Amorphous lithium vanadium chloride positive electrode material and preparation method and application thereof

Abstract

The invention discloses an amorphous lithium vanadium chloride positive electrode material and a preparation method and application thereof.The preparation method comprises the steps that S1, in an inactive atmosphere I, a mixture containing lithium chloride and vanadium chloride is subjected to melting synthesis in a vacuum state, crystalline lithium vanadium chloride with the chemical formula being Li < x > VCl < 3 + x > is obtained, and x is larger than 0 and smaller than or equal to 7; s2, in an inactive atmosphere II, mixing the crystalline lithium vanadium chloride obtained in the step (1) with conductive carbon black, and performing mechanical ball milling to obtain an amorphous lithium vanadium chloride positive electrode material; the preparation method is carried out under an anhydrous condition. The method provided by the invention is simple in process, the amorphous positive electrode material can be prepared through extremely low ball milling time, and the repeatability is high. And in a solid-state lithium metal battery positive electrode material, the material has excellent rate capability.

Description

Technical Field

[0001] The present application relates to an amorphous lithium vanadium chloride cathode material, a preparation method thereof, and an application thereof, belonging to the technical field of solid-state batteries. Background Art

[0002] The wide popularization of electric vehicles and the upgrading of wearable electronic products have put forward higher requirements for the performance of secondary batteries used, and there is an urgent need to develop secondary batteries with higher energy density. Lithium metal batteries matching lithium metal anodes have higher energy density, but the uneven deposition / dissolution of lithium anodes in liquid electrolytes will lead to the formation of lithium dendrites. On the one hand, the dendrite tips break off from the electrode and are wrapped by SEI to form dead lithium, resulting in irreversible capacity decay; on the other hand, the continuous growth of dendrites will pierce the separator, leading to battery short circuit. Solid-state lithium metal batteries have advantages such as safety and high energy density, and at the same time, the immobile and non-permeable characteristics of solid-state electrolytes can inhibit the dissolution of transition metal ions. The cathode material directly determines the capacity and cost of lithium batteries. At present, common cathode materials need to add 30wt% of supporting electrolyte due to their low ionic conductivity, which reduces their energy density and it is still difficult to improve their power density. Based on this, using advanced lithium battery cathode materials is expected to achieve 10-minute rapid charging for electric vehicles and truly solve the range anxiety problem.

[0003] In the past few decades of the rapid development of lithium batteries, researchers have discovered lithium battery cathode materials based on layered oxide structures (represented by lithium cobalt oxide LiCoO2), spinel structures (represented by lithium manganese oxide LiMn2O4), olivine structures (represented by lithium iron phosphate LiFePO4), etc. Among them, layered oxides are the most widely used cathode materials for lithium-ion batteries, and the most representative one is lithium cobalt oxide. Lithium cobalt oxide was proposed by Goodenough et al. in 1976 and then commercially applied. During the charging process, when the lithium deintercalation amount reaches 50%, the structure of lithium cobalt oxide begins to undergo an irreversible phase change from the hexagonal phase to the monoclinic phase, and the layered structure begins to collapse. Therefore, only half of the theoretical capacity of lithium cobalt oxide can be exerted, reducing the practical applicability of lithium cobalt oxide. As the most successful polyanion cathode material at present, the olivine structure framework of lithium iron phosphate determines its outstanding cycle stability and can resist overcharging and thermal degradation. During the intercalation / deintercalation process of lithium ions, it belongs to a non-phase change reaction. Therefore, lithium iron phosphate cathode materials have good cycle performance, but due to their low room-temperature ionic conductivity (about 10 -8 S / cm), it is necessary to add a supporting electrolyte or carry out modification treatment, reducing its energy density.

[0004] Currently, research shows that the lithiated state of transition metal halides has outstanding lithium ion conductivity (>10 -3(with a conductivity of S / cm) and good deformability, and has been widely used as a solid-state electrolyte in all-solid-state lithium batteries. However, the ion transport in the cathode material is relatively weak. At present, it is believed that amorphization can break the limitations of the original ion transport channels, provide a large number of defect concentrations, and provide a favorable channel for the diffusion of lithium ions, thus having higher rate performance. The amorphous halide cathode material has the following advantages:

[0005] (1) Compared with the complex production and modification processes of lithium iron phosphate cathode materials and NCM ternary cathode materials, the preparation process of amorphous halide cathode materials is simple. The electrode material can be prepared by the melting-mechanical ball milling method under normal temperature and pressure.

