Sulfide solid electrolyte, preparation method thereof and all-solid-state battery
By doping halogen in sulfide solid electrolyte and adopting a gradient heating strategy, the high energy consumption and equipment loss caused by high temperature sintering are solved, densification and high ionic conductivity are achieved at low temperatures, and the stability and safety of the battery are improved.
Patent Information
- Application Number
- CN202510606258.4
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-05-12
- Publication Date
- 2025-07-04
AI Technical Summary
The large-scale preparation of existing sulfide solid electrolytes requires high-temperature sintering, which leads to significant energy consumption and aggravate equipment losses. The high-temperature environment can easily lead to excessive grain growth, destroy internal uniformity, and reduce ion transmission efficiency.
The raw materials with the chemical formula of Li5.5PS4.5Cl0.8X0.7 were used for grinding and doping of halogen (bromide or iodine), and the lattice defect level and lithium ion transport channel were controlled, combined with low-temperature sintering (400℃-440℃) to achieve densification, reducing energy consumption and promoting uniform grain growth.
Low-temperature densification of sulfide solid electrolytes has been achieved, ion conductivity has been increased by 15%-30%, interface impedance has been reduced, battery cycle stability has been improved, and production costs have been reduced.
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Figure CN120261684A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the technical field of new energy batteries, and in particular to a sulfide solid electrolyte and a preparation method thereof, and an all-solid-state battery. Background Art
[0002] With the transformation of the global energy structure, high energy density and high safety energy storage technology has become the core development direction of the new energy field. All-solid-state batteries, by virtue of their use of non-flammable solid electrolytes instead of traditional liquid electrolytes, effectively solve the safety hazards of liquid batteries such as leakage and thermal runaway. At the same time, they are compatible with high-voltage positive electrodes and lithium metal negative electrodes. The theoretical energy density can reach more than twice that of liquid batteries (>500Wh / kg), and is regarded as a key technology for the next generation of electric vehicles and energy storage systems. However, the industrialization process of all-solid-state batteries is still subject to the performance bottleneck of solid electrolyte materials and the difficulty of large-scale preparation.
[0003] Solid electrolytes are the core components of all-solid-state batteries to achieve high ionic conductivity and low interface impedance. Their performance directly determines the cycle life and energy efficiency of all-solid-state batteries. At present, solid electrolytes mainly include oxide solid electrolytes, polymer solid electrolytes and sulfide solid electrolytes. Oxide solid electrolytes (such as Li7La3Zr2O 12 ) has excellent chemical stability, but its ionic conductivity is low (usually <1mS / cm); polymer solid electrolytes (such as PEO-based systems) have good flexibility at room temperature, but their ionic conductivity decreases significantly with increasing temperature and needs to be heated to above 60°C before use; sulfide solid electrolytes (such as Li 10 GeP2S 12 , Li6PS5Cl) with its ultra-high ionic conductivity (up to 10 -2 S / cm level), wide electrochemical window (>4.5V) and low interfacial impedance with electrodes, it is recognized as the candidate solid electrolyte with the greatest potential for industrialization.
[0004] However, the large-scale preparation of sulfide solid electrolytes still faces key technical obstacles: its lattice densification needs to be achieved through a high-temperature sintering process, and the conventional method needs to be maintained above 500°C for several hours, resulting in significant energy consumption (single batch energy consumption>200kWh) and increased equipment loss. Specifically, sulfide solid electrolyte materials are sensitive to oxygen / water, and sintering must be carried out in a glove box and in an inert atmosphere. The high temperature environment will accelerate the aging of the glove box sealing materials (such as silicone and metal foil), causing leakage risks (annual leakage rate>5%) and increasing maintenance costs (annual maintenance costs for a single glove box>50,000 yuan). In addition, high-temperature sintering can easily lead to excessive grain growth, destroy the internal uniformity of the sulfide solid electrolyte, and reduce the efficiency of ion transmission.
