A lithium-sulfur battery diaphragm modified by a bimetallic nanoparticle catalytic material and a preparation method and application thereof
By introducing a RuNi bimetallic nanoparticle catalytic layer onto the lithium-sulfur battery separator, the problem of insufficient barrier capacity of traditional separators against polysulfides is solved, achieving efficient adsorption and catalytic conversion of polysulfides and improving the cycle stability and electrochemical performance of the battery.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- NANTONG UNIV
- Filing Date
- 2026-03-26
- Publication Date
- 2026-07-14
AI Technical Summary
In existing lithium-sulfur batteries, traditional PP separators have large pore sizes and lack polar groups, making it difficult to effectively suppress the diffusion of polysulfides across the membrane. This results in low coulombic efficiency, rapid capacity decay, and poor cycle stability. The chemical adsorption capacity of a single carbon material modification layer for polysulfides is limited, and it cannot suppress lithium dendrite growth and side reactions.
By modifying the membrane with RuNi bimetallic nanoparticle catalytic material, a RuNi bimetallic nanoparticle catalytic layer is formed on the surface of the Celgard 2500 membrane, which enables efficient adsorption and catalytic conversion of polysulfides, promotes lithium-ion transport, and inhibits lithium dendrite growth.
It significantly improves the cycle stability and reversible specific capacity of lithium-sulfur batteries, enhances electrochemical reaction kinetics and rate performance, extends battery life, and has a simple preparation process that is easy to scale up for production.
Smart Images
Figure CN122393550A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of lithium-sulfur battery material technology, specifically relating to a lithium-sulfur battery separator modified with bimetallic nanoparticle catalytic material, its preparation method, and its application. Background Technology
[0002] Lithium-sulfur batteries, with their theoretical specific capacity of up to 1675 mAh / g and theoretical energy density of approximately 2600 Wh / kg, are considered important candidates for next-generation high-energy-density energy storage systems. Furthermore, the abundance, low cost, and environmental friendliness of sulfur resources make lithium-sulfur batteries a promising candidate for replacing traditional lithium-ion batteries in portable electronic devices, electric vehicles, and large-scale energy storage. However, lithium-sulfur batteries still face several key technological bottlenecks in practical applications, the most significant of which is the lithium polysulfide (Li₂S₃) barrier. n The "shuttle effect" caused by the dissolution and diffusion of lithium metal (4≤n≤8) in the electrolyte, and the growth of lithium dendrites caused by uneven deposition on the surface of lithium metal anode.
[0003] The aforementioned problems directly cause irreversible loss of the battery's active material (sulfur), triggering a series of side reactions between the lithium metal anode, electrolyte, and polysulfides. This leads to a decrease in battery coulombic efficiency, rapid capacity decay, and a significant reduction in cycle stability, severely hindering the industrial application of lithium-sulfur batteries.
[0004] Membrane modification is considered an effective strategy to simultaneously address the "shuttle effect" and lithium dendrite problems. In lithium-sulfur battery systems, the separator not only acts as a physical barrier to effectively separate the positive and negative electrodes and prevent short circuits, but also regulates the rapid and uniform transport of lithium ions and blocks the migration of soluble polysulfide intermediates. However, traditional polypropylene (PP) separators (such as Celgard 2500) have large pore sizes (typically 0.1~1 μm) and lack polar groups on their surface, resulting in limited ability to block and adsorb polysulfides, making it difficult to effectively suppress their transmembrane diffusion.
[0005] To address this issue, researchers have introduced various functional intermediate layers to modify the separator, such as carbon-based modification layers (e.g., carbon nanotubes (CNTs), graphene, Super P, etc.). These layers leverage the high specific surface area and porous structure of carbon materials to enhance the physical confinement of polysulfides within the separator. However, due to the inherent non-polarity of carbon materials, their chemisorption capacity for polar polysulfides is limited, making it difficult to fundamentally suppress the shuttle effect and maintain the long-term cycle stability of the battery. Therefore, developing a functionalized separator material that is structurally stable, has a simple fabrication process, is cost-controllable, and can simultaneously and effectively suppress polysulfide shuttle and lithium dendrite growth is of significant theoretical and engineering value for promoting the practical application of lithium-sulfur batteries. Summary of the Invention
[0006] Technical problems solved: To address the above-mentioned technical problems, this invention provides a lithium-sulfur battery separator modified with bimetallic nanoparticle catalytic material, its preparation method, and its application. This invention effectively solves the problems of low coulombic efficiency, rapid capacity decay, and poor cycle stability in existing lithium-sulfur batteries using traditional PP separators; the large and unevenly distributed pore size of traditional separators, which cannot effectively suppress the transmembrane diffusion of polysulfides; and the weak chemical adsorption capacity of existing separator modification materials (such as single carbon materials) for polysulfides, which lack catalytic conversion and are difficult to suppress the occurrence of lithium-sulfur side reactions, thus failing to achieve long-term stable cycle operation of the battery.
