Electrolyte containing phthalocyanine compound, preparation method and application thereof

Abstract

The application belongs to the technical field of lithium-sulfur batteries, and particularly relates to an electrolyte containing a phthalocyanine compound, a preparation method and application thereof; the electrolyte is composed of a conductive lithium salt, an ether solvent, a main additive and a secondary additive; the main additive is a phthalocyanine compound. By adding the phthalocyanine compound into the lithium-sulfur electrolyte, the phthalocyanine compound is used to complex with lithium ions and be adsorbed on the surface of a lithium negative electrode, so as to well regulate lithium ion deposition, improve lithium ion transference number, inhibit lithium dendrite growth, improve the surface morphology of lithium metal, reduce the direct contact between the negative electrode and the electrolyte, and achieve the effect of protecting the surface of the lithium metal electrode. The application also discloses the application of the electrolyte in lithium-sulfur batteries, and the lithium-sulfur battery prepared by using the electrolyte, which enhances the cycle stability of the lithium-sulfur battery and significantly improves the electrochemical performance.

Description

Technical Field

[0001] This invention belongs to the field of lithium-sulfur battery technology, specifically relating to an electrolyte containing phthalocyanine compounds, its preparation method, and its application. Background Technology

[0002] Lithium-sulfur batteries benefit from their high energy density (2600 Wh / kg) and the abundance, low price, and easy availability of sulfur resources. The lithium metal (Li) anode boasts the highest theoretical specific capacity (3860 mAh / kg). -1 Its low electrochemical potential (-3.04V vs standard hydrogen electrode) makes it the ultimate anode choice for high-energy lithium-based rechargeable batteries, making lithium-sulfur batteries a very promising candidate for next-generation energy storage devices.

[0003] However, lithium-sulfur batteries have not been put into practical use due to several thorny issues. For example, (1) the poor conductivity of sulfur and the diffusion and migration of intermediate polysulfides lead to a severe shuttle effect; (2) the cathode material expands or even collapses during charging and discharging; and (3) the disordered growth of lithium dendrites on the surface of the lithium anode may puncture the separator, causing a short circuit and safety problems. These issues lead to continuous irreversible loss of active materials and a severe decrease in coulombic efficiency, further causing the battery capacity to continuously decline.

[0004] Researchers have proposed many improvement methods to address the above problems. For example, nanoporous carbon is used as a conductive host for elemental sulfur to increase conductivity, provide void space to buffer volume fluctuations, and physically limit the dissolution of polysulfides. For example, modifying lithium anodes with 3D conductive substrates is an effective strategy that can self-limit the size of the Li coating to a current collector smaller than the nanostructure and improve the coulombic efficiency to 95%. For example, using nanostructured electrolytes with good toughness, high mechanical modulus, high ionic conductivity, and low interfacial impedance can suppress dendrite growth at room temperature.

[0005] However, due to cost or process limitations, selecting electrolyte additives to improve lithium-sulfur battery performance remains a viable approach. Modifying the electrolyte with additives is particularly significant in terms of energy density, cost, and ease of operation. The common function of most additives is to assist in stabilizing the SEI film, inhibiting Li dendrite formation, and improving cycle performance. While promising results have been presented, developing more effective electrolyte additives remains highly desirable because achieving sufficient passivation between the lithium anode and electrolyte during extended cycling is challenging. Summary of the Invention

[0006] To address the aforementioned problems, this invention provides an electrolyte containing phthalocyanine compounds, its preparation method, and its application. This electrolyte can inhibit lithium dendrite growth, improve the surface morphology of the lithium anode, and slow down the loss of active materials, thereby greatly improving the rate performance of lithium-sulfur batteries.

[0007] To solve the above-mentioned technical problems of the present invention, the present invention provides the following technical solution:

[0008] The first objective of this invention is to provide an electrolyte containing phthalocyanine compounds, wherein the electrolyte is composed of conductive lithium salt, ether solvent, main additive, and secondary additive; wherein the main additive is a phthalocyanine compound.

