Preparation method of positive electrode material and battery

Abstract

The application provides a positive electrode material preparation method and a battery, and is applied to the technical field of batteries. The method comprises the following steps: obtaining nano-sulfur prepared from sodium thiosulfate and hydrochloric acid; placing the nano-sulfur, polyacrylic acid, carbon disulfide and azobisisobutyronitrile in a reaction container to generate a first reaction, so as to obtain a first mixture, wherein the temperature of the first reaction ranges from 150 DEG C to 250 DEG C; and annealing the first mixture under the protection of argon, so as to obtain a sulfur positive electrode material. The in-situ generated nano-sulfur and the porous structure formed due to carbon disulfide improve the ion and electron conductivity of the sulfur positive electrode material, so that the capacity of the battery is improved.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of batteries, in particular to a positive electrode material preparation method and a battery. BACKGROUND

[0002] Improving the energy density of the standby battery of a communication base station is an important way to improve the efficiency of communication services. Among many new types of batteries, lithium-sulfur batteries have broad application potential based on high energy density. However, lithium-sulfur batteries based on liquid electrolyte face the problems of active material loss caused by the easy dissolution of polysulfides in the electrolyte and safety problems caused by the irregular lithium dendrite growth puncturing the separator. Compared with liquid electrolyte, solid electrolyte has the characteristics of light weight, high safety and no loss of active material. However, due to the contact problem at the solid interface, the ion exchange between the positive electrode and the electrolyte in the solid-state electrolyte is generally lower than that in the liquid electrolyte, thereby resulting in low battery capacity. SUMMARY

[0003] Embodiments of the application provide a positive electrode material preparation method and device to solve the problem of low battery capacity of the battery formed by the positive electrode material prepared by the existing positive electrode material preparation method.

[0004] To solve the above technical problems, the application is implemented as follows:

[0005] In a first aspect, the embodiments of the application provide a positive electrode material preparation method. The method comprises:

[0006] Obtaining nano-sulfur prepared from sodium thiosulfate and hydrochloric acid;

[0007] Placing the nano-sulfur, polyacrylic acid, carbon disulfide and azobisisobutyronitrile in a reaction container to occur a first reaction, to obtain a first mixture, and the temperature of the first reaction is in the range of 150-250°C;

[0008] Annealing the first mixture under argon protection to obtain a sulfur positive electrode material.

[0009] Optionally, the obtaining of the nano-sulfur prepared from sodium thiosulfate and hydrochloric acid comprises:

[0010] Adding sodium thiosulfate to a flask with an ambient temperature of zero degrees Celsius, and the mass of the sodium thiosulfate is in the range of 10-100 grams;

[0011] Adding hydrochloric acid to the flask containing sodium thiosulfate at a first rate and stirring to obtain a second mixture, the first rate is in the range of 5-200 milliliters / minute, the concentration of the hydrochloric acid is in the range of 0.1-0.6 moles / liter, and the volume of the hydrochloric acid is in the range of 100-1000 milliliters;

[0012] After the ambient temperature of the flask is raised from zero degrees Celsius to a first temperature at a first temperature raising speed, the second mixture is stirred in an argon gas stream for a first time length to obtain a third mixture, the first temperature raising speed ranges from 0.5 to 2 degrees Celsius per minute, the first temperature ranges from 25 to 40 degrees Celsius, and the first time length ranges from 2 to 6 hours.

[0013] The third mixture is vacuum filtered, and the third mixture after vacuum filtration is cleaned with an aqueous solution to obtain nano sulfur.

[0014] Optionally, after the third mixture is vacuum filtered and cleaned with an aqueous solution to obtain nano sulfur, the method further comprises:

[0015] After the nano sulfur is stored at a second temperature for a second time length, the nano sulfur is dried in a freeze dryer for a third time length.

[0016] The second temperature ranges from -30 to -10 degrees Celsius, the second time length ranges from 6 to 12 hours, the third time length ranges from 12 to 24 hours, and the particle size of the nano sulfur ranges from 100 to 600 nanometers.

[0017] Optionally, the adding of sodium thiosulfate into the flask with an ambient temperature of zero degrees Celsius comprises:

[0018] Sodium thiosulfate is added to the flask, and the flask with the added sodium thiosulfate is placed in a refrigeration device, and the temperature in the refrigeration device is lowered to zero degrees Celsius at a first temperature lowering speed, and the first temperature lowering speed ranges from 3 to 5 degrees Celsius per minute.

