JP2019505964A - Alkali metal-sulfur battery with high volume and weight energy density - Google Patents

Abstract

Conductivity acting as a 3D cathode current collector having (a) an anode, (b) a cathode active material slurry comprising (i) a cathode active material dispersed in an electrolyte, and (ii) at least 70% by volume pores. A cathode having a porous structure, wherein the cathode active material slurry is disposed in pores of the conductive porous structure, and the cathode active material is sulfur, lithium polysulfide, sodium polysulfide, sulfur An alkali metal comprising a cathode selected from a polymer composite, a sulfur-carbon composite, a sulfur-graphene composite, or combinations thereof, and (c) a separator disposed between the anode and the cathode In a sulfur battery, the ratio of cathode thickness to cathode current collector thickness is 0.8 / 1 to 1 / 0.8, and / or the cathode active Material, forms an electrode active material loading of 15 mg / cm ^2, greater than the 3D porous cathode current collector, or 200 [mu] m (preferably, 500 [mu] m greater) having a thickness of, alkali metal - sulfur battery.
[Selection] Figure 1 (A)

Description

CROSS REFERENCE TO RELATED APPLICATIONS This application is hereby incorporated by reference, US patent application Ser. Nos. 14 / 998,513 and 14 / 998,523, both filed Jan. 15, 2016. Claim priority to the specification.

  The present invention relates to secondary (rechargeable) lithium-sulfur batteries (including Li-S and Li-ion-S cells) or sodium-sulfur batteries (Na-S and Na) having high volumetric energy density and high gravimetric energy density. (Including ion-S cell).

Rechargeable lithium ion (Li ion) and lithium metal batteries (including Li-sulfur and Li metal-air batteries) are used in electric vehicles (EV), hybrid electric vehicles (HEV), and portable electronic devices such as laptop computers and It is regarded as a promising power source for mobile phones. Lithium as the metal element has the highest capacity compared to any other metal or metal intercalation compound as anode active material (except Li _4.4 Si with a specific capacity of 4,200 mAh / g) ( 3,861 mAh / g). Thus, in general, Li metal batteries have a significantly higher energy density than lithium ion batteries.

Historically, rechargeable lithium metal batteries, as a cathode active material bonded with a lithium metal _{anode, TiS 2, MoS 2, MnO} 2, CoO 2, and the like _V 2 _{O 5,} having a relatively high specific capacity Made using non-lithiated compounds. When the battery was discharged, lithium ions moved from the lithium metal anode through the electrolyte to the cathode, and the cathode was lithiated. Unfortunately, upon repeated charge and discharge, lithium metal formed dendrites at the anode, which eventually grew through 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 1990s and replaced by lithium ion batteries.

In lithium ion batteries, a pure lithium metal sheet or film was replaced by a carbonaceous material as the anode. The carbonaceous material absorbs lithium (eg, by lithium ion or atomic intercalation between graphene surfaces) and desorbs lithium ions during the recharge and discharge phases of lithium ion battery operation, respectively. The carbonaceous material may primarily contain graphite that can intercalate with lithium, and the resulting graphite intercalation compound can be represented as Li _x C ₆ , where x is typically Is less than 1.

  Lithium-ion (Li-ion) batteries are promising energy storage devices for electric powered vehicles, but state-of-the-art Li-ion batteries still do not meet cost and performance goals. Li ion cells typically use lithium transition metal oxides or phosphates as the positive electrode (cathode) that de / reintercalates Li + at a high potential relative to the carbon negative electrode (anode). The specific capacity of the lithium transition metal oxide or phosphate based cathode active material is typically in the range of 140-170 mAh / g. As a result, the specific energy of commercially available 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 2-3 times lower than required for battery-powered electric vehicles to be widely accepted.

With the rapid development of hybrid (HEV), plug-in hybrid electric vehicle (HEV), all-battery electric vehicle (EV), significantly higher specific energy, higher energy density, higher rate performance, longer cycle life, and There is an urgent need for anode and cathode materials that provide rechargeable batteries with safety. One of the most promising energy storage devices is a lithium-sulfur (Li-S) cell. This is because the theoretical capacity of Li is 3,861 mAh / g and the theoretical capacity of S is 1,675 mAh / g. In its simplest form, the Li—S cell consists of elemental sulfur as the positive electrode and lithium as the negative electrode. The lithium-sulfur cell operates with a redox couple represented by the reaction S ₈ + 16Li⇔8Li ₂ S close to 2.2 V versus Li ⁺ / Li ⁰ . This electrochemical potential is about 2/3 of the potential exhibited by a conventional positive electrode (eg, LiMnO ₄ ) in a conventional lithium ion battery. However, this drawback is offset by the very high theoretical capacity of both Li and S. Thus, compared to conventional intercalation-based Li-ion batteries, Li-S cells have the potential to provide a significantly higher energy density (product of capacity and voltage). Assuming a complete reaction to Li ₂ S, the energy density values can approach 2,500 Wh / kg and 2,800 Wh / L, respectively, based on the total weight or volume of Li and S. Based on total cell weight or volume, the energy density can reach about 1,000 Wh / kg and 1,100 Wh / L, respectively. However, current Li sulfur cells reported by sulfur cathode technology industry leaders have maximum cell specific energies of 250-400 Wh / kg and 500-650 Wh / L (based on total cell weight or volume). This is much lower than possible.

In summary, despite significant advantages, Li-S cells have a number of major technical problems, thus preventing the wide commercialization of Li-S cells.
(1) Conventional lithium metal cells still have the problems of dendrite formation and associated internal short circuits.
(2) Sulfur or sulfur-containing organic compounds have high insulation properties both electrically and ionically. In order to allow reversible electrochemical reactions at high current densities or charge / discharge rates, sulfur must maintain intimate contact with the conductive additive. Various carbon-sulfur composites have been utilized for this purpose, but with limited success due to the limited contact area scale. Typical capacities reported are 300-550 mAh / g (based on cathode carbon-sulfur composite weight) at moderate rates.
(3) This cell tends to show significant capacity decay during the discharge-charge cycle. This is mainly due to the high solubility of the polysulfide anion formed as a reaction intermediate in both the discharge and charge processes in the polar organic solvent used for the electrolyte. During cycling, the lithium polysulfide anion can migrate through the separator to the Li negative electrode where it is reduced to a solid precipitate (Li ₂ S ₂ and / or Li ₂ S), causing active mass loss. Furthermore, the solid product deposited on the surface of the positive electrode during discharge becomes electrochemically irreversible, which also contributes to active mass loss.
(4) More generally speaking, the major drawback of a cell comprising a cathode comprising elemental sulfur, organic sulfur, and carbon-sulfur material is that soluble sulfide, polysulfide, from the cathode to the rest of the cell, It relates to the dissolution and excessive outward diffusion of organosulfides, carbon sulfides and / or polysulfides (hereinafter referred to as anionic reduction products). This phenomenon is generally called the shuttle effect. This process results in several problems: high self-discharge rate, loss of cathode capacity, corrosion of current collectors and electrical leads leading to loss of electrical contact to active cell components, anode Contamination of the anode surface resulting in malfunction and clogging of the pores of the cell membrane separator resulting in loss of ion transport and a large increase in internal resistance within the cell.

  In response to these problems, new electrolytes, protective films for lithium anodes, and solid electrolytes have been developed. Several interesting cathode developments have recently been reported, including lithium polysulfide. However, their performance has not yet reached that required for practical applications.

  For example, Ji et al. Reported that cathodes based on nanostructured sulfur / mesoporous carbon materials can overcome these challenges significantly, exhibit stable high reversible capacity, and have excellent rate characteristics and cycling efficiency [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 creation of the proposed highly ordered mesoporous carbon structure requires a tedious and expensive template support process. It is also difficult to load these mesoscale pores with a high proportion of sulfur using physical vapor deposition or solution precipitation.

  Zhang et al. (US Patent Publication No. 2014/0234702; August 21, 2014) utilizes a chemical reaction method in which S particles are deposited on the surface of an isolated graphene oxide (GO) sheet. However, this method cannot produce a high proportion of S particles on the GO surface (ie, typically less than 66% S in a GO-S nanocomposite composition). The resulting Li-S cell also has low rate performance; for example, a specific capacity of 1,100 mAh / g (based on the weight of S) at a rate of 0.02 C, <450 mAh / g at a rate of 1.0 C Is lowered. Note that the highest specific capacity achievable, 1,100 mAh / g, shows a sulfur utilization efficiency of 1,100 / 1,675 = 65.7% 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 (similarly, 1C = 1 hour, 2C = 1/2 hour, 3C = 1/3 hour, etc.). In addition, such S-GO nanocomposite cathode-based Li-S cells exhibit very short cycle life, with a capacity typically 60% of its original capacity in less than 40 charge / discharge cycles. Less than. Due to such short cycle life, this Li-S cell is not useful for practical applications. Another chemical reaction method for depositing S particles on a graphene oxide surface is disclosed by Wang et al. (US Patent Application Publication No. 2013/0171339; July 4, 2013). This Li-S cell still has the same problem.

Liu et al. Discloses a solution precipitation method for preparing graphene-sulfur nanocomposites (with sulfur particles adsorbed on the GO surface) for use as cathode material in Li-S cells (US Patent). (Application Publication No. 2012/0088154; April 12, 2012). The method includes mixing the GO sheet and S in a solvent (CS ₂ ) to form a suspension. The solvent is then evaporated to obtain a solid nanocomposite, which is then ground to obtain a nanocomposite powder having primary sulfur particles having an average diameter of less than about 50 nm. Unfortunately, this method does not appear to be able to produce S particles below 40 nm. The resulting Li-S cell has a very short cycle life (50% capacity decay after only 50 cycles). Even when these nanocomposite particles are encapsulated in a polymer, the Li-S cell retains less than 80% of its original capacity after 100 cycles. This cell also exhibits low rate performance (specific capacity of 1,050 mAh / g (S weight) at a rate of 0.1 C. reduced to <580 mAh / g at a rate of 1.0 C). Again, this suggests that a high proportion of S does not contribute to lithium storage, resulting in low S utilization efficiency.

  Despite various proposals for the fabrication of high energy density Li-S cells, the use of electroactive cathode material (S utilization efficiency) is improved and charging with high capacity over multiple cycles There remains a need for cathode materials and manufacturing processes that provide Formula Li-S cells.

  Most importantly, including lithium metal (pure lithium, high lithium content lithium alloys with other metal elements, or lithium containing compounds with high lithium content; for example,> 80 wt% or more, or preferably > 90 wt% Li) still provides the highest anode specific capacity compared to virtually all other anode active materials (except pure silicon, but silicon has pulverization problems) To do. Lithium metal would be an ideal anode material in lithium-sulfur secondary batteries if it can address dendrite related problems.

  Sodium metal (Na) and potassium metal (K) have similar chemical properties as Li and are sulfur cathodes in room temperature sodium-sulfur cells (RT Na-S batteries) or potassium-sulfur cells (KS). Face the same problems observed with Li-S cells, such as (i) low active material utilization, (ii) low cycle life, and (iii) low Coulomb efficiency. Again, these shortcomings are mainly caused by the insulating properties of S, the dissolution of S and polysulfide Na or K intermediates in liquid electrolytes (and the associated shuttle effect), and large volume changes during charge and discharge.

  In most published literature reports (scientific papers) and patent literature, scientists or inventors have determined that the specific capacity of the cathode is based solely on the weight of sulfur or lithium polysulfide (not the total weight of the cathode composite). Unfortunately, these Li-S cells typically have a high proportion of inactive materials (materials that cannot store lithium, such as conductive additives and binders). Note that it is used. For practical purposes, it is more meaningful to use a capacity value based on the weight of the cathode composite.

A low capacity anode or cathode active material is not the only problem associated with lithium-sulfur batteries or sodium-sulfur batteries. There are significant design and manufacturing issues that the battery industry appears to be unrecognized or almost ignored. For example, these electrodes are unfortunate despite their high weight capacity at the electrode level (based solely on the weight of the anode or cathode active material) as frequently claimed in published and patent literature. However, high capacity at the battery cell or pack level (based on total battery cell weight or pack weight) cannot be provided to the battery. This is due to the view that in these reports the actual active material mass loading of the electrode is too low. In most cases, the active material mass load (area density) of the anode is much lower than 15 mg / cm ² , usually <8 mg / cm ² (area density = per electrode cross-sectional area along the electrode thickness direction). Amount of active material). The amount of cathode active material in the cell is typically 1.5 to 2.5 times the amount of anode active material. As a result, the weight ratio of the anode active material (eg, carbon) in the Na ion-sulfur battery cell or the Li ion-sulfur battery cell is typically 15% to 20%, and the weight ratio of the cathode active material is 20% to 35% (mostly <30%). The weight fraction of the composite 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 (thickness greater than 100-200 μm) using conventional slurry coating procedures. This is not as easy as it sounds, and in reality, electrode thickness is not a design parameter that can be varied arbitrarily and freely to optimize cell performance. Conversely, thicker samples tend to be very fragile or have poor structural integrity and require the use of large amounts of binder resin. Due to the low melting and soft nature of sulfur, it is virtually impossible to form a sulfur cathode thicker than 100 μm. Furthermore, in an actual battery manufacturing facility, a coated electrode thicker than 150 μm requires a 100 meter long heating zone to completely dry the coated slurry. This greatly increases equipment costs and reduces manufacturing throughput. Due to the low areal density and low volume density (associated with thin electrodes and low packing density), the volume capacity of the battery cells is relatively low and the volume energy density is low.

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

  Accordingly, it is an object of the present invention to provide a rechargeable alkali metal-sulfur based on rational materials and battery designs that overcome or significantly reduce the following problems typically associated with conventional Li-S and Na-S cells: To provide a cell: (a) dendrite formation (internal short circuit); (b) very low electrical and ionic conductivity of sulfur. This requires a large proportion (typically 30-55%) of inert conductive filler and has a significant proportion of inaccessible or unreachable sulfur or alkali metal polysulfides; c) Dissolution of S and alkali metal polysulfides in the electrolyte and migration of the polysulfides from the cathode to the anode (which reacts irreversibly with Li or Na metal at the anode). This results in loss of active material and capacity decay (shuttle effect); (d) short cycle life; and (e) low active mass loading at both anode and cathode.

  A specific object of the present invention is to provide rechargeable alkali metal-sulfur batteries (eg, mainly Li-S and room temperature Na-S batteries) that exhibit very high specific energy or specific energy density. One particular technical goal of the present invention is (based on total cell weight) greater than 400 Wh / Kg, preferably greater than 500 Wh / Kg, more preferably greater than 600 Wh / Kg, most preferably 700 Wh / kg. It is to provide an alkali metal-sulfur or alkali ion-sulfur cell having a greater cell specific energy. Preferably, the volume energy density is greater than 600 Wh / L, more preferably greater than 800 Wh / L, and most preferably greater than 1,000 Wh / L.

  Another object of the present invention includes higher than 1200 mAh / g based on the weight of sulfur, or the cathode composite weight (sulfur, conductive additive or substrate, and binder weight combined, It is to provide an alkali metal-sulfur cell exhibiting a high cathode specific capacity higher than 1,000 mAh / g based on the weight of the cathode current collector). Preferably, the specific capacity is greater than 1,400 mAh / g based solely on sulfur weight, or greater than 1,200 mAh / g based on cathode composite weight. This entails high specific energy, good resistance to dendrite formation, and a long and stable cycle life.

  The present invention provides high cathode active material mass loading, thick cathode, high sulfur cathode specific capacity, very low overhead weight and volume (relative to active material mass and volume), high weight energy density, which could not be realized previously. And an alkali metal-sulfur battery having a high volumetric energy density. The present invention includes both lithium metal-sulfur cells and room temperature sodium metal-sulfur cells.

  Lithium-sulfur batteries include (a) Li metal or Li metal alloy (eg, Li foil) as the main anode active material and sulfur, polysulfide, and / or sulfur-carbon compound as the main cathode active material. (B) Lithium intercalation compounds (eg, graphite and Si) as the main anode active materials and sulfur, polysulfide as the main cathode active materials And / or lithium ion-sulfur cells that utilize sulfur-carbon compounds. A sodium-sulfur battery comprises (a) Na metal or Na metal alloy (eg, Na foil) as the main anode active material and sulfur, polysulfide, and / or sulfur-carbon compound as the main cathode active material. (B) sodium intercalation compounds (eg, hard carbon particles and Si) as the main anode active material and sulfur as the main cathode active material, Sodium ion-sulfur cells that utilize polysulfides and / or sulfur-carbon compounds.

In one embodiment, the battery of the present invention comprises
(A) (i) an anode active material slurry (or suspension) comprising an anode active material dispersed in a first electrolyte and an optional conductive additive, and (ii) acting as a 3D anode current collector Having a conductive porous structure, wherein the conductive porous structure has at least 70% by volume of pores, and an anode active material slurry is disposed within the pores of the anode conductive porous structure. The terms “anode conductive porous structure” and “3D anode current collector” are used interchangeably herein,
(B) (i) a cathode activity comprising a cathode active material and an optional conductive additive dispersed in a second electrolyte (preferably a liquid or gel electrolyte) that is the same as or different from the first liquid or gel electrolyte. A cathode having a material slurry and (ii) a conductive porous structure acting as a 3D cathode current collector, the conductive porous structure having at least 70% by volume of pores, wherein the cathode active material slurry Are disposed within the pores of the cathode conductive porous structure (the terms “cathode conductive porous structure” and “3D cathode current collector” are used interchangeably herein),
Cathode active material is sulfur bound to the pore wall of the cathode current collector, sulfur bound to or confined by carbon or graphite material, sulfur bound to polymer or confined by polymer , Sulfur-carbon compound, metal sulfide M _x S _y (where x is an integer of 1 to 3, y is an integer of 1 to 10, M is Li, Na, K, Mg, Ca, transition A cathode selected from a metal, a metal element selected from Group 13 to Group 17 metals of the periodic table, or combinations thereof; and (c) disposed between the anode and the cathode A separator is provided.