[0009] Furthermore, the phthalocyanine compound is one or more of copper phthalocyanine, iron phthalocyanine, nickel phthalocyanine, zinc phthalocyanine, and cobalt phthalocyanine.

[0010] Furthermore, the molar concentration of the phthalocyanine compound in the electrolyte is 0.01-4 mM.

[0011] Furthermore, the molar concentration of the phthalocyanine compound in the electrolyte is 0.5-2.0 mM. If the content of the phthalocyanine compound used is too high, it will accumulate excessively on the lithium anode surface, hindering lithium ion transport; if the content of the phthalocyanine compound used is too low, it will not have an effective effect.

[0012] Furthermore, the secondary additive is one or more of lithium nitrate, lanthanum nitrate, praseodymium nitrate, neodymium nitrate, lithium polysulfide, and lithium iodide. The molar concentration of the secondary additive in the electrolyte is 0.1-0.5M, preferably 0.1-0.2M. When the concentration of the secondary additive is 0.1-0.2M, it will work in conjunction with the main additive to better improve the electrochemical performance of the electrolyte. Among them, lithium nitrate can fully utilize the high specific capacity of lithium-sulfur batteries together with conductive lithium salts and solvents.

[0013] Furthermore, the ether solvent is any two mixed solvents selected from 1,3-dioxapentane, 1,4-dioxane, ethylene glycol dimethyl ether, diethylene glycol dimethyl ether, 2-methyltetrahydrofuran, dimethoxymethane, sulfolane, ethyl methyl sulfone, isopropyl methyl sulfone, dimethyl disulfide, dimethyl trisulfide, and dimethyl sulfide solvents.

[0014] Furthermore, the ether solvent is a mixed solvent of ethylene glycol dimethyl ether and 1,3-dioxolane, with a volume ratio of 0.8-1.3:1.

[0015] Furthermore, the conductive lithium salt is one or more of lithium hexafluorophosphate, lithium bis(oxalato)borate, lithium bis(trifluoromethanesulfonyl)imide, lithium bis(fluorosulfonyl)imide, and lithium bis(fluorophosphate); the molar concentration of the conductive lithium salt in the electrolyte is 1-1.5M.

[0016] The second objective of this invention is to provide a method for preparing an electrolyte containing phthalocyanine compounds, wherein a conductive lithium salt, a secondary additive, a primary additive, and an ether solvent are mixed and stirred at 25°C for 12-16 hours at a stirring speed of 600-1200 r / s to form a stable and homogeneous liquid, thereby obtaining the electrolyte.

[0017] A third objective of this invention is to provide an application of an electrolyte containing phthalocyanine compounds in the preparation of a lithium-sulfur battery, the battery comprising a positive electrode, a negative electrode, a separator, and an electrolyte containing phthalocyanine compounds.

[0018] The beneficial effects of this invention are:

[0019] 1. This invention provides a novel electrolyte system for lithium-sulfur batteries, using phthalocyanine compounds as the main electrolyte additive. The planar molecular structure of phthalocyanine compounds is suitable for protecting the lithium metal anode. Its main functions are: (1) Phthalocyanine and lithium ions form a planar molecular layer. This planar molecular layer can not only regulate the uniform deposition of lithium ions but also improve the lithium ion transport flux, thereby reducing the space charge effect and forming a Li-rich functional SEI film, which improves the lithium deposition morphology. (2) The formed SEI can also reduce the direct reaction with the electrolyte, delay the corrosion of the anode, effectively avoid the growth of lithium dendrites and the generation of dead lithium, and thus improve the overall electrochemical performance and cycle stability of lithium-sulfur batteries.

[0020] 2. The method for improving the performance of lithium-sulfur batteries adopted in this invention is simple and easy to implement. At the same time, it can achieve good performance with a low addition amount and is suitable for high-load sulfur cathodes.