[0006] (2) Layered oxide cathode materials have a high theoretical specific capacity, but their cycle stability is poor at high voltages. It is difficult to fully utilize the theoretical specific capacity, and at the same time, the ionic conductivity is low. After adding a supporting electrolyte, the rate performance is still not ideal. Halide cathode materials have an ionic conductivity exceeding 10 -4 S / cm and can cycle stably without a supporting electrolyte.

[0007] (3) A large number of defects are introduced into the amorphous halide cathode material by the mechanical ball milling method, showing an amorphous phase. Due to complete / partial amorphization, the limitations of the original Li + transport channels are broken, and more defect concentrations provide a favorable channel for the diffusion of Li + , greatly improving its rate performance.

[0008] In summary, although the current layered oxide-type and olivine-type cathode materials have a high theoretical specific capacity, due to the limitations of their own physical and chemical properties, when applied in the all-solid-state system, they face complex problems such as slow ion transport, poor cycle stability, and poor rate performance. Therefore, the research on the cathode materials of all-solid-state lithium batteries still needs to develop new systems to solve the above challenges in order to obtain high-power density energy storage devices. Summary of the Invention

[0009] The purpose of this application is to provide a preparation method and application of an amorphous lithium vanadium chloride cathode material, which is used to solve at least the technical problems such as poor cycle stability, poor rate performance, low energy density, and complex material production process of traditional all-solid-state batteries.

[0010] In one aspect of this application, a preparation method of an amorphous lithium vanadium chloride cathode material is provided. The preparation method includes:

[0011] S1. Under an inert atmosphere I, a mixture containing lithium chloride and vanadium chloride is melted and synthesized under vacuum to obtain crystalline lithium vanadium chloride with the chemical formula Li x VCl 3+x , where 0 < x ≤ 7;

[0012] S2. Under an inert atmosphere II, mix the crystalline lithium vanadium chloride obtained in step (1) with conductive carbon black and perform mechanical ball milling to obtain an amorphous lithium vanadium chloride cathode material;

[0013] The preparation method is carried out under anhydrous conditions.

[0014] Optionally, in the mixture, the stoichiometric ratio of lithium chloride to vanadium chloride in chemical formula is 0 to 14:2;

[0015] Optionally, the stoichiometric ratio of lithium chloride to vanadium chloride in chemical formula is 1 to 7:2.

[0016] Optionally, the stoichiometric ratio of lithium chloride to vanadium chloride in chemical formula independently selects any value from 1:2, 1, 3:2, 2, 5:2, 3, 7:2, 9:2, 11:2, 13:2, 14:2 or the range value between any two of the above.

[0017] To obtain a product of Li x VCl 4+x , where 0 < x ≤ 7, regulate the lithium content by mechanical ball milling synthesis so that the stoichiometric ratio of the mixture of lithium chloride and vanadium chloride is 0 to 14:2.

[0018] Optionally, the ball milling beads for the mechanical ball milling synthesis include at least two diameter types.

[0019] Optionally, the ball milling beads for the mechanical ball milling include ball milling beads I with a diameter of 3 to 6 mm and ball milling beads II with a diameter of 8 to 15 mm;

[0020] The quantity ratio of the ball milling beads I and the ball milling beads II is 0 to 5:1. Optionally, the quantity ratio of the ball milling beads I and the ball milling beads II independently selects any value from 1:1, 2:1, 3:1, 4:1, 5:1 or the range value between any two of the above.

[0021] Optionally, the rotation speed of the mechanical ball milling is 300 to 1500 revolutions per minute;

[0022] The time of the mechanical ball milling is 2 to 108 hours.

[0023] Optionally, the rotation speed of the mechanical ball milling independently selects any value from 300 revolutions per minute, 552 revolutions per minute, 800 revolutions per minute, 1000 revolutions per minute, 1200 revolutions per minute, 1500 revolutions per minute or the range value between any two of the above.