[0019] Optionally, the placing of the nano sulfur, polyacrylic acid, carbon disulfide, and azobisisobutyronitrile in a reaction container to undergo a high-temperature reaction to obtain a first mixture comprises:

[0020] The nano sulfur and the polyacrylic acid are uniformly mixed at a first molar ratio and then placed in a ball mill for a fourth time length to obtain a fourth mixture, the first molar ratio ranges from 2 to 4:1, the rotational speed of the ball mill ranges from 300 to 600 revolutions per minute, and the fourth time length ranges from 6 to 12 hours.

[0021] The fourth mixture and the azobisisobutyronitrile are mixed at a first mass ratio to obtain a fifth mixture, and the first mass ratio ranges from 10 to 20:1.

[0022] The fifth mixture is placed in a hydrothermal reactor, carbon disulfide is added to the hydrothermal reactor at a second rate according to the mass of the fifth mixture, and the reaction temperature is increased to a third temperature at a second temperature increasing rate, and after a fifth time length, the reaction is naturally cooled to obtain the first mixture, wherein the second rate is 0.02-0.5 mL / g, the second temperature increasing rate is 5-10 ℃ / min, the third temperature is 150-250 ℃, and the fifth time length is 12-24 hours.

[0023] Optionally, the annealing of the first mixture under the protection of argon to obtain the sulfur positive electrode material comprises:

[0024] The first mixture is placed in a tube furnace and annealed in an argon gas stream at a fourth temperature for a sixth time length to obtain the sulfur positive electrode material, wherein the fourth temperature is 400-500 ℃, and the sixth time length is 1-3 hours.

[0025] Optionally, after the annealing of the first mixture under the protection of argon to obtain the sulfur positive electrode material, the method further comprises:

[0026] The sulfur positive electrode material, conductive carbon, and solid-state electrolyte are placed in a ball mill at a second mass ratio for a seventh time length to obtain an electrode powder, the second mass ratio is 1:(0.1-0.3):(0.05-0.1), and the seventh time length is 2-3 hours.

[0027] The electrode powder is placed in a tabletting device for compaction, the pressure of the tabletting device is 150-400 Mpa, and the compacted electrode powder is used to assemble a solid-state lithium-sulfur battery with the solid-state electrolyte and lithium metal.

[0028] Optionally, the solid-state electrolyte is any one of polyvinylidene fluoride, polyvinylidene fluoride, polyethylene oxide, polyacrylic acid, and polyvinyl alcohol.

[0029] In a second aspect, the embodiments of the present application further provide a battery.

[0030] The positive electrode material preparation method of the embodiment of the present application is to obtain nano sulfur prepared by sodium thiosulfate and hydrochloric acid; the nano sulfur, polyacrylic acid, carbon disulfide and azobisisobutyronitrile are placed in a reaction container to have a first reaction to obtain a first mixture, and the temperature of the first reaction ranges from 150 to 250 DEG C; the first mixture is annealed under argon protection to obtain a sulfur positive electrode material. The nano sulfur generated in situ and the porous structure formed by carbon disulfide improve the ion and electron conductivity of the sulfur positive electrode material, thereby improving the battery capacity. BRIEF DESCRIPTION OF DRAWINGS

[0031] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings needed in the description of the embodiments of the present application will be briefly introduced. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor.

[0032] Figure 1 is a flow chart of the positive electrode material preparation method provided by the embodiments of the present application;

[0033] Figure 2 is a schematic diagram of the structure of a solid-state lithium-sulfur battery provided by the embodiments of the present application;

[0034] Figure 3 is a scanning electron microscope image of the sulfur positive electrode material provided by Example 1 of the present application;

[0035] Figure 4 is a cycle curve diagram of the solid-state lithium-sulfur battery provided by Example 1 of the present application;

[0036] Figure 5 is a charge-discharge curve diagram of the cycle curve in Figure 4

[0037] Figure 6 is a rate cycle curve diagram of the solid-state lithium-sulfur battery provided by Example 1 of the present application. DETAILED DESCRIPTION

[0038] The technical solutions of the embodiments of the present application will be described clearly and completely in the following with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only some embodiments of the present application, not all embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor are within the scope of protection of the present application.

[0039] The embodiments of the present application provide a positive electrode material preparation method. Referring to Figure 1 , Figure 1 is a flow chart of the positive electrode material preparation method provided by the embodiments of the present application, as​Figure 1 as shown, comprising the following steps:

[0040] Step 101, obtaining nano-sulfur prepared by sodium thiosulfate and hydrochloric acid;

[0041] Step 102, placing the nano-sulfur, polyacrylic acid, carbon disulfide and azobisisobutyronitrile in a reaction container to occur a first reaction, obtaining a first mixture, and the temperature of the first reaction is in the range of 150-250℃;

[0042] Step 103, annealing the first mixture under argon protection to obtain a sulfur positive electrode material.

