WO2022246590A1

WO2022246590A1 - Aqueous metal ion secondary battery and aqueous electrolyte solution

Info

Publication number: WO2022246590A1
Application number: PCT/CN2021/095435
Authority: WO
Inventors: 陈维; 胥燕
Original assignee: 中国科学技术大学
Priority date: 2021-05-24
Filing date: 2021-05-24
Publication date: 2022-12-01

Abstract

The present disclosure provides an aqueous metal ion secondary battery and an aqueous electrolyte solution. The aqueous metal ion secondary battery comprises a positive electrode, a negative electrode and the aqueous electrolyte solution, wherein the aqueous electrolyte solution comprises an electrolyte, water and an organic compound, the electrolyte comprising a magnesium salt or an aluminum salt, the organic compound comprising one or more of an ether compound and an alcohol compound, and the mass percentages of the organic compound and water being 5-99.5%.

Description

Aqueous metal ion secondary battery and aqueous electrolyte

technical field

The present disclosure relates to the technical field of water-based secondary batteries, in particular to a water-based metal ion secondary battery and a water-based electrolyte.

Background technique

With the increasing consumption of fossil energy such as petroleum and environmental pollution, people pay more and more attention to the development and utilization of clean energy such as solar energy and wind energy. However, clean energy such as wind energy and solar energy has intermittent problems, which is not conducive to the utilization of energy. Therefore, it is very important to realize the optimal management and storage of energy. Lithium-ion batteries occupy an important position in the field of energy storage due to their advantages such as high energy density and long cycle life, but the current safety and cost issues of lithium-ion batteries hinder their further development.

Contents of the invention

In view of this, the present disclosure provides an aqueous metal ion secondary battery and an aqueous electrolyte, in order to at least partly solve the above technical problems.

As one aspect of the present disclosure, the present disclosure provides a water-based metal ion secondary battery, including a positive electrode, a negative electrode and an aqueous electrolyte. Wherein, the aqueous electrolyte includes electrolyte, water, and organic compound. Wherein, the electrolyte includes magnesium salt or aluminum salt. Organic compounds include one or more of ether compounds and alcohol compounds. The mass percentage of organic compound and water includes 5-99.5%.

According to an embodiment of the present disclosure, the aluminum salt includes one or more of aluminum sulfate, aluminum nitrate, aluminum perchlorate, aluminum acetate, aluminum chlorate, and aluminum trifluoromethanesulfonate.

According to an embodiment of the present disclosure, the magnesium salt includes one or more of magnesium sulfate, magnesium nitrate, magnesium perchlorate, magnesium acetate, magnesium chlorate, and magnesium trifluoromethanesulfonate.

According to an embodiment of the present disclosure, the ether compound includes one or more of diethylene glycol dimethyl ether and tetraethylene glycol dimethyl ether.

According to an embodiment of the present disclosure, the alcohol compound includes one or more of polyethylene glycol and isopropanol.

According to an embodiment of the present disclosure, the molar concentrations of the magnesium salt and the aluminum salt both include 0.01˜12 mol/L.

According to an embodiment of the present disclosure, the electrolyte further includes one or more of potassium salt, sodium salt, and bismuth salt.

According to an embodiment of the present disclosure, the molar concentration of the potassium salt, the sodium salt, and the bismuth salt includes 0.0001˜10 mol/L.

According to an embodiment of the present disclosure, the positive electrode includes manganese dioxide, and the negative electrode includes metal magnesium or metal aluminum.

As another aspect of the present disclosure, the present disclosure provides an aqueous electrolyte, including electrolyte, water, and an organic compound, wherein the electrolyte includes a magnesium salt or an aluminum salt; the organic compound includes one of an ether compound, an alcohol compound, or Various; the mass percentage of organic compound and water includes 5-99.5%.

In the water-based metal ion secondary battery involved in the present disclosure, the ether and alcohol compounds introduced into the electrolyte produce three beneficial effects:

1. Adsorb on the metal surface of the negative electrode, decompose preferentially, and optimize the composition of the passivation layer on the metal surface of the negative electrode.

2. Coordination of ethers and alcohols with Mg ²⁺ or Al ³⁺ , in the process of decoordination, prevent water from first obtaining electrons to generate hydrogen, leading to an increase in the pH value of the local solution to generate Mg(OH) ₂ or Al ₂ O ₃ .

3. O atoms in ethers and alcohols combine with H atoms in free water to limit the activity of free water and weaken the reaction between free water and negative metal, thereby inhibiting the formation of a metal hydroxide passivation layer on the negative metal surface and improving Battery voltage stability and cycle life stability.

