Lithium-sulfur battery cell, electrolyte for lithium-sulfur battery cell, battery device, and electric device

Abstract

The application provides a lithium-sulfur battery monomer, an electrolyte for the lithium-sulfur battery monomer, a battery device and a power utilization device. The lithium-sulfur battery monomer comprises a negative electrode sheet and an electrolyte; the negative electrode sheet and / or the electrolyte comprises an ion cluster, and the ion cluster comprises an ammonium ion, and a sulfur ion and / or a lithium ion. The cycle performance of the lithium-sulfur battery monomer is obviously improved.

Description

Technical Field

[0001] This application relates to the field of battery technology, and in particular to a lithium-sulfur battery cell, an electrolyte for the lithium-sulfur battery cell, a battery device, and an electrical device. Background Technology

[0002] In recent years, with the increasingly wide range of applications, batteries have been widely used in energy storage power systems such as hydropower, thermal power, wind power, and solar power plants, as well as in power tools, electric bicycles, electric motorcycles, electric cars, military equipment, aerospace, and many other fields. Due to the significant advancements in battery technology, higher requirements have been placed on their cycle performance and other characteristics. Summary of the Invention

[0003] This application was made in view of the above-mentioned problems, and its purpose is to provide a lithium-sulfur battery cell, an electrolyte for the lithium-sulfur battery cell, a battery device, and an electrical device. The cycle performance of the lithium-sulfur battery cell in this application is significantly improved.

[0004] To achieve the above objectives, the first aspect of this application provides a lithium-sulfur battery cell, including a negative electrode and an electrolyte; the negative electrode and / or the electrolyte include ion clusters, the ion clusters including ammonium ions, sulfur ions and / or lithium ions.

[0005] In this application, ammonium ions in the electrolyte form ion clusters with the reduction products Li2S and Li2S2 on the negative electrode surface to dissolve Li2S and Li2S2. These ion clusters easily diffuse back to the positive electrode under the influence of an electric field and concentration difference and are oxidized again to long-chain lithium polysulfides. This inhibits the corrosion and passivation effects of Li2S and Li2S2 on the negative electrode, reduces negative electrode polarization, and reduces the consumption of positive electrode active materials, thereby improving the cycle performance of the battery cell.

[0006] In any embodiment, the average diameter of the ion cluster is 3-4 nm.

[0007] Therefore, on the one hand, it is beneficial for ammonium ions to form ion clusters with Li2S and Li2S2 on the negative electrode surface to dissolve Li2S and Li2S2, thereby inhibiting the corrosion and passivation of the negative electrode by Li2S and Li2S2. On the other hand, it is beneficial to suppress the side reactions between ammonium ions and the active material of the negative electrode.

[0008] In any embodiment, the ion clusters are electrically neutral.

[0009] In any embodiment, the ion clusters include ammonium ions, sulfide ions, and optionally lithium ions.

[0010] In any embodiment, the ion cluster includes Li x (NH4) yS z Where x≥0, y>0 and x+y=2, 0 <z≤2。

[0011] In any embodiment, the ion cluster includes Li 0.5 (NH4) 1.5 S, Li(NH4)S, (NH4)2S, Li 0.5 (NH4) 1.5 One or more of S2, Li(NH4)S2, and (NH4)2S2.

[0012] Therefore, the ion clusters formed by ammonium ions in the electrolyte and Li2S and Li2S2 on the negative electrode surface include the above-mentioned compounds, indicating that the ion clusters can promote the dissolution of Li2S and Li2S2 on the negative electrode surface, thereby inhibiting the corrosion and passivation of the negative electrode by Li2S and Li2S2, reducing the formation of dead sulfur, and improving the cycle performance of the battery cell.

[0013] In any embodiment, the electrolyte comprises a compound containing ammonium ions.

[0014] In any embodiment, the molar concentration of the ammonium ion in the electrolyte is 0.01-0.1M.

[0015] Therefore, on the one hand, it is beneficial for ammonium ions to form ion clusters with Li2S and Li2S2 on the negative electrode surface to dissolve Li2S and Li2S2, thereby inhibiting the corrosion and passivation of the negative electrode by Li2S and Li2S2. On the other hand, it is beneficial to inhibit the oxidation of ammonium ions, thereby reducing the consumption of active ions and improving the cycle performance of battery cells.

[0016] In any embodiment, the electrolyte comprises a compound containing nitrate ions.

[0017] Therefore, nitrate ions in the electrolyte of this application can form a stable SEI film with high ionic conductivity on the negative electrode surface, reducing negative electrode polarization and further improving the cycle performance of the battery cell.

[0018] In any embodiment, the molar concentration of the nitrate ions in the electrolyte is 0.01-0.1M.

[0019] Therefore, on the one hand, it is beneficial for nitrate ions in the electrolyte to form a stable SEI film with high ionic conductivity on the negative electrode surface, thereby improving the cycle performance of the battery cell; on the other hand, it is beneficial to suppress the side reactions of nitrate ions, reduce the consumption of active ions, and improve the cycle performance of the battery cell.

[0020] In any embodiment, the negative electrode includes one or more of lithium nitride, lithium oxide, and lithium nitride.

[0021] In any embodiment, the electrolyte comprises a compound containing metal ions, the metal ions including one or more of sodium, potassium, rubidium, cesium, and cerium.

[0022] Therefore, the specific metal ions in this application generate electrostatic shielding through the tip effect, causing these metal ions to preferentially deposit on the surface of lithium metal, resulting in more uniform deposition of lithium ions on the negative electrode surface, reducing the formation of lithium dendrites, and further improving the cycle performance of the battery cell.

[0023] In any embodiment, the molar concentration of the metal ion in the electrolyte is 0.01-0.1M.

[0024] Therefore, on the one hand, it is beneficial for the tip effect of the specific metal ions in this application to generate electrostatic shielding, so as to promote the uniform deposition of lithium ions along the negative electrode surface, suppress the formation of lithium dendrites, and improve the cycle performance of the battery cell; on the other hand, it can reduce the rise of the reduction potential of the specific metal ions, thereby suppressing the possible decline in the cycle performance of the battery cell that may be caused by the preferential deposition of more specific metal ions.

[0025] In any embodiment, the negative electrode sheet comprises one or more elements selected from sodium, potassium, rubidium, cesium, and cerium. This demonstrates that the specific metal ions of this application generate electrostatic shielding through a tip effect, which can promote uniform deposition of lithium ions on the negative electrode surface, suppress lithium dendrite formation, and thereby improve the cycle performance of the battery cell.

[0026] In any embodiment, the compound containing ammonium ions includes one or more of potassium ammonium nitrate, cerium ammonium nitrate, cesium ammonium nitrate, rubidium ammonium nitrate, ammonium nitrate, ammonium nitrite, ammonium iodide, ammonium sulfide, ammonium bromide, ammonium fluoride, ammonium chloride, diammonium pentasulfide, ammonium borate, and ammonium dihydrogen phosphate.

[0027] In any embodiment, the compound containing nitrate ions includes one or more of potassium ammonium nitrate, cerium ammonium nitrate, cesium ammonium nitrate, rubidium ammonium nitrate, ammonium nitrate, potassium nitrate, cerium nitrate, cesium nitrate, rubidium nitrate, lithium nitrate, and sodium nitrate.

[0028] In any embodiment, the metal ion-containing compound includes one or more of potassium ammonium nitrate, cerium ammonium nitrate, cesium ammonium nitrate, rubidium ammonium nitrate, potassium nitrate, cerium nitrate, cesium nitrate, rubidium nitrate, potassium fluoride, potassium chloride, potassium bromide, potassium iodide, cerium fluoride, cerium chloride, cerium bromide, cerium iodide, rubidium fluoride, rubidium chloride, rubidium bromide, and rubidium iodide.

[0029] In any embodiment, the electrolyte includes one or more additives selected from ammonium fluoride, ammonium nitrate, potassium ammonium nitrate, cerium ammonium nitrate, cesium ammonium nitrate, and rubidium ammonium nitrate.

[0030] Therefore, the ammonium ions in the electrolyte of this application form ion clusters with Li2S and Li2S2 on the negative electrode surface to dissolve Li2S and Li2S2, thereby inhibiting the corrosion and passivation effects of Li2S and Li2S2 on the negative electrode. Furthermore, the nitrate ions in the electrolyte can form a high-conductivity and stable SEI film on the negative electrode, reducing the polarization of the negative electrode. At the same time, specific metal ions in the electrolyte generate electrostatic shielding through the tip effect, preferentially depositing on the surface of metallic lithium, promoting the uniform deposition of lithium ions on the negative electrode, reducing the formation of lithium dendrites, and thus improving the cycle performance of the battery cell.

[0031] In any embodiment, the additive has a mass content of 0.05%-5% in the electrolyte.

[0032] In any embodiment, the electrolyte comprises an ether solvent and / or a diluent, wherein the ether solvent has a mass content of 5%-33% in the electrolyte, and / or the diluent has a mass content of 50%-85% in the electrolyte.