[0043] In the positive electrode material preparation method of the embodiment of the present application, first, nano-sulfur is prepared by sodium thiosulfate and hydrochloric acid. It should be noted that the nano-sulfur and polyacrylic acid also need to be ball milled into a uniform powder in a ball mill, and then the ball milled powder is placed in a reaction container to occur a first reaction with an appropriate amount of carbon disulfide and azobisisobutyronitrile, wherein the temperature of the first reaction is in the range of 150-250℃. Then, the first mixture obtained by the foregoing first reaction is annealed in argon protection, and a sulfur positive electrode material suitable for a solid-state lithium-sulfur battery can be obtained. The foregoing reaction container can be a reaction kettle, and the foregoing annealing refers to calcining the material in a high-temperature furnace. The annealing temperature can be 400℃, and the annealing time can be 1 hour.

[0044] The positive electrode material preparation method of the embodiment of the present application improves the ion and electron conductivity of the sulfur positive electrode material through the in-situ generated nano-sulfur and the porous structure caused by carbon disulfide, thereby improving the battery capacity.

[0045] Optionally, the obtaining of the nano-sulfur prepared by sodium thiosulfate and hydrochloric acid comprises:

[0046] Sodium thiosulfate is added to a flask with an ambient temperature of zero degrees Celsius, and the mass of the sodium thiosulfate is in the range of 10-100 grams;

[0047] Hydrochloric acid is added to the flask containing sodium thiosulfate at a first rate and stirred to obtain a second mixture, the first rate is in the range of 5-200 milliliters / minute, the concentration of the hydrochloric acid is in the range of 0.1-0.6 moles / liter, and the volume of the hydrochloric acid is in the range of 100-1000 milliliters;

[0048] After the ambient temperature of the flask is raised from zero degrees Celsius to a first temperature at a first temperature raising speed, the second mixture is stirred in an argon gas stream for a first time length to obtain a third mixture, the first temperature raising speed is 0.5-2 degrees Celsius per minute, the first temperature is 25-40 degrees Celsius, and the first time length is 2-6 hours;

[0049] The third mixture is vacuum filtered, and the third mixture after vacuum filtration is washed with an aqueous solution to obtain nano sulfur.

[0050] In the method for preparing the positive electrode material, 50 g of sodium thiosulfate is added to a flask in which the ambient temperature is zero degrees Celsius, 200 ml of hydrochloric acid is added to the flask containing 50 g of sodium thiosulfate at a dropping speed of 10 ml / min and stirred to obtain a second mixture, wherein the concentration of the hydrochloric acid is 0.5 mol / L, and it should be noted that high-speed stirring is required during the dropping of the hydrochloric acid.

[0051] After the dropping is completed, the ambient temperature of the flask is raised from zero degrees Celsius to 30 degrees Celsius at a temperature raising speed of 1 degree Celsius per minute, and then the second mixture is stirred in the protection of an argon gas stream for 3 hours to ensure uniform mixing, and the stirring is completed to obtain a third mixture. Then, the third mixture is vacuum filtered, and the third mixture after vacuum filtration is repeatedly washed with an aqueous solution to obtain nano sulfur, and it should be noted that the nano sulfur obtained in this embodiment is a crude nano sulfur particle. The method for preparing the positive electrode material controls the reaction temperature and the stirring time, which is beneficial to the reaction of sodium thiosulfate and hydrochloric acid.

[0052] Optionally, after the third mixture is vacuum filtered and washed with an aqueous solution to obtain nano sulfur, the method further comprises:

[0053] After the nano sulfur is stored at a second temperature for a second time length, the nano sulfur is dried in a freeze dryer for a third time length;

[0054] The second temperature is -30 to -10 degrees Celsius, the second time length is 6-12 hours, the third time length is 12-24 hours, and the particle size of the nano sulfur is 100-600 nm.

[0055] In the preparation method of the positive electrode material, after the third mixture is vacuum filtered and the third mixture after the vacuum filtration is cleaned by using the aqueous solution to obtain the nano sulfur, the nano sulfur is exemplarily placed in zero below 30 degrees Celsius for frozen storage for 6 hours, and after being completely frozen, sublimation drying is performed in a freeze dryer for 12 hours, and finally the refined nano sulfur particles are obtained. It should be noted that the size of the obtained refined nano sulfur particles is 200 nanometers. The method can quickly sublimate ice by freeze drying, form a porous structure in the nano sulfur, and facilitate the transmission of ions and electrons.

[0056] Optionally, the adding of the sodium thiosulfate into the flask with the ambient temperature of zero degrees Celsius comprises:

[0057] The sodium thiosulfate is added into the flask, and the flask with the added sodium thiosulfate is placed in a freezing device, and the temperature in the freezing device is reduced to zero degrees Celsius at a first cooling rate, and the first cooling rate is in a range of 3-5 degrees Celsius per minute.

