High-entropy solid electrolyte membrane and preparation method and application thereof

Abstract

The invention discloses a high-entropy solid electrolyte membrane and a preparation method and application thereof, the high-entropy solid electrolyte membrane is composed of a high-entropy compound, the high-entropy compound comprises at least five transition metal cations, the mole of each group of transition metal cations is 0.05-0.15, and the high-entropy compound further comprises F <-> and / or N < 3->. According to the invention, five or more transition metals are introduced for the first time to construct the high-entropy solid electrolyte membrane, and the mechanical strength, chemical stability and lithium ion migration ability of the membrane layer are improved through a multi-element structure, a lattice distortion effect and an anion synergistic effect.

Description

Technical Field

[0001] This invention relates to the field of battery technology, specifically to a high-entropy solid electrolyte membrane, its preparation method, and its application. Background Technology

[0002] Lithium metal is known for its extremely high theoretical specific capacity (3860 mAh g). -1 With its extremely low electrochemical potential (-3.04 V vs. SHE), it is considered one of the most ideal anode materials. However, it is prone to dendrite growth, interfacial instability, and severe side reactions in a liquid electrolyte environment, which seriously limits its cycle life and safety. Therefore, constructing a stable, dense, uniform, and highly ionicly conductive solid-state electrolyte interface (SEI) film is a key means to solve the above problems. Existing SEI materials are mainly single-component systems such as LiF, Li3N, and LiSe. These single-component SEIs cannot simultaneously meet the requirements of high mechanical strength, high ionic conductivity, and high chemical stability.

[0003] High-entropy materials (HEMs) are a new type of material formed by introducing five or more main components with similar molar ratios. They possess unique properties such as "high-entropy effect, strong lattice distortion, and multi-component synergistic effect." These properties give high-entropy structures significant advantages in mechanical properties, thermal stability, and interfacial stability, making them an important development direction in the field of materials science in recent years.

[0004] Based on the above characteristics, high-entropy SEI is expected to simultaneously resolve the contradiction between mechanical strength, interface stability and ionic conductivity that existing SEIs struggle to balance, and achieve significant and unpredictable synergistic performance improvements.

[0005] In addition, the SEI film on the lithium anode in existing batteries is mainly formed during battery cycling. In order to improve the performance of the SEI film, existing technologies also add some additives (such as LiNO3) to the electrolyte to promote the formation of nitrides, which are reduced to generate substances such as Li3N, thereby improving the stability of the SEI film to a certain extent and inhibiting polysulfide shuttle.

[0006] Therefore, forming a high-entropy SEI film on the lithium anode in advance to protect it has become one of the key research and development priorities. Summary of the Invention

[0007] To address the issue that existing SEI membranes cannot simultaneously meet the requirements of high mechanical strength, high ionic conductivity, and high chemical stability with a single component, and that existing SEI membranes are mainly formed during battery cycling, one objective of this invention is to provide a high-entropy solid electrolyte membrane.

[0008] The technical solution of this invention to solve the above-mentioned technical problems is as follows: A high-entropy solid electrolyte membrane is provided, which is composed of a high-entropy compound, including transition metal cations, at least five kinds of transition metal cations, with each group of transition metal cations having a molar ratio of 0.05-0.15, and also including F... - and / or N 3- .

[0009] In this embodiment, at least five transition metal cations form a high-entropy structure through a near equimolar ratio of multiple components. The cations are uniformly distributed at the atomic scale in the crystal lattice, achieving high structural stability and high mechanical strength. Furthermore, the high-entropy structure in this application is related to the anion (F... - and / or N 3- Together, they form high-entropy compounds, among which fluorides (F) are formed. - Substances formed with transition metal cations possess good mechanical properties and provide some protection to crystals; nitrides (N 3- Compounds formed with transition metal cations improve the electronic and ionic conductivity of high-entropy solid electrolyte membranes, thereby constructing multiple ion migration channels; thus enabling the formed high-entropy SEI membrane to simultaneously possess high strength, high toughness, and high Li⁺ migration rate, thereby enhancing interface stability and cycle life.

