Polyethylene oxide-based solid electrolyte membrane as well as preparation method and application thereof

Abstract

The invention belongs to the technical field of lithium ion batteries, and particularly relates to a polyethylene oxide-based solid electrolyte membrane as well as a preparation method and application thereof. According to the preparation method of the polyethylene oxide-based solid electrolyte membrane, provided by the invention, biomass polysaccharide is subjected to modification treatment and then is subjected to in-situ reaction with MOF to prepare modified biomass, and the modified biomass is used for preparing the polyethylene oxide-based solid electrolyte membrane. The solid electrolyte membrane prepared by the invention has high ionic conductivity, wide electrochemical window and good interface compatibility, and meets the requirements of lithium ion batteries with high energy density and high safety.

Description

Technical Field

[0001] This invention belongs to the field of lithium-ion battery technology, specifically relating to a polyoxyethylene solid electrolyte membrane, its preparation method, and its application. Background Technology

[0002] Traditional liquid lithium-ion batteries, due to the addition of flammable liquid organic solvents, suffer from poor safety and low energy density, making them unsuitable for the current development requirements of lithium-ion batteries with higher safety and energy density. Solid-state batteries, a new type of lithium-ion battery system that uses solid electrolytes instead of liquid electrolytes, have become the future direction of battery development due to their advantages of high safety and high energy density.

[0003] Currently, solid-state lithium-ion batteries are classified into organic polymer solid-state electrolytes, inorganic solid-state electrolytes, and composite solid-state electrolytes. Organic polymer solid-state electrolytes include polyethylene oxide (PEO), polyacrylonitrile (PAN), polyvinylidene fluoride (PVDF), and polymethyl methacrylate (PMMA), among others. PEO, the earliest of these, was widely studied in the 1970s due to its significant advantages such as simple preparation, low interfacial resistance, and good stability with metallic lithium. However, its development has been limited by problems such as low ionic conductivity at room temperature, poor electrochemical stability, and low mechanical strength.

[0004] Therefore, how to improve the performance of polyethylene oxide polymer solid electrolytes has received increasing attention. Summary of the Invention

[0005] This invention aims to at least partially solve one of the technical problems in related technologies. To this end, embodiments of this invention provide a method for preparing a polyethylene oxide solid electrolyte membrane.

[0006] The method for preparing a polyoxyethylene solid electrolyte membrane according to an embodiment of the present invention includes the following steps: (1) After oxidizing the biomass polysaccharide solution, add ethylene glycol solution for the first reaction. After the first reaction, add NaHSO3 for the second reaction. After the second reaction, dry the solution to obtain semi-modified biomass. (2) The semi-modified biomass and MOF obtained in step (1) are dispersed in a methanol solution for in-situ reaction. After the in-situ reaction is completed, the biomass is washed and dried in sequence to obtain the modified biomass. (3) The modified biomass, lithium salt, polyethylene oxide and butadiene nitrile obtained in step (2) are added to an acetonitrile solution, stirred and then poured onto a polytetrafluoroethylene mold and dried to obtain a polyethylene oxide solid electrolyte membrane.

[0007] The advantages and technical effects of the preparation method of the polyoxyethylene solid electrolyte membrane in this invention are as follows: 1. In the method of this invention, after biomass polysaccharides and MOF are grown together in situ, the sulfonic acid groups of the biomass polysaccharides can promote the migration of lithium ions in the MOF porous material; 2. The modified biomass obtained by the method of this invention can, on the one hand, form strong hydrogen bonds with PEO solid electrolyte, effectively improving the mechanical strength of the solid electrolyte membrane, inhibiting the growth of lithium dendrites, and improving interfacial compatibility; on the other hand, due to the sulfonic acid functional groups contained on the surface of the modified biomass, it has Lewis acid-base interaction. The use of a one-dimensional ion channel structure reduces the crystallinity of polyethylene oxide, improves lithium-ion transport capacity, and also enhances the electrochemical stability of the polyethylene oxide solid electrolyte. 3. The method of this embodiment adds modified biomass to prepare a solid electrolyte membrane, allowing the sulfonic acid groups and the amino groups of the MOF to synergistically enhance the membrane. This not only gives the prepared modified biomass polyethylene oxide cyclic solid electrolyte membrane high ionic conductivity, a wide electrochemical window, and good interfacial compatibility, meeting the requirements of high energy density and high safety lithium-ion batteries, but also ensures that the biomass raw materials used in its preparation are readily available, inexpensive, and simple to synthesize.

