Positive electrode compositions including blends of intercalation materials for use in lithium-sulfur batteries - Patent Application 20070229633

Abstract

An exemplary positive electrode material includes a mixture of an electroactive sulfur material (e.g., S8) and a blended non-sulfur electroactive material including two or more non-sulfur electroactive materials. The blended non-sulfur electroactive materials are selected such that the discharge voltage profile of the blend of intercalation materials (considered separately from the sulfur electroactive materials) has a discharge voltage profile that has substantial overlap with the discharge voltage profile of the sulfur electroactive materials. For example, in a typical ether electrolyte commonly used in sulfur batteries, the discharge voltage profile of the S8→Li2S conversion has multiple plateaus (e.g., two plateaus). This is because sulfur is converted in multiple steps to soluble / intermediate polysulfides (PS), followed by progression to solid or semi-solid products (e.g., Li2S2 / Li2S).

Description

[Background technology]

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS This application claims priority to and the benefit of U.S. Provisional Patent Application No. 63 / 331,507, filed April 15, 2022, the entire contents of which are incorporated herein by reference.

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

[0003] Sulfur is a low-cost, high specific energy material available as a by-product of the oil and gas industry. The use of sulfur in lithium battery cathodes has been under development for some time but has not yet reached widespread commercial use. The use of sulfur could eliminate the need for cobalt and nickel in lithium batteries. Cobalt is expensive and toxic, and its mining in certain regions can result in loose regulation and unethical practices. Nickel has high energy density, but there are concerns about long-term nickel supplies, which, for example, have recently driven Tesla's move away from nickel-containing batteries.

[0004] Producing sulfur cathodes capable of commercial performance levels is challenging because, for example, sulfur by-products degrade performance and limit cycle life, and the low density monofunctional material negatively impacts energy and power. There remains a need for low-cost lithium-ion batteries with improved energy density and long cycle life.

[0005] An additional challenge for sulfur cathodes stems from the complexity of the sulfur conversion chemistry. The conversion of sulfur (e.g., S8) to lithium sulfide (e.g., Li2S) is a complex, multi-step process involving numerous intermediate species with varying chemical properties and solubilities. This complexity makes it difficult for sulfur cathodes to achieve high discharge or charge rates due to kinetic limitations of the multi-step chemical conversions, resulting in performance and efficiency variations depending on the battery's state of charge. Both of these properties pose challenges for demanding applications such as the consumer automotive market. Summary of the Invention

[0006] The present disclosure provides, among other things, a cathode material and a battery including the same. The cathode material can include at least one electroactive sulfur material and two or more non-sulfur active materials (e.g., a blend of two or more non-sulfur active materials).

[0007] In some aspects, the present disclosure relates to a cathode material comprising a mixture of a first active material comprising at least one electroactive sulfur material and a non-sulfur second active material comprising a blend of two or more non-sulfur electroactive materials (e.g., metal chalcogenides, transition metal oxides, and / or polyanionic compounds). The blend may be selected such that the discharge voltage profile of the blend has a voltage plateau that approximates the discharge voltage profile of the at least one electroactive sulfur material. In some embodiments, the cathode material is at least 10% by weight of the non-sulfur electroactive material (e.g., metal chalcogenides) relative to the sulfur, e.g., 10-90% by weight of the non-sulfur electroactive material (e.g., 30-70% by weight of the non-sulfur electroactive material).

[0008] In some embodiments, the voltage profiles of the first and second active materials are measured separately under similar electrochemical conditions to assess whether they approximate each other.

[0009] In some embodiments, a blend of two or more non-sulfur electroactive materials has a discharge voltage profile characterized by a discharge voltage attributable to the non-sulfur materials of the blend being within 10% (e.g., within 5%, within 3%, or within 1%) of the sulfur discharge voltage attributable to at least one sulfur electroactive material for at least 50% of the total discharge (e.g., at least 60%, at least 75%, or at least 80% of the total discharge).

[0010] In some embodiments, the at least one electroactive sulfur material comprises at least one of the following: (i) sulfur in the form of an S8 cyclic octaatomic molecule, (ii) sulfur in the form of lithium sulfide (e.g., Li2S2 and / or Li2S), (iii) sulfur in the form of an electroactive organosulfur compound, and (iv) sulfur in the form of an electroactive sulfur-containing polymer.

[0011] In some embodiments, each of the two or more non-sulfur electroactive materials (e.g., intercalation materials) has a unique discharge voltage profile with a voltage plateau that is different from the voltage plateau of the unique discharge voltage profile of the other of the two or more non-sulfur electroactive materials. In some embodiments, the blend of the two or more non-sulfur electroactive materials includes one or more chalcogenides (e.g., each of the two or more non-sulfur electroactive materials is a chalcogenide) (e.g., includes one or more metal chalcogenides (e.g., one or more metal sulfides)). In some embodiments, each of the two or more non-sulfur electroactive materials (i) has a different crystal structure (e.g., layered, spinel, olivine, tavorite), (ii) has a different composition, or (iii) has both (i) and (ii).

[0012] In some embodiments, the non-sulfur second active material has a discharge voltage profile with two plateaus. In some embodiments, one of the two plateaus corresponds to the conversion of soluble / intermediate polysulfides and the other of the two plateaus corresponds to the solid or semi-solid product(s). In some embodiments, the non-sulfur second active material has a discharge voltage profile that approximates the sulfur to lithium sulfide (e.g., S→LiS) discharge voltage profile. In some embodiments, the discharge voltage profile with two plateaus is about 2.2 to about 2.4 (V vs. Li / Li + ), and a first plateau in the range of about 2.0 to about 2.2 (V vs. Li / Li + ) and a second plateau in the range

[0013] In some embodiments, the at least one electroactive sulfur material has a discharge voltage profile with two plateaus. In some embodiments, one of the two plateaus corresponds to the conversion of soluble / intermediate polysulfides and the other of the two plateaus corresponds to the solid or semi-solid product(s). In some embodiments, the non-sulfur second active material has a discharge voltage profile that approximates the sulfur to lithium sulfide (e.g., S→LiS) discharge voltage profile. In some embodiments, the discharge voltage profile with two plateaus is between about 2.2 and about 2.4 (V vs. Li / Li + ), and a first plateau in the range of about 2.0 to about 2.2 (V vs. Li / Li + ) and a second plateau in the range

[0014] In some aspects, the present disclosure relates to a cathode material comprising an electroactive sulfur material and two or more non-sulfur electroactive materials (e.g., a blend of two or more non-sulfur electroactive materials). In some embodiments, the two or more electroactive materials together have a discharge voltage profile with at least two distinct voltage plateaus. The electroactive sulfur material comprises at least one of the following (i)-(iv): (i) sulfur in the form of an S8 cyclic octaatomic molecule, (ii) sulfur in the form of lithium sulfide (e.g., Li2S2 and / or Li2S), (iii) sulfur in the form of an electroactive organosulfur compound, and (iv) sulfur in the form of an electroactive sulfur-containing polymer. For example, the electroactive sulfur material may comprise at least one of (i) sulfur (S8) and (ii) lithium sulfide (e.g., Li2S2 and / or Li2S) (e.g., both). The cathode material may comprise another electroactive sulfur material. The two or more non-sulfur electroactive materials may be intercalation materials (e.g., lithium intercalation materials).

[0015] In some embodiments, the two or more non-sulfur electroactive materials collectively have a discharge voltage profile that corresponds to the discharge voltage profile of sulfur (e.g., each of the two or more electroactive materials has a discharge voltage profile with a voltage plateau that corresponds to the voltage plateau of the discharge voltage profile of sulfur). In some embodiments, each of the two or more non-sulfur electroactive materials has a unique discharge voltage profile with a voltage plateau that is different from the voltage plateau of the unique discharge voltage profile of another of the two or more non-sulfur electroactive materials. In some embodiments, the voltage plateau of the unique discharge voltage profile of each of the two or more electroactive materials is within 10% (e.g., within 5%, within 3%, or within 1%) of the corresponding voltage plateau of the discharge voltage profile of sulfur.

[0016] In some embodiments, the positive electrode material comprises a core-shell structure. In some embodiments, the core-shell structure comprises a core, each having a surrounding shell, the core comprising an electroactive sulfur material (e.g., S8, Li2S2, and / or Li2S), and the shell comprising at least one of two or more non-sulfur electroactive materials (e.g., one or more metal chalcogenides). In some embodiments, the core-shell structure has an average core diameter in the range of 50-300 nm and an average shell thickness in the thickness range of 1-20 nm (e.g., a thickness of 10 nm or less). In some embodiments, the core-shell structure has at least 10% by weight of non-sulfur electroactive material (e.g., metal chalcogenide) relative to sulfur (e.g., 10-90% by weight of non-sulfur, non-carbon electroactive material (e.g., 30-70% by weight of non-sulfur, non-carbon electroactive material)).

[0017] In some embodiments, the battery (e.g., secondary battery) includes (i) a positive electrode including a positive electrode material disclosed herein (e.g., in the Summary section) and (ii) an electrolyte (e.g., a solid-state electrolyte (SSE)) in contact with the positive electrode. In some embodiments, the battery further includes a negative electrode. In some embodiments, the negative electrode is a protected lithium metal negative electrode. In some embodiments, the battery further includes a protected current collector.

[0018] In some aspects, the present disclosure relates to a method of operating a lithium-sulfur battery. The lithium-sulfur battery can include a positive electrode including (i) sulfur or lithium sulfide (e.g., Li2S2 and / or Li2S) (e.g., both sulfur and lithium sulfide), (ii) a first non-sulfur electroactive material (e.g., a first intercalation material), and (iii) a second non-sulfur electroactive material (e.g., a second intercalation material) different from the first non-sulfur electroactive material. The method can include discharging the battery. Discharging the battery can include inserting (e.g., intercalating) lithium into the first non-sulfur electroactive material at a first voltage while at least partially converting (e.g., S8 → Li2S) at least a portion of the sulfur or lithium sulfide. Discharging the battery may further include subsequently inserting (e.g., intercalating) lithium into a second non-sulfur electroactive material at a second voltage different from the first voltage while at least partially (e.g., further) converting at least a portion of the sulfur of the lithium sulfide (e.g., S→LiS). Completing both of the simultaneous insertion steps may complete the discharge of the battery.

[0019] In some embodiments, the method includes discharging the battery and then charging the battery. Charging the battery can include simultaneously (i) removing lithium from the first non-sulfur electroactive material, (ii) removing lithium from the second non-sulfur electroactive material, and (iii) at least partially converting at least a portion of the sulfur or lithium sulfide (e.g., Li2S→S8) at a third voltage (e.g., different from the first voltage and the second voltage).

[0020] In some aspects, the disclosure relates to a method of operating a battery. The battery may include a positive electrode including (i) a sulfur electroactive material, (ii) a first non-sulfur electroactive material (e.g., a first intercalation material), and (iii) a second non-sulfur electroactive material (e.g., a second intercalation material) different from the first non-sulfur electroactive material. The method may include discharging the battery. Discharging the battery may include inserting (e.g., intercalating) ions (e.g., lithium) into the first non-sulfur electroactive material at a first voltage while at least partially converting at least a portion of the sulfur electroactive material (e.g., lithium sulfide) at a first voltage. Discharging the battery may further include subsequently inserting (e.g., intercalating) ions (e.g., lithium) into the second non-sulfur electroactive material at a second voltage different from the first voltage while at least partially (e.g., further) converting (e.g., S8→Li2S) at least a portion of the sulfur electroactive material (e.g., lithium sulfide). By completing both simultaneous insertion steps, the battery can be completely discharged.