[0010] Furthermore, the transition metal cation is selected from at least five cations of the elements Ni, Fe, Mn, Cu, Co, Cr, Mo, and V.

[0011] In the embodiments of this application, the atomic radii of Ni, Fe, Mn, Cu, Co, Cr, Mo and V are relatively close, thereby avoiding excessive lattice distortion that could damage the structure of the membrane and enhancing the strength of the high-entropy solid electrolyte membrane to a certain extent.

[0012] Furthermore, the transition metal cation is selected from Ni. 2+ Co 2+ Cu 2+ Fe 3+ Mn 4+ Mo 5+ and Cr 3+ At least 5 of them; High-entropy compounds include F - and N 3- At that time, F - and N 3- The molar ratio is 4~5:5~6.

[0013] In this embodiment of the application, F - and N 3-It can form fluorides and nitrides with transition metal cations, respectively, ensuring that the formed high-entropy solid electrolyte membrane has good mechanical properties, preventing dendrites from penetrating the membrane, and providing a certain degree of protection for the lithium anode, thereby improving the cycle performance of the battery. Meanwhile, the nitrides ensure that the membrane in this application has good electronic and ionic conductivity, improving the membrane's interfacial properties.

[0014] In the embodiments of this application, F - and N 3- When the molar ratio is 4~5:5~6, F - and N 3- The two work synergistically to ensure that the formed membrane has both good mechanical properties and good interfacial properties, so as to obtain a high-entropy solid electrolyte membrane with optimal comprehensive mechanical-chemical-electrochemical properties.

[0015] Furthermore, the thickness of the high-entropy solid electrolyte membrane is 10-50 nm.

[0016] In the embodiments of this application, the thickness of the film avoids the problem that the film is too thin and easily pierced by the generated dendrites, while also avoiding the problem that the film is too thick and affects ion transport.

[0017] A second objective of this invention is to provide a method for preparing a high-entropy solid electrolyte membrane, comprising the following steps: Step 1: Place the lithium sheet in the reaction zone of the PECVD system under an inert atmosphere, place the transition metal source in the heating zone of the PECVD system, and then add substance A, which provides a nitrogen source and / or a fluorine source, into the PECVD system. Step 2: After heating the heating zone to the heating temperature under vacuum conditions, start the PECVD system to carry out plasma reaction, where transition metal cations react with F. - and / or N 3- A high-entropy compound is formed on the lithium surface through a reaction, constituting a high-entropy solid electrolyte membrane. The transition metal source includes at least five transition metal salts.

[0018] In this embodiment, lithium sheets and multi-component transition metal salts are placed in a PECVD system under an inert atmosphere. Radio frequency plasma excites the multi-component metal source and nitrogen / fluorine source to react, allowing various cations to react with F... - / N 3- Anions are co-deposited on the lithium metal surface to form a high-entropy compound, thereby forming a uniform and dense high-entropy solid electrolyte film in situ. Furthermore, the method in this application features low deposition temperature and high film uniformity, effectively avoiding lithium sheet melting or interface damage, and achieving rapid construction of high-quality films. Preferably, the inert atmosphere in this embodiment is an argon atmosphere.

[0019] Furthermore, the PECVD system includes a quartz tube, which includes a heating zone and a reaction zone, a high-temperature heating jacket covering the quartz tube and located in the heating zone, a first electrode and a second electrode fitted on the quartz tube and separated by the heating zone and the reaction zone, a radio frequency power supply electrically connected to both the first electrode and the second electrode, and gas valves located at both ends of the quartz tube for sealing the quartz tube.

[0020] Furthermore, in step 1, the transition metal source is selected from at least 5 of the following: NiCl2, CoCl2, CuCl2, FeCl3, MnCl4, MoCl5, and CrCl3; When substance A is in a solid state, substance A is placed in the heating zone; When substance A is in a gaseous state, it is directly introduced into the quartz tube.