[0058] In the preparation method of the positive electrode material, exemplarily, 50 grams of sodium thiosulfate is weighed and poured into a flask, and then the flask is placed in a freezing device, and the temperature is reduced to zero degrees Celsius at a cooling rate of 3 degrees Celsius per minute, which is beneficial to control the reaction rate.

[0059] Optionally, the high-temperature reaction of the nano sulfur, the polyacrylic acid, the carbon disulfide, and the azobisisobutyronitrile in the reaction container to obtain a first mixture comprises:

[0060] The nano sulfur and the polyacrylic acid are uniformly mixed at a first molar ratio and then placed in a ball mill for ball milling for a fourth time length to obtain a fourth mixture, wherein the first molar ratio is in a range of (2-4):1, the rotation speed of the ball mill is in a range of 300-600 revolutions per minute, and the fourth time length is in a range of 6-12 hours.

[0061] The fourth mixture and the azobisisobutyronitrile are mixed at a first mass ratio to obtain a fifth mixture, and the first mass ratio is in a range of (10-20):1.

[0062] The fifth mixture is placed in a hydrothermal reactor, carbon disulfide is added to the hydrothermal reactor at a second rate according to the mass of the fifth mixture, and the reaction temperature is increased to a third temperature at a second temperature increasing rate, and after a fifth time length, the first mixture is obtained by natural cooling, wherein the second rate is 0.02-0.5 ml / g, the second temperature increasing rate is 5-10 ℃ / min, the third temperature is 150-250 ℃, and the fifth time length is 12-24 hours.

[0063] In the preparation method of the positive electrode material, the nano-sulfur and the polyacrylic acid are mixed uniformly at a molar ratio of 4:1, and then placed in a ball mill for 12 hours to obtain a fourth mixture, wherein the rotation speed of the ball mill is 500 rpm, and then the fourth mixture is mixed with azobisisobutyronitrile at a mass ratio of 15:1 to obtain a fifth mixture.

[0064] The fifth mixture is then placed in a hydrothermal reactor, carbon disulfide solution is added to the hydrothermal reactor at a rate of 0.5 ml / g according to the mass of the fifth mixture, and then the reaction temperature is increased to 250 ℃ at a temperature increasing rate of 10 ℃ / min, and after 20 hours of reaction, the first mixture is obtained by natural cooling, which is a high-ionic-conductivity sulfur positive electrode material precursor. The azobisisobutyronitrile in the present embodiment acts as a catalyst, which is beneficial to improve the carboxyl activity of the polyacrylic acid.

[0065] Optionally, the annealing of the first mixture under argon protection to obtain the sulfur positive electrode material comprises:

[0066] The first mixture is placed in a tube furnace and annealed in an argon gas stream at a fourth temperature for a sixth time length to obtain the sulfur positive electrode material, wherein the fourth temperature is 400-500 ℃, and the sixth time length is 1-3 hours.

[0067] In the preparation method of the positive electrode material, the first mixture is placed in a tube furnace and annealed in an argon gas stream at 450 ℃ for 1 hour to obtain the sulfur positive electrode material. In this method, annealing is beneficial to reduce hardness and improve the plasticity of the sulfur positive electrode material.

[0068] Optionally, after the annealing of the first mixture under argon protection to obtain the sulfur positive electrode material, the method further comprises:

[0069] ball-milling the sulfur cathode material, the conductive carbon and the solid-state electrolyte in a ball mill for a seventh time length according to a second mass ratio, to obtain an electrode powder, the second mass ratio being in a range of 1:(0.1-0.3):(0.05-0.1), and the seventh time length being in a range of 2-3 hours;

[0070] ball-milling the sulfur cathode material, the conductive carbon and the solid-state electrolyte in a ball mill for a seventh time length according to a second mass ratio, to obtain an electrode powder, the second mass ratio being in a range of 1:(0.1-0.3):(0.05-0.1), and the seventh time length being in a range of 2-3 hours;

[0071] In the method for preparing the cathode material, the sulfur cathode material, the conductive carbon and the solid-state electrolyte are weighed according to the mass ratio of 1:0.1:0.05, and then are ball-milled in a ball mill for 3 hours to obtain an electrode powder. Then, the electrode powder is compacted by using a tablet press device, and the pressure is controlled at 200 Mpa. Then, the compacted electrode powder, the solid-state electrolyte and the lithium metal are assembled into a solid-state lithium-sulfur battery in a conventional manner. It should be noted that the conductive carbon includes but is not limited to acetylene black, ketjen black, carbon nanotube, graphene and graphene oxide. The solid-state electrolyte is any one of polyvinylidene fluoride, polyvinylidene fluoride, polyethylene oxide, polyacrylic acid and polyvinyl alcohol. The solid-state electrolyte includes but is not limited to any one or a mixture of two of polyethylene oxide, polyacrylonitrile, polyvinylidene fluoride, polymethyl methacrylate, polypropylene oxide, polyvinylidene chloride, lithium-phosphorus-oxynitride electrolyte film and sulfide crystalline solid-state electrolyte (Li4-xGe1-xPxS4; 0.1≤x≤0.9). The electronic and ionic conductivities of the obtained sulfur cathode material are both greater than 10-3 S / cm.

