Glassy sulfide solid electrolyte material with high lithium iodide content, and preparation method and application thereof
By introducing glassy sulfides with high LiI content into the sulfide electrolyte, the lithium-ion diffusion channels are broadened and a stable interface layer is formed, which solves the problems of anode stability and conductivity of sulfide electrolytes in all-solid-state lithium metal batteries, and achieves improved energy density and safety.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- ZHEJIANG UNIV
- Filing Date
- 2023-04-25
- Publication Date
- 2026-05-12
AI Technical Summary
Existing sulfide electrolytes in all-solid-state lithium metal batteries suffer from poor negative electrode stability, lithium dendrite growth, and low conductivity, making it difficult to meet the requirements for high energy density and safety.
A glassy sulfide solid electrolyte material with high lithium iodide content is used. By introducing MS2 to reduce the dimer content in the glass network structure, a glassy sulfide with high LiI content is formed, which widens the lithium-ion diffusion channel, reduces the diffusion energy barrier, and forms a LiI-rich interface layer to suppress lithium dendrite growth.
It improves lithium-ion conductivity, enhances negative electrode stability, suppresses lithium dendrite growth, and improves the cycle performance and safety of all-solid-state lithium metal batteries.
Smart Images
Figure CN116315056B_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of solid electrolyte materials for lithium-ion batteries, specifically to a glassy sulfide solid electrolyte with high lithium iodide content, its preparation method, and its application in all-solid-state lithium metal batteries. Background Technology
[0002] With the dwindling supply of non-renewable petroleum fuels and the exacerbating greenhouse effect caused by excessive carbon emissions, the development of electrochemical energy storage devices is receiving increasing attention. Recently, the widespread adoption of digital devices and electric vehicles has placed higher demands on energy storage devices. Lithium-ion batteries have been widely adopted due to their high energy density, lack of memory effect, and good cycle stability. However, the ester / ether-based organic electrolytes used in classic lithium-ion batteries are volatile and flammable, posing significant safety hazards under conditions of overcharging, over-discharging, and leakage. Furthermore, liquid lithium-ion batteries have a theoretical energy density of 350 Wh / kg. -1 To a certain extent, existing energy storage systems are no longer sufficient to meet the demands of modern high-performance electronic devices. Therefore, developing the next generation of energy storage systems with high energy density and high safety is crucial. All-solid-state lithium metal batteries use metallic lithium instead of graphite as the negative electrode, significantly improving the energy density of the battery system. Simultaneously, the solid electrolyte layer replaces the electrolyte and separator in traditional lithium-ion batteries, fundamentally addressing the safety hazards of the battery system. Currently, all-solid-state lithium metal batteries have become one of the most promising future energy storage systems.
[0003] Currently, solid-state electrolytes are mainly classified into three types: inorganic solid-state electrolytes, polymer solid-state electrolytes, and polymer / inorganic composite solid-state electrolytes. Among them, inorganic solid-state electrolytes can be further divided into oxide, sulfide, and halide types. Of all types of solid-state electrolytes, sulfide electrolytes have attracted much attention due to their ionic conductivity comparable to liquid electrolytes and their ease of cold-pressing. However, sulfide electrolytes suffer from poor negative electrode stability and are prone to violent side reactions with lithium metal during cycling, generating an interface layer with low ionic conductivity, leading to increased battery polarization. Simultaneously, the electronic conductivity of sulfide electrolytes themselves and the grain boundaries present in crystalline sulfides are also speculated to be contributing factors to lithium dendrite growth and eventual short circuits. Compared to crystalline sulfides, glassy sulfides have higher compaction density due to the absence of grain boundaries; their amorphous nature allows for greater tolerance to compositional variations, thus enabling coupled regulation of composition, properties, and interface behavior. In particular, lithium iodide-doped glassy sulfides possess high ionic conductivity and high stability against lithium. The lithium iodide formed at the interface exhibits relatively high stability and ionic conductivity, effectively suppressing lithium dendrite growth. Therefore, to achieve the assembly of high-safety, high-energy-density all-solid-state lithium metal batteries, designing and synthesizing a novel glassy sulfide solid electrolyte with high lithium iodide content while maintaining the absence of a crystalline phase in the glassy system is of great significance. Summary of the Invention
[0004] The purpose of this invention is to provide a glassy sulfide solid electrolyte with high lithium iodide content, its preparation method, and its application in all-solid-state lithium metal batteries. This glassy sulfide solid electrolyte with high lithium iodide content has high ionic conductivity and good stability to metallic lithium. All-solid-state lithium metal batteries assembled with this novel glassy sulfide solid electrolyte with high lithium iodide content have excellent cycle performance, high charge-discharge specific capacity, and high safety.
