Composite negative electrode material, preparation method and application of composite negative electrode material in all-solid-state lithium battery
The composite negative electrode material with LixMoS2, sulfide electrolyte, and conductive carbon black addresses the limitations of existing sulfide-based electrode materials by enhancing conductivity and stability, improving the performance of solid-state lithium batteries.
Patent Information
- Application Number
- CN202510297098.X
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-03-13
- Publication Date
- 2025-07-08
AI Technical Summary
Current negative electrode materials for solid-state lithium batteries based on sulfide electrolytes suffer from low initial coulomb efficiency, poor electronic conductivity, and significant volume expansion, limiting their performance.
A composite negative electrode material comprising LixMoS2, sulfide electrolyte, and conductive carbon black in a specific ratio, prepared by mixing and grinding under inert conditions, which introduces additional lithium ions to compensate for losses and enhance electronic and ionic conductivity.
The composite material maintains high electronic and ionic conductivity, reduces volume expansion, and improves the electrochemical performance and stability of solid-state lithium batteries, with enhanced rate capability and long cycle life.
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Abstract
Description
Technical Field
[0001] The present invention relates to the technical field of solid-state batteries, and particularly to a composite anode material, a preparation method thereof, and an application thereof in all-solid-state lithium batteries. Background Art
[0002] At present, the lithium-ion battery industry has developed rapidly and is widely used in fields such as new energy vehicles, mobile phones, and energy storage devices. However, the development of the traditional lithium-ion battery industry is restricted by low theoretical energy density and serious safety problems in practical applications. Therefore, all-solid-state lithium batteries (ASSLBs) based on solid electrolytes have attracted attention due to their potential high energy density, ultra-high safety, and stability. Among all-solid-state lithium batteries, ASSLBs based on sulfide electrolytes stand out due to their excellent ionic conductivity, enhanced mechanical ductility, and excellent electrode / electrolyte interface compatibility, being superior to ASSLBs based on oxide, polymer, and halide electrolytes. These advantages make ASSLBs based on sulfide electrolytes the most promising candidates for advanced ASSLB applications. Therefore, developing an anode material that matches the sulfide electrolyte is crucial for improving the performance of ASSLBs. In current research and applications, graphite, silicon-based anode materials, transition metal oxides, and lithium metal are commonly used anode materials. However, the specific capacity of the graphite anode is relatively low (372 mAh g -1 ), the silicon-based anode has significant volume expansion and poor conductivity problems, the initial Coulomb efficiency of transition metal oxides is low, and the lithium metal anode is prone to reducing the electrolyte and forming lithium dendrites. Therefore, it is necessary to develop a suitable anode material to promote the development of ASSLBs based on sulfide electrolytes.
[0003] Based on this, the existing technology needs to be improved. Summary of the Invention
[0004] In view of the above deficiencies of the existing technology, the present invention provides a composite anode material, a preparation method thereof, and an application thereof in all-solid-state lithium batteries, aiming to solve problems such as low initial Coulomb efficiency and poor electronic conductivity of existing anode materials.
[0005] The technical solution of the present invention is as follows:
[0006] In the first aspect of the present invention, a composite anode material is provided, including Li x MoS2, sulfide electrolyte, and conductive carbon black with a mass ratio of 70 - 80:20 - 30:1, where x is the number of Li atoms.
[0007] Optionally, the x is between 0.5 and 1.
[0008] Optionally, the sulfide electrolyte is Li7P2S8I, Li10 GeP2S 12 or Li7P3S 11 。
[0009] Optionally, Li x The mass ratio of MoS2, sulfide electrolyte and conductive carbon black is 70:30:1 or 80:20:1.
[0010] In the second aspect of the present invention, a method for preparing a composite negative electrode material is provided. Li x with a mass ratio of 70-80:20-30:1 of MoS2, sulfide electrolyte and conductive carbon black are ground or ball-milled and mixed in an inert gas atmosphere to obtain the composite negative electrode material.