[0072] Referring to Figure 2 , Figure 2 A solid-state lithium-sulfur battery structure provided by the embodiment of the present application is shown in the figure, wherein 1 represents the sulfur cathode material, 2 represents the solid-state electrolyte, and 3 represents the lithium metal anode. As can be seen from the figure, the method of the embodiment of the present application only needs to physically extrude the sulfur cathode material, the solid-state electrolyte and the lithium metal together to form an integrated structure, without the need of injecting electrolyte again, which facilitates the assembly of the battery and improves the production efficiency of the battery. In addition, the powder of structure 1 only needs to be laid on the surface of structure 2, and then is dry-pressed, without the need of preparing the sulfur cathode material in a conventional manner.

[0073] Optionally, the solid-state electrolyte is any one of polyvinylidene fluoride, polyvinylidene fluoride, polyethylene oxide, polyacrylic acid and polyvinyl alcohol.

[0074] In the preparation method of the positive electrode material, the solid electrolyte is any one of polyvinyl fluoride, polyvinylidene fluoride, polyethylene oxide, polyacrylic acid, and polyvinyl alcohol, which is conducive to improving the bonding performance.

[0075] To further illustrate the preparation method of the positive electrode material, two examples are provided below to illustrate the embodiments of the present application.

[0076] Example 1: The preparation method of the positive electrode material provided in this example includes the following steps:

[0077] Step 1: 30 grams of sodium thiosulfate is weighed into a three-necked flask, then the three-necked flask is placed in a refrigeration device, and the temperature in the refrigeration device is reduced to 0 degrees Celsius at a cooling rate of 2 degrees Celsius per minute to control the reaction rate. Then, 100 milliliters of hydrochloric acid with a concentration of 0.2 moles per liter is added at a drop rate of 20 milliliters per minute, and high-speed stirring is maintained during the drop process. A second mixture is obtained;

[0078] Step 2: After the drop is completed, the stirring temperature is increased to 30 degrees Celsius at a heating rate of 0.8 degrees Celsius per minute, and the second mixture is kept stirring for 4 hours under the protection of argon gas flow to ensure uniform mixing. After stirring is completed, a third mixture is obtained. The third mixture is vacuum filtered, and the vacuum filtered third mixture is washed with an aqueous solution to obtain a preliminary nano-sulfur. It should be noted that the nano-sulfur obtained here is a crude nano-sulfur particle;

[0079] Step 3: The crude nano-sulfur particles are stored in a freezer at minus 20 degrees Celsius for 10 hours, and after complete freezing, sublimation drying is performed in a freeze dryer for 16 hours to obtain nano-sulfur. It should be noted that the nano-sulfur obtained here is a refined nano-sulfur particle with a size of 100 nanometers;

[0080] Step 4: The nano-sulfur obtained in step 3 and polyacrylic acid are uniformly mixed and placed in a high-energy ball mill for 7 hours to obtain a fourth mixture. The molar ratio of nano-sulfur to polyacrylic acid is controlled at 3:1, and the rotation speed of the ball mill is 300 revolutions per minute;

[0081] Step 5: After ball milling is completed, the fourth mixture and azobisisobutyronitrile are mixed to obtain a fifth mixture. Azobisisobutyronitrile acts as a catalyst to improve the carboxyl activity of polyacrylic acid. The mass ratio of the fourth mixture to azobisisobutyronitrile is controlled at 15:1;

[0082] Step 6: The fifth mixture is placed in a hydrothermal reactor, according to the mass of the fifth mixture, 0.04 milliliter / gram of carbon disulfide solution is added dropwise, then the reaction temperature is increased to 200 degrees Celsius at a temperature increasing rate of 5 degrees Celsius per minute, and after 18 hours of reaction, the first mixture, a high ionic conductivity sulfur positive electrode material precursor, is obtained by natural cooling;

[0083] Step 7: The fifth mixture is placed in a tube furnace and annealed at 400 degrees Celsius for 2 hours to obtain a sulfur positive electrode material;

[0084] Then, the sulfur positive electrode material obtained in step 7 is applied to a solid-state lithium-sulfur battery:

[0085] Step 8: The sulfur positive electrode material, conductive carbon, and solid-state electrolyte are weighed according to a mass ratio of 1:0.1:0.08, and then placed in a ball mill for 3 hours to obtain electrode powder;

[0086] Step 9: The electrode powder is compacted using a tablet press device, and the pressure is controlled at 200 Mpa;

[0087] Step 10: The compacted electrode powder, solid-state electrolyte, and lithium metal are assembled into a solid-state lithium-sulfur battery in a conventional and conventional manner.

