A chloride composite electrode containing sodium chloride and / or lithium chloride, a method for preparing the same, and a secondary battery

Abstract

The application discloses a chloride composite electrode containing sodium chloride and / or lithium chloride, a preparation method of the chloride composite electrode and a secondary battery, and belongs to the technical field of batteries. The chloride composite electrode containing sodium chloride and / or lithium chloride comprises a chloride composite material, the chloride composite material comprises alkali metal chloride (sodium chloride and / or lithium chloride) and a sulfur composite material, and the sulfur composite material comprises sulfur single substance and carbon material coated on at least part of the surface of the sulfur single substance. The chloride composite material of the application takes sodium chloride (table salt can be used) and / or lithium chloride as a key reaction component, and is combined with sulfur single substance and carbon material to form a composite microstructure. The material has low-energy-barrier redox centers, can promote the reversible conversion of sodium ions and lithium ions, significantly improves the reaction reversibility and cycle stability, ensures good electrochemical performance, has significant cost and resource advantages, and can be used for preparing a composite electrode and a secondary battery with good electrochemical performance. 0 / 4+ The application discloses a chloride composite electrode containing sodium chloride and / or lithium chloride, a preparation method

Description

Technical Field

[0001] This invention belongs to the field of battery technology, and particularly relates to a chloride composite electrode containing sodium chloride and / or lithium chloride, its preparation method, and a secondary battery. Background Technology

[0002] Alkali metal battery systems (such as lithium / sodium systems) are considered an important technological route for realizing high-energy-density rechargeable secondary batteries due to the high theoretical specific capacity and low electrochemical potential of the metal anode. Compared with traditional transition metal intercalation / deintercalation cathode materials, alkali metal chlorides (such as NaCl and LiCl) are widely available, low in cost, and abundant in resources, offering potential advantages for constructing low-cost battery systems. However, existing systems using alkali metal chlorides as cathode active materials or as key reactive components generally face problems of insufficient discharge output and difficulty in reversible cycling. The reasons include at least the following: alkali metal chlorides exhibit both low electronic and ionic conductivity in the solid state, leading to limited electron / ion transport within the electrode and low utilization of active components; electrochemical processes involving chloride ions and active chlorine species may be accompanied by the generation of highly reactive species, inducing electrolyte decomposition, corrosion, or safety risks, thus limiting the stable operation of the system. These factors have constrained the application of alkali metal chlorides in rechargeable secondary batteries despite their significant cost advantages.

[0003] Meanwhile, elemental sulfur, as an abundant cathode material, possesses high theoretical specific capacity and significant cost advantages. However, existing sulfur-based secondary batteries mostly rely on sulfur... 0 / S 2- The (polysulfide / sulfide) redox pathway has a relatively low reaction potential, limiting further improvements in battery output voltage and energy density. Theoretically, if the cathode reaction pathway could be elevated to a point where sulfur reacts with sulfur (S...)... 0 Towards higher price states (with S) 4+ The oxidation transformation of sulfur compounds (represented by sulfur chloride) and the formation of high-valence sulfur-containing species such as sulfur chlorides in a chlorine-containing coordination environment are expected to obtain higher reaction potentials and higher usable energy. However, in actual systems, this high-valence oxidation process usually faces problems such as high reaction energy barriers, kinetic stagnation and increased polarization, and may trigger side reactions that lead to decreased efficiency or even failure. Summary of the Invention

[0004] In view of the limitations of electron / ion transport in the alkali metal chloride system and the lack of reversibility caused by chlorine-related side reactions in the prior art, as well as the problems of at least one of kinetic lag, overpotential increase and product instability in the high-potential oxidation process of sulfur cathode, one of the objectives of the present invention is to provide a chloride composite electrode containing sodium chloride and / or lithium chloride, which can balance low cost and safety, effectively reduce the kinetic hindrance of high-valence sulfur oxidation, suppress polarization and achieve stable confinement and reversibility of reaction products.

[0005] The second objective of this invention is to provide a method for preparing the above-mentioned chloride composite electrode containing sodium chloride and / or lithium chloride.

[0006] The third objective of this invention is to provide a secondary battery.

[0007] To achieve the above objectives, the technical solution adopted by the present invention is as follows: A first aspect of the present invention provides a chloride composite electrode containing sodium chloride and / or lithium chloride, the chloride composite electrode containing sodium chloride and / or lithium chloride comprising a current collector and an active layer stacked thereon; the active layer comprising a chloride composite material; the chloride composite material comprising an alkali metal chloride and a sulfur composite material; the alkali metal chloride comprising sodium chloride and / or lithium chloride; the sulfur composite material comprising elemental sulfur and a carbon material coating at least a portion of the surface of the elemental sulfur.

[0008] This invention uses abundant alkali metal chlorides as key reaction components, specifically sodium chloride (table salt can be used) and / or lithium chloride, and constructs a composite electrode microstructure with elemental sulfur and carbon materials. This enables the chloride system, which typically exhibits inert components or irreversible byproducts in batteries, to possess reversible energy storage capabilities. Leveraging the electronic conductivity and pore / interface confinement effect of the chloride composite material, the sulfur chloride active products generated during charge and discharge can achieve a closed-loop transformation on the positive electrode side: "in-situ generation - stable carrying / binding - stepwise reduction and consumption." This significantly improves reaction reversibility and cycle stability, expands the positive electrode material system, and also offers significant cost and resource advantages.

[0009] Specifically, the chloride composite material of the present invention can form a high-potential S on the positive electrode side. 0 / S 4+ The reversible chloride-sulfur redox center, during the charging process, can induce multi-electron oxidation of sulfur and its entry into the S-phase. 4+ The high oxidation state channel, represented by [a specific type of channel], generates and stably supports sulfur chloride active species within the electrode; during discharge, these active species undergo reversible reduction and rotation through stepwise electron backfilling, restoring to elemental sulfur (S). 0It combines with chloride / active chlorine components to achieve reversible energy storage and stable cycling in a low-cost feedstock system.

[0010] The aforementioned high-potential, low-polarization chloride-sulfur redox centers can enhance energy output and reduce polarization loss. This invention establishes a composite structure of "alkali metal chloride-sulfur-carbon materials" with S... 0 / S 4+ The energy storage mechanism is based on the redox reaction of high-valence sulfur, forming reversible sulfur chloride active species in a chlorine-containing coordination environment. This enables energy storage at a higher thermodynamic equilibrium potential, improving battery output voltage and energy density. Simultaneously, the interface-dominated stepwise chlorination / coordination stabilization mechanism reduces the apparent activation energy and charge transfer impedance of the high-valence sulfur formation process, thereby reducing charge / discharge overpotential, minimizing polarization, and improving energy efficiency. Therefore, this invention achieves a high-potential, highly reversible, and low-polarization electrochemical energy storage reaction based on a low-cost, resource-rich material system, providing a new cathode technology route for constructing rechargeable secondary batteries with both high energy density and long cycle life.

