Low-temperature fast ion transport catalyst and low-temperature fast ion transport interface phase layer and method

Abstract

The invention discloses a preparation method of a low-temperature fast ion transport catalyst. The preparation method comprises the following steps: step 1, uniformly mixing nano carbon powder, polyvinylpyrrolidone and deionized water to prepare a mixed solution A; uniformly mixing niobium pentachloride and absolute ethyl alcohol to prepare a mixed solution B; step 2, preparing a mixed solution C; step 3, carrying out suction filtration and washing on the mixed solution C, and then freeze-drying; step 4, preparing a mixed solution D; preparing a mixed solution E; 5, uniformly mixing the mixed solution E and the mixed solution D, and drying; and step 6, carrying out heat treatment on the product obtained in the step 5 under atmosphere protection. The invention also discloses a preparation method of the low-temperature fast ion transport catalyst, a low-temperature fast ion transport interface phase layer and a preparation method of the low-temperature fast ion transport interface phase layer. According to the preparation method of the low-temperature fast ion transmission interface phase layer, conversion reaction kinetics of lithium polysulfide can be promoted, and the battery capacity is improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of lithium batteries, and specifically relates to a low-temperature fast ion transport catalyst and a method for preparing the low-temperature fast ion transport catalyst, and also relates to a low-temperature fast ion transport interface phase layer and a method for preparing the low-temperature fast ion transport interface phase layer. Background Art

[0002] Lithium-sulfur batteries (LSBs) have a high theoretical mass energy density (2600 Whkg -1 ) and volumetric energy density (2800 WhL -1 ), one of the most promising energy storage secondary batteries with long battery life. However, the current practical application of LSB still faces challenges such as low energy density, short life, and poor fast charging performance. The main problems are the slow desolvation of lithium ions at the interface, the hysteresis of lithium ion transfer at the interface, and the interaction between lithium ions and soluble intermediate products such as lithium polysulfide (Li2S x 4≤x≤8) is hindered, causing the shuttle effect and making the battery charge and discharge rate poor. o Below C, the lithium ion solvation space sheath structure becomes larger, and the steric hindrance is significantly enhanced, which inhibits the diffusion dynamics of lithium ions inside the electrolyte or at the interface, increases the desolvation barrier, slows the lithium ion transfer dynamics, slows the conversion of lithium polysulfide, and reduces the utilization rate of active materials, resulting in a significant decrease in capacity and a decrease in battery coulombic efficiency.

[0003] In response to the above problems, the current solution is mainly to promote the desolvation of interfacial solvated lithium ions through electrolyte engineering and porous material screening, obtain free lithium ions, and promote the conversion of lithium polysulfides. However, electrolyte engineering usually adds additives or dilute solvents to adjust the outer layer structure of the solvated lithium ions, weakening the Li + -Solvent effect promotes the release of free Li + , but it often reduces the ionic conductivity of the solvent. Porous screening materials can screen out part of the solvent sheath and dissolve it by physical extrusion at the positive electrode interface, but some solvent molecules with the same pore size will also pass through the screening layer, the dissolution capacity is limited, the lithium ion transmission is slow, especially at low temperatures, the ion transmission kinetics are insufficient, the lithium polysulfide conversion is slow, and the battery capacity is low. In addition, the existing modified interface layer on the positive electrode surface can adsorb lithium polysulfide and promote its conversion, but lacks the ability to catalyze lithium ion dissolution and promote ion transmission from the source, and there are insufficient active sites for dissolution and ion transmission. Summary of the Invention

[0004] The first object of the present invention is to provide a method for preparing a low-temperature fast ion transport catalyst, wherein the prepared catalyst can obtain high-concentration and fully dispersed ion transport sites.

[0005] A second object of the present invention is to provide a catalyst having low temperature fast ion transport.

[0006] The third object of the present invention is to provide a method for preparing a low-temperature fast ion transport interface phase layer. The use of a low-temperature fast ion transport catalyst can form uniform and fast ion transport sites, promote the reaction kinetics of lithium polysulfide conversion, and improve battery capacity.

[0007] The fourth object of the present invention is to provide a low-temperature fast ion transport interface phase layer.

[0008] The first technical solution adopted by the present invention is a method for preparing a low-temperature fast ion transport catalyst, comprising the following steps: Step 1: Evenly mix nano-carbon powder, polyvinyl pyrrolidone and deionized water to prepare a mixed solution A; evenly mix niobium pentachloride and anhydrous ethanol to prepare a mixed solution B; Step 2: uniformly mix the mixed solution B, the mixed solution A and urea, and heat and keep the mixture in a closed space to obtain a mixed solution C; Step 3, filtering and washing the mixed solution C, and then freeze-drying; Step 4: adding the product obtained in step 3 to methanol, further adding polyvinyl pyrrolidone to the mixed solution, and ultrasonically dispersing the mixture to obtain a mixed solution D; adding a soluble copper salt and acrylic acid to the mixed solution D to obtain a mixed solution E; Step 5: Evenly mix the mixed solution E and the mixed solution D and dry them; Step 6: heat-treating the product obtained in step 5 under atmosphere protection.

[0009] The present invention is also characterized in that: Step 1 is specifically as follows: nanocarbon powder, polyvinyl pyrrolidone and deionized water are mixed and ultrasonicated for 0.5 h to 2 h to obtain a mixed solution A, wherein the amount of nanocarbon powder is 0.42 g / L to 1.25 g / L and the amount of polyvinyl pyrrolidone is 0.21 g / L to 0.42 g / L; niobium pentachloride is dissolved in anhydrous ethanol and magnetically stirred for 0.5 h to 1.5 h to obtain a mixed solution B, wherein the concentration of niobium pentachloride in the mixed solution B is 37 mmol / L to 74 mmol / L; In step 1, the nano-carbon powder is carbon nanotubes or graphene or reduced graphene oxide; The thickness of the graphene and reduced graphene oxide sheets is 4 nm to 20 nm, the size of the microsheets is 5 μm to 10 μm, and the number of layers is no more than 20; The specifications of carbon nanotubes are: diameter: 10nm ~ 25nm, length: 5μm ~ 10μm; Step 2 is specifically as follows: after adding the mixed solution B to the mixed solution A, urea is further added to the mixed solution, magnetically stirred to be uniform, transferred to a sealed container, and then heated to 150° C. to 180° C., and kept warm for 15 h to 24 h to obtain a mixed solution C; In step 2, the mass ratio of the added urea to the niobium pentachloride in step 1 is 2.5-5:1; Step 3 is specifically as follows: filtering the mixed solution C, washing with deionized water and anhydrous ethanol to remove soluble impurities on the surface of the filtered solid, and freeze-drying at -20°C to -40°C for 12h to 24h to obtain the nanocarbon material-loaded niobium pentoxide nanomaterial.

