JP7252691B2 - Conformable Alkali-Sulfur Batteries with Deformable and Conductive Quasi-Solid Electrodes - Google Patents

Description

CROSS-REFERENCE TO RELATED APPLICATIONS This application is filed on June 30, 2017 and U.S. Patent Application Serial No. 15/638,811, filed June 30, 2017, which is hereby incorporated by reference. No. 15/638,854, filed herein.

The present invention relates generally to the field of alkali metal-sulfur batteries, such as rechargeable lithium metal-sulfur batteries, sodium metal-sulfur batteries, lithium ion-sulfur batteries, and sodium ion-sulfur batteries.

Rechargeable lithium-ion (Li-ion) and lithium-metal batteries (such as Li-sulphur and Li-metal-air batteries) are widely used in electric vehicles (EV), hybrid electric vehicles (HEV), and portable electronic devices such as laptop computers. and is considered a potential power source for mobile phones. Lithium as a metallic element has the highest capacity (3,861 mAh/g) when compared with any other metal or metal-intercalated compound as an anode active material (specific capacity is 4,200 mAh/g except for _Li4.4Si ). Li metal batteries therefore generally have a much higher energy density than lithium ion batteries.

Historically, rechargeable lithium metal batteries have used non-lithiated compounds with relatively high specific capacities as cathode active materials, _such as _TiS2 , _MoS2 , _MnO2 , _CoO2 , and _V2O5 , These were produced by combining them with a lithium metal anode. As the battery discharges, lithium ions migrate from the lithium metal anode through the electrolyte to the cathode, where the cathode becomes lithiated. Unfortunately, upon repeated charge/discharge, lithium metal forms dendrites at the anode, which eventually grow and penetrate the separator, causing internal short circuits and explosions. As a result of a series of accidents related to this problem, production of these types of secondary batteries was discontinued in the early 1990's and replaced by lithium ion batteries.

In lithium-ion batteries, carbonaceous materials have been used as anodes instead of sheets or films of pure lithium metal. During the recharge and discharge phases of lithium-ion battery operation, respectively, the carbonaceous material absorbs lithium (eg, by intercalation of lithium ions or atoms between graphene planes) and desorbs lithium ions. The carbonaceous material can contain primarily graphite in which lithium can be intercalated, and the resulting graphite intercalation compound can be represented by Li _x C ₆ , where x is typically 1. is less than

Lithium-ion (Li-ion) batteries are a promising energy storage device for electric powered vehicles, but state-of-the-art Li-ion batteries have not yet met cost and performance goals. Li-ion cells typically use a lithium transition metal oxide or phosphate as the positive electrode (cathode) where Li ⁺ deintercalates/reintercalates at high potentials against a carbon negative electrode (anode). be. The specific capacity of cathode active materials based on lithium transition metal oxides or phosphates is typically in the range of 140-170 mAh/g. As a result, the specific energy of commercial Li-ion cells is typically in the range of 120-250 Wh/kg, most typically in the range of 150-220 Wh/kg. These specific energy values are 1/2 to 1/3 of the values required for widespread acceptance of battery electric vehicles.

With the rapid development of hybrid (HEV), plug-in hybrid electric vehicles (HEV), and all-battery electric vehicles (EV), much higher specific energy, higher energy density, higher rate capability, longer cycle life, and stability. There is an urgent need for anodic and cathodic materials from which rechargeable batteries can be obtained. One of the most promising energy storage devices is the lithium-sulphur (Li—S) cell because Li has a theoretical capacity of 3,861 mAh/g and S has a theoretical capacity of 1,675 mAh/g. Because. In its simplest form, a Li—S cell consists of elemental sulfur as the positive electrode and lithium as the negative electrode. This lithium-sulphur cell operates with a redox couple represented by the reaction S ₈ +16Li←→8Li ₂ S at approximately 2.2 V relative to Li ⁺ /Li ^o . This electrochemical potential is approximately two-thirds that of the conventional positive electrode (eg, LiMnO ₄ ) in conventional lithium-ion batteries. However, this drawback is offset by the very high theoretical capacities of both Li and S. Therefore, compared to conventional intercalation-based Li-ion batteries, Li—S cells have the potential for much higher energy densities (the product of capacity and voltage). Assuming complete reaction to Li ₂ S, energy density values can approach 2,500 Wh/kg and 2,800 Wh/L based on the combined weight or volume of Li and S, respectively. Based on total cell weight or volume, the energy densities can approach 1,000 Wh/kg and 1,100 Wh/L, respectively. However, current Li-sulfur cells reported by industry leaders in sulfur cathode technology have maximum cell specific energies of 250-400 Wh/kg and 500-650 Wh/L (based on total cell weight or volume). , and these are much lower than achievable values.

In summary, despite its great advantages, Li—S cells suffer from some major technical problems that have greatly hampered their widespread commercialization:
(1) Conventional lithium metal cells still have dendrite formation and related internal short circuit problems.
(2) Sulfur or sulfur-containing organic compounds are highly insulating, both electrically and ionic. To enable reversible electrochemical reactions at high current densities or charge/discharge rates, it is necessary to maintain intimate contact between the sulfur and the electrically conductive additive. Various carbon-sulfur composites have been used for this purpose with only limited success due to the limited size of the contact area. Typical capacities reported are between 300-550 mAh/g at moderate rates (based on the weight of the cathode carbon-sulfur composite).
(3) Cells tend to exhibit large capacity losses during discharge-charge cycles. This is mainly due to the high solubility of the lithium polysulfide anions, which are formed as reaction intermediates during both the discharge and charge processes, in the polar organic solvents used in the electrolyte. During cycling, the lithium polysulfide anions can migrate through the separator to the Li negative electrode, where they are reduced to solid deposits (Li ₂ S ₂ and/or Li ₂ S), thereby reducing the active mass to Decrease. Furthermore, solid products that deposit on the cathode surface during discharge become electrochemically irreversible, which also contributes to the reduction of active mass.
(4) More generally, a major drawback of cells containing cathodes containing elemental sulfur, organic sulfur, and carbon-sulfur materials is that soluble sulfides, polysulfides, organic sulfides, carbon-sulfides, and/or or associated with dissolution of carbon-polysulfides (hereafter referred to as anion reduction products) and excessive outdiffusion from the cathode to the rest of the cell. This reduction is commonly referred to as the shuttle effect. Several problems arise with this method, including high self-discharge rates, reduced cathode capacity, corrosion of the current collectors and electrical leads leading to reduced electrical contact to the active cell components, and corrosion of the anode surface leading to failure of the anode. Fouling and clogging of pores in the cell membrane separators leads to reduced ion transport and a large increase in internal resistance in the cell.

To meet these challenges, new electrolytes, protective films for lithium anodes, and solid electrolytes have been developed. Although the development of some interesting cathodes containing lithium polysulfides has recently been reported, their performance still falls short of that required for practical applications.

For example, Ji et al. reported that cathodes based on nanostructured sulfur/mesoporous carbon materials can overcome these challenges to a large extent, exhibiting stable and high reversible capacities with good rate characteristics and cycling efficiencies. [Xiulei Ji, Kyu Tae Lee, & Linda F.; Nazar, "A highly ordered nanostructured carbon-sulfur cathode for lithium-sulfur batteries," Nature Materials 8, 500-506 (2009)]. However, the proposed fabrication of highly oriented mesoporous carbon structures requires template-based methods that are slow and expensive. It is also difficult to load large proportions of sulfur into these mesoscale pores using physical vapor deposition or solution precipitation.

Zhang et al. (U.S. Patent Application Publication No. 2014/0234702; 08/21/2014) used a chemical reaction method to deposit S particles on the surface of isolated graphene oxide (GO) sheets. . However, this method fails to form a large proportion of S particles on the GO surface (ie, typically <66% S in GO—S nanocomposite compositions). The resulting Li—S cell also exhibits low rate capability; to Note that the maximum achievable specific capacity of 1,100 mAh/g is only 1,100/1,675 = 65.7% sulfur utilization efficiency even at such a low charge/discharge rate ( 0.02C means that the charging or discharging process is completed in 1/0.02=50 hours; 1C=1 hour, 2C=1/2 hour, and 3C=1/3 hour, etc.). In addition, such S-GO nanocomposite cathode-based Li-S cells exhibit very low cycle life, typically less than 60% of their original capacity for less than 40 charge/discharge cycles. down to Such short cycle life does not render this Li--S cell useful in any practical application. Another chemical reaction method to deposit S particles on graphene oxide surfaces has been disclosed by Wang et al. This Li--S cell still has the same problem.

A solution precipitation method for producing graphene-sulfur nanocomposites (with sulfur particles adsorbed on the GO surface) for use as cathode materials in Li-S cells has been disclosed by Liu et al. Patent Application Publication No. 2012/0088154; 04/12/2012). This method involves mixing GO sheets and S in a solvent ( _CS2 ) to form a suspension. Evaporation of the solvent then yields a solid nanocomposite, which is then milled to yield a nanocomposite powder having primary sulfur particles with an average diameter of less than about 50 nm. Unfortunately, this method does not appear to be capable of producing S-particles smaller than 40 nm. The resulting Li-S cells exhibit very poor cycle life (50% capacity drop after only 50 cycles). Even when these nanocomposite particles are encapsulated in polymers, Li—S cells retain less than 80% of their original capacity after 100 cycles. The cell also exhibits low rate capability (1,050 mAh/g (S weight) specific capacity at 0.1 C rate drops to <580 mAh/g at 1.0 C rate). Again, this indicates that a large proportion of S is not contributing to lithium storage, resulting in low S utilization efficiency.

Although various methods have been proposed to fabricate Li-S cells with high energy densities, the utilization of electroactive cathode materials (S utilization efficiency) has been improved, leading to high-capacity rechargeable batteries over large number of cycles. There remains a need for cathode materials and manufacturing methods that yield Li—S cells.

Most notably, lithium metal (including pure lithium, high lithium content lithium alloys with other metallic elements, or high lithium content lithium containing compounds; e.g. >80% by weight, or preferably >90% wt % Li) still gives the highest anode specific capacity compared to virtually all other anode active materials (except pure silicon, which has grinding problems). Lithium metal is an ideal anode material in lithium-sulphur secondary batteries if it can address the problems associated with dendrites.

Sodium metal (Na) and potassium metal (K) have chemical properties similar to Li, and sulfur cathodes in room temperature sodium-sulfur cells (RTNa-S cells) or potassium sulfur-cells (KS) also They face the same problems observed in Li—S batteries such as (i) low active material utilization, (ii) short cycle life, and (iii) low coulombic efficiency. Again, these drawbacks are primarily due to the insulating properties of S, the dissolution of S with Na or K polysulfide intermediates in the liquid electrolyte (and the associated shuttle effect), and large volume changes during charge/discharge. occur.

In most of the published literature reports (scholarly articles) and patent literature, scientists or inventors prefer to express cathode specific capacity based on the weight of sulfur or lithium polysulfide only (rather than the weight of the total cathode composite). Although selected, it is unfortunately noted that a large proportion of inactive materials (those incapable of storing lithium, such as conductive additives and binders) are typically used in those Li—S cells. sea bream. For practical purposes, it makes more sense to use capacitance values based on cathode composite weight.

Low capacity anode or cathode active materials are not the only problem associated with lithium-sulfur or sodium-sulfur batteries. There are significant design and manufacturing issues that the battery industry seems to be unaware of or largely ignores. For example, despite the seemingly high gravimetric capacity at the electrode level (based solely on the weight of the anode or cathode active material), as frequently claimed in the published and patent literature, these electrodes Unfortunately, it is not possible to provide batteries with high capacity at the battery cell or pack level (based on total battery cell weight or pack weight). This is due to the observation that the actual active material mass loading of the electrodes is too low in these reports. In most cases, the active material mass loading (area density) of the anode is much lower than 15 mg/cm ² and is often <8 mg/cm ² (area density = per electrode cross-sectional area along the thickness of the electrode). amount of active material). The amount of cathode active material is typically 1.5 to 2.5 times the amount of anode active material in the cell. As a result, the weight ratio of anode active material (e.g., carbon) in a Na ion-sulfur battery cell or Li ion-sulfur battery cell is typically between 15% and 20%, and the weight ratio of cathode active material is , 20% to 35% (mostly <30%). The combined weight fraction of cathode active material and anode active material is typically 35% to 50% of the cell weight.

The low active material mass loading is primarily due to the inability to obtain relatively thick electrodes (greater than 100-200 μm) using conventional slurry coating procedures. This is not as easy a task as one might think, and in reality, electrode thickness is not a design parameter that can be arbitrarily and freely varied to optimize cell performance. Thicker samples, on the other hand, tend to be very brittle or have poor structural integrity and require the use of large amounts of binder resin. Due to the low melting and soft properties of sulfur, the fabrication of sulfur cathodes with a thickness greater than 100 μm was virtually impossible. Furthermore, in a practical battery manufacturing facility, a coated electrode thickness greater than 150 μm would require a 100 meter long heating zone to completely dry the coated slurry. This significantly increases equipment costs and reduces manufacturing throughput. Due to the low areal density and low volumetric density (related to thin electrodes and low packing density), the battery cell has a relatively low volumetric capacity and a low volumetric energy density.

With the growing demand for more compact and portable energy storage systems, there is a strong interest in increasing battery volume utilization. To achieve improvements in cell volumetric capacity and energy density, new electrode materials and designs that allow high volumetric capacity and high mass loading are essential.

Accordingly, one of the objects of the present invention is to solve the following problems commonly associated with conventional Li-S and Na-S cells: (a) dendrite formation (internal short circuit); Low electrical and ionic conductivity requires a large proportion (typically 30-55%) of inert conductive fillers and a significant proportion of unavailable or non-rechargeable sulfur or alkali metal polysulfides. (c) the dissolution of S and alkali metal polysulfides into the electrolyte and the migration of the polysulfides from the cathode to the anode (which react irreversibly with the Li or Na metal of the anode) to form the active material. (d) short cycle life; (e) low active mass loading at both the anode and cathode. To provide a rechargeable alkali metal-sulfur cell based on the design.

One of the specific objectives of the present invention is to provide rechargeable alkali metal-sulphur batteries (eg primarily Li-S batteries and room temperature Na-S batteries) that exhibit very high specific energy or high energy density. . One of the specific technical goals of the present invention is that the specific energy of the cell exceeds 400 Wh/kg, preferably exceeds 500 Wh/kg, more preferably exceeds 600 Wh/kg, and most preferably exceeds 700 Wh/kg (all To provide an alkali metal-sulfur cell or an alkali ion-sulfur cell (based on total cell weight). Preferably, the volumetric energy density is above 600 Wh/L, more preferably above 800 Wh/L, most preferably above 1,000 Wh/L.

Another object of the present invention is to exceed 1,200 mAh/g based on sulfur weight, or cathode composite weight (including sulfur, conductive additive, or substrate, with binder weight added, but To provide an alkali metal-sulfur cell exhibiting a high cathode specific capacity exceeding 1,000 mAh/g based on the weight of the cathode current collector). The specific capacity is preferably greater than 1,400 mAh/g based on sulfur weight alone, or greater than 1,200 mAh/g based on cathode composite weight. This should be accompanied by high specific energy, good resistance to dendrite formation, and long and stable cycle life.

As electronic devices become smaller and electric vehicles (EVs) become lighter, high energy that is form-conformable so that it can fit into some special shapes or confined spaces in the device or vehicle High density batteries are urgently needed. Making the device smaller by incorporating the battery into a space that would otherwise remain empty (unused or "wasted") space (e.g., part of a car door or rooftop). or allow EVs to store more power. To make the battery conformable, the electrodes need to be deformable, flexible and conformable.

Lithium and sodium batteries with high active material mass loading (high areal density), large electrode thickness or volume without compromising conductivity, high rate capability, high power density, and high energy density are therefore clearly urgent. is necessary. These batteries need to be manufactured in an environmentally friendly manner. Additionally, the battery must be conformable.

The present invention is a lithium-sulphur battery with high active material mass loading, very low overhead weight and volume (based on active material mass and volume), high capacity, and unprecedented high energy and power densities. , a sodium-sulfur battery, or a potassium-sulfur battery. The Li—S, Na—S, or KS batteries may be primary (non-rechargeable) or secondary (rechargeable) batteries, such as rechargeable lithium metal-sulfur batteries or sodium metal-sulfur batteries (lithium or sodium metal anode), and a lithium ion sulfur battery or a sodium ion sulfur battery (eg, having a first lithium intercalation compound as the anode active material). This battery also includes a potassium-sulfur battery.

In certain embodiments, the present invention provides: (a) about 30% to about 95% by volume sulfur-containing cathode active material (preferably sulfur, metal-sulfur compounds, sulfur-carbon composites, sulfur-graphene composites, sulfur - selected from graphite composites, organic sulfur compounds, sulfur-polymer composites, or combinations thereof) and an alkali salt dissolved in a solvent (but dissolved in this solvent, dispersed in this solvent) from about 5% to about 40% by volume of a first electrolyte and from about 0.01% to about 30% by volume of a conductive additive; In a quasi-solid cathode comprising a conductive additive comprising conductive filaments forms a 3D network of electronic conduction paths such that the quasi-solid electrode has an electrical conductivity of about 10 ⁻⁶ S/cm to about 300 S/cm , a quasi-solid cathode; (b) an anode; and (c) an ion-conducting membrane or porous separator disposed between the anode and the quasi-solid cathode; An alkali-sulfur cell is provided having a thickness of 200 μm or more. The quasi-solid cathode is preferably 10 mg/cm ² or more, preferably 15 mg/cm ² or more, more preferably 25 mg/cm ^{2 or} more, more preferably 35 mg/cm ² or more, even more preferably 45 mg/cm 2 or more, and most preferably 10 mg/cm ² or more. It preferably has a cathode active material mass loading greater than 65 mg/cm ² .