[0021] In some embodiments, the method includes discharging the battery and then charging the battery. Charging the battery may include simultaneously (i) removing ions from the first non-sulfur electroactive material, (ii) removing ions from the second non-sulfur electroactive material, and (iii) at least partially converting (e.g., Li2S→S8) at least a portion of the sulfur electroactive material (e.g., sulfur or lithium sulfide) at a third voltage (e.g., different from the first voltage and the second voltage).

[0022] In some aspects, the present disclosure relates to a positive electrode material that includes at least one electroactive sulfur material, for example, including at least one of (i) sulfur (S8) and (ii) lithium sulfide (e.g., Li2S2 and / or Li2S), and two or more intercalation materials (e.g., lithium intercalation materials). In some embodiments, each of the two or more intercalation materials has a unique discharge voltage profile with a voltage plateau that is different from the voltage plateaus of the unique discharge voltage profiles of the other of the two or more intercalation materials. In some embodiments, the discharge voltage profile of the blend approximates the discharge voltage profile of at least one electroactive sulfur material.

[0023] In some aspects, the present disclosure relates to a solid-state sulfur battery. The battery may include an anode, a solid electrolyte, and a cathode. The cathode may include a first active material including at least one electroactive sulfur material. The cathode may further include one or more non-sulfur electroactive materials (e.g., metal chalcogenides, transition metal oxides, and / or polyanionic compounds). In some embodiments, the discharge voltage profile of the one or more non-sulfur electroactive materials approximates at least a portion of the discharge voltage profile of the at least one electroactive sulfur material (e.g., where the cathode material is at least 10% by weight of the non-sulfur electroactive material (e.g., metal chalcogenides) relative to sulfur (e.g., 10-90% by weight of the non-sulfur electroactive material (e.g., 30-70% by weight of the non-sulfur electroactive material)).

[0024] In some embodiments, the one or more non-sulfur electroactive materials are a blend of two or more non-sulfur electroactive materials. In some embodiments, at least a portion of the discharge voltage profile includes two or more distinct portions, each of the two or more distinct portions corresponding to one of the two or more non-sulfur electroactive materials.

[0025] In some embodiments, the one or more non-sulfur electroactive materials include (eg, are) mixed metal sulfides.

[0026] In some embodiments, at least a portion of the discharge voltage profile is in a voltage range of 2.5 V to 1.9 V (e.g., 2.3 V to 2.1 V) and / or an SoC range of 90% to 30% (e.g., 90% to 60%). In some embodiments, at least a portion of the discharge voltage profile is a sloped portion of the discharge voltage profile (e.g., moderately and / or monotonically sloping).

[0027] In some embodiments, the present disclosure relates to a cathode material comprising a mixture of at least one electroactive sulfur material and at least one non-sulfur electroactive material that is a mixed metal chalcogenide, where the discharge voltage profile of the at least one non-sulfur electroactive material corresponds to the discharge voltage profile of the at least one sulfur electroactive material.

[0028] In some embodiments, the at least one non-sulfur electroactive material comprises two non-sulfur electroactive materials (two mixed metal chalcogenides). In some embodiments, the at least one non-sulfur electroactive material is a single non-sulfur electroactive material (single mixed metal chalcogenide).

[0029] In some embodiments, the mixed metal chalcogenide is a mixed metal sulfide (eg, the mixed metal chalcogenide is a mixed metal sulfide where the at least one non-sulfur electroactive material includes two non-sulfur electroactive materials).

[0030] In some embodiments, the discharge voltage profile of the at least one non-sulfur electroactive material has a voltage plateau that approximates the voltage plateau of the at least one sulfur electroactive material. In some embodiments, the at least one non-sulfur electroactive material has a discharge voltage profile characterized in that for at least 50% of the total discharge (e.g., at least 60%, at least 75%, or at least 80% of the total discharge), the discharge voltage attributable to the at least one non-sulfur material is within 10% (e.g., within 5%, within 3%, or within 1%) of the sulfur discharge voltage attributable to the at least one sulfur electroactive material.

[0031] In some embodiments, the at least one electroactive sulfur material comprises at least one of the following: (i) sulfur in the form of an S8 cyclic octaatomic molecule, (ii) sulfur in the form of lithium sulfide (e.g., Li2S2 and / or Li2S), (iii) sulfur in the form of an electroactive organosulfur compound, and (iv) sulfur in the form of an electroactive sulfur-containing polymer.

[0032] In some embodiments, the discharge voltage profile of the at least one non-sulfur electroactive material has two voltage plateaus, one of which corresponds to the conversion of soluble / intermediate polysulfides and the other of which corresponds to the conversion of solid or semi-solid product(s). In some embodiments, the discharge voltage profile of the at least one non-sulfur electroactive material has two voltage plateaus, the first of which corresponds to the conversion of soluble / intermediate polysulfides and the second ... + ), and the second plateau is in the range of about 2.0 to about 2.2 (V vs. Li / Li + In some embodiments, the at least one non-sulfur electroactive material has a discharge voltage profile that approximates the discharge voltage profile of sulfur to lithium sulfide (e.g., S→LiS).

[0033] In some embodiments, the positive electrode material is at least 10% by weight non-sulfur electroactive material (e.g., mixed metal chalcogenide) relative to sulfur (e.g., 10-90% by weight non-sulfur electroactive material (e.g., 30-70% by weight non-sulfur electroactive material)).

[0034] The battery may include (i) a positive electrode including a positive electrode material, and (ii) an electrolyte (e.g., a solid-state electrolyte (SSE)) in contact with the positive electrode. In some embodiments, the battery further includes a negative electrode. In some embodiments, the negative electrode is a protected lithium metal negative electrode. In some embodiments, the battery further includes a protected current collector.

[0035] The positive electrode material disclosed herein can be included in a positive electrode. The positive electrode can be in an electrochemical cell. The electrochemical cell can be a battery. The battery can be a primary battery, a low cycle life battery, or a secondary battery. The battery can be, for example, a sulfur battery, such as a lithium-sulfur battery.

[0036] Any two or more of the features described herein, including in this Summary section, may be combined to form embodiments of the present disclosure, whether or not specifically and explicitly described in a separate combination herein.

[0037] The present teachings described herein will be more fully understood from the following description of various exemplary embodiments when read in conjunction with the accompanying drawings. It should be understood that the drawings described below are for illustrative purposes only and are not intended to limit the scope of the present teachings in any manner. The foregoing and other objects, aspects, features, and advantages of the present disclosure will become more apparent and can be better understood by referring to the following description in conjunction with the accompanying drawings. [Brief description of the drawings]

[0038] [Figure 1] FIG. 1 is a schematic diagram showing an exemplary discharge profile of a lithium-sulfur battery operating with a liquid electrolyte.

[0039] [Diagram 2] FIG. 1 illustrates a cross-section of an electrochemical cell according to certain embodiments of the present disclosure.

[0040] [Diagram 3] FIG. 1 illustrates a cylindrical battery embodying the concepts of the present disclosure. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0041] definition About / Approximately: The term "about" or "approximately" when used herein with respect to a value refers to a value that is similar to the value referred to in the context. In general, a person skilled in the art who understands the context will recognize the appropriate degree of variation that is encompassed by "about" or "approximately" in that context. For example, in some embodiments, as provided herein, the term "about" can encompass a range of values ​​that is within 25%, 20%, 19%, 18%, 17%, 16%, 15%, 14%, 13%, 12%, 11%, 10%, 9%, 8%, 7%, 6%, 5%, 4%, 3%, 2%, 1%, or less of the value referred to.

[0042] Intercalation Material: As used herein, the term "intercalation material" refers to a material in which another substance or species (e.g., ions, metal ions) is reversibly inserted or contained within the vacancies, interstitial sites, interstices, or between the layers of the intercalation material, or combinations thereof.

[0043] Electroactive Material: As used herein, the term "electroactive material" refers to a composition that includes one or more components that can change their oxidation state in the charge transfer step of an electrochemical reaction.

[0044] Lithium Alloy: As used herein, the term lithium alloy refers to a material formed by the combination of lithium with other metal or metalloid elements. Non-limiting examples include lithium silicon compounds and alloys of lithium with metals such as sodium, cesium, indium, aluminum, zinc, and silver.

[0045] Nanoparticles, Nanostructures, Nanomaterials: As used herein, these terms may be used interchangeably to refer to particles of nanoscale dimensions or materials having nanoscale structures. Nanoparticles can have virtually any shape or configuration, such as tubes, wires, laminates, sheets, lattices, boxes, cores and shells, or combinations thereof.

[0046] Substantially: As used herein, the term "substantially" refers to a qualitative state in which a desired feature or characteristic is exhibited to a complete or nearly complete degree or extent.

[0047] The present disclosure seeks, inter alia, to improve the rate capability and state of charge (SoC) dependent performance characteristics that have previously limited the commercial application of lithium-sulfur batteries. A positive electrode for lithium-sulfur batteries is presented herein. The positive electrode comprises a mixture of i) electroactive sulfur (e.g., S8) and ii) a blended electroactive material comprising two or more non-sulfur electroactive materials, the blended non-sulfur electroactive materials being selected such that the discharge voltage profile of the blend of intercalation materials (considered separate from the sulfur electroactive materials) has a discharge voltage profile that has substantial overlap with the discharge voltage profile of the sulfur electroactive materials. For example, in a typical ether electrolyte commonly used in sulfur batteries, the discharge voltage profile of S8→Li2S conversion has multiple plateaus (e.g., two plateaus). This is because sulfur undergoes a multi-step conversion to soluble / intermediate polysulfides (PS), followed by progression to solid or semi-solid products (e.g., Li2S2 / Li2S).

[0048] By matching this discharge profile with a provided blend of non-sulfur electroactive materials, one or more rate and efficiency characteristics of the sulfur cathode can be improved, for example, throughout the battery discharge process. For example, without wishing to be bound by any particular theory, the intercalation compound can provide a solid ion transport pathway within the electrode (e.g., cathode) by percolation through the intercalation material particles. Under conditions where the solid end products of sulfur charge / discharge clog the pore structure of the electrode (e.g., cathode), the intercalation material can provide an alternative pathway for ion transport. Furthermore, the resistance of the electrolyte and the kinetics of the electrochemical conversion of sulfur vary with the state of charge of the electrode (e.g., cathode). Such an alternative pathway can, for example, allow the electrode (e.g., cathode) in an electrochemical cell (e.g., battery) to equilibrate faster and / or achieve higher power. The present disclosure provides an electrode. The electrode includes an intercalation material that provides voltage maintenance under high power pulses across the charge state of the device (e.g., battery), thereby improving the efficiency of the pulse power (e.g., less heat generation and more available energy from the pulse). As the data reveals, the intercalation material included in an electrode (e.g., a positive electrode) that includes a sulfur electroactive material can alter (e.g., improve) the rate capacity of the electrode at different charge states (e.g., both high and low charge states) compared to an otherwise equivalent electrode that does not include the intercalation material, for example, without substantially changing the discharge voltage profile of the electrode. When the high power load of the cell is released, the intercalation material can exit into the sulfur material, and the intercalation material is regenerated for the subsequent high load state. Less heat generation has system-level advantages, allowing, in some embodiments, a reduction in thermal management infrastructure in the battery pack, requiring fewer cells to generate the same power.

