Battery cathodes comprising intrinsically conductive polymers

Abstract

Provided herein are improved lithium-ion battery cathodes that comprise intrinsically conductive polymers (ICPs) such as polyaniline dinonylnaphthalene sulfonic acid (PANI- DNNSA). Lithium-ion battery cathodes that utilize intrinsically conductive polymers may, for example, exhibit increased conductivity and charge density as compared to battery cathodes prepared using conventional, non-conductive polymers.

Description

BATTERY CATHODES COMPRISING INTRINSICALLY CONDUCTIVEPOLYMERSCROSS REFERENCE

[0001] This application claims the benefit of priority from U.S. Provisional Patent Application Serial No. 63 / 600,907 filed on November 20, 2023, the disclosure of which is incorporated herein by reference.FIELD

[0002] The present disclosure relates to battery cathodes, for example lithium-ion battery cathodes, having an improved composition.BACKGROUND

[0003] Lithium-ion batteries have gained widespread adoption due to their high energy density, long cycle life, and relatively low cost compared to other battery technologies. Lithium-ion batteries are commonly used in a wide variety of applications and industries, including portable electronic devices, electric vehicles, and renewable energy storage systems, among many others.

[0004] In typical embodiments, a lithium-ion battery comprises a cathode, an anode, a separator, and an electrolyte. The electrolyte carries positively charged lithium ions from the anode to the cathode and vice versa through the separator. The movement of the lithium ions creates free electrons in the anode, which can be used to produce an electrical current.

[0005] Since the early 1990s, a variety of battery cathode compositions have been commercialized, including lithium cobalt oxide (LiCoCh), lithium manganese oxide (LiMnCh), lithium iron phosphate (LFP or LiFePCh), lithium nickel cobalt aluminum oxide (NCA), and nickel manganese cobalt (NMC). These materials are particulate in nature and are poorly conductive, resulting in low power densities and limits on charge / discharge current densities to avoid fires.

[0006] Today, battery cathodes are typically prepared by formulating intractable lithium metal oxide (LMO) powders in an insulating polymer resin (binder) containing carbon to enhance the conductivity of the resulting cathode. Currently available battery designs require particle-particle contact (percolation) forconductivity. This requires high loadings of the LMO in the binder that lead to brittle electrode films and failures.

[0007] There is a need in the industry for battery cathodes having improved electrical conductivity, and which provide enhanced power and energy density when incorporated into existing lithium-ion battery designs.SUMMARY

[0008] In one aspect, provided herein is a lithium-ion battery cathode that may comprise one or more of the following components: a cathode substrate comprising a lithium compound; a conductive polymer component comprising at least one conductive polymer; an insulating polymer component comprising one or more insulating polymer resins; and a conductivity enhancing component comprising one or more conductivity enhancers.

[0009] Also provided herein is a composition comprising core-shell particles, wherein the core-shell particles comprise a core layer comprising at least one alkali metal compound, and a conductive polymer layer comprising at least one conductive polymer.

[0010] Also provided herein is a core-shell particle comprising: a core layer comprising at least one alkali metal compound; and a conductive polymer layer comprising PANI-DNNSA. Preferably, the core-shell particle comprises the core layer in an amount of from about 20 percent by weight to about 80 percent by weight of the particle as a whole.

[0011] Also provided herein is a method of making core-shell particles, the method comprising providing a solid particulate material comprising at least one alkali metal compound; preparing a coating composition comprising at least one conductive polymer dispersed in an organic solvent; dispersing the solid particulate material in the coating composition, thereby forming coated particles; separating the coated particles form the coating composition; and drying the coated particles at an elevated temperature.

[0012] Other objects and features will be in part apparent and in part pointed out hereinafter.DESCRIPTION OF THE DRAWINGS

[0013] FIG. 1 depicts a schematic view of a lithium-ion battery 100 comprising a cathode substrate 102, a conductive polymer component 104, an electrolyte 106 and an anode 108.

[0014] FIG. 2 depicts a cross-sectional view of a core-shell particle 200 comprising a core layer 202 which is encapsulated by a conductive polymer layer 204.

[0015] FIG. 3 is an overlay of cyclic voltammogram readings taken on a glassy carbon electrode as described in Example 3.

[0016] FIG. 4 is an overlay of cyclic voltammogram readings taken on a glassy carbon electrode as described in Example 4.

[0017] FIG. 5 is an overlay of cyclic voltammogram readings taken on a gold electrode as described in Example 4.

[0018] FIG. 6 depicts the electrochemical resistance and capacitance of different conductive polymers as described in Example 4.

[0019] FIG. 7 is an overlay of cyclic voltammogram readings taken on a black iron wire as described in Example 5.DETAILED DESCRIPTION

[0020] Provided herein are improved lithium-ion battery cathodes that comprise intrinsically conductive polymers (ICPs). Lithium-ion battery cathodes that utilize intrinsically conductive polymers may, for example, exhibit increased conductivity and charge density as compared to battery cathodes prepared using conventional, non-conductive polymers.

[0021] For example, provided herein are processible intrinsically conductive polymers (ICPs) for coatings on LMO or LFP particles to enhance electrical conductivity and lithium-ion transport. The methods provided herein may comprise, for example, adding an ICP to an insulating polymer binder resin to enhance and improve the conductivity of the electrode composite structure.

[0022] Also provided herein are core-shell particles comprising a core layer comprising an alkali metal compound, and a conductive polymer layer comprising at least one conductive polymer. The core-shell particles may, for example, be useful as battery cathodes. Specifically, where the alkali metal compounds is alithium compound, the core-shell particles may be used as lithium-ion battery cathodes as described in further detail below.Lithium-Ion Battery Cathodes

[0023] Provided herein is a lithium-ion battery cathode that may comprise, consist essentially of, or consist of one or more of the following components: (1) a cathode substrate comprising a lithium compound, (2) a conductive polymer component comprising at least one conductive polymer, (3) an insulating polymer component comprising one or more insulating polymer resins, and (4) a conductivity enhancing component comprising one or more conductivity enhancers. Each of these components is described in further detail below.

[0024] Cathode Substrate

[0025] The lithium-ion battery cathode may comprise a cathode substrate. For example, the composition may comprise a particulate metal compound that is useful in the construction of battery cathodes.