[0033] Therefore, the electrolyte composition described above in this application restricts the dissolution and diffusion of long-chain lithium polysulfides in the electrolyte, inhibits the migration of long-chain polysulfides to the negative electrode, reduces the total amount of reducible long-chain polysulfides on the negative electrode surface, and thus inhibits the capacity decay of the battery cell.

[0034] A second aspect of this application provides an electrolyte for lithium-sulfur battery cells, comprising ion clusters, said ion clusters including ammonium ions, sulfur ions and / or lithium ions.

[0035] Therefore, the ammonium ions in the electrolyte of this application form ion clusters with the reduction products Li2S and Li2S2 on the negative electrode surface to dissolve Li2S and Li2S2. The ion clusters can easily diffuse back to the positive electrode under the action of electric field and concentration difference and be oxidized again to long-chain lithium polysulfide, which inhibits the corrosion and passivation effect of Li2S and Li2S2 on the negative electrode, reduces the polarization of the negative electrode, reduces the consumption of positive electrode active material, and thus improves the cycle performance of the battery cell.

[0036] In any embodiment, the average diameter of the ion cluster is 3-4 nm.

[0037] In any embodiment, the ion clusters are electrically neutral.

[0038] In any embodiment, the ion clusters include ammonium ions, sulfide ions, and optionally lithium ions.

[0039] In any embodiment, the ion cluster includes Li x (NH4) y S zWhere x≥0, y>0 and x+y=2, 0 <z≤2。

[0040] In any embodiment, the ion cluster includes Li 0.5 (NH4) 1.5 S, Li(NH4)S, (NH4)2S, Li 0.5 (NH4) 1.5 One or more of S2, Li(NH4)S2, and (NH4)2S2.

[0041] In any embodiment, the electrolyte comprises a compound containing ammonium ions.

[0042] In any embodiment, the molar concentration of the ammonium ion in the electrolyte is 0.01-0.1M.

[0043] In any embodiment, the electrolyte comprises a compound containing nitrate ions.

[0044] In any embodiment, the molar concentration of the nitrate ions in the electrolyte is 0.01-0.1M.

[0045] In any embodiment, the electrolyte comprises a compound containing metal ions, the metal ions including one or more of sodium, potassium, rubidium, cesium, and cerium.

[0046] In any embodiment, the molar concentration of the metal ion in the electrolyte is 0.01-0.1M.

[0047] In any embodiment, the compound containing ammonium ions includes one or more of potassium ammonium nitrate, cerium ammonium nitrate, cesium ammonium nitrate, rubidium ammonium nitrate, ammonium nitrate, ammonium nitrite, ammonium iodide, ammonium sulfide, ammonium bromide, ammonium fluoride, ammonium chloride, diammonium pentasulfide, ammonium borate, and ammonium dihydrogen phosphate.

[0048] In any embodiment, the compound containing nitrate ions includes one or more of potassium ammonium nitrate, cerium ammonium nitrate, cesium ammonium nitrate, rubidium ammonium nitrate, ammonium nitrate, potassium nitrate, cerium nitrate, cesium nitrate, rubidium nitrate, lithium nitrate, and sodium nitrate.

[0049] In any embodiment, the metal ion-containing compound includes one or more of potassium ammonium nitrate, cerium ammonium nitrate, cesium ammonium nitrate, rubidium ammonium nitrate, potassium nitrate, cerium nitrate, cesium nitrate, rubidium nitrate, potassium fluoride, potassium chloride, potassium bromide, potassium iodide, cerium fluoride, cerium chloride, cerium bromide, cerium iodide, rubidium fluoride, rubidium chloride, rubidium bromide, and rubidium iodide.

[0050] In any embodiment, the electrolyte includes one or more additives selected from ammonium fluoride, ammonium nitrate, potassium ammonium nitrate, cerium ammonium nitrate, cesium ammonium nitrate, and rubidium ammonium nitrate.

[0051] In any embodiment, the additive has a mass content of 0.05%-5% in the electrolyte.

[0052] In any embodiment, the electrolyte comprises an ether solvent and / or a diluent, wherein the ether solvent has a mass content of 5%-33% in the electrolyte, and / or the diluent has a mass content of 50%-85% in the electrolyte.

[0053] A third aspect of this application provides a battery device, including a battery cell according to the first aspect of this application or an electrolyte according to the second aspect of this application.

[0054] The fourth aspect of this application provides an electrical device, including a battery cell of the first aspect of this application or a battery device of the third aspect of this application. Attached Figure Description

[0055] Figure 1 This is a schematic diagram of a battery cell according to one embodiment of this application.

[0056] Figure 2 yes Figure 1 An exploded view of a battery cell according to one embodiment of this application is shown.

[0057] Figure 3 This is a schematic diagram of a battery module according to one embodiment of this application.

[0058] Figure 4 This is a schematic diagram of a battery pack according to one embodiment of this application.

[0059] Figure 5 yes Figure 4 An exploded view of a battery pack according to one embodiment of this application is shown.

[0060] Figure 6 This is a schematic diagram of an electrical device in which a single battery cell is used as a power source according to one embodiment of this application.

[0061] Explanation of reference numerals in the attached figures:

[0062] 1 Battery pack; 2 Upper housing; 3 Lower housing; 4 Battery module; 5 Battery cell; 51 Housing; 52 Electrode assembly; 53 Top cover assembly. Detailed Implementation

[0063] The following detailed description, with appropriate reference to the accompanying drawings, specifically discloses embodiments of the battery cell, battery module, battery pack, and power-consuming device of this application. However, unnecessary detailed descriptions may be omitted. For example, detailed descriptions of well-known matters and repetitive descriptions of practically identical structures may be omitted. This is to avoid unnecessarily lengthy descriptions and to facilitate understanding by those skilled in the art. Furthermore, the accompanying drawings and the following description are provided to enable those skilled in the art to fully understand this application and are not intended to limit the subject matter of the claims.

[0064] Unless otherwise specified, all embodiments and optional embodiments of this application can be combined to form new technical solutions.

[0065] Unless otherwise specified, all technical features and optional technical features of this application may be combined to form new technical solutions.

[0066] Unless otherwise specified, all steps of this application may be performed sequentially or randomly, preferably sequentially. For example, the method includes steps (a) and (b), indicating that the method may include steps (a) and (b) performed sequentially, or it may include steps (b) and (a) performed sequentially. For example, the mention that the method may also include step (c) indicates that step (c) may be added to the method in any order; for example, the method may include steps (a), (b), and (c), or it may include steps (a), (c), and (b), or it may include steps (c), (a), and (b), etc.

[0067] [Battery cell]

[0068] In this embodiment of the application, the battery cell can be a secondary battery, which refers to a battery cell that can be recharged to activate the active materials and continue to be used after the battery cell has been discharged.

[0069] The battery cells can be lithium-sulfur batteries, etc.

[0070] A single battery cell typically includes an electrode assembly. The electrode assembly includes a positive electrode, a negative electrode, and a separator, with the separator positioned between the positive and negative electrodes. During the charging and discharging process of a single battery cell, active ions (such as lithium ions) repeatedly insert and extract between the positive and negative electrodes. The separator, positioned between the positive and negative electrodes, prevents short circuits while allowing active ions to pass through.

[0071] In lithium-sulfur batteries, long-chain lithium polysulfides dissolve in the electrolyte and migrate to the negative electrode surface, where they are reduced to Li2S or Li2S2. However, Li2S or Li2S2 corrodes the lithium metal at the negative electrode. Furthermore, Li2S and Li2S2 are insulators of electrons and ions, which easily passivate the lithium metal surface and consume the positive electrode active material to produce dead sulfur, leading to a rapid capacity decay of lithium-sulfur batteries.

[0072] To address the aforementioned technical problems, one embodiment of this application provides a lithium-sulfur battery cell, comprising a negative electrode and an electrolyte; the negative electrode and / or the electrolyte comprises ion clusters, the ion clusters comprising ammonium ions, sulfur ions and / or lithium ions.

[0073] As a result, the applicant unexpectedly discovered that: the ammonium ions in the electrolyte of this application form ion clusters with the reduction products Li2S and Li2S2 on the negative electrode surface to dissolve Li2S and Li2S2. The ion clusters are easily diffused back to the positive electrode under the action of electric field and concentration difference and are oxidized again to long-chain lithium polysulfides, which inhibits the corrosion and passivation effect of Li2S and Li2S2 on the negative electrode, reduces the polarization of the negative electrode, reduces the consumption of positive electrode active material, and thus improves the cycle performance of the battery cell.

[0074] In some embodiments, the average diameter of the ion cluster is 3-4 nm, for example, 3 nm, 3.5 nm, 4 nm or any combination of the above values.

[0075] Therefore, on the one hand, it is beneficial for ammonium ions to form ion clusters with Li2S and Li2S2 on the negative electrode surface to dissolve Li2S and Li2S2, thereby inhibiting the corrosion and passivation of the negative electrode by Li2S and Li2S2. On the other hand, it is beneficial to suppress the side reactions between ammonium ions and the active material of the negative electrode.

