Metal chalcogenide-selenium-sulfur electrode for lithium sulfur batteries

Abstract

Cathode active material layers and methods are disclosed. The cathode active material layer includes a metal chalcogen, an electroactive sulfur conversion cathode material, and an electroactive selenium conversion cathode material. The cathode active material layer includes the metal chalcogen in a weight ratio (w / w) of between 5% and 75%, the electroactive sulfur conversion cathode material in a weight ratio (w / w) of between 15% and 75%, and the electroactive selenium conversion cathode material in a weight ratio (w / w) of between 2% and 25%.

Description

METAL CHALCOGENIDE-SELENIUM-SULFUR ELECTRODE FOR LITHIUM SULFUR BATTERIESCROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application is related to, claims priority to, and incorporates herein by reference for all purposes U.S. Provisional Patent Application No. 63 / 649,799, filed May 20, 2024.BACKGROUND

[0002] There is significant work being conducted to develop lithium batteries with high energy density, long cycle life, and low cost, particularly batteries for electric vehicles and consumer electronics.

[0003] Sulfur is a low-cost, high specific energy material that is available domestically as a byproduct of the oil and gas industry. Sulfur's use in lithium secondary battery cathodes has been under development for some time but has yet to achieve wide commercial adoption. The use of sulfur in the cathode can eliminate the need for cobalt and nickel required for manufacture of current lithium batteries. Cobalt is expensive, toxic, and it is mined in parts of the world known to have loose or unenforced regulations and unethical labor and trade practices. Nickel-rich cathodes have high energy density and can reduce cobalt consumption, but there are also serious long-term nickel supply concerns, for example, recently motivating Tesla’s shift away from nickel-containing battery cells.

[0004] Producing sulfur cathodes capable of commercial performance levels has been a challenge, for example, because sulfur by-products formed during cycling of lithium sulfur batteries reduce performance and limit cycle-life, and because low density’ single function materials such as conductive carbon additives negatively impact the energy density’ of formulated sulfur cathodes.

[0005] While not wanting to be bound by any particular theory, it is reported that the cycle life of lithium sulfur batteries is limited by several issues including the “shuttle effect”, electrolyte consumption, and solid-electrolyte interphase growth / ripening.

[0006] There have been a focused research efforts on mitigating these issues, which include the use of electrolyte formulations and additives, cathode additives, unique cathode micro- and nanostructuring, etc. However, it is preferred to use methods that are environmentally benign and easily implemented with current battery making equipment and procedures. Thus, electrolyte formulations that can be introduced through standard processes, or cathode formulations that avoid the use of toxic solvents and are compatible with standard fabrication processes are preferred routes to introducing additives that mitigate performance issues.

[0007] There have been many approaches published where the composition of the lithium-sulfur battery cathode has been tweaked and longer cycle life has been achieved. Most involve coating orotherwise physically protecting the elemental sulfur active material. Some approaches involve chemically binding the sulfur, usually on the surface of a solid inorganic additive or a high surface area carbon-based material that has been functionalized with additional elements or functional groups. There are approaches published where a layer is added between the cathode and the separator that either physically or chemically blocks the polysulfides from shuttling to the anode. None have led to successful development of a commercially viable lithium-sulfur battery.

[0008] A need exists for new cathode compositions, which are capable of operating under the conditions required of unmanned aerial vehicles (drones) and modem automotive batteries, among other intended uses, while overcoming one or more of the aforementioned shortcomings.SUMMARY

[0009] The present disclosure provides, among other things, cathode materials and batteries that include the same.

[0010] In an aspect, the present disclosure provides a battery cathode. The battery cathode includes a cathode film adhered to a current collector. The cathode film includes a mixture of titanium disulfide and a conversion active material. The conversion active material comprises a mixture of electroactive selenium and electroactive sulfur. The titanium disulfide is present in the cathode at between 5 and 30 mass percent relative to the conversion active material. The electroactive selenium in the conversion active material is present at between 5 and 15 mass percent relative to the electroactive sulfur.

[0011] In another aspect, the present disclosure provides a battery cathode. The battery cathode includes a cathode film adhered to a current collector. The cathode film includes a mixture of titanium disulfide and a conversion active material. The conversion active material comprises a mixture of electroactive selenium and electroactive sulfur. The titanium disulfide is present in the cathode at between 25 and 55 mass percent relative to the conversion active material. The electroactive selenium in the conversion active material is present at between 5 and 15 mass percent relative to the electroactive sulfur.

[0012] In an aspect, the present disclosure provides a cathode active material layer. The cathode active material layer includes a metal chalcogen, an electroactive sulfur conversion cathode material, and an electroactive selenium conversion cathode material. The cathode active material layer includes the metal chalcogen in a weight ratio (w / w) of between 5% and 75%, the electroactive sulfur conversion cathode material in a weight ratio (w / w) of between 15% and 75%, and the electroactive selenium conversion cathode material in a weight ratio (w / w) of between 2% and 25%.

[0013] In another aspect, the present disclosure provides a method of making a cathode active material layer. At step a), the method includes mixing and optionally milling a metal chalcogen powder, an electroactive sulfur conversion cathode material powder, and an electroactive selenium conversion cathode material powder to form a powder mixture. At step b), the method includes casting a slurry to form a slurry layer. The slurry includes the powder mixture and a solvent. At step c), the method includes drying the slurry layer to form the cathode active material layer. The metal chalcogen powder is composed of a metal chalcogen selected from the group consisting of TiS2. M0S2, MoeSs, VS2, TiSe2, TiTe2, VSe2, MoSe2, MoTe2, WS2, WTe2, WSe2, and combinations thereof. The electroactive sulfur conversion cathode material powder is composed of an electroactive sulfur conversion cathode material. The electroactive selenium conversion cathode material powder is composed of an electroactive selenium conversion cathode material. The cathode active material layer includes the metal chalcogen in a weight ratio (w / w) of between 5% and 75%, the electroactive sulfur conversion cathode material in a weight ratio (w / w) of between 15% and 75%, and the electroactive selenium conversion cathode material in a weight ratio (w / w) of between 2% and 25%.

[0014] In a further aspect, the present disclosure provides a cathode. The cathode includes a cathode active material layer as described herein disposed atop a current collector.

[0015] In yet another aspect, the present disclosure provides a battery. The battery includes a cathode including the cathode active material layer as described herein, an anode, and an electrolyte in contact with the cathode and the anode.

[0016] Any two or more of the features described in this specification, including in this summary section, may be combined to form implementations of the disclosure, whether or not specifically expressly described as a separate combination in this specification.BRIEF DESCRIPTION OF THE DRAWING

[0017] The present teachings described herein will be more fully understood from the following description of various illustrative embodiments, when read together with the accompanying drawings. It should be understood that the drawings described below are for illustration purposes only and are not intended to limit the scope of the present teachings in any way. The foregoing and other objects, aspects, features, and advantages of the disclosure will become more apparent and may be better understood by referring to the following description taken in conjunction with the accompanying drawings, in which:

[0018] FIG. 1 illustrates a cross section of an electrochemical cell 800 in accordance with exemplary embodiments of the disclosure.

[0019] FIG. 2 illustrates an example of a battery' according to various embodiments described herein.

[0020] FIG. 3 is a plot of capacity versus cycle number for a variety of test cells, as described in Example lb, in accordance with aspects of the present disclosure.

[0021] FIG. 4 is a plot of capacity versus cycle number for a variety of test cells, as described in Example 1c, in accordance with aspects of the present disclosure.

[0022] FIG. 5 is a plot showing lifetime to failure of the test cells descnbed in Example Id, in accordance with aspects of the present disclosure.

[0023] FIG. 6 is a plot of average battery life for the test cells described in Example le, in accordance with aspects of the present disclosure.

[0024] FIG. 7 is a plot of average pulse efficiency versus fraction discharge for the test cells described in Example le, in accordance with aspects of the present disclosure.

[0025] FIG. 8 is a plot of average battery life for various sulfur-to-selenium ratios within test cells described in Example 1 e, in accordance with aspects of the present disclosure.DEFINITIONS

[0026] About / Approximately: The term “about” or “approximately”, when used herein in reference to a value, refers to a value that is similar, in context, to the referenced value. In general, those skilled in the art, familiar with the context, will appreciate the relevant degree of variance encompassed by “about” or “approximately” in that context. For example, in some embodiments, e.g., as set forth herein, the term “about” can encompass a range of values that w ithin 25%, 20%, 19%, 18%, 17%, 16%, 15%, 14%, 13%, 12%, 11%, 10%, 9%, 8%, 7%, 6%, 5%, 4%, 3%, 2%, 1%, or within a fraction of a percent, of the referred value.

[0027] Carbon: As used herein in connection with cathode materials, refers to elemental carbon or materials that are substantially composed of elemental carbon, examples 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, solvents and the like are not encompassed by this term unless otherwise indicated.Similarly, in the context of terms such as Carbon Free ” and “Non-Carbon Materials” it is these elemental forms of carbon that are to be understood to be excluded.

[0028] Intercalation Material: As used herein, the term “intercalation material” refers to a substance into which another substance or species (e.g. ion. metal ion) is reversibly inserted or included in vacancies, interstitial sites, voids, or between layers of the intercalation material, or some combination thereof.

[0029] Electroactive Material: As used herein, the term “electroactive material” refers to a composition of matter with one or more components capable of changing its oxidation state in a charge-transfer step of an electrochemical reaction.

[0030] Lithium alloy: As used herein, the term lithium alloy refers to substances formed by combinations of lithium and other metals or semimetal elements: non-limiting examples include lithium silicon compounds, and alloys of lithium with metals such as sodium, cesium, indium, aluminum, zinc and silver.

[0031] Nanoparticle, Nanostructure, Nanomaterial. As used herein, these terms may be used interchangeably to denote a particle of nanoscale dimensions or a material having nanoscale structures. The nanoparticles can have essentially any shape or configuration, such as a tube, a wire, a laminate, sheets, lattices, a box, a core and shell, or combinations thereof.

[0032] Operable. As used herein, a battery or battery component is “operable” when a test cell is capable of operation at a minimum threshold of operability.

[0033] Pulse Average Efficiency. As used herein, a “pulse average efficiency” refers to an arithmetic mean of the pulse efficiency across the entire state of charge, where the pulse efficiency is the ratio of the voltage during a 1000 mA / gS pulse to the voltage immediately preceding / following the pulse during a 100 mA / gS discharge. For the specific experiments conducted herein, pulses were 5 seconds at 1000 mA / gS every 30 minutes during a 100 mA / gS discharge. For compositions including Se. the values described herein consider the mass of Se as mass of S for the purposes of computing the pulse average efficiency.

[0034] Substantially. As used herein, the term “substantially” refers to the qualitative condition of exhibiting total or near-total extent or degree of a characteristic or property of interest.DETAILED DESCRIPTION OF CERTAIN EMBODIMENTS

[0035] Elements of different implementations described herein may be combined to form other implementations not specifically set forth above. Certain elements may be left out of the devices described herein without adversely affecting their operation. Various separate elements may be combined into one or more individual elements to perform the functions described herein.

[0036] It is contemplated that articles, devices, compositions, systems, methods, and processes of the claimed invention encompass variations and adaptations developed using information from the embodiments described herein. Adaptation and / or modification of the articles, devices, compositions, systems, methods, and processes described herein may be performed, as contemplated by this description.

[0037] Throughout the description, where articles, devices, compositions, and systems are described as having, including, or comprising specific components, or where processes and methods are described as having, including, or comprising specific steps, it is contemplated that, additionally, there are articles, devices, compositions, and systems of the present invention that consist essentially of, or consist of, the recited components, and that there are processes and methods according to the present invention that consist essentially of, or consist of, the recited processing steps.

[0038] It should be understood that the order of steps or order for performing certain action is immaterial so long as the invention remains operable. Moreover, two or more steps or actions may be conducted simultaneously.

[0039] The mention herein of any publication is not an admission that the publication serves as prior art with respect to any of the claims presented herein. The Background section is presented for purposes of clarity and is not meant as a description of prior art with respect to any claim.

[0040] Headers are provided for the convenience of the reader - the presence and / or placement of a header is not intended to limit the scope of the subject matter described herein.

[0041] Broadly, the present disclosure provides a method of improving cathode active materials and their methods of making. The method of improving involves replacing between 5% and 50% (molar ratio) of an electroactive sulfur conversion cathode material with an electroactive selenium conversion cathode material in a method of making a cathode active material.