[0011] In some embodiments of the present invention, the raw material for providing the sodium chloride includes table salt. The main component of table salt is sodium chloride, and using it as a raw material for sodium chloride is advantageous because it is widely available, low in cost, and abundant in resources, thus enabling the construction of low-cost battery systems.

[0012] In some embodiments of the present invention, the chloride composite material contains chloride-sulfur redox centers.

[0013] In some embodiments of the present invention, the carbon material includes at least one of KB (Ketjenblack) carbon, Super-P (SP), carbon nanotubes, graphene, carbon black, acetylene black, or graphite; in some specific embodiments of the present invention, the carbon material is selected from KB carbon.

[0014] In some embodiments of the present invention, the mass ratio of elemental sulfur to carbon material is 1:(0.1~1.2); in some specific embodiments of the present invention, the mass ratio of elemental sulfur to carbon material is 1:(0.4~1); in some more specific embodiments of the present invention, the mass ratio of elemental sulfur to carbon material is 1:(0.45~0.55).

[0015] In some embodiments of the present invention, the molar ratio of elemental sulfur to alkali metal chloride is 1:(0.1~1.2); in some specific embodiments of the present invention, the molar ratio of elemental sulfur to alkali metal chloride is 1:(0.4~1); in some more specific embodiments of the present invention, the molar ratio of elemental sulfur to alkali metal chloride is 1:(0.45~0.7).

[0016] By optimizing the ratio of elemental sulfur, carbon materials, and alkali metal chlorides, the electrochemical performance of the material can be further improved.

[0017] In some embodiments of the present invention, the alkali metal chloride and the sulfur composite material are physically dispersed and bonded together.

[0018] In some embodiments of the present invention, the chloride composite material is obtained by mixing the alkali metal chloride and sulfur composite materials.

[0019] In some embodiments of the present invention, the chloride composite material is prepared by a method comprising the following steps: mixing an alkali metal chloride and a sulfur composite material in a protective gas.

[0020] In some embodiments of the present invention, the protective gas includes at least one of nitrogen, argon, or helium.

[0021] In some embodiments of the present invention, the sulfur composite material is prepared by a method comprising the following steps: mixing elemental sulfur with carbon material and subjecting the mixture to vacuum heat treatment to obtain the sulfur composite material.

[0022] In some embodiments of the present invention, the temperature of the vacuum heat treatment is 60~200℃; in some specific embodiments of the present invention, the temperature of the vacuum heat treatment is 90~170℃; in some more specific embodiments of the present invention, the temperature of the vacuum heat treatment is 140~160℃.

[0023] In some embodiments of the present invention, the vacuum heat treatment time is 1 to 36 hours; in some specific embodiments of the present invention, the vacuum heat treatment time is 6 to 18 hours; in some more specific embodiments of the present invention, the vacuum heat treatment time is 10 to 14 hours.

[0024] By optimizing the temperature and time of heat treatment, the electrochemical performance of the material can be further improved.

[0025] In some embodiments of the present invention, the sulfur element is mixed with the carbon material by ball milling.

[0026] In some embodiments of the present invention, the rotational speed of the ball mill is 200~800 rpm.

[0027] In some embodiments of the present invention, the ball milling time is 2 to 30 hours.

[0028] In some embodiments of the present invention, the current collector includes at least one of aluminum foil, carbon-coated aluminum foil, copper foil, titanium foil, or nickel mesh; in some specific embodiments of the present invention, the current collector includes at least one of aluminum foil, carbon-coated aluminum foil, or nickel mesh.

[0029] In some embodiments of the present invention, in the chloride composite electrode containing sodium chloride and / or lithium chloride, the loading of the chloride composite material is 1~20 mg·cm³. 2 In some specific embodiments of the present invention, in the chloride composite electrode containing sodium chloride and / or lithium chloride, the loading of the chloride composite material is 2~5 mg·cm³. 2 .

[0030] In some embodiments of the present invention, the active layer further includes a conductive agent and a binder, as well as an optional non-alkali metal chloride; in some specific embodiments of the present invention, the active layer further includes a conductive agent, a binder, and a non-alkali metal chloride.

[0031] The active layer of the chloride composite electrode of this invention contains a multiphase coupled microstructure and high-potential, low-activation-energy chloride-sulfur redox reaction centers, giving the chloride composite electrode high electrochemical performance and high reversibility. Specifically, carbon materials and conductive agents jointly construct a continuous conductive network. Alkali metal chlorides such as sodium chloride and lithium chloride (M = Na or Li) and AlCl3 form stable active chlorine reactive species within the positive electrode, promoting the high-valence redox of sulfur during charging and discharging via a more readily accessible pathway, thereby achieving the transformation from a primary system to a secondary system.

[0032] In this invention, the carbon material and the conductive agent can be the same or different.

[0033] In some embodiments of the present invention, the conductive agent includes at least one of KB carbon, Super-P, carbon nanotubes, graphene, carbon black, acetylene black, or graphite; in some specific embodiments of the present invention, the conductive agent is selected from Super-P (SP).

[0034] In some embodiments of the present invention, the adhesive includes at least one selected from polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), styrene-butadiene rubber (SBR), polyacrylic acid (PAA), carboxymethyl cellulose (CMC), or polyethylene oxide (PEO); in some specific embodiments of the present invention, the adhesive is selected from polyvinylidene fluoride (PVDF).

[0035] In some embodiments of the present invention, the non-alkali metal chloride includes at least one of aluminum chloride, ferric chloride, or cobalt chloride; in some specific embodiments of the present invention, the non-alkali metal chloride is selected from aluminum chloride (AlCl3).

[0036] In some embodiments of the present invention, the mass ratio of the chloride composite material to the conductive agent is 1:(0.05~0.4); in some specific embodiments of the present invention, the mass ratio of the chloride composite material to the conductive agent is 1:(0.07~0.2); in some more specific embodiments of the present invention, the mass ratio of the chloride composite material to the conductive agent is 1:(0.08~0.13).

[0037] In some embodiments of the present invention, the mass ratio of the chloride composite material to the binder is 1:(0.05~0.4); in some specific embodiments of the present invention, the mass ratio of the chloride composite material to the binder is 1:(0.07~0.2); in some more specific embodiments of the present invention, the mass ratio of the chloride composite material to the binder is 1:(0.08~0.13).

