Method for improving electrode capacity of low-temperature proton battery

Abstract

The invention discloses a method for improving the electrode capacity of a low-temperature proton battery. The method comprises the following steps: firstly, uniformly mixing MoO3, a conductive agent and a binder in proportion to obtain electrode slurry; coating a conductive current collector with the electrode slurry, and performing vacuum drying to obtain a MoO3 electrode; a MoO3 electrode is used as a working electrode, a carbon rod electrode is used as a counter electrode, an Ag / AgCl electrode is used as a reference electrode, and electrochemical performance optimization is respectively carried out in a sulfuric acid aqueous solution under normal temperature and low temperature conditions, so that the hydrogen storage capacity of MoO3 is improved. The low-temperature hydrogen suppression strategy in the invention greatly reduces the occurrence of hydrogen evolution side reaction, so that MoO3 can perform efficient hydrogen storage in a lower potential region, the voltage window is widened, the capacity and stability of the electrode are improved, and the low-temperature hydrogen suppression method has extremely high reference value for research and development of low-temperature batteries and has wide application prospects. Or the method can become a key link for constructing a future extreme condition battery energy storage system.

Description

Technical Field

[0001] The present invention belongs to the field of hydrogen storage materials, and particularly relates to a method for improving the electrode capacity of low-temperature proton batteries. Background Art

[0002] At present, new energy storage technologies represented by lithium-ion batteries are in the commercial development stage, but there are also problems such as high cost, thermal runaway under extreme conditions, and large temperature influence. Hydrogen ion batteries use protons as charge carriers. Hydrogen ions are one of the most abundant cations in nature, so they have resource advantages and cost advantages. Secondly, aqueous hydrogen ion batteries use aqueous electrolyte solutions, which are non-flammable and fundamentally solve the safety hazards brought by organic solutions. In addition, the charge transport mechanism in hydrogen ion batteries is different from the medium transport mechanism of other metal ions, but a Grotthuss mechanism involving hydrogen bond network conduction. The unique ion transport highway endows hydrogen ion batteries with excellent rate performance, suitable for large-scale grid energy storage, and some hydrogen ion batteries can work at extremely low temperatures, such as minus 70 degrees, which provides the possibility of power supply in extreme environments or in polar regions, outer space and other environments. As a new battery technology, the unique advantages of hydrogen ion batteries make them have great potential in specific application scenarios. With the progress of technology and the innovation of materials science, hydrogen ion batteries are expected to play an important role in the future energy storage field.

[0003] Among the electrode materials of aqueous hydrogen ion batteries, MoO 3 has received wide attention due to its high theoretical capacity (372 mAh g -1 ). However, MoO 3 also faces the inherent problems of aqueous batteries, that is, hydrogen evolution occurs at the MoO 3 negative electrode in the low potential region. The hydrogen evolution reaction in the low potential region is coupled with the hydrogen insertion reaction of MoO 3 , which hinders the hydrogen insertion capacity of MoO 3 in this region, making the potential unable to be widened to a lower level, and the continuous bubble evolution will destroy the stability of the electrode, resulting in a decrease in the capacity retention rate of MoO 3 . Summary of the Invention

[0004] The present invention is to inhibit the hydrogen evolution reaction of MoO 3 , decouple the hydrogen evolution and hydrogen insertion reactions in the low potential region, and more efficiently exert the hydrogen insertion capacity of MoO 3 . The purpose is to provide a method for improving the electrode capacity of low-temperature proton batteries.

[0005] The present invention is achieved by the following technical solutions:

[0006] A method for improving the electrode capacity of a low-temperature proton battery, comprising the following steps:

[0007] (ⅰ) Uniformly mix MoO 3 , a conductive agent, and a binder in proportion to obtain an electrode slurry;

[0008] (ⅱ) Coat the electrode slurry on a conductive current collector and dry it to obtain a MoO 3 electrode;

[0009] (ⅲ) Use the MoO 3 electrode as the working electrode, and optimize the electrochemical performance with the counter electrode and the reference electrode in an aqueous sulfuric acid solution under normal temperature conditions and low temperature conditions respectively, that is, complete the improvement of the hydrogen storage capacity of MoO 3 .

[0010] In the above technical solution, the conductive agent is any one of CNT, Ketjenblack, Acetylene black, Super P or Graphene; the binder is any one of PVDF, CMC, PTFE or LA..

[0011] In the above technical solution, the mass ratio of MoO 3 , the conductive agent and the binder is any one of 5:4:1, 6:3:1, 7:2:1 or 8:1:1.

