SnSe-MS2 staggered sulfide material, preparation method, application and sodium ion battery

Abstract

The present invention discloses a SnSe-MS2 staggered sulfide material, a preparation method, an application, and a sodium ion battery. The chemical formula of the material is (SnSe) 1.15 MS2, where M is Ta and / or Nb, and the SnSe-MS2 staggered sulfide material is composed of multiple stacked MS2 layers and SnSe layers, the MS2 layers and the SnSe layers being arranged alternately, and each MS2 layer being composed of one M atomic layer and two S atomic layers alternating. The SnSe-MS2 staggered sulfide material prepared by the present invention effectively mitigates the volume expansion and Sn-Se bond breakage during the SnSe alloying process, and exhibits excellent electrochemical performance when applied to sodium-ion batteries.

Description

Technical Field

[0001] The present invention specifically relates to a SnSe-MS2 staggered-layer sulfide material, a preparation method, an application and a sodium ion battery. Background Art

[0002] Sodium ion batteries (SIBs) have been widely studied as an alternative to lithium ion batteries for low-cost large-scale energy storage. For the anode materials of SIBs, the development of traditional carbon-based materials is limited due to their limited capacity, while alloy-type anode materials (such as tin-based materials) have the advantage of high capacity and are ideal candidates for SIBs. Among them, SnSe has a strong Na + Storage activity and high theoretical specific capacity, the average charging voltage is relatively low. However, SnSe materials have the following defects during use: (1) Na x Sn / Na2Se interface is unstable, Na x Sn particles are easily coarsened, resulting in the enrichment of Na2Se during the sodium alloying process, which reduces the reversibility of the conversion reaction; (2) During the tin alloying reaction, a huge volume expansion (Sn ~ 400%) occurs, resulting in capacity decay, making it difficult to apply in practice.

[0003] To address this issue, researchers are working to construct composite electrode structures containing carbon materials. This approach aims to alleviate the continuous grain pulverization and volume expansion at high current densities, while simultaneously improving the conductivity and stability of the carbon materials while increasing the high capacity of alloy anodes. However, simply physically mixing these components introduces additional mass into the matrix and leads to side reactions, which inevitably reduces the volumetric energy density. Summary of the Invention

[0004] The technical problem solved by the present invention is to overcome the defects of SnSe materials in the prior art, such as grain pulverization and large volume changes caused by phase aggregation during use, which lead to rapid capacity decay and unsatisfactory rate capability. The present invention provides a SnSe-MS2 staggered sulfide material, a preparation method, applications, and a sodium-ion battery. The SnSe-MS2 staggered sulfide material prepared by the present invention effectively alleviates the volume expansion and Sn-Se bond breakage during the SnSe alloying process, and exhibits excellent electrochemical performance when applied to sodium-ion batteries.

[0005] The present invention uses the MS layer as a strong framework and encapsulates the Sn-Se subunits in the rigid conductive framework, thereby forming a superconducting (SnSe) with a "thousand-layer pancake" structure. 1.15 The MS2 dislocation single-phase superlattice can suppress the volume expansion and migration of Sn atoms while maintaining high capacity and fast sodiumization kinetics. Under different charge states, the Na-MS skeleton can effectively alleviate the Sn-Se bond breakage and Na xVolume expansion caused by Sn alloy formation.

[0006] The present invention solves the above technical problems through the following technical solutions:

[0007] The present invention provides a SnSe-MS2 staggered sulfide material, the chemical formula of which is (SnSe) 1.15 MS2, M is Ta and / or Nb, the SnSe-MS2 staggered sulfide material is composed of a plurality of MS2 layers and SnSe layers stacked together, the MS2 layers and the SnSe layers are arranged alternately, and each MS2 layer is composed of an M atomic layer and two S atomic layers arranged alternately.