[0007] Technical solution: In a first aspect, the present invention provides a method for preparing a lithium-sulfur battery separator modified with a bimetallic nanoparticle catalytic material, comprising the following steps: S1, Ru3(CO) 12 Add Ni(acac)2, L-ascorbic acid, polyvinylpyrrolidone (PVP), and ethylene glycol (EG) sequentially to the vial, ensuring that the reagents are in full contact; S2. After tightening the cap, place the mixture in an ultrasonic cleaner and ultrasonically treat it for 15 minutes until a homogeneous mixture is formed. S3. The obtained homogeneous mixture was heated at a constant temperature of 180 °C for 5 h. After the reaction was completed, it was naturally cooled to room temperature to obtain a suspension containing RuNi bimetallic nanoparticles. S4. Place the above suspension in a centrifuge, collect RuNi nanoparticles by centrifugation, wash three times with a mixture of acetone / ethanol (volume ratio of 1:1), and then vacuum dry for later use. S5. Mix RuNi nanoparticles, Super P and binder LA133 in a mass ratio of 7:2:1 and stir evenly to obtain slurry A; S6. Using a 60 μm scraper, slurry A is uniformly coated onto the surface of the Celgard 2500 separator. After coating, the separator is placed in a vacuum drying oven and heated at a constant temperature of 60 °C for 10-12 h to completely remove the solvent. Finally, a lithium-sulfur battery separator modified with RuNi bimetallic nanoparticle catalyst material is obtained.
[0008] Preferably, in step S1, Ru3(CO) 12 The dosage is 5.4 mg, Ni(acac)2 is 6 mg, L-ascorbic acid is 54.6 mg, PVP is 40 mg and ethylene glycol is 10 mL.
[0009] In a second aspect, the present invention provides a lithium-sulfur battery separator modified with a bimetallic nanoparticle catalytic material, which is prepared by the preparation method described in the first aspect.
[0010] Thirdly, the present invention provides a lithium-sulfur battery, wherein the lithium-sulfur battery comprises a lithium-sulfur battery separator modified with the bimetallic nanoparticle catalytic material described in the second aspect.
[0011] Preferably, the lithium-sulfur battery further includes a positive electrode, a negative electrode, and an electrolyte, and the assembly of the lithium-sulfur battery is completed under argon protection.
[0012] Furthermore, the method for preparing the positive electrode sheet is as follows: (1) Take 7 parts of sublimed sulfur, 2 parts of conductive carbon black and 1 part of binder according to the mass ratio, grind and stir at 75 rpm for 6 h, and make a slurry after thorough mixing; the binder is composed of polyvinylidene fluoride and N-methylpyrrolidone, wherein the ratio of polyvinylidene fluoride to N-methylpyrrolidone is 0.75 g: 30 mL; (2) The slurry is uniformly coated on the clean aluminum foil current collector surface by scraper coating method. Then the aluminum foil is transferred to a vacuum drying oven and dried at 60 °C for 10 h. The dried aluminum foil is cut into small round pieces with a diameter of 16 mm using a precision punching die. These round pieces are the positive electrode plates.
[0013] Furthermore, the negative electrode is a commercially available lithium metal sheet.
[0014] Furthermore, the electrolyte is a mixed solution obtained by mixing DOL (1,3-dioxolane) and DME (dimethoxyethane) in a volume ratio of 1:1, and 0.1 M LiNO3 and 1 M LiTFSI (lithium bis(trifluoromethanesulfonyl)imide) are added to the mixed solution, wherein LiNO3 is used as an additive to inhibit lithium dendrite growth and reduce side reactions.