[0038] In some embodiments of the present invention, the mass ratio of the chloride composite material to the non-alkali metal chloride is 1:(0~0.2).

[0039] In some embodiments of the present invention, the active layer comprises a non-alkali metal chloride.

[0040] Alkali metal chlorides (sodium chloride and / or lithium chloride) and non-alkali metal chlorides (such as aluminum chloride, ferric chloride or cobalt chloride) can work synergistically to form stable active chlorine reactive species inside the cathode material, which promotes the high-valence redox of sulfur during charging and discharging through a more convenient pathway, thereby realizing the transformation from a primary system to a secondary system.

[0041] In some embodiments of the present invention, the mass ratio of the chloride composite material to the non-alkali metal chloride is 1:(0.01~0.2); in some specific embodiments of the present invention, the mass ratio of the chloride composite material to the non-alkali metal chloride is 1:(0.03~0.1); in some more specific embodiments of the present invention, the mass ratio of the chloride composite material to the non-alkali metal chloride is 1:(0.05~0.08).

[0042] In some embodiments of the present invention, the chloride composite electrode containing sodium chloride and / or lithium chloride generates sulfur chloride active products during charging.

[0043] In some embodiments of the present invention, the sulfur chloride active product includes at least one of S2Cl2, SCl2, or SCl4; in some specific embodiments of the present invention, the sulfur chloride active product includes SCl4.

[0044] In some embodiments of the present invention, the sulfur chloride active product is reduced and converted into elemental sulfur and chloride during the discharge process.

[0045] In some embodiments of the present invention, the sulfur is cyclic sulfur (S8).

[0046] During the charging process, in the chloride composite electrode of this invention, elemental sulfur (such as cyclic sulfur S8) is first electrochemically activated at the "conductive carbon network-alkali metal chloride-sulfur" three-phase composite interface of the electrode; relying on the chloride-sulfur redox reaction center constructed in the chloride composite material, the electron transfer of elemental sulfur is carried out by the conventional S... 0 / S 2 The route shifts to interface-dominated stepwise chlorination and coordination stabilization, achieving multi-electron oxidation, allowing sulfur to oxidize along the S-axis. 4+ The high oxidation state pathway, represented by this approach, reduces the apparent charge transfer resistance and activation energy of high-valence sulfur formation, and effectively suppresses polarization accumulation caused by the migration of soluble intermediates. As charging progresses, sulfur species distributed in the electrode channels and adjacent regions of the composite interface are continuously oxidized and chemically coupled with active chlorine species generated / enriched in situ within the electrode to form sulfur chloride active products, including at least one of S2Cl2, SCl2, or SCl4. Among these, the high-valence sulfur-related reactions correspond to higher thermodynamic equilibrium potentials, which is beneficial for increasing the battery output voltage and releasing higher usable energy.

[0047] In some embodiments of the present invention, under deep charging conditions, the characteristic peak of SCl4 (approximately 288.0 cm⁻¹) can be observed in the Raman spectrum of the positive electrode. 1 This indicates that sulfochlorides are generated in situ on the positive electrode side and participate in the energy storage process as a charging product.

[0048] After charging, the chloride composite electrode of the present invention exhibits a "confined-conductive-buffered" synergistic effect on the active products of sulfochloride: on the one hand, the porous structure of carbon materials (such as KB carbon) and the conductive network constructed by conductive agents (such as Super-P) allow the charging products to be preferentially generated and remain in the electron-accessible region, preventing the active products from migrating away from the electrode and causing irreversible loss; on the other hand, the micro-reaction units constructed inside the positive electrode by chlorine-containing components such as alkali metal chlorides (MCl, where M is Na or Li) and non-alkali metal chlorides play a role in carrying / buffering the active products, allowing sulfochloride to exist stably in the positive electrode structure in a reversible form, thereby providing a structural basis for the reversible reduction of the subsequent discharge process.

[0049] During discharge, the chloride composite electrode of the present invention gradually reduces the aforementioned sulfur chloride active products in the electrode and reversibly reverts them back to elemental sulfur and active chloride species / chlorides (which can further react with M...). + (forming MCl), thus constituting the positive electrode side S 0 / S 4+ The reversible redox closed ring structure is observed. Correspondingly, characteristic peaks (e.g., 153.4 cm⁻¹) of elemental sulfur (such as cyclic sulfur S₈) can be observed during discharge. 1 and 219.6cm 1 More importantly, this invention, through the structural design of "sulfur chloride carrier / buffering" inside the electrode, enables active chlorine species to preferentially participate in the reversible sulfur-chlorine coupling conversion, rather than escaping disorderly or triggering side reactions, thus ensuring the reversible charge and discharge of the battery from a mechanistic perspective.

[0050] A second aspect of the present invention provides a method for preparing a chloride composite electrode containing sodium chloride and / or lithium chloride as described in the first aspect of the present invention, comprising the following steps: mixing the components of the active layer with an organic solvent to form an electrode slurry; applying the electrode slurry onto the current collector and drying it to obtain the chloride composite electrode containing sodium chloride and / or lithium chloride.

[0051] In some embodiments of the present invention, the organic solvent includes at least one of N-methylpyrrolidone, dimethylformamide, dimethylacetamide, ethanol, isopropanol, acetone, or tetrahydrofuran.

[0052] A third aspect of the present invention provides a secondary battery comprising a positive electrode, a negative electrode, a separator, and an electrolyte; wherein the positive electrode is a chloride composite electrode containing sodium chloride and / or lithium chloride as described in the first aspect of the present invention.

[0053] In some embodiments of the present invention, the negative electrode includes a negative electrode current collector and an optional negative electrode active layer; the negative electrode active layer includes metallic lithium, metallic sodium, or a combination thereof. The negative electrode can be metallic lithium, metallic sodium, or a structure without a negative electrode active layer composed of a negative electrode current collector.

[0054] In some embodiments of the present invention, when the alkali metal chloride is NaCl, the negative electrode is metallic sodium or sodium is deposited in situ without a negative electrode; when the alkali metal chloride is LiCl, the negative electrode is metallic lithium or lithium is deposited in situ without a negative electrode.

[0055] In some embodiments of the present invention, the diaphragm includes at least one selected from glass fiber diaphragm, polyethylene (PE) diaphragm, and polypropylene (PP) diaphragm. Specifically, it may also be a composite or coated diaphragm of the above materials.

[0056] In some embodiments of the present invention, the electrolyte comprises a solvent and an electrolyte salt. The electrolyte salt is dissolved in the solvent.

[0057] In some embodiments of the present invention, the solvent includes nitrile solvents, sulfur-containing oxygen solvents, or combinations thereof.

