LITHIUM AND MANGANESE RICH POSITIVE ACTIVE MATERIAL COMPOSITIONS

A positive electrode active material includes a compound represented by formula 1:  Li(1.333-0.667x-y)Mn(0.667-0.333x)NixMyO2 or Li(4/3-2/3x-y)Mn(2/3-1/3x)NixMyO2  (1) wherein,          M is Co, Cr, or a combination thereof,     0.13<x<0.5; and     0<y<0.333.

TECHNICAL FIELD

In at least one aspect, positive electrode active materials for lithium-ion batteries are provided.

BACKGROUND

Lithium and Manganese Rich (LMR) positive electrode active material has been considered one of the most promising next-generation cathode materials due to the highest gravimetric energy density (Mn-rich and low Ni and low Co) compared to currently used NCMs and NCAs. However, intrinsic issues of LMR such as voltage decay during cycling, rate capability, cycle performance, and volumetric energy density have prevented successful commercialization.

Accordingly, there is a need for positive electrode active materials for lithium-ion batteries with increased rate capability, cell performance, and volumetric energy density.

SUMMARY

In at least one aspect, a positive electrode active material is provided. The positive electrode active material includes a compound represented by formula 1:

In another aspect, a positive electrode for a lithium-ion battery is provided. The positive electrode includes a positive electrode active material that includes a compound represented by Chemical Formula 1:

In another aspect, a rechargeable lithium-ion battery including at least one lithium-ion battery cell is provided. Each lithium-ion battering cell includes a positive electrode comprising a compound represented by formula 1:

wherein:M is Co, Cr, or a combination thereof,0.13<x<0.5; and0<y<0.333.
a negative electrode including a negative electrode active material, and an electrolyte.

Advantageously, the positive electrode active material is composed of an LMR composition with a lower average Mn oxidation state (i.e., a higher amount of Mn+3ions in the composition) than prior art positive electrode active materials. Moreover, this new LMR composition also can have lower Li content. Higher Mn+3and lower Li+compositions can mitigate critical issues of LMR such as severe voltage decay during cycling, poor rate capability, poor cycle performance, and/or lower volumetric energy density. This new composition also can have higher Mn and lower Li contents compared to previous LMR compositions (e.g, US 2017/0141393 A; the entire disclosure of which is hereby incorporated by reference).

In another aspect, the positive electrode materials provided herein minimized energy density decreases while mitigating other intrinsic issues such as voltage decay during cycling, poor rate compatibility, and poor cycle performance.

DETAILED DESCRIPTION

Except in the examples, or where otherwise expressly indicated, all numerical quantities in this description indicating amounts of material or conditions of reaction and/or use are to be understood as modified by the word “about” in describing the broadest scope of the invention. Practice within the numerical limits stated is generally preferred. Also, unless expressly stated to the contrary: when a given chemical structure includes a substituent on a chemical moiety (e.g., on an aryl, alkyl, etc.) that substituent is imputed to a more general chemical structure encompassing the given structure; percent, “parts of,” and ratio values are by weight; the term “polymer” includes “oligomer,” “copolymer,” “terpolymer,” and the like; molecular weights provided for any polymers refers to weight average molecular weight unless otherwise indicated; the description of a group or class of materials as suitable or preferred for a given purpose in connection with the invention implies that mixtures of any two or more of the members of the group or class are equally suitable or preferred; description of constituents in chemical terms refers to the constituents at the time of addition to any combination specified in the description, and does not necessarily preclude chemical interactions among the constituents of a mixture once mixed; the first definition of an acronym or other abbreviation applies to all subsequent uses herein of the same abbreviation and applies mutatis mutandis to normal grammatical variations of the initially defined abbreviation; and, unless expressly stated to the contrary, measurement of a property is determined by the same technique as previously or later referenced for the same property.

As used herein, the term “about” means that the amount or value in question may be the specific value designated or some other value in its neighborhood. Generally, the term “about” denoting a certain value is intended to denote a range within +/−5% of the value. As one example, the phrase “about 100” denotes a range of 100+/−5, i.e. the range from 95 to 105. Generally, when the term “about” is used, it can be expected that similar results or effects according to the invention can be obtained within a range of +/−5% of the indicated value.

As used herein, the term “and/or” means that either all or only one of the elements of said group may be present. For example, “A and/or B” shall mean “only A, or only B, or both A and B”. In the case of “only A”, the term also covers the possibility that B is absent, i.e. “only A, but not B”.