[0049] Figure 1 is a schematic diagram showing a typical discharge profile of a lithium-sulfur battery operating in a liquid electrolyte. The discharge (lower red curve) shows two plateaus, beginning at about 2.37 V that is believed to correspond to the conversion of S8 to soluble Li2S8, followed by the reduction of polysulfides (PS) from higher polysulfides to lower polysulfides (S8 2- →S6 2- →S4 2- This is followed by a second plateau at approximately 2.1 V that is believed to correspond to the Li2S2 / Li2S solid or quasi-solid product deposition. Charging the cell follows the reverse PS formation as shown in the upper blue curve.

[0050] Intercalation is a process by which mobile ions or molecules are reversibly incorporated into vacant sites within the crystal lattice of a host network. Intercalation minimizes volume changes and mechanical strains during repeated insertion and extraction of ions during charge and discharge. An intercalation positive electrode includes a solid host network that can store guest ions that are reversibly inserted and removed from the host network.

[0051] Presented herein is a technique for using blends of intercalation active materials (e.g., non-sulfur intercalation materials) and / or non-sulfur conversion active materials, the blends having a discharge voltage profile designed to track the discharge profile of an electroactive sulfur material under similar conditions. In certain embodiments, a blend of two or more intercalation materials is combined with an electroactive sulfur composition (e.g., sulfur in the form of an S8 cyclic octaatomic molecule, sulfur in the form of lithium sulfide (e.g., Li2S2 and / or Li2S), and / or sulfur in the form of an electroactive organosulfur compound or an electroactive sulfur-containing polymer). The blend is selected such that its discharge voltage profile (considered separately from the electroactive sulfur composition) has a voltage plateau that approximates that of the discharge voltage profile of S8→Li2S. For example, the blend of intercalation materials has a discharge voltage profile characterized by two plateaus in liquid electrolyte at approximately the same voltages as the two plateaus of the discharge voltage profile shown in FIG. 1 (e.g., the potential of the first plateau vs. Li / Li + is in the range of about 2.2 to about 2.4 V, and the potential of the second plateau (different from the first) vs. Li / Li + ranges from about 2.0 to about 2.2 V (e.g., when compared using the same electrolyte, since electrolyte composition can affect the discharge voltage profile). In certain embodiments, the distribution of discharge capacity of the blended intercalation material across its multiple discharge voltage plateaus approximates the ratio of capacities observed at the sulfur conversion discharge plateaus.

[0052] One or more non-sulfur electroactive materials can be added to a battery (e.g., a lithium-sulfur battery) (e.g., in the positive electrode) to impart additional capacity to the battery. A blend of electroactive materials can be provided, each of which has a discharge voltage profile that substantially overlaps with the discharge profile characteristic of the electroactive sulfur in the battery to which they are added (i.e., the battery without the blended electroactive material), thereby imparting additional capacity and / or additional rate capacity to the battery. For example, the blended non-sulfur electroactive materials can be characterized by a discharge voltage profile that is within 10% (e.g., within 5%, within 3%, or within 1%) of the sulfur discharge voltage due to the blend material for at least 50% of the total discharge (e.g., of the battery) (e.g., at least 60%, at least 75%, or at least 80% of the total discharge (e.g., of the battery)). The discharge voltage profile of a combination (e.g., blend) of two or more non-sulfur electroactive materials can be obtained experimentally or estimated, for example, through simulation.

[0053] Lithium-sulfur batteries operate by converting between electroactive sulfur in a charged state and lithium metal to lithium sulfide in a discharged state. In certain lithium-sulfur battery systems, this process is characterized by two distinct voltage plateaus during discharge. In certain embodiments, the blended non-sulfur electroactive materials provided can have a discharge voltage profile characterized by a voltage plateau that substantially overlaps with a voltage plateau of the discharge voltage profile of the sulfur electroactive material with which the blend is combined. For example, with reference to FIG. 1, one electroactive material in the non-sulfur blend can have a voltage plateau corresponding to a plateau of about 2.2-2.4 V, and the other electroactive material in the blend can have a voltage plateau corresponding to a plateau of about 2.0-2.2 V (although the exact values ​​may shift somewhat with different electrochemical environments (e.g., electrolytes)).

[0054] A region of the discharge profile of a provided positive electrode (e.g., in a battery) where the discharge voltage is relatively constant when the discharge current is held constant is a voltage plateau. The term plateau does not necessarily imply that there is no change in the discharge potential, but rather that the rate of change of the discharge voltage as a function of state of charge (SoC) is small in a particular region compared to other parts of the discharge profile of the positive electrode (e.g., in a battery). By way of example, FIG. 1 shows an exemplary discharge voltage profile of a typical lithium-sulfur battery discharged at a constant current. Viewing this discharge profile reveals at least four distinct regions. The four distinct regions are an initial region 102 where the battery has a relatively constant discharge voltage of about 2.35 volts, a second region 104 where the discharge voltage has a steep slope that drops from about 2.35 volts to 2.1 volts, followed by a third region 106 where the discharge voltage again exhibits a relatively constant discharge voltage near 2.1 volts, and finally a region 108 characterized by a steep drop in the discharge voltage near the end of discharge. In this type of system, the term plateau has a common meaning and refers to a region (e.g., 102 and 106) where the slope of voltage versus total discharge (or time in the case of constant current discharge) is less than adjacent regions of steeper slope.

[0055] The discharge voltage profile of the battery may or may not have one or more voltage plateaus. For example, in some embodiments, a solid-state sulfur battery has at least a portion of a monotonically sloping discharge voltage profile. The monotonically sloping portion may be relatively long and moderately sloping. Regardless of whether such a discharge voltage profile has a voltage plateau, one or more intercalation materials may be selected that approximate at least a portion of the discharge profile of a battery, such as a solid-state battery (e.g., a solid-state sulfur battery). In some embodiments, a blend of two or more non-sulfur electroactive materials (e.g., intercalation materials) may be included in the cathode material, where each material approximates at least a portion (e.g., a separate portion) of the discharge voltage profile. Such portion(s) of the discharge voltage profile may be within a particular voltage range (e.g., 2.3V-2.1V) and / or within a particular range of SoC (e.g., 90%-60% SoC).

[0056] In some embodiments, the non-sulfur electroactive material (e.g., intercalation material) has a discharge voltage profile that corresponds to (e.g., approximates) the discharge voltage profile of at least one sulfur electroactive material. For example, in some embodiments, the non-sulfur electroactive material has a discharge voltage that corresponds to a voltage plateau in the discharge voltage profile of at least one sulfur electroactive material, or has a discharge voltage profile with a voltage plateau that corresponds to a voltage plateau in the discharge voltage profile of at least one sulfur electroactive material. As another example, in some embodiments, the non-sulfur electroactive material has a discharge voltage profile that corresponds to (e.g., approximates) the discharge voltage profile of at least one sulfur electroactive material, where the discharge voltage of the non-sulfur electroactive material is (i) within 0.3 V (e.g., within 0.2 V, within 0.1 V, or within 0.05 V) and / or (ii) within 10% (e.g., within 5%, within 3%, or within 1%) of the discharge voltage of the at least one sulfur electroactive material for at least a portion of the discharge voltage profile of the at least one sulfur electroactive material. This may be the case, for example, in a solid-state sulfur battery or a liquid battery. The discharge voltage profile of the at least one sulfur electroactive material may be defined, at least in part, by a voltage range and / or an SoC range, which may be, for example, 2.5V to 1.9V, 2.4V to 2.0V, 2.3V to 2.1V, 2.5V to 2.0V, 2.5V to 2.1V, 2.5V to 2.2V, 2.4V to 2.1V, 2.4V to 2.2V, 2.3V to 2.0V, 2.3V to 1.9V, 2.2V to 1.9V, or 2.2V to 2.0V. The SoC range can be, for example, 90%-30% SoC, 90%-40% SoC, 90%-50% SoC, 90%-60% SoC, 90%-70% SoC, 80%-30% SoC, 80%-40% SoC, 80%-50% SoC, 80%-60% SoC, 70%-30% SoC, 70%-40% SoC, 70%-50% SoC, 60%-30% SoC, or 60%-40% SoC.In some embodiments, the discharge voltage or a portion of the discharge voltage profile of at least one sulfur electroactive material to which the discharge voltage profile of the non-sulfur electroactive material corresponds (e.g., approximates) has a slope. For example, the slope may be moderately sloping (e.g., as in certain solid-state sulfur batteries), monotonically sloping, or moderately monotonically sloping.

[0057] During operation of a lithium-sulfur battery including the provided blend of two or more non-sulfur electroactive materials, in addition to the ions / charges respectively stored by the electroactive sulfur, each of the electroactive materials can store or release ions and thus can store or release charges. In some embodiments, a method of operating the battery includes, during discharge, at a first voltage, simultaneously inserting (e.g., intercalating) lithium ions into the first electroactive material while converting at least a portion of the electroactive sulfur. For example, lithium can be inserted into (e.g., intercalated into) the first electroactive material by storing lithium at (e.g., on) the surface of (e.g., on) the first electroactive material or in the bulk of (e.g., in vacancies, interstitial sites, interstices, or between layers of the electroactive material, or some combination thereof). The conversion of the electroactive sulfur in this step may occur along the pathway of S to LiS (the conversion being fully completed (at least to LiS and / or LiS) upon full discharge of the battery, for at least a substantial majority (e.g., at least 80%) of the initial electroactive sulfur present upon full charge). Such simultaneous conversion and intercalation into the first electroactive material may occur at a first voltage plateau (e.g., about 2.2-2.4 V, with reference to FIG. 1) in the discharge voltage profile of the battery.

[0058] In some embodiments, the method of operating the battery includes converting at least a portion of the electroactive sulfur during discharge while simultaneously inserting (e.g., intercalating) lithium into the second electroactive material at a second voltage different from the first voltage. For example, lithium may be inserted into (e.g., intercalated into) the second electroactive material by storing lithium at (e.g., on) the surface of (e.g., on) the second electroactive material or in the bulk of (e.g., in vacancies, interstitial sites, interstices, or between layers of the electroactive material, or some combination thereof). The second voltage may be lower than the first voltage. The conversion of sulfur or lithium sulfide in this step may occur along a pathway from S8 to Li2S, e.g., a pathway later than the first step by the first electroactive material. Such simultaneous conversion and insertion into the second electroactive material may occur at a second voltage plateau in the discharge voltage profile of the battery (e.g., about 2.0-2.2 V, with reference to FIG. 1). A second step with a second electroactive material can occur subsequent to (e.g., after) the first step with the first electroactive material (e.g., as can occur during charging of the battery shown in FIG. 1 when two electroactive materials are added, each resulting in a voltage plateau).