[0008] In some embodiments, in step (1), the biomass polysaccharide includes at least one of cellulose, hemicellulose, or lignin; And / or, in step (1), the concentration of the biomass polysaccharide solution is 0.5~10wt%.

[0009] In some embodiments, step (1) includes the following process: adding a biomass polysaccharide solution to an oxidant solution and performing oxidation treatment in a dark environment.

[0010] In some embodiments, the oxidant solution includes at least one of NaIO4 solution or NaClO solution, the concentration of the oxidant solution is 0.02~0.06 mol / L, and the volume ratio of the biomass polysaccharide solution to the oxidant solution is (1~10):(3~5). And / or, the oxidation treatment temperature is 10~30℃, and the oxidation treatment time is 24~48h.

[0011] In some embodiments, in step (1), the concentration of the ethylene glycol solution is 1~2 g / mL, the volume ratio of the biomass polysaccharide solution to the ethylene glycol solution is (1~10):(1~2), and the time of the first reaction is 4~10 h; And / or, in step (1), the mass ratio of the biomass polysaccharide solution to NaHSO3 is (3~6):1, the temperature of the second reaction is 30~60℃, and the time of the second reaction is 3~8 h; And / or, in step (1), the drying temperature is 40~100℃ and the drying time is 5~7 days; the drying is carried out in a vacuum environment.

[0012] In some embodiments, in step (2), the MOF is any one of UIO-67-NH2, UIO-66-NH2, NH2-MIL-125 or Zr-BTB-NH2; And / or, in step (2), the mass ratio of the semi-modified biomass to MOF is (0.5~2):(0.5~2).

[0013] In some embodiments, in step (2), the in-situ reaction time is 24-36 h, the drying temperature is 40-80°C, and the drying time is 10-15 h.

[0014] In some embodiments, in step (3), the mass ratio of the modified biomass, lithium salt, polyethylene oxide and succinic acid is (0.1~1):(0.1~1):(0.1~1):(0.1~1). And / or, in step (3), the drying process includes: first drying in a 50~80℃ ordinary oven for 0.5~1.5h, and then drying in a 40~80℃ vacuum oven for 6~24h.

[0015] This invention also provides a polyoxyethylene solid electrolyte membrane, which is prepared using the above-described preparation method.

[0016] The present invention also provides the application of the above-described polyethylene oxide solid electrolyte membrane or the polyethylene oxide solid electrolyte membrane prepared by the above-described preparation method in lithium metal solid batteries. Attached Figure Description

[0017] Figure 1 This is the electrochemical impedance spectroscopy of the polyoxyethylene solid electrolyte membrane prepared in Example 1; Figure 2 This is a symmetrical long-cycle test diagram of the polyoxyethylene solid electrolyte membrane prepared in Example 2; Figure 3 This is an electrochemical window test diagram of the polyoxyethylene solid electrolyte membrane prepared in Example 1; Figure 4 This is a rate performance curve of the polyoxyethylene solid electrolyte membrane prepared in Example 7. Detailed Implementation

[0018] Embodiments of the present invention are described in detail below, examples of which are illustrated in the accompanying drawings. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain the present invention, and should not be construed as limiting the present invention.

[0019] The method for preparing a polyoxyethylene solid electrolyte membrane according to an embodiment of the present invention includes the following steps: (1) After oxidizing the biomass polysaccharide solution, add ethylene glycol solution for the first reaction. After the first reaction, add NaHSO3 for the second reaction. After the second reaction, dry the solution to obtain semi-modified biomass. (2) The semi-modified biomass and MOF obtained in step (1) are dispersed in a methanol solution for in-situ reaction. After the in-situ reaction is completed, the biomass is washed and dried in sequence to obtain the modified biomass. (3) The modified biomass, lithium salt, polyethylene oxide and butadiene nitrile obtained in step (2) are added to an acetonitrile solution, stirred and then poured onto a polytetrafluoroethylene mold and dried to obtain a polyethylene oxide solid electrolyte membrane.

