Water-based zinc battery modified diaphragm capable of inhibiting dendritic crystal growth and preparation method of water-based zinc battery modified diaphragm

Abstract

The invention discloses an aqueous zinc battery modified diaphragm capable of inhibiting dendritic crystal growth and a preparation method thereof, and belongs to the field of aqueous zinc batteries. Sodium polyphosphate SPPP is taken to be prepared into a solution, and ultrasonic treatment is performed until the sodium polyphosphate SPPP is completely dissolved; dripping the SPPP solution on the surface of the commercial glass fiber until the SPPP solution is completely infiltrated, and naturally airing; zinc chloride ZnCl2 is taken and added into deionized water to prepare electrolyte, hydrochloric acid is added for assisting dissolution, and then a magnetic stirrer is used for stirring until the zinc chloride ZnCl2 is completely dissolved; a zinc chloride solution is taken to be completely infiltrated on the glass fiber diaphragm with the SPPP, gel is formed on the surface after standing at room temperature, and the gel is attached to the surface of the diaphragm or is filled in the pores of the diaphragm, so that the flexibility and tensile strength of the diaphragm are enhanced, the diaphragm can better bear the expansion and contraction of an electrode in the charging and discharging process of the battery, the rupture and perforation of the diaphragm are reduced, and the contact of a positive electrode and a negative electrode is prevented; pores among the glass fiber diaphragms are filled with the gel, so that the toughness of the diaphragms is improved; and the point effect caused by uneven electric field distribution is reduced, so that dendritic crystal growth is inhibited.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of aqueous zinc batteries, and particularly relates to a modified separator for inhibiting dendrite growth of an aqueous zinc battery and a preparation method thereof. BACKGROUND

[0002] With the increasingly serious global climate change problem, reducing dependence on fossil fuels and promoting large-scale application of renewable energy (such as solar energy and wind energy) have become a global consensus. However, renewable energy such as solar energy, wind energy and tidal energy has intermittency and instability, and requires an efficient energy storage system to achieve smooth output of electricity and balance between supply and demand. Aqueous zinc batteries stand out due to their unique advantages. Zinc has a huge global reserve and is low in price, and is suitable for large-scale application. An aqueous zinc battery uses a water-based electrolyte, which not only has lower cost, but also completely solves the safety hazard of flammable and explosive organic electrolyte, and significantly improves the safety of the battery. From the performance point of view, zinc has a high theoretical specific capacity (820 mAh / g) and a moderate voltage window, so that the aqueous zinc battery has potential advantages in energy density. However, the aqueous zinc battery still faces many challenges in practical application, such as the zinc negative electrode being prone to form dendrites during charging and discharging, which may cause short circuit of the battery and even trigger safety hazards; the zinc negative electrode is prone to hydrogen evolution and corrosion and other side reactions in the aqueous electrolyte, which reduces the efficiency and service life of the battery, etc.

[0003] The commonly used separator for the aqueous zinc battery is a glass fiber separator, but the size and pore size distribution of the fibers inside the separator are uneven, which easily leads to uneven distribution of the electric field and electrolyte ions, and under the influence of the "tip effect", dendrites are easily produced to pierce the separator, leading to short circuit of the battery, and the hydrogen evolution reaction (HER) caused by water electrolysis accompanied by the generation of by-products such as basic zinc salt, which further consumes the electrolyte, resulting in low coulombic efficiency and short service life of the aqueous zinc battery, which seriously hinders the practical application of zinc batteries. Based on the current problems of zinc metal negative electrode, it is particularly important to modify the battery separator to inhibit the growth of dendrites on the surface of the zinc negative electrode and the occurrence of side reactions, and thus to protect the zinc metal negative electrode, improve the coulombic efficiency and cycle life of the battery. SUMMARY

[0004] Technical problems solved:

[0005] The application provides a modified separator for a zinc battery of a water system for inhibiting dendrite growth and a preparation method of the modified separator.