[0058] In nitrile solvent and / or sulfur-containing oxygen-containing solvent electrolyte systems, the alkali metal chloride / sulfur redox centers formed on the positive electrode side are used to regulate the oxidation pathway of sulfur and chloride, thereby reducing S 0 / S 4+ The energy barrier of redox reactions reduces polarization during the charging and discharging process of rechargeable secondary batteries.

[0059] In addition, the chloride composite electrode of the present invention, under the synergistic effect of electrolyte solvation and halide coordination chemistry, can make the active products of sulfur chlorides exist stably in the positive electrode and realize reversible generation / consumption, thereby achieving stable secondary battery cycling.

[0060] In some embodiments of the present invention, the nitrile solvent includes at least one of acetonitrile, propionitrile, butyronitrile, valerate, benzonitrile, and succinic anion; in some specific embodiments of the present invention, the nitrile solvent includes acetonitrile, propionitrile, or a combination thereof.

[0061] In some embodiments of the present invention, the sulfur-containing oxygen solvent is selected from sulfur-containing oxygen halide solvents; in some specific embodiments of the present invention, the sulfur-containing oxygen solvent includes sulfone solvents, thionyl chloride solvents, or combinations thereof.

[0062] In some embodiments of the present invention, the sulfur-containing oxygen solvent includes at least one of thionyl chloride, dimethyl sulfone, methyl ethyl sulfone, diethyl sulfone, or sulfone alkane; in some specific embodiments of the present invention, the sulfur-containing oxygen solvent is selected from thionyl chloride.

[0063] In some embodiments of the present invention, the electrolyte salt comprises an alkali metal chloride, and optionally a fluorine-containing additive and / or a non-alkali metal chloride; in some specific embodiments of the present invention, the electrolyte salt comprises an alkali metal chloride, a fluorine-containing additive, and a non-alkali metal chloride.

[0064] Based on the chloride composite electrode provided by this invention, and combined with a specific electrolyte system, the morphology and reaction pathways of sulfur and active chloride species can be jointly regulated, promoting elemental sulfur to move along a lower energy barrier path towards S during charging. 4+ The process involves conversion to form sulfur chloride active products, which are then reversibly reduced during discharge, thereby improving battery reversibility and inhibiting the accumulation of "dead salts" of halides. This allows the electrodes to operate based on S during charge and discharge. 0 / S 4+ The reversible redox pathway enables reversible charge-discharge and stable cycling.

[0065] Specifically, the alkali metal chlorides and non-alkali metal chlorides in the electrolyte salt can be selected from the types involved in the first aspect of the present invention.

[0066] In some embodiments of the present invention, the alkali metal chloride in the electrolyte salt includes sodium chloride and / or lithium chloride.

[0067] In some embodiments of the present invention, the non-alkali metal chloride in the electrolyte salt includes at least one of aluminum chloride, ferric chloride, or cobalt chloride; in some specific embodiments of the present invention, the non-alkali metal chloride in the electrolyte salt is selected from aluminum chloride (AlCl3).

[0068] In some embodiments of the present invention, the fluorine-containing additive in the electrolyte salt includes at least one of NaTFSI, LiTFSI, NaFSI, or LiFSI.

[0069] In some embodiments of the present invention, the concentration of alkali metal chloride in the electrolyte is 0.2~8 mol·L⁻¹. 1 In some specific embodiments of the present invention, the concentration of alkali metal chloride in the electrolyte is 3-6 mol·L⁻¹. 1 In some more specific embodiments of the present invention, the concentration of alkali metal chloride in the electrolyte is 4-5 mol·L⁻¹. 1 .

[0070] In some embodiments of the present invention, the concentration of the fluorine-containing additive in the electrolyte is 0~10wt%.

[0071] In some embodiments of the present invention, the electrolyte includes a fluorine-containing additive.

[0072] In some embodiments of the present invention, the concentration of the fluorine-containing additive in the electrolyte is 0.1-10 wt%; in some specific embodiments of the present invention, the concentration of the fluorine-containing additive in the electrolyte is 1-3 wt%.

[0073] In some embodiments of the present invention, the concentration of non-alkali metal chloride in the electrolyte is 0~10 mol·L⁻¹. 1 .

[0074] In some embodiments of the present invention, the electrolyte comprises a non-alkali metal chloride.

[0075] In some embodiments of the present invention, the concentration of non-alkali metal chloride in the electrolyte is 0.1~10 mol·L⁻¹. 1 In some specific embodiments of the present invention, the concentration of non-alkali metal chloride in the electrolyte is 2~8 mol·L⁻¹. 1 .

[0076] The beneficial effects of this invention are: the chloride composite material of this invention uses abundant sodium chloride (specifically, table salt) and / or lithium chloride alkali metal chloride as key reactive components, and constructs a composite microstructure with elemental sulfur and carbon materials. This material has low-barrier redox centers, which can promote the oxidation of sulfur. 0 / S 4+ The process enables reversible generation or consumption of sulfide active products, thereby significantly improving reaction reversibility and cycle stability. While ensuring good electrochemical performance, it also has significant cost and resource advantages, and can be used to prepare electrodes and secondary batteries with good electrochemical performance. Attached Figure Description

[0077] Figure 1 This is a schematic diagram illustrating the principles of materials and conventional materials in the electrode embodiments of the present invention.

[0078] Figure 2 The image shows the XRD pattern of the chloride composite electrode in Example 1 of this invention.

[0079] Figure 3 This is a SEM image of the chloride composite electrode in electrode example 1 of the present invention.

[0080] Figure 4 The XRD diffraction peaks of the chloride composite electrode in the half-charged state in electrode example 1 of the present invention are shown.

[0081] Figure 5This is a SEM image of the chloride composite electrode in the half-charged state in electrode embodiment 1 of the present invention.

[0082] Figure 6 This is the constant current charge-discharge curve of the secondary battery in Example 1 of the present invention after it has stabilized at 0.5C.

[0083] Figure 7 This is the discharge capacity-cycle number curve of the secondary battery in Example 1 of the present invention under long-cycle charge and discharge at 0.5C.

[0084] Figure 8 This is the Raman spectrum of the chloride composite electrode in the charged state in electrode example 1 of the present invention. Detailed Implementation

[0085] The following specific embodiments further illustrate the content of the present invention in detail. It should also be understood that the following embodiments are only for further explanation of the present invention and should not be construed as limiting the scope of protection of the present invention. Non-essential improvements and adjustments made by those skilled in the art based on the principles described herein are all within the scope of protection of the present invention. The specific process parameters, etc., in the following examples are merely examples within a suitable range; that is, those skilled in the art can make selections within a suitable range based on the description herein, and are not intended to be limited to the specific data in the examples below. Unless otherwise specified, the raw materials, reagents, or apparatus used in the following embodiments and comparative examples can be obtained from conventional commercial sources or by existing known methods.