[0020] The method for preparing a polyoxyethylene alkyl solid electrolyte membrane according to this invention involves in-situ growth of biomass polysaccharides and MOFs. The sulfonic acid groups in the biomass polysaccharides promote lithium ion migration within the MOF porous material. The modified biomass obtained by this method can, on the one hand, form strong hydrogen bonds with the PEO solid electrolyte, effectively improving the mechanical strength of the solid electrolyte membrane, inhibiting lithium dendrite growth, and enhancing interfacial compatibility. On the other hand, the sulfonic acid functional groups on the surface of the modified biomass exhibit Lewis acid-base interactions and a one-dimensional ion channel structure. This reduces the crystallinity of polyethylene oxide, improves lithium-ion transport capacity, and enhances the electrochemical stability of the polyethylene oxide solid electrolyte. The method in this embodiment of the invention adds modified biomass to prepare a solid electrolyte membrane, allowing the sulfonic acid groups and the amino groups of the MOF to synergistically interact. This not only gives the prepared modified biomass polyethylene oxide cyclic solid electrolyte membrane high ionic conductivity, a wide electrochemical window, and good interfacial compatibility, meeting the requirements of high energy density and high safety lithium-ion batteries, but also ensures that the biomass raw materials used in its preparation are readily available, inexpensive, and simple to synthesize.

[0021] In the preparation of semi-modified biomass, the biomass polysaccharide solution is oxidized and then reacted with ethylene glycol. The benzene ring in the biomass polysaccharide is opened, and its hydroxyl groups are oxidized to aldehyde groups. When NaHSO3 is added, the aldehyde groups are reduced to hydroxyl groups, and sodium sulfite is also connected to the carbon element of the opened benzene ring to obtain semi-modified biomass containing sulfonic acid groups. The semi-modified biomass and MOF are then reacted in situ to finally obtain modified biomass with amino and sulfonic acid groups.

[0022] In some embodiments, preferably, in step (1), the biomass polysaccharide includes at least one of cellulose, hemicellulose, or lignin. The biomass polysaccharides selected in these embodiments are widely available and have advantages such as being renewable, non-toxic, and low-cost.

[0023] In some embodiments, preferably, in step (1), the concentration of the biomass polysaccharide solution is 0.5~10 wt%. More preferably, the concentration of the biomass polysaccharide solution is 0.5~5 wt%. More preferably, the concentration of the biomass polysaccharide solution is 0.5~3 wt%.

[0024] In some embodiments, preferably, in step (1), the oxidation treatment includes the following process: adding the biomass polysaccharide solution to the oxidant solution and performing the oxidation treatment in a dark environment.

[0025] In some embodiments, preferably, the oxidant solution includes at least one of NaIO4 solution or NaClO solution, the concentration of the oxidant solution is 0.02~0.06 mol / L, and the volume ratio of the biomass polysaccharide solution to the oxidant solution is (1~10):(3~5). And / or, the oxidation treatment temperature is 10~30℃, and the oxidation treatment time is 24~48h. More preferably, the oxidation treatment temperature is 15~30℃.

[0026] In some embodiments, preferably, in step (1), the concentration of the ethylene glycol solution is 1~2 g / mL, the volume ratio of the biomass polysaccharide solution to the ethylene glycol solution is (1~10):(1~2), and the time for the first reaction is 4~10 h. More preferably, the volume ratio of the biomass polysaccharide solution to the ethylene glycol solution is (1~1.5):1.

[0027] In this embodiment of the invention, the volume ratio of biomass polysaccharide solution to ethylene glycol solution is limited to ensure that the reaction proceeds in proportion; if too much ethylene glycol is used, the residual ethylene glycol will affect the experimental results; if too little ethylene glycol is used, the reaction will be incomplete.

[0028] In some embodiments, preferably, in step (1), the mass ratio of the biomass polysaccharide solution to NaHSO3 is (3~6):1, the temperature of the second reaction is 30~60℃, and the time of the second reaction is 3~8 h; And / or, in step (1), the drying temperature is 40~100℃ and the drying time is 5~7 days; the drying is carried out in a vacuum environment.

[0029] In this embodiment of the invention, the mass ratio of biomass polysaccharide solution to NaHSO3 is limited to ensure that the reaction proceeds in proportion. If too much NaHSO3 is used, the residual NaHSO3 will affect the experimental results. If too little NaHSO3 is used, the biomass polysaccharide solution cannot be completely oxidized.