[0024] Optionally, the time of the mechanical ball milling independently selects any value from 2 hours, 16 hours, 32 hours, 48 hours, 64 hours, 80 hours, 96 hours, 108 hours or the range value between any two of the above.

[0025] Optionally, the mechanical ball milling synthesis procedure includes forward rotation, intermittent, reverse rotation, intermittent, and cycles in this order.

[0026] Optionally, the melt synthesis sequentially includes a heating stage, a heat preservation stage, and a cooling stage;

[0027] The temperature of the melt synthesis is 400 - 800 °C, the time of the heating stage is 1 - 8 hours, the time of the heat preservation stage is 2 - 24 hours, and the time of the cooling stage is 1 - 8 hours;

[0028] The heating rate is 1 - 10 °C / min;

[0029] The cooling rate is 1 - 10 °C / min.

[0030] Optionally, the temperature of the melt synthesis is independently selected from any value of 400 °C, 500 °C, 650 °C, 700 °C, 800 °C or the range value between any two of the above.

[0031] Optionally, the time of the heating stage is independently selected from any value of 1 hour, 2 hours, 4 hours, 6 hours, 8 hours or the range value between any two of the above.

[0032] Optionally, the time of the heat preservation stage is independently selected from any value of 2 hours, 6 hours, 12 hours, 18 hours, 24 hours or the range value between any two of the above.

[0033] Optionally, the time of the cooling stage is independently selected from any value of 1 hour, 2 hours, 4 hours, 6 hours, 8 hours or the range value between any two of the above.

[0034] Optionally, the heating rate is independently selected from any value of 1 °C / min, 2 °C / min, 3.125 °C / min, 4 °C / min, 6 °C / min, 8 °C / min, 10 °C / min or the range value between any two of the above.

[0035] Optionally, the cooling rate is independently selected from any value of 1 °C / min, 2 °C / min, 3.125 °C / min, 4 °C / min, 6 °C / min, 8 °C / min, 10 °C / min or the range value between any two of the above.

[0036] Optionally, in step (2), before mixing, it further includes manually grinding crystalline vanadium lithium chloride;

[0037] The manual grinding time is 0 - 2 h.

[0038] Optionally, in step (2), the mass ratio of the crystalline vanadium lithium chloride to the conductive carbon black is 5 - 9:1.

[0039] Optionally, the mass ratio of the crystalline lithium vanadium chloride to the conductive carbon black is independently selected from any value of 5:1, 6:1, 7:1, 8:1, 9:1 or the range value between any two of the above.

[0040] Optionally, the inert atmosphere I and the inert atmosphere II are independently selected from at least one of argon, nitrogen, and helium.

[0041] In this application, the inert atmosphere is high-purity argon, and the purity of high-purity argon is ≥99.999%, and the contents of oxygen and water are less than 0.1 ppm.

[0042] Optionally, before synthesis, it also includes drying the quartz tube, the ball milling tank, and the ball milling beads in an oven at 25 to 400 °C for 0 to 10 hours.

[0043] As a specific implementation method, the preparation method includes:

[0044] The preparation method of the amorphous lithium vanadium chloride cathode includes: S1, placing anhydrous lithium chloride and anhydrous vanadium chloride in a quartz tube under an inert atmosphere, sealing and then performing melt synthesis to form lithium vanadium chloride with the chemical formula Li x VCl 3+x where 0 < x ≤ 7. S2, under an inert atmosphere, adding the lithium vanadium chloride obtained in S1 to conductive carbon black (Ketjenblack) and performing mechanical ball milling to obtain an amorphous lithium vanadium chloride cathode material, with the composition: Li x VCl 3+x :Ketjenblack = 90 wt%:10 wt%, where 0 < x ≤ 7.

[0045] In another aspect of this application, an amorphous lithium vanadium chloride cathode material is provided. The amorphous lithium vanadium chloride cathode material is obtained according to the above preparation method and includes amorphous lithium vanadium chloride and conductive carbon black;

[0046] The chemical formula of the amorphous lithium vanadium chloride is Li x VCl 3+x where 0 < x ≤ 7.

[0047] Optionally, in the amorphous lithium vanadium chloride cathode material, the mass ratio of the amorphous lithium vanadium chloride to the conductive carbon black is 5 to 9:1.