[0026] The cathode substrate may comprise, for example, a lithium compound. Nonlimiting examples of cathode substrates include lithium cobalt oxide (LiCoCh), lithium manganese oxide (LiMnCh), lithium iron phosphate (LFP or LiFePCh), lithium nickel cobalt aluminum oxide (NCA), and nickel manganese cobalt (NMC). A preferred cathode substrate is lithium iron phosphate (LFP).

[0027] The cathode substrate may comprise a lithium compound in the form of a solid particulate. For example, in typical embodiments, the solid particulate may have a mean particle size of from about 1 nm to about 1000 nm. In typical embodiments, the solid particulate may, for example, have a D90 particle size of from about 10 nm to about 6000 nm.

[0028] For example, the solid particulate may have a mean particle size of at least about 0.5 nm, at least about 1 nm, at least about 2 nm, at least about 5 nm, at least about 10 nm, at least about 25 nm, at least about 50 nm, or at least about 100 nm. Conversely, the solid particulate may have a mean particle size of, for example, no greater than about 2000 nm, no greater than about 1500 nm, no greater than about 1000 nm, no greater than about 900 nm, no greater than about 800 nm, no greater than about 700 nm, no greater than about 600 nm, or no greater than about 500 nm.The solid particulate may have a mean particle size that falls within a rangebounded by any two values listed above. As non-limiting examples, the solid particulate may have a mean particle size of from about 1 nm to about 2000 nm, from about 1 nm to about 1000 nm, or from about 10 nm to about 500 nm.

[0029] The solid particulate may have a D90 particle size of at least about 5 nm, at least about 10 nm, at least about 20 nm, at least about 50 nm, at least about 100 nm, at least about 250 nm, at least about 500 nm, or at least about 1000 nm. Conversely, the solid particulate may have a D90 particle size of, for example, no greater than about 20,000 nm, no greater than about 15,000 nm, no greater than about 10,000 nm, no greater than about 9000 nm, no greater than about 8000 nm, no greater than about 7000 nm, no greater than about 6000 nm, or no greater than about 5000 nm. The solid particulate may have a D90 particle size that falls within a range bounded by any two values listed above. As non-limiting examples, the solid particulate may have a D90 particle size of from about 10 nm to about 10,000 nm, from about 100 nm to about 10,000 nm, or from about 1000 nm to about 6000 nm.

[0030] The lithium-ion battery cathode may comprise the cathode substrate in an amount of, for example, from about 1 percent by weight to about 90 percent by weight of the composition as a whole.

[0031] For example, the lithium-ion battery cathode may comprise the cathode substrate in an amount of at least about 1 percent by weight, at least about 5 percent by weight, at least about 10 percent by weight, at least about 20 percent by weight, at least about 30 percent by weight, at least about 40 percent by weight, at least about 50 percent by weight, or at least about 60 percent by weight of the composition as a whole. Conversely, the lithium-ion battery cathode may comprise the cathode substrate in an amount of, for example, at most about 90 percent by weight, at most about 85 percent by weight, at most about 80 percent by weight, at most about 75 percent by weight, or at most about 70 percent by weight of the composition as a whole. The lithium-ion battery cathode may comprise the cathode substrate in an amount that falls within a range bounded by any two values listed above. As non-limiting examples, the lithium-ion battery cathode may comprise the cathode substrate in an amount of from about 1 percent by weight to about 90 percent by weight, from about 20 percent by weight to about 80 percent by weight, or from about 40 percent by weight to about 70 percent by weight of the composition as a whole.

[0032] Conductive Polymer

[0033] The lithium-ion battery cathode may comprise a conductive polymer component comprising one or more conductive polymers. In the lithium-ion battery cathodes provided herein, the conductive polymer serves to bind together the cathode substrate (which may be in the form of a solid particulate, as discussed above) without decreasing the overall conductivity and charge density of the cathode, as is the case with traditional non-conductive polymers used for this purpose.

[0034] Without being bound to a particular theory, it is believed that the use of an intrinsically conductive polymer serves to increase the conductivity and charge density of the battery cathode by providing an electrically conductive network between substrate particles that efficiently utilizes the charge capacity of all the particles, shuttling electrons to and from the substrate particles as lithium ions are de-intercalated and intercalated into the substrate particles. Advantageously, in contrast to conventional battery cathodes, the substrate particles do not need to be in physical contact with one another and could be below the percolation limit.

[0035] In preferred embodiments, the conductive polymer is soluble in an organic solvent. For example, the conductive polymer may be soluble in an organic solvent selected from the group consisting of xylene, toluene, cymene, and ether.

[0036] Non-limiting examples of suitable conductive polymers include polyanilines, such as polyaniline dinonylnaphthalene sulfonic acid (PANI-DNNSA), polyaniline camphor sulfonic acid (PANI-CSA), polyaniline dodecylbenzene sulfonic acid (PANI-DBSA), polyaniline polystyrene sulfonic acid (PANI-PSSA); polyethylene di oxy thiophene polystyrene sulfonic acid (PEDOT-PSSA); polypyrrole; and combinations thereof. For example, the conductive polymer component may comprise PANI-DNSSA.

[0037] The conductive polymer component may comprise an alkali metal-doped conductive polymer. As used herein, the term “alkali metal-doped conductive polymer” refers to a conductive polymer wherein at least a portion of the hydrogen atoms naturally present in the polymer have been replaced with alkali metal cations. For example, the alkali metal-doped conductive polymer may be a lithium-doped conductive polymer wherein at least a portion of the hydrogen atoms naturally present in the polymer have been replaced with lithium cations. An alkali metal-doped conductive polymer may be prepared by soaking a conductive polymer in an alkali metal hydroxide (e.g., lithium hydroxide).

[0038] Non-limiting examples of suitable alkali metal-doped conductive polymers include alkali metal-doped polyanilines, such as alkali metal-doped PANI-DNNSA, alkali metal-doped PANI-CSA, alkali metal-doped PANI-DBSA, alkali metal- doped PANI-PSSA; alkali metal-doped PEDOT-PSSA; alkali metal-doped polypyrrole; and combinations thereof. For example, the conductive polymer component may comprise a lithium-doped conductive polymer selected from the group consisting of lithium-doped PANI-DNNSA, lithium-doped PANI-CSA, lithium-doped PANI-DBSA, lithium-doped PANI-PSSA, lithium-doped PEDOT-PSSA, lithium-doped polypyrrole, and combinations thereof. As a non-limiting example, the conductive polymer component may comprise lithium-doped PANI- DNSSA.

