CONJUGATION-FUSED BIPOLAR REDOX-ACTIVE MOLECULE, PREPARATION METHOD, AND APPLICATION THEREOF

Abstract

The present disclosure discloses a conjugation-fused bipolar redox-active molecule and its preparation method and application. The bipolar redox-active molecule includes a p-type redox active center and an n-type redox active center. The p-type redox active center and the n-type redox active center are fused in a molecular unit by conjugation.

Claims

1. A conjugation-fused bipolar redox-active molecule, comprising a p-type redox active center and an n-type redox active center; wherein the p-type redox active center and the n-type redox active center are fused in a molecular unit by conjugation.

2. The molecule according to claim 1, wherein the p-type redox active center is a quaternary nitrogen and the n-type redox active center is a carbonyl ketone.

3. The molecule according to claim 2, having a structural formula as: ##STR00012## wherein the R1 to R12 are identical or different from each other and are each independently selected from —H and polar functional groups; the X is a third main group element or a fifth main group element.

4. The molecule according to claim 3, wherein the structural formula is: ##STR00013##

5. The molecule according to claim 3, wherein the structural formula is: ##STR00014##

6. A method for preparing a conjugation-fused bipolar redox-active molecule; wherein the molecule comprises a p-type redox active center and an n-type redox active center; wherein the p-type redox active center and the n-type redox active center are fused in a molecular unit by conjugation; the p-type redox active center is a quaternary nitrogen and the n-type redox active center is a carbonyl ketone; the molecule has a structural formula as: ##STR00015## the method comprises: (1) mixing 10H-phenothiazine, methyl 2-bromo-5-methoxybenzoate, cesium carbonate, Pd(OAc).sub.2, 2-dicyclohexylphosphino-2′,4′,6′-triisopropylbiphenyl, and o-xylene and removing oxygen to obtain a first mixture, and heating the first mixture at 125˜135° C. for 20˜28 h to obtain a first product; separating the first product to obtain 5-methoxy-2-(10H-phenothiazin-10-yl)benzoate; (2) mixing the methyl 5-methoxy-2-(10H-phenothiazin-10-yl)benzoate, NaOH, H2O, and 1, 4-dioxane to obtain a second mixture, and heating the second mixture under inert atmosphere at 90˜110° C. for 10˜14 h to obtain a second product; separating the second product to obtain 5-methoxy-2-(10H-phenothiazin-10-yl)benzoic acid; and (3) mixing the 5-methoxy-2-(10H-phenothiazin-10-yl)benzoic acid and polyphosphoric acid to obtain a third mixture, and heating the third mixture under inert atmosphere at 140˜150° C. for 10˜14 h to obtain a third product; separating the third product to obtain the conjugation-fused bipolar redox-active molecule.

7. A method for preparing a conjugation-fused bipolar redox-active molecule; wherein the molecule comprises a p-type redox active center and an n-type redox active center; wherein the p-type redox active center and the n-type redox active center are fused in a molecular unit by conjugation; the p-type redox active center is a quaternary nitrogen and the n-type redox active center is a carbonyl ketone; the molecule has a structural formula as: ##STR00016## the method comprises: (1) mixing 10H-phenothiazine, methyl 2-bromo-5-fluorobenzoate, cesium carbonate, Pd(OAc).sub.2, 2-dicyclohexylphosphino-2′,4′,6′-triisopropylbiphenyl, and o-xylene and removing oxygen to obtain a fourth mixture, and heating the fourth mixture at 125˜135° C. for 20˜28 h to obtain a fourth product; separating the fourth product to obtain methyl 5-fluoro-2-(10H-phenothiazin-10-yl)benzoate; (2) mixing the methyl 5-fluoro-2-(10H-phenothiazin-10-yl)benzoate, NaOH, H2O, and 1, 4-dioxane to obtain a fifth mixture and heating the fifth mixture under inert atmosphere at 90˜110° C. for 10˜14 h to obtain a fifth product; separating the fifth product to obtain 5-fluoro-2-(10H-phenothiazin-10-yl)benzoic acid; (3) mixing the 5-fluoro-2-(10H-phenothiazin-10-yl)benzoic acid and polyphosphoric acid to obtain a sixth mixture, and heating the sixth mixture under inert atmosphere at 140˜150° C. for 10˜14 h to obtain a sixth product; separating the sixth product to obtain 11-fluoro-9H-quinolo[3,2,1-kl]phenothiazin-9-one; and (4) mixing the 11-fluoro-9H-quinolo[3,2,1-kl]phenothiazine-9-one, triethylene glycol monomethyl ether, NaH, and N,N-dimethylformamide to obtain a seventh mixture, and heating the seventh mixture under inert atmosphere and 75˜85° C. for 10˜14 h to obtain a seventh product; separating the seventh product to obtain the conjugation-fused bipolar redox-active molecule.

