High specific volume, high safety electrolyte, preparation method and supercapacitor

Abstract

The present disclosure provides a high specific capacity and high safety electrolyte, a preparation method thereof and a supercapacitor, and belongs to the technical field of supercapacitors. The high specific capacity and high safety electrolyte comprises an electrolyte salt, an organic solvent and a functional additive; the organic solvent is an ester solvent; and the functional additive has the following formula. The present disclosure develops a high-voltage and high-stability mixed solvent system and a flame-retardant electrolyte, thereby greatly improving the specific capacity and energy density of the device, and fundamentally solving the problems of volatilization, leakage and combustion of the liquid electrolyte, and achieving the synergistic optimization of high specific capacity and high safety.

Description

Technical Field

[0001] This disclosure belongs to the field of supercapacitor technology, specifically relating to a high specific capacitance, high safety electrolyte and its preparation method, and a supercapacitor. Background Technology

[0002] In recent years, with the rapid development of portable electronic devices, new energy vehicles, and large-scale energy storage systems, higher requirements have been placed on the energy density, power density, and safety performance of energy storage devices. While traditional supercapacitors offer advantages such as high power and long cycle life, their energy density is relatively low, and traditional organic electrolytes pose safety hazards such as flammability and volatility, hindering their further application. Therefore, developing supercapacitor technology that combines high specific capacitance and high safety is one of the urgent problems that needs to be solved. Summary of the Invention

[0003] This disclosure aims to at least solve one of the technical problems existing in the prior art, and to provide a high specific capacitance, high safety electrolyte and its preparation method, as well as a supercapacitor.

[0004] One aspect of this disclosure provides a high specific capacity, high safety electrolyte, comprising:

[0005] Electrolyte salts;

[0006] Organic solvent; the organic solvent is an ester solvent;

[0007] Functional additives, wherein the structural formula of the functional additives is as follows:

[0008] .

[0009] Optionally, the functional additive has a mass fraction of 1%-5% in the electrolyte.

[0010] Optionally, the organic solvent may also include sulfone solvents.

[0011] Optionally, the volume ratio of the ester solvent to the sulfone solvent is (50-70%):(30-50%).

[0012] Optionally, the ester solvent is selected from propylene carbonate;

[0013] The sulfone solvent is selected from either sulfolane or ethyl methyl sulfone.

[0014] Optionally, the electrolyte salt is selected from quaternary ammonium salts.

[0015] Optionally, the quaternary ammonium salt includes at least two of the following: ammonium methyltriethyltetrafluoroborate, N,N-dimethylpyrrolidinetetrafluoroborate, N-ethyl-N-methylpyrrolidinetetrafluoroborate, N-propyl-N-methylpyrrolidinetetrafluoroborate, and N,N-tetramethylenepyrrolidinetetrafluoroborate.

[0016] Optionally, the molar concentration of the electrolyte salt is 1-1.5 mol / L.

[0017] In another aspect, this disclosure provides a method for preparing a high-specific-capacity, high-safety electrolyte, the method comprising:

[0018] The organic solvent is dehydrated, and the electrolyte salt is vacuum dried.

[0019] Add the treated electrolyte salt to the treated organic solvent and stir to form a basic electrolyte solution;

[0020] Functional additives were added to the basic electrolyte and stirred until homogeneous to obtain the high specific capacity and high safety electrolyte described above.

[0021] In another aspect of this disclosure, a supercapacitor is provided, the supercapacitor comprising the high specific capacitance, high safety electrolyte described above.