[0008] The present invention also provides a method for preparing the SnSe-TaS2 staggered sulfide material, which comprises the following steps: subjecting a mixture of a Sn source, an M source, a Se source, an S source and an alkali metal halide to a high-temperature solid-phase reaction in a vacuum environment, naturally cooling to room temperature, and then washing and drying to obtain the SnSe-MS2 staggered sulfide material;

[0009] The temperature of the high-temperature solid-phase reaction is 800-1200° C., and the time of the high-temperature solid-phase reaction is 20-48 hours.

[0010] In the present invention, the Sn source may be a single substance Sn or a selenide containing Sn, such as SnSe. The M source may be a single substance M or a sulfide containing M, such as TaS2 or NbS2. The Se source may be a single substance Sn or SnSe. The S source may be a single substance S or a compound containing S, such as TaS2 or NbS2. As long as the molar ratio of Sn atoms, M atoms, Se atoms and S atoms meets the preset requirements, such as 1.15:1:1.15:2 (i.e., all raw materials are completely reacted), it can be. It will be understood that the Sn source and the M source may also be the S source or the Se source at the same time.

[0011] In a specific embodiment, the SnSe-MS2 staggered sulfide material is (SnSe) 1.15 TaS2, the Sn source is Sn powder, the M source is Ta powder, the Se source is Se powder, the S source is S powder, and the molar ratio of the Sn powder, the Ta powder, the Se powder and the S powder is 1.15:1:1.15:2; or, the Sn source is Sn powder, the M source and the S source are TaS2, the Se source is Se powder, and the molar ratio of the Sn powder, the TaS2 and the Se powder is 1.15:1:1.15.

[0012] In a specific embodiment, the SnSe-MS2 staggered sulfide material is (SnSe) 1.15NbS2, the Sn source is Sn powder, the M source is Nb powder, the Se source is Se powder, the S source is S powder, and the molar ratio of the Sn powder, the Nb powder, the Se powder and the S powder is 1.15:1:1.15:2.

[0013] In the present invention, the alkali metal halide salt is preferably NaCl and / or KCl, such as NaCl. The inorganic salt is used as a flux to achieve a liquid phase reaction environment, thereby effectively lowering the reaction threshold and promoting crystallization.

[0014] In the present invention, the ratio of the mass of the alkali metal halide to the sum of the masses of the Sn source, the M source, the Se source and the S source is preferably (5-10):1, such as 6:1 or 8:1.

[0015] In the present invention, the rate of heating to the temperature of the high-temperature solid-phase reaction may be 1-10° C. / min, for example, 3° C. / min.

[0016] In the present invention, the temperature of the high-temperature solid-phase reaction is preferably 800-1000°C, for example 880°C.

[0017] In the present invention, the time of the high temperature solid phase reaction is preferably 20-30 hours, for example 24 hours.

[0018] In the present invention, the water washing operation may be conventional in the art.

[0019] In the present invention, the drying temperature is generally 70-100°C, for example 80°C.

[0020] In the present invention, the drying time is generally 8-24 hours, for example 12 hours.

[0021] In the present invention, the preparation method of the SnSe-MS2 staggered sulfide material preferably includes the following steps before the high-temperature solid-phase reaction: grinding and mixing a mixture of Sn source, M source, Se source, S source and alkali metal halide to obtain a raw material powder; placing the raw material powder in a reaction tube, and vacuuming and sealing the reaction tube, and then conducting a high-temperature solid-phase reaction in a vacuum environment.

[0022] The present invention also provides an application of the aforementioned SnSe-MS2 staggered sulfide material in a sodium ion battery.

[0023] The present invention also provides a sodium ion battery, which includes a positive electrode, a negative electrode, an electrolyte and a separator, wherein the negative electrode includes the SnSe-MS2 staggered sulfide material as described above.

[0024] In the present invention, the positive electrode preferably includes a positive electrode current collector and a positive electrode active material coated on the positive electrode current collector.

[0025] The positive electrode active material is generally a layered transition metal oxide, a Prussian compound or a polyanion compound (such as Na3V2(PO4)3).