[0076] In some embodiments, the ion clusters are electrically neutral.

[0077] This application employs conventional methods in the art to detect the charge state of ion clusters, such as using a typical charge detector.

[0078] In some embodiments, the ion clusters include ammonium ions, sulfide ions, and optionally lithium ions.

[0079] In some embodiments, the ion clusters include Li x (NH4) y S zWhere x ≥ 0 (e.g., 0, 0.5, 0.8, 1, 1.3, 1.5, 1.6, 1.8, 1.9, or any range of the above values), y > 0 (e.g., 0.1, 0.3, 0.4, 0.5, 0.8, 1, 1.3, 1.5, 1.6, 1.8, 1.9, or any range of the above values) and x + y = 2, 0 <z≤2。

[0080] In some embodiments (e.g., 0.1, 0.3, 0.4, 0.5, 0.8, 1, 1.3, 1.5, 1.6, 1.8, 1.9, 2, or any range of the above values), the ion clusters include Li 0.5 (NH4) 1.5 S, Li(NH4)S, (NH4)2S, Li 0.5 (NH4) 1.5 One or more of S2, Li(NH4)S2, and (NH4)2S2.

[0081] Therefore, the ion clusters formed by ammonium ions in the electrolyte and Li2S and Li2S2 on the negative electrode surface include the above-mentioned compounds, indicating that the ion clusters can promote the dissolution of Li2S and Li2S2 on the negative electrode surface, thereby inhibiting the corrosion and passivation of the negative electrode by Li2S and Li2S2, reducing the formation of dead sulfur, and improving the cycle performance of the battery cell.

[0082] In some embodiments, the electrolyte comprises a compound containing ammonium ions.

[0083] In some embodiments, the molar concentration of the ammonium ion in the electrolyte is 0.01-0.1M, for example, 0.01M, 0.02M, 0.03M, 0.04M, 0.05M, 0.06M, 0.07M, 0.08M, 0.09M, 0.1M, or any range of the above values.

[0084] Therefore, on the one hand, it is beneficial for ammonium ions to form ion clusters with Li2S and Li2S2 on the negative electrode surface to dissolve Li2S and Li2S2, thereby inhibiting the corrosion and passivation of the negative electrode by Li2S and Li2S2. On the other hand, it is beneficial to inhibit the oxidation of ammonium ions, thereby reducing the consumption of active ions and improving the cycle performance of battery cells.

[0085] In some embodiments, the electrolyte comprises a compound containing nitrate ions.

[0086] Therefore, nitrate ions in the electrolyte of this application can form a stable SEI film with high ionic conductivity on the negative electrode surface, reducing negative electrode polarization and further improving the cycle performance of the battery cell.

[0087] In some embodiments, the molar concentration of the nitrate ions in the electrolyte is 0.01-0.1M, for example, 0.01M, 0.02M, 0.03M, 0.04M, 0.05M, 0.06M, 0.07M, 0.08M, 0.09M, 0.1M, or any range of the above values.

[0088] Therefore, on the one hand, it is beneficial for nitrate ions in the electrolyte to form a stable SEI film with high ionic conductivity on the negative electrode surface, thereby improving the cycle performance of the battery cell; on the other hand, it is beneficial to suppress the side reactions of nitrate ions, reduce the consumption of active ions, and improve the cycle performance of the battery cell.

[0089] In some embodiments, the negative electrode includes one or more of lithium nitride, lithium oxide, and lithium nitride.

[0090] In some embodiments, the electrolyte comprises a compound containing metal ions, including one or more ions selected from sodium, potassium, rubidium, cesium, and cerium.

[0091] Therefore, the specific metal ions in this application generate electrostatic shielding through the tip effect, causing these metal ions to preferentially deposit on the surface of lithium metal, resulting in more uniform deposition of lithium ions on the negative electrode surface, reducing the formation of lithium dendrites, and further improving the cycle performance of the battery cell.

[0092] In some embodiments, the molar concentration of the metal ion in the electrolyte is 0.01-0.1M, for example, 0.01M, 0.02M, 0.03M, 0.04M, 0.05M, 0.06M, 0.07M, 0.08M, 0.09M, 0.1M, or any range of the above values.

[0093] Therefore, on the one hand, it is beneficial for the tip effect of the specific metal ions in this application to generate electrostatic shielding, so as to promote the uniform deposition of lithium ions along the negative electrode surface, suppress the formation of lithium dendrites, and improve the cycle performance of the battery cell; on the other hand, it can reduce the rise of the reduction potential of the specific metal ions, thereby suppressing the possible decline in the cycle performance of the battery cell that may be caused by the preferential deposition of more specific metal ions.

[0094] In some embodiments, the negative electrode includes one or more elements selected from sodium, potassium, rubidium, cesium, and cerium. This demonstrates that the specific metal ions of this application generate electrostatic shielding through a tip effect, which can promote uniform deposition of lithium ions on the negative electrode surface, suppress lithium dendrite formation, and thereby improve the cycle performance of the battery cell.

[0095] In some embodiments, the ammonium-containing compound includes one or more of potassium ammonium nitrate, cerium ammonium nitrate, cesium ammonium nitrate, rubidium ammonium nitrate, ammonium nitrate, ammonium nitrite, ammonium iodide, ammonium sulfide, ammonium bromide, ammonium fluoride, ammonium chloride, diammonium pentasulfide, ammonium borate, and ammonium dihydrogen phosphate.

[0096] In some embodiments, the compound containing nitrate ions includes one or more of potassium ammonium nitrate, cerium ammonium nitrate, cesium ammonium nitrate, rubidium ammonium nitrate, ammonium nitrate, potassium nitrate, cerium nitrate, cesium nitrate, rubidium nitrate, lithium nitrate, and sodium nitrate.

[0097] In some embodiments, the metal ion-containing compound includes one or more of potassium ammonium nitrate, cerium ammonium nitrate, cesium ammonium nitrate, rubidium ammonium nitrate, potassium nitrate, cerium nitrate, cesium nitrate, rubidium nitrate, potassium fluoride, potassium chloride, potassium bromide, potassium iodide, cerium fluoride, cerium chloride, cerium bromide, cerium iodide, rubidium fluoride, rubidium chloride, rubidium bromide, and rubidium iodide.

[0098] In some embodiments, the electrolyte includes one or more additives selected from ammonium fluoride (NH4F), ammonium nitrate (NH4NO3), potassium ammonium nitrate, cerium ammonium nitrate, cesium ammonium nitrate, and rubidium ammonium nitrate.

[0099] Therefore, the ammonium ions in the electrolyte of this application form ion clusters with Li2S and Li2S2 on the negative electrode surface to dissolve Li2S and Li2S2, thereby inhibiting the corrosion and passivation effects of Li2S and Li2S2 on the negative electrode. Furthermore, the nitrate ions in the electrolyte can form a high-conductivity and stable SEI film on the negative electrode, reducing the polarization of the negative electrode. At the same time, specific metal ions in the electrolyte generate electrostatic shielding through the tip effect, preferentially depositing on the surface of metallic lithium, promoting the uniform deposition of lithium ions on the negative electrode, reducing the formation of lithium dendrites, and thus improving the cycle performance of the battery cell.

[0100] In some embodiments, potassium ammonium nitrate has the chemical formula NH4K(NO3)2.

[0101] In some embodiments, the chemical formula of cerium ammonium nitrate is (NH4)2Ce(NO3)6.

[0102] In some embodiments, the chemical formula of ammonium cesium nitrate is NH4Cs(NO3)2.

[0103] In some embodiments, the chemical formula of ammonium rubidium nitrate is NH4Rb(NO3)2.

[0104] In some embodiments, the additive is present in the electrolyte at a mass content of 0.05%-5%, for example, 0.05%, 0.5%, 0.8%, 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, 5%, or any combination of the above values.

[0105] In some embodiments, the electrolyte comprises an ether solvent and / or a diluent, wherein: the ether solvent contains 5%-33% by mass in the electrolyte (e.g., 5%, 6%, 8%, 9%, 10%, 12%, 14%, 15%, 17%, 19%, 20%, 22%, 24%, 25%, 26%, 28%, 29%, 30%, 31%, 33% or any range of the above values), and / or the diluent contains 50%-85% by mass in the electrolyte (50%, 53%, 55%, 57%, 59%, 60%, 63%, 65%, 67%, 68%, 70%, 72%, 74%, 75%, 76%, 78%, 79%, 80%, 81%, 83%, 84%, 85% or any range of the above values).

[0106] Therefore, the electrolyte composition described above in this application enables the dissolution and diffusion of long-chain lithium polysulfides in the electrolyte, inhibits the migration of long-chain polysulfides to the negative electrode, reduces the total amount of reducible long-chain polysulfides on the negative electrode surface, and thus suppresses the capacity decay of the battery cell.