[0059] In some embodiments, a battery incorporating multiple electroactive materials as described above can be charged at a third voltage by simultaneously (i) removing (e.g., deintercalating) lithium from a first electroactive material, (ii) removing lithium from a second electroactive material, and (iii) converting at least a portion of the lithium sulfide (or lithium polysulfide) to more oxidized sulfur species (e.g., long chain polysulfide or elemental sulfur). The conversion of at least a portion of the lithium polysulfide or lithium sulfide can be along a pathway from Li2S to S8. (The conversion can be fully completed (e.g., to S8) upon full charge of the battery, for at least a substantial majority (e.g., at least 80%) of the initial lithium sulfide present upon full discharge.) The third voltage can be different from (e.g., higher than) the first voltage and / or the second voltage.

[0060] In certain embodiments described herein, the discharge voltage profile(s) of the blended electroactive material(s) (e.g., intercalation material(s)) is compared to the discharge voltage profile of sulfur. For example, the discharge voltage profile(s) of the electroactive material(s) (e.g., intercalation material(s)) is expressed as being comparable to or approximating the discharge voltage profile of sulfur. Such a comparison can be made by separately measuring the discharge voltage profile of the electroactive sulfur and the blended non-sulfur electroactive material in an otherwise similar or identical electrochemical environment. For example, when considering the same electrochemical environment (e.g., same electrolyte and / or anode) except for using an electroactive material instead of (or in addition to) sulfur, the discharge voltage profile of the electroactive material has a voltage plateau that approximates the voltage plateau of the discharge voltage profile of sulfur.

[0061] In certain embodiments, a blend of two or more intercalation materials is used in a cathode that includes electroactive sulfur (e.g., sulfur in the form of an S8 cyclic octaatom molecule) and / or lithium sulfide (e.g., Li2S2 and / or Li2S). In certain embodiments, the blend of intercalation materials includes two or more intercalation materials, each of which has a different discharge voltage plateau from the other, and thus the blend has a discharge voltage profile with two or more plateaus.

[0062] In certain embodiments, the blend of two or more intercalation materials includes one or more chalcogenides (e.g., where at least one of the two or more intercalation materials is a chalcogenide). In certain embodiments, the chalcogenide has at least one chalcogen anion (anion of oxygen, sulfur, selenium, tellurium, or polonium) and at least one electropositive element. In certain embodiments, the one or more chalcogenides may be sulfide-based, selenide-based, or telluride-based. In certain embodiments, the one or more chalcogenides include a metal sulfide. In certain embodiments, the one or more chalcogenides include one or more of the following: TiS2, LiTiS2 (LTS), VS2, MoS2, Mo2S8, TaS2, and NbSe3. In certain embodiments, the one or more chalcogenides include a transition metal oxide and / or a polyanion compound. In certain embodiments, the one or more chalcogenides include a metal monochalcogenide having the formula MX, where M is a transition metal and X is S, Se, or Te. In certain embodiments, the one or more chalcogenides include 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) ... 0.33 Mn 0.33 Co0.33 O2, LiNi 0.8 Co 0.15 Al 0.05 Materials having a spinel crystal structure (e.g., LiMnO2, LiMnO3, or LiCoO4), materials having an olivine crystal structure (e.g., LiFePO4, LiMnPO4, or LiCoPO4), and / or materials having a tavorite crystal structure (e.g., LiFeSO4F or LiVPO4F).

[0063] In certain embodiments, the one or more non-sulfur electroactive materials include a mixed metal sulfide (MMS) (e.g., rather than a physical blend of two or more pure metal sulfides). Such mixed metal sulfides contain two or more transition metals in their crystal lattice. The MMS may have a discharge voltage profile having one or more voltage plateaus (e.g., each due to one of its constituent metals). The discharge voltage profile of the MMS may correspond to (e.g., may approximate) the discharge voltage profile of at least one sulfur electroactive material. In certain embodiments, the non-sulfur electroactive material may be of the formula Ti x M y S z where M is a transition metal other than titanium, and x, y, and z are any values ​​such that MMS has a chemically stable structure. In certain embodiments, the non-sulfur electroactive material is of the formula Mo x M y S z where M is a transition metal other than molybdenum, and x, y, and z are any values ​​such that MMS has a chemically stable structure. x M y S z where M is a transition metal other than vanadium, and x, y, and z are any values ​​such that MMS has a chemically stable structure. In certain embodiments, the non-sulfur electroactive material is of the formula Fe x M y S zwhere M is a transition metal other than iron, and x, y, and z are any values ​​such that MMS has a chemically stable structure. In certain embodiments, the non-sulfur electroactive material is of the formula Ta x M y S z where M is a transition metal other than tantalum, and x, y, and z are any values ​​such that MMS has a chemically stable structure. In certain embodiments, any of the above formulas for MMS are characterized in that 2(x+y)=z.

[0064] In certain embodiments, the non-sulfur electroactive material is MMS containing three transition metals. In certain embodiments, the MMS has the formula Ti x M y M' Y’ S z where M and M' are each a metal other than titanium, and x, y, y', and z are any values ​​such that MMS has a chemically stable structure. x M y M' Y’ S z where M and M' are each a metal other than molybdenum, and x, y, y', and z are any values ​​such that MMS has a chemically stable structure. x M y M' Y’ S z where M and M' are each a metal other than vanadium, and x, y, y', and z are any values ​​such that MMS has a chemically stable structure. In certain embodiments, MMS has the formula Fe x M y M' Y’ S z where M and M' are each a metal other than iron, and x, y, y', and z are any values ​​such that MMS has a chemically stable structure. In certain embodiments, any of the above formulas for MMS are characterized in that 2(x+y+y')=z.

[0065] In certain embodiments, the non-sulfur electroactive material has the formula Mo x Ti y S z (For example, Mo 0.5 Ti 0.5 S2), Ni x Co y S z (For example, Ni x Co 3-x S4, Co x Ni 1-x S2, Ni 3.5 Co 3.5 S8, Ni3Co6S8), Cu x Co y S z (e.g., CuCo2S4), Zn x Co y S z (e.g., Zn x Co 1-x S), Mn x Co y S z (e.g. MnCo2S4), Fe x Co y S z (For example, Fe x Co 1-x S2), Ni x Fe y S z (For example, Ni x Fe 1-x S2, FeNiS2, Ni x Fe 3-x S4 (e.g., Ni2FeS4), Ni x Mo y S z (For example, Ni x Mo 4-x S4 (e.g., NiMo3S4), M x Mo6S 8-y (For example, Cu x Mo6S 8-y , Ag x Mo6S 8-y , Fe x Mo6S 8-y , Cr x Mo6S 8-y , Co x Mo6S 8-y , Ni x Mo6S8-y , Cu2MoS4), M x Sb y S z (wherein M=Cu, Co, or Bi), or M x Sn y S z (wherein M=Cu or Co) stoichiometry. Examples of such materials and other materials that can be used as non-sulfur electroactive materials in cathode materials (e.g., in cathodes) are described in Yu, XY, and Lou, XW, Mixed Metal Sulfides for Electrochemical Energy Storage and Conversion, Adv. Energy Mater. 8:17015921 (2018); doi:10.1002 / aenm.201701592.

[0066] In some embodiments, mixed metal chalcogenides (MMCs) are used as the non-sulfur electroactive material. The chalcogen in the MMCs can be oxygen, sulfur (i.e., the MMCs are MMS), selenium, or tellurium. In some embodiments, the chalcogen in the MMCs is not sulfur. Each of the MMSe examples in the previous paragraph can be considered as a corresponding MMC that does not use sulfur as the chalcogen.

[0067] Moreover, it has been found that the use of such blends of two or more intercalation materials (e.g., including one or more chalcogenides) improves PS behavior and results in better battery performance (e.g., longer battery life, improved volumetric and coulombic efficiency, improved cycling characteristics with negligible or less capacity degradation). Attempts have been made to manage PS behavior (e.g., dissolution, diffusion, shuttling, and anode corrosion) in lithium-sulfur batteries through the formulation and design of the cathode and electrolyte. Such attempts include techniques that attempt to suppress the deleterious formation and / or dissolution of PS (PS bypass) as well as techniques that attempt to favorably retain PS in the Li-S system (PS retention). Without wishing to be limited to a particular theory, it is hypothesized that the use of blends of intercalation materials (e.g., including one or more chalcogenides) with a discharge voltage profile similar to S8→Li2S, as described herein, provides a balance between PS bypass and PS retention strategies for the formulation and design of the cathode, which is not possible with other techniques. For example, the use of a blend of intercalation materials can suppress the shuttling effect of PS, thereby minimizing its detrimental impact on battery operation. Additionally, the use of the blend of intercalation materials described herein can reduce the undesirable generation and / or dissolution of long-chain PS anions. Additionally, the use of the blend of intercalation materials in the sulfur and / or lithium sulfide cathodes described herein allows for higher sulfur loadings and lower electrolyte to sulfur (E / S) ratios compared to other PS management techniques, thereby contributing to improved energy density of lithium-sulfur batteries.

[0068] In some embodiments, the lithium-sulfur battery of the present disclosure includes a lithium anode, a sulfur-based cathode (e.g., including a sulfur electroactive material and two or more non-sulfur electroactive materials (e.g., a blend of two or more non-sulfur electroactive materials)), and an electrolyte that enables ion transport between the anode and the cathode. In certain embodiments described herein, the anode portion of the battery includes the anode and a portion of the electrolyte in contact with the anode. Similarly, in certain embodiments described herein, the cathode portion of the battery includes the cathode and a portion of the electrolyte in contact with the cathode. In certain embodiments, the battery includes a lithium-ion permeable separator that forms an interface between the anode portion and the cathode portion. In certain embodiments, the battery includes a case that encapsulates both the anode portion and the cathode portion. In certain embodiments, the battery case includes a conductive anode end cover in electrical communication with the anode and a conductive cathode end cover in electrical communication with the cathode to facilitate charging and discharging via an external circuit.

[0069] positive electrode The compositions of the present disclosure are useful in the manufacture of electrochemical devices. The compositions may be porous or non-porous. Certain compositions disclosed herein may be deposited on a current collector to form a positive electrode of a secondary sulfur battery. The provided positive electrode compositions may include one or more additives (e.g., conductive particles, binders, and other functional additives commonly found in battery positive electrode mixtures). In general, the provided compositions include sufficient conductive particles to enhance the conductivity of the positive electrode and provide a low resistance path for electrons to access the positive electrode so produced. In various embodiments, other additives are included in the compositions to modify or enhance the positive electrodes produced according to the principles described herein. Other positive electrode components include, for example, current collectors, connection tabs, and the like.

[0070] As discussed above, in certain embodiments, the positive electrode composition comprises a blend of two or more intercalation materials in sulfur (e.g., sulfur in the form of an S8 cyclic octaatom molecule) and / or lithium sulfide (e.g., Li2S2 and / or Li2S). In certain embodiments, the blend of intercalation materials comprises two or more intercalation materials, each of which has a different discharge voltage plateau from the other, and thus the blend has a discharge voltage profile with two or more plateaus. In certain embodiments, the blend of two or more intercalation materials is selected such that its discharge voltage profile (considered separately from sulfur and / or lithium sulfide) has a voltage plateau that approximates that of the discharge voltage profile of S8→Li2S.

