Electrolyte capable of inhibiting decomposition of binder of supercapacitor and preparation method and application of electrolyte

Abstract

The invention relates to the field of electrochemical energy storage devices, and discloses an electrolyte capable of inhibiting decomposition of a binder of a supercapacitor and a preparation method and application thereof, the electrolyte comprises an organic solvent, an electrolyte salt and an additive; wherein the additive has a general formula structure as shown in a formula (I) or a formula (II). The additive with a specific structure is added into the electrolyte disclosed by the invention, so that the expansion rate of a pole piece subjected to high-temperature load can be reduced to 16.3%, the service life of a battery cell is prolonged by about 600h by taking 80% of capacity retention ratio as an intercept point under the extreme test conditions of constant-voltage floating charge at 65 DEG C and 2.9 V, and the core problems of expansion and dusting of the pole piece, violent decomposition of the electrolyte under the extreme conditions and the like are remarkably relieved.

Description

Technical Field

[0001] This invention belongs to the field of electrochemical energy storage devices, and particularly relates to an electrolyte that can inhibit the decomposition of supercapacitor binders, its preparation method, and its application. Background Technology

[0002] In existing technologies, supercapacitors commonly use acetonitrile-based electrolytes to achieve high power and low-temperature performance, while the electrodes still rely on those containing carboxyl groups (-COO). - Water-based binders (such as sodium carboxymethyl cellulose CMC-Na and lithium polyacrylate PAA-Li); under high-temperature aging or float charging conditions at 85-105 ℃, these residual -COO in the electrode sheets - The sites continuously nucleophilically attack acetonitrile, causing the binder backbone to break and generating N-methylacetamide, acetic acid derivatives, and byproducts such as CH4, CO2, and H2. This leads to a sharp drop in electrode cohesion, powder shedding and expansion, gas generation and pressure increase, and micropore blockage. Ultimately, this manifests as accelerated capacity decay, a 20-40% increase in DCR, and premature opening and failure of the explosion-proof valve. Although increasing the degree of crosslinking, replacing non-carboxylic binders, or adding additional film-forming aids can alleviate the problem to some extent, these methods bring secondary defects such as insufficient adhesion, increased electrode internal resistance, or significantly increased costs.

[0003] Therefore, the industry urgently needs a method that can directly affect the COO. - A low-cost technical solution that effectively reduces electrolyte side reaction decomposition and electrode expansion and peeling without changing the existing carboxyl binder system or sacrificing conductivity. Summary of the Invention

[0004] To address the shortcomings of the prior art, this invention provides an electrolyte that can inhibit the decomposition of supercapacitor binders. This electrolyte enters the micropores of the electrode during the wetting process and reacts with the exposed -COO atoms on the pore surface. - Dynamic coordination occurs at the sites; when microcracks appear in the electrode due to thermal expansion or mechanical stress, free additives in the electrolyte can rapidly migrate to the newly exposed -COO sites. - It also completes re-coordination, realizes "liquid phase self-healing" cycle, extends cycle life, and improves capacity retention.

[0005] Another object of the present invention is to provide a method for preparing such an electrolyte that can inhibit the decomposition of supercapacitor binders.

[0006] Another object of the present invention is to provide the application of such an electrolyte that can inhibit the decomposition of supercapacitor binders.

[0007] To achieve the above-mentioned objectives, the present invention adopts the following technical solution:

[0008] An electrolyte capable of inhibiting the decomposition of supercapacitor binders, the electrolyte comprising an organic solvent, an electrolyte salt, and an additive; wherein the additive has a general structure of formula (I) or formula (II):

[0009]

[0010] Wherein, R is a C1~C3 carbon chain, or a strongly electron-withdrawing functional group, such as a cyano (-CN), trifluoromethyl (-CF3), nitro (-NO2), sulfonic acid (-SO3H), or quaternary ammonium (-N) group. + R3), carbonyl (-C=O), carboxyl (-COOH), fluorine (-F), etc.

[0011] Preferably, the additive of the present invention is any one of tris(trimethylsilyl)borate (TMSB), (trimethylsilyl)sulfate (BTSS), tris(2,2,2-trifluoroethyl)borate (TTFEB) or tris(trimethylsilane)phosphate (TMSP).

[0012] The amount of the additive added is 0.1%-1.0% of the total mass of the organic solvent and electrolyte salt.