[0048] Optionally, the mass ratio of the amorphous lithium vanadium chloride to the conductive carbon black is independently selected from any value of 5:1, 6:1, 7:1, 8:1, 9:1 or the range value between any two of the above.

[0049] Another aspect of the present application provides the use of the amorphous lithium vanadium chloride cathode material obtained by the above preparation method in an all-solid-state lithium metal battery.

[0050] In the present application, for the range values of data, the endpoint values are all included, and only when 0 appears, the value of 0 is not taken.

[0051] The beneficial effects that the present application can produce include:

[0052] 1) The preparation method of amorphous lithium vanadium chloride provided by the present application has a simple process and is environmentally friendly. By using the melt-mechanical ball milling method for synthesis, a solid cathode material with a relatively high room temperature conductivity can be prepared without complex modification treatment.

[0053] 2) For the amorphous lithium vanadium chloride cathode material prepared by the present application, when assembling an all-solid-state lithium metal battery, it can stably cycle without a supporting electrolyte, saving costs and increasing the energy density of the battery.

[0054] 3) For the amorphous lithium vanadium chloride cathode material prepared by the present application, when used as the cathode material of a solid-state lithium battery and assembling an all-solid-state lithium metal battery, the cycle stability and power density of the battery are improved, and it has good application prospects.

[0055] 4) The method provided by the present application has a simple process, can prepare an amorphous cathode material through an extremely low ball milling time, and has high repeatability. It has excellent rate performance among the cathode materials of all-solid-state lithium metal batteries. Description of the Drawings

[0056] Figure 1 is the preparation method and flow chart of the amorphous lithium vanadium chloride cathode material in the embodiment of the present application;

[0057] Figure 2 is the X-ray diffraction pattern of Comparative Example 1 and Example 1 of the present application;

[0058] Figure 3 is the X-ray diffraction pattern of Example 1, 4, 5, and 6 of the present application;

[0059] Figure 4 is the X-ray diffraction pattern of Comparative Example 2, Example 1, 7, 8, and 9 of the present application;

[0060] Figure 5 is the X-ray diffraction pattern of Example 1, 10, and 11 of the present application;

[0061] Figure 6 is the cyclic voltammetry test chart of the all-solid-state lithium metal battery prepared in Example 3 of the present application;

[0062] Figure 7 is the rate performance test chart of the all-solid-state lithium metal batteries prepared in Comparative Example 1 and Example 3;

[0063] Figure 8 It is a test chart of the cycle stability performance of the all-solid-state lithium metal batteries prepared in Comparative Example 1 and Example 3. Detailed implementation manners

[0064] The present application will be described in detail below in conjunction with embodiments, but the present application is not limited to these embodiments.

[0065] Unless otherwise specified, the raw materials in the embodiments of the present application are all purchased through commercial channels.

[0066] Example 1

[0067] This example provides a preparation method of amorphous lithium vanadium chloride, and the process is referred to Figure 1 , including: S1, under the protection of an inert atmosphere at room temperature, anhydrous lithium chloride and anhydrous vanadium chloride are placed in a quartz tube according to the stoichiometric ratio. After being strictly sealed with a quartz tube sealer, melt synthesis is carried out in a muffle furnace to obtain lithium vanadium chloride with the chemical formula LiVCl4. S2, the obtained lithium vanadium chloride is ground with agate, and conductive carbon black is added according to the mass fraction ratio, and then mechanical ball milling is carried out to synthesize an amorphous lithium vanadium chloride cathode material with the composition of LiVCl4:Ketjenblack = 90wt%:10wt%.

[0068] Among them, in S1, the raw material lithium chloride (LiCl, anhydrous grade, 99.99%), vanadium chloride (VCl3, anhydrous grade, 97%)

[0069] In S1, the molar ratio of the raw materials LiCl:VCl3 = 1:1, and the corresponding usage amounts are LiCl (0.1911g) and VCl3 (0.7089g).

[0070] In S1, the heating and cooling rates of the muffle furnace are 3.125 degrees Celsius per minute. It is heated to 650 degrees Celsius and kept warm for 12 hours. This temperature is higher than the melting points of LiCl and VCl3, and effectively reduces the influence of the disproportionation reaction of VCl3. After the reaction, it is cooled to 25 degrees Celsius.

