阅读说明：本技术 用于高电压锂离子电池的含磷聚酯电解质 (Phosphorus-containing polyester electrolyte for high voltage lithium ion batteries ) 是由 马拉·阿扎伽萨米 库兰戴维路·斯瓦南丹 哈尼·巴萨姆·埃陶尼 乔纳森·P·梅里奥 乔治·山姆 于 2020-02-12 设计创作，主要内容包括：本发明公开了用于高电压锂离子电池的含磷聚酯电解质。已经合成了新的含磷聚酯。当这些聚合物与电解质盐组合时,这种聚合物电解质在锂电池单元中显示出优异的电化学氧化稳定性。它们的稳定性以及出色的离子传输性能使其特别适合用作高能量密度锂电池单元中的电解质。(The invention discloses a phosphorus-containing polyester electrolyte for a high-voltage lithium ion battery. New phosphorus-containing polyesters have been synthesized. When these polymers are combined with an electrolyte salt, the polymer electrolyte shows excellent electrochemical oxidation stability in a lithium battery cell. Their stability and excellent ion transport properties make them particularly suitable for use as electrolytes in high energy density lithium battery cells.)

1. A polymer, comprising:

the polymer structure, described below:

wherein: y is selected from the group consisting of Z-substituted oxo-phosphorus and Z-substituted phosphorus;

a and n are integers, wherein a ranges from 2 to 10, and n ranges from 1 to 1000;

z is selected from the group consisting of:

wherein b is an integer ranging from 1 to 10;

R₁selected from the group consisting of hydrogen, methyl, ethyl, propyl, and isopropyl;

r is selected from the group consisting of:

wherein c, d and e are integers independently ranging from 0 to 10; and is

X is selected from the group consisting of hydrogen, fluoro, methyl, ethyl, isopropyl, and trifluoromethyl.

2. The polymer of claim 1, further comprising an electrolyte salt, wherein the polymer is an electrolyte.

3. The polymer of claim 2, further comprising ceramic electrolyte particles.

4. The polymer of claim 1, wherein the polymer is crosslinked.

5. The polymer of claim 4, further comprising an electrolyte salt, wherein the polymer is an electrolyte.

6. A positive electrode, comprising:

a positive electrode active material; and

a catholyte comprising the electrolyte of claim 2;

wherein the positive electrode active material particles and the catholyte are mixed together.

7. The cathode of claim 6, wherein the catholyte further comprises a solid polymer electrolyte.

8. The positive electrode of claim 6, wherein the catholyte further comprises ceramic electrolyte particles.

9. The cathode of claim 6, wherein the catholyte is crosslinked.

10. The positive electrode of claim 6, wherein the positive electrode active material is selected from the group consisting of lithium iron phosphate, lithium-metal-phosphates, vanadium pentoxide, lithium nickel cobalt aluminum oxide, lithium nickel cobalt manganese oxide, magnesium rich lithium nickel cobalt manganese oxide, lithium manganese spinel, lithium nickel manganese spinel, and combinations thereof.

11. The positive electrode according to claim 6, wherein the electrolyte salt is a lithium salt.

12. An electrochemical cell comprising:

an anode configured to absorb and release lithium ions;

a cathode comprising cathode active material particles, an electron conductive additive, and a first catholyte;

a current collector adjacent to an outer surface of the cathode; and

a separator region between the anode and the cathode, the separator region comprising a separator electrolyte configured to facilitate lithium ion movement back and forth between the anode and the cathode;

wherein the first catholyte comprises the electrolyte of claim 2, and the electrolyte salt is a lithium salt.

13. The electrochemical cell of claim 12, wherein the first catholyte further comprises a solid polymer electrolyte.

14. The electrochemical cell of claim 12, wherein the first catholyte and the separator electrolyte are the same.

15. The electrochemical cell of claim 12, wherein the separator electrolyte comprises a solid polymer electrolyte.

16. The electrochemical cell of claim 12, further comprising a cover layer between the cathode and the separator region, the cover layer comprising a second catholyte comprising the electrolyte of claim 2.

17. The electrochemical cell of claim 16, wherein the first catholyte and the second catholyte are the same.

18. The electrochemical cell of claim 12, wherein the anode comprises a material selected from the group consisting of lithium metal, lithium alloys, lithium titanate, graphite, and silicon.

19. The electrochemical cell of claim 12, wherein the first catholyte further comprises ceramic electrolyte particles.

20. The electrochemical cell of claim 12, wherein the first catholyte is crosslinked.

Technical Field

The present invention relates generally to electrolytes for lithium batteries, and more particularly to electrolytes particularly suitable for use in cathodes and at high voltages.