[0042] Presented herein is a cathode active material. The cathode active material includes a metal chalcogen, an electroactive sulfur conversion cathode material, and an electroactive selenium conversion cathode material. The metal chalcogen can be selected from the group consisting of TiS2, M0S2, MoeSs, VS2, TiSe2, TiTe2, VSe2, MoSe2, MoTe2, WS2, WTe2, WSe2, and combinations thereof The cathode active material includes the metal chalcogen in a weight ratio (w / w) of between 5% and 75%, the electroactive sulfur conversion cathode material in a weight ratio (w / w) of between 15% and 75%, and the electroactive selenium conversion cathode material in a weight ratio (w / w) of between 2% and 25%.

[0043] The electroactive sulfur conversion cathode material can be introduced in a variety' of forms, so long as the electroactive sulfur conversion cathode material can be electrochemically converted to support battery operation. In some cases, the electroactive sulfur conversion cathode material is present or introduced as Ss. In some cases, the electroactive sulfur conversion cathode material is present or introduced as SeS2. In some cases, the electroactive sulfur conversion cathode material is present or introduced as lithium sulfide.

[0044] The electroactive selenium conversion cathode material can be introduced in a variety of forms, so long as the electroactive selenium conversion cathode material can be electrochemicallyconverted to support battery operation. In some cases, the electroactive selenium conversion cathode material is present or is introduced as SeS2.

[0045] In some cases, a material may be introduced that is partly an electroactive sulfur conversion cathode material and / or partly an electroactive selenium conversion cathode material. In these instances, a skilled artisan will recognize that an elemental analysis can divide the mass of the material into respective components, such that a given percentage of mass can be attributed to the electroactive sulfur conversion cathode material and / or the electroactive selenium conversion cathode material. To use SeS2 as an example, the formula represents a stoichiometric relationship of 2 parts S to 1 part Se. Based on the atomic masses of sulfur (32.065 g / mol) and selenium (78.96 g / mol). a given mass unit of SeS2 will be considered to be (78.96 / 143.09) of a mass unit of electroactive selenium conversion cathode material and (64. 13 / 143.09) of a mass unit of electroactive sulfur conversion cathode material.

[0046] The cathode active material can include the metal chalcogen in a weight ratio (w / w) of at least 5%, at least 10%, at least 15%, at least 20%, at least 25%, at least 30%, at least 35%, at least 40%. at least 45%, or at least 50%. The cathode active material can include the metal chalcogen in a weight ratio (w / w) of at most 75%, at most 70%, at most 65%, at most 60%, at most 55%. at most 50%, at most 45%, at most 40%, at most 35%, at most 30%, or at most 25%.

[0047] The cathode active material can include the electroactive sulfur conversion cathode material in a weight ratio (w / w) of at least 15%, at least 20%, at least 25%, at least 30%, at least 35%, at least 40%. at least 45%. or at least 50%. The cathode active material can include the electroactive sulfur conversion cathode material in a weight ratio (w / w) of at most 75%, at most 70%, at most 65%, at most 60%, at most 55%, at most 50%, at most 45%, at most 40%, at most 35%, at most 30%, or at most 25%.

[0048] The cathode active material can include the electroactive selenium conversion cathode material in a weight ratio (w / w) of at least 2%, at least 3%, at least 4%, at least 5%, at least 7%, at least 10%, or at least 15%. The cathode active material can include the electroactive selenium conversion cathode material in a w eight ratio (w / w) of at most 25%, at most 22%, at most 20%, at most 17%, at most 15%, at most 12%, at most 10%. at most 8%, or at most 5%.

[0049] The cathode active material can also include a conductive binder. The conductive binder can be either: i) a conductive matrix; or ii) a non-conductive matrix having conductive particles distributed throughout. The cathode active material can include the conductive binder in a weight ratio (w / w) or betw een 5% and 25%. In some cases, the cathode active material includes the conductive binder in a weight ratio (w / w) or at least 5%, at least 10%, or at least 15%. In some cases,the cathode active material includes the conductive binder in a weight ratio (w / w) of at most 25%, at most 20%, or at most 15%.

[0050] In some cases, the conductive binder includes the conductive particles distributed in the non- conductive matrix. In these cases, the cathode active material layer can include the conductive particles in a weight ratio (w / w) or between 2% and 22% and the non-conductive matrix in a weight ratio (w / w) or between 3% and 23%. In some cases, the cathode active material includes the conductive particles in a weight ratio (w / w) of at least 2%, at least 5%. at least 7%. at least 10%. or at least 15%. In some cases, the cathode active material includes the conductive particles in a weight ratio (w / w) or at most 22%, at most 20%, at most 17%, at most 15%, or at most 10%. In some cases, the cathode active material includes the non-conductive matrix in a weight ratio (w / w) of at least 3%, at least 5%, at least 8%, at least 10%, or at least 15%. In some cases, the cathode active material includes the non-conductive matrix in a weight ratio (w / w) of at most 23%, at most 20%, at most 18%, at most 15%, or at most 10%.

[0051] The conductive particles can be carbon black, among other conductive particles. The non- conductive matrix can be a polymeric binder. The polymeric binder can be selected from the group consisting of a poly(acrylic acid), poly(vinyhdene fluoride) (PVDF). a cellulose derivative (e.g.. carboxymethyl cellulose), styrene-butadiene rubber (SBR), and combinations thereof. In some cases, the polymeric binder is a salt of poly(acrylic acid), such as sodium poly(acrylic acid).

[0052] In certain embodiments, an electrically conductive material is selected from the group consisting of conductive carbon powders, such as carbon black. Super P®, C-NERGY™ Super C65. Ensaco® black, Ketjenblack®, acetylene black, synthetic graphite such as Timrex® SFG-6, Timrex® SFG-15, Timrex® SFG-44, Timrex® KS-6, Timrex® KS-15, Timrex® KS-44, natural flake graphite, carbon nanotubes, fullerenes, hard carbon, mesocarbon microbeads, and the like. In certain embodiments, a conductive material comprises one or more conductive polymers. For example, in certain embodiments, a conductive polymer is selected from the group consisting of polyaniline, polythiophene, polyacetylene, polypyrrole, and the like. In some embodiments, a conductive polymer is a cationic polymer. In some embodiments, a cationic polymer is a quaternary' ammonium polymer. In certain embodiments, a cationic polymer is selected from the group consisting of a polydiallyldimethylammonium salt, a poly[(3-chloro-2- hydroxypropyl)methaciy loxy ethyldimethyl -ammonium salt, a poly(butyl acrylate- methacryloxyethyhrimethylammonium) salt, poly(l-methyl-4-vinylpyridinium) salt, a poly(l- methyl-2-vinylpyridinium) salt, and a poly(methyacryloxyethyltriethylammonium) salt. In certain embodiments, a cationic polymer is selected from polydiallyldimethylammonium chloride (polyDADMAC), polybrene, epichlorohydrin-dimethylamine (epi-DMA), poly[(3-chloro-2-hydroxypropyl)methacryloxyethyldimethyl-ammonium chloride), poly(acrylamide- methacryloxyethyltrimethylammonium bromide), polyfbutyl acrylatemethacryloxy ethyltrimethylammonium bromide), poly(l-methyl-4-vinylpyridinium bromide), poly(l-methyl-2-vinylpyridinium bromide), and poly(methyacryloxyethyltriethylammonium bromide). In certain embodiments, a conductive material comprises one or more metal oxides or chalcogenides (e g. metal sulfides, selenides or tellurides). For example, in certain embodiments, a conductive material comprises one or more oxides, sulfides, selenides or tellurides of a first-row transition metal such as titanium, vanadium, chromium, manganese, iron, cobalt, copper, zinc, or combinations thereof. For example, in certain embodiments, a conductive material comprises one or more oxides, sulfides, selenides or tellurides of a second-row transition metal such as zirconium, indium, tin, antimony, or combinations thereof. In certain embodiments, a single metal oxide or chalcogenide is included. In other embodiments, a provided conductive material is composed of a mixture of two or more metal oxides or chalcogenides or comprises a mixed metal oxides or chalcogenides.

[0053] In certain embodiments, a binder is included in the provided cathode compositions. Binders are generally polymeric materials that help adhere individual particles composing a cathode mixture into a stable composite. Typical binders include polyvinylidene fluoride, polyvinylidene fluoride-co- hexafluoropropene) (PVDF / HFP), polytetrafluoroethylene (PTFE), Kynar Flex® 2801, Kynar® Powerflex LBG, Kynar® HSV 900, Teflon®, carboxymethylcellulose, styrene-butadiene rubber (SBR). polyethylene oxide, polypropylene oxide, polyethylene, polypropylene, polyacrylates, polyvinyl pyrrolidone, poly(methyl methacrylate), polyethyl acrylate, polytetrafluoroethylene, polyvinyl chloride, polyacry lonitrile, polycaprolactam, polyethylene terephthalate, polybutadiene, polyisoprene or poly acrylic acid, or derivatives, mixtures, or copolymers of any of these. In some embodiments, a binder is water soluble binder, such as sodium alginate or carboxymethyl cellulose. Generally, binders hold the active materials together and in contact with a current collector (e.g., aluminum foil or copper foil). In certain embodiments, a binder is selected from the group consisting of poly(vinyl acetate), polyvinyl alcohol, polyethylene oxide, polyvinyl pyrrolidone, alky lated polyethylene oxide, crosslinked polyethylene oxide, polyvinyl ether, poly(methyl methacrylate), polyvinylidene fluoride, a copolymer of polyhexafluoropropylene and poly vinylidene fluoride, polyethyl acrylate, polytetrafluoroethylene, polyvinyl chloride, polyacrylonitrile, polyvinyl pyridine, polystyrene, and derivatives, mixtures, and copolymers thereof.

[0054] In certain embodiments, the cathode active material comprises an intercalation material capable of reversibly intercalating lithium ions in operation within a voltage range roughly corresponding to the voltage of sulfur-to-lithium-sulfide conversion (e.g., from about 1.8V to about2.6V vs. Li / Li+, e.g., from about 2.0V to about 2.4V vs. Li / Li+). Intercalation is the process by which a mobile ion or molecule is reversibly incorporated into vacant sites in a crystal lattice of a host network. Intercalation processes are generally characterized by minimal volume change and mechanical strain during repeated insertion and extraction of ions during charge and discharge. An intercalation cathode material comprises a solid host network which can reversibly store guest ions that are inserted into and removed from the host network.

[0055] In certain embodiments, the cathode active material comprises one or more chalcogenides. In certain embodiments, a chalcogenide has at least one chalcogen anion (oxygen, sulfur, selenium, tellurium, or polonium anion) and at least one electropositive element. In certain embodiments, the chalcogenide may be sulfide-, selenide-, or telluride-based. In certain embodiments, the chalcogenide comprises a metal sulfide (for example a sulfide of a metal other than lithium or sodium). In certain embodiments, the one or more chalcogenides comprises a transition metal sulfide. In certain embodiments, the one or more chalcogenides comprises one or more of the following: TiS2, LiTiS2 (LTS), VS2, M0S2, MosSs, and NbSes. In certain embodiments, the one or more chalcogenides comprises a transition metal oxide and / or a polyanion compound. In certain embodiments, the one or more chalcogenides comprises 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 comprises at least one transition metal dichalcogenide (TMD) of the formula MX2. 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 comprises a material with a layered crystal structure (e.g., LiTiS2, LiCoCh, LiNiCh, LiMnCh, LiNio.33Mno.33Coo.33O2, LiNi0.sCo0.15Al0.05O2, or Li2MnOs), and / or a material with a spinel crystal structure (e.g., LiMn2O4 or LiCo2O4).

[0056] In various aspects of the present disclosure, the cathode active material is described as a cathode active material layer. The concept of a layer is intended to be interpreted broadly here, though narrower understandings of the term are fully encompassed. In some cases, the cathode active material layer as described herein can have a thickness of between 50 pm and 500 pm. In some cases, the cathode active material layer can have a thickness of at least 50 pm, at least 100 pm, or at least 250 pm. In some cases, the cathode active material layer can have a thickness of at most 500 pm, at most 300 pm, or at most 200 pm.

[0057] The cathode active material is operable at a low ratio of electrolyte to (sulfur plus selenium). In some cases, the cathode active material is operable at a ratio of electrolyte to (sulfur plus selenium) (in pL / mg) of 6 or lower, 5.5 or lower, 5 or lower, 4.8 or lower, 4.6 or lower, 4.5 or lower,4.4 or lower, 4.2 or lower, 4 or lower, 3.9 or lower, 3.8 or lower, 3.7 or lower, 3.6 or lower, or 3.5 or lower.

[0058] The cathode active material is operable at a high loading of sulfur and selenium. In some cases, the cathode active material layer is operable at an electroactive sulfur conversion cathode material plus electroactive selenium conversion cathode material loading of 3 mg / cm2or greater, 3.3 mg / cm2or greater, 3.5 mg / cm2or greater, 3.7 mg / cm2or greater, 4.0 mg / cm2or greater, 4.2 mg / cm2or greater, 4.5 mg / cm2or greater, 4.7 mg / cm2or greater, 4.9 mg / cm2or greater, or 5.0 mg / cm2or greater.