In the cell, the anode comprises from about 1.0% to about 95% by volume of the anode active material and an alkali salt dissolved in a solvent (dissolved in the solvent, dispersed in the solvent, or from about 5% to about 40% by volume of a second electrolyte, including some solvent-impregnated ion-conducting polymer, or no ion-conducting polymer, and from about 0.01% to about 30% by volume. and a conductive additive comprising a conductive filament, such that the quasi-solid electrode has an electrical conductivity of from about 10 ⁻⁶ S/cm to about 300 S/cm. Additives form a 3D network of electron-conducting pathways; the quasi-solid anode has a thickness of 200 μm or more. The quasi-solid anode is preferably 10 mg/cm ² or more, preferably 15 mg/cm ² or more, more preferably 25 mg/cm ^{2 or} more, more preferably 35 mg/cm ² or more, even more preferably 45 mg/cm 2 or more, and most preferably 10 mg/cm ² or more. It preferably has an anode active material mass loading greater than 65 mg/cm ² . The first electrolyte can be the same or different in composition and structure from the second electrolyte.

In some embodiments, the present invention comprises: (A) from about 1.0% to about 95% by volume of an anode active material and an alkali salt dissolved in a solvent (dissolved in the solvent; about 5 to about 40 vol. In a solid anode, a quasi-solid electrode in which a conductive additive comprising conductive filaments forms a 3D network of electronic conduction paths such that the quasi-solid electrode has an electrical conductivity of about 10 ⁻⁶ S/cm to about 300 S/cm. a solid anode; and (B) selected from sulfur, metal-sulfur compounds, sulfur-carbon composites, sulfur-graphene composites, sulfur-graphite composites, organic sulfur compounds, sulfur-polymer composites, or combinations thereof. (C) an ion-conducting membrane or porous separator disposed between the quasi-solid anode and the cathode; wherein the quasi-solid anode and cathode are Alkali-sulphur cells are provided, each preferably having a thickness of 200 μm or more.

The quasi-solid electrodes according to the present invention are deformable, flexible and conformable, thereby enabling conformable batteries.

The present invention provides a method for manufacturing an alkali-sulphur cell with quasi-solid electrodes: (a) a quantity of active material (anode active material or cathode active material) and a quantity of electrolyte comprising an alkali salt dissolved in a solvent. and a conductive additive to form a deformable and electrically conductive electrode material, wherein the conductive additive comprising conductive filaments forms a 3D network of electron conducting pathways; (b ) In the step of forming a quasi-solid electrode (first electrode) from the above electrode material, the step of forming is performed so that the electrode has a viscosity of 10 ⁻⁶ S/cm or more (preferably 10 ⁻⁵ S/cm or more, more preferably 10 ⁻³ S/cm or more, more preferably 10 ⁻² S/cm or more, even more preferably typically 10 ⁻¹ S/cm or more, still more typically preferably 1 S/cm or more, still more typically (c ) forming a second electrode (which may also be a quasi-solid electrode); and forming an alkali-sulfur cell by combining with a second electrode.

A "filament" is an object of solid material having some largest dimension (e.g. length) and some smallest dimension (e.g. diameter or thickness), wherein the ratio of largest dimension to smallest dimension is greater than 3, preferably greater than 10. , more preferably greater than 100. Typically, this is a wire-like, fibrous, needle-like, rod-like, platelet-like, sheet-like, ribbon-like, or disc-like object, to name a few. In some embodiments, the conductive filaments are carbon fibers, graphite fibers, carbon nanofibers, graphite nanofibers, carbon nanotubes, needle coke, carbon whiskers, conductive polymer fibers, conductive material-coated fibers, metal nanowires, metal fibers, Selected from metal wires, graphene sheets, expanded graphite platelets, combinations thereof, or combinations thereof with non-filamentary conductive particles.

In some embodiments, the electrode maintains an electrical conductivity of 10 ⁻⁵ S/cm to about 100 S/cm.

In some embodiments, the deformable electrode material has an apparent viscosity of greater than or equal to about 10,000 Pa-s measured at an apparent shear rate of 1,000 s ^-1 . In some embodiments, the deformable electrode material has an apparent viscosity of greater than or equal to about 100,000 Pa-s at an apparent shear rate of 1,000 s ^-1 .

In this method, the amount of active material is typically about 20% to about 95% by volume electrode material, more typically about 35% to about 85% by volume electrode material, most typically about 50% to about 75% by volume of the electrode material.

Preferably, the steps of combining the active material, the conductive additive, and the electrolyte (including dissolving the lithium or sodium salt in the liquid solvent) follow a specific order. This step comprises first dispersing the conductive filaments in a liquid solvent to form a uniform suspension; and dissolving in. In other words, before adding another component such as an active material and before dissolving the lithium salt or sodium salt in the solvent, the conductive filaments must first be uniformly dispersed in the liquid solvent. This order is important to achieve permeation of the conductive filaments to form a 3D network of electronic conduction pathways at lower conductive filament volume fractions (lower threshold volume fraction). If such an order is not followed, penetration of the conductive filaments may not occur, or may occur only when an excessively large proportion of conductive filaments (e.g., >10% by volume) is added, thereby The fraction of active material is reduced, thus lowering the energy density of the cell.

In some embodiments, the step of combining and forming a quasi-solid electrode from the electrode material includes dissolving a lithium salt (or sodium salt) in a liquid solvent to form an electrolyte having a first salt concentration; Subsequently removing a portion of the liquid solvent to increase the salt concentration to a second salt higher than the first concentration, preferably greater than 2.5M salt (more preferably between 3.0M and 14M) and obtaining a quasi-solid electrolyte having a concentration. The resulting electrolyte is saturated or supersaturated in that neither precipitation nor crystallization of salts from the electrolyte occurs.

Removing a portion of the solvent can be done in such a way that the electrolyte is saturated or supersaturated without causing salt precipitation or crystallization. In certain preferred embodiments, the liquid solvent comprises a mixture of at least a first liquid solvent and a second liquid solvent, wherein the first liquid solvent is more volatile than the second liquid solvent and one of the liquid solvents is Removing the portion includes partially or completely removing the first liquid solvent. The resulting electrolyte is saturated or supersaturated in that neither precipitation nor crystallization of salts from the electrolyte occurs.

There is no limit to the types of anode active materials that can be used in the practice of the invention. In one preferred embodiment, the alkali metal cell is a lithium metal battery, a lithium ion battery, or a lithium ion capacitor, and the anode active material is: (a) particles of lithium metal or lithium metal alloy; (b) particles of natural graphite; Artificial graphite particles, mesocarbon microbeads (MCMB), carbon particles (such as soft carbon and hard carbon), needle coke, carbon nanotubes, carbon nanofibers, carbon fibers, and graphite fibers; (c) silicon (Si), germanium ( Ge), tin (Sn), lead (Pb), antimony (Sb), bismuth (Bi), zinc (Zn), aluminum (Al), nickel (Ni), cobalt (Co), manganese (Mn), titanium ( Ti), iron (Fe), and cadmium (Cd); (d) in alloys or intermetallic compounds of Si, Ge, Sn, Pb, Sb, Bi, Zn, Al, or Cd with another element, in stoichiometric amounts (e) oxides of Si, Ge, Sn, Pb, Sb, Bi, Zn, Al, Fe, Ni, Co, Ti, Mn, or Cd; (f) prelithiated versions thereof; (g) prelithiated graphene sheets; and selected from the group consisting of combinations thereof;

In some embodiments, the alkali metal cell is a sodium metal-sulfur cell or a sodium ion sulfur cell and the active material is petroleum coke, amorphous carbon, activated carbon, hard carbon (difficult to graphitize carbon), soft carbon. (readily graphitizable carbon ₎ , template carbon, _hollow carbon nanowires _, hollow carbon spheres _, titanates, _NaTi2 ( _PO4 ) ₃ , _Na2Ti3O7 , _{Na2C8H4O4 , Na2TP} , Na _x TiO ₂ (x=0.2-1.0), Na ₂ C ₈ H ₄ O ₄ , carboxylate-based materials, C ₈ H ₄ Na ₂ O ₄ , C ₈ H ₆ O ₄ , C ₈ H _{sodium intercalation selected from 5NaO4 , C8Na2F4O4 , C10H2Na4O8 , C14H4O6 , C14H4Na4O8 , or combinations thereof} An anode active material comprising a compound.

In some embodiments, the alkali metal cell is a sodium metal-sulfur cell or a sodium ion sulfur cell and the active material is: (a) particles of sodium metal or sodium metal alloy; (b) particles of natural graphite, particles of artificial graphite; mesocarbon microbeads (MCMB), carbon particles, needle coke, carbon nanotubes, carbon nanofibers, carbon fibers, and graphite fibers; (c) sodium-doped silicon (Si), germanium (Ge), tin (Sn); , Lead (Pb), Antimony (Sb), Bismuth (Bi), Zinc (Zn), Aluminum (Al), Titanium (Ti), Cobalt (Co), Nickel (Ni), Manganese (Mn), Cadmium (Cd) (d) sodium-containing alloys or intermetallic compounds of Si, Ge, Sn, Pb, Sb, Bi, Zn, Al, Ti, Co, Ni, Mn, Cd, and mixtures thereof; (e) sodium-containing oxides, carbides, nitrides of Si, Ge, Sn, Pb, Sb, Bi, Zn, Al, Fe, Ti, Co, Ni, Mn, Cd, and mixtures or composites thereof; , sulfides, phosphides, selenides, tellurides, or antimonides; (f) sodium salts; and (g) graphene sheets preloaded with sodium ions; and combinations thereof. material.

The electrolyte is water, an organic liquid, an ionic liquid (ionic salts with a melting temperature below 100° C., preferably below 25° C. at room temperature), or a mixture of an ionic liquid and an organic liquid in a ratio of 1/100 to 100/1. can include Organic liquids are preferred, but ionic liquids are preferred. The electrolyte typically and preferably has a high solute concentration (concentration of lithium/sodium salts) such that the solute becomes saturated or supersaturated in the resulting electrode (anode or cathode). Such electrolytes are substantially quasi-solid electrolytes that behave like deformable or conformable solids. This new class of electrolytes is fundamentally different from liquid electrolytes, polymer gel electrolytes, or solid electrolytes.

In one preferred embodiment, the thickness of the quasi-solid electrode is between 200 μm and 1 cm, preferably between 300 μm and 0.5 cm (5 mm), more preferably between 400 μm and 3 mm, most preferably between 500 μm and 2.5 mm (2,500 μm). . When the active material is an anode active material, the anode active material has a mass loading of 25 mg/cm ² or more (preferably 30 mg/cm ² or more, more preferably 35 mg/cm ² or more) and/or the entire battery cell accounts for at least 25% (preferably at least 30%, more preferably at least 35%) by weight or volume of When the active material is a cathode active material, the cathode active material preferably has a mass of 20 mg/cm ² or more (preferably 25 mg/cm ² or more, more preferably 30 mg/cm ² or more, most preferably 40 mg/cm ² or more). Have the load in the cathode and/or occupy at least 45% (preferably at least 50%, more preferably at least 55%) of the weight or volume of the entire battery cell.

The above requirements for electrode thickness, area mass loading of anode active material or mass fraction based on the entire battery cell, or area mass loading of cathode active material or mass fraction based on the entire battery cell, are conventional. This has not been possible with conventional lithium or sodium batteries using a slurry coating and drying process.

In some embodiments, the anode active material is pure graphene, graphene oxide, reduced graphene oxide, graphene fluoride, graphene chloride, graphene bromide, graphene iodide, graphene hydride, graphene nitride, boron doped. a prelithiated version of a graphene sheet selected from graphene, nitrogen-doped graphene, chemically functionalized graphene, physically or chemically activated or etched versions thereof, or combinations thereof . Surprisingly, without prelithiation, the resulting lithium battery cells do not exhibit adequate cycle life (ie, capacity declines rapidly).

In lithium metal batteries, the cathode active material has an electrode active material loading greater than 15 mg/cm ² (preferably greater than 25 mg/cm ² , more preferably greater than 35 mg/cm ² , most preferably greater than 50 mg/cm ² ). The structure and/or the electrodes have a thickness of 300 μm or more (preferably 400 μm or more, more preferably 500 μm or more, possibly 100 cm or more). There is no theoretical limit to the electrode thickness of the alkali metal battery according to the invention.

FIG. 1(A) shows an anode current collector, one or two anode active material layers (e.g. thin Si coating layers) coated on two major surfaces of the anode current collector, a porous separator and an electrolyte. 1 is a schematic diagram of a prior art lithium-ion battery cell consisting of , one or two cathode electrode layers (eg, sulfur layers), and a cathode current collector; FIG. FIG. 1B shows that the electrode layer consists of discrete particles of active material (e.g. graphite or tin oxide particles in the anode layer, or sulfur/carbon in the cathode layer) and a conductive additive (not shown). and a resin binder (not shown). FIG. 1(C) shows a quasi-solid anode (consisting of anode active material particles and conductive filaments directly mixed or dispersed in the electrolyte), a porous separator, and a quasi-solid cathode (mixed or dispersed directly in the electrolyte). 1 is a schematic diagram of a lithium-sulphur battery cell according to the present invention, comprising S-containing cathode active material particles and conductive filaments; FIG. In this embodiment, no resin binder is required. FIG. 1(D) shows an anode (comprising a lithium metal layer deposited on a Cu foil surface), a porous separator, a quasi-solid cathode (S-containing cathode active material particles mixed or dispersed directly in the electrolyte, and 1 is a schematic diagram of a lithium metal-sulphur battery cell according to the present invention comprising a conductive filament); FIG. In this embodiment, no resin binder is required. FIG. 2(A) is a schematic representation of a closely packed, highly ordered structure of a solid electrolyte. FIG. 2(B) is a schematic diagram of a totally amorphous liquid electrolyte having a large proportion of free volume through which cations (eg, Li ⁺ or Na ⁺ ) can readily pass. Figure 2(C) shows the disordered or amorphous phase of a quasi-solid electrolyte with solvent molecules separating salt species to form amorphous zones where free (unclustered) cations readily migrate. 1 is a schematic diagram of a structure; FIG. The lithium or sodium salts become saturated or supersaturated while remaining substantially amorphous. FIG. 3(A) is the Na ⁺ ion transference number of an electrolyte (eg, (NaTFSI salt) in (DOL+DME) solvent) versus the sodium salt molar ratio x. FIG. 3(B) is the Na ⁺ ion transference number of an electrolyte (eg, (NaTFSI salt) in (EMImTFSI+DOL) solvent) versus the sodium salt molar ratio x. FIG. 4 shows the results for producing exfoliated graphite, expanded graphite flakes (>100 nm thick), and graphene sheets (thickness <100 nm, more typically <10 nm, and can be as thin as 0.34 nm). 1 is a schematic diagram of a commonly used method; FIG. FIG. 5(A) is the electrical conductivity (penetration behavior) of the conductive filaments in the quasi-solid electrode plotted as a function of the volume fraction of the conductive filaments (carbon nanofibers). FIG. 5(B) is the electrical conductivity (penetration behavior) of the conductive filaments in the quasi-solid electrode plotted as a function of the volume fraction of the conductive filaments (reduced graphene oxide sheets). FIG. 6(A) is a Ragone plot (weight power density versus energy density) of a Li—S cell containing S/CB composite particles as cathode active materials and carbon nanofibers as conductive filaments. Three of the four data curves are for cells made according to one embodiment of the present invention and the remaining one is for cells made by conventional slurry coating (roll coating) of electrodes. FIG. 6(B) is the cycling behavior of a conventional Li—S cell and a Li—S cell containing a quasi-solid electrolyte and a quasi-solid cathode. FIG. 7(A) is a Ragone plot (weight power density versus energy density). Three of the four data curves are for cells made according to one embodiment of the present invention, and the remaining one is for cells made by conventional slurry coating (roll coating) of electrodes. FIG. 7(B) is the cycling behavior of a conventional Li—S cell and a Li—S cell containing a quasi-solid electrolyte and a quasi-solid cathode. FIG. 8 is a Ragone plot of a cell with a Si nanoparticle anode, lithium cobaltate (LiCoO ₂ ) cathode, and quasi-solid electrolytes (S1, S3) compared to conventional electrolytes. FIG. 9 is a Ragone plot of a sodium ion capacitor (SIC) with a quasi-solid electrolyte compared to a SIC with a conventional electrolyte.

The present invention is directed to lithium-sulphur or sodium-sulphur batteries exhibiting very high energy densities heretofore unachieved. The battery may be a primary battery, but is preferably a lithium ion sulfur battery, a lithium metal-sulfur secondary battery (for example lithium metal is used as the anode active material), a sodium ion sulfur battery or a sodium metal-sulfur battery. A secondary battery selected from sulfur batteries (eg, using sodium metal as the anode active material and carbon-supported sulfur as the cathode active material). This battery is based on a quasi-solid electrolyte comprising a lithium or sodium salt dissolved in water, an organic solvent, an ionic liquid, or a mixture of organic and ionic liquids. Preferably, the electrolyte contains a high concentration of solute (lithium salt or sodium salt) (hence the term "deformable quasi-solid electrode"). The electrolyte is neither a liquid electrolyte nor a solid electrolyte. The shape of the lithium battery can be cylindrical, square, button-like, etc., and can be special or irregular. The present invention is not limited to any battery shape and configuration.

