Carbon-free cathodes for lithium-sulfur batteries

Abstract

The present application presents a carbon-free (including relatively carbon-free) cathode material for a cathode, which comprises (i) sulfur and / or lithium sulfide, and (ii) a different non-carbon electroactive material, such as a metal chalcogenide. In certain embodiments, the carbon-free cathode material has been found to facilitate improved ion transport while maintaining sufficient mechanical stability and electrical connection of the cathode without the use of conductive carbon additives. The present disclosure provides, among other things, a cathode material and a battery including the same. The cathode material may comprise at least one electroactive sulfur material and a non-sulfur non-carbon material (e.g., the cathode material is substantially free of carbon).

Description

[Background technology]

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS This application claims priority to and the benefit of U.S. Provisional Patent Application No. 63 / 331,245, filed April 14, 2022, which is incorporated by reference in its entirety.

[0002] Considerable research is being conducted to develop high energy density, long cycle life, low cost lithium ion batteries, particularly for use in electric vehicles and consumer electronics.

[0003] Sulfur is a low-cost, high specific energy material that is a by-product of the oil and gas industry. Sulfur-based battery cathodes have been investigated for some time. As a high-energy density cathode material, sulfur holds promise for removing the need for cobalt and nickel in lithium batteries. Cobalt is expensive and toxic, and its mining in certain regions can result in loose regulation and unethical practices. Nickel has high energy density, but there are long-term nickel supply concerns, which, for example, have recently driven Tesla's move away from nickel-containing batteries.

[0004] It is difficult to fabricate sulfur cathodes capable of commercial levels of performance, for example, because sulfur by-products degrade performance and limit cycle life, and because low-density monofunctional materials such as conductive carbon additives adversely affect the energy density of the prepared sulfur cathodes.

[0005] The positive electrodes of lithium batteries, such as lithium-sulfur battery positive electrodes, almost always contain conductive carbon. For example, conductive graphite additives are often introduced to enhance the mechanical stability and electronic conductivity of the positive electrode. However, carbon has poor lithium ion transport properties (e.g., the transport of lithium ions through the positive electrode pore network may be hindered by this carbon-containing mixed phase) and does not provide electrochemical capacity to the battery. Furthermore, carbon has a low gravimetric density, so its presence significantly reduces the volumetric energy density of the sulfur positive electrode composite. Attempts have been made to improve such low ionic conductivity. For example, the use of conductive carbon-sulfur membranes with interconnected mesopores has been considered as an improved positive electrode for lithium-sulfur batteries.

[0006] However, this does not address the reduced energy density, and there remains a need for a lithium-sulfur battery positive electrode composition with satisfactory mechanical stability and electrical properties that overcome the problem of lithium ion transport inhibition and reduced energy density due to the carbon-containing phase of the positive electrode. Summary of the Invention [Means for solving the problem]

[0007] The present disclosure provides, among other things, a cathode material and a battery including the same. The cathode material can include at least one electroactive sulfur material and a non-sulfur, non-carbon material (e.g., the cathode material is substantially free of carbon).

[0008] In some embodiments, the present disclosure relates to a cathode material for a carbon-free sulfur cathode, the cathode material comprising at least one electroactive sulfur conversion cathode material and a non-sulfur, non-carbon electroactive material, wherein the carbon content of the cathode material (e.g., carbon-free cathode) is 5 wt.% or less (e.g., 2 wt.% or less, 1 wt.% or less, 0.5 wt.% or less, or 0.1 wt.% or less).

[0009] In some embodiments, the non-sulfur non-carbon electroactive material is a material that is capable of converting sulfur to sulfur at a voltage range between about 1.8 V and about 2.6 V vs. Li / Li+ For example, about 2.0V to about 2.4V vs. Li / Li + ) is an intercalation material having a structure that can reversibly insert lithium ions within a voltage range that overlaps with that of

[0010] In some embodiments, the non-sulfur non-carbon electroactive material is a conversion material (e.g., a material that is in the voltage range of sulfur conversion (e.g., about 1.8 V to about 2.6 V vs. Li / Li + For example, about 2.0V to about 2.4V vs. Li / Li + ) that undergo electrochemical conversion reactions within a voltage range that overlaps with

[0011] In some embodiments, the non-sulfur non-carbon electroactive material is a chalcogenide (eg, a metal chalcogenide, such as a metal sulfide).

[0012] In some embodiments, the non-sulfur, non-carbon electroactive material is also an electronic conductor.

[0013] In some embodiments, the non-sulfur, non-carbon electroactive material has a discharge capacity.

[0014] In some embodiments, the cathode material comprises a core-shell structure. In some embodiments, the cathode material comprises cores each having a surrounding shell, the cores being formed of an electroactive sulfur conversion material (e.g., Li 2 S 2 and / or Li 2 S), and the shell comprises a non-sulfur, non-carbon electroactive material (e.g., one or more metal chalcogenides).

[0015] In some embodiments, the core-shell structures have an average core diameter in the range of 50 to 300 nm and an average shell thickness in the thickness range of 1 to 20 nm (eg, a thickness of 10 nm or less).

[0016] In some embodiments, the core-shell structure has at least 10% by weight of non-sulfur non-carbon electroactive material (e.g., metal chalcogenide) relative to sulfur (e.g., 10-90% by weight of non-sulfur non-carbon electroactive material (e.g., 30-70% by weight of non-sulfur non-carbon electroactive material)).

[0017] In certain embodiments, the at least one electroactive sulfur converting cathode material is S 8 Sulfur in the form of cyclic octaatomic molecules, lithium sulfide (e.g., Li 2 S 2 and / or Li 2 S), electroactive organosulfur compounds, and electroactive sulfur-containing polymers.

[0018] In some embodiments, the invention relates to a positive electrode comprising any of the positive electrode materials described herein, wherein the percentage of carbon in the positive electrode is 5 wt.% or less (e.g., 2 wt.% or less, 1 wt.% or less, 0.5 wt.% or less, or 0.1 wt.% or less).

[0019] In some embodiments, the positive electrode material is disposed in a film (eg, a film with a binder).

[0020] In another aspect, the invention relates to a battery (e.g., a rechargeable battery) comprising: (i) a positive electrode described herein; and (ii) an electrolyte in contact with the positive electrode.

[0021] In some embodiments, the battery further comprises a negative electrode, hi some embodiments, the negative electrode is a protected lithium metal negative electrode.

[0022] In some embodiments, the battery further comprises a protected current collector.

[0023] Any two or more of the features described herein, including in this Summary section, may be combined to form embodiments of the present disclosure, whether or not specifically and explicitly described in a separate combination herein.