[0030] In some embodiments, preferably, in step (2), the MOF is any one of UIO-67-NH2, UIO-66-NH2, NH2-MIL-125 or Zr-BTB-NH2; And / or, in step (2), the mass ratio of the semi-modified biomass to MOF is (0.5~2):(0.5~2). More preferably, the mass ratio of the semi-modified biomass to MOF is (1~2):1.

[0031] In this embodiment of the invention, the mass ratio of semi-modified biomass to MOF is limited so that the prepared electrolyte membrane has a high ionic conductivity. If the amount of semi-modified biomass is too large, the ionic conductivity of the final membrane will be too small. If the amount of semi-modified biomass is too small, the ionic conductivity of the final membrane will also be too small.

[0032] In some embodiments, preferably, in step (2), the in-situ reaction time is 24-36 h, the drying temperature is 40-80 °C, and the drying time is 10-15 h.

[0033] In some embodiments, preferably, in step (3), the mass ratio of the modified biomass, lithium salt, polyethylene oxide and succinic acid is (0.1~1):(0.1~1):(0.1~1):(0.1~1). And / or, in step (3), the drying process includes: first drying in a 50~80℃ ordinary oven for 0.5~1.5h, and then drying in a 40~80℃ vacuum oven for 6~24h.

[0034] This invention also provides a polyoxyethylene solid electrolyte membrane, which is prepared using the above-described preparation method.

[0035] The present invention also provides the application of the above-described polyethylene oxide solid electrolyte membrane or the polyethylene oxide solid electrolyte membrane prepared by the above-described preparation method in lithium metal solid batteries.

[0036] The technical solution of the present invention will now be described in detail with reference to specific embodiments and accompanying drawings.

[0037] Example 1 (1) Take 50 mL of 0.5%wt. cellulose solution (the mass of cellulose solution is 49.9 g) and pour it into 50 mL of 0.02 M NaIO4 solution. Stir for 24 h in the dark at 20 °C to complete the oxidation. Then add 10 mL of 1.111 g / mL ethylene glycol solution and react for 6 h. Then add 10 g NaHSO3 and react at 50 °C for 5 h. Pour the final prepared solution into a petri dish and dry it in a vacuum drying oven at 60 °C for 5 days to obtain semi-modified biomass. (2) Take 1g of semi-modified biomass and 1g of UIO-67-NH2 and add them to 40mL of methanol solution and react for 48h. Then wash the mixed solution and finally put it into a 60℃ oven to dry for 12h to obtain modified biomass. (3) Take 1g of modified biomass, 0.1g of LITFSI, 0.1g of PEO and 1g of succinate and add them to 20mL of acetonitrile solution and stir for 12h. Pour the stirred solution onto a polytetrafluoroethylene mold and put it into an 80℃ ordinary oven for 1.5h, and then put it into an 80℃ vacuum oven for 24h to obtain a polyoxyethylene solid electrolyte film containing modified biomass.

[0038] Example 2 (1) Take 50 mL of 0.5%wt. hemicellulose solution (the mass of hemicellulose solution is 49.8 g) and pour it into 50 mL of 0.04 M NaIO4 solution. Stir for 24 h in the dark at 20 °C to complete the oxidation. Then add 10 mL of 1.111 g / mL ethylene glycol solution and react for 6 h. Then add 9 g of NaHSO3 and react at 50 °C for 5 h. Pour the final prepared solution into a petri dish and dry it in a vacuum drying oven at 60 °C for 5 days to obtain semi-modified biomass. (2) Take 1g of semi-modified biomass and 1g of UIO-66-NH2 and add them to 40mL of methanol solution and react for 48h. Then wash the mixed solution and finally put it into a 60℃ oven to dry for 12h to obtain modified biomass. (3) Take 1g of modified biomass, 1g of LITFSI, 0.1g of PEO and 1g of succinic acid and add them to 20mL of acetonitrile solution and stir for 12h. Pour the stirred solution onto a polytetrafluoroethylene mold and put it into a 60℃ ordinary oven to dry for 1.5h, and then put it into an 80℃ vacuum oven to dry for 24h to obtain a polyoxyethylene solid electrolyte film containing modified biomass.