[0107]

Positive Electrode

[0108] In some embodiments, the positive electrode can be a positive electrode sheet, which may include a positive current collector and a positive active material disposed on at least one surface of the positive current collector.

[0109] As an example, the positive current collector has two surfaces opposite each other in its own thickness direction, and the positive active material is disposed on either or both of the two opposite surfaces of the positive current collector.

[0110] As an example, the positive current collector can be a metal foil, a conductive polymer material, a carbon material, or a composite current collector. For example, as a metal foil, pure metals, alloys, or surface-treated metals can be used, including but not limited to stainless steel, copper, aluminum, nickel, titanium, or silver. The composite current collector may include a polymer material base layer and a metal layer. The composite current collector can be formed by forming a metal material (aluminum, aluminum alloys, nickel, nickel alloys, titanium, titanium alloys, silver, and silver alloys, etc.) on a polymer material substrate (such as a substrate of polypropylene, polyethylene terephthalate, polybutylene terephthalate, polystyrene, polyethylene, etc.).

[0111] As an example, the positive electrode active material may include at least one of the following materials: elemental sulfur, sulfur-carbon composites, and their respective modified compounds. However, this application is not limited to these materials, and other conventional materials that can be used as battery positive electrode active materials may also be used, such as lithium phosphates and lithium transition metal oxides. These positive electrode active materials may be used alone or in combination of two or more. Examples of lithium phosphates include, but are not limited to, at least one of lithium iron phosphate (such as LiFePO4 (also referred to as LFP)), lithium iron phosphate and carbon composites, lithium manganese phosphate (such as LiMnPO4), lithium manganese phosphate and carbon composites, lithium iron manganese phosphate, and lithium iron manganese phosphate and carbon composites. Examples of lithium transition metal oxides include, but are not limited to, lithium cobalt oxide (such as LiCoO2), lithium nickel oxide (such as LiNiO2), lithium manganese oxide (such as LiMnO2, LiMn2O4), lithium nickel cobalt oxide, lithium manganese cobalt oxide, lithium nickel manganese oxide, and lithium nickel cobalt manganese oxide (such as LiNi). 1 / 3Co 1 / 3 Mn 1 / 3 O2 (also known as NCM) 333 LiNi 0.5 Co 0.2 Mn 0.3 O2 (also known as NCM) 523 LiNi 0.5 Co 0.25 Mn 0.25 O2 (also known as NCM) 211 LiNi 0.6 Co 0.2 Mn 0.2 O2 (also known as NCM) 622 LiNi 0.8 Co 0.1 Mn 0.1 O2 (also known as NCM) 811 ), lithium nickel cobalt aluminum oxide (such as LiNi) 0.8 Co 0.15 Al 0.05 At least one of O2 and its modified compounds. Modified compounds refer to substances obtained by modification methods such as doping or coating based on the above-mentioned substances.

[0112] During the charging and discharging process of a battery, Li undergoes insertion / extraction and consumption, resulting in varying molar Li content at different discharge states. In the examples of cathode materials in this application, the molar Li content refers to the initial state of the material, i.e., the state before feeding. When the cathode material is applied to the battery system, the molar Li content changes after charge-discharge cycles.

[0113] In the examples of cathode materials in this application, the molar content of O is only a theoretical value. Oxygen release from the crystal lattice will cause changes in the molar content of oxygen, and the actual molar content of O will fluctuate.

[0114] In some embodiments, the positive electrode film layer may optionally include a binder. As an example, the binder may include at least one of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), PVDF-tetrafluoroethylene-propylene terpolymer, PVDF-hexafluoropropylene-tetrafluoroethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer, and fluorinated acrylate resin.

[0115] In some embodiments, the positive electrode film may optionally include a conductive agent. As an example, the conductive agent may include at least one selected from superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0116] In some embodiments, the positive electrode sheet can be prepared by dispersing the above-mentioned components for preparing the positive electrode sheet, such as positive active material, conductive agent, binder and any other components, in a solvent (e.g., N-methylpyrrolidone) to form a positive electrode slurry; coating the positive electrode slurry onto the positive electrode current collector, and then obtaining the positive electrode sheet after drying, cold pressing and other processes.

[0117] [Negative electrode plate]

[0118] In some embodiments, the negative electrode can be a negative electrode sheet, and the negative electrode sheet can include a negative current collector.

[0119] As an example, the negative electrode current collector can be a metal foil, a conductive polymer material, a carbon material, or a composite current collector. For example, as a metal foil, pure metals, alloys, or surface-treated metals can be used, including but not limited to stainless steel, copper, aluminum, nickel, titanium, or silver. The composite current collector may include a polymer material substrate and a metal layer. The composite current collector can be formed by forming a metal material (copper, copper alloys, nickel, nickel alloys, titanium, titanium alloys, silver, and silver alloys, etc.) on a polymer material substrate (such as a substrate of polypropylene, polyethylene terephthalate, polybutylene terephthalate, polystyrene, polyethylene, etc.).

[0120] As an example, the negative electrode sheet may include a negative electrode current collector and a negative electrode active material disposed on at least one surface of the negative electrode current collector.

[0121] As an example, the negative electrode current collector has two surfaces opposite each other in its own thickness direction, and the negative electrode active material is disposed on either or both of the two opposite surfaces of the negative electrode current collector.

[0122] As an example, the negative electrode active material may be lithium metal and its modified compounds. However, this application is not limited to these materials and may further include other conventional materials that can be used as battery negative electrode active materials, such as artificial graphite, natural graphite, soft carbon, hard carbon, silicon-based materials, tin-based materials, and lithium titanate. Silicon-based materials may be selected from at least one of elemental silicon, silicon oxide compounds, silicon-carbon composites, silicon-nitrogen composites, and silicon alloys. Tin-based materials may be selected from at least one of elemental tin, tin oxide compounds, and tin alloys. These negative electrode active materials may be used alone or in combination of two or more.

[0123] As an example, negative electrode active materials can be filled or / and deposited within the negative electrode current collector.

[0124] In some embodiments, the positive current collector can be made of aluminum, and the negative current collector can be made of copper.

[0125] In some embodiments, the negative electrode film layer may optionally include a binder. As an example, the binder may be selected from at least one of styrene-butadiene rubber (SBR), polyacrylic acid (PAA), sodium polyacrylate (PAAS), polyacrylamide (PAM), polyvinyl alcohol (PVA), sodium alginate (SA), polymethacrylic acid (PMAA), and carboxymethyl chitosan (CMCS).

[0126] In some embodiments, the negative electrode film may optionally include a conductive agent. As an example, the conductive agent may be selected from at least one of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0127] In some embodiments, the negative electrode film may optionally include other additives, such as thickeners (e.g., sodium carboxymethyl cellulose (CMC-Na)).

[0128] In some embodiments, the negative electrode sheet can be prepared by dispersing the components used to prepare the negative electrode sheet, such as the negative electrode active material, conductive agent, binder and any other components, in a solvent (e.g., deionized water) to form a negative electrode slurry; coating the negative electrode slurry onto the negative electrode current collector, and then obtaining the negative electrode sheet after drying, cold pressing and other processes.

[0129] Electrolytes

[0130] In some embodiments, the battery cell also includes an electrolyte, which acts as a conductor of ions between the positive and negative electrodes. This application does not impose specific limitations on the type of electrolyte; it can be selected according to requirements. The electrolyte can be liquid, gel, or solid.

[0131] One embodiment of the present application provides an electrolyte for a lithium-sulfur battery monomer, which includes ionic clusters, and the ionic clusters include ammonium ions, and sulfide ions and / or lithium ions.

[0132] Thus, the ammonium ions in the electrolyte of the present application form ionic clusters with the reduction products Li2S and Li2S2 on the surface of the negative electrode to dissolve Li2S and Li2S2. The ionic clusters are easily diffused back to the positive electrode and oxidized into long-chain polysulfides again under the action of an electric field and a concentration difference, inhibiting the corrosion and passivation of Li2S and Li2S2 on the negative electrode, reducing the polarization of the negative electrode, reducing the consumption of the positive electrode active material, and thus improving the cycle performance of the battery monomer.

[0133] In some embodiments, the average diameter of the ionic clusters is 3-4 nm, such as 3 nm, 3.5 nm, 4 nm or a range composed of any of the above values.

[0134] In some embodiments, the ionic clusters are electrically neutral.

[0135] In some embodiments, the ionic clusters include ammonium ions, sulfide ions and optional lithium ions.

[0136] In some embodiments, the ionic clusters include Li x (NH4) y S z , where x≥0 (such as 0, 0.5, 0.8, 1, 1.3, 1.5, 1.6, 1.8, 1.9 or a range composed of any of the above values), y>0 (such as 0.1, 0.3, 0.4, 0.5, 0.8, 1, 1.3, 1.5, 1.6, 1.8, 1.9 or a range composed of any of the above values) and x + y = 2, 0 < z ≤ 2 (such as 0.1, 0.3, 0.4, 0.5, 0.8, 1, 1.3, 1.5, 1.6, 1.8, 1.9, 2 or a range composed of any of the above values).