Background

More and more lithium battery manufacturers are using next generation cathode materials, such as NCA (lithium nickel cobalt aluminum oxide), NCM (lithium nickel cobalt manganese oxide) and high energy NCM (HE-NCM-magnesium rich lithium nickel cobalt manganese oxide) to exploit their potential high gravimetric energy density (up to 300-. Cells made with such oxidic cathode materials typically operate at higher voltages (e.g., up to 4.7V) than do cells of olivine cathode materials (e.g., LFP, lithium iron phosphate) (e.g., 3.6-3.8V). Electrolytes that are stable at the lower voltages of LFP cells can be difficult to operate at higher voltages, especially in the cathode. Oxidative forms of degradation may lead to capacity fade early in the life of the cell.

Therefore, there is a need to develop electrolytes that are particularly suitable for operating under the high voltage conditions of the next generation of cathode materials.

Disclosure of Invention

In one embodiment of the present invention, a novel polymer is disclosed. The polymer includes a phosphorus-containing polyester structure represented by:

wherein Y is selected from the group consisting of Z-substituted oxo-phosphorus (Z-substitated oxy-phosphorus) and Z-substituted phosphorus (Z-substitated phosphorus);

a and n are integers, wherein a ranges from 2 to 10, and n ranges from 1 to 1000;

z is selected from the group consisting of:

wherein b is a rangeAn integer of (d);

R₁selected from the group consisting of hydrogen, methyl, ethyl, propyl, and isopropyl;

r is selected from the group consisting of:

wherein c, d and e are integers independently ranging from 0 to 10; and is

X is selected from the group consisting of hydrogen, fluoro, methyl, ethyl, isopropyl, and trifluoromethyl.

In some embodiments of the invention, any of the polymers described herein are combined with an electrolyte salt and can be used as a polymer electrolyte.

In some embodiments of the invention, any of the polymer electrolytes described herein further comprise ceramic electrolyte particles.

In some arrangements, any of the polymers described herein are crosslinked. In some arrangements, any of the polymers described herein are crosslinked and combined with an electrolyte salt to function as a polymer electrolyte.

In one embodiment of the present invention, the positive electrode includes a positive electrode active material; and the catholyte comprises any of the electrolytes described herein. The positive electrode active material particles and the catholyte will be mixed together. The catholyte may also include a solid polymer electrolyte. The catholyte may also comprise ceramic electrolyte particles. The catholyte may be crosslinked. The catholyte may comprise an electrolyte salt that is a lithium salt.

The positive active material may be any one of lithium iron phosphate, lithium-metal-phosphate, vanadium pentoxide, lithium nickel cobalt aluminum oxide, lithium nickel cobalt manganese oxide, magnesium rich lithium nickel cobalt manganese oxide, lithium manganese spinel, lithium nickel manganese spinel, and combinations thereof.

In another embodiment of the present invention, an electrochemical cell includes an anode configured to absorb and release lithium ions; a cathode comprising cathode active material particles, an electron conductive additive, and a first catholyte; a current collector adjacent to an outer surface of the cathode; a separator region positioned between the anode and the cathode, the separator region comprising a separator electrolyte configured to facilitate movement of lithium ions back and forth between the anode and the cathode. The first catholyte can include any of the electrolytes described herein. The first catholyte may also include ceramic electrolyte particles. The first catholyte may be crosslinked. The electrolyte salt may be a lithium salt.

The first catholyte and/or separator electrolyte may also comprise a solid polymer electrolyte. In one arrangement, the first catholyte and the separator electrolyte are the same.

In one arrangement, there is a cover layer between the cathode and the separator region. The cover layer includes a second catholyte, which may be any of the electrolytes disclosed herein. The first catholyte and the second catholyte may be the same or may be different.

The anode may comprise any one of lithium metal, lithium alloy, lithium titanate, graphite, and silicon.

Drawings

The foregoing aspects and others will become apparent to those skilled in the art from the following description of the illustrative embodiments, when read in light of the accompanying drawings.

Fig. 1 is a schematic diagram of one configuration of a lithium battery cell including an electrolyte used in a cathode and a separator according to an embodiment of the present invention.

Fig. 2 is a schematic diagram of another configuration of a lithium battery cell including a catholyte and a separator electrolyte different from the catholyte in accordance with an embodiment of the invention.

Fig. 3 is a schematic view of another configuration of a lithium battery cell including a catholyte and a cathode capping layer according to an embodiment of the present invention.