[0086] Electrode Example 1 A chloride composite electrode, specifically a sodium chloride (NaCl) composite electrode, is prepared using the following steps: S1: In an argon glove box (H2O / O2<0.1ppm), weigh appropriate amounts of sulfur powder and KB carbon at a mass ratio of 2:1, add them to a zirconia ball mill jar and seal it, and ball mill at 300 rpm for 5 hours.

[0087] S2: The sulfur / KB carbon composite material obtained by ball milling in step S1 is transferred to a vacuum-sealed quartz tube and heat-treated at 150°C for 12 hours. After natural cooling, the sulfur / KB carbon composite material is obtained.

[0088] S3: In an argon glove box (H2O / O2<0.1ppm), weigh an appropriate amount of NaCl and the sulfur / KB carbon composite material obtained in step S2 according to the molar ratio of NaCl to sulfur of 3:2. After thorough grinding, the NaCl@sulfur / KB carbon composite material is obtained and used as the active material of the electrode.

[0089] S4: In an argon glove box (H2O / O2<0.1ppm), weigh appropriate amounts of NaCl@sulfur / KB carbon composite material, Super-P, and PVDF obtained in step S3 according to a mass ratio of 8:1:1. Mix them thoroughly and grind them completely. Then, add N-methylpyrrolidone dropwise and grind them thoroughly to prepare a uniform electrode slurry.

[0090] S5: In an argon glove box (H2O / O2 < 0.1 ppm), the electrode slurry obtained in step S4 was uniformly coated onto aluminum foil (current collector), transferred to a vacuum drying oven, and dried at 70°C for 24 hours. The electrode was then rolled to obtain an active material loading of 3 mg·cm³. 2 Chloride composite electrode.

[0091] Electrode Example 2 A chloride composite electrode differs from electrode example 1 in that NaCl in step S3 is replaced with LiCl; all other conditions are the same as in electrode example 1.

[0092] Electrode Example 3 A chloride composite electrode differs from electrode example 1 in that the mass ratio of sulfur powder to KB carbon in step S1 is changed to 8:1; all other conditions are the same as in electrode example 1.

[0093] Electrode Example 4 A chloride composite electrode differs from electrode example 1 in that the mass ratio of sulfur powder to KB carbon in step S1 is changed to 6:1; all other conditions are the same as in electrode example 1.

[0094] Electrode Example 5 A chloride composite electrode differs from electrode example 1 in that the mass ratio of sulfur powder to KB carbon in step S1 is changed to 4:1; all other conditions are the same as in electrode example 1.

[0095] Electrode Example 6 A chloride composite electrode differs from electrode example 1 in that the mass ratio of sulfur powder to KB carbon in step S1 is changed to 1:1; all other conditions are the same as in electrode example 1.

[0096] Electrode Example 7 A chloride composite electrode differs from electrode example 1 in that the heat treatment temperature in step S2 is changed to 50°C; all other conditions are the same as in electrode example 1.

[0097] Electrode Example 8 A chloride composite electrode differs from electrode example 1 in that the heat treatment temperature in step S2 is changed to 100°C; all other conditions are the same as in electrode example 1.

[0098] Electrode Example 9 A chloride composite electrode differs from electrode example 1 in that the heat treatment temperature in step S2 is changed to 200°C; all other conditions are the same as in electrode example 1.

[0099] Electrode Example 10 A chloride composite electrode differs from electrode example 1 in that the heat treatment time in step S2 is changed to 6 hours; all other conditions are the same as in electrode example 1.

[0100] Electrode Example 11 A chloride composite electrode differs from electrode example 1 in that the heat treatment time in step S2 is changed to 18 hours; all other conditions are the same as in electrode example 1.

[0101] Electrode Example 12 A chloride composite electrode differs from electrode example 1 in that the molar ratio of NaCl to sulfur in step S3 is changed to 6:1; all other conditions are the same as in electrode example 1.

[0102] Electrode Example 13 A chloride composite electrode differs from electrode example 1 in that the molar ratio of NaCl to sulfur in step S3 is changed to 4:1; all other conditions are the same as in electrode example 1.

[0103] Electrode Example 14 A chloride composite electrode differs from electrode example 1 in that the molar ratio of NaCl to sulfur in step S3 is changed to 2:1; all other conditions are the same as in electrode example 1.

[0104] Electrode Example 15 A chloride composite electrode differs from electrode example 1 in that the molar ratio of NaCl to sulfur in step S3 is changed to 1:1; all other conditions are the same as in electrode example 1.

[0105] Electrode Example 16 A chloride composite electrode differs from electrode example 1 in that the mass ratio of NaCl@sulfur / KB carbon composite material, Super-P, and PVDF in step S4 is changed to 7:1.5:1.5; all other conditions are the same as in electrode example 1.

[0106] Electrode Example 17 A chloride composite electrode differs from electrode example 1 in that the mass ratio of NaCl@sulfur / KB carbon composite material, Super-P, and PVDF in step S4 is changed to 6:2:2; all other conditions are the same as in electrode example 1.

[0107] Electrode Example 18 A chloride composite electrode differs from electrode example 1 in that: AlCl3 is added in step S4, and the amount added satisfies the mass ratio of NaCl@sulfur / KB carbon composite material, Super-P, PVDF and AlCl3 as 80:7:7:6; all other conditions are the same as in electrode example 1.

[0108] Electrode Example 19 A chloride composite electrode differs from electrode example 1 in that: AlCl3 is added in step S4, and the amount added satisfies the mass ratio of NaCl@sulfur / KB carbon composite material, Super-P, PVDF and AlCl3 as 80:8:8:4; all other conditions are the same as in electrode example 1.

[0109] Electrode Example 20 A chloride composite electrode differs from electrode example 1 in that: AlCl3 is added in step S4, and the amount added satisfies the mass ratio of NaCl@sulfur / KB carbon composite material, Super-P, PVDF and AlCl3 as 70:10:10:10; all other conditions are the same as in electrode example 1.

[0110] Electrode Example 21 A chloride composite electrode differs from electrode example 1 in that: AlCl3 is added in step S4, and the amount added satisfies the mass ratio of NaCl@sulfur / KB carbon composite material, Super-P, PVDF, and AlCl3 as 70:12:12:6; all other conditions are the same as in electrode example 1.