[0137] In some embodiments, the ionic clusters include Li 0.5 (NH4) 1.5 S, Li(NH4)S, (NH4)2S, Li 0.5 (NH4) 1.5 S2, Li(NH4)S2, (NH4)2S2 or one or more of them.

[0138] In some embodiments, the electrolyte includes a compound containing ammonium ions.

[0139] In some embodiments, the molar concentration of the ammonium ion in the electrolyte is 0.01-0.1M, for example, 0.01M, 0.02M, 0.03M, 0.04M, 0.05M, 0.06M, 0.07M, 0.08M, 0.09M, 0.1M, or any range of the above values.

[0140] In some embodiments, the electrolyte comprises a compound containing nitrate ions.

[0141] In some embodiments, the molar concentration of the nitrate ions in the electrolyte is 0.01-0.1M, for example, 0.01M, 0.02M, 0.03M, 0.04M, 0.05M, 0.06M, 0.07M, 0.08M, 0.09M, 0.1M, or any range of the above values.

[0142] In some embodiments, the electrolyte comprises a compound containing metal ions, including one or more ions selected from sodium, potassium, rubidium, cesium, and cerium.

[0143] In some embodiments, the molar concentration of the metal ion in the electrolyte is 0.01-0.1M, for example, 0.01M, 0.02M, 0.03M, 0.04M, 0.05M, 0.06M, 0.07M, 0.08M, 0.09M, 0.1M, or any range of the above values.

[0144] In some embodiments, the ammonium-containing compound includes one or more of potassium ammonium nitrate, cerium ammonium nitrate, cesium ammonium nitrate, rubidium ammonium nitrate, ammonium nitrate, ammonium nitrite, ammonium iodide, ammonium sulfide, ammonium bromide, ammonium fluoride, ammonium chloride, diammonium pentasulfide, ammonium borate, and ammonium dihydrogen phosphate.

[0145] In some embodiments, the compound containing nitrate ions includes one or more of potassium ammonium nitrate, cerium ammonium nitrate, cesium ammonium nitrate, rubidium ammonium nitrate, ammonium nitrate, potassium nitrate, cerium nitrate, cesium nitrate, rubidium nitrate, lithium nitrate, and sodium nitrate.

[0146] In some embodiments, the metal ion-containing compound includes one or more of potassium ammonium nitrate, cerium ammonium nitrate, cesium ammonium nitrate, rubidium ammonium nitrate, potassium nitrate, cerium nitrate, cesium nitrate, rubidium nitrate, potassium fluoride, potassium chloride, potassium bromide, potassium iodide, cerium fluoride, cerium chloride, cerium bromide, cerium iodide, rubidium fluoride, rubidium chloride, rubidium bromide, and rubidium iodide.

[0147] In some embodiments, the electrolyte includes one or more additives selected from ammonium fluoride (NH4F), ammonium nitrate (NH4NO3), potassium ammonium nitrate, cerium ammonium nitrate, cesium ammonium nitrate, and rubidium ammonium nitrate.

[0148] In some embodiments, the additive is present in the electrolyte at a mass content of 0.05%-5%, for example, 0.05%, 0.5%, 0.8%, 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, 5%, or any combination of the above values.

[0149] In some embodiments, the liquid electrolyte includes an electrolyte salt, an ether solvent, and / or a diluent.

[0150] In some embodiments, the ether solvent in the electrolyte has a mass content of 5%-33% (e.g., 5%, 6%, 8%, 9%, 10%, 12%, 14%, 15%, 17%, 19%, 20%, 22%, 24%, 25%, 26%, 28%, 29%, 30%, 31%, 33% or any range of the above values), and / or the diluent in the electrolyte has a mass content of 50%-85% (50%, 53%, 55%, 57%, 59%, 60%, 63%, 65%, 67%, 68%, 70%, 72%, 74%, 75%, 76%, 78%, 79%, 80%, 81%, 83%, 84%, 85% or any range of the above values).

[0151] In some embodiments, the electrolyte salt may be selected from one or more of lithium bis(fluorosulfonyl)imide (LiFSI), lithium hexafluorophosphate (LiPF6), lithium tetrafluoroborate (LiBF4), lithium hexafluoroarsenate (LiAsF6), lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), lithium trifluoromethanesulfonate (LiOTF), lithium difluorophosphate (LiDFP), lithium dioxolaneborate (LiBOB), lithium difluorooxolaneborate (LiDFOB), lithium difluorodioxolane phosphate, and lithium tetrafluorooxolane phosphate.

[0152] In some embodiments, the ether solvent may be selected from one or more of diethyl ether, dipropyl ether, ethylpropyl ether, methyl butyl ether, dibutyl ether, ethyl butyl ether, ethylene glycol dimethyl ether (DME), ethylene glycol diethyl ether, ethylene glycol methyl ethyl ether, ethylene glycol diethyl ether, ethylene glycol dipropyl ether, ethylene glycol dibutyl ether, propylene glycol dimethyl ether, propylene glycol methyl ethyl ether, propylene glycol diethyl ether, butanediol dimethyl ether, butanediol methyl ethyl ether, butanediol diethyl ether, tetrahydrofuran, 3-methyltetrahydrofuran, 1,3-dioxopentane, tetrahydropyran, 1,3-dioxane, and 1,4-dioxane.

[0153] In some embodiments, the diluent may be selected from benzene (B2), fluorobenzene, p-difluorobenzene, m-difluorobenzene, o-difluorobenzene, trifluorotoluene, trifluoromethoxybenzene, decafluoropentane, 1,1,2,2-tetrafluoroethyl-2,2,3,3-tetrafluoropropyl ether (TTE), 1,2-dimethoxy-1,1,2,2-tetrafluoroethane, 1,2-bis(difluoromethoxy)ethane, 1,2-bis(trifluoromethoxy)ethane, 1,2-diethoxy-1,1,2,2-tetrafluoroethane, 1,2-bis(1,1,2,2-tetrafluoroethoxy)ethane, bis(2,2,2-trifluoroethyl) ether, bis(2,2-difluoro... One or more of the following: ethyl ether, 1,1,2,3,3,3-hexafluoropropyl ethyl ether, 1H,1H,5H-octafluoropentyl-1,1,2,2-tetrafluoroethyl ether, ethyl trifluoromethyl ether, difluoromethyl-2,2,3,3,3-pentafluoropropyl ether, heptafluoropropyl-1,2,2,2-tetrafluoroethyl ether, difluoromethyl 2,2,3,3-tetrafluoropropyl ether, perfluoroisopropylmethyl ether, 1,1,2,2-tetrafluoroethyl-2,2,2-trifluoroethyl ether, ethyl-1,1,2,2-tetrafluoroethyl ether, ethyl-2,2,2-tetrafluoroethyl ether, and bis(1,1,2,2-tetrafluoroethyl) ether.

[0154] In some embodiments, the electrolyte may optionally include additives. For example, additives may include negative electrode film-forming additives, positive electrode film-forming additives, and additives that can improve certain properties of the battery cell, such as additives that improve the overcharge / fast charge performance of the battery cell, additives that improve the high-temperature performance of the battery cell, and additives that improve the low-temperature performance of the battery cell.

[0155] The gel electrolyte includes a polymer as a backbone network and can be used in conjunction with an ionic liquid-lithium salt.

[0156] Solid electrolytes include polymer solid electrolytes, inorganic solid electrolytes, and composite solid electrolytes.

[0157] As an example, the polymers of polymeric solid electrolytes may include polyethers (polyoxyethylene), polysiloxanes, polycarbonates, polyacrylonitrile, polyvinylidene fluoride, polymethyl methacrylate, monoionic polymers, polyionic liquids, cellulose, etc.

[0158] As an example, inorganic solid electrolytes can be one or more of the following: oxide solid electrolytes (crystalline perovskite, sodium superconducting ion conductor, garnet, amorphous LiPON thin film), sulfide solid electrolytes (crystalline lithium superconducting ion conductor (lithium-germanium-phosphorus-sulfur, sulfosilium-germanium), amorphous sulfides), halide solid electrolytes, nitride solid electrolytes, and hydride solid electrolytes.

[0159] As an example, composite solid electrolytes are formed by adding inorganic solid electrolyte fillers to polymer solid electrolytes.

[0160]

Isolation Components

[0161] In some embodiments, the electrode assembly further includes an isolator disposed between the positive and negative electrodes.

[0162] In some embodiments, the separator is a separator membrane. This application does not impose any particular limitation on the type of separator membrane; any known porous separator membrane with good chemical and mechanical stability can be selected.

[0163] As an example, the main material of the separator can be selected from at least one of glass fiber, non-woven fabric, polyethylene, polypropylene, polyimide porous membrane, polyvinylidene fluoride, and ceramic. The separator can be a single-layer film or a multi-layer composite film, without particular limitation. When the separator is a multi-layer composite film, the materials of each layer can be the same or different, without particular limitation. The separator can be a single component located between the positive and negative electrodes, or it can be attached to the surfaces of the positive and negative electrodes. An inorganic particle coating, an organic particle coating, or an organic / inorganic composite coating can also be applied to the surface of the separator.