[0071] In certain embodiments, the blend of two or more intercalation materials includes one or more chalcogenides (e.g., where each of the two or more intercalation materials is a chalcogenide). In certain embodiments, the chalcogenide has at least one chalcogen anion (an anion of oxygen, sulfur, selenium, tellurium, or polonium) and at least one electropositive element. In certain embodiments, the one or more chalcogenides may be sulfide-based, selenide-based, or telluride-based. In certain embodiments, the one or more chalcogenides include a metal sulfide. In certain embodiments, the one or more chalcogenides include one or more of the following: TiS2, TiS3, LiTiS2 (LTS), and NbSe3. In certain embodiments, the one or more chalcogenides include a transition metal oxide and / or a polyanion compound. In certain embodiments, the one or more chalcogenides include a metal monochalcogenide having the formula MX, where M is a transition metal and X is S, Se, or Te. In certain embodiments, the one or more chalcogenides include 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) ... 0.33 Mn 0.33 Co 0.33 O2, LiNi 0.8 Co 0.15 Al 0.05 Materials having a spinel crystal structure (e.g., LiMnO2, LiMnO3, or LiCoO4), materials having an olivine crystal structure (e.g., LiFePO4, LiMnPO4, or LiCoPO4), and / or materials having a tavorite crystal structure (e.g., LiFeSO4F or LiVPO4F).

[0072] In some embodiments, the non-sulfur electroactive material comprises particles (e.g., nanoparticles). For example, chalcogenide particles can be used as the non-sulfur electroactive material. The blend of two or more non-sulfur electroactive materials can include a blend of two particles (e.g., two different chalcogenides), particles including a blend of two non-sulfur electroactive materials (e.g., particles including two different chalcogenides), or both. In some embodiments, the particles of the non-sulfur electroactive material are distributed (e.g., dispersed) throughout the positive electrode material. The positive electrode material can include particles including a sulfur electroactive material (e.g., particles of a sulfur electroactive material). The one or more non-sulfur electroactive materials can form one or more separate and / or one or more interconnected (e.g., charge and / or ion) transport pathways through the positive electrode material (e.g., within a battery positive electrode). The one or more non-sulfur electroactive materials can be distributed (e.g., dispersed) throughout a sulfur electroactive material matrix (e.g., including one or more sulfur electroactive materials). As described elsewhere, at least one non-sulfur electroactive material of the blend may be included in the shell of a core-shell particle that includes a core of sulfur electroactive material. The particles (e.g., nanoparticles) may have any suitable shape, such as, for example, rod-like, flake-like, tubular, spherical, etc. The particles may be porous or non-porous. The particles may have any suitable size. In some embodiments, the particles are 500 micrometers or less in dimensions, 250 micrometers or less in dimensions, 100 micrometers or less in dimensions, 50 micrometers or less in dimensions, 20 micrometers or less in dimensions, 10 micrometers or less in dimensions, 5 micrometers or less in dimensions, 1 micrometer or less in dimensions, 500 nanometers or less in dimensions, 400 nanometers or less in dimensions, 300 nanometers or less in dimensions, 250 nanometers or less in dimensions, 200 nanometers or less in dimensions, 100 nanometers or less in dimensions, or 50 nanometers or less in dimensions.

[0073] In certain embodiments, the positive electrode composition includes a conductive material and a binder. In certain embodiments, the conductive material includes a conductive material that facilitates the movement of electrons within the composite. For example, in certain embodiments, the conductive material is selected from the group consisting of carbon-based materials, graphite-based materials, conductive polymers, metals, semiconductors, metal oxides, metal sulfides, and combinations thereof. In certain embodiments, the conductive material includes a carbon-based material. For example, in certain embodiments, the provided positive electrode composition may include a 3D structure of graphene (e.g., as described in U.S. Pat. No. 11,299,397 (LytEn, Inc.), the entire text of which is incorporated herein by reference). In certain embodiments, the conductive material includes a graphite-based material. In certain embodiments, the positive electrode composition does not contain carbon or has a low carbon content (e.g., 5.0 wt.% or less, 3.0 wt.% or less, 2.0 wt.% or less, 1.0 wt.% or less, or 0.5 wt.% or less).

[0074] In certain embodiments, the conductive material is selected from the group consisting of 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 other conductive carbon powders. In certain embodiments, the conductive material comprises one or more conductive polymers. For example, in certain embodiments, the conductive polymer is selected from the group consisting of polyaniline, polythiophene, polyacetylene, polypyrrole, and the like. In some embodiments, the conductive polymer is a cationic polymer. In some embodiments, the cationic polymer is a quaternary ammonium polymer. In certain embodiments, the cationic polymer is selected from the group consisting of polydiallyldimethylammonium salts, poly[(3-chloro-2-hydroxypropyl)methacryloxyethyldimethyl-ammonium salts, poly(butylacrylate-methacryloxyethyltrimethylammonium) salts, poly(1-methyl-4-vinylpyridinium) salts, poly(1-methyl-2-vinylpyridinium) salts, and poly(methacryloxyethyltriethylammonium) salts. In certain embodiments, the 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), poly(butylacrylate-methacryloxyethyltrimethylammonium bromide), poly(1-methyl-4-vinylpyridinium bromide), poly(1-methyl-2-vinylpyridinium bromide), and poly(methylacryloxyethyltriethylammonium bromide).In certain embodiments, the conductive material comprises one or more metal oxides or metal sulfides. For example, in certain embodiments, the conductive material comprises one or more oxides or sulfides of a first row transition metal, such as titanium, vanadium, chromium, manganese, iron, cobalt, copper, zinc, or combinations thereof. For example, in certain embodiments, the conductive material comprises one or more oxides or sulfides of a second row transition metal, such as zirconium, indium, tin, antimony, or combinations thereof. In certain embodiments, the conductive material is used alone. In other embodiments, the conductive material is used as a mixture of two or more of the above conductive materials.

[0075] In certain embodiments, a binder is included in the provided cathode composition material. Binders are generally polymeric materials that help to bond the individual particles that make up the cathode mixture together to form a stable composite. Exemplary binders include polyvinylidene fluoride, poly(vinylidene fluoride-co-hexafluoropropene) (PVDF / HFP), polytetrafluoroethylene (PTFE), Kynar Flex® 2801, Kynar® Powerflex LBG, Kynar® HSV 900, Teflon®, carboxymethyl cellulose, styrene-butadiene rubber (SBR), polyethylene oxide, polypropylene oxide, polyethylene, polypropylene, polyacrylate, polyvinylpyrrolidone, poly(methyl methacrylate), polyethyl acrylate, polytetrafluoroethylene, polyvinyl chloride, polyacrylonitrile, polycaprolactam, polyethylene terephthalate, polybutadiene, polyisoprene, or polyacrylic acid, or any derivative, mixture, or copolymer thereof. In some embodiments, the binder is a water-soluble binder such as sodium alginate, carrageenan, or carboxymethylcellulose. In general, the binder holds the active material in contact with the current collector (e.g., a metal foil such as aluminum, stainless steel, copper, or a sheet of conductive carbon) together. In certain embodiments, the binder is selected from the group consisting of poly(vinyl acetate), polyvinyl alcohol, polyethylene oxide, polyvinylpyrrolidone, alkylated polyethylene oxide, crosslinked polyethylene oxide, polyvinyl ether, poly(methyl methacrylate), polyvinylidene fluoride, copolymers of polyhexafluoropropylene and polyvinylidene fluoride, polyethyl acrylate, polytetrafluoroethylene, polyvinyl chloride, polyacrylonitrile, polyvinylpyridine, polystyrene, and derivatives, mixtures, and copolymers thereof. In some embodiments, the binder is a cationic polymer. In some embodiments, the binder is a quaternary ammonium polymer. In some embodiments, the binder is a cationic polymer as described above.

[0076] In certain embodiments, the positive electrode further comprises a coating layer, for example, in certain embodiments, the coating layer comprises a polymer, an organic material, an inorganic material, or a mixture thereof, which is not an integral part of the porous composite or the current collector. In certain such embodiments, the polymer is selected from the group consisting of polyvinylidene fluoride, copolymers of polyvinylidene fluoride and hexafluoropropylene, poly(vinyl acetate), poly(vinyl butyral-co-vinyl alcohol-co-vinyl acetate), poly(methyl methacrylate-co-ethyl acrylate), polyacrylonitrile, polyvinyl chloride-co-vinyl acetate, polyvinyl alcohol, poly(l-vinyl pyrrolidone-co-vinyl acetate), cellulose acetate, polyvinyl pyrrolidone, polyacrylates, polymethacrylates, polyolefins, polyurethanes, polyvinyl ethers, acrylonitrile-butadiene rubber, styrene butadiene rubber, acrylonitrile-butadiene styrene, sulfonated styrene / ethylene-butylene / styrene triblock copolymers, polyethylene oxide, and derivatives, mixtures, and copolymers thereof. In some embodiments, the coating layer comprises a cationic polymer. In some embodiments, the coating layer comprises a quaternary ammonium polymer. In some embodiments, the coating layer comprises the cationic polymer described above. In certain such embodiments, the 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 (ZrO2), iron oxide, iron sulfide (FeS), iron titanate (FeTiO3), barium titanate (BaTiO3), and combinations thereof. In certain embodiments, the organic material comprises conductive carbon.

[0077] Materials suitable for use in the positive electrode mixture are disclosed in Cathode Materials for Lithium Sulfur Batteries: Design, Synthesis, and Electrochemical Performance, Lianfeng, et al., Interchopen.com, published June 1, 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 incorporated herein by reference.

[0078] In certain embodiments, the positive electrode comprises one or more of the following features (a)-(l): (a) a "stack" of multifunctional materials (e.g., the stack comprises particles with gradient structures that balance ion and electron transport for improved power capability, energy density, and lifetime; comprises bifunctional positive electrode additives that store Li and simultaneously conduct electrons, replacing expensive and bulky carbons; comprises binding molecules that spatially confine the electrochemical reaction that stores energy, thereby extending lifetime; comprises electrolyte components that improve the basic efficiency of the electrolyte and improve energy density; and / or comprises electrolyte components that provide improved safety and energy density). (b) tight electrode layers; (c) tight tertiary structures; (d) porosity control; (e) core-shell structures; (f) crosslinked polymer shells; (g) self-doped polymer shells; (h) ionically conductive binders; (i) bilayer hybrid cathodes; (j) polysulfide-trapping polymers; (k) three-dimensional structures with high surface area (e.g., retaining (e.g., intercalating) both carbon and lithium); and (l) three-dimensional structures where carbon is substituted with metal disulfides (e.g., the battery contains a polymer electrolyte for sulfur).

