Supercapacitor electrolyte additive, supercapacitor electrolyte and application of supercapacitor electrolyte additive
Technical Field
The invention belongs to the technical field of super capacitors, and particularly relates to a super capacitor electrolyte additive, electrolyte and application thereof.
Background
With the rapid development of portable electronic equipment, wearable equipment and electric vehicles, people have higher and higher requirements on energy storage devices of various electronic equipment, and among a plurality of energy storage devices, a supercapacitor is a high-efficiency electrochemical energy storage device and has the advantages of high charge-discharge rate, high power density, long cycle life, quick charging, stable performance and the like. Therefore, the super capacitor is receiving an increasingly wide attention and is widely used, but compared with energy storage devices such as lithium ion batteries, the super capacitor has a lower energy density, and this disadvantage greatly limits the application of the super capacitor. Therefore, how to further increase the energy density of the super capacitor is the key of the current research under the advantages of ensuring the long cycle life and high power density of the super capacitor.
The addition of the electrolyte additive can reduce the internal resistance of the electrolyte and effectively improve the specific capacitance of the super capacitor, and the electrolyte additive is convenient to use without changing the structure and process conditions of the conventional super capacitor. In addition, the dosage of the electrolyte additive is small, and the electrochemical performance of the super capacitor can be greatly improved only by adding a small amount of the electrolyte additive.
CN105006377A discloses a composite electrolyte using azo substances as additives and a preparation method thereof, wherein the composite electrolyte is composed of a blank electrolyte and an electrolyte additive, the blank electrolyte is KOH solution, and the electrolyte additive is azo substances. The concentration of KOH in the composite electrolyte is 1-6mol/L, and the concentration of azo substances is 1-10 mmol/L. The method is easy to operate, the raw materials are cheap and easy to obtain, and the azo substances are used as the electrolyte additive, so that the ionic conductivity of the electrolyte can be improved, the internal resistance of the electrolyte can be reduced, and the electrochemical performance of the super capacitor can be obviously improved.
CN107275120A discloses an electrolyte additive and a lithium ion hybrid super capacitor containing the same, wherein a small amount of additive is added into the electrolyte of the lithium ion hybrid super capacitor, so that the charge and discharge performance of the lithium ion hybrid super capacitor is greatly improved, and the lithium ion hybrid super capacitor containing the electrolyte additive has flame retardant capability and improves the use safety.
In the prior art, the strategy for effectively improving the energy density of the super capacitor is limited, so that it is significant to develop an electrolyte additive for further improving the energy density of the super capacitor on the premise of ensuring the long cycle life and high power density of the super capacitor.
Disclosure of Invention
Aiming at the defects of the prior art, the invention aims to provide a super capacitor electrolyte additive, an electrolyte and application thereof.
In order to achieve the purpose, the invention adopts the following technical scheme:
in one aspect, the present invention provides a supercapacitor electrolyte additive comprising a bipyridylium conjugated organic molecule; the structure of the bipyridyl salt conjugated organic molecule is shown as the formula (I):
wherein R is1And R1' is independently selected from substituted or unsubstituted alkyl, substituted or unsubstituted aryl, substituted or unsubstituted alkoxy, in particular: r1May be selected from substituted alkyl, unsubstituted alkyl, substituted aryl, unsubstituted aryl, substituted alkoxy, or unsubstituted alkoxy; r1' may be selected from substituted alkyl, unsubstitutedSubstituted alkyl, substituted aryl, unsubstituted aryl, substituted alkoxy, or unsubstituted alkoxy.
R2Selected from single bonds, substituted or unsubstituted heteroaryl groups, and substituted or unsubstituted five-membered heterocyclic groups, and specifically: r2May be selected from a single bond, a substituted heteroaryl group, an unsubstituted heteroaryl group, a substituted five-membered heterocyclic group or an unsubstituted five-membered heterocyclic group.
X1And X2Independently selected from fluoride-containing anions.
X1And X2The fluoride-containing anion is selected because it makes the electrolyte additive of formula (I) more soluble in organic solvents, less dissociative, and forms a salt that readily dissociates in the solvent.