As shown in FIG. 1(A), prior art lithium or sodium battery cells, such as Li—S cells or room temperature Na—S cells, typically include an anode current collector (eg, Cu foil) , an anode electrode or anode active material layer (e.g., a prelithiated Si coating deposited on one or both sides of a Li metal foil, sodium foil, or Cu foil), a porous separator and/or electrolyte component, a cathode electrode or consists of a cathode active material layer (or two cathode active material layers coated on both sides of an Al foil), as well as a cathode current collector (eg Al foil).

In the more commonly used prior art cell construction (FIG. 1(B)), the anode layer consists of anode active material (e.g. graphite, hard carbon, or Si), conductive additive (e.g. carbon black particles), ), and particles of a resin binder (eg SBR or PVDF). The cathode layer comprises particles of cathode active material (e.g. LFP particles in Li-ion cells, and lithium polysulfide/carbon composite particles in Li-S cells), conductive additives (e.g. carbon black particles), and resin binders (e.g. PVDF ). Both the anode and cathode layers are typically up to 100-200 μm thick, and are likely to produce a sufficient amount of current per unit electrode area. This thickness range is considered an industry accepted constraint with which battery designers routinely work. This thickness limitation is due to several reasons: (a) existing battery electrode coating machines are not equipped to coat very thin or very thick electrode layers; (b) thinner layers are preferred given the reduced lithium-ion diffusion path length; (c) thicker electrodes are prone to delamination or cracking during drying or handling after roll coating; and (d) minimum overhead weight and maximum lithium storage capacity, and therefore maximum energy density ( In order to obtain the Wk/kg or Wh/L of the cell, all non-active material layers (eg, current collectors and separators) within the battery cell must be kept to a minimum.

In a less commonly used cell configuration, the anode active material (e.g., Si coating) or cathode active material is deposited on a current collector such as copper or Al foil, as shown in FIG. It is deposited directly in the form of a thin film. However, such thin film structures with very small thickness dimensions (typically much less than 500 nm, and often less than 100 nm if desired) do not allow for the same electrode or current collector surface area. (assuming ) that only a small amount of active material can be incorporated into the electrode, reducing the total lithium storage capacity and reducing the lithium storage capacity per unit electrode surface area. Such thin films should be less than 100 nm thick in order to be more resistant to cycling-induced cracking (for the anode) or to facilitate full utilization of the cathode active material. Such constraints further reduce the total lithium storage capacity and the lithium storage capacity per unit electrode surface area. Such thin film batteries have a very limited range of applications.

On the anode side, Si layers thicker than 100 nm have been found to be less crack resistant during charge-discharge cycling of the battery. The Si layer is fractured in just a few cycles. On the cathode side, a sputtered layer of lithium metal oxide thicker than 100 nm does not allow the lithium ions to fully penetrate and reach the entire cathode layer, resulting in low cathode active material utilization. Desirable electrode thickness is at least 100 μm and individual active material coatings or particles desirably have dimensions less than 100 nm. Therefore, these thin film electrodes (with thickness <100 nm) deposited directly on the current collector are three orders of magnitude short of the required thickness. As a further problem, not all cathode active materials are conductive to both electrons and lithium ions. A large layer thickness implies a very high internal resistance and a low active material utilization. Sodium batteries have similar problems.

That is, there are several conflicting factors that must be considered simultaneously in the design and selection of cathode or anode active materials in terms of material type, size, electrode layer thickness, and active material mass loading. So far, there have been no effective solutions provided by any prior art teachings to these often-conflicting problems. As disclosed herein, the inventors have puzzled battery designers and also electrochemists for over 30 years by developing novel methods of manufacturing lithium or sodium batteries. solved these problems.

Prior art lithium battery cells are typically manufactured by a method comprising the following steps: (a) the first step is to prepare an anode active material (e.g. Si nanoparticles or mesocarbon microbeads, MCMB); , conductive filler (eg graphite flakes), and resin binder (eg PVDF) particles in a solvent (eg NMP) to form an anode slurry. Separately, particles of cathode active material (e.g., LFP particles), conductive filler (e.g., acetylene black), and resin binder (e.g., PVDF) are mixed and dispersed in a solvent (e.g., NMP). to form a cathode slurry. (b) the second step is to coat one or both major surfaces of the anode current collector (e.g. Cu foil) with the anode slurry and dry the coated layer by evaporating the solvent (e.g. NMP); to form a dry anode electrode coated on Cu foil. Similarly, the cathode slurry is coated and dried to form a dry cathode electrode coated on Al foil. In practical manufacturing situations, slurry coating is usually done in a roll-to-roll manner; (c) the third step is to laminate the anode/Cu foil sheet, porous separator layer and cathode/Al foil sheet together , to form a 3- or 5-layer assembly, which is cut or slit to the desired size and laminated to form a rectangular structure (as an example shape) or rolled into a cylindrical cellular structure. including doing (d) The rectangular or cylindrical laminated structure is then encased in an aluminum plastic laminated envelope or steel casing. (e) then injecting a liquid electrolyte into the laminate structure to fabricate a lithium battery cell;

There are several significant problems associated with the method and resulting lithium battery cells.
1) It is very difficult to manufacture electrode layers (anode or cathode layers) thicker than 200 μm. There are several reasons. A 100-200 μm thick electrode typically requires a heating zone of 30-50 meters in length in a slurry coating facility, which is too time consuming, too energy consuming and cost effective. do not have. For some electrode active materials, such as metal oxide particles, it has not been possible to continuously produce electrodes with good structural integrity thicker than 100 μm in a practical manufacturing environment. The resulting electrodes are very fragile and brittle. Thicker electrodes are more prone to delamination and cracking.
2) In the conventional method as shown in FIG. 1(A), the actual mass loading of the electrodes and the apparent density for the active material are too low to achieve gravimetric energy densities above 200 Wh/kg. Mostly, even for relatively large graphite particles, the anode active material mass loading (area density) of the electrode is well below 25 mg/cm ² and the apparent volume or tap density of the active material is typically 1.2 g. / ^cm3 . The cathode active material mass loading (area density) of the electrode is substantially lower than 45 mg/cm ² for inorganic materials based on lithium metal oxides and substantially lower than 15 mg/cm ² for organic or polymeric materials. . In addition, there are numerous other non-active materials (eg, conductive additives and resin binders) that add additional weight and volume to the electrodes without contributing to battery capacity. These low areal densities and low volume densities result in relatively low gravimetric and low volumetric energy densities.
3) The conventional method requires the electrode active materials (anode active material and cathode active material) to be dispersed and slurried in a liquid solvent (e.g., NMP), and the liquid solvent is applied after coating the current collector surface. After removal, the electrode layer must be dried. After the anode and cathode layers are laminated together with a separator layer and packaged in a housing to form a battery cell, a liquid electrolyte is injected into the cell. In practice, the two electrodes are wetted, then the electrodes are dried and finally wetted again. Such a dry-wet-dry-wet process is not a good process at all.
4) Current lithium-ion batteries still suffer from relatively low gravimetric energy densities and low volumetric energy densities. Commercially available lithium-ion batteries exhibit gravimetric energy densities of about 150-220 Wh/kg and volumetric energy densities of 450-600 Wh/L.

In the literature, energy densities for practical battery cells or devices cannot be directly derived from energy density data reported based on active material weight alone or electrode weight. "Overhead weight", ie the weight of other device components (binders, conductive additives, current collectors, separators, electrolytes, and packaging) must also be taken into account. In conventional manufacturing methods, the weight ratio of anode active material (e.g. graphite or carbon) in lithium ion batteries is typically 12%-17% and the weight ratio of cathode active material is 20%-35% ( _LiMn2 for inorganics such as O ₄ ) or 7-15% (for organic or polymeric cathode materials).

The present invention provides lithium-sulfur or room-temperature sodium-sulfur battery cells with large electrode thickness, high active material mass loading, low overhead weight and volume, high capacity, and high energy density. In some embodiments, the present invention provides: (a) about 30% to about 95% by volume of a cathode active material (sulfur, metal-sulfur compounds, sulfur-carbon composites, sulfur-graphene composites, sulfur-graphite composites; , an organic sulfur compound, a sulfur-polymer composite, or a combination thereof); and about 5% to about 40% by volume of a first and about 0.01 vol ^. (b) an anode (either a conventional anode or a (c) an ion-conducting membrane or porous separator disposed between an anode and a quasi-solid cathode; the quasi-solid cathode having a thickness of 200 μm or more. provide cells. The quasi-solid cathode is preferably 10 mg/cm ² or more, preferably 15 mg/cm ² or more, more preferably 25 mg/cm ^{2 or} more, more preferably 35 mg/cm ² or more, even more preferably 45 mg/cm 2 or more, and most preferably 10 mg/cm ² or more. It preferably has a cathode active material mass loading greater than 65 mg/cm ² .

In this cell, the anode also comprises from about 30% to about 95% by volume of anode active material, from about 5% to about 40% by volume of a second electrolyte comprising an alkali salt dissolved in a solvent, and from about 0% by volume. .01% to about 30% by volume of a conductive additive and no quasi-solid polymer, wherein the quasi-solid electrode has an electrical conductivity of about 10 ⁻⁶ S/cm to about 300 S/cm. The conductive additives, including conductive filaments, form a 3D network of electron-conducting pathways, such that the quasi-solid anode has a thickness of 200 μm or more. The quasi-solid anode is preferably 10 mg/cm ² or more, preferably 15 mg/cm ² or more, more preferably 25 mg/cm ^{2 or} more, more preferably 35 mg/cm ² or more, still more preferably 45 mg/cm 2 or more, and most preferably 10 mg/cm ² or more. It preferably has an anode active material mass loading greater than 65 mg/cm ² . The first electrolyte can be the same or different in composition and structure from the second electrolyte.

In some embodiments, the alkali metal battery includes a quasi-solid anode, but a conventional cathode. Preferably, however, the cathode is also a quasi-solid electrode.

The present invention also provides a method of manufacturing an alkali metal battery. In one embodiment, the method:
(a) an amount of active material (anode active material or cathode active material) and an amount of quasi-solid electrolyte (preferably comprising an alkali metal salt dissolved in a solvent having a salt concentration of 2.5M to 14M); and a conductive additive to form a deformable and electrically conductive electrode material, wherein the conductive additive comprising conductive filaments forms a 3D network of electron conducting pathways; These conductive filaments, such as carbon nanotubes and graphene sheets, are irregularly aggregated filament assemblies before being mixed with particles of active material and electrolyte. It involves dispersing these conductive filaments in a viscous electrolyte, which is discussed further in a later section.)
(b) in the step of forming a quasi-solid electrode from the above electrode material, the forming step is such that the electrode is 10 ⁻⁶ S/cm or more (preferably 10 ⁻⁵ S/cm or more, more preferably 10 ⁻⁴ S/cm above, more preferably 10 ⁻³ S/cm or more, still more preferably typically 10 ⁻² S/cm or more, still more typically preferably 10 ⁻¹ S/cm or more, still more typically preferably deforming the electrode material into the electrode shape without disrupting the 3D network of electronic conduction pathways so as to maintain an electrical conductivity of greater than or equal to 1 S/cm; up to 300 S/cm was observed; ;
(c) forming a second electrode (the second electrode may be a quasi-solid electrode or a conventional electrode);
(d) forming an alkali metal cell by combining the quasi-solid electrode and a second electrode such that an ion-conducting separator is disposed between the two electrodes;
including.

As shown in FIG. 1(C), one preferred embodiment of the present invention comprises a conductive quasi-solid anode 236, a conductive quasi-solid cathode 238 (including a sulfur-containing cathode active material), and an anode and a cathode. is an alkali ion sulfur cell with a porous separator 240 (or ion permeable membrane) that electronically separates the . These three components are typically encased in a protective housing (not shown) which typically includes an anode tab (terminal) connected to the anode, and a cathode tab (terminal) connected to the cathode. It has tabs (terminals). These tabs are for connecting to an external load (eg an electronic device powered by a battery). In this particular embodiment, the quasi-solid polymer anode 236 comprises an anode active material (e.g. particles of Li, Si, or hard carbon, not shown in FIG. 1(C)) and an electrolyte phase (typically contains a lithium or sodium salt dissolved in a solvent); also not shown in FIG. including) and including. Similarly, a quasi-solid cathode includes a sulfur-containing cathode active material, an electrolyte, and conductive additives (including conductive filaments) that form a 3D network 242 of electron-conducting pathways.

Another preferred embodiment of the present invention consists of a lithium or sodium metallization/foil 282 deposited/attached to a current collector 280 (e.g. Cu foil), as shown in Figure 1(D). A quasi-solid cathode 284 and a separator or ion-conducting membrane 282. The quasi-solid cathode 284 comprises a cathode active material 272 (e.g. porous carbon particles impregnated with S or lithium polysulfide, or composite particles comprising S supported on graphene sheets) and an electrolyte phase 274 (typically a lithium or sodium salt dissolved in a solvent) and a conductive additive phase (including conductive filaments) that forms a 3D network 270 of electronic conduction pathways.

The electrolyte is preferably a salt of 1.5M or greater, preferably greater than 2.5M, more preferably greater than 3.5M, even more preferably greater than 5M, even more preferably greater than 7M, even more preferably greater than 10M. It is a quasi-solid electrolyte containing a lithium or sodium salt dissolved in a solvent at a concentration. In some embodiments, the electrolyte is a quasi-solid electrolyte comprising a lithium or sodium salt dissolved in a liquid solvent at a salt concentration of 3.0M to 14M. The choice of lithium or sodium salt and solvent are discussed in detail in the following sections.

Both the quasi-solid anode and the quasi-solid cathode preferably have a thickness greater than 200 μm (preferably greater than 300 μm, more preferably greater than 400 μm, even more preferably greater than 500 μm, even more preferably greater than 800 μm, more preferably is greater than 1 mm, can be greater than 5 mm, can be greater than 1 cm, or can be thicker.There is no theoretical limit to the electrode thickness according to the present invention.In the cell according to the present invention, the anode active material is , typically comprising an electrode active material loading of 10 mg/cm ² or more (more typically preferably 20 mg/cm ² or more, more preferably 30 mg/cm ² or more) in the anode. 45 mg/cm ² or more (typically preferably greater than 50 mg/cm ² , more preferably greater than 60 mg/cm ² ) for inorganic materials as active materials (25 mg/cm ² for organic or polymeric cathode active materials). above) constitute the electrode active material mass load.

In such a configuration (FIGS. 1(C)-1(D)), the electrons constitute a 3D network of electron conduction pathways, with the ubiquitous conductivity across the quasi-solid electrode (anode or cathode). Only a short distance (eg, a few micrometers or less) movement is required before being collected by the filament. Additionally, all electrode active material particles are pre-dispersed in the electrolyte solvent (no wetting issues) and dry pockets commonly present in electrodes fabricated by conventional methods of wet coating, drying, packing, and electrolyte infusion. ceases to exist. Thus, the process or method according to the invention has a completely unexpected advantage over conventional battery cell manufacturing methods.

Prior to being mixed with the particles of active material and electrolyte, these conductive filaments (such as carbon nanotubes and graphene sheets), as supplied, are essentially aggregates of randomly aggregated filaments. A mixing procedure can involve dispersing these conductive filaments in a highly viscous solid electrolyte containing particles of the active material. This is not as mundane a task as you might think. Dispersion of nanomaterials (particularly nanofilament materials such as carbon nanotubes, carbon nanofibers, and graphene sheets) in highly fluid (non-viscous) liquids is well known to be difficult, leading to high load activity. This is even more so in highly viscous quasi-solids such as electrolytes containing materials such as solid particles such as Si nanoparticles for the anode and lithium cobaltate for the cathode. This problem is exacerbated in some preferred embodiments by the idea that the electrolyte itself is a quasi-solid electrolyte comprising a high concentration of lithium or sodium salts and a polymer in a solvent.

In some embodiments of the invention, the formation of the electrode layer can be achieved by using the following sequence of steps:
Sequence 1 (S1): First, a lithium or sodium salt (e.g. _LiBF4 ) and an ion-conducting polymer (e.g. PEO) are dissolved in a mixture of PC and DOL to have the desired total salt/polymer concentration. An electrolyte can be formed. Conductive filaments (eg, carbon nanofibers, reduced graphene oxide sheets, or CNTs) are then dispersed in this electrolyte to form a filament-electrolyte suspension. Mechanical shear can be used to facilitate the formation of uniform dispersions. (This filament-electrolyte suspension is very viscous even at salt concentrations as low as 1.0 M). Particles of cathode active material (eg, S/carbon composite particles) are then dispersed in the filament-electrolyte suspension to form a quasi-solid electrode material.

Sequence 2 (S2): First, a lithium or sodium salt is dissolved in a mixture of PC and DOL to form an electrolyte with the desired salt concentration. Particles of cathode active material are then dispersed in the electrolyte to form an active particle-electrolyte suspension. Mechanical shear can be used to facilitate the formation of uniform dispersions. A quasi-solid electrode material is then formed by dispersing the conductive filaments in the active particle-electrolyte suspension.

