KR102042098B1 - Seawater Battery - Google Patents

Abstract

The present invention relates to a seawater battery.
Seawater battery according to an embodiment of the present invention, the anode (anode); And a cathode comprising a catalyst layer made of an electrochemical catalyst material used for intercalation and deintercalation and bifunctional electrode catalysis of sodium ions. have.
The cathode material for a seawater battery according to an embodiment of the present invention promotes both an intercalation and deintercalation of sodium ions, as well as an oxygen evolution reaction (OER) / oxygen reduction reaction (ORR) catalytic activity reaction. Its charging and discharging rate is improved and energy capacity is increased.

Description

Seawater Battery

The present invention relates to seawater cells, and more particularly to electrochemical catalyst materials applied to cathodes for seawater cells.

Effective use of renewable energy sources is one of the most essential issues to be solved to achieve a sustainable society. Renewable energy sources such as wind, solar, hydro, biomass and geothermal energy do not reliably produce electricity. As a result, large-scale energy storage devices are necessary to accumulate intermittent energy in a consistent power supply that can meet current energy consumption, and high-energy lithium-ion batteries are expected to contribute as solutions. However, as the cost of lithium has increased recently, seawater cells have been considered as low-cost / high-efficiency technologies that can replace conventional lithium-ion battery technology for large-scale applications, and research and development efforts for seawater batteries have been activated.

[Patent Document 1] Korean Patent Registration No. 10-1702929

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and an object thereof is to provide a bifunctional electrochemical catalyst used in the cathode of a seawater battery.

The objects of the present invention are not limited to the above-mentioned objects, and other objects that are not mentioned will be clearly understood from the following description.

In order to achieve the above objects, a seawater battery according to an embodiment of the present invention, an anode (anode); And a cathode comprising a catalyst layer made of an electrochemical catalyst material used for intercalation and deintercalation and bifunctional electrode catalysis of sodium ions. have.

In an embodiment, the bifunctional electrode catalysis may include an oxygen evolution reaction (OER) / oxygen reduction reaction (ORR) catalytic activity reaction.

In an embodiment, the electrochemical catalyst material may comprise P2-type layered Na _0.5 Co _0.5 Mn _0.5 O ₂ .

In an embodiment, the seawater battery includes a positive electrode portion including the cathode impregnated with seawater, a negative electrode portion including the anode impregnated with an organic electrolyte, and positioned between the positive electrode portion and the negative electrode portion and the positive electrode portion and the negative electrode portion. It may further include a solid electrolyte for separating the negative electrode.

In an embodiment, the cathode may include a catalyst layer made of P2-type layered Na _0.5 Co _0.5 Mn _0.5 O ₂ provided on the cathode current collector and the cathode current collector.

In an embodiment, cobalt ions may be oxidized and reduced to 3 + / 4 + as the sodium ions are intercalated-deintercalated in the Na _0.5 Co _0.5 Mn _0.5 O ₂ material.

In an embodiment, the intercalation-deintercalation of the sodium ions may comprise a reaction in which the sodium ions are inserted or released into the hard carbon of the anode.

Specific details for achieving the above objects will be apparent with reference to the embodiments to be described later in detail with the accompanying drawings.

However, the present invention is not limited to the embodiments disclosed below, but may be configured in a variety of different forms, to make the disclosure of the present invention complete and those skilled in the art to which the present invention belongs ( In the following, the description is provided to fully inform the scope of the invention to the ordinary technician.

According to an embodiment of the present invention, by using a bifunctional electrochemical catalyst for the cathode of the seawater battery, Na ⁺ ion intercalation / deintercalation reaction and OER (oxygen) It promotes both the evolution reaction (oxygen reduction reaction) / ORR (oxygen reduction reaction) catalytic activity reaction, thereby improving the charge and discharge rate of the seawater battery and increase the energy density.

The effects of the present invention are not limited to the above-described effects, and the tentative effects expected by the technical features of the present invention will be clearly understood from the following description.

1 is a view showing a seawater battery according to an embodiment of the present invention.
2 is a graph of the electrochemical properties of the cathode according to an embodiment of the present invention.
3 and 4 is a graph of the charge and discharge performance of the seawater battery according to an embodiment of the present invention.

The present invention may be modified in various ways and may have various embodiments. Specific embodiments are illustrated in the drawings and described in detail.

