A Zn with surface defects x Mn 1-x S-infinite solid solution, preparation method and its application in Li-S batteries

Abstract

This application provides a Zn with surface defects. x Mn 1‑x This paper discusses the infinite solid solution of Zn, its preparation method, and its application in Li-S batteries, belonging to the field of lithium-sulfur battery technology. x Mn 1‑x S-type infinite solid solution uses zinc, manganese, and organic sulfur sources as raw materials. The Zn content can be adjusted by regulating the ratio x of the zinc and manganese sources. x Mn 1‑x The band structure of an infinite solid solution balances redox properties and conductivity to improve the performance of lithium-sulfur batteries. Glycerol, ammonia, and organic sulfur sources restrict the mass transfer of metal cations and sulfur ions, playing a role in sulfide nucleation and growth. This allows for the formation of an infinite solid solution and results in more surface defects within the sulfide crystals, which promotes electron migration and ion adsorption, further enhancing lithium-sulfur battery performance.

Description

Technical Field

[0001] This invention belongs to the field of lithium-sulfur battery technology and relates to a Zn with surface defects. x Mn 1-x S-infinite solid solution, preparation method and its application in Li-S batteries. Background Technology

[0002] As a representative energy storage device, batteries are widely used in portable electronic products and electric transportation devices. However, factors such as cost, power, cycle life, safety and environmental compatibility have become important parameters that need to be considered.

[0003] Li-S batteries are secondary batteries that use lithium metal as the negative electrode, sulfur as the positive electrode, and the conversion mechanism is 2Li + S → Li₂S. Their theoretical specific capacity and specific energy density are as high as 1672 mAh·g⁻¹. -1 and 2600Wh·kg -1 The efficiency is more than five times higher than that of commercial lithium-ion batteries. Sulfur also boasts advantages such as abundant reserves, non-toxicity, environmental friendliness, and low cost. However, the development and application of Li-S batteries are limited by the shuttle effect of LiPSs, an intermediate product of Li-S battery charging and discharging. To address this effect, catalysts are typically introduced into Li-S batteries to improve their kinetic performance, thereby enhancing the performance of lithium-sulfur batteries.

[0004] Zn x Mn 1-x S solid solutions possess tunable band structures; by adjusting the x-value, their redox properties and electrical conductivity can be modified, thereby enhancing their catalytic performance. Zn x Mn 1-x S solid solutions possess wurtzite and zincblende-type structures, which can form surface defects. These surface defects facilitate electron migration and ion adsorption, further enhancing Zn content. x Mn 1-x The catalytic performance of S solid solution is shown. However, as the value of x decreases, manganese ions readily precipitate from the solid solution to form rock-salt-type MnS. Therefore, the synthesis of infinitely soluble Zn is hindered. x Mn 1-x S solid solutions are relatively difficult to synthesize, and the synthesis of Zn with surface defects is also challenging. x Mn 1-x S solid solutions are also relatively difficult to obtain. Summary of the Invention

[0005] The purpose of this invention is to provide a Zn with surface defects. x Mn 1-x Infinite solid solution of Zn, preparation method and its application in Li-S batteries, to solve the problem of existing methods for synthesizing Zn x Mn1-x S is a difficult problem in infinite solid solutions.

[0006] To achieve the above objectives, the present invention adopts the following technical solution: Firstly, this application provides a Zn with surface defects. x Mn 1-x S is an infinite solid solution of Zn. x Mn 1-x S-infinite solid solution is a nanosphere formed by clusters of short rod-shaped structures, and all of the short rod-shaped structures have surface defects.

[0007] Secondly, this application provides a Zn with surface defects. x Mn 1-x A method for preparing an infinite solid solution of S, the method comprising: After glycerol and deionized water are mixed to form a glycerol / water mixture, zinc and manganese sources are dissolved in the glycerol / water mixture to form an ionic solution. After adding ammonia water to the ionic solution and mixing well, an organic sulfur source is added and stirred until well mixed to form a suspension. The suspension was reacted at 120-200℃ for 2-24 hours, and after filtration, washing, and drying, Zn was obtained. x Mn 1- x S is an infinite solid solution, where 0 <x<1。

[0008] Thirdly, this application provides a Li-S battery, which includes Zn with planar defects as described in the first aspect. x Mn 1-x S is an infinite solid solution.

