A polymer solid electrolyte and its preparation method and application

Abstract

The present invention relates to a polymer solid electrolyte and a preparation method and application thereof. Melamine, diallyl vanillyl alcohol or diallyl gastrodin or triallyl pyrogallol and lithium salt are added to a methanol solvent, and the raw materials are vigorously stirred in an anhydrous and oxygen-free environment to dissolve the raw materials. The mixed solution obtained after the dissolution is heated to a certain temperature in an anhydrous and oxygen-free environment to perform a polymerization reaction, and the slurry after the reaction is placed in a vacuum drying oven for further post-curing, while the solvent is volatilized to obtain a polymer solid electrolyte material. The present invention improves the raw materials and key preparation process flow and the reaction conditions of each step, and accordingly forms a polymer solid electrolyte material, and the obtained solid electrolyte material has excellent ionic conductivity.

Description

Technical Field

[0001] The present invention belongs to the field of electrolyte materials for lithium ion batteries, and in particular relates to a polymer solid electrolyte and a preparation method and application thereof. Background Art

[0002] Electrolyte is one of the key materials of lithium-ion batteries. It is placed between the positive and negative electrodes of the battery and plays the role of transferring charge. Although lithium-ion batteries have been widely used in people's daily lives, because the electrolytes used are mostly traditional flammable organic liquids, they have huge safety hazards during repeated charging and discharging. In order to improve the safety performance of lithium-ion batteries, using more reliable all-solid-state electrolytes to replace liquid electrolytes has become an important choice to solve this problem. All-solid-state electrolytes have many advantages such as high energy density and no fire or explosion. Using all-solid-state batteries to replace traditional liquid batteries is in line with the future development direction of large capacity, high energy density, and high safety.

[0003] Generally speaking, all-solid-state electrolytes are divided into two categories: inorganic solid electrolytes and polymer solid electrolytes, according to differences in composition. Inorganic solid electrolytes have relatively good ionic conductivity, but they have high modulus, high brittleness, and poor processability. Polymer solid electrolytes are soft and easy to control and shape, have good processability, and have good interface compatibility with positive and negative electrodes. However, the crystallization transformation of the polymer matrix at room temperature hinders the conduction of ions in the electrolyte system, greatly restricting its practical application in lithium-ion batteries. Therefore, it is necessary to develop a polymer solid electrolyte material with high ionic conductivity. Summary of the invention

[0004] The purpose of the present invention is to provide a polymer solid electrolyte and a preparation method and application thereof, by improving the raw materials and key preparation process flow and reaction conditions of each step, a polymer solid electrolyte material with high ionic conductivity is formed accordingly.

[0005] The present invention is specifically implemented by the following technical scheme. According to a polymer solid electrolyte proposed in the present invention, melamine and diallyl vanillyl alcohol (DAVA) or diallyl gastrodin (DAGd) or triallyl pyrogallol (TAPg) and lithium salt are dissolved in methanol solvent and then subjected to polymerization reaction, followed by post-curing at a certain temperature. Specifically, the preparation process includes:

[0006] Melamine, diallylvanillyl alcohol or diallylgastrine or triallylpyrogallol and lithium salt are added to a methanol solvent, and the raw materials are dissolved by vigorous stirring in an anhydrous and oxygen-free environment. The mixed solution obtained after the dissolution is heated to a certain temperature in an anhydrous and oxygen-free environment to carry out a polymerization reaction. After the reaction is completed, the obtained slurry is placed in a vacuum drying oven for further post-curing, and the solvent is volatilized at the same time to obtain a polymer solid electrolyte.

[0007] The molecular structural formulas of diallyl vanillyl alcohol (DAVA), diallyl gastrodin (DAGd), and triallyl pyrogallol (TAPg) are as follows:

[0008]

[0009] Among them, diallylvanillyl alcohol (DAVA) and diallylgastrodin (DAGd) were synthesized by the method of EABaroncini, JF Stanzione, Incorporating allylated lignin-derivatives inthiol-ene gel-polymerelectrolytes, Int. J. Biol. Macromol. 113 (2018) 1041–1051, and triallylpyrogallol (TAPg) was synthesized by the method of Y. Uemura, T. Shimasaki, N.Teramoto, M. Shibata, Thermal and mechanical properties of bio-based polymernetworks by thiol-ene photopolymerizations ofgallic acid and pyrogallolderivatives, J. Polym. Res. 23 (2016) 1–10.

[0010] Preferably, the mass ratio of melamine to diallyl vanillyl alcohol (DAVA) or diallyl gastrodin (DAGd) or triallyl pyrogallol (TAPg) is 1:(2-10).

