4、LiMn 0.6 Fe 0.4 PO4、LiMn 0.8 Fe 0.2 PO4 and LiMn 0.75 Fe 0.25 PO4.

[0095] Conductive material 116 may include carbon-based materials, conductive polymers, or both. Carbon-based materials may include, for example, particles of KETJEN black, DENKA black, acetylene black, carbon black, etc. Examples of conductive polymers include polyaniline, polythiophene, polyacetylene, polypyrrole, etc.

[0096] The polymer binder in the binder solution 118 may be selected from polyvinylidene fluoride (PVDF), polyacrylic acid (PAA), styrene butadiene rubber (SBR), polytetrafluoroethylene (PTFE), or any combination thereof.

[0097] Reference Figure 3 , a positive electrode 130 according to various aspects of the present disclosure is provided. The positive electrode 130 is composed of Figure 2 The positive electrode 130 comprises a blended electroactive material comprising a first electroactive material 112 and a second electroactive material 114; a conductive material 116; and a polymer binder 120. For example, the positive electrode 130 may comprise greater than or equal to about 80% by weight to less than or equal to about 98% by weight, such as greater than or equal to about 80% by weight to less than or equal to about 85% by weight, greater than or equal to about 85% by weight to less than or equal to about 90% by weight, greater than or equal to about 90% by weight to less than or equal to about 95% by weight, greater than or equal to about 95% by weight to less than or equal to about 98% by weight of the blended electroactive material. In certain aspects, the positive electrode 130 is substantially free of acetic acid.

[0098] In certain aspects, the slurry 110 ( Figure 2 ) is advantageous for forming an electrode surface 132 with low roughness. In certain aspects, the positive electrode 130 defines a single-side thickness 140. The single-side thickness 140 may be greater than or equal to about 75 μm to less than or equal to about 100 μm.

[0099] In various aspects, the present disclosure provides an electrochemical cell including a positive electrode 130. In addition to including a positive electrode 130, the electrochemical cell may be Figure 1 The same as the lithium-ion battery pack 20 of . In some aspects, the electrochemical cell includes a negative electrode containing lithium metal. The electrochemical cell also includes an electrolyte (e.g., a liquid, gel, or solid electrolyte) and a separator. In some aspects, the electrolyte includes 1.2M LiPF6 in a fluoroethylene carbonate (FEC) / dimethyl carbonate (DMC) solvent (1:4 volume ratio). In some aspects, the electrolyte is a solid electrolyte that is also used as a separator.

[0100] In certain aspects, the electrochemical cell is configured to have a discharge capacity greater than 160 mAh / g, optionally greater than or equal to 165 mAh / g, optionally greater than or equal to 170 mAh / g, optionally greater than or equal to 175 mAh / g, or optionally greater than or equal to 180 mAh / g.

[0101] Example 1: Gelation in a high nickel content slurry

[0102] Three slurries were prepared according to various aspects of the present disclosure, each slurry having 95% by dry weight of a nickel-containing positive electrode electroactive material, 2.5% by dry weight of PVDF (as a polymer binder), and 2.5% by dry weight of conductive carbon (as a conductive material) in NMP solvent. The pH of the slurry in NMP solvent increases with increasing nickel content. In a high pH environment, for example, at a pH greater than about 12, the NMP solvent can solvate with the lithium of the electroactive material, causing at least a portion of the polymer binder to desolvate and form aggregates, which can lead to gelation of the slurry.

[0103] Reference Figure 4A The first slurry 210 according to various aspects of the present disclosure comprises 95% by dry weight of LiNi in NMP solvent. 0.6 Co 0.2 Mn 0.2 O2 (NMC 622), 2.5% PVDF by dry weight, and 2.5% conductive carbon by dry weight (about 10 g solvent per about 10 g electroactive material). At this nickel content in the electroactive material, the slurry can be applied as a substantially uniform coating (i.e., little or no gelling).

[0104] Reference Figure 4B , the second slurry 220 according to various aspects of the present disclosure comprises 95% by dry weight NMC 811, 2.5% by dry weight PVDF, and 2.5% by dry weight conductive carbon in NMP solvent (about 10 g solvent per about 10 g electroactive material). At this nickel content in the electroactive material, gelation occurs in the slurry, inhibiting the formation of a uniform slurry coating for forming an electrode.