[0039] As an illustrative example, the polymer component may comprise lithium- doped PANI-DNSSA comprising DNSSA and aniline in a molar ratio of about 6:4, as shown in the following exemplary structure.Formula I

[0040] For alkali metal-doped conductive polymers, the optimal amount of doping will depend on the concentration of conducting groups present in the conductive polymer. For example, with respect to PANI-DNNSA, the molar ratio of DNNSA to aniline in the polymer is controlled during the polymer synthesis, and can range from about 1 to 3. There is usually an excess of DNNSA to keep the polymer soluble. When the PANI-DNSSA is reacted with LiOH, the DNNSA units neutralized by the hydroxide, leaving lithium salts of the DNNSA units. Accordingly, if a PANI-DNSSA having a starting DNNSA / aniline molar ratio of2: 1 is fully neutralized using LiOH, the resulting lithium doped PANI-DNSSA has 2 moles of LiDNNS (lithium dinonlynaphthalene sulfonate) per mole of aniline.

[0041] Conductive polymers, and particularly lithium doped conductive polymers, may be both electron conducting as well as lithium ion conducting. For example, in a lithium-ion battery cathode comprising LFP as the cathode substrate, a lithium doped conductive polymer would facilitate lithium ion transport to the LFP substrate. When the battery charges, lithium ions move out of the LFP substrate; when the battery discharges, lithium ions move into the LFP substrate. Additionally, the lithium doped conductive polymer may act as a barrier for negatively charged species from the electrolyte that may contaminate the cathode substrate and decrease cycle life. The lithium doped conductive polymer may inhibit dendrite growth.

[0042] The lithium-ion battery cathode may comprise the conductive polymer component in an amount, for example, of at least about 0.1 percent by weight, at least about 0.5 percent by weight, at least about 1 percent by weight, at least about 2 percent by weight, at least about 3 percent by weight, at least about 4 percent by weight, at least about 5 percent by weight, or at least about 10 percent by weight of the composition as a whole. Conversely, the lithium-ion battery cathode may comprise the conductive polymer component in an amount of, for example, at most about 30 percent by weight, at most about 25 percent by weight, at most about 20 percent by weight, at most about 15 percent by weight, or at most about 10 percent by weight of the composition as a whole. The lithium-ion battery cathode may comprise the conductive polymer component in an amount that falls within a range bounded by any two values listed above. As non-limiting examples, the lithium-ion battery cathode may comprise the conductive polymer component in an amount of from about 0.1 percent by weight to about 25 percent by weight, from about 1 percent by weight to about 25 percent by weight, or from about 5 percent by weight to about 25 percent by weight of the composition as a whole.

[0043] The lithium-ion battery cathode may, for example, comprise the conductive polymer component in a weight ratio of about 1 : 1 or less with respect to the cathode substrate. For example, the weight ratio of the conductive polymer component to the cathode substrate may be at most about 1 : 1, at most about 0.9: 1, at most about 0.8: 1, at most about 0.7:1, at most about 0.6: 1, at most about 0.5: 1, or at most about 0.4: 1. Conversely, the lithium-ion battery cathode may comprise the conductive polymer component in a weight ratio of, for example, at least about 0.01 : 1, at leastabout 0.05: 1, at least about 0.1 : 1, at least about 0.15: 1, at least about 0.2: 1, or at least about 0.25: 1 with respect to the cathode substrate. The lithium-ion battery cathode may comprise the conductive polymer component and the cathode substrate in a weight ratio that falls within a range bounded by any two values listed above. As non-limiting examples, the lithium-ion battery cathode may comprise the conductive polymer component and the cathode substrate in a weight ratio of from about 0.01 : 1 to about 1: 1, from about 0.1 : 1 to about 1 : 1, or from about 0.2: 1 to about 0.6: 1.

[0044] Insulating Polymer

[0045] The lithium-ion battery cathode may comprise an insulating polymer component comprising one or more insulating polymer resins. In the lithium-ion battery cathodes provided herein, the insulating polymer resin component may optionally be used in combination with a conductive polymer component as described above. Incorporating an insulating polymer resin component into the battery cathode may be desirable, for example, to increase the flexibility of the cathode structure.

[0046] Non-limiting examples of suitable insulating polymer resins include polyvinylidene difluoride, polytetrafluoroethylene (PTFE), styrene-butadiene block copolymers (SBR), sodium carboxymethylcellulose (CMC), polyacrylates, ethylene-propylene-diene rubber (EPDM), and mixtures thereof. For example, the insulating polymer component may comprise polyvinylidene difluoride.

[0047] The lithium-ion battery cathode may comprise the insulating polymer resin component in an amount of, for example, from about 0.1 percent by weight to about 25 percent by weight of the composition as a whole.

[0048] The lithium-ion battery cathode may comprise the insulating polymer component in an amount, for example, of at least about 0.1 percent by weight, at least about 0.5 percent by weight, at least about 1 percent by weight, at least about 2 percent by weight, at least about 3 percent by weight, at least about 4 percent by weight, at least about 5 percent by weight, or at least about 10 percent by weight of the composition as a whole. Conversely, the lithium-ion battery cathode may comprise the insulating polymer component in an amount of, for example, at most about 30 percent by weight, at most about 25 percent by weight, at most about 20percent by weight, at most about 15 percent by weight, or at most about 10 percent by weight of the composition as a whole. The lithium-ion battery cathode may comprise the insulating polymer component in an amount that falls within a range bounded by any two values listed above. As non-limiting examples, the lithium-ion battery cathode may comprise the insulating polymer component in an amount of from about 0.1 percent by weight to about 25 percent by weight, from about 1 percent by weight to about 25 percent by weight, or from about 5 percent by weight to about 25 percent by weight of the composition as a whole.

[0049] Conductivity Enhancers

[0050] The lithium-ion battery cathode may further comprise a conductivity enhancing component comprising one or more conductivity enhancers. Conductivity enhancers include secondary dopants that allow the polymer chains to extend and increase pi stacking and chain-to-chain electron hopping.