[0013] Preferably, the electrolyte salt of the present invention is at least one selected from tetraethylamine tetrafluoroborate (TEA BF4), spiro-(1,1')-bispyrrolidine tetrafluoroborate (SBP BF4), 1,1-dimethylpyrrolidine tetrafluoroborate (DMP BF4), 1-ethyl-3-methylimidazolium tetrafluoroborate (EMIm BF4), and 1-ethyl-3-methylimidazolium bis(fluorosulfonyl)imide (EMIm FSI).

[0014] The concentration of the electrolyte salt is 1.0-2.0 mol / L, and preferably, the concentration of the electrolyte salt in this invention is 1.0 mol / L.

[0015] Preferably, the organic solvent of the present invention is at least one selected from acetonitrile (AN), ethylene carbonate (EC) electrolyte, dimethyl carbonate (DMC), methyl propionate (MP), acetonitrile (ACN), 3-methoxypropionitrile (MPN), propionitrile (PN), butyronitrile (BN), dimethylformamide (DMF), methyl formate (MF), ethyl formate (EF), ethyl acetate (EA), and methyl acetate (MA).

[0016] In this invention, the mass concentration of the organic solvent is 50-80 wt%.

[0017] On the other hand, the aforementioned method for preparing an electrolyte that can inhibit the decomposition of supercapacitor binders includes the following steps:

[0018] (1) The organic solvent is purified by removing impurities and water to obtain purified organic solvent;

[0019] (2) At room temperature, the electrolyte salt is added to the purified organic solvent obtained in step (1) and allowed to stand to dissolve, thus obtaining the electrolyte solution;

[0020] (3) Add the additive to the electrolyte obtained in step (2) and let it stand and dissolve to obtain the electrolyte.

[0021] On another front, a double-layer capacitor includes the aforementioned electrolyte that can inhibit the decomposition of supercapacitor binder or the electrolyte prepared by the aforementioned method that can inhibit the decomposition of supercapacitor binder.

[0022] Compared with the prior art, the advantages and positive effects of the present invention are as follows:

[0023] This invention provides an electrolyte that can suppress the decomposition of supercapacitor binders. It incorporates a multifunctional electrolyte additive with a specific structural type. Without altering the existing carboxyl binder system or adding electrode manufacturing steps, the addition of this additive reduces the electrode expansion rate under high-temperature loads to 16.3%. Under extreme testing conditions such as 65°C and 2.9V constant voltage float charging, with an 80% capacity retention rate as the cutoff point, the cell lifespan is extended by approximately 600 hours. This significantly alleviates core issues such as electrode expansion and powder shedding, and the severe decomposition of the electrolyte under extreme conditions. Attached Figure Description

[0024] Figure 1 Capacitor retention graph and dQ / dV-t graph calibrated in the first week for Comparative Example 1 and Example 1 after floating charge at 65°C and 2.9 V for 1500 h;

[0025] Figure 2 The elemental distribution map of the positive electrode cross-section after floating charge at 65°C and 2.9 V for 1500 h is shown for Comparative Example 1 and Example 1.

[0026] Figure 3 The specific gravity-temperature graph and the integral graph of the specific gravity decrease curve of the positive electrode sheet of Comparative Example 1 and Example 1 after floating charge at 65°C and 2.9 V for 1500 h are shown.

[0027] Figure 4 The capacitance retention rate of the comparative and example samples after floating charge at 65°C and 2.9 V for 1500 h was measured.

[0028] Figure 5 Disassembly diagram of the comparative example and the embodiment after 1500 h of high-temperature loading at 2.9 V and 65 °C;

[0029] Figure 6This is a cross-sectional view of the positive electrode sheet after high-temperature loading, used for comparative and example embodiments. Detailed Implementation

[0030] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be further described in detail below with reference to specific embodiments. It should be understood that the specific embodiments described herein are only for explaining this invention and are not intended to limit this invention.

[0031] To control production costs, the electrodes of most mass-produced electric double-layer capacitors (EDLCs) currently use electrodes containing carboxyl groups (-COO). - Water-based binders (such as sodium carboxymethyl cellulose CMC-Na and lithium polyacrylate PAA-Li) are commonly used, while acetonitrile (AN), with its high ionic conductivity, is commonly used as the main solvent in electrolytes. However, during high-temperature aging or float charging tests at 65-105 °C, these residual carboxyl groups (-COO) in the electrodes... - The sites will continuously nucleophilically attack the cyano (-CN) group in AN, causing the binder main chain to break and generate N-methylacetamide, acetic acid derivatives and gaseous byproducts, resulting in electrode powder shedding and expansion, gas generation and pressure rise and micropore blockage. The continuous consumption of electrolyte will also lead to a shortened cell life.