[0022] This disclosure presents a high-specific-capacitance, high-safety electrolyte, its preparation method, and a supercapacitor. The high-specific-capacitance, high-safety electrolyte comprises: an electrolyte salt, an organic solvent, and a functional additive; wherein the organic solvent is an ester solvent; and the functional additive has the following structural formula: This disclosure significantly improves the specific capacity and energy density of devices by developing novel high-voltage, high-stability mixed solvent systems and flame-retardant electrolytes. It also fundamentally solves the problems of volatilization, leakage, and combustion of liquid electrolytes, achieving synergistic optimization of high specific capacity and high safety. Attached Figure Description

[0023] Figure 1 This is a flowchart illustrating a method for preparing a high-specific-capacity, high-safety electrolyte according to a specific embodiment of this disclosure.

[0024] Figure 2 The capacitance values ​​are for Embodiments 1-6 and Comparative Example 1 of this disclosure;

[0025] Figure 3 The capacity retention results are for Examples 1-6 and Comparative Example 1 of this disclosure. Detailed Implementation

[0026] To enable those skilled in the art to better understand the technical solutions of this disclosure, the disclosure will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are only used to explain this disclosure and represent a part of the embodiments of this disclosure, not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this disclosure without creative effort are within the protection scope of this disclosure.

[0027] One aspect of this disclosure provides a high specific capacity and high safety electrolyte, comprising: an electrolyte salt, an organic solvent, and a functional additive; wherein the organic solvent is an ester solvent; and the functional additive is 1-(3-glycidyl ether propyl)-1,1,3,3,3-pentaethoxy-1,3-disilpropane, with the following structural formula: .

[0028] It should be noted that the functional additive in this embodiment is 1-(3-glycidyl ether propyl)-1,1,3,3,3-pentaethoxy-1,3-disilpropane. This additive has silane and epoxy structures as well as ether chain structures. These groups have a synergistic effect with ester solvents, effectively improving the specific capacitance of the capacitor, while also having high safety.

[0029] In this embodiment, by synergistically using ester solvents and functional additives, the molecules of these functional additives migrate to the surface of the carbon electrode. Their silane moieties (-Si(OEt)3) undergo hydrolysis and condensation to form a robust "Si-O-Si" three-dimensional inorganic network, while the epoxy moieties undergo ring-opening polymerization to form a flexible polyether organic layer. These two layers are chemically bonded together, forming a dense, stable, and ionicly conductive organic-inorganic hybrid interface protective layer, the positive electrode electrolyte interphase (CEI) film, on the electrode surface. This CEI film completely blocks direct contact between ester solvent molecules and the electrode surface, almost completely suppressing decomposition side reactions—a crucial step in improving cycle life. Furthermore, eliminating interfacial side reactions fundamentally solves the potential bulging problem of the capacitor, improving safety. Moreover, the combined use of functional additives and ester solvents can reduce solvent viscosity. The larger size of the functional additive molecules, along with their silane moieties and ether chains, may disrupt the regular, strong interactions between ester solvent molecules, acting as a "diluent" and helping to improve ionic conductivity, thereby improving the capacitor's rate performance and power density.

[0030] In some preferred embodiments, the functional additive has a mass fraction of 1%-5% in the electrolyte, for example, preferably 1%, 2%, 3%, 4%, 5%, etc.

[0031] In some other preferred embodiments, propylene carbonate (PC) is preferred as the ester solvent. It should be noted that although PC solvent is stable, it will still slowly decompose under long-term high-voltage cycling, especially under the catalysis of carbon electrode. To address this, this embodiment uses it in conjunction with functional additives to allow the functional additive molecules to migrate to the surface of the carbon electrode, forming a dense, stable, ion-conducting organic-inorganic hybrid interface protective layer on the electrode surface. This layer can completely block the direct contact between PC molecules and the electrode surface, and almost completely suppress decomposition side reactions.

[0032] In some other preferred embodiments, the organic solvent also includes sulfone solvents. That is, the organic solvent is preferably a mixture of ester solvents and sulfone solvents to achieve a balance between high ionic conductivity and good flowability, improve rate performance, broaden the electrochemical window, suppress electrolyte decomposition at high voltages, support the supercapacitor to operate at higher voltages, and improve energy density.