[0111] Electrode Example 22 A chloride composite electrode differs from electrode example 1 in that: AlCl3 is added in step S4, and the amount added satisfies the mass ratio of NaCl@sulfur / KB carbon composite material, Super-P, PVDF, and AlCl3 as 60:15:15:10; all other conditions are the same as in electrode example 1.

[0112] Electrode Example 23 A chloride composite electrode differs from electrode example 1 in that: AlCl3 is added in step S4, and the amount added satisfies the mass ratio of NaCl@sulfur / KB carbon composite material, Super-P, PVDF and AlCl3 as 60:17:17:6; all other conditions are the same as in electrode example 1.

[0113] Electrode Example 24 A chloride composite electrode differs from electrode example 1 in that the current collector in step S5 is replaced with carbon-coated aluminum foil; all other conditions are the same as in electrode example 1.

[0114] Electrode Example 25 A chloride composite electrode differs from electrode example 1 in that the current collector in step S5 is replaced with copper foil; all other conditions are the same as in electrode example 1.

[0115] Electrode Example 26 A chloride composite electrode differs from electrode example 1 in that the current collector in step S5 is replaced with titanium foil; all other conditions are the same as in electrode example 1.

[0116] Electrode Example 27 A chloride composite electrode differs from electrode example 1 in that the current collector in step S5 is replaced with a nickel mesh; all other conditions are the same as in electrode example 1.

[0117] Electrode Comparative Example 1 A chloride composite electrode differs from electrode example 1 in that step S3 is omitted, i.e., the electrode does not contain NaCl; all other conditions are the same as in electrode example 1. The specific preparation steps are as follows: S1: In an argon glove box (H2O / O2<0.1ppm), weigh appropriate amounts of sulfur powder and KB carbon at a mass ratio of 2:1, add them to a zirconia ball mill jar and seal it, and ball mill at 300 rpm for 5 hours.

[0118] S2: The sulfur / KB carbon composite material obtained by ball milling in step S1 is transferred to a vacuum-sealed quartz tube and heat-treated at 150°C for 12 hours. After natural cooling, the sulfur / KB carbon composite material is obtained and used as the active material of the electrode.

[0119] S3: In an argon glove box (H2O / O2<0.1ppm), weigh appropriate amounts of the sulfur / KB carbon composite material, Super-P, and PVDF obtained in step S2 according to a mass ratio of 8:1:1. Mix them thoroughly and grind them completely. Then, add N-methylpyrrolidone dropwise and grind them thoroughly to form a uniform electrode slurry.

[0120] S4: In an argon glove box (H2O / O2 < 0.1 ppm), the electrode slurry obtained in step S3 was uniformly coated onto aluminum foil (current collector), transferred to a vacuum drying oven, and dried at 70°C for 24 hours. The electrode was then rolled to obtain an active material loading of 3 mg·cm³. 2 Chloride composite electrode.

[0121] Electrode Comparative Example 2 A chloride composite electrode differs from electrode example 1 in that steps S1 and S2 are omitted, i.e., the electrode does not contain sulfur powder; all other conditions are the same as in electrode example 1. The specific preparation steps are as follows: S1: In an argon glove box (H2O / O2<0.1ppm), appropriate amounts of NaCl and KB carbon were weighed out at a mass ratio of 2:1, added to a zirconia ball mill jar and sealed. The mixture was ball-milled at 300 rpm for 5 hours to obtain a NaCl / KB carbon composite material, which was used as the active material for the electrode.

[0122] S2: In an argon glove box (H2O / O2<0.1ppm), weigh appropriate amounts of the NaCl / KB carbon composite material, Super-P, and PVDF obtained in step S1 according to a mass ratio of 8:1:1. Mix them thoroughly and grind them completely. Then, add N-methylpyrrolidone dropwise and grind them thoroughly to prepare a uniform electrode slurry.

[0123] S3: In an argon glove box (H2O / O2 < 0.1 ppm), the electrode slurry obtained in step S2 was uniformly coated onto aluminum foil (current collector), transferred to a vacuum drying oven, and dried at 70°C for 24 hours. The electrode was then rolled to obtain an active material loading of 3 mg·cm³. 2 Chloride composite electrode.

[0124] Electrode Comparative Example 3 A chloride composite electrode differs from electrode example 1 in that step S2 is omitted, i.e., the ball-milled sulfur / KB carbon composite material is not heat-treated; all other conditions are the same as in electrode example 1. The specific preparation steps are as follows: S1: In an argon glove box (H2O / O2<0.1ppm), appropriate amounts of sulfur powder and KB carbon were weighed at a mass ratio of 2:1, added to a zirconia ball mill jar and sealed. The mixture was ball-milled at 300 rpm for 5 hours to obtain the sulfur / KB carbon composite material.

[0125] S2: In an argon glove box (H2O / O2<0.1ppm), weigh an appropriate amount of NaCl and the sulfur / KB carbon composite material obtained in step S1 according to the molar ratio of NaCl to sulfur of 3:2. After thorough grinding, the NaCl@sulfur / KB carbon composite material is obtained and used as the active material of the electrode.

[0126] S3: In an argon glove box (H2O / O2<0.1ppm), weigh appropriate amounts of NaCl@sulfur / KB carbon composite material, Super-P, and PVDF obtained in step S2 according to a mass ratio of 8:1:1. Mix them thoroughly and grind them completely. Then, add N-methylpyrrolidone dropwise and grind them thoroughly to prepare a uniform electrode slurry.

[0127] S4: In an argon glove box (H2O / O2 < 0.1 ppm), the electrode slurry obtained in step S3 was uniformly coated onto aluminum foil (current collector), transferred to a vacuum drying oven, and dried at 70°C for 24 hours. The electrode was then rolled to obtain an active material loading of 3 mg·cm³. 2 Chloride composite electrode.

[0128] Battery Example 1 A secondary battery uses the chloride composite electrode prepared in Electrode Example 1 as the positive electrode. The specific preparation steps are as follows: 1) In an argon glove box (H2O / O2 < 0.1 ppm), weigh out a certain mass of NaCl and AlCl3 and place them in a clean glass bottle. Add a certain volume of acetonitrile as a solvent and stir magnetically for 1 hour until fully dissolved to obtain a mixture. Control the concentration of NaCl in the mixture to be 4.5 mol·L⁻¹. 1 The concentration of AlCl3 was 8.0 mol·L⁻¹. 1 .

[0129] 2) In an argon glove box (H2O / O2<0.1ppm), weigh 2% of the total mass of the mixture in step 1) of NaFSI and add it to the mixture obtained in step 1). Stir magnetically for 0.5h until fully dissolved to obtain the electrolyte.