Various features of the invention disclosed in the claims may be better understood in view of the drawings and detailed description. The apparatus, methods, recipes, and various embodiments disclosed herein are provided for purposes of illustration. The disclosed structural and functional features are intended to enable those skilled in the art to specifically practice the various embodiments, and are not intended to limit the scope of the invention. The terms and phrases disclosed are intended to explain various features of the disclosed invention in an easy-to-understand manner, and are not intended to limit the scope of the invention.

In the following description of the present invention, if it is determined that the detailed description of the related known technology may unnecessarily obscure the subject matter of the present invention, the detailed description thereof will be omitted.

Hereinafter, a configuration of a seawater battery according to an embodiment of the present invention will be described with reference to FIG. 1.

1 is a view showing a seawater battery 100 according to an embodiment of the present invention.

Referring to FIG. 1, the seawater battery 100 according to the present embodiment may include a cathode 110 and an anode 120. Specifically, the seawater battery 110 is positioned between an anode part including a cathode 110 impregnated in seawater, an anode part including an anode 120 impregnated in an organic electrolyte, and between the anode part and the cathode part, It may include a solid electrolyte for separating the negative electrode. In one embodiment of the present invention, nasicon was used as the solid electrolyte.

The cathode 110 is a P2-type layered Na _0.5 Co _0.5 Mn _0.5 O ₂ material provided on the positive electrode current collector and the positive electrode current collector, which may be carbon felt, carbon paper, carbon fiber, metal thin film or a combination thereof. It may comprise a catalyst layer made up. In one embodiment of the present invention, the carbon felt was used as the positive electrode current collector.

The anode 120 may include a negative electrode current collector and an active material layer positioned on the negative electrode current collector. In an embodiment of the present invention, hard carbon (HC) is used as the active material layer.

Available energy even when intercalation-deintercalation occurs by using a P2-type layered Na _0.5 Co _0.5 Mn _0.5 O ₂ material as a catalyst constituting the catalyst layer in the seawater cell 100 It can be obtained, has the effect of increasing the energy capacity. In other words, by using a catalyst made of such a material it is possible to reduce the voltage gap by improving both the OER (oxygen evolution reaction) / ORR (oxygen reduction reaction) reaction, thus increasing the amount of discharge compared to the charge, intercalation Deintercalation allows the charge through sodium ions to increase energy capacity. On the other hand, in the case of the conventional seawater battery, that is, in the case of the seawater battery using the existing catalyst material, only the OER / ORR reaction was performed to obtain energy, the intercalation-de-intercalation process was not performed.

For example, in the conventional case, a noble metal such as Pt was used as a catalyst constituting the catalyst layer of the cathode, and only an OER / ORR reaction occurred on the surface of the noble metal based electrocatalyst such as Pt. Since no deintercalation reaction occurred, energy could not be obtained during charging and discharging, resulting in low availability and high cost, which hampered the large-scale use of seawater batteries. However, according to various embodiments of the present invention, OER / ORR by using a P2-type layered Na0.5Co0.5Mn0.5O2 material as a catalyst constituting the catalyst layer of the cathode 110 in the seawater cell 100, In addition to the reaction, Na + ion intercalation-deintercalation reaction occurs, which has the effect of increasing the energy capacity. In this case, Co ions may be oxidized and reduced to 3 + / 4 + as Na + ions are intercalated-deintercalated. In one embodiment of the present invention, intercalation-deintercalation of Na + ions may refer to a reaction in which Na + ions are inserted or released into the active material layer of the anode 120, for example, hard carbon.

에서 NaOH 2몰(mole) 및 Na₂CO₃ 1몰을 함유하는 용액이 제조될 수 있다. In some embodiments, the P2-type layered Na _0.5 Co _0.5 Mn _0.5 O ₂ material may be prepared by a mixed hydroxy-carbonate (MHC) method. For example, by adding and stirring a precursor solution of Co (NO ₃ ) ₂ .6H ₂ O and Mn (NO ₃ ) ₂ .4H ₂ O salt (Sigma-Aldrich), 40

A solution containing 2 moles of NaOH and 1 mole of Na ₂ CO ₃ can be prepared.