The electrolyte additive comprises bipyridyl salt conjugated organic molecules which have redox properties and can be reduced during charging and oxidized during discharging. The oxidation/reduction reaction of the molecules in the charge and discharge process provides pseudo capacitance for the capacitor, and further enhances the specific capacitance of the capacitor. The molecule has the advantages of good solubility in an organic system, simpler synthesis, higher performance and the like. Therefore, the super capacitor prepared by the method has long cycle life, cycle stability, high power density and high energy density.
Preferably, said R is1Selected from any one of the following structural formulas:
wherein the curve represents the attachment position of the group.
When n is 0, it is methyl.
Wherein n is selected from any integer from 0 to 10, such as 0,1, 2, 3, 4, 5, 6, 7, 8, 9 or 10.
The groups have different electronic structures and electronegativities, and can influence the electronic structure of the pyridine-containing conjugated group, further influence the redox property of molecules, and finally influence the performance of the molecules in a capacitor.
Preferably, said R is1' is selected from any one of the following structural formulae:
wherein the curve represents the attachment position of the group.
Wherein n is selected from any integer from 0 to 10, such as 0,1, 2, 3, 4, 5, 6, 7, 8, 9 or 10.
The value of n should not exceed 10, and if it exceeds 10, the solubility of the electrolyte additive is greatly reduced.
Preferably, said R is2Selected from any one of the following structural formulas:
wherein the curve represents the attachment position of the group.
Wherein m is selected from any integer from 1 to 4, such as 1, 2, 3 or 4.
The structure can stabilize the pyridine ring in a reduction state, so that the circulation stability of additive molecules is improved, the dissociation of anions and cations is facilitated, the resistance of the electrolyte is improved, and the performance of the electrolyte is improved.
The value of m cannot exceed 4, and if the value of m exceeds 4, the solubility of the electrolyte additive is greatly reduced due to the overlarge conjugated ring.
Preferably, said X1Selected from any one of the following structural formulas:
preferably, said X2Selected from any one of the following structural formulas:
reference is made to the bipyridylium salt conjugated organic molecules (K.Takahashi, T.Nihira, K.Akiyama, Y.Ikegami, E.Fukuyo, Synthesis and Characterization of New Conjugation-Extended virology, Involution a Central Aromatic Linking Group, J.chem.Commun, 1992,620-622, Terry L.Prime, J.and Harder W.Gibson, Supermolecular Pseudomonas Polymers from Biscoryutan Bisaraaquats, J.Am.Soc.2018, 140,12,4455-4465, D.Taffa, M.Kathesean, L.Walder, Tug, Hydrogen, and humidity of moisture TiO, of moisture2Langmuir,2009,25, 5371-5379).
In another aspect, the present invention provides a supercapacitor electrolyte comprising a base electrolyte and a supercapacitor electrolyte additive as described above.
Preferably, the concentration of the supercapacitor electrolyte additive in the supercapacitor electrolyte is 0.01-2000mmol/L, such as 0.01mmol/L, 0.1mmol/L, 1mmol/L, 5mmol/L, 10mmol/L, 50mmol/L, 100mmol/L, 200mmol/L, 500mmol/L, 800mmol/L, 1000mmol/L, 1500mmol/L or 2000mmol/L, and the like.
Preferably, the concentration of the supercapacitor electrolyte additive in the supercapacitor electrolyte is 5-1000mmol/L, such as 5mmol/L, 10mmol/L, 20mmol/L, 50mmol/L, 100mmol/L, 200mmol/L, 500mmol/L or 1000mmol/L, etc.
Preferably, the base electrolyte is an organic system electrolyte, i.e. the supercapacitor electrolyte additive is applicable to all organic system electrolytes.
The basic electrolyte not only comprises the above electrolyte, but also is applicable to all organic system electrolytes, and the electrolyte additive is applicable to all organic system electrolytes and has a wide application range.
In a further aspect, the invention provides the use of a supercapacitor electrolyte as described above in the preparation of a supercapacitor.
Compared with the prior art, the invention has the following beneficial effects:
the electrolyte additive provided by the invention can greatly improve the electrochemical performance of the super capacitor, effectively reduce the internal resistance of the electrolyte, enhance the current density, and improve the specific capacitance, energy density, rate capability and cycle stability of the super capacitor.