[0011] Optionally, the Li x MoS2 is prepared by the following method:
[0012] In an inert gas atmosphere, molybdenum disulfide is placed in a container;
[0013] Add n-butyllithium solution until molybdenum disulfide is submerged, and seal the opening of the container (wrap it with a sealing film to avoid contact with air and moisture);
[0014] Place the sealed container in an ultrasonic cleaning instrument, perform ultrasonic treatment, washing, and drying to obtain the Li x MoS2.
[0015] Optionally, the molar ratio of molybdenum disulfide to n-butyllithium in the n-butyllithium solution is 7-8:1.
[0016] Optionally, the ultrasonic time is 5-6 h.
[0017] The inert gas atmosphere is preferably argon. The lithium intercalated negative electrode material Li x MoS2 is prepared by a chemical prelithiation method.
[0018] Optionally, the washing is performed with hexane for more than once, and the supernatant is removed by centrifugation after each washing. The centrifugation speed is 8000-10000 revolutions per minute, and the centrifugation time is 1-2 min.
[0019] Optionally, the drying atmosphere is an inert gas, the drying temperature is 70-80 °C, and the time is 18-24 h.
[0020] In the third aspect of the present invention, an application of a composite negative electrode material in a all-solid-state lithium battery is provided.
[0021] In the fourth aspect of the present invention, a all-solid-state lithium battery is provided, which includes a composite negative electrode material, a sulfide electrolyte and lithium or a lithium indium alloy containing lithium.
[0022] During preparation, the sulfide electrolyte is pressed into a sulfide electrolyte sheet, the composite anode material is pressed on one side of the sulfide electrolyte sheet, and then lithium or a lithium-indium alloy containing lithium is pressed on the other side of the sulfide electrolyte sheet to obtain an all-solid-state lithium battery.
[0023] Advantages of the present invention:
[0024] (1) The Li x MoS2 of the composite anode material of the present invention has high electronic conductivity, ionic conductivity and discharge specific capacity. When it is compounded with the sulfide electrolyte and conductive carbon black, the obtained composite anode material retains the characteristics of Li x MoS2, and has a low volume expansion rate. When it is matched with the sulfide electrolyte, it has high stability. Therefore, the all-solid-state lithium battery prepared by using the composite anode material of the present invention has excellent electrochemical performance and stable performance.
[0025] (2) The preparation method of the composite anode material of the present invention is simple, easy to industrialize, environmentally friendly and low in cost. Description of the drawings
[0026] Figure 1 XRD test curve comparison diagram of Li x MoS2 of Example 1 and MoS2 of Comparative Example 1.
[0027] Figure 2 Raman spectrum test curve comparison diagram of Li x MoS2 of Example 1 and MoS2 of Comparative Example 1.
[0028] Figure 3 SEM microscopic image comparison diagram of Li x MoS2 of Example 1 and MoS2 of Comparative Example 1.
[0029] Figure 4 Electronic conductivity curve comparison diagram of Li x MoS2 of Example 1 and MoS2 of Comparative Example 1.
[0030] Figure 5 Ionic conductivity curve comparison diagram of the composite materials of Example 1 and Comparative Example 1.
[0031] Figure 6 Rate performance comparison diagram of the all-solid-state lithium batteries of Example 1 and Comparative Example 1.
[0032] Figure 7 Long cycle performance comparison diagram of the all-solid-state lithium batteries of Example 1 and Comparative Example 1. Detailed implementation manners
[0033] To make the objectives, technical solutions, and advantages of the present invention clearer, the following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings and embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts fall within the protection scope of the present invention. Without conflict, the following embodiments and the features in the embodiments can be combined with each other.
[0034] All-solid-state lithium-ion batteries (ASSLBs) based on sulfide electrolytes stand out due to their excellent ionic conductivity, enhanced mechanical ductility, and excellent electrode / electrolyte interface compatibility. Currently, the anode material molybdenum disulfide (MoS₂) has a graphite-like layered structure and weak van der Waals forces between adjacent layers, allowing lithium ions to easily intercalate into the MoS₂ layers, making it one of the most popular electrode materials. In addition, the layered structure of MoS₂ can provide a theoretical capacity of up to 670 mAh g⁻¹ through a 4-electron transfer reaction during discharge, which is 1.8 times that of the commonly used graphite material of 372 mAh g⁻¹. However, due to the low initial Coulomb efficiency, poor electronic conductivity of MoS₂, and high volume expansion rate when used alone, it is not compatible with sulfide electrolytes, thus limiting its application in all-solid-state lithium batteries. -1 of -1 However, due to the low initial Coulomb efficiency, poor electronic conductivity of MoS₂, and high volume expansion rate when used alone, it is not compatible with sulfide electrolytes, thus limiting its application in all-solid-state lithium batteries.