에서 24시간 동안 건조될 수 있다. 또한, 균질한 혼합물을 만들기 위해 (Co_0.5Mn_0.5)₂(OH)₂CO₃전구체와 Na₂CO₃분말이 분쇄기에 의해 400rpm에서 2시간 동안 잘 갈아서 분쇄될 수 있다. During the addition of the precursor solution, a precipitate of (Co _0.5 Mn _0.5 ) ₂ (OH) ₂ CO ₃ compound is obtained, and the obtained precipitate is washed with distilled water and ethanol and then 60

Can be dried for 24 hours. In addition, the (Co _0.5 Mn _0.5 ) ₂ (OH) ₂ CO ₃ precursor and the Na ₂ CO ₃ powder can be ground and ground well at 400 rpm for 2 hours by a mill to make a homogeneous mixture.

에서 12시간 동안 하소(calcine)시키고, P2-타입 층상 Na_0.5Co_0.5Mn_0.5O₂ 물질이 획득될 수 있다. 예를 들어, 혼합물의 열분해 반응은 하기 <화학식 1>과 같이 정의될 수 있다.Crushed mixture 900

Calcined for 12 hours at, and a P2-type layered Na _0.5 Co _0.5 Mn _0.5 O ₂ material can be obtained. For example, the pyrolysis reaction of the mixture may be defined as in the following <Formula 1>.

In the P2-type layered Na _0.5 Co _0.5 Mn _0.5 O ₂ material, sodium ions are arranged at two prismatic sites of the cathode 110 and share a corner and face, and the Na _0.5 Co proposed in the present invention. _{The 0.5} Mn _0.5 O ₂ material comprises multiple oxidation states corresponding to the P2-type layered Na _0.5 ⁺ Co _0.5 ³⁺ Mn _0.5 ⁴⁺ 0 ₂ structure. In this case, OER activity can be promoted based on Co ^{3 + / 4 +} ions, followed by ORR activity based on Mn ⁴⁺ ions.

Accordingly, by using P2-type layered Na _0.5 Co _0.5 Mn _0.5 O ₂ as a catalyst on a seawater battery positive electrode current collector, redox reaction based on Na ⁺ ions and bifunctional electrode catalysis can be expressed. Specifically, the P2-type layered Na _0.5 Co _0.5 Mn _0.5 O ₂ material is the main electrochemical reaction of the seawater cell 100, which will promote both O ⁺ / ORR catalytic activity as well as Na ⁺ ion intercalation-deintercalation. Can be.

Here, the Na ⁺ ion intercalation-deintercalation and OER / ORR catalyst activation process can be referred to as a dual process. As a result, the seawater battery 100 using the P2-type layered Na _0.5 Co _0.5 Mn _0.5 O ₂ material as a cathode improves the charging and discharging rate and increases the energy density.

According to some embodiments, in a high Na content system that is expected to stabilize the P2 structure of the laminate material up to a high voltage range, a P2-type layered Na _0.5 Co _0.5 Mn _0.5 O ₂ material may be used as the cathode 110. . According to various embodiments of the present disclosure, in order to understand the cell voltage and the cycling performance of the seawater battery 100, the full-cell is a cathode 110 with Na _0.5 Co _0.5 Mn _0.5 O ₂ material. The anode 120 may be manufactured using hard carbon.

In this case, the Na _0.5 Co _0.5 Mn _0.5 O ₂ material, the electrode material, constitutes a single P2 phase and is very well implemented as a high energy density rechargeable cathode 110.

In some embodiments, half-cell and full-cell seawater cells are used in aqueous seawater as catholyte and nonaqueous material as anolyte (e.g., in tetraethylene glycol dimethylether) partitioned by a ceramic NASICON solid electrolyte. 1M NaCF ₃ SO ₃ ) and P2-type layered Na _0.5 Co _0.5 Mn _0.5 O ₂ material as cathode and sodium metal and hard carbon as anode. For example, electrochemical reactions that may occur at the cathode 110 and the anode 120 of the seawater battery 110 may be defined as in the following <Formula 2> and <Formula 3>.

2 is a graph of the electrochemical characteristics of the cathode 110 according to an embodiment of the present invention.

Referring to FIG. 2A, in consideration of the proposed dual process, the P2-type layered Na _0.5 Co _0.5 Mn _0.5 O ₂ material used in the cathode 110 may be formed of a 20% Pt / C catalyst and a carbon felt substrate ( For 5 hours at 0.1 mA (load weight 10 mg), a non-aqueous electrolyte (e.g., 1M NaCF3SO3 in TEGDME) was used as the anolyte and aqueous It was applied to the seawater battery 100 using the seawater as the catholyte.

