Natural sulfide ore-based metal oxide electrocatalyst composite material as well as preparation method and application thereof

Abstract

The invention discloses a natural sulfide ore-based metal oxide electrocatalyst composite material, which comprises a natural sulfide ore microchip and a transition metal oxide M2Oz combined on the natural sulfide ore microchip, and the transition metal M2 is Mn, Fe, Co, Ni or Cu. The composite material shows significantly improved reversibility and stable cycle performance as a lithium-sulfur battery negative electrode material.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of mineral battery materials, in particular to a natural sulfide mineral-based metal oxide electrocatalyst composite material and a preparation method and application thereof. BACKGROUND

[0002] As the most practical energy storage system, alkali metal ion batteries have attracted extensive attention due to their long cycle life and high power density. Among them, metal sulfide mineral materials such as molybdenite have significant capacity and rich redox potential, and are widely used in the field of energy storage. However, their ion storage capacity is still limited by the dissolution of polysulfides and the sluggish electrochemical kinetics. Among them, the sandwich-like S-Mo-S layers of MoS2 are connected to each other, thereby endowing lithium ions with fast electrochemical intercalation / deintercalation ability. During the process of deep lithiation, MoS2 is first decomposed into metallic molybdenum and Li2S through the reaction with Li + ions, resulting in a volume expansion of about 103%. Notably, the reactivity of molybdenum atoms in 2H-MoS2 is too low to react with Li2S, resulting in insufficient reversibility accompanied by the generation of excess Li2S. That is, the reversible reaction will act as the main redox pair, similar to the reaction process of lithium-sulfur batteries (S + 2Li + + 2e − ↔ Li2S). Therefore, the improvement of the ion storage capacity of MoS2 is still limited by the "shuttle effect" of the intermediate of the conversion reaction, mainly in the form of lithium polysulfides (LiPSs).

[0003] In order to improve the performance of MoS2 anodes, a series of methods have been proposed to solve the above problems. As one of the traditional strategies, the design of nanostructure can provide a shorter diffusion path for Li + ions, while effectively accelerating the reaction kinetics. However, the optimized MoS2 nanostructure still faces the problems of electrode pulverization and polysulfide loss. In addition, the combination of conductive carbon materials can be used to alleviate the volume change and physically suppress the "shuttle effect" of LiPSs. Although long-term stability can be achieved through the synergistic effect of the above methods, the relatively low capacity and initial coulombic efficiency (ICE) due to the presence of carbon matrix cannot be ignored. Through a multi-step method, C@ MoS2@NC hollow spheres were successfully prepared, which can provide 650 mA h g −1 at a current density of 1.0 A g −1The capacity of the Li-S battery is 1672 mAh / g, but the ICE is only 74%. In addition, it is found that the conversion reaction from soluble LiPSs to insoluble Li2S is greatly hindered due to slow kinetics. Therefore, the above problems can be alleviated to some extent by constructing nanostructures, and compositing with carbon materials, but the sluggish conversion reaction between soluble LiPSs and Li2S has not been effectively solved. SUMMARY

[0004] To solve the above problems, the present application studies and finds a natural sulfide mineral-based metal oxide electrocatalyst composite material, which comprises natural sulfide mineral microsheets and transition metal oxides M 2 O z bonded thereon. 2 The transition metal M 1 x S y is Mn, Fe, Co, Ni, or Cu. Since the natural sulfide mineral M 2 O z is closely combined with the transition metal oxide M 1 -S-M 2 through an interfacial chemical bond, and the transition metal oxide M 2 O z and lithium polysulfides LiPSs in lithium-sulfur batteries form M 2 -S bonds due to the charge transfer between the 3d orbitals of the transition metal M 2 cations and the 3p orbitals of the sulfur anions, the composite material significantly promotes the rapid transport of lithium ions and greatly improves the lithium ion storage capacity, exhibits significantly improved reversibility and stable cycle performance as a lithium-sulfur battery negative material, thereby completing the present application.

