Modified solid-state electrolyte material, preparation method thereof, and all-solid-state lithium ion battery
By coating the surface of sulfide solid electrolyte particles with LiI-C2H5Li complex, the problems of poor compatibility between solid electrolyte and electrode and air stability are solved, achieving high-efficiency lithium-ion battery performance improvement and cost control.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- SVOLT ENERGY TECH (WUXI) CO LTD
- Filing Date
- 2022-12-27
- Publication Date
- 2026-05-29
AI Technical Summary
Existing solid electrolytes have poor compatibility with electrodes, constructing artificial SEI layers is costly and has limited performance, sulfide solid electrolytes have poor air stability, and lithium dendrite growth poses safety hazards.
The sulfide solid electrolyte particles are modified with a LiI and C2H5Li complex coating layer to form a lithium iodide and ethyl lithium complex coating layer, which improves the compatibility and stability with the electrode.
It effectively reduces side reactions, improves energy density and cycle performance, inhibits lithium dendrite growth, maintains high ionic conductivity, reduces production costs, improves air stability, and is suitable for large-scale production.
Smart Images
Figure CN115882054B_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of solid electrolyte technology for all-solid-state lithium-ion batteries, specifically to modified solid electrolyte materials and their preparation methods, and all-solid-state lithium-ion batteries. Background Technology
[0002] To improve the capacity density and safety of lithium-ion batteries, all-solid-state lithium-ion batteries have become the ultimate goal. The key to the development and application of all-solid-state batteries is the solid-state electrolyte. Solid-state electrolytes are broadly classified into inorganic solid-state electrolytes and polymer solid-state electrolytes. Inorganic electrolytes are further divided into oxide and sulfide types. Among them, sulfide solid-state electrolytes exhibit the best performance in terms of ionic conductivity, comparable to that of liquid electrolytes, and have therefore attracted widespread attention.
[0003] However, solid electrolytes such as sulfide solid electrolytes face many technical barriers: First, there is the compatibility problem between solid electrolytes and the solid-solid interface of electrodes. During cycling, solid electrolytes are prone to side reactions with lithium metal at the solid-solid interface, which can lead to a decrease in battery capacity and a rapid decline in battery life. In addition, uneven deposition of lithium ions on the negative electrode surface can form lithium dendrites. As the charge and discharge cycle continues, lithium dendrites gradually extend and pierce the separator, causing a short circuit in the battery and posing a serious safety hazard. Second, sulfide solid electrolytes are prone to decomposition in the air to produce H2S gas. They have poor air stability and require stringent production and storage conditions.
[0004] Currently, to improve the compatibility between solid electrolytes and electrodes, artificial SEI layers are typically constructed on either the electrolyte or electrode side. This measure effectively reduces side reactions, lowers interfacial impedance, or slows down lithium dendrite growth. However, these measures require highly advanced equipment or very expensive raw materials. Furthermore, the yield rate of artificial SEI construction at the interface is insufficient, leading to a significant increase in production costs. Moreover, this measure can only improve the performance of solid-state batteries to a limited extent in one aspect, and may even be based on sacrificing other performance aspects. For example, while this measure improves compatibility, it significantly reduces ionic conductivity. Summary of the Invention
[0005] Therefore, the technical problem to be solved by the present invention is to overcome the problems of poor compatibility between existing solid electrolytes and electrodes and high manufacturing cost of constructing artificial SEI layers, thereby providing a modified solid electrolyte with better compatibility and lower cost, as well as a method for its preparation and an all-solid-state lithium-ion battery.
[0006] The technical solution of this invention:
[0007] A modified solid electrolyte material includes solid electrolyte particles and a lithium iodide and lithium ethyl complex coating layer covering the surface of the solid electrolyte particles.
[0008] The solid electrolyte particles are sulfide solid electrolyte particles.
[0009] The solid electrolyte particles are made of lithium phosphorus sulfide (Li3PS4) and lithium germanium phosphorus sulfide (Li 10 GeP2S 12 Lithium phosphide sulfide bromide (Li6PS5Br), lithium phosphide sulfide iodide (Li6PS5I), or lithium phosphide sulfide chlorine (Li6PS5Cl).