Order 3 (S3): This is one of the preferred orders. First, the desired amount of conductive filaments is dispersed in a liquid solvent mixture (eg PC+DOL) in which the lithium salt is not dissolved. Mechanical shear can be used to promote the formation of a uniform suspension of conductive filaments in the solvent. A lithium or sodium salt is then added to this suspension and dissolved in the solvent mixture of the suspension to form an electrolyte with the desired total salt/polymer concentration. Simultaneously or subsequently, the active material particles are dispersed in the electrolyte to form a deformable quasi-solid electrode material, which is dispersed in a quasi-solid electrolyte (neither a liquid electrolyte nor a solid electrolyte). It consists of active material particles and conductive filaments. In this quasi-solid electrode material, conductive filaments permeate to form a 3D network of electronic conduction pathways. This 3D conductive network is maintained when the electrode material is molded into a battery electrode.

In some preferred embodiments, the electrolyte exhibits a vapor pressure of less than 0.01 kPa or less than 0.6 (60%) of the vapor pressure of the solvent alone (when measured at 20° C.) and the first organic liquid Alkali metal salts high enough to exhibit a flash point at least 20° C. above the flash point of the solvent alone (in the absence of lithium salt), exhibit a flash point above 150° C., or exhibit no detectable flash point at all The electrolyte comprises an alkali metal salt (lithium salt and/or sodium salt) dissolved in an organic or ionic liquid solvent at a concentration.

Of most surprising and great scientific and technical importance is the fact that the flammability of volatile organic solvents is such that a sufficiently large amount of an alkali metal salt is added into this organic solvent and dissolved to form a solid or quasi-solid electrolyte. It is the discovery of the present inventors that if they are formed, they can be effectively suppressed. In general, such quasi-solid electrolytes are less than 0.01 kPa, often less than 0.001 kPa (when measured at 20°C), and less than 0.1 kPa, often less than 0.01 kPa (when measured at 100°C). (The vapor pressure of the corresponding neat solvent, in which no alkali metal salt is dissolved, is typically much higher). In many cases featuring quasi-solid electrolytes, gas molecules are actually too few to be detected.

One very important observation is the high solubility of alkali metal salts in otherwise highly volatile solvents (large molecular ratios or mole fractions of alkali metal salts, typically >0.2, (more typically >0.3, often >0.4, or even >0.5) significantly increases the amount of volatile solvent molecules that can escape into the gas phase at thermodynamic equilibrium conditions. can be reduced to In many cases, this effectively prevents the gas molecules of flammable solvents from flaming even at very high temperatures (eg using a torch). The flash point of the quasi-solid polymer electrolyte is typically at least 20 degrees (often >50 degrees or >100 degrees) higher than the flash point of the neat organic solvent alone. In most cases, either the flash point is above 150° C. or the flash point cannot be detected. This electrolyte is completely non-flammable. Furthermore, any accidental flames do not last more than a few seconds. Considering that fire and explosion problems have been major obstacles to widespread acceptance of battery-powered electric vehicles, this is a very significant finding. This new technology could go a long way in facilitating the emergence of a vibrant EV industry.

ultra-high concentration battery electrolytes (having high molecular fractions, e.g., >0.2 or >0.3 alkali metal salts, or approximately >2.5M or 3.5M salt concentrations) for safety considerations; There are no previous studies reported on vapor pressure. This is just unexpected and of most technical and scientific importance.

The inventors propose that the presence of a 3D network of electron-conducting pathways constituted by conducting nanofilaments serves to further reduce the threshold concentration of alkali metal salts required to achieve critical vapor pressure suppression. I made another unexpected discovery.

One of the other surprising elements of the invention is that the inventors have used almost any kind of high concentration alkali metal salt to form a quasi-solid electrolyte suitable for use in rechargeable alkali metal batteries. of commonly used battery grade organic solvents. Expressed in more readily understandable terms, this concentration typically exceeds 2.5M (moles/liter), more typically preferably greater than 3.5M, and even more typically preferably greater than 5M. greater than, even more preferably greater than 7M and most preferably greater than 10M. At salt concentrations above 2.5 M, the electrolyte is no longer a liquid electrolyte, rather it is a quasi-solid electrolyte. In the field of lithium or sodium batteries, such high concentrations of alkali metal salts in the solvent have generally been considered impossible or undesirable. However, the inventors have found that these quasi-solid electrolytes are surprisingly good in both lithium and sodium batteries due to their markedly improved safety (nonflammability), improved energy density, and improved power density. It was found that it was a good electrolyte.

In addition to non-flammability and high alkali metal ion transference numbers as discussed above, there are several additional advantages associated with the use of quasi-solid electrolytes according to the present invention. As an example, quasi-solid electrolytes, at least when used in the anode, significantly enhance the cyclability and safety performance of rechargeable alkali metal-sulfur batteries by effectively suppressing dendrite growth, presumably for the following reasons: can be improved to:
1) It is generally accepted that dendrites begin to grow in non-aqueous liquid electrolytes when anions are depleted in the vicinity of the electrode where plating occurs. In ultra-high concentration electrolytes, there is a large amount of anions to maintain a balance between cations (Li ⁺ or Na ⁺ ) and anions near the metallic lithium or sodium anode.
2) In addition, the space charge caused by the depletion of anions is minimal and does not contribute to dendrite growth.
3) The presence of a 3D network of electron-conducting pathways constituted by conductive filaments creates a more uniform electric field in the anode, promoting more uniform deposition of lithium or sodium.
4) Furthermore, due to both the ultra-high Li or Na salt concentration and the high Li-ion or Na-ion transference numbers, the quasi-solid-state electrolyte provides a large amount of available lithium-ion or sodium-ion flux, The mass transfer rate of lithium or sodium ions to and from the lithium or sodium electrode is increased, thereby improving the deposition uniformity and dissolution of lithium or sodium during charge/discharge processes.
5) In addition, the high local viscosity caused by the high concentration increases the pressure from the electrolyte and inhibits dendrite growth, possibly resulting in a more uniform deposition on the anode surface. The high viscosity can also limit the convection of anions near the deposition area, promoting more uniform deposition of sodium ions. The same reasoning is applicable to lithium metal batteries.

These reasons, individually or in combination, are believed to be responsible for the lack of dendritic features observed in any of the many rechargeable alkali-metal-sulfur cells we have previously studied. Conceivable.

Furthermore, those skilled in the field of chemistry or materials science know that at such a high salt concentration the electrolyte should behave like a solid with very high viscosity, thus the electrolyte will have a high concentration of alkali metal ions inside. It was expected that it would not be suitable for rapid diffusion. As a result, those skilled in the art know that alkali metal batteries containing such solid electrolytes do not and cannot exhibit high capacities at high charge-discharge rates or under high current density conditions (i.e., batteries should have a high rate capability). Contrary to these expectations by those of ordinary or even very high skill in the art, all alkali metal-sulfur cells containing such quasi-solid electrolytes show high energy densities with long cycle lives. and high power density are obtained. It is believed that the quasi-solid electrolyte disclosed herein according to the present invention facilitates the migration of alkali metal ions. This surprising observation is likely due to two main factors: one related to the internal structure of the electrolyte and the other related to the high Na ⁺ or Li ⁺ ion transference number (TN).

Without wishing to be bound by theory, the internal structure of three disparate types of electrolytes can be visualized by referring to FIGS. 2(A)-3(C). FIG. 2(A) schematically shows the closely packed and highly ordered structure of a typical solid electrolyte, with little free volume for alkali metal ion diffusion. Movement of any ion in such a crystal structure is very difficult, resulting in very low diffusion coefficients (10 ⁻¹⁶ to 10 ⁻¹² cm ² /s) and very low ionic conductivities (typically 10 ⁻⁷ S/cm to 10 ⁻⁴ S/cm) are obtained. In contrast, as shown schematically in FIG. 2(B), the internal structure of the liquid electrolyte is totally amorphous with a high proportion of free volume through which cations ( or Li ⁺ or Na ⁺ ) can easily migrate, resulting in high diffusion coefficients (10 ⁻⁸ to 10 ⁻⁶ cm ² /sec) and high ionic conductivities (typically 10 ⁻³ S/ cm to 10 ⁻² S/cm) can be obtained. However, liquid electrolytes containing low concentrations of alkali metal salts are flammable and susceptible to dendrite formation, creating fire and explosion hazards. FIG. 2(C) shows a disordered or amorphous quasi-solid electrolyte with solvent molecules separating salt species to form amorphous zones where free (unclustered) cations readily migrate. is shown schematically. Such structures are suitable for achieving high ionic conductivity values (typically 10 ⁻⁴ S/cm to 8×10 ⁻³ S/cm) and still remain non-flammable. Relatively few solvent molecules are present, and these molecules are retained (prevented from evaporating) by the preponderance of salt species, polymer chain segments, and a network of conductive filaments.

In Li—S or Na—S cells according to the present invention, the anode is typically a metal foil, thin film, or thin coating (< 50 μm thickness) in the form of Li metal or Na metal.

In some embodiments, the anode active material is pure graphene, graphene oxide, reduced graphene oxide, graphene fluoride, graphene chloride, graphene bromide, graphene iodide, graphene hydride, graphene nitride, graphene chemically functionalized. , or a combination thereof. Starting graphene materials for making any one of the above graphene materials include natural graphite, synthetic graphite, mesophase carbon, mesophase pitch, mesocarbon microbeads, soft carbon, hard carbon, coke, carbon fiber, carbon nanofiber , carbon nanotubes, or combinations thereof. Graphene materials are also good conductive additives for both anode and cathode active materials in lithium batteries.

Assuming that interplanar van der Waals forces can be overcome, the constituent graphene planes of graphite crystals in natural or artificial graphite particles can be exfoliated and extracted or isolated to form individual graphenes of hexagonal carbon atoms. Sheets can be obtained and these sheets are a single atom thick. An isolated individual graphene plane of carbon atoms is commonly referred to as monolayer graphene. A stack of multiple graphene planes joined by van der Waals forces with a graphene plane spacing of about 0.3354 nm in the thickness direction is commonly referred to as multi-layer graphene. Multilayer graphene platelets have up to 300 graphene planes (thickness less than 100 nm), but more typically up to 30 graphene planes (thickness less than 10 nm), even more typically up to 20 layers. It has graphene planes (thickness less than 7 nm), and most typically up to 10 layers of graphene planes (commonly called few-layer graphene in the scientific community). Single-layer graphene and multi-layer graphene sheets are collectively referred to as “nanographene platelets” (NGP). Graphene sheets/platelets (collectively NGP) are a new class of carbon nanomaterials (2D nanocarbons) distinct from 0D fullerenes, 1D CNTs or CNFs, and 3D graphite. For the purposes of defining the claims, and as commonly understood in the art, graphene materials (isolated graphene sheets) are not carbon nanotubes (CNT) or carbon nanofibers (CNF). ).

In one method, graphene material is obtained by intercalating natural graphite particles with strong acids and/or oxidizing agents to obtain graphite intercalation compound (GIC) or graphite oxide (GO), as shown in FIG. obtained by The presence of chemical species or functional groups in the interstitial space between graphene planes in GIC or GO serves to increase the graphene spacing (d ₀₀₂ ; determined by X-ray diffraction), thereby This greatly reduces the van der Waals forces that hold the graphene planes together along the c-axis direction. GIC or GO is most often produced by soaking natural graphite powder in a mixture of sulfuric acid, nitric acid (an oxidizing agent), and another oxidizing agent such as potassium permanganate or sodium perchlorate. . When an oxidizing agent is present during the intercalation procedure, the resulting GIC is actually a type of graphite oxide (GO) particles. The GIC or GO is then repeatedly washed and rinsed in water to remove excess acid, resulting in a graphite oxide suspension or dispersion that is dispersed in water in discrete, visually distinguishable containing graphite oxide particles. To produce graphene material, one of two processing routes can be followed after this rinsing step, briefly described below.

Route 1 involves removing water from the suspension to obtain "expanded graphite" which is essentially a mass of dry GIC or dry graphite oxide particles. When exfoliated graphite is exposed to temperatures typically in the range of 800-1,050° C. for about 30 seconds to 2 minutes, the GIC undergoes a rapid volume expansion of 30-300 times to form "graphite worms." . Each graphite worm (104) is a collection of flakes of graphite that have been exfoliated, but are largely unseparated and remain interconnected.

In Route 1A, these graphite worms (exfoliated graphite or "network of interconnected/unseparated graphite flakes") are recompressed to typically 0.1 mm (100 μm) to 0.5 mm Flexible graphite sheets or foils with thicknesses in the range (500 μm) can be obtained. Alternatively, graphite worms are simply extruded using a low-intensity air mill or shears for the purpose of producing so-called "expanded graphite flakes", which mainly contain graphite flakes or platelets thicker than 100 nm (thus not nanomaterials by definition). You can also choose to shred.

In Route 1B, exfoliation, as disclosed in commonly-owned US patent application Ser. The resulting graphite is subjected to high-intensity mechanical shear (e.g., using an ultrasonic device, high-shear mixer, high-intensity air jet mill, or high-energy ball mill) to separate single- and multi-layer graphene sheets ( collectively referred to as NGP). Single-layer graphene can be as thin as 0.34 nm, while multi-layer graphene can have a thickness of up to 100 nm, but more typically less than 10 nm (commonly referred to as few-layer graphene). Multiple graphene sheets or platelets may be formed as a sheet of NGP paper using a papermaking process. This NGP paper is an example of a porous graphene structured layer utilized in the method according to the present invention.

Route 2 involves sonicating a graphite oxide suspension (eg, graphite oxide particles dispersed in water) for the purpose of separating/isolating individual graphene oxide sheets from the graphite oxide particles. This shows that the separation of the graphene planes has been increased from 0.3354 nm in natural graphite to 0.6-1.1 nm in highly oxidized graphite oxide, a van der Waals separation that holds adjacent planes together. It is based on the view that it greatly weakens power. The ultrasonic power may be sufficient to further separate the graphene plane sheets to form fully separated, isolated, or discrete graphene oxide (GO) sheets. These graphene oxide sheets can then be chemically or thermally reduced to yield “reduced graphene oxide” (RGO), which typically contains 0.001 wt % to 10 wt %, More typically it has an oxygen content of 0.01% to 5% by weight, and most typically and preferably contains less than 2% by weight oxygen.

For the purposes of defining the claims of this application, NGP or graphene materials include single and multilayer (typically less than 10 layers) pure graphene, graphene oxide, reduced graphene oxide (RGO), graphene fluoride , graphene chloride, graphene bromide, graphene iodide, graphene hydride, graphene nitride, graphene chemically functionalized, discrete sheets/platelets of doped (eg, B or N doped) graphene. Pure graphene has essentially 0% oxygen. RGO typically has an oxygen content of 0.001% to 5% by weight. Graphene oxide (including RGO) can have between 0.001% and 50% oxygen by weight. Except for pure graphene, all graphene materials contain 0.001% to 50% by weight of non-carbon elements (eg, O, H, N, B, F, Cl, Br, I, etc.). These materials are referred to herein as impure graphene materials.

Pure graphene is produced as smaller, discrete graphene sheets (typically 0.3 μm to 10 μm) by direct sonication (also known as liquid phase exfoliation or generation) or supercritical fluid exfoliation of graphite particles. can do. These methods are well known in the art.

Graphene oxide (GO) is added to the starting graphite material in a reaction vessel at a desired temperature for a period of time (typically 0.5-96 hours depending on the nature of the starting material and the type of oxidant used). can be obtained by immersing a powder or filament of (eg, natural graphite powder) in an oxidizing liquid medium (eg, a mixture of sulfuric acid, nitric acid, and potassium permanganate). As described above, the resulting graphite oxide particles can then be subjected to thermal exfoliation or ultrasonically induced exfoliation to produce isolated GO sheets. These GO sheets can then be transformed into various graphene materials by replacing the OH groups with other chemical groups (such as Br and _NH2 ).

Fluorinated graphene or graphene fluoride is used herein as an example of a group of halogenated graphene materials. There are two different approaches that have been taken to produce fluorinated graphene. (1) Fluorination of pre-synthesized graphene: This approach requires treating graphene prepared by mechanical exfoliation or CVD growth with a fluorinating agent such as _XeF2 or F-based plasma. (2) Exfoliation of multilayer graphite fluoride: both mechanical exfoliation and liquid phase exfoliation of graphite fluoride can be easily achieved.

Graphite intercalation compounds (GICs) _CxF (2 ≤ x ≤ 24) are produced at low temperatures, whereas the interaction of _F2 with graphite at high temperatures leads to covalent graphite fluoride (CF) _n or ( _C2F ) _n . In (CF) _n , the carbon atoms are sp3-hybridized and thus the fluorocarbon layers are corrugated and consist of trans-linked cyclohexane chair conformations. In (C ₂ F) _n , only half of the C atoms are fluorinated and any pair of adjacent carbon sheets are linked by C—C covalent bonds. Systematic studies on fluorination reactions show that the obtained F/C ratio depends on the fluorination temperature, the partial pressure of fluorine in the fluorination gas, and the physical properties of the graphite precursor, such as the degree of graphitization, grain size, and ratio. It was shown to strongly depend on the surface area. In addition to fluorine ( _F2 ), other fluorinating agents can also be used _, but most of the available literature involves fluorination with F2 gas, sometimes in the presence of fluoride.

In order to exfoliate the layered precursor material into individual layers or several layers, it is necessary to overcome the attractive forces between adjacent layers and further stabilize the layers. This may be achieved by covalent modification of the graphene surface with functional groups or by non-covalent modification using specific solvents, surfactants, polymers, or donor-acceptor aromatic molecules. The process of liquid phase exfoliation involves sonication of graphite fluoride in a liquid medium.