[0009] Fourthly, this application provides a method for assembling a Li-S battery, the method comprising: Graphene, carbon nanotubes, and Zn from the first aspect x Mn 1-x S is a uniformly dispersed solid solution in ethanol and filtered onto a diaphragm to form a solid solution modified diaphragm. A Li-S battery is assembled by placing aluminum foil with sublimed sulfur as the positive electrode, lithium metal sheet as the negative electrode, and the solid solution modified separator as the separator in a battery case, filling it with electrolyte, and then assembling it.

[0010] The present invention has the following beneficial effects: (1) In this application, zinc source, manganese source and sulfur source are used as raw materials, and the ratio x of zinc source and manganese source can be adjusted to adjust Zn x Mn 1-xThe band structure of an infinite solid solution balances redox properties and conductivity to improve the performance of lithium-sulfur batteries. Glycerol, ammonia, and organic sulfur sources restrict the mass transfer of metal cations and sulfur ions, playing a role in sulfide nucleation and growth. This allows for the formation of an infinite solid solution and results in more surface defects within the sulfide crystals, which promotes electron migration and ion adsorption, further enhancing lithium-sulfur battery performance.

[0011] (2) Zn in this application x Mn 1-x S-infinite solid solution is a nanosphere formed by clusters of short rod-shaped structures. It has polyhedral structures of wurtzite and zinc sphalerite, and all the short rod-shaped structures have surface defects, which are conducive to promoting electron migration and ion adsorption. Attached Figure Description

[0012] Figure 1 Zn prepared in Examples 1-5 of this application x Mn 1-x XRD pattern of an infinite solid solution; Figure 2 Zn prepared in Examples 1-5 of this application x Mn 1-x SEM (scanning electron microscope) images of the infinite solid solution S; where Figures a-e are Zn prepared in Examples 1-5, respectively. x Mn 1-x SEM image of an infinite solid solution; Figure 3 Zn prepared in Examples 1-5 of this application x Mn 1-x TEM (Transmission Electron Microscope) and HRTEM (High-resolution Transmission Electron Microscopy) images of the infinite solid solution S; wherein, Figures ZMS-1 to ZMS-5 are Zn prepared in Examples 1-5 respectively. x Mn 1-x TEM images of the infinite solid solution at 500 nm; Figures ZMS-1' to ZMS-5' are Zn prepared in Examples 1-5, respectively. x Mn 1-x Figure S is a TEM image of the infinite solid solution magnified to 100 nm; Figure ZMS-3'' is the Zn prepared in Example 3. x Mn 1-x HRTEM image of the S infinite solid solution magnified to 5 nm; Figure 4 XRD patterns of the catalyst samples prepared in Comparative Examples 1-5 of this application; Figure 5 SEM images of the catalyst samples prepared in Comparative Examples 1-5 of this application; wherein, Figures a - e are SEM images of the catalyst samples prepared in Comparative Examples 1-5 in sequence, and the upper right corner image in each figure is the SEM image magnified to 200 nm; Figure 6 Performance detection images of the Li-S batteries prepared in Example 9 and Comparative Example 6 of this application. Detailed implementation manners

[0013] In the first aspect, this application provides a Zn x Mn 1-x S infinite solid solution, where 0 < x < 1. This Zn x Mn 1-x S infinite solid solution is a nanospherical flower formed by short rod-shaped structure clusters, having a polyhedral structure of wurtzite and sphalerite, and all the short rod-shaped structures have surface defects, which is beneficial to promoting the migration of electrons and the adsorption of ions.

[0014] In the second aspect, this application provides a preparation method of a Zn x Mn 1-x S infinite solid solution with surface defects, and this method includes: S01: Stir and mix glycerol and deionized water for 10 - 60 min to form a glycerol / water mixture. Dissolve a zinc source and a manganese source into the glycerol / water mixture according to the molar ratio of Zn to Mn being (1 - 10):(1 - 10) to form an ionic solution.