In this battery, the ratio of anode thickness to anode current collector thickness is 0.8 / 1 to 1 / 0.8 and / or the ratio of cathode thickness to cathode current collector thickness is 0.8 / 1. ~ 1 / 0.8. The 3D porous anode current collector or cathode current collector has a thickness of 200 μm or more, the cathode active material has an electrode active material loading of more than 10 mg / cm ² and / or the anode active material and the cathode The active material together exceeds 40% by weight of the total battery cell weight.

This alkali metal-sulfur battery can be manufactured by a method comprising (as an example) the following steps.
(A) a first conductive porous structure as a 3D anode current collector (eg, a conductive foam or an interconnected 3D network of electron conduction paths), a second conductivity as a 3D cathode current collector Assembling a porous cell framework comprised of a conductive porous structure (eg, conductive foam) and a separator disposed between the first and second conductive porous structures, The first and / or second conductive foam structure has a thickness of 200 μm or more (preferably more than 300 μm, preferably more than 400 μm, more preferably more than 500 μm, most preferably more than 600 μm) and a fineness of at least 70% by volume. Pores (preferably at least 80% porosity, more preferably at least 90%, most preferably at least 95%; these pore volumes are Representing the amount of pores before being impregnated with an active material slurry or suspension,
(B) a first suspension of an anode active material and optional conductive additive dispersed in a first liquid or gel electrolyte, and a cathode active material dispersed in a second liquid or gel electrolyte. And a second suspension of the optional conductive additive, and (c) preferably the anode active material has a material mass loading of 20 mg / cm ² or more in the anode, or cathode activity The pores of the first conductive porous structure are impregnated with the first suspension to an extent that the material has a material mass loading of 15 mg / cm ² or more in the cathode (eg, the first conductive A first suspension is injected into the pores of the porous structure to form an anode, and the pores of the second conductive porous structure are impregnated with the second suspension (eg, the second suspension). The second suspension is injected into the pores of the conductive foam structure of Forming a cathode.

  Before, during, or after the first suspension injection (or impregnation) and / or the second suspension injection (or impregnation), the anode current collector, separator, and cathode current collector are protected housings. Embedded in.

Another embodiment of the present invention is:
a) an anode having an anode active material coated on or in physical contact with the anode current collector, wherein the anode active material is in ionic contact with the first electrolyte;
b) (i) a cathode active material slurry or suspension comprising a cathode active material and an optional conductive additive dispersed in a second liquid or gel electrolyte that is the same as or different from the first liquid or gel electrolyte; (Ii) a cathode having a conductive porous structure acting as a 3D cathode current collector, wherein the conductive porous structure is at least 70% by volume (preferably at least 80%, more preferably at least 90%) The cathode active material slurry is disposed within the pores of the cathode conductive porous structure, and the cathode active material is sulfur, lithium polysulfide, sodium polysulfide, sulfur-polymer composite, organo A cathode selected from sulfides, sulfur-carbon composites, sulfur-graphene composites, or combinations thereof; and c) an anode In an alkali metal-sulfur battery comprising a separator disposed between a cathode and a cathode,
The ratio of cathode thickness to cathode current collector thickness is 0.8 / 1 to 1 / 0.8 and / or the cathode active material has an electrode active material loading greater than 15 mg / cm ² , An alkali metal-sulfur battery in which the current collector has a thickness of 200 μm or more (preferably more than 300 μm, more preferably more than 400 μm, even more preferably more than 500 μm, most preferably more than 600 μm). There is no theoretical limit to the thickness of the conductive porous structure. A thicker porous structure (or porous current collector) suggests a higher amount of electrode active material. Assuming the same separator layer, and approximately the same packaging envelope and other inactive components, this thicker electrode also suggests a relatively high proportion of active material and thus a higher energy density.

  In alkali metal-sulfur batteries (eg, the anode active material is Li foil or Na foil), the anode current collector may include a porous foam structure. In an alkali metal-sulfur battery, the first electrolyte may be a gel electrolyte or a solid electrolyte.

  In certain embodiments, the cathode active material is supported by a functional material or nanostructured material selected from the group consisting of: (A) Nanostructured selected from soft carbon, hard carbon, polymeric carbon or carbonized resin, mesophase carbon, coke, carbonized pitch, carbon black, activated carbon, nanocell carbon foam, or partially graphitized carbon Or a porous disordered carbon material; (b) nanographene platelets selected from single-layer graphene sheets or multilayer graphene platelets; (c) carbon nanotubes selected from single-walled carbon nanotubes or multi-walled carbon nanotubes; (d) Carbon nanofibers, nanowires, metal oxide nanowires or fibers, conductive polymer nanofibers, or combinations thereof; (e) carbonyl-containing organic or polymer molecules; (f) carbonyl groups, carboxyl groups for irreversibly trapping sulfur Or Ami And combinations thereof; functional materials containing groups.

  In certain embodiments, the anode active material is an alkali ion source selected from alkali metals, alkali metal alloys, alkali metals or mixtures of alkali metal alloys and alkali intercalation compounds, alkali element-containing compounds, or combinations thereof including.

In some embodiments (eg, Li ion-sulfur or sodium ion-sulfur cell), the anode active material is petroleum coke, carbon black, amorphous carbon, activated carbon, hard carbon, soft carbon, template carbon, hollow carbon nanowire. , Hollow carbon sphere, natural graphite, artificial graphite, lithium or sodium titanate, 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), Na 2 C} 8 H 4 O 4, carboxylate-based _{material, C 8 H 4 Na 2 O} 4, C 8 H 6 O 4, C 8 H 5 NaO 4, _{C 8 Na 2 F 4 O 4} , C 10 H 2 Na 4 O 8, C 14 H 4 O 6, C 14 H 4 Na 4 O 8 or alkaline interface selected from combinations thereof, Including the intercalation compound.

  In some embodiments, the anode active material comprises (A) lithium or 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; (B) Si, Ge, Sn, Lithium or sodium-containing alloys or intermetallic compounds of Pb, Sb, Bi, Zn, Al, Ti, Co, Ni, Mn, Cd, and mixtures thereof; (C) Si, Ge, Sn, Pb, Sb, Bi, Zn, Al, Fe, Ti, Co, Ni, Mn, Cd, and mixtures or composites thereof containing lithium or sodium oxides, carbides, nitrogen Alkaline intercalation selected from the group consisting of oxides, sulfides, phosphides, selenides, tellurides, or antimonides; (D) lithium or sodium salts; and (E) graphene sheets preloaded with lithium or sodium Or an alkali-containing compound.

  Graphene sheets preloaded with lithium or sodium were pure graphene, graphene oxide, reduced graphene oxide, graphene fluoride, graphene chloride, graphene bromide, graphene iodide, graphene hydride, graphene nitride, boron doped Selecting from pre-sodiumized or pre-lithiated versions of graphene, nitrogen-doped graphene, chemically functionalized graphene, physically or chemically activated or etched versions thereof, or combinations thereof Can do.

The first or second electrolyte can be selected from an aqueous electrolyte, an organic electrolyte, an ionic liquid electrolyte, a mixture of an organic electrolyte and an ionic electrolyte, or a mixture of them and a polymer. In one embodiment, the aqueous electrolyte comprises a sodium or potassium salt dissolved in water or a mixture of water and alcohol. The sodium or lithium salt can be selected from Na ₂ SO ₄ , Li ₂ SO ₄ , NaOH, LiOH, NaCl, LiCl, NaF, LiF, NaBr, LiBr, NaI, LiI, or mixtures thereof.

  Alkali metal-sulfur batteries include 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), γ-butyrolactone (γ-BL), acetonitrile (AN), ethyl acetate (EA), propyl formate (PF), methyl formate (MF), toluene, xylene, methyl acetate (MA), fluoroethylene carbonate ( FEC), vinylene carbonate (VC), allyl ethyl carbonate (AEC), hydrofluoroethers, and organic electrolytes having a liquid organic solvent selected from the group consisting of combinations thereof.

The electrolyte in the alkali metal-sulfur battery is lithium perchlorate (LiClO ₄ ), lithium hexafluorophosphate (LiPF ₆ ), lithium borofluoride (LiBF ₄ ), lithium hexafluoroarsenate (LiAsF ₆ ), trifluoro - lithium methanesulfonic acid _(LiCF 3 _SO 3), bis - trifluoromethyl sulfonyl imide lithium _{(LiN (CF 3 SO 2)} 2), lithium bis (oxalato) borate (LiBOB), lithium oxalyl difluoro borate (LiBF ₂ C ₂ O ₄ ), lithium oxalyl difluoroborate (LiBF ₂ C ₂ O ₄ ), lithium nitrate (LiNO ₃ ), Li-fluoroalkyl phosphate (LiPF ₃ (CF ₂ CF ₃ ) ₃ ), lithium bisperfluoroethisulfonyl-imide ( LiBE TI), sodium perchlorate (NaClO ₄ ), potassium perchlorate (KClO ₄ ), sodium hexafluorophosphate (NaPF ₆ ), potassium hexafluorophosphate (KPF ₆ ), sodium borofluoride (NaBF ₄ ) , Potassium borofluoride (KBF ₄ ), sodium hexafluoroarsenate, potassium hexafluoroarsenate, sodium trifluoro-metasulfonate (NaCF ₃ SO ₃ ), potassium trifluoro-metasulfonate (KCF ₃ SO ₃ ), bis - trifluoromethylsulfonyl imide sodium _{(NaN (CF 3 SO 2)} 2), trifluoromethane sulfonimide sodium (NaTFSI), bis - trifluoromethyl sulfonyl imide potassium _{(KN (CF 3 SO 2)} 2), or a combination thereof Alkali metal selected from Which may include.

Alkali metal-sulfur batteries are made from tetra-alkyl ammonium, di-, tri-, or tetra-alkyl imidazolium, alkyl pyridinium, dialkyl-pyrrolidinium, dialkyl piperidinium, tetraalkyl phosphonium, trialkyl sulfonium, or combinations thereof. An ionic liquid electrolyte comprising an ionic liquid solvent selected from room temperature ionic liquids having selected cations may be included. The ionic liquid solvents are BF ₄ ⁻ , B (CN) ₄ ⁻ , CH ₃ BF ₃ ⁻ , CH ₂ CHBF ₃ ⁻ , CF ₃ BF ₃ ⁻ , C ₂ F ₅ BF ₃ ⁻ , n-C ₃ F ₇ BF ^{_{3 -, n-C 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 those Can be selected from room temperature ionic liquids having anions selected from:

  The conductive porous structure may be a foam structure that includes interconnected 2D or 3D networks of electronic conduction paths. This may be, for example, a 2D mat, web, chicken wire-like metal screen connected at the ends, as shown in FIG. This may also be a metal foam, a conductive polymer foam, a graphite foam, a carbon foam, a graphene foam or the like, where the pore walls comprise a conductive material.

  In a preferred embodiment, as shown in FIG. 1 (C) or FIG. 1 (D), the 3D porous anode current collector extends to and is in physical contact with the edge of the porous separator layer. ing. The 3D porous conductive cathode current collector may also extend to the opposite edge of the porous separator and be in physical contact with the edge. In other words, the pore wall of the anode current collector covers the entire anode layer and / or the pore wall of the cathode current collector covers the entire cathode layer. In these configurations, the current collector thickness / active material layer thickness ratio is approximately 1/1, and the electrode thickness is essentially the same as the current collector thickness (the cathode thickness and The ratio of the thickness of the cathode current collector is about 1, and the ratio of the thickness of the anode to the thickness of the anode current collector is about 1). In such a situation, the conductive pore wall is in the immediate vicinity of any anode active material particles or any cathode active material particles.

  In certain embodiments, the ratio of current collector thickness / active material layer thickness can be about 0.8 / 1.0 to 1.0 / 0.8. In other words, the ratio of the thickness of the cathode to the thickness of the cathode current collector is 0.8 / 1 to 1 / 0.8, and the ratio of the thickness of the anode to the thickness of the anode current collector is 0. 8/1 to 1 / 0.8. In conventional lithium ion or sodium ion batteries (schematically illustrated in FIGS. 1A and 1B), the anode (or cathode) current collector is typically 8-12 μm thick. Cu foil (or Al foil). The anode active material layer coated on the Cu foil surface is typically 80-100 μm. Thus, the ratio of anode current collector thickness / anode active material layer thickness is typically between 8/100 and 12/80. The ratio of current collector thickness / active material layer thickness on the cathode side of a conventional Li ion or Na ion cell is also about 1 / 12.5 to 1 / 6.7. In contrast, in the battery according to the present invention, the ratio is 0.8 / 1 to 1 / 0.8, more preferably 0.9 / 1 to 1 / 0.9, and still more preferably 0.95 / 1 to 1. /0.95, most desirably typically 1/1.

  The pore volume (eg,> 70%) of the foamable current collector is a very important requirement to ensure that a large percentage of the active material is accommodated in the current collector. Based on this criterion, conventional papers or fabrics formed from natural and / or synthetic fibers do not meet this requirement because they do not have a sufficient amount of appropriately sized pores.

  The pore size of the first and / or second conductive porous structure is preferably 10 nm to 100 μm, more preferably 100 nm to 50 μm, more preferably 500 nm to 20 μm, still more preferably 1 μm to 10 μm, and most preferably 1 μm to It is in the range of 5 μm. These pore size ranges are designed to accommodate anode active materials (such as carbon particles) and cathode active materials (such as sulfur / graphene composition particles), typically 10 nm to 20 μm in diameter, most typically It has a primary or secondary particle size of 50 nm to 10 μm, more typically 100 nm to 5 μm, and most typically 200 nm to 3 μm.

  More importantly, however, all active material particles in the pores (eg having a pore size of 5 μm) are on average within a distance of 2.5 μm from the pore walls of the 3D foam structure, so that the anode active material Electrons can be easily collected from the particles, and there is no need for Na or Li ions to undergo long-range solid diffusion. This is because in a conventional thick electrode of a prior art lithium ion battery or sodium ion battery (eg, a 100 μm thick graphite particle layer is coated on the surface of a 10 μm thick solid Cu foil current collector). In contrast to the view that some electrons must travel at least 50 μm to be collected by the current collector (meaning greater internal resistance and reduced ability to deliver higher power) It is.

  In general, in a battery, the first liquid electrolyte and the second liquid electrolyte are the same, but the composition may be different. The liquid electrolyte can be an aqueous liquid, an organic liquid, an ionic liquid (an ionic salt having a melting temperature lower than 100 ° C., preferably lower than room temperature 25 ° C.), or an ionic liquid in a ratio of 1/100 to 100/1. And a mixture of organic liquids. An organic liquid is desirable, but an ionic liquid is preferred. Gel electrolytes can also be used, assuming that the electrolyte has some fluidity that allows injection. A small amount of 0.1% to 10% can be incorporated into the liquid electrolyte.

In certain embodiments, the 3D porous anode current collector or 3D porous cathode current collector comprises a conductive foam structure having a thickness of 200 μm or more having at least 85% by volume pores and / or an anode The active material has a mass loading of 20 mg / cm ² or more, occupies at least 25% by weight or volume% of the entire battery cell, and / or the cathode active material has a mass loading of 20 mg / cm ² or more. .

In some preferred embodiments, the 3D porous anode current collector or 3D porous cathode current collector comprises a conductive foam structure having a thickness of 300 μm or more with at least 90% by volume pores, and / or Or the anode active material has a mass loading of 25 mg / cm ² or more and occupies at least 30% by weight or volume% of the total battery cell, and / or the cathode active material has a mass loading of 25 mg / cm ² or more. Have

In some further preferred embodiments, the 3D porous anode current collector or 3D porous cathode current collector comprises a conductive foam structure having a thickness of 400 μm or more having at least 95% by volume pores, and The anode active material has a mass loading of 30 mg / cm ² or more, occupies at least 35% by weight or volume% of the entire battery cell, and / or the cathode active material has a mass loading of 30 mg / cm ² or more. Have quantity.

  3D porous anode current collector or 3D porous cathode current collector includes metal foam, metal web or screen, perforated metal sheet-based 3D structure, metal fiber mat, metal nanowire mat, conductive polymer nanofiber mat , Conductive polymer foam, conductive polymer coated fiber foam, carbon foam, graphite foam, carbon aerogel, carbon xerogel, graphene foam, graphene oxide foam, reduced graphene oxide foam, carbon fiber foam, graphite It may include a conductive foam structure selected from fiber foam, exfoliated graphite foam, or combinations thereof.