[0006] Technical scheme:

[0007] To achieve the above-mentioned purpose, the application is implemented by the following technical scheme:

[0008] A preparation method of a modified separator for a zinc battery of a water system for inhibiting dendrite growth, steps are as follows:

[0009] Step 1: sodium polyphosphate (SPPP) is taken and added into deionized water to prepare an SPPP aqueous solution with a concentration ranging from 0.05 g / mL to 1 g / mL, and the SPPP is ultrasonically dissolved completely;

[0010] Step 2: 2-5 drops of the ultrasonically treated SPPP solution are dropped on the surface of glass fiber until the glass fiber is completely infiltrated, and the glass fiber separator with SPPP is obtained by being naturally dried at room temperature;

[0011] Step 3: ZnCl2 is taken and added into deionized water to prepare a ZnCl2 electrolyte with a concentration of 10 mol / L to 30 mol / L, 150-250 microliters of hydrochloric acid is added to assist dissolution, and then a magnetic stirrer is used to stir until the ZnCl2 is completely dissolved to obtain a ZnCl2 solution;

[0012] Step 4: 2-5 drops of the ZnCl2 solution are taken and dropped on the glass fiber separator with SPPP until the glass fiber separator is completely infiltrated, the glass fiber surface is formed with a gel by being placed at room temperature for 10-60 minutes, and the modified separator for the zinc battery of the water system for inhibiting dendrite growth is obtained.

[0013] Further, the power during the first step is 100W-150W, the temperature is controlled at 25℃-40℃, and the ultrasonic time is 7-12 minutes.

[0014] Further, the room temperature environment for natural drying in the second step is 15℃-30℃, and the time is 36-48 hours.

[0015] Further, the concentration of hydrochloric acid in the third step is 36%-38%.

[0016] Further, the stirring speed of the magnetic stirrer in the third step is 150r / min-180r / min, and the stirring time is controlled at 3-5 hours. Further, the room temperature environment for standing in the fourth step is 15℃-30℃.

[0017] A modified separator for aqueous zinc batteries that inhibits dendrite growth, prepared by any of the above preparation methods.

[0018] Original explanation: In this application, SPPP is used to dissociate polyphosphate ions in water, and ZnCl2 completely ionizes zinc ions; zinc ions can crosslink with polyphosphate ions through electrostatic attraction and chemical bond action, connecting polyphosphate ions to form a three-dimensional network structure; as the reaction proceeds, more and more ions participate in crosslinking, and when the crosslinking degree reaches a certain degree, a gel is formed; the gel adheres to the surface of the separator or fills the pores of the separator, which can enhance the flexibility and tensile strength of the separator, making it more able to withstand the expansion and contraction of the electrode during the charging and discharging process of the battery, reducing the risk of separator rupture and perforation, and preventing direct contact between the positive and negative electrodes to cause short circuit.

[0019] Beneficial effects:

[0020] The present application provides a modified separator for aqueous zinc batteries that inhibits dendrite growth and its preparation method, which has the following beneficial effects compared with the prior art:

[0021] 1. The present application forms a gel by the reaction of SPPP and ZnCl2 electrolyte, which adheres to the surface of the separator or fills the pores of the separator, increasing the toughness of the separator, and the puncture strength is increased to 1.2MPa;

[0022] 2. The gel on the modified separator for zinc batteries that inhibits dendrite growth provided by the present application can reduce the sharp tip effect caused by uneven electric field distribution, thereby inhibiting dendrite growth, especially under the conditions of a large current density of 50mAcm -2 and a dissolution time of 1h, it can also be stably cycled for more than 2000 hours;

[0023] 3. The zinc battery modified separator for inhibiting dendrite growth provided by the present application can inhibit the hydrogen evolution reaction at the electrode interface, thereby reducing the occurrence of harmful side reactions, and can also better protect the separator.