[0059] In some embodiments, a lithium-sulfur battery of the present disclosure comprises a lithium anode, a sulfur-selenium-based cathode, and an electrolyte permitting ion transport between anode and cathode. In certain embodiments, described herein, an anodic portion of a battery comprises an anode and a portion of electrolyte with which it is in contact. Similarly, in certain embodiments, described herein, a cathodic portion of a battery comprises a cathode and a portion of electrolyte with which it is in contact. In certain embodiments, a battery comprises a lithium ion-permeable separator, which defines a boundary between an anodic portion and a cathodic portion. In certain embodiments, a battery comprises a case, which encloses both anodic and cathodic portions. In certain embodiments, a battery case comprises an electrically conductive anodic-end cover in electrical communication with an anode, and an electrically conductive cathodic-end cover in electrical communication with a cathode to facilitate charging and discharging via an external circuit.Cathode

[0060] In certain embodiments, an electrochemical cell includes a cathode. A cathode generally includes a cathode active material as described herein. Certain compositions disclosed herein can be adhered to a current collector to form cathodes for electrochemical cells, such as batteries.

[0061] In certain aspects, the battery’ cathode disclosed herein can include a cathode film adhered to a current collector. The cathode film can include a mixture of titanium disulfide and a conversion active material. The conversion active material can include a mixture of electroactive selenium and electroactive sulfur. The titanium disulfide can be present in the cathode at between 5 and 30 mass percent relative to the conversion active material. The electroactive selenium in the conversion active material can be present at between 5 and 15 mass percent relative to the electroactive sulfur. In some cases, the titanium disulfide can be present at between 5 and 20 mass percent, including but not limited to, between 5 and 15 mass percent, between 6 and 12 mass percent, between 5 and 10 mass percent, between 7.5 and 16 mass percent, between 12 and 18 mass percent, or between 8 and 13 mass percent relative to the conversion active material. Without wishing to be bound by anyparticular theory, it is believed that cathodes with a cathode film having the composition described in this paragraph may be particularly suitable for UxS applications.

[0062] In certain aspects, the battery cathode disclosed herein can include a cathode film adhered to a current collector. The cathode film can include a mixture of titanium disulfide and a conversion active material. The conversion active material can include a mixture of electroactive selenium and electroactive sulfur. The titanium disulfide can be present in the cathode at between 25 and 55 mass percent relative to the conversion active material. The electroactive selenium in the conversion active material can be present at between 5 and 15 mass percent relative to the electroactive sulfur. In some cases, the titanium disulfide can be present at between 30 and 55 mass percent, including but not limited to, between 35 and 50 mass percent, between 40 and 55 mass percent, between 25 and 40 mass percent, between 30 and 50 mass percent, or between 30 and 45 mass percent relative to the conversion active material.

[0063] A sum of the titanium disulfide and the conversion active material can comprise at least 70% of the mass of the cathode film. In some cases, the sum of the titanium disulfide and the conversion active material can comprise at least 75%. at least 80%. at least 85%, or at least 90% of the mass of the cathode film.

[0064] A ratio of electrolyte volume in the battery to the mass of conversion active material in the cathode can be less than 3.5 pL / mg, less than 3.3 pL / mg, less than 3.2 pL / mg, less than 3.0 mL / mg, or less than 2.8 mL / mg, or less than 2.7 mL / mg, or less than 2.6 mL / mg, or less than 2.5 mL / mg, or less than 2.4 mL / mg, or less than 2.2 mL / mg, or less than 2. 1 mL / mg, or less than 2.0 mL / mg.

[0065] The cathode film can have an areal loading of at least 3 mg / cm2, or at least 3.5 mg / cm2, at least 4 mg / cm2, or at least 4.5 mg / cm2, or at least 5 mg / cm2, or at least 5.5 mg / cm2, or at least 6 mg / cm2, or at least 6.5 mg / cm2, or at least 7 mg / cm2, or at least 7.5 mg / cm2, or at least 8 mg / cm2.

[0066] Compositions of the present disclosure have utility in manufacture of electrochemical devices. The compositions disclosed may be porous or non-porous. Cathodes can be carbon-free (including relatively carbon free, e.g., no greater than 5wt.% carbon, no greater than 4 wt.% carbon, no greater than 3 wt.% carbon, no greater than 2 wt.% carbon, no greater than 1 wt.% carbon, or no greater than 0.5 wt.% carbon, for example) or can include some carbon. Provided cathode compositions may compnse one or more additives such as electrically conductive particles, binders, and other functional additives typically found in battery cathode mixtures. For example, in certain embodiments, provided cathode compositions may comprise 3D structured graphene (e.g., as described in U.S. Patent No. 11,299,397, LytEn, Inc., the text of which is incorporated herein by reference in its entirety). In certain embodiments, provided compositions have satisfactory electrical conductivity to provide a cathode with a low resistance pathway for electrons to access suchmanufactured cathode. In various embodiments, other additives are included in the composition to alter or otherwise enhance a cathode produced according to the principles described herein. Other cathode components include, for example, a current collector, connecting tabs, and the like.

[0067] In some cases, the cathode composition does not contain carbon, or contains a low amount of carbon (e.g., no greater than 5.0 wt.%, no greater than 3.0 wt. %, no greater than 2.0 wt.%, no greater than 1.0 wt.%, no greater than 0.5 wt.%. or no greater than 0.1 wt.%).

[0068] In certain embodiments, a cathode further comprises a coating layer. For example, in certain embodiments, a coating layer comprises a polymer, an organic material, an inorganic material, or a mixture thereof that is not an integral part of the porous composite or the current collector. In certain such embodiments, a polymer is selected from the group consisting of poly vinylidene fluoride, a copolymer of polyvinylidene fluoride and hexafluoropropylene, poly(vinyl acetate), poly(vinyl butyral-co-vinyl alcohol-co-vinyl acetate), poly(methylmethacrylate-coethyl acrylate), polyacrylonitrile, polyvinyl chloride-co-vinyl acetate, polyvinyl alcohol, poly(l-vinylpyrrolidone-co- vinyl acetate), cellulose acetate, polyvinyl pyrrolidone, polyacrylate, polymethacrylate, polyolefin, polyurethane, polyvinyl ether, acrylonitrile-butadiene rubber, styrenebutadiene rubber, acrylonitrilebutadiene styrene, a sulfonated styrene / ethylene-butylene / styrene triblock copolymer, polyethylene oxide, and derivatives, mixtures, and copolymers thereof. In some embodiments, a coating layer comprises a cationic polymer. In some embodiments, a coating layer comprises a quaternary ammonium polymer. In some embodiments, a coating layer comprises a cationic polymer as described above. In certain such embodiments, an inorganic material comprises, for example, colloidal silica, amorphous silica, surface-treated silica, colloidal alumina, amorphous alumina, tin oxide, titanium oxide, titanium sulfide (TiS2), vanadium oxide, zirconium oxide (ZrCh), iron oxide, iron sulfide (FeS), iron titanate (FeTiOs ). barium titanate (BaTiCh), and combinations thereof. In certain embodiments, an organic material comprises conductive carbon.

[0069] Suitable materials for use in cathode mixtures are disclosed in Cathode Materials for Lithium Sulfur Batteries: Design, Synthesis, and Electrochemical Performance, Lianfeng, et al., Interchopen.com, Published June 1st 2016, and The strategies of advanced cathode composites for lithium-sulfur batteries, Zhou et al., SCIENCE CHINA Technological Sciences, Volume 60. issue 2: 175-185(2017), the entire disclosures of each of which are hereby incorporated by reference herein.

[0070] In certain embodiments, the cathode comprises one or more of the following features: (a) a “stack” of multi-functional materials (e.g., wherein the stack comprises, for example, particles with gradient structures that balance the transport of ions and electrons for improved power capability, energy density, and life; bi-functional cathode additives that simultaneously store Li and conduct electrons, replacing expensive and space-wasting carbons; a binding molecule that spatiallyconstrains the electrochemical reaction storing the energy and thereby extends life; electrolyte components that improve the basic efficiency of the electrolyte, providing improved energy density; and / or a cathode design that enables greater safety and energy density); (b) a tight electrode layer; (c) a tight tertiary structure; (d) porosity control; (e) a core-shell structure; (f) a cross-linked polymer shell; (g) a self-doped poly mer shell; (h) an ion conductive binder; (i) a dual layer hybrid cathode; (j) a polymer that traps poly sulfide; (k) a three-dimensional structure with high surface area (e.g., to hold both carbon and lithium, e.g., to intercalate); and (1) a three-dimensional structure within which carbon is replaced with a metal disulfide (e.g., and wherein the battery comprises a polymer electrolyte for sulfur).

[0071] Compositions of the present disclosure have utility in manufacture of cathodes for electrochemical devices. They may be porous or non-porous. Certain compositions disclosed herein would be adhered to a current collector to form cathodes for secondary sulfur batteries. Provided cathode compositions may comprise one or more additives such as electrically conductive particles, binders, and other functional additives ty pically found in battery cathode mixtures. Generally, provided compositions include plentiful conductive particles to increase electrical conductivity of a cathode and provide a low resistance pathway for electrons to access such manufactured cathode. In various embodiments, other additives are included in the composition to alter or otherwise enhance a cathode produced according to the principles described herein. Other cathode components include, for example, a current collector, connecting tabs, and the like.Anode

[0072] In certain embodiments, a secondary sulfur battery comprises a lithium anode. A lithium anode suitable for use in lithium-sulfur cells may be used. In certain embodiments, an anode of a secondary' sulfur battery comprises a negative active material selected from materials in which lithium intercalation reversibly occurs, materials that react with lithium ions to form a lithium- containing compound, metallic lithium, lithium alloys, and combinations thereof. In certain embodiments, an anode comprises metallic lithium. In certain embodiments, lithium-containing anodic compositions comprise carbon-based compounds. In certain embodiments, a carbon-based compound is selected from the group consisting of crystalline carbon, amorphous carbon, graphite, and mixtures thereof. In certain embodiments, the anode does not contain carbon, or contains a low amount of carbon (e.g., no greater than 5.0 wt.%, no greater than 3.0 wt. %, no greater than 2.0 wt.%, no greater than 1.0 wt.%, or no greater than 0.5 wt.%). In certain embodiments, a material that reacts w ith lithium ions to form a lithium-containing compound is selected from the group consisting of tin oxide (SnCh). titanium nitrate, and silicon. In certain embodiments, a lithium alloy comprises an alloy of lithium with another alkali metal (e.g. sodium, potassium, rubidium or cesium). In certainembodiments, a lithium alloy comprises an alloy of lithium with a transition metal. In certain embodiments, lithium alloys include alloys of lithium and 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, Si, and combinations thereof. In certain embodiments, a lithium alloy comprises an alloy of lithium with indium. In certain embodiments, a lithium alloy comprises an alloy of lithium with aluminum. In certain embodiments, a lithium alloy comprises an alloy of lithium with zinc. In certain embodiments, an anode comprises a lithium-silicon alloy. Examples of suitable lithium-silicon alloys include: LiisSu, Li Si?, LivSis, LiisSia, and Li2iSi5 / Li22Sis. In certain embodiments, a lithium metal or lithium alloy is present as a composite with another material. In certain embodiments, such composites include materials such as graphite, graphene, metal sulfides or oxides, or conductive polymers.

[0073] In some embodiments, an anode is protected against redox shuttling reactions and hazardous runaway reactions by any of the methodologies reported in the art, for example, by creating a protective layer on a surface of an anode by chemical passivation or by deposition or polymerization. For example, in certain embodiments, an anode comprises an inorganic protective layer, an organic protective layer, or a mixture thereof, on a surface of lithium metal. In certain embodiments, an inorganic protective layer comprises Mg, Al, B. Sn. Pb. Cd, Si. In, Ga. lithium silicate, lithium borate, lithium phosphate, lithium phosphoronitride, lithium silicosulfide, lithium borosulfide, lithium aluminosulfide, lithium phosphosulfide, lithium fluoride or combinations thereof. In certain embodiments, an organic protective layer includes a conductive monomer, oligomer, or polymer. In certain embodiments, such polymer is selected from poly( / ?-phenylene), polyacetylene, polyty- phenylene vinylene), polyaniline, polypyrrole, polythiophene, poly(2,5-ethylene vinylene), acetylene, poly(perinaphthalene), polyacene, and poly(naphthalene-2,6-di-yl), or combinations thereof.