[0164] In some embodiments, the separator is a solid electrolyte. The solid electrolyte is disposed between the positive and negative electrodes, serving both to transport ions and to isolate the positive and negative electrodes.

[0165] In some implementations, the positive electrode, negative electrode, and separator can be fabricated into an electrode assembly using a winding or stacking process.

[0166] [Structure of the Electrode Assembly]

[0167] The electrode assembly can be a wound structure, a stacked structure, or a hybrid structure of wound and stacked.

[0168] In some implementations, the electrode assembly is a wound structure. The positive and negative electrode sheets are wound into a wound structure.

[0169] In some implementations, the electrode assembly is a stacked structure.

[0170] As an example, multiple positive and negative electrodes can be set, and multiple positive and multiple negative electrodes can be stacked alternately.

[0171] As an example, multiple positive electrode plates can be provided, and negative electrode plates can be folded to form multiple stacked folded segments, with a positive electrode plate sandwiched between adjacent folded segments.

[0172] As an example, both the positive and negative electrode plates are folded to form multiple stacked folded segments.

[0173] As an example, multiple separators can be provided, each positioned between any adjacent positive or negative electrode plates.

[0174] As an example, the separators can be continuously arranged, either by folding or rolling between any adjacent positive or negative electrode plates.

[0175] In some embodiments, the electrode assembly can be cylindrical, flat, or polygonal, etc.

[0176] In some embodiments, the electrode assembly is provided with tabs that allow current to be drawn from the electrode assembly. The tabs include a positive tab and a negative tab.

[0177]

shell

[0178] In some embodiments, the battery cell may include a casing. The casing may be a steel casing, an aluminum casing, a plastic casing (such as a polypropylene casing), a composite metal casing (such as a copper-aluminum composite casing), or an aluminum-plastic film, etc. In some embodiments, the casing may be a sealed structure or a non-sealed structure. As an example, when the casing is a non-sealed structure, the casing serves to protect the electrode assembly, and a sealing bag is included between the casing and the electrode assembly to encapsulate the electrode assembly and electrolyte. Specifically, the sealing bag may be a bag-shaped insulating component or an aluminum-plastic film. When the casing is a sealed structure, it is used to encapsulate components such as the electrode assembly and electrolyte.

[0179] As an example, the battery cell can be a cylindrical battery cell, a prismatic battery cell, a pouch battery cell, or a battery cell of other shapes. Prismatic battery cells include prismatic battery cells, blade-shaped battery cells, and multi-prismatic batteries, such as hexagonal prismatic batteries. This application does not have any particular limitations.

[0180] In some embodiments, the housing includes an end cap and a housing, the housing having an opening, and the end cap covering the opening. The housing may have one or more openings. The end cap may also have one or more.

[0181] Electrode terminals

[0182] In some embodiments, at least one electrode terminal is provided on the housing, and the electrode terminal is electrically connected to the tab. The electrode terminal can be directly connected to the tab, or it can be indirectly connected to the tab through a current collector. The electrode terminal can be provided on the end cap or on the housing.

[0183] Pressure relief mechanism

[0184] In some embodiments, a pressure relief mechanism is provided on the casing. The pressure relief mechanism is used to release the internal gas of the battery cell.

[0185] As an example, the internal pressure or temperature of a battery cell is actuated to release the internal pressure or temperature when it reaches a predetermined threshold. When the internal pressure or temperature of the battery cell reaches the predetermined threshold, the pressure relief mechanism is activated or a weak structure in the pressure relief mechanism is broken, thereby creating an opening or channel for the internal pressure or temperature to be released. The threshold design varies depending on the design requirements. The threshold may depend on the materials of one or more of the positive electrode, negative electrode, electrolyte, and separator in the battery cell.

[0186] As an example, the pressure relief mechanism can be integrally molded with the housing.

[0187] As an example, the pressure relief mechanism can also be separately installed and connected to the housing.

[0188] The term "actuation" as used in this application refers to the activation or actuation of the pressure relief mechanism to a certain state, thereby releasing the internal pressure and temperature of the battery cell. The actions of the pressure relief mechanism may include, but are not limited to: movement of components within the mechanism to form an exhaust channel, rupture, breakage, tearing, or opening of at least a portion of the mechanism, etc. When the pressure relief mechanism is activated, the high-temperature, high-pressure substances inside the battery cell are discharged as waste from the activated portion. This method allows for pressure and temperature relief of the battery cell under controllable pressure or temperature, thereby preventing potentially more serious accidents.

[0189] In some embodiments, when the housing is a non-sealed structure, the pressure relief mechanism can be configured as a through hole for venting gas inside the battery cell.

[0190] The emissions from battery cells mentioned in this application include, but are not limited to: electrolyte, dissolved or split positive and negative electrode plates, fragments of separators, high-temperature and high-pressure gases generated by the reaction, flames, etc.

[0191] [Battery Device]

[0192] The battery apparatus mentioned in the embodiments of this application may include one or more battery cell assemblies for providing voltage and capacity. A battery cell assembly may include multiple battery cells connected in series, parallel, or mixed connections via a busbar.

[0193] In some embodiments, a battery cell assembly is typically formed by arranging multiple battery cells.

[0194] As an example, a battery cell assembly can be a battery module, which is formed by arranging and fixing multiple battery cells together to form an independent module. As another example, a battery module can be formed by bundling multiple battery cells together with cable ties.

[0195] In some embodiments, the battery device may be a battery pack, which includes a housing and one or more individual battery cells housed within the housing.

[0196] As an example, the battery cell assembly can be a battery module, which can be housed in a housing by fixing the battery module in the housing.

[0197] As an example, battery cell assemblies can also be housed in a housing by directly fixing multiple battery cells to the housing.

[0198] As an example, the enclosure may include a first enclosure and a second enclosure. The first enclosure and the second enclosure are fastened together to form a closed space inside the enclosure to house the individual battery cells. Here, "closed" refers to covering or closing, and can be either sealed or unsealed. The first enclosure may be a top cover or a bottom plate.

[0199] As an example, the enclosure may include a top cover, a frame, and a bottom plate. The top cover and bottom plate are connected to the frame, creating an enclosed space inside the enclosure to house the individual battery cells.

[0200] In some embodiments, the housing may be part of the vehicle's chassis structure. For example, a portion of the housing may be at least a part of the vehicle's floor, or a portion of the housing may be at least a part of the vehicle's crossbeams and longitudinal beams.

[0201] The technical solutions described in the embodiments of this application are applicable to various electrical devices that use individual battery cells, such as mobile phones, portable devices, laptops, electric vehicles, electric toys, power tools, vehicles, ships, and spacecraft. For example, spacecraft include airplanes, rockets, space shuttles, and spacecraft.

[0202] For example, Figure 1 The example shown is a square-structured battery cell 5.

[0203] In some implementations, refer to Figure 2The outer packaging may include a housing 51 and a cover 53. The housing 51 may include a base plate and side plates connected to the base plate, the base plate and side plates forming a receiving cavity. The housing 51 has an opening communicating with the receiving cavity, and the cover 53 can be placed over the opening to close the receiving cavity. The positive electrode, negative electrode, and separator may be formed into an electrode assembly 52 by a winding process or a stacking process. The electrode assembly 52 is encapsulated within the receiving cavity. Electrolyte is immersed in the electrode assembly 52. ​​The number of electrode assemblies 52 contained in a single battery cell 5 may be one or more, which can be selected by those skilled in the art according to specific practical needs.

[0204] In some implementations, individual battery cells can be assembled into a battery module. The number of individual battery cells contained in a battery module can be one or more, and the specific number can be selected by those skilled in the art based on the application and capacity of the battery module.

[0205] Figure 3 This is battery module 4, used as an example. (See reference...) Figure 3 In battery module 4, multiple battery cells 5 can be arranged sequentially along the length of battery module 4. Of course, they can also be arranged in any other manner. Furthermore, these multiple battery cells 5 can be fixed in place using fasteners.

[0206] Optionally, the battery module 4 may also include a housing with a receiving space in which multiple battery cells 5 are received.

[0207] In some embodiments, the battery modules described above can also be assembled into a battery pack, and the number of battery modules contained in the battery pack can be one or more, the specific number of which can be selected by those skilled in the art according to the application and capacity of the battery pack.

[0208] Figure 4 and Figure 5 This is battery pack 1 as an example. (See reference...) Figure 4 and Figure 5 The battery pack 1 may include a battery box and multiple battery modules 4 disposed within the battery box. The battery box includes an upper body 2 and a lower body 3, with the upper body 2 covering the lower body 3 to form a closed space for accommodating the battery modules 4. The multiple battery modules 4 can be arranged in any manner within the battery box.