[0105] Reference Figure 4C The third slurry 230 according to various aspects of the present disclosure comprises 95% by dry weight NMCA, 2.5% by dry weight PVDF, and 2.5% by dry weight conductive carbon in NMP solvent (about 10 g solvent per about 10 g electroactive material). NMCA has the formula LiNi x Co y Mn z Al α O2 and contains nickel with x greater than or equal to about 0.9. At this nickel content in the electroactive material, gelation occurs in the slurry, inhibiting the formation of a uniform slurry coating for forming an electrode.

[0106] The energy density of the electrode increases with increasing nickel content. However, as described above, high nickel content can increase the pH of the slurry and lead to gelation of the slurry and inhibited ability to form a substantially uniform coating from the slurry. The relative amounts of the first and second electroactive materials can be selected to reduce or prevent gelation while optimizing or maximizing energy density.

[0107] Example 2: pH reduction using olivine phosphate compounds

[0108] As described above, pH increases with increasing nickel content. By adding a second electroactive material comprising an olivine-type phosphate compound, the pH can be lowered to a level that does not cause gelation of the slurry. Several slurries were prepared having different weight ratios of the first electroactive material containing nickel and the second electroactive material comprising an olivine-type phosphate compound.

[0109] Reference Figure 5A , samples containing positive electrode material compositions according to various aspects of the present disclosure were prepared. Each sample contained 1 g of electroactive material (first electroactive material and / or second electroactive material) in 10 g of deionized (DI) water. The x-axis 310 represents the mass percentage of the second electroactive material containing LMFP. The y-axis 312 represents the pH of the sample. The first curve 314 represents a sample containing a first electroactive material containing NMP 622. The second curve 316 represents a sample containing a first electroactive material containing NMP 811. The third curve 318 represents a sample containing a first electroactive material containing NMCA.

[0110] At each LMFP content, the third curve 318 is higher than the first and second curves 314, 316, corresponding to a higher pH because NMCA has a higher nickel content than NMC 622 and NMC 811. At each LMFP content, the second curve 216 is higher than the first curve 314 because NMC 811 has a higher nickel content than NMC 622. For each curve 314, 316, 318, the pH decreases as the LMFP content increases.

[0111] Reference Figure 5B, sample positive electrode materials according to various aspects of the present disclosure were prepared. Each sample contained 1 g of electroactive material (first electroactive material and / or second electroactive material) in a solution of 5 g of DI water and 5 g of NMP solvent. The x-axis 330 represents the mass percentage of the second electroactive material containing LMFP. The y-axis 332 represents the pH of the sample. The first curve 334 represents a sample containing a first electroactive material containing NMP 622. The second curve 336 represents a sample containing a first electroactive material containing NMP 811. The third curve 338 represents a sample containing a first electroactive material containing NMCA.

[0112] At each LMFP content, the third curve 338 is higher than the first and second curves 334, 336, corresponding to a higher pH because NMCA has a higher nickel content than NMC 622 and NMC 811. At each LMFP content, the second curve 336 is higher than the first curve 334 because NMC 811 has a higher nickel content than NMC 622. For each curve 334, 336, 338, the pH decreases as the LMFP content increases. On the respective y-axes 332, 312, the curves 334, 336, 338 are generally higher than the first curve 334. Figure 5A The curves 314, 316, 318 show that the presence of NMP further increases the pH of the sample compared to DI water alone.

[0113] Example 3: Improved electrode morphology using olivine-type phosphate compounds

[0114] Four electrodes according to various aspects of the present disclosure were prepared. Each electrode contained 96% by dry weight of electroactive material, 2% by dry weight of PVDF binder, and 2% by dry weight of conductive carbon. Fig. 6A , an electrode 410 was prepared in air (i.e., a moisture-containing environment). The electrode 410 contained 100 wt % of NMC 811 electroactive material. Due to the aggregation of the PVDF binder and the gelation of the electrode slurry, the electrode 410 had a non-uniform morphology including a plurality of clusters 412.

[0115] Reference Figure 6B , electrode 420 comprises 100 wt % NMC 811 electroactive material. Electrode 420 is prepared in a glove box with a moisture controlled environment that is extremely dry with a water content of less than about 2 ppm. Fig. 6A Compared to electrode 410 , electrode 420 has improved morphology and reduced gelation.

[0116] Reference Figure 6C , the electrode 430 comprises a blended electroactive material, the blended electroactive material comprising 80 wt % of NMC811 and 20 wt % of LMFP. The electrode 430 is prepared in air. The electrode 430 is respectively Fig. 6A and 6B The electrodes 410 and 420 have an improved morphology compared to the electrodes 410 and 420 .