[0021] Furthermore, substance A can be any one of high-purity N2, PVDF powder, and NH4F solid.

[0022] Furthermore, in step 2, the heating temperature is 100~300℃, and the conditions for plasma reaction in the PECVD system are: 200~300W reaction for 3~5min.

[0023] A third objective of this invention is to provide a battery comprising a lithium metal anode and a high-entropy solid electrolyte membrane located on the lithium metal anode, wherein the high-entropy solid electrolyte membrane is derived from one of the objectives.

[0024] The present invention has the following beneficial effects: This invention introduces five or more transition metals with F for the first time. - and / or N 3- High-entropy compounds were constructed to form high-entropy solid electrolyte membranes. Through the synergistic effect of multi-component structures, lattice distortion effects, and mixed anion frameworks, the mechanical strength, chemical stability, and lithium-ion migration ability of the membrane were improved.

[0025] Secondly, the high-entropy structure in the high-entropy solid electrolyte membrane improves mechanical strength. According to the subsequent battery cycle performance test analysis, the cycle time of the traditional Li@LiF membrane is about 900 hours, while the cycle time of the Li@HEF membrane prepared in this application is about 2600 hours. It can be reasonably inferred that the mechanical properties of the Li@HEF membrane in this application are more than doubled compared with the traditional Li@LiF membrane.

[0026] Furthermore, the membrane in this application also forms multiple ion migration channels, significantly reducing interfacial impedance and improving Li... + Migration rate; the hybrid anionic framework enhances the interface's corrosion resistance and effectively suppresses dendrite growth, significantly improving battery cycle performance.

[0027] Furthermore, the preparation method in this invention ensures controllable film thickness and a dense structure. Simultaneous deposition and solid solution construction via low-temperature PECVD results in film uniformity and interface stability significantly superior to traditional SEIs such as LiF and LiSe. The synergistic effect of these structural effects enables high-entropy SEIs to exhibit comprehensive performance far exceeding that of single-component fast films in terms of cycle life, interfacial impedance, and stability, demonstrating extremely high innovation and application value. Attached Figure Description

[0028] Figure 1 This is a schematic diagram of the PECVD system. Figure 2 SEM and EDS images of the Li@HEF membrane; Figure 3 SEM and EDS images of the Li@HEN membrane; Figure 4 SEM and EDS images of the Li@HENF membrane Figure 5 The rate performance diagrams for symmetrical cells with Li@LiF and Li@HEF films are shown. Figure 6 The cycling performance of symmetrical cells with Li@LiF and Li@HEF films is shown. Explanation of reference numerals in the attached figures: 1. Quartz tube, 1-1-Heating zone, 1-2. Reaction zone; 2. High-temperature heating jacket; 3. First electrode; 4. Second electrode; 5. Radio frequency power supply; 6. Gas valve. Detailed Implementation

[0029] The following describes a high-entropy solid electrolyte membrane, its preparation method, and its application, with reference to embodiments.

[0030] However, this application may be exemplified in many different forms and should not be construed as limited to the specific embodiments set forth herein. Rather, these embodiments are provided so that this application will be thorough and complete and will fully convey the scope of this application to those skilled in the art.

[0031] Example 1 A PECVD system, such as Figure 1 As shown, the PECVD system includes a quartz tube 1, a high-temperature heating jacket 2, a first electrode 3, a second electrode 4, an RF power supply 5, and a gas valve 6.