[0039] Example 3 (1) Take 50 mL of lignin solution with a concentration of 1.21%wt. (the mass of the lignin solution is 50.3 g) and pour it into 50 mL of 0.06 M NaClO solution. Stir for 24 h in the dark at 20 °C to complete the oxidation. Then add 10 mL of ethylene glycol solution with a concentration of 1.111 g / mL and react for 6 h. Then add 10 g of NaHSO3 and react for 5 h at 50 °C. Pour the final prepared solution into a petri dish and dry it in a vacuum drying oven at 60 °C for 5 days to obtain semi-modified biomass. (2) Take 1g of semi-modified biomass and 1g of UIO-66-NH2 and add them to 40mL of methanol solution and react for 24h. Then wash the mixed solution and finally put it into a 60℃ oven to dry for 12h to obtain modified biomass. (3) Take 1g of modified biomass, 0.41g of LITFSI, 0.1g of PEO and 1g of succinate and add them to 20mL of acetonitrile solution and stir for 12h. Pour the stirred solution onto a polytetrafluoroethylene mold and put it into a 60℃ ordinary oven to dry for 1.5h, and then put it into a 60℃ vacuum oven to dry for 24h to obtain a polyoxyethylene solid electrolyte film containing modified biomass.

[0040] Example 4 (1) Take 20 mL of cellulose solution with a concentration of 1.21%wt. (the mass of the cellulose solution is 19.9 g) and pour it into 50 mL of 0.04 M NaIO4 solution. Stir for 24 h in the dark at 20 °C to complete the oxidation. Then add 20 mL of ethylene glycol solution with a concentration of 1.111 g / mL and react for 6 h. Then add 4.5 g of NaHSO3 and react at 50 °C for 5 h. Pour the final prepared solution into a petri dish and dry it in a vacuum drying oven at 60 °C for 5 days to obtain semi-modified biomass. (2) Take 1g of semi-modified biomass and 0.8g of UIO-66-NH2 and add them to 40mL of methanol solution and react for 24h. Then wash the mixed solution and finally put it into a 60℃ oven to dry for 12h to obtain modified biomass. (3) Take 0.5g of modified biomass, 0.41g of LITFSI, 1g of PEO and 0.23g of succinic acid and add them to 30mL of acetonitrile solution and stir for 12h. Pour the stirred solution onto a polytetrafluoroethylene mold, put it in a 60℃ ordinary oven and bake for 1h, then put it in a 55℃ vacuum oven and bake for 12h to obtain a polyoxyethylene solid electrolyte film containing modified biomass.

[0041] Example 5 (1) Take 30 mL of lignin solution with a concentration of 1.21%wt. (the mass of the lignin solution is 30.2 g) and pour it into 50 mL of 0.06 M NaIO4 solution. Stir for 48 h in the dark at 20 °C to complete the oxidation. Then add 20 mL of ethylene glycol solution with a concentration of 1.111 g / mL and react for 6 h. Then add 5.5 g of NaHSO3 and react at 50 °C for 5 h. Pour the final prepared solution into a petri dish and dry it in a vacuum drying oven at 60 °C for 5 days to obtain semi-modified biomass. (2) Take 1g of semi-modified biomass and 0.8g of NH2-MIL-125 and add them to 40mL of methanol solution and react for 24h. Then wash the mixed solution and finally put it into a 60℃ oven to dry for 12h to obtain modified biomass. (3) Take 0.8 g of modified biomass, 0.41 g of LITFSI, 1 g of PEO and 0.23 g of succinic acid and add them to 30 mL of acetonitrile solution and stir for 12 h. Pour the stirred solution onto a polytetrafluoroethylene mold, put it in a 60 °C ordinary oven and bake for 1 h, then put it in a 55 °C vacuum oven and bake for 12 h to obtain a polyoxyethylene solid electrolyte film containing modified biomass.

