An electrode suitable for a zinc-bromine flow battery and a method of making the same

Abstract

The application discloses an electrode suitable for a zinc-bromine flow battery and a preparation method thereof. The electrode has periodically arranged holes, the holes are circular or square, the size of the holes is 0.4-0.6 mm, and the interval between the holes is 0.4-0.6 mm; the electrode is prepared by using a mixture of titanium alloy matrix powder and nano-conductive particles as material, wherein the particle size of the titanium alloy matrix powder is 15-53 mu m, the titanium alloy matrix powder is selected from one of TA1, TA2 and TC4, the particle size of the nano-conductive particles is 100-200 nm, the nano-conductive particles are selected from one or more of TiN, silver and graphene, and the mass ratio of the nano-conductive particles to the titanium alloy matrix powder is 0.5%-2.0%. The electrode with periodically arranged three-dimensional holes is prepared based on the SLM printing process, has a very high specific surface area, can keep a low current density in the charging process of the zinc-bromine flow battery, and promotes the zinc to be deposited on the electrode surface in a three-dimensional instantaneous nucleation mode.

Description

Technical fields:

[0001] This invention relates to the field of zinc-bromine flow battery technology, and more specifically to an electrode suitable for zinc-bromine flow batteries and its preparation method. Background technology:

[0002] Zinc-bromine flow batteries, as a typical representative of flow batteries, have broad application prospects in distributed energy storage due to their high energy density and low electrolyte cost. However, the large-scale promotion and application of zinc-bromine batteries still faces some challenges, such as the excessive growth of zinc dendrites during the zinc deposition process at the negative electrode, leading to short-circuit failure due to membrane penetration; and low voltage efficiency and easy leakage of bromine on the positive electrode side. These problems are mainly addressed through the optimized design and modification of electrode materials and electrolytes to improve the lifespan, efficiency, and safety of zinc-bromine flow batteries. Existing research shows that the growth rate of zinc dendrites is mainly related to the electrolyte flow rate, current density, and electrode material characteristics.

[0003] Chinese patent application CN 118039991 A discloses a zinc-bromine flow battery electrolyte for suppressing zinc dendrites and its preparation method. This patent adds conductive powders such as graphite powder, carbon black powder, zinc powder, and copper powder to the negative electrode electrolyte. When the powder contacts the electrode, zinc preferentially deposits on the powder. The powder carries away the elemental zinc with the fluid circulation, thereby preventing or reducing zinc deposition on the negative electrode. Patent ZL 201811423933.6 discloses a zinc-based battery negative electrode and its preparation and application. It uses magnetron sputtering to deposit one or more of metals, metal alloys, and metal oxides onto an electrode substrate under a specific atmosphere. This effectively prevents severe changes in the shape of the zinc electrode, suppresses dendrite growth, and results in a denser and more uniform deposition of metallic zinc, thereby improving the coulombic efficiency and cycle life of aqueous and organic zinc-based batteries. Publication No. CN116344856A discloses a bipolar plate for zinc-based flow batteries and its preparation method. By adding ferroelectric nanoparticles to the bipolar plate composition and controlling the ratio, a high-voltage corona discharge is applied to induce uniform and switchable polarization within the ferroelectric phase of the bipolar plate, guiding ordered zinc ion migration and solving the problem of zinc dendrite formation during electrodeposition in zinc-based flow batteries. Patent Publication No. CN118588954A discloses a method for preparing a modified electrode for zinc-bromine flow batteries. This patent rapidly and uniformly drip-coates or sprays carbon black onto the electrode surface, allowing zinc to be uniformly deposited on the electrode surface and effectively preventing zinc dendrites from piercing the battery separator. This method is inexpensive and can improve the energy efficiency of battery operation.

[0004] A comprehensive analysis of publicly available information on techniques for suppressing excessive zinc dendrite growth in zinc-bromine flow batteries primarily focuses on modifying the electrolyte, bipolar plates, and electrodes. Electrode modification mainly involves altering the surface of traditional carbon felt electrodes to promote uniform zinc deposition and control the growth direction of zinc dendrites. However, these modified electrode substrates still utilize conventional negative electrode materials and structures, limiting their ability to control dendrite growth. Furthermore, the disordered deposition of zinc dendrites on the cathode surface during charging results in weak bonding with the cathode, making them prone to detachment and energy loss, further negatively impacting the performance of the zinc-bromine flow battery. Among the many factors influencing zinc deposition, studies have shown that electrochemical polarization during electrode charging has the greatest impact on zinc deposition morphology. According to the Bolter-Volmer equation for overpotential and electrode current density, there is a positive linear relationship between overpotential and current density; the higher the current density, the greater the overpotential. Within a lower overpotential range, zinc electrocrystallization exhibits three-dimensional transient nucleation behavior. As the overvoltage continues to increase, the electrocrystallization behavior of zinc transforms into a continuous nucleation model. Therefore, this invention aims to address the problem of excessive zinc dendrite growth in zinc-bromine flow batteries by altering the electrochemical polarization behavior during electrode charging. Summary of the Invention:

