Method for preparing anhydrous lithium iodide powder
The preparation of anhydrous lithium iodide by reacting lithium nitride and iodine under an inert atmosphere has solved the problems of complex preparation, high cost and serious pollution in the prior art, and achieved efficient and low-cost preparation of anhydrous lithium iodide, which improved the battery performance.
Patent Information
- Application Number
- CN202510684878.X
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-05-26
- Publication Date
- 2025-08-19
AI Technical Summary
The existing preparation methods for anhydrous lithium iodide are complex, expensive, difficult to purify and severe pollution, making it difficult to achieve large-scale production.
Lithium nitride and iodine are heated or ball milled under an inert atmosphere to generate anhydrous lithium iodide, simplifying the preparation process and avoiding solid-liquid separation and waste liquid generation.
It realizes high-purity, low-cost, green and environmentally friendly preparation of anhydrous lithium iodide, is suitable for industrial production, and improves the electrochemical performance of lithium-sulfur batteries and lithium-ion batteries.
Smart Images
Figure CN120504331A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the technical field of lithium iodide material synthesis, and in particular to a method for preparing anhydrous lithium iodide powder. Background Art
[0002] Lithium iodide, an inorganic compound with the chemical formula LiI, exhibits a cubic crystal system and a sodium chloride-type structure. It is susceptible to deliquesce and deactivation in air. Lithium iodide is commonly used in lithium-sulfur batteries, lithium-ion batteries, organic synthesis, pharmaceutical preparation, and dehydrogenation catalysis. In the battery field, lithium iodide is widely used as an electrolyte additive to improve battery performance and cycle stability. In organic synthesis, lithium iodide can be used as a catalyst for addition reactions of olefins and reduction reactions of aromatic compounds.
[0003] Due to the unique physical and chemical properties of lithium iodide, there are relatively few methods for preparing lithium iodide, which mainly include the following three methods: the first method is to react lithium salt and hydroiodic acid in a solution to obtain lithium iodide trihydrate, and then obtain anhydrous lithium iodide through a multi-step dehydration process; the second method is to place ammonium iodide and metallic lithium into liquid ammonia to react to prepare lithium iodide with crystalline water, and then dry and dehydrate it in an atmosphere filled with hydrogen iodide to obtain anhydrous lithium iodide; the third method is to add iodine and iron powder to lithium hydroxide and stir thoroughly, and then prepare lithium iodide containing crystalline water through separation and concentration, and finally obtain anhydrous lithium iodide through a dehydration process.
[0004] All three methods require the reaction to proceed in solution, followed by solid-liquid separation and dehydration to obtain anhydrous lithium iodide. This results in complex synthesis processes, high costs, difficult purification, and severe pollution, making it unsuitable for large-scale production. Therefore, developing a novel, efficient, low-cost, and environmentally friendly method for synthesizing anhydrous lithium iodide is of great significance. Summary of the Invention
[0005] The present invention aims to solve the problems of the current anhydrous lithium iodide preparation method, such as complexity, high price, difficulty in purification, and serious pollution, and provides a new, efficient, low-cost and green preparation method of anhydrous lithium iodide that meets the requirements of industrial production.
[0006] The technical solution adopted in the present invention is:
[0007] A method for preparing anhydrous lithium iodide powder, wherein lithium nitride and iodine react under energy conditions to generate anhydrous lithium iodide, specifically comprising the following steps:
[0008] (1) Under inert atmosphere, lithium nitride and iodine are mixed uniformly in a molar ratio of 1:0.1 to 10, and then the mixed powder is transferred to a reactor and sealed;
[0009] (2) operating the reactor under specific conditions for a specific time;
[0010] (3) After the reaction is completed, the solid product in the reactor is taken out under the protection of an inert atmosphere to obtain anhydrous lithium iodide.
[0011] As a preferred technical solution of the present invention, in the preparation method:
[0012] The uniform mixing method described in step (1) includes mechanical stirring or manual grinding.
[0013] The specific reaction time under the specific conditions described in step (2) includes heating the reaction at 50-200° C. for 0.1-120 h, or ball milling at a rotation speed of 10-800 rpm for 1-50 h.
[0014] The inert gas described in steps (1) and (3) is a mixture of one or more of nitrogen, argon and helium.
[0015] Compared with the prior art, the present invention has the following beneficial effects:
[0016] (1) The raw materials used in the present invention are lithium nitride and iodine, and the types of raw materials required for the reaction are few, the reaction control is simple and the product purity is high. The product purity is not affected by external factors such as the operation sequence, which greatly simplifies the preparation process.
[0017] (2) This reaction is a typical solid-solid reaction. No waste liquid is generated during the preparation process, and there is no complicated solid-liquid separation process.