In this case, the voltage vs. time performance for substrates consisting only of uncatalyzed carbon felt (red line) and 20% Pt / C on carbon felt as catalyst (blue line) yields a complete OER and ORR similar to the flat voltage profile. Characteristics.

However, when a P2-type layered Na _0.5 Co _0.5 Mn _0.5 O ₂ material was used as catalyst on the carbon felt (green line), two types of voltage profiles related to 1) slope and 2) plat were developed. Indicates. The voltage profile of the green line includes the slope voltage profile corresponding to Na ⁺ ion intercalation-deintercalation and the flat voltage profile associated with the OER / ORR characteristics. That is, the P2-type layered Na _0.5 Co _0.5 Mn _0.5 O ₂ material for half-cell seawater cells shows better performance compared to 20% Pt / C catalysts and carbon felt substrates.

Referring to (b) of FIG. 2, Na ⁺ ion intercalation-deintercalation and OER / ORR characteristics can be confirmed. For example, the delivered discharge capacity may be defined as the corresponding Na ⁺ ion intercalation-deintercalation process (slope voltage profile) for P2-type layered Na _0.5 Co _0.5 Mn _0.5 O ₂ material. 30 mAh g-1. In some embodiments, constant for Na ⁺ ion intercalation-deintercalation when the charge-discharge cycle duration is extended to 10 hours based on 0.1 mA to confirm clear OER / ORR characteristics. The slope voltage profile and the flat voltage profile for the OER / ORR characteristics can be identified.

When reference to Fig. (C) 2, Na ⁺ ions half-from the voltage-capacity graph of the result cell (half-cell), P2- type layer Na _0.5 Co _0.5 Mn _0.5 O ₂ material Na ⁺ ion intercalation - We can see the slope voltage profile due to deintercalation. Thus, the P2-type layered Na _0.5 Co _0.5 Mn _0.5 O ₂ material is used as a catalyst on the active material of the cathode 110 of the seawater cell 100 and also operates in the high voltage region with good rate capacity. In some embodiments, ˜52 mAh g − between 3.0 and 4.4 V at 0.1 C for 50 cycles using a nonaqueous 1 M NaPF 6 in a 1: 1 (v / v) EC-PC with FEC (5 wt.%). 1 is given to the Na-ion half-cell.

Referring to (d) of FIG. 2, cyclic voltammetric analysis was performed at 0.1 mV s −1 at 2.5-4.0 V, which is compared with the carbon felt substrate to form a P2-type layered Na _0.5 Co _0.5. In the presence of apparent oxidation and reduction peaks at 3.31 / 3.04V for Co ^{3 + / 4 +} redox species due to the Na-ion intercalation-deintercalation process of Mn _0.5 O ₂ material It can be confirmed by. That is, from the obtained oxidation and reduction peaks, it was confirmed that the P2-type layered Na _0.5 Co _0.5 Mn _0.5 O ₂ material promotes the redox process associated with Co ^{3 + / 4 +} redox species for the seawater cell 100. Can be.

3 and 4 is a graph of the charge and discharge performance of the seawater battery according to an embodiment of the present invention.

Referring to FIG. 3A, a half-cell seawater charge-discharge cycling study was conducted at 0.1 mA, and considering the voltage versus time performance during the initial 5 cycles, P2-type layered Na _0.5 Co _0.5 Mn _0.5 O _{It can be seen that the two} materials show a significant improvement in the charge and discharge performance of the seawater cell 100 compared to the carbon felt substrate and the 20% Pt / C catalyst.

For example, the obtained voltage difference of ˜0.78 V (ΔV) for Na ⁺ ion intercalation-deintercalation and OER / ORR properties of P2-type layered Na _0.5 Co _0.5 Mn _0.5 O ₂ material is carbon felt. It is smaller than the substrate and approximates the performance of nearly 20% Pt / C catalyst.

Referring to FIG. 3 (b), a half-cell seawater cell cycle study using P2-type layered Na _0.5 Co _0.5 Mn _0.5 O ₂ material as the cathode 110 was compared with a carbon felt substrate and a 20% Pt / C catalyst. Showing good cycle stability for 50 cycles.

Referring to (c) of FIG. 3, the voltage vs. time cyclic graph can confirm the characteristics of Na + ion intercalation-deintercalation and OER / ORR catalytic activity associated with the integrated voltage profile corresponding to the slope and flat voltage regions. have.