[0015] Glycerol has poor fluidity, is viscous, and can be miscible with water in any proportion. After the zinc source and the manganese source are dissolved into the glycerol / water mixture, glycerol can reduce the movement speed of metal cations and sulfide ions in the zinc source and the manganese source, limit the mass transfer of anions and cations, facilitate the formation of an infinite solid solution, and is also the key to forming an infinite solid solution.

[0016] In the embodiments of this application, the zinc source includes one or more of zinc acetate, zinc nitrate, zinc sulfate, and zinc chloride, and the manganese source includes one or more of manganese acetate, manganese nitrate, manganese sulfate, and manganese chloride.

[0017] SO2: Add ammonia to the ionic solution and stir thoroughly for 10-60 minutes to allow the ammonia to complex the metal cations in the ionic solution, further restricting the mass transfer of the metal cations. After stirring evenly, add an organic sulfur source to further restrict the mass transfer of anions, and stir vigorously for 10-60 minutes to allow the S in the organic sulfur source to be concentrated. 2- It combines with metal cations to form a sulfide suspension.

[0018] In the embodiments of this application, the volume ratio of glycerol, deionized water, and ammonia is (5-13):9:(1-5), and the molar ratio of the amount of organic sulfur source added to the total metal ions in the zinc and manganese sources is 1:(2-10). The organic sulfur source includes one or more of L-cysteine, thioacetamide, and thiourea.

[0019] S03: Transfer the suspension to a polytetrafluoroethylene autoclave and perform a hydrothermal reaction at 120-200℃ for 2-24 hours to allow sulfide nucleation and growth. After cooling, the solid obtained by filtration is washed with deionized water, placed in a drying oven, and dried at 60℃ to obtain Zn with surface defects. x Mn 1-x S is an infinite solid solution, where 0 <x<1。

[0020] Due to S 2- Mass transfer with metal cations is limited by glycerol, ammonia, and organic sulfur sources. Therefore, during sulfide nucleation and growth, the sulfide crystal contains numerous surface defects, which promote electron migration and ion adsorption. The Zn concentration can be adjusted by regulating the x value. x Mn 1-x The redox properties and conductivity of S-infinite solid solutions further improve the performance of lithium-sulfur batteries.

[0021] Thirdly, this application provides a Li-S battery, which includes the Zn from the first aspect. x Mn 1-x S is an infinite solid solution.

[0022] Fourthly, this application provides a method for assembling a Li-S battery, the method comprising: S01: Incorporating graphene, carbon nanotubes, and Zn from the first aspect. x Mn 1-x S is a uniformly dispersed solid solution in ethanol and filtered onto a diaphragm to form a solid solution modified diaphragm. S02: A Li-S battery is formed by placing aluminum foil with sublimed sulfur as the positive electrode, lithium metal sheet as the negative electrode, and solid solution modified membrane as the separator in a battery case, filling it with electrolyte, and then assembling it.

[0023] The technical solution of the present invention will be further explained and described below through specific embodiments.

[0024] Example 1 This application provides a Zn with surface defects. x Mn 1-x S is an infinite solid solution of Zn. x Mn 1-x Methods for preparing S-infinite solid solutions include: S101: Mix 16 mL of glycerol and 18 mL of deionized water for 20 min to form a glycerol / water mixture. Dissolve 0.02 g of zinc acetate and 0.22 g of manganese acetate in the glycerol / water mixture at a Zn:Mn molar ratio of 1:9 to form an ionic solution.

[0025] S102: Add 6 mL of ammonia water to the ionic solution and stir thoroughly for 40 min. After stirring evenly, add 0.73 g of L-cysteine ​​and stir vigorously for 10-60 min to form a sulfide suspension.

[0026] S103: The suspension was transferred to a polytetrafluoroethylene autoclave and hydrothermally reacted at 160°C for 6 hours. After cooling, the solid obtained by filtration was washed with deionized water, placed in a drying oven, and dried at 60°C to obtain Zn. x Mn 1-x S is an infinite solid solution with x = 0.1, abbreviated as ZMS-1.