[0071] In S2, the manual grinding time is 15 minutes.

[0072] In S2, the mass ratio of the added raw materials is LiVCl4:conductive carbon black (Ketjenblack) = 9:1, and the specific usage amounts are LiVCl4 (0.27g) and Ketjenblack (0.03g).

[0073] The ball milling synthesis process in S2 is as follows: All the raw materials prepared in proportion are placed in a 100 ml zirconia ball milling jar. Subsequently, 10 ball milling beads with a diameter of 10 mm and 20 ball milling beads with a diameter of 6 mm are added to the ball milling jar. The ball milling jar is strictly sealed with a silica gel gasket in a glove box to ensure that the atmosphere in the ball milling jar is argon. Subsequently, the sealed ball milling jar is placed in the planetary disk of a planetary ball mill and fixed with a V-shaped clamp. Immediately afterwards, the working program of the ball mill is set to a mode of 20 minutes of forward rotation, a 5-minute interval, 20 minutes of reverse rotation, and a 5-minute interval. At the same time, the rotation speed is set to 552 revolutions per minute, and the number of repetitions is set to 10 times. After the ball mill program runs to completion, an amorphous lithium vanadium chloride cathode material can be prepared. The ball milling beads used for mechanical ball milling synthesis include at least two diameters. The large ball milling beads provide shear force and impact force to reduce the diameter of material particles and provide mechanical energy for the amorphous phase transformation. The small ball milling beads are used for grinding to fully mix lithium vanadium chloride and conductive carbon black.

[0074] In this embodiment, the inert atmosphere is high-purity argon, and the purity of high-purity argon is ≥99.99%. The content of oxygen and water is <0.1 ppm. High-purity argon has the function of maintaining an inert atmosphere in the glove box. When the content of water and oxygen is greater than 0.1 ppm, the product will absorb moisture and cause the material to deliquesce.

[0075] In this embodiment, the material of the ball milling beads is zirconia. The zirconia material is selected because it has the characteristics of high hardness, low wear rate, and long service life. It can greatly reduce the pollution of the raw materials by the tank body and ball milling beads during the ball milling process, effectively ensuring the quality of the product. At the same time, the zirconia material has a high density, and as a grinding medium with strong impact energy, it can greatly improve the grinding efficiency and effectively shorten the grinding time.

[0076] Before mechanical ball milling synthesis, it also includes drying the zirconia grinding jar and zirconia ball milling beads in an oven. The drying temperature is 60 degrees Celsius, and the drying time is 3 hours. Then, the prepared materials are put in and sealed.

[0077] Based on the amorphous lithium vanadium chloride prepared by melting-mechanical ball milling synthesis in this embodiment, the room temperature ionic conductivity can reach 10 -5 S / cm. After assembling the full battery and cycling, the rate performance is better than that of the VCl3 cathode material with 50 wt% supporting electrolyte added. The process is simple and has high repeatability.

[0078] Example 2

[0079] This embodiment provides a solid cathode material, and the solid cathode material is the amorphous lithium vanadium chloride cathode material obtained in Example 1.

[0080] The amorphous lithium vanadium chloride cathode material obtained in Example 1 is pressed by a tablet press to obtain a solid cathode sheet.

[0081] Example 3

[0082] This example provides a all-solid-state lithium metal battery. The all-solid-state lithium metal battery uses the amorphous vanadium lithium chloride cathode material obtained in Example 1. The specific steps include:

[0083] The instruments and equipment used to assemble the all-solid-state lithium metal battery with the amorphous vanadium lithium chloride cathode material obtained in Example 1 include a 10 mm solid-state pressure battery mold, a manual tablet press, a bliologic multi-channel electrochemical test system, and a BlueTEC battery test system. The assembly process of the solid-state lithium metal battery is carried out in a dry glove box filled with argon, where the content of water and oxygen is less than 0.1 ppm.