Referring to FIG. 3D, the half-cell seawater battery exhibits a constant voltage difference of ˜0.78 V (ΔV) at a voltage efficiency of 80%. In some embodiments, to verify the performance of the designed cathode in the device, a full-cell seawater cell uses ceramic NASICON and seawater catholyte as the solid electrolyte, and nonaqueous material (eg 1M NaCF3SO3 in TEGDME) as the solid electrolyte. , Using HC as an anode. In some embodiments, the anode can be selected based on Na-ion half-cell cycling analysis.

Referring to FIG. 4A, half-cell (red line) and full-cell (blue line) voltage versus time profiles are plotted with Na ⁺ ions for the cathode of the P2-type layered Na _0.5 Co _0.5 Mn _0.5 O ₂ material. It can be compared for a dual process of intercalation-deintercalation and OER / ORR catalytic activity.

Referring to Figure 4 (b), it can be seen that the P2-type layered Na _0.5 Co _0.5 Mn _0.5 O ₂ material is compared with the carbon felt substrate for the performance of the full-cell of the seawater battery. That is, the voltage difference for the P2-type layered Na _0.5 Co _0.5 Mn _0.5 O ₂ material is about 0.36 V, much less than the carbon felt substrate (1.06 V), and the hard carbon discharge capacity is 183 mAh g-1.

Referring to (c) of FIG. 4, a considerable voltage stability of the electrode can be confirmed through a graph of voltage versus time.

Referring to FIG. 4D, in the full-cell cycling experiment, the hard carbon discharge capacity is stabilized after 5 cycles, and the stabilized discharge capacity is 183 mAh g-1 having excellent cycle stability, and 0.1 mA for 50 cycles. It can be seen that at 85% Coulomb efficiency is maintained. That is, the cathode of the P2-type Na _0.5 Co _0.5 Mn _0.5 O ₂ material represents an excellent dual process of Na ⁺ ion intercalation-deintercalation and OER / ORR catalytic activity corresponding to the integrated voltage profile for seawater cells. It can operate on a commercial scale.

The above descriptions are merely illustrative of the technical idea of the present invention, and various changes and modifications may be made by those skilled in the art without departing from the essential characteristics of the present invention.

Therefore, the embodiments disclosed herein are not intended to limit the technical spirit of the present invention, but to describe, and the scope of the present invention is not limited by these embodiments.

The scope of protection of the present invention should be interpreted by the claims, and all technical ideas within the scope equivalent thereto should be understood as being included in the scope of the present invention.

100: seawater battery
110: cathode
120: anode

Claims (7)

Anode; And
A cathode comprising a catalyst layer of an electrochemical catalyst material used for intercalation and deintercalation of sodium ions and bifunctional electrode catalysis;
Including,
The electrochemical catalyst material comprises a P2-type layered Na _0.5 Co _0.5 Mn _0.5 O ₂ ,
The P2-type layered Na _0.5 Co _0.5 Mn _0.5 O ₂ Silver, Of (Co _0.5 Mn _0.5 ) ₂ (OH) ₂ CO ₃ precursor and Na ₂ CO ₃ powder produced by stirring the precursor solution of Co (NO ₃ ) ₂ .6H ₂ O and Mn (NO ₃ ) ₂ .4H ₂ O salts Produced by calcining the mixture,
Seawater battery.
The method of claim 1,
The bifunctional electrode catalyst reaction,
Including an oxygen evolution reaction (OER) / oxygen reduction reaction (ORR) catalytic activity reaction,
Seawater battery.
delete The method of claim 1,
Further comprising a cathode comprising the cathode impregnated in sea water, a cathode comprising the anode impregnated in an organic electrolyte and a solid electrolyte located between the anode and the cathode to separate the anode and the cathode doing,
Seawater battery.
The method of claim 4, wherein
The cathode,
Comprising a positive electrode collector and a catalyst layer made of P2-type layered Na0.5Co0.5Mn0.5O2 provided on the positive electrode current collector,
Seawater battery.
The method of claim 5,
In the Na0.5Co0.5Mn0.5O2 material, cobalt ions are oxidized and reduced to 3 + / 4 + as the sodium ions are intercalated-deintercalated.
Seawater battery.
The method of claim 5,
Intercalation-deintercalation of the sodium ions comprises reaction in which the sodium ions are inserted or released into the hard carbon of the anode,
Seawater battery.

Images