[0026] The positive electrode current collector may be conventional in the art, generally aluminum foil.

[0027] In the present invention, the negative electrode preferably includes a negative electrode current collector and a negative electrode active material coated on the negative electrode current collector, and the negative electrode active material includes the SnSe-TaS2 staggered sulfide material as described above.

[0028] The negative electrode current collector may be conventional in the art, typically aluminum foil.

[0029] In the present invention, the positive electrode or the negative electrode may further include a binder and a conductive agent.

[0030] The binder may be one or more of polyurethane, epoxy resin, polyvinylidene fluoride, carboxymethyl cellulose, styrene-butadiene rubber and polyacrylic acid.

[0031] The conductive agent may be conventional in the art, such as SuperP.

[0032] In the present invention, the electrolyte can be conventional in the art, for example, a diethylene glycol dimethyl ether solution containing 1.0 M NaPF6.

[0033] In the present invention, an insulating film having high ion permeability and mechanical strength is used as the separator. For example, an olefin-based polymer such as chemically resistant and hydrophobic polypropylene, a sheet made of glass fiber, polyethylene, or the like, or a nonwoven fabric can be used as the separator.

[0034] In the present invention, the sodium ion battery further includes a shell for loading the positive electrode, the negative electrode, and the electrolyte.

[0035] On the basis of conforming to the common sense in this field, the above-mentioned preferred conditions can be arbitrarily combined to obtain the preferred embodiments of the present invention.

[0036] The reagents and raw materials used in the present invention are commercially available.

[0037] The positive progress effect of the present invention is:

[0038] The SnSe-TaS2 staggered sulfide material prepared by the present invention effectively alleviates the volume expansion and Sn-Se bond breakage of SnSe during the alloying process, and exhibits excellent electrochemical performance when applied to sodium ion batteries. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1Schematic diagram of the structure of the prepared SnSe-MS2 staggered sulfide material;

[0040] Figure 2 (SnSe) prepared in Example 1 1.15 SEM image of TaS2 sample;

[0041] Figure 3 (SnSe) prepared in Example 1 1.15 HRTEM image of TaS2 sample;

[0042] Figure 4 (SnSe) prepared in Example 1 1.15 XRD pattern of TaS2 sample. DETAILED DESCRIPTION

[0043] The present invention is further illustrated by way of examples below, but the present invention is not limited to the scope of the examples. Experimental methods in the following examples where specific conditions are not specified were performed according to conventional methods and conditions, or selected according to the product specifications.

[0044] The raw materials used in the following examples and comparative examples were all commercially available and were not further processed before use.

[0045] Example 1

[0046] Sn powder, Ta powder, Se powder and S powder were weighed according to the stoichiometric ratio (the molar ratio of Sn:Ta:Se:S was 1.15:1:1.15:2), and NaCl (the mass of NaCl was 6 times the sum of the mass of Sn powder, Ta powder, Se powder and S powder) was added and ground uniformly to obtain a mixed powder; the mixed powder was sealed in a vacuum quartz tube and placed in a muffle furnace for calcination at a heating rate of 3°C / min, a calcination temperature of 880°C, and a calcination time of 24 hours; after naturally cooling to room temperature, the product was collected and immersed in deionized water to remove NaCl, and then dried at 80°C for 12 hours to obtain (SnSe) 1.15 TaS2 sample.

[0047] Example 2

[0048] Sn powder, Nb powder, Se powder, and S powder were weighed according to a stoichiometric ratio (the molar ratio of Sn:Nb:Se:S was 1.15:1:1.15:2), and NaCl (the mass of NaCl was 6 times the sum of the mass of Sn powder, Nb powder, Se powder, and S powder) was added and ground uniformly to obtain a mixed powder; the mixed powder was sealed in a vacuum quartz tube and placed in a muffle furnace for calcination at a heating rate of 3°C / min, a calcination temperature of 880°C, and a calcination time of 24 hours; after naturally cooling to room temperature, the product was collected and immersed in deionized water to remove NaCl, and then dried at 80°C for 12 hours to obtain (SnSe) 1.15 NbS2 sample.