[0079] negative electrode In certain embodiments, the secondary sulfur battery includes a lithium anode. Any lithium anode suitable for use in lithium-sulfur cells can be used. In certain embodiments, the anode of the secondary sulfur battery includes an anode active material selected from a material in which lithium intercalation occurs reversibly, a material that reacts with lithium ions to form a lithium-containing compound, metallic lithium, a lithium alloy, and combinations thereof. In certain embodiments, the anode includes metallic lithium. In certain embodiments, the lithium-containing anode composition includes a carbon-based compound. In certain embodiments, the carbon-based compound is selected from the group consisting of crystalline carbon, amorphous carbon, graphite, and mixtures thereof. In certain embodiments, the anode is carbon-free or has a low carbon content (e.g., 5.0 wt.% or less, 3.0 wt.% or less, 2.0 wt.% or less, 1.0 wt.% or less, or 0.5 wt.% or less). In certain embodiments, the material that reacts with lithium ions to form a lithium-containing compound is selected from the group consisting of tin oxide (SnO2), titanium nitrate, and silicon. In certain embodiments, the lithium alloy comprises an alloy of lithium with another alkali metal (e.g., sodium, potassium, rubidium, or cesium). In certain embodiments, the lithium alloy comprises an alloy of lithium with a transition metal. In certain embodiments, the lithium alloy comprises an alloy of lithium with a metal selected from the group consisting of Na, K, Rb, Cs, Fr, Be, Mg, Ca, Sr, Ba, Ra, Al, Sn, In, Zn, Sm, La, and combinations thereof. In certain embodiments, the lithium alloy comprises an alloy of lithium with indium. In certain embodiments, the lithium alloy comprises an alloy of lithium with aluminum. In certain embodiments, the lithium alloy comprises an alloy of lithium with zinc. In certain embodiments, the negative electrode comprises a lithium-silicon alloy. Examples of suitable lithium-silicon alloys include Li 15 Si4, Li 12 Si7, Li7Si3, Li 13 Si4 and Li 21 Si5 / Li 22In certain embodiments, the lithium metal or lithium alloy is present as a composite with another material. In certain embodiments, such a composite includes a material such as graphite, graphene, a metal sulfide or metal oxide, or a conductive polymer.

[0080] In some embodiments, the negative electrode is protected from redox shuttling reactions and dangerous runway reactions by any of the methods reported in the art (e.g., by chemical passivation or by deposition or polymerization to generate a protective layer on the surface of the negative electrode). For example, in certain embodiments, the negative electrode comprises an inorganic protective layer, an organic protective layer, or a mixture thereof, on the surface of the lithium metal. In certain embodiments, the inorganic protective layer comprises Mg, Al, B, Sn, Pb, Cd, Si, In, Ga, lithium silicate, lithium borate, lithium phosphate, lithium phosphorus nitride, lithium silicosulfide, lithium borosulfide, lithium aluminosulfide, lithium phosphorus sulfide, lithium fluoride, or a combination thereof. In certain embodiments, the organic protective layer comprises a conductive monomer, oligomer, or polymer. In certain embodiments, such polymers are selected from poly(p-phenylene), polyacetylene, poly(p-phenylenevinylene), polyaniline, polypyrrole, polythiophene, poly(2,5-ethylenevinylene), acetylene, poly(perinaphthalene), polyacene, and poly(naphthalene-2,6-di-yl), or combinations thereof.

[0081] Furthermore, in certain embodiments, during charging and discharging of the secondary sulfur battery, inactive sulfur material generated from the electroactive sulfur material of the positive electrode is deposited on the negative electrode surface. As used herein, the term "inactive sulfur" refers to sulfur that is not active in electrochemical and chemical reactions and therefore cannot participate in the electrochemical reaction of the positive electrode. In certain embodiments, the inactive sulfur on the negative electrode surface acts as a protective layer on such an electrode. In certain embodiments, the inactive sulfur is lithium sulfide.

[0082] In some embodiments, the battery is a primary battery or a low cycle life battery. Such a battery may include a negative electrode, a positive electrode (e.g., including a positive electrode material disclosed herein), an electrolyte, and optionally a separator. The positive electrode may be suitable for use in a secondary battery. However, the battery may be a primary battery or a low cycle life battery, for example, because the negative electrode irreversibly degrades during discharge (e.g., during one or a few cycles).

[0083] It is further contemplated that the present disclosure may be adapted for use in sodium-sulfur batteries, which include sodium-based negative electrodes and are encompassed within the scope of the present disclosure.

[0084] It is further contemplated that the present disclosure may be adapted for use in batteries having a configuration that does not include a negative electrode. In certain embodiments, the battery has a configuration that does not include a negative electrode and includes one or more of the following (a) to (e): (a) a thin layer of garnet, (b) a structure (e.g., a composite 3D structure) having a coating deposited by atomic layer deposition (ALD) (e.g., the ALD coating includes one or more components selected from the group consisting of lithium phosphorus oxynitride (LiPON), garnet, oxide, perovsite, sulfide, Li3BO3-Li2CO3 (LBCO), sodium superionic 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).

[0085] 1. Preparation of Electrodes There are various methods for producing electrodes for use in secondary sulfur batteries. One process, for example the "wet process", involves adding solid cathode material to a liquid to prepare a slurry composition. These slurries are usually in the form of viscous liquids formulated to facilitate downstream coating operations. Thorough mixing of the slurry can be important for coating and drying operations that affect the performance and quality of the electrode. Suitable mixing equipment includes ball mills, magnetic stirrers, ultrasonication, planetary mixers, high speed mixers, homogenizers, universal type mixers, and static mixers. The liquid used to make the slurry can be any that uniformly disperses the active material, binder, conductive material, and any additives and evaporates easily. 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.

[0086] In some embodiments, the prepared composition is coated onto a current collector and dried to form an electrode. Specifically, the electrode is formed by coating a conductor with the slurry and spreading the slurry evenly over the conductor, and then, in certain embodiments, the electrode is roll-pressed (e.g., calendered) and heated as needed, as known in the art. Generally, the matrix of active material and conductive material is held together on the conductor by a binder. In certain embodiments, the matrix comprises a polymer binder, such as polyvinylidene fluoride (PVDF), poly(vinylidene fluoride-co-hexafluoropropene) (PVDF / HFP), polytetrafluoroethylene (PTFE), Kynar Flex® 2801, Kynar® Powerflex LBG, Kynar® HSV 900, Teflon®, styrene butadiene rubber (SBR), polyethylene oxide (PEO), or polytetrafluoroethylene (PTFE). In certain embodiments, additional carbon particles, carbon nanofibers, carbon nanotubes are dispersed in the matrix to improve electrical conductivity. Alternatively or additionally, in certain embodiments, a lithium salt is dispersed in the matrix to improve lithium conductivity.

[0087] In certain embodiments, the current collector is selected from the group consisting of aluminum foil, copper foil, nickel foil, stainless steel foil, titanium foil, zirconium foil, molybdenum foil, nickel foam, copper foam, carbon paper or carbon fiber sheet, a polymer substrate coated with a conductive metal, and / or combinations thereof.

[0088] PCT Publication Nos. WO2015 / 003184, WO2014 / 074150, and WO2013 / 040067, the disclosures of which are incorporated herein by reference in their entireties, describe various methods of manufacturing electrodes and electrochemical cells.

[0089] Separator In certain embodiments, the secondary sulfur battery includes a separator. The separator divides the negative and positive electrodes and prevents direct electronic conduction between them. In certain embodiments, the separator has high lithium ion permeability. In certain embodiments, the separator is relatively impermeable to polysulfide ions dissolved in the electrolyte. In certain such embodiments, the separator as a whole inhibits or limits the passage of electrolyte-soluble sulfides between the negative and positive electrode portions of the battery. In certain embodiments, the separator of impermeable material is configured to allow lithium ion transport between the negative and positive electrodes of the battery during charging and discharging of the cell. In some such embodiments, the separator is porous. One or more electrolyte-permeable channels can be provided that bypass or penetrate the impermeable surface of the separator to allow sufficient lithium ion flow between the negative and positive electrode portions of the battery.

[0090] As will be apparent to those skilled in the art, the optimum dimensions of the separator require a balance between the competing concerns of maximizing impedance to polysulfide migration while allowing sufficient lithium ion flow. Apart from this consideration, the shape and orientation of the separator is not particularly limited and will depend in part on the battery configuration. For example, in some embodiments, the separator is substantially circular in a coin-type cell and substantially rectangular in a pouch-type cell. In some embodiments, the separator is substantially flat. However, curved or other non-planar shapes are not precluded from being used.

[0091] The separator can be of any suitable thickness. To maximize the energy density of the battery, it is generally preferred that the separator be as thin and lightweight as possible. However, the separator should be thick enough to provide sufficient mechanical robustness and ensure adequate electrical isolation of the electrodes. In certain embodiments, the separator has a thickness of about 1 μm to about 200 μm, preferably about 5 μm to about 100 μm, and more preferably about 10 μm to about 30 μm.

[0092] electrolyte In certain embodiments, the secondary sulfur battery includes an electrolyte that includes an electrolyte salt, such as lithium trifluoromethanesulfonimide, lithium triflate, lithium perchlorate, LiPF6, LiBF4, tetraalkylammonium salts (e.g., tetrabutylammonium tetrafluoroborate, TBABF4), and salts that are liquid at room temperature (e.g., imidazolium salts such as 1-ethyl-3-methylimidazolium bis-(perfluoroethylsulfonyl)imide, EMIBeti).

[0093] In certain embodiments, the electrolyte comprises one or more alkali metal salts. In certain embodiments, such salts comprise lithium salts (e.g., LiCF3SO3, LiClO4, LiNO3, LiPF6, LiBr, LiTDI, LiFSI, and LiTFSI, or combinations thereof). In certain embodiments, the electrolyte comprises an ionic liquid (e.g., 1-ethyl-3-methylimidazolium-TFSI, N-butyl-N-methyl-piperidinium-TFSI, N-methyl-n-butylpyrrolidinium-TFSI, and N-methyl-N-propylpiperidinium-TFSI, or combinations thereof). In certain embodiments, the electrolyte comprises a superionic conductor (e.g., a sulfide, an oxide, and a phosphate (e.g., phosphorus pentasulfide), or combinations thereof).

[0094] In certain embodiments, the electrolyte is a liquid. For example, in certain embodiments, the electrolyte comprises an organic solvent. In certain embodiments, the electrolyte comprises only one organic solvent. In some embodiments, the electrolyte comprises a mixture of two or more organic solvents. In certain embodiments, the mixture of organic solvents comprises one or more of a weakly polar solvent, a strongly polar solvent, and a lithium-protecting solvent.

[0095] As used herein, the term "weakly polar solvent" is defined as a solvent capable of dissolving elemental sulfur and having a dielectric constant less than 15. Weakly polar solvents are selected from aryl compounds, bicyclic ethers, and acyclic carbonate compounds. Examples of weakly polar solvents include xylene, dimethoxyethane, 2-methyltetrahydrofuran, diethyl carbonate, dimethyl carbonate, toluene, dimethyl ether, diethyl ether, diglyme, tetraglyme, and the like. As used herein, the term "strongly polar solvent" is defined as a solvent capable of dissolving lithium polysulfide and having a dielectric constant greater than 15. Strongly polar solvents are selected from bicyclic carbonate compounds, sulfoxide compounds, lactone compounds, ketone compounds, ester compounds, sulfate compounds, and sulfite compounds. Examples of strong polar solvents include hexamethylphosphoric triamide, γ-butyrolactone, acetonitrile, ethylene carbonate, propylene carbonate, N-methylpyrrolidone, 3-methyl-2-oxazolidone, dimethylformamide, sulfolane, dimethylacetamide, dimethylsulfoxide, dimethyl sulfate, ethylene glycol diacetate, dimethyl sulfite, ethylene glycol sulfite, and the like. As used herein, the term "lithium protection solvent" is defined as a solvent that forms a good protection layer, i.e., a stable solid electrolyte interface (SEI) layer, on the lithium surface and exhibits at least 50% cycle efficiency. The lithium protection solvent is selected from saturated ether compounds, unsaturated ether compounds, and heterocyclic compounds containing one or more heteroatoms selected from the group consisting of N, O, and / or S. Examples of lithium protection solvents include tetrahydrofuran, 1,3-dioxolane, 3,5-dimethylisoxazole, 2,5-dimethylfuran, furan, 2-methylfuran, 1,4-oxane, 4-methyldioxolane, and the like.