[0051] Non-limiting examples of conductivity enhancers that may be added to improve conductivity include sulfonyl diphenol (SDP), meta-cresol, p-toluene sulfonamide, p-toluene sulfonic acid, lithium stearate, and combinations thereof.

[0052] The lithium-ion battery cathode may comprise the one or more conductivity enhancers in an amount of from about 0.1 percent by weight to about 10 percent by weight of the composition as a whole.

[0053] For example, the lithium-ion battery cathode may comprise the conductivity enhancing component in an amount, for example, of at least about 0.1 percent by weight, at least about 0.5 percent by weight, at least about 1 percent by weight, at least about 2 percent by weight, at least about 3 percent by weight, at least about 4 percent by weight, or at least about 5 percent by weight of the composition as a whole. Conversely, the lithium-ion battery cathode may comprise the conductivity enhancing component in an amount of, for example, at most about 10 percent by weight, at most about 9 percent by weight, at most about 8 percent by weight, at most about 7 percent by weight, at most about 6 percent by weight, or at most about 5 percent by weight of the composition as a whole. The lithium-ion battery cathode may comprise the conductivity enhancing component in an amount that falls within a range bounded by any two values listed above. As non-limiting examples, the lithium-ion battery cathode may comprise the conductivity enhancing component inan amount of from about 0.1 percent by weight to about 10 percent by weight, from about 1 percent by weight to about 10 percent by weight, or from about 1 percent by weight to about 5 percent by weight of the composition as a whole.Lithium-Ion Battery

[0054] Also provided herein is a lithium-ion battery comprising a lithium-ion battery cathode as generally described above.

[0055] For example, FIG. 1 depicts a schematic view of a lithium-ion battery 100. Generally, the lithium-ion battery 100 comprises a cathode substrate 102, a conductive polymer component 104, an electrolyte 106 and an anode 108.

[0056] Generally, cathode substrate 102 may be selected as described in detail above. As shown in FIG. 1, cathode substrate 102 comprises lithium iron phosphate (LFP).

[0057] Generally, the conductive polymer component 104 may be selected as described in detail above. As shown in FIG. 1, conductive polymer component 104 comprises lithium doped PANI.

[0058] The electrolyte 106 may generally comprise any suitable electrolyte composition known to those skilled in the art. Non-limiting examples of electrolyte salts suitable for use in lithium-ion batteries include lithium hexafluorophosphate, lithium bis(trifluoromethanesulfonyl)imide, lithium tetrafluoroborate, lithium perchlorate, lithium bis(oxalato)borate, lithium difluoro(oxalato)borate, lithium triflate, and lithium bis(fluorosulfonyl)imide. As shown in FIG. 1, electrolyte 106 comprises lithium hexafluorophosphate. Electrolyte 106 may comprise the electrolyte salt in a concentration of, for example, from about 0.1 mole / L to about 10 mole / L, more typically from about 0.5 moles / L to about 2 moles / L, or most typically about 1 mole / L.

[0059] Optionally, electrolyte 106 may further comprise a solvent component comprising one or more solvents. Non-limiting examples of suitable solvents include carbonate solvents such as ethylene carbonate, dimethyl carbonate, propylene carbonate, ethylmethyl carbonate, and combinations thereof.

[0060] The anode 108 may generally comprise any suitable material known for use as an anode in a lithium-ion battery. For example, anode 108 may comprise graphite.Core-Shell Particles

[0061] Also provided herein is a composition comprising core-shell particles, wherein the core-shell particles comprise, consist essentially of, or consist of (1) a core layer comprising at least one alkali metal compound, and (2) a conductive polymer layer comprising at least one conductive polymer. Optionally, the conductive polymer layer may further comprise one or more of (a) an insulating polymer component comprising one or more insulating polymer resins, and (b) a conductivity enhancing component comprising one or more conductivity enhancers. Core-shell particles as provided herein may be useful, for example, as alkali metal battery cathodes (for example, lithium-ion battery cathodes) as generally described above.

[0062] Turning now to the figures, FIG. 2 shows a cross-sectional view of a coreshell particle 200. The particle 200 comprises a core layer 202 which is encapsulated by a conductive polymer layer 204.

[0063] As shown in FIG. 2, conductive polymer layer 204 encapsulates core layer 202 and forms a continuous interface across the entire surface of core layer 202. In alternative embodiments, the core-shell particle may comprise one or more additional layers between conductive polymer layer 204 and core layer 202, and / or one or more additional layers exterior to conductive polymer layer 204.

[0064] Core layer 202 comprises at least one alkali metal compound. Non-limiting examples of alkali metal compounds include lithium cobalt oxide, lithium nickel manganese cobalt oxide, lithium iron phosphate, lithium nickel cobalt aluminum oxide, lithium manganese oxide, lithium titanate, sodium nickel chloride, sodium cobalt oxide, sodium iron phosphate, potassium iron phosphate, lithium vanadium oxide, lithium nickel oxide, sodium manganese oxide, lithium manganese nickel oxide, lithium copper oxide, sodium vanadium oxide, lithium titanium oxide, sodium titanium oxide, lithium manganese titanium oxide, lithium nickel manganese oxide, lithium iron silicate, lithium manganese silicate, lithium iron borate, lithium manganese borate, lithium iridium, rhodium oxides, platinum oxides, and mixtures thereof. Preferably, the alkali metal compound comprises a lithium compound, which may be selected as generally described above with respect to the lithium-ion battery cathode substrate. For example, the alkali metal compound may comprise lithium iron phosphate.

[0065] Typically, core layer 202 will account for a weight fraction of about 1 percent by weight to about 90 percent by weight of core-shell particle 200 as a whole.

[0066] For example, core-shell particle 200 may comprise the core layer 202 in an amount of at least about 1 percent by weight, at least about 5 percent by weight, at least about 10 percent by weight, at least about 20 percent by weight, at least about 30 percent by weight, at least about 40 percent by weight, at least about 50 percent by weight, or at least about 60 percent by weight of the particle as a whole. Conversely, core-shell particle 200 may comprise core layer 202 in an amount of, for example, at most about 90 percent by weight, at most about 85 percent by weight, at most about 80 percent by weight, at most about 75 percent by weight, or at most about 70 percent by weight of the particle as a whole. Core-shell particle 200 may comprise core layer 202 in an amount that falls within a range bounded by any two values listed above. As non-limiting examples, core-shell particle 200 may comprise core layer 202 in an amount of from about 1 percent by weight to about 90 percent by weight, from about 20 percent by weight to about 80 percent by weight, or from about 40 percent by weight to about 70 percent by weight of the particle as a whole.