[0024] The present teachings described herein will be more fully understood from the following description of various exemplary embodiments when read in conjunction with the accompanying drawings. It should be understood that the drawings described below are for illustrative purposes only and are not intended to limit the scope of the present teachings in any manner. The foregoing and other objects, aspects, features, and advantages of the present disclosure will become more apparent and can be better understood by referring to the following description in conjunction with the accompanying drawings. [Brief description of the drawings]

[0025] [Figure 1] FIG. 8 illustrates a cross-section of an electrochemical cell 800 according to an exemplary embodiment of the present disclosure.

[0026] [Diagram 2] FIG. 1 illustrates an example of a battery according to various embodiments described herein. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0027] definition About / Approximately: The term "about" or "approximately" when used herein with respect to a value refers to a value that is similar to the value referred to in the context. In general, a person skilled in the art who understands the context will recognize the appropriate degree of variation that is encompassed by "about" or "approximately" in that context. For example, in some embodiments, as provided herein, the term "about" can encompass a range of values ​​that is within 25%, 20%, 19%, 18%, 17%, 16%, 15%, 14%, 13%, 12%, 11%, 10%, 9%, 8%, 7%, 6%, 5%, 4%, 3%, 2%, 1%, or less of the value referred to.

[0028] Carbon: As used herein in connection with positive electrode materials, "carbon" refers to elemental carbon or a material substantially composed of elemental carbon, examples of which include graphite, carbon black, graphene, carbon nanotubes, and derivatives of such materials (e.g., oxidized, nitrogen-doped, or carboxylated graphene derivatives). Carbon-containing organic molecules such as hydrocarbons, polymers, and solvents are not included in this term unless otherwise indicated. Similarly, in connection with terms such as "carbon-free" and "non-carbon materials," what is to be understood not to be included are these elemental forms of carbon.

[0029] Intercalation Material: As used herein, the term "intercalation material" refers to a material in which another substance or species (e.g., ions, metal ions) is reversibly inserted or included into the vacancies, interstitial sites, interstices, or between the layers of the intercalation material, or some combination thereof.

[0030] Electroactive Material: As used herein, the term "electroactive material" refers to a composition that includes one or more components that can change their oxidation state in the charge transfer step of an electrochemical reaction.

[0031] Lithium Alloy: As used herein, the term lithium alloy refers to a material formed by the combination of lithium with other metal or metalloid elements. Non-limiting examples include lithium silicon compounds and alloys of lithium with metals such as sodium, cesium, indium, aluminum, zinc, and silver.

[0032] Nanoparticles, Nanostructures, Nanomaterials: As used herein, these terms may be used interchangeably to refer to particles of nanoscale dimensions or materials having nanoscale structures. Nanoparticles can have virtually any shape or configuration, such as tubes, wires, laminates, sheets, lattices, boxes, cores and shells, or combinations thereof.

[0033] Substantially: As used herein, the term "substantially" refers to a qualitative state in which a desired feature or characteristic is exhibited to a complete or nearly complete degree or extent.

[0034] Elements of different embodiments described herein may be combined to create other embodiments not specifically described above. Elements may be omitted from the devices described herein if they do not adversely affect the operation of the devices. Various separate elements may be combined into one or more individual elements to perform the functions described herein.

[0035] The claimed objects, devices, compositions, systems, methods, and processes are intended to encompass variations and modifications developed using information from the embodiments described herein. It is contemplated herein that variations and / or modifications of the objects, devices, compositions, systems, methods, and processes described herein may be made.

[0036] Throughout this specification, when objects, devices, compositions, and systems are described as having, including, or comprising particular elements, or processes and methods are described as having, including, or comprising particular steps, it is intended that there are additional objects, devices, compositions, and systems of the invention that consist essentially of or consist of the recited elements, and that there are additional processes and methods of the invention that consist essentially of or consist of the recited process steps.

[0037] It should be understood that the order of steps or order for performing certain actions is not essential so long as the invention remains operable. Moreover, two or more steps or actions may be conducted simultaneously.

[0038] The citation of any publication in this specification is not an admission that such publication is prior art with respect to any of the claims presented in this application. The "Background" section is provided for clarity and is not intended as a description of prior art with respect to any claim.

[0039] Headings are provided for the convenience of the reader, and the presence and / or placement of headings is not intended to limit the scope of the subject matter described herein.

[0040] Provided herein are positive electrode materials for producing carbon-free (including relatively carbon-free) positive electrodes, which include (i) a sulfur-based active material, and (ii) a different non-carbon electroactive material, such as a metal chalcogenide. In certain embodiments, the carbon-free positive electrode materials have been found to facilitate improved ion transport while maintaining sufficient mechanical stability and electrical conductivity of the positive electrode without the use of graphite or other carbon additives.

[0041] In certain embodiments, the non-carbon electroactive material is a material that is capable of converting sulfur to lithium sulfide at a voltage between about 1.8 V and about 2.6 V vs. Li / Li + For example, about 2.0V to about 2.4V vs. Li / Li + ), which can reversibly insert lithium ions during operation in a voltage range approximately corresponding to the voltage range of 1000 V. Intercalation is a process by which mobile ions or molecules are reversibly incorporated into vacant sites in the crystal lattice of a host network. The intercalation process is generally characterized by minimal volume change and mechanical strain during repeated insertion and extraction of ions during charge and discharge. Intercalation cathode materials include a solid host network that can reversibly store guest ions that are inserted into and removed from the host network.

[0042] In further particular embodiments, the cathode material has a core-shell structure (e.g., nanostructure), in which the core contains the sulfur active material and the surrounding shell contains the non-carbon electroactive material. In particular embodiments, the structure is nanoporous. In particular embodiments, the average diameter of the core is, for example, less than about 1000 nm, less than about 500 nm, less than about 250 nm, less than about 100 nm, less than about 80 nm, less than about 70 nm, less than about 60 nm, less than about 50 nm, less than about 40 nm, less than about 30 nm, less than about 25 nm, less than about 20 nm, less than about 10 nm, or less than about 5 nm, and / or the average diameter of the core may be within any range between any two of the above values. In particular embodiments, the core is spherical, approximately spherical, or amorphous in shape. In certain embodiments, the average diameter of the core is about 50 to about 500 nm, about 50 to about 200 nm, about 20 to about 100 nm, about 100 to about 300 nm, or about 200 to about 400 nm.