[0032] To block this side reaction, this invention introduces tris(trimethylsilyl)borate (TMSB) with multiple positively charged centers as an additive, which reacts with the -CN and carboxyl-COO groups. - Prioritizes binding before coordination, binding with the exposed -COO segments of the binder chain at the solid-liquid interface. - Rapid coordination occurs, occupying nucleophilic sites and preventing AN from approaching; secondly, the large-volume trimethylsilyl group introduced after coordination forms a thin shielding layer on the pore wall surface, increasing the diffusion of AN to -COO. - Nearby steric hindrance.

[0033] In one specific embodiment of the present invention, an electrolyte capable of inhibiting the decomposition of supercapacitor binders is provided, the electrolyte comprising an organic solvent, an electrolyte salt, and an additive; wherein the additive has a general formula structure of formula (I) or formula (II):

[0034]

[0035] Where R is a C1~C3 carbon chain, or a strong electron-withdrawing functional group, such as cyano (-CN), trifluoromethyl (-CF3), nitro (-NO2), sulfonic acid (-SO3H), quaternary ammonium (-N) group. + R3), carbonyl (-C=O), carboxyl (-COOH), fluorine (-F), etc.

[0036] Preferably, the additive of the present invention is any one of tris(trimethylsilyl)borate (TMSB), (trimethylsilyl)sulfate (BTSS), tris(2,2,2-trifluoroethyl)borate (TTFEB) or tris(trimethylsilane)phosphate (TMSP).

[0037] The amount of the additive added is 0.1%-1.0% of the total mass of the organic solvent and electrolyte salt.

[0038] Preferably, the electrolyte salt of the present invention is at least one selected from tetraethylamine tetrafluoroborate (TEA BF4), spiro-(1,1')-bispyrrolidine tetrafluoroborate (SBP BF4), 1,1-dimethylpyrrolidine tetrafluoroborate (DMP BF4), 1-ethyl-3-methylimidazolium tetrafluoroborate (EMIm BF4), and 1-ethyl-3-methylimidazolium bis(fluorosulfonyl)imide (EMIm FSI).

[0039] The concentration of the electrolyte salt is 1.0-2.0 mol / L, and preferably, the salt concentration in this patent is 1.0 mol / L.

[0040] Preferably, the organic solvent of the present invention is at least one selected from acetonitrile (AN), ethylene carbonate (EC) electrolyte, dimethyl carbonate (DMC), methyl propionate (MP), acetonitrile (ACN), 3-methoxypropionitrile (MPN), propionitrile (PN), butyronitrile (BN), dimethylformamide (DMF), methyl formate (MF), ethyl formate (EF), ethyl acetate (EA), and methyl acetate (MA).

[0041] In this invention, the mass concentration of the organic solvent is 50-80 wt%.

[0042] The electrolyte of this invention incorporates a multifunctional additive that inhibits binder decomposition. This additive enters the micropores of the electrode during the wetting process and interacts with the exposed -COO atoms on the pore surface. - Site formation involves dynamic coordination; the selected additive must contain electron-deficient B, Si, or P centers, and can preferentially react with carboxyl-COO before the cyano-CN group. - In terms of specific technical principles, this blocking layer suppresses side reactions through "liquid-phase diffusion-interfacial coordination-spatial shielding": First, the additive enters the electrode micropores along with the electrolyte, and at the solid-liquid interface, it interacts with the exposed -COO segments of the binder chain. - Rapid coordination occurs, forming BO, Si-OC, or POC bonds, which directly occupy nucleophilic sites and prevent acetonitrile molecules from approaching. Secondly, the large-volume trimethylsilyl group (-Si(CH3)3) introduced after coordination forms a thin shielding layer on the pore wall surface, increasing the diffusion of AN to -COO. -Nearby steric hindrance. When microcracks appear in the electrode due to thermal expansion or mechanical stress, free additives in the electrolyte can rapidly migrate to the newly exposed -COO. - It also completes re-coordination, realizes "liquid phase self-healing" cycle, extends cycle life, and improves capacity retention.

