CN111934029A - High-rate and low-self-discharge zinc-organic battery and application thereof - Google Patents

Abstract

The invention discloses a zinc-organic battery with high rate and low self-discharge and its application. The zinc-organic battery Zn//r-PTCDA positive electrode material of the present invention is r-PTCDA material, the negative electrode material is zinc, the electrolyte is an inorganic zinc ion aqueous solution, and has a high specific capacity of 126.4 mA h/g, and the current density increases by 160 It also has a capacity retention rate of 62.6% under the condition of 32A/g, has excellent rate performance, and maintains 70% of the capacity after 1000 cycles, with good cycle stability. After 24 hours of standing, the battery Basically no capacity loss, capacity retention rate > 99.9%, low self-discharge of the battery, high rate, long life, repeatable charge and discharge and low self-discharge, it has great application prospects in energy storage.

Description

A high rate, low self-discharge zinc-organic battery and its application

technical field

The present invention relates to the technical field of electrochemical energy storage batteries, and more particularly, to a zinc-organic battery with high rate and low self-discharge and its application.

Background technique

With the rapid growth of the world population and the continuous development of human society, people's various demands for energy are increasing day by day. With the depletion of fossil energy, environmental pollution is increasing day by day. In recent years, many green and environmentally friendly renewable energy and clean energy have been developed, such as wind energy, solar energy, tidal energy and geothermal energy. However, due to the shortcomings of intermittency and geographical dispersion, renewable energy cannot provide large-scale, continuous and stable electrical energy. At this time, it is necessary to develop safe and reliable new electrical energy storage devices to realize energy storage and transportation. New energy storage devices with large specific capacity, good cycle stability, high power density and energy density can not only improve the utilization rate and application scope of renewable energy to meet daily life, but also promote the development of high-tech.

Zinc-organic batteries are low-cost, high-efficiency, and practical new energy storage devices with the advantages of low cost and good cycle stability. It uses metallic zinc as the negative electrode, organic compounds as the positive electrode, and an aqueous solution containing zinc ions as the electrolyte, which is safe, non-toxic and environmentally friendly. Unlike very active lithium and sodium metal electrodes, zinc electrodes are stable in both air and water, so they are very suitable for water-based energy storage devices. Compared with traditional transition metal compounds, organic compound cathodes have much lower cost and difficulty in recycling, and their capacity and cycle stability are even better than metal-based cathodes, so they have great development prospects. At present, the development of Zn-organic batteries is still in its infancy, and many aspects are immature. For example, due to the sharply increased ion/electron diffusion resistance at high loadings, the rate performance of Zn-organic batteries at high current densities is not good enough. , cannot store enough energy in the case of rapid discharge. At the same time, due to the mechanism of adsorption and desorption of cations on the surface of many organic materials during the charging and discharging process, the self-discharge of zinc-organic batteries composed of them is very serious. Therefore, developing a Zn-organic battery with high rate capability and low self-discharge through structural optimization remains a major challenge at present.

CN107069089A discloses an electrolyte and a lithium ion battery, the electrolyte includes lithium salts, additives, organic solvents and metal salts, and the metal salts are sodium salts, potassium salts, calcium salts, copper salts, zinc salts and nickel salts at least one of them. It is mainly to increase the conductivity of the electrolyte by adding metal salts to the electrolyte, reduce the internal resistance of the battery, and improve the rate performance of the battery. The radius of sodium ion in sodium salt, potassium ion in potassium salt, calcium ion in calcium salt, copper ion in copper salt, zinc ion in zinc salt or nickel ion in nickel salt is larger than that of lithium ion in lithium salt The large radius of the SEI film can make the pore size of the SEI film moderately increase. The SEI film produced in this way is conducive to the entry and exit of lithium ions, reduces the internal resistance of the battery, and improves the rate performance and cycle performance of the battery. However, it is not aimed at improving the rate performance and self-discharge performance of zinc-organic batteries at high current density, and the rate performance improvement effect is limited, and cannot solve the problem of improving the rate performance and self-discharge performance of existing zinc-organic batteries.

SUMMARY OF THE INVENTION

The technical problem to be solved by the present invention is to overcome the defects and deficiencies of the rate performance and self-discharge performance of the existing zinc-organic batteries, and provide a zinc-organic battery with high rate and low self-discharge.

The purpose of the present invention is to provide a zinc-organic battery with high rate and low self-discharge in the field of electrochemical energy storage.