[0005] This invention primarily addresses the problems of existing technologies by designing electrode materials and structures to reduce the electrochemical polarization of the electrode during charging, thereby achieving controllable growth regulation of zinc deposition. This invention provides an electrode suitable for zinc-bromine flow batteries and its preparation method. The proposed electrode is prepared using selective laser melting (SLM) and features periodically arranged channels. Furthermore, by optimizing the addition of nano-conductive particles to the electrode printing material, dispersed conductive sites are formed on the surface of the periodically arranged channels after SLM preparation. This ensures the electrode possesses excellent strength, conductivity, and corrosion resistance while also exhibiting excellent ability to inhibit zinc dendrite growth.

[0006] The first objective of this invention is to provide an electrode suitable for zinc-bromine flow batteries. The electrode has periodically arranged channels, which are circular or square in shape, with a channel size of 0.4-0.6 mm and a channel spacing of 0.4-0.6 mm. The electrode is prepared using a mixture of titanium alloy matrix powder and conductive nanoparticles as the material. The titanium alloy matrix powder has a particle size of 15-53 μm and is selected from one of TA1, TA2, and TC4. The conductive nanoparticles have a particle size of 100-200 nm and are selected from one or more of TiN, silver, and graphene. The mass ratio of the conductive nanoparticles to the titanium alloy matrix powder is 0.5%-2.0%.

[0007] The electrode substrate material selected in this invention is titanium alloy, which easily forms a dense and strongly adherent oxide film on its surface. This film can effectively resist corrosion from acidic, alkaline, neutral, and oxidizing media. It can keep the electrode substrate from being corroded in the electrolyte of zinc-bromine batteries. Even if corrosion or mechanical damage occurs on the surface, a dense and stable protective film can be quickly formed on the surface, thereby protecting the electrode substrate from damage.

[0008] Nano-TiN, a conductive material with metallic properties, is dispersed on the surface of titanium electrodes, increasing the active sites of the electrode. Silver can form a conductive network on the surface of titanium electrodes, improving their conductivity; graphene nanosheets, with their unique two-dimensional structure, can also form a conductive network on the surface of titanium electrodes.

[0009] Preferably, the size of the channel is 0.5 mm, and the spacing between the channels is 0.5 mm.

[0010] Preferably, the nano-conductive particles are a mixture of TiN and silver, wherein the mass ratio of nano-TiN to silver in the mixture is 0.8-1.2:1.

[0011] Preferably, the nano-conductive particles are a mixture of TiN and graphene, with a mass ratio of nano-TiN to graphene of 0.8-1.2:1.

[0012] Further optimization is achieved by having a mass ratio of nano-TiN to silver of 1:1 and a mass ratio of nano-TiN to graphene of 1:1.

[0013] A second objective of this invention is to provide a method for preparing the electrode suitable for a zinc-bromine flow battery, using a laser selective melting process, comprising the following steps:

[0014] (1) According to the different electrode conductivity, different nano-conductive particles are added to the titanium alloy matrix powder to prepare composite powder for laser selective melting process;

[0015] (2) The composite powder obtained in step (1) is added to an SLM printing device to print the electrode. The printing process parameters are: laser power: 200-300W; scanning speed: 200-300mm / s; scanning spacing: 40-50μm; layer thickness: 20-30μm.

[0016] For different titanium alloy composite powders, SLM printing process parameters are selected. The size of the electrode is designed according to the single cell plate size of the required zinc-bromine flow battery, and the proportion is 10% of the single cell plate size. The structure of the prepared electrode is a periodically arranged channel with a circular or square shape.

[0017] Preferably, step (1) specifically involves adding nano-conductive particles and titanium alloy powder into a powder mixer and mixing them at a speed of 50-60 rpm for 1-2 hours to obtain an electrode matrix composite powder with nano-conductive particles dispersed on the surface of the titanium alloy powder.

[0018] Preferably, the printing process parameters in step (2) are: laser power: 260-300W; scanning speed: 200-300mm / s; scanning spacing: 40-50μm; layer thickness: 20-30μm.

[0019] The present invention also protects a zinc-bromine flow battery, using the electrode described above suitable for a zinc-bromine flow battery as the negative electrode.