[0088] Referring to Figure 3 , Figure 3 The scanning electron microscope image of the sulfur positive electrode material obtained in Example 1 of the present application shows that the sulfur positive electrode material prepared by the positive electrode preparation method provided by the present application has a porous distribution, and the sulfur particles are stacked to form a network structure, which is beneficial to electrode preparation, forms a compact electrode structure, and realizes the improvement of battery performance.

[0089] Referring to Figure 4 , Figure 4 The cycle curve of the solid-state lithium-sulfur battery prepared in Example 1 of the present application is shown in the figure, and the battery cycle rate is 0.2C cycle. As can be observed from the figure, the stability of the battery is greatly improved, and the discharge capacity can reach 1200 mAh / g, which is much higher than that of existing solid-state lithium-sulfur batteries, indicating that the sulfur positive electrode material prepared by the present application is completely suitable for solid-state lithium-sulfur batteries. In addition, from the cycle stability, it can be observed that during the 50 cycles, the capacity retention rate can reach 98% retention rate, which again indicates that the present application can greatly improve the stability of the solid-state lithium-sulfur battery, promote its commercialization, that is, meet the requirements of high energy density and long cycle life.

[0090] Referring to Figure 5 , Figure 5 is Figure 4The charge-discharge curve of the cycle curve can be observed from the graph. The charge-discharge platform voltage of the solid-state lithium-sulfur battery prepared by the embodiment of the present application is 2.0V, and no polysulfide of the lithium-sulfur battery is generated, which greatly promotes the improvement of the cycle stability of the solid-state lithium-sulfur battery, and confirms the advancement of the sulfur positive electrode material prepared by the present application, i.e. no polysulfide is generated, and only solid-phase reaction occurs in the material.

[0091] Referring to Figure 6 , Figure 6 The rate cycle curve of the solid-state lithium-sulfur battery prepared according to the embodiment 1 of the present application can be observed from the curve. Even if the current density is increased to 4C, the capacity of the battery can reach 600mAh / g, which fully proves that the sulfur positive electrode material prepared by the present application not only solves the electronic insulation of the traditional sulfur positive electrode, but also greatly improves the ionic conductivity of the electrode material, so that the lithium ion can quickly react with the positive electrode material, and the demand of high rate (5C) and high capacity (1200mAh / g) can be met.

[0092] Example two: the positive electrode material preparation method provided in the present example includes the following steps:

[0093] Step 1: weigh 100 grams of sodium thiosulfate into a three-necked flask, then place the three-necked flask in a refrigeration device, and reduce the temperature in the refrigeration device to 0 degrees Celsius at a cooling rate of 5 degrees Celsius per minute to control the reaction rate. Then add 1000 milliliters of 0.1 mole / liter hydrochloric acid at a dropping rate of 5 milliliters per minute, and always keep high-speed stirring during the dropping process to obtain a second mixture;

[0094] Step 2: after the dropping is completed, increase the stirring temperature to 40 degrees Celsius at a temperature increasing rate of 0.5 degrees Celsius per minute, and keep the second mixture under stirring for 6 hours under the protection of argon gas flow to ensure uniform mixing, and obtain a third mixture after the stirring is completed. The third mixture is vacuum filtered, and the third mixture after vacuum filtration is washed with an aqueous solution to preliminarily obtain nano sulfur. It should be noted that the nano sulfur obtained here is a crude nano sulfur particle;

[0095] Step 3: freeze the crude nano sulfur particles in minus 30 degrees Celsius for 12 hours, and sublimate and dry in a freeze dryer for 14 hours after complete freezing, to finally obtain nano sulfur. It should be noted that the nano sulfur obtained here is a refined nano sulfur particle, and the size is 600 nanometers;

[0096] Step 4: uniformly mix the nano sulfur obtained in step 3 and polyacrylic acid, and then place them in a high-energy ball mill for ball milling for 12 hours to obtain a fourth mixture, wherein the molar ratio of nano sulfur to polyacrylic acid is controlled at 3:1, and the rotating speed of the ball mill is 300 revolutions per minute;