[0049] Example 3

[0050] Sn powder, TaS2, and Se powder were weighed according to a stoichiometric ratio (the molar ratio of Sn:TaS2:Se was 1.15:1:1.15), and NaCl (the mass of NaCl was 6 times the sum of the mass of Sn powder, TaS2, and Se powder) was added and ground uniformly to obtain a mixed powder. The mixed powder was sealed in a vacuum quartz tube and placed in a muffle furnace for calcination at a heating rate of 3°C / min, a calcination temperature of 880°C, and a calcination time of 24 hours. After naturally cooling to room temperature, the product was collected and immersed in deionized water to remove NaCl, and then dried at 80°C for 12 hours to obtain (SnSe). 1.15 TaS2 sample.

[0051] Comparative Example 1

[0052] Sn powder and Se powder with a molar ratio of 1:1 were ground and placed in a quartz tube. The quartz tube was evacuated and sealed, and then placed in a muffle furnace for calcination at a heating rate of 3°C / min, a calcination temperature of 900°C, and a calcination time of 24 hours. After naturally cooling to room temperature, SnSe sample powder was obtained.

[0053] Comparative Example 2

[0054] Ta powder and S powder with a molar ratio of 1:2 were ground and placed in a quartz tube. The quartz tube was evacuated and sealed, and then placed in a muffle furnace for calcination at a heating rate of 3°C / min, a calcination temperature of 900°C, and a calcination time of 24 hours. After naturally cooling to room temperature, TaS2 sample powder was obtained.

[0055] Effect embodiment

[0056] (1) Morphological characterization

[0057] according to Figure 1It can be seen that the SnSe-MS2 staggered sulfide material prepared by the present invention is composed of a plurality of MS2 layers and SnSe layers stacked together, the MS2 layers and the SnSe layers are arranged alternately, and each MS2 layer is composed of one M atomic layer and two S atomic layers arranged alternately. Figure 2 It can be seen that (SnSe) 1.15 TaS2 has a flake-like morphology with micrometer-sized size; Figure 3 The HRTEM images also show that TaS2 and SnSe layers grow alternately, forming a uniform "thousand-layer pancake" structure with similar lattice arrangement.

[0058] (2) XRD test

[0059] The samples were subjected to XRD using conventional testing methods in the art, wherein XRD characterization was performed on a Bruker D8Advance diffractometer using Cu Kα radiation. carried out.

[0060] Figure 4 Showing the prepared (SnSe) 1.15 High crystallinity of TaS2 samples.

[0061] (3) Conductivity test

[0062] The temperature-dependent resistivity test was performed using a physical property measurement system (PPMS, Quantum Design). In the conductivity test, the sample powder was pressed into a square disk and silver paste was used as the contact electrode.

[0063] After testing, it is known that (SnSe) 1.15 The room temperature conductivity of TaS2 is about 2902S cm -1 , and a superconducting transition occurs at a critical temperature of about 3K, exceeding the superconducting temperature of TaS2, which is about 928S cm -1 conductivity and its superconducting transition at 2K.

[0064] (4) Electrochemical performance test

[0065] 1. The sodium storage performance of the SnSe-MS2 staggered sulfide material prepared in Examples 1-3 was evaluated by assembling CR2032 button-type batteries. The SnSe-MS2 staggered sulfide material, conductive carbon black (Super P) and sodium alginate (SA) binder were mixed in a mass ratio of 8:1:1, and deionized water was added as a solvent and stirred until uniform to form a slurry. The slurry was then evenly coated on a copper foil and dried under vacuum at 100°C for 12 hours. The average mass of active material on each disc was 1.0-1.2 mgcm -2The half-cell was assembled in an argon-filled glove box (MBRAUN-LABstar, with H2O and O2 contents less than 0.5 ppm) using a sodium disc (Canrd, 99.7%, 15.6*0.45 mm) as the counter electrode, glass fiber (GF / D, Whatman) as the separator, and a diethylene glycol dimethyl ether (DEGDME) solution containing 1.0 M NaPF6 as the electrolyte.