[0130] 3) In an argon glove box (H2O / O2 < 0.1ppm), place the negative electrode shell horizontally, put in the sodium metal sheet (negative electrode), and then place the separator in the center; add 100 μL of the electrolyte prepared in step 2) to completely wet the separator; place the chloride composite electrode (positive electrode) with the coating facing down in the center of the separator, and add another 20 μL of the electrolyte prepared in step 2) to wet the positive electrode; place the gasket and spring in sequence; finally, cover with the positive electrode shell and pressurize at 5MPa for 15s to obtain the secondary battery.

[0131] Battery Example 2 A secondary battery differs from Battery Example 1 in that: NaCl in step 1) is replaced with LiCl; NaFSI in step 2) is replaced with LiFSI; the positive electrode in step 3) is replaced with the chloride composite electrode prepared in Electrode Example 2, and the negative electrode is replaced with lithium foil; all other conditions are the same as in Battery Example 1.

[0132] Battery Examples 3-27 A secondary battery differs from Battery Example 1 in that the positive electrode in step 3) is replaced with the chloride composite electrode prepared in Electrode Examples 3 to 27; all other conditions are the same as in Battery Example 1.

[0133] Battery Example 28 A secondary battery differs from Battery Example 1 in that the solvent in step 1) is replaced with propionitrile; all other conditions are the same as in Battery Example 1.

[0134] Battery Example 29 A secondary battery differs from Battery Example 1 in that the solvent in step 1) is replaced with benzonitrile; all other conditions are the same as in Battery Example 1.

[0135] Battery Example 30 A secondary battery differs from Battery Example 1 in that the solvent in step 1) is replaced with thionyl chloride; all other conditions are the same as in Battery Example 1.

[0136] Battery Example 31 A secondary battery differs from Battery Example 1 in that the solvent in step 1) is replaced with dimethyl sulfone; all other conditions are the same as in Battery Example 1.

[0137] Battery Example 32 A secondary battery differs from Battery Example 1 in that the solvent in step 1) is replaced with diethyl sulfone; all other conditions are the same as in Battery Example 1.

[0138] Battery Example 33 A secondary battery differs from battery example 1 in that the concentration of NaCl in step 1) is changed to 3 mol·L⁻¹. 1 All other conditions are the same as in Battery Example 1.

[0139] Battery Example 34 A secondary battery differs from battery example 1 in that the concentration of NaCl in step 1) is changed to 6 mol·L⁻¹. 1 All other conditions are the same as in Battery Example 1.

[0140] Battery Example 35 A secondary battery differs from battery example 1 in that the concentration of AlCl3 in step 1) is changed to 2 mol·L⁻¹. 1 All other conditions are the same as in Battery Example 1.

[0141] Battery Example 36 A secondary battery differs from battery example 1 in that the concentration of AlCl3 in step 1) is changed to 4 mol·L⁻¹. 1 All other conditions are the same as in Battery Example 1.

[0142] Battery Example 37 A secondary battery differs from battery example 1 in that the concentration of AlCl3 in step 1) is changed to 6 mol·L⁻¹. 1 All other conditions are the same as in Battery Example 1.

[0143] Battery Examples 38-72 A secondary battery differs from batteries 3-37 in that: NaCl in step 1) is replaced with LiCl; NaFSI in step 2) is replaced with LiFSI; and the negative electrode in step 3) is replaced with lithium foil; all other conditions are the same as those in batteries 3-37.

[0144] Battery Comparison 1~3 A secondary battery differs from Battery Example 1 in that the positive electrode in step 3) is replaced with the chloride composite electrode prepared in Electrode Comparison Examples 1 to 3; all other conditions are the same as in Battery Example 1.

[0145] Battery Comparison 4 A secondary battery differs from Battery Example 1 in that NaCl is not added in step 1); all other conditions are the same as in Battery Example 1.

[0146] Performance testing Constant current charge-discharge and long-cycle tests were performed on the secondary batteries provided in each battery embodiment and battery comparison example. The specific steps are as follows: The test was conducted under constant temperature conditions of 25°C. The batteries were first charged to 4.2V at a rate of 0.5C, then discharged to 2V, and then cycled 300 times. The discharge specific capacity after stable discharge and the number of cycles at 80% capacity retention (i.e., 80% capacity retention life) were recorded. The results are shown in Tables 1-3.

[0147] Table 1. Preparation process parameters and electrochemical performance data of each battery example

[0148] Table 2. Preparation process parameters and electrochemical performance data of each battery example

[0149] Table 3. Preparation process parameters and electrochemical performance data of each battery comparative example.

[0150] As can be seen from Tables 1-3, the chloride composite electrodes and batteries prepared in the various embodiments of the present invention have good electrochemical performance, especially high discharge specific capacity and high capacity retention life.

[0151] Figure 1This is a schematic diagram illustrating the principles of materials and conventional materials in the electrode embodiments of the present invention; wherein, (A) is a conventional transition metal positive electrode, and (B) is a positive electrode using sodium chloride (NaCl) as the electrode material in the electrode embodiments of the present invention. Figure 1 As can be seen, compared with traditional transition metal intercalation / deintercalation cathode materials, the material of the electrode embodiment of the present invention can construct high-potential and highly reversible chloride-sulfur redox centers. It utilizes the confinement effect of the composite microstructure and the synergistic regulation of the electrolyte solvation / coordination environment to control the sulfur oxidation pathway, reducing the oxidation of sulfur from sulfur by S. 0 Towards higher price state (S 4+ The reaction energy barrier for the conversion. During charging, sulfur chloride active products, including S2Cl2, SCl2, and SCl4, are generated and stably present in the positive electrode system; during discharging, these active products are gradually reduced and reversibly converted back to elemental sulfur and chloride / active chlorine species, thereby achieving reversible charge-discharge and stable cycling. In some extended embodiments, NaCl can be replaced by LiCl, or LiCl and NaCl can be used in combination, and the corresponding negative electrode can be metallic lithium or metallic sodium.

[0152] Figure 2 This is the XRD (X-ray diffraction) pattern of the chloride composite electrode in Example 1 of the present invention. Figure 2 As can be seen, based on the standard PDF card of NaCl crystals, the diffraction peaks of the chloride composite electrode (uncharged state) of this invention basically correspond to those of NaCl crystals, indicating the presence of NaCl crystals in the material.

[0153] Figure 3 This is a SEM (scanning electron microscope) image of the chloride composite electrode in Example 1 of the present invention. From... Figure 3 It can be seen that the sulfur powder is uniformly coated with KB carbon and uniformly dispersed and compounded with NaCl.