[0005] Therefore, the prior art still needs to be improved and developed. Summary of the Invention
[0006] In view of the deficiencies of the above-mentioned prior art, the present invention provides a sulfide solid electrolyte, a preparation method thereof, and a all-solid-state battery, so as to solve the problem that the existing method for preparing sulfide solid electrolyte requires high-temperature sintering (above 500 °C), resulting in significant energy consumption (energy consumption per batch > 200 kWh) and aggravating equipment loss.
[0007] The technical solutions adopted by the present invention to solve the above technical problems are as follows:
[0008] In the first aspect of the present invention, a preparation method of a sulfide solid electrolyte is provided, and the preparation method includes the following steps:
[0009] Weigh the raw materials according to the molar ratio of Li 5.5 PS 4.5 Cl 0.8 X 0.7 chemical formula, and perform grinding treatment to obtain a mixed powder;
[0010] Heat the mixed powder to a first temperature at a first heating rate and keep it for a first time, then heat it to a second temperature at a second heating rate and keep it for a second time to obtain the sulfide solid electrolyte;
[0011] wherein, X is bromine or iodine, the first temperature is 200 °C, and the second temperature is 400 °C - 440 °C.
[0012] Preferably, the bromine source in the raw materials is lithium bromide, and the iodine source is lithium iodide.
[0013] Preferably, in the sulfide solid electrolyte, the doping ratio of bromine or iodine is 0.5 - 2.0 mol%.
[0014] Preferably, the first heating rate is 2 - 5 °C / min, and the second heating rate is 2 - 5 °C / min.
[0015] Preferably, the first time is 1 - 3 h, and the second time is 1 - 5 h.
[0016] In the second aspect of the present invention, a sulfide solid electrolyte is provided, and the sulfide solid electrolyte is prepared by using the above preparation method.
[0017] Preferably, the D50 particle size of the sulfide solid electrolyte is ≤ 500 nm.
[0018] Preferably, the hardness of the sulfide solid electrolyte is ≤ 3.5 GPa.
[0019] Preferably, the ionic conductivity of the sulfide solid electrolyte at room temperature is 8.5-10.5 mS / cm.
[0020] In a third aspect of the present invention, a all-solid-state battery is provided, and the all-solid-state battery includes the above-mentioned sulfide solid electrolyte.
[0021] Beneficial effects:
[0022] The present invention discloses a sulfide solid electrolyte, a preparation method thereof, and an all-solid-state battery. First, Br or I is doped into lithium phosphorus sulfur chlorine (LPSC, Li6PS5Cl) to regulate the defect energy level of the existing sulfide solid electrolyte lattice and the lithium ion transport channel. After Br or I ions are embedded in the lattice, by optimizing the P-S bond length (shortening ) and reducing the density of grain boundary vacancy defects, the uniform growth of grains is promoted, and the generation of impurity phases (such as Li3PS4) is inhibited. Experimental data show that the material obtained after doping Br or I can achieve complete densification (density > 99%) by sintering at 440 °C for 8 hours, which is 50-100 °C lower than the traditional process (500-600 °C). In addition, the present invention also adopts a gradient heating strategy (such as pre-burning at 200 °C for 2 hours and then heating to 440 °C), combined with the guiding effect of Br or I doping on crystal nucleus growth, so that the material after doping Br or I can quickly complete phase purification at low temperature, and the energy consumption is reduced by more than 40%. Description of the drawings
[0023] Figure 1 is a flow chart of the preparation method of the sulfide solid electrolyte provided by a preferred embodiment of the present invention;
[0024] Figure 2 is an XRD pattern of the sulfide solid electrolyte prepared in Examples 1-3 and Comparative Examples 1 and 2 of the present invention;
[0025] Figure 3 is a particle size test chart of the sulfide solid electrolyte prepared in Example 1 of the present invention;
[0026] Figure 4 is a particle size test chart of the sulfide solid electrolyte prepared in Example 2 of the present invention;
[0027] Figure 5 is a particle size test chart of the sulfide solid electrolyte prepared in Example 3 of the present invention;
[0028] Figure 6 is a particle size test chart of the sulfide solid electrolyte prepared in Comparative Example 1 of the present invention;
[0029] Figure 7 is a particle size test chart of the sulfide solid electrolyte prepared in Comparative Example 2 of the present invention. Detailed implementation mode
[0030] The present invention provides a sulfide solid electrolyte, a preparation method thereof, and a all-solid-state battery. To make the objectives, technical solutions, and effects of the present invention clearer and more definite, the present invention is further described in detail below. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.