[0084] Weigh 50 mg of lithium zirconium chloride electrolyte and place it in a 10 mm pressure battery mold. After spreading it flat, use a manual tablet press to apply a pressure of 0.5 tons for 30 seconds. Then, take another 50 mg of Li6PS5Cl electrolyte and place it on the pressed lithium zirconium chloride electrolyte, and apply a pressure of 1 ton for 30 seconds. Subsequently, take 2.5 mg of the amorphous vanadium lithium chloride cathode material obtained in Example 1 and add it to the back of the pressed lithium zirconium chloride electrolyte. After spreading it evenly, apply a pressure of 4 tons for 30 seconds. Finally, place a lithium sheet and a copper foil on the upper layer of the pressed Li6PS5Cl in sequence, and finally apply a pressure of 1 ton. The battery assembly is completed.

[0085] Example 4

[0086] This example provides a preparation method of amorphous vanadium lithium chloride. The process refers to Example 1, only changing S1. The raw material molar ratio is changed to LiCl:VCl3 = 1:2, and the corresponding amounts are LiCl (0.1189 g) and VCl3 (0.8811 g). Other conditions are the same as those in Example 1.

[0087] Example 5

[0088] This example provides a preparation method of amorphous vanadium lithium chloride. The process refers to Example 1, only changing S1. The raw material molar ratio is changed to LiCl:VCl3 = 2:1, and the corresponding amounts are LiCl (0.3506 g) and VCl3 (0.6494 g). Other conditions are the same as those in Example 1.

[0089] Example 6

[0090] This example provides a preparation method of amorphous vanadium lithium chloride. The process refers to Example 1, only changing S1. The raw material molar ratio is changed to LiCl:VCl3 = 7:1, and the corresponding amounts are LiCl (0.6539 g) and VCl3 (0.3461 g). Other conditions are the same as those in Example 1.

[0091] Example 7

[0092] This embodiment provides a method for preparing amorphous lithium vanadium chloride. The process refers to Example 1, only changing the rotation speed in S2 to 300 revolutions per minute, and other conditions are the same as those in Example 1.

[0093] Example 8

[0094] This embodiment provides a method for preparing amorphous lithium vanadium chloride. The process refers to Example 1, only changing the rotation speed in S2 to 1000 revolutions per minute, and other conditions are the same as those in Example 1.

[0095] Example 9

[0096] This embodiment provides a method for preparing amorphous lithium vanadium chloride. The process refers to Example 1, only changing the rotation speed in S2 to 1500 revolutions per minute, and other conditions are the same as those in Example 1.

[0097] Example 10

[0098] This embodiment provides a method for preparing amorphous lithium vanadium chloride. The process refers to Example 1, only changing the mass ratio of the raw material to conductive carbon black in S2, LiVCl4: conductive carbon black (Ketjenblack) = 5:1, and the specific dosage is LiVCl4 (0.25 g), Ketjenblack (0.05 g). Other conditions are the same as those in Example 1.

[0099] Example 11

[0100] This embodiment provides a method for preparing amorphous lithium vanadium chloride. The process refers to Example 1, only changing the mass ratio of the raw material to conductive carbon black in S2, LiVCl4: conductive carbon black (Ketjenblack) = 7:1, and the specific dosage is LiVCl4 (0.2625 g), Ketjenblack (0.0375 g). Other conditions are the same as those in Example 1.

[0101] Comparative Example 1

[0102] Take 0.1911 g of lithium chloride (LiCl, anhydrous grade, 99.99%) and 0.7089 g of vanadium chloride (VCl3, anhydrous grade, 97%) and place them in a quartz tube. After sealing with a vacuum quartz tube sealer, melt and synthesize them using a muffle furnace to obtain lithium vanadium chloride with the chemical formula LiVCl4. Subsequently, take 0.27 g of the obtained lithium vanadium chloride and 0.03 g of conductive carbon black, place them in an agate mortar, and manually grind for 15 minutes to obtain a lithium vanadium chloride cathode material. Perform X-ray diffraction testing on the obtained lithium vanadium chloride cathode material.