[0067] Conductive polymer layer 204 comprises at least one conductive polymer, which may be selected as generally described above with respect to the lithium-ion battery cathode substrate. For example, conductive polymer layer 204 may comprise at least one conductive polymer selected from the group consisting of polyanilines, such as polyaniline dinonylnaphthalene sulfonic acid (PANI- DNNSA), polyaniline camphor sulfonic acid (PANI-CSA), polyaniline dodecylbenzene sulfonic acid (PANI-DBSA), polyaniline polystyrene sulfonic acid (PANI-PSSA); polyethylene di oxy thiophene polystyrene sulfonic acid (PEDOT- PSSA); polypyrrole; and combinations thereof. As a further example, conductive polymer layer 204 may comprise an alkali metal-doped conductive polymer as described in detail above.

[0068] Conductive polymer layer 204 may optionally comprise an insulating polymer component comprising one or more insulating polymer resins, which may be selected as described above. For example, conductive polymer layer 204 may optionally comprise polyvinylidene difluoride.

[0069] Conductive polymer layer 204 may optionally comprise a conductivity enhancing component comprising one or more conductivity enhancers. For example, conductive polymer layer 204 may optionally comprise at least one conductivity enhancer selected from the group consisting of sulfonyl diphenol (SDP), meta-cresol, p-toluene sulfonamide, p-toluene sulfonic acid, lithium stearate, and combinations thereof.

[0070] Conductive polymer layer 204 may comprise the conductive polymer component in a concentration of at least about 10% by weight, relative to the total weight of conductive polymer layer 204. For example, conductive polymer layer 204 may comprise the conductive polymer component in a concentration of at least about 15% by weight, at least about 20% by weight, at least about 25% by weight, at least about 30% by weight, at least about 35% by weight, or at least about 40% by weight. Conversely, conductive polymer layer 204 may comprise the conductive polymer component in a concentration of at most about 80% by weight, at most about 75% by weight, at most about 70% by weight, at most about 65% by weight, at most about 60% by weight, at most about 55% by weight, or at most about 50% by weight. Conductive polymer layer 204 may comprise the conductive polymer component in a concentration that falls within a range bounded by any two values listed above. For example, conductive polymer layer 204 may comprise the conductive polymer component in a concentration of from about 10% by weight to about 80% by weight, or from about 20% by weight to about 70% by weight.

[0071] Conductive polymer layer 204 may comprise the insulating polymer component in a concentration of at least about 10% by weight, relative to the total weight of conductive polymer layer 204. For example, conductive polymer layer 204 may comprise the insulating polymer component in a concentration of at least about 15% by weight, at least about 20% by weight, at least about 25% by weight, at least about 30% by weight, at least about 35% by weight, or at least about 40% by weight. Conversely, conductive polymer layer 204 may comprise the insulating polymer component in a concentration of at most about 60% by weight, at most about 55% by weight, at most about 50% by weight, at most about 45% by weight, at or at most about 40% by weight. Conductive polymer layer 204 may comprise the insulating polymer component in a concentration that falls within a range bounded by any two values listed above. For example, conductive polymer layer204 may comprise the insulating polymer component in a concentration of from about 10% by weight to about 50% by weight, or from about 20% by weight to about 40% by weight.

[0072] Conductive polymer layer 204 may comprise a conductivity enhancing component in a concentration of at least about 0.5% by weight, relative to the total weight of conductive polymer layer 204. For example, conductive polymer layer 204 may comprise the conductivity enhancing component in a concentration of at least about 1% by weight, at least about 1.5% by weight, at least about 2% by weight, at least about 3% by weight, at least about 4% by weight, or at least about 5% by weight. Conversely, conductive polymer layer 204 may comprise the conductivity enhancing component in a concentration of at most about 15% by weight, at most about 10% by weight, at most about 9% by weight, at most about 8% by weight, at most about 7% by weight, at most about 6% by weight, at most about 5% by weight, at most about 4% by weight, at most about 3% by weight, or at most about 2% by weight. Conductive polymer layer 204 may comprise the conductivity enhancing component in a concentration that falls within a range bounded by any two values listed above. For example, conductive polymer layer 204 may comprise the conductivity enhancing component in a concentration of from about 0.5% by weight to about 10% by weight, or from about 1% by weight to about 5% by weight.

[0073] The composition may comprise core-shell particles having a mean particle size of from about 1 nm to about 1000 nm. In typical embodiments, the solid particulate may, for example, have a D90 particle size of from about 10 nm to about 6000 nm.

[0074] For example, the composition may comprise core-shell particles having a mean particle size of at least about 0.5 nm, at least about 1 nm, at least about 2 nm, at least about 5 nm, at least about 10 nm, at least about 25 nm, at least about 50 nm, or at least about 100 nm. Conversely, the composition may comprise core-shell particles having a mean particle size of, for example, no greater than about 2000 nm, no greater than about 1500 nm, no greater than about 1000 nm, no greater than about 900 nm, no greater than about 800 nm, no greater than about 700 nm, no greater than about 600 nm, or no greater than about 500 nm. The composition may comprise core-shell particles having a mean particle size that falls within a range bounded by any two values listed above. As non-limiting examples, thecomposition may comprise core-shell particles having a mean particle size of from about 1 nm to about 2000 nm, from about 1 nm to about 1000 nm, or from about 10 nm to about 500 nm.