[0011] Preferably, the added mass of lithium salt accounts for 5-30% of the total mass of the mixed raw materials, and the mixed raw materials refer to a mixture of melamine, diallylvanillyl alcohol and lithium salt, or a mixture of melamine, diallylgastrin and lithium salt, or a mixture of melamine, triallylpyrogallol and lithium salt.

[0012] Furthermore, the heating may be performed by using an oil bath.

[0013] Preferably, the polymerization reaction temperature is 40°C to 80°C, and the reaction time is 10 to 48 h.

[0014] Preferably, the post-curing temperature is 60°C to 100°C, and the curing time is 15 to 60 h.

[0015] Furthermore, the lithium salt is at least one of lithium bis(trifluoromethanesulfonate)imide, lithium perchlorate, lithium chloride, lithium bromide, lithium trifluoromethanesulfonate, lithium hexafluorophosphate, and lithium tetrafluoroborate.

[0016] Furthermore, the ionic conductivity of the polymer solid electrolyte at 30°C is 7.11×10 -6 ~ 5.41×10 -4 S cm -1 The ionic conductivity at 60°C is 1.22×10 -4 ~ 6.22×10 -3 S cm -1 The ionic conductivity at 90°C is 4.40×10 -3 ~ 4.39×10 -2 S cm -1 .

[0017] The present invention also provides a lithium ion battery, which comprises the polymer solid electrolyte as described above.

[0018] Compared with the prior art, the present invention has obvious advantages and beneficial effects. By means of the above technical solution, the present invention can achieve considerable technical progress and practicality, and has a wide range of utilization value, and has at least the following advantages:

[0019] The present invention uses melamine to react with diallyl vanillyl alcohol (DAVA) or diallyl gastrodin (DAGd) or triallyl pyrogallol (TAPg), and improves the raw materials, key preparation process flow and reaction conditions of each step, so as to form a polymer solid electrolyte material with high ion conductivity. The reaction between melamine and diallyl vanillyl alcohol (DAVA) or diallyl gastrodin (DAGd) or triallyl pyrogallol (TAPg) is achieved by the addition reaction of -NH2 in melamine and C=C in diallyl vanillyl alcohol (DAVA) or diallyl gastrodin (DAGd) or triallyl pyrogallol (TAPg). The addition reaction of -NH2 and C=C is highly efficient, and the target product can be obtained under relatively mild conditions. The C=C of the allyl raw material will not have side reactions with each other, and the reaction selectivity is strong, so a polymer solid electrolyte material with a clear structure and a high yield can be obtained. In addition, there are three -NH2 groups linked in the melamine structure, each of which contains two active H atoms. Each active H atom can react with a C=C group, thereby obtaining a dense spatial network structure polymer matrix, which can improve the mechanical strength of the resulting polymer solid electrolyte material. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 is a curve showing the change of ionic conductivity of the polymer solid electrolyte material prepared in Example 1 with temperature;

[0021] Figure 2 is a curve showing the change of ionic conductivity of the polymer solid electrolyte material prepared in Example 2 with temperature;

[0022] Figure 3 is a curve showing the change of ionic conductivity of the polymer solid electrolyte material prepared in Example 3 with temperature;

[0023] Figure 4 is a curve showing the change of ionic conductivity of the polymer solid electrolyte material prepared in Example 4 with temperature;

[0024] Figure 5 is a curve showing the change of ionic conductivity of the polymer solid electrolyte material prepared in Example 5 with temperature;

[0025] Figure 6 is a curve showing the change of ionic conductivity of the polymer solid electrolyte material prepared in Example 6 with temperature;

[0026] Figure 7 This is a curve showing the change of ionic conductivity of the polymer solid electrolyte material prepared in Example 7 with temperature. DETAILED DESCRIPTION

[0027] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution of the present invention will be clearly and completely described below in conjunction with specific embodiments. Obviously, the described embodiments are part of the embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0028] The present invention is described in detail with specific examples below. If no specific conditions are specified in the following examples, they are all carried out according to conventional conditions or conditions recommended by the manufacturer. The raw materials and reagents used without specifying the manufacturer are all conventional products that can be purchased from the market.

[0029] The molecular structures of diallyl vanillyl alcohol (DAVA), diallyl gastrodin (DAGd), and triallyl pyrogallol (TAPg) in the following examples are as follows:

[0030]

[0031] Among them, diallylvanillyl alcohol (DAVA) and diallylgastrodin (DAGd) were synthesized by the method of the literature EABaroncini, JF Stanzione, Incorporating allylated lignin-derivatives inthiol-ene gel-polymer electrolytes, Int. J. Biol. Macromol. 113 (2018) 1041–1051, and triallylpyrogallol (TAPg) was synthesized by the method of the literature Y. Uemura, T. Shimasaki, N.Teramoto,M. Shibata, Thermal and mechanical properties of bio-based polymernetworks by thiol-ene photopolymerizations of gallic acid andpyrogallolderivatives, J. Polym. Res. 23 (2016) 1–10.