[0043] In certain embodiments, the average thickness of the shell surrounding the core is, for example, less than about 1000 nm, less than about 500 nm, less than about 250 nm, less than about 100 nm, less than about 80 nm, less than about 70 nm, less than about 60 nm, less than about 50 nm, less than about 40 nm, less than about 30 nm, less than about 25 nm, less than about 20 nm, less than about 15 nm, less than about 10 nm, less than about 5 nm, less than about 3 nm, less than about 2 nm, or less than about 1 nm, and / or the average thickness of the shell may be within any range between any two of the above values. In certain embodiments, the average thickness of the shell surrounding the core is about 1 to about 50 nm, about 2 to about 20 nm, about 1 to about 10 nm, about 10 to about 20 nm, about 5 to about 15 nm, or about 1 to about 5 nm.

[0044] In certain embodiments, the core of the core-shell particle provided is composed of substantially pure electroactive sulfur material. In certain embodiments, the core comprises a composite of the electroactive sulfur material with an additional material, such as an inorganic solid, a metal, a polymer, or other non-sulfur electroactive material. Such a composite may comprise a simple physical mixture of materials, or may comprise a composite of more complex structure, such as a porous framework material infused with sulfur electroactive material.

[0045] In certain embodiments, the non-carbon electroactive shell of the provided core-shell particles is non-porous and / or substantially impermeable to liquids (e.g., electrolytes) and / or impermeable to sulfur or polysulfides (or mixtures of electrolytes and polysulfides). Such configurations allow electrons and lithium ions to access the electroactive sulfur core while preventing redistribution of the electroactive sulfur material within the cathode or battery. Such configurations can be advantageous in this regard.

[0046] In other embodiments, the non-carbon electroactive shell of the provided core-shell particles is porous and / or permeable (e.g., permeable to liquid electrolyte or components thereof). In certain embodiments, such a permeable shell may be advantageous to ensure electrolyte contact with the electroactive sulfur and / or to prevent the shell from rupturing or being damaged by physical strain due to volume changes in the core. In certain embodiments, such shells are nanoporous, e.g., having pores with diameters less than 1 nm (e.g., less than 0.5 nm, less than 0.4 nm, or less than 0.3 nm, or less than 0.2 nm) and / or with an average pore size within any range between any two of the above values. In certain embodiments, the average pore size of the core and / or shell is less than 1 nm, e.g., less than 0.9 nm, less than 0.8 nm, less than 0.7 nm, or less than 0.6 nm, and / or within any range between any two of the above values. In certain embodiments, the pore size is measured by microscopy (e.g., TEM, SEM, or AFM).

[0047] In certain embodiments, the non-carbon electroactive material includes one or more chalcogenides. In certain embodiments, the chalcogenides have at least one chalcogen anion (anion of oxygen, sulfur, selenium, tellurium, or polonium) and at least one electropositive element. In certain embodiments, the chalcogenides may be sulfide-based, selenide-based, or telluride-based. In certain embodiments, the chalcogenides include metal sulfides (e.g., sulfides of metals other than lithium or sodium). In certain embodiments, the one or more chalcogenides include a transition metal sulfide. In certain embodiments, the one or more chalcogenides include one or more of the following: TiS 2 , LiTiS 2 (LTS), VS 2 , MoS 2 , Mo 6 S 8 , and NbSe 3 In certain embodiments, the one or more chalcogenides include a transition metal oxide and / or a polyanion compound. In certain embodiments, the one or more chalcogenides include a metal monochalcogenide having the formula MX, where M is a transition metal and X is S, Se, or Te. In certain embodiments, the one or more chalcogenides include a metal monochalcogenide having the formula MX 2 where M is a transition metal (e.g., Ti, V, Co, Ni, Zr, Nb, Mo, Tc, Rh, Pd, Hf, Ta, W, Re, Ir, or Pt) and where X is S, Se, or Te. In certain embodiments, the one or more chalcogenides are materials having a layered crystal structure (e.g., LiTiS 2 , LiCoO 2 , LiNiO 2 , LiMnO 2 , LiNi 0.33 Mn 0.33 Co 0.33 O 2 , LiNi 0.8 Co 0.15 Al 0.05 O 2 , or Li 2 MnO 3), and / or materials having a spinel crystal structure (e.g., LiMn 2 O 4 or LiCo 2 O 4 ).

[0048] In certain embodiments, the non-carbon electroactive material comprises an intercalation material and / or a non-sulfur non-carbon electroactive material. For example, in certain embodiments, the non-carbon electroactive material may be LiFePO 4 , LiMnPO 4 , or LiCoPO 4 (e.g., those with an olivine crystal structure), and / or LiFeSO 4 F or LiVPO 4 F (e.g., those with the tavorite crystal structure).

[0049] In some embodiments, the lithium-sulfur battery of the present disclosure includes a lithium anode, a sulfur-based cathode, and an electrolyte that allows for ion transport between the anode and cathode. In certain embodiments described herein, the anode portion of the battery includes the anode and a portion of the electrolyte in contact with the anode. Similarly, in certain embodiments described herein, the cathode portion of the battery includes the cathode and a portion of the electrolyte in contact with the cathode. In certain embodiments, the battery includes a lithium-ion permeable separator that forms a boundary between the anode portion and the cathode portion. In certain embodiments, the battery includes a case that encapsulates both the anode portion and the cathode portion. In certain embodiments, the battery case includes a conductive anode end cover in electrical communication with the anode and a conductive cathode end cover in electrical communication with the cathode to facilitate charging and discharging via an external circuit.

[0050] positive electrode The compositions of the present disclosure are useful for the manufacture of electrochemical devices. The disclosed compositions can be porous or non-porous. Certain compositions disclosed herein can be deposited on a current collector to form a positive electrode of a secondary sulfur battery. The positive electrodes described herein are intended to be carbon-free (including relatively carbon-free, e.g., 5% or less by weight carbon, 4% or less by weight carbon, 3% or less by weight carbon, 2% or less by weight carbon, 1% or less by weight carbon, or 0.5% or less by weight carbon), while some embodiments contain some carbon. The provided positive electrode compositions can include one or more additives (e.g., conductive particles, binders, and other functional additives commonly found in battery positive electrode mixtures). For example, in certain embodiments, the provided positive electrode compositions can include 3D structured graphene (e.g., as described in U.S. Pat. No. 11,299,397 (LytEn, Inc.), the entire text of which is incorporated herein by reference). In certain embodiments, the compositions provided have sufficient electrical conductivity to provide a low resistance path for electrons to access the cathode so fabricated. In various embodiments, other additives are included in the compositions to modify or enhance the cathodes fabricated according to the principles described herein. Other cathode components include, for example, current collectors, connection tabs, and the like.