The electrolyte additive needs a small amount of use when improving the performance of the super capacitor, is suitable for all organic system electrolytes, and has a wide application range.
Drawings
FIG. 1 is a graph showing the results of comparing the specific capacitances of the capacitors obtained in examples 1 and 2 with those of comparative example 1 at different current densities;
FIG. 2 is a graph showing the results of comparing the cycle characteristics of the capacitors obtained in example 1 with those of comparative example 1.
Detailed Description
The technical solution of the present invention is further explained by the following embodiments. It should be understood by those skilled in the art that the examples are only for the understanding of the present invention and should not be construed as the specific limitations of the present invention.
Example 1
The embodiment provides a supercapacitor electrolyte additive, which comprises a bipyridyl salt conjugated organic molecule; the bipyridylium conjugated organic molecule has a structure shown in formula (A), and is prepared according to the preparation method in the literature (K.TAKAHASHI, T.NIHIRA, K.AKIYAMA, Y.IKEGAMI, E.FUKUYO, Synthesis and Characterization of New coupling-Extended virology Involution, J.chem.Commun.,1992, 620-plus 622.).
Preparing an electrolyte containing the electrolyte additive: 0.02mmol of the compound of formula (A) was weighed and dissolved in 100mL of a base electrolyte solution for a supercapacitor (acetonitrile solution containing 1M LiTFSI), to obtain an organic electrolyte solution containing 0.2M of the compound of formula (A).
Assembling the super capacitor: and (3) taking the ordered mesoporous carbon CMK-3 as an electrode material, taking a glass fiber membrane as a diaphragm, and taking the prepared electrolyte as an electrolyte to manufacture the 2032 type button type supercapacitor.
Example 2
The embodiment provides a supercapacitor electrolyte additive, which comprises a bipyridyl salt conjugated organic molecule; the structure of the bipyridyl salt conjugated organic molecule is shown as a formula (B), and the bipyridyl salt conjugated organic molecule is prepared by a preparation method in a reference literature (Terry L.price, Jr.and Harry W.Gibson, Supramolecular pseudotaxane Polymers from Biscrypands and Bisparaquats, J.Am.chem.Soc.2018,140(12), 4455-4465):
preparing an electrolyte containing the electrolyte additive: 0.02mmol of the compound of formula (B) was weighed and dissolved in 100mL of a base electrolyte solution for a supercapacitor (acetonitrile solution containing 1M LiTFSI), to obtain an organic electrolyte solution containing 0.2M of the compound of formula (B).
Assembling the super capacitor: and (3) taking the ordered mesoporous carbon CMK-3 as an electrode material, taking a glass fiber membrane as a diaphragm, and taking the prepared electrolyte as an electrolyte to manufacture the 2032 type button type supercapacitor.
Example 3
The embodiment provides a supercapacitor electrolyte additive, which comprises a bipyridyl salt conjugated organic molecule; the structure of the bipyridyl salt conjugated organic molecule is shown as the formula (A):
preparing an electrolyte containing the electrolyte additive: 0.02mmol of the compound of the formula (A) is weighed and dissolved in 100mL of a basic electrolyte (ionic liquid: 1-ethyl-3-methylimidazolium bistrifluoromethanesulfonylimide) for a super capacitor, so as to obtain an organic electrolyte containing 0.2M of the compound of the formula (A).
Assembling the super capacitor: and (3) taking the ordered mesoporous carbon CMK-3 as an electrode material, taking a glass fiber membrane as a diaphragm, and taking the prepared electrolyte as an electrolyte to manufacture the 2032 type button type supercapacitor.
Example 4
The embodiment provides a supercapacitor electrolyte additive, which comprises a bipyridyl salt conjugated organic molecule; the structure of the bipyridine salt conjugated organic molecule is shown as a formula (C), and the preparation method is prepared by referring to the preparation method disclosed in the document in example 1.
Preparing an electrolyte containing the electrolyte additive: 0.02mmol of the compound of the formula (C) is weighed and dissolved in 100mL of a basic electrolyte (ionic liquid: 1-ethyl-3-methylimidazolium bistrifluoromethanesulfonylimide) for a super capacitor, so as to obtain an organic electrolyte containing 0.2M of the compound of the formula (C).