[0032] like Figure 1As shown, the quartz tube 1 includes a heating zone 1-1 and a reaction zone 1-2. A high-temperature heating sleeve 2 is fitted onto the outer wall of the quartz tube 1 and located in the heating zone 1-1. A first electrode 3 and a second electrode 4 are fitted onto the outer wall of the quartz tube 1 and separated by the heating zone 1-1 and the reaction zone 1-2. The first electrode 3 is closer to the end of the heating zone 1-1 and farther from the reaction zone 1-2, and the second electrode 4 is closer to the end of the reaction zone 1-2 and farther from the heating zone 1-1. The radio frequency power supply 5 is electrically connected to the first electrode 3 and the second electrode 4, thereby forming a radio frequency region in the area of ​​the quartz tube 1 between the first electrode 3 and the second electrode 4, while the heating zone 1-1 and the reaction zone 1-2 are located in the radio frequency region. Gas valves 6 are located at both ends of the quartz tube to prevent gaseous substances in the quartz tube from escaping during the PECVD system reaction.

[0033] Example 2 A method for preparing a high-entropy solid electrolyte membrane, wherein the high-entropy solid electrolyte membrane in this embodiment is prepared using the PECVD system in Example 1, specifically including the following steps: Step 1: Under an argon atmosphere, place a 15 mm diameter lithium sheet into the reaction zone of a quartz tube. Add a mixed salt consisting of NiCl2, CoCl2, CuCl2, FeCl3, and MnCl4 to the heating zone. The mass of each component salt in the mixed salt is 100 mg. At the same time, place 200 mg of substance A, which is PVDF (polyvinylidene fluoride) powder, in the heating zone as a fluorine source.

[0034] Step 2: After the quartz tube is evacuated, the heating zone is heated to 200 °C and the radio frequency power supply is turned on to initiate the plasma reaction. The plasma reaction conditions are: 500 W for 5 min. After the radio frequency power supply is turned on, the active material generated by PVDF decomposition reacts with transition metal ions on the lithium anode surface to form a high-entropy compound. The high-entropy compound is uniformly loaded on the lithium anode surface, eventually forming a uniform high-entropy fluoride film (Li@HEF) on the lithium anode surface.

[0035] Example 3 A method for preparing a high-entropy solid electrolyte membrane, wherein the high-entropy solid electrolyte membrane in this embodiment is prepared using the PECVD system in Example 1, specifically including the following steps: Step 1: Under an argon atmosphere, place a 15 mm diameter lithium sheet into the reaction zone of a quartz tube. Add a mixed salt consisting of NiCl2, CoCl2, CuCl2, FeCl3, and MoCl5 to the heating zone. The mass of each component salt in the mixed salt is 100 mg.

[0036] Step 2: After evacuating the quartz tube to a vacuum, heat the heating zone to 150 °C. Introduce substance A (N2, flow rate 30 sccm) into the quartz tube and turn on the radio frequency power supply to initiate the plasma reaction. The plasma reaction conditions are: 400W for 4 minutes. After starting the radio frequency power supply, nitrogen gas generates active N2 under plasma excitation. + / N2 + The high-entropy compound reacts with transition metal ions on the surface of the lithium anode to form a high-entropy compound. The high-entropy compound is uniformly loaded on the surface of the lithium anode, and finally a uniform high-entropy nitride film (Li@HEN) is formed on the surface of the lithium anode.

[0037] Example 4 A method for preparing a high-entropy solid electrolyte membrane, wherein the high-entropy solid electrolyte membrane in this embodiment is prepared using the PECVD system in Example 1, specifically including the following steps: Step 1: Under an argon atmosphere, a 15 mm diameter lithium sheet is placed into the reaction zone of a quartz tube. A mixed salt consisting of NiCl2, CrCl3, CuCl2, FeCl3, and MnCl4 is added to the heating zone. The mass of each component salt in the mixed salt is 100 mg. At the same time, 200 mg of substance A, which is NH4F (ammonium fluoride) powder, is placed in the heating zone as a fluorine source and a nitrogen source.