8. A symmetric redox flow battery, comprising a cathode electrolyte and an anode electrolyte; wherein the cathode electrolyte and the anode electrolyte both contain a conjugation-fused bipolar redox-active molecule; wherein the molecule comprises a p-type redox active center and an n-type redox active center; wherein the p-type redox active center and the n-type redox active center are fused in a molecular unit by conjugation.

9. The battery according to claim 8, wherein the cathode electrolyte and the anode electrolyte both further contain an electrolyte salt and an organic solvent.

10. The battery according to claim 8, being a static flow battery or a dynamic flow battery.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0044] FIG. 1 is a schematic diagram of charge transfer of a conjugation-fused bipolar redox-active molecule.

[0045] FIG. 2 is a nuclear magnetic resonance .sup.1H spectrum of QPT-OMe prepared in Embodiment 1.

[0046] FIG. 3 is a cyclic voltammetric test curves of QPT-OMe prepared in Embodiment 1.

[0047] FIG. 4 is a nuclear magnetic resonance .sup.1H spectrum of QPT-TEG prepared in Embodiment 2.

[0048] FIG. 5 is a cyclic voltammetric test curve of QPT-TEG prepared in Embodiment 2.

[0049] FIG. 6 is a cyclic voltammetric test curve of a mixture of QPT-OME and QPT-TEG.

[0050] FIG. 7 is a schematic diagram of a battery structure and an electrochemical process during battery charging of an QPT-OMe-based bipolar flow battery.

[0051] FIG. 8 shows representative charge and discharge curves of an QPT-OMe-based bipolar static flow battery at different current densities.

[0052] FIG. 9 shows selected charge and discharge curves during a long cycle for an QPT-OMe-based bipolar static flow battery.

[0053] FIG. 10 shows corresponding capacity retention, coulombic efficiency, and energy efficiency for an QPT-OMe-based bipolar static flow battery.

[0054] FIG. 11 shows representative constant current charge/discharge curves for an QPT-OMe in a bipolar static flow battery in a polarity reversal test.

[0055] FIG. 12 shows long cycle battery charge/discharge curves of an QPT-OMe in a bipolar static flow battery in a polarity reversal test.

[0056] FIG. 13 shows corresponding charge/discharge capacity, coulombic efficiency, and energy efficiency of an QPT-OMe in a bipolar static flow battery in a polarity reversal test.

[0057] FIG. 14 shows selected charge/discharge curves during a long cycle for an QPT-OMe-based bipolar dynamic flow battery.

[0058] FIG. 15 shows capacity retention, coulombic efficiency, and energy efficiency of an QPT-OMe-based bipolar dynamic flow battery.

[0059] FIG. 16 shows selected charge/discharge curves during a long cycle for an QPT-TEG based bipolar static flow battery.

[0060] FIG. 17 shows capacity retention, coulombic efficiency, and energy efficiency of an QPT-TEG-based bipolar static flow battery.

DETAILED DESCRIPTION

[0061] The present disclosure is further described below in conjunction with embodiments.

Embodiment 1

[0062] A conjugation-fused bipolar redox-active molecule (QPT-OMe) with the following structural formula.

##STR00006##

[0063] QPT-OMe may be prepared by the following steps.

(1) Synthesis of methyl 5-methoxy-2-(10H-phenothiazin-10-yl)benzoate

[0064] A mixture of 10H-phenothiazine (0.796 g, 4.0 mmol), methyl 2-bromo-5-methoxybenzoate (1.029 g, 4.2 mmol), cesium carbonate (3.910 g, 12.0 mmol), catalyst Pd(OAc).sub.2 (90 mg), and ligand XPhos (381 mg) is added to o-xylene (40 mL), degassed by freezing-pumping-thawing, charged with nitrogen, and heated to react at 130° C. for 24 h. After the reaction is completed, the resultant is cooled to room temperature, extracted with dichloromethane (DCM), and the mixed organic phase is collected and concentrated to obtain a crude product, which is later purified by silica gel column chromatography to obtain a yellow solid, methyl 5-methoxy-2-(10H-phenothiazin-10-yl)benzoate, in a yield of 24%.