Nitridation of graphene can be performed by exposing graphene materials, such as graphene oxide, to ammonia at elevated temperatures (200-400° C.). Nitrogenated graphene can also be produced at lower temperatures by hydrothermal methods. This is done, for example, by sealing the GO and ammonia in an autoclave and then increasing the temperature to 150-250°C. Other methods to synthesize nitrogen-doped graphene include nitrogen plasma treatment on graphene, arc discharge between graphite electrodes in the presence of ammonia, ammonolysis of graphene oxide under CVD conditions, and graphene oxide at various temperatures. and hydrothermal treatment of urea.

There is no limit to the types of anode active materials that can be used in the practice of the invention. Preferably ^, in a lithium-sulphur cell according to the invention, when the battery is charged, less than 1.0 ^{volts (} preferably At high electrochemical potentials (below 0.7 volts), the anode active material absorbs lithium ions. In one preferred embodiment, the anode active material for a lithium battery is: (a) particles of lithium metal or lithium metal alloy; (b) natural graphite particles, synthetic graphite particles, mesocarbon microbeads (MCMB), carbon particles (soft carbon and hard carbon, etc.), needle coke, carbon nanotubes, carbon nanofibers, carbon fibers, and graphite fibers; (c) silicon (Si), germanium (Ge), tin (Sn), lead (Pb), antimony (Sb) , bismuth (Bi), zinc (Zn), aluminum (Al), nickel (Ni), cobalt (Co), manganese (Mn), titanium (Ti), iron (Fe), and cadmium (Cd); (d) (e ) oxides, carbides, nitrides, sulfides, phosphides, selenides, and tellurides of Si, Ge, Sn, Pb, Sb, Bi, Zn, Al, Fe, Ni, Co, Ti, Mn, or Cd and mixtures or composites thereof; (f) prelithiated versions thereof; (g) prelithiated graphene sheets; and combinations thereof.

In some embodiments, the alkali metal-sulfur cell is a sodium ion sulfur cell and the active materials include petroleum coke, carbon black, amorphous carbon, activated carbon, hard carbon (difficult to graphitize carbon), soft carbon (easily graphitizable _carbon ), template carbon, _hollow carbon nanowires, hollow carbon spheres _, titanates, _NaTi2 ( _PO4 ) ₃ , _{Na2Ti3O7 , Na2C8H4O4 , Na2TP} , Na _x TiO ₂ (x=0.2-1.0), Na ₂ C ₈ H ₄ O ₄ , carboxylate-based materials, C ₈ H ₄ Na ₂ O ₄ , C ₈ H ₆ O ₄ , C ₈ H ₅ NaO _{4 , C8Na2F4O4 , C10H2Na4O8 , C14H4O6 , C14H4Na4O8 , or combinations thereof . _ _} an anode active material comprising:

In some embodiments, the alkali metal-sulfur cell is a sodium metal-sulfur cell or a sodium ion sulfur cell, and the active material is: (a) particles of sodium metal or sodium metal alloys; (b) natural graphite particles, artificial graphite particles. , mesocarbon microbeads (MCMB), carbon particles, needle coke, carbon nanotubes, carbon nanofibers, carbon fibers, and graphite fibers; (c) sodium-doped silicon (Si), germanium (Ge), tin (Sn) ), lead (Pb), antimony (Sb), bismuth (Bi), zinc (Zn), aluminum (Al), titanium (Ti), cobalt (Co), nickel (Ni), manganese (Mn), cadmium (Cd ), and mixtures thereof; (d) sodium-containing alloys or intermetallic compounds of Si, Ge, Sn, Pb, Sb, Bi, Zn, Al, Ti, Co, Ni, Mn, Cd, and mixtures thereof; (e) sodium-containing oxides, carbides, nitrides of Si, Ge, Sn, Pb, Sb, Bi, Zn, Al, Fe, Ti, Co, Ni, Mn, Cd, and mixtures or composites thereof; (f) sodium salts; and (g) graphene sheets preloaded with sodium ions; and combinations thereof. Active material.

A wide variety of sulfur-based cathode active materials can be used to implement a lithium-sulfur or sodium-sulfur cell according to the present invention. Such sulfur-containing cathode active materials include sulfur, metal-sulfur compounds (such as lithium polysulfide), sulfur-carbon composites (such as carbon black-S composites made by ball milling, or porous carbon impregnated with S). particles), sulfur-graphene composites, sulfur-graphite composites, organic sulfur compounds, sulfur-polymer composites, or combinations thereof.

In some embodiments, the cathode active material can be selected from sulfur or sulfur compounds supported by or bound to functionalized or nanostructured materials. The functional or nanostructured material is (a) soft carbon, hard carbon, polymeric carbon or carbonized resin, mesophase carbon, coke, carbonized pitch, carbon black, activated carbon, nanocellular carbon foam, or partial graphite. (b) nanographene platelets selected from single-walled graphene sheets or multi-walled graphene platelets; (c) single-walled carbon nanotubes or multi-walled carbon nanotubes; carbon nanotubes selected from carbon nanotubes; (d) carbon nanofibers, nanowires, metal oxide nanowires or fibers, conducting polymer nanofibers, or combinations thereof; (e) carbonyl-containing organic or polymeric molecules; (f) carbonyls functional materials containing groups, carboxylic acid groups, or amine groups; and combinations thereof.

Functional or nanostructured materials include poly(2,5-dihydroxy-1,4-benzoquinone-3,6-methylene), Na _x C ₆ O ₆ (x=1-3), Na ₂ (C ₆ H ₂ O ₄ ), Na ₂ C ₈ H ₄ O ₄ (Na terephthalate), Na ₂ C ₆ H ₄ O ₄ (trans-trans-muconate Na), 3,4,9,10-perylenetetracarboxylic acid di anhydride (PTCDA) sulfide polymer, PTCDA, 1,4,5,8-naphthalene-tetracarboxylic dianhydride (NTCDA), benzene-1,2,4,5-tetracarboxylic dianhydride, 1,4 , 5,8-tetrahydroxyanthraquinones, tetrahydroxy-p-benzoquinones, and combinations thereof. Desirably the functional or nanostructured material has functional groups selected from -COOH, =O, _-NH2 , -OR, or -COOR, where R is a hydrocarbon group.

Single-layer or few-layer (up to 20 layers) non-graphene 2D nanomaterials can be fabricated by several methods as follows. Mechanical ablation, laser ablation (e.g., using laser pulses to ablate the TMD to a monolayer), liquid phase exfoliation, and synthesis of thin film techniques such as PVD (e.g., sputtering), vapor deposition, vapor phase epitaxy, liquid phase epitaxy, chemical vapor deposition epitaxy, molecular beam epitaxy (MBE), atomic layer epitaxy (ALE), and plasma versions thereof.

A wide variety of electrolytes can be used in the practice of the invention. Non-aqueous organic and/or ionic liquid electrolytes are most preferred. Non-aqueous electrolytes employed herein may be produced by dissolving an electrolyte salt in a non-aqueous solvent. Any known nonaqueous solvent that is employed as a solvent for lithium secondary batteries can be employed. A non-aqueous solvent (hereinafter referred to as a second (referred to as the solvent of ) can preferably be employed. The non-aqueous solvent is (a) stable to negative electrodes containing well-formed carbonaceous materials in a graphite structure, (b) effective in suppressing reduction or oxidative decomposition of the electrolyte, and ( c) It has the advantage of high electrical conductivity. A non-aqueous electrolyte composed only of ethylene carbonate (EC) has the advantage of being relatively stable against decomposition due to reduction by a graphitized carbonaceous material. However, the melting point of EC is relatively high at 39-40°C, and the viscosity of EC is relatively high, so the electrical conductivity of EC is low. Therefore, EC alone is used as an electrolyte for secondary batteries that operate below room temperature is inappropriate for A second solvent used in a mixture with EC serves to make the solvent mixture less viscous than EC alone, thereby increasing the ionic conductivity of the mixed solvent. Furthermore, the use of a second solvent having a donor number of 18 or less (the donor number of ethylene carbonate is 16.4) enables the ethylene carbonate to be easily and selectively solvated with lithium ions, thus sufficiently It is hypothesized that the reduction reaction of the second solvent with the carbonaceous material produced by graphitization of 1 is inhibited. Furthermore, when the number of donors in the second solvent is controlled to 18 or less, the oxidative decomposition potential to the lithium electrode can be easily increased to 4 V or more, thereby producing a high voltage lithium secondary battery. becomes possible.

Preferred second solvents are dimethyl carbonate (DMC), methyl ethyl carbonate (MEC), diethyl carbonate (DEC), ethyl propionate, methyl propionate, propylene carbonate (PC), γ-butyrolactone (γ-BL), acetonitrile (AN), ethyl acetate (EA), propyl formate (PF), methyl formate (MF), toluene, xylene, and methyl acetate (MA). These second solvents may be employed alone or in combination of two or more. More desirably, this second solvent should be selected from those having a donor number of 16.5 or less. The viscosity of this second solvent should preferably be no greater than 28 cps at 25°C.

The mixing ratio of the ethylene carbonate in the mixed solvent should preferably be 10-80% by volume. If the mixing ratio of ethylene carbonate is out of this range, the conductivity of the solvent may be lowered, or the solvent tends to decompose more easily, thereby deteriorating the charge-discharge efficiency. A more preferable mixing ratio of ethylene carbonate is 20 to 75% by volume. When the mixing ratio of ethylene carbonate in the non-aqueous solvent is increased to 20% by volume or more, the solvation effect of ethylene carbonate on lithium ions is promoted, and the effect of inhibiting solvent decomposition can be improved.

Examples of preferred mixed solvents are compositions comprising EC and MEC; compositions comprising EC, PC and MEC; compositions comprising EC, MEC and DEC; compositions comprising EC, MEC and DMC; , MEC, PC and DEC, and the volume ratio of MEC is controlled within the range of 30-80%. By selecting the volume ratio of MEC from the range of 30-80%, more preferably 40-70%, the conductivity of the solvent can be improved. For the purpose of suppressing the decomposition reaction of the solvent, the electrolyte with dissolved carbon dioxide can be employed, thereby effectively improving both the capacity and the cycle life of the battery. Electrolyte salts incorporated into the non-aqueous electrolyte include lithium perchlorate (LiClO ₄ ), lithium hexafluorophosphate (LiPF ₆ ), lithium borofluoride (LiBF ₄ ), lithium hexafluoroarsenate (LiAsF ₆ ), trifluoro -lithium methosulfonate (LiCF ₃ SO ₃ ), and lithium salts such as lithium bis-trifluoromethylsulfonylimide [LiN(CF ₃ SO ₂ ) ₂ ]. Among them, LiPF ₆ , LiBF ₄ and LiN(CF ₃ SO ₂ ) ₂ are preferred. The content of the electrolyte salt in the non-aqueous solvent is preferably 0.5-2.0 mol/l.

For sodium cells, the electrolyte (including non-flammable pseudo-solid electrolytes) is preferably sodium perchlorate ( _NaClO4 ), sodium hexafluorophosphate ( _NaPF6 ), sodium borofluoride ( _NaBF4 ), hexafluoroarsenide selected from sodium, sodium trifluoro-metasulfonate (NaCF ₃ SO ₃ ), sodium bistrifluoromethylsulfonylimide (NaN(CF ₃ SO ₂ ) ₂ ), ionic liquid salts, or combinations thereof It can contain sodium salts.

Ionic liquids are composed only of ions. Ionic liquids are salts with low melting temperatures that become molten or liquid when a desired temperature is exceeded. For example, a salt is considered an ionic liquid if its melting point is below 100°C. If the melting temperature is below room temperature (25° C.), the salt is called a room temperature ionic liquid (RTIL). IL salts are characterized by weak interactions in combination with large cations and charge-delocalized anions. This reduces the tendency to crystallize due to flexibility (anions) and asymmetry (cations).

A typical well-known ionic liquid is formed by combining the 1-ethyl-3-methylimidazolium (EMI) cation with the N,N-bis(trifluoromethane)sulfonamide (TFSI) anion. This combination results in a fluid with ionic conductivity comparable to many organic electrolyte solutions up to about 300-400° C., as well as low degradability and low vapor pressure. This suggests electrolytes that are generally less volatile and non-flammable and thus much safer for batteries.

Ionic liquids are basically composed of organic ions that undergo an essentially unlimited number of structural changes due to the ease of preparing a wide variety of components. Therefore, different types of salts can be used to design ionic liquids with desired properties for a given application. These include, inter alia, imidazolium, pyrrolidinium and quaternary ammonium salts as cations and bis(trifluoromethanesulfonyl)imide, bis(fluorosulfonyl)imide and hexafluorophosphate as anions. Based on their composition, ionic liquids basically fall into different classes, including aprotic, protic and zwitterionic forms, each suitable for specific applications.

Common cations of room temperature ionic liquids (RTILs) include, but are not limited to, tetraalkylammonium, di-, tri-, and tetra-alkylimidazolium, alkylpyridinium, dialkylpyrrolidinium, dialkylpiperidinium, tetra Alkylphosphonium, as well as trialkylsulfonium are mentioned. Common anions of RTIL include, but are not limited to, BF ₄ ⁻ , B(CN) ₄ ⁻ , CH ₃ BF ₃ ⁻ , CH2CHBF ₃ − , CF ₃ BF ₃ ^{− ,} C ₂ F ₅ BF ₃ ⁻ , n _-C3F7BF3- ^, _n ^- _C4F9BF3- ^, _PF6- ^, _CF3CO2- ^, _CF3SO3- ^, N _{( SO2CF3 ) 2- , N ( COCF3 )} (SO ₂ CF ₃ ) ⁻ , N(SO ₂ F) ₂ ⁻ , N(CN) ₂ ⁻ , C(CN) ₃ ⁻ , SCN ⁻ , SeCN ⁻ , CuCl ₂ ⁻ , AlCl ₄ ⁻ , F(HF) _{2 .3} ^- and the like. Relatively speaking, imidazolium or sulfonium based cations and AlCl ₄ ⁻ , BF ₄ ⁻ , CF ₃ CO ₂ ⁻ , CF ₃ SO ₃ ⁻ , NTf ₂ ⁻ , N(SO ₂ F) ₂ ⁻ , or F Combinations with complex halide anions such as (HF) _2.3 ^- lead to RTILs with good operational conductivity.

RTILs have high intrinsic ionic conductivity, high thermal stability, low volatility, low (substantially zero) vapor pressure, non-flammability, and the ability to remain liquid over a wide temperature range above and below room temperature. , high polarity, high viscosity, and a wide electrochemical window. These properties, with the exception of high viscosity, are desirable properties when using RTILs as electrolyte components (salts and/or solvents) in supercapacitors.

Below are provided several examples of several different types of anode active materials, sulfur-based cathode active materials, and ion-conducting polymers to illustrate the best mode of practicing the invention. These illustrative examples, as well as the rest of the specification and drawings, individually or in combination, are more than sufficient to enable those skilled in the art to practice the invention. However, these examples should not be construed as limiting the scope of the invention.

Example 4: Preparation of Graphene Oxide (GO) and Reduced Graphene Oxide (RGO) Nanosheets from Natural Graphite Powder Huadong Graphite Co.; (Qingdao, China) was used as the starting material. GO was obtained by following the well-known modified Hummers method. This method involved two oxidation stages. In a typical procedure, the first oxidation was achieved under the following conditions. 1100 mg of graphite was placed in a 1000 mL boiling flask. K ₂ S ₂ O ₈ , 20 g of P ₂ O ₅ and 400 mL of concentrated aqueous H ₂ SO ₄ (96%) were then added to the flask. The mixture was heated under reflux for 6 hours and then left at room temperature for 20 hours. The graphite oxide was filtered and rinsed with copious amounts of distilled water to neutral pH. At the end of this first oxidation, a wet cake material was recovered.

In the second oxidation process, the previously collected wet cake was placed in a _boiling flask containing 69 mL of concentrated aqueous _H2SO4 (96%). The flask was kept in an ice bath while 9 g of KMnO ₄ was added slowly. Care was taken to avoid overheating. The resulting mixture was stirred at 35° C. for 2 hours (sample color turned dark green) followed by the addition of 140 mL of water. After 15 minutes, the reaction was quenched by adding 420 mL of water and 15 mL of 30 wt % H ₂ O ₂ aqueous solution. The color of the sample at this stage turned bright yellow. The mixture was filtered and rinsed with 1:10 aqueous HCl to remove metal ions. Collected material was gently centrifuged at 2700 g and rinsed with deionized water. The final product was a wet cake containing 1.4 wt% GO as estimated from the dry extract. A liquid dispersion of GO platelets was then obtained by lightly sonicating the wet cake material diluted with deionized water.

Surfactant-stabilized RGO (RGO-BS) was obtained by diluting the wet cake with an aqueous surfactant solution instead of pure water. A commercial mixture of salts of sodium cholate (50 wt%) and sodium deoxycholate (50 wt%) provided by Sigma Aldrich was used. The weight fraction of surfactant was 0.5 wt%. This fraction was kept constant for all samples. Sonication was performed using a Branson Sonifier S-250A equipped with a 13 mm step distractor horn and a 3 mm tapered microtip operating at a frequency of 20 kHz. For example, 10 mL of an aqueous solution containing 0.1 wt % GO was sonicated for 10 minutes and then centrifuged at 2700 g for 30 minutes to remove undissolved large particles, aggregates, and impurities. Chemical reduction of GO obtained as described above was carried out to produce RGO by following a method comprising placing 10 mL of 0.1 wt % GO aqueous solution in a 50 mL boiling flask. To the surfactant-stabilized mixture was then added 10 μL of 35 wt % aqueous N ₂ H ₄ (hydrazine) and 70 mL of 28 wt % aqueous NH ₄ OH (ammonia). The solution was heated to 90° C. and refluxed for 1 hour. The pH value measured after the reaction was about 9. The color of the sample turned dark black during the reduction reaction.