[0117] Reference Fig.6D , the electrode 440 comprises a blended electroactive material, the blended electroactive material comprising 50 wt % of NMC811 and 50 wt % of LMFP. The electrode 440 is prepared in air. The electrode 440 is respectively Fig. 6A , 6B Compared with the electrodes 410, 420, 430 of 6C, they have an improved morphology.

[0118] Adding a second electroactive material comprising an olivine-type phosphate compound to a nickel-containing electrode slurry effectively improves morphology and texture and reduces or prevents gelation. Although the morphology of the 100 wt % NMC 811 electrode 420 may be acceptable, large-scale manufacturing in an environment with strict moisture control may be challenging. Therefore, adding a second electroactive material comprising an olivine-type phosphate compound to the slurry helps to prepare a substantially uniform high nickel content positive electrode with an acceptable morphology in air without the need to control moisture in the environment.

[0119] Example 4: Effect of olivine phosphate compounds on energy density

[0120] In various aspects, the present disclosure provides a high energy density positive electrode. In certain aspects, the positive electrode comprises a blended electroactive material, the blended electroactive material comprising a first and a second electroactive material. The first electroactive material comprises NMC811 and the second electroactive material comprises LMFP. NMC 811 has a capacity delivery of 185 mAh / g, a normalized voltage of 3.8 V, and a material level energy density of 703 wh / kg. LMFP has a capacity delivery of 155 mAh / g, a normalized voltage of 4 V, and a material level energy density of 620 wh / kg.

[0121] Electrodes comprising first and / or second electroactive materials according to various aspects of the present disclosure are prepared. Figure 7 , provides a graph of positive electrode electroactive material energy density as a function of NMC 811 content according to various aspects of the present disclosure. The x-axis 510 represents the weight percentage of NMC 811, and the balance of the electroactive material is LMFP. The y-axis 512 represents the electroactive material energy density in wh / kg.

[0122] Energy density increases with increasing NMC 811 content and decreasing LMFP content. However, as shown in Example 2, pH (and gelation) also increases with increasing NMC 811 content. For electroactive materials having NMC 811 content greater than or equal to about 70 wt %, the energy density is greater than about 678 wh / kg, for electroactive materials having NMC 811 content greater than or equal to about 90 wt %, the energy density is greater than about 686 wh / kg, and for electroactive materials having NMC 811 content greater than or equal to about 80 wt %, the energy density is greater than about 694 wh / kg.

[0123] Example 5: Effect of olivine phosphate compounds on the thickness of a single-side electrode

[0124] Reference Fig. 8A , provides a graph showing the relationship between LMFP content and electrode thickness according to various aspects of the present disclosure. An electrode having a positive electroactive material is prepared, the positive electroactive material comprising NMC 811 as a first electroactive material and / or LMFP as a second electroactive material. The electrode comprises 96 wt % of the electroactive material. The electrode also comprises 2 wt % of PVDF as a polymer binder and 2 wt % of conductive carbon as a conductive material.

[0125] The x-axis 610 represents the weight percentage of LMFP. The y-axis 612 represents the weight percentage of LMFP with 3.75 mAh / cm 2 The single-side electrode thickness of the electrode with active material loading, in μm. The thickness of the electrode increases with increasing LMFP content. A LMFP content of less than or equal to about 30 wt % and 3.75 mAh / cm 2 The single-sided electrode may have a thickness of less than or equal to about 100 μm.

[0126] Figure 8B A positive electrode 630 according to various aspects of the present disclosure is depicted. Electrode 630 comprises 100 wt% NMC 811 and 0 wt% LMFP in the electroactive material. The electrode comprises 96 wt% of the electroactive material. Electrode 630 also comprises 2 wt% PVDF as a polymer binder and 2 wt% conductive carbon as a conductive material. Electrode 630 defines an average thickness 632 of 75 μm.

[0127] Figure 8C A positive electrode 640 is depicted in accordance with various aspects of the present disclosure. Electrode 640 comprises about 70 wt % NMC 811 and about 30 wt % LMFP in the electroactive material. The electrode comprises 96 wt % electroactive material. Electrode 640 also comprises 2 wt % PVDF as a polymer binder and about 2 wt % conductive carbon as a conductive material. Electrode 640 defines a thickness 642 of about 100 μm.

[0128] Example 6: Performance in an electrochemical cell

[0129] Reference Figures 9A-9B , electrochemical performance of different electrochemical cells with positive electrodes according to various aspects of the present disclosure are provided. Each electrochemical cell comprises a lithium metal negative electrode having a thickness of 30 μm and 25 μL of a fluoroethylene carbonate (FEC)-based electrolyte. Each positive electrode has a capacity of about 3.75 mAh / cm 2 The cells were cycled at a constant charge rate of 0.2C and a constant discharge rate of 0.5C.