(2) Synthesis of 5-methoxy-2-(10H-phenothiazin-10-yl)benzoic acid

[0065] Methyl 5-methoxy-2-(10H-phenothiazin-10-yl)benzoate (0.544 g, 1.5 mmol), NaOH (0.480 g, 12 mmol), H.sub.2O (10 mL), and 1,4-dioxane (20 mL) are mixed and heated under nitrogen atmosphere at 100° C. for 12 h. After the reaction is completed, the resultant is cooled to room temperature and aqueous hydrogen chloride solution (1 M) is added dropwise until a white solid precipitate is formed and the pH is less than 1. Filtration is performed and a resulting solid is washed completely with water to obtain a product of 96% purity, namely 5-methoxy-2-(10H-phenothiazin-10-yl)benzoic acid.

(3) Synthesis of QPT-OMe

[0066] 5-methoxy-2-(10H-phenothiazin-10-yl)benzoic acid and polyphosphoric acid (PAA) (50 mL) are mixed and heated under nitrogen atmosphere at 140° C. for 12 h. After the reaction is completed, the resultant is cooled to room temperature and is added with ice water (200 mL) dropwise and then extracted with DCM. The organic phase is collected, dried with anhydrous magnesium sulfate, and concentrated. A crude product is purified by silica gel column chromatography to obtain a yellow solid, QPT-OMe, in a yield of 45%.

Embodiment 2

[0067] A conjugation-fused bipolar redox-active molecule (QPT-OMe) with the following structural formula.

##STR00007##

[0068] QPT-OMe may be prepared by the following steps.

(1) Synthesis of methyl 5-methoxy-2-(10H-phenothiazin-10-yl)benzoate

[0069] A mixture of 10H-phenothiazine (0.796 g, 4.0 mmol), methyl 2-bromo-5-methoxybenzoate (0.931 g, 3.8 mmol), cesium carbonate (3.258 g, 10.0 mmol), catalyst Pd(OAc).sub.2 (85 mg), and ligand XPhos (370 mg) is added to o-xylene (35 mL), degassed by freezing-pumping-thawing, charged with nitrogen, and heated to react at 125° C. for 28 h. After the reaction is completed, the resultant is cooled to room temperature, extracted with dichloromethane (DCM), and the mixed organic phase is collected and concentrated to obtain a crude product, which is later purified by silica gel column chromatography to obtain a yellow solid, methyl 5-methoxy-2-(10H-phenothiazin-10-yl)benzoate.

(2) Synthesis of 5-methoxy-2-(10H-phenothiazin-10-yl)benzoic acid

[0070] Methyl 5-methoxy-2-(10H-phenothiazin-10-yl)benzoate (0.544 g, 1.5 mmol), NaOH (0.400 g, 10 mmol), H.sub.2O (8 mL), and 1,4-dioxane (16 mL) are mixed and heated under nitrogen atmosphere at 90° C. for 14 h. After the reaction is completed, the resultant is cooled to room temperature and aqueous hydrogen chloride solution (0.8 M) is added dropwise until a white solid precipitate is formed and the pH is less than 1. Filtration is performed and a resulting solid is washed completely with water to obtain a product, namely 5-methoxy-2-(10H-phenothiazin-10-yl)benzoic acid.

(3) Synthesis of QPT-OMe

[0071] 5-methoxy-2-(10H-phenothiazin-10-yl)benzoic acid and polyphosphoric acid (PAA) (47 mL) are mixed and heated under nitrogen atmosphere at 145° C. for 14 h. After the reaction is completed, the resultant is cooled to room temperature and is added with ice water (200 mL) dropwise and then extracted with DCM. The organic phase is collected, dried with anhydrous magnesium sulfate, and concentrated. A crude product is purified by silica gel column chromatography to obtain a yellow solid, QPT-OMe.

Embodiment 3

[0072] A conjugation-fused bipolar redox-active molecule (QPT-OMe) with the following structural formula.

##STR00008##

[0073] QPT-OMe may be prepared by the following steps.

(1) Synthesis of methyl 5-methoxy-2-(10H-phenothiazin-10-yl)benzoate

[0074] A mixture of 10H-phenothiazine (0.796 g, 4.0 mmol), methyl 2-bromo-5-methoxybenzoate (0.980 g, 4.0 mmol), cesium carbonate (4.888 g, 15.0 mmol), catalyst Pd(OAc).sub.2 (93 mg), and ligand XPhos (385 mg) is added to o-xylene (45 mL), degassed by freezing-pumping-thawing, charged with nitrogen, and heated to react at 130° C. for 20 h. After the reaction is completed, the resultant is cooled to room temperature, extracted with dichloromethane (DCM), and the mixed organic phase is collected and concentrated to obtain a crude product, which is later purified by silica gel column chromatography to obtain a yellow solid, methyl 5-methoxy-2-(10H-phenothiazin-10-yl)benzoate, in a yield of 24%.