[0035] An embodiment of the present invention provides a composite anode material, including LiₓMoS₂, a sulfide electrolyte, and conductive carbon black with a mass ratio of 70-80:20-30:1, where x is the number of lithium atoms. x An embodiment of the present invention provides a composite anode material, including LiₓMoS₂, a sulfide electrolyte, and conductive carbon black with a mass ratio of 70-80:20-30:1, where x is the number of lithium atoms.
[0036] LiₓMoS₂ of the present invention x As the active material of the composite anode material, it is obtained by embedding lithium ions in the MoS₂ layers. When used, it can introduce additional active lithium ions into the all-solid-state lithium battery to compensate for lithium loss, thereby extending the battery life. Moreover, LiₓMoS₂ does not directly change the structure of MoS₂, only expanding the layer spacing of the anode material and promoting the diffusion of lithium ions, thereby improving the electronic conductivity, ionic conductivity, and discharge specific capacity of the material. LiₓMoS₂ x When combined with a sulfide electrolyte and conductive carbon black to form a composite anode material, it not only maintains the original high electronic conductivity, ionic conductivity, and discharge specific capacity characteristics of LiₓMoS₂, but also has a low volume expansion rate and good compatibility with the sulfide electrolyte. After being made into an all-solid-state lithium battery, it can also improve the rate performance and long-cycle stability of the battery, enabling it to be well applied in all-solid-state lithium batteries. x When combined with a sulfide electrolyte and conductive carbon black to form a composite anode material, it not only maintains the original high electronic conductivity, ionic conductivity, and discharge specific capacity characteristics of LiₓMoS₂, but also has a low volume expansion rate and good compatibility with the sulfide electrolyte. After being made into an all-solid-state lithium battery, it can also improve the rate performance and long-cycle stability of the battery, enabling it to be well applied in all-solid-state lithium batteries. x When combined with a sulfide electrolyte and conductive carbon black to form a composite anode material, it not only maintains the original high electronic conductivity, ionic conductivity, and discharge specific capacity characteristics of LiₓMoS₂, but also has a low volume expansion rate and good compatibility with the sulfide electrolyte. After being made into an all-solid-state lithium battery, it can also improve the rate performance and long-cycle stability of the battery, enabling it to be well applied in all-solid-state lithium batteries.
[0037] Li x When the proportion of MoS2 is too high, the battery releases more specific capacity, but lacks sufficient protection from other materials, making the composite anode material prone to swelling and fragmentation, etc., and the cycling performance deteriorates; on the contrary, when x the proportion of MoS2 is too low, the composite anode material has sufficient protection from other materials, the cycling stability is enhanced, and the conductivity is enhanced, but due to the x decrease in the proportion of this active substance MoS2, the specific capacity released by the battery will decrease. Selecting the above range can fully exert the performance of all-solid-state lithium batteries.
[0038] In some embodiments, x is 0.5 - 1, and can be 0.5, 0.6, 0.7, 0.8, 0.9, 1.
[0039] In some embodiments, the sulfide electrolyte is Li7P2S8I (LPSI), Li 10 GeP2S 12 (LGPS) or Li7P3S 11 (LPS), preferably Li 10 GeP2S 12 (LGPS).
[0040] In some embodiments, the mass ratio of Li x MoS2, sulfide electrolyte and conductive carbon black is 70:30:1 or 80:20:1, preferably 70:30:1.
[0041] In one embodiment, the conductive carbon black selected is conductive carbon black of model Super P.
[0042] The embodiment of the present invention also provides a preparation method of a composite anode material, including the following steps: Mixing Li x MoS2, sulfide electrolyte and conductive carbon black with a mass ratio of 70 - 80:20 - 30:1 under an inert gas atmosphere by grinding or ball milling to obtain the composite anode material.