[0021] 3. The operation method of this invention is simple, has good repeatability, is environmentally friendly, and has research value and potential practical application value. Attached Figure Description

[0022] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0023] Figure 1 This is a comparison chart of the rate cycling performance of the lithium-sulfur battery containing copper phthalocyanine electrolyte prepared in Example 1 and the lithium-sulfur battery without copper phthalocyanine electrolyte prepared in Comparative Example 1.

[0024] Figure 2 The rate cycling comparison chart shows the lithium-sulfur battery prepared in Example 3 with 0.5 mM copper phthalocyanine electrolyte and the lithium-sulfur battery prepared in Example 5 with 2.0 mM copper phthalocyanine electrolyte.

[0025] Figure 3 The lithium-lithium symmetric battery containing copper phthalocyanine electrolyte prepared in Example 2 and the lithium-lithium symmetric battery without copper phthalocyanine electrolyte prepared in Comparative Example 2 were compared at 1 mA cm⁻¹. -2 / 3mAh cm -2 Cyclic comparison chart;

[0026] Figure 4 The lithium-lithium symmetric battery (1 mA cm⁻¹) without copper phthalocyanine electrolyte prepared in Comparative Example 2 -2 / 1mAh cm -2 SEM image after 50 cycles;

[0027] Figure 5 The lithium-lithium symmetric battery containing copper phthalocyanine electrolyte prepared in Example 2 has a 1 mA cm⁻¹ capacity. -2 / 1mAh cm -2 SEM image after 50 cycles. Detailed Implementation

[0028] To make the objectives and technical solutions of the embodiments of the present invention clearer, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings and specific embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0029] This invention relates to an electrolyte containing phthalocyanine compounds, its preparation method, and its application. The battery electrolyte comprises: a conductive lithium salt, an ether solvent, a primary additive, and secondary additives. The main additive is a phthalocyanine compound, specifically one or more of copper phthalocyanine, iron phthalocyanine, nickel phthalocyanine, zinc phthalocyanine, and cobalt phthalocyanine. The secondary additive is one or more of lithium nitrate, lanthanum nitrate, praseodymium nitrate, neodymium nitrate, lithium polysulfide, and lithium iodide. The ether solvent is any two mixed solvents selected from 1,3-dioxapentane, 1,4-dioxane, ethylene glycol dimethyl ether, diethylene glycol dimethyl ether, 2-methyltetrahydrofuran, dimethoxymethane, sulfolane, ethyl methyl sulfone, isopropyl methyl sulfone, dimethyl disulfide, dimethyl trisulfide, and dimethyl sulfide, with a volume ratio of 0.8-1.3:1. The conductive lithium salt is one or more of lithium hexafluorophosphate, lithium bis(oxalato)borate, lithium bis(trifluoromethanesulfonyl)imide, lithium bis(fluorosulfonyl)imide, and lithium difluorophosphate, with a molar concentration of 1-1.5 M in the electrolyte.

[0030] Assembly of lithium-sulfur batteries. As an example, sulfur powder, conductive carbon black, carbon nanotubes, and PVDF binder were mixed in a mass ratio of 60:15:15:10, and N-methylpyrrolidone (NMP) solvent was added. After ball milling for 4–6 hours, a homogeneous slurry was formed. The slurry was coated onto carbon-containing aluminum foil using a scraper and then placed in a vacuum oven at 110°C for 10–12 hours to obtain the positive electrode. Using lithium metal sheets as the negative electrode and a Celgard 2400 separator, an electrolyte containing phthalocyanine compounds was prepared. A coin-type lithium-sulfur battery was assembled in an argon glove box.

[0031] As described above, the present invention does not impose any particular restrictions on the cathode material used in lithium-sulfur batteries. For example, cathode materials containing elemental sulfur, such as sulfur / carbon composite materials, sulfur / polymer composite materials, and sulfur / metal oxide composite materials, can also be cathode materials containing sulfur, such as lithium sulfide / carbon composite materials, lithium sulfide / polymer composite materials, and lithium sulfide / metal oxide composite materials.