[0103] Take 50 mg of lithium zirconium chloride electrolyte and place it in a 10 mm pressure cell mold. After spreading it flat, use a manual press to apply a pressure of 0.5 tons for 30 seconds. Then, take another 50 mg of Li6PS5Cl electrolyte and place it on top of the pressed lithium zirconium chloride electrolyte, and apply a pressure of 1 ton for 30 seconds. Subsequently, take 2.5 mg of lithium vanadium chloride cathode material and add it to the back of the pressed lithium zirconium chloride electrolyte. After spreading it evenly, apply a pressure of 4 tons for 30 seconds. Finally, place a lithium sheet and a copper foil on top of the pressed Li6PS5Cl in sequence, and finally apply a pressure of 1 ton. The battery assembly is completed. Use a Blue Power battery test system to perform rate performance testing. Take out the electrode sheet and cover it with a Kapton film to isolate water and oxygen. Then, use a Rigaku UltimaⅣ X-ray diffractometer to perform XRD testing.

[0104] Comparative Example 2

[0105] This comparative example provides a preparation method of amorphous lithium vanadium chloride. The process refers to Example 1, only changing the rotation speed in S2 to 100 revolutions per minute, and other conditions are the same as those in Example 1.

[0106] Test Example 1

[0107] Perform X-ray diffraction testing on the amorphous lithium vanadium chloride cathode materials obtained in Examples 1, 4, 5, and 6 and the lithium vanadium chloride cathode material obtained in Comparative Example 1 using a Rigaku UltimaⅣ X-ray diffractometer. The test results are as Figure 2 、 Figure 3 shown. The horizontal axis is the diffraction angle 2θ, and the vertical axis is the diffraction intensity. It can be obtained that the amorphous lithium vanadium chloride cathode materials provided in Examples 1, 4, 5, and 6 have the characteristics of good amorphous state, indicating that Li x VCl 3+x lithium vanadium chloride can exist in the amorphous phase form at a ratio of 0 < x ≤ 7, while Comparative Example 1 obviously has the characteristics of a crystalline structure.

[0108] Perform X-ray diffraction testing on the amorphous lithium vanadium chloride cathode materials obtained in Examples 1, 7, 8, and 9 and the lithium vanadium chloride cathode material obtained in Comparative Example 2 using a Rigaku UltimaⅣ X-ray diffractometer. The test results are as Figure 4 shown. The horizontal axis is the diffraction angle 2θ, and the vertical axis is the diffraction intensity. It can be obtained that the amorphous lithium vanadium chloride cathode materials provided in Examples 1, 7, 8, and 9 have the characteristics of good amorphous state, while Comparative Example 2 has the characteristics of a mixture of crystalline and amorphous states, indicating that at a ball milling rotation speed of 300 - 1500 revolutions per minute, Li x VCl 3+x can exist in the amorphous phase form. If the synthesis is carried out outside this rotation speed range, a mixed state of crystalline and amorphous Li x VCl 3+x material will be obtained.

[0109] For Examples 1, 10, and 11, the obtained amorphous lithium vanadium chloride cathode material was subjected to X-ray diffraction testing using a Rigaku Ultima IV X-ray diffractometer in Japan. The test results are as follows: Figure 5 As shown, the horizontal axis is the diffraction angle 2θ and the vertical axis is the diffraction intensity. It can be obtained that the amorphous lithium vanadium chloride cathode materials provided in Examples 1, 10, and 11 have the characteristics of good amorphous state, indicating that the conductive carbon black does not participate in the occurrence of the amorphization reaction, and the ratio of lithium vanadium chloride to conductive carbon black only affects the energy density of the cathode material.

[0110] The obtained amorphous lithium vanadium chloride all-solid-state battery of Example 3 was tested:

[0111] A biologic multi-channel electrochemical workstation was used to perform cyclic voltammetry testing on it. In this test, the scanning voltage was 2 - 3.5 V and the scanning rate was 0.1 mV / s. The test results are shown in Figure 6 .

[0112] Figure 6 It is the cyclic voltammetry test chart of the amorphous lithium vanadium chloride cathode material. Among them, the oxidation-reduction peaks at 2.8 and 2.9 V are very symmetrical and have extremely small differences, indicating that the repeatability of its electrochemical reaction is extremely high.

[0113] Figure 8 It is the cyclic performance chart of Example 3 and Comparative Example 1. It can be found that the amorphous lithium vanadium chloride cathode material has excellent cyclic performance. Under the same conditions, after 200 cycles, its capacity retention rate is 93%, indicating that the amorphous lithium vanadium chloride cathode creates a three-dimensional ion transport network by constructing an amorphous phase, introducing more reactive sites, and has excellent cyclic performance.