[0043] The present invention will be further explained and illustrated below through more specific embodiments, but these do not constitute any limitation.

[0044] The names and structural formulas of the additives added in the following examples and comparative examples are shown in Table 1 below.

[0045] Table 1. Names and structural formulas of additives used in the examples and comparative examples.

[0046]

[0047] Example 1

[0048] (1) Electrolyte preparation: 1,1-dimethylpyrrolidine tetrafluoroborate (DMP BF4) was vacuum baked at 150°C for 8 hours. Before the salt cooled down, it was transferred to a glove box with a moisture content of <20ppm and cooled. The acetonitrile solvent was dehydrated using molecular sieve for more than 24 hours. DMP BF4 was added to ACN solvent to prepare a 1mol / L solution, and 0.2wt% tris(trimethylsilyl)borate (TMSB) was added. The mixture was stirred and mixed at room temperature for 10 minutes.

[0049] (2) Electrode preparation: Both positive and negative electrode sheets are made by coating aluminum foil with activated carbon YP-50, conductive agent Super P (SP) and binder polyacrylic acid (PAA) mixed evenly in a mass ratio of 90:5:5.

[0050] (3) Cell assembly: The symmetrical electrode and cellulose membrane are wound and assembled into the shell and injected with the electrolyte prepared in step (1) to make a 900 F cylindrical cell.

[0051] Example 2

[0052] (1) Electrolyte preparation: 1,1-dimethylpyrrolidine tetrafluoroborate (DMP BF4) was vacuum baked at 150°C for 8 hours. Before the salt cooled down, it was transferred to a glove box with a moisture content of <20ppm and cooled. The acetonitrile solvent was dehydrated using molecular sieve for more than 24 hours. DMP BF4 was added to ACN solvent to prepare a 1mol / L solution, and 0.2 wt% bis(trimethylsilyl)sulfate (BTSS) was added. The mixture was stirred and mixed at room temperature for 10 minutes.

[0053] (2) Electrode preparation: Same as in Example (1).

[0054] (3) Cell assembly: Same as in Example (1).

[0055] Example 3

[0056] (1) Electrolyte preparation: 1,1-dimethylpyrrolidine tetrafluoroborate (DMP BF4) was vacuum baked at 150°C for 8 hours. Before the salt cooled down, it was transferred to a glove box with a moisture content of <20ppm and cooled. The acetonitrile solvent was dehydrated using molecular sieve for more than 24 hours. DMP BF4 was added to ACN solvent to prepare a 1mol / L solution, and 0.2 wt% tri(2,2,2-trifluoroethyl) borate (TTFEB) was added. The mixture was stirred and mixed at room temperature for 10 minutes.

[0057] (2) Electrode preparation: Same as in Example (1).

[0058] (3) Cell assembly: Same as in Example (1).

[0059] Comparative Example 1

[0060] (1) Electrolyte preparation: 1,1-dimethylpyrrolidine tetrafluoroborate (DMP BF4) was vacuum baked at 150°C for 8 hours. Before the salt cooled down, it was transferred to a glove box with a moisture content of <20ppm and cooled. The acetonitrile solvent was dehydrated using molecular sieve for more than 24 hours. DMP BF4 was added to ACN solvent to prepare a 1mol / L solution and stirred at room temperature for 10 minutes.

[0061] (2) Electrode preparation: Same as in Example (1).

[0062] (3) Cell assembly: Same as in Example (1).

[0063] Comparative Example 2

[0064] (1) Electrolyte preparation: 1,1-dimethylpyrrolidine tetrafluoroborate (DMP BF4) was vacuum baked at 150°C for 8 hours. Before the salt cooled down, it was transferred to a glove box with a moisture content of <20ppm and cooled. The acetonitrile solvent was dehydrated using molecular sieve for more than 24 hours. DMP BF4 was added to ACN solvent to prepare a 1mol / L solution, and 0.2 wt% tris(trimethylsilane) phosphate (TMSP) was added. The mixture was stirred and mixed at room temperature for 10 minutes.

[0065] (2) Electrode preparation: Same as in Example (1).

[0066] (3) Cell assembly: Same as in Example (1).