[0032] The water-free and oxygen-free environment in the following embodiments can be achieved by using double-row pipes. Those skilled in the art are familiar with the use of double-row pipes, which will not be described in detail here.

[0033] Example 1: 1 g of melamine, 2 g of diallyl vanillyl alcohol (DAVA) and 1 g of lithium bis(trifluoromethanesulfonyl)amide were added to 50 mL of methanol, and the raw materials were dissolved by vigorous stirring in an anhydrous and oxygen-free environment. The mixed solution obtained after dissolution was heated to 40°C in an oil bath in an anhydrous and oxygen-free environment for reaction for 10 h to promote the reaction of amino and allyl groups. The slurry obtained after the reaction was placed in a vacuum drying oven at 60°C for further post-curing for 15 h, and the solvent was evaporated at the same time to obtain a polymer solid electrolyte material.

[0034] Embodiment 2:

[0035] 1 g of melamine, 6 g of diallylvanillyl alcohol (DAVA) and 3 g of lithium trifluoromethanesulfonate were added to 70 mL of methanol and stirred vigorously in an anhydrous and oxygen-free environment to dissolve the raw materials. The mixed solution after dissolution was heated to 50°C in an oil bath in an anhydrous and oxygen-free environment for reaction for 12 h to promote the reaction of amino and allyl groups. The slurry obtained after the reaction was placed in a vacuum drying oven at 60°C for further post-curing for 20 h, while the solvent was evaporated to obtain a polymer solid electrolyte material.

[0036] Embodiment 3:

[0037] 1 g of melamine, 7 g of diallylvanillyl alcohol (DAVA) and 2 g of lithium tetrafluoroborate were added to 60 mL of methanol and stirred vigorously in an anhydrous and oxygen-free environment to dissolve the raw materials. The mixed solution after dissolution was heated to 60°C in an oil bath in an anhydrous and oxygen-free environment for reaction for 12 h to promote the reaction of amino and allyl groups. The slurry obtained after the reaction was placed in a vacuum drying oven at 70°C for further post-curing for 18 h, while the solvent was evaporated to obtain a polymer solid electrolyte material.

[0038] Embodiment 4:

[0039] 1 g of melamine, 10 g of diallyl gastrodin (DAGd) and 4 g of lithium hexafluorophosphate were added to 100 mL of methanol and stirred vigorously in an anhydrous and oxygen-free environment to dissolve the raw materials. The mixed solution after dissolution was heated to 80°C in an oil bath in an anhydrous and oxygen-free environment for reaction for 12 h to promote the reaction between amino and allyl groups. The slurry obtained after the reaction was placed in a vacuum drying oven at 90°C for further post-curing for 18 h, while the solvent was evaporated to obtain a polymer solid electrolyte material.

[0040] Embodiment 5:

[0041] 1 g of melamine, 4 g of diallyl gastrodin (DAGd) and 2 g of lithium tetrafluoroborate were added to 50 mL of methanol and stirred vigorously in an anhydrous and oxygen-free environment to dissolve the raw materials. The mixed solution after dissolution was heated to 80°C in an oil bath in an anhydrous and oxygen-free environment for reaction for 10 h to promote the reaction between amino and allyl groups. The slurry obtained after the reaction was placed in a vacuum drying oven at 100°C for further post-curing for 15 h, while the solvent was evaporated to obtain a polymer solid electrolyte material.

[0042] Embodiment 6:

[0043] 1 g of melamine, 8 g of triallylpyrogallol (TAPg) and 3.5 g of lithium bis(trifluoromethanesulfonyl)amide were added to 80 mL of methanol and stirred vigorously in an anhydrous and oxygen-free environment to dissolve the raw materials. The mixed solution after dissolution was heated to 60°C in an oil bath in an anhydrous and oxygen-free environment for reaction for 12 h to promote the reaction of amino and allyl groups. The slurry obtained after the reaction was placed in a vacuum drying oven at 80°C for further post-curing for 18 h, while the solvent was evaporated to obtain a polymer solid electrolyte material.