[0209] In addition, this application also provides an electrical device, which includes at least one of the battery cell, battery module, or battery pack provided in this application. The battery cell, battery module, or battery pack can be used as the power source of the electrical device or as the energy storage unit of the electrical device. The electrical device may include, but is not limited to, mobile devices (e.g., mobile phones, laptops, etc.), electric vehicles (e.g., pure electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, electric bicycles, electric scooters, electric golf carts, electric trucks, etc.), electric trains, ships and satellites, energy storage systems, etc.

[0210] As an electrical device, you can choose individual battery cells, battery modules, or battery packs according to your usage requirements.

[0211] Figure 6 This is an example of an electrical device. The device could be a pure electric vehicle, a hybrid electric vehicle, or a plug-in hybrid electric vehicle. To meet the high power and high energy density requirements of individual battery cells, a battery pack or battery module can be used.

[0212] [Example]

[0213] The following describes embodiments of this application. The embodiments described below are exemplary and are only used to explain this application, and should not be construed as limiting this application. Where specific techniques or conditions are not specified in the embodiments, they are performed according to the techniques or conditions described in the literature in this field or according to the product instructions. Reagents or instruments used, unless otherwise specified, are all conventional products that can be obtained commercially.

[0214] Example 1

[0215] (1) Preparation of electrolyte:

[0216] Ethylene glycol dimethyl ether (DME) and 1,1,2,2-tetrafluoroethyl-2,2,3,3-tetrafluoropropyl ether (TTE) were mixed at a mass ratio of 1:7 to form a solvent. 2g of lithium difluorosulfonyl imide (LiFSI) was added to 8g of the solvent, and after thorough mixing, 0.05g of potassium ammonium nitrate was added to form the electrolyte.

[0217] (2) Preparation of the positive electrode sheet:

[0218] A sulfur-carbon mixture (75% sulfur by mass), acetylene black (conductive agent), and PVDF (binder) were mixed in a mass ratio of 7:1:2. N-methylpyrrolidone (NMP) was added as solvent and stirred until the system was homogeneous, yielding a positive electrode slurry (70% solids by mass). The positive electrode slurry was then subjected to a concentration of 1.75 mg / cm³. 2The sulfur content is uniformly coated on both sides of the positive electrode current collector aluminum foil, dried at room temperature, transferred to an oven for further drying, and then cut into 40mm*50mm rectangles as positive electrode sheets.

[0219] (3) Preparation of the separating membrane:

[0220] Select a porous polyethylene membrane and cut it into rectangles of 45mm*55mm for later use.

[0221] (4) Preparation of negative electrode sheet:

[0222] A 50μm thick lithium foil is rolled onto one side of a 12μm thick copper foil and then cut into 41mm*51mm rectangles to serve as negative electrode sheets.

[0223] (5) Assembly of individual battery cells:

[0224] The positive electrode, separator, and negative electrode are stacked to form an electrode assembly. This assembly is then wrapped in an aluminum-plastic film bag, dried, and injected with electrolyte. After encapsulation, high-temperature settling, formation, secondary electrolyte injection, aging, and capacity testing, a single battery cell is obtained. The rated capacity of the single battery cell is 70mAh.

[0225] The parameters that differentiate Examples 2-20 and Comparative Examples 1-2 from Example 1 are shown in Table 1.

[0226]

[0227]

[0228] Parameter testing

[0229] (1) Method for testing the average diameter of ion clusters in electrolytes:

[0230] The battery cell was disassembled, and the electrolyte was taken near the negative electrode. The average diameter of the ion clusters was measured using small-angle X-ray scattering (SAXS). The specific test steps were performed according to paragraphs

[0166] -

[0184] of the specification of Chinese patent document CN107532316B.

[0231] (2) Method for testing the molar concentration of ions in electrolytes:

[0232] A series of standard solutions of ammonium ions, metal ions, sulfide ions, or nitrate ions with varying concentrations were prepared and analyzed by ion chromatography (IC). Ion chromatography operating conditions were as follows: IonPac AG22 (4×50 mm) and IonPac AS22 (4×250 mm) columns; eluent: an aqueous solution of acetonitrile containing 15.5 mmol / L sodium carbonate and 3.5 mmol / L sodium bicarbonate (containing 28% wt% acetonitrile); eluent flow rate: 1.0 mL / min; column temperature: 30 °C. A standard curve was established with the peak area of ​​the standard solution as the ordinate and the concentration of the standard solution as the abscissa.

[0233] Disassemble the battery cell, take electrolyte near the negative electrode, and test it using ion chromatography IC (operating conditions as above). Determine the type of ion based on the peak position and substitute the peak area into the standard curve to calculate the molar concentration of the ion in the electrolyte.

[0234] (3) Test methods for ionic cluster compounds in electrolytes:

[0235] Disassemble the battery cell, take electrolyte near the negative electrode and dilute with DMSO, or rinse the surface of the negative electrode with DMSO and dilute. Dissolve Li₂S and cerium ammonium nitrate separately in DMSO, with the solution volume equal to the volume of the diluent. Analyze the diluent and solution using liquid chromatography-nuclear magnetic resonance spectroscopy to obtain... 1 H spectrum and 7 Li spectrum.

[0236] Test (2) revealed that the electrolyte in Example 1 contained ammonium ions, sulfur ions, and lithium ions.

[0237] Comparison of Li2S solution and dilution solution of Example 1 7 As can be seen from the Li spectrum, compared to the Li2S solution... 7 Li spectrum, diluent 7 The peak positions in the Li spectrum differ from those in Li2S, indicating that in the diluted solution, the lithium ions in Li2S are at least partially replaced by ammonium ions.

[0238] Comparison of ammonium nitrate cerium solution and diluted solution of Example 1 1 The H spectrum shows that, compared to the ammonium cerium nitrate solution, 1 H spectrum, diluent 1 The appearance of a new absorption peak in the vicinity of the H spectrum indicates that there is an interaction between ammonium ions and sulfur or lithium ions.

[0239] Therefore, it can be concluded that the electrolyte contains compounds formed by lithium ions, ammonium ions and sulfur ions or compounds formed by ammonium ions and sulfur ions. Since the test in item (1) confirms the presence of ion clusters, it can be concluded that the ion clusters include compounds formed by lithium ions, ammonium ions and sulfur ions or compounds formed by ammonium ions and sulfur ions. The molar ratio between each ion can be obtained by the degree of peak shift or the degree of peak change.

[0240] (4) Test methods for lithium nitride, lithium oxide, lithium nitride oxides, and metal elements in the negative electrode:

[0241] The negative electrode sheet is disassembled from the battery cell, cleaned with a solvent (e.g., DMC), and dried. XPS is used to perform a full-spectrum scan of the negative electrode sheet to obtain a spectrum. This spectrum is compared with a standard spectrum to determine the presence of sodium, potassium, rubidium, cesium, cerium, lithium, nitrogen, and oxygen. Fine spectral analysis of lithium, nitrogen, and oxygen is used to determine the chemical state and valence of these elements, thus identifying the compounds.

[0242] Battery test

[0243] Cycle life test method for individual battery cells:

[0244] The ambient temperature was set to 25℃. The battery cells were charged at a constant current of 0.2C to 4.3V, then charged at a constant voltage of 0.1C, and finally discharged at a constant current of 1C to 2.8V. The first discharge capacity C0 was recorded. The charging and discharging process was repeated until the discharge capacity decreased to 80% of the first discharge capacity, and the number of cycles at this point was recorded.

[0245] The test results are shown in Table 2.

[0246] Table 2 Test results of Examples 1-20 and Comparative Examples 1-2

[0247]

[0248]

[0249] From the above test results, we can conclude that:

[0250] Compared with Comparative Example 1, which did not use electrolyte additives, the cycle life of the battery cells in Examples 1-20 of this application is significantly improved.

[0251] Compared with Comparative Example 2, which uses potassium nitrate as an electrolyte additive, the battery cells in Examples 1-20 of this application using electrolyte additives containing ammonium ions have significantly improved cycle life.

[0252] Compared to Example 4, where the ammonium ion molar content in the electrolyte was lower, the cycle life of the battery cells in Examples 1-3 of this application was significantly higher.

[0253] Compared to Example 5, which has a higher molar content of ammonium ions in the electrolyte, the cycle life of the battery cells in Examples 1-3 of this application is significantly higher.

[0254] Compared to the lower molar content of ammonium and nitrate ions in the electrolyte in Example 9, the cycle life of the battery cells in Examples 6-8 of this application is significantly higher.

[0255] Compared to the higher molar content of ammonium and nitrate ions in the electrolyte in Example 10, the cycle life of the battery cells in Examples 6-8 of this application is significantly higher.

[0256] Compared to the lower molar content of ammonium ions, nitrate ions and metal ions in the electrolyte in Example 14, the cycle life of the battery cells in Examples 11-13 of this application is significantly higher.

[0257] Compared to the higher molar content of ammonium ions, nitrate ions and metal ions in the electrolyte in Example 15, the cycle life of the battery cells in Examples 11-13 of this application is significantly higher.