[0051] As discussed above, in certain embodiments, the positive electrode composition comprises a non-carbon electroactive material (e.g., an intercalation material) and a sulfur electroactive material (e.g., S 8 Sulfur in the form of a cyclic octaatomic molecule, lithium sulfide (e.g., Li 2 S 2 and / or Li 2 S) and / or sulfur in the form of an electroactive organosulfur compound or an electroactive sulfur-containing polymer. In certain embodiments, the electroactive material is an intercalation material structured to insert lithium ions. In certain embodiments, the electroactive material is S 8 →Li 2 Discharge voltage range of S (conversion of sulfur to lithium sulfide) (e.g., about 1.8 V to about 2.6 V vs. Li / Li +For example, about 2.0V to about 2.4V vs. Li / Li + ) and operates in a voltage range that overlaps with

[0052] In certain embodiments, the electroactive material includes one or more chalcogenides. In certain embodiments, the chalcogenides have at least one chalcogen anion (anion of oxygen, sulfur, selenium, tellurium, or polonium) and at least one electropositive element. In certain embodiments, the one or more chalcogenides may be sulfide-based, selenide-based, or telluride-based. In certain embodiments, the one or more chalcogenides include a metal sulfide. In certain embodiments, the one or more chalcogenides include one or more of the following: TiS 3 , LiTiS 2 (LTS), MoS 2 , Mo 6 S 8 , V.S. 2 , TaS 2 , and NbSe 3 In certain embodiments, the one or more chalcogenides include a transition metal oxide and / or a polyanion compound. In certain embodiments, the one or more chalcogenides include a metal monochalcogenide having the formula MX, where M is a transition metal and X is S, Se, or Te. In certain embodiments, the one or more chalcogenides include a metal monochalcogenide having the formula MX 2 where M is a transition metal (e.g., Ti, V, Co, Ni, Zr, Nb, Mo, V, Tc, Rh, Pd, Hf, Ta, W, Re, Ir, or Pt) and where X is S, Se, or Te. In certain embodiments, the one or more chalcogenides are lithiated materials having a layered crystal structure (e.g., TiS 2 , CoO 2 , NiO 2 , MnO 2 , Ni 0.33 Mn 0.33 Co 0.33 O 2 , Ni 0.8 Co 0.15 Al 0.05 O 2 , or MnO 3), materials with spinel crystal structure (e.g., Mn 2 O 4 Or Co 2 O 4 ), materials with olivine crystal structure (e.g., FePO 4 , MnPO 4 , or CoPO 4 ), and / or materials with a tavorite crystal structure (e.g., FeSO 4 F or VPO 4 F). In certain embodiments, the one or more chalcogenides include lithiated derivatives of materials having a layered crystal structure (e.g., LiTiS 2 , LiCoO 2 , LiNiO 2 , LiMnO 2 , LiNi 0.33 Mn 0.33 Co 0.33 O 2 , LiNi 0.8 Co 0.15 Al 0.05 O 2 , or Li 2 MnO 3 ), lithiated derivatives of materials with spinel crystal structure (e.g., LiMn 2 O 4 or LiCo 2 O 4 ), lithiated derivatives of materials with olivine crystal structure (e.g., LiFePO 4 , LiMnPO 4 , or LiCoPO 4 ), and / or lithiated derivatives of materials having the tavorite crystal structure (e.g., LiFeSO 4 F or LiVPO 4 F).

[0053] In certain embodiments, the one or more non-carbon, non-sulfur electroactive materials are characterized by having high electronic conductivity. For example, the electrical conductivity of the non-carbon, non-sulfur electroactive materials is about 10 -3 mS / cm 2 Super, about 0.01mS / cm 2 Super, about 0.05mS / cm 2 Super, 0.1mS / cm 2Ultra, 0.5mS / cm 2 Greater than or about 1 mS / cm 2 It's super.

[0054] In preferred embodiments, the positive electrode composition is carbon-free or has a low carbon content (e.g., 5.0 wt.% or less, 3.0 wt.% or less, 2.0 wt.% or less, 1.0 wt.% or less, 0.5 wt.% or less, or 0.1 wt.% or less). In certain embodiments, the positive electrode composition comprises a conductive material and a binder. In certain embodiments, the conductive material comprises a conductive material that facilitates the movement of electrons within the composite. For example, in certain embodiments, the conductive material is selected from the group consisting of carbon-based materials, graphite-based materials, conductive polymers, metals, semiconductors, metal oxides, metal sulfides, and combinations thereof, where non-carbon materials are preferred.

[0055] In certain embodiments, the positive electrode further comprises a coating layer, for example, in certain embodiments, the coating layer comprises a polymer, an organic material, an inorganic material, or a mixture thereof, which is not an integral part of the porous composite or the current collector.

[0056] In certain embodiments, the positive electrode comprises one or more of the following features (a)-(l): (a) a "stack" of multifunctional materials (e.g., the stack comprises particles with gradient structures that balance ion and electron transport for improved power capability, energy density, and lifetime, comprises bifunctional positive electrode additives that store Li and simultaneously conduct electrons, replacing expensive and bulky carbons, comprises binding molecules that spatially confine the energy-storing electrochemical reaction, thereby extending lifetime, comprises electrolyte components that improve the base efficiency of the electrolyte and improve energy density, and / or comprises electrolyte components that provide improved safety and energy density). (b) tight electrode layers; (c) tight tertiary structures; (d) porosity control; (e) core-shell structures; (f) crosslinked polymer shells; (g) self-doped polymer shells; (h) ionically conductive binders; (i) bilayer hybrid cathodes; (j) polysulfide-trapping polymers; (k) three-dimensional structures with high surface area (e.g., retaining (e.g., intercalating) both carbon and lithium); and (l) three-dimensional structures where carbon is substituted with metal disulfides (e.g., the battery contains a polymer electrolyte for sulfur).

