KR20220042918A - Electrolyte for zinc air battery - Google Patents

Abstract

An object of the present invention is to provide an electrolyte for a zinc air battery to which an additive for properly forming and growing dendrite is added. The present invention relates to an electrolyte for a zinc air battery. According to an embodiment of the present invention, the electrolyte for a zinc air battery comprises: potassium hydroxide aqueous solution; an organic additive that inhibits growth of dendrite formed on an anode containing zinc during charging and discharging of a zinc air battery; and a metal additive that inhibits growth of the dendrite formed on the anode containing zinc during charging and discharging of the zinc air battery.

Description

Electrolyte for zinc-air batteries

The present invention relates to an electrolyte for a zinc-air battery capable of suppressing the growth of dendrites formed in the anode during charging and discharging of the zinc-air battery.

Secondary batteries include an anode, a cathode, an electrolyte, and a separator, and their use is very diverse, such as electric vehicles, micro-mobility, and energy storage systems (ESSs), so the demand for them is high. situation is increasing.

There are various types of secondary batteries such as nickel cadmium batteries, nickel metal hydride batteries, lithium ion batteries, and lithium ion polymer batteries. there is.

However, lithium-ion batteries have a disadvantage in that stability may be lowered due to fire and explosion due to thermal runaway and reignition, etc., and the theoretical energy density limit is somewhat low.

Due to the above-mentioned disadvantages, secondary batteries are being developed to replace lithium-ion batteries, and among them, zinc-air batteries having a high theoretical energy density and manufacturing cost 5 times cheaper than lithium-ion batteries are being actively researched. .

However, in the zinc-air battery, as dendrites are excessively formed and grown at the anode during charging and discharging, the dendrites break the separator and cause an electrical short, resulting in a short cycle life of the battery.

In order to overcome this, active research is being conducted to suppress the formation and growth of dendrites at the anode during heavy discharge of zinc-air batteries. There was a problem with falling.

Accordingly, there is an urgent need to develop a zinc-air battery capable of securing energy efficiency while improving cycle life by properly forming and growing dendrites in the anode during charging and discharging.

Registration of Republic of Korea Patent Publication No. 10-1661960, 2016.09.27.

SUMMARY OF THE INVENTION It is an object of the present invention to solve the above problems, and for zinc-air batteries to which an additive is added to properly form and grow dendrites so that the cycle life of the zinc-air battery can be improved and output voltage can be secured at the same time to provide electrolytes.

The object of the present invention is not limited to the object mentioned above, and other objects not mentioned will be clearly understood from the description below.

In order to achieve the above object, the electrolyte for a zinc-air battery according to an aspect of the present invention includes an aqueous potassium hydroxide solution, an organic additive for inhibiting the growth of dendrites formed on the anode containing zinc during charging and discharging of a zinc-air battery, and zinc air It contains a metal additive that inhibits the growth of dendrites formed on the anode containing zinc during charging and discharging of the battery.

The electrolyte for a zinc-air battery according to an embodiment of the present invention according to the above configuration can be expected.

As the organic and metal additives added to the electrolyte allow the growth of dendrites formed at the anode during charging and discharging of the zinc-air battery to be properly performed, the cycle life of the energy efficiency of the zinc-air battery is improved while the energy efficiency is excessively reduced. it can be prevented

1 is a view showing the SEM analysis result of Test Example 1 when the electrolyte for a zinc-air battery according to Example 1 is used.
2 is a view showing the SEM analysis results of Test Example 1 when the electrolyte for a zinc-air battery according to Example 2 is used.
3 is a view showing the SEM analysis results of Test Example 1 when the electrolyte for a zinc-air battery according to Example 3 is used.
4 is a view showing the SEM analysis result of Test Example 1 when the electrolyte for a zinc-air battery according to Comparative Example 1 is used.
5 is a view showing the SEM analysis result of Test Example 1 when the electrolyte for a zinc-air battery according to Comparative Example 2 is used.
6 is a view showing the SEM analysis result of Test Example 1 when the electrolyte for a zinc-air battery according to Comparative Example 3 is used.
7 is a view showing the charge/discharge cycle test results of Test Example 2 using the zinc-air battery electrolyte according to Examples 1 to 3 and Comparative Examples 1 to 3;

Advantages and features of the present invention and methods of achieving them will become apparent with reference to the embodiments described below in detail in conjunction with the accompanying drawings. However, the present invention is not limited to the embodiments disclosed below, but will be implemented in various different forms, and only these embodiments allow the disclosure of the present invention to be complete, and those of ordinary skill in the art to which the present invention pertains. It is provided to fully inform the person of the scope of the invention. On the other hand, the terms used herein are for the purpose of describing the embodiments, and are not intended to limit the present invention. In this specification, the singular also includes the plural unless specifically stated otherwise in the phrase.