[0010] Step 4 is specifically as follows: adding the product (Nb2O5-C powder) obtained in step 3 to methanol and mixing evenly, then adding polyvinyl pyrrolidone to the mixed solution, and ultrasonically dispersing for 0.5h~2h to obtain a mixed solution D, wherein the amount of niobium pentoxide nanomaterial supported by the nanocarbon material in the mixed solution D is 3.4g / L~13.3g / L, and the amount of polyvinyl pyrrolidone is 0.7g / L~3.4g / L; dissolving a soluble copper salt in methanol and adding acrylic acid dropwise to obtain a mixed solution E; in the mixed solution E, the concentration of the soluble copper salt is 5.1mmol / L~15.2mmol / L, and the concentration of the acrylic acid is 16mmol / L~48mmol / L; In step 4, the soluble copper salt is copper acetate, copper nitrate or copper chloride.

[0011] Step 5 is specifically as follows: adding the mixed solution E to the mixed solution D, mixing by magnetic stirring until uniform, placing the mixed solution in a drying device, rapidly evaporating to dryness, and collecting the obtained product; In step 5, the drying temperature is 60° C. to 80° C., and the drying time is 0.5 h to 1 h.

[0012] Step 6 is specifically as follows: the product obtained in step 5 is placed in a heating furnace under atmosphere protection, and is kept at 600°C to 900°C for 2h to 4h at a heating rate of 5°C / min to 10°C / min to obtain a low-temperature fast ion transport catalyst; The protective gas used in the protective atmosphere is argon, nitrogen, hydrogen-argon mixture or ammonia; The composition of the hydrogen-argon mixed gas is a volume ratio, specifically H2:Ar=5~10%:95~90%.

[0013] The second technical solution adopted by the present invention is that the low-temperature fast ion transport catalyst is prepared by the above method.

[0014] The third technical solution adopted by the present invention is a method for preparing a low-temperature fast ion transport interface phase layer, comprising the following steps: Step 1: Mixing and grinding the above-mentioned low-temperature fast ion transport catalyst, carbon material and binder until a mixed solid A is obtained; Step 2: Mix the mixed solid A and N-methylpyrrolidone to form a slurry, and apply the slurry to the diaphragm using a coating device and dry it.

[0015] The present invention is also characterized in that: In step 1, the mass ratio of the low-temperature fast ion transport catalyst, the carbon material, and the binder is: 7-9: 2-0.5: 1-0.5; The carbon material is acetylene black, super conductive carbon black, Ketjen black or carbon nanotube; The binder is polyvinylidene fluoride.

[0016] Step 2 is specifically as follows: adding mixed solid A to N-methylpyrrolidone, the mass ratio of mixed solid A to N-methylpyrrolidone is: 1:5~10, and magnetic stirring is performed for 8h~12h to form a uniform slurry; using a coater to apply the slurry to the diaphragm, and placing it in an oven at 50℃~80℃ for 24h~48h; wherein, the coater is used to control the thickness of the film to 5μm~15μm.

[0017] The fourth technical solution adopted by the present invention is that the low-temperature fast ion transport interface phase layer is prepared by the above method.

[0018] The beneficial effects of the present invention are: (1) The low-temperature fast ion transport catalyst prepared by the method of the present invention is obtained by constructing defects in niobium pentoxide with a 3d unsaturated electronic structure (Nb2O 5-x ), which easily forms electron-delocalized active sites, allowing them to undergo electron hybridization with copper atoms with strong charge hybridization capabilities, anchoring dispersed metal atoms and effectively preventing metal atom aggregation, achieving high atomic utilization and high catalytic efficiency. Furthermore, this catalyst's intrinsic charge transfer modification is less sensitive to ambient temperature than electrolyte regulation and solvent porous sieves, facilitating rapid interfacial ion transport at low temperatures, promoting lithium polysulfide conversion, and facilitating the development of high-performance, low-temperature lithium-sulfur batteries.

[0019] (2) The preparation method of the low-temperature fast ion transport interface phase layer of the present invention uses a low-temperature fast ion transport catalyst to form a uniform and fast ion transport site, and uses an organic solvent coating combined with hydrothermal synthesis and impregnation method to synthesize a catalyst based on defective niobium pentoxide loaded with different copper single atoms and dispersed on nano-carbon powder (SACu@Nb2O 5-x-C) of the low-temperature fast ion transport interface phase. This fast ion transport interface phase can effectively regulate the Helmholtz layer within the interface, lowering the desolvation energy barrier to promote desolvation while releasing free lithium ions, enhancing ion diffusion to promote the conversion of lithium polysulfide, inhibiting the shuttle effect, and improving the low-temperature rise battery capacity.