[0020] Compared with the prior art, the present invention has the following advantages:

[0021] 1) This invention utilizes SLM printing technology to fabricate electrodes with periodically arranged three-dimensional channels, resulting in an extremely high specific surface area. This allows for maintaining a low current density during the charging process of the zinc-bromine flow battery, promoting zinc deposition on the electrode surface via a three-dimensional instantaneous nucleation process. 2) The addition of nano-conductive particles to the electrode material forms an active center on the electrode surface, with a silver or graphene conductive network and nano-TiN serving as conductive nucleation sites. This allows metallic zinc to preferentially nucleate and grow at the conductive sites within the porous titanium metal framework, gradually forming a dense and uniform zinc deposition layer, effectively suppressing the growth of zinc dendrites. 3) Based on the porous framework structure of the electrode, the dense zinc deposition layer formed during charging remains stable within the titanium framework during discharging, reducing dead zinc detachment from the electrode, achieving full discharge, and improving the battery's energy density. Detailed implementation method:

[0022] The following embodiments are further illustrations of the present invention, but not limitations thereof.

[0023] Unless otherwise defined, all technical terms used herein have the same meaning as commonly understood by those skilled in the art. The technical terms used herein are for the purpose of describing particular embodiments only and are not intended to limit the scope of the invention. Unless otherwise specified, the experimental materials and reagents used herein are commercially available products conventionally available in this technical field.

[0024] Example 1

[0025] An electrode suitable for zinc-bromine flow batteries was fabricated using SLM (Surface Mount Technology) printing. The titanium alloy powder used in the SLM was TA1 with a particle size of 15–53 μm. The conductive nanoparticles were a mixture of TiN and silver, with a particle size ranging from 100–200 nm. The mass percentage of TiN to silver was 1:1, and the mass ratio of the conductive nanoparticles to the titanium alloy matrix powder was 0.5%. The resulting titanium electrode had dimensions of 10 × 10 × 2 mm and a frame structure with periodically arranged 0.5 mm diameter circular pores. The specific steps of its fabrication method are as follows:

[0026] (1) First, the above-mentioned nano-conductive particles and titanium alloy powder are added to a V-type powder mixer and mixed at a speed of 50-60 rpm for 1-2 hours to obtain an electrode matrix composite powder with nano-conductive particles dispersed on the surface of titanium powder.

[0027] (2) The composite powder obtained in step (1) is added to the SLM printing equipment. The main parameters of the printing process are: laser power: 300W; scanning speed: 200mm / s; scanning spacing: 40μm; layer thickness: 20μm. The structure of the electrode after printing is a three-dimensional channel with a periodic arrangement of 0.5mm aperture and an adjacent channel spacing of 0.5mm.

[0028] Example 2

[0029] An electrode suitable for zinc-bromine flow batteries was fabricated using SLM (Surface Mount Technology) printing. The titanium alloy powder used in the SLM was TA2 with a particle size of 15–53 μm. The conductive nanoparticles were a mixture of TiN and graphene nanosheets, with a particle size ranging from 100–200 nm. The mass percentage of TiN to graphene was 1:1, and the mass ratio of the conductive nanoparticles to the titanium alloy matrix powder was 1.0%. The resulting titanium electrode had dimensions of 10 × 10 × 2 mm and a frame structure with periodically arranged 0.5 mm pores. The specific steps of its fabrication are as follows:

[0030] (1) First, the above-mentioned nano-conductive particles and titanium alloy powder are added to a V-type powder mixer and mixed at a speed of 50-60 rpm for 1-2 hours to obtain an electrode matrix composite powder with nano-conductive particles dispersed on the surface of titanium powder.

[0031] (2) The composite powder obtained in step (1) is added to the SLM printing equipment. The main parameters of the printing process are: laser power: 300W; scanning speed: 300mm / s; scanning spacing: 50μm; layer thickness: 30μm. The structure of the electrode after printing is a three-dimensional channel with a periodic arrangement of 0.5mm aperture and an adjacent channel spacing of 0.5mm.

[0032] Example 3

[0033] An electrode suitable for zinc-bromine flow batteries was fabricated using SLM (Surface Mount Technology) printing. The titanium alloy powder used in the SLM was TC4 with a particle size of 15–53 μm. The conductive nanoparticles were a mixture of TiN and graphene nanosheets, with a particle size ranging from 100–200 nm. The mass percentage of TiN to graphene was 1:1, and the mass ratio of the conductive nanoparticles to the titanium alloy matrix powder was 2.0%. The resulting titanium electrode had dimensions of 10 × 10 × 2 mm and a frame structure consisting of periodically arranged square holes with a side length of 0.5 mm. The specific steps of its fabrication are as follows:

[0034] (1) First, add the above-mentioned nano-conductive particles and titanium alloy powder into a V-type powder mixer and mix at a speed of 50-60 rpm for 1-2 hours to obtain an electrode matrix powder with nano-conductive particles dispersed on the surface of the titanium powder.