Assembling the super capacitor: and (3) taking the ordered mesoporous carbon CMK-3 as an electrode material, taking a glass fiber membrane as a diaphragm, and taking the prepared electrolyte as an electrolyte to manufacture the 2032 type button type supercapacitor.
Example 5
The embodiment provides a supercapacitor electrolyte additive, which comprises a bipyridyl salt conjugated organic molecule; the structure of the bipyridine salt conjugated organic molecule is shown as a formula (D), and the preparation method thereof is referred to a literature (D.Taffa, M.Kathiresan, L.Walder, Tuning the Hy)drophilic,Hydrophobic,and Ion Exchange Properties of Mesoporous TiO2Langmuir,2009,25, 5371-5379).
Preparing an electrolyte containing the electrolyte additive: 0.02mmol of the compound of the formula (D) was weighed and dissolved in 100mL of a base electrolyte for a supercapacitor (ionic liquid: 1-ethyl-3-methylimidazolium bistrifluoromethanesulfonylimide) to obtain an organic electrolyte containing 0.2M of the compound of the formula (D).
Assembling the super capacitor: and (3) taking the ordered mesoporous carbon CMK-3 as an electrode material, taking a glass fiber membrane as a diaphragm, and taking the prepared electrolyte as an electrolyte to manufacture the 2032 type button type supercapacitor.
Example 6
The embodiment provides a supercapacitor electrolyte additive, which comprises a bipyridyl salt conjugated organic molecule; the structure of the bipyridine salt conjugated organic molecule is shown as a formula (E), and the preparation method is prepared by referring to the preparation method in the literature in example 5.
Preparing an electrolyte containing the electrolyte additive: 0.02mmol of the compound of formula (E) was weighed and dissolved in 100mL of a base electrolyte for a supercapacitor (ionic liquid: 1-ethyl-3-methylimidazolium bistrifluoromethanesulfonylimide) to obtain an organic electrolyte containing 0.2M of the compound of formula (E).
Assembling the super capacitor: and (3) taking the ordered mesoporous carbon CMK-3 as an electrode material, taking a glass fiber membrane as a diaphragm, and taking the prepared electrolyte as an electrolyte to manufacture the 2032 type button type supercapacitor.
Example 7
The embodiment provides a supercapacitor electrolyte additive, which comprises a bipyridyl salt conjugated organic molecule; the structure of the bipyridyl salt conjugated organic molecule is shown as a formula (F), and the preparation method is prepared by referring to the preparation method in the literature in example 1.
Preparing an electrolyte containing the electrolyte additive: 0.02mmol of the compound of formula (F) was weighed and dissolved in 100mL of a base electrolyte for a supercapacitor (ionic liquid: 1-ethyl-3-methylimidazolium bistrifluoromethanesulfonylimide) to obtain an organic electrolyte containing 0.2M of the compound of formula (F).
Assembling the super capacitor: and (3) taking the ordered mesoporous carbon CMK-3 as an electrode material, taking a glass fiber membrane as a diaphragm, and taking the prepared electrolyte as an electrolyte to manufacture the 2032 type button type supercapacitor.
Example 8
The embodiment provides a supercapacitor electrolyte additive, which comprises a bipyridyl salt conjugated organic molecule; the structure of the bipyridyl salt conjugated organic molecule is shown as a formula (G), and the preparation method is prepared by referring to the preparation method in the literature in example 1.
Preparing an electrolyte containing the electrolyte additive: 0.02mmol of the compound of formula (G) was weighed and dissolved in 100mL of a base electrolyte solution for a supercapacitor (a dimethyl sulfoxide solution containing 1M LiTFSI), to obtain an organic electrolyte solution containing 0.2M of the compound of formula (G).
Assembling the super capacitor: and (3) taking the ordered mesoporous carbon CMK-3 as an electrode material, taking a glass fiber membrane as a diaphragm, and taking the prepared electrolyte as an electrolyte to manufacture the 2032 type button type supercapacitor.
Example 9
The embodiment provides a supercapacitor electrolyte additive, which comprises a bipyridyl salt conjugated organic molecule; the structure of the bipyridine salt conjugated organic molecule is shown as a formula (H), and the preparation method is prepared by referring to the preparation method in the literature in example 1.