[0010] A method for preparing a modified solid electrolyte material includes the following steps: coating LiI onto the surface of solid electrolyte particles to obtain LiI-coated solid electrolyte particles; mixing the LiI-coated solid electrolyte particles with C2H5Li, and then heating to form a lithium iodide and ethyl lithium complex coating layer on the surface of the solid electrolyte particles, thereby obtaining the modified solid electrolyte material.
[0011] The LiI-coated solid electrolyte particles are mixed with C2H5Li by grinding, preferably by ball milling, with a ball milling speed of 50-500 rpm and a ball milling time of 0.5-120 min.
[0012] And / or, the heating temperature is 80-600℃, and the holding time is 0.5-5h.
[0013] The solid electrolyte is a sulfide solid electrolyte, and the preparation of the sulfide solid electrolyte includes the following steps: mixing raw materials in the formula ratio to obtain a mixture; grinding the mixture and vacuum annealing to obtain sulfide solid electrolyte particles;
[0014] The raw materials are lithium sulfide (Li2S) and phosphorus pentasulfide (P2S5), preferably with a molar ratio of Li2S to P2S5 of 3:1-7:1; or lithium sulfide, phosphorus pentasulfide and germanium sulfide (GeS2), with a molar ratio of Li2S, P2S5 and GeS2 of 5:1:1; or lithium sulfide, phosphorus pentasulfide and lithium halide (LiX), wherein the lithium halide is any one of lithium chloride, lithium bromide and lithium iodide, preferably with a molar ratio of Li2S, P2S5 and LiX of 5:(0.8-1.5):(0.8-3).
[0015] The mixture is mixed by grinding, preferably by ball milling, with a ball milling speed of 200-700 rpm and a ball milling time of 2-24 hours;
[0016] And / or, the annealing temperature is 400-600℃, and the annealing time is 2h-8h;
[0017] And / or, after annealing, the process also includes grinding and sieving the annealed material, with a sieve mesh size of 100-400 mesh.
[0018] The preparation method of the LiI-coated solid electrolyte particles is as follows:
[0019] LiI coating is performed using a gas-phase method; preferably, the step of performing LiI coating using a gas-phase method involves contacting LiI vapor with the solid electrolyte particles under an inert atmosphere to obtain LiI-coated solid electrolyte particles; the flow rate of the LiI vapor is 0.2 m³ / s. 3 / h-3m 3 / h, the LiI vapor introduction time is from before the solid electrolyte particles are introduced until after the solid electrolyte particles are removed, preferably, the introduction time is from 3 minutes before the solid electrolyte particle powder is introduced until 3 minutes after the solid electrolyte particle powder is removed; the introduction rate of the solid electrolyte particles is 5-30 g / s, the introduction time is 30-120 s; the reaction temperature is between 60-100℃;
[0020] Alternatively, LiI coating can be performed using a liquid-phase method. Preferably, the step of LiI coating using a liquid-phase method is as follows: dissolving LiI in a solvent to obtain a precursor solution, adding the solid electrolyte particles to the precursor solution and stirring for 10-15 min; vacuum drying the solvent to obtain LiI-coated solid electrolyte particles. Preferably, the solvent is an organic solvent, and the organic solvent is any one or more of tetrahydrofuran, toluene, and xylene; the concentration of LiI in the solvent is 0.01 g / ml-0.5 g / ml, and the concentration of the solid electrolyte particles in the solvent is 0.04-0.05 g / ml.
[0021] The thickness of the LiI coating layer is 20nm-100nm, and the mass ratio of C2H5Li to LiI-coated solid electrolyte particles is (1-2.5):(8-15).
[0022] A modified solid electrolyte sheet comprising the modified solid electrolyte material described above or the modified solid electrolyte material obtained by the preparation method described above.
[0023] An all-solid-state lithium-ion battery includes a positive electrode, a negative electrode, and the modified solid electrolyte sheet.