[0005] The present application aims to provide the following aspects: 1. A natural sulfide mineral-based metal oxide electrocatalyst composite material, comprising natural sulfide mineral microsheets and transition metal oxides M 2 O z bonded thereon. 2 The transition metal M 2 O z is Mn, Fe, Co, Ni, Cu, Zn, V, Ti, or Cr.

[0006] 2. The natural sulfide mineral-based metal oxide electrocatalyst composite material according to claim 1, wherein the M 2 O z is MnO, MnO2, Fe2O3, CoO, Co3O4, NiO, or CuO. The natural sulfide mineral microsheets are nanosheets, and the natural sulfide mineral is selected from molybdenite, pyrite, chalcopyrite, sphalerite, chalcocite, galena, bornite, stibiconite, or bismuthinite.

[0007] 3. The natural sulfide mineral-based metal oxide electrocatalyst composite material as described in 1 above, wherein the natural sulfide mineral M 1 x S y With transition metal oxides M 2 O z M is connected through interfacial chemical bonds 1 -SM 2 Closely integrated.

[0008] 4. The natural sulfide mineral-based metal oxide electrocatalyst composite material as described in 1 above, wherein the transition metal oxide M, as the electrocatalyst, is... 2 O z The interaction between lithium polysulfides (LiPSs) and lithium-sulfur batteries is due to the transition metal M 2 Charge transfer between the 3d orbital of the cation and the 3p orbital of the sulfide anion initiates the formation of M. 2 -S key.

[0009] 5. A method for preparing a composite material of natural sulfide mineral-based metal oxide electrocatalysts, comprising the following steps: (1) Preparation of natural sulfide mineral M 1 x S y Microplate suspension; (2) Loading metal M onto natural sulfide mineral flakes 2 hydroxides; (3) Heating to obtain M 1 x S y / M 2 O z Complex.

[0010] 6. The method described in 5 above, wherein in step (1), natural sulfide mineral particles, especially natural sulfide mineral micron particles, are uniformly dispersed in water and subjected to ultrasonic treatment to obtain natural sulfide mineral flakes, especially natural sulfide mineral nanoflakes.

[0011] 7. The method described in 5 above, wherein, in step (2), a transition metal M is added to the natural sulfide mineral flake suspension obtained in step (1). 2 Metal salts are stirred to form a homogeneous mixture, and then an alkaline solution is added to generate transition metal M on natural sulfide mineral flakes. 2 Hydroxide precipitate.

[0012] 8. The method described in 5 above, wherein in step (3), the filter residue is washed with water and alcohol solvent, dried, and calcined in an inert atmosphere.

[0013] 9. Use of the natural sulfide ore-based metal oxide electrocatalyst composite material as claimed in claim 1 or prepared according to the method as claimed in claim 5 as a negative electrode material for lithium-sulfur batteries.

[0014] In a preferred embodiment of the present application, in step (1), the natural sulfide ore is ground to obtain micron-sized sulfide particles, which are then uniformly dispersed in a medium and subjected to ultrasonic treatment to obtain natural sulfide ore nanosheets.

[0015] In a preferred embodiment of the present application, in step (2), the soluble metal salt of the transition metal can be any commonly used soluble salt of the transition metal Mn, Fe, Co, Ni, or Cu, such as hydrochloride, nitrate, sulfate, etc., for example, manganese chloride, iron nitrate, cobalt nitrate, nickel sulfate, copper sulfate, etc., and is not particularly limited.

[0016] In a preferred embodiment of the present application, in step (3), heating is performed under an inert atmosphere. As the inert atmosphere, any non-reactive gas can be used, such as nitrogen, argon, helium, neon, etc.