(2) Synthesis of 5-methoxy-2-(10H-phenothiazin-10-yl)benzoic acid

[0075] Methyl 5-methoxy-2-(10H-phenothiazin-10-yl)benzoate (0.544 g, 1.5 mmol), NaOH (0.600 g, 15 mmol), H.sub.2O (13 mL), and 1,4-dioxane (25 mL) are mixed and heated under nitrogen atmosphere at 110° C. for 10 h. After the reaction is completed, the resultant is cooled to room temperature and aqueous hydrogen chloride solution (1.2 M) is added dropwise until a white solid precipitate is formed and the pH is less than 1. Filtration is performed and a resulting solid is washed completely with water to obtain a product of 96% purity, namely 5-methoxy-2-(10H-phenothiazin-10-yl)benzoic acid.

(3) Synthesis of QPT-OMe

[0076] 5-methoxy-2-(10H-phenothiazin-10-yl)benzoic acid and polyphosphoric acid (PAA) (55 mL) are mixed and heated under nitrogen atmosphere at 150° C. for 10 h. After the reaction is completed, the resultant is cooled to room temperature and is added with ice water (200 mL) dropwise and then extracted with DCM. The organic phase is collected, dried with anhydrous magnesium sulfate, and concentrated. A crude product is purified by silica gel column chromatography to obtain a yellow solid, QPT-OMe, in a yield of 45%.

Embodiment 4

[0077] A conjugation-fused bipolar redox-active molecule (QPT-TEG) with the following structural formula.

##STR00009##

[0078] QPT-TEG may be prepared by the following steps.

(1) Synthesis of methyl 5-fluoro-2-(10H-phenothiazin-10-yl)benzoate

[0079] A mixture of 10H-phenothiazine (0.796 g, 4.0 mmol), methyl 2-bromo-5-fluorobenzoate (0.979 g, 4.2 mmol), cesium carbonate (3.910 g, 12.0 mmol), catalyst Pd(OAc).sub.2 (90 mg) and ligand XPhos (381 mg) is added to o-xylene (40 mL), degassed by freezing-pumping-thawing, charged with nitrogen, and heated to react at 130° C. for 24 h. After the reaction is completed, the resultant is cooled to room temperature, extracted with dichloromethane (DCM), and the mixed organic phase is collected and concentrated to obtain a crude product, which is later purified by silica gel column chromatography to obtain a yellow solid, methyl 5-fluoro-2-(10H-phenothiazin-10-yl)benzoate, in a yield of 35%.

(2) Synthesis of 5-methoxy-2-(10H-phenothiazin-10-yl)benzoic acid

[0080] Methyl 5-methoxy-2-(10H-phenothiazin-10-yl)benzoate (0.702 g, 2.0 mmol), NaOH (0.480 g, 12 mmol), H.sub.2O (10 mL), and 1,4-dioxane (20 mL) are mixed and heated under nitrogen atmosphere at 100° C. for 12 h. After the reaction is completed, the resultant is cooled to room temperature and aqueous hydrogen chloride solution (1 M) is added dropwise until a white solid precipitate is formed and the pH is less than 1. Filtration is performed and a resulting solid is washed completely with water to obtain a product of 96% purity, namely 5-methoxy-2-(10H-phenothiazin-10-yl)benzoic acid.

(3) Synthesis of 11-fluoro-9H-quinolo[3,2,1-kl]phenothiazin-9-one

[0081] 5-Fluoro-2-(10H-phenothiazin-10-yl)benzoic acid (0.505 g, 1.5 mmol) and polyphosphoric acid (50 mL) are mixed and heated under nitrogen atmosphere at 140° C. for 12 h. After the reaction is completed, the resultant is cooled to room temperature and is added with ice water (200 mL) dropwise and then extracted with DCM. The organic phase is collected, dried with anhydrous magnesium sulfate, and concentrated. A crude product is purified by silica gel column chromatography to obtain a yellow solid, 11-fluoro-9H-quinolo[3,2,1-kl]phenothiazine-9-one, in a yield of 66%.