Some lithium-sulphur cells according to the invention used RGO as a conductive additive in either or both the anode and cathode active materials. Prelithiated RGO (eg, RGO + lithium particles, or RGO pre-deposited with a lithium coating) was also used as the anode active material in selected lithium-sulfur cells.

For comparison, a slurry coating and drying procedure was performed to produce a conventional electrode. One anode and one cathode and a separator disposed between the two electrodes are then assembled into an Al-plastic laminated packaging envelope followed by injection of a liquid electrolyte to produce a conventional lithium A battery cell was formed.

Example 2 Preparation of Sheets of Pure Graphene (Essentially 0% Oxygen) The inventors have demonstrated high electrical and thermal conductivity by using sheets of pure graphene (e.g., non-oxidized, oxygen-free, non-halogenated, and halogen-free). We decided to investigate whether we could obtain a conductive additive with Prelithiated pure graphene was also used as the anode active material. Sheets of pure graphene were fabricated by using direct sonication or liquid phase fabrication methods.

In a typical procedure, 5 grams of graphite flakes, ground to a size of about 20 μm or less, were mixed with 1,000 mL of deionized water (containing 0.1 wt % dispersant, Zonyl® FSO from DuPont). to obtain a suspension. An ultrasonic energy level of 85 W (Branson S450 Ultrasonicator) was used for exfoliation, separation, and size reduction of the graphene sheets over a period of 15 minutes to 2 hours. The resulting graphene sheets are pure graphene that has never been oxidized, does not contain oxygen, and is relatively defect-free. Pure graphene is essentially free of non-carbon elements.

Pure graphene as a conductive additive is then added into the battery using both the procedure according to the invention of injecting the slurry into the pores of the foam and the conventional slurry coating, drying and lamination procedure. The sheet was assembled with the anode active material (or cathode active material in the cathode). Both lithium ion sulfur batteries and lithium metal-sulfur batteries were investigated.

Example 3 Preparation of Prelithiated Graphene Fluoride Sheets as Anode Active Materials for Lithium Ion Batteries Although we have used several methods to produce GFs, only one method is presented here as an example. Described in the specification. In one typical procedure, heavily exfoliated graphite (HEG) was prepared from the intercalate compound С ₂ F.xClF ₃ . HEG was further fluorinated by chlorine trifluoride vapor to obtain fluorinated heavily exfoliated graphite (FHEG). A pre-chilled Teflon reactor was charged with 20-30 mL of liquid pre-chilled ClF ₃ , the reactor was closed and cooled to liquid nitrogen temperature. Next, 1 g or less of HEG was placed in a container with holes for ClF ₃ gas to pass through and placed in the reactor. A grey-beige product with the general formula C ₂ F was formed in 7-10 days.

Subsequently, a small amount of FHEG (approximately 0.5 mg) was mixed with 20-30 mL of organic solvent (methanol and ethanol separately) and sonicated (280 W) for 30 min to form a homogeneous yellowish dispersion. formed. Upon removal of solvent, the dispersion became a brownish powder. Prelithiation was performed by mixing the graphene fluoride powder with surface-stabilized lithium powder in a liquid electrolyte.

Example 4: Some Examples of Preferred Salts, Solvents, and Polymers for Forming Pseudo-Solid Polymer Electrolytes Preferred sodium metal salts include: sodium perchlorate ( _NaClO4 ), sodium hexafluorophosphate ( _NaPF6 ) , sodium borofluoride (NaBF ₄ ), sodium hexafluoroarsenide, potassium hexafluoroarsenide, sodium trifluoro-metasulfonate (NaCF ₃ SO ₃ ), and sodium bistrifluoromethylsulfonylimide (NaN( CF ₃ SO ₂ ) ₂ ). A good selection of lithium salts that tend to dissolve well in the organic or ionic liquid solvent of choice are: lithium borofluoride (LiBF ₄ ), lithium trifluoro-metasulfonate. _{( LiCF3SO3} ), lithium bistrifluoromethylsulfonylimide (LiN _{( CF3SO2 ) 2} or _LITFSI ), lithium bis(oxalato)borate (LiBOB), lithium oxalyldifluoroborate ( _LiBF2C2O4 ) , and lithium bisperfluoroethy-sulfonylimide (LiBETI). One of the good electrolyte additives to promote stabilization of Li metal is _LiNO3 . A particularly useful ionic liquid-based lithium salt includes lithium bis(trifluoromethanesulfonyl)imide (LiTFSI).

In the case of aqueous electrolytes, the sodium or potassium salts are preferably _{Na2SO4 , K2SO4} , mixtures thereof, NaOH, KOH, NaCl, KCl, NaF, KF, NaBr, KBr, _NaI , KI, or is selected from a mixture of Salt concentrations used in this study ranged from 0.3 M to 3.0 M (0.5 M to 2.0 M in most cases).

Preferred organic liquid solvents include ethylene carbonate (EC), dimethyl carbonate (DMC), methyl ethyl carbonate (MEC), diethyl carbonate (DEC), propylene carbonate (PC), acetonitrile (AN), vinylene carbonate (VC), allyl ethyl carbonate (AEC), 1,3-dioxolane (DOL), 1,2-dimethoxyethane (DME), tetraethylene glycol dimethyl ether (TEGDME), poly(ethylene glycol) dimethyl ether (PEGDME), diethylene glycol dibutyl ether (DEGDBE), 2-ethoxyethyl ether (EEE), hydrofluoroethers (eg TPTP), sulfones, and sulfolane.

Preferred ionic liquid solvents can be selected from room temperature ionic liquids (RTIL) with cations selected from tetraalkylammonium, dialkylimidazolium, alkylpyridinium, dialkylpyrrolidinium, or dialkylpiperidinium. The counter anions are preferably BF ₄ ⁻ , B(CN) ₄ ⁻ , CF ₃ CO ₂ ⁻ , CF ₃ SO ₃ ⁻ , N(SO ₂ CF ₃ ) ₂ ⁻ , N(COCF ₃ )(SO ₂ CF ₃ ) ^- , or N(SO ₂ F) ₂ ^- . Particularly useful ionic liquid-based solvents include Nn-butyl-N-ethylpyrrolidinium bis(trifluoromethanesulfonyl)imide (BEPyTFSI), N-methyl-N-propylpiperidinium bis(trifluoro methylsulfonyl)imide (PP ₁₃ TFSI), and N,N-diethyl-N-methyl-N-(2-methoxyethyl)ammonium bis(trifluoromethylsulfonyl)imide.

Example 5: Vapor Pressures of Several Solvents with Different Sodium Salt Molecular Ratios and Corresponding Pseudo-Solid Electrolytes Sodium Borofluoride ( _NaBF4 ), Sodium Perchlorate ( _NaClO4 ), or Bis(trifluoromethanesulfonyl)imide Vapor pressure of several solvents (DOL, DME, PC, AN with or without ionic liquid co-solvent PP ₁₃ TFSI) before and after addition of sodium (sodium salt such as NaTFSI in a wide molecular ratio range) Vapor pressure drops at a very rapid rate for salinity above 2.3M and rapidly approaches a minimum or virtually zero for salinity above 3.0M. At vapor pressure, the gas phase of the electrolyte either cannot ignite or sustain a flame for more than 3 seconds after igniting.

Example 6 Flash Point and Vapor Pressure of Several Solvents and Corresponding Pseudo-Solid Electrolytes with 3.0 M Sodium or Lithium Salt Concentrations Flash points and vapor pressures with electrolytes are shown in Table 1 below. Note that according to OSHA (Occupational Safety & Health Administration) classification, any liquid with a flash point less than 38.7°C is flammable. However, in order to ensure safety, the inventors have determined that the We have designed a quasi-solid polymer electrolyte. The data in Table 1 show that addition of an alkali metal salt concentration of 3.0M is usually sufficient to meet these criteria (2.3M is sufficient in many cases). All of our quasi-solid electrolytes are not flammable.

Example 7: Alkali Metal Ion Transference Numbers in Several Electrolytes The Na ⁺ ion transference numbers of several electrolytes (e.g., (PEO+NaTFSI salt) in (EMImTFSI+DME) solvent) to lithium salt molecular ratios were investigated and representative results are shown in the figure. They are summarized in 3(A) to 3(B). In general, the Na ⁺ ion transference number in low salt electrolytes decreases as the concentration increases from x=0 to x=0.2-0.30. However, beyond a molecular ratio of x=0.2-0.30, the transference number increased with increasing salt concentration, indicating a fundamental change in the Na ⁺ ion transfer mechanism. A similar trend was observed for lithium ions.

When a Na ⁺ ion moves in a low-salt electrolyte (eg, x<0.2), the Na ⁺ ion can pull multiple solvate molecules with it. Coordinated movement of such clusters of charged species can be further hindered if fluid viscosity increases due to more salt dissolved in the solvent. In contrast, when very high concentrations of sodium salts with x > 0.2 are present, they otherwise cluster with sodium ions to form multi-ionic complex species, slowing their diffusion processes. The number of Na ⁺ ions can be much higher than the available solvate molecules. This high Na ⁺ ion concentration makes it possible to have more “free Na ⁺ ions” (unclustered), which gives a higher Na ⁺ transference number (and hence easier Na ⁺ migration). be done. The sodium ion transfer mechanism varies from a multi-ion complex dominated mechanism (with an overall larger hydrodynamic radius) to a single ion dominated mechanism with a large number of available free ^Na ions (smaller with hydrodynamic radius). This observation suggests that rapid migration of a sufficient number of Na ⁺ ions through or out of the quasi-solid electrolyte will facilitate their interaction or reaction with the cathode (during discharging) or the anode (during charging). It further shows that it can be utilized, thereby ensuring good rate capability of sodium secondary cells. Most notably, these very concentrated electrolytes are non-flammable and safe. Combining safety, easy sodium ion transport, and electrochemical performance characteristics has been a challenge in all types of sodium and lithium secondary batteries.

Example 8 Preparation of Sulfur/Carbon Black (S/CB) Composite Particles for Lithium Sulfur Battery Cathodes Sulfur powder and CB particles were mixed (70/30 ratio), ball milled for 2 hours, and S/CB Particles were obtained. In this example, graphene sheets (RGO) and carbon nanofibers (CNF) were used as conductive filaments in an electrode containing S/CB particles as the cathode active material and an electrolyte (comprising a lithium salt dissolved in an organic solvent). ) were included separately. The lithium salts used in this example included lithium borofluoride ( _LiBF4 ) and the organic solvents were PC, DOL, DEC, and mixtures thereof. This study included a wide range of conductive filament volume fractions from 0.1% to 30%. The following sequence of steps was used to form the electrode layers:

Sequence 1 (S1): _LiBF4 salt and PEO were first dissolved in a mixture of PC and DOL to form electrolytes with total salt/polymer concentrations of 1.0 M, 2.5 M, and 3.5 M, respectively. . (At concentrations above 2.3 M, the resulting electrolyte was no longer a liquid electrolyte. It actually behaved like a solid and is therefore called a ``pseudo-solid''.) Next, RGO or CNT filaments were placed in the electrolyte. to form a filament-electrolyte suspension. Mechanical shear was used to facilitate the formation of uniform dispersions. (This filament-electrolyte suspension was also very viscous even at a low salt concentration of 1.0M). The S/CB particles of the cathode active material were then dispersed in the filament-electrolyte suspension to form a quasi-solid electrode material.

Sequence 2 (S2): _LiBF4 salt was first dissolved in a mixture of PC and DOL to form electrolytes with salt concentrations of 1.0 M, 2.5 M, and 3.5 M, respectively. The S/CB particles of the cathode active material were then dispersed in the electrolyte to form an active particle-electrolyte suspension. Mechanical shear was used to facilitate the formation of uniform dispersions. (This active particle-electrolyte suspension was also very viscous even at a low salt concentration of 1.0M). RGO or CNT filaments were then dispersed in the active particle-electrolyte suspension to form a quasi-solid electrode material.

Sequence 3 (S3): First, the desired amount of RGO or CNT filaments was dispersed in a liquid solvent mixture (PC+DOL) in which no lithium salt was dissolved. Mechanical shear was used to promote the formation of a uniform suspension of conductive filaments in the solvent. LiBF ₄ salt, PEO, and S/CB particles were then added into the suspension, and the LiBF ₄ salt was dissolved in the solvent mixture of the suspension to obtain 1.0 M, 2.5 M, and 3.5 M, respectively. formed an electrolyte having a salt concentration of Simultaneously, or subsequently, by dispersing S/CB particles in the electrolyte, a deformable material composed of dispersed active material particles and conductive filaments in a quasi-solid electrolyte (neither a liquid electrolyte nor a solid electrolyte) A quasi-solid electrode material was formed. In this quasi-solid electrode material, conductive filaments permeate to form a 3D network of electron-conducting pathways. This 3D conductive network is maintained when the electrode material is molded into a battery electrode.

The electrical conductivity of the electrodes was measured using a four-point probe method. The results are summarized in FIGS. 5(A) and 5(B). These data indicate that, except for electrodes fabricated according to sequence 3 (S3), typically the formation of a 3D network of electron conduction pathways by penetration of conductive filaments (CNF or RGO) is less than the volume fraction of the conductive filaments. It shows that it does not occur until the rate exceeds 10-12%. In other words, before the lithium salt, sodium salt, or ion-conducting polymer is dissolved in the liquid solvent, and before the active material particles are dispersed in the solvent, the step of dispersing the conductive filaments in the liquid solvent should be performed. There is Such a sequence also allows penetration thresholds as low as 0.3% to 2.0%, using minimal amounts of conductive additives and thus a higher proportion of active material (and higher energy density). This makes it possible to produce conductive electrodes. It has also been found that these observations hold true for all types of electrodes examined thus far, including active material particles, conductive filaments, and electrolytes. This is a very important and unexpected process requirement for producing high performance alkali metal batteries with both high energy density and high power density.

A quasi-solid cathode, a porous separator, and a quasi-solid anode (made in a similar manner but with artificial graphite particles as the anode active material) are then combined together to form a unit cell, which is then externally The battery was constructed in a protective housing (laminated aluminum-plastic pouch) with two protruding terminals. Batteries containing liquid or polymer gel electrolytes (1M) and quasi-solid electrolytes (2.5M and 3.5M) were fabricated and tested.

For comparison purposes, a slurry coating and drying procedure was performed to produce a conventional electrode. One anode and one cathode, and a separator positioned between the two electrodes are then combined and placed in an Al-plastic laminated packaging envelope followed by injection of liquid electrolyte to form a prior art lithium battery. formed a cell. Battery test results are summarized in Example 18.

Example 9: Electrochemical deposition of S on various web or paper structures for Li-S and Na-S batteries. ) can be electrochemically deposited. In this method, an anode, an electrolyte, and a layer of graphene sheets agglomerated together (functioning as a cathode layer) are placed in an electrochemical deposition chamber. The equipment required is similar to electroplating systems known in the art.

In one typical procedure, a metal polysulfide (M _x S _y ) is dissolved in a solvent (eg, a mixture of DOL/DME in a volume ratio of 1:3 to 3:1) to form an electrolyte solution. A certain amount of lithium salt can optionally be added, but this is not necessary for external electrochemical deposition. A wide variety of solvents can be used for this purpose, and there is no theoretical limit as to which type of solvent can be used, and any solvent can be used as long as the metal polysulfide has some degree of solubility in this desired solvent. can be used. Higher solubility means that higher amounts of sulfur can come from the electrolyte solution.

This electrolyte solution is then poured into a chamber or reactor under dry and controlled atmospheric conditions (eg He or nitrogen gas). A metal foil can be used as the anode and a layer of porous graphene structure can be used as the cathode; both are immersed in the electrolyte solution. This structure constitutes an electrochemical deposition system. The step of electrochemically depositing nanoscale sulfur particles or a coating on the graphene sheet surface preferably at a current density in the range of 1 mA/g to 10 A/g, based on the weight of the layer of porous graphene structure. done.

The chemical reaction occurring in this reactor can be represented by the formula: M _x S _y →M _x S _y−z +zS (typically z=1-4). Quite surprisingly, the precipitated S nucleates and grows preferentially on large graphene surfaces to form nanoscale coatings or nanoparticles. The coating thickness or particle size, as well as the amount of S-coating/particle, can be controlled by the specific surface area, current density, temperature, and time of the electrochemical reaction. In general, lower current densities and lower reaction temperatures result in a more uniform distribution of S and easier control of the reaction. Longer reaction times result in higher amounts of S being deposited on the graphene surface, and the reaction stops when the sulfur source is consumed or the desired amount of S is deposited. These S-coated paper or web structures are then ground into fine particles for use as cathode active materials in Li--S cells or Na--S cells.

Example 10 Chemical Reaction Induced Deposition of Sulfur Particles on Isolated Graphene Sheets Prior to Forming a Cathode Layer A deposition method is used here (ie, before chemically depositing S on the surface of the GO sheets, these GO sheets are not compacted into a monolithic structure of porous graphene). The procedure started by adding 0.58 g of Na ₂ S into a flask containing 25 ml of distilled water to form a Na ₂ S solution. Next, 0.72 g of elemental S was suspended in the Na ₂ S solution and stirred with a magnetic stirrer at room temperature for about 2 hours. The color of the solution slowly changed to orange-yellow as the sulfur dissolved. After the sulfur dissolved, a sodium polysulfide (Na ₂ S _x ) solution was obtained (x=4-10).