[0031] An embodiment of the present invention provides a preparation method of a sulfide solid electrolyte. The preparation method includes the following steps:
[0032] Weigh raw materials according to the molar ratio of the chemical formula of Li 5.5 PS 4.5 Cl 0.8 X 0.7 and perform grinding treatment to obtain a mixed powder;
[0033] Heat the mixed powder to a first temperature at a first heating rate and keep it for a first time, and then heat it to a second temperature at a second heating rate and keep it for a second time to obtain the sulfide solid electrolyte;
[0034] wherein, X is bromine or iodine, the first temperature is 200°C, and the second temperature is 400°C - 440°C.
[0035] In the embodiment of the present invention, Br or I is first doped in lithium phosphorus sulfur chlorine (LPSC, Li6PS5Cl) to regulate the defect energy level of the existing sulfide solid electrolyte lattice and the lithium ion transport channel. After Br or I ions are embedded in the lattice, by optimizing the P-S bond length (shortening ), and reducing the density of grain boundary vacancy defects, promoting the uniform growth of grains, and inhibiting the generation of impurity phases (such as Li3PS4). Experimental data show that the material obtained after doping Br or I can achieve complete densification (density > 99%) after sintering at 440°C for 8 hours, which is 50 - 100°C lower than the traditional process (500 - 600°C). In addition, the present invention also adopts a gradient heating strategy (such as pre-burning at 200°C for 2 hours and then heating to 440°C), combined with the guiding effect of Br or I doping on the growth of crystal nuclei, so that the material doped with Br or I can quickly complete phase purification at low temperature, and the energy consumption is reduced by more than 40%.
[0036] The room-temperature ionic conductivity of the sulfide solid electrolyte doped with halogen reaches 8.2 - 10.5 mS / cm (Br doping) or 8.5 - 11.2 mS / cm (I doping) after sintering at 440 °C, which is 15% - 30% higher than that of the undoped one. At the same time, halogen doping can passivate the interface between the sulfide solid electrolyte and the lithium metal anode, reducing the risk of dendrite penetration. The interface impedance increase of the symmetric cell using the sulfide solid electrolyte of the embodiment of the present invention is <5% after cycling for 4600 hours, and the interface impedance remains stable at 10 Ω·cm after 500 charge-discharge cycles. 2 as follows.
[0037] In some embodiments, in the sulfide solid electrolyte, the doping ratio of bromine or iodine is 0.5 - 2.0 mol%.
[0038] Less than 0.5 mol% has no doping effect, and more than 2 mol% will affect the structure of the sulfide solid electrolyte itself, resulting in a significant decline in properties such as phase and ionic conductivity.
[0039] In some preferred embodiments, in the sulfide solid electrolyte, the doping ratio of bromine or iodine is 0.7 mol%.
[0040] In some embodiments, the first heating rate is 2 - 5 °C / min, and the second heating rate is 2 - 5 °C / min.
[0041] In some embodiments, the first time is 2 h, and the second time is 1 - 5 h.
[0042] The heating rate should not be too fast. Slow heating gives sufficient reaction time. Because of the two-stage heating, the overall heat preservation time does not need to be too long, which can save energy consumption and improve efficiency.
[0043] In some embodiments, before weighing the raw materials according to the molar ratio of the chemical formula Li 5.5 PS 4.5 Cl 0.8 X 0.7 and grinding them, the following steps are also included: placing the weighed mixture in a powder grinder for powder mixing. The rotation speed of the powder grinder is 1000 - 2000 r, and more preferably 1500 r.