[0042] Example 6 (1) Take 40 mL of a 1.01% wt. hemicellulose solution (the mass of the hemicellulose solution is 40.2 g) and pour it into 50 mL of 0.06 M NaClO solution. Stir for 48 h in the dark at 20 °C to complete the oxidation. Then add 20 mL of 1.111 g / mL ethylene glycol solution and react for 6 h. Then add 7.5 g of NaHSO3 and react at 50 °C for 5 h. Pour the final prepared solution into a petri dish and dry it in a vacuum drying oven at 60 °C for 5 days to obtain semi-modified biomass. (2) Take 1g of semi-modified biomass and 0.8g of Zr-BTB-NH2 and add them to 40mL of methanol solution and react for 24h. Then wash the mixed solution and finally put it into a 60℃ oven to dry for 12h to obtain modified biomass. (3) Take 0.8 g of modified biomass, 0.48 g of LITFSI, 1 g of PEO and 0.32 g of succinic acid and add them to 30 mL of acetonitrile solution and stir for 12 h. Pour the stirred solution onto a polytetrafluoroethylene mold and put it into a 60 °C ordinary oven to dry for 1.5 h, and then put it into a 55 °C vacuum oven to dry for 12 h to obtain a polyoxyethylene solid electrolyte film containing modified biomass.

[0043] Example 7 (1) Take 40 mL of cellulose solution with a concentration of 1.01%wt. (the mass of the cellulose solution is 40.1 g) and pour it into 50 mL of 0.06 M NaClO solution. Stir for 48 h in the dark at 20 °C to complete the oxidation. Then add 20 mL of ethylene glycol solution with a concentration of 1.111 g / mL and react for 6 h. Then add 7.5 g of NaHSO3 and react at 50 °C for 5 h. Pour the final prepared solution into a petri dish and dry it in a vacuum drying oven at 60 °C for 5 days to obtain semi-modified biomass. (2) Take 1g of semi-modified biomass and 0.8g of Zr-BTB-NH2 and add them to 40mL of methanol solution and react for 24h. Then wash the mixed solution and finally put it into a 60℃ oven to dry for 12h to obtain modified biomass. (3) Take 0.8 g of modified biomass, 0.48 g of LITFSI, 1 g of PEO and 0.32 g of succinic acid and add them to 30 mL of acetonitrile solution and stir for 12 h. Pour the stirred solution onto a polytetrafluoroethylene mold and put it into a 60 °C ordinary oven to dry for 1.5 h, and then put it into a 65 °C vacuum oven to dry for 12 h to obtain a polyoxyethylene solid electrolyte film containing modified biomass.

[0044] Example 8 (1) Take 40 mL of cellulose solution with a concentration of 1.01%wt. (the mass of the cellulose solution is 40.1 g) and pour it into 50 mL of 0.06 M NaClO solution. Stir for 48 h in the dark at 20 °C to complete the oxidation. Then add 20 mL of ethylene glycol solution with a concentration of 1.111 g / mL and react for 6 h. Then add 8.5 g of NaHSO3 and react at 50 °C for 5 h. Pour the final prepared solution into a petri dish and dry it in a vacuum drying oven at 60 °C for 5 days to obtain semi-modified biomass. (2) Take 1g of semi-modified biomass and 0.8g of NH2-MIL-125 and add them to 40mL of methanol solution and react for 24h. Then wash the mixed solution and finally put it into a 60℃ oven to dry for 12h to obtain modified biomass. (3) Take 0.8 g of modified biomass, 0.48 g of LITFSI, 1 g of PEO and 0.32 g of succinic acid and add them to 30 mL of acetonitrile solution and stir for 12 h. Pour the stirred solution onto a polytetrafluoroethylene mold and put it into a 60 °C ordinary oven to dry for 1.5 h, and then put it into a 65 °C vacuum oven to dry for 12 h to obtain a polyoxyethylene solid electrolyte film containing modified biomass.

[0045] Comparative Example 1 The preparation method of this comparative example is the same as that of Example 1, except that steps (1) and (2) are omitted, and modified biomass and succinate are not added in step (3).

[0046] Comparative Example 2 The preparation method of this comparative example is the same as that of Example 1, except that steps (1) and (2) remain unchanged, and no modified biomass is added in step (3).

[0047] Comparative Example 3 The preparation method of this comparative example is the same as that of Example 1, except that steps (1) and (2) remain unchanged, and succinic acid is not added in step (3).

[0048] The performance of the polyoxyethylene solid electrolyte films containing modified biomass prepared in Examples 1-8 and Comparative Examples 1-3 was tested.