[0020] (3) No toxic substances are produced during the preparation process of the method of the present invention, the cost is low and the pollution is small. The synthesis method is simple and controllable, and does not require large-scale precision equipment and complex process, and is easy to achieve large-scale production and application. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 The XRD patterns of the fast ion transport catalysts with different Cu atom loadings prepared in Examples 1, 2, 3 and 5 of the present invention and the niobium pentoxide nanomaterial supported by the nanocarbon material, the intermediate product of Example 1; Figure 2 SACu (2 wt%)@Nb2O with a Cu single atom loading of 2 wt% prepared in Example 1 of the present invention 5-x -SEM image of C fast ion transport catalyst; Figure 3 SACu (2 wt%)@Nb2O prepared in Example 1 of the present invention 5-x -Spherical aberration corrected electron microscopy image of C fast ion transport catalyst; Figure 4 SACu (2 wt%)@Nb2O prepared in Example 1 of the present invention 5-x -C cross-sectional SEM image of the fast ion transport interface phase layer; Figure 5 SACu (2 wt%)@Nb2O prepared in Example 1 of the present invention 5-x - Plane SEM image of C fast ion transport interface phase layer; Figure 6 SACu (3 wt%)@Nb2O with a Cu single atom loading of 3 wt% prepared in Example 2 of the present invention 5-x -SEM image of C fast ion transport catalyst; Figure 7 SACu (2 wt%)@Nb2O prepared in Example 1 of the present invention 5-x -Electrochemical impedance spectroscopy (EIS) of lithium-sulfur batteries modified with C fast ion transport interface phase layer; Figure 8 SACu (2 wt%)@Nb2O prepared in Example 1 of the present invention 5-x -C fast ion transport interface phase layer modified lithium sulfur battery characterization ion diffusion (impedance-angular frequency) curve; Figure 9SACu (2 wt%)@Nb2O prepared in Example 1 of the present invention 5-x -C catalyzed sulfur cathode low-temperature cycling performance diagram. DETAILED DESCRIPTION

[0022] The present invention will be described in detail below with reference to the accompanying drawings and specific embodiments.

[0023] The present invention provides a method for preparing a low-temperature fast ion transport catalyst, comprising the following steps: Step 1: Evenly mix nano-carbon powder, polyvinyl pyrrolidone and deionized water to prepare a mixed solution A; evenly mix niobium pentachloride and anhydrous ethanol to prepare a mixed solution B; Step 2: uniformly mix the mixed solution B, the mixed solution A and urea, and heat and keep the mixture in a closed space to obtain a mixed solution C; Step 3, filtering and washing the mixed solution C, and then freeze-drying; Step 4: adding the product obtained in step 3 to methanol, further adding polyvinyl pyrrolidone to the mixed solution, and ultrasonically dispersing the mixture to obtain a mixed solution D; adding a soluble copper salt and acrylic acid to the mixed solution D to obtain a mixed solution E; Step 5: Evenly mix the mixed solution E and the mixed solution D and dry them; Step 6: heat-treating the product obtained in step 5 under atmosphere protection.

[0024] Step 1 specifically comprises: mixing nanocarbon powder, polyvinyl pyrrolidone, and deionized water, and ultrasonicating for 0.5 h to 2 h to obtain a mixed solution A, wherein the amount of nanocarbon powder is 0.42 g / L to 1.25 g / L, and the amount of polyvinyl pyrrolidone is 0.21 g / L to 0.42 g / L; dissolving niobium pentachloride in anhydrous ethanol, and magnetically stirring for 0.5 h to 1.5 h to mix uniformly to obtain a mixed solution B, wherein the concentration of niobium pentachloride in the mixed solution B is 37 mmol / L to 74 mmol / L; In step 1, the nano-carbon powder is carbon nanotubes or graphene or reduced graphene oxide; The thickness of the graphene and reduced graphene oxide sheets is 4 nm to 20 nm, the size of the microsheets is 5 μm to 10 μm, and the number of layers is no more than 20; The specifications of carbon nanotubes are: diameter: 10nm ~ 25nm, length: 5μm ~ 10μm; Step 2 is specifically as follows: slowly adding mixed solution B to mixed solution A, then continuing to add urea to the mixed solution, stirring evenly with a magnetic stirrer, transferring to a sealed container, and then heating to 150° C. to 180° C., keeping warm for 15 h to 24 h, to obtain mixed solution C; In step 2, the mass ratio of the added urea to the niobium pentachloride in step 1 is 2.5-5:1; Step 3 is specifically as follows: filtering the mixed solution C, washing it with deionized water and anhydrous ethanol to remove soluble impurities on the surface of the filtered solid, and freeze-drying it at -20°C to -40°C for 12h to 24h to obtain a nanocarbon material-loaded niobium pentoxide nanomaterial (Nb2O5-C).

[0025] Step 4 is specifically as follows: adding the product (Nb2O5-C powder) obtained in step 3 to methanol and mixing evenly, then adding polyvinyl pyrrolidone to the mixed solution, and ultrasonically dispersing for 0.5h~2h to obtain a mixed solution D, wherein the amount of niobium pentoxide nanomaterial supported by the nanocarbon material in the mixed solution D is 3.4g / L~13.3g / L, and the amount of polyvinyl pyrrolidone is 0.7g / L~3.4g / L; dissolving a soluble copper salt in methanol and adding acrylic acid dropwise to obtain a mixed solution E; in the mixed solution E, the concentration of the soluble copper salt is 5.1mmol / L~15.2mmol / L, and the concentration of acrylic acid is 16mmol / L~48mmol / L; In step 4, the soluble copper salt is copper acetate, copper nitrate or copper chloride.

[0026] Step 5 is specifically as follows: slowly adding the mixed solution E to the mixed solution D, stirring the mixed solution by magnetic stirring until uniform, placing the mixed solution in a drying device, rapidly evaporating to dryness, and collecting the obtained product; In step 5, the drying temperature is 60° C. to 80° C., and the drying time is 0.5 h to 1 h.

[0027] Step 6 is as follows: the product obtained in step 5 is placed in a heating furnace under atmosphere protection, and the temperature is kept at 600°C to 900°C for 2h to 4h at a heating rate of 5°C / min to 10°C / min to obtain defective niobium oxide loaded with 1.5wt% to 4.5wt% copper single atoms (SACu(1.5~4.5 wt%)@Nb2O 5-x -C) nanocomposites as low-temperature fast ion transport catalysts; The protective gas used in the protective atmosphere is argon, nitrogen, hydrogen-argon mixture or ammonia; The composition of the hydrogen-argon mixed gas is a volume ratio, specifically H2:Ar=5~10%:95~90%.

[0028] The present invention also provides a low-temperature fast ion transport catalyst, which is prepared by the above method.

[0029] The present invention also provides a method for preparing a low-temperature fast ion transport interface phase layer, comprising the following steps: Step 1: Prepare the SACu(1.5~4.5 wt%)@Nb2O 5-x -C) mixing and grinding the low-temperature fast ion transport catalyst, the carbon material and the binder until a uniform mixed solid A is obtained; Step 2: Mix the mixed solid A and N-methylpyrrolidone to form a slurry, and apply the slurry to the diaphragm using a coating device and dry it.