Detailed Description

Embodiments of the present invention are illustrated in the context of phosphorus-containing polyesters, which may be used as electrolytes or electrolyte additives in lithium battery cells and the like. However, one skilled in the art will readily appreciate that the materials and methods disclosed herein will have application in many other situations where high voltage electrolytes are required, particularly where long term stability is important.

These and other objects and advantages of the present invention will become more apparent from the following description taken in conjunction with the accompanying drawings.

All publications mentioned herein are incorporated herein by reference in their entirety for all purposes as if fully set forth herein.

In the present disclosure, the terms "negative electrode" and "anode" are both used to describe a negative electrode. Likewise, the terms "positive electrode" and "cathode" are both used to describe a positive electrode.

It should be understood that the term "lithium metal" or "lithium foil" as used herein for the negative electrode is intended to include pure lithium metal and lithium-rich metal alloys known in the art. Examples of lithium-rich metal alloys suitable for use as the anode include Li-Al, Li-Si, Li-Sn, Li-Hg, Li-Zn, Li-Pb, Li-C, or any other lithium metal alloy suitable for use in a lithium metal battery. Other negative electrode materials that may be used in embodiments of the invention include materials into which lithium may be intercalated, such as graphite, and other materials that may absorb and release lithium ions, such as silicon, germanium, tin, and alloys thereof. Many of the embodiments described herein are directed to batteries having a solid polymer electrolyte that functions as both an electrolyte and a separator. As is well known in the art, batteries with liquid electrolytes use a different inactive separator material than the liquid electrolyte.

The following sentence pattern is used throughout this disclosure: each variable is independently selected from the list provided. Examples of such usage can be found with reference to the X groups/groups in certain polymer structures of the present invention in which there are many X's. For example, "each X may be independently selected from hydrogen, fluoro, methyl, ethyl, isopropyl, and trifluoromethyl. "this pattern is used to indicate that any group in the list can be used for a particular X in the structure. In selecting a group to be used for another X in the structure, any of the groups in the list can be used without regard to the selection made for the other X groups. Thus, the following arrangements are possible: all xs may be the same, all xs may be different, or some xs may be the same and some xs may be different.

The molecular weights given herein are number average molecular weights.

The term "solid polymer electrolyte" is used herein to refer to a polymer electrolyte that is solid at the cell operating temperature. Examples of useful cell operating temperatures include room temperature (25 ℃), 40 ℃, and 80 ℃.

In this disclosure, a range of values is given for a number of variables. It should be understood that the possible values of the various variables also include any range within the given range.

Based on repeated observation of Li in Molecular Dynamics (MD) simulations⁺Interaction with other atoms, it appears that Li⁺Coordinated to a portion of the negatively charged atoms in the polymer electrolyte. For example, in polyethylene oxide (PEO), Li⁺Coordinated to a portion of the negatively charged oxygen atoms in the PEO. Similarly, in the phosphorus-containing polyesters, Li⁺Oxygen coordinated to a portion of the phosphorus-containing ester groups that is negatively charged.

Phosphorus-containing polyester:

in some embodiments of the present invention, the phosphorus-containing polyester has the general structure:

wherein Y may be Z and the structure is poly (phosphate), or Y may be OZ and the structure is poly (phosphonate). The poly (phosphate) and poly (phosphonate) have functional side chains Z, which may be directly linked as shown or linked by an extendable alkyl chain (not shown). a and n are integers. The value of a ranges from 2 to 10. The value of n is in the range of 1 to 1000. Each R and Z is independently selected from the following list.

In Z, b is an integer ranging from 1 to 10; r₁Can be hydrogen, methyl, ethyl, propyl or isopropyl. In R, c, d and e are integers independently ranging from 0 to 10; x may be hydrogen, fluoro, methyl, ethyl, isopropyl or trifluoromethyl.

In another embodiment of the present invention, particles of a ceramic electrolyte are mixed into a phosphorus-containing polyester electrolyte to form an enhanced composite electrolyte with excellent ion transport and mechanical properties. Such composite electrolytes can be used in lithium battery cells in the separator region or in the cathode. Examples of ceramic electrolytes that can be used in admixture with the phosphorus-containing polyester electrolyte include, but are not limited to, those shown in table 1 below.

TABLE 1

Exemplary ceramic conductors for use as additives in phosphorus-containing polyester electrolytes

Means that the components are mixed together

Table 2 below shows simulated lithium ion transport properties of various phosphorus-containing polyester materials. These polymers exhibit desirable lithium ion transport properties.