[0067] Comparative Example 3

[0068] (1) Electrolyte preparation: 1,1-dimethylpyrrolidine tetrafluoroborate (DMP BF4) was vacuum baked at 150°C for 8 hours. Before the salt cooled down, it was transferred to a glove box with a moisture content of <20ppm and cooled. The acetonitrile solvent was dehydrated using molecular sieve for more than 24 hours. DMP BF4 was added to ACN solvent to prepare a 1mol / L solution, and 0.2 wt% tris(trimethylsilyl) phosphite (TMSPi) was added. The mixture was stirred and mixed at room temperature for 10 minutes.

[0069] (2) Electrode preparation: Same as in Example (1).

[0070] (3) Cell assembly: Same as in Example (1).

[0071] Performance Testing

[0072] Test method:

[0073] The capacity and internal resistance of a 900F battery cell were determined using the Maxwell six-step method. An Arbin 5V 30A 32CH device was used. The cell was allowed to stand for 10 seconds, then charged with a constant current (e.g., 25A) to the rated voltage (e.g., 2.9V), allowed to stand for 5 seconds, and then allowed to stand for another 10 seconds. The cell was then discharged with a constant current (e.g., 25A) to the set voltage (50% of the rated voltage, 1.45V), allowed to stand for 5 seconds, and steps 1 to 6 were repeated for a second test. The cutoff voltage (V1) at step 5 and the voltage (V2) after standing for 5 seconds at step 6 were recorded during the second test. The capacity was calculated as: C = I5 * (t5 - t4) / (V4 - V5). The DC internal resistance was calculated using the formula: ESR. DC =(V6-V5) / I5. The testing procedure for low-temperature DCR is the same as above. After the cell has been left to stand at the rated temperature for 2 hours, the internal resistance is tested.

[0074] The test method for high-temperature load with a voltage limit of 2.9 V at 65℃ is as follows: At room temperature, test the basic performance: voltage, internal resistance, thickness (height of top and bottom), and mass. Control the temperature of the temperature chamber at 25℃ and let it stand for 2.5 h; charge it to 2.9V with a constant current of 25A; discharge it to 1.5V with a constant current of 25A (this step is 0.1s timing), repeat the charge and discharge cycle 3 times, and take the third time as the cell capacitor; transfer the cell to the 65℃ temperature chamber and connect it; charge it at a constant voltage of 2.9V for 168 h (7 days); transfer the cell to room temperature and let it stand for 3 h; repeat the above steps for 1500 h.

[0075] For the characterization instruments, the scanning electron microscope was model FEI Quanta FEG, and the thermogravimetric analyzer was model JH-TGA150.

[0076] Example 1 involved adding 0.2 wt% TMSB to Comparative Example 1 (without additives), and then assembling a 900 F battery cell using this additive. The cell was then subjected to constant voltage float charging at 2.9 V for 1500 h at 65°C. Figure 1 The comparative and example samples showed almost identical capacity retention rates initially, but the differences gradually widened after 700 hours, with the blank sample (Comparative Example 1) exhibiting a significantly lower capacity retention rate. Using 80% capacity retention as the cutoff point, the slope of the curves was fitted and extrapolated, resulting in a cell lifespan extension of approximately 600 hours. The sudden rise in the dQ / dV-t graph corresponds to the onset of Faraday side reactions (e.g., electrolyte decomposition, functional group redox, ion rearrangement, or micropore ion exchange), while pure double-layer adsorption / desorption (non-Faraday) exhibits a flat baseline. Before float charging, the dQ / dV-t graph of the cell's calibrated capacity showed that Example 1 exhibited a peak with a slight rise around 150 min (charging), while Comparative Example 1 only showed a small peak with a slight rise around 1000 min (charging), indicating that TMSB, due to its electron-deficient centers, can indeed preferentially adsorb and react.

[0077] All electrodes were disassembled from the battery cell under strictly controlled moisture content (H2O < 20 ppm) and quickly vacuum-sealed. The vacuum bags were only opened for electrode testing at the start of characterization, thus minimizing electrolyte evaporation during transport. Scanning electron microscopy (SEM) and elemental mapping of the positive electrode cross-sections of Comparative Example 1 and Example 1 after 1500 h of float charging under high temperature and high pressure were performed. Figure 2 As shown, the cross-section of the electrode in Comparative Example 1 exhibits obvious delamination. The N and F elements originate from the cations and anions of the salt 1,1-dimethylpyrrolidine tetrafluoroborate (DMP BF4), while O originates from the binder polyacrylic acid (PAA). Both contents are less than in Example 1, indicating that the electrolyte in Comparative Example 1 is severely decomposed, and the binder also undergoes severe decomposition, leading to significant interlayer cracks in the electrode. Consequently, during the later stages of high-temperature, high-pressure float charging, anions struggle to reach the surface of the positive electrode activated carbon to exchange charge, resulting in rapid capacity decay. In contrast, the cross-section of Example 1 shows no delamination, the activated carbon remains uniformly distributed, and there is less decomposition of the electrolyte and binder. This indicates that the preferential reaction of TMSB effectively blocks the decomposition of the binder and the continuous consumption of electrolyte by side reactions.