[0017] In the most preferred embodiment of the method of the present application, first, 2 grams of molybdenite nanosheets are uniformly dispersed in 30 milliliters of distilled water and subjected to ultrasonic treatment for 1 hour, and then a metal salt is added and stirred for 1 hour to form a uniform mixture. Subsequently, 1 gram of 20.0 wt% sodium hydroxide is injected to form a hydroxide precipitate on the MoS2 nanosheets. After the filtered material is washed with distilled water and ethanol three times, it is dried at 80°C for 12 hours. The dried mixture is calcined at 600°C for 2 hours at a temperature increase rate of 5°C / min under an argon atmosphere, and finally a MoS2@MOx composite material product is obtained.

[0018] The mechanism of the present application is speculated as follows: according to the experience of lithium-sulfur battery systems, electrocatalysts play a crucial role in accelerating the speed of polysulfide redox reactions. Reasonable introduction of electrocatalysts into metal sulfide negative electrodes is expected to reduce the energy barrier of conversion reactions, thereby obtaining excellent electrochemical performance. The anions of electrocatalysts mainly come from V / VI main group elements, such as metal oxides, metal nitrides, metal sulfides, metal selenides, etc. Due to the high electronegativity of oxygen atoms, metal oxide electrocatalysts exhibit the strongest polar surface, which can provide abundant polar active sites for the adsorption of polysulfide LiPSs. Transition metal metal oxides such as MnO, MnO2, Fe2O3, CoO, Co3O4, NiO or CuO, etc. exhibit effective LiPSs fixation and conversion ability, due to their strong affinity with LiPSs and their electrocatalytic effect on the conversion process of sulfur-containing species. With the help of these electrocatalyst transition metal oxides, the Gibbs free energy of the redox reaction is significantly reduced, accelerating the conversion kinetics and improving the stability of the active material. Moreover, the interaction between transition metal oxide electrocatalysts and LiPSs mainly comes from sulfur binding and lithium binding, and sulfur binding is mainly caused by charge transfer between the 3d orbitals of transition metal cations and the 3p orbitals of sulfur anions, i.e. the formation of M-S chemical bonds. Therefore, the introduction of transition metal oxides into metal sulfide ore negative electrode materials as electrocatalysts can significantly improve their lithium ion storage capacity.

[0019] The present application has the following technical effects: (1) The present application obtains the natural sulfur ore M 2 O z nanosheet by chemical precipitation and heat treatment method, which anchors the transition metal oxide M 1 x S y The "hot effect" is beneficial, forming M 1 -S-M 2 chemical bonds, promoting faster ion transport, and moreover, dissolved high-order polysulfides LiPSs are effectively captured and catalytically converted into Li2S, thereby greatly improving the lithium ion storage capacity.

[0020] (2) The present application can anchor different metal oxide electrocatalysts M 2 O z on the natural sulfur ore M 1 x S y (metal sulfide) by chemical precipitation and heat treatment method, forming M 1 x S y @M 2 O zComposite materials. Due to the strong interaction between transition metal cations and the sulfur edges of natural sulfide mineral nanosheets that serve as a metal sulfide matrix, M 1 x S y and M 2 O z M is connected through interfacial chemical bonds 1 -SM 2 Closely connected. M 1 -SM 2 The establishment of the "bridge" helps improve electrocatalytic performance and accelerate electrochemical reaction kinetics. In addition, the introduced transition metal oxide electrocatalyst can capture soluble LiPSs and prevent the aggregation of metal sulfide nanosheets during charge-discharge cycling, thereby improving cycle reversibility and long-term stability.

[0021] (3) M 1 x S y @M 2 O z Composite materials, as anode materials for lithium-sulfur batteries, exhibit significantly improved reversibility and stable cycling performance. For example, the MoS2@Fe2O3 sample at 5.0 A g... −1 It can still provide 637mAh g after 3000 cycles at a current density. −1 Significant capacity. Attached Figure Description