[0043] When the total mass of Li x MoS2, sulfide electrolyte and conductive carbon black is 2 g, the grinding time is 15 min. It is also possible to use a ball mill (thinky) to perform ball milling for 2 minutes at a rotational speed of 400 rpm to also obtain the composite anode material of the present invention.
[0044] In one embodiment, the Li x MoS2 is prepared by the following method:
[0045] Under an inert atmosphere, place molybdenum disulfide (1 g) in a container (50 mL centrifuge tube);
[0046] Under an inert atmosphere, add n-butyllithium solution until the molybdenum disulfide is submerged, and seal the opening of the container (wrap it with sealing film to avoid contact with air and moisture);
[0047] Place the sealed container in an ultrasonic cleaning instrument, perform ultrasonic treatment, washing, and drying to obtain the Li x MoS2.
[0048] In some embodiments, the molar ratio of molybdenum disulfide to n-butyllithium in the n-butyllithium solution is 7-8:1.
[0049] If there is too little n-butyllithium, the lithium ions cannot be fully embedded, which may cause the structure in the area where lithium ions are not embedded to change and collapse, resulting in a decrease in the electronic and ionic conductivities of the anode material. At the same time, incomplete embedding leads to insufficient expansion of the material layer spacing, affecting the subsequent insertion and extraction of lithium ions. Too much n-butyllithium is also not needed because when the layer spacing of molybdenum disulfide is filled with lithium ions, no more lithium ions can be embedded, and excessive n-butyllithium will cause waste.
[0050] In one embodiment, the molar concentration of n-butyllithium in the n-butyllithium solution is 1.6 M.
[0051] In some embodiments, the ultrasonic time is 5-6 h. A time of 5-6 hours can ensure a sufficient reaction. If the time is too short, lithium ions cannot be embedded; if the time is too long, air is likely to be mixed in, resulting in a decrease in performance.
[0052] In some embodiments, the inert gas atmosphere is preferably argon.
[0053] In some embodiments, the washing is performed with hexane for more than once. After each washing, the supernatant is removed by centrifugation at a centrifugation speed of 8000-10000 revolutions per minute for 1-2 min.
[0054] In some embodiments, the drying atmosphere is an inert gas, the drying temperature is 70-80 °C, and the time is 18-24 h. Drying can be carried out in a heating chamber.
[0055] The Li x MoS2 obtained in this example has an electronic conductivity greater than 5 mS cm -1 , and an ionic conductivity greater than 2.5 mS cm -1 .
[0056] The embodiments of the present invention also provide an application of the composite anode material in all-solid-state lithium batteries.
[0057] An embodiment of the present invention also provides an all-solid-state lithium battery, which includes the composite negative electrode material, a sulfide electrolyte, and lithium or a lithium-indium alloy containing lithium.
[0058] During preparation, the sulfide electrolyte is pressed into a sulfide electrolyte sheet, the composite negative electrode material is pressed on one side of the sulfide electrolyte sheet, and then lithium or a lithium-indium alloy containing lithium is bonded to the other side of the sulfide electrolyte sheet to obtain an all-solid-state lithium battery.
[0059] Among them, the sulfide electrolyte sheet can be obtained by pressing powdery sulfide electrolytes such as LPSI, LGPS, or LPS (such as LGPS). For example, the powdery sulfide electrolyte can be added to a tablet pressing mold and kept under pressure for 30 s - 2 min at a pressure of 120 - 240 MPa to prepare the sulfide electrolyte sheet. The pressing pressure can be 120 MPa, 180 MPa, or 240 MPa, etc., and the pressure holding time can be 30 s, 60 s, 1 min, or 2 min, etc.
[0060] Then, the composite negative electrode material powder is evenly sprinkled on the surface of one side of the sulfide electrolyte sheet. The sulfide electrolyte sheet with the composite negative electrode material powder sprinkled thereon is placed in a tablet pressing mold and kept under pressure for 2 - 4 min at a pressure of 120 - 240 MPa. For example, the pressing pressure can be 120 MPa, 180 MPa, or 240 MPa, etc., and the pressure holding time can be 2 min, 2 min 30 s, 3 min, 3 min 30 s, or 4 min, etc.
