阅读说明：本技术 一种锌空气电池锌电极还原再生循环利用方法 (Reduction, regeneration and cyclic utilization method for zinc electrode of zinc-air battery ) 是由 刘伟春 于 2019-11-13 设计创作，主要内容包括：本发明提供一种锌空气电池锌电极还原再生循环利用方法,具体涉及电化学技术和电池制造技术领域,将锌与集流体分离；恒温下搅拌碱溶后进行通过滤分离机进行过滤分离后进行电解液净化；电解液循环罐内的电解液按流量3～5m<Sup>3</Sup>/h泵入电解槽内,电解槽的阴、阳极板选择析气量小的合金板,阴极选择钛合金板(或镁合金板)喷涂氧化物(或镁合金、铅合金)；阳极选择镍合金板；阴、阳极板四周采用耐腐蚀橡胶包边,包边宽度≤20mm,阴、阳极板面积0.8m<Sup>2</Sup>～1.0m<Sup>2</Sup>,阴、阳极板厚度2.0～3.5mm,电解槽底部倾斜20°～30°,阴极析出枝状或台藓状锌,通过电沉积自动脱落在电解槽低部,最后进入锌粉储存罐。本发明还原成本低且效率高。(The invention provides a method for reducing, regenerating and recycling a zinc electrode of a zinc-air battery, and particularly relates to the technical field of electrochemistry and battery manufacturing, wherein zinc is separated from a current collector; stirring at constant temperature to dissolve alkali, filtering and separating by a filter separator, and purifying the electrolyte; electrolyte in the electrolyte circulation tank is 3-5 m according to flow 3 Pumping into an electrolytic cell, selecting an alloy plate with small gas evolution quantity for a cathode plate and an anode plate of the electrolytic cell, and selecting a titanium alloy plate (or magnesium alloy) for the cathodePlate) spray coating oxide (or magnesium alloy, lead alloy); selecting a nickel alloy plate as an anode; the peripheries of the cathode plate and the anode plate are wrapped with corrosion-resistant rubber, the width of the wrapped edge is less than or equal to 20mm, and the area of the cathode plate and the anode plate is 0.8m 2 ～1.0m 2 The thickness of the cathode plate and the anode plate is 2.0-3.5 mm, the bottom of the electrolytic tank is inclined by 20-30 degrees, dendritic or dittany zinc is separated out from the cathode, automatically falls off at the lower part of the electrolytic tank through electrodeposition, and finally enters a zinc powder storage tank. The invention has low reduction cost and high efficiency.)

1. A zinc electrode reduction, regeneration and recycling method of a zinc-air battery is characterized by comprising the following specific steps:

s1, separating zinc from a current collector, crushing a zinc electrode, and then sending the crushed zinc electrode and KOH into a constant-temperature stirring alkali dissolving tank according to the mass ratio of 4: 1; wherein the zinc particles in the constant-temperature stirring alkali dissolving tank are less than or equal to 8cm³(ii) a The concentration of KOH alkali is 6 mol/L; the mass ratio of alkali dissolution is 4:1, the temperature is 30-50 ℃, the stirring speed is 50 r/min, and the dissolution time is 2-4 h;

s2, stirring at a constant temperature, carrying out alkali dissolution, filtering and separating by a filter separator, and purifying the electrolyte; wherein the flow rate of the filtering separator is controlled to be 5m³/～8m³The filtering separator separates solute from the solution when the electrolyte passes through; separating out unreacted zinc powder, detecting the separated electrolyte, controlling the zinc content to be within the range of 25 g/L-35 g/L, feeding the electrolyte into an electrolyte purification tank, purifying for 12 hours, fully dissolving in alkali, and feeding the electrolyte into an electrolyte circulation tank; separating out filter residues which are unreacted zinc, and directly recycling the zinc with the granularity of 20-40 meshes to prepare a zinc electrode; when Zn is contained in the electrolyte circulation tank^2-When the ion content is reduced to be less than or equal to 6-8 g/L and the current efficiency is less than or equal to 85%, stopping electrolyzing the electrolyte in the circulating tank; conveying the electrolyte in the electrolyte circulation tank to a constant-temperature alkali dissolution tank through a pump, and recovering the alkali dissolution state of the electrolyte; the electrolyte is circulated in a closed system through a centrifugal pump; the electrolyzed electrolyte enters an alkali dissolving tank for circulation, and the purity of KOH in the electrolyte is kept to be more than or equal to 95 percent