[0015] Furthermore, under argon protection, H2O < 0.1 ppm and O2 < 0.1 ppm.
[0016] Beneficial effects: 1) Synergistic suppression of shuttle effect and improvement of cycle stability: This application introduces RuNi bimetallic nanoparticle catalytic layer on the surface of Celgard 2500 membrane, which can simultaneously achieve efficient adsorption and catalytic conversion of polysulfides, effectively slow down the transmembrane diffusion of polysulfides, reduce the loss of active materials, and significantly improve the cycle stability and reversible specific capacity of lithium-sulfur battery. 2) Bimetallic synergistic effect, accelerating reaction kinetics: In the prepared RuNi bimetallic nanoparticle modified membrane, Ru and Ni metal sites form a synergistic effect. Ni sites exhibit strong chemisorption capacity for polysulfides, rapidly capturing soluble polysulfides in the electrolyte; while Ru sites possess excellent catalytic activity, catalyzing the redox reaction of polysulfides and accelerating the reaction of sulfur species (S8→Li2S). n The conversion process of →Li2S significantly improves the electrochemical reaction kinetics of the battery; 3) Optimize lithium-ion transport and improve rate performance: RuNi nanoparticles have a high specific surface area and abundant metal active sites, which can construct a catalytically active functional layer on the membrane surface, promote the nucleation and decomposition of Li2S, reduce the reaction energy barrier, and at the same time do not hinder the rapid transport of lithium ions, thereby improving the rate performance of lithium-sulfur batteries and reducing polarization. 4) The preparation process is simple and easy to scale up: The preparation method of this application does not require complex equipment and harsh reaction conditions. The steps are simple and easy to operate. The cost of the reagents used is controllable. Moreover, the modified separator is compatible with the existing lithium-sulfur battery assembly process, which is convenient for large-scale industrial production and application. 5) Stable structure and long service life: RuNi bimetallic nanoparticles are tightly bonded to the Celgard 2500 substrate through a binder, the catalyst layer is not easy to fall off, and the bimetallic nanoparticles themselves have good chemical stability, which can maintain the functional characteristics of the separator for a long time and extend the service life of the battery. Attached Figure Description
[0017] Figure 1 The graph shows a comparison of the cycle performance of the lithium-sulfur battery with RuNi bimetallic nanoparticle-modified separator in Example 1 at a rate of 0.5C. Figure 2 This is a comparative test diagram of the symmetrical cell of the lithium-sulfur battery with RuNi bimetallic nanoparticle-modified separator in Example 1. Detailed Implementation
[0018] The present invention will be described in detail below with reference to specific embodiments: Example 1
[0019] A method for preparing a lithium-sulfur battery separator modified with bimetallic nanoparticle catalytic material, the specific steps of which are as follows: S1, 5.4 mg Ru3(CO) 12 6 mg Ni(acac)2, 54.6 mg L-ascorbic acid, 40 mg PVP and 10 mL EG were added sequentially to a 35 mL vial to obtain a mixture; S2. After tightening the bottle cap, place the mixture in an ultrasonic cleaner and ultrasonically treat it for 15 minutes to obtain a homogeneous mixture. S3. The obtained homogeneous mixture is transferred to an oven and heated at 180 °C for 5 h. Then it is naturally cooled to room temperature to obtain a suspension containing RuNi bimetallic nanoparticles. S4. Place the suspension in a centrifuge, centrifuge to collect RuNi nanoparticles, wash three times with an acetone / ethanol mixture (volume ratio 1:1), and vacuum dry for later use. S5. Mix RuNi nanoparticles, Super P and binder LA133 in a mass ratio of 7:2:1 and stir until homogeneous to obtain a uniform slurry A; S6. Using a 60 μm scraper, slurry A is uniformly coated on the surface of the Celgard 2500 separator, and then placed in a vacuum drying oven and heated at 60 °C for 11 h to finally obtain a lithium-sulfur battery separator modified with RuNi bimetallic nanoparticle catalyst material.
[0020] The specific process for preparing lithium-sulfur batteries using the above-mentioned separator is as follows: The aforementioned lithium-sulfur battery is prepared in an argon protective atmosphere (H2O < 0.1 ppm, O2 < 0.1 ppm) by a positive electrode, a lithium-sulfur battery separator modified with the aforementioned RuNi bimetallic nanoparticle catalytic material, a negative electrode, and an electrolyte.