[0057] negative electrode In certain embodiments, the secondary sulfur battery includes a lithium anode. Lithium anodes suitable for use in lithium-sulfur cells can be used. In certain embodiments, the anode of the secondary sulfur battery includes an anode active material selected from a material in which lithium intercalation occurs reversibly, a material that reacts with lithium ions to form a lithium-containing compound, metallic lithium, a lithium alloy, and combinations thereof. In certain embodiments, the anode includes metallic lithium. In certain embodiments, the lithium-containing anode composition includes a carbon-based compound. In certain embodiments, the carbon-based compound is selected from the group consisting of crystalline carbon, amorphous carbon, graphite, and mixtures thereof. In certain embodiments, the anode is carbon-free or has a low carbon content (e.g., 5.0 wt.% or less, 3.0 wt.% or less, 2.0 wt.% or less, 1.0 wt.% or less, or 0.5 wt.% or less). In certain embodiments, the material that reacts with lithium ions to form a lithium-containing compound is tin oxide (SnO 2 ), titanium nitrate, and silicon. In certain embodiments, the lithium alloy comprises an alloy of lithium with another alkali metal (e.g., sodium, potassium, rubidium, or cesium). In certain embodiments, the lithium alloy comprises an alloy of lithium with a transition metal. In certain embodiments, the lithium alloy comprises an alloy of lithium with a metal selected from the group consisting of Na, K, Rb, Cs, Fr, Be, Mg, Ca, Sr, Ba, Ra, Al, Sn, In, Zn, Sm, La, and combinations thereof. In certain embodiments, the lithium alloy comprises an alloy of lithium with indium. In certain embodiments, the lithium alloy comprises an alloy of lithium with aluminum. In certain embodiments, the lithium alloy comprises an alloy of lithium with zinc. In certain embodiments, the negative electrode comprises a lithium-silicon alloy. Examples of suitable lithium-silicon alloys include Li 15 S 4 , Li 12 S 7 , Li 7 S 3 , Li 13 S 4 , and Li 21 S 5 / Li22 S 5 In certain embodiments, the lithium metal or lithium alloy is present as a composite with another material. In certain embodiments, such a composite includes a material such as graphite, graphene, a metal sulfide or oxide, or a conductive polymer.

[0058] In some embodiments, the negative electrode is protected from redox shuttling reactions and dangerous runway reactions by any of the methods reported in the art (e.g., by chemical passivation or by deposition or polymerization to generate a protective layer on the surface of the negative electrode). For example, in certain embodiments, the negative electrode comprises an inorganic protective layer, an organic protective layer, or a mixture thereof, on the surface of the lithium metal. In certain embodiments, the inorganic protective layer comprises Mg, Al, B, Sn, Pb, Cd, Si, In, Ga, lithium silicate, lithium borate, lithium phosphate, lithium phosphorus nitride, lithium silicosulfide, lithium borosulfide, lithium aluminosulfide, lithium phosphorus sulfide, lithium fluoride, or a combination thereof. In certain embodiments, the organic protective layer comprises a conductive monomer, oligomer, or polymer. In certain embodiments, such polymers are selected from poly(p-phenylene), polyacetylene, poly(p-phenylenevinylene), polyaniline, polypyrrole, polythiophene, poly(2,5-ethylenevinylene), acetylene, poly(perinaphthalene), polyacene, and poly(naphthalene-2,6-di-yl), or combinations thereof.

[0059] Furthermore, in certain embodiments, during charging and discharging of the secondary sulfur battery, inert sulfur material generated from the electroactive sulfur material of the positive electrode is deposited on the negative electrode surface. As used herein, the term "inert sulfur" refers to sulfur that cannot participate in the electrochemical reaction of the positive electrode and therefore does not contribute capacity upon repeated charge / discharge cycles. In certain embodiments, the inert sulfur on the negative electrode surface acts as a protective layer on such negative electrode. In certain embodiments, the inert sulfur is present in the form of lithium sulfide.

[0060] It is further believed that the concepts of the present disclosure may be adapted for use in sodium-sulfur batteries, which include a sodium-based negative electrode and an intercalation or conversion material capable of inserting or reacting with sodium ions. Such systems are encompassed within the embodiments of the present disclosure.

[0061] It is further contemplated that the present disclosure may be adapted for use in batteries assembled in a configuration that does not include an anode. In certain embodiments, the battery or battery component manufactured has a configuration that does not include an anode and includes an anode current collector (e.g., copper) and one or more of the following (a)-(e): (a) a thin layer of garnet; (b) a structure (e.g., a composite 3D structure) having a coating deposited by atomic layer deposition (ALD) (e.g., the ALD coating may be LiPON, garnet, oxide, perovskite, sulfide, Li, 3 BO 3 -Li 2 CO 3 (b) a polymer (e.g., polyethylene oxide (PEO) or a block copolymer); (c) a solid electrolyte interface (SEI) layer (e.g., an artificial SEI layer formed in situ); (d) a lithium phosphorus oxynitride (LiPON); and (e) a solid electrolyte interface (SEI) layer (e.g., an artificial SEI layer formed in situ).

[0062] 1. Preparation of Electrodes There are various methods for producing electrodes for use in secondary sulfur batteries. One such process, commonly referred to as the "wet process," involves adding solid cathode material to a liquid to prepare a slurry composition. Such slurries are usually in the form of viscous liquids formulated to facilitate downstream coating operations. Thorough mixing of the slurry can be important for coating and drying operations that affect the performance and quality of the electrode. Suitable mixing equipment includes ball mills, magnetic stirrers, ultrasonication, planetary mixers, high speed mixers, homogenizers, universal type mixers, and static mixers. The liquid used to prepare the slurry can be any that can uniformly disperse the active material, binder, conductive material, and any additives, and can also be evaporated. Suitable slurry liquids include, for example, N-methylpyrrolidone, acetonitrile, methanol, ethanol, propanol, butanol, tetrahydrofuran, water, isopropyl alcohol, dimethylpyrrolidone, propylene carbonate, gamma butyrolactone, and the like.

[0063] In some embodiments, the prepared composition is coated onto a current collector and dried to form an electrode. Specifically, the electrode is formed by coating a conductor with the slurry and spreading the slurry evenly over the conductor, and then, in certain embodiments, the electrode is roll pressed (e.g., calendered) and / or heated as needed, as known in the art. Generally, the matrix of active material and conductive material is held together on the conductor by a binder. In certain embodiments, the matrix comprises a polymer binder, such as polyvinylidene fluoride (PVDF), poly(vinylidene fluoride-co-hexafluoropropene) (PVDF / HFP), polytetrafluoroethylene (PTFE), Kynar Flex® 2801, Kynar® Powerflex LBG, Kynar® HSV900, Teflon®, styrene butadiene rubber (SBR), polyethylene oxide (PEO), or polytetrafluoroethylene (PTFE). Alternatively or additionally, in certain embodiments, a lithium salt is dispersed in the matrix to improve lithium conductivity.

[0064] In certain embodiments, the current collector is selected from the group consisting of aluminum foil, copper foil, nickel foil, stainless steel foil, titanium foil, zirconium foil, molybdenum foil, nickel foam, copper foam, carbon paper or carbon fiber sheet, a polymer substrate coated with a conductive metal, and / or combinations thereof.

[0065] PCT Publication Nos. WO2015 / 003184, WO2014 / 074150, and WO2013 / 040067, the disclosures of which are incorporated herein by reference in their entireties, describe various methods of manufacturing electrodes and electrochemical cells.