[0061] Lithium or a lithium-indium alloy (such as a lithium-indium alloy) and the other side of the sulfide electrolyte sheet are pressed through a tablet pressing mold to make them bond.
[0062] The following is further illustrated by specific examples.
[0063] Example 1
[0064] 1. Preparation of Li x MoS2:
[0065] S1: Under an inert atmosphere (argon), 1 g of molybdenum disulfide powder is placed in a 50 mL centrifuge tube;
[0066] S2: While maintaining the inert atmosphere, n-butyllithium solution (molar concentration of 1.6 M) is added to the centrifuge tube to submerge the molybdenum disulfide until the 30 mL mark. The centrifuge tube is sealed with a sealing film to avoid contact with air and moisture. The molar ratio of the molybdenum disulfide to n-butyllithium in the n-butyllithium solution is 7.5:1;
[0067] S3: The sealed centrifuge tube is placed in an ultrasonic cleaning instrument for ultrasonic treatment, washing, and drying to obtain the Li x MoS2.
[0068] The ultrasonic time was 5 h. The washing was carried out three times with hexane. After each washing, the supernatant was removed by centrifugation at a rotational speed of 10,000 revolutions per minute for 2 min. The drying was carried out by placing the washed centrifuge tube in a heating chamber. The drying atmosphere was an inert gas (argon), the drying temperature was 70 °C, and the time was 24 h.
[0069] 2. Preparation of the composite anode material:
[0070] Under an inert atmosphere, the obtained Li x MoS2, sulfide electrolyte (LPSC), and conductive carbon black (Super P) were mixed in a mortar at a mass ratio of 70:30:1. The total mass was 2 g, and the grinding time was 15 min to obtain the composite anode material.
[0071] 3. Preparation of the all-solid-state lithium battery
[0072] The sulfide electrolyte was pressed into a sulfide electrolyte sheet. The composite anode material was pressed on one side of the solid electrolyte sheet, and then the lithium-indium alloy sheet was pressed on the other side of the solid electrolyte sheet to obtain the all-solid-state lithium battery.
[0073] Specifically: 200 mg of the sulfide electrolyte was placed in a tablet press mold and pressed at a pressure of 240 MPa for 1 min to obtain the sulfide electrolyte sheet; 9 mg of the above composite anode material was coated on one side of the sulfide electrolyte sheet and pressed at a pressure of 240 MPa for 1 min. Finally, the lithium-indium alloy was pressed on the other side of the sulfide electrolyte sheet to obtain the all-solid-state lithium battery of Example 1.
[0074] Comparative Example 1
[0075] 1. Preparation of the MoS2 composite anode material:
[0076] Under an argon atmosphere, MoS2, sulfide electrolyte (LPSC), and conductive carbon black (Super P) were mixed in a mortar at a mass ratio of 70:30:1. The total mass was 2 g, and the grinding time was 15 min to obtain the composite anode material.
[0077] 2. Preparation of the all-solid-state lithium battery
[0078] 200 mg of the sulfide electrolyte was placed in a tablet press mold and pressed at a pressure of 240 MPa for 1 min to obtain the sulfide electrolyte sheet; 9 mg of the MoS2 composite anode material obtained in Comparative Example 1 was coated on one side of the sulfide electrolyte sheet and pressed at a pressure of 240 MPa for 1 min. Finally, the lithium-indium alloy was pressed on the other side of the sulfide electrolyte sheet to obtain the all-solid-state lithium battery of Comparative Example 1.
[0079] Performance characterization:
[0080] X-ray Diffractometer (XRD) Test:
[0081] Figure 1 XRD test curve comparison diagram of Li x MoS2 of Example 1 and MoS2 of Comparative Example 1. The XRD pattern of Li x MoS2 shifted 0.32° towards lower angles at 2θ = 14.32°. This shift corresponds to the (001) peak of Li x MoS2, indicating that lithium ions have successfully inserted into the MoS2 lattice, expanding the lattice spacing, and further indicating that Li x MoS2 of the present invention was successfully prepared.