[0027] Example 2 This application provides a Zn with surface defects. x Mn 1-x S is an infinite solid solution of Zn. x Mn 1-x The preparation method of the S-infinite solid solution is the same as in Example 1, except that the molar ratio of Zn to Mn is 3:7 and x is 0.3, and it is abbreviated as ZMS-2.

[0028] Example 3 This application provides a Zn with surface defects. x Mn 1-x S is an infinite solid solution of Zn. x Mn 1-x The preparation method of the S-infinite solid solution is the same as in Example 1, except that the molar ratio of Zn to Mn is 1:1 and x is 0.5, and it is abbreviated as ZMS-3.

[0029] Example 4 This application provides a Zn with surface defects. x Mn 1-x S is an infinite solid solution of Zn. x Mn1-x The preparation method of the S-infinite solid solution is the same as in Example 1, except that the molar ratio of Zn to Mn is 7:3 and x is 0.7, and it is abbreviated as ZMS-4.

[0030] Example 5 This application provides a Zn with surface defects. x Mn 1-x S is an infinite solid solution of Zn. x Mn 1-x The preparation method of the S-infinite solid solution is the same as in Example 1, except that the molar ratio of Zn to Mn is 9:1 and x is 0.9, and it is abbreviated as ZMS-5.

[0031] Example 6 This application provides a Zn with surface defects. x Mn 1-x S is an infinite solid solution of Zn. x Mn 1-x The preparation method of the S-infinite solid solution is the same as in Example 1, except that x is 0.1, and the zinc source is zinc nitrate, the manganese source is manganese nitrate, and the organic sulfur source is thioacetamide.

[0032] Example 7 This application provides a Zn with surface defects. x Mn 1-x S is an infinite solid solution of Zn. x Mn 1-x The preparation method of the S-infinite solid solution is the same as in Example 1, except that x is 0.1, and the zinc source is zinc sulfate, the manganese source is manganese sulfate, and the organic sulfur source is thiourea.

[0033] Example 8 This application provides a Zn with surface defects. x Mn 1-x S is an infinite solid solution of Zn. x Mn 1-x The preparation method of the S-infinite solid solution is the same as in Example 1, except that x is 0.1, and the zinc source is zinc chloride, the manganese source is manganese chloride, and the organic sulfur source is L-cysteine.

[0034] Example 9 This application provides a Li-S battery, the assembly method of which includes: S901: Graphene, carbon nanotubes, and Zn from Example 3 are incorporated. x Mn 1-x S is a uniformly dispersed solid solution in ethanol and filtered onto a Celgard 2500 membrane to form a solid solution modified membrane. S902: An aluminum foil with sublimed sulfur attached is placed in a battery case as a positive electrode, a lithium metal sheet is placed in a battery case as a negative electrode, and a solid solution modified membrane is placed in a battery case as a separator. The electrolyte is a 1.0M LiTFSI salt with a volume ratio of 1:1 DOL / DME as a solvent, and 2.0% LiNO3 is added as an additive. After filling the electrolyte, the battery is assembled to form a Li-S battery.

[0035] Comparative Example 1 This application provides a catalyst sample as a comparative example. The preparation method of this sample is the same as that of Example 1, except that the solvent is ethylenediamine solution, and the volume ratio of ethylenediamine to deionized water in the ethylenediamine solution is 1:5. The organic sulfur source is thioacetamide, the hydrothermal temperature is 180°C, the reaction time is 24 h, and x is 0.1, abbreviated as ZMS-a.

[0036] Comparative Example 2 This application provides a catalyst sample as a comparative example. The preparation method of the sample is the same as that of Comparative Example 1, except that the molar ratio of Zn to Mn is 3:7 and x is 0.3. It is referred to as ZMS-b.

[0037] Comparative Example 3 This application provides a catalyst sample as a comparative example. The preparation method of the sample is the same as that of Comparative Example 1, except that the molar ratio of Zn and Mn is 1:1 and x is 0.5. It is referred to as ZMS-c.