[0066] Separator In certain embodiments, the secondary sulfur battery includes a separator. The separator divides the negative and positive electrodes and prevents direct electronic conduction between them. In certain embodiments, the separator has high lithium ion permeability. In certain embodiments, the separator is relatively impermeable to polysulfide ions dissolved in the electrolyte. In certain such embodiments, the separator as a whole inhibits or limits the passage of electrolyte-soluble sulfides between the negative and positive electrode portions of the battery. In certain embodiments, the separator of impermeable material is configured to allow lithium ion transport between the negative and positive electrodes of the battery during charging and discharging of the cell. In some such embodiments, the separator is porous. One or more electrolyte-permeable channels can be provided that bypass or penetrate the impermeable surface of the separator to allow sufficient lithium ion flow between the negative and positive electrode portions of the battery.

[0067] As will be apparent to those skilled in the art, the optimum dimensions of the separator require a balance between the competing concerns of maximizing impedance to polysulfide migration while allowing sufficient lithium ion flow. Apart from this consideration, the shape and orientation of the separator is not particularly limited and will depend in part on the battery configuration. For example, in some embodiments, the separator is substantially circular in a coin-type cell and substantially rectangular in a pouch-type cell. In some embodiments, the separator is substantially flat. However, curved or other non-planar shapes are not precluded from being used.

[0068] The separator can be of any suitable thickness. To maximize the energy density of the battery, it is generally preferred that the separator be as thin and lightweight as possible. However, the separator should be thick enough to provide sufficient mechanical robustness and ensure adequate electrical isolation of the electrodes. In certain embodiments, the separator has a thickness of about 1 μm to about 200 μm, preferably about 5 μm to about 100 μm, and more preferably about 10 μm to about 30 μm.

[0069] electrolyte In certain embodiments, the secondary sulfur battery includes an electrolyte that includes an electrolyte salt, such as, for example, lithium trifluoromethanesulfonimide, lithium triflate, lithium perchlorate, LiPF 6 , LiBF 4 , tetraalkylammonium salts (e.g., tetrabutylammonium tetrafluoroborate, TBABF 4 ), salts that are liquid at room temperature (for example, imidazolium salts such as 1-ethyl-3-methylimidazolium bis-(perfluoroethylsulfonyl)imide, EMIBeti, etc.).

[0070] In certain embodiments, the electrolyte comprises one or more alkali metal salts. In certain embodiments, such salts include lithium salts (e.g., LiCF 3 SO 3 , LiClO 4 , LiNO 3 , LiPF 6 , LiBr, LiTDI, LiFSI, and LiTFSI, or combinations thereof. In certain embodiments, the electrolyte comprises an ionic liquid (e.g., 1-ethyl-3-methylimidazolium-TFSI, N-butyl-N-methyl-piperidinium-TFSI, N-methyl-n-butylpyrrolidinium-TFSI, and N-methyl-N-propylpiperidinium-TFSI, or combinations thereof). In certain embodiments, the electrolyte comprises a superionic conductor (e.g., a sulfide, an oxide, and a phosphate (e.g., phosphorus pentasulfide), or combinations thereof).

[0071] In certain embodiments, the electrolyte is a liquid. For example, in certain embodiments, the electrolyte comprises an organic solvent. In certain embodiments, the electrolyte comprises only one organic solvent. In some embodiments, the electrolyte comprises a mixture of two or more organic solvents. In certain embodiments, the mixture of organic solvents comprises one or more of a weakly polar solvent, a strongly polar solvent, and a lithium-protecting solvent.

[0072] As used herein, the term "weakly polar solvent" is defined as a solvent capable of dissolving elemental sulfur and having a dielectric constant less than 15. Weakly polar solvents are selected from aryl compounds, bicyclic ethers, and acyclic carbonate compounds. Examples of weakly polar solvents include xylene, dimethoxyethane, 2-methyltetrahydrofuran, diethyl carbonate, dimethyl carbonate, toluene, dimethyl ether, diethyl ether, diglyme, tetraglyme, and the like. As used herein, the term "strongly polar solvent" is defined as a solvent capable of dissolving lithium polysulfide and having a dielectric constant greater than 15. Strongly polar solvents are selected from bicyclic carbonate compounds, sulfoxide compounds, lactone compounds, ketone compounds, ester compounds, sulfate compounds, and sulfite compounds. Examples of strong polar solvents include hexamethylphosphoric triamide, γ-butyrolactone, acetonitrile, ethylene carbonate, propylene carbonate, N-methylpyrrolidone, 3-methyl-2-oxazolidone, dimethylformamide, sulfolane, dimethylacetamide, dimethylsulfoxide, dimethyl sulfate, ethylene glycol diacetate, dimethyl sulfite, ethylene glycol sulfite, and the like. As used herein, the term "lithium protection solvent" is defined as a solvent that forms a good protection layer, i.e., a stable solid electrolyte interface (SEI) layer, on the lithium surface and exhibits at least 50% cycle efficiency. The lithium protection solvent is selected from saturated ether compounds, unsaturated ether compounds, and heterocyclic compounds containing one or more heteroatoms selected from the group consisting of N, O, and / or S. Examples of lithium protection solvents include tetrahydrofuran, 1,3-dioxolane, 3,5-dimethylisoxazole, 2,5-dimethylfuran, furan, 2-methylfuran, 1,4-oxane, 4-methyldioxolane, and the like.

[0073] In certain embodiments, the electrolyte is a liquid (e.g., an organic solvent). In some embodiments, the liquid is selected from the group consisting of an organic carbonate, an ether, a sulfone, water, an alcohol, a fluorocarbon, or any combination thereof. In certain embodiments, the electrolyte comprises an ether solvent.

[0074] In certain embodiments, the organic solvent comprises an ether. In certain embodiments, the organic solvent is selected from the group consisting of 1,3-dioxolane, dimethoxyethane, diglyme, triglyme, γ-butyrolactone, γ-valerolactone, and combinations thereof. In certain embodiments, the organic solvent comprises a mixture of 1,3-dioxolane and dimethoxyethane. In certain embodiments, the organic solvent comprises a 1:1 (v / v) mixture of 1,3-dioxolane and dimethoxyethane. In certain embodiments, the organic solvent is selected from the group consisting of diglyme, triglyme, γ-butyrolactone, γ-valerolactone, and combinations thereof. In certain embodiments, the electrolyte comprises sulfolane, sulfolene, dimethyl sulfone, methyl ethyl sulfone, or combinations thereof. In some embodiments, the electrolyte comprises ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate, methyl ethyl carbonate, or combinations thereof.