[0033] As a further preferred embodiment, the volume ratio of ester solvent to sulfone solvent is (50-70%):(30-50%), for example, 70:30 is preferred.

[0034] As a further preferred option, the sulfone solvent is selected from either sulfolane or ethyl methyl sulfone.

[0035] In some other preferred embodiments, the electrolyte salt is selected from quaternary ammonium salts.

[0036] As a further preferred embodiment, the quaternary ammonium salt includes one or more of the following: methyltriethyltetrafluoroborate ammonium, N,N-dimethylpyrrolidinetetrafluoroborate ammonium, N-ethyl-N-methylpyrrolidinetetrafluoroborate ammonium, N-propyl-N-methylpyrrolidinetetrafluoroborate ammonium, and N,N-tetramethylenepyrrolidinetetrafluoroborate ammonium. In other words, the electrolyte salt is any mixture of one or more of the following quaternary ammonium salts.

[0037] As a further preferred option, the molar concentration of the electrolyte salt is 1-1.5 mol / L, for example, 1.1 mol / L, 1.2 mol / L, 1.3 mol / L, 1.4 mol / L, etc. are preferred.

[0038] As shown in Figure 1, another aspect of this disclosure provides a method S100 for preparing a high specific capacity and high safety electrolyte, specifically including the following steps S110~S130:

[0039] S110, Dehydration treatment of organic solvents, and vacuum drying treatment of electrolyte salts.

[0040] Specifically, molecular sieves can be used to dehydrate organic solvents to a moisture content of less than 10 ppm, and electrolyte salts can be vacuum dried to a moisture content of less than 50 ppm.

[0041] It should be noted that the organic solvent in step S110 is preferably an ester solvent, such as propylene carbonate (PC). In other embodiments, the organic solvent may also be a mixed solution of an ester solvent and a sulfone solvent. The volume ratio of the two is (50-70%):(30-50%).

[0042] S120. Add the treated electrolyte salt to the treated organic solvent and stir to form a basic electrolyte solution.

[0043] Specifically, in a glove box with water and oxygen content below 0.1 ppm, a mixed organic solvent is added to a volumetric flask, an electrolyte salt is added to the organic solvent, and the mixture is stirred into a homogeneous liquid as the base electrolyte.

[0044] It should be noted that the electrolyte salt in step S120 can preferably be any one or a mixture of several quaternary ammonium salts, wherein the quaternary ammonium salts include ammonium methyltriethyltetrafluoroborate, N,N-dimethylpyrrolidinetetrafluoroborate, N-ethyl-N-methylpyrrolidinetetrafluoroborate, N-propyl-N-methylpyrrolidinetetrafluoroborate, and N,N-tetramethylenepyrrolidinetetrafluoroborate. Furthermore, the molar concentration of the electrolyte salt is 1-1.5 mol / L.

[0045] S130. Add functional additives to the basic electrolyte and stir evenly to obtain a high specific capacity and high safety electrolyte.

[0046] It should be noted that the functional additive in step S130 is 1-(3-glycidyl ether propyl)-1,1,3,3,3-pentaethoxy-1,3-disilpropane, with the following structural formula: .

[0047] In the preparation process of this embodiment, by synergistically using ester solvents and functional additives, a dense, stable, and ionically conductive organic-inorganic hybrid interface protective layer, the positive electrode electrolyte interphase (CEI) film, can be formed on the electrode surface. This CEI film can completely block direct contact between ester solvent molecules and the electrode surface, almost completely suppressing decomposition side reactions, thereby improving cycle life and preventing problems such as capacitor swelling. In addition, the combined use of functional additives and ester solvents can also reduce the viscosity of the solvent, which helps to improve ionic conductivity, thereby improving the rate performance and power density of the capacitor.

[0048] In another aspect of this disclosure, a supercapacitor is proposed, which includes electrodes, a diaphragm, and an electrolyte, wherein the electrolyte is the high specific capacitance and high safety electrolyte given above.