[0038] Step 2: After the quartz tube is evacuated, the heating zone is heated to 150 °C and the radio frequency power supply is turned on to initiate the plasma reaction. The plasma reaction conditions are: 400 W for 4 min. After the radio frequency power supply is turned on, the active material generated by the decomposition of NH4F reacts with transition metal ions on the lithium anode surface to form a high-entropy compound. The high-entropy compound is uniformly loaded on the lithium anode surface, ultimately forming a uniform high-entropy fluoride / nitride solid electrolyte film (Li@HEFN) on the lithium anode surface.

[0039] Comparative Example 1 A method for preparing a solid electrolyte membrane, wherein the solid electrolyte membrane in this embodiment is prepared using the PECVD system described in Example 1, specifically including the following steps: Step 1: Under an argon atmosphere, place a 15 mm diameter lithium sheet into the reaction zone of a quartz tube, and place 50 mg of PVDF powder in the heating zone of the quartz tube as a fluorine source.

[0040] Step 2: After the quartz tube is evacuated to a vacuum, the heating zone is heated to 200°C and the radio frequency power supply is turned on to carry out the plasma reaction. The plasma reaction conditions are: 200 W for 2 min. After the radio frequency power supply is turned on, the active material generated by the decomposition of PVDF is deposited on the surface of the lithium anode to form a LiF film (Li@LiF).

[0041] Comparative Example 2 A method for preparing a solid electrolyte membrane, wherein the solid electrolyte membrane in this embodiment is prepared using the PECVD system described in Example 1, specifically including the following steps: Step 1: Under an argon atmosphere, place a 15 mm diameter lithium sheet into the reaction zone of the quartz tube, and place 100 mg of selenium powder into the heating zone of the quartz tube.

[0042] Step 2: After the quartz tube is evacuated to a vacuum, the heating zone is heated to 200°C to evaporate and generate Se active species. The radio frequency power supply is then turned on to carry out the plasma reaction. The plasma reaction conditions are: 200 W for 2 min. After the radio frequency power supply is turned on, the active substances generated by the decomposition of selenium powder are deposited on the surface of the lithium anode to form a LiSe film (Li@LiSe).

[0043] Test Analysis: 1. Structural Analysis The Li@HEF film prepared in Example 2, the Li@HEN film prepared in Example 3, and the Li@HEFN film prepared in Example 4 were analyzed by SEM and EDS, respectively. The results are detailed in [link to relevant documentation]. Figure 2 , Figure 3 and Figure 4 ;in, Figure 2 SEM and EDS images of the Li@HEF membrane; Figure 3 SEM and EDS images of the Li@HEN membrane; Figure 4 The images show the SEM and EDS images of the Li@HENF membrane.

[0044] from Figures 2-4 It can be seen that the high-entropy solid electrolyte membrane prepared in this application contains various metal cations, F... - and N 3- The anions are uniformly distributed within the film layer, and no element enrichment or phase separation occurs, proving that the PECVD technology provided in this application can stably construct high-entropy structures.

[0045] 2. Performance Analysis Electrochemical tests were conducted on symmetrical cells composed of lithium electrodes loaded with solid electrolyte membranes prepared in the examples and comparative examples at 25°C ± 2°C. The rate performance test conditions were 1 mA cm⁻¹. -2 1mAh cm -2 2mA cm -2 2mAh cm -2 3mA cm -2 3mAh cm -2 and 5mA cm -2 5mAh cm -2 Cyclic performance test conditions: 1 mA cm -21mAhcm -2 The test curve is as follows: Figure 5 , 6 As shown in Table 1, the results of the rate performance test are shown in Table 2, and the results of the cycle performance test are shown in Table 2.

[0046] Table 1. Rate Performance Table 2. Cyclic Performance As can be seen from Table 1, based on the rate performance of Examples 2-4 and Comparative Examples 1 and 2, the high-entropy solid electrolyte membrane prepared in this application maintains low polarization even at high current densities, and its lithium-ion transport is significantly faster than that of the comparative LiF and LiSe membranes. This is due to the presence of multiple Li-ion sites. + The improved interfacial conductivity is due to the migration channels and the mixed anion framework.