For convenience of explanation, in describing the method for manufacturing a magneto-electric laminate in which porous magnetostrictive electrodes are laminated and a magneto-electric laminate in which porous magnetostrictive electrodes are laminated according to embodiments of the present invention, substantially the same components are denoted by reference numerals. The descriptions are made coincidentally, and repeated explanations are omitted.

On the other hand, the inventors of the present invention, when an organic additive is added alone to the electrolyte in the process of inventing the electrolyte for a zinc-air battery, the effect of inhibiting the growth of dendrites is so excellent that the lifespan of the zinc-air battery can be improved, but the energy efficiency of the zinc-air battery It was confirmed that, when only the metal additive was included, the growth of dendrites was not effectively suppressed compared to when the organic additive was used alone. did

Accordingly, the inventors of the present invention have completed the present invention through continuous research and experiments in order to prevent energy efficiency from being reduced while improving the lifespan of a zinc-air battery.

Hereinafter, an electrolyte for a zinc-air battery according to embodiments of the present invention will be described with reference to the drawings.

The electrolyte for a zinc-air battery according to an embodiment of the present invention may include an aqueous potassium hydroxide solution, an organic additive, and a metal additive.

The potassium hydroxide aqueous solution may be prepared by dissolving potassium hydroxide (KOH) in water.

The concentration of the aqueous potassium hydroxide solution may be 3.5 to 4.5M.

If the concentration of the aqueous potassium hydroxide solution is less than 3.5M, the discharge rate of the zinc-air battery may decrease when the zinc-air battery electrolyte according to the embodiment of the present invention is included in the zinc-air battery.

When the concentration of the aqueous potassium hydroxide solution exceeds 4.5M, when the zinc-air battery electrolyte according to an embodiment of the present invention is included in the zinc-air battery, the discharge rate of the zinc-air battery may be excessively increased.

The organic additive inhibits the growth of dendrites formed on the anode during charging and discharging of a zinc-air battery.

The organic additive may be an organic compound having a predetermined dielectric constant, and may preferably include at least one selected from polyetherimide (PEI) and vanillin, and more preferably include vanillin. can

On the other hand, in the zinc-air battery, the anode containing zinc may have a flat portion and a fine tip formed on the surface.

When charging a zinc-air battery, charge aggregation is easier on the fine concavities and convexities compared to the flat parts, and the reduction of Zn ions occurs actively. The growth of dendrites becomes more concentrated compared to , and eventually the dendrites grown intensively in the protruding part may cause a short circuit of the zinc-air battery and shorten the life of the zinc-air battery.

The organic additive has a predetermined dielectric constant and is polarized when an electric field is applied during charging of the zinc-air battery. When the zinc-air battery is charged, the organic additive is adsorbed to the flat part and the fine unevenness of the anode to make the charge aggregated on the flat part and the fine unevenness uniform. This may be to prevent intensive growth of dendrites on the fine irregularities.

That is, the organic additive may be to suppress the growth of dendrites by making the dendrites grow uniformly on the flat surface of the anode and on the fine irregularities so that the dendrites are uniformly on the surface of the anode as a whole.

Metal additives inhibit the growth of dendrites formed on the anode during charging and discharging of zinc-air batteries. When dissolved in a solvent and dissociated, the standard reduction potential contains a metal oxide that generates a metal cation relatively larger than -0.76V. It may be one, more preferably, it may include a tin oxide that generates a tin cation when dissociated, and most preferably, it may include a stannous oxide (SnO).

The metal additive may be partially reduced prior to Zn ions in a plurality of preferred reduction sites where reduction of Zn ions actively occurs, such as fine irregularities on the surface of the anode during charging of a zinc-air battery.

That is, the metal additive is partially reduced at the reduction-preferring site prior to Zn ions, preventing the reduction of Zn ions at the reduction-preferring site, causing Zn ions to be reduced in places with low reduction preference, such as a flat part of the anode surface, through dendrites. It may be to inhibit the growth of dendrites by allowing them to be formed not only in the reduction preference site but also in the reduction preference area.

The electrolyte for a zinc-air battery according to an embodiment of the present invention may contain an organic additive at a concentration of 4 to 6 mM.

If the concentration of the organic additive contained in the electrolyte for a zinc-air battery according to an embodiment of the present invention is less than 4 mM, the growth of dendrites generated on the surface of the anode during charging of the zinc-air battery may not be effectively inhibited.