(4) Synthesis of QPT-TEG

[0082] 11-fluoro-9H-quinolinolo[3,2,1-kl]phenothiazin-9-one (0.319 g, 1.0 mmol), triglyceride monomethyl ether (0.164 g, 1.0 mmol), NaH (0.200 g, 5.0 mmol, dispersed in liquid paraffin at 60 wt % by mass), and N,N-dimethylformamide (DMF) are mixed and heated under nitrogen atmosphere at 80° C. for 12 h. After the reaction is completed, the resultant is cooled to room temperature and is extracted with DCM. The organic phase is collected, dried with anhydrous magnesium sulfate, and concentrated. A crude product is purified by silica gel column chromatography to obtain an orange colloidal liquid, QPT-TEG, in a yield of 70%.

Embodiment 5

[0083] A conjugation-fused bipolar redox-active molecule (QPT-TEG) with the following structural formula.

##STR00010##

[0084] QPT-TEG may be prepared by the following steps.

(1) Synthesis of methyl 5-fluoro-2-(10H-phenothiazin-10-yl)benzoate

[0085] A mixture of 10H-phenothiazine (0.796 g, 4.0 mmol), methyl 2-bromo-5-fluorobenzoate (0.886 g, 3.8 mmol), cesium carbonate (3.258 g, 10.0 mmol), catalyst Pd(OAc).sub.2 (85 mg) and ligand XPhos (370 mg) is added to o-xylene (35 mL), degassed by freezing-pumping-thawing, charged with nitrogen, and heated to react at 125° C. for 28 h. After the reaction is completed, the resultant is cooled to room temperature, extracted with dichloromethane (DCM), and the mixed organic phase is collected and concentrated to obtain a crude product, which is later purified by silica gel column chromatography to obtain a yellow solid, methyl 5-fluoro-2-(10H-phenothiazin-10-yl)benzoate.

(2) Synthesis of 5-methoxy-2-(10H-phenothiazin-10-yl)benzoic acid

[0086] Methyl 5-methoxy-2-(10H-phenothiazin-10-yl)benzoate (0.702 g, 2.0 mmol), NaOH (0.400 g, 10 mmol), H.sub.2O (8 mL), and 1,4-dioxane (16 mL) are mixed and heated under nitrogen atmosphere at 90° C. for 14 h. After the reaction is completed, the resultant is cooled to room temperature and aqueous hydrogen chloride solution (1 M) is added dropwise until a white solid precipitate is formed and the pH is less than 1. Filtration is performed and a resulting solid is washed completely with water to obtain a product of 96% purity, namely 5-methoxy-2-(10H-phenothiazin-10-yl)benzoic acid.

(3) Synthesis of 11-fluoro-9H-quinolo[3,2,1-kl]phenothiazin-9-one

[0087] 5-Fluoro-2-(10H-phenothiazin-10-yl)benzoic acid (0.505 g, 1.5 mmol) and polyphosphoric acid (47 mL) are mixed and heated under nitrogen atmosphere at 145° C. for 14 h. After the reaction is completed, the resultant is cooled to room temperature and is added with ice water (200 mL) dropwise and then extracted with DCM. The organic phase is collected, dried with anhydrous magnesium sulfate, and concentrated. A crude product is purified by silica gel column chromatography to obtain a yellow solid, 11-fluoro-9H-quinolo[3,2,1-kl]phenothiazine-9-one.

(4) Synthesis of QPT-TEG

[0088] 11-fluoro-9H-quinolinolo[3,2,1-kl]phenothiazin-9-one (0.319 g, 1.0 mmol), triglyceride monomethyl ether (0.197 g, 1.2 mmol), NaH (0.212 g, 5.3 mmol, dispersed in liquid paraffin at 60 wt % by mass), and N,N-dimethylformamide (DMF) are mixed and heated under nitrogen atmosphere at 80° C. for 12 h. After the reaction is completed, the resultant is cooled to room temperature and is extracted with DCM. The organic phase is collected, dried with anhydrous magnesium sulfate, and concentrated. A crude product is purified by silica gel column chromatography to obtain an orange colloidal liquid, QPT-TEG.

Embodiment 6

[0089] A conjugation-fused bipolar redox-active molecule (QPT-TEG) with the following structural formula.

##STR00011##

[0090] QPT-TEG may be prepared by the following steps.