[0022] Figure 1 The MoS2@M obtained in the examples is shown. 2 O z (also known as M) 2 O z @MO z XRD patterns (a) and Raman spectra (b) of the composite material; Figure 2 The MoS2@M obtained in the examples is shown. 2 O z (also known as M) 2 O z @MO z High-resolution XPS spectra of Mo 3d and S 2p in MoS2@MnO composite material (ab), high-resolution XPS spectra of Mn 2p in MoS2@MnO composite material (c), high-resolution XPS spectra of Fe 2p in MoS2@Fe2O3 composite material (d), high-resolution XPS spectra of Co 2p in MoS2@CoO composite material (e), and high-resolution XPS spectra of Ni 2p in MoS2@NiO composite material (f). Figure 3 MoS2 and the MoS2@M obtained in the examples are shown. 2 Oz (also known as M 2 O z @MO z ) composite at a current density of 2 A g -1 under the cycling performance graph (a) MoS2and MoS2@M 2 O z composite at a gradient current density (b); DETAILED DESCRIPTION

[0023] Example 1 Two grams of molybdenite nanosheets were uniformly dispersed in 30 mL of distilled water and subjected to 1 hour of ultrasonication, followed by the addition of 0.27 grams of iron nitrate nonahydrate, stirred for 1 hour to form a uniform mixture. Subsequently, 1 gram of 20.0 wt% sodium hydroxide was injected to generate a precipitate of iron hydroxide on the MoS2nanosheets. The filtered material was washed with distilled water and ethanol 3 times and dried at 80 °C for 12 hours. The dried mixture was calcined at 600 °C for 2 hours in an argon atmosphere with a heating rate of 5 °C / min, and the final product was MoS2@Fe2O3.

[0024] Example 2 Two grams of molybdenite nanosheets were uniformly dispersed in 30 mL of distilled water and subjected to 1 hour of ultrasonication, followed by the addition of 0.3 grams of manganese chloride tetrahydrate, stirred for 1 hour to form a uniform mixture. Subsequently, 1 gram of 20.0 wt% sodium hydroxide was injected to generate a precipitate of iron hydroxide on the MoS2nanosheets. The filtered material was washed with distilled water and ethanol 3 times and dried at 80 °C for 12 hours. The dried mixture was calcined at 600 °C for 2 hours in an argon atmosphere with a heating rate of 5 °C / min, and the final product was MoS2@MnO.

[0025] Example 3 Two grams of molybdenite nanosheets were uniformly dispersed in 30 mL of distilled water and subjected to 1 hour of ultrasonication, followed by the addition of 0.41 grams of cobalt nitrate hexahydrate, stirred for 1 hour to form a uniform mixture. Subsequently, 1 gram of 20.0 wt% sodium hydroxide was injected to generate a precipitate of iron hydroxide on the MoS2nanosheets. The filtered material was washed with distilled water and ethanol 3 times and dried at 80 °C for 12 hours. The dried mixture was calcined at 600 °C for 2 hours in an argon atmosphere with a heating rate of 5 °C / min, and the final product was MoS2@CoO.

[0026] Example 4 Two grams of molybdenite nanosheets were uniformly dispersed in 30 mL of distilled water and sonicated for 1 h, followed by the addition of 0.38 g of nickel sulfate hexahydrate and stirring for 1 h to form a homogeneous mixture. Subsequently, 1 g of 20.0 wt% sodium hydroxide was injected to form a nickel hydroxide precipitate on the MoS2nanosheets. The filtered material was washed with distilled water and ethanol three times and dried at 80 °C for 12 h. The dried mixture was calcined in an argon atmosphere at 600 °C with a ramp rate of 5 °C / min for 2 h, and the final product was MoS2@NiO.

[0027] Example 5 Natural pyrite was ground in a three-head grinder for 3 h, and then it was quickly ground in a vibration mill for three times, with 1 min of vibration each time, and the resulting material was a micron-sized pyrite product. Two grams of pyrite nanosheets were uniformly dispersed in 30 mL of distilled water and sonicated for 1 h, followed by the addition of 0.41 g of cobalt nitrate hexahydrate and stirring for 1 h to form a homogeneous mixture. Subsequently, 1 g of 20.0 wt% sodium hydroxide was injected to form a cobalt hydroxide precipitate on the micron-sized pyrite. The filtered material was washed with distilled water and ethanol three times and dried at 80 °C for 12 h. The dried mixture was calcined in an argon atmosphere at 600 °C with a ramp rate of 5 °C / min for 2 h, and the final product was FeS2@CoO.