Graphene oxide-sulfur (GO-S) composites were subsequently fabricated by a chemical deposition method in aqueous solution. First, 180 mg of graphite oxide was suspended in 180 ml of ultrapure water, followed by sonication at 50° C. for 5 hours to prepare a stable graphene oxide (GO) dispersion. Subsequently, Na ₂ S _x solution was added to the GO dispersion prepared above in the presence of ₅ wt. _{The x} mixed solution was sonicated for another 2 hours, then titrated into 100 ml of 2 mol/L HCOOH solution at a rate of 30-40 drops/min and stirred for 2 hours. Finally, the precipitate was filtered and washed several times with acetone and distilled water to remove salts and impurities. After filtration, the precipitate was dried in a drying oven at 50° C. for 48 hours. This reaction can be represented by the reaction: S _x ²⁻ +2H ⁺ →(x−1)S+H ₂ S.

Example 11: Deposition of Sulfur Particles Induced by a Redox Chemical Reaction on Isolated Graphene Sheets and Activated Carbon (AC) Particles Prior to Forming the Cathode Layer In this chemical reaction-based deposition method, sodium thiosulfate ( Na ₂ S ₂ O ₃ ) was used as the sulfur source and HCl was used as the reactant. A GO-water or activated carbon-water suspension was prepared and then the two reactants (HCl and Na ₂ S ₂ O ₃ ) were poured into this suspension. The reaction was allowed to proceed at 25-75° C. for 1-3 hours, resulting in precipitation of S particles deposited on the surface of the GO sheets or within the pores of the AC particles. This reaction can be expressed as: _2HCl + _Na2S2O3 →2NaCl+S↓+ _{SO2 ↑} + _H2O .

Example 12 Preparation of S/GO Nanocomposites by Solution Deposition GO sheets and S were mixed and dispersed in a solvent ( _CS2 ) to form a suspension. After sufficient stirring, the solvent was evaporated to obtain a solid nanocomposite, which was then ground to obtain a nanocomposite powder. The primary sulfur particles in these nanocomposite particles have an average diameter of about 40-50 nm.

Example 13: Conductive web of filaments from electrospun PAA fibrils as support layer for anode Pyromellitic dianhydride (Aldrich ) and 4,4′-oxydianiline (Aldrich) to prepare a poly(amic acid) (PAA) precursor for spinning. The PAA solution was spun using an electrostatic spinning device to obtain a fibrous web. The apparatus consisted of a 15 kV DC power supply with a positively charged capillary through which the polymer solution was extruded and a negatively charged drum to collect the fibers. Simultaneous solvent removal and imidization from PAA was achieved by stepwise heat treatment under air flow at 40° C. for 12 hours, 100° C. for 1 hour, 250° C. for 2 hours, and 350° C. for 1 hour. A thermoset polyimide (PI) web sample was carbonized at 1,000° C. to yield carbonized nanofibers with an average fibril diameter of 67 nm. Such webs can be used as a conductive substrate for anode active materials. We have determined that the use of a network of conductive nanofilaments in the anode of Li—S cells can effectively suppress the initiation and growth of lithium dendrites that could otherwise cause internal short circuits. are doing.

Example 14: Preparation of pre-sodiumated graphene fluoride sheets as anode active materials for sodium-sulfur batteries. Only one method is described here. In one typical procedure, heavily exfoliated graphite (HEG) was prepared from the intercalate compound С ₂ F.xClF ₃ . HEG was further fluorinated by chlorine trifluoride vapor to obtain fluorinated heavily exfoliated graphite (FHEG). A pre-chilled Teflon reactor was charged with 20-30 mL of liquid pre-chilled ClF ₃ , the reactor was closed and cooled to liquid nitrogen temperature. Next, 1 g or less of HEG was placed in a container with holes for ClF ₃ gas to pass through and placed in the reactor. A grey-beige product with the general formula C ₂ F was formed in 7-10 days.

Subsequently, a small amount of FHEG (approximately 0.5 mg) was mixed with 20-30 mL of organic solvent (methanol and ethanol separately) and sonicated (280 W) for 30 min to form a homogeneous yellowish dispersion. formed. Upon removal of solvent, the dispersion became a brownish powder. The graphene fluoride powder can be pre-sodiumized by mixing with sodium chips in a liquid electrolyte before or after injection into the pores of the anode current collector.

Example 15: Graphene Enhanced Nanosilicon as Anode Active Material for Lithium Ion Sulfur Batteries Angstron Energy Co.; Graphene-wrapped Si particles were available from Physics, Inc., Dayton, Ohio. Pure graphene sheets (as conductive filaments) were dispersed in a PC-DOL (50/50 ratio) mixture, followed by graphene-wrapped Si particles (anode active material) and 3.5 M hexagonal A quasi-solid anode electrode was fabricated by dissolving lithium fluorophosphate (LiPF ₆ ) in the mixture solvent at 60°C. Then the DOL was removed to obtain a quasi-solid electrolyte containing about 5.0 M _LiPF6 in PC. Since the maximum solubility of LiPF ₆ in PC is known to be less than 3.0 M at room temperature, this makes LiPF ₆ supersaturated.

Example 16: Graphene Reinforced Tin Oxide Microparticles as Anode Active Materials Tin oxide ( _SnO2 ) nanoparticles were obtained by controlled hydrolysis of _SnCl4.5H2O and _NaOH using the following procedure: SnCl ₄ .5H ₂ O (0.95 g, 2.7 m-mol) and NaOH (0.212 g, 5.3 m-mol) were each dissolved in 50 mL of distilled water. The NaOH solution was added dropwise at a rate of 1 mL/min to the tin chloride solution with vigorous stirring. The solution was homogenized by sonication for 5 minutes. The resulting hydrosol was then reacted with the GO dispersion for 3 hours. A few drops of 0.1 M H ₂ SO ₄ were added to the mixed solution to aggregate the product. The precipitated solid was collected by centrifugation, washed with water and ethanol and dried in vacuum. The dried product was heat treated at 400° C. for 2 hours under Ar atmosphere and used as an anode active material.

Example 17 Preparation and Electrochemical Testing of Various Battery Cells For most of the anode and cathode active materials investigated, lithium ion or lithium metal cells were prepared using both the method according to the invention and conventional methods. prepared.

In conventional methods, a typical anode composition comprises 85 wt % active material (eg, Si-coated graphene sheets) dissolved in N-methyl-2-pyrrolidinone (NMP) and 7 wt % acetylene black (Super -P) and 8 wt% polyvinylidene fluoride binder (PVDF, 5 wt% solids). After coating the slurry on the Cu foil, the electrode was vacuum dried at 120° C. for 2 hours to remove the solvent. By this method, typically no binder resin is required or used, saving 8% by weight (reducing the amount of non-active materials). The cathode layer is similarly formed (using Al foil as the cathode current collector) using conventional slurry coating and drying procedures. The anode layer, separator layer (eg Celgard 2400 membrane), and cathode layer are then laminated together and encased in a plastic Al envelope. As an example, the cell is then injected with a 1 M LiPF ₆ electrolyte solution dissolved in a mixture of ethylene carbonate (EC) and diethyl carbonate (DEC) (EC-DEC, 1:1 v/v). Some cells used ionic liquids as liquid electrolytes. A cell assembly was formed in an argon-filled glove box.

In the method according to the invention, preferably the quasi-solid polymer anode, porous separator and quasi-solid polymer cathode are assembled in a protective housing. The pouch was then sealed.

Cyclic voltammetry (CV) measurements were performed using an Arbin electrochemical workstation with a typical scan rate of 1 mV/s. Furthermore, the electrochemical performance of various cells was evaluated at current densities from 50 mA/g to 10 A/g by galvanostatic charge/discharge cycling. A LAND multi-channel battery tester was used for long-term cycling tests.

Example 18: Typical Test Results For each sample, several current densities (representing charge/discharge rates) were imposed to determine the electrochemical response and the Ragone plot (power density versus energy density) It enabled the calculation of the energy density and power density values required for construction. In FIG. 6(A), a Ragone plot (weight power density versus energy density) of a lithium-sulfur cell containing Li foil as the anode active material and carbon black-sulfur composite particles as the cathode active material is shown. there is Three of the four data curves are for cells made according to one embodiment of the present invention (using the order S1, S2, and S3, respectively), and the remaining one is for a conventional electrode slurry coating (roll coating). Several important observations can be made from these data.

The gravimetric energy densities and power densities of lithium-ion battery cells prepared by the method according to the invention are considerably higher than those of counterparts prepared by conventional roll coating methods (denoted as "conventional"). Gravimetric energy density from 325 Wh/kg to 415 Wh/kg (S1) as a result of changing from a cathode thickness of 150 μm (coated on a flat solid Al foil) to a thickness of 525 μm with a quasi-solid polymer electrolyte, It increases to 430 Wh/kg (S2) and 530 Wh/kg (S3) respectively. Also surprisingly, batteries containing a quasi-solid electrode according to the present invention, which has a 3D network of electronically conducting pathways (due to penetration of conductive filaments), have much higher energy densities (FIG. 6(A)) and more stable cycling. The behavior (FIG. 6(B)) is obtained.

These large differences are not solely due to increased electrode thickness and mass loading. This difference is probably due to the very high active material mass loading (not just mass loading) and high electrical conductivity associated with the cell according to the invention, the reduced ratio of overhead (inactive) components to active material weight/volume. , as well as the surprisingly good utilization of the electrode active materials (most if not all S contributes to the lithium ion storage capacity due to the high conductivity, and especially under high charge/discharge rate conditions, no dry pockets or ineffective spots in the electrode).

FIG. 7(A) shows Ragone plots (gravimetric energy density versus gravimetric power density) of two cells containing graphene-supported S particles as the cathode active material. Experimental data were obtained from Li--S battery cells prepared by the method according to the present invention and Li--S battery cells prepared by conventional slurry coating of electrodes.

These data show that the gravimetric energy density and power density of battery cells prepared by the method according to the invention are significantly higher than their counterparts prepared by conventional methods. The difference is big here too. Conventionally produced cells exhibit a gravimetric energy density of 433 Wh/kg, whereas cells according to the invention yield energy densities (S3) of 605 Wh/kg respectively. Power densities as high as 2,021 W/kg are also unprecedented for lithium-sulphur batteries. Cells according to the invention also yield much more stable charge/discharge cycling behavior, as shown in FIG. 7(B)).

The difference in these energy densities and power densities is mainly due to the following. High active material mass loading (>25 mg/cm ² for anode and >45 mg/cm ² for cathode) and high electrode conductivity associated with cells according to the invention; and a better utilization of the active material (all particles accessible to the liquid electrolyte, high ion and electron kinetic velocities) function of the method according to the invention.

FIG. 8 shows Ragone plots (gravimetric power density vs. gravimetric energy) of cells with quasi-solid electrolytes (S1, S3) with Si nanoparticle anodes and lithium cobalt oxide (LiCoO ₂ ) cathodes compared to cells with conventional electrolytes. density). FIG. 9 shows Ragone plots (gravimetric power density versus gravimetric energy density) of a sodium ion capacitor (SIC) with a quasi-solid electrolyte with a conventional electrolyte and compared to a SIC.

Reporting energy and power densities per weight of the active material alone on Ragone plots, as many researchers do, may not give a realistic picture of the performance of the assembled supercapacitor cells. It would be important to point out The weight of other device components must also be taken into account. These overhead components, including current collectors, electrolytes, separators, binders, connectors, and packaging, are non-active materials and do not contribute to charge storage mass. These components only add weight and volume to the device. Therefore, it is desirable to reduce the relative proportions of weight of overhead components and increase the percentage of active material. However, it has not been possible to achieve this goal using conventional battery manufacturing methods. The present invention overcomes this longstanding and most serious problem in the lithium battery art.

In commercial lithium-ion batteries with an electrode thickness of 100-200 μm, the weight ratio of anode active material (e.g., graphite or carbon) in lithium-ion batteries is typically 12-17%, and that of the cathode active material. The weight ratio (for inorganic materials such as LiMn ₂ O ₄ ) is between 22% and 41%, or between 10% and 15% for organic or polymeric materials. Therefore, a factor of 3-4 is frequently used to extrapolate the energy or power density of a device (cell) from properties based on active material weight alone. In most scientific papers, reported properties are typically based on active material weight only, and electrodes are typically very thin (<<100 μm, and often <<50 μm). The active material weight is typically 5%-10% of the total device weight, which is the actual cell (device) energy or power density by dividing the corresponding active material weight base value by a factor of 10-20. suggests that we can obtain After this factor is taken into account, the properties reported in these papers are unlikely to be better than those of commercial batteries. Therefore, great caution must be exercised in reading and interpreting battery performance data reported in scientific papers and patent applications.

Claims (47)