[0082] Raman Spectroscopy Test:
[0083] Figure 2 Raman spectroscopy test curve comparison diagram of Li x MoS2 of Example 1 and MoS2 of Comparative Example 1. A new Raman active mode was introduced at 150 cm -1 corresponding to the characteristic peak of Li x MoS2, while the E -1 and A -1 characteristic peaks at 379 cm 2g and 405 cm 1g disappeared. These characteristic peaks belong to MoS2, indicating that Li x MoS2 of Example 1 was successfully prepared.
[0084] Morphology Test (SEM):
[0085] Figure 3 SEM microscopic image comparison diagram of Li x MoS2 of Example 1 and MoS2 of Comparative Example 1. Both Li x MoS2 of Example 1 and MoS2 of Comparative Example 1 showed a layered stacking structure. The layered stacking structure provides insertion sites and diffusion channels for lithium ions, facilitating the transport of lithium ions and enhancing the battery capacity and energy density. In the image of Li x MoS2 of Example 1, many small particle substances can be seen, which are residues of n-butyllithium solution, further indicating that Li x MoS2 of the present invention was formed by the reaction of n-butyllithium with molybdenum disulfide.
[0086] All-solid-state Lithium Battery Performance Test:
[0087] Conductivity Test:
[0088] Respectively take 50 mg of Li xThe MoS2 of Example 1 and the MoS2 of Comparative Example 1 were placed in a tablet press mold and pressed into a negative electrode material sheet under a pressure of 120 MPa for 1 minute. Stainless steel sheets were placed on both sides of the two negative electrode material sheets and assembled into a battery. The electronic conductivity was tested by the DC polarization method. Under a constant voltage of 0.05 V, the current change was observed for 24 hours. The Li of Example 1 x The test results of the electronic conductivity of the MoS2 of Example 1 and the MoS2 of Comparative Example 1 are as Figure 4 shown.
[0089] 200 mg of sulfide solid electrolyte (LPSC) was taken and placed in a tablet press mold, and two sulfide electrolyte sheets were obtained by pressing under a pressure of 240 MPa for 1 minute. 9 mg of the Li of Example 1 x MoS2 and the MoS2 of Comparative Example 1 were pressed on one side of the sulfide electrolyte sheet and pressed for 1 minute under a pressure of 240 MPa. The lithium-indium alloy was pressed on the other side of the sulfide electrolyte sheet, and then EIS test was carried out to obtain the ionic conductivity. The test temperature was 25 °C. The test results of the ionic conductivity of the composite materials of Example 1 and Comparative Example 1 are as Figure 5 shown.
[0090] From Figure 4 and Figure 5 it can be seen that the electronic conductivity and ionic conductivity of the Li x MoS2 of Example 1 are significantly improved compared with those of Comparative Example 1, which are 5 times and 2.5 times that of the MoS2 of Comparative Example 1 respectively, indicating that pre-lithiation of MoS2 can effectively improve the properties such as electronic conductivity and ionic conductivity.
[0091] Rate performance test:
[0092] Figure 6 Fig. (25 °C) is a comparison chart of the rate performance of the all-solid-state lithium batteries of Example 1 and Comparative Example 1. The all-solid-state lithium batteries of Example 1 and Comparative Example 1 were tested using a Neware electrochemical workstation. The test rates were 0.1C, 0.2C, 0.3C, 0.5C and 1C (1C = 670 mAh g -1 ), and the voltage range was -0.6 - 3V. When cycling the fifth lap at different rates, the discharge specific capacities of the all-solid-state lithium battery of Example 1 were 723, 690, 657, 588 and 476 mAh g -1 respectively, and after recovering to 0.1C, it still discharged a specific capacity of 665 mAh g -1 ; the discharge specific capacities of the all-solid-state lithium battery of Comparative Example 1 were 770, 724, 633, 529 and 229 mAh g -1 respectively, and the discharge specific capacity after recovering to 0.1C was 636 mAh g -1。The rate performance of the all-solid-state lithium battery in Example 1 is superior to that in Comparative Example 1, maintaining a good discharge specific capacity at high rates, indicating an improvement in the kinetics of the battery in Example 1. Combining Figure 1 , it shows that Li x MoS2 in the composite anode material of the present invention expands the layer spacing due to the intercalation of lithium ions, which is beneficial to the diffusion of lithium ions, and thus improves the kinetic performance of the all-solid-state lithium battery.