[0097] Step 5: After the ball milling is completed, the fourth mixture and azobisisobutyronitrile are mixed to obtain a fifth mixture, and the azobisisobutyronitrile acts as a catalyst for improving the carboxyl activity of the polyacrylic acid, wherein the mass ratio of the fourth mixture to the azobisisobutyronitrile is controlled to be 10:1;

[0098] Step 6: The fifth mixture is placed in a hydrothermal reaction kettle, and according to the mass of the fifth mixture, 0.5 milliliter per gram of carbon disulfide solution is added dropwise, and then the reaction temperature is increased to 150 degrees Celsius at a temperature increasing rate of 10 degrees Celsius per minute, and after 24 hours of reaction, the first mixture, i.e., a high-ionic-conductivity sulfur positive electrode material precursor, is obtained after natural cooling;

[0099] Step 7: The fifth mixture is placed in a tube furnace and annealed at 500 degrees Celsius for 3 hours to obtain a sulfur positive electrode material;

[0100] After that, the sulfur positive electrode material obtained in step 7 is applied to a solid-state lithium-sulfur battery:

[0101] Step 8: After the sulfur positive electrode material, conductive carbon, and solid-state electrolyte are weighed according to a mass ratio of 1:0.2:0.1, they are placed in a ball mill for 3 hours to obtain electrode powder;

[0102] Step 9: The electrode powder is compacted using a tablet pressing device, and the pressure is controlled to be 250 Mpa;

[0103] Step 10: The compacted electrode powder, the solid-state electrolyte, and lithium metal are assembled into a solid-state lithium-sulfur battery in a conventional and regular manner.

[0104] In a second aspect, the embodiments of the present application also provide a battery. The battery includes the positive electrode material prepared by the positive electrode material preparation method provided in any of the embodiments.

[0105] It should be noted that in this document, the terms “comprising”, “including”, or any other variant thereof are intended to cover non-exclusive inclusion, so that processes, methods, articles, or devices including a series of elements not only include those elements, but also include other elements not explicitly listed, or further include elements inherent to such processes, methods, articles, or devices. Without more limitations, the element defined by the statement “comprising a” does not exclude the presence of additional identical elements in the process, method, article, or device including the element.

[0106] Those skilled in the art can clearly understand the above-mentioned embodiment method can be realized by means of software and the necessary general hardware platform, of course, also can be through hardware, but many cases the former is the better embodiment. Based on such understanding, the technical solutions of the present application essentially or say the part of the contribution to the prior art can be embodied in the form of software products, the computer software product is stored in a storage medium (such as ROM / RAM, magnetic disc, optical disc), including a number of instructions to make a terminal (may be a mobile phone, computer, server, air conditioner, or network equipment, etc.) executes the method described in various embodiments of the present application.

[0107] The embodiments of the present application are described above in conjunction with the drawings, but the present application is not limited to the above-mentioned specific embodiments, the above-mentioned specific embodiments are only illustrative, but not limited, those skilled in the art can make many forms without departing from the purpose of the present application and the scope of the claims under the inspiration of the present application, all belong to the protection of the present application.

Claims

1. A method for preparing a cathode material, characterized in that, The method comprises: obtaining nano-sulfur prepared from sodium thiosulfate and hydrochloric acid; placing the nano-sulfur, polyacrylic acid, carbon disulfide and azobisisobutyronitrile in a hydrothermal reaction kettle to generate a first reaction, obtaining a first mixture, and the temperature of the first reaction ranges from 150 to 250 DEG C; annealing the first mixture under argon protection to obtain a sulfur positive electrode material.

2. The method for preparing the cathode material according to claim 1, characterized in that, The method comprises: adding sodium thiosulfate to a flask with an ambient temperature of 0 DEG C, and the mass of the sodium thiosulfate ranges from 10 to 100 g; adding hydrochloric acid to the flask with the sodium thiosulfate at a first rate and stirring to obtain a second mixture, the first rate ranges from 5 to 200 ml / min, the concentration of the hydrochloric acid ranges from 0.1 to 0.6 mol / L, and the volume of the hydrochloric acid ranges from 100 to 1000 ml; increasing the ambient temperature of the flask from 0 DEG C to a first temperature at a first temperature increasing rate, then stirring the second mixture in an argon stream for a first time length to obtain a third mixture, the first temperature increasing rate ranges from 0.5 to 2 DEG C / min, the first temperature ranges from 25 to 40 DEG C, and the first time length ranges from 2 to 6 h; vacuum filtering the third mixture and washing the vacuum filtered third mixture with an aqueous solution to obtain nano-sulfur.