[0024] The technical solution of this invention has the following advantages:
[0025] This invention provides a LiI-C2H5Li-coated solid electrolyte material. Through modification of the lithium iodide and ethyl lithium complex coating layer, the solid electrolyte effectively reduces side reactions with electrodes (including but not limited to lithium metal, silicon-carbon, and other negative electrodes), reducing the consumption of both the negative electrode and the electrolyte, thereby improving the overall energy density and cycle performance of the battery and exhibiting excellent storage performance. Secondly, through modification, effective anions (iodide ions) in the electrolyte deposit at the interface during cycling, inhibiting the growth of lithium dendrites and effectively improving the suppression of lithium dendrites, thus significantly increasing the cycle life throughout the entire cycle process. Thirdly, the modified sulfide electrolyte still possesses high ionic conductivity, ensuring high ion transport rates and low solid-solid interface impedance during cycling. In summary, the solid electrolyte modified with the lithium iodide and ethyl lithium complex coating layer effectively improves the compatibility between the solid electrolyte and the electrode. Furthermore, the raw materials used are inexpensive, and the modified solid electrolyte has a low Young's modulus, allowing for compaction of the powder under lower pressure, saving manufacturing costs in battery assembly.
[0026] This modification method is applicable to most sulfide electrolytes, and even to other solid electrolyte systems. The complex coating does not react with sulfide electrolytes, and it exhibits high stability, not being consumed during cycling.
[0027] This invention discloses a method for preparing a modified solid electrolyte material. In the electrolyte powder preparation process, LiI is first coated onto the surface of solid electrolyte particles. Then, the LiI-coated solid electrolyte particles are uniformly mixed with C2H5Li, allowing LiI and C2H5Li to adhere together to the surface of the solid electrolyte particles. After heating and complexation, LiI and C2H5Li undergo a complexation reaction, thereby forming a stable lithium iodide and lithium ethyl complex coating layer on the surface of the solid electrolyte particles. This modification method is effective and simple, requiring no expensive equipment, thus controlling costs and enabling widespread adoption in the lithium battery industry. After modifying the sulfide electrolyte, it has no significant impact on its ionic conductivity, etc., and improves the solid-solid interface stability with electrode materials such as lithium anodes without affecting the performance of the sulfide itself. This modification method has broad applicability, suitable for most sulfide solid electrolytes, without reducing the performance of the sulfide itself. While increasing the stability with the electrode, it also improves the air stability of the sulfide electrolyte, enabling large-scale production in dry air and meeting the conditions for large-scale mass production of all-solid-state secondary batteries. In addition, this modification method can effectively provide a prerequisite for the popularization of sulfide electrolytes and generate positive effects in secondary batteries such as sodium-ion batteries and zinc-ion batteries. Attached Figure Description
[0028] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.
[0029] Figure 1 These are SEM images of Li6PS5Cl powder in Example 1 of this invention before and after modification with LiI-C2H5Li, wherein... Figure 1 (a) is a SEM image of Li6PS5Cl powder before modification. Figure 1 (b) is a SEM image of Li6PS5Cl powder modified with LiI-C2H5Li;
[0030] Figure 2 This is a cycle performance diagram of the all-solid-state battery assembled with Li6PS5Cl@LiI-C2H5Li electrolyte in Example 1 of the present invention for the first 150 cycles;
[0031] Figure 3 The graph shows the cycle performance of an all-solid-state battery assembled with unmodified Li6PS5Cl electrolyte.
[0032] Figure 4 This is a graph showing the H2S concentration curves of Li6PS5Cl electrolyte and Li6PS5Cl@LiI-C2H5Li electrolyte in contact with air in a closed container.