[0049] In some preferred embodiments, the supercapacitor can be an electric double-layer supercapacitor, and the electrodes of the supercapacitor are porous activated carbon electrodes. Further, the electric double-layer supercapacitor is preferably a symmetrical supercapacitor, with both electrodes being porous activated carbon electrodes.

[0050] The following will further illustrate the high specific capacity, high safety electrolyte and its preparation method with specific embodiments:

[0051] Example 1

[0052] An electrolyte with a molar concentration of 1.2 mol / L was prepared using N,N-dimethylpyrrolidine tetrafluoroborate ammonium and methyltriethyltetrafluoroborate ammonium as electrolyte salts and propylene carbonate and sulfolane as solvents. Then, a functional additive with a mass percentage of 2% was added to the electrolyte. The structural formula of the functional additive is as described above.

[0053] The electrolyte was prepared using the following method:

[0054] Step 1: Dehydrate the organic solvent (formed by mixing propylene carbonate and sulfolane in a volume ratio of 70:30) to less than 10 ppm using a molecular sieve, and vacuum dry the electrolyte salts (N,N-dimethylpyrrolidine tetrafluoroborate ammonium and methyltriethyltetrafluoroborate ammonium) to less than 50 ppm.

[0055] Step 2: In a glove box with water and oxygen content below 0.1 ppm, add a mixed organic solvent to a volumetric flask. Add 0.8 mol / L of N,N-dimethylpyrrolidine tetrafluoroborate ammonium and 0.4 mol / L of methyltriethyltetrafluoroborate ammonium to the organic solvent, and stir until a homogeneous liquid is obtained as the basic electrolyte. Step 3: Add 2% of functional additive to the basic electrolyte and stir until homogeneous to obtain the final supercapacitor electrolyte.

[0056] Example 2

[0057] The only difference between this embodiment and Embodiment 1 is that the amount of functional additive added to the electrolyte is 3%, while the rest is the same as in Embodiment 1.

[0058] Example 3

[0059] The only difference between this embodiment and Embodiment 1 is that the amount of functional additive added to the electrolyte is 5%, otherwise it is the same as Embodiment 1.

[0060] Example 4

[0061] An electrolyte with a molar concentration of 1.3 mol / L was prepared using N,N-dimethylpyrrolidine tetrafluoroborate ammonium and methyltriethyltetrafluoroborate ammonium as electrolyte salts and propylene carbonate and sulfolane as solvents. Then, a functional additive with a mass percentage of 2% was added to the electrolyte.

[0062] The electrolyte was prepared using the following method:

[0063] Step 1: Dehydrate the organic solvent (formed by mixing propylene carbonate and sulfolane in a volume ratio of 70:30) to less than 10 ppm using a molecular sieve, and vacuum dry the electrolyte salts (N,N-dimethylpyrrolidine tetrafluoroborate amine and NN-tetramethylenepyrrolidine tetrafluoroborate amine) to less than 50 ppm.

[0064] Step 2: In a glove box with water and oxygen content below 0.1 ppm, add a mixed organic solvent to a volumetric flask. Add 0.9 mol / L of N,N-dimethylpyrrolidine tetrafluoroborate amine and 0.4 mol / L of N,N-tetramethylenepyrrolidine tetrafluoroborate amine to the organic solvent, and stir until a homogeneous liquid is obtained as the basic electrolyte. Step 3: Add 2% functional additive to the basic electrolyte and stir until homogeneous to obtain the final supercapacitor electrolyte.

[0065] Example 5

[0066] An electrolyte with a molar concentration of 1.1 mol / L was prepared using N,N-dimethylpyrrolidine tetrafluoroborate ammonium and methyltriethyltetrafluoroborate ammonium as electrolyte salts and propylene carbonate and sulfolane as solvents. Then, a functional additive with a mass percentage of 2% was added to the electrolyte.