[0049] (1) Ionic conductivity The modified biomass-containing polyethylene oxide solid electrolyte membranes prepared in Examples 1-8 and Comparative Examples 1-3 were assembled into stainless steel|electrolyte membrane|stainless steel coin cells, and their electrochemical impedance spectroscopy was tested. The results are shown in Table 1. The electrochemical impedance spectroscopy of the modified biomass polyethylene oxide solid electrolyte membrane prepared in Example 1 is shown below. Figure 1 As shown. According to Figure 1 It can be seen that the modified biomass polyoxyethylene solid electrolyte membrane prepared in Example 1 has a large electrochemical impedance in the temperature range of 25~60℃, and its room temperature ionic conductivity is 0.017 ms / cm.

[0050] (2) Symmetrical long-cycle test diagram The modified biomass-containing polyethylene oxide solid electrolyte membranes prepared in Examples 1-8 and Comparative Examples 1-3 were assembled into lithium-ion coin cells (lithium-ion membrane-lithium-ion membrane). Cycle test times were then performed, and the results are shown in Table 1. Figure 2 This is a symmetrical long-cycle test diagram of the modified biomass polyoxyethylene solid electrolyte membrane prepared in Example 2. Figure 2 It can be seen that the cycle time of the solid electrolyte membrane in Example 2 exceeds 600 hours.

[0051] (3) Electrochemical window The modified biomass-containing polyethylene oxide solid electrolyte membranes prepared in Examples 1-8 and Comparative Examples 1-3 were assembled into lithium-ion battery-electrolyte-membrane-stainless steel coin cells, and their electrochemical windows were tested. The results are shown in Table 1. Figure 3 This is an electrochemical window test diagram of the modified biomass solid electrolyte membrane prepared in Example 1. (From...) Figure 3 It can be seen that the electrochemical window of the solid electrolyte membrane in Example 1 is 4.8 V.

[0052] (4) Ratio performance test The modified biomass-containing polyethylene oxide solid electrolyte membranes prepared in Examples 1-8 and Comparative Examples 1-3 were assembled into Li|electrolyte membrane|LiFePO4 asymmetric coin cells, and their rate performance was tested. The results are shown in Table 1. Figure 4 This is a rate performance curve obtained from the modified biomass polyethylene oxide solid electrolyte membrane in Example 7. From... Figure 4 As can be seen, at discharge rates of 0.1C, 0.2C, 0.3C, 0.5C, and 1C, the discharge specific capacity is 149.37mAh / g, 146.68mAh / g, 141.44mAh / g, 128.52mAh / g, and 105.35mAh / g, respectively. Moreover, when the discharge specific capacity is restored to 0.1C, the discharge specific capacity rebounds, indicating that the solid electrolyte membrane with modified biomass has good reversibility.

[0053] Table 1

[0054] As can be seen from the data in Table 1, the ionic conductivity of Examples 1-8 is significantly higher than that of Comparative Example 1. This is mainly due to the effects of the added succinic acid and the one-dimensional ion channels, sulfonic acid groups, and amino groups in the modified biomass. Succinic acid, added as a plasticizer to the solid electrolyte membrane, can reduce the crystallinity of polymer PEO and expand the amorphous region of polymer PEO. In the battery system, ion transport is accomplished through the amorphous region; expanding the amorphous region makes ion transport faster and easier, thus increasing the ionic conductivity. The sulfonic acid functional groups in the modified biomass can react with TFSI⁻ in LITFSI, anchoring TFSI⁻ and promoting Li⁻ absorption. + Transportation. Therefore, this invention effectively improves the ionic conductivity of the prepared modified biomass polyoxyethylene solid electrolyte membrane by adding modified biomass.

[0055] In Examples 1-8, the cycle time of the solid electrolyte membranes was 300 hours or more. It can be seen that the activation energy of the solid electrolyte membrane with modified biomass is low. This is because the sulfonic acid groups in the modified biomass can improve its interfacial compatibility, thereby enabling long-term cycle testing. Therefore, the solid electrolyte membrane with modified biomass has the longest cycle time.

[0056] In Example 1, the electrochemical window of the solid electrolyte was 4.8 V, while in Comparative Example 2, the electrochemical window of the solid electrolyte membrane was 4.5 V. This indicates that the solid electrolyte membrane with modified biomass has a higher electrochemical window. This is because modified biomass can improve antioxidant capacity and effectively enhance the Li... + This enhances the transport and broadens the electrochemical window, enabling the modified biomass polyoxyethylene solid electrolyte membrane to possess a wide electrochemical window.