[0033] Figure 5 The impedance comparison diagram is shown between Li6PS5Cl@LiI-C2H5Li of Example 1 and Li6PS5Cl of Comparative Example 1. Detailed Implementation
[0034] Example 1
[0035] A method for preparing a modified sulfide solid electrolyte material Li6PS5Cl@LiI-C2H5Li includes the following steps:
[0036] 1) Preparation of Li6PS5Cl solid electrolyte particles: 42.39g of LiCl (1mol), 114.875g of Li2S (2.5mol) and 111g of P2S5 (0.5mol) were added to a planetary ball mill to obtain a mixture; the mixture was ball-milled at 500rpm for 10h and annealed at 550℃ under vacuum for 2h; the annealed material was ground and passed through a 200-mesh sieve to obtain 1mol of Li6PS5Cl solid electrolyte particle powder;
[0037] 2) Modification treatment: First, LiI is coated onto Li6PS5Cl using a gas-phase method to obtain LiI-coated Li6PS5Cl solid electrolyte particles. Specifically, LiI vapor is introduced from the bottom inlet of the gas-phase reactor, and then Li6PS5Cl powder is injected from the top inlet of the reactor along with hot argon gas at 60℃; the LiI vapor introduction rate is 1 m / s². 3 LiI vapor was continuously introduced for 3 minutes from the time Li6PS5Cl powder was introduced until 3 minutes after the powder was removed; the introduction rate of Li6PS5Cl was 10 g / s, and the introduction time was 30 s; the introduction rate of hot argon was 0.01 m / s. 3 / min. The pressure in the reactor was adjusted so that the upper pressure was 0.03 kPa lower than the lower pressure, causing the gas to flow upwards while the solid electrolyte particles fell downwards due to gravity. The reactor was continuously heated, and the temperature was controlled at 80℃. The entire operation was carried out under an argon atmosphere, resulting in a LiI coating layer with a thickness of 20 nm. Then, ethyl lithium was complexed with the LiI coating layer to form a LiI-C2H5Li complex coating layer. Specifically, 10 g of LiI-Li6PS5Cl solid electrolyte particles and 2 g of ethyl lithium (C2H5Li) were ball-milled in a planetary ball mill at a rate of 200 rpm for 30 min, then heated to 95℃ and held for 2 h to form a lithium iodide and ethyl lithium complex coating layer on the surface of the solid electrolyte particles. After cooling, Li6PS5Cl@LiI-C2H5Li solid electrolyte particles were obtained.
[0038] like Figure 1 As shown, with Figure 1 (a) Compared to, from Figure 1 (b) It can be seen that many small particles are attached to the surface of the large particles, which indicates that LiI and C2H5Li form a new compound that is attached to the surface of Li6PS5Cl electrolyte particles.
[0039] Example 2
[0040] A method for preparing a modified sulfide solid electrolyte material Li3PS4@LiI-C2H5Li includes the following steps:
[0041] 1) Preparation of Li3PS4 solid electrolyte particles: 68.925g Li2S (1.5mol) and 111g P2S5 (0.5mol) were added to a planetary ball mill to obtain a mixture; the mixture was ball-milled at 500rpm for 5h and annealed at 450℃ under vacuum for 8h; the annealed material was ground and passed through a 100-mesh sieve to obtain 1mol of Li3PS4 solid electrolyte particle powder;
[0042] 2) Modification treatment: First, LiI is coated onto Li3PS4 using a gas-phase method to obtain LiI-coated Li3PS4 solid electrolyte particles. Specifically, LiI vapor is introduced from the bottom inlet of the gas-phase reactor, and then Li3PS4 powder is injected from the top inlet of the reactor along with hot argon gas at 60°C; the LiI vapor introduction rate is 3m / s. 3 LiI vapor was continuously introduced at a rate of 10 g / s for 2 minutes before Li3PS4 powder was introduced and for 2 minutes after the Li3PS4 powder was removed. The introduction time for Li3PS4 was 60 s, and the introduction rate for hot argon was 0.01 m / s. 3 / min. The pressure in the reactor was adjusted so that the upper pressure was 0.05 kPa lower than the lower pressure, causing the gas to flow upwards while the solid electrolyte particles fell downwards due to gravity. The reactor was continuously heated, and the temperature was controlled at 60℃. The entire operation was carried out under an argon atmosphere, resulting in a LiI coating layer with a thickness of 50 nm. Then, ethyl lithium was complexed with the LiI coating layer to form a LiI-C2H5Li complex coating layer. Specifically, 8 g of LiI-Li3PS4 solid electrolyte particles and 1 g of ethyl lithium (C2H5Li) were ball-milled in a planetary ball mill at a rate of 100 rpm for 50 min, then heated to 200℃ and held for 2 h to form a lithium iodide and ethyl lithium complex coating layer on the surface of the solid electrolyte particles. After cooling, Li3PS4@LiI-C2H5Li solid electrolyte particles were obtained.