[0035] (2) The composite powder obtained in step (1) is added to the SLM printing equipment. The main parameters of the printing process are: laser power: 260W; scanning speed: 300mm / s; scanning spacing: 45μm; layer thickness: 25μm. The structure of the electrode after printing is a three-dimensional square channel with a side length of 0.5mm arranged periodically, and the interval between adjacent channels is 0.5mm.

[0036] Comparative Example 1

[0037] The TA1 titanium electrode was prepared by machining without the addition of nano-conductive particles.

[0038] Using the electrodes prepared in Examples 1-3 or Comparative Example 1 as negative electrodes, a zinc-bromine flow battery was assembled, with carbon felt as the positive electrode, polyethersulfone as the porous membrane, and a titanium plate as the current collector. The electrolyte consisted of 3 mol / L ZnBr2 as the active material and 2 mol / L KBr as the supporting electrolyte. The positive and negative electrodes of the battery were connected to a testing system at 40 mA / cm². 2 Constant current charging and discharging were performed at the current density, charging to 60% SOC and then discharging to 0.5V. The performance test results of the flow battery with the above electrode structure were compared with those of a zinc-bromine flow battery using the same electrolyte and carbon felt as the positive and negative electrodes. The results are shown in Table 1 below.

[0039] Table 1

[0040]

[0041] The above description of the embodiments is only for the purpose of helping to understand the technical solution and core idea of ​​the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made to the present invention without departing from the principle of the present invention, and these improvements and modifications also fall within the protection scope of the claims of the present invention.

Claims

1. An electrode suitable for use in a zinc-bromine flow battery, characterized in that, The electrode has periodically arranged holes, the holes are circular or square, the size of the holes is 0.4-0.6 mm, and the interval between each hole is 0.4-0.6 mm; the electrode is prepared by using a mixture of titanium alloy matrix powder and nano-conductive particles as the material by laser selective melting process, wherein the particle size of the titanium alloy matrix powder is 15-53 μm, the titanium alloy matrix powder is selected from one of TA1, TA2 and TC4, the particle size of the nano-conductive particles is 100-200 nm, the nano-conductive particles are selected from one or more of TiN and silver, graphene, and the mass ratio of the nano-conductive particles to the titanium alloy matrix powder is 0.5%-2.0%.

2. The electrode suitable for use in a zinc-bromine flow battery according to claim 1, wherein, The size of the holes is 0.5 mm, and the interval between each hole is 0.5 mm.

3. The electrode suitable for use in a zinc-bromine flow battery of claim 1, wherein, The nano-conductive particles are a mixture of TiN and silver, and the mass ratio of nano-TiN to silver in the mixture is 0.8-1.2:

1.

4. The electrode suitable for use in a zinc-bromine flow battery according to claim 3, wherein, The mass ratio of nano-TiN to silver is 1:

1.

5. The electrode suitable for use in a zinc-bromine flow battery of claim 1, wherein, The nano-conductive particles are a mixture of TiN and graphene, and the mass ratio of nano-TiN to graphene is 0.8-1.2:

1.

6. The electrode suitable for use in a zinc-bromine flow battery according to claim 5, wherein, The mass ratio of nano-TiN to graphene is 1:

1.

7. The method for the production of an electrode suitable for use in a zinc-bromine flow battery according to any one of claims 1 to 6, characterized in that, Prepared by laser selective melting process, comprising the following steps: (1) according to the different conductivity of the electrode, select to add different nano-conductive particles to the titanium alloy matrix powder, prepare the composite powder for laser selective melting process; (2) add the composite powder obtained in step (1) to the SLM printing equipment for printing to obtain the electrode, and the printing process parameters are laser power: 200-300 W; scanning speed: 200-300 mm / s; scanning interval: 40-50 μm; layer thickness 20-30 μm.

8. The production method according to claim 7, characterized by, The specific steps of step (1) are: add nano-conductive particles and titanium alloy powder to a powder mixer, mix at a speed of 50-60 revolutions per minute for 1-2 hours to obtain an electrode matrix composite powder with nano-conductive particles dispersed on the surface of the titanium alloy powder.

9. The preparation method according to claim 7, characterized in that, The printing process parameters in step (2) are laser power: 260-300 W; scanning speed: 200-300 mm / s; scanning interval: 40-50 μm; layer thickness 20-30 μm.

10. A zinc-bromine flow battery characterized by, The electrode suitable for zinc-bromine flow battery as a negative electrode according to any one of claims 1-6.

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