The above-mentioned purpose of the present invention is achieved through the following technical solutions:

A zinc-organic battery with high rate and low self-discharge, wherein the positive electrode material of the zinc-organic battery is r-PTCDA material, the negative electrode material is zinc, and the electrolyte is an aqueous solution of inorganic zinc ions.

The r-PTCDA material is the r-PTCDA organic molecular crystal obtained by the sublimation-sublimation recrystallization method of 3,4,9,10-perylenetetracarboxylic dianhydride organic molecular crystal (PTCDA).

The zinc anode material can be a nanomaterial or a commercial zinc material such as a commercial zinc sheet, a zinc foil, a zinc wire, etc., wherein the nano zinc material is prepared by a constant current electrodeposition method, and the details are as follows:

Take 50～150g/L NaSO ₄ , 5～50g/LH ₃ BO ₃ , 50～150g/L ZnSO ₄ , or a mixed aqueous solution of 50～150g/L ZnCl ₂ as electrolyte, take graphite rod as auxiliary electrode, calomel electrode It is a reference electrode, and carbon paper is a working electrode. At room temperature, the constant current density is -1～100mA cm ^-2 , and the electrodeposition is 1～180min.

The preferred preparation method of Zn nanomaterials is as follows:

The mixed aqueous solution of 125g/L NaSO ₄ , 20g/LH ₃ BO ₃ and 125g/L ZnSO ₄ ·7H ₂ O was used as electrolyte, graphite rod as auxiliary electrode, calomel electrode as reference electrode, and carbon paper as working electrode. At room temperature, constant current density -30--70mAcm ^-2 , electrodeposition for 1-60min.

Preferably, the positive electrode of the zinc-organic battery is made by electrode film forming technology. The specific operation is as follows: mixing the r-PTCDA material with acetylene black and PVDF uniformly to obtain a mixed powder slurry, using NMP as a dispersant, and coating the film on the substrate It is prepared by drying under vacuum heating for 5 to 48 hours.

The content of acetylene black per 100 mg of mixed powder slurry is 5-15 mg, the content of PVDF is 5-15 mg, 0.1-1 mL of NMP is added dropwise to each 100 mg of mixed powder, and 0.1-15 mg of mixed powder is coated per 1 cm ² of base.

Preferably, the content of acetylene black in every 100 mg of the mixed powder slurry is 5-15 mg, and the content of PVDF is 5 mg.

Preferably, the vacuum drying temperature for making the positive electrode of the zinc-organic battery by the above-mentioned electrode film forming technology is 60-80° C., the vacuum degree is 100-5000 Pa, and the drying is performed for 24 hours.

Preferably, the particle size of the r-PTCDA material is 0.002-50 μm.

Preferably, the r-PTCDA material is obtained by heating the organic molecular crystals of 3,4,9,10-perylenetetracarboxylic dianhydride in an inert gas atmosphere, then cooling, desublimation and recrystallization,

The heating temperature is 400-600 DEG C, the holding time is 0.1-5 hours, the cooling temperature is 0-300 DEG C, and the holding time is 0.1-5 hours.

In the desublimation and recrystallization process of the present invention, the inert gas atmosphere is an inert gas atmosphere such as low-pressure N ₂ , Ar, He, etc., and the pressure thereof is 1-30 kPa.

Preferably, the heating temperature is 400-500° C., and the holding time is 0.1-2 hours.

Preferably, the cooling temperature is 100-200° C., and the holding time is 0.1-2 hours.

Further preferably, in the desublimation and recrystallization process of the present invention, the heating temperature is 500°C, the holding time is 1 hour, and the cooling is from 500°C to 100°C naturally, and the temperature is kept for 1 hour.

Preferably, the molar concentration of the electrolyte is 0.5-3 mol/L, and the pH is 1-5.5.

Preferably, the electrolyte is zinc chloride or zinc sulfate or zinc trifluoromethanesulfonate.

In the technical scheme of the present invention, the crystal form of PTCDA is adjusted by the sublimation-sublimation recrystallization method, and the kinetics of intercalation and deintercalation of zinc ions in the material is optimized, so as to realize the improvement of the rate performance and the reduction of self-discharge of the material; The pH improves the capacity and cycle performance of the battery; by adjusting the ratio of r-PTCDA cathode mixed powder, the number of NMP droplets and the loading of the substrate, the conductivity and cycle performance of the electrode are improved.