[0024] 4. The zinc battery modified separator for inhibiting dendrite growth provided by the present application can prolong the service life of the separator under large current and capacity density, thereby prolonging the service life of the battery, and is conducive to wide application. BRIEF DESCRIPTION OF DRAWINGS

[0025] Figure 1 Scanning electron microscope images of a commercial glass fiber separator and the modified separator prepared in Example 1 of the present application, wherein the left image is a scanning electron microscope image of the commercial glass fiber separator, and the right image is a scanning electron microscope image of the modified separator;

[0026] Figure 2 Puncture resistance images of the zinc battery modified separator for inhibiting dendrite growth prepared in Example 1 of the present application and a commercial glass fiber separator;

[0027] Figure 3 Constant current charge-discharge long cycle comparison images of symmetric batteries assembled by the zinc battery modified separator for inhibiting dendrite growth prepared in Example 1 of the present application and a commercial glass fiber separator under a current density of 50 mA cm -2 , an area capacity of 50 mAh cm -2 ;

[0028] Figure 4 EDS energy spectrum analysis images of the zinc negative electrode after 50 cycles of the symmetric battery assembled by a commercial glass fiber separator under a current density of 1 mA cm -2 , an area capacity of 1 mAh cm -2 ;

[0029] Figure 5 EDS energy spectrum analysis images of the zinc negative electrode after 50 cycles of the symmetric battery assembled by the zinc battery modified separator for inhibiting dendrite growth prepared in Example 1 of the present application under a current density of 1 mA cm -2 , an area capacity of 1 mAh cm -2 . DETAILED DESCRIPTION

[0030] The present application will be described in detail below with reference to specific embodiments. The following examples will help those skilled in the art to further understand the present application, but do not limit the present application in any form. It should be noted that, for those skilled in the art, without departing from the concept of the present application, a number of modifications and improvements can be made. These all belong to the protection scope of the present application.

[0031] Example 1

[0032] The embodiment provides a preparation method of a dendrite growth inhibited aqueous zinc battery modified diaphragm, and the preparation method is as follows:

[0033] First step: take sodium polyphosphate SPPP and add it into deionized water to prepare a SPPP aqueous solution with a concentration range of 0.2 g / mL, and ultrasonic treatment until complete dissolution; the power during ultrasonic treatment is 100 W-150 W, the temperature is controlled at 25 DEG C, and the ultrasonic treatment time is 10 minutes;

[0034] Second step: take 3 drops of the SPPP solution after ultrasonic treatment, drop them on the surface of the glass fiber until complete wetting, and place the glass fiber in a room temperature environment for natural air drying to obtain a glass fiber diaphragm with SPPP; the room temperature environment for natural air drying is 25 DEG C, and the time length is 40 hours;

[0035] Third step: take 34.075 g of ZnCl2, add it into 10 mL of deionized water to prepare a ZnCl2 electrolyte, add 200 μL of hydrochloric acid to assist dissolution, then use a magnetic stirrer to stir until complete dissolution to obtain a ZnCl2 solution, and the concentration of the hydrochloric acid is 37%; the stirring speed of the magnetic stirrer is 150 r / min-180 r / min, and the stirring time length is controlled at 4 hours;

[0036] Fourth step: take 3 drops of the ZnCl2 solution on the glass fiber diaphragm with 0.2 g / mL SPPP until complete wetting, place the glass fiber diaphragm in a room temperature environment for 30 minutes to form a gel on the surface of the glass fiber, the room temperature environment is 25 DEG C, and an aqueous zinc battery modified diaphragm for inhibiting dendrite growth is obtained.

[0037] Assemble a symmetrical battery:

[0038] Battery assembly method: prepare a pure zinc foil, two titanium meshes and a glass fiber diaphragm. First, stack the two titanium meshes in the battery shell. Then, place the pure zinc foil on the titanium mesh, and ensure that the titanium mesh is regular. Then, use tweezers to clamp the glass fiber diaphragm with 0.2 g / mL SPPP on the pure zinc foil, and drop the ZnCl2 solution to completely wet the diaphragm. Finally, place the zinc negative electrode in the middle of the diaphragm, cover the battery shell, and perform packaging operation through a battery packaging machine to assemble a CR2016 button cell. Denoted as SPPP-GF-Zn / / Zn button cell.