[0078] To further confirm the electrolyte retention capacity in the activated carbon, thermogravimetric analysis (TGA) was simultaneously performed on the positive electrode. The DTF curve was obtained by integrating the gravity-temperature curve to clearly distinguish overlapping thermal events. The sharp peak shape visually reflects the severity of mass changes and the corresponding temperatures. Figure 3As shown, activated carbon inherently exhibits high thermal stability, with only minor decomposition occurring at 690 °C. The decrease in temperature before 690 °C corresponds to the decomposition of the electrolyte stored in the activated carbon pores. In Comparative Example 1, the electrolyte decomposes violently and almost dries up during the float charging process, yet there is no significant mass change within the temperature range of 30–690 °C. In contrast, the electrolyte in Example 1 exhibits excellent wettability and extremely high electrolyte retention, with the electrode containing approximately 28% electrolyte. The thermal decomposition of TMSB at 220.5 °C and 342.8 °C in the DTF curve indicates that this additive has high thermal stability, and its addition significantly inhibits the side reaction decomposition of the electrolyte, thus supporting the continuous cycling of the battery cell in the later stages of high-temperature, high-pressure float charging.

[0079] To further verify the universality of the strong positively charged center additive in inhibiting adhesive decomposition, bis(trimethylsilyl)sulfate (BTSS), also with a strong positive charge, was designed and introduced as Example 2, and tris(2,2,2-trifluoroethyl) borate (TTFEB) as Example 3. Simultaneously, tris(trimethylsilane) phosphate (TMSP), with a weak positive charge, was designed and introduced as Comparative Example 2, and tris(trimethylsilyl) phosphite (TMSPi), with a negative charge, as Comparative Example 3. Similar to TMSB, the +6 valence S center in BTSS is electron-deficient due to the electron withdrawal of four oxygen atoms. It also features a sterically hindered -Si(CH3)3 group as a positive charge center, raising the energy barrier for AN migration to the adhesive surface. TTFEB, however, removed the -Si(CH3)3 group to verify its effect. Although the +5 valence P center in TMSP is also electron-deficient, the lone O pair can form π feedback with the empty d orbitals of P, thus homogenizing the charge distribution, making it a weakly positive charge center. The center of TMSPi is a +3 valence P (electron-rich), and the remaining 2 electrons exist in the form of a lone pair, hence it is a Lewis base and a strongly negatively charged center, as detailed in Table 1.

[0080] Similarly, the battery cells from Examples 2-3 and Comparative Examples 2-3 were subjected to a constant voltage float charge at 65°C and 2.9V for 1500 hours. Figure 4 As shown, Example 2 exhibits a high capacity retention similar to Example 1 (TMSB), indicating the universality of the effect of additives with multiple positively charged centers. Example 3 shows a slightly lower retention, possibly due to the lack of three sterically hindered -Si(CH3)3 groups, suggesting that both the B / SO bond center and -Si(CH3)3 are indispensable. Comparative Examples 2 (TMSP) and 3 (TMSPi) show gradually decreasing capacity retention due to P being a weakly positively charged center and a strongly negatively charged center, respectively.

[0081] The battery cells after high-temperature and high-pressure float charging were disassembled separately. The surface morphology of the positive and negative electrode plates and separators of Comparative Examples 1-3 and 1-3 are as follows: Figure 5As shown in the figures, Example 1 exhibits the best overall morphology, with minimal adhesion between the positive electrode and the positive electrode-side separator, and the negative electrode retaining its original morphology. The high electrolyte retention of the negative electrode-side separator indicates minimal electrolyte decomposition, and both the positive and negative electrodes feel moist with a good interface. In contrast, the positive and negative electrodes and separator of Comparative Example 1 (blank sample) feel dry and brittle. Due to extensive binder decomposition, the activated carbon on both the positive and negative electrodes adheres heavily to the separator, resulting in significant powder shedding. Furthermore, due to the higher potential on the positive electrode side and severe electrolyte decomposition, the positive electrode-side separator is significantly yellowed, and a noticeable yellowish-brown band appears at the bottom of the negative electrode-side separator, corresponding to the severe electrolyte decomposition. Examples 2-3 also show similar issues of activated carbon adhesion to the separator and yellowing of the positive electrode-side separator, but their morphologies are better than those of the comparative examples. These morphological findings demonstrate the significant positive effect of inhibiting binder decomposition in delaying electrolyte consumption and activated carbon shedding.