S3, 3-5 m of electrolyte in the electrolyte circulation tank according to flow³Pumping into an electrolytic cell, selecting an alloy plate with small gas evolution quantity for a cathode plate and an anode plate of the electrolytic cell, and spraying an oxide (or a magnesium alloy or a lead alloy) on a titanium alloy plate (or a magnesium alloy plate) for the cathode; selecting a nickel alloy plate as an anode; the peripheries of the cathode plate and the anode plate are wrapped with corrosion-resistant rubber, the width of the wrapped edge is less than or equal to 20mm, and the area of the cathode plate and the anode plate is 0.8m²～1.0m²The thickness of the cathode plate and the anode plate is 2.0-3.5 mm, the bottom of the electrolytic tank is inclined by 20-30 degrees, and the cathode is precipitated into a branch shape or a shape of a branchThe dittany zinc automatically falls off from the lower part of the electrolytic tank through electrodeposition and finally enters a zinc powder storage tank.

2. The zinc air battery zinc electrode reduction, regeneration and recycling method according to claim 1, characterized in that: the volume of the purification tank is more than or equal to 2 times of the volume of the electrolyte circulation tank; the volume of the electrolyte circulating tank is 2 times larger than the effective capacity of the electrolytic cell.

3. The zinc air battery zinc electrode reduction, regeneration and recycling method according to claim 1, characterized in that: in the electrodeposition process, the crystal nucleus growth speed is higher than the zinc crystal nucleus generation speed, and the electrolyte is controlled by a circulating time sequence and is circulated for 20 minutes at intervals of 50-60 minutes; the circulation flow of the electrolyte in each electrolytic cell is controlled to be 500-800L/h, the circulation time sequence of the electrolyte is controlled by a PLC (programmable logic controller), the zinc content of the electrolyte is monitored at any time, and the cell voltage in the electrolytic cell is 2.3-3.0V; the current density of the polar plate is 100-150 mA/cm²。

4. The zinc air battery zinc electrode reduction, regeneration and recycling method according to claim 1, characterized in that: oxygen is separated out from the electrolytic cell during operation, and the discharged oxygen is collected by a collector and purified to be used as a byproduct; the upper surface of the electrolyte in the electrolytic bath is covered by the composite chemical liquid.

5. The zinc air battery zinc electrode reduction, regeneration and recycling method according to claim 1, characterized in that: the distance between the cathode plate and the anode plate in the electrolytic cell is 60mm to 150mm, the anode plate is a nickel alloy plate or a 304 stainless steel plate, the aperture ratio on the plate is 6 to 10 percent, and the aperture is

6. The zinc air battery zinc electrode reduction, regeneration and recycling method according to claim 1, characterized in that: the temperature of electrolyte in the electrolytic cell is constant within the range of 30-50 ℃, the electrolyte circularly flows according to time sequence, the flow among the polar plates is balanced, and the deposited zinc powder of the negative plate is scraped once every 50-80 minutes; the process of electrodeposition zinc precipitation is ensured, the crystal nucleus growth speed is larger than the zinc crystal nucleus generation speed, and the zinc powder is dendritic or tableau-shaped.