TABLE 2

Comparing lithium transport properties of PEO, PPM, and poly (phosphate) electrolyte materials

Cell design including phosphorus-containing polyester electrolyte

In one embodiment of the present invention, as shown in fig. 1, a lithium battery cell 200 has an anode 220 configured to absorb and release lithium ions. Anode 220 may be a lithium foil or a lithium alloy foil, or may be made of a material that absorbs lithium ions, such as graphite or silicon. Other options for anode 220 include, but are not limited to, lithium titanate and lithium silicon alloys. Lithium battery cell 200 also includes a cathode 240, which cathode 240 includes cathode active material particles 242, an electron conducting additive (not shown) such as carbon black, a current collector 244, a catholyte (electrolyte in the cathode) 246, and an optional binder (not shown). In one arrangement, the catholyte 246 comprises any of the phosphorus-containing polyester electrolytes disclosed above. In another arrangement, catholyte 246 comprises a mixture or combination of other solid polymer electrolytes with a phosphorus-containing polyester electrolyte. A separator region 260 is present between the anode 220 and the cathode 240. Catholyte 246 extends all the way into separator region 260 and facilitates lithium ion movement back and forth between anode 220 and cathode 240 as unit cell 200 cycles. The electrolyte 246 in the separator region 260 is the same as the catholyte 246 in the cathode 240.

In another embodiment of the present invention, as shown in fig. 2, the lithium battery cell 300 has an anode 320 configured to absorb and release lithium ions. Anode 320 may be a lithium or lithium alloy foil or may be made of a material that absorbs lithium ions, such as graphite or silicon. Other options for anode 320 include, but are not limited to, lithium titanate and lithium silicon alloys. The lithium battery cell 300 also includes a cathode 340, the cathode 340 including cathode active material particles 342, an electron conductive additive (not shown) such as carbon black, a current collector 344, a cathode electrolyte 346, and an optional binder (not shown). In one arrangement, catholyte 346 includes any of the phosphorus-containing polyester electrolytes disclosed above. In another arrangement, catholyte 346 comprises a mixture or combination of other solid polymer electrolytes with a phosphorus-containing polyester electrolyte. A separator electrolyte 360 is present between the anode 320 and the cathode 340. The separator electrolyte 360 facilitates lithium ions to move back and forth between the anode 320 and the cathode 340 as the unit cell 300 is cycled. The separator electrolyte 360 may comprise any electrolyte suitable for use in a lithium battery cell. In one arrangement, the separator electrolyte 360 comprises a liquid electrolyte that is immersed in a porous plastic material (not shown). In another arrangement, the separator electrolyte 360 comprises a viscous liquid electrolyte or a gel electrolyte. In another arrangement, the separator region 360 contains a solid polymer electrolyte in which the phosphorus-containing polyester is immiscible.

In another embodiment of the present invention, a battery cell having a third configuration is described. Referring to fig. 3, the lithium battery cell 400 has an anode 420 configured to absorb and release lithium ions. Anode 420 may be a lithium or lithium alloy foil, or may be made of a material that absorbs lithium ions, such as graphite or silicon. Other options for anode 420 include, but are not limited to, lithium titanate and lithium silicon alloys. Lithium battery cell 400 also includes cathode 450, cathode 450 including cathode active material particles 452, an electronically conductive additive (not shown), current collector 454, catholyte 456, an optional binder (not shown), and capping layer 458. In one arrangement, the electrolyte in the cover layer 458 and the catholyte 456 are the same. In another arrangement, the electrolyte in the cover layer 458 and the catholyte 456 are different. Cover layer 458 and/or catholyte 456 may comprise a mixture or combination of any of the phosphorus-containing polyester electrolytes or other solid polymer electrolytes disclosed herein with a phosphorus-containing polyester electrolyte or electrolyte additive (in a solid polymer electrolyte matrix). In one arrangement, capping layer 458 is a solid electrolyte layer. A separator region 460 is present between the anode 420 and the cathode 450. The separator region 460 contains an electrolyte that facilitates the movement of lithium ions back and forth between the anode 420 and the cathode 450 as the unit cell 400 is cycled. The separator region may comprise any electrolyte suitable for use in a lithium battery cell. In one arrangement, the separator electrolyte 460 comprises a liquid electrolyte that is immersed in a porous plastic material (not shown). In another arrangement, separator electrolyte 460 comprises a viscous liquid electrolyte or a gel electrolyte. In another arrangement, the separator region 460 contains a solid polymer electrolyte in which the phosphorus-containing polyester is immiscible.