FIG. 1A shows a prior art Li-S or an anode current collector, an anode electrode (eg, Li foil or thin Sn coating layer), a porous separator, a cathode electrode, and a cathode current collector. It is the schematic of a Na-S battery cell. FIG. 1B is a schematic diagram of a prior art sodium ion battery where the electrode layer is composed of discrete particles of active material (eg, hard carbon particles in the anode layer or polysulfide particles in the cathode layer). is there. FIG. 1C shows a lithium-sulfur according to the present invention comprising an anode current collector in the form of a high porosity foam, a porous separator, and a cathode current collector in the form of a high porosity foam. Or it is the schematic of a sodium-sulfur battery cell. The suspension is injected or impregnated into the pores of the two current collectors. For illustration, half of the pores are filled. FIG. 1 (D) shows an Na current collector according to the present invention comprising an anode current collector in the form of a highly conductive porous foam, a porous separator, and a cathode current collector in the form of a high porosity foam. It is the schematic of an ion-sulfur or Li ion-sulfur battery cell. The pores of the two foamable current collectors are impregnated with the respective suspensions. FIG. 1 (E) comprises an anode current collector comprising a layer of Na or Li metal or an alloy deposited thereon, a porous separator, and a cathode current collector in the form of a high porosity foam. 1 is a schematic view of a Na metal-sulfur or Li metal-sulfur battery cell according to the present invention. FIG. The pores of the foamable current collector are impregnated with the cathode-electrolyte suspension. FIG. 2 shows an exemplary foam or construction composed of five high porosity 2D webs (eg, a thin 2D structure in the form of chicken wire) connected at the ends (electrical terminals) to form a tab. It is the schematic of a porous electrical power collector. FIG. 3A is a diagram showing an example of a conductive porous layer: a metal grid / mesh and a carbon nanofiber mat. FIG. 3B is a diagram showing an example of a conductive porous layer: graphene foam and carbon foam. FIG. 3C is a diagram showing examples of the conductive porous layer: graphite foam and Ni foam. FIG. 3D is a diagram showing examples of the conductive porous layer: Cu foam and stainless steel foam. FIG. 4A produces exfoliated graphite, expanded graphite flakes (thickness> 100 nm), and graphene sheets (thickness <100 nm, more typically <10 nm, may be as thin as 0.34 nm). FIG. 2 is a schematic diagram of a commonly used method for FIG. 4B is a schematic view showing a method for producing exfoliated graphite, expanded graphite flakes, and graphene sheets. FIG. 5 shows a Ragone plot (weight and volume power density versus energy density) of a Na ion-sulfur battery cell containing hard carbon particles as the anode active material and carbon / sodium polysulfide particles as the cathode active material. is there. Two of the four data curves are for cells prepared in accordance with embodiments of the present invention and the other two are by conventional slurry coating (roll coating) of the electrodes. FIG. 6 is a diagram showing a Ragone plot (weight and volume power density vs weight and volume energy density) of two Na-S cells. Both Na-S cells contain graphene-encapsulated Na nanoparticles as the anode active material and sulfur coated on the graphene sheet as the cathode active material. The data relates to both sodium ion cells prepared by the method according to the invention and sodium ion cells with conventional electrode slurry coatings. FIG. 7 is a graph showing a Ragone plot of a Li-S battery including lithium foil as an anode active material, graphene sheet-supported sulfur as a cathode active material, and lithium salt (LiPF ₆ ) -PC / DEC as an organic liquid electrolyte. It is. The data relates to both a lithium metal-sulfur cell prepared by the method according to the invention and a lithium metal-sulfur cell with a conventional electrode slurry coating. FIG. 8 shows a Ragone plot of a series of Li-ion-S cells (graphene wrapped Si nanoparticles) prepared by a conventional slurry coating process and a corresponding Ragone plot prepared by the process of the present invention. is there. FIG. 9 shows a Li ion-S cell plotted over a feasible cathode thickness range of an S / RGO cathode prepared by a conventional method without delamination and cracking and an S / RGO cathode according to the present invention ( It is a figure which shows the cell level weight energy density (Wh / kg) and volume energy density (Wh / L) of a prelithiated graphite anode + graphene carrying | support S cathode.

  The present invention is directed to alkali metal-sulfur batteries (Li-S or room temperature Na-S) that exhibit very high volumetric energy densities not previously achieved with batteries of the same type. This does not include so-called high temperature Na-S cells which must operate at temperatures above the melting point of the electrolyte (typically> 350 ° C.) and above the melting point of sulfur. The alkali metal battery may be a primary battery, but an alkali metal ion battery (for example, using a Li or Na intercalation compound such as hard carbon particles) or an alkali metal secondary battery (for example, a Na or Li metal foil). It is preferably a secondary battery selected from (used as an anode active material). The battery is based on an aqueous electrolyte, an organic electrolyte, a gel electrolyte, an ionic liquid electrolyte, or a mixture of an organic liquid and an ionic liquid. The shape of the alkali metal battery may be a cylindrical shape, a square shape, a button shape or the like. The present invention is not limited to any battery shape or configuration.

As shown in FIGS. 1A and 1B, conventional lithium ion, sodium ion, Li—S, or Na—S battery cells typically have an anode current collector (eg, Cu foil). ), An anode electrode (anode active material layer), a porous separator and / or an electrolyte component, a cathode electrode (cathode active material layer), and a cathode current collector (eg, Al foil). In the more commonly used cell configuration (FIG. 1B), the anode layer comprises an anode active material (eg, hard carbon particles), a conductive additive (eg, expanded graphite flakes), and a resin binder (eg, SBR or PVDF). The cathode layer comprises a cathode active material (eg, NaFePO ₄ particles in a Na ion cell, or S-carbon composite particles in a Li-S cell), a conductive additive (eg, carbon black particles), and a resin binder (eg, PVDF) particles. Both the anode and cathode layers are typically 60-100 μm thick (typically much thinner than 200 μm) to produce a probably sufficient amount of current per unit electrode area. . Using as an example an active material layer thickness of 100 μm and a solid (Cu or Al foil) current collector layer thickness of 10 μm, the resulting battery configuration is the current collector thickness and active material in a conventional battery cell. The ratio to the layer thickness is 10/100, ie 1/10.

  This thickness range of 60-100 μm is accepted in the industry, where battery designers typically work based on current slurry coating methods (active material-binder-additive mixed slurry roll coating). It is considered that there are constraints. This thickness constraint is due to several reasons: (a) existing battery electrode coating machines are not equipped to coat very thin or very thick electrode layers. (B) a thinner layer is preferred in view of the shortened lithium ion diffusion path length; however, if the layer is too thin (eg <60 μm), it does not contain a sufficient amount of active alkali metal ion storage material (and therefore (C) Thicker electrodes are prone to delamination or cracking during drying or handling after slurry roll coating; and (d) Thicker coatings can cause very long heating zones. Needed (it is not uncommon to have a heating zone longer than 100 meters, which makes the manufacturing equipment very expensive). This constraint increases the amount of all inactive materials (eg current collector and separator) in order to obtain minimum overhead weight and maximum sodium storage capacity and thus maximum energy density (cell Wk / kg or Wh / L) It is impossible to freely increase the amount of active material (which serves to store Na or Li ions) without it.

In a less commonly used cell configuration, an anode active material (eg, NaTi ₂ (PO ₄ ) ₃ or Na film) or a cathode active material (eg, a Li-ion cell), as shown in FIG. Or a lithium transition metal oxide in a sulfur / carbon mixture in a Li-S cell) is deposited in the form of a thin film directly on a current collector such as a copper foil or Al foil utilizing sputtering. However, such thin film structures with very small thickness dimensions (typically much smaller than 500 nm, often thinner than 100 nm if necessary) have the same surface area of the electrode or current collector. (Assuming that) only a small amount of active material can be incorporated into the electrode, reducing the total Na or Li storage capacity per unit electrode surface area. Such thin films must be less than 100 nm in thickness to be more resistant to cycling-induced cracking (with respect to the anode) or to facilitate full utilization of the cathode active material. Such constraints further reduce total Na or Li storage capacity and sodium or lithium storage capacity per unit electrode surface area. Such thin film batteries have a very limited scope of application.

On the anode side, a sputtered NaTi ₂ (PO ₄ ) ₃ layer thicker than 100 nm has been found to have low crack resistance during the charge / discharge cycle of the battery. It will be crushed in just a few cycles. On the cathode side, a layer of sulfur thicker than 100 nm does not allow lithium or sodium ions to penetrate completely and reach the entire cathode layer, resulting in low cathode active material utilization. The desired electrode thickness is at least 100 μm (not 100 nm) and the individual active material particles desirably have dimensions of less than 100 nm. Therefore, these thin film electrodes (having a thickness <100 nm) deposited directly on the current collector are less than three orders of magnitude in required thickness. As a further problem, all cathode active materials are not conductive to both electrons and sodium / lithium ions. Large layer thickness suggests very high internal resistance and low active material utilization.

  That is, there are several conflicting factors that must be considered simultaneously in the design and selection of the cathode or anode active material in terms of material type, size, electrode layer thickness, and active material mass loading. To date, there is no effective solution provided by any prior art teaching for these often conflicting problems. As disclosed herein, the inventors have plagued battery designers and also electrochemists for over 30 years by developing new methods of manufacturing alkali metal-sulfur batteries. Solved these challenges.

Prior art sodium or lithium battery cells are typically manufactured by a method comprising the following steps: (a) The first step comprises anode active material (eg, hard carbon particles), conductive filler ( For example, expanded graphite flakes) and particles of resin binder (eg, PVDF) are mixed in a solvent (eg, NMP) to form an anode slurry. Separately, cathode active material (eg, sodium phosphate metal particles in Na-ion cells and LFP particles in Li-ion cells), conductive filler (eg, acetylene black), and resin binder (eg, PVDF) particles Are mixed and dispersed in a solvent (eg, NMP) to form a cathode slurry. (B) The second step is to coat the anode slurry on one or both major surfaces of the anode current collector (eg Cu foil) and dry the coated layer by evaporating the solvent (eg NMP) And forming a dry anode electrode coated on the Cu foil.
Similarly, the cathode slurry is coated and dried to form a dry cathode electrode coated on the Al foil. In actual 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, the porous separator layer, and the cathode / Al foil sheet together. Form a three-layer or five-layer assembly and cut it into desired sizes or tear and laminate to form a rectangular structure (as an example of shape) or roll it into a cylindrical cell structure Including doing. (D) The rectangular or cylindrical laminated structure is then housed in an aluminum plastic laminated envelope or steel casing. (E) Next, a liquid electrolyte is injected into the laminated structure to manufacture sodium ions or lithium battery cells.

There are several significant problems associated with this method and the resulting sodium and lithium ion battery cells (or Li-S and Na-S cells).
1) It is very difficult to produce an electrode layer (anode layer or cathode layer) thicker than 100 μm and even thicker than 200 μm. There are several reasons for this. A 100 μm thick electrode typically requires a 30-100 meter long heating zone in a slurry coating facility, which is too time consuming, too energy consuming and not cost effective. For some electrode active materials such as metal oxide particles or sulfur, electrodes with good structural integrity thicker than 100 μm cannot be manufactured continuously in an actual manufacturing environment. The resulting electrode is 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 electrode and the apparent density with respect to the active material are too low to achieve high energy density. Mostly, even for relatively large graphite particles, the anode active material mass load (area density) of the electrode is much lower than 15 mg / cm ^{2 and} the apparent volume density or tap density of the active material is typically 1.2 g. / Cm ^{3 or} less. The cathode active material mass load (area density) of the electrode is substantially lower than 10 mg / cm ^{2 for the} sulfur cathode. In addition, there are numerous other inactive materials (eg, conductive additives and resin binders) that add additional weight and volume to the electrode without contributing to battery capacity. These low areal and low volume densities result in a relatively low weight energy density and low volume energy density.
3) Conventional methods require that the electrode active materials (anode active material and cathode active material) be dispersed in a liquid solvent (eg, NMP) to form a slurry, and the liquid solvent is applied after coating on the current collector surface. It must be removed and the electrode layer dried. After the anode and cathode layers are laminated with the separator layer and packaged in a housing to form a supercapacitor cell, a liquid electrolyte is injected into the cell (using a salt dissolved in a solvent different from NMP). To do. In practice, the two electrodes are wetted, then the electrodes are dried and finally wetted again. Such a wet-dry-wet method is not a good process. Furthermore, the most commonly used solvent (NMP) is a well-known undesirable solvent (eg, known to cause congenital anomalies).
4) Current Li-S and Na-S batteries still have the problem of relatively low weight energy density and low volumetric energy density. Therefore, neither Li-S nor room temperature Na-S batteries are on the market.

  In the literature, the energy density of a practical battery cell or device cannot be directly derived from energy density data reported based on active material weight alone or electrode weight. "Overhead weight", i.e., the weight of other device components (binder, conductive additive, current collector, separator, electrolyte, and packaging) must also be taken into account. In conventional manufacturing methods, the weight ratio of anode active material (eg, carbon particles) in a sodium ion battery is typically 15% to 20% and the weight of cathode active material (eg, sodium transition metal oxide). The ratio is 20% to 30%.

The present invention provides high electrode thickness (thickness of electrode with electrode active material; does not include thickness of current collector layer without active material (if present)), high active material mass load, low overhead weight. And a method for manufacturing Li-S or Na-S battery cells having high volume, high volume capacitance, and high volumetric energy density. In one embodiment, as shown in FIG. 1 (C) and FIG. 1 (D), the method of the present invention includes:
(A) The first conductive porous or foam structure 236 as the anode current collector, the second conductive porous or foam structure 238 as the cathode current collector, and the first and second conductive pores A porous cell framework composed of a porous separator 240 disposed between the porous structures is assembled.
a. The first and / or second conductive porous structure has a thickness of 100 μm or more (preferably greater than 200 μm, more preferably greater than 300 μm, even more preferably greater than 400 μm, and most preferably greater than 500 μm), and at least 70 volumes. % Pores (preferably a porosity of at least 80% by volume, more preferably at least 90% by volume, and most preferably at least 95% by volume).
b. These conductive porous structures essentially have a porosity level of 70% to 99%, with the remaining 1% to 30% being pore walls (eg, metal or graphite skeleton). These pores are used to contain a mixture of active material (eg, carbon particles in the anode + optional conductive additive) and a liquid electrolyte.
(B) a first suspension (or slurry) of anode active material and optional conductive additive dispersed in a first liquid electrolyte and a cathode active material dispersed in a second liquid electrolyte. And a second suspension (slurry) of optional conductive additives.
(C) Injecting or impregnating the first suspension into the pores of the first conductive porous structure to form an anode, and the second suspension in the pores of the second conductive foam structure A liquid is injected or impregnated to form a cathode, whereby the anode active material is 20 mg / cm ² or more (preferably 25 mg / cm ² or more, and more preferably 30 mg / cm ² or more) in the anode. An active material mass load of at least 10 mg / cm ² (preferably greater than 15 mg / cm ² , and more preferably greater than 20 mg / cm ² ) with respect to the active material load or the cathode active material with respect to the sulfur-based cathode active material Where the anode, separator, and cathode are assembled in a protective housing.
a. It is preferred that substantially all of the pores are filled with an electrode (anode or cathode) active material, an optional conductive additive, and a liquid electrolyte (no binder resin is required).
b. Since the amount of pores is large (70 to 99%) with respect to the pore walls (1 to 30%), there is almost no wasted space ("waste" means that the electrode active material and the electrolyte are not occupied. As a result, a large amount of electrode active material-electrolyte zone (high active material loading mass) is obtained.
c. Shown in FIG. 1 (C) is a conductive porous structure for the anode (3D anode current collector 236) comprising a first suspension (anode active material dispersed in a liquid electrolyte and optional It is in a state of being partially filled with a selected conductive additive). The upper portion 240 of the anode current collector foam 236 remains empty, while the lower portion 244 is filled with the anode suspension. Similarly, the upper portion 242 of the cathode current collector foam 238 remains empty and the lower portion 246 is filled with a cathode suspension (cathode active material dispersed in a liquid electrolyte). Four arrows represent the injection direction of the suspension.

  FIG. 1D shows a situation where both the anode current collector foam and the cathode current collector foam are filled with the respective suspensions. As an example, the foam holes 250 (enlarged view) are filled with an anode suspension containing hard carbon particles 252 (anode active material) and a liquid electrolyte 254. Similarly, the foam holes 260 (enlarged view) are filled with a cathode suspension containing carbon-coated sulfur or polysulfide particles 262 (cathode active material) and a liquid electrolyte 264.

  An alternative configuration schematically shown in FIG. 1 (E) is a sodium metal or lithium metal battery cell according to the present invention, comprising a layer of Na or Li metal 282 or a Na / Li metal alloy deposited thereon. A current collector 280, a porous separator, and a cathode current collector in the form of a high porosity foam. The pores 270 of the foamable current collector are impregnated with a suspension of the cathode active material 272 and the liquid electrolyte 274.

  In such a configuration (FIGS. 1 (C)-(E)), the pore walls exist throughout the entire current collector (and also the entire anode layer), so electrons are short distances (on average half the pore diameter). If it moves by a few micrometers, for example, it is collected by the current collector (pore wall). Furthermore, in each suspension, all electrode active material particles are predispersed in a liquid electrolyte (no electrolyte wettability issues) and prepared by conventional methods of wet coating, drying, filling, and electrolyte injection. Eliminate the presence of dry pockets that are generally present in Thus, the method according to the present invention produces a completely unexpected advantage over conventional battery cell manufacturing methods.

  In preferred embodiments, the anode active material is pure graphene, graphene oxide, reduced graphene oxide, graphene fluoride, graphene chloride, graphene bromide, graphene iodide, graphene hydride, nitrogenated graphene, chemically functionalized graphene, or A pre-sodiumized or pre-lithiated version of the graphene sheet selected from their combination. Starting graphene materials for producing any one of the above graphene materials are natural graphite, artificial graphite, mesophase carbon, mesophase pitch, mesocarbon microbeads, soft carbon, hard carbon, coke, carbon fiber, carbon nanofiber , Carbon nanotubes, or combinations thereof. Graphene material is also a good conductive additive for both the anode and cathode active materials of alkaline metal batteries.