Description of drawings

Figure 1 schematically shows a schematic diagram of the reaction mechanism of an aqueous MnO ₂ -Mg secondary battery;

Fig. 2 schematically shows the cycle stability curve of the aqueous MnO ₂ -Mg secondary battery.

Detailed ways

In order to make the purpose, technical solutions and advantages of the present disclosure clearer, the present disclosure will be further described in detail below in conjunction with specific embodiments and with reference to the accompanying drawings.

Rechargeable aqueous batteries have attracted extensive attention due to their high ionic conductivity, high safety, and low cost. Metal magnesium (Mg) and aluminum (Al) have the advantages of abundant reserves, low electrode potential, and high volume and mass energy density. Therefore, when the metal Mg and Al are used as the negative electrode, the aqueous battery can output a higher working voltage and break through the energy density bottleneck of the aqueous battery, which is one of the battery systems with great development potential.

However, in the aqueous Mg and Al battery system, highly active free water has poor compatibility with metal Mg and Al, and the two continue to react to form discontinuous Mg(OH) ₂ and Al ₂ O ₃ passivation films. The passivation film may not be able to block the continuous erosion of water on metal Mg, resulting in the continuous accumulation of Mg(OH) ₂ , increasing the polarization potential of the battery or not conducting Al ³⁺ , resulting in slow reaction kinetics.

As one aspect of the present disclosure, the present disclosure provides a water-based metal ion secondary battery, including a positive electrode, a negative electrode and an aqueous electrolyte. Wherein, the aqueous electrolyte includes electrolyte, water, and organic compound. Wherein, the electrolyte includes magnesium salt or aluminum salt. Organic compounds include one or more of ether compounds and alcohol compounds. The mass percentage of organic compound and water includes 5-99.5%. For example, 5%, 10%, 20%, 50%, 80%, 99.5%.

In the embodiments of the present disclosure, the ether and alcohol compounds in the electrolyte are adsorbed on the surface of the metal of the negative electrode and decomposed preferentially, which can optimize the composition of the passivation layer on the surface of the metal of the negative electrode. At the same time, ethers and alcohols coordinate with Mg ²⁺ or Al ³⁺ . During the process of decoordination, it prevents water from getting electrons to generate hydrogen, which leads to an increase in the pH value of the local solution and generates Mg(OH) ₂ or Al ₂ O ₃ . At the same time, O atoms in ethers and alcohols combine with H atoms in free water to limit the activity of free water and weaken the reaction between free water and negative metal, thereby inhibiting the formation of a metal hydroxide passivation layer on the negative metal surface and improving Battery voltage stability and cycle life stability.

In the embodiments of the present disclosure, organic compounds such as ether compounds and alcohol compounds that are miscible with water are used to make the aqueous electrolyte form a homogeneous miscible state, and the O atoms in the ether or alcohol compounds and the O atoms in the electrolyte The combination of H atoms in free water limits the activity of free water, thereby inhibiting the reaction of free water with Mg and Al, and inhibiting the formation of passive films of Mg(OH) ₂ and Al ₂ O ₃ .

According to an embodiment of the present disclosure, the molar concentrations of the magnesium salt and the aluminum salt both include 0.01˜12 mol/L. For example: 0.01mol/L, 1mol/L, 3mol/L, 5mol/L, 8mol/L, 12mol/L.

According to an embodiment of the present disclosure, the molar concentration of the potassium salt, the sodium salt, and the bismuth salt includes 0.0001˜10 mol/L. For example: 0.001mol/L, 0.01mol/L, 1mol/L, 5mol/L, 10mol/L.

As another aspect of the present disclosure, the present disclosure provides an aqueous electrolyte, including electrolyte, water, and an organic compound, wherein the electrolyte includes a magnesium salt or an aluminum salt; the organic compound includes one of an ether compound, an alcohol compound, or Various; the mass percentage of organic compound and water includes 5-99.5%, for example, 5%, 10%, 20%, 50%, 80%, 99.5%.

In the embodiment of the present disclosure, the introduction of ethers and alcohols into the electrolyte plays three roles: first, the ethers and alcohols are adsorbed on the surface of the metal negative electrode and decomposed preferentially to produce a continuous and dense organic passivation layer , to prevent water from corroding the negative electrode metal. Second, ethers and alcohols are coordinated with Mg ²⁺ or Al ³⁺ . In the process of decoordination, water is prevented from first obtaining electrons to generate hydrogen, which leads to an increase in the pH value of the local solution to form Mg(OH) ₂ or Al ₂ O ₃ . Third, ethers, alcohols and free water form weak hydrogen bonds, which inhibit the activity of free water. After the water activity is reduced, the reactivity of water and the metal negative electrode is reduced, and the formation of the metal hydroxide passivation film on the surface of the metal negative electrode is reduced.