When the concentration of the organic additive contained in the electrolyte for a zinc-air battery according to an embodiment of the present invention exceeds 6 mM, the growth of dendrites generated on the surface of the anode during charging of the zinc-air battery is excessively suppressed, thereby energy efficiency of the zinc-air battery can be excessively reduced.

On the other hand, since the electrolyte for a zinc-air battery according to an embodiment of the present invention includes both an organic additive and a metal additive, an organic additive on the surface of the anode during charging and discharging of a zinc-air battery using the electrolyte for a zinc-air battery according to the embodiment of the present invention and the dendrite growth inhibition mechanism according to each metal additive can act independently.

Referring to the results of Test Examples 1 and 2 to be described later, in the electrolyte for a zinc-air battery, the organic additive may inhibit the growth of dendrites more effectively than the metal additive.

The electrolyte for a zinc-air battery according to an embodiment of the present invention may include a metal additive at a concentration of 0.5 or more and less than 1.5 mM.

When the concentration of the metal additive contained in the electrolyte for a zinc-air battery according to an embodiment of the present invention is less than 0.5 mM, the growth inhibition mechanism of dendrite by the metal additive hardly works, and the growth inhibition mechanism of dendrite by the organic additive is dominant. As a result, the growth of dendrites on the anode surface of the zinc-air battery can be excessively suppressed.

If the concentration of the metal additive contained in the electrolyte for a zinc-air battery according to an embodiment of the present invention is 1.5 mM or more, the effect due to the dendrite growth inhibition mechanism by the metal additive is greater than the effect due to the dendrite growth inhibition mechanism by the organic additive. It is too large to cause excessive growth of dendrites on the anode surface of the zinc-air cell.

As the electrolyte for a zinc-air battery according to an embodiment of the present invention includes both an organic additive and a metal additive, the growth of dendrites on the anode surface is relatively greater than when an organic additive is used alone in the electrolyte for a zinc-air battery. , there is an effect of not excessively reducing energy efficiency while improving the lifespan of a zinc-air battery by suppressing the growth of dendrites compared to using a metal additive alone.

<Example 1>

Potassium hydroxide (model name: DSP-39, manufactured by DUKSAN) was dissolved in distilled water to prepare an aqueous solution of potassium hydroxide having a concentration of 4M. To the prepared aqueous potassium hydroxide solution, vanillin (model name: DSP1-124, manufactured by DUKSAN) was added as an organic additive, and tin oxide (model name: 32200-1501, manufactured by JUNSEI) was added as a metal additive to make an electrolyte for a zinc-air battery. prepared. At this time, vanillin and stannous oxide were added to the potassium hydroxide aqueous solution so that the concentrations of vanillin and tin oxide in the zinc-air battery electrolyte were 5 mM and 0.5 mM, respectively.

<Example 2>

An electrolyte for a zinc-air battery was prepared in the same manner as in Example 1. However, vanillin and tin oxide were added to the potassium hydroxide aqueous solution so that the concentrations of vanillin and tin oxide in the electrolyte for zinc-air batteries were 5 mM and 1.0 mM, not 5 mM and 0.5 mM, respectively.

<Example 3>

An electrolyte for a zinc-air battery was prepared in the same manner as in Example 1. However, vanillin and tin oxide were added to the potassium hydroxide aqueous solution so that the concentrations of vanillin and tin oxide in the electrolyte for zinc-air batteries were 5 mM and 1.5 mM, not 5 mM and 0.5 mM, respectively.

<Comparative Example 1>

An electrolyte for a zinc-air battery was prepared in the same manner as in Example 1. However, an electrolyte for a zinc-air battery was prepared without adding organic and metal additives.

<Comparative Example 2>

An electrolyte for a zinc-air battery was prepared in the same manner as in Example 1. However, an electrolyte was prepared by adding only vanillin to a concentration of 5 mM as an organic additive without adding a metal additive.

<Comparative Example 3>

An electrolyte for a zinc-air battery was prepared in the same manner as in Example 1. However, an electrolyte was prepared by adding only stannous oxide as a metal additive to a concentration of 1 mM without adding an organic additive.

<Test Example 1>

1. Experimental method

(1) Production of dust collector specimen

Nickel foil (Alfa Aeser, 99.9%) was polished with 600 grid emery paper and washed with distilled water. After drying the distilled water, the nickel foil was masked to expose the nickel foil in an area of 0.25 cm ² to prepare a dust collector specimen.