[0075] The composition may comprise core-shell particles having a D90 particle size of at least about 5 nm, at least about 10 nm, at least about 20 nm, at least about 50 nm, at least about 100 nm, at least about 250 nm, at least about 500 nm, or at least about 1000 nm. Conversely, the composition may comprise core-shell particles having a D90 particle size of, for example, no greater than about 20,000 nm, no greater than about 15,000 nm, no greater than about 10,000 nm, no greater than about 9000 nm, no greater than about 8000 nm, no greater than about 7000 nm, no greater than about 6000 nm, or no greater than about 5000 nm. The composition may comprise core-shell particles having a D90 particle size that falls within a range bounded by any two values listed above. As non-limiting examples, the composition may comprise core-shell particles having a D90 particle size of from about 10 nm to about 10,000 nm, from about 100 nm to about 10,000 nm, or from about 1000 nm to about 6000 nm.Methods of Making Core-Shell Particles

[0076] Also provided herein are methods of making core-shell particles, and particularly core-shell particles as described in detail above. The methods may comprise any one or more of the following steps: (1) providing a solid particulate material comprising at least one alkali metal compound; (2) preparing a coating composition comprising at least one conductive polymer dispersed in an organic solvent; (3) dispersing the solid particulate material in the coating composition, thereby forming coated particles; (4) separating the coated particles form the coating composition; and (5) removing excess solvent from the coated particles.

[0077] The solid particulate material preferably has a particle size distribution as described above with respect to the cathode substrate. The alkali metal may be selected as described above with respect to the core-shell particles.

[0078] The coating composition may comprise any solvent in which the at least one conductive polymer has sufficient solubility. For example, the solvent may comprise water (for example, when the conductive polymer is PEDOT-PSS). The solvent may comprise an organic solvent. Non-limiting examples of suitableorganic solvents include NMP (N-methyl-2-pyrrolidone), N,N-Dimethylacetamide (DMAc), xylene, toluene, cymene, and ether. The at least one conductive polymer may be selected as described in detail above.

[0079] The solid particulate material may be dispersed in the coating composition using any suitable technique known to those skilled in the art. For example, the solid particulate material may be dispersed by mixing (e.g., with a high shear mixer).

[0080] The coated particles may be separated from the coating composition using any suitable technique known to those skilled in the art. For example, the coated particles may be separated from the coating composition by filtration. Optionally, the coated particles may be washed with a solvent (for example, isopropanol) before they are filtered. Depending on the size of the coated particles, an ultrafiltration membrane having a pore size of from about 0.3 nm to about 10 nm could be used to carry out the filtration. As a further alternative, the particles could be separated from the coating composition using an ultra-centrifuge.

[0081] The coated particles may be dried at an elevated temperature to remove excess solvent. For example, the coated particles may be dried at a temperature at least about 40 °C, at least about 50 °C, at least about 60 °C, at least about 70 °C, or at least about 80 °C. Typically, the coated particles are dried at a temperature of no greater than about 100 °C. The particles may be dried for a time sufficient to substantially remove any excess solvent, typically within a range of from about 1 hour to about 24 hours (for example, from about 1 hour to about 4 hours).

[0082] The coated particles may be dried under a reduced pressure. For example, the coated particles may be dried at a pressure of less than about 1000 mbar, less than about 800 mbar, less than about 600 mbar, less than about 500 mbar, less than about 420 mbar, less than about 400 mbar, less than about 350 mbar, or less than about 300 mbar. In some embodiments, the coated particles may be dried at a very low pressure of less than about 250 mbar, less than about 200 mbar, less than about 150 mbar, or even less than about 100 mbar. As a non-limiting example, the coated particles may be dried at a pressure of from about 10 mbar to about 500 mbar, or at a pressure of from about 200 to 400 mbar, or at a pressure of from about 10 to 100 mbar..

[0083]

[0084] The following examples illustrate various aspects of the present invention. The examples should, of course, be understood to be merely illustrative of only certain embodiments of the invention and not to constitute limitations upon the scope of the invention which is defined by the claims that are appended at the end of this description.

[0085] Having described the disclosure in detail, it will be apparent that modifications and variations are possible without departing from the scope of the claims.EXAMPLES

[0086] The following non-limiting examples are provided to further illustrate the present disclosure.

[0087] Example 1 : Polyaniline Lithium Iron Phosphate (LFP)

[0088] This example illustrates the use of an ICP coating to provide a more conductive LFP structure with improved conductivity, charge / discharge stability and reduced charge transfer resistance.

[0089] Here, polyaniline dinonylnaphthalene sulfonic acid (PANI-DNNSA), a highly soluble form of polyaniline is employed to formulate a higher conductivity cathode that provides a more stable structure as the electrode discharges (lithium intercalation) and charges (lithium de-intercalation). The PANI-DNNSA is a cation dominant transport system and facilitates lithium-ion transport as it oxidizes and reduces during charging and discharging, respectively.

[0090] Details:

[0091] LFP powder is dispersed in a dilute solution of PANI-DNNSA in an organic solvent (xylene, toluene, cymene or ether) using a high shear mixer. After a period of time, the coated particles are separated from the solvent by filtration and tumble dried to remove the solvent. The coated particles are then rinsed with a solvent (isopropanol, ethanol, or acetone) to remove excess dopant (DNNSA). After further drying under vacuum, the electrical conductivity of the powder is measured (method described in Carbon 40 (2002) 2801-2815).

[0092] At this point, various amounts the coated powder are dispersed in a resin solution (10 wt.% polyvinylidene fluoride in NMP). The formulations are coated onto a current collector electrode (glassy carbon, gold, or copper electrodes) and dried. Electrochemical measurements are performed in ethylene carbonate(EC) / dimethyl carbonate (DMC) solvent containing 0.1 M lithium hexafluorophosphate (LiPFe) in a 3 -electrode configuration with a lithium reference electrode and platinum counter electrode. Energy density, power density and cycle life will be measured and compared with controls.

[0093] Example 2: Polyaniline Lithium Metal Oxide (LMO) Cathode

[0094] In this example, the objective is to form a more stable LMO structure with improved conductivity, charge / discharge stability and reduced charge transfer resistance.

[0095] In the effort described here, LiMn2O4 will be evaluated as the base LMO since it is environmentally more benign than other LMOs and lower cost. The proposed technology would apply to other LMO’s such as LiCoO2.

[0096] Details:

[0097] LiMn2O4 (supplied by American Elements) is dispersed into PANLDNNSA toluene. Other additives such as sulfonyl diphenol (SDP) and lithium stearate are then added to the formulation to enhance conductivity. At this point, the formulation may be used as is as a coating or blended into a graphite / PVDF resin solution (10 wt.% Ketjen black (KB, Lion Co. Ltd.) and 10 wt.% polyvinylidene fluoride (PVDF, Canrd Co. Ltd.) in NMP).