[0044] In some embodiments, the powder mixing method of the powder grinder is intermittent mixing, with each mixing for 60 s and a total of 10 times of mixing. The powder is swept away during the intermediate interval.
[0045] In some embodiments, the grinding treatment is specifically as follows: The mixed material after powdering is placed in a 500 mL - 2 L zirconia jar, and an aromatic hydrocarbon organic solvent such as xylene, toluene, or ethylbenzene is added. The ball-to-material ratio is 1:(20 - 50), the ball milling speed is 200 - 300 r, and the time is 10 - 20 h.
[0046] In some preferred embodiments, the grinding treatment is specifically as follows: The mixed material after powdering is placed in a 500 mL zirconia jar, and xylene is added. The ball-to-material ratio is 1:30, the ball milling speed is 200 r, and the time is 15 h.
[0047] An embodiment of the present invention provides a sulfide solid electrolyte, and the sulfide solid electrolyte is prepared by using the above preparation method.
[0048] In some embodiments, the D50 particle size of the sulfide solid electrolyte is ≤ 500 nm.
[0049] In some embodiments, the hardness of the sulfide solid electrolyte is ≤ 3.5 GPa.
[0050] By using the sintering method of the embodiment of the present invention, the obtained sulfide solid electrolyte particles are small and soft, which is easy to collect materials, reduces the difficulty of subsequent processes, and improves engineering properties. Specifically, when sintering at low temperature, the ion migration rate is low, resulting in insufficient grain growth or weak bonding force between particles, which may cause incomplete fusion between particles and form a loose structure. For sulfide solid electrolytes, the advantages of softer particles are as follows: 1. Improving processability and interfacial contact cold pressing forming advantages: Softer particles are more easily pressed by cold pressing process to achieve close contact between the electrode and the electrolyte, reduce interfacial impedance, and improve battery efficiency. 2. Flexibility device adaptability: Softer particles can be adapted to flexible electrodes or special-shaped devices, reducing processing complexity. 3. Suppressing lithium dendrite growth: Softer particles may absorb the stress of dendrite penetration through plastic deformation, thereby suppressing dendrite formation and improving battery safety. 4. Reducing production costs: Simplifying process steps: Softer particles can be directly used for slurry coating or composite electrode preparation, reducing post-treatment steps. 5. Improving cycle stability: Softer particles may relieve volume changes during charge and discharge through elastic deformation, reduce the risk of cracking at the electrode / electrolyte interface, and extend battery life.
[0051] In some embodiments, the ionic conductivity of the sulfide solid electrolyte at room temperature is 8.5 - 10.5 mS / cm.
[0052] An embodiment of the present invention provides a all-solid-state battery, and the all-solid-state battery includes the above-mentioned sulfide solid electrolyte.
[0053] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments, and are only used to illustrate the present invention without any limitation to the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts belong to the scope of protection of the present invention.
[0054] Example 1
[0055] The preparation of a sulfide solid electrolyte includes the following steps: Weigh 5.69 g of LiCl, 15.43 g of Li2S, 18.66 g of P2S5, and 10.21 g of LiBr respectively and put them into a pulverizer. Mix them evenly at 1500 r for 60 s, 10 times, and then add them to a 500 mL zirconia jar with a ball-to-material ratio of 1:30. Then add xylene to cover the balls. Then, carry out sufficient ball milling at 200 r in a ball mill for 15 h. The milled mixture is heated to 200 °C at a heating rate of 3 °C / min and held for 2 h, and then continues to be heated to 400 °C at a heating rate of 3 °C / min and held for 5 h to obtain the sulfide solid electrolyte.
[0056] Example 2
[0057] The preparation method of this example is basically the same as that of Example 1, except that: the milled mixture is heated to 200 °C at a heating rate of 3 °C / min and held for 2 h, and then continues to be heated to 420 °C at a heating rate of 3 °C / min.
[0058] Example 3
[0059] The preparation method of this example is basically the same as that of Example 1, except that: the milled mixture is heated to 200 °C at a heating rate of 3 °C / min and held for 2 h, and then continues to be heated to 440 °C at a heating rate of 3 °C / min.