The phrase “composed of” means “including” or “consisting of.” Typically, this phrase is used to denote that an object is formed from a material.

The term “one or more” means “at least one” and the term “at least one” means “one or more.” The terms “one or more” and “at least one” include “plurality” and “multiple” as a subset. In a refinement, “one or more” includes “two or more.”

The term “substantially,” “generally,” or “about” may be used herein to describe disclosed or claimed embodiments. The term “substantially” may modify a value or relative characteristic disclosed or claimed in the present disclosure. In such instances, “substantially” may signify that the value or relative characteristic it modifies is within ±0%, 0.1%, 0.5%, 1%, 2%, 3%, 4%, 5% or 10% of the value or relative characteristic.

When referring to a numeral quantity, in a refinement, the term “less than” includes a lower non-included limit that is 5 percent of the number indicated after “less than.” For example, “less than 20” includes a lower non-included limit of 1 in a refinement. Therefore, this refinement of “less than 20” includes a range between 1 and 20. In another refinement, the term “less than” includes a lower non-included limit that is, in increasing order of preference, 20 percent, 10 percent, 5 percent, or 1 percent of the number indicated after “less than.”

The term “positive electrode” means a battery cell electrode from which current flows out when the lithium-ion battery cell or battery is discharged. Sometimes a “positive electrode” is referred to as a “cathode.”

The term “negative electrode” means a battery cell electrode to which current flows in when the lithium-ion battery cell is discharged. Sometimes a “negative electrode” is referred to as an “anode.”

The term “cell” or “battery cell” means an electrochemical cell made of at least one positive electrode, at least one negative electrode, an electrolyte, and a separator membrane.

The term “battery” or “battery pack” means an electric storage device made of at least one battery cell. In a refinement, “battery” or “battery pack” is an electric storage device made of a plurality of battery cells.

The term “specific capacity” means the capacity per unit mass of the anode active. Specific capacity has units of milliamp hours/gram (mAh/g).

Abbreviations

“BEV” means battery electric vehicle.“LMR” means lithium and manganese-rich.“mAh” means milliamp-hour.“mAh/g” means milliamp-hour per gram.

Referring toFIG.1, a schematic of a positive electrode that includes a positive electrode active material is provided. Positive electrode10includes positive electrode active material layer12of positive electrode active material disposed over and typically contacting positive electrode current collector14. Typically, positive electrode current collector14is a metal plate or metal foil composed of a metal such as aluminum, copper, platinum, zinc, titanium, and the like. Currently, copper is most commonly used for the positive electrode current collector. The positive electrode active material is represented by formula 1:

wherein:M is Co, Cr, or a combination thereof,0.13<x<0.5; and0<y<0.333.
In a refinment, 0.13<x<0.5 and 0<y<0.13. In another refinement, 0.25<x<0.35 and 0.04<y<0.09. In another refinement, 0.2<x<0.5 and 0<y<0.333. In still another refinement, 1<(1.333-0.667x-y) or (4/3-2/3x-y)<1.19 and 0.5<0.667-0.333x or (2/3-1/3x)<0.667. In some refinements, x is greater than, in increasing order of preference 0.2, 0.21, 0.22, 0.23, 0.24, or 0.25. and less than in increasing order of preference, 0.5, 0.45, 0.4, 0.38, 0.36, 0.34, 0.32, 0.30, or 0.28. In further refinements, y is greater than in increasing order of preference, 0.0, 0.01, 0.02, 0.04, 0.08, 0.1, 0.12, or 0.15. and less than 0.35, 0.333, 0.3, 0.25, 0.20, 0.18, 0.15, 0.1, 0.09, or 0.08. Specific positive electrode active materials are Li1.12Mn0.59Ni0.23M0.6O2and Li1.10Mn0.59Ni0.23M0.8O2.

In a variation, the Mn comprises Mn having an oxidation number of +3 and Mn having an oxidation number of +4. In a variation, the content of the Mn having an oxidation number of +3 is greater than about 3.5 wt % and less than about 45 weight %. In a refinement, the content of Mn having an oxidation number of +3 is greater than about 3.5 wt % and less than about 30 weight %.