(2) Electroplating

In order to analyze the dendrites formed on the surface of the anode when the zinc-air battery of the electrolyte according to Examples 1 to 3 and Comparative Examples 1 to 3 is charged, the electrolytes according to Examples 1 to 3 and Comparative Examples 1 to 3 were used as a plating solution ( After performing electroplating on the dust collector specimen prepared in 1), the electroplated part was analyzed by SEM.

Here, the zinc ion concentration in the electrolytes for zinc-air batteries according to Examples 1 to 3 and Comparative Examples 1 to 3 so that the electrolytes for zinc-air batteries according to Examples 1 to 3 and Comparative Examples 1 to 3 can be used as plating solutions during electroplating. Zinc oxide (model name: 8602-4405, manufactured by DAEJUNG) was added to 0.1M.

Using the dust collector specimen obtained in (1) as the anode, zinc foil as the cathode, and the zinc-air battery electrolyte according to Examples 1 to 3 and Comparative Examples 1 to 3 containing zinc ions at a concentration of 0.1M as a plating solution Electroplating was performed.

During electroplating, the temperature of the plating solution was 25° C., the current density was 60 mA/cm ⁻² , the plating time was 1800 seconds, and the current was 15 mA.

2. Experimental results

1 to 6 show the results of SEM analysis of the electroplated area of the electroplated dust collector specimen obtained in (2).

1 to 6 are diagrams showing the SEM analysis results of Test Example 1 when using electrolytes for zinc-air batteries according to Examples 1, 2, 3, Comparative Example 1, Comparative Example 2, and Comparative Example 3, respectively.

With reference to FIGS. 1 to 6 , the average height of dendrites in the portions plated with the zinc-air battery electrolyte according to Examples 1 to 3 and Comparative Examples 1 to 3 is summarized in Table 1 below.

Example 1 Example 2 Example 3 Comparative Example 1 Comparative Example 2 Comparative Example 3 average height
(μm) 107.2 107.8 249.4 827.3 88.1 267.8

1 to 4, compared with dendrites formed when using the zinc-air battery electrolyte according to Comparative Example 1 in which no organic additive and metal additive were added, compared with Examples 1 to 3 in which at least one of an organic additive and a metal additive was added In Examples 2 to 3, it can be seen that the height of the dendrite formed when the electrolyte for a zinc-air battery is used is relatively low, which is a result confirming that the organic additive and the metal additive effectively inhibit the dendrite growth.

5 and 6, it can be seen that the dendrite formed when the electrolyte for a zinc-air battery according to Comparative Example 2 is used has a relatively low height compared to the dendrite formed when the electrolyte for a zinc-air battery according to Comparative Example 3 is used. This is a result confirming that the additive inhibits dendrite formation more effectively than the metal additive.

In addition, it can be seen that the shape of the dendrite formed when the electrolyte for a zinc-air battery according to Comparative Example 2 is used is relatively blunt than the shape of the dendrite formed when the electrolyte for a zinc-air battery according to Comparative Example 3 is used.

This is because organic additives are adsorbed to the plating area as a whole so that dendrites grow uniformly over the entire plating area, while metal additives are adsorbed to areas where plating is preferred so that dendrites are concentrated in areas where plating is preferred. It is judged that it is due to the difference in the dendrite growth inhibition mechanism of the organic additive and the metal additive according to the prevention of growth.

1 to 3, it can be seen that the average height of the dendrites formed when the electrolyte for a zinc air battery according to Example 3 is used is relatively higher than the average height of the dendrites formed when the electrolyte for a zinc air battery according to Examples 1 and 2 is used. , This is a result confirming that the dendrite growth inhibition mechanism due to the metal additive prevails over the dendrite growth inhibition mechanism rare in the organic additive when a certain concentration of the metal additive is added when using a mixture of organic and metal additives.

That is, when the concentration of the metal additive is 0.5 or more and less than 1.5 mM, the dendrite growth inhibition mechanism by the organic additive is more dominant. It is judged that the height of the dendrite becomes larger as it predominates over the dendrite growth inhibition mechanism.

Referring to FIGS. 1 and 2, 5 and Table 1, the average height of the dendrites formed when the electrolyte for a zinc-air battery according to Examples 1 and 2 is used is relatively higher than the dendrites formed when the electrolyte for a zinc-air battery according to Comparative Example 2 is used. can be checked This is judged to be the effect of the addition of metal additives.

3 and 5, it can be seen that the dendrite formed when the electrolyte for a zinc-air battery according to Example 3 is used has a relatively blunt shape than the dendrite formed when the electrolyte for a zinc-air battery according to Comparative Example 3 is used. It is judged to be the effect of the addition.