[0098] At this point, various amounts the coated powder are dispersed in a resin solution (10 wt.% polyvinylidene fluoride in NMP). The formulations are coated onto a current collector electrode (glassy carbon, gold, or copper electrodes) and dried. Electrochemical measurements are performed in ethylene carbonate (EC) / dimethyl carbonate (DMC) solvent containing 0.1 M lithium hexafluorophosphate (LiPFe) in a 3 -electrode configuration with a lithium reference electrode and platinum counter electrode. Energy density, power density and cycle life will be measured and compared with controls.

[0099] Note that this process described in examples 1 and 2 above would translate to other active Li metal oxide anode materials including Li cobalt oxide, Li-cobalt, Li- nickel aluminum oxide, Li-nickel manganese cobalt as well as Li-Manganese, iron or cobalt silicates.

[0100] Example 3: Preparation of Lithium -Doped PANI-DNSSA

[0101] PANLDNNSA was dissolved in cymene at about 5% w / w. 10 drops of the solution was added to a 1 ml of water in a vial containing 100 mg of lithium hydroxide. The solution was shaken for a few seconds, after which the green PANI- DNNSA solution turned blue and phase separated into a clear lower layer aqueous and a blue upper layer cymene layer containing the lithium doped PANLDNNSA. The upper layer was coated onto a glassy carbon electrode and allowed to dry for 3 days in air. After this period a cyclic voltammogram (shown as FIG. 3) was run on the electrode in a 2.8% solution of lithium nitrate in water.

[0102] As shown in FIG. 3, Curve A shows the oxidation wave of Lithium PANI- DNNSA coating as compared with Curve B for the glassy carbon electrode.

[0103] Example 4: Electrochemical Evaluation of Lithium -Doped PANI-DNSSA

[0104] 0.5 microliters of 50% solution of PANLDNNSA in toluene was applied to both glassy carbon and gold electrodes. The electrodes were allowed to dry for 24 hours at ambient temperature and both cyclic voltammetry and impedance spectroscopy experiments were performed in 2.8% Lithium nitrate.

[0105] The electrodes were evaluated each of the following sequential chemical treatments: (1) no treatment; (2) 10 second dip in isopropanol; and (3) 10 minute soak in 1 M LiOH solution.

[0106] An overlay of the cyclic voltammograms is shown in FIG. 4. Curve A is the CV for the untreated PANI film on GC, Curve B is the IP A treated film, and Curve C is the Lithium doped PANI DNNSA curve. Though the 10 minutes in the KOH solution neutralized the PANLDNNSA, the film still exhibited electroactivity due to lithium ion transport facilitation.

[0107] The coated gold electrode behaved similarly to the glassy carbon electrode, as shown in FIG. 5.

[0108] The electrochemical impedance of each treatment was also evaluated, and the results are depicted in FIG. 6. As shown in the chart, it appears the lithium doped polymer behaves very similarly to the non-lithium doped polymers coatings in terms of resistance and capacitance.

[0109] Example 5: Electrochemical Evaluation of Lithium -Doped PANI-DNSSA

[0110] 0.125 mm black iron wire (low carbon steel) was abraded with Grade # 000 steel wool, wiped with 70% isopropanol in water and immersed in boiling 10% phosphoric acid for 10 minutes. After rinsing with water, the potential of the wire was cycled ten times between -0.5 and 0.6 V versus SCE in 2.8% lithium nitrate to produce lithium iron oxide (LiFeCL) on the wire’s surface.[OHl] The wire was then dip coated in a 5% PANI solution in xylene and air dried. Cyclic voltammetry was then run on the PANLDNNSA coated LiFeCh iron wire (Curve A in FIG. 7) in 2.8% lithium nitrate. The coated wire was then dipped in a 70% isopropanol solution for 10 seconds and air dried. Cyclic voltammetry as then run on this specimen (Curve B in FIG. 7). Curve C shown in FIG. 7 is for a wire that was cleaned as described above and immersed in boiling phosphoric acid (the control). The red and blue curves show a pronounced enhancement of current between 0 and 0.6 volts demonstrating an increase in cathode current versus the control.

[0112] When introducing elements of the present disclosure or the preferred embodiment s) thereof, the articles “a”, “an”, “the”, and “said” are intended to mean that there are one or more of the elements. The terms “comprising”, “including”, and “having” are intended to be inclusive and mean that there may be additional elements other than the listed elements.

[0113] In view of the above, it will be seen that the several objects of the disclosure are achieved and other advantageous results attained.

[0114] As various changes could be made in the above products and methods without departing from the scope of the disclosure, it is intended that all matter contained in the above description shall be interpreted as illustrative and not in a limiting sense.

Claims

CLAIMSWhat is claimed is:

1. A lithium-ion battery cathode comprising:(1) a cathode substrate comprising a lithium compound; and(2) a conductive polymer component comprising at least one conductive polymer; wherein the cathode comprises the conductive polymer component and the cathode substrate in a weight ratio of from about 0.01 : 1 to about 1 : 1.

2. The cathode of claim 1 wherein the cathode substrate comprises a lithium compound selected from the group consisting of lithium cobalt oxide, lithium manganese oxide, lithium iron phosphate, lithium nickel cobalt aluminum oxide, and combinations thereof.

3. The cathode of claim 1 wherein the cathode substrate comprises lithium iron phosphate.

4. The cathode of any one of claims 1 to 3 comprising the cathode substrate in an amount of at least about 10 percent by weight of the composition as a whole.

5. The cathode of any one of claims 1 to 3 wherein the conductive polymer component comprises a conductive polymer selected from the group consisting of poly aniline dinonylnaphthalene sulfonic acid (PANI-DNNSA), polyaniline camphor sulfonic acid (PANI-CSA), polyaniline dodecylbenzene sulfonic acid (PANI-DBSA), polyaniline polystyrene sulfonic acid (PANI-PSSA), polyethylene di oxy thiophene polystyrene sulfonic acid (PEDOT-PSSA), polypyrrole, and combinations thereof.

6. The cathode of claim 5 wherein the conductive polymer component comprises PANI- DNNSA.

7. The cathode of any one of claims 1 to 3 wherein the conductive polymer component comprises an alkali metal-doped conductive polymer.

8. The cathode of any one of claims 1 to 6 comprising the conductive polymer component in an amount of at least about 1 percent by weight of the composition as a whole.