[0057] In this invention, the terms "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., refer to a specific feature, structure, material, or characteristic described in connection with that embodiment or example, which is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0058] Although the above embodiments have been shown and described, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Any changes, modifications, substitutions and variations made to the above embodiments by those skilled in the art are within the protection scope of the present invention.

Claims

1. A method for preparing a polyoxyethylene solid electrolyte membrane, characterized in that, Includes the following steps: (1) After oxidizing the biomass polysaccharide solution, add ethylene glycol solution for the first reaction. After the first reaction, add NaHSO3 for the second reaction. After the second reaction, dry the solution to obtain semi-modified biomass. (2) The semi-modified biomass and MOF obtained in step (1) are dispersed in a methanol solution for in-situ reaction. After the in-situ reaction is completed, the biomass is washed and dried in sequence to obtain the modified biomass. (3) The modified biomass, lithium salt, polyethylene oxide and butadiene nitrile obtained in step (2) are added to an acetonitrile solution, stirred and then poured onto a polytetrafluoroethylene mold and dried to obtain a polyethylene oxide solid electrolyte membrane.

2. The method for preparing the polyoxyethylene solid electrolyte membrane according to claim 1, characterized in that, In step (1), the biomass polysaccharide includes at least one of cellulose, hemicellulose, or lignin; And / or, in step (1), the concentration of the biomass polysaccharide solution is 0.5~10wt%.

3. The method for preparing a polyoxyethylene solid electrolyte membrane according to claim 1 or 2, characterized in that, In step (1), the oxidation treatment includes the following process: adding the biomass polysaccharide solution to the oxidant solution and performing the oxidation treatment in the dark.

4. The method for preparing the polyoxyethylene solid electrolyte membrane according to claim 3, characterized in that, The oxidant solution includes at least one of NaIO4 solution or NaClO solution, the concentration of the oxidant solution is 0.02~0.06mol / L, and the volume ratio of the biomass polysaccharide solution to the oxidant solution is (1~10):(3~5). And / or, the oxidation treatment temperature is 10~30℃, and the oxidation treatment time is 24~48h.

5. The method for preparing a polyoxyethylene solid electrolyte membrane according to claim 1, characterized in that, In step (1), the concentration of the ethylene glycol solution is 1~2 g / mL, the volume ratio of the biomass polysaccharide solution to the ethylene glycol solution is (1~10):(1~2), and the time of the first reaction is 4~10h; And / or, in step (1), the mass ratio of the biomass polysaccharide solution to NaHSO3 is (3~6):1, the temperature of the second reaction is 30~60℃, and the time of the second reaction is 3~8h; And / or, in step (1), the drying temperature is 40~100℃ and the drying time is 5~7 days; the drying is carried out in a vacuum environment.

6. The method for preparing the polyoxyethylene solid electrolyte membrane according to claim 1, characterized in that, In step (2), the MOF is any one of UIO-66-NH2, UIO-66-NH2, NH2-MIL-125 or Zr-BTB-NH2; And / or, in step (2), the mass ratio of the semi-modified biomass to MOF is (0.5~2):(0.5~2).

7. The method for preparing a polyoxyethylene solid electrolyte membrane according to claim 1 or 6, characterized in that, In step (2), the in-situ reaction time is 24-36 h, the drying temperature is 40-80℃, and the drying time is 10-15 h.

8. The method for preparing a polyoxyethylene solid electrolyte membrane according to claim 1, characterized in that, In step (3), the mass ratio of the modified biomass, lithium salt, polyethylene oxide and succinic acid is (0.1~1):(0.1~1):(0.1~1):(0.1~1). And / or, in step (3), the drying process includes: first drying in a 50~80℃ ordinary oven for 0.5~1.5h, and then drying in a 40~80℃ vacuum oven for 6~24h.

9. A polyoxyethylene solid electrolyte membrane, characterized in that, It is prepared by the preparation method according to any one of claims 1 to 8.

10. The application of the polyethylene oxide solid electrolyte membrane prepared by the preparation method according to any one of claims 1 to 8 or the polyethylene oxide solid electrolyte membrane according to claim 9 in lithium-ion solid batteries.

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