[0258] Compared with Examples 1-3 which used ammonium fluoride as an electrolyte additive, the cycle life of the battery cells in Examples 6-8 of this application, which used ammonium nitrate as an electrolyte additive, is further improved.

[0259] Compared with Examples 6-8 which used ammonium nitrate as an electrolyte additive, the cycle life of the battery cells in Examples 11-13 of this application which used potassium ammonium nitrate as an electrolyte additive, and Examples 16-18 of this application which used cerium ammonium nitrate, cesium ammonium nitrate, and rubidium ammonium nitrate as electrolyte additives, respectively, is further improved.

[0260] It should be noted that this application is not limited to the above-described embodiments. The above embodiments are merely examples, and any embodiments with the same structure and effect as the technical concept within the scope of this application are included in the technical scope of this application. Furthermore, various modifications that can be conceived by those skilled in the art to the embodiments, and other ways of constructing by combining some of the constituent elements of the embodiments, without departing from the spirit of this application, are also included in the scope of this application.

Claims

1. A lithium-sulfur battery cell, comprising a negative electrode and an electrolyte; wherein the negative electrode and / or the electrolyte comprises ion clusters, the ion clusters comprising ammonium ions, sulfur ions and / or lithium ions.

2. The lithium-sulfur battery cell according to claim 1, wherein, The average diameter of the ion clusters is 3-4 nm.

3. The lithium-sulfur battery cell according to claim 1 or 2, wherein, The ion clusters are electrically neutral.

4. The lithium-sulfur battery cell according to any one of claims 1 to 3, wherein, The ion clusters include ammonium ions, sulfide ions, and optionally lithium ions.

5. The lithium-sulfur battery cell according to any one of claims 1 to 4, wherein, The ionic cluster includes Li x (NH4) y S z , where x≥0, y>0 and x + y = 2, 0 < z ≤ 2; and / or, The ion clusters include Li 0.5 (NH4) 1.5 S, Li(NH4)S, (NH4)2S, Li 0.5 (NH4) 1.5 One or more of S2, Li(NH4)S2, and (NH4)2S2.

6. The lithium-sulfur battery cell according to any one of claims 1 to 5, wherein, The electrolyte includes compounds containing ammonium ions.

7. The lithium-sulfur battery cell according to any one of claims 1 to 6, wherein, The molar concentration of the ammonium ion in the electrolyte is 0.01-0.1 M.

8. The lithium-sulfur battery cell according to any one of claims 1 to 7, wherein, The electrolyte includes compounds containing nitrate ions.

9. The lithium-sulfur battery cell according to claim 8, wherein, The molar concentration of nitrate ions in the electrolyte is 0.01-0.1M.

10. The lithium-sulfur battery cell according to any one of claims 1 to 9, wherein, The negative electrode includes one or more of lithium nitride, lithium oxide, and lithium nitride oxide.

11. The lithium-sulfur battery cell according to any one of claims 1 to 10, wherein, The electrolyte includes a compound containing metal ions, which include one or more of sodium, potassium, rubidium, cesium, and cerium.

12. The lithium-sulfur battery cell according to claim 11, wherein, The molar concentration of the metal ion in the electrolyte is 0.01-0.1M.

13. The lithium-sulfur battery cell according to any one of claims 1 to 12, wherein, The negative electrode includes one or more elements selected from sodium, potassium, rubidium, cesium, and cerium.

14. The lithium-sulfur battery cell according to any one of claims 1 to 13, characterized in that... One or more of the following: The compounds containing ammonium ions include one or more of the following: potassium ammonium nitrate, cerium ammonium nitrate, cesium ammonium nitrate, rubidium ammonium nitrate, ammonium nitrate, ammonium nitrite, ammonium iodide, ammonium sulfide, ammonium bromide, ammonium fluoride, ammonium chloride, diammonium pentasulfide, ammonium borate, and ammonium dihydrogen phosphate. The compounds containing nitrate ions include one or more of potassium ammonium nitrate, cerium ammonium nitrate, cesium ammonium nitrate, rubidium ammonium nitrate, ammonium nitrate, potassium nitrate, cerium nitrate, cesium nitrate, rubidium nitrate, lithium nitrate, and sodium nitrate; The compounds containing metal ions include one or more of the following: potassium ammonium nitrate, cerium ammonium nitrate, cesium ammonium nitrate, rubidium ammonium nitrate, potassium nitrate, cerium nitrate, cesium nitrate, rubidium nitrate, potassium fluoride, potassium chloride, potassium bromide, potassium iodide, cerium fluoride, cerium chloride, cerium bromide, cerium iodide, rubidium fluoride, rubidium chloride, rubidium bromide, and rubidium iodide.

15. The lithium-sulfur battery cell according to any one of claims 1 to 14, wherein, The electrolyte includes one or more additives selected from ammonium fluoride, ammonium nitrate, potassium ammonium nitrate, cerium ammonium nitrate, cesium ammonium nitrate, and rubidium ammonium nitrate.

16. The lithium-sulfur battery cell according to claim 15, wherein, The additive has a mass content of 0.05%-5% in the electrolyte.

17. The battery cell according to any one of claims 1 to 16, wherein, The electrolyte comprises an ether solvent and / or a diluent, wherein: The ether solvent has a mass content of 5%-33% in the electrolyte; and / or, The diluent has a mass content of 50%-85% in the electrolyte.

18. An electrolyte for lithium-sulfur battery cells, comprising ion clusters, said ion clusters including ammonium ions, sulfur ions and / or lithium ions.

19. The electrolyte according to claim 18, wherein, The average diameter of the ion clusters is 3-4 nm; and / or, The ion clusters are electrically neutral.

20. The electrolyte according to claim 18 or 19, wherein, The ion clusters include ammonium ions, sulfide ions, and optionally lithium ions; and / or, The ionic cluster includes Li x (NH4) y S z , where x≥0, y>0 and x + y = 2, 0 < z ≤ 2; and / or, The ion clusters include Li 0.5 (NH4) 1.5 S, Li(NH4)S, (NH4)2S, Li 0.5 (NH4) 1.5 One or more of S2, Li(NH4)S2, and (NH4)2S2.

21. The electrolyte according to any one of claims 18 to 20, wherein, The electrolyte includes compounds containing ammonium ions.

22. The electrolyte according to any one of claims 18 to 21, wherein, The molar concentration of the ammonium ion in the electrolyte is 0.01-0.1 M.

23. The electrolyte according to any one of claims 18 to 22, wherein, The electrolyte includes compounds containing nitrate ions.

24. The electrolyte according to claim 23, wherein, The molar concentration of nitrate ions in the electrolyte is 0.01-0.1M.

25. The electrolyte according to any one of claims 18 to 24, wherein, The electrolyte includes a compound containing metal ions, which include one or more of sodium, potassium, rubidium, cesium, and cerium.

26. The electrolyte according to claim 25, wherein, The molar concentration of the metal ion in the electrolyte is 0.01-0.1M.

27. The electrolyte according to any one of claims 18 to 26, characterized in that... One or more of the following: The compounds containing ammonium ions include one or more of the following: potassium ammonium nitrate, cerium ammonium nitrate, cesium ammonium nitrate, rubidium ammonium nitrate, ammonium nitrate, ammonium nitrite, ammonium iodide, ammonium sulfide, ammonium bromide, ammonium fluoride, ammonium chloride, diammonium pentasulfide, ammonium borate, and ammonium dihydrogen phosphate. The compounds containing nitrate ions include one or more of potassium ammonium nitrate, cerium ammonium nitrate, cesium ammonium nitrate, rubidium ammonium nitrate, ammonium nitrate, potassium nitrate, cerium nitrate, cesium nitrate, rubidium nitrate, lithium nitrate, and sodium nitrate; The compounds containing metal ions include one or more of the following: potassium ammonium nitrate, cerium ammonium nitrate, cesium ammonium nitrate, rubidium ammonium nitrate, potassium nitrate, cerium nitrate, cesium nitrate, rubidium nitrate, potassium fluoride, potassium chloride, potassium bromide, potassium iodide, cerium fluoride, cerium chloride, cerium bromide, cerium iodide, rubidium fluoride, rubidium chloride, rubidium bromide, and rubidium iodide.

28. The electrolyte according to any one of claims 18 to 27, wherein, The electrolyte includes one or more additives selected from potassium ammonium nitrate, cerium ammonium nitrate, cesium ammonium nitrate, and rubidium ammonium nitrate.

29. The electrolyte according to claim 28, wherein, The additive has a mass content of 0.05%-5% in the electrolyte.

30. The electrolyte according to any one of claims 18 to 29, wherein, The electrolyte comprises an ether solvent and / or a diluent, wherein: The ether solvent has a mass content of 5%-20% in the electrolyte; and / or, The diluent has a mass content of 50%-85% in the electrolyte.

31. A battery device comprising a battery cell according to any one of claims 1 to 17 or an electrolyte according to any one of claims 18 to 30.

32. An electrical device comprising a battery cell as described in any one of claims 1 to 17 or a battery device as described in claim 31.

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