[0043] Example 3
[0044] A modified sulfide solid electrolyte material Li 10 GeP2S 12 The preparation method of @LiI-C2H5Li includes the following steps:
[0045] 1) Preparation of Li 10 GeP2S 12 Solid electrolyte particles: 136.6 g of GeS2 (1 mol), 229.75 g of Li2S (5 mol), and 222 g of P2S5 (1 mol) were added to a planetary ball mill to obtain a mixture; the mixture was ball-milled at 500 rpm for 6 h and annealed at 600 °C under vacuum for 5 h; the annealed material was then ground and passed through a 400-mesh sieve to obtain 1 mol of Li2S5. 10 GeP2S 12 Solid electrolyte;
[0046] 2) Modification treatment: First, LiI is coated onto Li using a gas-phase method. 10 GeP2S 12 Above, LiI-coated Li was obtained 10 GeP2S12 Solid electrolyte particles, specifically, LiI vapor is introduced from the bottom inlet of the gas-phase reactor, and then Li... 10 GeP2S 12 The powder was injected into the reactor from the top along with hot argon gas at 60°C; the LiI vapor was introduced at a rate of 0.2 m / s. 3 / h is adjusted, and the inlet time is controlled within Li 10 GeP2S 12 Powder is introduced into Li for 3 minutes before the process. 10 GeP2S 12 Within 4 minutes after powder removal; Li 10 GeP2S 12 The gas flow rate was 10 g / s, the flow time was 120 s, and the flow rate of hot argon was 0.01 m. 3 / min. The pressure at the top of the reactor was adjusted to be 0.01 kPa lower than the pressure at the bottom, causing the overall gas flow to rise while the solid electrolyte particles fell due to gravity. The reactor was continuously heated, with the temperature controlled at 100℃. The entire operation was conducted under an argon atmosphere, resulting in a 100 nm thick LiI coating. Then, ethyl lithium was complexed with the LiI coating to form a LiI-C2H5Li complex coating. Specifically, 15 g of LiI-Li... 10 GeP2S 12 Solid electrolyte powder and 2.5 g of ethyl lithium (C2H5Li) were ball-milled in a planetary ball mill at 50 rpm for 120 min. The mixture was then heated to 80 °C and held for 5 h to form a lithium iodide-ethyl lithium complex coating on the surface of the solid electrolyte particles. After cooling, Li was obtained. 10 GeP2S 12 @LiI-C2H5Li solid electrolyte particle powder.
[0047] Example 4
[0048] A method for preparing a modified sulfide solid electrolyte material Li6PS5Cl@LiI-C2H5Li includes the following steps:
[0049] 1) Preparation of Li6PS5Cl solid electrolyte particles: 42.39g of LiCl (1mol), 114.875g of Li2S (2.5mol) and 111g of P2S5 (0.5mol) were added to a planetary ball mill to obtain a mixture; the mixture was ball-milled at 500rpm for 10h and annealed at 550℃ under vacuum for 6h; the annealed material was ground and passed through a 200-mesh sieve to obtain 1mol of Li6PS5Cl solid electrolyte particle powder;
[0050] 2) Modification treatment: First, LiI was coated onto Li6PS5Cl by liquid phase method. Specifically, 5g of LiI was dissolved in 300ml of tetrahydrofuran and stirred for 30min to obtain a precursor solution. 12g of Li6PS5Cl was added to the precursor solution and stirred evenly. The mixture was stirred slowly for 15min and the solvent was dried to obtain LiI-Li6PS5Cl solid electrolyte particles. 9g of LiI-Li6PS5Cl solid electrolyte particle powder and 1g of ethyl lithium (C2H5Li) were ball-milled in a planetary ball mill at 500rpm for 30min. After heating to 600℃ and holding for 1h, a lithium iodide and ethyl lithium complex coating layer was formed on the surface of the solid electrolyte particles. After cooling, Li6PS5Cl@LiI-C2H5Li solid electrolyte particle powder was obtained.
[0051] Comparative Example 1
[0052] A sulfide solid electrolyte material, which is unmodified Li6PS5Cl solid electrolyte particles.