[0038] Comparative Example 4 This application provides a catalyst sample as a comparative example. The preparation method of the sample is the same as that of Comparative Example 1, except that the molar ratio of Zn to Mn is 7:3 and x is 0.7. It is referred to as ZMS-d.

[0039] Comparative Example 5 This application provides a catalyst sample as a comparative example. The preparation method of the sample is the same as that of Comparative Example 1, except that the molar ratio of Zn to Mn is 9:1 and x is 0.9. It is referred to as ZMS-e.

[0040] Comparative Example 6 This application provides a Li-S battery as a comparative example, the assembly method of which includes: D601: An aluminum foil with sublimed sulfur attached is placed in a battery case as the positive electrode, a lithium metal sheet is placed in the negative electrode, and Celgard 2500 is placed in the battery case. The electrolyte is a 1.0M LiTFSI salt with a volume ratio of 1:1 DOL / DME as the solvent, and 2.0% LiNO3 is added as an additive. After filling the electrolyte, a Li-S battery is formed.

[0041] The embodiments of this application respectively describe the Zn with surface defects prepared in Examples 1-5. x Mn 1-xThe S-type infinite solid solution was analyzed by XRD, SEM, and TEM to obtain the attached... Figure 1 -Appendix Figure 3 Meanwhile, XRD and SEM analyses were performed on the catalyst samples prepared in Comparative Examples 1-5 to obtain the attached... Figure 4 Appendix Figure 5 .

[0042] From the appendix Figure 1 As can be seen, the Zn prepared in Examples 1-5 of this application x Mn 1-x S-infinite solid solutions exhibit good crystallinity, Zn x Mn 1-x The characteristic peak of S gradually shifts to a larger angle as the x value increases, and always lies between the corresponding characteristic peaks of ZnS and MnS, which is consistent with the characteristics of solid solutions.

[0043] From the appendix Figure 2 As can be seen, the Zn prepared in Examples 1-5 of this application x Mn 1-x The S-infinite solid solution consists of nanospheres composed of short rod-shaped clusters. As the x-value increases, i.e., the zinc content increases, the size of the spheres decreases and the breakage becomes more severe.

[0044] From the appendix Figure 3 As can be seen, the Zn prepared in Examples 1-5 of this application x Mn 1-x Morphology and attachment of S infinite solid solution Figure 2 Consistent. From the magnified TEM images (ZMS-1' ~ ZMS-5') of the rod-like structures that make up the flower-shaped structure, the diameter of the rod-like structures decreases with increasing x-value, and all rod-like structures have stripe structures parallel to the cross-section, i.e., at the short red lines. These stripe structures represent surface defects at twin boundaries or phase boundaries. When attached... Figure 3 When the ZMS-3' image is magnified to the ZMS-3'' image, the stripe structure at the red short line clearly shows that this is a surface defect. This surface defect is beneficial to promoting electron migration and ion adsorption in lithium-sulfur batteries.

[0045] From the appendix Figure 4 It is evident that the catalyst samples prepared in Comparative Examples 1-5 exhibit good crystallinity. When x = 0.1, the characteristic peaks of the catalyst samples are predominantly of rock-salt type MnS. As the x value increases, the amount of rock-salt type MnS decreases, and by x = 0.9, almost no rock-salt type MnS peaks appear. When x = 0.9, the characteristic peaks of the catalyst samples are similar to those of ZnS, but shifted towards a smaller angle compared to the characteristic peaks of ZnS. This shift continues towards a smaller angle as the x value decreases, indicating that these characteristic peaks belong to ZnS. x Mn 1-xThe characteristic peaks of S solid solution. That is, the catalyst samples prepared in Comparative Examples 1-5 contain Zn... x Mn 1-x It consists of S solid solution and rock salt-type MnS, and does not form an infinite solid solution.