9. The cathode of any one of claims 1 to 7 comprising the conductive polymer component and the cathode substrate in a weight ratio of from about 0.1 : 1 to about 1 : 1.

10. The cathode of claim 9 wherein the cathode substrate comprises a lithium compound in the form of a solid particulate having a mean particle size of from about 1 nm to about 1000 nm.

11. The cathode of claim 9 or 10 wherein the cathode substrate comprises a lithium compound in the form of a solid particulate having a D90 particle size of from about 10 nm to about 6000 nm.

12. The cathode of any one of claims 1 to 11 wherein the cathode further comprises an insulating polymer component comprising one or more insulating polymer resins.

13. The cathode of claim 12 wherein the insulating polymer component comprises polyvinylidene difluoride.

14. The cathode of claim 12 or 13 comprising the insulating polymer component in an amount of from about 0.1 percent by weight to about 25 percent by weight of the composition as a whole.

15. The cathode of any one of claims 1 to 14 wherein the cathode further comprises a conductivity enhancing component comprising one or more conductivity enhancers.

16. The cathode of claim 15 wherein the conductivity enhancing component comprises at least one conductivity enhancer selected from the group consisting of sulfonyl diphenol (SDP), meta-cresol, p-toluene sulfonamide, p-toluene sulfonic acid, lithium stearate, and combinations thereof.

17. The cathode of claim 15 or 16 comprising the conductivity enhancing component in an amount of from about 0.1 percent by weight to about 10 percent by weight of the composition as a whole.

18. A composition comprising core-shell particles, wherein the core-shell particles comprise: (1) a core layer comprising at least one alkali metal compound, and (2) a conductive polymer layer comprising at least one conductive polymer.

19. The composition of claim 18 wherein the core layer comprises at least one alkali metal compound selected from the group consisting of lithium cobalt oxide, lithium nickel manganese cobalt oxide, lithium iron phosphate, lithium nickel cobalt aluminum oxide, lithium manganese oxide, lithium titanate, sodium nickel chloride, sodium cobalt oxide, sodium iron phosphate, potassium iron phosphate, lithium vanadium oxide, lithium nickel oxide, sodium manganese oxide, lithium manganese nickel oxide, lithium copper oxide, sodium vanadium oxide, lithium titanium oxide, sodium titanium oxide, lithium manganese titanium oxide, and lithium nickel manganese oxide.

20. The composition of claim 19 wherein the core layer comprises lithium iron phosphate.

21. The composition of claim 18 wherein the conductive polymer layer comprises at least one conductive polymer selected from the group consisting of polyaniline dinonylnaphthalene sulfonic acid (PANI-DNNSA), polyaniline camphor sulfonic acid (PANI-CSA), polyaniline dodecylbenzene sulfonic acid (PANI-DBSA), polyaniline polystyrene sulfonic acid (PANI-PSSA), polyethylene di oxy thiophene polystyrene sulfonic acid (PEDOT-PSSA), and polypyrrole (PPy).

22. The composition of claim 21 wherein the conductive polymer layer comprises PANI- DNNSA.

23. The composition of any one of claims 18 to 22 wherein the core-shell particles have a mean particle size of from about 1 nm to about 2000 nm.

24. The composition of any one of claims 18 to 23 wherein the core-shell particles have a D90 particle size of from about 10 nm to about 10,000 nm.

25. The composition of any one of claims 18 to 24 wherein the core-shell particles comprise the core layer in an amount of from about 20 percent by weight to about 80 percent by weight of the particles as a whole.

26. A core-shell particle comprising:(1) a core layer comprising at least one alkali metal compound selected from the group consisting of lithium cobalt oxide, lithium nickel manganese cobalt oxide, lithium iron phosphate, lithium nickel cobalt aluminum oxide, lithium manganese oxide, lithium titanate, sodium nickel chloride, sodium cobalt oxide, sodium iron phosphate, potassium iron phosphate, lithium vanadium oxide, lithium nickel oxide, sodium manganese oxide, lithium manganese nickel oxide, lithium copper oxide, sodium vanadium oxide, lithium titanium oxide, sodium titanium oxide, lithium manganese titanium oxide, and lithium nickel manganese oxide; and(2) a conductive polymer layer comprising PANI-DNNSA; wherein the particle comprises the core layer in an amount of from about 20 percent by weight to about 80 percent by weight of the particle as a whole.

27. The core-shell particle of claim 26 wherein the core layer comprises lithium iron phosphate.

28. A method of making core-shell particles, the method comprising:(1) providing a solid particulate material comprising at least one alkali metal compound;(2) preparing a coating composition comprising at least one conductive polymer dispersed in an organic solvent;(3) dispersing the solid particulate material in the coating composition, thereby forming coated particles;(4) separating the coated particles form the coating composition; and(5) drying the coated particles at an elevated temperature.

29. The method of claim 28 wherein the solid particulate material comprises at least one alkali metal compound selected from the group consisting of lithium cobalt oxide, lithium nickel manganese cobalt oxide, lithium iron phosphate, lithium nickel cobalt aluminumoxide, lithium manganese oxide, lithium titanate, sodium nickel chloride, sodium cobalt oxide, sodium iron phosphate, potassium iron phosphate, lithium vanadium oxide, lithium nickel oxide, sodium manganese oxide, lithium manganese nickel oxide, lithium copper oxide, sodium vanadium oxide, lithium titanium oxide, sodium titanium oxide, lithium manganese titanium oxide, and lithium nickel manganese oxide.

30. The method of claim 29 wherein the solid particulate material comprises lithium iron phosphate.

31. The method of claim 28 wherein the coating composition comprises at least one conductive polymer selected from the group consisting of polyaniline dinonylnaphthalene sulfonic acid (PANI-DNNSA), polyaniline camphor sulfonic acid (PANI-CSA), polyaniline dodecylbenzene sulfonic acid (PANI-DBSA), polyaniline polystyrene sulfonic acid (PANI- PSSA), polyethylene di oxy thiophene polystyrene sulfonic acid (PEDOT-PSSA), and polypyrrole (PPy).

32. The method of claim 31 wherein the coating composition comprises PANI-DNNSA.

33. The method of claim 28 wherein the coating composition comprises an organic solvent selected from the group consisting of xylene, toluene, cymene, and ether.

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