  Assuming that the interplane van der Waals force can be overcome, the constituent graphene surfaces of graphite crystals in natural or artificial graphite particles are exfoliated, extracted or isolated, and individual graphenes of hexagonal carbon atoms Sheets can be obtained and these sheets are monoatomic thick. Individual isolated graphene surfaces of carbon atoms are commonly referred to as single layer graphene. A stack of a plurality of graphene surfaces bonded by van der Waals forces with a graphene surface spacing of about 0.3354 nm in the thickness direction is generally referred to as multilayer graphene. Multilayer graphene platelets can have up to 300 graphene faces (thickness less than 100 nm), but more typically up to 30 layers of graphene face (thickness less than 10 nm), and even more typically up to 20 layers. It has a graphene surface (thickness less than 7 nm), and most typically up to 10 layers of graphene surfaces (commonly referred to in the scientific community as several layers of graphene). Single layer graphene and multilayer graphene sheets are collectively referred to as “nanographene platelets” (NGP). Graphene sheets / platelets (collectively NGP) are a new class of carbon nanomaterials (2D nanocarbons) different from 0D fullerene, 1D CNT or CNF, and 3D graphite. For the purposes of defining the claims and as generally understood in the art, graphene materials (isolated graphene sheets) are not carbon nanotubes (CNT) or carbon nanofibers (CNF) (they Not included).

In one method, as shown in FIG. 4 (A) and FIG. 4 (B) (schematic diagram), the graphene material is obtained by intercalating natural graphite particles with a strong acid and / or oxidizing agent. It is obtained by obtaining a compound (GIC) or graphite oxide (GO). The presence of chemical species or functional groups in the interstitial spaces between the graphene surfaces in GIC or GO serves to increase the graphene spacing (d ₀₀₂ ; determined by X-ray diffraction), thereby For example, the van der Waals force that integrally holds the graphene surface along the c-axis direction is greatly reduced. GIC or GO is a natural graphite powder (reference number 100 in FIG. 4B) in a mixture of sulfuric acid, nitric acid (oxidant), and another oxidant (eg, potassium permanganate or sodium perchlorate). Is most often produced by soaking. If an oxidant is present during the intercalation procedure, the resulting GIC (102) is actually some kind 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, which is discrete and visually distinguishable dispersed in water. Containing graphite oxide particles. To make the graphene material, one of two processing routes can be followed after this rinsing step, which is 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 expanded graphite is exposed to temperatures typically in the range of 800 to 1,050 ° C. for about 30 seconds to 2 minutes, the GIC expands rapidly by a factor of 30 to 300 times, resulting in a “graphite worm” (104) Form. Each graphite worm (104) is a collection of graphite flakes that are exfoliated but hardly separated and remain interconnected.

  In Route 1A, these graphite worms (exfoliated graphite or “network of interconnected / unseparated graphite flakes”) are compressed again, typically 0.1 mm (100 μm) to 0.5 mm. A flexible graphite sheet or foil (106) having a thickness in the range of (500 μm) can be obtained. Alternatively, graphite may be produced using a low-strength air mill or shear to produce so-called “expanded graphite flakes” (108) that primarily comprise graphite flakes or platelets thicker than 100 nm (and thus not nanomaterials by definition). It is also possible to choose to simply crush the worm.

  In Route 1B, as disclosed in commonly assigned US patent application Ser. No. 10 / 858,814 (March 6, 2004), exfoliated graphite is (eg, ultrasonic equipment, high Subjected to high strength mechanical shear (using a shear mixer, high strength air jet mill, or high energy ball mill) to form separated single and multilayer graphene sheets (collectively referred to as NGP 112). While single layer graphene can be as thin as 0.34 nm, multilayer 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 single sheet of NGP paper using a papermaking process. This NGP paper is an example of a porous graphene structure 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 graphite oxide particles. This is because the distance between the graphene surfaces is increased from 0.3354 nm in natural graphite to 0.6 to 1.1 nm in highly oxidized graphite, and van der Waals holding the adjacent surfaces together It is based on the view that it weakens the power significantly. The ultrasonic power may be sufficient to further separate the graphene face sheet to form a completely separated, isolated or discrete graphene oxide (GO) sheet. These graphene oxide sheets can then be chemically or thermally reduced to give “reduced graphene oxide” (RGO), typically 0.001% to 10% by weight, More typically it has an oxygen content of 0.01 wt% to 5 wt%, most typically and preferably contains less than 2 wt% oxygen.

  For the purposes of defining the claims of this application, NGP or graphene materials are composed of single and multilayer (typically less than 10) pure graphene, graphene oxide, reduced graphene oxide (RGO), graphene fluoride Graphene chloride, graphene bromide, graphene bromide, graphene iodide, graphene hydride, graphene nitride, chemically functionalized graphene, discrete sheets / platelets of doped graphene (eg, doped with B or N). 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 0.001 wt% to 50 wt% oxygen. 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.). In this specification, these materials are referred to as impure graphene materials.

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

Graphene oxide (GO) is produced in a reaction vessel at a desired temperature over a period of time (typically 0.5 to 96 hours depending on the nature of the starting material and the type of oxidizing agent used). Or a filament (eg, natural graphite powder) can be obtained by dipping in an oxidizing liquid medium (eg, a mixture of sulfuric acid, nitric acid, and potassium permanganate). As described above, the resulting oxidized graphite particles can then be subjected to thermal exfoliation or ultrasonic induced exfoliation to produce an isolated GO sheet. These GO sheets can then be converted to various graphene materials by substituting OH groups with other chemical groups (eg, Br, NH _2, etc.).

In this specification, fluorinated graphene or graphene fluoride is used as an example of the halogenated graphene material group. There are two different approaches that have been employed 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 XeF ₂ or F-based plasma. (2) Peeling of multilayer fluorinated graphite: Both mechanical peeling and liquid phase peeling of fluorinated graphite can be easily achieved.

Graphite intercalation compound (GIC) C _x F (2 ≦ x ≦ 24) is produced at low temperature, whereas the interaction between F ₂ and graphite at high temperature is due to covalently bonded graphite fluoride (CF) resulting in _n or (C ₂ F) _n . In (CF) _n , the carbon atoms are sp3 hybridized, so the fluorocarbon layer is corrugated and consists of a chair-conformation of translinked cyclohexane. In (C ₂ F) _n , only half of the C atoms are fluorinated, and any adjacent pairs of carbon sheets are joined by a C—C covalent bond. From a systematic study on the fluorination reaction, the F / C ratio obtained is 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, particle size, and ratio. It was shown to be highly dependent on surface area. In addition to fluorine (F ₂ ), other fluorinating agents can be used, but most of the available literature involves fluorination with F ₂ 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 to 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 stripping involves sonication of graphite fluoride in a liquid medium.

  Nitrogenization of graphene can be performed by exposing a graphene material such as graphene oxide to ammonia at a high temperature (200 to 400 ° C.). Nitrided graphene can also be produced at lower temperatures by the hydrothermal method. This is done, for example, by sealing GO and ammonia in an autoclave and then raising the temperature to 150-250 ° C. Other methods for synthesizing nitrogen-doped graphene include nitrogen plasma treatment for graphene, arc discharge between graphite electrodes in the presence of ammonia, graphene oxide ammonolysis under CVD conditions, and graphene oxide at various temperatures And hydrothermal treatment of urea.

  The above features are described and explained in further detail as follows. As shown in FIG. 4B, the graphite particles (for example, 100) are typically composed of a plurality of graphite crystals or fine particles. Graphite crystals are composed of layer faces of a hexagonal network of carbon atoms. These layer planes of hexagonally arranged carbon atoms are substantially flat and oriented or ordered to be substantially parallel and equidistant from each other in a particular crystal. These layers of hexagonal carbon atoms, commonly referred to as graphene layers or basal planes, are weakly bonded in their thickness direction (crystallographic c-axis direction) by a weak van der Waals force, and these groups of graphene layers Are arranged as crystals. Graphite crystal structures are usually characterized with respect to two axes or directions. That is, the c-axis direction and the a-axis (or b-axis) direction. The c-axis is a direction perpendicular to the basal plane. The a-axis or b-axis is a direction parallel to the basal plane (perpendicular to the c-axis direction).

Due to the weak van der Waals forces that hold parallel graphene layers, natural graphite is treated to significantly open the space between the graphene layers, thereby allowing significant expansion in the c-axis direction, thus the layered properties of the carbon layer. A substantially retained expanded graphite structure can be formed. Methods for producing flexible graphite are well known in the art. In general, natural graphite flakes (eg, reference number 100 in FIG. 4B) are intercalated into an acid solution to produce a graphite intercalation compound (GIC, 102). The GIC is washed and dried and then stripped by brief exposure to high temperatures. This causes the flakes to expand or delaminate in the c-axis direction of graphite up to 80-300 times their original dimensions. The exfoliated graphite flakes look like insects and are therefore commonly referred to as graphite worms 104. These worms of highly expanded graphite flakes are sticky to expanded graphite having a typical density of about 0.04 to 2.0 g / cm ³ without the use of a binder for most applications. Or it can be formed as a unitary sheet, such as a web, paper, strip, tape, foil, mat, etc. (typically referred to as “flexible graphite” 106).

  Acids such as sulfuric acid are not the only type of intercalating agent (intercalant) that penetrates into the space between graphene faces to obtain GIC. Many other types of intercalating agents such as alkali metals (Li, K, Na, Cs, and their alloys or eutectics) are used to intercalate graphite into stage 1, stage 2, stage 3, etc. Can be used. Stage n suggests that there is one intercalant layer for every n graphene surfaces. For example, a Stage 1 potassium intercalated GIC means that there is one K layer per graphene plane. That is, one K atomic layer inserted between two adjacent graphene surfaces in a permutation of G / K / G / K / G / KG. Here, G is a graphene surface, and K is a potassium atom surface. The stage 2 GIC has a permutation of GG / K / GG / K / GG / K / GG. The stage 3 GIC has a permutation of GGG / K / GGG / K / GGG. The same applies hereinafter. These GICs can then be contacted with water or a water-alcohol mixture to produce exfoliated graphite and / or separated / isolated graphene sheets.

  The exfoliated graphite worm is subjected to high-strength mechanical shearing / separation using a high-strength air jet mill, high-strength ball mill, or ultrasonic device to produce separated nanographene platelets (NGP) All graphene platelets are thinner than 100 nm, usually thinner than 10 nm, and are often single-layer graphene (also shown as reference 112 in FIG. 4B). NGP is composed of a graphene sheet or a plurality of graphene sheets, and each sheet has a two-dimensional hexagonal structure of carbon atoms. Using a film forming or papermaking method, a plurality of NGP masses including single and / or several layers of graphene or graphene oxide discrete sheets / platelets are graphed into graphene film / paper (reference number 114 in FIG. 4B). ) Can be formed. Alternatively, at low strength shear, the graphite worms tend to separate into so-called expanded graphite flakes (reference number 108 in FIG. 4B) with a thickness greater than 100 nm. These flakes can be formed as graphite paper or mat 106 using a papermaking or matting process with or without a resin binder. Expanded graphite flakes can be used as a conductive filler in batteries. Separated NGP (individual single or multilayer graphene sheets) can be used as an anode active material or as a supporting conductive material in the cathode of an alkali metal-sulfur battery.

  There is no limitation on the type of anode active material or cathode active material that can be used to practice the present invention. In one preferred embodiment, the anode active material is selected from the group consisting of: (a) sodium or lithium 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 their (B) Si, Ge, Sn, Pb, Sb, Bi, Zn, Al, Ti, Co, Ni, Mn, Cd, and mixtures thereof, sodium or lithium containing alloys or intermetallic compounds; (c) Si Ge, Sn, Pb, Sb, Bi, Zn, Al, Fe, Ti, Co, Ni, Mn, Cd, and mixtures or composites thereof Or lithium-containing oxides, carbides, nitrides, sulfides, phosphides, selenides, tellurides, or antimonides; (d) sodium or lithium salts; and (e) sodium or lithium preloaded or previously Attached graphene sheet (referred to herein as presodiumized or prelithiated graphene sheet).

In the rechargeable alkali metal-sulfur battery, the anode is an alkali ion selected from an alkali metal, an alkali metal alloy, an alkali metal or a mixture of an alkali metal alloy and an alkali intercalation compound, an alkali element-containing compound, or a combination thereof. May include sources. Particularly desirable are petroleum coke, carbon black, amorphous carbon, hard carbon, template carbon, hollow carbon nanowire, hollow carbon sphere, natural graphite, artificial graphite, lithium or sodium titanate, NaTi ₂ (PO ₄ ) ₃ , Na ₂ Ti ₃ O ₇ (sodium titanate), Na ₂ C ₈ H ₄ O ₄ (disodium terephthalate), Na ₂ TP (sodium terephthalate), TiO ₂ , Na _x TiO ₂ (x = 0.2 to 1.0), carboxylate-based _{material, C 8 H 4 Na 2 O} 4, C 8 H 6 O 4, C 8 H 5 NaO 4, C 8 Na 2 F 4 O 4, C 10 H 2 Na 4 _{O 8, C 14 H 4 O} 6, C 14 H 4 Na 4 O 8 or anode active material containing an alkali intercalation compound selected from combinations thereof, It is. In one embodiment, the anode may comprise a mixture of two or three anode active materials (eg, a mixture of activated carbon + NaTi ₂ (PO ₄ ) ₃ or a mixture of Li and graphite particles).

The first or second liquid electrolyte in the method or battery according to the present invention can be selected from an aqueous electrolyte, an organic electrolyte, an ionic liquid electrolyte, a mixture of an organic electrolyte and an ionic electrolyte, or a mixture of them and a polymer. In some embodiments, the aqueous electrolyte comprises a sodium or potassium salt dissolved in water or a mixture of water and alcohol. In some embodiments, the sodium salt or potassium salt is Na ₂ SO ₄ , K ₂ SO ₄ , a mixture thereof, NaOH, LiOH, NaCl, LiCl, NaF, LiF, NaBr, LiBr, NaI, LiI, or they Selected from a mixture of

  Organic solvents include 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), γ-butyrolactone (γ-BL), acetonitrile (AN), ethyl acetate (EA), propyl formate (PF), methyl formate (MF), toluene, xylene, methyl acetate (MA), fluoroethylene carbonate (FEC), carbonic acid It may include a liquid solvent selected from vinylene (VC), allyl ethyl carbonate (AEC), hydrofluoroether (eg, methyl perfluorobutyl ether, MFE, or ethyl perfluorobutyl ether, EFE), and combinations thereof.

The organic electrolyte is sodium perchlorate (NaClO ₄ ), potassium perchlorate (KClO ₄ ), sodium hexafluorophosphate (NaPF ₆ ), potassium hexafluorophosphate (KPF ₆ ), sodium borofluoride (NaBF _4). ), Potassium borofluoride (KBF ₄ ), sodium hexafluoroarsenate, potassium hexafluoroarsenate, sodium trifluorometasulfonate (NaCF ₃ SO ₃ ), potassium trifluorometasulfonate (KCF ₃ SO ₃ ), Preferably selected from sodium bis-trifluoromethylsulfonylimide (NaN (CF ₃ SO ₂ ) ₂ ), potassium bis-trifluoromethylsulfonylimide (KN (CF ₃ SO ₂ ) ₂ ), ionic liquid salts, or combinations thereof May contain alkali metal salts.

The electrolyte is lithium perchlorate (LiClO ₄ ), lithium hexafluorophosphate (LiPF ₆ ), lithium borofluoride (LiBF ₄ ), lithium hexafluoroarsenate (LiAsF ₆ ), lithium trifluoro-metasulfonate (LiCF) ₃ SO ₃ ), lithium bis-trifluoromethylsulfonylimide (LiN (CF ₃ SO ₂ ) ₂ ), lithium bis (oxalate) borate (LiBOB), lithium oxalyl difluoroborate (LiBF ₂ C ₂ O ₄ ), lithium oxalyl-difluoro Borate (LiBF ₂ C ₂ O ₄ ), lithium nitrate (LiNO ₃ ), Li-fluoroalkyl phosphate (LiPF ₃ (CF ₂ CF ₃ ) ₃ ), lithium bisperfluoro-ethisulfonylimide (LiBETI), lithium bis ( Trough May include a lithium salt selected from fluoromethanesulfonyl) imide, lithium bis (fluorosulfonyl) imide, lithium trifluoromethanesulfonimide (LiTFSI), ionic liquid lithium salt, or combinations thereof.

  The ionic liquid is composed only of ions. An ionic liquid is a low melting temperature salt that becomes molten or liquid when a desired temperature is exceeded. For example, an ionic salt is considered an ionic liquid when its melting point is less than 100 ° C. If the melting temperature is below room temperature (25 ° C.), the salt is called room temperature ionic liquid (RTIL). IL-based lithium salts are characterized by weak interactions due to the combination of large cations and charge delocalized anions. This reduces the tendency of crystallization due to flexibility (anions) and asymmetry (cations).

  Some ILs can be used as a cosolvent (not a salt) to work with the first organic solvent of the present invention. The combination of 1-ethyl-3-methyl-imidazolium (EMI) cation and N, N-bis (trifluoromethane) sulfonamide (TFSI) anion produces a well-known ionic liquid. This combination results in fluids having ionic conductivity comparable to many organic electrolyte solutions, as well as low degradability and low vapor pressure, up to about 300-400 ° C. This suggests an electrolyte solvent that is generally less volatile and non-flammable and thus much safer for batteries.

  The ionic liquid is basically composed of organic or inorganic ions that cause an unlimited number of structural changes by facilitating the preparation of various components. Thus, various types of salts can be used to design ionic liquids having the desired properties for a given application. These include, among others, imidazolium, pyrrolidinium, and quaternary ammonium salts as cations and bis (trifluoromethanesulfonyl) imide, bis (fluorosulfonyl) imide, and hexafluorophosphate as anions. Useful ionic liquid-based sodium salts (not solvents) are composed of sodium ions as cations and bis (trifluoromethanesulfonyl) imide, bis (fluorosulfonyl) imide, or hexafluorophosphate as anions. be able to. For example, sodium trifluoromethanesulfonimide (NaTFSI) is a particularly useful sodium salt.