[0028] The cycling performance at 2.0 A g -1 and the rate capability at a gradient current density were similar to those of MoS2@Fe2O3in Example 1.

[0029] Example 6 Natural sphalerite was ground in a three-head grinder for 3 h, and then it was quickly ground in a vibration mill for three times, with 1 min of vibration each time, and the resulting material was a micron-sized sphalerite product. Two grams of sphalerite nanosheets were uniformly dispersed in 30 mL of distilled water and sonicated for 1 h, followed by the addition of 0.38 g of nickel sulfate hexahydrate and stirring for 1 h to form a homogeneous mixture. Subsequently, 1 g of 20.0 wt% sodium hydroxide was injected to form a nickel hydroxide precipitate on the micron-sized sphalerite. The filtered material was washed with distilled water and ethanol three times and dried at 80 °C for 12 h. The dried mixture was calcined in an argon atmosphere at 600 °C with a ramp rate of 5 °C / min for 2 h, and the final product was ZnS@NiO.

[0030] The cycling performance at 2.0 A g -1 and the rate capability at a gradient current density were similar to those of MoS2@Fe2O3in Example 1.

Claims

1. A natural sulfide ore-based metal oxide electrocatalyst composite comprising natural sulfide ore microflakes and a transition metal oxide M bound thereto 2 O z wherein the transition metal M 2 is Mn, Fe, Co, Ni, Cu, Zn, V, Ti, or Cr.

2. The natural sulfide ore-based metal oxide electrocatalyst composite of claim 1, wherein, The M 2 O z is MnO, Mn02, Fe203, CoO, C03O4, NiO or CuO; The natural sulfide mineral flake is a nanoflake, and the natural sulfide mineral is selected from molybdenite, pyrite, chalcopyrite, sphalerite, chalcocite, galena, bornite, stibnite, or bismuthinite.

3. The natural sulfide ore-based metal oxide electrocatalyst composite of claim 1, wherein the natural sulfide ore M 1 x S y is intimately bound to the transition metal oxide M 2 O z through an interfacial chemical bond M 1 -S-M 2 .

4. The natural sulfidic mineral-based metal-oxide electrocatalyst composite of claim 1, wherein the transition metal oxide M 2 O z between the transition metal M 2 cation and the 3p orbitals of the sulfur anion induces the formation of M 2 -S bonds.

5. A method for preparing a natural sulfide mineral-based metal oxide electrocatalyst composite material, comprising the following steps: (1) Preparation of natural sulphide ores M 1 x S y Microflake suspensions; (2) loading metal M on a natural sulphide ore microflake 2 hydroxide; (3) heating to obtain M 1 x S y / M 2 O z complex.

6. The method of claim 5, wherein, In step (1), the natural sulfide mineral particles, particularly natural sulfide mineral microparticles, are uniformly dispersed in water and subjected to ultrasonic treatment to obtain natural sulfide mineral flakes, particularly natural sulfide mineral nanoflakes.

7. The method of claim 5, wherein, In step (2), a metal salt of the transition metal M 2 is added to the suspension of natural sulfide ore microflakes obtained in step (1), stirred to form a uniform mixture, and then an alkali solution is added to form a hydroxide precipitate of the transition metal M 2 on the natural sulfide ore microflakes.

8. The method of claim 5, wherein, In step (3), filtration is performed, the filter residue is washed with water and an alcohol solvent, and drying and calcination under an inert atmosphere are performed.

9. Use of the natural sulfide mineral-based metal oxide electrocatalyst composite material according to claim 1 as a negative electrode material for lithium-sulfur batteries.

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