[0053] Comparative Example 2
[0054] A method for preparing a modified sulfide solid electrolyte material Li6PS5Cl@LiI includes the following steps:
[0055] 1) Preparation of Li6PS5Cl solid electrolyte particles: 42.39g of LiCl (1mol), 114.875g of Li2S (2.5mol) and 111g of P2S5 (0.5mol) were added to a planetary ball mill to obtain a mixture; the mixture was ball-milled at 500rpm for 10h and annealed at 550℃ under vacuum for 2h; the annealed material was ground and passed through a 200-mesh sieve to obtain 1mol of Li6PS5Cl solid electrolyte particle powder;
[0056] 2) Modification treatment: LiI was coated onto Li6PS5Cl using a gas-phase method to obtain LiI-coated Li6PS5Cl solid electrolyte particles. Specifically, LiI vapor was introduced from the bottom inlet of the gas-phase reactor, and then Li6PS5Cl powder was injected from the top inlet of the reactor along with hot argon gas at 60°C; the LiI vapor introduction rate was 1 m / s. 3 LiI vapor was continuously introduced for 3 minutes from the time Li6PS5Cl powder was introduced until 3 minutes after the powder was removed; the introduction rate of Li6PS5Cl was 10 g / s, the introduction time was 30 s, and the introduction rate of hot argon was 0.01 m / s. 3 / min. The pressure at the top of the reactor was adjusted to be 0.03 kPa lower than the pressure at the bottom, causing the overall gas to flow upwards while the solid electrolyte particles fell downwards due to gravity. The reactor was continuously heated, with the temperature controlled at 80°C. The entire operation was carried out under an argon atmosphere, resulting in a LiI coating layer with a thickness of 20 nm.
[0057] Comparative Example 3
[0058] A method for preparing a modified sulfide solid electrolyte material Li6PS5Cl@C2H5Li includes the following steps:
[0059] 1) Preparation of Li6PS5Cl solid electrolyte particles: 42.39g of LiCl (1mol), 114.875g of Li2S (2.5mol) and 111g of P2S5 (0.5mol) were added to a planetary ball mill to obtain a mixture; the mixture was ball-milled at 500rpm for 10h and annealed at 550℃ under vacuum for 2h; the annealed material was ground and passed through a 200-mesh sieve to obtain 1mol of Li6PS5Cl solid electrolyte particles;
[0060] 2) Modification treatment: Ethyl lithium is coated on the surface of Li6PS5Cl solid electrolyte particles to obtain ethyl lithium coated Li6PS5Cl solid electrolyte particles. Specifically, 10g of Li6PS5Cl solid electrolyte particles and 2g of ethyl lithium (C2H5Li) are ball-milled in a planetary ball mill at a rate of 200rpm for 30min, then heated to 95℃ and held for 2h, and then cooled to obtain Li6PS5Cl@C2H5Li solid electrolyte particles.
[0061] Test case
[0062] The modified sulfide solid electrolyte material Li6PS5Cl@LiI-C2H5Li prepared in Example 1 was pressed into sheets under a pressure of 300 MPa, and then pressed together with NCM811 positive electrode sheets and lithium metal negative electrode sheets under a pressure of 6 MPa. The resulting battery was then held at 3 MPa for 24 hours to obtain an NCM811 / Li6PS5Cl@LiI-C2H5Li / Li all-solid-state lithium-ion battery. Following the same method, only the solid electrolyte material was replaced. The modified solid electrolyte particles from Examples 2-4, the unmodified solid electrolyte particles from Comparative Example 1, and the modified solid electrolyte particles from Comparative Examples 2 and 3 were pressed into sheets and assembled to form all-solid-state lithium-ion batteries.
[0063] Electrochemical performance testing of solid electrolytes:
[0064] To verify and compare the cycle performance of the modified solid electrolyte in all-solid-state batteries, and to investigate the reaction between the electrolyte and the electrode and the resistance to lithium dendrite formation in all-solid-state batteries, cycle tests were conducted on all-solid-state lithium-ion batteries assembled in Examples 1-4 and Comparative Examples 1-3. The test conditions were as follows: the all-solid-state lithium-ion batteries were first charged and discharged three times at a rate of 0.05C, with a voltage range of 2.8V-4.2V, and then charged and discharged at a rate of 0.1C, still with a voltage range of 2.8V-4.2V. A 10-minute rest period was allowed between each cycle. The electrochemical performance of the sulfide solid electrolyte was verified, and the results are shown in Table 1.