[0012] In the above technical solution, the conductive current collector is any one of carbon cloth, carbon paper, graphite paper or graphite felt.

[0013] In the above technical solution, the MoO 3 loading in the dried MoO 3 electrode is 2.0 mg cm -2 ~10.0 mg cm -2 .

[0014] In the above technical solution, the drying condition in step (ⅱ) is vacuum drying at 80.0 °C for 24.0 h.

[0015] In the above technical solution, the counter electrode in step (ⅲ) is a carbon rod electrode, and the reference electrode is an Ag / AgCl electrode.

[0016] In the above technical solution, the concentration of the aqueous sulfuric acid solution in step (ⅲ) is 1.0 mol L -1 ~17.0 molL -1 .

[0017] In the above technical solution, the test temperature under normal temperature conditions is 20.0°C to 25.0°C; the test temperature under low temperature conditions is 0.0°C to -100.0°C.

[0018] In the above technical solution, the voltage window for optimizing the electrochemical performance is -0.8V to 0.5V vs. Ag / AgCl;

[0019] In the above technical solution, the low-temperature hydrogen inhibition strategy effectively broadens the voltage window of MoO 3 (from -0.4V vs. Ag / AgCl to -0.8V vs. Ag / AgCl), enabling the capacity of MoO 3 masked by the hydrogen evolution reaction in the low potential region to be released. The capacity is increased by 35.4%, and at the same time, the damage to the electrode caused by the hydrogen evolution reaction is reduced. The electrode stability is improved by 27.6% compared with MoO 3 at normal temperature.

[0020] The beneficial effects of the present invention are as follows:

[0021] The present invention provides a method for suppressing the hydrogen evolution side reaction on MoO 3 to improve the hydrogen storage capacity of MoO 3 . Under low temperature conditions, not only can the capacity masked by the coupling of hydrogen evolution and hydrogen intercalation in the low potential region be efficiently decoupled, but also the potential can reach a lower level while suppressing the hydrogen evolution reaction, broadening the voltage window of MoO 3 , compensating for the capacity that should have been lost due to low temperature and achieving the outstanding effect of increasing instead of decreasing. The present invention can also provide a forward-looking method for improving the capacity of other hydrogen intercalation electrodes and their applications in the low temperature field. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 is the scanning electron microscope image of the MoO 3 electrode prepared in Example 1 of the present invention;

[0023] Figure 2 is the X-ray diffraction spectrum of the MoO 3 electrode prepared in Example 1 of the present invention;

[0024] Figure 3 is the cyclic voltammetry polarization curve of the MoO 3 prepared in Example 1 of the present invention under normal temperature and low temperature conditions;

[0025] Figure 4 is the charge-discharge curve of the MoO 3 prepared in Example 1 of the present invention under normal temperature and low temperature conditions;

[0026] Figure 5 is the MoO3 Cycling performance graphs at normal and low temperatures.

[0027] For those of ordinary skill in the art, without creative efforts, other related drawings can be obtained based on the above drawings. Detailed implementation manners

[0028] In order to enable those in the technical field to better understand the technical solution of the present invention, the technical solution of the present invention will be further described below in conjunction with the drawings of the specification and through specific implementation manners.

[0029] Example 1

[0030] A method for improving the capacity of the electrode of a low-temperature proton battery, specifically:

[0031] (ⅰ) Mix MoO 3 , a conductive agent and a binder evenly according to a mass ratio of 7:2:1, and use a planetary ball mill for sufficient mixing at a rotation speed of 300.0 rpm. After 24.0 h, a light gray electrode slurry is obtained;

[0032] (ⅱ) Coat the light gray electrode slurry on a conductive current collector, and after vacuum drying at 80.0 °C for 24.0 h, a MoO 3 electrode is obtained. Weigh the mass of the electrode sheet before and after loading the active substance. The content of MoO 3 in the dried MoO 3 electrode is 2.0 mg cm -2 ;

[0033] (ⅲ) Use MoO 3 as the working electrode, a carbon rod electrode as the counter electrode, and an Ag / AgCl electrode as the reference electrode to conduct electrochemical performance tests at normal temperature (20.0 °C to 25.0 °C) and low temperature conditions (0.0 °C to -100.0 °C) in an aqueous sulfuric acid solution (1.0 mol L -1 ~17.0 mol L -1 ).

[0034] Test and characterize the MoO 3 electrode prepared in Example 1:

[0035] (a) Scanning electron microscope test

[0036] Perform a scanning electron microscope test on the MoO 3 electrode prepared in Example 1 to observe its surface morphology. It is Figure 1 observed that the active substance on the electrode is a bulk material with a diameter significantly in the range of 2 μm to 10 μm.