[0074] Moreover, in certain embodiments, inactive sulfur material, generated from an electroactive sulfur material of a cathode, during charging and discharging of a secondary sulfur battery, attaches to an anode surface. The term "inactive sulfur", as used herein, refers to sulfur that cannot participate in an electrochemical reaction of a cathode such that it contributes no capacity7upon repeated charge / discharge cycles. In certain embodiments, inactive sulfur on an anode surface acts as a protective layer on such anode. In certain embodiments, inactive sulfur is present in the form of lithium sulfide.

[0075] It is further contemplated that the concepts of the present disclosure can be adapted for use in sodium-sulfur batteries. Such sodium-sulfur batteries comprise a sodium-based anode and an intercalation or conversion material capable of intercalating or reacting with sodium ions. Such systems are encompassed within embodiments of the present disclosure.

[0076] It is further contemplated that the present disclosure can be adapted for use in batteries constructed in an anode-free configuration. In certain embodiments, a manufactured battery or battery component has an anode-free configuration and comprises an anodic current collector (e.g. copper) and one or more of the following: (a) a thin layer of garnet, (b) a structure (e.g., a complex 3D structure) with a coating deposited by atomic layer deposition (ALD) (e.g., wherein the ALD coating comprises one or more members selected from the group consisting of lithium phosphorus oxynitride (LiPON). lithium aluminum titanium phosphate (LATP), a phosphate, garnet, an oxide, perovskite, a sulphide, Li3BCh-Li2CO3 (LBCO), a sodium super ionic conductor (NASICON), and alumina); (c) a polymer (e.g., polyethylene oxide (PEO) or a block copolymer); (d) lithium phosphorus oxynitride (LiPON). and (e) a solid-electrolyte interface (SEI) layer (e.g., an artificial SEI layer formed in situ).

[0077] In certain embodiments, provided electrochemical cells are characterized in that they have a specific molar ratio of anode capacity (e.g. lithium metal provided) to cathode capacity (e.g. electroactive sulfur compositions and optionally any additional intercalation or electroactive materials included in the cathode composite). At an electrochemical cell level, this ratio of anode to cathode capacity is referred to as the n / p ratio. In its broadest embodiments, the present invention does not place any specific limits on the n / p ratio of provided electrochemical cells, however it is preferred that this ratio be optimized such that there is sufficient anode material to support full utilization of the electroactive materials in the cathode. This can be ensured by providing an n / p ratio greater than 1. An excess of anode material can be provided to account for loss of anode active material (e.g. lithium metal) during repeated cycles of stripping and plating. Many lithium sulfur batteries described in publications use a large excess of anode material to maximize cycle life, however such cells are not commercially practical as excess anode material increases cost and lowers energy density. In certain embodiments, provided electrochemical cells are characterized in that they have an n / p ratio less than 2, or less than 1.8, or less than 1.6, or less than 1.5, or less than 1.4, or less than 1.3, or less than 1.25, or less than 1.2, or less than 1.15, or less than 1.1. In certain embodiments, provided electrochemical cells are characterized in that they have an n / p ratio between 1.0 and 1.2, or between 1.05 and 1.15.Preparation of electrodes

[0078] There are a variety of methods for manufacturing electrodes for use in a secondary’ sulfur battery. One such process, commonly referred to as a “wet process,” involves adding the solid cathode materials to a liquid to prepare a slurry composition. These slurries are typically in the form of a viscous liquid that is formulated to facilitate a downstream coating operation. A thorough mixing of a slurry can be important for coating and drying operations, which affect performance and quality of an electrode. Suitable mixing devices include ball mills, magnetic stirrers, sonication, planetary mixers, high speed mixers, homogenizers, universal type mixers, and static mixers. A liquid used to make a slurry can be any capable of homogeneously dispersing an active material, a binder, a conducting material, and any additives, and that is also able to 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. It should be appreciated that certain aspects of the present disclosure can eliminate the use of one or more of these solvents.

[0079] In some embodiments, a prepared composition is coated on a current collector and dried to form an electrode. Specifically, a slurry is used to coat an electrical conductor to form an electrode by evenly spreading a slurry on to a conductor, which is then, in certain embodiments, optionally roll-pressed (e.g. calendared) and / or heated as is known in the art. Generally, a matrix of an active material and conductive material are held together and on a conductor by a binder. In certain embodiments, a 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® HSV 900, Teflon®, styrene butadiene rubber (SBR), polyethylene oxide (PEO), or polytetrafluoroethylene (PTFE) . Alternatively or additionally, in certain embodiments, lithium salts are dispersed in a matrix to improve lithium conductivity.

[0080] In certain embodiments, a 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 sheets, polymer substrates coated with conductive metal, and / or combinations thereof.

[0081] PCT Publication Nos. WO2015 / 003184, WO2014 / 074150, and WO2013 / 040067. the entire disclosures of which are hereby incorporated by reference herein, describe various methods of fabricating electrodes and electrochemical cells.

[0082] In one particular aspect, the present disclosure provides a method of making a cathode active material layer including the following steps: a) mixing and optionally milling a metal chalcogen powder, an electroactive sulfur conversion cathode material powder, and an electroactive seleniumconversion cathode material powder to form a powder mixture; b) casting a slurry to form a slurry layer, wherein the slurry includes the powder mixture and a solvent; and c) drying the slurry layer to form the cathode active material layer.

[0083] In some cases, step a) include the milling. While the mixing of step a) is shown in a particular order in the example below, any order of mixing may be utilized in step a). While SeS2 is added at a later stage of the mixing process in the example below, this component (and other components) can be added in earlier stages. While SeS2 is added after milling in the example below, this component (and other components) can be added prior to the milling.

[0084] In some cases, the method optionally includes melt diffusing a portion of the pow der mixture with another portion of the powder mixture. For example, the method can include melt diffusing the electroactive sulfur conversion cathode material and / or the electroactive selenium conversion cathode material onto the metal chalcogen.

[0085] In some cases, the casting of step b) includes casting the slurry atop a current collector, thereby forming the cathode active material layer atop the current collector. The cathode active material layer atop the current collector can be an effective cathode.

[0086] In some cases, the current collector is a coated metal foil. The coated metal foil can have a carbon coating and / or a plastic coating. The coated metal foil is composed of a metal selected from the group consisting of aluminum, nickel, copper, stainless steel, and combinations thereof.

[0087] The slurry can have a solvent composition that is more environmentally friendly than solvents that are conventionally used to form cathode active materials. In many conventional processes, the solvent includes N-methyl-2-pyrrolidone (NMP). The inventors unexpectedly discovered that the current process can be performed with a slurry that is free of NMP.

[0088] The solvent can include an alcohol. In some cases, the alcohol is selected from the group consisting of ethanol, propanol, butanol, diacetone alcohol, and combinations thereof. An example of a suitable propanol includes 1 -propanol. An example of a suitable butanol includes 1 -butanol.

[0089] In some cases, the drying of step c) is a two-stage drying process including a first stage and a second stage. The drying conditions are different betw een the first stage and the second stage. In some cases, the drying conditions of the first stage can include covering the layer of the slurry to reduce evaporation. In some cases, the drying conditions of the first stage include a first drying temperature that is lower than a second drying temperature of the second stage. In some cases, the drying conditions of the second stage include flowing a cooling fluid over a surface of the layer of the slurry to enhance and / or control evaporation. In some cases, the drying conditions of the second stage include reducing pressure to a second pressure value that is less than atmospheric pressure (i.e., less than 1 atm) and greater than 0.5 atm.Separator

[0090] In certain embodiments, a secondary sulfur battery comprises a separator, which divides the anode and cathode and prevents direct electron conduction between them. In certain embodiments, the separator has a high lithium ion permeability. In certain embodiments, a separator is relatively less permeable to polysulfide ions dissolved in electrolyte. In certain such embodiments, a separator as a whole inhibits or restricts passage of electrolyte-soluble sulfides between anodic and cathodic portions of a battery. In certain embodiments, a separator of impermeable material is configured to allow lithium ion transport between anode and cathode of a battery during charging and discharging of a cell. In some such embodiments, a separator is porous. One or more electrolyte-permeable channels bypassing, or penetrating through apertures in, an impermeable face of a separator can be provided to allow sufficient lithium ion flux between anodic and cathodic portions of a battery.

[0091] It will be appreciated by a person skilled in the art that optimal dimensions of a separator must balance competing imperatives: maximum impedance to poly sulfide migration while allowing sufficient lithium ion flux. Aside from this consideration, shape and orientation of a separator is not particularly limited, and depends in part on battery configuration. For example, in some embodiments, a separator is substantially circular in a coin-type cell, and substantially rectangular in a pouch-type cell. In some embodiments, a separator is substantially flat. However, it is not excluded that curved or other non-planar configurations may be used.

[0092] A separator may be of any suitable thickness. In order to maximize energy density of a battery, it is generally preferred that a separator is as thin and light as possible. However, a separator should be thick enough to provide sufficient mechanical robustness and to ensure suitable electrical separation of the electrodes. In certain embodiments, a separator has a thickness of from about 1 pm to about 200 pm, preferably from about 5 pm to about 100 pm, more preferably from about 10 pm to about 30 pm.Electrolyte

[0093] For the provided cathode active material to function in an electrochemical cell, an electrolyte is needed to support the movement of metal ions (e.g. lithium or sodium ions) from the anode to the cathode. To accomplish this function, the electrolyte must be in intimate contact with both the anode (i.e. in contact with a lithium metal anode surface or a solid lithium protection layer on such a lithium metal anode) and with the cathode active material. As noted herein, cathodes are ty pically porous composites; it is desirable that electrolyte occupies most or substantially all of this porosity7and thereby enables metal ions from the anode to reach the cathode active material and vice-versa. Beyond fulfilling this function, the present invention places no particular constraints on thecomposition or physical properties of the electrolyte. In certain embodiments, a suitable electrolyte may comprise a liquid, a solid, a gel, or a combination of two or more of these.

[0094] In certain embodiments, a secondary sulfur battery includes an electrolyte comprising one or more salts to support ion transport (e.g. lithium ion transport) such salts are referred to herein as electrolytic salts. Examples of useful electroly tic salts are lithium salts having reasonable solubility in organic solvents. Such salts include, for example, lithium halides, lithium sulfonyl imide salts, lithium organosulfonate salts, and lithium carboxylate salts. Examples of electrolytic salts include, for example, lithium trifluoromethane sulfonimide, lithium triflate, lithium perchlorate, LiPFe, LiBF4, tetraalkylammonium salts (e.g. tetrabutylammonium tetrafluoroborate, TBABF4), liquid state salts at room temperature (e.g. imidazolium salts, such as l-ethyl-3-methylimidazolium bis- (perfluoroethyl sulfonyl)imide, EMIBeti). and the like.

[0095] In certain embodiments, an electrolyte comprises one or more alkali metal salts. In certain embodiments, such salts comprise lithium salts selected from LiOSChCFs, LiCICL, LiNCh, LiPFe, LiBF4, LiBr, Lithium bis(trifluoromethanesulfonyl)imide( LiTFSI), Lithium bis(fluorosulfonyl)amide (LiFSI, lithium 4,5-dicyano-2-(trifluoromethyl)imidazole (LiTDI), LiBr. Lil, LiCChCF?, LiOAc, lithium difluoro(oxalato)borate (LiDFOB), lithium bis(oxalato)borate (LiBOB), lithium oxalatophosphates (e.g., lithium tetrafluoro oxalatophosphate, lithium trisoxalatophosphate, lithium difluoro bisoxalatophosphate, etc.), lithium trifluoroacetate, Lil, lithium difluorophosphate, or combinations of any two or more of these. In certain embodiments, an electrolyte comprises ionic liquids, such as l-ethyl-3-methylimidzaolium-TFSI, N-butyl-N-methyl- piperidinium-TFSI, N-methyl-n-butyl pyrrolidinium-TFSL and N-methyl-N-propylpiperidinium- TFSI, or combinations thereof. In certain embodiments, an electrolyte comprises superionic conductors, such as sulfides, oxides, and phosphates, for example, phosphorous pentasulfide, or combinations thereof. In certain embodiments, electrolytes may include salts of cations other than lithium. These can include salts of other alkali earth metals (e.g. sodium, potassium, rubidium or cesium salts), tetraalkylammonium salts (e.g. tetrabutylammonium tetrafluoroborate, TBABF4), as well as ionic liquids (e.g. imidazolium salts, such as l-ethyl-3-methylimidazolium bis- (perfluoroethyl sulfonyl)imide, EMIBeti), and the like.