[0067] The electrolyte was prepared using the following method:

[0068] Step 1: Dehydrate the organic solvent (formed by mixing propylene carbonate and sulfolane in a volume ratio of 70:30) to less than 10 ppm using a molecular sieve, and vacuum dry the electrolyte salts (N-ethyl-N-methylpyrrolidine tetrafluoroborate amine and NN-tetramethylenepyrrolidine tetrafluoroborate amine) to less than 50 ppm.

[0069] Step 2: In a glove box with water and oxygen content below 0.1 ppm, add a mixed organic solvent to a volumetric flask. Add 0.8 mol / L of N-ethyl-N-methylpyrrolidine tetrafluoroborate amine and 0.3 mol / L of N-N-tetramethylenepyrrolidine tetrafluoroborate amine to the organic solvent, and stir until a homogeneous liquid is obtained as the basic electrolyte. Step 3: Add 2% functional additive to the basic electrolyte and stir until homogeneous to obtain the final supercapacitor electrolyte.

[0070] Example 6

[0071] An electrolyte with a molar concentration of 1.1 mol / L was prepared using N,N-dimethylpyrrolidine tetrafluoroborate ammonium and methyltriethyltetrafluoroborate ammonium as electrolyte salts and propylene carbonate and sulfolane as solvents. Then, a functional additive with a mass percentage of 2% was added to the electrolyte.

[0072] The electrolyte was prepared using the following method:

[0073] Step 1: Dehydrate the organic solvent (formed by mixing propylene carbonate and sulfolane in a volume ratio of 70:30) to less than 10 ppm using a molecular sieve, and vacuum dry the electrolyte salts (N,N-dimethylpyrrolidine tetrafluoroborate amine and methyl N-propyl-N-methylpyrrolidine tetrafluoroborate amine) to less than 50 ppm.

[0074] Step 2: In a glove box where the water and oxygen content is below 0.1 ppm, add a mixed organic solvent to a volumetric flask. Add 0.7 mol / L of N-ethyl-N-methylpyrrolidine tetrafluoroborate amine and 0.4 mol / L of N-propyl-N-methylpyrrolidine tetrafluoroborate amine to the organic solvent, and stir until a homogeneous liquid is obtained as the basic electrolyte. Step 3: Add 2% of a functional additive to the basic electrolyte and stir until homogeneous to obtain the final supercapacitor electrolyte.

[0075] Comparative Example 1

[0076] An electrolyte with a molar concentration of 1.1 mol / L was prepared using N,N-dimethylpyrrolidine tetrafluoroborate ammonium and methyltriethyltetrafluoroborate ammonium as electrolyte salts and propylene carbonate and sulfolane as solvents.

[0077] The electrolyte was prepared using the following method:

[0078] Step 1: Dehydrate the organic solvent (formed by mixing propylene carbonate and sulfolane in a volume ratio of 70:30) to less than 10 ppm using a molecular sieve, and vacuum dry the electrolyte salts (N,N-dimethylpyrrolidine tetrafluoroborate amine and methyl N-propyl-N-methylpyrrolidine tetrafluoroborate amine) to less than 50 ppm.

[0079] Step 2: In a glove box with water and oxygen content below 0.1 ppm, add a mixed organic solvent to a volumetric flask, then add 0.7 mol / L of N-ethyl-N-methylpyrrolidine tetrafluoroborate amine and 0.4 mol / L of N-propyl-N-methylpyrrolidine tetrafluoroborate amine to the organic solvent, and stir to form a homogeneous liquid as the basic electrolyte.