[0066] The sodium storage performance of SnSe-MS2 interlayer sulfide materials was studied in the voltage range of 0.01-2 V. In the half-cell, (SnSe) 1.15 The initial coulombic efficiency (ICE) of TaS2 anode is as high as 77.5%, and the average charging voltage is as low as 1V, which is much lower than other metal sulfides. -1 ) conditions, (SnSe) 1.15 The specific capacities of TaS2 anodes reached 904, 882, 803, 773, 691, 618, and 539 mAh cm, respectively. -3 , which is superior to SnSe, TaS2 and physical mixed composite materials of SnSe and TaS2 anodes. Under 15C conditions, (SnSe) 1.15 The TaS2 anode has a capacity retention of nearly 100% after 2000 cycles, with a capacity of 730 mAh cm -3 .

[0067] Table 1 Capacity after 2000 cycles at 15C

[0068]

[0069]

[0070] 2. Preparation (SnSe) 1.15 TaS2||Na3V2(PO4)3(NVP) full battery, NVP cathode was obtained from Shenzhen Kejing Hengxing Technology Co., Ltd. Using N-methyl-2-pyrrolidone (NMP) as solvent, NVP, SuperP and polyvinylidene fluoride (PVDF) were mixed in a mass ratio of 8:1:1 to prepare cathode slurry. The slurry was evenly coated on aluminum foil and dried under vacuum conditions at 100°C for 12 hours. The mass ratio of cathode to anode active material was 3:1. The electrolyte used was a diethylene glycol dimethyl ether (DEGDME) solution containing 1.0M NaPF6, and glass fiber (GF / D, Whatman) was used as a separator. The specific capacity of the full battery was calculated based on the mass of the cathode. Electrochemical test of the full battery (1C=100mAg -1 ) is performed in the voltage range of 1.0-3.5V.

[0071] The full battery achieved 117.5 / 109.4 mAh g at 0.2C. -1 The initial charge and discharge capacity is 100 mAh g, and the initial coulombic efficiency is 93.1%. The NVP cathode shows good rate capability, with a specific capacity of 102 mAh g in a 15C Hall cell. -1 The full cell showed excellent rate capability at 0.2, 0.5, 1, 2, 5, 10, and 15C (1C = 100 mA g -1 ) conditions, the discharge capacities were 107.4, 100.7, 95.2, 90.4, 84.3, 76.9, and 69.8 mAh g -1 After the formation process, the discharge capacity can reach 65.6 mAh g after 650 cycles at 15C. -1 , the capacity retention rate is close to 100%.

[0072] The full battery can power a light-emitting diode (LED) lamp. According to the time-voltage curve, the full battery can provide 183Whkg -1 The maximum energy density. Even at 2424W kg -1 At the maximum power density, the full battery can still provide 113Wh kg -1 Energy density. In addition, the full battery also has excellent low-temperature performance. The rate performance of the full battery at -20 ° C shows that the specific capacity is 80.5, 60.4, 41.4, 31.7 and 23.3 mAh g at 0.2, 0.5, 1, 1.5 and 2C, respectively. -1 Under 1C conditions, the capacity retention of the full battery after 100 cycles is close to 83%, and the capacity at -20°C is 41.5 mAh g -1 .

[0073] Although specific embodiments of the present invention have been described above, those skilled in the art will appreciate that these are merely illustrative and that the scope of the present invention is defined by the appended claims. Those skilled in the art may make various changes or modifications to these embodiments without departing from the principles and essence of the present invention, and such changes and modifications are intended to fall within the scope of the present invention.