[0096] In certain embodiments, a total concentration of salts in an electrolyte is no more than 2M, no more than 1.8M, no more than 1.6M, no more than 1.5M, no more than 1.4M, no more than 1.3M, no more than 1.2M, or no more than IM. In certain embodiments, a total concentration of lithium salts in an electrolyte is no more than 2M, no more than 1.8M, no more than 1.6M, no more than 1.5M, no more than 1.4M. no more than 1.3M, no more than 1.2M. or no more than IM. In certain embodiments, a total concentration of primary lithium salts in an electrolyte is no more than 2M, nomore than 1.8M, no more than 1.6M, no more than 1.5M, no more than 1.4M, no more than 1.3M, no more than 1 ,2M. or no more than IM. In certain embodiments, a total concentration of electrolytically active salts in an electrolyte is no more than 2M, no more than 1.8M, no more than 1.6M, no more than 1.5M, no more than 1.4M, no more than 1.3M, no more than 1.2M, or no more than IM. In certain embodiments, a total concentration of electroly tically active salts in an electrolyte is no more than 2M, no more than 1.8M. no more than 1.6M, no more than 1.5M. no more than 1.4M. no more than 1.3M, no more than 1.2M. or no more than IM. In certain embodiments, a total concentration of electrolytically active lithium salts in an electrolyte is no more than 2M, no more than 1.8M, no more than 1.6M, no more than 1.5M, no more than 1.4M, no more than 1.3M, no more than 1.2M, or no more than IM.

[0097] In certain embodiments, an electrolyte is a liquid. For example, in certain embodiments, an electrolyte comprises an organic solvent. In certain embodiments, an electrolyte comprises only one organic solvent. In some embodiments, an electrolyte comprises a mixture of two or more organic solvents. In certain embodiments, a mixture of organic solvents comprising one or more weak polar solvents, strong polar solvents, and lithium protecting solvents.

[0098] In certain embodiments, a provided electrolyte comprises a liquid composition comprising one or more organic solvents. In certain embodiments, provided electrolyte compositions comprise one or more ethers selected from the group consisting of: dimethoxyethane, dioxolane, tetrahydrofuran, methylcyclopentyl ether, methyl tetrahydrofuran, dimethyl tetrahydrofuran, dibutyl ether, 1,4-dioxane. glyme. di ethoxy ethane, diglyme, triglyme, tetraglyme, or n-glymes with n > 5 (e.g., pentaglyme or hexaglyme), or a mixture thereof. In certain embodiments, an electrolyte comprises a mixture of organic solvents. For example, a mixture of two or more ethers, for example an electrolyte may comprise a mixture of dimethoxyethane and 1,3 -di oxolane. Such mixtures may be mixed at a ratio (e.g., by weight) of dimethoxy ethane to 1.3-dioxolane in a range of 10: 1 to 1 : 10, 5: 1 to 1:5, or 3: 1 to 1:3.

[0099] In certain embodiments, electrolytes comprise blends of multiple classes of organic solvents, e.g., a mixture of a weak polar solvent and / or a strong polar solvent and / or a lithium protecting solvent. The term "weak polar solvent", as used herein, is defined as a solvent that is capable of dissolving elemental sulfur and has a dielectric coefficient of less than 15. A weak polar solvent is selected from aryl compounds, bicyclic ethers, and acyclic carbonate compounds. Examples of weak polar solvents include xylene, dimethoxyethane, 2-methyltetrahydrofuran, diethyl carbonate, dimethyl carbonate, toluene, dimethyl ether, diethyl ether, diglyme. tetraglyme, and the like. The term "strong polar solvent", as used herein, is defined as a solvent that is capable of dissolving lithium polysulfide and has a dielectric coefficient of more than 15. A strong polar solvent isselected from bicyclic carbonate compounds, sulfoxide compounds, lactone compounds, ketone compounds, ester compounds, sulfate compounds, and sulfite compounds. Examples of strong polar solvents include hexamethyl phosphoric triamide, y-butyrolactone, acetonitrile, ethylene carbonate, propylene carbonate, N-methylpyrrolidone, 3-methyl-2-oxazolidone, dimethyl formamide, sulfolane, dimethyl acetamide, dimethyl sulfoxide, dimethyl sulfate, ethylene glycol diacetate, dimethyl sulfite, ethylene glycol sulfite, and the like. The term "lithium protection solvent", as used herein, is defined as a solvent that forms a good protective layer, i.e. a stable solid-electrolyte interface (SEI) layer, on a lithium surface, and which shows a cyclic efficiency of at least 50%. A lithium protection solvent is selected from saturated ether compounds, unsaturated ether compounds, and heterocyclic compounds including one or more heteroatoms selected from the group consisting of N, O, and / or S. Examples of lithium protection solvents include tetrahydrofuran, 1.3 -di oxolane, 3,5- dimethylisoxazole, 2,5-dimethyl furan, furan, 2-methyl furan, 1,4-oxane, 4-methyldi oxolane, and the like.

[0100] In certain embodiments, a lithium protection solvent is selected from fluorinated hydrocarbons and fluoroethers. Examples of fluorinated solvents include bis(trifluoroethyl) ether.1.1.2.2-TetrafluoroethyI-2,2,3.3-teirafluoropropylether, tris(2,2.2-trifluoroethyl) orthofonnaie. mefhoxyperfiuorobutane. hexafluoroisopropyl methyl ether, 1,1,2,2-tetrafluoroethyl 2,2.2- trifluoroetliyl ether, 3-(Difluoromethoxy)-I,l,2,2-tetrafluoropropane, fluoroacetonitrile, ethyl1.1 .2.2-telrafluoroelhyl ether.

[0101] In certain embodiments, a mixture of a weak polar solvent and strong polar solvent is provided at a weight ratio in a range of 10: 1 to 1 : 10, 5: 1 to 1 :5, or 3:1 to 1 :3. In certain embodiments, a mixture of a weak polar solvent and a lithium-protective solvent is provided at a weight ratio in a range of 10: 1 to 1: 10, 5: 1 to 1 :5, or 3: 1 to 1:3.

[0102] In certain embodiments, an electrolyte is a liquid (e.g., an organic solvent). In some embodiments, a liquid is selected from the group consisting of organocarbonates, ethers, sulfones, water, alcohols, fluorocarbons, or combinations of any of these. In certain embodiments, an electrolyte comprises an ethereal solvent.

[0103] In certain embodiments, an organic solvent comprises an ether. In certain embodiments, an organic solvent is selected from the group consisting of 1, 3 -di oxolane, dimethoxy ethane, diglyme. triglyme, y-butyrolactone, y-valerolactone, and combinations thereof. In certain embodiments, an organic solvent comprises a mixture of 1,3-di oxolane and dimethoxyethane. In certain embodiments, an organic solvent comprises a 1 :1 v / v mixture of 1,3-dioxolane and dimethoxy ethane. In certain embodiments, an organic solvent is selected from the group consisting of: diglyme, triglyme, y-butyrolactone, y-valerolactone, and combinations thereof. In certain embodiments, anelectrolyte comprises sulfolane, sulfolene, dimethyl sulfone, methyl ethyl sulfone, or a combination thereof. In some embodiments, an electrolyte comprises ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate, methylethyl carbonate, or a combination thereof

[0104] In certain embodiments, a provided electrolyte (or a portion of a provided electrolyte) is a solid. In certain embodiments, a solid electrolyte comprises a glass, a ceramic, an inorganic composite, or combinations thereof. In certain embodiments, a solid electrolyte comprises a polymer. In certain embodiments, a solid electrolyte comprises a polymer composite with a glass, a ceramic, an inorganic composite, or combinations thereof. In certain embodiments, such solid electrolytes comprise one or more liquid components as plasticizers or to form a “gel electrolyte”. In certain embodiments, a solid electrolyte comprises superionic conductors, such as sulfides, oxides, and phosphates, for example, phosphorous pentasulfide, or combinations thereof.Secondary sulfur-selenium batery

[0105] Described herein are secondary sulfur batteries comprising cathode compositions described above. For example, in certain embodiments, such batteries include a lithium-containing anode composition coupled to the provided cathode composition by a lithium conducting electrolyte. In some embodiments, such batteries also comprise additional components such as separators between the anode and cathode, anodic and cathodic current collectors, terminals by which a cell can be coupled to an external load, and packaging such as a flexible pouch or a rigid metal container. It is further contemplated that the present disclosure regarding secondary sulfur batteries can be adapted for use in sodium-sulfur batteries, and such batteries are also considered within the scope of certain embodiments of the present disclosure.

[0106] FIG. 1 illustrates a cross section of an electrochemical cell 800 in accordance with exemplary embodiments of the disclosure. Electrochemical cell 800 includes a negative electrode 802, a positive electrode 804, a separator 806 interposed between negative electrode 802 and positive electrode 804, a container 810, and a fluid electrolyte 812 in contact with negative and positive electrodes 802, 804. Such cells optionally include additional layers of electrode and separators 802a, 802b, 804a, 804b, 806a, and 806b.

[0107] Negative electrode 802 (also sometimes referred to herein as an anode) comprises a negative electrode active material that can accept cations. Non-limiting examples of negative electrode active materials for lithium-based electrochemical cells include Li metal, Li alloys such as those of Si, Sn, Bi, In, and / or Al alloys, Li4TisOi2, hard carbon, graphitic carbon, metal chalcogenides, and / or amorphous carbon. In accordance with some embodiments of the disclosure, most (e.g., greater than 90 wt %) of an anode active material can be initially included in a discharged positive electrode 804 (also sometimes referred to herein as a cathode) when electrochemical cell 800 isinitially made, so that an electrode active material forms part of first electrode 802 during a first charge of electrochemical cell 800.

[0108] A technique for depositing electroactive material on a portion of negative electrode 802 is described in U.S. Patent Publication Nos. 2016 / 0172660 and 2016 / 0172661, in the name of Fischer et al., the contents of each of which are hereby incorporated herein by reference, to the extent such contents do not conflict with the present disclosure.

[0109] Positive electrode 804 (also referred to herein as cathode) comprises a cathode composition as described herein. In certain embodiments, the cathode composition comprises about 30 to about 70 wt% electroactive sulfur. In certain embodiments, a cathode comprises at least about 70% of total sulfur present in an electrochemical cell. In certain embodiments, a cathode comprises at least about 80% of total sulfur present in an electrochemical cell. In certain embodiments, a cathode comprises at least about 90% of total sulfur present in an electrochemical cell. In certain embodiments, a cathode comprises at least about 95% of total sulfur present in an electrochemical cell. In certain embodiments, a cathode comprises at least about 99% of total sulfur present in an electrochemical cell. In certain embodiments, a cathode comprises essentially all of the total sulfur present in an electrochemical cell.

[0110] Negative electrode 802 and positive electrode 804 can further include one or more electrically conductive additives as described herein. In accordance with some embodiments of the disclosure, negative electrode 802 and / or positive electrode 804 further include one or more polymer binders as described herein.

[0111] FIG. 2 illustrates an example of a battery according to various embodiments described herein. A cylindrical battery' is show n here for illustration purposes, but other types of arrangements, including prismatic or pouch (laminate-type) batteries, may also be used as desired. Example Li battery 901 includes a negative anode 902, a positive cathode 904, a separator 906 interposed between the anode 902 and the cathode 904, an electrolyte (not shown) impregnating the separator 906, a battery case 905, and a sealing member 908 sealing the battery' case 905. It w ill be appreciated that example battery' 901 may simultaneously embody multiple aspects of the present disclosure in various designs.

[0112] A secondary sulfur battery of the present disclosure comprises a lithium anode, a sulfurbased cathode, and an electrolyte permitting lithium ion transport between anode and cathode. In certain embodiments, described herein, an anodic portion of a battery' comprises an anode and a portion of electrolyte with which it is in contact. Similarly, in certain embodiments, described herein, a cathodic portion of a battery comprises a cathode and a portion of electrolyte with which it is in contact. In certain embodiments, a battery comprises a lithium ion-permeable separator, whichdefines a boundary between an anodic portion and a cathodic portion. In certain embodiments, a battery comprises a case, which encloses both anodic and cathodic portions. In certain embodiments, a battery case comprises an electrically conductive anodic-end cover in electrical communication with an anode, and an electrically conductive cathodic-end cover in electrical communication with a cathode to facilitate charging and discharging via an external circuit.