[0154] Figure 4 These are the XRD diffraction peaks of the chloride composite electrode in the half-charged state of electrode embodiment 1 of the present invention. From... Figure 4 As can be seen, based on the standard PDF card of NaCl crystals, the diffraction peaks of the chloride composite electrode of the present invention in the half-charged state basically correspond to those of NaCl crystals, indicating that NaCl crystals still exist in the material in the half-charged state.

[0155] Figure 5 This is a SEM image of the chloride composite electrode in the half-charged state in electrode embodiment 1 of the present invention. From... Figure 5 It can be seen that the sulfur powder is uniformly coated with KB carbon and uniformly dispersed and combined with NaCl, and its morphology does not change much from that in the uncharged state.

[0156] Figure 6 This is the constant current charge-discharge curve of the secondary battery in Example 1 of the present invention after it has stabilized at 0.5C. Figure 7 This is the discharge capacity-cycle count curve of the secondary battery in Example 1 of the present invention under long-cycle charge-discharge at 0.5C. From... Figures 6-7 It is evident that this secondary battery possesses high specific capacity and high stability.

[0157] Figure 8 This is the Raman spectrum of the chloride composite electrode in the charged state of electrode Example 1 of the present invention. From... Figure 8 As can be seen, combined with the Raman peak of elemental sulfur, the chloride composite electrode in Example 1 of the present invention can form a stable sulfur chloride active product SCl4 in the material after charging, indicating that sulfur chloride is generated in situ on the positive electrode side and participates in the energy storage process as a charging product.

[0158] In summary, the chloride composite material of the present invention uses abundant sodium chloride (specifically, table salt) and / or lithium chloride alkali metal chloride as key reactive components, and constructs a composite microstructure with elemental sulfur and carbon materials. This material has low-barrier redox centers, which can promote the oxidation of sulfur. 0 / S 4+ The process enables reversible generation or consumption of sulfide active products, thereby significantly improving reaction reversibility and cycle stability. While ensuring good electrochemical performance, it also has significant cost and resource advantages, and can be used to prepare electrodes and secondary batteries with good electrochemical performance.

Claims

1. A chloride composite electrode containing sodium chloride or lithium chloride, characterized in that, The chloride composite electrode containing sodium chloride or lithium chloride includes a current collector and an active layer stacked together; the active layer includes a chloride composite material; the chloride composite material includes an alkali metal chloride and a sulfur composite material; the alkali metal chloride includes sodium chloride or lithium chloride; the sulfur composite material includes elemental sulfur and a carbon material coating at least a portion of the surface of the elemental sulfur. The mass ratio of elemental sulfur to carbon material is 1:(0.1~1.2); the molar ratio of elemental sulfur to alkali metal chloride is 1:(1~1.2), 1:1.5, 1:2, 1:4 or 1:

6. The sulfur composite material is prepared by a method comprising the following steps: mixing elemental sulfur with carbon material and subjecting it to vacuum heat treatment to obtain the sulfur composite material. The temperature of the vacuum heat treatment is 60~200℃; the time of the vacuum heat treatment is 1~36h; The chloride composite electrode containing sodium chloride or lithium chloride generates sulfur chloride active products during charging; the sulfur chloride active products include at least one of S2Cl2, SCl2 or SCl4.

2. The chloride composite electrode containing sodium chloride or lithium chloride according to claim 1, characterized in that, The carbon material includes at least one of KB carbon, Super-P, carbon nanotubes, graphene, acetylene black, or graphite.

3. The chloride composite electrode containing sodium chloride or lithium chloride according to claim 1, characterized in that, The current collector includes at least one of aluminum foil, carbon-coated aluminum foil, copper foil, titanium foil, or nickel mesh; And / or, in the chloride composite electrode containing sodium chloride or lithium chloride, the loading of the chloride composite material is 1~20 mg·cm³. -2 .

4. The chloride composite electrode containing sodium chloride or lithium chloride according to claim 1, characterized in that, The active layer also includes a conductive agent and a binder, as well as an optional non-alkali metal chloride.

5. The chloride composite electrode containing sodium chloride or lithium chloride according to claim 4, characterized in that, The conductive agent includes at least one of KB carbon, Super-P, carbon nanotubes, graphene, acetylene black, or graphite. And / or, the adhesive comprises at least one of polyvinylidene fluoride, polytetrafluoroethylene, styrene-butadiene rubber, polyacrylic acid, carboxymethyl cellulose or polyethylene oxide; And / or, the non-alkali metal chloride includes at least one of aluminum chloride, ferric chloride, or cobalt chloride; And / or, the mass ratio of the chloride composite material to the conductive agent is 1:(0.05~0.4). And / or, the mass ratio of the chloride composite material to the binder is 1:(0.05~0.4); And / or, the mass ratio of the chloride composite material to the non-alkali metal chloride is 1:(0~0.2).

6. A method for preparing a chloride composite electrode containing sodium chloride or lithium chloride as described in any one of claims 1 to 5, characterized in that, Includes the following steps: The components of the active layer are mixed with an organic solvent to prepare an electrode slurry; The electrode slurry is applied to the current collector and dried to obtain the chloride composite electrode containing sodium chloride or lithium chloride.

7. A secondary battery, characterized in that, The secondary battery includes a positive electrode, a negative electrode, a separator, and an electrolyte; the positive electrode is a chloride composite electrode containing sodium chloride or lithium chloride as described in any one of claims 1 to 5.

8. The secondary battery according to claim 7, characterized in that, The negative electrode includes a negative electrode current collector and an optional negative electrode active layer; the negative electrode active layer includes metallic lithium or metallic sodium. And / or, the diaphragm includes at least one of glass fiber diaphragm, polyethylene diaphragm, and polypropylene diaphragm; And / or, the electrolyte comprises a solvent and an electrolyte salt; the solvent comprises nitrile solvents, sulfur-containing oxygen solvents, or combinations thereof; the electrolyte salt comprises an alkali metal chloride and a fluorine-containing additive, and optionally a non-alkali metal chloride; wherein the nitrile solvent comprises acetonitrile, propionitrile, or combinations thereof; the sulfur-containing oxygen solvent comprises at least one of thionyl chloride, dimethyl sulfone, methyl ethyl sulfone, or diethyl sulfone; the fluorine-containing additive comprises at least one of NaTFSI, LiTFSI, NaFSI, or LiFSI; and the concentration of the alkali metal chloride in the electrolyte is 0.2–8 mol·L⁻¹. -1 The concentration of the fluorine-containing additive is 0.1–10 wt%, and the concentration of the optional non-alkali metal chloride is 0–10 mol·L⁻¹. -1 .

Images