The application of the above-mentioned high rate, low self-discharge zinc-organic battery in the field of electrochemical energy storage is also within the protection scope of the present invention.

The zinc-organic battery Zn//r-PTCDA of the present invention can be packaged into AA batteries, button batteries, soft-pack batteries and the like.

Compared with the prior art, the beneficial effects of the present invention are:

The invention provides a zinc-organic battery that adjusts the crystal form of PTCDA through a sublimation-sublimation recrystallization method, optimizes the kinetics of zinc ion insertion and extraction of the material, and realizes the improvement of the rate performance and the reduction of self-discharge of the material; The species and its pH can improve the capacity and cycle performance of the battery; by adjusting the ratio of the r-PTCDA cathode mixed powder, the number of NMP drops and the loading of the substrate, the conductivity and cycle performance of the electrode can be improved.

The zinc-organic battery Zn//r-PTCDA of the present invention has a high specific capacity of 126.4 mA h/g, and also has a capacity retention rate of 62.6% under the condition that the current density is increased by 160 times and reaches 32 A/g, and has excellent Rate performance, after 1000 cycles, it still maintains 70% of the capacity, and has good cycle stability. The battery has basically no capacity loss after 24 hours of standing, and the capacity retention rate is >99.9%. The self-discharge of the battery is low, with high Rate, long life, repeatable charge and discharge and low self-discharge, have great application prospects in energy storage.

Description of drawings

Figure 1: (a) is a picture of commercially available PTCDA powder, (b) is a picture of r-PTCDA powder in Example 1.

Figure 2: X-ray diffraction comparison diagram of r-PTCDA powder in Example 1 and commercially available PTCDA powder.

Figure 3: The charge-discharge curve of the Zn//r-PTCDA battery in Example 1.

Figure 4: Cycle life test of the Zn//r-PTCDA battery in Example 1.

Figure 5: The discharge curve of the Zn//r-PTCDA battery in Example 1 after standing for 24 hours.

Detailed ways

The present invention will be further described below in conjunction with specific embodiments, but the embodiments do not limit the present invention in any form. Unless otherwise specified, the raw material reagents used in the examples of the present invention are conventionally purchased raw material reagents.

Example 1

A zinc-organic battery Zn//r-PTCDA with high rate and low self-discharge, wherein the positive electrode material of the zinc-organic battery is r-PTCDA material, the negative electrode material is zinc, and the electrolyte is an aqueous solution of inorganic zinc ions.

The preparation of r-PTCDA positive electrode is realized by electrode film forming technology, and r-PTCDA powder is obtained by sublimation-sublimation recrystallization method.

The preparation steps are as follows:

(a) Take commercially available PTCDA powder as raw material, heat it to 500°C under 20kPa _N2 atmosphere and keep it for 1 hour, then separate _N2 to cool it down to 100°C and keep it for 1 hour, collect the desublimated powder That is r-PTCDA powder;

(b) Take 90mgr-PTCDA powder, grind it with 5mg acetylene black powder and 5mg PVDF powder evenly, add 1mL NMP dropwise and stir until it becomes a paste;

(c) The paste mixture described in (b) was uniformly coated on carbon paper (5cm×10cm), dried for 24 hours under a vacuum degree of 200Pa and 70°C, and the r-PTCDA positive electrode was obtained after natural cooling.

The electrolyte of Zn//r-PTCDA battery is 2M ZnCl ₂ , and its pH value is 3.0.

Characterization and Performance Testing:

As shown in Figure 1, the r-PTCDA (b) obtained by sublimation-sublimation recrystallization is a brown powder, which is darker than the commercially available PTCDA powder (a).

减少至

说明了r-PTCDA中π-π堆叠作用增强。与商业锌片组装成纽扣电池。The X-ray diffraction test was carried out on the prepared r-PTCDA powder. The contrast image of it and PTCDA powder is shown in Figure 2. It can be seen that the crystal structure of the r-PTCDA powder has undergone a certain degree of transformation, and its (102) plane (ie stacked layer) Spacing by

reduce to

It shows that the π-π stacking effect is enhanced in r-PTCDA. Assembled with commercial zinc flakes into a coin cell battery.