[0113] In certain embodiments, a secondary sulfur battery of the present disclosure is defined in terms of its ratio of electrolyte to electroactive sulfur. Electrolyte volume and the ratio (vol / wt) of electrolyte to sulfur in a cathode correlate to energy density of a sulfur battery. Electrolyte may be distributed among different volumes within a cell, for example electrolyte may be contained in porosity of the cathode, in the separator, and in contact with the anode or within an anodic solid electrolyte interphase. Electrolyte may also be contained in other spaces within a battery where it is not in direct contact with the anodic or cathodic active materials-for example electrolyte may be stranded in an annular volume at the edges of a coin cell. In certain embodiments, the present invention provides batteries where all or most of the electrolyte is contained within the cathode. Preferably, substantially all of the electrolyte is contained within the cathode and only a minimal amount of electrolyte that is necessary to wet the separator and the anode surface or SEI is outside of the cathode. Electrolyte contained within the cathode is referred to as ‘’contained electrolyte” and its volume VCE can be estimated as theoretical pore volume, or porosity’ multiplied by the geometric volume of a cathode film:

[0114] In certain embodiments, a provided secondary sulfur battery is characterized in that at least 50% of the total electrolyte inventoryis contained in the cathode (e.g. NCENM >0.5). In certain embodiments, a provided secondary sulfur battery is characterized in that at least 50% of the total electrolyte inventory (Vtor) is contained in the cathode (e.g.>0.8). In certain embodiments, a secondary sulfur batters’ has at least 60%, at least 65%, or at least 70% of the electrolyte contained in the cathode porosity. In certain embodiments, a secondary sulfur battery has at least 80%, at least 85%, or at least 90%, of the electrolyte contained in the cathode porosity. In certain embodiments, a 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 cathode.

[0115] The ratio of total electrolyte-to-sulfur (E / S) is another parameter that influences the energy density7of a battery. The E / S ratio is calculated based on the total volume of electrolyteand the mass of electroactive sulfur (m™ / ):

[0116] In certain embodiments, a secondary sulfur battery has an electrolyte-to-sulfur ratio equal to or less than about 6 microliters of electrolyte per milligram of electroactive sulfur. In certain embodiments, a secondary sulfur battery' has an electrolyte-to-sulfur ratio equal to or less than about 5 microliters of electrolyte per milligram of electroactive sulfur. In certain embodiments, a secondary sulfur battery has an electrolyte-to-sulfur ratio equal to or less than about 4.5 microliters of electrolyte per milligram of electroactive sulfur. In certain embodiments, a secondary sulfur battery has an electrolyte-to-sulfur ratio equal to or less than about 3.5 microliters of electrolyte per milligram of electroactive sulfur or less than about 3.0 microliters of electrolyte per milligram of electroactive sulfur. In certain embodiments, a secondary7sulfur battery has an electrolyte-to-sulfur ratio equal to or less than about 3.5 microliters of electrolyte per milligram of electroactive sulfur. In certain embodiments, a secondary' sulfur battery' has an electrolyte-to-sulfur ratio equal to or less than about 3 microliters of electrolyte per milligram of electroactive sulfur. In certain embodiments, a secondary sulfur battery has an electrolyte-to-sulfur ratio between about 1.8 and about 3.5 pL / mg S. In certain embodiments, a secondary' sulfur battery has an electrolyte-to-sulfur ratio between about 1.8 and about 2.5 pL / mg S. In certain embodiments, a secondary sulfur battery' has an electrolyte-to- sulfur ratio between about 1.0 and about 2.0 pL / mg S. In certain embodiments, a secondary sulfur battery' has an electrolyte-to-sulfur ratio between about 1.5 and about 2.0 pL / mg S.

[0117] The disclosed cathode active materials can be deployed in a variety' of different applications for electrochemical storage.

[0118] For UxS applications, an ideal battery' cell will have the highest specific energy density possible (Wh / kg) while also being able to supply sufficient power (discharge rate) for rapid acceleration or elevation gain. UxS applications can refer to vertical takeoff aircraft (e.g. “quadcopter’'), fixed wing aircraft, and hybrids that are both fixed wing and vertical takeoff of which there are many variants. The term '‘UxS applications” also includes surveillance reconnaissance (“ISR”) missions that use similar aircraft and UxSs that carry7kinetic and / or explosive charges such as loitering munitions.

[0119] Fixed wing aircraft are generally less sensitive to power requirements as they can be “launched” by hand, with a catapult, or dropped from other aircraft. Then, elevation gain early in the flight requires less power vs. vertical lift.

[0120] For aircraft with short lifetimes, i.e. “one way missions”, a very7low cost of energy7is also ideal, and these applications are relatively insensitive to cycle life.

[0121] Therefore, a cell with ven' high specific energy density, high discharge rate, and low' cost is most ideal for UxS applications.

[0122] Pulse power and pulse efficiency are important in vehicle applications where the vehicle is accelerating. When a vehicle accelerates, it uses the most power and is the least efficient. Maximizing these tw o performance metrics is important in order to make electric vehicles appealing to customers. As illustrated in the examples below, the addition of Se and TiS2 also increased the pulse efficiency at high discharge rates of 3C between 30-90% discharge, as shown in Fig. 7. This discharge range is relevant to vehicle applications where the batteries are not usually either fully charged or fully discharged to prolong battery' life. The high discharge rate of 3C is relevant because that would represent the conditions where the vehicle is accelerating at a high rate. The pulse pow er density versus fraction discharge was also measured and S-Se-TiS2 cathodes are nearly as high as the S-only cathodes and much higher than the S-Se and the S-TiS2 cathodes. Thus, the S-Se-TiS2 cathodes yield only a small sacrifice of pulse pow er for a much longer cycle life versus the S-only cathodes, especially compared to the S-Se and the S-TiS2 cathodes. Gravimetric pulse power density' is important to vehicle applications where lightweight components produce more fuel efficient (or energy efficient) vehicles. It is not obvious that adding both Se and TiS2 to a sulfur-based cathode would produce these effects on the pulse power density and the pulse efficiency because adding both independently was detrimental.

[0123] In certain cases, the disclosed cathode active materials when deployed in a functioning battery (e.g., a test battery, a car battery, etc.) can produce an unexpectedly strong average pulse efficiency versus fraction discharge 10% and 100% discharge, between 20% and 95% discharge, and / or between 30% and 90% discharge. In some cases, the disclosed cathode active materials, when deployed in a functioning battery' and / or test battery under the conditions described herein, can produce an average pulse efficiency of at least 60%, at least 65%, or at least 70% for each fraction discharge between 30% and 90% discharge or an average pulse efficiency of at least 70%, at least 75%, at least 80%, or at least 85% for each fraction discharge betw een 40% and 90% discharge.

[0124] In general, the disclosed cathode active materials when deployed in a functioning battery' (e.g., a test battery, a car battery, etc.) can produce an average pulse efficiency above a first average pulse efficiency threshold over a predetermined fraction discharge range (i.e., across the entirety of the range). The first average pulse efficiency threshold can be at least 50%, at least 55%, at least 60%, at least 65%, at least 70%, at least 75%, at least 80%, or at least 85%. The predetermined fraction discharge range can have a minimum value of at least 10%, at least 15%, at least 20%, at least 25%, at least 30%, at least 35%, at least 40%, at least 45%, at least 50%, at least 55%, or at least 60%. The predetermined fraction discharge range can have a maximum value of at most 100%,at most 99%, at most 95%, at most 90%, at most 85%, at most 80%, at most 75%, at most 70%, at most 65%, at most 60%. at most 55%. or at most 50%.

[0125] For electrochemical measurements described herein, measurements may be made at a discharge rate that is intended to simulate specific real-world conditions. In some cases, the measurements may be made using a 3C discharge rate. In some cases, the measurements may be made with a discharge rate of 200-5000 mA / gS. including 500 mA / gS, 1000 mA / gS. 2000 mA / gS, or 3000 mA / gS.

[0126] Given the enhanced power and conversion efficiency, the disclosed cathode active materials may be useful in all solid state sulfur cells that operate within ranges that are around room temperature and under ambient conditions, i.e. from about -20 °C up to about 60 °C. These cells could use solid electrolytes known to those of ordinary skill in the art, such as sulfides (compositions of Li, phosphorus and sulfur, and in some cases halides, e.g. argyrodites), garnets, LiSiCON, thio- LiSiCONs, etc.

[0127] Additionally , it may be advantageous to use these blends in cells that operate at elevated temperatures where one or more of the electrodes may be in a molten state. These cells may also utilize a solid electrolyte separator, solid electrolyte in the cathode, or both. The solid electrolytes in each component may not be the same. The cathode compositions may optionally contain a metal sulfide and / or other additives that alter the performance and / or the mechanism of reduction of the conversion active.

[0128] In some cases the cell may be a “hybrid” cell that utilizes a solid electrolyte protected anode, with a liquid electrolyte on the cathode side. There may be a solid electrolyte separator with liquid on both anode and cathode side. The liquid electrolytes need not be the same. The cell may operate at relatively low' temperatures or elevated temperatures, as dictated by the stability' of the components and interfaces.

[0129] Liquid electrolytes may be of the type that dissolve polysulfides, polyselenides and polyselenosulfides, or may not give rise to dissolved intermediates, in other words the conversion may be effectively a solid state conversion of the active material in some electrolytes, and may go through dissolved intermediates in some electrolytes.

[0130] In some cases, the cathode active materials are capable of forming batteries having unexpectedly improved performance, particularly relating to improved cycle life at high powder. In particular, the cathode active materials described herein have superior performance when compared w ith a comparison cathode active material that replaces all of the electroactive selenium conversion cathode with an equal mass of electroactive sulfur conversion cathode material. In these comparisons, the cathode active material having selenium has a battery life cycle that is at least 10%,at least 20%, at least 30%, at least 40%, or at least 50% greater than a comparison test cell battery cycle life for the comparison cathode active material.EXAMPLES

[0131] In order that the application may be more fully understood, the following examples are set forth. It should be understood that these examples are for illustrative purposes only and are not to be construed as limiting in any manner.

[0132] Example la: construction of sulfur selenium batteries and comparative batteries lacking selenium

[0133] To evaluate the operability and performance advantages of the inventive selenium- containing cathodes, coin cells were constructed using single layer cathodes comprising electroactive sulfur, selenium and titanium disulfide along with additives, conductive carbon and a polymer binder (other solids). Sulfur-selenium cathodes (Cathodes 1-8) were formulated with a range of compositions varying the mass ratios of sulfur, selenium and TiS2 comparative cathodes lacking selenium (Cathodes C1-C3) were also produced as controls. The compositions of the cathodes are shown in TABLE 1:TABLE 1, composition of cathodes used in Example 1

[0134] To produce the cathodes in Table 1 homogenized slurries of the cathode components suspended in a suitable solvent was cast onto a carbon-coated aluminum current collector and dried to provide cathodes with areal loadings of 3.4 - 6.7 mg S+Se / cm2and thicknesses from 100-250 microns.

[0135] Punches of the dried cathode films were assembled into 2032 coin cells using Celgard™ separators and lithium metal anodes. Each coin cell was loaded with enough liquid electrolyte (LiFSI and LiNCh in DOL / DME) to provide an E / S+Se ratios of 4-4.5 pL / mg. Groups of five cells containing each cathode composition were cycled using a Maccor battery' test system according to the protocols described in Examples lb to 1c.Example lb: impact of selenium cathodes on cycle life

[0136] Coin cells containing either cathode composition 1 (with selenium) or cathode composition Cl (lacking selenium) were tested using a battery cycling protocol consisting of a 5 cycle formation period consisting of discharges at C / 10, 2 x C / 5, 2 x C / 3, following which the cells were looped through one cycle at lOOmA / g with intermittent pulses followed by 19 cycles at 335mA / g Fig. 3, shows a plot of capacity versus number of charge discharge cycles for these cells. It is apparent from this plot that the selenium-containing cathodes (solid gray lines) have higher capacity retention than the cells lacking selenium (solid black lines). Unexpectedly, replacing a mere 27% of the sulfur in the cathode active material with selenium led to an average cycle life that was more than doubled under these test conditions.Example 1c: synergy between selenium and metal chalcogenides

[0137] In this example, coin cells with cathode compositions 1 and 2 from Table 1 which both contain sulfur, selenium, and the metal chalcogenide (US2) were compared with cells contain with cathode 3 containing sulfur and selenium but lacking TiS2. As shown in Fig. 4. cathodes containing both selenium and TiS2 have improved cycle life relative to the cathode which does not contain TiS2. Cells depicted in solid grey lines have similar composition to those depicted by solid black lines with respect to S+Se content, how ever the cells depicted by black lines also contain TiS2, furtherdemonstrating the unexpected improvement in cycle life when both metal sulfide and selenium are present in the cathode composition.Example Id: improved cycle life

[0138] Cathode active materials and coin cells were prepared using the methods described in Example la, both cathodes had an overall composition of -55% chalcogen in the cathode by mass. These cells were fabricated with an E / S=4 and a loading of approx. 4-4.5 mg S (or S+Se) / cm2. Referring to Fig. 5, Se-containing cells (denoted by "SSeMS”) have, on average. -25 more life cycles prior to failure, which represents >50% higher cycle life versus a sulfur-only cathode (denoted by “SMS-Ti-PM”). The cells were cycled through 800 mAh / g, -80% of their capacity via limited charge to 800 mAh / g following a full discharge. The 80% cycling protocol assists in equalizing total Li throughput at the anode when there is cell-to-cell variability in observed capacity (mAh / g S+Se). The figure demonstrates the unexpectedly improved cycle life of the cells using a blend of S+Se+Metal Sulfide (SSeMS) vs those cells containing S+Metal sulfide only (SMS-Ti-PM).Example le: improved pulse efficiency across fractional discharge

[0139] Cathode active materials and coin cells were prepared using the methods described in Example la. A “sulfur-only “ cathode active material included (all values in this paragraph are by weight) 60.8% S, 30.2% carbon black (“CB”) and 9% NaPAA. A “S / Se” cathode active material included 44.2% S, 17% Se, 29.8% CB, and 9% NaPAA. A “S / TiS2” cathode active material included 57.9% S, 23.1% TiS2, 10% CB, and 9% NaPAA. A “S / Se / TiS2'’ cathode active material included 49.8% S. 7.8% Se. 23.4% TiS2, 10% CB, and 9% NaPAA.