7. The zinc air battery zinc electrode reduction, regeneration and recycling method according to claim 1, characterized in that: the cathode plate and the anode plate are connected with a high-power direct-current power supply by adopting a conductive copper bar with the thickness of 100 multiplied by 10mm, the pole plates are connected with a copper bar bus in a quick-release locking mode, the voltage drop of a contact point is less than 0.2mV (under the current of 200A), and the one-time connection point is cleaned after the continuous working for 300 hours.

8. The zinc air battery zinc electrode reduction, regeneration and recycling method according to claim 1, characterized in that: the electrolytic reduction of the metal zinc is realized by using a high-power direct-current power supply, and can be replaced by new solar energy, wind energy or tide energy.

Technical Field

The invention belongs to the technical field of electrochemistry and battery manufacturing, and particularly relates to a zinc electrode reduction, regeneration and recycling method of a zinc-air battery.

Background

The mechanical replacement type zinc-air battery adopts metal zinc as a negative electrode, and the discharge product of the zinc-air battery is the excessive product of zinc oxide (Zno) and zinc; the zinc-air battery can be changed from a primary battery to a secondary battery by reducing the excess products of ZnO and zinc into zinc, which is a key link for the commercialization of the mechanical replacement type zinc-air battery.

KOH is used for zinc-air battery electrolyte, Zn is changed into ZnO in the discharging process of the battery, and part of ZnO is dissolved in KOH solution to generate K₂Zn(OH)₄(ii) a A part of Zn (OH) is formed₄ ^2-. Under the condition of high power output of the zinc-air battery, the generation speed of ZnO is greater than the dissolution speed of ZnO, and a large amount of Zn (OH) exists in a zinc electrode₄ ^2-Ions, generating K under the action of KOH as electrolyte₂Zn(OH)₄A large amount of electrolyte KOH is needed for dissolution, but the amount of electrolyte in the zinc-air battery is limited, and the rest of most discharge products are Zn (OH)₄ ^2-The existence of an ionic state; the mechanical replacement type zinc-air battery is an alkaline battery, secondary reduction and regeneration of the zinc electrode are only carried out under an alkaline body, the reduction and regeneration process path of the zinc electrode is short, and the reduction and regeneration cost is low.

Disclosure of Invention

In view of the above, the invention provides a method for recycling zinc air battery zinc electrode by reduction and regeneration, which reduces zinc by an electrodeposition method from an alkali solution preparation to industrial production of zinc with large specific surface area, small particle size and high activity, and is used for mechanical replacement type zinc air battery zinc electrode reduction and regeneration. Through years of research and combination with a mature industrial method for zinc smelting, the requirements of manufacturing zinc electrodes of batch mechanical replacement type zinc-air batteries and secondary reduction and reutilization of the zinc electrodes are met. Effectively solves the problems of uneven flow velocity of electrolyte of each independent electrolytic cell, uneven current distribution on a cathode plate and an anode plate, large concentration polarization of the electrolyte on the surface of the plate, high cell voltage, high direct current energy consumption, low current efficiency, high electrolytic reduction cost and the like in an alkaline system

The invention provides the following technical scheme:

a zinc electrode reduction regeneration recycling method of a zinc-air battery comprises the following specific steps:

s1, separating zinc from a current collector, crushing a zinc electrode, and then sending the crushed zinc electrode and KOH into a constant-temperature stirring alkali dissolving tank according to the mass ratio of 4: 1; wherein the zinc particles in the constant-temperature stirring alkali dissolving tank are less than or equal to 8cm³(ii) a The concentration of KOH alkali is 6 mol/L; the mass ratio of alkali dissolution is 4:1, the temperature is 30-50 ℃, the stirring speed is 50 r/min, and the dissolution time is 2-4 h;