Based on their composition, ionic liquids fall into different classes including three basic types: aprotic, protic, and zwitterionic, each suitable for a particular application. Common cations of room temperature ionic liquids (RTIL) include, but are not limited to, tetraalkylammonium, di-, tri-, and tetra-alkylimidazolium, alkylpyridinium, dialkylpyrrolidinium, dialkylpiperidinium, tetra Alkylphosphonium, and trialkylsulfonium are mentioned. Common anions of RTIL include, but are not limited to, BF ₄ ⁻ , B (CN) ₄ ⁻ , CH ₃ BF ₃ ⁻ , CH ₂ CHBF ₃ ⁻ , CF ₃ BF ₃ ⁻ , C ₂ F ₅ BF ₃ ⁻ , n ^{_{-C 3 F 7 BF 3 -,}} n-C 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-} ^{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 _{(HF) 2.3} ^- combination with complex halide anions, such as results in a RTIL having good operation conductivity.

  RTIL has high intrinsic ionic conductivity, high thermal stability, low volatility, low (substantially zero) vapor pressure, non-flammability, and the ability to maintain liquids over a wide temperature range above and below room temperature Can have typical properties such as high polarity, high viscosity, and wide electrochemical window. With the exception of high viscosity, these properties are desirable when using RTIL as an electrolyte co-solvent in replaceable lithium cells.

The specific capacity and specific energy of the Li-S cell or Na-S cell is the actual amount of sulfur that can be implemented in the cathode active layer (relative to other non-active components such as caking resin and conductive filler), and It is determined by the utilization of this amount of sulfur (ie, the utilization efficiency of the cathode active material, or the actual proportion of S that is actively involved in the storage and release of lithium ions). High-capacity and high-energy Li-S or Na-S cells provide high amounts of S in the cathode active material layer (ie non-active materials such as caking resins, conductive additives, and other modification or support materials) ) And high S utilization efficiency. The present invention provides such cathode active layers and methods for making such cathode active layers (eg, pre-sulfided active cathode layers). As an example of a sulfur preloading procedure, the method includes the following four steps (a) to (d):
a) providing a layer of a porous graphene structure with a large graphene surface having a specific surface area greater than 100 m ² / g (these surfaces must be accessible to the electrolyte); The porous graphene structure preferably has a specific surface area of> 500 m ² / g, more preferably> 700 m ² / g, most preferably> 1,000 m ² / g;
b) providing an electrolyte comprising a solvent (an organic solvent and / or a non-aqueous solvent such as an ionic liquid) and a sulfur source dissolved or dispersed in the solvent;
c) providing an anode;
d) The porous graphene structure and anode integral layer is in ionic contact with the electrolyte (eg, all these components are immersed in a chamber outside the intended Li-S cell, or these three components are Nanoscale sulfur particles are deposited electrochemically between the anode and the porous graphene structure monolayer (functioning as a cathode) or on the graphene surface (by encapsulating inside the Li-S cell) Applying a current at a sufficient current density for a period of time sufficient to coat and form a pre-sulfided graphene layer;
e) pulverizing the pre-sulfided layer to produce an isolated S-coated graphene sheet. These sheets can be injected or impregnated into the pores of the cathode current collector foam (porous conductive structure) to form the cathode.

The layer of the porous graphene structure described in step (a) includes graphene material or exfoliated graphite material, and the graphene material is pure graphene, graphene oxide, reduced graphene oxide, graphene fluoride, graphene chloride, graphene bromide, Selected from graphene iodide, hydrogenated graphene, nitrogenated graphene, boron-doped graphene, nitrogen-doped graphene, chemically functionalized graphene, or combinations thereof, exfoliated graphite material is exfoliated graphite worm, expanded graphite flakes, Or selected from recompressed graphite worms or flakes (which still must exhibit a high specific surface area >> 100 m ² / g accessible to the electrolyte). It was surprising that it was discovered that multiple graphene sheets could be packed together to form a sulfur-based electrode layer with structural integrity without the need for a caking resin, and so on The layer can retain its shape and function during repeated charging and discharging of the resulting Li-S cell.

  S particles or coatings have a thickness or diameter of less than 20 nm (preferably <10 nm, more preferably <5 nm, even more preferably <3 nm), and nanoscale sulfur particles or coatings can be combined with sulfur particles or coatings and graphene It accounts for a weight fraction of at least 70% (preferably> 80%, more preferably> 90%, and most preferably> 95%) based on the total weight of the combination with the material. Deposit as much S as possible while still maintaining the ultra-thin thickness or diameter of the S coating or particles (eg,> 80% and <3 nm;> 90% and <5 nm; and> 95% and <10 nm, etc.) It is advantageous to do so.

  When a layer having a porous graphene structure is prepared, this layer can be immersed in an electrolyte (preferably a liquid electrolyte), and the electrolyte includes a solvent and a sulfur source dissolved or dispersed in the solvent. This layer basically functions as the cathode in the external electrochemical deposition chamber.

  Thereafter, the anode layer is also immersed in the chamber. Although any conductive material can be used as the anode material, preferably this layer contains some lithium or sodium. In such a configuration, the porous graphene structure layer and the anode are in ionic contact with the electrolyte. A pre-sulfided active cathode is then deposited electrochemically or coated on the surface of graphene between the anode and an integral layer of porous graphene structure (which functions as a cathode) Current is applied at a sufficient current density for a period sufficient to form the layer. The required current density depends on the desired deposition rate and the uniformity of the deposited material.

  This current density can easily be adjusted to deposit S particles or coatings having a thickness or diameter of less than 20 nm (preferably <10 nm, more preferably <5 nm, even more preferably <3 nm). The resulting nanoscale sulfur particles or coating is at least 70% (preferably> 80%, more preferably> 90%, and most preferably> 95% based on the total weight of the combination of sulfur particles or coating and graphene material. %) Weight fraction.

In a preferred embodiment, the sulfur source is M _x S _y , where x is an integer from 1 to 3, y is an integer from 1 to 10, and M is selected from alkali metals, Mg or Ca. Metal element selected from alkaline metals, transition metals, metals of Groups 13 to 17 of the periodic table, or combinations thereof. In a preferred embodiment, the metal element M is selected from Li, Na, K, Mg, Zn, Cu, Ti, Ni, Co, Fe, or Al. In particularly desirable embodiments, M _x S _y is Li ₂ S ₆ , Li ₂ S ₇ , Li ₂ S ₈ , Li ₂ S ₉ , Li ₂ S ₁₀ , Na ₂ S ₆ , Na ₂ S ₇ , Na ₂ S. ₈ , Na ₂ S ₉ , Na ₂ S ₁₀ , K ₂ S ₆ , K ₂ S ₇ , K ₂ S ₈ , K ₂ S ₉ , or K ₂ S ₁₀ .

  In one embodiment, the anode comprises an anode active material selected from alkali metals, alkaline metals, transition metals, metals from Groups 13-17 of the periodic table, or combinations thereof. This anode may be the same anode intended to be included in the Li-S cell.

  The solvent and lithium or sodium salt used in the electrochemical deposition chamber can be selected from any of the solvents or salts listed above for lithium sulfur or sodium sulfur batteries.

  As a result of extensive and deep research efforts, the inventors have surprisingly found that such presulfidation solves some of the most important problems associated with current Li-S or Na-S cells. It was. For example, this method allows sulfur to be deposited in a thin coating or ultrafine particle form, thus providing an ultrashort lithium ion diffusion path and thus providing ultrafast reaction times for fast charge and discharge of batteries. provide. For a high specific capacity (mAh / g; based on the total weight of the cathode layer, including the mass of active material, S, supported graphene sheet, caking resin, and conductive filler), a relatively high proportion of sulfur ( Active material responsible for the storage of lithium) and thus is achieved while maintaining the high specific lithium storage capacity of the resulting cathode active layer.

  Prior art procedures can be used to deposit small S particles, but cannot provide high S ratios or can achieve high ratios, but in the form of large particles or thick films. It is important to note that only can be provided. However, the prior art procedure could not achieve both at the same time. Thus, it is unexpectedly very advantageous to obtain a high sulfur loading while maintaining ultra-thin / small thickness / diameter sulfur. This was not possible with conventional sulfur loading techniques. For example, we were able to deposit nanoscale sulfur particles or coatings that accounted for> 90% weight fraction of the cathode layer and still maintained the coating thickness or particle size <3 nm. This is an exceptional result in the field of lithium-sulfur batteries. As another example, we achieved> 95% S loading with an average S coating thickness of 4.8-7 nm.

  Electrochemists or materials scientists in the field of Li-S batteries, especially when there is a higher amount of highly conductive graphene sheets or graphite flakes in the cathode active material layer (and therefore a lower amount of S) We expected that S utilization would be better under high charge / discharge rate conditions. Contrary to these expectations, the key to achieving high S utilization efficiency is to minimize the S coating or particle size, and the S coating or particle thickness / diameter is sufficiently small (eg, <10 nm, or It has been observed by the inventors that it depends on the amount of S loaded in the cathode, assuming that it is even better for <5 nm. The problem here is that when S was higher than 50% by weight, it was not possible to maintain a thin S coating or small particle size. More surprisingly, the key to enabling a high specific capacity at the cathode under high rate conditions is to maintain a high S loading and still keep the S coating or particle size as small as possible. Has been observed by the present inventors, which is achieved using the presulfidation method of the present invention.

  Electrons entering and exiting an external load or circuit are either conductive additives or conductive frameworks (at a conventional sulfur cathode) (eg, exfoliated graphite mesoporous structures or nanostructures of conductive graphene sheets disclosed herein) ) To reach the cathode active material. Since the cathode active material (eg, sulfur or lithium polysulfide) is a weak electron conductor, the active material particles or coating should be as thin as possible to reduce the required electron transfer distance.

  Furthermore, cathodes in conventional Li-S cells typically have less than 70 wt% sulfur in a composite cathode composed of sulfur and a conductive additive / support. Even when the sulfur content of prior art composite cathodes reaches or exceeds 70% by weight, the specific capacity of the composite cathode is typically higher than expected based on theoretical predictions. Significantly lower. For example, the theoretical specific capacity of sulfur is 1,675 mAh / g. A composite cathode composed of 70% sulfur (S) and 30% carbon black (CB) without binder should be able to store up to 1,675 × 70% = 1,172 mAh / g. Unfortunately, the specific capacities observed are typically less than 75% or 879 mAh / g of what is feasible (often less than 50% or 586 mAh / g in this example). In other words, the active material utilization is typically less than 75% (or even less than 50%). This is a major problem in Li-S cell technology and there was no solution to this problem. Most surprisingly, the realization of huge graphene surfaces associated with porous graphene structures as conductive support materials for sulfur or lithium polysulfide is typically >> 80%, more often 90% It makes it possible to achieve an active material utilization of more than 95% to 99% in many cases.

Alternatively, the cathode active material (S or polysulfide) may be deposited on or bound by a functional material or nanostructured material. Functional materials or nanostructured materials are: (a) soft carbon, hard carbon, polymeric carbon or carbonized resin, mesophase carbon, coke, carbonized pitch, carbon black, activated carbon, nanocell carbon foam, or partially graphitized Nanostructured or porous disordered carbon materials selected from selected carbon; (b) nanographene platelets selected from single-layer graphene sheets or multilayer graphene platelets; (c) single-wall carbon nanotubes or multi-wall carbon nanotubes (D) carbon nanofibers, nanowires, metal oxide nanowires or fibers, conductive polymer nanofibers, or combinations thereof; (e) carbonyl-containing organic or polymer molecules; (f) carbonyl groups; Carboxyl group, also It can be selected from the group consisting of:; functional materials containing amine groups. In a preferred embodiment, the functional material or nanostructured material has a specific surface area of at least 500 m ² / g, preferably at least 1,000 m ² / g.

  Typically, the cathode active material is not conductive. Thus, in one embodiment, the cathode active material is carbon black (CB), acetylene black (AB), graphite particles, expanded graphite particles, activated carbon, mesoporous carbon, mesocarbon microbeads (MCMB), carbon nanotubes (CNT). ), Carbon nanofibers (CNF), graphene sheets (also referred to as nanographene platelets, also NGP), carbon fibers, or combinations thereof. These carbon / graphite / graphene materials (including sulfur or polysulfides) can be made into fine particles as cathode active materials for the Li-S or Na-S cells of the present invention.

  In preferred embodiments, nanoscale filaments (eg, CNT, CNF, and / or NGP) are large surfaces for supporting an anode active material (eg, Na or Li coating) or a cathode active material (eg, S). Formed as a porous nanostructure. The porous nanostructure should preferably have pores with a pore size of 2 nm to 50 nm, preferably 2 nm to 10 nm. These pores are appropriately sized to contain the electrolyte on the cathode side and retain the cathode active material within the pores during repeated charging and discharging. The same type of nanostructures may be realized on the anode side to support the anode active material.

  On the anode side, dendrite formation is a concern when alkali metal is used as the only anode active material in an alkali metal cell, which can lead to internal short circuits and thermal runaway. Here, two approaches were used individually or in combination to address this problem of dendrite formation. One involves the use of high concentration electrolytes and the other involves the use of nanostructures composed of conductive nanofilaments for supporting alkali metals at the anode. Examples of nanofilament include carbon nanofiber (CNF), graphite nanofiber (GNF), carbon nanotube (CNT), metal nanowire (MNW), conductive nanofiber obtained by electrospinning, and conductive electrospinning composition nano It can be selected from fiber, nanoscale graphene platelets (NGP), or combinations thereof. The nanofilaments may be bound by a binder material selected from polymers, coal tar pitch, petroleum pitch, mesophase pitch, coke, or derivatives thereof.

  Surprisingly, significantly, the nanostructures have a uniform deposition of alkali metal ions during cell recharging to the extent that geometrically sharp structures or dendrites are not seen at the anode even after many cycles. Provide an environment that brings Without wishing to be bound by any theory, Applicants believe that the 3D network of highly conductive nanofilaments provides a substantially uniform attractive force of alkali metal ions to the filament surface during recharging. ing. Furthermore, the surface area per unit volume or unit weight of the nanofilament is large due to the nanometer size of the filament. This ultra-high specific surface area provides an opportunity for alkali metal ions to uniformly deposit a thin coating on the filament surface. The high surface area readily accepts large amounts of alkali metal ions in the liquid electrolyte and allows a high recharge rate for the alkali metal secondary battery.

  In the examples discussed below, unless otherwise noted, raw materials such as silicon, germanium, bismuth, antimony, zinc, iron, nickel, titanium, cobalt, and tin are available from Alfa Aesalof Ward Hill, Massachusetts, USA. Obtained from Chemical Company (Milwaukee, Wis., USA) or Alcan Metal Powders of Berkeley (California, USA). X-ray diffraction patterns were collected using a diffractometer equipped with a copper target X-ray tube and a diffracted beam monochromator. The presence or absence of a characteristic peak pattern was observed for each alloy sample tested. For example, a phase was considered amorphous if there was no X-ray diffraction pattern or no clear and distinct peak. In some cases, scanning electron microscopy (SEM) and transmission electron microscopy (TEM) were used to characterize the structure and morphology of hybrid material samples.

  In the following, several different types of anode active materials, cathode active materials, and porous current collector materials (eg, graphite foam, graphene foam, and metal are shown to illustrate the best mode of carrying out the invention. Some examples of foams are provided. These exemplary embodiments, and other portions of the specification and drawings, are individually or in combination to be sufficient to enable one of ordinary skill in the art to practice the invention. However, these examples should not be construed as limiting the scope of the invention.

Example 1: Example of conductive porous layer (foam current collector) Various types of metals such as Ni foam, Cu foam, Al foam, Ti foam, Ni mesh / web, stainless steel fiber mesh, etc. Foam and fine metal web / screen are commercially available. These conductive foam structures were used as anode or cathode conductive porous layers (foam current collectors) in this study. Furthermore, as shown in FIGS. 3A, 3B, 3C, and 3D, metal-coated polymer foam and carbon foam were also used as current collectors.

Example 2: Ni foam on a Ni foam template and current collector based on CVD graphene foam (conductive porous layer)
The procedure for producing CVD graphene foam was adapted from that disclosed in the following published literature: Chen, Z. et al. et al. “Three-dimensional flexible and conductive interconnected network networks grown by chemical vapor deposition,” Nature Materials, 10, 424-428. A porous structure with nickel foam, a nickel interconnected 3D scaffold, was selected as a template for growth of graphene foam. Briefly, carbon was introduced into the nickel foam by decomposing CH ₄ at 1,000 ° C. under ambient pressure, and then a graphene film was deposited on the surface of the nickel foam. Corrugations and wrinkles occurred in the graphene film due to the difference in thermal expansion coefficient between nickel and graphene. Four types of foams formed in this example: Ni foam, CVD graphene coated Ni foam, CVD graphene foam (Ni is etched away), and conductive polymer bonded CVD graphene foam, Used as a current collector in a lithium battery according to the present invention.

  The Ni frame was etched away to recover (separate) the graphene foam from the support Ni foam. In the procedure proposed by Chen et al., A thin layer of poly (methyl methacrylate) (PMMA) is deposited on the surface of a graphene film as a support before etching away the nickel skeleton with hot HCl (or FeCl3) solution, The graphene network was prevented from collapsing during nickel etching. After carefully removing the PMMA layer with hot acetone, a fragile graphene foam sample was obtained. The use of a PMMA support layer was considered important for preparing a free-standing film of graphene foam. Instead, the inventors used a conductive polymer as a binder resin to hold the graphene together and remove Ni by etching. It should be noted that the CVD graphene foam used herein is intended as a foamable current collector to contain a suspension of active material dispersed in a liquid electrolyte. Note, for example, that it is intended as a foamable current collector containing hard carbon nanoparticles implanted with a liquid electrolyte at the anode and graphene-supported sulfur nanoparticles implanted with a liquid electrolyte at the cathode.