[0005] A glassy sulfide solid electrolyte material with high lithium iodide content has the chemical composition (0.65-x)((0.75+0.5y)Li₂S-(0.25-0.5y)P₂S₅-yMS₂)-(0.35+x)LiI, where x≥0, y>0, and M is a metal or nonmetal element of Group IV.
[0006] Preferably, x is 0 to 0.1, y is 0 to 0.2, and M is one of SiS2, GeS2, and SnS2.
[0007] The glassy sulfide solid electrolyte material with high lithium iodide content described in this invention is an amorphous powder material.
[0008] This invention is based on a 75Li2S-25P2S5 glassy system with a stoichiometric ratio of Li3PS4. By modifying the glass framework and introducing MS2, the content of dimers in the glass network structure is reduced, providing space for higher lithium iodide doping and forming a high-LiI-content glassy sulfide solid electrolyte material. The electrolyte is a glassy phase.
[0009] Further preferably, the high LiI content glassy sulfide solid electrolyte material is (0.65-x)((0.75+0.5y)Li2S-(0.25-0.5y)P2S5-yMS2)-(0.35+x)LiI, where x is 0.03-0.08, y is 0.02-0.1, and MS2 is SiS2.
[0010] In this invention, the LiI doped in the glass system occupies the interstitial positions of the glass framework, because I - The large ionic radius of I- broadens the diffusion channels of lithium ions; due to the large ionic radius of I-, the diffusion channels of lithium ions are widened; + The weaker binding capacity lowers the diffusion barrier of lithium ions within the glass framework. Consequently, glassy sulfide solid electrolyte materials with high LiI content exhibit higher ionic conductivity. Simultaneously, these materials tend to form a LiI-rich interface layer on the negative electrode side. This interface layer possesses high ionic conductivity and good stability, effectively reducing interfacial polarization and suppressing lithium dendrite growth.
[0011] The method for preparing a glassy electrolyte with high LiI content includes the following steps:
[0012] (1) Weigh the following raw materials according to the molar ratio: compounds Li2S, P2S5, MS2 and LiI.
[0013] (2) Use an agate mortar and pestle to manually grind and mix the weighed raw materials to obtain a uniformly mixed precursor.
[0014] (3) The obtained precursors are mixed and ball-milled to obtain the glassy sulfide solid electrolyte.
[0015] The following are preferred technical solutions of the present invention:
[0016] In step (1), MS2 is SiS2. The molar ratio of the chemical and Li2S, P2S5, SiS2 and LiI is (0.43~0.50):(0.11~0.15):(0.01~0.06):(0.38~0.43).
[0017] In step (2), the grinding and mixing time is 30 to 60 minutes.
[0018] In step (3), the ball milling is a high-energy mechanical ball milling, the ball milling speed is 500-700 rpm, the ball milling time is 10-70 hours, and the sample obtained by ball milling is a slightly yellow sample with certain hygroscopicity.
[0019] In step (3), the high-energy ball milling is carried out under an inert atmosphere, which is any one of argon, neon, and helium, preferably argon. The water content of the atmosphere is less than 0.1 ppm, and the oxygen content is less than 10 ppm.
[0020] The application of the high lithium iodide content glassy sulfide solid electrolyte material in the preparation of all-solid-state lithium batteries specifically includes:
[0021] The positive electrode of the all-solid-state lithium metal battery is any one of NCM ternary material, lithium cobalt oxide, and sulfur, preferably NCM ternary material; the intermediate electrolyte of the all-solid-state lithium metal battery is a glassy sulfide solid electrolyte material with high lithium iodide content; the negative electrode of the all-solid-state lithium metal battery is metallic lithium.
[0022] Compared with the prior art, the present invention has the following advantages:
[0023] By increasing the LiI content in the glassy sulfide solid electrolyte, the diffusion channels of lithium ions are broadened, the binding effect of anions on lithium ions is reduced, and the diffusion energy barrier of lithium ions is lowered, resulting in a glassy sulfide solid electrolyte with higher ionic conductivity.
[0024] By increasing the LiI content in the glassy sulfide solid electrolyte, the Li2S content in the system is reduced, thereby lowering production costs.
[0025] The prepared sulfide solid electrolyte exhibits better negative electrode stability, longer stability time in lithium cycle tests, and less battery polarization.