[0030] In step 1, the mass ratio of the low-temperature fast ion transport catalyst, the carbon material, and the binder is: 7-9: 2-0.5: 1-0.5; The carbon material is acetylene black (particle size 29 nm), super conductive carbon black (particle size 40 nm), Ketjen black (particle size ≤ 200 mesh) or carbon nanotubes (tube diameter: 10 nm ~ 25 nm, length 5 μm ~ 10 μm); The binder is polyvinylidene fluoride.

[0031] Step 2 is specifically as follows: adding mixed solid A to N-methylpyrrolidone (NMP), the mass ratio of mixed solid A to N-methylpyrrolidone being 1:5~10, and magnetically stirring for 8h~12h to form a uniform viscous slurry; using a film applicator to apply the slurry to the diaphragm, and placing it in an oven at 50℃~80℃ for 24h~48h; wherein, the film thickness is controlled to 5μm~15μm (after drying) using the film applicator.

[0032] The present invention also provides a low-temperature fast ion transport interface phase layer, which is prepared by the above method.

[0033] Example 1 The preparation method of the low-temperature fast ion transport catalyst comprises the following steps: (1) Dissolve carbon nanotubes and polyvinyl pyrrolidone in deionized water and disperse them uniformly by ultrasonication for 1 h to obtain a mixed solution A, wherein the concentration of carbon nanotubes in solution A is 1.25 g / L and the concentration of polyvinyl pyrrolidone in solution A is 0.21 g / L; dissolve niobium pentachloride in anhydrous ethanol and mix them uniformly by magnetic stirring for 0.5 h to obtain a mixed solution B with a concentration of 44 mmol / L; In step 1, the specifications of the carbon nanotubes are: diameter: 10 nm, length: 10 μm; (2) Slowly adding the mixed solution B to the mixed solution A, adding urea, stirring evenly with a magnetic stirrer, transferring to a sealed container, and then heating to 180° C. and keeping warm for 15 hours to obtain a mixed solution C, wherein the mass ratio of the added urea to the niobium pentachloride in step (1) is 3:1; (3) The mixed solution C of step (2) was filtered, washed with deionized water and anhydrous ethanol to remove soluble impurities on the surface of the filtered solid, and then freeze-dried at -20°C for 24 hours to obtain carbon nanotube-loaded niobium pentoxide nanomaterial (Nb2O5-C); (4) The solid powder obtained in step (3) was added to methanol, and polyvinyl pyrrolidone was then added to the mixed solution, and ultrasonic dispersion was performed for 0.5 h to obtain a mixed solution D, wherein the amount of Nb2O5-C powder in the mixed solution D was 6.7 g / L, and the amount of polyvinyl pyrrolidone was 0.7 g / L; copper acetate was dissolved in methanol, and acrylic acid was added dropwise to obtain a mixed solution E, wherein the concentration of copper acetate was 6.8 mmol / L, and the concentration of acrylic acid was 22.9 mmol / L; (5) Solution E was slowly added to solution D. After the mixture was evenly mixed by magnetic stirring, the mixed solution was placed in a heating device for rapid evaporation to dryness, and the obtained product was collected. The drying temperature was 80 °C and the drying time was 0.5 h. (6) The product obtained in (5) was heated at 600°C for 3 h in a tubular heating furnace under argon protection at a heating rate of 5°C / min to obtain defective niobium oxide loaded with 2 wt% Cu single atoms (SACu(2wt%)@Nb2O 5-x -C) Nanocomposites as low-temperature fast ion transport catalysts.

[0034] The method for preparing a low-temperature fast ion transport interface phase layer comprises the following steps: (1) SACu (2wt%)@ Nb2O prepared by the above method 5-x -C powder was mixed with acetylene black and binder polyvinylidene fluoride in a mass ratio of (9:0.5:0.5) and ground until uniform mixed solid A was obtained; wherein the particle size of acetylene black was 29 nm; (2) mixed solid A was added to N-methylpyrrolidone (NMP) in a mass ratio of mixed solid A to N-methylpyrrolidone of 1:5, and magnetically stirred for 8 h to form a uniform viscous slurry; the slurry was coated on the diaphragm using a coater and placed in a 70°C oven for 28 h; wherein the film thickness was controlled to 5 μm (after drying) using a coater.

[0035] Example 2 The preparation method of the low-temperature fast ion transport catalyst comprises the following steps: (1) Dissolve carbon nanotubes and polyvinyl pyrrolidone in deionized water and disperse them uniformly by ultrasonication for 1.5 h to obtain a mixed solution A, wherein the concentration of carbon nanotubes in solution A is 1.25 g / L and the concentration of polyvinyl pyrrolidone in solution A is 0.42 g / L; dissolve niobium pentachloride in anhydrous ethanol and mix them uniformly by magnetic stirring for 1 h to obtain a 60 mmol / L mixed solution B; In step 1, the specifications of the carbon nanotubes are: diameter: 20 nm, length: 8 μm; (2) Slowly adding mixed solution B to mixed solution A, adding urea, stirring evenly with a magnetic stirrer, transferring to a sealed container, and then heating to 180° C. and keeping warm for 24 hours to obtain mixed solution C, wherein the mass ratio of the added urea to the niobium pentachloride in step (1) is 4:1; (3) The mixed solution C of step (2) was filtered, washed with deionized water and anhydrous ethanol to remove soluble impurities on the surface of the filtered solid, and then freeze-dried at -30°C for 20 hours to obtain carbon nanotube-loaded niobium pentoxide nanomaterial (Nb2O5-C); (4) The solid powder obtained in step (3) was added to methanol, and polyvinyl pyrrolidone was then added to the mixed solution, and ultrasonic dispersion was performed for 1 h to obtain a mixed solution D, wherein the amount of Nb2O5-C powder in the mixed solution D was 6.7 g / L, and the amount of polyvinyl pyrrolidone was 1.2 g / L; copper acetate was dissolved in methanol, and acrylic acid was added dropwise to obtain a mixed solution E, wherein the concentration of copper acetate was 7.2 mmol / L, and the concentration of acrylic acid was 34.4 mmol / L; (5) Solution E was slowly added to solution D. After the mixture was evenly mixed by magnetic stirring, the mixed solution was placed in a heating device for rapid evaporation to dryness, and the obtained product was collected. The drying temperature was 70 °C and the drying time was 0.8 h. (6) The product obtained in (5) was heated at 700 °C for 3 h in a tubular heating furnace under argon protection at a heating rate of 8 °C / min to obtain defective niobium oxide loaded with 3 wt% Cu single atoms (SACu(3wt%)@Nb2O 5-x -C) Nanocomposites as low-temperature fast ion transport catalysts.