[0021] The method for preparing the positive electrode sheet is as follows: (1) Weigh 7 parts of sublimed sulfur, 2 parts of conductive carbon black and 1 part of binder (0.75 g PVDF dissolved in 30 mL NMP) according to the mass fraction, grind and stir at 75 rpm for 6 h, and mix thoroughly to make a slurry; (2) Use a 60 μm scraper to evenly coat the slurry onto the clean aluminum foil current collector surface, then transfer the aluminum foil to a vacuum drying oven and dry it at 60 °C for 10 h. Use a precision punching die to cut the dried aluminum foil into small round pieces with a diameter of 16 mm. These round pieces are the positive electrode plates. The above negative electrode is a commercial lithium metal sheet (120 μm thick, 15 mm in diameter). Before use, the surface should be wiped with anhydrous ethanol to remove the oxide layer. The electrolyte is a mixed solution obtained by mixing DOL and DME at a volume ratio of 1:1, with 0.1 M LiNO3 and 1 M LiTFSI added to the mixed solution.
[0022] After the battery is assembled, it is left to stand for 12 hours. The assembled battery is then tested for long-cycle electrochemical performance on a battery test cabinet (Neware BTS 7.6.0).
[0023] Comparative Example 1 Using the same positive electrode sheet prepared in Example 1, an unmodified Celgard 2500 separator, and a commercial lithium metal sheet as the negative electrode, along with the same electrolyte as in Example 1, the battery was assembled in the same argon protective atmosphere. After assembly, the battery was allowed to stand for 12 hours, and its electrochemical performance was tested under the same test conditions as in Example 1.
[0024] Comparative Example 2 The positive electrode sheet prepared in the same way as in Example 1, the Super P modified Celgard 2500 separator, the commercial lithium metal sheet as the negative electrode, and the electrolyte as in Example 1 were used to assemble the battery in the same argon protective atmosphere. After assembly, the battery was left to stand for 12 hours and then the electrochemical performance was tested under the same test conditions as in Example 1.
[0025] Test Method: The lithium-sulfur battery's constant current charge-discharge performance was tested using a charge-discharge instrument from Shenzhen Xinwei Co., Ltd. The test environment temperature was 25°C, the charge-discharge voltage cutoff range was 1.7–2.8 V, and the set charge-discharge current was 0.5 C. The initial capacity was the specific capacity at the first discharge, and the termination capacity was the specific capacity at the previous discharge when the battery could no longer charge or discharge normally. Cycle Count: Each charge-discharge cycle is considered one cycle. The lithium-sulfur battery is considered to have reached the end of its life when it cannot complete a single charge-discharge cycle, or when its capacity drops by more than 50% within 5 cycles. This rapid capacity drop usually indicates severe internal side reactions or rapid structural deterioration, leading to a sharp decline in battery performance and rendering it unable to meet practical application requirements. This rigorous standard allows for accurate determination of the lithium-sulfur battery's lifespan. The results are shown in Table 1. Table 1. Performance comparison of lithium-sulfur batteries prepared using different separators in Example 1, Comparative Examples 1 and 2 after 200 cycles at 0.5C rate.
[0026] Compared to the lithium-sulfur battery using Celgard 2500 as the separator in Comparative Example 1 and the lithium-sulfur battery using Super P-modified Celgard 2500 as the separator in Comparative Example 2, the separator modified with Ru-Ni bimetallic nanoparticles exhibits superior electrochemical performance. The initial discharge specific capacity of the lithium-sulfur battery with the Ru-Ni bimetallic separator reaches 903 mAh / g, comparable to the Celgard 2500 separator system, indicating that the introduction of bimetallic materials does not reduce the initial capacity of the battery. Simultaneously, the Ru-Ni bimetallic nanoparticles form a catalytically active functional layer on the separator surface, enabling the separator to simultaneously possess polysulfide adsorption and catalytic conversion capabilities. This reduces the diffusion and migration of polysulfides in the electrolyte, minimizes side reactions, and accelerates the redox reaction process of sulfur species, thereby improving the coulombic efficiency and reaction kinetics of the lithium-sulfur battery. In terms of long-cycle performance, the lithium-sulfur battery using a Ru-Ni bimetallic modified separator maintained a discharge specific capacity of 750 mAh / g after 200 cycles, with a capacity retention of 83%. In contrast, Comparative Example 1 battery only achieved a capacity of 384 mAh / g under the same cycling conditions, with a capacity retention of 50.7%; Comparative Example 2 battery only achieved a capacity of 498 mAh / g under the same cycling conditions, with a capacity retention of 60.9%, exhibiting significant capacity decay. These results demonstrate that the introduction of Ru-Ni bimetallic nanomaterials can effectively suppress the polysulfide shuttle effect and promote the rapid conversion of polysulfides through synergistic adsorption and catalysis, thereby reducing active material loss and improving battery cycle stability, resulting in a significant improvement in the electrochemical performance of lithium-sulfur batteries.