[0096] In certain embodiments, the electrolyte is a liquid (e.g., an organic solvent). In some embodiments, the liquid is selected from the group consisting of an organic carbonate, an ether, a sulfone, water, an alcohol, a fluorocarbon, or any combination thereof. In certain embodiments, the electrolyte comprises an ether solvent.

[0097] In certain embodiments, the organic solvent comprises an ether. In certain embodiments, the organic solvent is selected from the group consisting of 1,3-dioxolane, dimethoxyethane, diglyme, triglyme, γ-butyrolactone, γ-valerolactone, and combinations thereof. In certain embodiments, the organic solvent comprises a mixture of 1,3-dioxolane and dimethoxyethane. In certain embodiments, the organic solvent comprises a 1:1 (v / v) mixture of 1,3-dioxolane and dimethoxyethane. In certain embodiments, the organic solvent is selected from the group consisting of diglyme, triglyme, γ-butyrolactone, γ-valerolactone, and combinations thereof. In certain embodiments, the electrolyte comprises sulfolane, sulfolene, dimethyl sulfone, methyl ethyl sulfone, or combinations thereof. In some embodiments, the electrolyte comprises ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate, methyl ethyl carbonate, or combinations thereof.

[0098] In certain embodiments, the electrolyte is solid. In certain embodiments, the solid electrolyte comprises a polymer. In certain embodiments, the solid electrolyte comprises a glass, a ceramic, an inorganic composite, or a combination thereof. In certain embodiments, the solid electrolyte comprises a polymer composite containing a glass, a ceramic, an inorganic composite, or a combination thereof. In certain embodiments, such solid electrolytes include one or more liquid components as plasticizers or to form a "gel electrolyte".

[0099] Secondary Sulfur Battery Described herein is a secondary sulfur battery comprising the above-mentioned positive electrode composition. For example, in certain embodiments, such a battery comprises a provided positive electrode composition and a lithium-containing negative electrode composition combined therewith by a lithium conductive electrolyte. In some embodiments, such a battery also comprises additional components (e.g., a separator between the negative and positive electrodes, a negative and positive current collectors, terminals that can connect the cell to an external load, and packaging such as a flexible pouch or a rigid metal container). As further contemplated, the present disclosure regarding secondary sulfur batteries can be adapted for use in sodium-sulfur batteries, and such batteries are also considered to be within the scope of certain embodiments of the present disclosure.

[0100] 2 illustrates a cross-section of an electrochemical cell 800 according to an exemplary embodiment of the present disclosure. The electrochemical cell 800 includes a negative electrode 802, a positive electrode 804, a separator 806 interposed between the negative electrode 802 and the positive electrode 804, a container 810, and a fluid electrolyte 812 in contact with the negative electrode 802 and the positive electrode 804. Such a cell optionally includes additional layers of electrodes and separators 802a, 802b, 804a, 804b, 806a, and 806b.

[0101] The negative electrode 802 (sometimes referred to herein as the anode) comprises an active negative electrode material capable of accepting cations. Non-limiting examples of active negative electrode materials for lithium-based electrochemical cells include Li metal, Li alloys (e.g., Li alloys such as Si, Sn, Bi, In, and / or Al alloys), Li4Ti5O 12 , hard carbon, graphitic carbon, metal chalcogenides, and / or amorphous carbon. According to some embodiments of the present disclosure, most (e.g., greater than 90% by weight) of the negative electrode active material may be initially contained in the discharged positive electrode 804 (sometimes referred to herein as the positive electrode) when the electrochemical cell 800 is first fabricated, and thus the electrode active material forms part of the first electrode 802 during the initial charging of the electrochemical cell 800.

[0102] Methods for depositing an electroactive material onto a portion of the negative electrode 802 are described in U.S. Patent Publication Nos. 2016 / 0172660 and 2016 / 0172661 (applicant Fischer et al.), the contents of each of which are incorporated herein by reference to the extent that the content thereof is not inconsistent with this disclosure.

[0103] The positive electrode 804 (also referred to herein as the positive electrode) comprises a positive electrode composition as described herein. In certain embodiments, the positive electrode composition comprises about 30 to about 70 weight percent electroactive sulfur. In certain embodiments, the positive electrode comprises at least about 70% of the total sulfur present in the electrochemical cell. In certain embodiments, the positive electrode comprises at least about 80% of the total sulfur present in the electrochemical cell. In certain embodiments, the positive electrode comprises at least about 90% of the total sulfur present in the electrochemical cell. In certain embodiments, the positive electrode comprises at least about 95% of the total sulfur present in the electrochemical cell. In certain embodiments, the positive electrode comprises at least about 99% of the total sulfur present in the electrochemical cell. In certain embodiments, the positive electrode comprises substantially all of the total sulfur present in the electrochemical cell.

[0104] The negative electrode 802 and the positive electrode 804 can further include one or more conductive additives, as described above. According to some embodiments of the present disclosure, the negative electrode 802 and / or the positive electrode 804 further include one or more polymer binders, as described above.

[0105] FIG. 3 shows an example of a battery according to various embodiments described herein. A cylindrical battery is shown here for illustrative purposes, but other types of configurations, such as prismatic or pouch (laminated type) batteries, can also be used. The exemplary Li battery 901 includes a negative electrode 902, a positive electrode 904, a separator 906 interposed between the negative electrode 902 and the positive electrode 904, an electrolyte (not shown) impregnated in the separator 906, a battery case 905, and a sealing member 908 that seals the battery case 905. Of course, the exemplary battery 901 may simultaneously embody multiple aspects of the present disclosure in various designs.

[0106] The secondary sulfur battery of the present disclosure includes a lithium anode, a porous sulfur-based cathode, and an electrolyte that allows for the transport of lithium ions between the anode and cathode. In certain embodiments described herein, the anode portion of the battery includes the anode and a portion of the electrolyte in contact with the anode. Similarly, in certain embodiments described herein, the cathode portion of the battery includes the cathode and a portion of the electrolyte in contact with the cathode. In certain embodiments, the battery includes a lithium-ion permeable separator that forms an interface between the anode portion and the cathode portion. In certain embodiments, the battery includes a case that encapsulates both the anode portion and the cathode portion. In certain embodiments, the battery case includes a conductive anode end cover in electrical communication with the anode and a conductive cathode end cover in electrical communication with the cathode to facilitate charging and discharging via an external circuit.

[0107] In certain embodiments, the secondary sulfur battery of the present disclosure is specified in terms of its ratio of electrolyte to electroactive sulfur. The volume of the electrolyte and the ratio of electrolyte to sulfur in the positive electrode (volume / weight) correlate with the energy density of the sulfur battery. The electrolyte may be distributed among different parts of the volume in the cell, for example, the electrolyte may be included in the pores of the positive electrode, in the separator, and in contact with the negative electrode or between the negative electrode solid electrolyte phases. The electrolyte may also be included in other spaces in the battery that are not in direct contact with the negative electrode active material or the positive electrode active material, for example, the electrolyte may be left in the annular volume at the edge of a coin cell. In certain embodiments, the present disclosure provides a battery in which the entire or majority of the electrolyte is included in the positive electrode. Preferably, substantially all of the electrolyte is included in the positive electrode, and only the minimum amount of electrolyte required to wet the separator and negative electrode surface or SEI is outside the positive electrode. The electrolyte included in the positive electrode is called the "contained electrolyte" and its volume V CE can be estimated as the theoretical pore volume or as the porosity multiplied by the geometric volume of the positive electrode film.

number

[0108] In certain embodiments, the provided secondary sulfur battery has a total electrolyte content (V tot ) is in the positive electrode (e.g., V CE / V tot In certain embodiments, the provided secondary sulfur battery is characterized by a total electrolyte content (V tot ) is in the positive electrode (e.g., V CE / V tot >0.8). In certain embodiments, the secondary sulfur battery has at least 60%, at least 65%, or at least 70% of the electrolyte contained in the positive electrode porous material. In certain embodiments, the secondary sulfur battery has at least 80%, at least 85%, or at least 90% of the electrolyte contained in the positive electrode porous material. In certain embodiments, the secondary sulfur battery has at least 92%, at least 94%, at least 95%, at least 96%, or at least 97% of the electrolyte contained in the positive electrode porous material.

[0109] The total electrolyte to sulfur ratio (E / S) is another parameter that affects the energy density of the battery. The E / S ratio is proportional to the total volume of electrolyte, V tot and the mass of electroactive sulfur (m sulfur ) is calculated based on

number

[0110] In certain embodiments, the secondary sulfur battery has an electrolyte to sulfur ratio of about 6 microliters or less per milligram of electroactive sulfur. In certain embodiments, the secondary sulfur battery has an electrolyte to sulfur ratio of about 5 microliters or less per milligram of electroactive sulfur. In certain embodiments, the secondary sulfur battery has an electrolyte to sulfur ratio of about 4.5 microliters or less per milligram of electroactive sulfur. In certain embodiments, the secondary sulfur battery has an electrolyte to sulfur ratio of about 3.5 microliters or less per milligram of electroactive sulfur, or an electrolyte to sulfur ratio of less than about 3.0 microliters per milligram of electroactive sulfur. In certain embodiments, the secondary sulfur battery has an electrolyte to sulfur ratio of about 3.5 microliters or less per milligram of electroactive sulfur. In certain embodiments, the secondary sulfur battery has an electrolyte to sulfur ratio of about 3 microliters or less per milligram of electroactive sulfur. In certain embodiments, the secondary sulfur battery has an electrolyte to sulfur ratio of about 1.8 to about 3.5 μL / mg S. In certain embodiments, the secondary sulfur battery has an electrolyte to sulfur ratio of about 1.8 to about 2.5 μL / mg S.

[0111] Core-shell nanostructure In certain embodiments, the cathode material has a core-shell structure (e.g., nanostructure), in which the core contains the sulfur active material and the surrounding shell contains the non-sulfur electroactive material. In certain embodiments, the structure is nanoporous. In certain embodiments, the average diameter of the core is, for example, less than about 1000 nm, less than about 500 nm, less than about 250 nm, less than about 100 nm, less than about 80 nm, less than about 70 nm, less than about 60 nm, less than about 50 nm, less than about 40 nm, less than about 30 nm, less than about 25 nm, less than about 20 nm, less than about 10 nm, or less than about 5 nm, and / or the average diameter of the core may be within any range between any two of the above values. In certain embodiments, the core is spherical, nearly spherical, or amorphous in shape. In certain embodiments, the average diameter of the core is about 50 to about 500 nm, about 50 to about 200 nm, about 20 to about 100 nm, about 100 to about 300 nm, or about 200 to about 400 nm.