[0037] (b) X-ray diffraction pattern test

[0038] The MoO prepared in Example 1 3 electrode was subjected to an X-ray diffraction spectrum experiment to explore its phase composition. From Figure 2 obvious diffraction peaks were observed at 12.8°, 23.3°, 25.9°, 27.3°, 33.8° and 39.0°, corresponding to the (020), (110), (120), (021), (111) and (060) crystal planes of MoO 3 , proving that the active substance on the electrode prepared by the present invention is MoO 3 .

[0039] (c) Electrochemical performance test

[0040] The MoO prepared in Example 1 3 electrode was subjected to cyclic voltammetry polarization curve test. As Figure 3 shown, when the electrode potential (vs. Ag / AgCl) of MoO 3 was in the region of -0.8V to -0.5V, the current of its low-temperature polarization curve was significantly less than that at room temperature, indicating that low temperature significantly inhibited the hydrogen evolution reaction of MoO 3 .

[0041] The MoO prepared in Example 1 3 electrode was subjected to constant current charge-discharge test. As Figure 4 shown, due to the limitation of the hydrogen evolution reaction, the MoO 3 electrode at room temperature could not reach a lower potential, while the MoO 3 at low temperature, due to the inhibition of the hydrogen evolution reaction, the potential broke through to a lower level, and an obvious third reduction plateau appeared, improving the hydrogen intercalation capacity of MoO 3 .

[0042] The MoO prepared in Example 1 3 electrode was subjected to cyclic stability test. As Figure 5 shown, due to the inhibition of the hydrogen evolution side reaction of MoO 3 at low temperature, the damage to the electrode caused by the continuously evolving bubbles due to the hydrogen evolution reaction was reduced, improving the cyclic stability of MoO 3 .

[0043] The applicant declares that the above is only the specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed by the present invention fall within the protection scope and the disclosure scope of the present invention.

Claims

1. A method for increasing the electrode capacity of a low-temperature proton battery, characterized in that: The following steps are involved: (i) uniformly mixing MoO3, a conductive agent and a binder according to a certain proportion to obtain an electrode slurry; (ii) coating the electrode slurry on a conductive current collector and drying to obtain a MoO3 electrode; (iii) The MoO3 electrode was used as the working electrode, counter electrode and reference electrode in a sulfuric acid aqueous solution to optimize the electrochemical performance under room temperature and low temperature conditions, respectively, to improve the hydrogen storage capacity of MoO3.

2. The method for improving the electrode capacity of a low-temperature proton battery according to claim 1, characterized in that: The conductive agent is any one of CNT, Ketjenblack, Acetylene black, Super P or Graphene; the binder is any one of PVDF, CMC, PTFE or LA.

3. The method for improving the electrode capacity of a low-temperature proton battery according to claim 1, characterized in that: The mass ratio of MoO3, conductive agent and binder is any one of 5:4:1, 6:3:1, 7:2:1 or 8:1:

1.

4. The method for improving the electrode capacity of a low-temperature proton battery according to claim 1, characterized in that: The conductive current collector is any one of carbon cloth, carbon paper, graphite paper or graphite felt.

5. The method for improving the electrode capacity of a low-temperature proton battery according to claim 1, characterized in that: The MoO3 loading in the dried MoO3 electrode is 2.0 mg cm -2 ~10.0mg cm -2 .

6. The method for increasing the electrode capacity of a low-temperature proton battery according to claim 1, characterized in that: The drying condition of step (ii) is vacuum drying at 80.0°C for 24.0 hours.

7. The method for improving the electrode capacity of a low-temperature proton battery according to claim 1, characterized in that: The counter electrode in step (iii) is a carbon rod electrode, and the reference electrode is an Ag / AgCl electrode.

8. The method for increasing the electrode capacity of a low-temperature proton battery according to claim 1, characterized in that: The concentration of the sulfuric acid aqueous solution in step (iii) is 1.0 mol L -1 ~17.0mol L -1 .

9. The method for improving the electrode capacity of a low-temperature proton battery according to claim 1, characterized in that: The test temperature under the normal temperature condition is 20.0°C to 25.0°C; the test temperature under the low temperature condition is 0.0°C to -100.0°C.

10. The method for increasing the electrode capacity of a low-temperature proton battery according to claim 1, characterized in that: The voltage window for optimizing the electrochemical performance is -0.8V to 0.5V vs. Ag / AgCl.

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