[0140] Coin cells for each composition were cycled under a 3C discharge rate. Average battery life as measured by total number of cycles is shown in Fig. 6. Average pulse efficiency versus fraction discharge is shown in Fig. 7.

[0141] Figure 6 demonstrates the improved cycle life improvement achieved for the S / Se / TiS2 cathode vs when only Se is added (S / Se) or when only metal sulfide is added (S / TiS2). Likewise, Figure 7 demonstrates the unexpected improvement in pow er for this cathode. While S-TiS2 demonstrates low' pulse efficiency across the total discharge, there is a marked improvement for S- Se-TiS2 cathode in the region of 0-0.3 fractional discharge and then the S-Se-TiS2 cathode demonstrates the highest pulse efficiency from approx. 0.4-0.9 fractional discharge, further demonstrating the synergistic and unexpected improvement in powder delivery for this cathode composition.

[0142] We have also shown that changing the ratios of S to Se produces similarly high cycle life cells as shown in Fig. 8 for coin cells using Li metal anodes. The weight ratios of S:Se that we have tested in cells (with TiS2 added) are 2.7: 1 (41.7% S, 15.7% Se, 23.7% TiS2, 10% CB, and 9%NaPAA). 6.4: 1 (49.8% S, 7.8% Se, 23.4% TiS2, 10% CB. and 9% NaPAA), and 13.8: 1 (53.9% S, 3.9% Se, 23.2% TiS2, 10% CB and 9% NaPAA), but other ratios would be expected to work also. Those cathode compositions all contained -23.5 wt% TiS2, but we believe other amounts will work as well. The amount of carbon black and Na-PAA binder in those cells was kept constant at 10 wt% and 9%, respectively, but these amounts could also be varied to some degree and still be expected to produce functional, cycling batteries.

[0143] Further functioning test cells have been prepared with the following cathode active material composition ranges: 31-58 wt% S; 3.9-15.7 wt% Se; 8-53 wt% TiS2; 2-15 wt% CB; and a constant of 9% NaPAA (though varying that concentration is also contemplated as discussed elsewhere herein).

[0144] Two specific test cells were made and showed generally good performance. One of these test cells included a cathode active material with the following composition: 58.6% S; 8.4% Se, 8% TiS2, 15% CB, and 9% NaPAA. The other included a cathode active material with the following composition: 46.4% S; 7.6% Se; 33% TIS2; 3% CB; and 9% NaPAA.Example 2: impact of selenium cathodes on capacity at E / S=2.5

[0145] To produce the cathodes in Table 2 homogenized slurries of the cathode components suspended in a suitable solvent were cast onto a carbon-coated aluminum current collector and dried to provide cathodes with areal loadings of -3 mg S+Se / cm2

[0146] Punches of the dried cathode films w ere assembled into 2032 coin cells using Celgard™ separators and lithium metal anodes. Each coin cell was loaded with enough liquid electrolyte (LiFSI and L1NO3 in DOL / DME) to provide an E / S+Se ratio of 2.5 pL / mg. Groups of cells containing each cathode composition were cycled using a Maccor battery test system according to a protocol described in in Examples lb to 1c.

[0147] Coin cells containing either cathode composition 10 (with selenium) or cathode composition C4 were tested using a battery cycling protocol consisting of a 3 cycle formation period consisting of discharges at C / 10 and charges at C / 5, followed by continuous cycling using a discharge at C / 2 and charge at C / 5. Table 2 shows the compositions of the cathodes. Table 3 shows capacity in mAh / g S+Se for the 2nddischarge at C / 10 and the first discharge at C / 2. Unexpectedly, introducing a mere 8% of the sulfur in the cathode active material with selenium led to an improved average discharge capacity at both rates, with a significant improvement at C / 2. This is particularly surprising given that Se has a low er capacity (mAh / g) than sulfur.TABLE 2, composition of cathodes used in Example 2TABLE 3, capacity measurements for cathodes in Example 2EQUIVALENTS

[0148] It is contemplated that systems, devices, methods, and processes of the disclosure encompass variations and adaptations developed using information from the embodiments described herein. Adaptation and / or modification of the systems, devices, methods, and processes described herein may be performed by those of ordinary skill in the relevant art.

[0149] Certain embodiments of the present disclosure were described above. It is, however, expressly noted that the present disclosure is not limited to those embodiments, but rather the intention is that additions and modifications to what was expressly described in the present disclosure are also included within the scope of the disclosure. Moreover, it is to be understood thatthe features of the various embodiments described in the present disclosure were not mutually exclusive and can exist in various combinations and permutations, even if such combinations or permutations were not made express, without departing from the spirit and scope of the disclosure. The disclosure has been described in detail with particular reference to certain embodiments thereof, but it will be understood that variations and modifications can be effected within the spirit and scope of the claimed invention.

[0150] It should be apparent to those skilled in the art that many additional modifications beside those already described are possible without departing from the inventive concepts. In interpreting this disclosure, all terms should be interpreted in the broadest possible manner consistent with the context. Variations of the term "comprising" should be interpreted as referring to elements, components, or steps in a non-exclusive manner, so the referenced elements, components, or steps may be combined with other elements, components, or steps that are not expressly referenced. Embodiments referenced as "comprising" certain elements are also contemplated as "consisting essentially of and "consisting of those elements. When two or more ranges for a particular value are recited, this disclosure contemplates all combinations of the upper and lower bounds of those ranges that are not explicitly recited. For example, recitation of a value of between 1 and 10 or between 2 and 9 also contemplates a value of between 1 and 9 or between 2 and 10.

[0151] As used herein, the terms “include’' and “including” have the same meaning as the terms “comprise” and “comprising.” The terms “comprise” and “comprising” should be interpreted as being “open” transitional terms that permit the inclusion of additional components further to those components recited in the claims. The terms “consist” and “consisting of’ should be interpreted as being “closed” transitional terms that do not permit the inclusion of additional components other than the components recited in the claims. The term “consisting essentially of’ should be interpreted to be partially closed and allowing the inclusion only of additional components that do not fundamentally alter the nature of the claimed subject matter.

[0152] All methods described herein can be performed in any suitable order unless otherwise indicated herein or otherwise clearly contradicted by context. The use of any and all examples, or exemplary language (e.g., “such as”) provided herein, is intended merely to better illuminate the invention and does not pose a limitation on the scope of the invention unless otherwise claimed. No language in the specification should be construed as indicating any non-claimed element as essential to the practice of the invention.

[0153] All references, including publications, patent applications, and patents, cited herein are hereby incorporated by reference to the same extent as if each reference were individually and specifically indicated to be incorporated by reference and were set forth in its entirety herein.

[0154] Preferred aspects of this invention are described herein, including the best mode know n to the inventors for carrying out the invention. Variations of those preferred aspects may become apparent to those of ordinary skill in the art upon reading the foregoing description. The inventors expect a person having ordinary skill in the art to employ such variations as appropriate, and the inventors intend for the invention to be practiced otherwise than as specifically described herein. Accordingly, this invention includes all modifications and equivalents of the subject matter recited in the claims appended hereto as permitted by applicable law. Moreover, any combination of the abovedescribed elements in all possible variations thereof is encompassed by the invention unless otherwise indicated herein or otherwise clearly contradicted by context.

[0155] While the invention has been illustrated and described in detail in the foregoing drawings and description, the same is to be considered as illustrative and not restrictive in character, it being understood that only illustrative embodiments thereof have been show n and described and that all changes and modifications that come within the spirit of the invention are desired to be protected. For example, any of the features or functions of any of the embodiments disclosed herein may be incorporated into any of the other embodiments disclosed herein.

Claims

What is claimed is:

1. A batery cathode comprising: a cathode film adhered to a current collector, the cathode film comprising a mixture of titanium disulfide and a conversion active material, wherein: the conversion active material comprises a mixture of electroactive selenium and electroactive sulfur, the titanium disulfide is present in the cathode at between 5 and 30 mass percent relative to the conversion active material, and the electroactive selenium in the conversion active material is present at between 5 and 15 mass percent relative to the electroactive sulfur.

2. The batery cathode of claim 1, wherein the sum of the titanium disulfide and the conversion active material comprise at least 70% of the mass of the cathode film, or at least 75%, or at least 80%. or at least 85%, or at least 90% of the mass of the cathode film.

3. The batery cathode of claim 1 or 2, characterized in that the cathode film has an areal loading of at least 3 mg / cm2, or at least 3.5 mg / cm2, at least 4 mg / cm2, or at least 4.5 mg / cm2, or at least 5 mg / cm2, or at least 5.5 mg / cm2, or at least 6 mg / cm2, or at least 6.5 mg / cm2, or at least 7 mg / cm2, or at least 7.5 mg / cm2, or at least 8 mg / cm2.

4. The batery cathode of any one of claims 1 to 3, wherein the titanium disulfide is present at between 5 and 20 mass percent, or between 5 and 15 mass percent, or between 6 and 12 mass percent, or between 5 and 10 mass percent, or between 7.5 and 16 mass percent, or between 12 and 18 mass percent, or between 8 and 13 mass percent relative to the conversion active material.

5. The batery cathode of any one of claims 1 to 4, wherein the electroactive selenium is present at between 5 and 10 mass percent, or between 10 and 15 mass percent, or between 6 and 12 mass percent, or between 7 and 14 mass percent, or between 8 and 13 mass percent, or between 5 and 12 mass percent relative to the electroactive sulfur.

6. The batery cathode of any one of claims 1 to 5, wherein the titanium disulfide is present at between 5 and 20 mass percent, or between 5 and 15 mass percent, or between 6 and 12 mass percent, or between 5 and 10 mass percent, or between 7.5 and 16 mass percent, or between 12 and 18 mass percent, or between 8 and 13 mass percent relative to the conversion active material, and wherein the electroactive selenium is present at between 5 and 10 mass percent, or between 10 and 15 mass percent, or between 6 and 12 mass percent, or between 7 and 14 mass percent, or between 8 and 13 mass percent, or between 5 and 12 mass percent relative to the electroactive sulfur.

7. A battery comprising the cathode of any one of claims 1 to 6, wherein a ratio of electrolyte volume in the batten’ to the mass of conversion active material in the cathode is less than 3.5 pL / mg. less than 3.3 pL / mg, less than 3.2 pL / mg, less than 3.0 mL / mg, or less than 2.8 mL / mg, or less than 2.7 mL / mg, or less than 2.6 mL / mg, or less than 2.5 mL / mg, or less than 2.4 mL / mg, or less than 2.2 mL / mg, or less than 2. 1 mL / mg, or less than 2.0 mL / mg.

8. A battery cathode comprising: a cathode film adhered to a current collector, the cathode film comprising a mixture of titanium disulfide and a conversion active material, wherein: the conversion active material comprises a mixture of electroactive selenium and electroactive sulfur, the titanium disulfide is present in the cathode at between 25 and 55 mass percent relative to the conversion active material, and the electroactive selenium in the conversion active material is present at between 5 and 15 mass percent relative to the electroactive sulfur.

9. The battery cathode of claim 8, wherein the sum of the titanium disulfide and the conversion active material comprise at least 70% of the mass of the cathode film, or at least 75%, or at least 80%. or at least 85%, or at least 90% of the mass of the cathode film.

10. The battery cathode of claim 8 or 9, characterized in that the cathode film has an areal loading of at least 3 mg / cm2. or at least 3.5 mg / cm2. at least 4 mg / cm2, or at least 4.5 mg / cm2, or at least 5 mg / cm2, or at least 5.5 mg / cm2, or at least 6 mg / cm2, or at least 6.5 mg / cm2, or at least 7 mg / cm2, or at least 7.5 mg / cm2, or at least 8 mg / cm2.