[0026] The prepared sulfide solid electrolyte has a better ability to suppress lithium dendrite growth. Applying the prepared sulfide solid electrolyte to all-solid-state lithium metal batteries can effectively reduce the risk of battery short circuit and enhance the cycle stability of the battery.
[0027] All-solid-state lithium metal batteries assembled using the sulfide solid electrolyte of this invention have advantages such as large charge / discharge specific capacity and high cycle stability. Attached Figure Description
[0028] Figure 1 This is a scanning electron microscope image of the glassy sulfide solid electrolyte material from Example 1.
[0029] Figure 2The XRD phase analysis diagram of the glassy sulfide solid electrolyte material in Example 1 is shown.
[0030] Figure 3 AC impedance spectrum of glassy sulfide solid electrolyte material prepared into a thin sheet and carbon-coated aluminum foil fixed on both sides of the sheet, as shown in Example 1;
[0031] Figure 4 The critical current density diagram of the glassy sulfide solid electrolyte material of Example 1, which is fabricated into a thin sheet and has metallic lithium sheets fixed on both sides of the sheet;
[0032] Figure 5 The corresponding XRD pattern for Comparative Example 2;
[0033] Figure 6 The diagram shows the critical current test result for Comparative Example 2. Detailed Implementation
[0034] The present invention will be described in detail below with reference to embodiments, but the present invention is not limited thereto.
[0035] Example 1
[0036] 1. This embodiment provides a glassy sulfide solid electrolyte with high LiI content, whose chemical composition is 0.6(0.786Li2S-0.214P2S5-0.0714SiS2)-0.4LiI.
[0037] 2. In an argon-protected glove box, weigh the compounds Li2S, P2S5, SiS2 and LiI respectively in a molar ratio of 0.472:0.128:0.043:0.4.
[0038] 3. Grind and mix the weighed materials for 30 minutes to obtain a uniformly mixed precursor.
[0039] 4. The obtained precursor was placed in an argon-protected zirconium dioxide ball mill jar and milled at 650 rpm for 40 hours to obtain a slightly yellow glassy sulfide solid electrolyte material with a particle size of approximately 4 μm. Figure 1 As shown. XRD phase analysis revealed the absence of obvious LiI impurity peaks, as indicated. Figure 2 As shown.
[0040] 5. Using a tablet press, 150 mg of the obtained glassy solid electrolyte material powder was pressed into a sheet of approximately 0.9 mm thick under a pressure of 500 MPa. Carbon-coated aluminum foil was fixed to both sides of the sheet to form a sandwich structure. Its AC impedance spectrum was obtained using a Princeton electrochemical workstation, and its ohmic impedance was Ω ( Figure 3 ), thereby calculating its ionic conductivity.
[0041] 6. Using a tablet press, 150 mg of the obtained glassy solid electrolyte material powder was pressed into a sheet of approximately 0.9 mm thick under a pressure of 500 MPa. A 0.1 mm thick lithium metal sheet was fixed to both sides of the sheet to form a sandwich structure. The negative electrode stability of the obtained glassy solid electrolyte powder was verified through constant current charge-discharge cycle testing and critical current density testing. Figure 4 As shown, its critical current density is 1.20 mA / cm². -2 .
[0042] Commercial NMC811 cathode and commercial Li6PS5Cl electrolyte were placed in an agate mortar in a 7:3 ratio and manually ground for 60 minutes to obtain NMC811 composite cathode material.
[0043] 7. Using a tablet press, 80 mg of the obtained glassy solid electrolyte material powder was pressed into a sheet of approximately 0.45 mm in diameter at 500 MPa for 5 minutes. 8 mg of NMC811 composite cathode material was dispersed on one side of the sheet, and the sheet was pressed again at 500 MPa for 10 minutes. Finally, the lithium metal anode was placed on the other side of the sheet and pressed at 20 MPa for 1 minute to produce an all-solid-state lithium metal battery. The cycle stability and rate performance of the all-solid-state lithium metal battery were verified through constant current charge-discharge cycle tests and rate tests.
[0044] Example 2
[0045] 1. This embodiment provides a glassy sulfide solid electrolyte with high LiI content, whose chemical composition is 0.62(0.77Li2S-0.23P2S5-0.04SiS2)-0.38LiI.
[0046] 2. In an argon-protected glove box, weigh the compounds Li2S, P2S5, SiS2 and LiI respectively in a molar ratio of 0.477:0.142:0.024:0.38.