[0036] The method for preparing a low-temperature fast ion transport interface phase layer comprises the following steps: (1) SACu (3wt%)@ Nb2O 5-x -C powder, acetylene black and binder polyvinylidene fluoride were mixed and ground in a mass ratio of (8:1:1) until a uniform mixture was obtained to obtain a mixed solid A; wherein the particle size of the acetylene black was 29 nm; (2) The mixed solid A was added to N-methylpyrrolidone (NMP) at a mass ratio of 1:7, and magnetic stirring was performed for 8 h to form a uniform viscous slurry. The slurry was coated on the diaphragm using a coater and placed in a 70°C oven for 32 h. The film thickness was controlled to 10 μm (after drying) using a coater.

[0037] Example 3 The preparation method of the low-temperature fast ion transport catalyst comprises the following steps: (1) Graphene powder and polyvinyl pyrrolidone were dissolved in deionized water and dispersed uniformly by ultrasonication for 2 h to obtain a mixed solution A, wherein the concentration of graphene in solution A was 0.42 g / L and the concentration of polyvinyl pyrrolidone in solution A was 0.25 g / L; niobium pentachloride was dissolved in anhydrous ethanol and magnetically stirred for 1 h to obtain a 37 mmol / L mixed solution B; In step 1, the thickness of the graphene powder is 10 nm, the size of the micro-flakes is 8 μm, and the number of layers is no more than 20; (2) Slowly adding mixed solution B to mixed solution A, adding urea, stirring evenly with a magnetic stirrer, transferring to a sealed container, and then heating to 170° C. and keeping warm for 24 hours to obtain mixed solution C, wherein the mass ratio of the added urea to the niobium pentachloride in step (1) is 5:1; (3) The mixed solution C of step (2) was filtered, washed with deionized water and anhydrous ethanol to remove soluble impurities on the surface of the filtered solid, and then freeze-dried at -40°C for 18 hours to obtain graphene-supported niobium pentoxide nanomaterial (Nb2O5-C); (4) The solid powder obtained in step (3) was added to methanol, and polyvinyl pyrrolidone was then added to the mixed solution, and ultrasonic dispersion was performed for 1 h to obtain a mixed solution D, wherein the amount of Nb2O5-C powder in the mixed solution D was 6.7 g / L and the amount of polyvinyl pyrrolidone was 1.2 g / L; copper acetate was dissolved in methanol, and acrylic acid was added dropwise to obtain a mixed solution E, wherein the concentration of copper acetate was 11.4 mmol / L and the concentration of acrylic acid was 48 mmol / L; (5) Solution E was slowly added to solution D, and after being mixed evenly by magnetic stirring, the mixed solution was placed in a heating device for rapid evaporation to dryness, and the obtained product was collected. The drying temperature was 60 °C and the drying time was 1 h. (6) The product obtained in (5) was heated at 600 °C for 4 h in a tubular heating furnace under the protection of hydrogen and argon mixed gas at a heating rate of 10 °C / min to obtain defective niobium oxide loaded with 4.5 wt% Cu single atoms (SACu(4.5wt%)@Nb2O 5-x -C) Nanocomposites as low-temperature fast ion transport catalysts.

[0038] The method for preparing a low-temperature fast ion transport interface phase layer comprises the following steps: (1) SACu (4.5wt%) @ Nb2O 5-x -C) the powder was mixed with acetylene black and a binder, polyvinylidene fluoride, in a mass ratio of 7:2:1, and ground until uniformly mixed to obtain a solid mixture A; wherein the particle size of the acetylene black was 29 nm; (2) The mixed solid A was added to N-methylpyrrolidone (NMP) at a mass ratio of 1:10, and magnetic stirring was performed for 10 h to form a uniform viscous slurry. The slurry was coated on the diaphragm using a coater and placed in a 60 °C oven for 45 h. The film thickness was controlled to 15 μm (after drying) using a coater.

[0039] Example 4 (1) Reduced graphene oxide powder and polyvinyl pyrrolidone were dissolved in deionized water and dispersed uniformly by ultrasonication for 2 h to obtain a mixed solution A, wherein the concentration of reduced graphene oxide in solution A was 1.04 g / L and the concentration of polyvinyl pyrrolidone in solution A was 0.42 g / L; niobium pentachloride was dissolved in anhydrous ethanol and magnetically stirred for 1 h to obtain a 62 mmol / L mixed solution B; In step 1, the thickness of the reduced graphene oxide powder is 15 nm, the size of the micro-sheet is 6 μm, and the number of layers is no more than 20; (2) Slowly adding the mixed solution B to the mixed solution A, adding urea, stirring evenly with a magnetic stirrer, transferring to a sealed container, and then heating to 150° C. and keeping warm for 24 hours to obtain a mixed solution C, wherein the mass ratio of the added urea to the niobium pentachloride in step (1) is 5:1; (3) The mixed solution C of step (2) was filtered, washed with deionized water and anhydrous ethanol to remove soluble impurities on the surface of the filtered solid, and then freeze-dried at -40°C for 15 hours to obtain graphene-supported niobium pentoxide nanomaterial (Nb2O5-C); (4) The solid powder obtained in step (3) was added to methanol, and polyvinyl pyrrolidone was then added to the mixed solution, and ultrasonic dispersion was performed for 1.2 h to obtain a mixed solution D, wherein the amount of Nb2O5-C powder in the mixed solution D was 5 g / L and the amount of polyvinyl pyrrolidone was 1 g / L; copper nitrate was dissolved in methanol, and acrylic acid was added dropwise to obtain a mixed solution E, wherein the concentration of copper nitrate was 11.4 mmol / L and the concentration of acrylic acid was 48 mmol / L; (5) Solution E was slowly added to solution D, and after being mixed evenly by magnetic stirring, the mixed solution was placed in a heating device for rapid evaporation to dryness, and the obtained product was collected. The drying temperature was 80 °C and the drying time was 0.5 h. (6) The product obtained in (5) was heated at 800 °C for 2.5 h in a tubular heating furnace under argon protection at a heating rate of 7 °C / min to obtain 4.5 wt% Cu single atoms supported by defective niobium oxide (SACu(4.5wt%)@Nb2O 5-x -C) Nanocomposites as low-temperature fast ion transport catalysts.