[0032] The lithium-sulfur battery of the present invention does not have any particular restrictions on the negative electrode material. It can be one or more of lithium metal, lithium foil, lithium metal sheet, and lithium alloy, or it can be carbon material, silicon material, silicon / carbon composite material, metal oxide or conductive polymer, etc.

[0033] The lithium-sulfur battery in this invention does not have any particular restrictions on the separator; it can be a Celgard 2400 separator.

[0034] The lithium-sulfur battery structure of the present invention is not particularly limited and can be a button cell, a tubular cell, or a pouch cell, etc.

[0035] Assembly of a lithium-ion symmetric battery. As an example, lithium metal sheets are used for both positive and negative electrodes, a Celgard 2400 separator is used, an electrolyte containing phthalocyanine compounds is prepared, and a CR2032 battery case is used for the assembly of the lithium-ion symmetric battery.

[0036] As described above, the present invention does not impose any particular restrictions on the positive and negative electrode materials used in lithium-lithium symmetric batteries. The positive and negative electrodes can be one or more of lithium metal, lithium foil, lithium metal sheets, and lithium alloys.

[0037] The lithium-lithium symmetric battery in this invention does not have any particular limitations on the separator; it can be a Celgard 2400 separator.

[0038] The following examples further illustrate the present invention in detail. It should also be understood that the following examples are only for further explanation of the present invention and should not be construed as limiting the scope of protection of the present invention. Any non-essential improvements and adjustments made by those skilled in the art based on the above description of the present invention are 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 appropriate selections within the appropriate range based on the description herein, and are not intended to be limited to the specific values ​​in the examples below.

[0039] Example 1: Preparation of a lithium-sulfur battery with an electrolyte containing copper phthalocyanine

[0040] Electrolyte preparation: In an argon-filled glove box (O2, H2O < 0.1 ppm), 1.0 M lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) was added to a mixture of ethylene glycol dimethyl ether (DME) and 1,3-dioxolane (DOL), where DME:DOL (V:V) = 1:1. Then, 1.0 mM copper phthalocyanine and 0.2 M lithium nitrate were added. After stirring thoroughly for 12 h, a stable and homogeneous liquid was formed, which is the electrolyte.

[0041] Preparation of the cathode material: Sulfur powder, conductive carbon black, carbon nanotubes, and PVDF were mixed in a mass ratio of 60:15:15:10, and N-methylpyrrolidone (NMP) solvent was added. The mixture was ball-milled for 6 hours to form a stable and homogeneous slurry. This slurry was coated onto aluminum foil using a doctor blade and dried in a vacuum drying oven at 60°C for 12 hours. After drying, it was cut into 12mm diameter discs with a sulfur loading of 1.3 mg / cm³. -2 .

[0042] Assembly of coin cell lithium-sulfur batteries: The batteries are assembled in a glove box filled with argon (O2, H2O < 0.1ppm), in the following order: positive electrode, Celgard 2400 separator, negative electrode lithium metal sheet. Electrolyte is added to both sides of the separator, with a total electrolyte volume of 60μL, to assemble the coin cell lithium-sulfur battery.

[0043] Rate performance testing of lithium-sulfur batteries: The assembled batteries need to be left at room temperature for 10 hours, followed by cycle testing on a Newway testing machine with a voltage window of 1.7-2.8V at different rates (0.1C, 0.2C, 0.5C, 1C, 2C, 3C, 4C, 1C = 1675mAh g). -1 Tests were conducted under the following conditions.

[0044] Example 2: Preparation of a lithium-lithium symmetric battery with an electrolyte containing copper phthalocyanine

[0045] The electrolyte was prepared in the same manner as in Example 1.

[0046] Lithium-lithium symmetric battery assembly: The battery was assembled in a glove box filled with argon atmosphere (O2, H2O<0.1ppm), in the following order: positive electrode lithium metal sheet, Celgard2400 separator, negative electrode lithium metal sheet. Electrolyte was added to both sides of the separator, and the total amount of electrolyte was 60μL. The lithium-lithium symmetric battery was assembled using a CR2032 battery case.