[0027] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.
Claims
1. A method for preparing a lithium-sulfur battery separator modified with a bimetallic nanoparticle catalytic material, characterized in that, Includes the following steps: S1, Ru3(CO) 12 Ni(acac)2, L-ascorbic acid, polyvinylpyrrolidone and ethylene glycol were added to the vial in sequence; S2. After tightening the cap, place the mixture in an ultrasonic cleaner and ultrasonically treat it for 15 minutes until a homogeneous mixture is formed. S3. The obtained homogeneous mixture was heated at a constant temperature of 180 °C for 5 h. After the reaction was completed, it was naturally cooled to room temperature to obtain a suspension containing RuNi bimetallic nanoparticles. S4. Place the above suspension in a centrifuge, collect the RuNi nanoparticles by centrifugation, wash them three times with an acetone / ethanol mixture, and then vacuum dry them for later use. S5. Mix RuNi nanoparticles, Super P and binder LA133 in proportion and stir evenly to obtain slurry A; S6. Using a 60 μm scraper, slurry A is uniformly coated onto the surface of the Celgard 2500 separator. After coating, the separator is placed in a vacuum drying oven and heated at a constant temperature of 60 °C for 10-12 h to obtain a lithium-sulfur battery separator modified with RuNi bimetallic nanoparticle catalyst material.
2. The preparation method according to claim 1, characterized in that: In step S1, Ru3(CO) 12 The dosage is 5.4 mg, Ni(acac)2 is 6 mg, L-ascorbic acid is 54.6 mg, PVP is 40 mg and ethylene glycol is 10 mL.
3. A lithium-sulfur battery separator modified with a bimetallic nanoparticle catalytic material, characterized in that: It is prepared by the preparation method described in claim 1 or 2.
4. A lithium-sulfur battery, characterized in that: The lithium-sulfur battery includes a lithium-sulfur battery separator modified with the bimetallic nanoparticle catalytic material as described in claim 3.
5. A lithium-sulfur battery according to claim 4, characterized in that: The lithium-sulfur battery also includes a positive electrode, a negative electrode, and an electrolyte, and the assembly of the lithium-sulfur battery is completed under argon protection.
6. A lithium-sulfur battery according to claim 5, characterized in that: The method for preparing the positive electrode sheet is as follows: (1) Take 7 parts of sublimed sulfur, 2 parts of conductive carbon black and 1 part of binder according to the mass ratio, grind and stir at 75 rpm for 6 h, and make a slurry after thorough mixing; the binder is composed of polyvinylidene fluoride and N-methylpyrrolidone, wherein the ratio of polyvinylidene fluoride to N-methylpyrrolidone is 0.75 g: 30 mL; (2) The slurry is uniformly coated on the clean aluminum foil current collector surface by scraper coating method. Then the aluminum foil is transferred to a vacuum drying oven and dried at 60 °C for 10 h. The dried aluminum foil is cut into small round pieces with a diameter of 16 mm using a precision punching die. These round pieces are the positive electrode plates.
7. A lithium-sulfur battery according to claim 5, characterized in that: The negative electrode is a commercially available lithium metal sheet.
8. A lithium-sulfur battery according to claim 5, characterized in that: The electrolyte is a mixed solution obtained by mixing 1,3-dioxolane and dimethoxyethane in a volume ratio of 1:1, with 0.1 M LiNO3 and 1 M lithium bis(trifluoromethanesulfonyl)imide added to the mixed solution.
9. A lithium-sulfur battery according to claim 5, characterized in that: In argon protection, H2O < 0.1 ppm, O2 < 0.1 ppm.