[0018] (3) The preparation process is simple, easy to control, green and environmentally friendly, low-cost, and easy to achieve industrial production.
[0019] (4) The anhydrous lithium iodide prepared by the present invention can be used in lithium-sulfur batteries, lithium-ion batteries, organic synthesis, pharmaceutical preparation, and dehydrogenation catalysis. Electrochemical test results show that adding a trace amount of anhydrous lithium iodide to the electrolyte can effectively increase the discharge capacity of the lithium sulfide positive electrode and reduce the initial activation voltage barrier of the lithium sulfide positive electrode.
[0020] (5) The anhydrous lithium iodide microspheres prepared by the present invention have a relatively regular morphology, high dispersibility and high product purity. BRIEF DESCRIPTION OF THE DRAWINGS
[0021] Figure 1 This is the X-ray diffraction pattern of the anhydrous lithium iodide microspheres prepared in Example 1.
[0022] Figure 2 This is a scanning electron microscope image of the anhydrous lithium iodide microspheres prepared in Example 1.
[0023] Figure 3This is the X-ray diffraction pattern of the anhydrous lithium iodide powder prepared in Example 2.
[0024] Figure 4 This is a scanning electron microscope image of the anhydrous lithium iodide powder prepared in Example 2.
[0025] Figure 5 This is a diagram showing the rate performance of anhydrous lithium iodide microspheres prepared in Example 1 as an electrolyte additive in a lithium sulfide positive electrode.
[0026] Figure 6 This is a diagram showing the cycling performance of the anhydrous lithium iodide microspheres prepared in Example 1 as an electrolyte additive in a lithium sulfide positive electrode.
[0027] Figure 7 The voltage barrier diagram of the first activation of the anhydrous lithium iodide microspheres prepared in Example 1 as an electrolyte additive in a lithium sulfide positive electrode. DETAILED DESCRIPTION
[0028] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts shall fall within the scope of protection of the present invention.
[0029] Example 1
[0030] Under an argon atmosphere, lithium nitride and iodine were added to a mortar at a molar ratio of 1:1.5 and ground by hand. The mixed powder was then transferred to a sealed reactor. The reactor was then transferred to a heating furnace and incubated at 80°C for 36 hours. After the reaction was complete and cooled, the product was removed to obtain anhydrous lithium iodide microspheres.
[0031] Figure 1 This is the X-ray diffraction pattern of the product prepared in Example 1, Figure 2 This is a scanning electron microscope image of the product prepared in Example 1. Figure 1 It can be seen that the position of the product diffraction peak is completely consistent with the PDF#-74-1974 card of anhydrous lithium iodide, indicating that the present invention successfully prepared anhydrous lithium iodide. Figure 2 It can be seen that the prepared anhydrous lithium iodide particles are spherical, with a size distribution of 20 to 60 μm, a relatively regular morphology and high dispersibility.
[0032] Example 2
[0033] Under a nitrogen atmosphere, lithium nitride and iodine were added to a blender at a molar ratio of 1:1.5 and stirred. The resulting powder was then transferred to a reactor, where grinding balls were added and milled at 350 rpm for 3 hours. After the reaction was complete, the product was removed to obtain anhydrous lithium iodide powder.
[0034] Figure 3 This is the X-ray diffraction pattern of the product prepared in Example 2, Figure 4 The scanning electron microscope image of the product prepared in Example 2 is shown in FIG. Figure 3 It can be seen that the position of the product diffraction peak is completely consistent with the PDF#-74-1974 card of anhydrous lithium iodide, indicating that the present invention successfully prepared anhydrous lithium iodide. Figure 4 It can be seen that the prepared anhydrous lithium iodide particles are irregular in shape, with a size distribution of 5 to 20 μm and high dispersibility.
[0035] Example 3
[0036] Under a helium atmosphere, lithium nitride and iodine were added to a mortar at a molar ratio of 1:2 and ground by hand. The mixed powder was then transferred to a sealed reactor. The reactor was then transferred to a heating furnace and kept at 150°C for 10 hours. After the reaction was completed and cooled, the product was removed to obtain anhydrous lithium iodide microspheres.
[0037] Example 4
[0038] Under an argon / nitrogen atmosphere, lithium nitride and iodine were added to a blender in a molar ratio of 1:3 and stirred. The resulting powder was then transferred to a reactor. Milling balls were then added to the reactor and milled at 500 rpm for 10 hours. After the reaction was complete, the product was removed to obtain anhydrous lithium iodide powder.
[0039] Example 5
[0040] Under an argon atmosphere, lithium nitride and iodine were added to a mortar at a molar ratio of 1:3 and ground by hand. The mixed powder was then transferred to a sealed reactor. The reactor was then transferred to a heating furnace and kept at 200°C for 5 hours. After the reaction was completed and cooled, the product was removed to obtain anhydrous lithium iodide microspheres.