3. The method for preparing the cathode material according to claim 2, characterized in that, After the vacuum filtering and washing, the method further comprises: storing the nano-sulfur at a second temperature for a second time length, and then drying the nano-sulfur in a freeze dryer for a third time length; wherein the second temperature ranges from -30 to -10 DEG C, the second time length ranges from 6 to 12 h, the third time length ranges from 12 to 24 h, and the particle size of the nano-sulfur ranges from 100 to 600 nm.

4. The method for preparing the cathode material according to claim 2, characterized in that, The method comprises: adding sodium thiosulfate to a flask with an ambient temperature of 0 DEG C, and the mass of the sodium thiosulfate ranges from 10 to 100 g; 5. The method for preparing the cathode material according to claim 1, characterized in that, adding hydrochloric acid to the flask with the sodium thiosulfate at a first rate and stirring to obtain a second mixture, the first rate ranges from 5 to 200 ml / min, the concentration of the hydrochloric acid ranges from 0.1 to 0.6 mol / L, and the volume of the hydrochloric acid ranges from 100 to 1000 ml; increasing the ambient temperature of the flask from 0 DEG C to a first temperature at a first temperature increasing rate, then stirring the second mixture in an argon stream for a first time length to obtain a third mixture, the first temperature increasing rate ranges from 0.5 to 2 DEG C / min, the first temperature ranges from 25 to 40 DEG C, and the first time length ranges from 2 to 6 h; vacuum filtering the third mixture and washing the vacuum filtered third mixture with an aqueous solution to obtain nano-sulfur. After the vacuum filtering and washing, the method further comprises: storing the nano-sulfur at a second temperature for a second time length, and then drying the nano-sulfur in a freeze dryer for a third time length; wherein the second temperature ranges from -30 to -10 DEG C, the second time length ranges from 6 to 12 h, the third time length ranges from 12 to 24 h, and the particle size of the nano-sulfur ranges from 100 to 600 nm. The method comprises: adding sodium thiosulfate to a flask with an ambient temperature of 0 DEG C, and the mass of the sodium thiosulfate ranges from 10 to 100 g; adding hydrochloric acid to the flask with the sodium thiosulfate at a first rate and stirring to obtain a second mixture, the first rate ranges from 5 to 200 ml / min, the concentration of the hydrochloric acid ranges from 0.1 to 0.6 mol / L, and the volume of the hydrochloric acid ranges from 100 to 1000 ml; increasing the ambient temperature of the flask from 0 DEG C to a first temperature at a first temperature increasing rate, then stirring the second mixture in an argon stream for a first time length to obtain a third mixture, the first temperature increasing rate ranges from 0.5 to 2 DEG C / min, the first temperature ranges from 25 to 40 DEG C, and the first time length ranges from 2 to 6 h; vacuum filtering the third mixture and washing the vacuum filtered third mixture with an aqueous solution to obtain nano-sulfur. The fifth mixture is placed in a hydrothermal reactor, carbon disulfide is added to the hydrothermal reactor at a second rate according to the mass of the fifth mixture, and the reaction temperature is increased to a third temperature at a second temperature increasing rate, and after a fifth time length, the reaction is naturally cooled to obtain a first mixture, wherein the second rate is 0.02-0.5 mL / g, the second temperature increasing rate is 5-10 ℃ / min, the third temperature is 150-250 ℃, and the fifth time length is 12-24 hours.

6. The method for preparing the cathode material according to claim 1, characterized in that, The first mixture is annealed under argon protection to obtain a sulfur positive electrode material, including: The first mixture is placed in a tube furnace and annealed in an argon gas stream at a fourth temperature for a sixth time length to obtain a sulfur positive electrode material, wherein the fourth temperature is 400-500 ℃, and the sixth time length is 1-3 hours.

7. The method for preparing the cathode material according to claim 1, characterized in that, After the first mixture is annealed under argon protection to obtain a sulfur positive electrode material, the method further includes: The sulfur positive electrode material, conductive carbon, and solid-state electrolyte are placed in a ball mill in a second mass ratio for a seventh time length to obtain an electrode powder, the second mass ratio is 1:(0.1-0.3):(0.05-0.1), and the seventh time length is 2-3 hours; The electrode powder is placed in a tabletting device for compaction, the pressure of the tabletting device is 150-400 MPa, and the compacted electrode powder is used to assemble a solid-state lithium-sulfur battery with the solid-state electrolyte and lithium metal.

8. The method for preparing the cathode material according to claim 7, characterized in that, The solid-state electrolyte is any one of polyvinylidene fluoride, polyvinylidene fluoride, polyethylene oxide, polyacrylic acid, and polyvinyl alcohol.

9. A battery, characterized by The battery includes a positive electrode material prepared by the positive electrode material preparation method of any one of claims 1-8.

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