The present disclosure will be described in detail below by taking a water-based MnO ₂ -Mg secondary battery as an example.

A carbon felt is used as the positive electrode current collector, a magnesium sheet is used as the negative electrode, and a mixed solution of 5 mol/L magnesium chloride water and diethylene glycol dimethyl ether is used as the electrolyte. In the mixed solution, the weight percentage of diethylene glycol dimethyl ether and water is 20%. And add manganese chloride to the electrolyte, so that the molar concentration of manganese chloride is 1mol/L.

After assembling the positive electrode current collector, negative electrode, and electrolyte into a secondary battery, the test was performed. The working principle of the positive and negative electrodes of the secondary battery is shown in FIG. 1 .

When charging, the divalent manganese ions (Mn ²⁺ ) in the solution undergo an electrochemical oxidation reaction on the positive electrode current collector, lose electrons, and are oxidized to MnO2. MnO2 deposits on the positive electrode current collector in solid form, and the lost electrons pass through The circuit flows to the negative electrode, while the Mg ²⁺ ions (or Al ³⁺ ions) in the solution get electrons at the negative electrode, are reduced to metal Mg (or Al), and are deposited on the negative electrode current collector. The battery discharge process is the opposite of the charge process. The main electrode reactions of the secondary battery are as follows:

Charging process:

Positive electrode: Mn ²⁺ +2H ₂ O→MnO ₂ +4H ⁺ +2 _e ^-

Negative electrode: Mg ²⁺ +2e ^- →Mg

Discharge process:

Positive electrode: MnO ₂ +4H ⁺ +2 _e ^- →Mn ²⁺ +2H ₂ O

Negative electrode: Mg→Mg ²⁺ +2e ^-

As shown in FIG. 2 , the curves at the top of the graph are indicated by arrows, indicating the change of the coulombic efficiency of the secondary battery. After 1000 cycles, the coulombic efficiency of the secondary battery is still close to 100%, with almost no attenuation. Compared with the cycle life of the traditional zinc-manganese dry battery once, the cycle life of 1000 times and the coulombic efficiency are almost not attenuated. The curve located at the bottom of the figure is indicated by the arrow, indicating the change of the specific capacity of the secondary battery. After 1000 cycles, the specific capacity of the secondary battery is still close to 500mAh/g. It can be seen that after 1000 cycles of the secondary battery, the specific capacity and Coulombic efficiency are almost not attenuated, which improves the practical application value of the secondary battery.

The specific embodiments described above have further described the purpose, technical solutions and beneficial effects of the present disclosure in detail. It should be understood that the above descriptions are only specific embodiments of the present disclosure, and are not intended to limit the present disclosure. Within the spirit and principles of the present disclosure, any modifications, equivalent replacements, improvements, etc., shall be included in the protection scope of the present disclosure.

Claims

A water-based metal ion secondary battery, comprising a positive electrode, a negative electrode and an aqueous electrolyte;

Wherein, the aqueous electrolyte includes electrolyte, water, organic compound, wherein,

The electrolyte includes a magnesium salt or an aluminum salt;

The organic compound includes one or more of ether compounds and alcohol compounds;

The mass percentage of the organic compound and the water includes 5-99.5%.
The secondary battery according to claim 1, wherein the aluminum salt comprises one or more of aluminum sulfate, aluminum nitrate, aluminum perchlorate, aluminum acetate, aluminum chlorate, and aluminum trifluoromethanesulfonate.
The secondary battery according to claim 1, wherein the magnesium salt comprises one or more of magnesium sulfate, magnesium nitrate, magnesium perchlorate, magnesium acetate, magnesium chlorate, and magnesium trifluoromethanesulfonate.
The secondary battery according to claim 1, wherein the ether compound comprises one or more of diethylene glycol dimethyl ether and tetraethylene glycol dimethyl ether.
The secondary battery according to claim 1, wherein the alcohol compound comprises one or more of polyethylene glycol and isopropanol.
According to the secondary battery according to claim 1, the molar concentrations of the magnesium salt and the aluminum salt both include 0.01˜12 mol/L.
The secondary battery according to claim 1, the electrolyte further comprises one or more of potassium salt, sodium salt, and bismuth salt.
The secondary battery according to claim 7, wherein the molar concentrations of the potassium salt, the sodium salt, and the bismuth salt are 0.0001˜10 mol/L.
The secondary battery according to claim 1, wherein the positive electrode includes manganese dioxide, and the negative electrode includes metal magnesium or metal aluminum.
A kind of aqueous electrolytic solution, comprises electrolyte, water, organic compound, wherein,

The electrolyte includes a magnesium salt or an aluminum salt;

The organic compound includes one or more of ether compounds and alcohol compounds;

The mass percentage of the organic compound and the water includes 5-99.5%.