[0041] Electrochemical performance test of anhydrous lithium iodide microspheres as electrolyte additive in lithium sulfide positive electrode:
[0042] Preparation of a lithium-sulfur battery electrolyte containing lithium iodide: The lithium-sulfur battery electrolyte used was composed of 1 wt.% lithium nitrate and 1M lithium bis(trifluoromethylsulfonyl)imide dissolved in equal volumes of 1,3-dioxolane and ethylene glycol dimethyl ether. Under an argon atmosphere, the anhydrous lithium iodide microspheres prepared in Example 1 were added to the lithium-sulfur battery electrolyte at a concentration of 0.6 wt%. The solution was then heated at 80°C for 12 hours to completely dissolve the lithium iodide in the lithium-sulfur battery electrolyte, thereby preparing a lithium-sulfur battery electrolyte containing lithium iodide.
[0043] Preparation of positive electrode: A carbon nanotube / lithium sulfide composite material is prepared by mixing carbon nanotubes and lithium sulfide in a mass ratio of 1:3, further mixed with polyvinylidene fluoride binder and conductive carbon black in a mass ratio of 8:1:1, added to a nitrogen-methylpyrrolidone solution and stirred to a uniform slurry, then the slurry is coated on an aluminum sheet and dried at 80°C for 12 hours to obtain a carbon nanotube / lithium sulfide positive electrode.
[0044] Lithium-sulfur battery assembly: CR2025 button cell batteries were assembled in an argon glove box, using carbon nanotube / lithium sulfide as the positive electrode, a lithium sheet as the negative electrode, and a microporous polypropylene membrane as the separator. The electrolytes used were either lithium-sulfur battery electrolytes with or without lithium iodide.
[0045] Figure 5 The rate performance diagram of the anhydrous lithium iodide microspheres prepared in Example 1 as an electrolyte additive in a lithium sulfide positive electrode. -1 At the current density, the discharge capacities of the batteries with lithium iodide electrolyte were 555, 461, 408, 363, and 303 mAh g -1 , which is much higher than that of batteries without lithium iodide electrolyte. This result shows that the synthesized anhydrous lithium iodide microspheres can effectively improve the rate performance and reaction kinetics activity of lithium sulfide positive electrodes when used as electrolyte additives.
[0046] Figure 6 The cycle performance of the battery with anhydrous lithium iodide microspheres prepared in Example 1 as an electrolyte additive in a lithium sulfide positive electrode. -1 At the current density, the initial discharge capacity is 798 mAh g -1 After 120 cycles, the discharge capacity remains at 436 mAh g -1 , which is better than the 633mAh g of the battery without adding lithium iodide electrolyte. -1 and 343mAh g -1 The results show that the synthesized anhydrous lithium iodide microspheres can effectively improve the cycle performance of lithium sulfide cathode when used as electrolyte additives.
[0047] Figure 7 This figure shows the initial activation voltage barrier of the anhydrous lithium iodide microspheres prepared in Example 1 as an electrolyte additive in a lithium sulfide cathode. As can be seen from the figure, the activation voltage barrier of Li2S decreases from 3.0V to 2.9V after the introduction of lithium iodide into the electrolyte. This result demonstrates that the synthesized anhydrous lithium iodide microspheres, when used as an electrolyte additive, can effectively improve the reaction kinetics of lithium sulfide cathodes.
Claims
1. A method for preparing anhydrous lithium iodide powder, characterized in that: Lithium nitride and iodine are reacted under energy conditions to generate anhydrous lithium iodide, which specifically includes the following steps: (1) Under inert atmosphere, lithium nitride and iodine are mixed uniformly in a molar ratio of 1:0.1 to 10, and then the mixed powder is transferred to a reactor and sealed; (2) operating the reactor under specific conditions for a specific time; (3) After the reaction is completed, the solid product in the reactor is taken out under the protection of an inert atmosphere to obtain anhydrous lithium iodide.
2. The method according to claim 1, wherein The inert gas is a mixture of one or more gases selected from nitrogen, argon and helium.
3. The method according to claim 1, wherein The uniform mixing method includes mechanical stirring or manual grinding.
4. The method according to claim 1, wherein The specific reaction time under the specific conditions includes heating the reaction at 50-200° C. for 0.1-120 h.
5. The method according to claim 1, wherein The specific reaction time under the specific conditions includes ball milling at a rotation speed of 10 to 800 rpm for 1 to 50 hours.
6. Use of anhydrous lithium iodide prepared by the method according to any one of claims 1 to 5 as an additive for lithium-sulfur battery electrolyte.