s2, stirring at a constant temperature, carrying out alkali dissolution, filtering and separating by a filter separator, and purifying the electrolyte; wherein the flow rate of the filtering separator is controlled to be 5m³/～8m³The filtering separator separates solute from the solution when the electrolyte passes through; separating out unreacted zinc powder, detecting the separated electrolyte, controlling the zinc content to be within the range of 25 g/L-35 g/L, feeding the electrolyte into an electrolyte purification tank, purifying for 12 hours, fully dissolving in alkali, and feeding the electrolyte into an electrolyte circulation tank; separating out filter residues which are unreacted zinc, and directly recycling the zinc with the granularity of 20-40 meshes to prepare a zinc electrode; when Zn is contained in the electrolyte circulation tank^2-When the ion content is reduced to be less than or equal to 6-8 g/L and the current efficiency is less than or equal to 85%, stopping electrolyzing the electrolyte in the circulating tank; conveying the electrolyte in the electrolyte circulation tank to a constant-temperature alkali dissolution tank through a pump, and recovering the electrolyte to be in an electrolyte state; the electrolyte is circulated in a closed system through a centrifugal pump; the electrolyzed electrolyte enters an alkali dissolving tank for circulation, the electrolyte is subjected to causticization treatment periodically, and the purity of KOH in the electrolyte is kept to be more than or equal to 95 percent

S3, 3-5 m of electrolyte in the electrolyte circulation tank according to flow³Pumping into an electrolytic cell, selecting an alloy plate with small gas evolution quantity for a cathode plate and an anode plate of the electrolytic cell, and spraying an oxide (or a magnesium alloy or a lead alloy) on a titanium alloy plate (or a magnesium alloy plate) for the cathode; selecting a nickel alloy plate as an anode; the peripheries of the cathode plate and the anode plate are wrapped with corrosion-resistant rubber, the width of the wrapped edge is less than or equal to 20mm, and the area of the cathode plate and the anode plate is 0.8m²～1.0m²The thickness of the cathode plate and the anode plate is 2.0-3.5 mm, the bottom of the electrolytic tank is inclined by 20-30 degrees, dendritic or dittany zinc is separated out from the cathode and automatically falls off at the lower part of the electrolytic tank through electrodeposition,finally, the zinc powder enters a zinc powder storage tank,

preferably, the volume of the purification tank is more than or equal to 2 times of the volume of the electrolyte circulation tank; the volume of the electrolyte circulating tank is 2 times larger than the effective capacity of the electrolytic cell.

Preferably, the crystal nucleus growth speed is larger than the zinc crystal nucleus generation speed in the electrodeposition process, and the electrolyte is controlled by a circulating time sequence and is circulated for 20 minutes at intervals of 50-60 minutes; the circulation flow of the electrolyte in each electrolytic cell is controlled to be 500-800L/h, the circulation time sequence of the electrolyte is controlled by a PLC (programmable logic controller), the zinc content of the electrolyte is monitored at any time, and the cell voltage in the electrolytic cell is 2.3-3.0V; the current density of the polar plate is 100-150 mA/cm²。

Preferably, the electrolytic cell is used for oxygen evolution during operation, and the discharged oxygen is collected by a collector and purified to be used as a byproduct; the electrolyte in the electrolytic cell is covered by the composite chemical liquid, so that the electrolyte is prevented from being polluted by harmful gas in the air.

Preferably, the distance between the cathode plate and the anode plate in the electrolytic cell is 60mm to 150mm, the anode plate is a nickel alloy plate or a 304 stainless steel plate, the aperture ratio of the plate is 6 to 10 percent, and the aperture isThe electrolyte is distributed in a radial rule to form a porous plate type anode, so that the surface area of the anode plate is increased, the electrolyte has good fluidity and high flow speed through the anode plate, and the voltage of the cell is reduced; an anode plate is connected in parallel with a left cathode plate and a right cathode plate in the electrolytic bath, and the electrolytic baths are connected in series; the voltage of the electrolytic bath is controlled between 2.3V and 3.0V; the current density of the polar plate is 100-150 mA/cm²(ii) a The growth speed of crystal nucleus is higher than the generation speed of zinc crystal nucleus in the process of zinc precipitation by electrodeposition, and the zinc powder is dendritic or tableau-shaped.