[0130] Five electrochemical cells were prepared according to Table 1 below, each with a different positive electrode. The weight percentages in the table below refer to the weight percentages in the positive electrode electroactive material rather than the weight percentages in the positive electrode. Each electrode contained 96 wt % of electroactive material (NMC 811 or NMC 811 + LMFP), 2 wt % of PVDF as a polymer binder, and 2 wt % of amorphous carbon (C45) as a conductive material.

[0131] .

[0132] Reference Fig. 9A , depicting the capacity retention of each of the five electrochemical cells. The x-axis 710 represents the number of cycles, and the y-axis 712 represents the capacity in mAh / g. A first curve 714 represents the capacity of the first electrochemical cell. A second curve 716 represents the capacity of the second electrochemical cell. A third curve 718 represents the capacity of the third electrochemical cell. A fourth curve 720 represents the capacity of the fourth electrochemical cell. A fifth curve 722 represents the capacity of the fifth electrochemical cell.

[0133] The second electrochemical cell including a positive electrode prepared in air and having 100 wt % NMC 811 experienced significant capacity fade, as shown by the second curve 716. More specifically, after about 50 cycles, the capacity of the second electrochemical cell decreased by about 50%. In contrast, the first, third, fourth, and fifth electrochemical cells all exhibited acceptable capacity retention after 100 cycles.

[0134] Reference Fig. 9B, depicting the charge and discharge voltage lines for each of the five electrochemical cells. The x-axis 736 represents the capacity in mAh / g and the y-axis 738 represents the voltage in V. The first curve 740 represents the voltage line during the charge of the first electrochemical cell. The second curve 742 represents the voltage line during the discharge of the first electrochemical cell. The first electrochemical cell achieves a discharge capacity 743 of almost about 190 mAh / g. The third curve 744 represents the voltage line during the charge of the second electrochemical cell. The fourth curve 746 represents the voltage line during the discharge of the second electrochemical cell. The second electrochemical cell achieves a discharge capacity 747 of about 160 mAh / g, and gelation of the slurry may occur when prepared in the presence of moisture (i.e., in air). The fifth curve 748 represents the voltage line during the charge of the third electrochemical cell. The sixth curve 750 represents the voltage line during the discharge of the third electrochemical cell. The seventh curve 752 represents the voltage line during the charge of the fourth electrochemical cell. The eighth curve 754 represents the voltage line during the discharge of the fourth electrochemical cell. The ninth curve 756 represents the voltage line during the charging of the fifth electrochemical cell. The tenth curve 758 represents the voltage line during the discharge of the fifth electrochemical cell. The fifth electrochemical cell achieves a discharge capacity 759 of about 170 mAh / g. The discharge capacity 759 of the fifth electrochemical cell is higher than the discharge capacity 747 of the second electrochemical cell, which contains 100% NMC 811 active material prepared in air, indicating that the presence of LMFP reduces gelation and improves discharge capacity.

[0135] It is noteworthy that when the weight percentage of NMC 811 in the active material increases from 20 wt % to 80 wt %, the discharge capacity increases from 170 mAh / g to 190 mAh / g. However, when the electrode is prepared at

[0136] The above description of the embodiments has been provided for the purpose of illustration and description. It is not intended to be exhaustive or to limit the present disclosure. Individual elements or features of a particular embodiment are generally not limited to that particular embodiment, but are interchangeable and can be used in selected embodiments when applicable, even if not explicitly shown or described. It can also be varied in many ways. Such variations are not considered to depart from the present disclosure, and all such modifications are intended to be included within the scope of the present disclosure.

[0137] This application may include the following technical solutions.

[0138] 1. An electrode slurry for making a high nickel content positive electrode for an electrochemical cell, the electrode slurry comprising:

[0139] A blended electroactive material, the blended electroactive material comprising,

[0140] A first electroactive material containing nickel, wherein the first electroactive material is selected from LiNi wherein x is greater than 0.6 x Co y Mn z O2, LiNi where x is greater than 0.6 x Co y Al z O2, LiNi where x is greater than 0.6 x Co y Mn z Al α O2, or any combination thereof, and

[0141] a second electroactive material comprising less than or equal to about 30% by weight of an olivine-type phosphate compound of the blended electroactive material; and

[0142] A binder solution comprising a polymer binder and a solvent containing N-methyl-2-pyrrolidone.