[0047] Electroplating peeling long-cycle test: The assembled battery needs to be left at room temperature for 10 hours, followed by a current density of 1 mA cm⁻¹. -2 / 3mAh cm -2 Electroplating peeling cycle test was then performed.

[0048] Electroplating peeling cycle test: The assembled battery needs to be left at room temperature for 10 hours, followed by a current density of 1 mA / cm². -2 / 1mAh cm -2 The battery was subjected to an electroplating stripping cycle test. After 50 cycles, the battery was disassembled in a glove box, and the obtained lithium metal sheet was subjected to SEM testing.

[0049] Example 3: Preparation of a lithium-sulfur battery with an electrolyte containing copper phthalocyanine

[0050] Electrolyte preparation: In an argon-filled glove box (O2, H2O < 0.1 ppm), 1.0 M lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) was added to a mixture of ethylene glycol dimethyl ether (DME) and 1,3-dioxolane (DOL), where DME:DOL (V:V) = 1:1. Then, 0.5 mM copper phthalocyanine and 0.2 M lithium nitrate were added. After stirring thoroughly for 14 h, a stable and homogeneous liquid was formed, which is the electrolyte.

[0051] The preparation of the cathode material and the assembly of the lithium-sulfur battery are the same as in Example 1.

[0052] Rate performance testing of lithium-sulfur batteries: The assembled batteries need to be left at room temperature for 10 hours, followed by cycle testing on a Newway testing machine with a voltage window of 1.7-2.8V at different rates (0.1C, 0.2C, 0.5C, 1C, 2C, 3C, 4C, 1C = 1675mAh g). -1 Tests were conducted under the following conditions.

[0053] Example 4: Preparation of a lithium-sulfur battery with an electrolyte containing copper phthalocyanine

[0054] Electrolyte preparation: In an argon-filled glove box (O2, H2O < 0.1 ppm), 1.0 M lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) was added to a mixture of ethylene glycol dimethyl ether (DME) and 1,3-dioxolane (DOL), where DME:DOL (V:V) = 1:1. Then, 1.5 mM copper phthalocyanine and 0.2 M lithium nitrate were added. After stirring thoroughly for 16 h, a stable and homogeneous liquid was formed, which is the electrolyte.

[0055] The preparation of the cathode material and the assembly of the lithium-sulfur battery are the same as in Example 1.

[0056] Example 5: Preparation of a lithium-sulfur battery with an electrolyte containing copper phthalocyanine

[0057] Electrolyte preparation: In an argon-filled glove box (O2, H2O < 0.1 ppm), 1.0 M lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) was added to a mixture of ethylene glycol dimethyl ether (DME) and 1,3-dioxolane (DOL), where DME:DOL = 1:1 (V:V). Then, 2.0 mM copper phthalocyanine and 0.2 M lithium nitrate were added. After stirring thoroughly for 13 h, a stable and homogeneous liquid was formed, which is the electrolyte.

[0058] The preparation of the cathode material and the assembly of the lithium-sulfur battery are the same as in Example 1.

[0059] Rate performance testing of lithium-sulfur batteries: The assembled batteries need to be left at room temperature for 10 hours, followed by cycle testing on a Newway testing machine with a voltage window of 1.7-2.8V at different rates (0.1C, 0.2C, 0.5C, 1C, 2C, 3C, 4C, 1C = 1675mAh g). -1 Tests were conducted under the following conditions.

[0060] Comparative Example 1

[0061] Electrolyte preparation: In an argon-filled glove box (O2, H2O < 0.1 ppm), 1.0 M lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) was added to a mixture of ethylene glycol dimethyl ether (DME) and 1,3-dioxolane (DOL), where DME:DOL (V:V) = 1:1. Then, 0.2 M lithium nitrate was added, and the mixture was stirred thoroughly for 12 h to form a stable and homogeneous liquid, which is the basic electrolyte.