Example 3: Graphite foam-based current collector from pitch-based carbon foam Pitch powder, granules, or pellets are placed in an aluminum mold having the desired final shape of the foam. A Mitsubishi ARA-24 mesophase pitch was utilized. The sample is evacuated to less than 1 Torr and then heated to a temperature of about 300 ° C. At this point, the vacuum was released to a nitrogen blanket and then pressure up to 1,000 psi was applied. The system temperature was then raised to 800 ° C. This was done at a rate of 2 ° C./min. The temperature was maintained for at least 15 minutes to achieve immersion, then the furnace was turned off and cooled to room temperature at a rate of about 1.5 ° C./min, along with releasing the pressure at a rate of about 2 psi / min. The final foam temperatures were 630 ° C and 800 ° C. During the cooling cycle, the pressure is gradually released to atmospheric conditions. The foam was then heat treated (carbonized) to 1050 ° C. under a nitrogen blanket and then separately heat treated to 2500 ° C. and 2800 ° C. (graphitized) in argon in a graphite crucible.

Example 4: Some examples of electrolytes used Preferred non-lithium alkali metal salts include: Sodium perchlorate (NaClO ₄ ), potassium perchlorate (KClO ₄ ), sodium hexafluorophosphate (NaPF ₆ ), potassium hexafluorophosphate (KPF ₆ ), sodium borofluoride (NaBF ₄ ), borofluoride Potassium (KBF ₄ ), sodium hexafluoroarsenate, potassium hexafluoroarsenate, sodium trifluorometasulfonate (NaCF ₃ SO ₃ ), potassium trifluorometasulfonate (KCF ₃ SO ₃ ), bis-trifluoro methylsulfonyl imide sodium _{(NaN (CF 3 SO 2)} 2), and bis - potassium trifluoromethylsulfonylimide _{[KN (CF 3 SO 2)} 2].

In aqueous electrolytes, the sodium or potassium salt is preferably Na ₂ SO ₄ , K ₂ SO ₄ , mixtures thereof, NaOH, KOH, NaCl, KCl, NaF, KF, NaBr, KBr, NaI, KI, or Selected from a mixture of The salt concentrations used in this study were 0.3M to 3.0M (most often 0.5M to 2.0M).

Various lithium salts dissolved in organic liquid solvents were used in this study (alone or in a mixture with another organic or ionic liquid). The following lithium salts were considered well soluble in selected organic or ionic liquid solvents. Lithium borofluoride (LiBF ₄ ), lithium trifluoro-metasulfonate (LiCF ₃ SO ₃ ), lithium bis-trifluoromethylsulfonylimide (LiN (CF ₃ SO ₂ ) ₂ or LITFSI), lithium bis (oxalate) borate (LiBOB) ), Lithium oxalyl difluoroborate (LiBF ₂ C ₂ O ₄ ), and lithium bisperfluoroethyl-sulfonylimide (LiBETI). A good electrolyte additive that helps stabilize the Li metal is LiNO ₃ . Particularly useful ionic liquid-based lithium salts include lithium bis (trifluoromethanesulfonyl) imide (LiTFSI).

  Preferred organic liquid solvents include the following: 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 sulfolanes.

Preferred ionic liquid solvents can be selected from room temperature ionic liquids (RTIL) having cations selected from tetraalkylammonium, di-alkylimidazolium, alkylpyridinium, dialkyl-pyrrolidinium, or dialkylpiperidinium. The counter anion is 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 are Nn-butyl-N-ethylpyrrolidinium bis (trifluoromethanesulfonyl) imide (BEPyTFSI), N-methyl-N-propylpiperidinium bis (trifluoromethylsulfonyl) Imido (PP ₁₃ TFSI), and N, N-diethyl-N-methyl-N- (2-methoxyethyl) ammonium bis (trifluoromethylsulfonyl) imide.

Example 4 Preparation of Graphene Oxide (GO) and Reduced Graphene Oxide (RGO) Nanosheets from Natural Graphite Powder Nominal 45 μm size natural provided by Asbury Carbons (405 Old Main St., Asbury, NJ 08802, USA) The graphite was crushed to reduce the size to about 14 μm and used as starting material. GO was obtained by following the well-known modified Hummers method. This method involves 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 P ₂ O ₅ , and 400 mL concentrated aqueous H ₂ SO ₄ (96%) were then added to the flask. The mixture was heated under reflux for 6 hours and then allowed to stand at room temperature for 20 hours. Graphite oxide was filtered and rinsed with plenty of distilled water until neutral pH. At the end of this initial oxidation, a wet cake was recovered.

In the second oxidation process, the previously collected wet cake was placed in a boiling flask containing 69 mL of concentrated aqueous H ₂ SO ₄ (96%). The flask was kept in an ice bath while 9 g of KMnO ₄ was slowly added. Care was taken to avoid overheating. The resulting mixture was stirred at 35 ° C. for 2 hours (sample color turned dark green) followed by addition of 140 mL of water. After 15 minutes, the reaction was stopped 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 changed to bright yellow. To remove metal ions, the mixture was filtered and rinsed with 1:10 aqueous HCl. The 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. Thereafter, the wet cake material diluted with deionized water was lightly sonicated to obtain a liquid dispersion of GO platelets.

RGO (RGO-BS) stabilized with a surfactant was obtained by diluting the wet cake with a surfactant aqueous solution instead of pure water. A commercial mixture of sodium cholate (50 wt%) and sodium deoxycholate (50 wt%) provided by Sigma Aldrich was used. The weight fraction of the 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 microchip and 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 the GO obtained above was performed to produce RGO by following a method that included putting 10 mL of a 0.1 wt% GO aqueous solution into a 50 mL boiling flask. Next, 10 μL of 35 wt% aqueous solution of N ₂ H ₄ (hydrazine) and 70 mL of 28 wt% aqueous NH ₄ OH (ammonia) were added to the mixture stabilized by the surfactant. The solution was heated to 90 ° C. and refluxed for 1 hour. The pH value measured after the reaction was about 9. During the reduction reaction, the color of the sample changed to dark black.

  RGO was used as a conductive additive for one or both of the anode and cathode in certain alkali metal batteries of the present invention. In selected sodium-sulfur cells, presodiumated RGO (eg, RGO + sodium particles, or RGO pre-deposited with a sodium coating) was also used as the anode active material. A prelithiated RGO film was also used as the anode active material for the Li-S cell.

  For comparison, slurry coating and drying procedures were performed to produce a conventional electrode. The electrode and separator disposed between the two electrodes were then assembled and placed in an Al-plastic laminate packaging envelope, followed by liquid electrolyte injection to form a sodium or potassium battery cell.

Example 5: Preparation of a sheet of pure graphene (0% oxygen) Recognizing the possibility that high defect populations in a GO sheet act to reduce the conductivity of individual graphene surfaces, we Conductive addition with high conductivity and thermal conductivity by using pure graphene sheet (eg not oxidized, oxygen free, halogenated, halogen free) I decided to study if I could get an agent. Pre-sodiumated pure graphene was also used as the anode active material. Pure graphene sheets were produced by using direct sonication or liquid phase production methods.

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

  Then, using both the slurry injection procedure into the foam pores according to the present invention and the conventional slurry coating, drying, and laminating procedure, a sheet of pure graphene as the conductive additive, the anode active Incorporated into the cell along with the material (or cathode active material for the cathode). Both alkali metal ion batteries and alkali metal batteries (injection into the cathode only) were investigated. In an alkali metal battery (primary battery or secondary battery), the anode is a Na foil or K chip supported by a graphene sheet.

Example 6: Preparation of presodium graphene fluoride sheet as anode active material for sodium sulfur battery Several methods were used to produce graphene fluoride (GF), but here one Only the method is described. In a typical procedure, heavily exfoliated graphite (HEG) was prepared from the intercalate compound C ₂ F · xClF ₃ . The HEG was further fluorinated with chlorine trifluoride vapor to produce fluorinated heavily exfoliated graphite (FHEG). A pre-cooled Teflon reactor was charged with 20-30 mL of pre-cooled liquid ClF ₃ and the reactor was closed and cooled to liquid nitrogen temperature. Next, 1 g or less of HEG was placed in a container having a hole that allows ClF ₃ gas to enter the inside of the reactor. In 7-10 days, a grey-beige product with the approximate formula C ₂ F was formed.

  A small amount of FHEG (approximately 0.5 mg) is then mixed with 20-30 mL of organic solvent (separately methanol and ethanol) and sonicated (280 W) for 30 minutes to produce a homogeneous yellowish dispersion. did. After removal of the solvent, the dispersion became a brownish powder. In a liquid electrolyte, graphene fluoride powder was mixed with a sodium tip to cause presodiumization before or after injection into the pores of the anode current collector.

Example 7: Preparation of Nitrogenized Graphene Nanosheet and Porous Graphene Structure Graphene oxide (GO) synthesized in Example 1 was pulverized with different ratios of urea, and the pelletized mixture was placed in a microwave reactor (900 W) For 30 seconds. The product was washed several times with deionized water and vacuum dried. In this method, graphene oxide is reduced and simultaneously doped with nitrogen. The products obtained with graphene: urea mass ratios of 1: 0.5, 1: 1, and 1: 2 were named NGO-1, NGO-2, and NGO-3, respectively. The nitrogen content of these samples was 14.7, 18.2, and 17.5 wt%, respectively, as revealed by elemental analysis. These nitrogenated graphene sheets remain dispersible in water. Next, two types of dispersions were prepared. One added a water-soluble polymer (eg, polyethylene oxide) to the nitrogenated graphene sheet-water dispersion to produce a water-based suspension. On the other hand, the nitrogenated graphene sheet-water dispersion was dried to recover the nitrogenated graphene sheet, which was then added to the precursor polymer-solvent solution to obtain an organic solvent-based suspension.

  The obtained suspension was cast, dried, carbonized, and graphitized to produce a porous graphene structure. The carbonization temperature of the comparative sample is 900 to 1,350 ° C. The graphitization temperature is 2,200 ° C to 2,950 ° C. The porous graphene layer is used as a porous current collector for both the anode and cathode of the Li-S cell.

Example 8: Conductive web of filaments from electrospun PAA fibrils as support layer for the anode Pyromellitic dianhydride (Aldrich) and 4,4'-oxydianiline (Aldrich) in tetrahydrofuran / methanol (THF / MeOH) The poly (amic acid) (PAA) precursor for spinning was prepared by copolymerization in a mixed solvent having a weight ratio of 8/2. A PAA solution was spun using an electrospinning apparatus to obtain a fiber web. This device consisted of a 15 kV DC power source with a positively charged capillary tube through which the polymer solution was extruded and a negatively charged drum to collect the fibers. Solvent removal and imidization from PAA was performed simultaneously 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 obtain carbonized nanofibers with an average fibril diameter of 67 nm. Such a web can be used as a conductive substrate for the anode active material. It has been observed by the inventors that the implementation of a network of conductive nanofilaments at the anode of a Li-S cell can effectively suppress the initiation and growth of lithium dendrite, which could otherwise cause an internal short circuit.

Example 9: Electrochemical deposition of S (external electrochemical deposition) on various web or paper structures for Li-S and Na-S batteries
Electrochemical deposition may be performed before the cathode active layer is incorporated into an alkali metal-sulfur battery cell (Li-S or Na-S cell). In this approach, the anode, electrolyte, and integral layer of porous graphene structure (functioning as the cathode layer) are positioned in an external container outside the lithium-sulfur cell. The required equipment is similar to electroplating systems well known in the art.

In a typical procedure, 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. Optionally, an amount of lithium salt may be added, but this is not necessary for external electrochemical deposition. A wide range of solvents can be utilized for this purpose, and there is no theoretical limit as to what kind of solvent can be used. Any solvent can be used provided that there is some solubility of the metal polysulfide in this desired solvent. Greater solubility means that a greater amount of sulfur can be derived from the electrolyte.

  The electrolyte is then injected into a chamber or reactor under a dry controlled atmosphere (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. This configuration constitutes an electrochemical deposition system. Electrochemically depositing nanoscale sulfur particles or coatings on the graphene surface is preferably performed at a current density in the range of 1 mA / g to 10 A / g, based on the layer weight of the porous graphene structure. .

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

Example 10 Chemical Reaction Induced Deposition of Sulfur Particles on Isolated Graphene Sheets Before Cathode Layer Preparation To prepare S-graphene composites from isolated graphene oxide sheets, Chemical vapor deposition is used (ie, these GO sheets were not packed into a porous graphene monolith before chemical deposition of S on the surface of the GO sheet). The procedure began with the addition of 0.58 g Na ₂ S to a flask filled with 25 ml distilled water to produce a Na ₂ S solution. Next, 0.72 g of element S was suspended in the Na ₂ S solution, and stirred with a magnetic stirrer at room temperature for about 2 hours. As the sulfur dissolved, the color of the solution slowly changed to orange-yellow. After the dissolution of sulfur, a sodium polysulfide (Na ₂ S _x ) solution was obtained (x = 4-10).

Then, the graphene oxide-sulfur (GO-S) composite was produced by chemical vapor deposition in an aqueous solution. First, 180 mg of graphite oxide was suspended in 180 ml of ultrapure water, and then sonicated for 5 hours at 50 ° C. to produce a stable graphene oxide (GO) dispersion. Thereafter, a Na ₂ S _x solution was added to the GO dispersion prepared as described above in the presence of 5 wt% surfactant cetyltrimethylammonium bromide (CTAB), and the prepared GO / Na ₂ S _x mixture was added. The solution was sonicated for an additional 2 hours, then 100 ml of 2 mol / L HCOOH solution was titrated 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: Redox Chemical Reaction Induced Deposition of Sulfur Particles on Isolated Graphene Sheets Before Cathode Layer Preparation In this deposition process based on chemical reactions, sodium thiosulfate (Na ₂ S ₂₎ as a sulfur source O ₃ ) was used and HCl was used as the reaction. GO- water suspension is prepared and then poured two reactants (HCl and _Na 2 _S 2 _{O 3)} to the suspension. The reaction was allowed to proceed at 25 to 75 ° C. for 1 to 3 hours to obtain a precipitate of S particles deposited on the surface of the GO sheet. This reaction can be represented by the following reaction:
2HCl + Na ₂ S ₂ O ₃ → 2NaCl + S ↓ + SO ₂ ↑ + H ₂ O

Example 12: Preparation of S / GO nanocomposite by solution deposition A GO sheet and S were mixed and dispersed in a solvent (CS ₂ ) to produce a suspension. After careful stirring, the solvent was evaporated to obtain a solid nanocomposite, which was then pulverized to obtain a nanocomposite powder. The primary sulfur particles in these nanocomposite particles have an average diameter of about 40-50 nm.

Example 13: Preparation of various battery cells and electrochemical testing For most of the anode and cathode active materials studied, an alkali metal-sulfur cell or alkali metal ion- using both the method according to the invention and the conventional method- A sulfur cell was prepared.

In conventional methods, a typical anode composition comprises 85% by weight of active material (eg, Sn or Na ₂ C ₈ H ₄ O ₄ coated graphene sheet for Na ion-sulfur anode; Li ion-sulfur anode Graphite or Si particles), 7% by weight acetylene black (Super-P), and 8% by weight polyvinylidene fluoride binder (PVDF, 5) dissolved in N-methyl-2-pyrrolidinone (NMP). Wt% solids content). After coating the slurry on the Cu foil, the electrode was vacuum dried at 120 ° C. for 2 hours to remove the solvent. The cathode layer is similarly prepared (using Al foil as the cathode current collector). The anode layer, separator layer (eg, Celgard 2400 membrane), and cathode layer are then laminated together and housed in a plastic Al envelope. A 1M LiPF ₆ or NaPF ₆ electrolyte solution dissolved in a mixture of ethylene carbonate (EC) and diethyl carbonate (DEC) (EC-DEC, 1: 1 v / v) is then injected into the cell. In some cells, an ionic liquid was used as the liquid electrolyte. The cell assembly was made in an argon filled glove box.

  In the process according to the invention, in a particular embodiment, the anode current collector (anode) before or after the injection (or impregnation) of the first suspension and / or the injection (or impregnation) of the second suspension. A conductive porous structure), a separator, and a cathode current collector (conductive porous structure for the cathode side) are assembled in a protective housing. In some examples, an empty foamable anode current collector, a porous separator layer, and an empty foamable current collector were assembled together and housed in a pouch (consisting of an Al-nylon bilayer film). An assembly was formed. The first suspension was then injected into the anode current collector and the second suspension was injected into the cathode current collector. The pouch was then sealed. In another example, the inventors impregnate a foamable anode current collector with a first suspension to form an anode layer, and alternatively, a second suspension in the foamable cathode current collector. A cathode layer was formed by impregnating the solution. Next, the anode layer, the porous separator layer, and the cathode layer were assembled and accommodated in a pouch to form a cell. In the process according to the invention, typically no binder resin is needed or used, resulting in a savings of 8% by weight (reduced amount of inactive material).

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

  It should be noted that in the lithium ion battery industry, the cycle life of a battery is defined as the number of charge / discharge cycles at which the battery undergoes a 20% capacity decay based on the initial capacity measured after the required electrochemical formation. It is a common practice. Again, the same definition for the cycle life of Li-S or room temperature Na-S cells follows.