Preferably, the temperature of the electrolyte in the electrolytic cell is constant within the range of 30-50 ℃, the electrolyte circularly flows according to a time sequence, the flow among the polar plates is balanced, and the deposited zinc powder of the negative plate is scraped once every 50-80 minutes; ensuring the process of electrodeposition zinc precipitation, wherein the growth speed of crystal nucleus is larger than the generation speed of zinc crystal nucleus, and the zinc powder is dendritic or tableau-shaped; the liquid phase resistance of the electrolyte is reduced, and the growth speed of the zinc precipitation crystal nucleus is improved.

Preferably, the cathode plate and the anode plate are connected with a high-power direct-current power supply by adopting a conductive copper bar with the thickness of 100 multiplied by 10mm, the electrode plates are connected with a copper bar bus in a quick-release locking mode, the voltage drop of a contact point is less than 0.2mV (under the current of 200A), the one-time connection point is cleaned after the continuous working for 300 hours, the corrosion of the contact point is prevented, and the contact point contact resistance is reduced.

Preferably, the electrolytic reduction of the metal zinc is performed by using a high-power direct-current power supply, and other new energy sources such as solar energy, wind energy, tide and the like can be adopted for replacement.

The invention has the beneficial effects that:

(1) the invention reduces zinc by an electrodeposition method through alkali solution preparation, achieves the industrial production of zinc with large specific surface area, small granularity and high activity, and is used for reducing and regenerating the zinc electrode of the mechanical replacement type zinc-air battery. Through years of research and combination with a mature industrial method for zinc smelting, the requirements of manufacturing zinc electrodes of batch mechanical replacement type zinc-air batteries and secondary reduction and reutilization of the zinc electrodes are met. The problems that the flow velocity of electrolyte of each independent electrolytic cell is not uniform, the current distribution on a cathode plate and an anode plate is not uniform, the concentration polarization of the electrolyte on the surface of the plate is large, the cell voltage is high, the direct current energy consumption is high, the current efficiency is low, the electrolytic reduction cost is high and the like in an alkaline system are effectively solved.

(2) According to the invention, the alkali solution enters the electrolyte for circulation, so that the current efficiency is improved, the energy consumption is reduced, the secondary reduction regenerated zinc has the characteristics of good appearance uniformity, high activity and the like, the automatic or semi-automatic production of a zinc reduction system is realized, and the zinc reduction system is carried out under the totally closed condition to prevent zinc oxidation and electrolyte failure;

(3) the industrial method for recycling the zinc electrode of the zinc-air battery comprises the steps of stirring and dissolving a product of the discharged zinc-air battery at a set temperature, separating an alkali solution from unreacted metal zinc by a filter, and feeding a saturated alkali solution into an electrolytic bath for electrodeposition. Dynamically monitoring and adjusting the concentration of zinc ions in the alkali solution in the electrolytic bath, the circulation quantity of the alkali solution, the voltage of the electrolytic bath and the current density in real time; the high current efficiency is kept, the electric energy utilization rate is improved, and meanwhile, the cathode deposition dendritic zinc powder and the tableau-shaped zinc powder automatically fall off and enter a zinc powder storage tank along with the bed body. The system realizes automatic or semi-automatic production of the system from alkali solution preparation, filtration and separation, alkali solution purification, circulation in an electrolyte electrolytic cell and dynamic monitoring of electrolyte and electrolysis parameters.

Drawings

The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the description serve to explain the principles of the invention and not to limit the invention. In the attached drawings

FIG. 1 is a flow chart of a zinc electrode reduction, regeneration and cyclic utilization method of a zinc-air battery;

FIG. 2, example 3 first photograph of electro-deposited zinc by scanning electron microscopy;

FIG. 3, example 3 second photograph of electro-deposited zinc by scanning electron microscope;

Detailed Description