[0075] In certain embodiments, the electrolyte is solid. In certain embodiments, the solid electrolyte comprises a polymer. In certain embodiments, the solid electrolyte comprises a glass, a ceramic, an inorganic composite, or a combination thereof. In certain embodiments, the solid electrolyte comprises a polymer composite containing a glass, a ceramic, an inorganic composite, or a combination thereof. In certain embodiments, such solid electrolytes include one or more liquid components as plasticizers or to form a "gel electrolyte".

[0076] Secondary Sulfur Battery Described herein is a secondary sulfur battery comprising the above-mentioned positive electrode composition. For example, in certain embodiments, such a battery comprises a provided positive electrode composition and a lithium-containing negative electrode composition combined therewith by a lithium conductive electrolyte. In some embodiments, such a battery also comprises additional components (e.g., a separator between the negative and positive electrodes, a negative and positive current collectors, terminals that can connect the cell to an external load, and packaging such as a flexible pouch or a rigid metal container). As further contemplated, the present disclosure regarding secondary sulfur batteries can be adapted for use in sodium-sulfur batteries, and such batteries are also considered to be within the scope of certain embodiments of the present disclosure.

[0077] 1 illustrates a cross-section of an electrochemical cell 800 according to an exemplary embodiment of the present disclosure. The electrochemical cell 800 includes a negative electrode 802, a positive electrode 804, a separator 806 interposed between the negative electrode 802 and the positive electrode 804, a container 810, and a fluid electrolyte 812 in contact with the negative electrode 802 and the positive electrode 804. Such a cell optionally includes additional layers of electrodes and separators 802a, 802b, 804a, 804b, 806a, and 806b.

[0078] The negative electrode 802 (sometimes referred to herein as the anode) comprises an active negative electrode material capable of accepting cations. Non-limiting examples of active negative electrode materials for lithium-based electrochemical cells include Li metal, Li alloys (e.g., Li alloys such as Si, Sn, Bi, In, and / or Al alloys), Li 4 Ti 5 O 12 , hard carbon, graphitic carbon, metal chalcogenides, and / or amorphous carbon. According to some embodiments of the present disclosure, most (e.g., greater than 90% by weight) of the negative electrode active material may be initially contained in the discharged positive electrode 804 (sometimes referred to herein as the positive electrode) when the electrochemical cell 800 is first fabricated, and thus the electrode active material forms part of the first electrode 802 during the initial charging of the electrochemical cell 800.

[0079] Methods for depositing an electroactive material onto a portion of the negative electrode 802 are described in U.S. Patent Publication Nos. 2016 / 0172660 and 2016 / 0172661 (applicant Fischer et al.), the contents of each of which are incorporated herein by reference to the extent that the content thereof is not inconsistent with this disclosure.

[0080] The positive electrode 804 (also referred to herein as the positive electrode) comprises a positive electrode composition as described herein. In certain embodiments, the positive electrode composition comprises about 30 to about 70 weight percent electroactive sulfur. In certain embodiments, the positive electrode comprises at least about 70% of the total sulfur present in the electrochemical cell. In certain embodiments, the positive electrode comprises at least about 80% of the total sulfur present in the electrochemical cell. In certain embodiments, the positive electrode comprises at least about 90% of the total sulfur present in the electrochemical cell. In certain embodiments, the positive electrode comprises at least about 95% of the total sulfur present in the electrochemical cell. In certain embodiments, the positive electrode comprises at least about 99% of the total sulfur present in the electrochemical cell. In certain embodiments, the positive electrode comprises substantially all of the total sulfur present in the electrochemical cell.

[0081] The negative electrode 802 and the positive electrode 804 can further include one or more conductive additives, as described above. According to some embodiments of the present disclosure, the negative electrode 802 and / or the positive electrode 804 further include one or more polymer binders, as described above.

[0082] FIG. 2 shows an example of a battery according to various embodiments described herein. A cylindrical battery is shown here for illustrative purposes, but other types of configurations, such as prismatic or pouch (laminated type) batteries, can also be used. The exemplary Li battery 901 includes a negative electrode 902, a positive electrode 904, a separator 906 interposed between the negative electrode 902 and the positive electrode 904, an electrolyte (not shown) impregnated in the separator 906, a battery case 905, and a sealing member 908 that seals the battery case 905. Of course, the exemplary battery 901 may simultaneously embody multiple aspects of the present disclosure in various designs.

[0083] The secondary sulfur battery of the present disclosure includes a lithium anode, a porous sulfur-based cathode, and an electrolyte that allows for the transport of lithium ions between the anode and cathode. In certain embodiments described herein, the anode portion of the battery includes the anode and a portion of the electrolyte in contact with the anode. Similarly, in certain embodiments described herein, the cathode portion of the battery includes the cathode and a portion of the electrolyte in contact with the cathode. In certain embodiments, the battery includes a lithium-ion permeable separator that forms an interface between the anode portion and the cathode portion. In certain embodiments, the battery includes a case that encapsulates both the anode portion and the cathode portion. In certain embodiments, the battery case includes a conductive anode end cover in electrical communication with the anode and a conductive cathode end cover in electrical communication with the cathode to facilitate charging and discharging via an external circuit.

[0084] In certain embodiments, the secondary sulfur battery of the present disclosure is specified in terms of its ratio of electrolyte to electroactive sulfur. The volume of the electrolyte and the ratio of electrolyte to sulfur in the positive electrode (volume / weight) correlate with the energy density of the sulfur battery. The electrolyte may be distributed among different parts of the volume in the cell, for example, the electrolyte may be included in the pores of the positive electrode, in the separator, and in contact with the negative electrode or between the negative electrode solid electrolyte phases. The electrolyte may also be included in other spaces in the battery that are not in direct contact with the negative electrode active material or the positive electrode active material, for example, the electrolyte may be left in the annular volume at the edge of a coin cell. In certain embodiments, the present disclosure provides a battery in which the entire or majority of the electrolyte is included in the positive electrode. Preferably, substantially all of the electrolyte is included in the positive electrode, and only the minimum amount of electrolyte required to wet the separator and negative electrode surface or SEI is outside the positive electrode. The electrolyte included in the positive electrode is called the "contained electrolyte" and its volume V CE can be estimated as the theoretical pore volume or as the porosity multiplied by the geometric volume of the positive electrode film.

number

[0085] In certain embodiments, the provided secondary sulfur battery has a total electrolyte content (V tot ) is in the positive electrode (e.g., V CE / V tot In certain embodiments, the provided secondary sulfur battery is characterized by a total electrolyte content (V tot ) is in the positive electrode (e.g., V CE / V tot >0.8). In certain embodiments, the secondary sulfur battery has at least 60%, at least 65%, or at least 70% of the electrolyte contained in the positive electrode porous material. In certain embodiments, the secondary sulfur battery has at least 80%, at least 85%, or at least 90% of the electrolyte contained in the positive electrode porous material. In certain embodiments, the secondary sulfur battery has at least 92%, at least 94%, at least 95%, at least 96%, or at least 97% of the electrolyte contained in the positive electrode porous material.