In an alkali metal-sulfur cell:
(a) from 30% to 95% by volume of a sulfur-containing cathode active material and from 5% to 40% by volume of an alkali salt dissolved in a solvent and excluding an ionically conductive polymer dissolved or dispersed in said solvent; A quasi-solid cathode comprising a first electrolyte and 0.01% to 30% by volume of a conductive additive, wherein the sulfur-containing cathode active material comprises sulfur, metal-sulfur compounds, sulfur-carbon composites, sulfur - graphene composites, sulfur-graphite composites, organic sulfur compounds, sulfur-polymer composites, or combinations thereof, such that the quasi-solid cathode has an electrical conductivity of 10 ^-6 S/cm to 300 S/cm. a quasi-solid cathode, wherein said conductive additives comprising conductive filaments form a 3D network of electron conducting pathways;
(b) an anode;
(c) an ion-conducting membrane or porous separator disposed between the anode and the quasi-solid cathode;
An alkali metal-sulfur cell comprising: 2. The alkali metal-sulfur cell of claim 1, wherein the anode comprises 1.0% to 95% by volume anode active material and 5% to 40% by volume of an alkali salt dissolved in a solvent. 2 and a conductive additive of 0.01% to 30% by volume, such that the quasi-solid electrode has an electrical conductivity of 10 ⁻⁶ S/cm to 300 S/cm. , an alkali metal-sulfur cell characterized in that said conductive additive comprising conductive filaments forms a 3D network of electron conducting pathways. In an alkali metal-sulfur cell:
A) 1.0% to 95% by volume of anode active material and 5% to 40% by volume of electrolyte comprising an alkali salt dissolved in a solvent and excluding an ion-conducting polymer dissolved or dispersed in said solvent. and 0.01% to 30% by volume of a conductive additive, the conductive additive such that the pseudosolid anode has an electrical conductivity of 10 ⁻⁶ S/cm to 300 S/cm a quasi-solid anode, wherein said conductive additive comprising filaments forms a 3D network of electron-conducting pathways;
B) a cathode comprising a cathode active material selected from sulfur, metal-sulfur compounds, sulfur-carbon composites, sulfur-graphene composites, sulfur-graphite composites, organic sulfur compounds, or sulfur-polymer composites;
C) an ion-conducting membrane or porous separator disposed between said quasi-solid anode and said cathode;
An alkali metal-sulfur cell comprising: The alkali metal-sulfur cell of claim 1, wherein the conductive filaments are carbon fibers, graphite fibers, carbon nanofibers, graphite nanofibers, carbon nanotubes, needle coke, carbon whiskers, conductive polymer fibers, conductive materials. An alkali metal-sulfur cell characterized by being selected from coated fibers, metal nanowires, metal fibers, metal wires, graphene sheets, expanded graphite platelets, combinations thereof, or combinations thereof with non-filamentary conductive particles. . 4. The alkali metal-sulfur cell of claim 3, wherein the conductive filaments are carbon fibers, graphite fibers, carbon nanofibers, graphite nanofibers, carbon nanotubes, needle coke, carbon whiskers, conductive polymer fibers, conductive materials. An alkali metal-sulfur cell characterized by being selected from coated fibers, metal nanowires, metal fibers, metal wires, graphene sheets, expanded graphite platelets, combinations thereof, or combinations thereof with non-filamentary conductive particles. . An alkali metal-sulphur cell according to claim 1, characterized in that said quasi-solid cathode has an electrical conductivity between 10 ^-3 S/cm and 10 S/cm. An alkali metal-sulfur cell according to claim 1, characterized in that the quasi-solid cathode comprises 0.1% to 20% by volume of a conductive additive. An alkali metal-sulfur cell according to claim 1, characterized in that the quasi-solid cathode comprises 1% to 10% by volume of a conductive additive. An alkali metal-sulfur cell according to claim 1, characterized in that the amount of sulfur-containing cathode active material is between 40% and 90% by volume of the quasi-solid cathode. An alkali metal-sulfur cell according to claim 1, characterized in that the amount of said sulfur-containing cathode active material is between 50% and 85% by volume of said quasi-solid cathode. The alkali metal-sulfur cell of claim 1, wherein said first electrolyte is supersaturated. 3. An alkali metal-sulfur cell as claimed in claim 2, characterized in that the first electrolyte or the second electrolyte is supersaturated. An alkali metal-sulfur cell according to claim 1, characterized in that the solvent is selected from water, organic solvents, ionic liquids, or mixtures of organic solvents and ionic liquids. 3. The alkali metal-sulfur cell of claim 2, wherein said first electrolyte or second electrolyte comprises a solvent selected from water, organic solvents, ionic liquids, or mixtures of organic solvents and ionic liquids. An alkali metal-sulfur cell characterized by: The alkali metal-sulfur cell of claim 1, wherein the anode comprises:
(a) particles, films, or foils of lithium metal or lithium metal alloy;
(b) natural graphite particles, synthetic graphite particles, mesocarbon microbeads (MCMB), carbon particles, needle coke, carbon nanotubes, carbon nanofibers, carbon fibers, and graphite fibers;
(c) silicon (Si), germanium (Ge), tin (Sn), lead (Pb), antimony (Sb), bismuth (Bi), zinc (Zn), aluminum (Al), nickel (Ni), cobalt ( Co), manganese (Mn), titanium (Ti), iron (Fe), and cadmium (Cd);
(d) stoichiometric or non-stoichiometric alloys or compounds of Si, Ge, Sn, Pb, Sb, Bi, Zn, Al, or Cd with another element or intermetallic compound;
(e) Si, Ge, Sn, Pb, Sb, Bi, Zn, Al, Fe, Ni, Co, Ti, Mn, or Cd oxides, carbides, nitrides, sulfides, phosphides, selenides, and tellurides, and mixtures or composites thereof;
(f) prelithiated Si;
(g) prelithiated graphene sheets; and combinations thereof;
An alkali metal-sulfur cell comprising an anode active material selected from the group consisting of: 16. The alkali metal-sulfur cell of claim 15, wherein the prelithiated graphene sheets are composed of pure graphene, graphene oxide, reduced graphene oxide, graphene fluoride, graphene chloride, graphene bromide, graphene iodide, hydrogen prelithiation of graphene nitride, graphene nitrogen, boron doped graphene, nitrogen doped graphene, chemically functionalized graphene, physically or chemically activated or etched versions thereof, or combinations thereof Alkali metal-sulphur cell, characterized in that it is selected from the selected versions. The alkali metal-sulfur cell of claim 1, wherein the alkali metal-sulfur cell is a sodium metal-sulfur cell or a sodium ion sulfur cell, and the anode comprises sodium metal or petroleum coke, amorphous Carbon, activated carbon, hard carbon _{, soft carbon} , template carbon, hollow carbon nanowires, hollow carbon spheres _, titanates, _NaTi2 ( _PO4 ) ₃ , _{Na2Ti3O7 , Na2C8H4O4} , _Na2TP , Na _x TiO ₂ (x=0.2-1.0), Na ₂ C ₈ H ₄ O ₄ , carboxylate-based materials, C ₈ H ₄ Na ₂ O ₄ , C ₈ H ₆ O ₄ , C ₈ H _{alkali intercalation selected from 5NaO4 , C8Na2F4O4 , C10H2Na4O8 , C14H4O6 , C14H4Na4O8 , or combinations thereof} An alkali metal-sulfur cell comprising an anode active material comprising a compound. 3. The alkali metal-sulfur cell of claim 2, wherein the alkali metal-sulfur cell is a sodium-sulfur cell or a sodium ion sulfur cell, and the anode comprises:
a) particles, foils or films of sodium metal or sodium metal alloys;
b) natural graphite particles, synthetic graphite particles, mesocarbon microbeads (MCMB), carbon particles, needle coke, carbon nanotubes, carbon nanofibers, carbon fibers and graphite fibers;
c) Sodium-doped Silicon (Si), Germanium (Ge), Tin (Sn), Lead (Pb), Antimony (Sb), Bismuth (Bi), Zinc (Zn), Aluminum (Al), Titanium (Ti ), cobalt (Co), nickel (Ni), manganese (Mn), cadmium (Cd), and mixtures thereof;
d) sodium-containing alloys or intermetallic compounds of Si, Ge, Sn, Pb, Sb, Bi, Zn, Al, Ti, Co, Ni, Mn, Cd, and mixtures thereof;
e) sodium-containing oxides, carbides, nitrides of Si, Ge, Sn, Pb, Sb, Bi, Zn, Al, Fe, Ti, Co, Ni, Mn, Cd, and mixtures or composites thereof; sulfides, phosphides, selenides, tellurides, or antimonides;
f) sodium salts;
g) graphene sheets preloaded with sodium ions; and combinations thereof,
An alkali metal-sulfur cell comprising an anode active material selected from the group consisting of: The alkali metal-sulfur cell of claim 1, wherein the sulfur-containing cathode active material is:
A) Nanostructured selected from soft carbon, hard carbon, polymeric carbon or carbonized resin, mesophase carbon, coke, carbonized pitch, carbon black, activated carbon, nanocellular carbon foam, or particles of partially graphitized carbon. textured or porous irregular carbon materials;
B) nanographene platelets selected from monolayer graphene sheets or multilayer graphene platelets;
C) carbon nanotubes selected from single-wall carbon nanotubes or multi-wall carbon nanotubes;
D) carbon nanofibers, nanowires, metal oxide nanowires or fibers, conducting polymer nanofibers, or combinations thereof;
E) carbonyl-containing organic or polymeric molecules;
F) functional materials containing carbonyl, carboxylic acid, or amine groups to reversibly trap sulfur;
and combinations thereof,
An alkali metal-sulfur cell characterized in that it is supported by a functional or nanostructured material selected from the group consisting of: The alkali metal-sulfur cell of claim 1, wherein the first electrolyte is 1,3-dioxolane (DOL), 1,2-dimethoxyethane (DME), tetraethylene glycol dimethyl ether (TEGDME), poly(ethylene glycol) dimethyl ether (PEGDME), diethylene glycol dibutyl ether (DEGDBE), 2-ethoxyethyl ether (EEE), sulfone, sulfolane, ethylene carbonate (EC), dimethyl carbonate (DMC), methyl ethyl carbonate (MEC), diethyl carbonate (DEC ), ethyl propionate, methyl propionate, propylene carbonate (PC), gamma-butyrolactone (γ-BL), acetonitrile (AN), ethyl acetate (EA), propyl formate (PF), methyl formate (MF), toluene, an organic solvent selected from the group consisting of xylene, methyl acetate (MA), fluoroethylene carbonate (FEC), vinylene carbonate (VC), allyl ethyl carbonate (AEC), hydrofluoroethers, and combinations thereof An alkali metal-sulfur cell characterized by: The alkali metal-sulfur cell of claim 1, wherein the first electrolyte is lithium perchlorate (LiClO ₄ ), lithium hexafluorophosphate (LiPF ₆ ), lithium borofluoride (LiBF ₄ ), lithium trifluoro-metasulfonate (LiCF 3 SO 3 ), _lithium bistrifluoromethylsulfonylimide _{(LiN(CF 3 SO 2 ) 2} ) , lithium bis(oxalato)borate (LiBOB), lithium oxalyl difluoroborate (LiBF ₂ C ₂ O ₄ ), lithium oxalyl difluoroborate (LiBF ₂ C ₂ O ₄ ), lithium nitrate (LiNO ₃ ), Li-fluoroalkyl-phosphate (LiPF3(CF ₂ CF ₃ ) ₃ ), lithium bisperfluoroethysulfonylimide (LiBETI), sodium perchlorate (NaClO ₄ ), potassium perchlorate (KClO ₄ ), sodium hexafluorophosphate (NaPF _{6 ), hexafluorophosphate (NaPF 6} ), Potassium fluorophosphate (KPF ₆ ), sodium borofluoride (NaBF ₄ ), potassium fluoroborate (KBF ₄ ), sodium hexafluoroarsenide, potassium hexafluoroarsenide, sodium trifluoro-metasulfonate ( NaCF ₃ SO ₃ ), potassium trifluoro-metasulfonate (KCF ₃ SO ₃ ), sodium bistrifluoromethylsulfonylimide (NaN(CF ₃ SO ₂ ) ₂ ), sodium trifluoromethanesulfonimide (NaTFSI) , potassium bistrifluoromethylsulfonylimide (KN(CF ₃ SO ₂ ) ₂ ), or combinations thereof. The alkali metal-sulfur cell of claim 1, wherein the first electrolyte is tetraalkylammonium, di-, tri-, or tetraalkylimidazolium, alkylpyridinium, dialkylpyrrolidinium, dialkylpiperidinium, tetraalkylphosphonium , trialkylsulfonium, or combinations thereof . 23. The alkali metal-sulfur cell of claim 22, wherein the ionic liquid solvent is BF ₄ ⁻ , B(CN) ₄ ⁻ , CH ₃ BF ₃ ⁻ , CH ₂ CHBF ₃ ⁻ , CF ₃ BF ₃ ⁻ , C ₂ F ₅ BF ₃ ⁻ , nC ₃ F ₇ BF ₃ ⁻ , nC ₄ F ₉ BF ₃ ⁻ , PF ₆ ⁻ , CF ₃ CO ₂ ⁻ , CF ₃ SO ₃ ⁻ , N(SO ₂ CF ₃ ) ₂ ⁻ , N(COCF ₃ )(SO ₂ CF ₃ ) ⁻ , N(SO ₂ F) ₂ ⁻ , N(CN) ₂ ⁻ , C(CN) ₃ ⁻ , SCN ⁻ , SeCN ⁻ , CuCl ₂ ⁻ , AlCl ₄ ^- , F ( HF) _2.3 ^- , or a combination thereof. An alkali metal-sulfur cell according to claim 1, characterized in that the sulfur-containing cathode active material constitutes an electrode active material mass loading of greater than 15 mg/cm ² . 3. The alkali metal-sulfur cell of claim 2, wherein said anode active material constitutes an electrode active material mass loading of greater than 20 mg/ ^cm2 . An alkali metal-sulfur cell according to claim 1, characterized in that the sulfur-containing cathode active material constitutes an electrode active material mass loading of greater than 30 mg/cm ² . In a method for manufacturing an alkali metal-sulfur cell with quasi-solid electrodes:
(a) combining an amount of cathode active material, an amount of electrolyte, and a conductive additive to form a deformable, electrically conductive cathode material, wherein said cathode active material comprises sulfur, a metal - a conductive filament comprising a sulfur-containing material selected from sulfur compounds, sulfur-carbon composites, sulfur-graphene composites, sulfur-graphite composites, organic sulfur compounds, sulfur-polymer composites, or combinations thereof; said conductive additives comprising forming a 3D network of electronically conducting pathways, said electrolyte comprising an alkali salt dissolved in a solvent and no ion-conducting polymer dissolved or dispersed in said solvent;
(b) forming a quasi-solid cathode from said cathode material, said forming step forming a 3D network of said electron conducting pathways such that said quasi-solid cathode maintains an electrical conductivity of 10 ⁻⁶ S/cm or greater; deforming the cathode material into an electrode shape without interrupting;
(c) forming an anode;
(d) forming an alkali metal-sulfur cell by combining said quasi-solid cathode and said anode;
A method comprising: 28. The method of claim 27, wherein the quasi-solid cathode comprises 30% to 95% by volume of the cathode active material, 5% to 40% by volume of the electrolyte, and 0.01% to 30% by volume. and the conductive additive of 28. The method of claim 27, wherein the conductive filaments are carbon fibers, graphite fibers, carbon nanofibers, graphite nanofibers, carbon nanotubes, needle coke, carbon whiskers, conductive polymer fibers, conductive material coated fibers, metal selected from nanowires, metal fibers, metal wires, graphene sheets, expanded graphite platelets, combinations thereof, or combinations thereof with non-filamentary conductive particles. 28. The method of claim 27, wherein the quasi-solid electrode maintains an electrical conductivity between ^10-3 S/cm and 10 S/cm. 28. The method of claim 27, wherein the quasi-solid cathode comprises 0.1% to 20% by volume conductive additive. 28. The method of claim 27, wherein the quasi-solid cathode comprises 1% to 10% by volume of a conductive additive. 28. The method of claim 27, wherein the amount of cathode active material is between 40% and 90% by volume of the cathode material. 28. The method of claim 27, wherein the amount of cathode active material is between 50% and 85% by volume of the cathode material. 28. The method of claim 27, wherein said combining step comprises dispersing said conductive filaments in a liquid solvent to form a uniform suspension before adding said cathode active material to said uniform suspension. and prior to dissolving said alkali metal salt in said liquid solvent of said homogeneous suspension. 28. The method of claim 27, wherein combining and forming a quasi-solid cathode from the cathode material comprises dissolving a lithium or sodium salt in a liquid solvent to form an electrolyte having a first salt concentration. followed by removing a portion of said liquid solvent to increase said first salt concentration to form a pseudo-solid having a second salt concentration higher than said first salt concentration and greater than 2.5M. obtaining an electrolyte. 37. The method of claim 36, wherein the removing step neither precipitates nor crystallizes the salt and the electrolyte is supersaturated. 37. The method of claim 36, wherein said liquid solvent comprises a mixture of at least a first liquid solvent and a second liquid solvent, wherein said first liquid solvent is more volatile than said second liquid solvent. , wherein said removing a portion of said liquid solvent comprises removing said first liquid solvent. 28. The method of claim 27, wherein the step of forming the anode comprises: (A) combining an amount of anode active material, an amount of electrolyte, and a conductive additive to form a deformable, electrically conductive (B ) forming a quasi-solid anode from said deformable and conductive anode material, said forming step reducing said electronic conduction path such that said anode maintains an electrical conductivity of 10 ⁻⁶ S/cm or greater; deforming the deformable and conductive anode material into an electrode shape without disrupting the 3D network;
A method comprising: 28. The method of claim 27, wherein the solvent is selected from water, organic solvents, ionic liquids, or mixtures of organic solvents and ionic liquids. 28. The method of claim 27, wherein the alkali metal-sulfur cell is a lithium ion sulfur cell and the anode comprises:
(h) particles of lithium metal or lithium metal alloy;
(i) natural graphite particles, synthetic graphite particles, mesocarbon microbeads (MCMB), carbon particles, needle coke, carbon nanotubes, carbon nanofibers, carbon fibers, and graphite fibers;
(j) silicon (Si), germanium (Ge), tin (Sn), lead (Pb), antimony (Sb), bismuth (Bi), zinc (Zn), aluminum (Al), nickel (Ni), cobalt ( Co), manganese (Mn), titanium (Ti), iron (Fe), and cadmium (Cd);
(k) alloys or intermetallics of Si, Ge, Sn, Pb, Sb, Bi, Zn, Al, or Cd with another element, which are stoichiometric or non-stoichiometric; Compound;
(l) Si, Ge, Sn, Pb, Sb, Bi, Zn, Al, Fe, Ni, Co, Ti, Mn, or Cd oxides, carbides, nitrides, sulfides, phosphides, selenides, and tellurides, and mixtures or composites thereof;
(m) prelithiated versions thereof;
(n) prelithiated graphene sheets; and combinations thereof;
A method comprising an anode active material selected from the group consisting of: 42. The method of claim 41, wherein the prelithiated graphene sheets are pure graphene, graphene oxide, reduced graphene oxide, graphene fluoride, graphene chloride, graphene bromide, graphene iodide, graphene hydride, nitrogen. from prelithiated versions of graphene, boron-doped graphene, nitrogen-doped graphene, chemically functionalized graphene, physically or chemically activated or etched versions thereof, or combinations thereof A method characterized by being selected. 28. The method of claim 27, wherein the alkali metal-sulfur cell is a sodium ion sulfur cell and the anode is petroleum coke, carbon black, amorphous carbon, activated carbon, hard carbon, soft carbon, template carbon, hollow Carbon nanowires, hollow carbon spheres, titanates, NaTi ₂ (PO ₄ ) ₃ , Na ₂ Ti ₃ O ₇ , Na ₂ C ₈ H ₄ O ₄ , Na ₂ TP, Na _x TiO ₂ (x=0.2-1. _{0 ) , Na2C8H4O4 ,} carboxylate _{- based materials , C8H4Na2O4 , C8H6O4 , C8H5NaO4 , C8Na2F4O4 , C} A method comprising _an anode active material comprising _an alkaline intercalation compound selected from _{10H2Na4O8 , C14H4O6 , C14H4Na4O8 ,} or _{combinations thereof .} . 28. The method of claim 27, wherein the alkali metal-sulfur cell is a sodium ion sulfur cell and the anode comprises:
a) particles of sodium metal or sodium metal alloy;
b) natural graphite particles, synthetic graphite particles, mesocarbon microbeads (MCMB), carbon particles, needle coke, carbon nanotubes, carbon nanofibers, carbon fibers and graphite fibers;
c) Sodium-doped Silicon (Si), Germanium (Ge), Tin (Sn), Lead (Pb), Antimony (Sb), Bismuth (Bi), Zinc (Zn), Aluminum (Al), Titanium (Ti ), cobalt (Co), nickel (Ni), manganese (Mn), cadmium (Cd), and mixtures thereof;
d) Sodium-containing alloys or intermetallic compounds of Si, Ge, Sn, Pb, Sb, Bi, Zn, Al, Ti, Co, Ni, Mn, Cd, and mixtures thereof;
e) sodium-containing oxides, carbides, nitrides of Si, Ge, Sn, Pb, Sb, Bi, Zn, Al, Fe, Ti, Co, Ni, Mn, Cd, and mixtures or composites thereof; sulfides, phosphides, selenides, tellurides, or antimonides;
f) sodium salts;
g) graphene sheets preloaded with sodium ions; and combinations thereof,
A method comprising an anode active material selected from the group consisting of: 28. The method of claim 27, wherein the cathode active material constitutes an electrode active material mass loading greater than 15 mg/cm ^<2> . 28. The method of claim 27, wherein the cathode active material constitutes an electrode active material mass loading greater than 25 mg/cm ^<2> . 28. The method of claim 27, wherein the cathode active material constitutes an electrode active material mass loading greater than 45 mg/cm ^<2> .

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