[0112] In certain embodiments, the average thickness of the shell surrounding the core is, for example, less than about 1000 nm, less than about 500 nm, less than about 250 nm, less than about 100 nm, less than about 80 nm, less than about 70 nm, less than about 60 nm, less than about 50 nm, less than about 40 nm, less than about 30 nm, less than about 25 nm, less than about 20 nm, less than about 15 nm, less than about 10 nm, less than about 5 nm, less than about 3 nm, less than about 2 nm, or less than about 1 nm, and / or the average thickness of the shell may be within any range between any two of the above values. In certain embodiments, the average thickness of the shell surrounding the core is about 1 to about 50 nm, about 2 to about 20 nm, about 1 to about 10 nm, about 10 to about 20 nm, about 5 to about 15 nm, or about 1 to about 5 nm.

[0113] In certain embodiments, the core of the core-shell particle provided is composed of substantially pure electroactive sulfur material. In certain embodiments, the core comprises a composite of the electroactive sulfur material with an additional material, such as an inorganic solid, a metal, a polymer, or other non-sulfur electroactive material. Such a composite may comprise a simple physical mixture of materials, or may comprise a composite of more complex structure, such as a porous framework material infused with sulfur electroactive material.

[0114] In certain embodiments, the non-sulfur electroactive shell of the provided core-shell particles is non-porous and / or substantially impermeable to liquids (e.g., electrolytes) and / or impermeable to sulfur or polysulfides (or mixtures of electrolytes and polysulfides). Such configurations allow electrons and lithium ions to access the electroactive sulfur core while preventing redistribution of the electroactive sulfur material within the cathode or battery. Such configurations can be advantageous in this regard.

[0115] In other embodiments, the non-sulfur electroactive shell of the provided core-shell particles is porous and / or permeable (e.g., permeable to liquid electrolyte or components thereof). In certain embodiments, such a permeable shell may be advantageous to ensure electrolyte contact with the electroactive sulfur and / or to prevent the shell from rupturing or being damaged by physical strain due to volume changes in the core. In certain embodiments, such shells are nanoporous, e.g., having pores with diameters less than 1 nm (e.g., less than 0.5 nm, less than 0.4 nm, or less than 0.3 nm, or less than 0.2 nm) and / or with an average pore size within any range between any two of the above values. In certain embodiments, the average pore size of the core and / or shell is less than 1 nm, e.g., less than 0.9 nm, less than 0.8 nm, less than 0.7 nm, or less than 0.6 nm, and / or within any range between any two of the above values. In certain embodiments, the size of the pores is measured by microscopy (e.g., TEM, SEM, or AFM).

[0116] In certain embodiments, the electroactive sulfur material comprises sulfur in the form of an S8 cyclic octaatomic molecule, sulfur in the form of a lithium sulfide (e.g., Li2S2 and / or Li2S), sulfur in the form of an electroactive organosulfur compound, and / or sulfur in the form of an electroactive sulfur-containing polymer. In certain embodiments, the non-sulfur electroactive blend comprises one or more non-sulfur chalcogenides.

[0117] In certain embodiments, the chalcogenide has at least one chalcogen anion (anion of oxygen, sulfur, selenium, tellurium, or polonium) and at least one electropositive element. In certain embodiments, the chalcogenide may be sulfide-based, selenide-based, or telluride-based. In certain embodiments, the chalcogenide includes a metal sulfide (e.g., a sulfide of a metal other than lithium or sodium). In certain embodiments, the one or more chalcogenides include a transition metal sulfide. In certain embodiments, the one or more chalcogenides include one or more of the following: TiS2, LiTiS2 (LTS), VS2, MoS2, Mo6S8, and NbSe3. In certain embodiments, the one or more chalcogenides include a transition metal oxide and / or a polyanion compound. In certain embodiments, the one or more chalcogenides include a metal monochalcogenide having the formula MX, where M is a transition metal and X is S, Se, or Te. In certain embodiments, the one or more chalcogenides include 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) ... 0.33 Mn 0.33 Co 0.33 O2, LiNi 0.8 Co 0.15 Al 0.05In certain embodiments, the cathode material includes LiFePO4, LiMnPO4, or LiCoPO4 (e.g., having an olivine crystal structure), and / or LiFeSO4F or LiVPO4F (e.g., having a taborite crystal structure). Throughout the description, although articles, devices, and systems are described as having, including, or comprising certain components, or processes and methods are described as having, including, or comprising certain steps, it is believed that there are articles, devices, and systems according to certain embodiments of the disclosure that consist essentially of or consist of the described components, and further that there are processes and methods according to certain embodiments of the disclosure that consist essentially of or consist of the described processing steps. "Sulfur electroactive material" and "electroactive sulfur material" are used interchangeably herein.

[0118] It should be understood that the order of steps or the order for performing certain actions is not important so long as operability is not lost. Moreover, two or more steps or actions may be performed simultaneously. As will be appreciated by those skilled in the art, the terms "on", "under", "up", "down", "under" and "on" are relative terms and can be interchanged with one another with respect to different orientations of layers, components, and substrates included in this disclosure. For example, in some embodiments, a first layer on a second layer means that the first layer is directly on top of and in contact with the second layer. In other embodiments, the first layer on the second layer can include another layer between them.

[0119] Headings are provided for the convenience of the reader, and the presence and / or placement of headings is not intended to limit the scope of the subject matter described herein.

[0120] Equivalent The systems, devices, methods, and processes of the present disclosure are considered to encompass variations and modifications developed using information from the embodiments described herein. Those skilled in the art may make modifications and / or variations to the systems, devices, methods, and processes described herein.

[0121] Specific embodiments of the present disclosure have been described above. However, it should be particularly noted that the present disclosure is not limited to those embodiments, but rather additions and modifications to those explicitly described in the present disclosure are intended to be included within the scope of the present disclosure. Moreover, it should be understood that the features of the various embodiments described in the present disclosure are not mutually exclusive, and may exist in various combinations and permutations, and such combinations or permutations are possible without departing from the spirit and scope of the present disclosure, even if not expressly indicated. Although the present disclosure has been described in detail with particular reference to specific embodiments thereof, it should be understood that variations and modifications can be made within the spirit and scope of the invention as claimed.

Claims

1. A positive electrode material comprising a mixture, wherein the mixture is A first active material comprising at least one electroactive sulfur material, The cathode material is a mixture of a second non-sulfur active material comprising a blend of two or more non-sulfur electroactive materials, wherein the blend is selected such that the discharge voltage profile of the blend has a voltage plateau that approximates the discharge voltage profile of the at least one electroactive sulfur material.

2. The cathode material according to claim 1, wherein the voltage profiles of the first active material and the second active material are measured separately under similar electrochemical conditions to evaluate whether they approximate each other.

3. The cathode material according to claim 1, wherein the blend of two or more non-sulfur electroactive materials has a discharge voltage profile characterized in that, for at least 50% of the total discharge, the discharge voltage attributable to the non-sulfur material in the blend is within 10% of the sulfur discharge voltage attributable to the at least one electroactive sulfur material.

4. The positive electrode material according to claim 1, wherein each of the two or more non-sulfur electroactive materials has its own discharge voltage profile, which includes a voltage plateau different from the voltage plateau of the other of the two or more non-sulfur electroactive materials.

5. The cathode material according to claim 1, wherein the blend of two or more non-sulfur electroactive materials comprises one or more chalcogenides.

6. The cathode material according to claim 5, wherein each of the two or more non-sulfur electroactive materials (i) has a different crystal structure, (ii) has a different composition, or (iii) is both (i) and (ii).

7. The cathode material according to claim 1, wherein the non-sulfur second active material has a discharge voltage profile with two plateaus.

8. The positive electrode material according to claim 1, wherein the non-sulfur second active material has a discharge voltage profile that approximates the discharge voltage profile from sulfur to lithium sulfide.

9. The discharge voltage profile, which has two plateaus, is approximately 2.2 to approximately 2.4 (V vs. Li / Li ＋ The first plateau in the range of ), and about 2.0 to about 2.2 (V vs. Li / Li ＋ The positive electrode material according to claim 7, having a second plateau in the range of ).

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

11. The core-shell structure each includes a core having a surrounding shell, and the core is made of the electroactive sulfur material (for example, S ８ Li ２ S ２ , and / or Li ２ The positive electrode material according to claim 10, comprising S), wherein the shell comprises at least one of the two or more non-sulfur electroactive materials.

12. The positive electrode material according to claim 10, wherein the core-shell structure has an average core diameter in the range of 50 to 300 nm and an average shell thickness in the range of 1 to 20 nm.

13. The positive electrode material according to claim 10, wherein the core-shell structure has at least 10% by mass of a non-sulfur electroactive material relative to sulfur.

14. A battery comprising: (i) a positive electrode containing the positive electrode material described in any one of claims 1 to 13; and (ii) an electrolyte in contact with the positive electrode.

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

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

17. A method for operating a lithium-sulfur battery having a positive electrode comprising (i) sulfur or lithium sulfide, (ii) a first non-sulfur electroactive material, and (iii) a second non-sulfur electroactive material different from the first non-sulfur electroactive material, The first voltage converts at least a portion of the sulfur or lithium sulfide at least partially, while simultaneously inserting lithium into the first non-sulfur electroactive material. The method further comprises discharging the battery by subsequently converting at least a portion of the sulfur in the lithium sulfide with a second voltage different from the first voltage, while simultaneously inserting lithium into the second non-sulfur electroactive material.

18. This includes discharging the battery and then charging the battery, and charging the battery is The method according to claim 17, wherein, at a third voltage, simultaneously comprises (i) removing lithium from the first non-sulfur electroactive material, (ii) removing lithium from the second non-sulfur electroactive material, and (iii) converting at least a portion of the sulfur or lithium sulfide at least partially.

19. A solid-state sulfur battery, The negative electrode and, Solid electrolytes, A solid sulfur battery comprising: a first active material comprising at least one electroactive sulfur material; and a positive electrode comprising one or more non-sulfur electroactive materials, wherein the discharge voltage profile of the one or more non-sulfur electroactive materials approximates at least a portion of the discharge voltage profile of the at least one electroactive sulfur material.

20. The battery according to claim 19, wherein the one or more non-sulfur electroactive materials are a blend of two or more non-sulfur electroactive materials, and the at least portion of the discharge voltage profile comprises two or more distinct portions, each of which corresponds to one of the two or more non-sulfur electroactive materials.

21. The battery according to claim 19, wherein the one or more non-sulfur electroactive materials include a mixed metal sulfide.

22. A positive electrode material comprising a mixture, wherein the mixture is At least one electroactive sulfur material, The positive electrode material is a mixture of at least one non-sulfur electroactive material which is a mixed metal chalcogenide, wherein the discharge voltage profile of the at least one non-sulfur electroactive material corresponds to the discharge voltage profile of the at least one electroactive sulfur material.

23. The positive electrode material according to claim 22, wherein the mixed metal chalcogenide is a mixed metal sulfide.

24. The cathode material according to claim 22, wherein the discharge voltage profile of the at least one non-sulfur electroactive material has a voltage plateau that approximates the voltage plateau of the at least one electroactive sulfur material, and the at least one non-sulfur electroactive material has a discharge voltage profile characterized in that, for at least 50% of the total discharge, the discharge voltage attributable to the at least one non-sulfur material is within 10% of the sulfur discharge voltage attributable to the at least one electroactive sulfur material.

25. A battery comprising: (i) a positive electrode containing the positive electrode material described in any one of claims 22 to 24; and (ii) an electrolyte in contact with the positive electrode.

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