[0040] The method for preparing a low-temperature fast ion transport interface phase layer comprises the following steps: (1) SACu (4.5wt%)@Nb2O 5-x -C powder, Ketjen black and binder polyvinylidene fluoride were mixed and ground in a mass ratio of (7:2:1) until a uniform mixture solid A was obtained; wherein the particle size of Ketjen black was 200 mesh; (2) The mixed solid A was added to N-methylpyrrolidone (NMP) at a mass ratio of 1:10, and magnetic stirring was performed for 12 h to form a uniform viscous slurry. The slurry was coated on the diaphragm using a film applicator and placed in an 80 °C oven for 24 h. The film thickness was controlled to 12 μm (after drying) using a film applicator.

[0041] Example 5 1) Dissolve carbon nanotubes and polyvinyl pyrrolidone in deionized water and disperse them uniformly under ultrasonication for 2 hours to obtain a mixed solution A, wherein the concentration of carbon nanotubes in solution A is 0.42 g / L and the concentration of polyvinyl pyrrolidone in solution A is 0.31 g / L. Dissolve niobium pentachloride in anhydrous ethanol and mix uniformly under magnetic stirring for 1 hour to obtain a 37 mmol / L mixed solution B. In step 1, the specifications of the carbon nanotubes are: diameter: 12 nm, length: 7 μm; (2) Slowly adding mixed solution B to mixed solution A, adding urea, stirring evenly with a magnetic stirrer, transferring to a sealed container, and then heating to 180° C. and keeping warm for 24 hours to obtain mixed solution C, wherein the mass ratio of the added urea to the niobium pentachloride in step (1) is 4:1; (3) The mixed solution C of step (2) was filtered, washed with deionized water and anhydrous ethanol to remove soluble impurities on the surface of the filtered solid, and then freeze-dried at -25°C for 30 hours to obtain carbon nanotube-loaded niobium pentoxide nanomaterial (Nb2O5-C); (4) The solid powder obtained in step (3) was added to methanol, and polyvinyl pyrrolidone was then added to the mixed solution, and ultrasonic dispersion was performed for 2 h to obtain a mixed solution D, wherein the amount of Nb2O5-C powder in the mixed solution D was 13.3 g / L, and the amount of polyvinyl pyrrolidone was 3.4 g / L; copper chloride was dissolved in methanol, and acrylic acid was added dropwise to obtain a mixed solution E, wherein the concentration of copper chloride was 7.6 mmol / L, and the concentration of acrylic acid was 34 mmol / L; (5) Solution E was slowly added to solution D, and after being mixed evenly by magnetic stirring, the mixed solution was placed in a heating device for rapid evaporation to dryness, and the obtained product was collected. The drying temperature was 60 °C and the drying time was 1 h. (6) The product obtained in (5) was heated at 900°C for 2 h in a tubular heating furnace under argon protection at a heating rate of 9°C / min to obtain a nanocomposite material of defective niobium oxide loaded with 1.5 wt% copper single atoms (SACu(1.5 wt%)@Nb2O5-C) as a low-temperature fast ion transport catalyst.

[0042] The method for preparing a low-temperature fast ion transport interface phase layer comprises the following steps: (1) SACu (1.5 wt%)@Nb2O5-C powder was mixed with carbon nanotubes and binder polyvinylidene fluoride in a mass ratio of (9:0.5:0.5) and ground until a mixed solid A was obtained; wherein the specifications of the carbon nanotubes were: diameter of 20 nm and length of 8 μm; (2) The mixed solid A was added to N-methylpyrrolidone (NMP) at a mass ratio of 1:5, and magnetic stirring was performed for 10 h to form a uniform viscous slurry. The slurry was coated on the diaphragm using a coater and placed in a 70 °C oven for 28 h. The film thickness was controlled to 8 μm (after drying) using a coater.

[0043] Example 6 (1) Dissolve carbon nanotubes and polyvinyl pyrrolidone in deionized water and disperse them uniformly by ultrasonication for 2 h to obtain a mixed solution A, wherein the concentration of carbon nanotubes in solution A is 1.25 g / L and the concentration of polyvinyl pyrrolidone in solution A is 0.42 g / L; dissolve niobium pentachloride in anhydrous ethanol and mix them uniformly by magnetic stirring for 1 h to obtain a mixed solution B with a concentration of 44.5 mmol / L; In step 1, the specifications of the carbon nanotubes are: diameter: 25 nm, length: 5 μm; (2) Slowly adding mixed solution B to mixed solution A, adding urea, stirring evenly with a magnetic stirrer, transferring to a sealed container, and then heating to 150° C. and keeping warm for 24 hours to obtain mixed solution C, wherein the mass ratio of the added urea to the niobium pentachloride in step (1) is 3.5:1; (3) The mixed solution C of step (2) was filtered, washed with deionized water and anhydrous ethanol to remove soluble impurities on the surface of the filtered solid, and then freeze-dried at -35°C for 20 hours; (4) The solid powder obtained in step (3) was added to methanol, and polyvinyl pyrrolidone was then added to the mixed solution, and ultrasonic dispersion was performed for 1.5 h to obtain a mixed solution D, wherein the amount of Nb2O5-C powder in the mixed solution D was 6.7 g / L and the amount of polyvinyl pyrrolidone was 2 g / L; copper nitrate was dissolved in methanol, and acrylic acid was added dropwise to obtain a mixed solution E, wherein the concentration of copper nitrate was 5.1 mmol / L and the concentration of acrylic acid was 16 mmol / L; (5) Solution E was slowly added to solution D, and after being mixed evenly by magnetic stirring, the mixed solution was placed in a heating device for rapid evaporation to dryness, and the obtained product was collected. The drying temperature was 60 °C and the drying time was 1 h. (6) The product obtained in (5) was heated at 700 °C for 2 h in a tubular heating furnace under argon protection at a heating rate of 8 °C / min to obtain a defective niobium oxide-loaded 1.5 wt% copper single atom (SACu(1.5 wt%)@Nb2O5-C) nanocomposite material as a low-temperature fast ion transport catalyst.

