Modified pEO-based composite solid-state electrolyte, preparation method and application thereof

Abstract

The application provides a modified PEO-based composite solid-state electrolyte and a preparation method and application thereof, and the modified PEO-based composite solid-state electrolyte comprises MS2Br2, PEO and a lithium-based electrolyte, wherein the element M is at least one of Mo and Nb. The PEO-based solid-state electrolyte is modified by using MS2Br2, so that the conductivity of the PEO-based solid-state electrolyte can be effectively improved, the interface stability of the electrolyte and the negative electrode is enhanced, and then the electrical performance and the cycle performance of the solid-state electrolyte battery are improved.

Description

Technical Field

[0001] This invention belongs to the field of solid electrolytes, specifically relating to modified PEO-based composite solid electrolytes, their preparation methods, and applications. Background Technology

[0002] With continuous technological advancements and evolving market demands, battery manufacturers need to refine their products based on different types and characteristics, configuring them for appropriate applications. This requires continuous technological iteration and upgrading to drive the steady development of the battery industry. In 2020, China's lithium-ion battery production reached 18.845 billion units, a year-on-year increase of 16.68%. Polymer electrolytes, represented by PEO, were among the earliest developed solid-state electrolytes. Solid-state polymer electrolytes possess good plasticity, making it relatively easy to solve the interfacial contact problems inherent in solid-state electrolytes, thus attracting significant attention. However, polymer electrolytes themselves have low conductivity. Therefore, composite modification treatment is typically required for polymer electrolytes. Summary of the Invention

[0003] The present invention aims to solve the above-mentioned problems of the prior art, and its purpose is to provide a modified PEO-based composite solid electrolyte, its preparation method and application.

[0004] To achieve the above objectives, the present invention adopts the following technical solution:

[0005] In a first aspect, a modified PEO-based composite solid electrolyte is provided, wherein the modified PEO-based composite solid electrolyte comprises a novel high-conductivity material, PEO, and a lithium-based electrolyte, wherein the novel high-conductivity material is MS2Br2, and the element M is at least one of Mo and Nb.

[0006] Secondly, a method for preparing modified PEO-based composite solid electrolytes is provided, including:

[0007] (1) Hydrogen sulfide and hydrogen bromide are continuously introduced into a furnace containing metal oxide M and subjected to high temperature holding treatment to obtain MS2Br2, wherein element M is at least one of Mo and Nb.

[0008] (2) MS2Br2, PEO and lithium-based electrolyte are mixed and slurry is prepared. The resulting slurry is coated and dried to obtain a modified PEO-based composite solid electrolyte.

[0009] Thirdly, a solid-state battery is provided, comprising the modified PEO-based composite solid-state electrolyte described in the first aspect or the modified PEO-based composite solid-state electrolyte prepared by the preparation method described in the second aspect.

[0010] Compared with the prior art, one or more of the above technical solutions can achieve at least one of the following beneficial effects:

[0011] (1) The present invention uses MS2Br2 to modify PEO-based solid electrolyte, which can effectively improve the conductivity of PEO-based solid electrolyte, enhance the interface stability between electrolyte and negative electrode, and thus improve the electrical performance and cycle performance of solid electrolyte battery.

[0012] (2) MS2Br2 is directly synthesized by one-step synthesis method, and then combined with PEO and lithium-based electrolyte as the main components of solid electrolyte to form MS2Br2 modified PEO-based composite solid electrolyte. The preparation process is simple, the process is short, the raw materials are readily available, and it is easy to achieve large-scale production. Attached Figure Description

[0013] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0014] Figure 1 This is the XRD pattern of NbS2Br2 in Embodiment 1 of the present invention.

[0015] Figure 2 This is a SEM image of the NbS2Br2-modified PEO-based composite solid electrolyte membrane synthesized in Example 1 of this invention.

[0016] Figure 3 Cycle performance of coin cells assembled with modified solid electrolytes prepared in Examples 1-3 and Comparative Examples 1-2. Detailed Implementation

[0017] Some embodiments of the present invention provide a modified PEO-based composite solid electrolyte, which includes a novel high-conductivity material, PEO, and a lithium-based electrolyte. The novel high-conductivity material is MS2Br2, wherein element M is at least one of Mo and Nb.