[0047] 3. Grind and mix the weighed raw materials for 20 minutes to obtain a uniformly mixed precursor.
[0048] 4. The obtained precursor was placed in an argon-protected zirconium dioxide ball mill jar and milled at 600 rpm for 32 hours to obtain a slightly yellow glassy sulfide solid electrolyte material.
[0049] 5. Using a tablet press, 150 mg of the obtained glassy solid electrolyte material powder was pressed into a sheet of approximately 0.93 mm under a pressure of 500 MPa. Carbon-coated aluminum foil was fixed on both sides of the sheet to form a sandwich structure. Its AC impedance spectrum was obtained using a Princeton electrochemical workstation, and its ionic conductivity was calculated.
[0050] 6. Using a tablet press, 150 mg of the obtained glassy solid electrolyte material powder was pressed into a sheet of approximately 0.93 mm under a pressure of 500 MPa. A 0.1 mm thick lithium metal sheet was fixed on both sides of the sheet to form a sandwich structure. The negative electrode stability of the obtained glassy solid electrolyte powder was verified by constant current charge-discharge cycle test and critical current density test.
[0051] Commercial NMC811 cathode and commercial Li6PS5Cl electrolyte were placed in an agate mortar in a 7:3 ratio and manually ground for 60 minutes to obtain NMC811 composite cathode material.
[0052] 7. Using a tablet press, 80 mg of the obtained glassy solid electrolyte material powder was pressed into a sheet of approximately 0.50 mm in diameter at 500 MPa for 5 minutes. 8 mg of NMC811 composite cathode material was dispersed on one side of the sheet, and the sheet was pressed again at 500 MPa for 10 minutes. Finally, a lithium metal anode was placed on the other side of the sheet and pressed at 20 MPa for 1 minute to produce an all-solid-state lithium metal battery. The cycle stability and rate performance of the all-solid-state lithium metal battery were verified through constant current charge-discharge cycle tests and rate tests.
[0053] Example 3
[0054] 1. This embodiment provides a glassy sulfide solid electrolyte with high LiI content, whose chemical composition is 0.61(0.781Li2S-0.218P2S5-0.0625SiS2)-0.39LiI.
[0055] 2. In an argon-protected glove box, weigh the compounds Li2S, P2S5, SiS2 and LiI respectively in a molar ratio of 0.476:0.133:0.038:0.39.
[0056] 3. Grind and mix the weighed raw materials for 40 minutes to obtain a uniformly mixed precursor.
[0057] 4. The obtained precursor was placed in an argon-protected zirconium dioxide ball mill jar and milled at 675 rpm for 36 hours to obtain a slightly yellow glassy sulfide solid electrolyte material.
[0058] 5. Using a tablet press, 150 mg of the obtained glassy solid electrolyte material powder was pressed into a sheet of approximately 0.91 mm under a pressure of 500 MPa. Carbon-coated aluminum foil was fixed on both sides of the sheet to form a sandwich structure. The AC impedance spectrum was obtained using a Princeton electrochemical workstation, and its ionic conductivity was calculated.
[0059] 6. Using a tablet press, 150 mg of the obtained glassy solid electrolyte material powder was pressed into a sheet of approximately 0.91 mm under a pressure of 500 MPa. A 0.1 mm thick lithium metal sheet was fixed on both sides of the sheet to form a sandwich structure. The negative electrode stability of the obtained glassy solid electrolyte powder was verified by constant current charge-discharge cycle test and critical current density test.
[0060] Commercial NMC811 cathode and commercial Li6PS5Cl electrolyte were placed in an agate mortar in a 7:3 ratio and manually ground for 60 minutes to obtain NMC811 composite cathode material.
[0061] 7. Using a tablet press, 80 mg of the obtained glassy solid electrolyte material powder was pressed into a sheet of approximately 0.47 mm in diameter at 500 MPa for 5 minutes. 8 mg of NMC811 composite cathode material was dispersed on one side of the sheet, and the sheet was pressed again at 500 MPa for 10 minutes. Finally, a lithium metal anode was placed on the other side of the sheet and pressed at 20 MPa for 1 minute to produce an all-solid-state lithium metal battery. The cycle stability and rate performance of the all-solid-state lithium metal battery were verified through constant current charge-discharge cycle tests and rate tests.
[0062] Comparative Example 1
[0063] Classic glassy sulfide solid electrolyte, chemically composed of 0.75Li₂S-0.25P₂S₅, otherwise the same.