[0039] Example 2

[0040] The embodiment provides a preparation method of a dendrite growth inhibited aqueous zinc battery modified diaphragm, and the preparation method is as follows:

[0041] First step: take sodium polyphosphate SPPP and add it into deionized water to prepare a SPPP aqueous solution with a concentration range of 0.05 g / mL, and ultrasonic treatment until complete dissolution; the power during ultrasonic treatment is 100 W, the temperature is controlled at 25 DEG C, and the ultrasonic treatment time is 7 minutes;

[0042] Second step: take 2 drops of ultrasonic SPPP solution on the surface of glass fiber to completely soak, and place it at room temperature to dry naturally to obtain glass fiber separator with SPPP; the natural drying room temperature environment is 15℃, and the time length is 36 hours;

[0043] Third step: take ZnCl2 and add it into deionized water to prepare 10mol / L ZnCl2 electrolyte, add 150μL of hydrochloric acid to assist dissolution, then use a magnetic stirrer to stir until completely dissolved to obtain ZnCl2 solution, the concentration of hydrochloric acid is 36%; the stirring speed of the magnetic stirrer is 150r / min, and the stirring time is controlled for 3 hours;

[0044] Fourth step: take 2 drops of ZnCl2 solution on the glass fiber separator with SPPP to completely soak, and place it at room temperature for 10 minutes to form a gel on the surface of the glass fiber, the standing room temperature environment is 15℃, to obtain a modified separator of aqueous zinc battery that inhibits dendrite growth.

[0045] Example 3

[0046] The embodiment provides a preparation method of a modified separator of aqueous zinc battery that inhibits dendrite growth, and the preparation method is as follows:

[0047] First step: take sodium polyphosphate SPPP and add it into deionized water to prepare SPPP aqueous solution with a concentration range of 1g / mL, and ultrasonic treatment until completely dissolved; the power during ultrasonic treatment is 150W, the temperature is controlled at 40℃, and the ultrasonic treatment time is 12 minutes;

[0048] Second step: take 5 drops of ultrasonic SPPP solution on the surface of glass fiber to completely soak, and place it at room temperature to dry naturally to obtain glass fiber separator with SPPP; the natural drying room temperature environment is 30℃, and the time length is 48 hours;

[0049] Third step: take ZnCl2 and add it into deionized water to prepare 30mol / L ZnCl2 electrolyte, add 250μL of hydrochloric acid to assist dissolution, then use a magnetic stirrer to stir until completely dissolved to obtain ZnCl2 solution, the concentration of hydrochloric acid is 38%; the stirring speed of the magnetic stirrer is 180r / min, and the stirring time is controlled for 5 hours;

[0050] Fourth step: take 5 drops of ZnCl2 solution on the glass fiber separator with SPPP to completely soak, and place it at room temperature for 60 minutes to form a gel on the surface of the glass fiber, the standing room temperature environment is 30℃, to obtain a modified separator of aqueous zinc battery that inhibits dendrite growth.

[0051] Comparative Example 1

[0052] A preparation method of a zinc battery separator, and the preparation method is as follows:

[0053] First step: take 34.075 g of ZnCl2 and add it to 10 mL of deionized water to prepare a ZnCl2 electrolyte;

[0054] Second step: add 200 μL of 37% hydrochloric acid to assist dissolution, and then stir with a magnetic stirrer for 4 hours until complete dissolution.

[0055] Water-based zinc battery (pure zinc) CR2016 button cell, the battery assembly method is the same as example 1, and the glass fiber separator used is a commercial glass fiber separator. Denoted as GF-Zn / / Zn button cell.

[0056] Application Example 1

[0057] The micro-morphology characteristics of the dendrite growth inhibiting zinc battery modified separator prepared in example 1 and the commercial glass fiber separator were analyzed by scanning electron microscope:

[0058] As shown in Figure 1 , Figure 1 The left image is a scanning electron microscope image of a commercial glass fiber separator, and the right image is a scanning electron microscope image of the dendrite growth inhibiting zinc battery modified separator prepared in example 1. The commercial glass fiber separator has irregular micron-sized pores, which has weak physical blocking ability for zinc dendrites, and is easy to cause short circuit in the cycle due to dendrite penetration, significantly shortening the battery life. The gel can fill the pores between the glass fiber separators, increasing the toughness of the separator.

[0059] The puncture resistance of the dendrite growth inhibiting zinc battery modified separator prepared in example 1 and the commercial glass fiber separator is shown in Figure 2 As shown in

[0060] The symmetric battery assembled with the dendrite growth inhibiting zinc battery modified separator prepared in example 1 and the commercial glass fiber separator was subjected to long cycle comparison under constant current charge and discharge at a current density of 50 mA / cm 2 and an area capacity of 50 mAh / cm 2 .