[0018] In some preferred embodiments, the mass ratio of the novel highly conductive material to the total mass of PEO and lithium-based electrolyte is (5~15):100, for example, 5:100, 6:100, 7:100, 8:100, 9:100, 10:100, 11:100, 12:100, 13:100, 14:100, 15:100, etc.

[0019] In some preferred embodiments, the molar ratio of EO to lithium-based electrolyte in the PEO is 15 to 20:1, such as 15:1, 16:1, 17:1, 18:1, 19:1, 20:1, etc.

[0020] In some preferred embodiments, the lithium-based electrolyte is one or more of LiPF6, LiTFSI, LiFSI, and LiBF4.

[0021] Some embodiments of the present invention provide a method for preparing a modified PEO-based composite solid electrolyte, comprising:

[0022] (1) Hydrogen sulfide and hydrogen bromide are continuously introduced into a furnace containing metal oxide M and subjected to high temperature holding treatment to obtain MS2Br2, wherein element M is at least one of Mo and Nb.

[0023] (2) MS2Br2, PEO and lithium-based electrolyte are mixed and slurry is prepared. The resulting slurry is coated and dried to obtain a modified PEO-based composite solid electrolyte.

[0024] In some preferred embodiments, the metal oxide of M is one or both of molybdenum oxide and niobium oxide.

[0025] In some embodiments, the furnace body can be a tube furnace. Specifically, hydrogen sulfide and hydrogen bromide gases can be introduced into the tube furnace, and a magnetic boat containing metal oxides can be placed in the middle of the tube furnace.

[0026] In some preferred embodiments, the temperature of the high-temperature heat preservation treatment is 600~800℃, for example, 600℃, 650℃, 700℃, 750℃, 800℃; and the time of the high-temperature heat preservation treatment is 8~20h, for example, 8h, 10h, 12h, 15h, 18h, 20h, etc.

[0027] In some preferred embodiments, when mixing MS2Br2, PEO, and lithium-based electrolyte as raw materials to form a slurry, the solvent used is an organic solvent; the organic solvent is at least one of acetonitrile, tetrahydrofuran, or N,N-dimethylformamide.

[0028] In some embodiments, the mixing and slurry preparation using MS2Br2, PEO, and lithium-based electrolyte as raw materials includes: uniformly mixing MS2Br2 with the solid electrolyte main components PEO and lithium-based electrolyte in a solid phase, then adding an organic solvent dropwise, and continuously grinding to uniformly disperse it into a slurry.

[0029] In some embodiments, the coating may involve applying a slurry to a substrate such as a polytetrafluoroethylene (PTFE) sheet.

[0030] In some preferred embodiments, the drying is vacuum drying; the temperature of the vacuum drying is 70~90℃; and the drying time is 6~12h.

[0031] In some preferred embodiments, the flow rates of hydrogen sulfide and hydrogen bromide are each independently 10-30 mL / min. Both hydrogen bromide and hydrogen sulfide gases are introduced during the high-temperature insulation process. To remove air, they can also be introduced during the heating process, and for ease of operation, they can also be introduced during the cooling process after the high-temperature insulation treatment.

[0032] Some embodiments of the present invention provide solid-state batteries, including the aforementioned modified PEO-based composite solid-state electrolyte or the modified PEO-based composite solid-state electrolyte prepared by the aforementioned preparation method.

[0033] To facilitate understanding of the present invention, the present invention will be described more fully and in detail below with reference to the accompanying drawings and preferred embodiments, but the scope of protection of the present invention is not limited to the following specific embodiments.

[0034] Unless otherwise defined, all technical terms used herein have the same meaning as commonly understood by those skilled in the art. The technical terms used herein are for the purpose of describing particular embodiments only and are not intended to limit the scope of the invention.

[0035] Unless otherwise specified, all raw materials, reagents, instruments and equipment used in this invention can be purchased from the market or prepared by existing methods.