[0064] Example 1
[0065] Comparative Example 2
[0066] The sulfide electrolyte with high LiI content without SiS2 introduction has a chemical composition of 0.6(0.75Li2S-0.24P2S5)-0.4LiI, and the rest is the same as in Example 1. Figure 5 The corresponding XRD patterns show that there are obvious LiI crystallization peaks in Comparative Example 2, and its glass network structure cannot accommodate the same amount of LiI as in Example 1. Figure 6 The graph shows the critical current test result for Comparative Example 2, with a critical current density of 0.7 mA cm⁻¹. -2 The value was significantly lower than that of Example 1.
[0067] Performance testing
[0068] Table 1. Statistics of Ion Conductivity
[0069]
[0070] The lithium symmetric batteries prepared in Examples 1-3 and Comparative Examples 1-2 were subjected to critical current density tests, and the current step gradient was 0.1 mA cm⁻¹. -2 The single charge and discharge time was 1 hour each, the test temperature was 25℃, and the critical current density statistics are shown in Table 3:
[0071] Table 2. Statistics on the critical current density of symmetrical cells
[0072]
[0073] The all-solid-state lithium batteries prepared in Examples 1-3 and Comparative Examples 1-2 were subjected to constant current charge-discharge tests. The test conditions were a charge-discharge voltage range of 2.5-4.2V, a charge-discharge rate of 0.2C, and a test temperature of 25℃. The capacity retention rate after 100 cycles is shown in Table 3.
[0074] Table 3. Statistics on the Constant Current Charge-Discharge Cycle Performance of All-Solid-State Lithium Metal Batteries
[0075]
[0076] As can be seen from Tables 1-3, the glassy sulfide solid electrolyte with high lithium iodide content prepared above has advantages such as high ionic conductivity and good lithium compatibility. All-solid-state lithium metal batteries assembled with this high-lithium-iodide glassy sulfide solid electrolyte exhibit excellent cycle stability and high safety. This is because, on the one hand, the higher LiI content doping in the glassy sulfide solid electrolyte reduces the amount of lithium ions absorbed by S. 2- The confinement of lithium ions lowers the diffusion barrier, thereby improving ionic conductivity. On the other hand, the higher content of LiI doping enables the formation of a LiI-rich solid electrolyte layer at the interface between the electrolyte and lithium metal, which can effectively suppress the growth of lithium dendrites.
Claims
1. A glassy sulfide solid electrolyte material with high lithium iodide content, characterized in that, Its chemical composition is (0.65-x)((0.75+0.5y)Li2S-(0.25-0.5y)P2S5-yMS2)-(0.35+x)LiI, where 0≤x<0.1, where 0<y<0.2, and where M is a metal or nonmetal element of Group IV. Where x is 0.03-0.08, y is 0.02-0.1, and MS2 is SiS2; The electrolyte material is a glass phase electrolyte material.
2. The method for preparing a glassy sulfide solid electrolyte material with high lithium iodide content according to claim 1, characterized in that, Includes the following steps: (1) Weigh the following raw materials according to the molar ratio of (0.65-x)((0.75+0.5y)Li2S-(0.25-0.5y)P2S5-yMS2)-(0.35+x)LiI: compounds Li2S, P2S5, MS2 and LiI; (2) Grind and mix the raw materials to obtain a uniformly mixed precursor; (3) The obtained precursors were mixed and ball-milled to obtain a glassy sulfide solid electrolyte material with high lithium iodide content.
3. The method for preparing a glassy sulfide solid electrolyte material with high lithium iodide content according to claim 2, characterized in that, In step (1), MS2 is SiS2.
4. The method for preparing a glassy sulfide solid electrolyte material with high lithium iodide content according to claim 2, characterized in that, In step (2), the grinding and mixing time is 10 to 100 minutes.
5. The method for preparing a glassy sulfide solid electrolyte material with high lithium iodide content according to claim 2, characterized in that, In step (3), the ball mill is a high-energy mechanical ball mill, the ball mill speed is 500-700 rpm, and the ball milling time is 10-70 hours.
6. The application of the glassy sulfide solid electrolyte material with high lithium iodide content according to claim 1 in the preparation of all-solid-state lithium batteries.
7. The application according to claim 6, characterized in that, In the preparation of all-solid-state lithium batteries, the electrolyte intermediate layer used is a glassy sulfide solid electrolyte material with high lithium iodide content, the positive electrode material used is NCM ternary material, lithium cobalt oxide or sulfur, and the negative electrode used is a metallic lithium negative electrode.