[0044] The method for preparing a low-temperature fast ion transport interface phase layer comprises the following steps: (1) SACu (1.5 wt%)@Nb2O5-C powder was mixed with conductive carbon black and binder polyvinylidene fluoride in a mass ratio of (8:1:1) and ground until a mixed solid A was obtained; wherein the particle size of the conductive carbon black was 40 nm; (2) The mixed solid A was added to N-methylpyrrolidone (NMP) at a mass ratio of 1:8, and magnetic stirring was performed for 10 h to form a uniform viscous slurry. The slurry was coated on the diaphragm using a coater and placed in a 50 °C oven for 48 h. The film thickness was controlled to 10 μm (after drying) using a coater.

[0045] By the method of the present invention, fast ion transport catalysts with a copper single atom loading of 1.5 wt% to 4.5 wt% can be prepared. The X-ray diffraction patterns of these catalysts are as follows: Figure 1 shown. Figure 1 The copper single atom concentration in the Nb2O2 matrix increased from 1.5 wt% to 4.5 wt%, including the SACu (2 wt%)@Nb2O2 prepared in Example 1. 5-x -C and SACu (3 wt%)@Nb2O prepared in Example 2 5-x -C composite materials mainly show the characteristic peaks of Nb2O5 and C, and no Cu peak, indicating that there is no Cu agglomeration in the products prepared by the method of the present invention. Figure 2 It can be seen that the SACu (2 wt%)@Nb2O prepared in Example 1 5-x -C shows a loose and porous morphology, SACu (2 wt%) @ Nb2O 5-x The size of nanoparticles is about 220~300nm. Figure 3 As shown in the spherical aberration corrected electron microscope image, SACu (2 wt%)@Nb2O prepared in Example 1 5-x In the C-C catalyst, Cu single atoms are uniformly dispersed in Nb2O 5-x On the nanoparticles, no agglomeration occurs. Figure 4-Figure 5As shown, a uniform fast ion transport layer was prepared by the preparation method of Example 1, with a thickness of about 5 μm and a uniform and flat surface. Figure 6 As shown, SACu (3wt%)@Nb2O prepared in Example 2 5-x -C composite morphology and SACu(2 wt%)@Nb2O 5-x -C is similar, and no Cu agglomeration occurs. 5-x -C fast ion transport interface phase layer as an example, it is coated on the diaphragm, CNTs / S is used as the positive electrode, metallic lithium is used as the negative electrode, and 1wt% LiNO3 LiTFSI DOL / DME (volume ratio is 1:1) solution is used as the electrolyte to assemble CR2025 button cells. During the battery packaging process, the diaphragm modification layer is pressed and adhered to the positive electrode surface under pressure to form a fast ion transport interface phase layer. SACu (2wt%)@Nb2O prepared in Example 1 5-x -C fast ion transport interface phase layer and the intermediate product in Example 1 are not loaded with Cu single atom catalyst Nb2O 5-x -C interface modification layer modified battery electrochemical impedance test, the results are as follows Figure 7 Impedance spectrum shown. Figure 7 The diameter of the semicircle in the impedance spectrum represents the desolvation reaction impedance of the battery. It can be seen that SACu(2 wt%)@Nb2O 5-x The battery modified with Cu has a smaller desolvation reaction impedance of 26 Ω, which is much lower than that of Nb2O without Cu single atoms. 5-x -C modified layer modified 75 Ω, indicating that SACu (2 wt%)@Nb2O 5-x -C fast ion transport interface layer catalyzed cells have faster desolvation kinetics. Figure 7 The oblique line part of the Weibull impedance is fitted to obtain the real part of the impedance Z' and the angular frequency ω -1 / 2 The linear relationship between Figure 8 As shown. Figure 8 It can be seen that the SACu (2wt%)@Nb2O prepared in Example 1 5-x The slope of the cell line σ for the catalytic layer of the C-C fast ion transport interface is 3.5, which is higher than that of the intermediate product Nb2O without Cu single atom catalyst. 5-x -C modified layer modified battery 8.7. Because D (ion diffusion coefficient) ∝ 1 / σ, therefore, SACu (2wt%) @ Nb2O 5-x -C catalyzed battery has a larger ion diffusion coefficient, indicating that SACu(2wt%)@Nb2O 5-x-C fast ion transport interface phase layer can catalyze and enhance the interfacial lithium ion desolvation and ion transport kinetics of the battery, promote the conversion of lithium polysulfide, inhibit the shuttle effect, and improve the capacity and stability of the battery.

[0046] Further evaluation of SACu (2 wt%)@Nb2O prepared in Example 1 5-x -C fast ion transport interface phase layer catalyzed low-temperature electrochemical performance of the battery, compared with SACu (2wt%)@Nb2O 5-x -C fast ion transport interface phase layer catalytic cell and the intermediate product in Example 1 without Cu single atom catalyst Nb2O 5-x -C interface modification layer modified battery cycle performance, the results are as follows Figure 9 As shown. Figure 9 It can be seen that at 0℃, SACu(2 wt%)@Nb2O 5-x -C fast ion transport interface phase layer catalyzed lithium-sulfur battery, compared with modified Nb2O without Cu single atom loading 5-x -C non-catalytic modified layer has higher specific capacity and cycle stability. SACu(2 wt%)@Nb2O 5-x -C catalytic battery's first discharge capacity is as high as 1022mAhg -1 , compared with the control sample Nb2O 5-x -C non-catalytic modified layer modified battery is 20.1% higher, while after 80 cycles, SACu (2wt%) @ Nb2O 5-x -C catalyzed battery capacity retention rate is as high as 86%, which is higher than that of Nb2O 5-x -C non-catalytic modified layer modified cells improved by 5%, which is due to SACu (2 wt%) @ Nb2O 5-x -C fast ion transport layer catalyzes the rapid desolvation of free Li at the cathode interface + He Li + Rapid transmission promotes the rapid conversion of the intermediate product lithium polysulfide, thereby inhibiting the shuttle effect and improving battery capacity and retention rate.