[0062] The preparation of the cathode material and the assembly of the lithium-sulfur battery are the same as in Example 1.

[0063] Rate performance testing of lithium-sulfur batteries: The assembled batteries need to be left at room temperature for 10 hours, followed by cycle testing on a Newway testing machine with a voltage window of 1.7-2.8V at different rates (0.1C, 0.2C, 0.5C, 1C, 2C, 3C, 4C, 1C = 1675mAh g). -1 Tests were conducted under the following conditions.

[0064] Comparative Example 2

[0065] Electrolyte preparation: In an argon-filled glove box (O2, H2O < 0.1 ppm), 1.0 M lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) was added to a mixture of ethylene glycol dimethyl ether (DME) and 1,3-dioxolane (DOL), where DME:DOL (V:V) = 1:1. Then, 0.2 M lithium nitrate was added, and the mixture was stirred thoroughly for 12 h to form a stable and homogeneous liquid, which is the basic electrolyte.

[0066] Lithium-lithium symmetric battery assembly: The battery was assembled in a glove box filled with argon atmosphere (O2, H2O<0.1ppm), in the following order: positive electrode lithium metal sheet, Celgard2400 separator, negative electrode lithium metal sheet. Electrolyte was added to both sides of the separator. The total amount of electrolyte was 80μL. The lithium-lithium symmetric battery was assembled using a CR2032 battery case.

[0067] Electroplating peeling long-cycle test: The assembled battery needs to be left at room temperature for 10 hours, followed by a current density of 1 mA cm⁻¹. -2 / 3mAh cm -2 Electroplating peeling cycle test was then performed.

[0068] Electroplating peeling cycle test: The assembled battery needs to be left at room temperature for 10 hours, followed by a current density of 1 mA / cm². -2 / 1mAh cm -2 The battery was subjected to an electroplating stripping cycle test. After 50 cycles, the battery was disassembled in a glove box, and the obtained lithium metal sheet was subjected to SEM testing.

[0069] Figure 1 This is a rate cycling comparison chart between the lithium-sulfur battery containing copper phthalocyanine electrolyte prepared in Example 1 and the lithium-sulfur battery without copper phthalocyanine electrolyte prepared in Comparative Example 1. Figure 1 It can be seen that the lithium-sulfur battery containing copper phthalocyanine and lithium nitrate electrolyte has more stable rate performance and achieves higher discharge specific capacity, while the lithium-sulfur battery without copper phthalocyanine electrolyte exhibits very obvious fluctuations under high rate current conditions, accompanied by a rapid decrease in capacity.

[0070] Figure 2This is a rate cycling comparison chart between the lithium-sulfur battery prepared in Example 3 with a 0.5 mM copper phthalocyanine electrolyte and the lithium-sulfur battery prepared in Example 5 with a 2.0 mM copper phthalocyanine electrolyte. Figure 2 It can be seen that the batteries containing 0.5mM and 2.0mM copper phthalocyanine have better rate performance than the batteries without additives, but both are lower than the batteries containing 1.0mM copper phthalocyanine. This indicates that too little copper phthalocyanine cannot form a stable and uniform functional film on the lithium surface, while too much copper phthalocyanine will hinder lithium ion migration.

[0071] Figure 3 The lithium-lithium symmetric battery containing copper phthalocyanine electrolyte prepared in Example 2 and the lithium-lithium symmetric battery without copper phthalocyanine electrolyte prepared in Comparative Example 2 were compared at 1 mA cm⁻¹. -2 / 3mAh cm -2 Long loop comparison chart, through Figure 3 It can be seen that, compared with lithium-sulfur batteries without copper phthalocyanine electrolyte, lithium-sulfur batteries with copper phthalocyanine electrolyte exhibit less voltage hysteresis.