[0065] Table 1. Cyclic test results of all-solid-state lithium-ion batteries
[0066]
[0067]
[0068] like Figure 3 As shown, the unmodified sulfide electrolyte short-circuited after approximately twenty revolutions. Figure 2 As shown, the modified sulfide electrolyte Li6PS5Cl@LiI-C2H5Li exhibits significantly improved cycle performance compared to the unmodified Li6PS5Cl electrolyte. In the assembled NCM811 / Li6PS5Cl@LiI-C2H5Li / Li all-solid-state battery, it demonstrates excellent cycle performance, retaining 87% capacity after 150 cycles, with a coulombic efficiency close to 100%. As shown in Table 1, the LiI-C2H5Li complex-modified solid-state electrolytes in Examples 2-4 also exhibit excellent cycle performance. This is because after the solid electrolyte particles are coated with the LiI-C2H5Li complex, the coating layer isolates the solid electrolyte particles from direct contact with the electrode, reducing side reactions and significantly improving the compatibility of the solid electrolyte with both the lithium anode and the NCM811 cathode. Figure 2 As shown, there is a slight capacity decay in the early stage of cycling. This is because the LiI-C2H5Li complex forms a stable SEI layer with the lithium metal anode, which consumes some of the active lithium. Stable performance is obtained in subsequent cycles. Therefore, the lithium dendrite resistance of the modified Li6PS5Cl@LiI-C2H5Li is also significantly improved.
[0069] Air stability tests of sulfide solid electrolytes before and after modification:
[0070] To test and demonstrate the improved air stability of the modified sulfide solid electrolyte, the amount of H2S generated was compared between the solid electrolyte powder before and after modification in a closed space for 5 minutes. The air stability was explored by detecting the H2S concentration: the more H2S generated and the higher the concentration, the worse the air stability; the less H2S generated and the lower the concentration, the better the air stability.
[0071] like Figure 4 As shown in Table 1, the H2S rise curves within a sealed container over 300 seconds show that, compared to the unmodified sample in Comparative Example 1, the modified Li6PS5Cl@LiI-C2H5Li electrolyte of Example 1 exhibits a 14% reduction in H2S concentration over 300 seconds. The air stability of the LiI-C2H5Li complex-modified solid electrolytes in Examples 2-4 is also improved. This is attributed to the LiI-C2H5Li complex coating layer in the modified sulfide electrolyte effectively isolating the solid electrolyte from direct contact with air, thereby reducing sulfide electrolyte decomposition and significantly decreasing Li2S production. Therefore, the air stability of the modified sulfide electrolyte is significantly improved.
[0072] Impedance test:
[0073] Impedance tests were performed on the electrolytes of Example 1 and Comparative Example 1. The impedance test conditions were as follows: 50g of solid electrolyte powder was pressed into a sheet with a diameter of 10mm under a pressure of 300M. Platinum sheets with a diameter of 10mm and a thickness of 0.1mm were attached to both sides of the electrolyte sheet. The sheet was then clamped in a mold, and a pressure of 5Mpa was applied to both sides of the mold for testing. The test conditions were: frequency 10MHz-0.1mHz, amplitude 10mV.
[0074] like Figure 5 As shown, compared with the unmodified Li6PS5Cl electrolyte, the modified Li6PS5Cl@LiI-C2H5Li electrolyte can maintain a lower solid-solid interface impedance during cycling, i.e., a higher ion transport rate, while still having a higher ionic conductivity.
[0075] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.
Claims
1. A modified solid electrolyte material, characterized in that, It includes solid electrolyte particles and a lithium iodide and lithium ethyl complex coating layer covering the surface of the solid electrolyte particles; The preparation method includes the following steps: coating LiI onto the surface of solid electrolyte particles to obtain LiI-coated solid electrolyte particles; After mixing the LiI-coated solid electrolyte particles with C2H5Li, the surface of the solid electrolyte particles is coated with a lithium iodide and ethyl lithium complex by heating to obtain the modified solid electrolyte material. The heating complexation temperature is 80-95℃; The solid electrolyte particles are sulfide solid electrolyte particles.