[0080] according to Figure 2It can be seen that the capacitance of Examples 1-6 is significantly higher than that of Comparative Example 1. This indicates that, at 25°C, the supercapacitor assembled using an electrolyte composed of 1-(3-glycidyl ether propyl)-1,1,3,3,3-pentaethoxy-1,3-disilpropane and PC solvent exhibits higher capacitance, and the capacitance increases with the increase of the amount added. This is because the introduction of 1-(3-glycidyl ether propyl)-1,1,3,3,3-pentaethoxy-1,3-disilpropane forms an inorganic Si-O-Si network through hydrolysis and condensation at its silane end, and an organic polymer layer through ring-opening polymerization at its epoxy end, thus constructing a robust CEI film on the electrode surface. Secondly, the addition of additives reduces the viscosity of the entire electrolyte system.

[0081] according to Figure 3 It can be seen that the capacity retention rates of Examples 1-6 are significantly higher than those of Comparative Example 1. This indicates that the supercapacitor prepared by introducing 1-(3-glycidyl ether propyl)-1,1,3,3,3-pentaethoxy-1,3-disilpropane and compounding it with PC solvent has a high capacity retention rate and demonstrates superior electrical performance.

[0082] This disclosure proposes a high specific capacitance and high safety electrolyte and its preparation method, as well as a supercapacitor. Compared with the prior art, it has the following beneficial effects: By compounding organic solvents with functional additives, this disclosure forms an electrolyte with high voltage, high stability and flame retardancy, which can significantly improve the specific capacitance and energy density of the device, fundamentally solving the problems of volatilization, leakage and combustion of liquid electrolytes, and achieving synergistic optimization of high specific capacitance and high safety.

[0083] It is understood that the above embodiments are merely exemplary embodiments used to illustrate the principles of this disclosure, and this disclosure is not limited thereto. For those skilled in the art, various modifications and improvements can be made without departing from the spirit and substance of this disclosure, and these modifications and improvements are also considered to be within the scope of protection of this disclosure.

Claims

1. A high specific capacity, high safety electrolyte, characterized in that, The electrolyte salt; The organic solvent; the organic solvent is an ester solvent; A functional additive, the structural formula of the functional additive is as follows: The mass fraction of the functional additive in the electrolyte is 1%-5%. 。 2. The high specific capacity, high safety electrolyte of claim 1, wherein, The organic solvent further comprises a sulfone solvent.

3. The high specific volume, high safety electrolyte of claim 1, wherein, The volume ratio of the ester solvent and the sulfone solvent is (50-70%):(30-50%).

4. The high safety electrolyte of claim 3, wherein the electrolyte is characterized by The ester solvent is selected from propylene carbonate; 5. The high safety electrolyte of claim 3, wherein the electrolyte is characterized by The sulfone solvent is selected from any one of sulfolane and ethyl methyl sulfone. The electrolyte salt is selected from a quaternary ammonium salt.

6. The high specific capacity, high safety electrolyte of claim 1, wherein, The quaternary ammonium salt comprises at least two of the following: methyl triethyl ammonium tetrafluoroborate, N, N-dimethyl pyrrolidine tetrafluoroborate amine, N-ethyl-N-methyl pyrrolidine tetrafluoroborate amine, N-propyl-N-methyl pyrrolidine tetrafluoroborate amine, and N-N-tetramethylene pyrrolidine tetrafluoroborate amine.

7. The high safety electrolyte of claim 6, wherein the electrolyte is characterized by The molar concentration of the electrolyte salt is 1-1.5 mol / L.

8. The high safety electrolyte of claim 1, wherein the electrolyte is characterized by, The preparation method comprises:

9. A method for preparing a high specific capacity, high safety electrolyte, characterized in that, dehydration treatment on the organic solvent, vacuum drying treatment on the electrolyte salt; adding the treated electrolyte salt into the treated organic solvent, stirring to form a base electrolyte; adding the functional additive into the base electrolyte, stirring to obtain the high specific capacity and high safety electrolyte according to any one of claims 1-8. The supercapacitor comprises the high specific capacity and high safety electrolyte according to any one of claims 1-8.

10. An ultracapacitor, characterized by, ​

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