[0086] The total electrolyte to sulfur ratio (E / S) is another parameter that affects the energy density of the battery. The E / S ratio is proportional to the total volume of electrolyte, V tot and the mass of electroactive sulfur (m sulfur ) is calculated based on

number

[0087] In certain embodiments, the secondary sulfur battery has an electrolyte to sulfur ratio of about 6 microliters or less per milligram of electroactive sulfur. In certain embodiments, the secondary sulfur battery has an electrolyte to sulfur ratio of about 5 microliters or less per milligram of electroactive sulfur. In certain embodiments, the secondary sulfur battery has an electrolyte to sulfur ratio of about 4.5 microliters or less per milligram of electroactive sulfur. In certain embodiments, the secondary sulfur battery has an electrolyte to sulfur ratio of about 3.5 microliters or less per milligram of electroactive sulfur, or an electrolyte to sulfur ratio of less than about 3.0 microliters per milligram of electroactive sulfur. In certain embodiments, the secondary sulfur battery has an electrolyte to sulfur ratio of about 3.5 microliters or less per milligram of electroactive sulfur. In certain embodiments, the secondary sulfur battery has an electrolyte to sulfur ratio of about 3 microliters or less per milligram of electroactive sulfur. In certain embodiments, the secondary sulfur battery has an electrolyte to sulfur ratio of about 1.8 to about 3.5 μL / mgS. In certain embodiments, the secondary sulfur battery has an electrolyte to sulfur ratio of about 1.8 to about 2.5 μL / mg S. In certain embodiments, the secondary sulfur battery has an electrolyte to sulfur ratio of about 1.0 to about 2.0 μL / mg S. In certain embodiments, the secondary sulfur battery has an electrolyte to sulfur ratio of about 1.5 to about 2.0 μL / mg S.

[0088] Equivalent The systems, devices, methods, and processes of the present disclosure are considered to encompass variations and modifications developed using information from the embodiments described herein. Those skilled in the art may make modifications and / or variations to the systems, devices, methods, and processes described herein.

[0089] Specific embodiments of the present disclosure have been described above. However, it should be specifically noted that the present disclosure is not limited to these embodiments, but rather additions and modifications to those explicitly described in the present disclosure are also intended to be included within the scope of the present disclosure. Furthermore, it should be understood that the features of the various embodiments described in the present disclosure are not mutually exclusive and may exist in various combinations and permutations, which may be possible without departing from the spirit and scope of the present disclosure even if such combinations or permutations are not expressed. Although the present disclosure has been described in detail with particular reference to specific embodiments thereof, it will be understood that variations and modifications may occur within the spirit and scope of the invention as claimed.

Claims

1. A cathode material for a carbon-free sulfur cathode, At least one electroactive sulfur conversion cathode material, It includes a non-sulfur, non-carbon electroactive material, The positive electrode material (for example, the carbon-free positive electrode) has a carbon content of 5% by weight or less (for example, 2% by weight or less, 1% by weight or less, 0.5% by weight or less, or 0.1% by weight or less).

2. The aforementioned non-sulfur, non-carbon electroactive material has a sulfur conversion voltage range (for example, about 1.8V to about 2.6V vs. Li / Li ＋ For example, approximately 2.0V to approximately 2.4V vs. Li / Li ＋ The positive electrode material according to claim 1, which is an intercalation material having a structure that allows for the reversible insertion of lithium ions within a voltage range that overlaps with ).

3. The aforementioned non-sulfur, non-carbon electroactive material is a conversion material (for example, a sulfur conversion voltage range (for example, about 1.8V to about 2.6V vs. Li / Li) ＋ For example, approximately 2.0V to approximately 2.4V vs. Li / Li ＋ The positive electrode material according to claim 1, which is a chalcogenide that undergoes an electrochemical conversion reaction within a voltage range that overlaps with ).

4. The positive electrode material according to claim 1, wherein the non-sulfur, non-carbon electroactive material is a chalcogenide (e.g., a metal chalcogenide, e.g., a metal sulfide).

5. The positive electrode material according to claim 1, wherein the non-sulfur, non-carbon electroactive material is also an electron conductor.

6. The non-sulfur, non-carbon electroactive material has a discharge capacity, as described in claim 1.

7. A cathode material according to claim 1, comprising a core-shell structure.

8. Each includes a core having a surrounding shell, the core being the electroactive sulfur conversion material (e.g., Li ２ S ２ and / or Li ２ The cathode material according to claim 7, comprising S), wherein the shell comprises the non-sulfur non-carbon electroactive material (e.g., one or more metal chalcogenides).

9. The positive electrode material according to claim 7, wherein the core-shell structure has an average core diameter in the range of 50 to 300 nm and an average shell thickness in the range of 1 to 20 nm (for example, a thickness of 10 nm or less).

10. The positive electrode material according to claim 7, wherein the core-shell structure has at least 10% by mass of a non-sulfur, non-carbon electroactive material (e.g., a metal chalcogenide) relative to sulfur (for example, 10 to 90% by mass of a non-sulfur, non-carbon electroactive material, for example, 30 to 70% by mass of a non-sulfur, non-carbon electroactive material).

11. The at least one electroactive sulfur conversion cathode material is S ８ sulfur in the form of a cyclic octatomic molecule, lithium sulfide (e.g., Li ２ S ２ and / or Li ２ S), an electroactive organic sulfur compound, and an electroactive sulfur-containing polymer, the cathode material according to claim 1, comprising one or more selected from the group consisting of.

12. A positive electrode comprising the positive electrode material described in any one of claims 1 to 11, wherein the proportion of carbon in the positive electrode is 5% by weight or less (for example, 2% by weight or less, 1% by weight or less, 0.5% by weight or less, or 0.1% by weight or less).

13. The positive electrode according to claim 12, wherein the positive electrode material is disposed in a film (for example, a film containing a binder).

14. A battery (e.g., a rechargeable battery) comprising (i) the positive electrode described in claim 12, and (ii) an electrolyte in contact with the positive electrode.

15. The battery according to claim 14, further comprising a negative electrode.

16. The battery according to claim 15, wherein the negative electrode is a protected lithium metal negative electrode.

17. The battery according to claim 14, further comprising a protected current collector.

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