[0072] Figure 4 The lithium-ion symmetric battery with a 1 mA cm⁻¹ corresponding to the electrolyte without copper phthalocyanine in Comparative Example 2. -2 / 1mAh cm -2 SEM image after 50 cycles; Figure 5 The 1 mA cm-type lithium-lithium symmetric battery corresponding to the electrolyte containing copper phthalocyanine in Example 2. -2 / 1mAh cm -2 SEM image after 50 cycles. Figure 4 , Figure 5 It can be seen that in lithium-sulfur batteries containing copper phthalocyanine and lithium nitrate electrolytes, the lithium surface morphology is more uniform and compact with fewer pores, while in batteries without copper phthalocyanine, the lithium surface morphology is rough, porous, and has obvious dendrite growth. This indicates that the electrolyte described in this invention has a significant effect on protecting the negative electrode, inhibiting dendrite growth, and improving the negative electrode morphology.

[0073] The preferred embodiments of this patent have been described in detail above. However, this patent is not limited to the above embodiments. Within the scope of knowledge possessed by those skilled in the art, other variations or modifications can be made. It is neither necessary nor possible to exhaustively list all embodiments here. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this invention should be included within the protection scope of the claims of this invention.

Claims

1. A lithium-sulfur battery electrolyte comprising a phthalocyanine compound, characterized in that, The electrolyte is composed of conductive lithium salt, ether solvent, main additive, and secondary additive; the main additive is a phthalocyanine compound. The phthalocyanine compounds are one or more of copper phthalocyanine, iron phthalocyanine, nickel phthalocyanine, zinc phthalocyanine, and cobalt phthalocyanine. The molar concentration of the phthalocyanine compound in the electrolyte is 0.01-4 mM; The molar concentration of the additive in the electrolyte is 0.1-0.5 M; The ether solvent is a mixture of ethylene glycol dimethyl ether and 1,3-dioxolane, with a volume ratio of 0.8-1.3:

1. The molar concentration of the conductive lithium salt in the electrolyte is 1-1.5M.

2. The lithium-sulfur battery electrolyte containing phthalocyanine-based compounds according to claim 1, characterized in that, The molar concentration of the phthalocyanine compound in the electrolyte is 0.5-2.0 mM.

3. The lithium-sulfur battery electrolyte containing phthalocyanine compounds according to claim 1, characterized in that, The additive is one or more of lithium nitrate, lanthanum nitrate, praseodymium nitrate, neodymium nitrate, lithium polysulfide, and lithium iodide.

4. The lithium-sulfur battery electrolyte containing phthalocyanine-based compounds according to claim 1, characterized in that, The ether solvent is any two mixed solvents selected from 1,3-dioxapentane, 1,4-dioxane, ethylene glycol dimethyl ether, diethylene glycol dimethyl ether, 2-methyltetrahydrofuran, dimethoxymethane, sulfolane, ethyl methyl sulfone, isopropyl methyl sulfone, dimethyl disulfide, dimethyl trisulfide, and dimethyl sulfide.

5. The lithium-sulfur battery electrolyte containing phthalocyanine-based compounds according to claim 1, characterized in that, The conductive lithium salt is one or more of lithium hexafluorophosphate, lithium bis(oxalato)borate, lithium bis(trifluoromethanesulfonyl)imide, lithium bis(fluorosulfonyl)imide, and lithium bis(fluorophosphate).

6. The method for preparing a lithium-sulfur battery electrolyte containing phthalocyanine compounds according to any one of claims 1 to 5, characterized in that, The conductive lithium salt, secondary additives, primary additives, and ether solvents are mixed and stirred at 25°C for 12-16 hours at a stirring speed of 600-1200 r / s to form a stable and homogeneous liquid, which is the electrolyte.

7. The application of a lithium-sulfur battery electrolyte containing phthalocyanine compounds as described in any one of claims 1-5 in the preparation of lithium-sulfur batteries, characterized in that, The lithium-sulfur battery includes a positive electrode, a negative electrode, a separator, and a lithium-sulfur battery electrolyte containing phthalocyanine compounds.

Images