Example 14: Typical test results For each sample, several current densities (representing charge / discharge rates) were imposed to determine the electrochemical response, and a Ragone plot (power density versus energy density) It enabled calculation of energy density and power density value required for construction. FIG. 5 shows a Ragone plot (weight and volume power density versus energy density) of a Na-ion battery cell containing hard carbon particles as the anode active material and activated carbon / sulfur composite particles as the cathode active material. . Two of the four data curves are for cells prepared in accordance with embodiments of the present invention, and the other two are by conventional slurry coating of electrodes (slurry roll coating). From these data, several important observations can be made:

  The weight and volume energy density and power density of sodium ion-S battery cells prepared by the method according to the present invention (represented as “present invention” in the legend of the figure) Considerably higher than the equivalent provided by Change from 150 μm anode thickness (coated on flat solid Cu foil) to 225 μm thickness (all contained within the pores of Ni foam with 85% porosity), and balance The corresponding change in cathode to maintain the capacity ratio taken results in an increase in weight energy density from 155 Wh / kg to 187 Wh / kg. Even more surprising, the volumetric energy density is increased from 232 Wh / L to 318 Wh / L.

  These significant differences are not simply due to the increase in electrode thickness and mass loading. This difference is probably due to: Significantly higher active material mass loading (relative to other materials) associated with cells according to the invention; reduced ratio of overhead (inactive) component to active material weight / volume; need to have binder resin Surprisingly good utilization of the electrode active material (most if not all hard carbon particles and C / S particles contribute to the sodium ion storage capacity, especially under conditions of high charge / discharge rates in the electrode And the surprising function of the method according to the invention, which can more effectively fill the active material particles within the pores of the foamable current collector.

  FIG. 6 shows a Ragone plot (weight and volume power density versus weight and volume energy density) of two cells containing graphene-encapsulated Na nanoparticles as the anode active material and S-coated graphene sheets as the cathode active material. Experimental data was obtained from battery cells prepared by the method according to the invention and battery cells prepared by conventional slurry coating of electrodes.

  These data show that the weight and volumetric energy density and power density of the battery cells prepared by the method according to the present invention are considerably higher than the counterparts prepared by the conventional method. Again, the difference is significant. A cell formed in a conventional manner exhibits a weight energy density of 215 Wh / kg and a volumetric energy density of 323 Wh / L, whereas a cell according to the invention delivers 334 Wh / kg and 601 Wh / L, respectively. A cell level weight energy density of 601 Wh / L has not been achieved in a rechargeable sodium battery. The power densities of 1432 W / kg and 2,578 W / L are typically unprecedented for higher energy lithium ion batteries, not to mention sodium ion batteries.

The difference between these energy densities and power densities is mainly due to the following. High active material mass loading associated with cells according to the invention (> 25 mg / cm ^{2 for} anode and> 35 mg / cm ^{2 for} cathode); reduction of the ratio of overhead (inactive) components to active material weight / volume; No need to have a binder resin; active material particles can be better utilized (all particles are accessible to the liquid electrolyte, fast ion and electron kinetics), and the fineness of the foamable current collector The function of the method according to the invention, which can more effectively fill the pores with active material particles.

FIG. 7 shows a Ragone plot of a Li-S battery containing lithium foil as the anode active material, S-coated graphene sheet as the cathode active material, and lithium salt (LiaPF ₆ ) -PC / DEC as the organic liquid electrolyte. The data relates to both sodium metal cells prepared by the method according to the invention and sodium metal cells prepared by conventional slurry coating of electrodes. These data show that the weight and volumetric energy density and power density of sodium metal cells prepared by the method according to the present invention are considerably higher than their counterparts prepared by conventional methods. Again, the differences are significant, probably due to: A fairly high active material mass load associated with the cell according to the invention; a reduction in the ratio of overhead (inactive) components to active material weight / volume; no need to have a binder resin; surprisingly active electrode material Good utilization (most if not all active material contributes to the sodium ion storage capacity. There are no dry pockets or ineffective spots in the electrode, especially under conditions of high charge / discharge rates); and Surprising function of the method according to the invention, which can more effectively fill the active material particles into the pores of the foamable current collector.

  The observation that the cell level weight energy density of the Li-S cell according to the invention is 624 Wh / kg higher than that of all rechargeable lithium metal or lithium ion batteries reported so far is quite remarkable. However, it is unexpected (recall that current Li-ion batteries typically store 150-250 Wh / kg based on total cell weight and 500-650 Wh / L per cell volume). Furthermore, in a lithium cathode based on a sulfur cathode active material, a volume energy density of 1,185 Wh / L, a weight density of 2,457 W / kg, and a volume density of 4,668 W / L were unthinkable.

  The report of energy and power density per weight of active material alone on a Ragone plot as many researchers do may not show a realistic picture of the performance of the assembled battery cell. It is 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. These components only add weight and volume to the device. Therefore, it is desirable to reduce the relative ratio of overhead component weights 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 having an electrode thickness of 150 μm, the weight ratio of the anode active material (eg, graphite or carbon) in the lithium ion battery is typically 12-17%, the weight ratio of the cathode active material. (For inorganic materials such as LiMn ₂ O ₄ ) is 22% to 41%, or 10% to 15% for organic or polymer materials. Corresponding weight ratios for Na ion batteries are expected to be very similar. This is because, between the two types of batteries, both the anode active material and the cathode active material have the same physical density, and the ratio of the cathode specific capacity to the anode specific capacity is also the same. Thus, factors 3-4 may be used to extrapolate the energy or power density of a device (cell) from properties based solely on the active material weight. In most scientific papers, the reported properties are typically based only on the active material weight, and the electrodes are typically very thin (<< 100 μm, and often << 50 μm). The active material weight is typically 5% to 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. Suggest that you can get After this factor is taken into account, the characteristics reported in these papers do not appear to be better than those of commercial batteries. Therefore, it must be very careful when reading and interpreting battery performance data reported in scientific papers and patent applications.

  FIG. 8 shows a Ragone plot of a series of Li-ion-S cells (graphene-wrapped Si nanoparticles or prelithiated Si nanoparticles) prepared by a conventional slurry coating process and the corresponding prepared by the process of the present invention. A cell Ragone plot is shown. These data also demonstrate the effect of the method according to the present invention to give an unexpectedly high energy density (both weight and volume) to Li-S battery cells.

Example 15: Achievable electrode thickness and its impact on the electrochemical performance of lithium battery cells The electrode thickness of alkaline metal batteries is considered a design parameter that can be freely adjusted to optimize device performance It tends to be. In practice, in contrast to this perception, the thickness of alkaline metal battery electrodes is subject to manufacturing limitations, and in real industrial manufacturing environments (eg, roll-to-roll coating facilities) It is not possible to produce electrodes with good structural integrity that exceeds. Conventional battery electrode designs are based on the coating of an electrode layer on a flat metal current collector, which has several main problems: (A) Thick coating on Cu foil or Al foil requires a long drying time (requires a heating area of 30-100 meters in length). (B) Thick electrodes are prone to delamination or cracking during drying and subsequent handling, and this problem is significant even with the 15-20% resin binder ratio expected to improve electrode integrity. It remains a limiting factor. Thus, such industry practice of roll coating slurry onto a solid flat current collector does not allow for high active mass loading. (C) Thick electrodes prepared by coating, drying, and compression make it difficult for the electrolyte (which is injected into the cell after the cell is formed) to penetrate through the electrode; It means many dry pockets or spots that are not wetted by. This suggests a low utilization of active material. The present invention solves these longstanding very important problems associated with alkaline metal batteries.

  FIG. 9 shows Li ion-S plotted over a feasible cathode thickness range of an S / RGO cathode prepared by a conventional method without delamination and cracking and a cathode prepared by a method according to the present invention. The cell level weight energy density (Wh / kg) and volumetric energy density (Wh / L) of the cell (prelithiated graphite anode + RGO supported S cathode) are shown.

  The electrodes can be manufactured with a thickness of up to 100-200 μm using conventional slurry coating methods. However, in contrast, there is no theoretical limit to the electrode thickness that can be achieved with the method according to the invention. Typically, practical electrode thicknesses are 10 μm to 1000 μm, more typically 100 μm to 800 μm, and most typically 200 μm to 600 μm.

These data further confirm the unexpected effectiveness of the method according to the present invention in producing ultra-thick lithium or sodium battery electrodes that could not be realized previously. These ultra-thick electrodes in sodium metal batteries are typically substantially> 15 mg / cm ² (more typically> 20 mg / cm ² , more typically> 30 mg / cm ² , often> 40 mg / Cm ² , and even> 50 mg / cm ² ) resulting in a very high sulfur cathode active material mass load. These high active mass loads could not be obtained with conventional alkali metal sulfur batteries formed by slurry coating processes. These high active mass loads resulted in very high weight and volume energy densities that were not previously achieved, assuming the same battery system.

  The dendrite problem commonly associated with Li, Na, and K metal secondary batteries is also solved by using the foamable current collector strategy of the present invention. Hundreds of cells were investigated and no failure due to penetration of dendrites through the separator was found in cells with foamable anode current collectors. SEM testing of samples from the sodium and potassium cells of the present invention showed that the alkali metal surface redeposited on the pore walls of the porous anode current collector appeared smooth and uniform, and the solid current collector on the anode It was confirmed that it does not show signs of sharp metal deposits or dendritic morphology as often observed in corresponding cells with (Cu foil). This is due to the lower exchange current density associated with the high specific surface area of the foamable current collector at the anode and the more uniform local electric field in the foam structure that promotes alkali metal deposition during repeated recharge procedures. possible.

Claims (44)