Figure 3. The rate capability of the cells was tested with different current densities. As can be seen from the figure, the obtained Zn//r-PTCDA battery has a high specific capacity of 126.4 mA h/g. The zinc-organic battery prepared under the condition that the current density increased by 160 times to 32 A/g also had a capacity retention rate of 62.6%, indicating that the material has excellent rate performance.

It can be seen from Figure 4 that the battery still maintains 70% of the capacity after 1000 cycles, indicating that the material has good cycle stability. It can be seen from Figure 5 that the battery has basically no capacity loss after standing for 24 hours (capacity retention rate>99.9%), indicating that the battery has low self-discharge.

In conclusion, this Zn-organic battery has high rate, long life, repeatable charge and discharge and low self-discharge, and has great application prospects in energy storage.

Examples 2 to 17

The preparation methods of Examples 2-17 are the same as those of Example 1, except that the temperature used for sublimation-sublimation recrystallization and the corresponding time period, the ratio of acetylene black and PVDF in the mixed powder, and the composition of the electrolyte.

The specific temperature and time, composition ratio, electrolyte composition and the results of each example are listed in Tables 1-4.

Table 1. Sublimation-sublimation-recrystallization method sublimation conditions regulation

Table 2. Regulation of sublimation conditions for sublimation-sublimation recrystallization method

Table 3. Control of mixed powder slurry ratio

Table 4. Regulation of battery electrolyte composition

Obviously, the above-mentioned embodiments of the present invention are only examples for clearly illustrating the present invention, and are not intended to limit the embodiments of the present invention. For those of ordinary skill in the art, changes or modifications in other different forms can also be made on the basis of the above description. There is no need and cannot be exhaustive of all implementations here. Any modifications, equivalent replacements and improvements made within the spirit and principle of the present invention shall be included within the protection scope of the claims of the present invention.

Claims (10)

1. The high-rate and low-self-discharge zinc-organic battery is characterized in that a positive electrode material of the zinc-organic battery is an r-PTCDA material, a negative electrode material of the zinc-organic battery is zinc, and an electrolyte is an inorganic zinc ion aqueous solution.

2. The high-rate, low-self-discharge zinc-organic cell of claim 1, wherein said zinc-organic cell positive electrode is fabricated by an electrode film-forming technique, comprising the steps of: the preparation method comprises the steps of uniformly mixing an r-PTCDA material, acetylene black and PVDF to obtain mixed powder slurry, coating a film on a substrate by taking NMP as a dispersing agent, and drying for 5-48 hours under a vacuum heating condition.

Wherein the content of acetylene black in every 100mg of mixed powder slurry is 5-15 mg, the content of PVDF is 5-15 mg, 0.1-1 mL of NMP is dripped into every 100mg of mixed powder, and every 1cm of NMP²The substrate is coated with 0.1-15 mg of the mixed powder.

3. The high-rate, low-self-discharge zinc-organic battery according to claim 2, wherein the content of acetylene black is 5-15 mg and the content of PVDF is 5mg per 100mg of the mixed powder slurry.

4. The high-rate, low-self-discharge zinc-organic cell of claim 2, wherein said r-PTCDA material has a particle size of 0.002 to 50 μm.

5. The high-rate, low-self-discharge zinc-organic battery according to claim 4, wherein the r-PTCDA material is obtained by heating 3,4,9, 10-perylenetetracarboxylic dianhydride organic molecular crystals in an inert gas atmosphere, cooling, desublimation and recrystallization.

Wherein the heating temperature is 400-600 ℃, the heat preservation time is 0.1-5 hours, the cooling temperature is 0-300 ℃, and the heat preservation time is 0.1-5 hours.

6. The high-rate, low-self-discharge zinc-organic battery according to claim 5, wherein the heating temperature is 400 to 500 ℃ and the holding time is 0.1 to 2 hours.

7. The high-rate, low-self-discharge zinc-organic battery according to claim 5, wherein said cooling temperature is 100 to 200 ℃ and the holding time is 0.1 to 2 hours.

8. The high-rate, low-self-discharge zinc-organic battery according to claim 1, wherein the electrolyte has a molar concentration of 0.5 to 3mol/L and a pH of 5.5 to 1.

9. The high-rate, low self-discharge zinc-organic cell of claim 8, wherein said electrolyte is zinc chloride or zinc sulfate or zinc triflate.

10. Use of a high-rate, low-self-discharge zinc-organic cell according to any one of claims 1 to 9 in the field of electrochemical energy storage.

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