(1) Synthesis of methyl 5-fluoro-2-(10H-phenothiazin-10-yl)benzoate

[0091] A mixture of 10H-phenothiazine (0.796 g, 4.0 mmol), methyl 2-bromo-5-fluorobenzoate (0.932 g, 4.0 mmol), cesium carbonate (4.888 g, 15.0 mmol), catalyst Pd(OAc).sub.2 (93 mg) and ligand XPhos (385 mg) is added to o-xylene (45 mL), degassed by freezing-pumping-thawing, charged with nitrogen, and heated to react at 130° C. for 20 h. After the reaction is completed, the resultant is cooled to room temperature, extracted with dichloromethane (DCM), and the mixed organic phase is collected and concentrated to obtain a crude product, which is later purified by silica gel column chromatography to obtain a yellow solid, methyl 5-fluoro-2-(10H-phenothiazin-10-yl)benzoate.

(2) Synthesis of 5-methoxy-2-(10H-phenothiazin-10-yl)benzoic acid

[0092] Methyl 5-methoxy-2-(10H-phenothiazin-10-yl)benzoate (0.702 g, 2.0 mmol), NaOH (0.600 g, 15 mmol), H.sub.2O (13 mL), and 1,4-dioxane (25 mL) are mixed and heated under nitrogen atmosphere at 110° C. for 10 h. After the reaction is completed, the resultant is cooled to room temperature and aqueous hydrogen chloride solution (1.2 M) is added dropwise until a white solid precipitate is formed and the pH is less than 1. Filtration is performed and a resulting solid is washed completely with water to obtain a product of 96% purity, namely 5-methoxy-2-(10H-phenothiazin-10-yl)benzoic acid.

(3) Synthesis of 11-fluoro-9H-quinolo[3,2,1-kl]phenothiazin-9-one

[0093] 5-Fluoro-2-(10H-phenothiazin-10-yl)benzoic acid (0.505 g, 1.5 mmol) and polyphosphoric acid (55 mL) are mixed and heated under nitrogen atmosphere at 150° C. for 10 h. After the reaction is completed, the resultant is cooled to room temperature and is added with ice water (200 mL) dropwise and then extracted with DCM. The organic phase is collected, dried with anhydrous magnesium sulfate, and concentrated. A crude product is purified by silica gel column chromatography to obtain a yellow solid, 11-fluoro-9H-quinolo[3,2,1-kl]phenothiazine-9-one.

(4) Synthesis of QPT-TEG

[0094] 11-fluoro-9H-quinolinolo[3,2,1-kl]phenothiazin-9-one (0.319 g, 1.0 mmol), triglyceride monomethyl ether (0.230 g, 1.4 mmol), NaH (0.220 g, 5.5 mmol, dispersed in liquid paraffin at 60 wt % by mass), and N,N-dimethylformamide (DMF) are mixed and heated under nitrogen atmosphere at 80° C. for 12 h. After the reaction is completed, the resultant is cooled to room temperature and is extracted with DCM. The organic phase is collected, dried with anhydrous magnesium sulfate, and concentrated. A crude product is purified by silica gel column chromatography to obtain an orange colloidal liquid, QPT-TEG, in a yield of 70%.

Test Example 1: QPT-OMe

[0095] NMR characterization of QPT-OMe obtained in Embodiment 1 is performed, and the results are shown in FIG. 2. In the NMR .sup.1H spectrum of QPT-OMe, .sup.1H NMR (400 MHz, DMSO-d6, ppm) δ=8.06 (dd, J=8.0, 1.4 Hz, 1H), 7.82 (d, J=9.2 Hz, 1H), 7.73 (dt, J=7.6, 1.3 Hz, 1H), 7.66 (d, J=3.1 Hz, 1H), 7.58−7.49 (m, 1H), 7.47−7.36 (m, 2H), 7.35−7.23 (m, 3H), 3.92 (s, 3H).

[0096] Redox kinetics of QPT-OMe obtained in Embodiment 1 is tested by cyclic voltammetry (CV). Tetrabutylammonium bis(trifluoromethylsulfonyl)imide (TBA-TF SI) is used as a supporting electrolyte and acetonitrile as a solvent. The results are shown in FIG. 3, where two pairs of symmetrical cathodic and anodic peaks can be clearly observed. The half-wave potentials of −2.04 and 0.72 V (with respect to Ag.sup.+/Ag) correspond to the reduction and oxidation reactions of QPT-OMe, respectively. The open-circuit voltage is about 2.76 V when using QPT-OMe as the active material in the RFB, which is one of the highest value for bipolar molecules so far.

[0097] Furthermore, the QPT-OMe/QPT-OMe and QPT-P-OMe/QPT-OMe redox pairs show high rate constants of 1.4×10.sup.−2 and 1.6×10−2 cm s.sup.−1, respectively, by calculation. This is probably due to the relatively low recombination energy required for single electron transfer to occur from a large off-domain π-conjugated system. The high rate constants also imply negligible voltage loss when electrochemical reactions occur at the electrode surface.