[0036] Example 1

[0037] A novel high-conductivity material-modified PEO-based composite solid electrolyte comprises the following steps:

[0038] (1) Hydrogen sulfide and hydrogen bromide gases were continuously introduced into a tube furnace at a flow rate of 20 mL / min. A magnetic boat containing NbO2 was placed in the middle of the tube furnace. After high-temperature holding treatment at 800℃ for 8 hours, a new high-conductivity material NbS2Br2 was obtained. The XRD pattern is shown in the figure. Figure 1 As shown;

[0039] (2) The 15g NbS2Br2 prepared in step (1) was ball-milled and mixed with 80.9g PEO and 19.1g LiFSI. After uniform mixing, a mixture was obtained. The molar ratio of repeating units in PEO to molars in LiFSI was 18:1. Then, 2L of acetonitrile was added dropwise to the mixture and continuously ground to disperse it into a slurry. The slurry was then uniformly coated onto a polytetrafluoroethylene plate and dried under vacuum at 90℃ for 8 hours to obtain a modified PEO-based composite solid electrolyte membrane. The SEM image is shown below. Figure 2 As shown.

[0040] Example 2

[0041] Modified PEO-based composite solid electrolyte, comprising the following steps:

[0042] (1) Hydrogen sulfide and hydrogen bromide are continuously introduced into a tube furnace at a flow rate of 20 mL / min. A magnetic boat containing MoO3 is placed in the middle of the tube furnace. After a high-temperature heat treatment at 700℃ for 12 h, MoS2Br2 is obtained.

[0043] (2) The 10g MoS2Br2 prepared in step (1) was ball-milled and mixed with 80.9g PEO and 19.1g LiFSI. After the mixture was homogeneous, a mixture was obtained. The ratio of the number of repeating units in PEO to the number of moles in LiFSI was 18:1. Then, 2L of acetonitrile was added dropwise to the mixture and continuously ground to make it uniformly dispersed into a slurry. The slurry was then uniformly coated onto a polytetrafluoroethylene plate and dried under vacuum at 80℃ for 10h to obtain a modified PEO-based composite solid electrolyte membrane.

[0044] Comparative Example 1

[0045] Modified PEO-based composite solid electrolyte, comprising the following steps:

[0046] 10g of nano-MoO3 was ball-milled and mixed with 80.9g of PEO and 19.1g of LiFSI to obtain a homogeneous mixture. The molar ratio of repeating units in PEO to molars in LiFSI was 18:1. Then, 2L of acetonitrile was added dropwise to the mixture, and it was continuously ground to disperse it into a slurry. This slurry was then uniformly coated onto a polytetrafluoroethylene (PTFE) plate and dried under vacuum at 80°C for 10 hours to obtain a modified PEO-based composite solid electrolyte membrane.

[0047] Comparative Example 2

[0048] 80.9g PEO and 19.1g LiFSI were ball-milled and mixed to obtain a mixture. The molar ratio of repeating units in PEO to molars in LiFSI was 18:1. Then, 2L of acetonitrile was added dropwise to the mixture and it was continuously ground to disperse it evenly into a slurry. The slurry was then uniformly coated onto a polytetrafluoroethylene plate and dried under vacuum at 80℃ for 10h to obtain a modified PEO-based composite solid electrolyte membrane.

[0049] Example 3

[0050] The only difference between this embodiment and embodiment 2 is that in step (1), the flow rate of hydrogen sulfide and hydrogen bromide is 10 mL / min, the temperature of the high-temperature heat preservation treatment is 600℃, and the duration is 20 h.

[0051] In step (2), 5g MoS2Br2 is ball-milled with 80.9g PEO and 19.1g LiFSI to obtain a mixture after uniform mixing; wherein, the ratio of the number of repeating units in PEO to the number of moles in LiFSI is 18:1.

[0052] Battery assembly is completed using the following method:

[0053] The modified PEO-based composite solid electrolyte membranes obtained in Examples 1-3 and Comparative Examples 1-2 were used as solid electrolyte components and assembled into coin cells, with Li 1.1 Mn 0.9 O2 is used as the positive electrode and lithium sheet is used as the negative electrode. The cells are placed in a glove box filled with argon atmosphere with water and oxygen content both below 0.1ppm for 4 hours to reduce the moisture adsorbed by the electrode during the transfer process. Then, they are assembled into CR2032 button cells in the glove box.