2. The modified solid electrolyte material according to claim 1, characterized in that, The solid electrolyte particles are made of lithium phosphorus sulfur, lithium germanium phosphorus sulfur, lithium phosphorus sulfur bromine, lithium phosphorus sulfur iodine, or lithium phosphorus sulfur chlorine.
3. The method for preparing a modified solid electrolyte material according to claim 1, characterized in that, Includes the following steps: LiI-coated solid electrolyte particles are obtained by coating the surface of solid electrolyte particles with LiI. After mixing the LiI-coated solid electrolyte particles with C2H5Li, the surface of the solid electrolyte particles is coated with a lithium iodide and ethyl lithium complex by heating to obtain the modified solid electrolyte material. The heating complexation temperature is 80-95℃.
4. The preparation method according to claim 3, characterized in that, The LiI-coated solid electrolyte particles and C2H5Li were mixed by grinding. And / or, the heating and complexing holding time is 0.5-5h.
5. The preparation method according to claim 4, characterized in that, The grinding method is ball milling, with a ball milling speed of 50-500 rpm and a ball milling time of 0.5-120 min.
6. The preparation method according to claim 3, characterized in that, The solid electrolyte is a sulfide solid electrolyte, and the preparation of the sulfide solid electrolyte includes the following steps: mixing raw materials in the formula ratio to obtain a mixture; grinding the mixture and vacuum annealing to obtain sulfide solid electrolyte particles; The raw materials are lithium sulfide and phosphorus pentasulfide, or lithium sulfide, phosphorus pentasulfide and germanium sulfide, or lithium sulfide, phosphorus pentasulfide and lithium halide, wherein the lithium halide is any one of lithium chloride, lithium bromide and lithium iodide.
7. The preparation method according to claim 6, characterized in that, The mixture is prepared by grinding. And / or, the annealing temperature is 400-600℃, and the annealing time is 2h-8h; And / or, after annealing, the process also includes grinding and sieving the annealed material, with a sieve mesh size of 100-400 mesh.
8. The preparation method according to claim 7, characterized in that, The grinding method is ball milling, with a ball milling speed of 200-700 rpm and a ball milling time of 2-24 hours.
9. The preparation method according to claim 3, characterized in that, The preparation method of the LiI-coated solid electrolyte particles is as follows: LiI coating was performed using a vapor phase method. Alternatively, LiI coating can be performed using a liquid phase method.
10. The preparation method according to claim 9, characterized in that, The step of LiI coating via the gas phase method is as follows: under an inert atmosphere, LiI vapor is contacted with the solid electrolyte particles to obtain LiI-coated solid electrolyte particles; the flow rate of the LiI vapor is 0.2 m³ / s. 3 / h-3m 3 / h, the LiI vapor introduction time is from before the solid electrolyte particles are introduced until after the solid electrolyte particles are removed; the introduction rate of the solid electrolyte particles is 5-30 g / s, the introduction time is 30-120 s; the reaction temperature is between 60-100℃; Alternatively, the step of coating LiI by liquid phase method is as follows: dissolve LiI in a solvent to obtain a precursor solution, add the solid electrolyte particles to the precursor solution and stir for 10-15 min; vacuum dry the solvent to obtain LiI-coated solid electrolyte particles.
11. The preparation method according to claim 10, characterized in that, The solvent is an organic solvent, which is one or more of tetrahydrofuran, toluene, and xylene; the concentration of LiI in the solvent is 0.01 g / ml to 0.5 g / ml, and the concentration of the solid electrolyte particles in the solvent is 0.04 g / ml to 0.05 g / ml.
12. A modified solid electrolyte sheet, characterized in that, The modified solid electrolyte material comprising any one of claims 1-3 or the modified solid electrolyte material obtained by any one of claims 3-11.
13. An all-solid-state lithium-ion battery, characterized in that, It includes a positive electrode, a negative electrode, and a modified solid electrolyte sheet as described in claim 12.