With reference toFIG.2, a schematic of a rechargeable lithium-ion battery cell incorporating the positive electrode ofFIG.1is provided. Battery cell20includes positive electrode10as described above, negative electrode22, and separator24interposed between the positive electrode and the negative electrode. Negative electrode22includes an negative electrode current collector26and a negative active material layer28disposed over and typically contacting the negative current collector. Typically, negative electrode current collector26is a metal plate or metal foil composed of a metal such as aluminum, copper, platinum, zinc, titanium, and the like. Currently, copper is most commonly used for the negative electrode current collector. The battery cell is immersed in electrolyte30which is enclosed by battery cell case32. Electrolyte30imbibes into separator24. In other words, the separator24includes the electrolyte thereby allowing lithium ions to move between the negative and positive electrodes. The electrolyte includes a non-aqueous organic solvent and a lithium salt. The non-aqueous organic solvent serves as a medium for transmitting ions taking part in the electrochemical reaction of a battery. Advantageously, battery cell20can have a specific capacity of greater than 150 mAh/g.

With reference toFIG.3, a schematic of a rechargeable lithium-ion battery incorporating the positive electrode ofFIG.1and the battery cells ofFIG.2is provided. Rechargeable lithium-ion battery40includes at least one battery cell of the design inFIG.2. Typically, comprising rechargeable lithium-ion battery40includes at least one battery cell20iof the design ofFIG.2. Each lithium-ion battery cell20iincludes a positive electrode10which includes the compound represented by formula 1, a negative electrode22which includes a negative active material, and an electrolyte30, where i is an integer label for each battery cell. The label i runs from 1 to nmax, where nmax is the total number of battery cells in rechargeable lithium-ion battery40. The electrolyte30includes a non-aqueous organic solvent and a lithium salt. The non-aqueous organic solvent serves as a medium for transmitting ions taking part in the electrochemical reaction of a battery. The plurality of battery cells can be wired in series, in parallel, or a combination thereof. The voltage output from battery40is provided across terminals42and44. Advantageously, rechargeable lithium-ion battery40can have a specific capacity of greater than 150 mAh/g for each battery cell therein.

Referring toFIGS.2and3, separator24physically separates the negative electrode22from the positive electrode10thereby presenting shorting while allowing the transport of lithium ions for charging and discharging. Therefore, separator24can be composed of any material suitable for this purpose. Examples of suitable materials from which separator24can be composed include but are not limited to, polytetrafluoroethylene (e.g., TEFLON®), glass fiber, polyester, polyethylene, polypropylene, and combinations thereof. Separator24can be in the form of either a woven or non-woven fabric. Separator24can be in the form of a non-woven fabric or a woven fabric. For example, a polyolefin-based polymer separator such as polyethylene and/or polypropylene is typically used for a lithium-ion battery. In order to ensure heat resistance or mechanical strength, a coated separator includes a coating of ceramic or a polymer material may be used.

Referring toFIGS.2and3, electrolyte30includes a lithium salt dissolved in the non-aqueous organic solvent. Therefore, electrolyte30includes lithium ions that can intercalate into the positive electrode active material during charging and into the anode active material during discharging. Examples of lithium salts include but are not limited to LiPF6, LiBF4, LiSbF6, LiAsF6, LiC4F9SO3, LiClO4, LiAlO2, LiAlCl4, LiCl, LiI, LiB(C2O4)2, and combinations thereof. In a refinement, the electrolyte includes the lithium salt in an amount from about 0.1 M to about 2.0 M.

Still referring toFIGS.2and3, the electrolyte includes a non-aqueous organic solvent and a lithium salt. Advantageously, the non-aqueous organic solvent serves as a medium for transmitting ions, and in particular, lithium ions participate in the electrochemical reaction of a battery. Suitable non-aqueous organic solvents include carbonate-based solvents, ester-based solvents, ether-based solvents, ketone-based solvents, alcohol-based solvents, aprotic solvents, and combinations thereof. Examples of carbonate-based solvents include but are not limited to dimethyl carbonate, diethyl carbonate, dipropyl carbonate, methylpropyl carbonate, ethylpropyl carbonate, methylethyl carbonate, ethylene carbonate, propylene carbonate, butylene carbonate, and combinations thereof. Examples of ester-based solvents include but are not limited to methyl acetate, ethyl acetate, n-propyl acetate, methylpropionate, ethylpropionate, γ-butyrolactone, decanolide, valerolactone, mevalonolactone, caprolactone, and combinations thereof. Examples of ether-based solvents include but are not limited to dibutyl ether, tetraglyme, diglyme, dimethoxyethane, 2-methyltetrahydrofuran, tetrahydrofuran, and the like, and the ketone-based solvent may include cyclohexanone, and the like. Examples of alcohol-based solvent include but are not limited to methanol, ethyl alcohol, n-propyl alcohol, isopropyl alcohol, and the like. Examples of the aprotic solvent include but are not limited to nitriles such as R—CN (where R is a C2-20linear, branched, or cyclic hydrocarbon that may include a double bond, an aromatic ring, or an ether bond), amides such as dimethylformamide, dioxolanes such as 1,3-dioxolane, sulfolanes, and the like. Advantageously, the non-aqueous organic solvent can be used singularly. In other variations, mixtures of the non-aqueous organic solvent can be used. Such mixtures are typically formulated to optimize battery performance. In a refinement, a carbonate-based solvent is prepared by mixing a cyclic carbonate and a linear carbonate. In a variation, electrolyte30can further include vinylene carbonate or an ethylene carbonate-based compound to increase e battery cycle life.