The solid polymer electrolyte used in the separator region (e.g., separator region 360 or 460) can be any electrolyte suitable for Li batteries. Of course, many such electrolytes also include electrolyte salts that help provide ionic conductivity. Examples of useful lithium salts include, but are not limited to, LiPF₆、LiN(CF₃SO₂)₂(LiTFSI)、Li(CF₃SO₂)₃C、LiN(SO₂CF₂CF₃)₂、LiN(FSO₂)2、LiN(CN)₂、LiB(CN)4、 LiB(C₂O₄)₂、Li₂B₁₂F_xH_12-x、Li₂B₁₂F₁₂And mixtures thereof. Examples of such electrolytes include, but are not limited to, block copolymers comprising ion-conducting blocks and structural blocks that constitute an ion-conducting phase and a structural phase, respectively. The ionically conductive phase may comprise one or more linear polymers, such as polyethers, polyamines, polyimides, polyamides, polyalkylcarbonates, polynitriles, perfluoropolyethers, fluorocarbon polymers substituted with high dielectric constant groups (e.g., nitriles, carbonates, and sulfones), and combinations thereof. In one arrangement, the ionically conductive phase comprises one or more phosphorus-containing polyester electrolytes as disclosed herein. Linear polymers may also be used as graft copolymers in combination with polysiloxanes, polyalkoxysiloxanes, polyphosphazines, polyolefins and/or polydienes to form the conductive phase. The structural phase may be formed from materials such as polystyrene, hydrogenated polystyrene, polymethacrylates, poly (methyl methacrylate), polyvinylpyridine, polyvinylcyclohexane, polyimide, polyamide, polypropylene, polyolefins, poly (t-butyl vinyl ether), poly (cyclohexyl methacrylate), poly (cyclohexyl vinyl ether)Ethers), poly (t-butyl vinyl ether), polyethylene, polyphenylene oxide, poly (2, 6-dimethyl-1, 4-phenylene oxide), polyphenylene sulfide sulfone, polyphenylene sulfide ketone, polyphenylene sulfide amide, polysulfone, fluorocarbons (e.g., polyvinylidene fluoride), or copolymers containing styrene, methacrylate, or vinyl pyridine. It is particularly useful if the structural phase is rigid and is in a glassy or crystalline state.

For the embodiments depicted in fig. 2 and 3, suitable cathode active materials include, but are not limited to, LFP (lithium iron phosphate), LMP (lithium-metal phosphate where the metal may be Mn, Co, or Ni), V₂O₅(vanadia pentoxide), NCA (lithium nickel cobalt aluminum oxide), NCM (lithium nickel cobalt manganese oxide), high energy NCM (HE-NCM-magnesium rich lithium nickel cobalt manganese oxide), lithium manganese spinel, lithium nickel manganese spinel, and combinations thereof. Suitable electron conducting additives include, but are not limited to, carbon black, graphite, vapor grown carbon fibers, graphene, carbon nanotubes, and combinations thereof. A binder may be used to hold the cathode active material particles and the electron conductive additive together. Suitable binders include, but are not limited to, PVDF (polyvinylidene fluoride), PVDF-HFP (polyvinylidene fluoride-co-hexafluoropropylene), PAN (polyacrylonitrile), PAA (polyacrylic acid), PEO (polyethylene oxide), CMC (carboxymethylcellulose), and SBR (styrene butadiene rubber).

Any of the polymers described herein may be liquid or solid, depending on their molecular weight. Any of the polymers described herein can be in a crosslinked state or an uncrosslinked state. Any of the polymers described herein may be crystalline or glassy. Any of the polymers described herein can be copolymerized with other polymers to form copolymers, block copolymers, or graft copolymers. Copolymerization may also affect the mechanical properties of certain polymers, making them solid polymer electrolytes. Any of the polymers described herein can be combined with an electrolyte salt to serve as a solid polymer electrolyte. Any of these solid polymer electrolytes can be used as a separator, a catholyte, an anolyte, or any combination thereof in a battery cell.

Examples of the invention

The following examples provide details relating to the synthesis of phosphorus-containing polyesters according to the present invention. It should be understood that the following is representative only, and that the invention is not limited by the details set forth in this example.

In one example, a synthetic route to poly (dibutyl dimethyl diphosphonate) is shown below.

The present invention has been described herein in considerable detail in order to provide those skilled in the art with information pertaining to the novel principles of application and the configuration and use of such specialized components. However, it is to be understood that the invention may be carried out by different equipment, materials and devices, and that various modifications, both as to the equipment and operating procedures, may be accomplished without departing from the scope of the invention itself.