[0054] After battery assembly and aging for 12 hours, charge-discharge tests were conducted at different potentials. The battery was activated for 3 cycles at a current density of 0.1 C under a voltage of 2.7~4.5V, and then cycled 100 cycles at a current density of 1C. Cycling performance was as follows: Figure 3 As shown.

[0055] Depend on Figure 3 As can be seen from the performance comparison of the batteries in Example 2 and Comparative Examples 1-2, the battery assembled with the solid electrolyte prepared in Example 2 not only showed a significant improvement in initial discharge specific capacity but also a significant improvement in cycle performance. The cycle performance ranking was Example 2 > Comparative Example 1 > Comparative Example 2. Analysis showed that the PEO-based composite solid electrolyte membrane with nano-molybdenum oxide composite in Comparative Example 1, when assembled into a coin cell as a solid electrolyte component, could suppress PEO crystallization and enhance mechanical properties, thus improving the cycle performance compared to the battery assembled with the PEO-based solid electrolyte in Comparative Example 2. Compared to Comparative Example 1, the battery assembled with the MoS2Br2 modified solid electrolyte provided in Example 2 had superior performance. Analysis suggests this may be due to the special layered structure and properties of MoS2Br2, which can improve the ion conduction performance of solid batteries, thereby improving capacity. Furthermore, it may form an excellent SEI film in situ on the lithium metal surface during subsequent charge and discharge processes, suppressing dendrites, improving mechanical properties, enhancing interface stability, and thus improving the battery's cycle performance.

[0056] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A modified PEO-based composite solid electrolyte, characterized in that, The modified PEO-based composite solid electrolyte comprises MS2Br2, PEO, and lithium-based electrolyte, wherein element M is at least one of Mo and Nb; the mass ratio of MS2Br2 to the total mass of PEO and lithium-based electrolyte is (5~15):100; MS2Br2, PEO, and lithium-based electrolyte are mixed and slurried as raw materials, and the resulting slurry is coated and dried to obtain the modified PEO-based composite solid electrolyte.

2. The modified PEO-based composite solid electrolyte as described in claim 1, characterized in that, The molar ratio of EO to lithium-based electrolyte in the PEO is (15~20):

1.

3. The modified PEO-based composite solid electrolyte as described in claim 1, characterized in that, The lithium-based electrolyte is one or more of LiPF6, LiTFSI, LiFSI, and LiBF4.

4. The method for preparing the modified PEO-based composite solid electrolyte according to any one of claims 1 to 3, characterized in that, include: (1) Hydrogen sulfide and hydrogen bromide are continuously introduced into a furnace containing metal oxide M and subjected to high temperature holding treatment to obtain MS2Br2, wherein element M is at least one of Mo and Nb. (2) MS2Br2, PEO and lithium-based electrolyte are mixed and slurry is prepared. The resulting slurry is coated and dried to obtain a modified PEO-based composite solid electrolyte.

5. The preparation method of the modified PEO-based composite solid electrolyte as described in claim 4, characterized in that, The metal oxide of M is one or both of molybdenum oxide and niobium oxide.

6. The preparation method of the modified PEO-based composite solid electrolyte as described in claim 4, characterized in that, The high-temperature insulation treatment is performed at a temperature of 600~800℃ for a duration of 8~20 hours.

7. The preparation method of the modified PEO-based composite solid electrolyte as described in claim 4, characterized in that, When mixing MS2Br2, PEO, and lithium-based electrolyte as raw materials to prepare the slurry, the solvent used is an organic solvent; the organic solvent is at least one of acetonitrile, tetrahydrofuran, or N,N-dimethylformamide.

8. The preparation method of the modified PEO-based composite solid electrolyte as described in claim 4, characterized in that, The drying process is vacuum drying; the temperature of the vacuum drying is 70~90℃; and the drying time is 6~12 hours.

9. The preparation method of the modified PEO-based composite solid electrolyte as described in claim 4, characterized in that, The flow rates of hydrogen sulfide and hydrogen bromide are each independently 10-30 mL / min.

10. A solid-state battery, characterized in that, This includes the modified PEO-based composite solid electrolyte as described in any one of claims 1 to 3, or the modified PEO-based composite solid electrolyte prepared by the preparation method described in any one of claims 4 to 9.

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