Preparing an electrolyte containing the electrolyte additive: 0.02mmol of the compound of formula (H) was weighed and dissolved in 100mL of a base electrolyte for a supercapacitor (a dimethyl sulfoxide solution containing 1M LiTFSI), to obtain an organic electrolyte containing 0.2M of the compound of formula (H).
Assembling the super capacitor: and (3) taking the ordered mesoporous carbon CMK-3 as an electrode material, taking a glass fiber membrane as a diaphragm, and taking the prepared electrolyte as an electrolyte to manufacture the 2032 type button type supercapacitor.
Example 10
The embodiment provides a supercapacitor electrolyte additive, which comprises a bipyridyl salt conjugated organic molecule; the structure of the bipyridyl salt conjugated organic molecule is shown as a formula (I), and the preparation method is prepared by referring to the preparation method in the literature in example 1.
Preparing an electrolyte containing the electrolyte additive: 0.02mmol of the compound of formula (I) was weighed and dissolved in 100mL of a base electrolyte for a supercapacitor (1M solution of LiTFSI in dimethylsulfoxide) to obtain an organic electrolyte containing 0.2M of the compound of formula (I).
Assembling the super capacitor: and (3) taking the ordered mesoporous carbon CMK-3 as an electrode material, taking a glass fiber membrane as a diaphragm, and taking the prepared electrolyte as an electrolyte to manufacture the 2032 type button type supercapacitor.
Comparative example 1
This comparative example provides an electrolyte: this electrolyte contained only the base electrolyte (acetonitrile solution containing 1M LiTFSI) and no additive, compared to example 1.
Assembling the super capacitor: and (3) taking the ordered mesoporous carbon CMK-3 as an electrode material, taking a glass fiber membrane as a diaphragm, and taking the prepared electrolyte as an electrolyte to manufacture the 2032 type button type supercapacitor.
Electrochemical properties (specific capacitance, rate capability and cycle stability) of the supercapacitors prepared in examples 1-2 and comparative example 1 were tested as follows:
test 1: the specific capacitance of each supercapacitor was tested at different current densities, and the test results are shown in fig. 1: the results of this test are comparative results of specific capacitance at different current densities for the capacitors made in examples 1 and 2 and comparative example 1. As can be seen from FIG. 1, the addition of the additives A and B to the blank electrolyte (acetonitrile solution containing 1M LiTFSI) can greatly improve the specific capacitance of the capacitor under different current densities, and can be up to more than twice as high as that of the blank electrolyte. At the same time, at very high current densities (20A g)-1) The specific capacitance attenuation of the electrolyte containing the additive is extremely small, and the prepared electrolyte containing the additive not only can greatly improve the specific capacitance of the super capacitor, but also has excellent rate performance, so that the power density of the capacitor is improved.
And (3) testing 2: the cycling stability of each supercapacitor was tested, and the test results are shown in fig. 2: the results of this test are the results of comparing the cycle performance of the capacitors made in example 1 with those made in comparative example 1. As can be seen from fig. 2, the capacitor of example 1 has more excellent cycle performance. At 2 A.g-1After 10000 cycles, the specific capacitance is not attenuated and is still more than doubled compared with the specific capacitance of the capacitor of the comparative example 1.
The applicant states that the present invention is illustrated by the above examples of the supercapacitor electrolyte additive, the electrolyte and the application thereof, but the present invention is not limited to the above examples, i.e. it does not mean that the present invention must rely on the above examples to be implemented. It should be understood by those skilled in the art that any modification of the present invention, equivalent substitutions of the raw materials of the product of the present invention, addition of auxiliary components, selection of specific modes, etc., are within the scope and disclosure of the present invention.
The preferred embodiments of the present invention have been described in detail, however, the present invention is not limited to the specific details of the above embodiments, and various simple modifications may be made to the technical solution of the present invention within the technical idea of the present invention, and these simple modifications are within the protective scope of the present invention.
It should be noted that the various technical features described in the above embodiments can be combined in any suitable manner without contradiction, and the invention is not described in any way for the possible combinations in order to avoid unnecessary repetition.