Claims

1. A method for preparing a low-temperature fast ion transport catalyst, characterized in that: The following steps are involved: Step 1: Evenly mix nano-carbon powder, polyvinyl pyrrolidone and deionized water to prepare a mixed solution A; evenly mix niobium pentachloride and anhydrous ethanol to prepare a mixed solution B; Step 2: uniformly mix the mixed solution B, the mixed solution A and urea, and heat and keep the mixture in a closed space to obtain a mixed solution C; Step 3, filtering and washing the mixed solution C, and then freeze-drying; Step 4: adding the product obtained in step 3 to methanol, further adding polyvinyl pyrrolidone to the mixed solution, and ultrasonically dispersing the mixture to obtain a mixed solution D; adding a soluble copper salt and acrylic acid to the mixed solution D to obtain a mixed solution E; Step 5: Evenly mix the mixed solution E and the mixed solution D and dry them; Step 6: heat-treating the product obtained in step 5 under atmosphere protection.

2. The method for preparing a low-temperature fast ion transport catalyst according to claim 1, wherein: Step 1 specifically comprises: mixing nanocarbon powder, polyvinyl pyrrolidone, and deionized water, and ultrasonicating for 0.5 h to 2 h to obtain a mixed solution A, wherein the amount of nanocarbon powder is 0.42 g / L to 1.25 g / L, and the amount of polyvinyl pyrrolidone is 0.21 g / L to 0.42 g / L; dissolving niobium pentachloride in anhydrous ethanol, and magnetically stirring for 0.5 h to 1.5 h to mix uniformly to obtain a mixed solution B, wherein the concentration of niobium pentachloride in the mixed solution B is 37 mmol / L to 74 mmol / L; In step 1, the nano-carbon powder is carbon nanotubes or graphene or reduced graphene oxide; Step 2 is specifically as follows: after adding the mixed solution B to the mixed solution A, urea is further added to the mixed solution, magnetically stirred to be uniform, transferred to a sealed container, and then heated to 150° C. to 180° C., and kept warm for 15 h to 24 h to obtain a mixed solution C; In step 2, the mass ratio of the added urea to the niobium pentachloride in step 1 is 2.5-5:1; Step 3 is specifically as follows: filtering the mixed solution C, washing with deionized water and anhydrous ethanol to remove soluble impurities on the surface of the filtered solid, and freeze-drying at -20°C to -40°C for 12h to 24h to obtain the nanocarbon material-loaded niobium pentoxide nanomaterial.

3. The method for preparing a low-temperature fast ion transport catalyst according to claim 1, wherein: Step 4 is specifically as follows: adding the product obtained in step 3 to methanol and mixing evenly, then adding polyvinyl pyrrolidone to the mixed solution, and ultrasonically dispersing for 0.5h~2h to obtain a mixed solution D, wherein the amount of niobium pentoxide nanomaterial supported by the nanocarbon material in the mixed solution D is 3.4g / L~13.3g / L, and the amount of polyvinyl pyrrolidone is 0.7g / L~3.4g / L; dissolving the soluble copper salt in methanol and adding acrylic acid dropwise to obtain a mixed solution E; in the mixed solution E, the concentration of the soluble copper salt is 5.1mmol / L~15.2mmol / L, and the concentration of the acrylic acid is 16mmol / L~48mmol / L; In step 4, the soluble copper salt is copper acetate, copper nitrate or copper chloride.

4. The method for preparing a low-temperature fast ion transport catalyst according to claim 1, wherein: Step 5 is specifically as follows: adding the mixed solution E to the mixed solution D, mixing by magnetic stirring until uniform, placing the mixed solution in a drying device, rapidly evaporating to dryness, and collecting the obtained product; In step 5, the drying temperature is 60° C. to 80° C., and the drying time is 0.5 h to 1 h.

5. The method for preparing a low-temperature fast ion transport catalyst according to claim 1, wherein: Step 6 is specifically as follows: the product obtained in step 5 is placed in a heating furnace under atmosphere protection, and is kept at 600°C to 900°C for 2h to 4h at a heating rate of 5°C / min to 10°C / min to obtain a low-temperature fast ion transport catalyst; The protective gas used in the protective atmosphere is argon, nitrogen, hydrogen-argon mixture or ammonia; The composition of the hydrogen-argon mixed gas is a volume ratio, specifically H2:Ar=5~10%:95~90%.

6. Low-temperature fast ion transport catalyst, characterized in that Prepared by the method according to any one of claims 1 to 5.

7. A method for preparing a low-temperature fast ion transport interface phase layer, characterized in that: The following steps are involved: Step 1: mixing and grinding the low-temperature fast ion transport catalyst according to claim 6 with a carbon material and a binder until a mixed solid A is obtained; Step 2: Mix the mixed solid A and N-methylpyrrolidone to form a slurry, and apply the slurry to the diaphragm using a coating device and dry it.

8. The method for preparing a low-temperature fast ion transport interface phase layer according to claim 7, characterized in that: In step 1, the mass ratio of the low-temperature fast ion transport catalyst, the carbon material, and the binder is: 7-9: 2-0.5: 1-0.5; The carbon material is acetylene black, super conductive carbon black, Ketjen black or carbon nanotube; The binder is polyvinylidene fluoride.

9. The method for preparing a low-temperature fast ion transport interface phase layer according to claim 7, characterized in that: Step 2 is specifically as follows: adding mixed solid A to N-methylpyrrolidone, the mass ratio of mixed solid A to N-methylpyrrolidone is: 1:5~10, and magnetic stirring is performed for 8h~12h to form a uniform slurry; using a coater to apply the slurry to the diaphragm, and placing it in an oven at 50℃~80℃ for 24h~48h; wherein, the coater is used to control the thickness of the film to 5μm~15μm.

10. Low temperature fast ion transport interface phase layer, characterized in that: The method according to any one of claims 8 to 9 is used for preparation.

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