[0046] From the appendix Figure 5 As can be seen, in the catalyst samples prepared in Comparative Examples 1-5, the catalyst samples gradually agglomerated from separate particles into clusters as the value of x increased. When x=0.1, the catalyst sample consisted of large MnS particles of about 2 μm, with a small amount of short rod-shaped Zn particles of about 20 nm loaded on them. x Mn 1-x S. As the x value increases, the number of rod-like structures on the large particles increases, gradually covering the large particles completely, and the size of the rod-like structures gradually increases. This is consistent with the structure tested by XRD, further indicating that this method cannot form an infinite solid solution, and some Mn ions cannot enter the solid solution to form rock salt-type MnS.

[0047] After the Li-S batteries prepared in Example 9 and Comparative Example 6 were activated for 6 hours, their performance was tested, and the results were obtained. Figure 6 .

[0048] From the appendix Figure 6 As can be seen, the highest specific capacity of the Li-S battery prepared in Example 9 can reach 1243 mAh·g. -1 The initial specific capacity of the Li-S battery prepared in Comparative Example 6 was only 867 mAh·g. -1 The specific capacity is relatively low. This indicates that the Li-S battery prepared in the embodiments of this application has a high specific capacity, and Zn x Mn 1-x S solid solutions have a significant effect on improving the performance of lithium-sulfur batteries.

[0049] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A Zn with surface defects x Mn 1-x The method for preparing an infinite solid solution of S is characterized by... include: After glycerol and deionized water are mixed to form a glycerol / water mixture, zinc and manganese sources are dissolved in the glycerol / water mixture to form an ionic solution. After adding ammonia water to the ionic solution and mixing well, an organic sulfur source is added and stirred until well mixed to form a suspension. The suspension was reacted at 120-200℃ for 2-24 hours, and after filtration, washing, and drying, Zn with surface defects was obtained. x Mn 1-x S is an infinite solid solution, where 0 <x<1。 2. The Zn with surface defects according to claim 1 x Mn 1-x The method for preparing an infinite solid solution of S is characterized by... The volume ratio of the glycerol, the deionized water and the ammonia is (5-13):9:(1-5).

3. The Zn with surface defects according to claim 1 x Mn 1-x The method for preparing an infinite solid solution of S is characterized by... The molar ratio of Zn and Mn in the zinc source and the manganese source is (1-10):(1-10), and the molar ratio of the organic sulfur source to the total metal ions in the zinc source and the manganese source is 1:(2-10).

4. The Zn with surface defects according to claim 1 x Mn 1-x The method for preparing an infinite solid solution of S is characterized by... The zinc source includes one or more of zinc acetate, zinc nitrate, zinc sulfate, and zinc chloride.

5. The Zn with surface defects according to claim 1 x Mn 1-x The method for preparing an infinite solid solution of S is characterized by... The manganese source includes one or more of manganese acetate, manganese nitrate, manganese sulfate, and manganese chloride.

6. The Zn with surface defects according to claim 1 x Mn 1-x The method for preparing an infinite solid solution of S is characterized by... The organic sulfur source includes one or more of L-cysteine, thioacetamide, and thiourea.

7. Zn with surface defects prepared by the preparation method according to any one of claims 1-6 x Mn 1-x S is an infinite solid solution.

8. The Zn with surface defects according to claim 7 x Mn 1-x S is an infinite solid solution, characterized in that... The Zn x Mn 1- x S-infinite solid solution is a nanosphere formed by clusters of short rod-shaped structures, and all of the short rod-shaped structures have surface defects.

9. A Li-S battery, characterized in that, The Li-S battery includes Zn with planar defects prepared by the preparation method according to any one of claims 1-6. x Mn 1-x S is an infinite solid solution.

10. A method for assembling a Li-S battery, characterized in that, include: Zn with surface defects prepared by any one of the preparation methods described in claims 1-6, using graphene, carbon nanotubes, or the method described in any one of claims 1-6. x Mn 1-x S is a uniformly dispersed solid solution in ethanol and filtered onto a diaphragm to form a solid solution modified diaphragm. Using aluminum foil with sublimed sulfur as the positive electrode, lithium metal sheet as the negative electrode, and the solid solution modified separator as the separator, the cells are placed in a battery case, filled with electrolyte, and assembled into a Li-S battery.

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