Referring toFIGS.1,2, and3, the negative electrode and the positive electrode can be fabricated by methods known to those skilled in the art of lithium-ion batteries. Typically, an active material (e.g., the positive o negative active material) is mixed with a conductive material, and a binder in a solvent (e.g., N-methylpyrrolidone) into an active material composition and coating the composition on a current collector. The electrode manufacturing method is well known and thus is not described in detail in the present specification. The solvent includes N-methylpyrrolidone and the like but is not limited thereto.

Referring toFIGS.1,2, and3, the positive electrode active material layer12includes the positive electrode active material represented by formula 1, a binder, and a conductive material. The binder can increase the binding properties of positive electrode active material particles with one another and with the positive electrode current collector14. Examples of suitable binders include but are not limited to polyvinyl alcohol, carboxylmethyl cellulose, hydroxypropyl cellulose, diacetyl cellulose, polyvinylchloride, carboxylated polyvinylchloride, polyvinylfluoride, an ethylene oxide-containing polymer, polyvinylpyrrolidone, polyurethane, polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, polypropylene, a styrene-butadiene rubber, an acrylate styrene-butadiene rubber, an epoxy resin, nylon, and the like, and combinations thereof. The conductive material provides positive electrode10with electrical conductivity. Examples of suitable electrically conductive materials include but are not limited to natural graphite, artificial graphite, carbon black, acetylene black, ketjen black, carbon fibers, copper, metal powders, metal fibers, and combinations thereof. Examples of metal powders and metal fibers are composed of including nickel, aluminum, silver, and the like.

Referring toFIGS.1,2, and3, the negative active material layer26includes a negative active material, includes a binder, and optionally a conductive material. The negative active materials used herein can be those negative materials known to one skilled in the art of lithium-ion batteries. Negative active materials include but are not limited to, carbon-based negative active materials, silicon-based negative active materials, and combinations thereof. A suitable carbon-based negative active material may include graphite and graphene. A suitable silicon-based negative active material may include at least one selected from silicon, silicon oxide, silicon oxide coated with conductive carbon on the surface, and silicon (Si) coated with conductive carbon on the surface. For example, silicon oxide can be described by the formula SiOzwhere z is from 0.09 to 1.1. Mixtures of carbon-based negative active materials, silicon-based negative active materials can also be used for the negative active material.

The negative electrode binder increases the binding properties of negative active material particles with one another and with a current collector. The binder can be a non-aqueous binder, an aqueous binder, or a combination thereof. Examples of non-aqueous binder may be polyvinylchloride, carboxylated polyvinylchloride, polyvinylfluoride, an ethylene oxide-containing polymer, polyvinylpyrrolidone, polyurethane, polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, polypropylene, polyamideimide, polyimide, or a combination thereof. Aqueous binders can be rubber-based binders or polymer resin binders. Examples of rubber-based binders include but are not limited to styrene-butadiene rubbers, acrylated styrene-butadiene rubbers, acrylonitrile-butadiene rubbers, acrylic rubbers, butyl rubbers, fluorine rubbers, and combinations thereof. Examples of polymer resin binders include but are not limited to polyethylene, polypropylene, ethylenepropylene copolymer, polyethyleneoxide, polyvinylpyrrolidone, epichlorohydrin, polyphosphazene, polyacrylonitrile, polystyrene, ethylenepropylenediene copolymer, polyvinylpyridine, chlorosulfonated polyethylene, latex, a polyester resin, an acrylic resin, a phenolic resin, an epoxy resin, polyvinyl alcohol and combinations thereof.