[0060] Comparative Example 1
[0061] The preparation method of this comparative example is basically the same as that of Example 1, except that: the milled mixture is heated to 200 °C at a heating rate of 3 °C / min and held for 2 h, and then continues to be heated to 460 °C at a heating rate of 3 °C / min.
[0062] Comparative Example 2
[0063] The preparation method of this comparative example is basically the same as that of Example 1, except that: the milled mixture is heated to 200 °C at a heating rate of 3 °C / min and held for 2 h, and then continues to be heated to 480 °C at a heating rate of 3 °C / min.
[0064] XRD measurements and particle size tests were carried out on the sulfide solid electrolytes prepared in the above Examples 1-3 and Comparative Examples 1 and 2, and the results are as Figure 2-7 shown;
[0065] Ionic conductivity tests were carried out on the sulfide solid electrolytes prepared in the above Examples 1-3 and Comparative Examples 1 and 2, and the results are shown in Table 1 below:
[0066] Table 1
[0067] Sample Ionic conductivity (mS / cm) Particle size (D50): um Example 1 (400 °C) 3.800 7.642 Example 2 (420 °C) 4.366 7.249 Example 3 (440 °C) 8.450 8.902 Comparative Example 1 (460 °C) 10.869 10.975 Comparative Example 2 (480 °C) 11.432 10.988
[0068] From the above test results, it can be seen that by using the preparation method of the present invention, it can be seen that as the temperature rises, the particle size of the sulfide solid electrolyte as a whole shifts towards a larger particle size, and at the same time, the ionic conductivity also increases. Among them, at 400 °C, the D50 particle size is only 7.642 μm, but there is still an ionic conductivity of 3.8 mS / cm. If considering the pure phase and selecting 440 °C, the D50 particle size is only 8.902 μm, and an ionic conductivity of 8.45 mS / cm can be maintained.
[0069] 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, improvements or transformations can be made according to the above description, and all such improvements and transformations should fall within the protection scope of the appended claims of the present invention.
Claims
1. A preparation method of a sulfide solid electrolyte, characterized in that, The preparation method includes the following steps: According to Li 5.5 PS 4.5 Cl 0.8 X 0.7 Weigh the raw materials according to the molar ratio of the chemical formula, and conduct grinding treatment to obtain a mixed powder; The mixed powder is heated to a first temperature at a first heating rate and held for a first time, and then heated to a second temperature at a second heating rate and held for a second time to obtain the sulfide solid electrolyte; Wherein, X is bromine or iodine, the first temperature is 200 °C, and the second temperature is 400 °C - 440 °C.
2. The preparation method of the sulfide solid electrolyte according to claim 1, characterized in that, The bromine source in the raw materials is lithium bromide, and the iodine source is lithium iodide.
3. The preparation method of the sulfide solid electrolyte according to claim 1, wherein In the sulfide solid electrolyte, the doping ratio of bromine or iodine is 0.5 - 2.0 mol%.
4. The preparation method of the sulfide solid electrolyte according to claim 1, wherein The first heating rate is 2 - 5 °C / min, and the second heating rate is 2 - 5 °C / min.
5. The preparation method of the sulfide solid electrolyte according to claim 1, wherein The first time is 1 - 3 h, and the second time is 1 - 5 h.
6. A sulfide solid electrolyte, characterized in that, The sulfide solid electrolyte is prepared by the preparation method described in any one of claims 1 - 5.
7. The sulfide solid electrolyte according to claim 6, wherein The D50 particle size of the sulfide solid electrolyte is ≤500 nm.
8. The sulfide solid electrolyte according to claim 6, wherein The hardness of the sulfide solid electrolyte is ≤3.5 GPa.
9. The sulfide solid electrolyte according to claim 6, wherein The ionic conductivity of the sulfide solid electrolyte at room temperature is 8.5 - 10.5 mS / cm.
10. A all-solid-state battery, characterized in that, The all-solid-state battery includes the sulfide solid electrolyte described in any one of claims 6 - 9.