[0143] 2. The electrode slurry according to claim 1, wherein the first electroactive material is selected from LiNi wherein x is greater than or equal to 0.8 x Co y Mn z O2, LiNi where x is greater than or equal to 0.8 x Co y Al z O2, LiNi where x is greater than or equal to 0.8 x Co y Mn z Al α O2, or any combination thereof.

[0144] 3. The electrode slurry according to claim 1, wherein the first electroactive material is selected from LiNi wherein x is greater than or equal to 0.85 x Co y Mn z O2, LiNi where x is greater than or equal to 0.85 x Co y Al z O2, LiNi where x is greater than or equal to 0.85 x Co y Mn z Al α O2, or any combination thereof.

[0145] 4. The electrode slurry according to claim 1, wherein the first electroactive material comprises NMC 811, NMCA, or both NMC 811 and NMCA.

[0146] 5. The electrode slurry according to claim 1, wherein the second electroactive material comprises Li-M 1 -M 2 -PO4, where M 1 is the first transition metal and M 2 A second transition metal different from the first transition metal.

[0147] 6. The electrode slurry according to claim 1, wherein the second electroactive material comprises LiFe x M 1-x PO4, wherein M is a transition metal and x is greater than 0 to less than 1.

[0148] 7. An electrode slurry according to Option 1, wherein the second electroactive material comprises LMFP.

[0149] 8. The electrode slurry of claim 1, wherein the blended electroactive material comprises less than or equal to about 20 wt % of the second electroactive material.

[0150] 9. The electrode slurry according to claim 1, further comprising:

[0151] Conductive material.

[0152] 10. The electrode slurry according to claim 1, wherein the polymer binder is selected from polyvinylidene fluoride, polyacrylic acid, styrene-butadiene rubber, polytetrafluoroethylene, or any combination thereof.

[0153] 11. The electrode slurry of Option 1, wherein the electrode slurry has a pH less than or equal to about 12.5.

[0154] 12. A positive electrode for an electrochemical cell, comprising

[0155] A blended electroactive material, the blended electroactive material comprising,

[0156] A first electroactive material containing nickel, wherein the first electroactive material is selected from LiNi wherein x is greater than 0.6 x Co y Mn z O2, LiNi where x is greater than 0.6 x Co y Al z O2, LiNi where x is greater than 0.6 x Co y Mn z Al α O2, or any combination thereof, and

[0157] a second electroactive material comprising less than or equal to about 30% by weight of an olivine-type phosphate compound of the blended electroactive material; and

[0158] Polymer Binders.

[0159] 13. The positive electrode of claim 12, wherein the positive electrode defines an average thickness of greater than or equal to about 75 μm to less than or equal to about 100 μm.

[0160] 14. A positive electrode according to Option 12, wherein the positive electrode is substantially free of acetic acid.

[0161] 15. The positive electrode according to claim 12, wherein the first electroactive material is selected from LiNi wherein x is greater than or equal to 0.8 x Co y Mn z O2, LiNi where x is greater than or equal to 0.8 x Co y Al z O2, LiNi where x is greater than or equal to 0.8 x Co y Mn z Al α O2, or any combination thereof.

[0162] 16. The positive electrode according to claim 12, wherein the second electroactive material comprises Li-M 1 -M 2 -PO4, where M 1 is the first transition metal and M 2 A second transition metal different from the first transition metal.

[0163] 17. The positive electrode of claim 16, wherein the first electroactive material comprises NMC 811 and the second electroactive material comprises LMFP.

[0164] 18. The positive electrode according to claim 12, further comprising:

[0165] Conductive material.

[0166] 19. The positive electrode according to claim 12, wherein the polymer binder is selected from polyvinylidene fluoride, polyacrylic acid, styrene-butadiene rubber, polytetrafluoroethylene, or any combination thereof.

[0167] 20. An electrochemical cell comprising:

[0168] A positive electrode, the positive electrode comprising,

[0169] A blended electroactive material, the blended electroactive material comprising,

[0170] A first electroactive material containing nickel, wherein the first electroactive material is selected from LiNi wherein x is greater than 0.6 x Co y Mn z O2, LiNi where x is greater than 0.6 x Co y Al z O2, LiNi where x is greater than 0.6 x Co y Mn z Al α O2, or any combination thereof, and

[0171] a second electroactive material comprising less than or equal to about 30% by weight of an olivine-type phosphate compound of the blended electroactive material; and

[0172] polymer binders;

[0173] a negative electrode comprising lithium metal; and

[0174] An electrolyte is between the positive electrode and the negative electrode.