[0082] Since the disassembly results showed that the morphology of the positive electrode side was worse than that of the negative electrode side, SEM images were further taken of the cross-section of the positive electrode sheet. Figure 6 As shown, the thicknesses are in the following order: Comparative Example 1 (TMSB) < Example 2 (BTSS) < Example 3 (TTEB) < Comparative Example 2 (TMSP) < Comparative Example 1 (blank sample) < Comparative Example 3 (TMSPi), which is positively correlated with the disassembly results and the positive charge of the molecular center.

[0083] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of this invention patent should be determined by the appended claims.

Claims

1. An electrolyte capable of inhibiting the decomposition of supercapacitor binders, characterized in that, The electrolyte comprises an organic solvent, an electrolyte salt, and an additive; wherein the additive has a general structure of formula (I) or formula (II): Wherein, R is a carbon chain of C1 to C3 or a strongly electron-withdrawing functional group.

2. The electrolyte according to claim 1, characterized in that, The strong electron-withdrawing functional group is selected from cyano (-CN), trifluoromethyl (-CF3), nitro (-NO2), sulfonic acid (-SO3H), quaternary ammonium (-N) + Any one of the following: R3, carbonyl (-C=O), carboxyl (-COOH), or fluorine (-F).

3. The electrolyte according to claim 2, characterized in that, The additive is any one of tris(trimethylsilyl)borate (TMSB), trimethylsilyl)sulfate (BTSS), tri(2,2,2-trifluoroethyl)borate (TTFEB), or tri(trimethylsilane)phosphate (TMSP).

4. The electrolyte according to any one of claims 1-3, characterized in that, The amount of the additive added is 0.1%-1.0% of the total mass of the organic solvent and electrolyte salt.

5. The electrolyte according to claim 4, characterized in that, The electrolyte salt is at least one of tetraethylamine tetrafluoroborate (TEA BF4), spiro-(1,1')-bispyrrolidine tetrafluoroborate (SBP BF4), 1,1-dimethylpyrrolidine tetrafluoroborate (DMPBF4), 1-ethyl-3-methylimidazolium tetrafluoroborate (EMIm BF4), and 1-ethyl-3-methylimidazolium bis(fluorosulfonyl)imide (EMIm FSI).

6. The electrolyte according to claim 5, characterized in that, The concentration of the electrolyte salt is 1.0-2.0 mol / L, preferably 1.0 mol / L.

7. The electrolyte according to any one of claims 1-3, characterized in that, The organic solvent is selected from nitrile and ester organic solvents, preferably at least one of acetonitrile (AN), ethylene carbonate (EC) electrolyte, dimethyl carbonate (DMC), methyl propionate (MP), acetonitrile (ACN), 3-methoxypropionitrile (MPN), propionitrile (PN), butyronitrile (BN), dimethylformamide (DMF), methyl formate (MF), ethyl formate (EF), ethyl acetate (EA), and methyl acetate (MA).

8. The electrolyte according to claim 7, characterized in that, The organic solvent has a mass concentration of 50-80 wt%.

9. The method for preparing the electrolyte capable of inhibiting the decomposition of supercapacitor binders according to any one of claims 1 to 8, characterized in that, Includes the following steps: (1) The organic solvent is purified by removing impurities and water to obtain purified organic solvent; (2) At room temperature, the electrolyte salt is added to the purified organic solvent obtained in step (1) and allowed to stand to dissolve, thus obtaining the electrolyte solution; (3) Add the additive to the electrolyte obtained in step (2) and let it stand and dissolve to obtain the electrolyte.

10. A double-layer capacitor, characterized in that, Includes the electrolyte that can inhibit the decomposition of supercapacitor binder as described in any one of claims 1 to 8, or the electrolyte that can inhibit the decomposition of supercapacitor binder prepared by the preparation method described in claim 9.

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