[0061] The battery using the dendrite growth inhibiting zinc battery modified separator prepared in example 1 exhibited excellent cycle life of more than 2000 hours under ultra-large current and capacity density (DOD, 89.9%) of 50 mA / cm 2 and 50 mA / h cm 2 , while the commercial glass fiber separator battery showed internal short circuit at the beginning of the test.

[0062] The symmetric battery assembled with the dendrite growth inhibiting zinc battery modified separator prepared in example 1 and the commercial glass fiber separator was subjected to long cycle comparison under constant current charge and discharge at a current density of 1 mA / cm2 ,1mAh / cm 2 Comparison of EDS spectrum analysis of zinc negative electrode after 50 cycles in ambient environment;

[0063] like Figure 4 and Figure 5 As shown in the figure, element signals of Cl and Si appeared on the surface of the zinc negative electrode using the commercial glass fiber separator, but no such result was found on the surface of the zinc negative electrode using the modified zinc battery separator for inhibiting dendrite growth prepared in Example 1. This shows that the modified zinc battery separator for inhibiting dendrite growth prepared in Example 1 has excellent performance in inhibiting side reactions. At the same time, the absence of Si element signals also shows that there is no residual separator on the surface of the zinc negative electrode after the cycle test, indicating that the separator was not damaged during multiple zinc ion electroplating / stripping processes.

[0064] The examples selected in the above materials are intended to facilitate understanding and are not intended to limit the process. Those skilled in the art may readily modify the process or transfer it to other cases without inventive change. If such modifications fall within the same scope of claims or similar technologies as the present invention, the invention is intended to encompass such modifications.

Claims

1. A method for preparing a modified aqueous zinc battery diaphragm for inhibiting dendrite growth, characterized in that: The steps are: Step 1: Sodium polyphosphate (SPPP) was added to deionized water to prepare an SPPP aqueous solution with a concentration range of 0.05 to 1 g / mL, and ultrasonicated until completely dissolved. Step 2: Take 2 to 5 drops of the ultrasonicated SPPP solution and drop it on the glass fiber surface until it is completely soaked, and then leave it to dry naturally at room temperature to obtain a glass fiber membrane with SPPP; Step 3: Add ZnCl2 to deionized water to prepare a 10-30 mol / L ZnCl2 electrolyte, add 150-250 μL of hydrochloric acid to dissolve it, and then stir with a magnetic stirrer until it is completely dissolved to obtain a ZnCl2 solution; Step 4: Take 2 to 5 drops of ZnCl2 solution and apply it to the glass fiber separator with SPPP until it is completely soaked. Let it stand at room temperature for 10 to 60 minutes to form a gel on the surface of the glass fiber, thereby obtaining a modified aqueous zinc battery separator that inhibits dendrite growth.

2. The method for preparing a modified aqueous zinc battery diaphragm for inhibiting dendrite growth according to claim 1, wherein: In the first step, the power of ultrasound is 100W to 150W, the temperature is controlled at 25° C. to 40° C., and the duration of ultrasound is 7 to 12 minutes.

3. The method for preparing a modified aqueous zinc battery diaphragm for inhibiting dendrite growth according to claim 2, wherein: The room temperature for natural drying in the second step is 15°C to 30°C, and the drying time is 36 to 48 hours.

4. The method for preparing a modified aqueous zinc battery diaphragm for inhibiting dendrite growth according to claim 1, wherein: The concentration of hydrochloric acid in the third step is 36% to 38%.

5. The method for preparing a modified aqueous zinc battery diaphragm for inhibiting dendrite growth according to claim 1, wherein: In the third step, the stirring speed of the magnetic stirrer is 150 r / min to 180 r / min, and the stirring time is controlled to be 3 to 5 hours.

6. The method for preparing a modified aqueous zinc battery diaphragm for inhibiting dendrite growth according to claim 1, wherein: The room temperature environment in the fourth step is 15° C. to 30° C.

7. A modified aqueous zinc battery diaphragm for inhibiting dendrite growth, obtained by the preparation method according to any one of claims 1 to 6.

Images