Claims

1. An electrode slurry for making a high nickel content positive electrode for an electrochemical cell, the electrode slurry comprising: A blended electroactive material, the blended electroactive material comprising, A first electroactive material containing nickel, wherein the first electroactive material is selected from LiNi wherein x is greater than or equal to 0.8 x Co y Mn z O2, LiNi where x is greater than or equal to 0.8 x Co y Al z O2, LiNi where x is greater than or equal to 0.8 x Co y Mn z Al α O2, or any combination thereof, and The second electroactive material comprises an olivine phosphate compound of greater than 0 wt % and less than or equal to 30 wt % of the blended electroactive material, wherein the olivine phosphate compound is selected from the group consisting of LiMn 0.7 Fe 0.3 PO4、LiMn 0.6 Fe 0.4 PO4、LiMn 0.8 Fe 0.2 PO4 and LiMn 0.75 Fe 0.25 PO4 group; and A binder solution comprising a polymer binder and a solvent containing N-methyl-2-pyrrolidone.

2. The electrode slurry according to claim 1, wherein the first electroactive material is selected from LiNi wherein x is greater than or equal to 0.85 x Co y Mn z O2, LiNi where x is greater than or equal to 0.85 x Co y Al z O2, LiNi where x is greater than or equal to 0.85 x Co y Mn z Al α O2, or any combination thereof. 3 . The electrode slurry of claim 1 , wherein the first electroactive material comprises NMC 811, NMCA, or both NMC 811 and NMCA.

4. The electrode slurry of claim 1, wherein the blended electroactive material comprises less than or equal to 20 wt% of the second electroactive material.

5. The electrode slurry according to claim 1, further comprising: Conductive material. 6 . The electrode slurry according to claim 1 , wherein the polymer binder is selected from polyvinylidene fluoride, polyacrylic acid, styrene-butadiene rubber, polytetrafluoroethylene, or any combination thereof.

7. The electrode slurry of claim 1, wherein the electrode slurry has a pH less than or equal to 12.

5.

8. A positive electrode for an electrochemical cell, comprising A blended electroactive material, the blended electroactive material comprising, A first electroactive material containing nickel, wherein the first electroactive material is selected from LiNi wherein x is greater than or equal to 0.8 x Co y Mn z O2, LiNi where x is greater than or equal to 0.8 x Co y Al z O2, LiNi where x is greater than or equal to 0.8 x Co y Mn z Al α O2, or any combination thereof, and The second electroactive material comprises an olivine phosphate compound of greater than 0 wt % and less than or equal to 30 wt % of the blended electroactive material, wherein the olivine phosphate compound is selected from the group consisting of LiMn 0.7 Fe 0.3 PO4、LiMn 0.6 Fe 0.4 PO4、LiMn 0.8 Fe 0.2 PO4 and LiMn 0.75 Fe 0.25 PO4 group; and Polymer Binder. 9 . The positive electrode of claim 8 , wherein the positive electrode defines an average thickness of greater than or equal to 75 μm to less than or equal to 100 μm.

10. The positive electrode of claim 8, wherein the positive electrode is substantially free of acetic acid.

11. The positive electrode according to claim 8, further comprising: Conductive material. 12 . The positive electrode according to claim 8 , wherein the polymer binder is selected from polyvinylidene fluoride, polyacrylic acid, styrene-butadiene rubber, polytetrafluoroethylene, or any combination thereof.

13. An electrochemical cell comprising: A positive electrode, the positive electrode comprising, A blended electroactive material, the blended electroactive material comprising, A first electroactive material containing nickel, wherein the first electroactive material is selected from LiNi wherein x is greater than or equal to 0.8 x Co y Mn z O2, LiNi where x is greater than or equal to 0.8 x Co y Al z O2, LiNi where x is greater than or equal to 0.8 x Co y Mn z Al α O2, or any combination thereof, and The second electroactive material comprises an olivine phosphate compound of greater than 0 wt % and less than or equal to 30 wt % of the blended electroactive material, wherein the olivine phosphate compound is selected from the group consisting of LiMn 0.7 Fe 0.3 PO4、LiMn 0.6 Fe 0.4 PO4、LiMn 0.8 Fe 0.2 PO4 and LiMn 0.75 Fe 0.25 PO4 group; and polymer binders; a negative electrode comprising lithium metal; and An electrolyte is between the positive electrode and the negative electrode.

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