[0044] Embodiment 7:

[0045] 1 g of melamine, 7 g of triallylpyrogallol (TAPg) and 2 g of lithium tetrafluoroborate were added to 60 mL of methanol and stirred vigorously in an anhydrous and oxygen-free environment to dissolve the raw materials. The mixed solution after dissolution was heated to 40°C in an oil bath in an anhydrous and oxygen-free environment for reaction for 12 h to promote the reaction between amino and allyl groups. The slurry obtained after the reaction was placed in a vacuum drying oven at 60°C for further post-curing for 18 h, while the solvent was evaporated to obtain a polymer solid electrolyte material.

[0046] With the aid of an electrochemical workstation, the ionic conductivity of the polymer solid electrolyte membranes prepared in Examples 1 to 7 at different temperatures was tested using an AC impedance method. Specifically, the obtained polymer solid electrolyte membrane was sandwiched between two stainless steel sheets, and the thickness of the solid electrolyte membrane was measured ( L ) and conductive area ( S ). The working electrode and reference electrode of the electrochemical workstation were connected to the stainless steel sheets on both sides of the polymer solid electrolyte membrane, and the AC impedance test frequency was set to 1M-100 Hz, the sine amplitude was 10 mV, and the test temperature was 30-90 o C, temperature interval 10 o C, and the bulk resistance of the polymer solid electrolyte membrane at different temperatures was measured ( R ), using the formula σ = L / ( S×R ) The ionic conductivity of the polymer solid electrolyte membrane was calculated, and the results are shown in Table 1 and Figure 1 to Figure 7 shown.

[0047] Table 1. Ionic conductivity of polymer solid electrolytes obtained in Examples 1 to 7

[0048]

[0049] Depend on Figure 1 to Figure 7 It can be seen that the ionic conductivity of the polymer solid electrolyte prepared by the present invention is substantially linearly related to the change in temperature, indicating that the ionic conductivity of the polymer solid electrolyte material prepared by the present invention is consistent with the Nyquist equation. In addition, for the same polymer solid electrolyte, the ionic conductivity increases with increasing temperature.

[0050] Table 1 shows that the ionic conductivity of the polymer solid electrolytes of Examples 1 to 7 at 90°C is 8.44×10 -3 S cm -1 , 2.04×10 -2 S cm -1 4.60×10 -3 S cm -1 4.40×10 -3 S cm -1 , 3.14×10 -2 S cm -1 ,4.39×10 -2 S cm -1 , 1.44×10 -2 S cm -1 ; The ionic conductivity at 60°C is 1.22×10 -3 S cm -1 ,3.82×10 -3 S cm -1 , 1.00×10 -3 S cm -1 , 1.22× 10 -4 S cm -1 , 3.22×10 -3 S cm -1 , 6.22×10 -3 Scm -1 4.22×10 -3 S cm -1 , the ionic conductivity at 30°C is 4.11×10 -5 S cm -1 4.11×10 -4 S cm -1 , 1.04×10 -4 S cm -1 ,7.11×10 -6S cm -1 , 2.41×10 -4 S cm -1 , 5.41×10 -4 S cm -1 , 5.39×10 -4 S cm -1 , indicating that the polymer solid electrolyte material prepared by the present invention has excellent ionic conductivity.

[0051] The above is only an embodiment of the present invention, and does not limit the present invention in any form. The present invention can also have other forms of embodiments according to the above structures and functions, which are not listed one by one. Therefore, any simple modification, equivalent change and modification made by any technician familiar with the profession to the above embodiment according to the technical essence of the present invention without departing from the scope of the technical solution of the present invention still falls within the scope of the technical solution of the present invention.

Claims

1. A polymer solid electrolyte, characterized in that: The preparation method is as follows: 1 g of melamine, 6 g of diallyl vanillin and 3 g of lithium trifluoromethanesulfonate are added to 70 mL of methanol, and the raw materials are dissolved by vigorous stirring in an anhydrous and oxygen-free environment. The mixed solution obtained after the dissolution is heated to 50° C. in an oil bath in an anhydrous and oxygen-free environment for reaction for 12 h to promote the reaction between amino and allyl groups. The slurry obtained after the reaction is placed in a vacuum drying oven at 60° C. for further post-curing for 20 h, and the solvent is volatilized at the same time to obtain a polymer solid electrolyte material; the molecular structure of the diallyl vanillin is as follows: 。 2. The polymer solid electrolyte according to claim 1, characterized in that The ionic conductivities of the obtained polymer solid electrolyte materials at 30°C, 40°C, 50°C, 60°C, 70°C, 80°C, and 90°C are 4.41×10 -4 S cm -1 , 6.41×10 -4 S cm -1 , 0.00141 S cm -1 , 0.00382 S cm -1 , 0.00595 S cm -1 , 0.00708 S cm -1 、0.02044S cm -1 .

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