Test Example 2: QPT-TEG

[0098] NMR characterization of QPT-TEG obtained in Embodiment 4 is performed, and the results are shown in FIG. 4. In the NMR .sup.1H spectrum of QPT-TEG, .sup.1H NMR (400 MHz, DMSO-d6, ppm) δ=8.06 (dd, J=8.0, 1.4 Hz, 1H), 7.82 (d, J=9.2 Hz, 1H), 7.74 (dd, J=7.4, 1.4 Hz, 1H), 7.67 (d, J=3.0 Hz, 1H), 7.57−7.52 (m, 1H), 7.45−7.40 (m, 2H), 7.32−7.25 (m, 3H), 4.29−4.24 (m, 2H), 3.84−3.80 (m, 2H), 3.62 (dd, J=5.7, 3.1 Hz, 2H), 3.58−3.50 (m, 4H), 3.42 (dd, J=5.8, 3.7 Hz, 2H), 3.23 (s, 3H).

[0099] The redox kinetics of QPT-TEG obtained in Embodiment 4 is tested by cyclic voltammetry (CV). Tetrabutylammonium bis(trifluoromethylsulfonyl)imide (TBA-TF SI) is used as a supporting electrolyte and acetonitrile as a solvent. As shown in FIG. 5, the redox behavior of QPT-TEG is basically the same as that of QPT-OMe.

Test Example 3: Mixture of QPT-OMe and QPT-TEG

[0100] QPT-OMe obtained in Embodiment 1 and QPT-TEG obtained in Embodiment 2 are mixed in a 1:1 molar ratio, and the mixture is subjected to electrochemical cyclic voltammetry tests, and the results are shown in FIG. 6, where the waveforms of the two materials completely overlap, indicating that functionalization using polar groups is an easy and effective way to increase the energy density without severely altering the redox of the QPT nuclei behavior and electronic configuration.

Application Example 1: QPT-OMe-Based Bipolar Static Flow Battery

[0101] The acetonitrile mixture of QPT-OMe and TBA-TFSI made in Embodiment 1 is used as cathode and anode electrolytes (where the concentrations of QPT-OMe and TBA-TFSI are 0.025 M and 0.5 M, respectively), and a porous membrane Daramic AA-800 is used as a membrane and graphite carbon felt is used as a collector to form a static flow battery.

[0102] FIG. 7 is a schematic diagram of a battery structure and an electrochemical process during battery charging of an QPT-OMe-based bipolar static flow battery.

[0103] 0.1 mL of electrolyte is injected into both the cathode and anode reservoirs of the battery, and the charging and discharging cycles are tested with a charging current density of 5 mA cm.sup.−1 and a discharging current density of 5 mA cm.sup.−1. The test results are shown in FIGS. 8 to 10.

[0104] FIG. 8 shows representative charge and discharge curves of an QPT-OMe-based bipolar static flow battery at different current densities. A clear charging/discharging plateau is exhibited at all measured current densities. At low current densities (<5 mA cm.sup.−1), the discharge voltage is 2.5 to 2.7 V, which is one of the highest values of discharge voltage available for RFBs. At high current densities of 20 mA cm.sup.−2, the battery exhibits dense differential polarization due to limited mass transfer in the electrolyte and across the membrane. The utilization rates of QPT-OMe at current densities of 1, 2, 5, 10 and 20 mA cm.sup.−2 are 77.6, 86.3, 94.3, 97.6 and 65.4%, respectively, with corresponding coulombic efficiencies (CE) of 70.0, 82.1, 90.6, 92.9 and 92.8%, respectively. At a current density of 20 mA cm.sup.−2, the utilization rate decreases, which may be due to the increase in mass transfer limitation and voltage hysteresis, but the CE still increases due to the shortened charge/discharge time.

[0105] FIG. 9 shows selected charge and discharge curves during a long cycle for an QPT-OMe-based bipolar static flow battery. The voltage plateau remains almost constant over 900 cycles, which is further demonstrated by the differential capacity analysis shown in the inset on the right side of FIG. 9, where the potential ranges as well as the peak positions for the charging (2.7 to 3.1 V) and discharging (2.4 to 2.7 V) processes do not change over long periods of time.

[0106] FIG. 10 shows corresponding capacity retention, coulombic efficiency, and energy efficiency for an QPT-OMe-based bipolar static flow battery. After 900 cycles, the capacity retention of the battery is about 63.5%, the decay rate is about 0.4%0 per cycle, and the coulombic efficiency and energy efficiency reach about 97% and 84%, respectively. The presented performance is superior to most non-aqueous phase flow batteries that use BRM or asymmetric organic molecules as active materials.