11. The battery cathode of any one of claims 8 to 10, wherein the titanium disulfide is present at between 30 and 55 mass percent, or between 35 and 50 mass percent, or between 40 and 55 mass percent, or between 25 and 40 mass percent, or between 30 and 50 mass percent, or between 30 and 45 mass percent relative to the conversion active material.

12. The battery cathode of any one of claims 8 to 11, wherein the electroactive selenium is present at between 5 and 10 mass percent, or between 10 and 15 mass percent, or between 6 and 12 mass percent, or between 7 and 14 mass percent, or between 8 and 13 mass percent, or between 5 and 12 mass percent relative to the electroactive sulfur.

13. The battery' cathode of any one of claims 8 to 12, wherein the titanium disulfide is present at between 30 and 55 mass percent, or between 35 and 50 mass percent, or between 40 and 55 mass percent, or between 25 and 40 mass percent, or between 30 and 50 mass percent, or between 30 and 45 mass percent relative to the conversion active material, and wherein the electroactive selenium ispresent at between 5 and 10 mass percent, or between 10 and 15 mass percent, or between 6 and 12 mass percent, or between 7 and 14 mass percent, or between 8 and 13 mass percent, or between 5 and 12 mass percent relative to the electroactive sulfur.

14. A battery comprising the cathode of any one of claims 8 to 13, wherein a ratio of electrolyte volume in the battery to the mass of conversion active material in the cathode is less than 3.5 pL / mg, less than 3.3 pL / mg, less than 3.2 pL / mg, less than 3.0 mL / mg. or less than 2.8 mL / mg, or less than 2.7 mL / mg, or less than 2.6 mL / mg. or less than 2.5 mL / mg, or less than 2.4 mL / mg. or less than 2.2 mL / mg, or less than 2. 1 mL / mg, or less than 2.0 mL / mg.

15. A cathode active material layer comprising: a metal chalcogen selected from the group consisting of TiSz, M0S2, MoeSs, VS2, TiSe2, TiTe2, VSe2, MoSe2. MoTe2, WS2, WTe2. WSe2, and combinations thereof; an electroactive sulfur conversion cathode material; and an electroactive selenium conversion cathode material, wherein the cathode active material layer includes the metal chalcogen in a weight ratio (w / w) of between 5% and 75%, the electroactive sulfur conversion cathode material in a weight ratio (w / w) of between 15% and 75%, and the electroactive selenium conversion cathode material in a weight ratio (w / w) of between 2% and 25%.

16. A method of making a cathode active material layer, the method comprising the following steps: a) mixing and optionally milling a metal chalcogen powder, an electroactive sulfur conversion cathode material powder, and an electroactive selenium conversion cathode material powder to form a powder mixture, wherein the metal chalcogen powder is composed of a metal chalcogen selected from the group consisting of TiS2. M0S2, MoeSs, VS2, TiSe2, TiTe2, VSe2, MoSe2, MoTe2, WS2, WTe2, WSe2, and combinations thereof, wherein the electroactive sulfur conversion cathode material powder is composed of an electroactive sulfur conversion cathode material, wherein the electroactive selenium conversion cathode material powder is composed of an electroactive selenium conversion cathode material; b) casting a slurry to form a slurry layer, wherein the slurry includes the powder mixture and a solvent; and c) drying the slurry layer to form the cathode active material layer, wherein the cathode active material layer includes the metal chalcogen in a w eight ratio (w / w) of between 5% and 75%. the electroactive sulfur conversion cathode material in a weight ratio (w / w) ofbetween 15% and 75%, and the electroactive selenium conversion cathode material in a weight ratio (w / w) of between 2% and 25%.

17. The method of the immediately preceding claim, wherein step a) includes milling.

18. The method of claim 16 or 17, wherein the casting of step b) includes casting the slurry atop a current collector, thereby forming the cathode active material layer atop the current collector.

19. The method of any one of claims 16 to the immediately preceding claim, wherein the current collector is a coated metal foil.

20. The method of the immediately preceding claim, wherein the coated metal foil has a carbon coating and / or a plastic coating.

21. The method of claim 19 or 20, wherein the coated metal foil is composed of a metal selected from the group consisting of aluminum, nickel, copper, and combinations thereof.

22. The method of any one of claims 16 to the immediately preceding claim, wherein the slurry is free of N-methyl-2-pyrrolidone.

23. The method of any one of claims 16 to the immediately preceding claim, wherein the solvent comprises an alcohol.

24. The method of the immediately preceding claim, wherein the alcohol is selected from the group consisting of ethanol, propanol such as 1 -propanol, butanol such as 1 -butanol, diacetone alcohol, and combinations thereof.

25. The method of any one of claims 16 to the immediately preceding claim, wherein the dry ing of step c) is a two-stage drying comprising a first stage and a second stage, wherein the drying conditions are different between the first stage and the second stage.

26. The method of the immediately preceding claim, wherein the drying conditions of the first stage produce less evaporation than the dry ing conditions of the second stage.

27. The method of claim 25 or 26, wherein the drying conditions of the first stage include covering the layer of the sluny' to reduce evaporation.

28. The method of any one of claims 25 to the immediately preceding claim, wherein the dry ing conditions of the first stage include a first drying temperature that is lower than a second drying temperature of second stage.

29. The method of any one of claims 25 to the immediately preceding claim, wherein the drying conditions of the second stage include flowing a cooling fluid over a surface of the layer of the slurry to enhance and / or control evaporation.

30. The method of any one of claims 25 to the immediately preceding claim, wherein the dry ing conditions of the second stage include reducing pressure to a second pressure value that is less than atmospheric pressure (i.e. , less than 1 atm) and greater than 0.5 atm.

31. The batery cathode, the cathode active material layer, or the method of any one of the preceding claims, wherein at least a portion of the electroactive sulfur or the electroactive sulfur conversion cathode material is present or introduced as Ss.

32. The batten cathode, the cathode active material layer, or the method of any one of the preceding claims, wherein at least a portion of the electroactive sulfur or the electroactive sulfur conversion cathode material is present or introduced as SeS2.

33. The batery cathode, the cathode active material layer, or the method of any one of the preceding claims, wherein at least a portion of the electroactive sulfur or the electroactive sulfur conversion cathode material is present or introduced as lithium sulfide.

34. The batery cathode, the cathode active material layer, or the method of any one of the preceding claims, wherein the electroactive sulfur or the electroactive sulfur conversion cathode material is present or introduced as SeS2.

35. The cathode active material layer or method of any one of the preceding claims, wherein the cathode film or the cathode active material layer has a thickness of between 50 pm and 500 pm.

36. The batery cathode, the cathode active material layer, or the method of any one of the preceding claims, wherein the cathode film or the cathode active material layer further comprises a conductive binder that is either: i) a conductive matrix; or ii) a non-conductive matrix having conductive particles distributed throughout.

37. The battery cathode, the cathode active material layer, or the method of the immediately preceding claim, wherein the cathode film or the cathode active material layer includes the conductive binder in a weight ratio (w / w) of between 5% and 25%.

38. The batery' cathode, the cathode active material layer, or the method of claim 36 or 37, wherein the conductive binder is the conductive matrix.

39. The batery cathode, the cathode active material layer, or the method of claim 36 or 37, wherein the conductive binder includes the non-conductive matrix having conductive particles distributed throughout.

40. The batery cathode, the cathode active material layer, or the method of the immediately preceding claim, wherein the cathode film or the cathode active material layer includes the conductive particles in a weight ratio (w / w) of between 2% and 22% and the non-conductive matrix in a weight ratio (w / w) of between 3% and 23%.

41. The batery' cathode, the cathode active material layer, or the method of claim 39 or 40, wherein the conductive particles include carbon black.

42. The batery cathode, the cathode active material layer, or the method of any one of claims 39 to the immediately preceding claim, wherein the non-conductive matrix is a polymeric binder.

43. The batery cathode, the cathode active material layer, or the method of the immediately preceding claim, wherein the polymeric binder is selected from the group consisting of a polyfacrylic acid), poly(vinylidene fluoride) (PVDF), a cellulose derivative (e.g., carboxymethyl cellulose), styrene-butadiene rubber (SBR), and combinations thereof.

44. The batery cathode, the cathode active material layer, or the method of the immediately preceding claim, wherein the polymeric binder is a salt of polyiaciylic acid).

45. The batery cathode, the cathode active material layer, or the method of the immediately preceding claim, wherein the salt of poly(acrylic acid) is sodium poly(acrylic acid).

46. The cathode active material layer of or made by the method of any one of claims 15 to the immediately preceding claim, characterized in that a batery' constructed with a cathode composed of the cathode active material layer deposited at an areal loading of at least 3 mg elemental chalcogen per cm2in combination with a lithium metal anode, and a liquid electrolyte, is operable at an electrolyte to chalcogen ratio of 6 or lower and a 3C discharge rate (e.g., a 3C pulse at 30s pulse) with an average baten' cycle life of at least 30 cycles.

47. The cathode active material layer of or made by the method of any one of claims 15 to the immediately preceding claim, wherein the cathode active material layer has a test cell batery cycle life that is at least 10% greater than a comparison test cell battery cycle life for a comparison cathode active material layer that replaces the electroactive selenium conversion cathode material with an equal weight of the electroactive sulfur conversion cathode material and is otherwise identical to the cathode active material layer, wherein the electroactive sulfur conversion cathode material is selenium free.

48. The cathode active material layer of or made by the method of any one of claims 15 to the immediately preceding claim, wherein the cathode active material layer has a test cell baten' power that is at least 10% greater than a comparison test cell batery power for a comparison cathode active material layer that replaces the electroactive selenium conversion cathode material with an equal weight of the electroactive sulfur conversion cathode material and is otherwise identical to the cathode active material layer, wherein the electroactive sulfur conversion cathode material is selenium free.

49. The cathode active material layer of or made by the method of any one of claims 15 to the immediately preceding claim, wherein the cathode active material layer is operable at a ratio of electrolyte to (sulfur plus selenium) (in pL / mg) of 6 or lower, including but not limited to, 5 or lower or 4 or lower.

50. The cathode active material layer of or made by the method of any one of claims 15 to the immediately preceding claim, wherein the cathode active material layer is operable at anelectroactive sulfur conversion cathode material plus electroactive selenium conversion cathode material loading of 3 mg / cm2or greater.

51. The cathode active material layer of or made by the method of any one of claims 15 to the immediately preceding claim, wherein the cathode active material layer includes the metal chalcogen in a weight ratio (w / w) of at least 5%, at least 10%, at least 15%, at least 20%, at least 25%, at least 30%, at least 35%, at least 40%, at least 45%, or at least 50% and at most 75%, at most 70%, at most 65%. at most 60%. at most 55%, at most 50%, at most 45%, at most 40%, at most 35%, at most 30%, or at most 25%.

52. The cathode active material layer of or made by the method of any one of claims 15 to the immediately preceding claim, wherein the cathode active material layer includes the electroactive sulfur conversion cathode material in a weight ratio (w / w) of at least 15%, at least 20%, at least 25%, at least 30%, at least 35%, at least 40%, at least 45%, or at least 50% and at most 75%, at most 70%, at most 65%, at most 60%, at most 55%, at most 50%, at most 45%, at most 40%, at most 35%, at most 30%, or at most 25%.

53. The cathode active material layer of or made by the method of any one of claims 15 to the immediately preceding claim, wherein the cathode active material layer includes the electroactive selenium conversion cathode material in a weight ratio (w / w) of at least 2%, at least 3%, at least 4%, at least 5%, at least 7%, at least 10%, or at least 15% and at most 25%, at most 22%, at most 20%, at most 17%, at most 15%, at most 12%, at most 10%. at most 8%, or at most 5%.

54. The cathode active material layer of or made by the method of any one of claims 15 to the immediately preceding claim, wherein the cathode active material has an as-deposited porosity of between 55% and 85%, between 60% and 78%, or between 65% and 75%, as measured by Hg porosimetry or He pycnometr .

55. A cathode made by the method of any one of claims 18 to the immediately preceding claim.

56. A cathode comprising the cathode active material layer of or made by the method of any one of claims 15 to 53 disposed atop a current collector.

57. A battery comprising the cathode of claim 55 or 56, an anode, and an electrolyte in contact wi th the cathode and the anode.

58. A method of improving a method of making a cathode active material, the method comprising: replacing between 5% and 50% of an electroactive sulfur conversion cathode material with an electroactive selenium conversion cathode material.

59. A battery comprising the cathode active material layer of claim 15 and a substantially solid electrolyte.

60. A battery comprising the cathode active material layer of claim 15, wherein one or more of the electrodes of the battery is molten.

61. A battery comprising the cathode active material layer of claim 15 and a hybrid electrolyte.

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