Claims

1. A SnSe-MS2 staggered sulfide material, characterized in that: Its chemical formula is (SnSe) 1.15 MS2, M is Ta and / or Nb, the SnSe-MS2 staggered sulfide material is composed of a plurality of MS2 layers and SnSe layers stacked together, the MS2 layers and the SnSe layers are arranged alternately, and each MS2 layer is composed of an M atomic layer and two S atomic layers arranged alternately.

2. A method for preparing the SnSe-MS2 staggered sulfide material according to claim 1, characterized in that: The method comprises the following steps: subjecting a mixture of a Sn source, an M source, a Se source, an S source and an alkali metal halide to a high-temperature solid-phase reaction in a vacuum environment, naturally cooling to room temperature, washing with water, and drying to obtain the SnSe-MS2 staggered sulfide material; The temperature of the high-temperature solid-phase reaction is 800-1200° C., and the time of the high-temperature solid-phase reaction is 20-48 hours.

3. The method for preparing the SnSe-MS2 staggered sulfide material according to claim 2, wherein: The Sn source is a single substance of Sn or a selenide containing Sn; And / or, the M source is M element or M-containing sulfide; And / or, the Se source is Sn element or SnSe; And / or, the S source is a single substance of S or a compound containing S; And / or, in the mixture, the molar ratio of Sn atoms, M atoms, Se atoms and S atoms is 1.15:1:1.15:

2.

4. The method for preparing the SnSe-MS2 staggered sulfide material according to claim 3, wherein: The Sn source is SnSe; And / or, the M source is TaS2 or NbS2; And / or, the S source is TaS2 or NbS2.

5. The method for preparing the SnSe-MS2 staggered sulfide material according to claim 2, wherein: The SnSe-MS2 staggered sulfide material is (SnSe) 1.15 TaS2, the Sn source is Sn powder, the M source is Ta powder, the Se source is Se powder, the S source is S powder, and the molar ratio of the Sn powder, the Ta powder, the Se powder and the S powder is 1.15:1:1.15:2; Or, the SnSe-MS2 staggered sulfide material is (SnSe) 1.15 TaS2, the Sn source is Sn powder, the M source and the S source are TaS2, the Se source is Se powder, and the molar ratio of the Sn powder, the TaS2 and the Se powder is 1.15:1:1.15; Or, the SnSe-MS2 staggered sulfide material is (SnSe) 1.15 NbS2, the Sn source is Sn powder, the M source is Nb powder, the Se source is Se powder, the S source is S powder, and the molar ratio of the Sn powder, the Nb powder, the Se powder and the S powder is 1.15:1:1.15:

2.

6. The method for preparing the SnSe-MS2 staggered sulfide material according to claim 2, wherein: The alkali metal halide salt is NaCl and / or KCl; And / or, the ratio of the mass of the alkali metal halide to "the sum of the masses of the Sn source, the M source, the Se source and the S source" is (5-10):

1.

7. The method for preparing the SnSe-MS2 staggered sulfide material according to claim 2, wherein: The temperature of the high-temperature solid-phase reaction is 800-1000°C.

8. The method for preparing the SnSe-MS2 staggered sulfide material according to claim 2, wherein: The high temperature solid phase reaction time is 20-30h.

9. The method for preparing the SnSe-MS2 staggered sulfide material according to claim 2, wherein: Before carrying out the high-temperature solid-phase reaction, the following steps are included: grinding and mixing a mixture of Sn source, M source, Se source, S source and alkali metal halide to obtain a raw material powder; placing the raw material powder in a reaction tube, and vacuuming and sealing the reaction tube to carry out a high-temperature solid-phase reaction in a vacuum environment.

10. Use of the SnSe-MS2 staggered sulfide material according to claim 1 in a sodium ion battery.

11. A sodium ion battery, characterized in that: The invention comprises a positive electrode, a negative electrode, an electrolyte and a separator, wherein the negative electrode comprises the SnSe-MS2 staggered sulfide material according to claim 1.

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