[0047] As can be seen from Table 2, the cycling performance of Examples 2-4 and Comparative Examples 1 and 2 shows that the lithium sheet covered by the high-entropy solid electrolyte membrane prepared in this application can maintain a stable voltage plateau for a long time without instability or a sharp increase in polarization. In contrast, Comparative Examples 1 and 2 both failed in the early stage. This indicates that the lattice distortion and solid solution strengthening brought about by the high-entropy solid solution structure significantly improve the mechanical strength of the membrane and effectively suppress interface cracking and dendrite penetration.

[0048] At the same time, in conjunction with Table 1, Table 2 and Figure 5 and Figure 6 It can be seen that the high-entropy solid electrolyte membrane in this application has achieved significant improvements in structural uniformity, ion migration capability and cycle stability, demonstrating a synergistic enhancement effect that is difficult to achieve with traditional SEI (LiF, LiSe membranes).

[0049] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A high-entropy solid electrolyte membrane, characterized in that, The high-entropy solid electrolyte membrane is composed of a high-entropy compound, which includes transition metal cations, at least five of which are present, with each group containing 0.05-0.15 molar amounts of the transition metal cations. It also includes F... - and / or N 3- .

2. The high-entropy solid electrolyte membrane according to claim 1, characterized in that, The transition metal cation is selected from at least five cations selected from the elements Ni, Fe, Mn, Cu, Co, Cr, Mo, and V.

3. The high-entropy solid electrolyte membrane according to claim 2, characterized in that, The transition metal cation is selected from Ni. 2 + Co 2+ Cu 2+ Fe 3+ Mn 4+ Mo 5+ and Cr 3+ At least 5 of them; The high-entropy compound includes F. - and N 3- At that time, the F - and N 3- The molar ratio is 4~5:5~6.

4. The high-entropy solid electrolyte membrane according to claim 3, characterized in that, The thickness of the high-entropy solid electrolyte membrane is 10-50 nm.

5. The method for preparing the high-entropy solid electrolyte membrane according to any one of claims 1 to 4, characterized in that, Includes the following steps: Step 1: Place the lithium sheet in the reaction zone of the PECVD system under an inert atmosphere, place the transition metal source in the heating zone of the PECVD system, and then add substance A, which provides a nitrogen source and / or a fluorine source, into the PECVD system. Step 2: After heating the heating zone to the heating temperature under vacuum conditions, start the PECVD system to carry out plasma reaction, where transition metal cations react with F. - and / or N 3- A high-entropy compound is formed on the lithium surface through a reaction, constituting a high-entropy solid electrolyte membrane. The transition metal source includes at least five transition metal salts.

6. The preparation method according to claim 5, characterized in that, The PECVD system includes a quartz tube, which includes a heating zone and a reaction zone, a high-temperature heating jacket covering the outer shell of the quartz tube and located in the heating zone, a first electrode and a second electrode sleeved on the quartz tube and separated by the heating zone and the reaction zone, a radio frequency power supply electrically connected to both the first electrode and the second electrode, and gas valves located at both ends of the quartz tube for sealing the quartz tube.

7. The preparation method according to claim 5, characterized in that, In step 1, the transition metal source is selected from at least 5 of the following: NiCl2, CoCl2, CuCl2, FeCl3, MnCl4, MoCl5, and CrCl3; When substance A is in a solid state, substance A is placed in the heating zone; When substance A is in a gaseous state, substance A is directly introduced into the quartz tube.

8. The preparation method according to claim 7, characterized in that, The substance A is any one of high-purity N2, PVDF powder, and NH4F solid.

9. The preparation method according to claim 8, characterized in that, In step 2, the heating temperature is 100~300℃, and the conditions for plasma reaction in the PECVD system are: 200~300W reaction for 3~5min.

10. A battery, characterized in that, It includes a lithium metal anode and a high-entropy solid electrolyte membrane as described in any one of claims 1 to 4 located on the lithium metal anode.

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