In a method for producing an alkali metal-sulfur battery, the alkali metal is selected from lithium (Li) and / or sodium (Na),
(A) providing a first conductive porous structure or a first conductive foam layer;
(B) providing a second conductive porous structure or a second conductive foam layer;
(C) a step of injecting or impregnating a first suspension into pores of the first conductive porous structure to form an anode electrode, wherein the first suspension comprises an anode active material Comprising an optional conductive additive and a first liquid or gel electrolyte, wherein the anode electrode and the first conductive porous structure are similar or equivalent in shape and size;
(D) Injecting or impregnating a second suspension into the pores of the second conductive porous structure to form a cathode electrode, wherein the second suspension comprises a cathode active material. , An optional conductive additive, and a second liquid or gel electrolyte, wherein the cathode active material is sulfur, lithium polysulfide, sodium polysulfide, sulfur-polymer composite, organosulfide, sulfur-carbon composite Selected from a sulfur-graphene complex, or a combination thereof, and the shape and dimensions of the cathode electrode and the second conductive porous structure are similar or equivalent;
(E) assembling the anode electrode, the separator, and the cathode electrode into the alkali metal-sulfur battery. The method of claim 1, wherein said steps (a), (b), (c), (d), and (e) are:
(A) preparing the first suspension and the second suspension;
(B) The first conductive porous structure as a porous anode current collector, the second conductive porous structure as a porous cathode current collector, and the porous anode current collector and the porous Assembling a porous cell framework comprising a porous separator disposed between the porous anode current collector and the porous anode current collector and / or the porous cathode current collector, (C) the anode active material has a material mass loading of 10 mg / cm ² or more within the anode electrode, or to the extent that the cathode active material will have a 15 mg / cm ² or more materials mass loading in the cathode electrode, the first in the pores of the anode current collector The anode electrode is formed by implanting Nigoeki, by injecting the second suspension into the pores of the cathode current collector is performed in order of the step of forming the cathode electrode,
The anode current collector, the separator, and the cathode current collector are protected before or after injection or impregnation of the first suspension, or before or after injection or impregnation of the second suspension. A method characterized in that it is assembled in a housing. The method of claim 1, wherein
Steps (a), (b), (c), (d), and (e)
a) providing one or more conductive porous layers, one or more wet anode layers of the first suspension, and one or more wet cathode layers of the second suspension; The conductive porous layer comprising interconnected conductive paths and at least 70% by volume pores;
b) sequentially stacking and solidifying a desired number of the porous layers and a desired number of the wet anode layers to form the anode electrode having a thickness of 200 μm or more;
c) placing the porous separator layer in contact with the anode electrode;
d) sequentially stacking and solidifying a desired number of the porous layers and a desired number of the wet anode layers to form the cathode electrode in contact with the porous separator, the cathode electrode And e) assembling and sealing the anode electrode, porous separator, and cathode electrode in a housing to produce the alkali metal-sulfur battery. I,
The anode active material has a material mass loading of 20 mg / cm ² or more in the anode electrode and / or the cathode active material has a material mass loading of 10 mg / cm ² or more in the cathode electrode. A method characterized by comprising. In a method for producing an alkali metal-sulfur battery, the alkali metal is selected from lithium (Li) and / or sodium (Na),
(A) Porous structure comprising a first conductive porous structure as a cathode current collector, an anode current collector, and a porous separator disposed between the anode current collector and the cathode current collector Assembling a porous cell framework, wherein the first conductive porous structure has a thickness of 200 μm or more and at least 70 volume% pores, and the anode current collector has two opposing And wherein at least one of the two major surfaces comprises a layer of sodium or lithium metal, or an alloy having at least 50% by weight of sodium or lithium element therein,
(B) preparing a first suspension of cathode active material dispersed in a first liquid electrolyte, wherein the cathode active material is sulfur, lithium polysulfide, sodium polysulfide, sulfur-polymer; Selected from a complex, an organosulfide, a sulfur-carbon complex, a sulfur-graphene complex, or a combination thereof;
(C) Injecting the first suspension into the pores of the first conductive porous structure to such an extent that the cathode active material has an electrode active material loading of 7 mg / cm ² or more, Forming an electrode and the anode, the separator, and the cathode are assembled in a protective housing before or after the implantation step is performed. In a method for producing an alkali metal-sulfur battery, the alkali metal is selected from lithium (Li) and / or sodium (Na),
(A) providing at least one or more conductive porous structures and one or more wet cathode layers of a cathode active material and optional conductive additives mixed with a liquid electrolyte; The cathode active material is selected from sulfur, lithium polysulfide, sodium polysulfide, sulfur-polymer composite, organosulfide, sulfur-carbon composite, sulfur-graphene composite, or combinations thereof, and the conductive porous material A layer of material comprising interconnected conductive paths and at least 80% by volume pores;
(B) providing an anode electrode having an anode current collector having two opposite major surfaces, wherein at least one of the two major surfaces has at least 50 wt% Na and / or Li therein Depositing a layer of an alkali metal or alkali metal alloy with the element;
(C) placing a porous separator layer in contact with the anode electrode;
(D) stacking and solidifying a desired number of the porous layers and a desired number of the wet cathode layers in an alternating order to form the cathode electrode in contact with the porous separator, The cathode electrode has a thickness of 200 μm or more, and the step (d) is performed before or after step (b);
(E) assembling and sealing the anode electrode, the porous separator, and the cathode electrode in a housing to manufacture the alkali metal battery,
The method wherein the cathode active material has a material mass loading of 10 mg / cm ² or more within the cathode electrode. The method of claim 1, wherein the cathode active material is sulfur bound to pore walls of the cathode current collector, sulfur bound to carbon or graphite material, or trapped by carbon or graphite material, polymer. Sulfur, sulfur-carbon compound, metal sulfide M _x S _y bonded to or confined by a polymer (where x is an integer of 1 to 3, y is an integer of 1 to 10, and M is A metal element selected from Li, Na, K, Mg, Ca, transition metals, metals of Groups 13 to 17 of the periodic table, and combinations thereof. 5. The method of claim 4, wherein the cathode active material is sulfur bound to pore walls of the cathode current collector, sulfur bound to carbon or graphite material, or trapped by carbon or graphite material, polymer. Sulfur, sulfur-carbon compound, metal sulfide M _x S _y bonded to or confined by a polymer (where x is an integer of 1 to 3, y is an integer of 1 to 10, and M is , Li, Na, K, Mg, Ca, transition metals, metals in Groups 13 to 17 of the periodic table, and combinations thereof) . 6. The method of claim 5, wherein the cathode active material is sulfur bound to pore walls of the cathode current collector, sulfur bound to carbon or graphite material, or trapped by carbon or graphite material, polymer. Sulfur, sulfur-carbon compound, metal sulfide M _x S _y bonded to or confined by a polymer (where x is an integer of 1 to 3, y is an integer of 1 to 10, and M is A metal element selected from Li, Na, K, Mg, Ca, transition metals, metals of Groups 13 to 17 of the periodic table, and combinations thereof.   The method of claim 1, wherein the conductive porous structure is a metal foam, a metal web or screen, a perforated metal sheet base structure, a metal fiber mat, a metal nanowire mat, a conductive polymer nanofiber mat, Conductive polymer foam, conductive polymer coated fiber foam, carbon foam, graphite foam, carbon aerogel, carbon xerogel, graphene foam, graphene oxide foam, reduced graphene oxide foam, carbon fiber foam, graphite fiber A method characterized in that it is selected from foams, exfoliated graphite foams, and combinations thereof.   5. The method of claim 4, wherein the conductive porous layer comprises a metal foam, a metal web or screen, a perforated metal sheet base structure, a metal fiber mat, a metal nanowire mat, a conductive polymer nanofiber mat, Conductive polymer foam, conductive polymer coated fiber foam, carbon foam, graphite foam, carbon aerogel, carbon xerogel, graphene foam, graphene oxide foam, reduced graphene oxide foam, carbon fiber foam, graphite fiber A method characterized in that it is selected from foams, exfoliated graphite foams, and combinations thereof.   6. The method of claim 5, wherein the conductive porous layer comprises a metal foam, a metal web or screen, a perforated metal sheet base structure, a metal fiber mat, a metal nanowire mat, a conductive polymer nanofiber mat, Conductive polymer foam, conductive polymer coated fiber foam, carbon foam, graphite foam, carbon aerogel, carbon xerogel, graphene foam, graphene oxide foam, reduced graphene oxide foam, carbon fiber foam, graphite fiber A method characterized in that it is selected from foams, exfoliated graphite foams, and combinations thereof. 2. The method of claim 1 wherein the ratio of cathode thickness to cathode current collector thickness is 0.8 / 1 to 1 / 0.8 and / or the cathode active material is greater than 15 mg / cm < ² >. A method comprising an electrode active material loading, wherein the cathode current collector has a thickness of 300 μm or more. The method of claim 1, wherein the cathode active material is
(A) Nano selected from soft carbon, hard carbon, polymeric carbon or carbonized resin, mesophase carbon, coke, carbonized pitch, carbon black, activated carbon, nanocell carbon foam, or partially graphitized carbon particles Structured or porous disordered carbon material;
(B) nano graphene platelets selected from single layer graphene sheets or multilayer graphene platelets;
(C) a carbon nanotube selected from single-walled carbon nanotubes or multi-walled carbon nanotubes;
(D) carbon nanofibers, nanowires, metal oxide nanowires or fibers, conductive polymer nanofibers, or combinations thereof;
(E) a carbonyl-containing organic or polymer molecule;
(F) a functional material containing a carbonyl group, a carboxylic acid group, or an amine group that reversibly captures sulfur;
And supported by a functional material or nanostructured material selected from the group consisting of and combinations thereof.   2. The method of claim 1, wherein the anode active material is selected from alkali metals, alkali metal alloys, alkali metals or mixtures of alkali metal alloys and alkali intercalation compounds, alkali element-containing compounds, and combinations thereof. Comprising a source of alkaline ions. The method according to claim 1, wherein the anode active material is petroleum coke, carbon black, amorphous carbon, activated carbon, hard carbon, soft carbon, template carbon, hollow carbon nanowire, hollow carbon sphere, natural graphite, artificial graphite, Lithium or sodium titanate, 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 to 1.0) , Na ₂ C ₈ H ₄ O ₄ , carboxylate based material, C ₈ H ₄ Na ₂ O ₄ , C ₈ H ₆ O ₄ , C ₈ H ₅ NaO ₄ , C ₈ Na ₂ F ₄ O ₄ , C A method comprising an alkali intercalation compound selected from ₁₀ H ₂ Na ₄ O ₈ , C ₁₄ H ₄ O ₆ , C ₁₄ H ₄ Na ₄ O ₈ , and combinations thereof. The method of claim 1, wherein the anode active material is
(A) Lithium or 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;
(B) lithium or sodium containing alloys or intermetallic compounds of Si, Ge, Sn, Pb, Sb, Bi, Zn, Al, Ti, Co, Ni, Mn, Cd, and mixtures thereof;
(C) Lithium or 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;
(D) a lithium or sodium salt; and (e) an alkali intercalation compound or alkali-containing compound selected from the group of materials such as graphene sheets preloaded with lithium or sodium.   17. The alkali metal-sulfur battery according to claim 16, wherein the graphene sheet preloaded with lithium or sodium is pure graphene, graphene oxide, reduced graphene oxide, graphene fluoride, graphene chloride, graphene bromide, or iodide. Pre-sodium of graphene, hydrogenated graphene, nitrogenated graphene, boron-doped graphene, nitrogen-doped graphene, chemically functionalized graphene, physically or chemically activated or etched versions thereof, and combinations thereof Alkali metal-sulfur battery, characterized in that it is selected from hydrogenated or prelithiated versions.   2. The method of claim 1, wherein the first or second liquid or gel electrolyte is selected from an aqueous electrolyte, an organic electrolyte, an ionic liquid electrolyte, a mixture of an organic electrolyte and an ionic electrolyte, or a mixture of them and a polymer. A method characterized by being made.   19. The method of claim 18, wherein the aqueous electrolyte comprises a sodium or potassium salt dissolved in water or a mixture of water and alcohol. The method of claim 19, sodium salt or lithium _{salt, Na 2 SO 4, Li 2} SO 4, mixtures thereof, NaOH, LiOH, NaCl, LiCl , NaF, LiF, NaBr, LiBr, NaI, LiI, And a mixture thereof.   19. The method of claim 18, wherein the organic 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), γ-butyrolactone (γ-BL), acetonitrile (AN), ethyl acetate (EA), propyl formate (PF), methyl formate (MF), toluene, xylene, methyl acetate (MA) ) And a liquid organic solvent selected from the group consisting of fluoroethylene carbonate (FEC), vinylene carbonate (VC), allyl ethyl carbonate (AEC), hydrofluoroether, and combinations thereof. The method according to claim 18, wherein the organic electrolyte, lithium perchlorate (LiClO _4), lithium hexafluorophosphate (LiPF _6), lithium borofluoride (LiBF _4), lithium hexafluoroarsenate (LiAsF ₆ ), lithium trifluoro-metasulfonate (LiCF ₃ SO ₃ ), lithium bis-trifluoromethylsulfonylimide (LiN (CF ₃ SO ₂ ) ₂ ), lithium bis (oxalate) 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, lithium bisperfluoroethylsulfonylimide (LiBETI), sodium perchlorate ( ACLO _4), potassium perchlorate (KClO _4), sodium hexafluorophosphate (NaPF _6), potassium hexafluorophosphate _(KPF 6), sodium borofluoride (NaBF _4), potassium borofluoride _(KBF 4) , Sodium hexafluoroarsenate, potassium hexafluoroarsenate, sodium trifluoro-metasulfonate (NaCF ₃ SO ₃ ), potassium trifluoro-metasulfonate (KCF ₃ SO ₃ ), sodium bis-trifluoromethylsulfonylimide ( An alkali metal salt selected from NaN (CF ₃ SO ₂ ) ₂ ), sodium trifluoromethanesulfonimide (NaTFSI), potassium bis-trifluoromethylsulfonylimide (KN (CF ₃ SO ₂ ) ₂ ), and combinations thereof A method characterized by comprising.   19. The method of claim 18, wherein the ionic liquid electrolyte is tetra-alkyl ammonium, di-, tri-, or tetra-alkyl imidazolium, alkyl pyridinium, dialkyl-pyrrolidinium, dialkyl piperidinium, tetraalkyl phosphonium, tri-alkyl. A process comprising an ionic liquid solvent selected from room temperature ionic liquids having a cation selected from alkylsulfonium and combinations thereof. The method of claim 23, wherein the ionic liquid _{^{solvent, BF 4 -, B (CN}} ) 4 -, CH 3 BF 3 -, CH 2 CHBF 3 -, CF 3 BF 3 -, C 2 F 5 BF 3 _{^{-, n-C 3 F 7}} BF 3 -, n-C 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 ⁻ , and a room temperature ionic liquid having an anion selected from combinations thereof. (A) (i) an anode active material slurry comprising an anode active material and an optional conductive additive dispersed in a first liquid or gel electrolyte; and (ii) a conductive material acting as a 3D anode current collector. An anode having a porous structure, wherein the conductive porous structure has at least 70% by volume of pores, and the anode active material slurry is disposed within the pores of the conductive porous structure. Being the anode,
(B) (i) a cathode active material slurry comprising a cathode active material and an optional conductive additive dispersed in a second liquid or gel electrolyte that is the same as or different from the first liquid or gel electrolyte; (ii) ) A cathode having a conductive porous structure acting as a 3D cathode current collector, wherein the conductive porous structure has at least 70% by volume of pores, and the cathode active material slurry has the conductive conductivity Disposed within the pores of the porous structure, wherein the cathode active material is bonded to or confined by sulfur, carbon or graphite material bonded to the pore walls of the cathode current collector Sulfur, sulfur bound to polymer or trapped by polymer, sulfur-carbon compound, metal sulfide M _x S _y (where x is an integer from 1 to 3) Y is an integer of 1 to 10, and M is a metal selected from Li, Na, K, Mg, Ca, transition metal, Group 13 to Group 17 metal of the periodic table, or combinations thereof (C) an alkali metal-sulfur battery comprising: a cathode selected from (a) element; and (c) a separator disposed between the anode and the cathode;
The ratio of anode thickness to anode current collector thickness is 0.8 / 1 to 1 / 0.8, and / or the ratio of cathode thickness to cathode current collector thickness is 0.8 / 1 to 1/0. 8 and the 3D porous anode current collector or cathode current collector has a thickness of 200 μm or more, and the cathode active material comprises an electrode active material loading of more than 10 mg / cm ² ; And / or the anode active material and the cathode active material together exceed 40% by weight of the battery cell weight. (A) an anode having an anode active material coated on or in physical contact with the anode current collector, wherein the anode active material is in ionic contact with the first electrolyte; ,
(B) (i) a cathode active material slurry comprising a cathode active material and an optional conductive additive dispersed in a second liquid or gel electrolyte that is the same as or different from the first liquid or gel electrolyte; ii) a cathode having a conductive porous structure acting as a 3D cathode current collector, wherein the conductive porous structure has at least 70 volume% pores, and the cathode active material slurry comprises Disposed within the pores of a conductive porous structure, the cathode active material is sulfur, lithium polysulfide, sodium polysulfide, sulfur-polymer composite, organosulfide, sulfur-carbon composite, sulfur-graphene composite Or a cathode selected from a combination thereof; and (c) an anode comprising a separator disposed between the anode and the cathode. In Lucari metal-sulfur battery,
The ratio of cathode thickness to cathode current collector thickness is 0.8 / 1 to 1 / 0.8 and / or the cathode active material comprises an electrode active material loading greater than 15 mg / cm ² ; The alkali metal-sulfur battery, wherein the 3D cathode current collector has a thickness of 200 μm or more.   27. The alkali metal-sulfur battery according to claim 26, wherein the anode current collector includes a porous foam structure. The alkali metal-sulfur battery of claim 26, wherein the cathode active material is
a) Nanostructures selected from soft carbon, hard carbon, polymeric carbon or carbonized resin, mesophase carbon, coke, carbonized pitch, carbon black, activated carbon, nanocell carbon foam, or partially graphitized carbon particles Or porous disordered carbon material;
b) nano graphene platelets selected from single layer graphene sheets or multilayer graphene platelets;
c) carbon nanotubes selected from single-walled carbon nanotubes or multi-walled carbon nanotubes;
d) carbon nanofibers, nanowires, metal oxide nanowires or fibers, conductive polymer nanofibers, or combinations thereof;
e) a carbonyl-containing organic or polymer molecule;
f) a functional material containing a carbonyl group, a carboxyl group, or an amine group for irreversibly capturing sulfur;
And an alkaline metal-sulfur battery supported by a functional material or nanostructured material selected from the group consisting of combinations thereof.   27. The alkali metal-sulfur battery of claim 26, wherein the anode active material comprises an alkali metal, an alkali metal alloy, an alkali metal or a mixture of an alkali metal alloy and an alkali intercalation compound, an alkali element-containing compound, and their An alkali metal-sulfur battery comprising an alkali ion source selected from a combination. 26. The alkali metal-sulfur battery of claim 25, wherein the anode active material is petroleum coke, carbon black, amorphous carbon, activated carbon, hard carbon, soft carbon, template carbon, hollow carbon nanowire, hollow carbon sphere, natural graphite. , Artificial graphite, lithium or sodium titanate, 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 (0.2 ≦ x ≦ _{1.0), Na 2 C 8 H} 4 O 4, carboxylate-based _{material, C 8 H 4 Na 2 O} 4, C 8 H 6 O 4, C 8 H 5 NaO 4, C 8 Na 2 F 4 this including _{O 4, C 10 H 2 Na} 4 O 8, C 14 H 4 O 6, C 14 H 4 Na 4 O 8, and alkaline intercalation compound combinations thereof Sulfur battery - alkali metal, characterized in. 26. The alkali metal-sulfur battery of claim 25, wherein the anode active material is
a) Lithium or 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;
b) Lithium or sodium containing alloys or intermetallic compounds of Si, Ge, Sn, Pb, Sb, Bi, Zn, Al, Ti, Co, Ni, Mn, Cd, and mixtures thereof;
c) Lithium or 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;
An alkali metal-sulfur battery comprising d) a lithium or sodium salt; and e) an alkali intercalation compound or an alkali-containing compound selected from the group of materials such as graphene sheets preloaded with lithium or sodium.   32. The alkali metal-sulfur battery according to claim 31, wherein the graphene sheet preloaded with lithium or sodium is pure graphene, graphene oxide, reduced graphene oxide, graphene fluoride, graphene chloride, graphene bromide, or iodide. Pre-sodium of graphene, hydrogenated graphene, nitrogenated graphene, boron-doped graphene, nitrogen-doped graphene, chemically functionalized graphene, physically or chemically activated or etched versions thereof, and combinations thereof Alkali metal-sulfur battery, characterized in that it is selected from hydrogenated or prelithiated versions.   27. The alkali metal-sulfur battery according to claim 26, wherein the first electrolyte is a gel electrolyte or a solid electrolyte.   26. The alkali metal-sulfur battery according to claim 25, wherein the first or second liquid or gel electrolyte is an aqueous electrolyte, an organic electrolyte, an ionic liquid electrolyte, a mixture of an organic electrolyte and an ionic electrolyte, or a polymer thereof. An alkali metal-sulfur battery, characterized in that it is selected from a mixture of:   35. The alkali metal-sulfur battery according to claim 34, wherein the aqueous electrolyte includes a sodium salt or a potassium salt dissolved in water or a mixture of water and alcohol. In the alkali metal ion battery according to claim 35, wherein the sodium or lithium _{salt, Na 2 SO 4, Li 2} SO 4, NaOH, LiOH, NaCl, LiCl, NaF, LiF, NaBr, LiBr, NaI, LiI, And an alkali metal ion battery characterized in that it is selected from these and mixtures thereof.   35. The alkali metal-sulfur battery according to claim 34, wherein the organic 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), γ-butyrolactone (γ-BL), acetonitrile (AN), ethyl acetate (EA), propyl formate (PF), methyl formate (MF), toluene, xylene, Characterized in that it comprises a liquid organic solvent selected from the group consisting of methyl acetate (MA), fluoroethylene carbonate (FEC), vinylene carbonate (VC), allyl ethyl carbonate (AEC), hydrofluoroether, and combinations thereof. Alkali metal-sulfur battery. 35. The alkali metal-sulfur battery according to claim 34, wherein the organic electrolyte is lithium perchlorate (LiClO ₄ ), lithium hexafluorophosphate (LiPF ₆ ), lithium borofluoride (LiBF ₄ ), or hexafluorohexafluoride. Lithium oxide (LiAsF ₆ ), lithium trifluoro-metasulfonate (LiCF ₃ SO ₃ ), lithium bis-trifluoromethylsulfonylimide (LiN (CF ₃ SO ₂ ) ₂ ), lithium bis (oxalate) 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, lithium bisperfluoroethylsulfonylimide (LiBETI), Excessive Sodium periodate (NaClO _4), potassium perchlorate (KClO _4), sodium hexafluorophosphate (NaPF _6), potassium hexafluorophosphate _(KPF 6), sodium borofluoride (NaBF _4), potassium borofluoride (KBF ₄ ), sodium hexafluoroarsenate, potassium hexafluoroarsenate, sodium trifluoro-metasulfonate (NaCF ₃ SO ₃ ), potassium trifluoro-metasulfonate (KCF ₃ SO ₃ ), bis-trifluoromethyl imide sodium _{(NaN (CF 3 SO 2)} 2), trifluoromethane sulfonimide sodium (NaTFSI), bis - trifluoromethyl sulfonyl imide potassium _{(KN (CF 3 SO 2)} 2), and combinations thereof Containing alkali metal salt Sulfur battery - alkali metal, characterized.   35. The alkali metal-sulfur battery of claim 34, wherein the ionic liquid electrolyte is tetra-alkyl ammonium, di-, tri-, or tetra-alkyl imidazolium, alkyl pyridinium, dialkyl-pyrrolidinium, dialkyl piperidinium, tetra. An alkali metal-sulfur battery comprising an ionic liquid solvent selected from room temperature ionic liquids having a cation selected from alkylphosphonium, trialkylsulfonium, and combinations thereof. 40. The alkali metal-sulfur battery according to claim 39, 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 -, n-}} C 3 F 7 BF 3 -, n-C 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 -}} , and alkali metal, characterized in that it is selected from the room temperature ionic liquids having the selected anions combinations thereof - sulfur battery. 2. The conductive metal foam according to claim 1, wherein the 3D porous anode current collector or the 3D porous cathode current collector has a thickness of 200 μm or more having at least 85% by volume of pores. 3. And / or the anode active material has a mass loading of 20 mg / cm ² or more and occupies at least 25% by weight or volume% of the total battery cell and / or the cathode active material is 20 mg An alkali metal-sulfur battery having a mass loading of at least / cm ² . 2. The alkali metal-sulfur battery according to claim 1, wherein the 3D porous anode current collector or the 3D porous cathode current collector has a thickness of 300 μm or more having at least 90% by volume of pores. And / or the anode active material has a mass loading of 25 mg / cm ² or more, occupies at least 30% by weight or volume% of the total battery cell, and / or the cathode active material is 25 mg An alkali metal-sulfur battery having a mass loading of at least / cm ² . 2. The conductive metal foam according to claim 1, wherein the 3D porous anode current collector or the 3D porous cathode current collector has a thickness of 400 μm or more having at least 95% by volume of pores. 3. And / or the anode active material has a mass loading of 30 mg / cm ² or more, occupies at least 35% by weight or volume% of the total battery cell, and / or the cathode active material is 30 mg An alkali metal-sulfur battery having a mass loading of / cm ² or more.   The alkali metal-sulfur battery of claim 1, wherein the 3D porous anode current collector or 3D porous cathode current collector is a metal foam, a metal web or screen, a perforated metal sheet based 3D structure, Metal fiber mat, metal nanowire mat, conductive polymer nanofiber mat, conductive polymer foam, conductive polymer coated fiber foam, carbon foam, graphite foam, carbon aerogel, carbon xerogel, graphene foam, graphene oxide foam An alkaline metal-sulfur battery comprising a conductive foam structure selected from the group, reduced graphene oxide foam, carbon fiber foam, graphite fiber foam, exfoliated graphite foam, and combinations thereof.

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