[0114] According to the test method of Comparative Example 1, the rate performance test of the amorphous lithium vanadium chloride all-solid-state battery obtained in Example 3 was carried out. Figure 7 It is the rate performance comparison chart of the amorphous lithium vanadium chloride all-solid-state battery provided in Example 3 and Comparative Example 1. It can be found that compared with the crystalline lithium vanadium chloride cathode material, the amorphous lithium vanadium chloride cathode material has a great improvement in rate performance. Under the condition of the same current density, it is increased from 3C to 15C (taking discharging to 0% SOC in 1 hour as 1C).

[0115] The above are only several embodiments of the present application, and do not impose any form of limitation on the present application. Although the present application is disclosed as above with preferred embodiments, it is not intended to limit the present application. Any person skilled in the art, without departing from the scope of the technical solution of the present application, making some changes or modifications using the disclosed technical content above is equivalent to equivalent embodiments and all belong to the scope of the technical solution.

Claims

1. A preparation method of an amorphous lithium vanadium chloride cathode material, characterized in that, The preparation method includes: S1. Under an inert atmosphere I, a mixture containing lithium chloride and vanadium chloride is subjected to fusion synthesis under vacuum to obtain crystalline lithium vanadium chloride with the chemical formula Li x VCl 3+x , where 0 < x ≤ 7; S2. Under an inert atmosphere II, mix the crystalline lithium vanadium chloride obtained in step (1) with conductive carbon black and mechanically ball-mill to obtain an amorphous lithium vanadium chloride cathode material; The preparation method is carried out under anhydrous conditions.

2. The preparation method according to claim 1, characterized in that, In the mixture, the stoichiometric ratio of lithium chloride to vanadium chloride in chemical formula is 0-14:2; Preferably, the stoichiometric ratio of lithium chloride to vanadium chloride in chemical formula is 1-7:

2.

3. The preparation method according to claim 1, characterized in that, The ball-milling beads for the mechanical ball-milling include ball-milling beads I with a diameter of 3-6 mm and ball-milling beads II with a diameter of 8-15 mm; The quantity ratio of the ball-milling beads I to the ball-milling beads II is 0-5:

1.

4. The preparation method according to claim 1, characterized in that, The rotation speed of the mechanical ball-milling is 300-1500 revolutions per minute; The time of the mechanical ball-milling is 2-108 hours.

5. The preparation method according to claim 1, characterized in that, The melt synthesis sequentially includes a heating stage, a heat preservation stage, and a cooling stage; The temperature of the melt synthesis is 400-800 °C, the time of the heating stage is 1-8 hours, the time of the heat preservation stage is 2-24 hours, and the time of the cooling stage is 1-8 hours; The heating rate is 1-10 °C / min; The cooling rate is 1-10 °C / min.

6. The preparation method according to claim 1, characterized in that, In step (2), before mixing, it further includes manually grinding the crystalline lithium vanadium chloride; The time of the manual grinding is 0-2 h; Preferably, in step (2), the mass ratio of the crystalline lithium vanadium chloride to the conductive carbon black is 5-9:

1.

7. The preparation method according to claim 1, characterized in that, The inert atmosphere I and the inert atmosphere II are independently selected from at least one of argon, nitrogen, and helium.

8. An amorphous lithium vanadium chloride cathode material, characterized in that, The amorphous lithium vanadium chloride cathode material is obtained according to the preparation method described in any one of claims 1-7, and includes amorphous lithium vanadium chloride and conductive carbon black; The chemical formula of the amorphous vanadium lithium chloride is Li x VCl 3+x , where 0 < x ≤ 7.

9. The amorphous lithium vanadium chloride cathode material according to claim 8, characterized in that, In the amorphous lithium vanadium chloride cathode material, the mass ratio of amorphous lithium vanadium chloride to conductive carbon black is 5-9:

1.

10. Application of the amorphous lithium vanadium chloride cathode material obtained by the preparation method described in any one of claims 1-7 in a all-solid-state lithium metal battery.

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