[0107] A polarity reversal test is performed by filling 0.1 mL of electrolyte into both the cathode and anode reservoirs of the battery with a charging current density of 5 mA cm.sup.−1 and a discharging current density of 5 mA cm.sup.−1. The polarity of the battery is reversed every 50 cycles, and the current is reversed 4 times before 300 cycles. The test results are shown in FIGS. 11 to 13.

[0108] FIG. 11 shows representative constant current charge/discharge curves for an QPT-OMe in a bipolar static flow battery in a polarity reversal test.

[0109] FIG. 12 shows long cycle battery charge/discharge curves of an QPT-OMe in a bipolar static flow battery in a polarity reversal test.

[0110] FIG. 13 shows corresponding charge/discharge capacity, coulombic efficiency, and energy efficiency of an QPT-OMe in a bipolar static flow battery in a polarity reversal test.

[0111] The charge/discharge curves (FIGS. 11 and 12) exhibit a high degree of symmetry throughout the cycle and no deviation is observed between two consecutive charge or discharge cycles. 56% capacity retention is achieved, and the coulombic efficiency and energy efficiency are maintained at approximately 94% and 86%, respectively, after 500 cycles (FIG. 13).

Application Example 2: QPT-OMe-Based Bipolar Dynamic Flow Battery

[0112] The acetonitrile mixture of QPT-OMe and TBA-TFSI made in Embodiment 1 is used as cathode and anode electrolytes (where the concentrations of QPT-OMe and TBA-TFSI are 0.025 M and 0.5 M, respectively), and a porous membrane Daramic AA-800 is used as a membrane and graphite carbon is used as a collector to form a dynamic flow battery.

[0113] 3 mL of electrolyte is injected into both the cathode and anode reservoirs of the battery, and a circulation pump is started to make the electrolyte flow from the reservoir through a circulation pipe to the cathode and anode of the battery, and the charging and discharging cycles are tested with a charging current density of 10 mA cm.sup.−1 and a discharging current density of 10 mA cm.sup.−1. The test results are shown in FIGS. 14 to 15.

[0114] FIG. 14 shows selected charge/discharge curves during a long cycle for an QPT-OMe-based bipolar dynamic flow battery. The voltage plateau remains almost constant over 50 cycles. The charge/discharge curves are the same as FIG. 9, with a first utilization rate of 83.5%.

[0115] FIG. 15 shows capacity retention, coulombic efficiency, and energy efficiency of an QPT-OMe-based bipolar dynamic flow battery. The capacity retention of the battery is about 73.8%, and the coulombic efficiency and energy efficiency are maintained at 95% and 87%, respectively, after 50 charge and discharge cycles.

Application Example 3: QPT-TEG-Based Bipolar Static Flow Battery

[0116] An acetonitrile mixture of QPT-TEG and TBA-TFSI made in Embodiment 4 is used as cathode and anode electrolytes (where the concentrations of QPT-TEG and TBA-TFSI are 0.5 M and 0.5 M, respectively), and a porous membrane Daramic AA-800 is used as a membrane and graphite carbon is used as a collector to form a static flow battery.

[0117] 0.1 mL of electrolyte is injected into both the cathode and anode reservoirs of the battery, and the charge and discharge cycles are tested with a charge current density of 5 mA cm.sup.−1 and a discharge current density of 5 mA cm.sup.−1. The test results are shown in FIGS. 16 to 17.

[0118] FIG. 16 shows selected charge/discharge curves during a long cycle for an QPT-TEG based bipolar static flow battery. The voltage plateau is maintained at about 2.3 V during discharge.

[0119] FIG. 17 shows capacity retention, coulombic efficiency, and energy efficiency of an QPT-TEG-based bipolar static flow battery. The utilization of active substance in the first cycle is 74.6%, and the discharge capacity remained 63% after 200 cycles. Compared with low concentration batteries, both the active substance utilization and capacity retention decreases, which is common in RFBs using high concentration electrolytes.

[0120] The raw materials and equipment used in the present disclosure, if not otherwise specified, are commonly used in the field; the methods used in the present disclosure, if not otherwise specified, are conventional methods in the field.

[0121] The above mentioned is only prefer embodiments of the present disclosure, not any limitation of the present disclosure, and any simple modification, change and equivalent transformation of the above embodiment according to the technical substance of the present disclosure are still within the scope of the technical solution of the present disclosure.