<Test Example 2>

In order to compare the energy efficiency during charging and discharging of zinc-air batteries using the electrolytes according to Examples 1 to 3 and Comparative Examples 1 to 3, a charge/discharge cycle test was performed using the electrolytes according to Examples 1 to 3 and Comparative Examples 1 to 3 proceeded.

The charging current was +15 mA, the cut-off time was 30 minutes, the discharging current was -15 mA, and the cut-off voltage was 1.2 V. The number of cycle repetitions was set to 20.

7 is a test result of a charge/discharge cycle test of a zinc-air battery using the electrolyte for a zinc-air battery according to Examples 1 to 3 and Comparative Examples 1 to 3;

In FIG. 7 , the x-axis is the number of charge/discharge cycles and the y-axis is energy efficiency. In this case, the energy efficiency was defined as the ratio of the electrical energy emitted during discharging to the charged electrical energy during charging.

Referring to FIG. 7 , it can be seen that the energy efficiency is lowered when the electrolyte for a zinc-air battery according to Comparative Example 2 is used compared to Comparative Example 1, which is that the organic additive excessively inhibits the growth of dendrites to increase the energy efficiency of the battery. It is considered to be due to reduction.

In addition, when the electrolyte for a zinc-air battery according to Comparative Example 3 is used, it can be seen that energy efficiency is higher than when the electrolyte for a zinc-air battery of Comparative Example 1 is used, which is charged and discharged using the electrolyte for a zinc-air battery according to Comparative Example 1 It is judged that the dendrite is overgrown and destroyed during the cycle test.

Referring to FIG. 7 , when the charge/discharge cycle test was performed using the electrolyte for a zinc air battery according to Examples 1 to 3 and the electrolyte for a zinc air battery according to Comparative Example 2, for zinc air batteries according to Comparative Examples 1 and 3 It can be seen that the charge and discharge energy efficiency is lower than when using the electrolyte, which is considered to be due to the dendrite growth inhibitory effect of the organic additive.

However, when the electrolyte for a zinc-air battery according to Examples 1 to 3 is used, it can be seen that the charge/discharge energy efficiency is higher than when the electrolyte for a zinc-air battery according to Comparative Example 2 is used. It is judged that the average height of the dry is increased. In particular, it can be seen that the charge/discharge energy efficiency is high when the electrolyte for a zinc-air battery according to Example 1 is used.

In addition, it can be seen that the change in energy efficiency is smaller when the electrolyte for a zinc-air battery according to Examples 1 to 3 is used than when the electrolyte for a zinc-air battery according to Comparative Example 1 is used, which is the electrolyte for a zinc-air battery according to Examples 1 to 3 It is a result confirming that the stability of the battery is improved when using the zinc-air battery electrolyte according to Comparative Example 2.

To summarize the results of Test Example 1 and Test Example 2, the electrolyte for a zinc-air battery according to an embodiment of the present invention contains both an organic additive and a metal additive, so that the growth of dendrites is not excessively suppressed and the battery is properly formed. It may be to generate the effect of improving the lifespan of the device and at the same time preventing a decrease in energy efficiency.

According to Test Example 2, the electrolyte for a zinc-air battery according to an embodiment of the present invention may produce an effect of further improving the stability of the battery during charging and discharging of the battery than the electrolyte to which the organic additive is added alone.

Those of ordinary skill in the art to which the present invention pertains will understand that the present invention may be embodied in other specific forms without changing the technical spirit or essential characteristics thereof. Therefore, it should be understood that the embodiments described above are illustrative in all respects and not restrictive. The scope of the present invention is indicated by the claims to be described later rather than the above detailed description, and all changes or modifications derived from the claims and their equivalent concepts should be construed as being included in the scope of the present invention.

Claims (4)

aqueous potassium hydroxide solution;
an organic additive that inhibits the growth of dendrites formed on the anode containing zinc during charging and discharging of a zinc-air battery; and
What contains;
Electrolyte for phosphorus zinc air batteries. The method of claim 1,
The organic additive includes at least one selected from polyethyleneimine and vanillin
Electrolyte for phosphorus zinc air batteries. The method of claim 1,
When the metal additive is dissolved in the aqueous solution and dissociated, the standard reduction potential contains a metal oxide that generates a metal cation relatively larger than -0.76V.
Electrolyte for phosphorus zinc air batteries. The method of claim 1,
The concentration of the organic additive is 4 to 6mM, the concentration of the metal additive is 0.5 or more and less than 1.5mM
Electrolyte for a zinc-air battery, characterized in that.

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