[0093] Long cycle performance test:
[0094] Figure 7 Figure (25 °C) for comparing the long cycle performance of the all-solid-state lithium batteries in Example 1 and Comparative Example 1. Cycled 100 times at 0.2C, the initial Coulombic efficiency of the all-solid-state lithium battery in Example 1 is 155%, and the discharge specific capacity after 100 cycles is 677 mAh g -1 , and the capacity retention rate is 93.4%; the initial Coulombic efficiency of the all-solid-state lithium battery in Comparative Example 1 is 96.3%, and the discharge specific capacity after 100 cycles is 527 mAh g -1 , and the capacity retention rate is only 72.2%. It shows that the composite anode material of Example 1 is beneficial to maintaining the long cycle performance due to the additional lithium source.
[0095] In summary, the present invention provides a composite anode material, a preparation method and its application in all-solid-state lithium batteries. The present invention obtains Li x MoS2 by intercalating lithium ions into the MoS layer. The Li x MoS2 of the present invention can introduce additional active lithium ions into the all-solid-state lithium battery to compensate for the loss of lithium, thereby extending the service life of the battery. Moreover, Li x MoS2 does not directly change the structure of MoS, only expands the layer spacing of the anode material, promotes the diffusion of lithium ions, and thus can improve the electronic conductivity, ionic conductivity and discharge specific capacity of the material. Combined with sulfide electrolyte and conductive carbon black to form a composite anode material, maintaining the original high electronic conductivity, ionic conductivity and discharge specific capacity characteristics of Li x MoS2, and having a low volume expansion rate and good matching with sulfide electrolyte. After being made into an all-solid-state lithium battery, it can also improve the rate performance and long cycle stability of the battery, enabling it to be well applied in all-solid-state lithium batteries.
[0096] It should be understood that the application of the present invention is not limited to the above examples. For those of ordinary skill in the art, it can be improved or transformed according to the above description. All such improvements and transformations should fall within the protection scope of the appended claims of the present invention.
Claims
1. A composite negative electrode material, characterized in that, Comprising Li with a mass ratio of 70 - 80:20 - 30:1 x MoS2, a sulfide electrolyte, and conductive carbon black, where x is the number of Li atoms.
2. The composite negative electrode material according to claim 1, characterized in that, Wherein x is 0.5 - 1.
3. The composite negative electrode material according to claim 1, wherein The sulfide electrolyte is Li7P2S8I, Li 10 GeP2S 12 or Li7P3S 11 .
4. The composite anode material according to claim 1, characterized in that Li x The mass ratio of MoS2, sulfide electrolyte, and conductive carbon black is 70:30:1 or 80:20:
1.
5. A method for preparing a composite negative electrode material, characterized in that, comprising the following steps: mixing Li, x x MoS2, a sulfide electrolyte, and conductive carbon black in a mass ratio of 70-80:20-30:1 by grinding or ball milling in an inert gas atmosphere to obtain the composite negative electrode material.
6. The preparation method of a composite anode material according to claim 5, characterized in that, The Li x MoS2 is prepared by the following method: Under an inert gas atmosphere, place molybdenum disulfide in a container; Add n-butyllithium solution until molybdenum disulfide is submerged, and seal the opening of the container; Place the sealed container in an ultrasonic cleaning instrument, perform ultrasonic treatment, washing, and drying to obtain the Li x MoS2.
7. The preparation method of a composite anode material according to claim 6, characterized in that, The molar ratio of the molybdenum disulfide to n-butyllithium in the n-butyllithium solution is 7 - 8:
1.
8. The preparation method of a composite anode material according to claim 6, characterized in that, The ultrasonic time is 5 - 6 h.
9. Application of a composite anode material in an all-solid-state lithium battery.
10. A all-solid-state lithium battery, characterized in that: It includes the composite anode material described in claim 1, a sulfide electrolyte, and lithium or a lithium-indium alloy containing lithium.