CN109428138B - Preparation method of lithium-air battery and lithium-air battery - Google Patents

Abstract

The invention provides a preparation method of a lithium-air battery without metal lithium, which comprises the following steps: (1) mixing and coating a silicon-based negative electrode material, a conductive agent and a binder on a negative electrode current collector; (2) mixing and pressing a catalyst, a conductive agent, a binder and lithium nitride to a positive current collector in an anhydrous and oxygen-free environment; (3) and (3) separating the positive electrode and the negative electrode by using a diaphragm in an anhydrous and oxygen-free environment, and dropwise adding an electrolyte to assemble the lithium-air battery. According to the lithium-silicon alloy cathode, lithium nitride is used as a lithium source, a silicon-based material is used as a cathode, the lithium-silicon alloy cathode is formed during the first charging, metal lithium is replaced, lithium dendrite is avoided, and a discharge product lithium peroxide can be effectively stored in a vacancy generated by decomposition of the lithium nitride.

Description

Preparation method of lithium-air battery and lithium-air battery

technical field

The invention relates to a preparation method of a lithium-air battery, and belongs to the technical field of fuel cells.

Background technique

With the increasing urgency of energy demand in modern society, secondary batteries with high energy density have become the focus of future energy industry development, and lithium-ion batteries have become the most commonly used secondary batteries due to their outstanding performance advantages. However, the commonly used negative electrode material for existing lithium-ion batteries is graphitized carbon, whose theoretical specific capacity is 370mAh/g, and the positive electrode material is lithium iron phosphate, lithium cobaltate, lithium manganate, and ternary materials, whose actual specific capacity is far from meet the needs of modern society. In particular, the rapid development of electric vehicles has put forward higher requirements for the development of high specific energy lithium-ion batteries. The high specific energy advantages of metal lithium-based battery systems have become more and more research hotspots and development directions, such as lithium-sulfur batteries and lithium-air batteries, the theoretical energy density of Li/S batteries can be as high as 2600Wh/Kg, and lithium-air batteries The energy density of the battery is as high as 3500Wh/Kg, which is much higher than the energy density of the current conventional lithium-ion battery of about 200Wh/Kg. However, there are two main problems in the use of metallic lithium as the negative electrode material of secondary batteries. One is that due to the high activity of metallic lithium, it is easy to irreversibly react with the electrolyte during the cycle, consume the electrolyte, reduce the Coulombic efficiency, and lead to The second is that the dendrites and "dead lithium" formed by metal lithium during the cycle will also reduce the cycle efficiency of the lithium electrode. If the lithium dendrite continues to grow, it will pierce the separator and cause a series of safety problems such as short circuit or even explosion. In particular, since the lithium-air battery is a semi-open system, the protection of metallic lithium is a difficult problem. Therefore, it is of great significance to find a high specific capacity anode material that can replace metallic lithium.

Silicon material has a theoretical specific capacity of up to 4200mAh/g, and has a lower charge-discharge platform than lithium, but if it is to be used in lithium-air batteries, it must first be reacted with lithium to form an alloy. Electrodes are difficult and unstable. Therefore, there are still great challenges in applying silicon-based anode materials to lithium-air batteries.

SUMMARY OF THE INVENTION

The purpose of the present invention is to provide a method for making a lithium-air battery without metal lithium and a lithium-air battery made by using the method, wherein a silicon-based material is used as the negative electrode, which avoids the low coulombic efficiency, low safety, and low lithium metal lithium. Dendrite problem. The lithium-air battery uses lithium nitride as the lithium source, realizes the in-situ electrochemical lithium intercalation of the silicon-based negative electrode through one-time assembly of the lithium-air battery, and the vacancies generated by the decomposition of lithium nitride can effectively store the discharge products of the lithium-air battery. The preparation method of the metal-free lithium-air battery is simple to operate and easy to realize industrial application.

The present invention is achieved through the following technical solutions:

In a first aspect, the present invention provides a method for preparing a lithium-air battery, comprising the following steps:

Prepare battery negative electrode and battery positive electrode respectively;

In an anhydrous and oxygen-free environment, the battery positive electrode, the separator and the battery negative electrode are sequentially packaged, and an electrolyte is added dropwise to obtain the lithium-air battery;

The preparation method of the battery negative electrode is:

After mixing the silicon-based negative electrode material, the conductive agent and the binder uniformly, it is coated on the negative electrode current collector and dried to obtain the battery negative electrode.

As a preferred solution, the conductive agent for the negative electrode is one or more of acetylene black, Super P, Ketjen black, and conductive graphite.

As a preferred solution, the binder for the negative electrode is one or more of polyacrylic acid, sodium alginate, sodium carboxymethyl cellulose, polyvinylidene fluoride, cyclodextrin, gum arabic, xanthan gum, and guar gum .

As a preferred solution, the preparation method of the positive electrode of the battery is:

In an anhydrous and oxygen-free environment, the lithium nitride, the catalyst, the conductive agent and the binder are mixed uniformly, and then pressed on the positive electrode current collector to obtain the positive electrode of the battery.

As a preferred solution, the material of the positive electrode current collector is nickel foam or carbon paper.

As a preferred solution, the content of the catalyst in the positive electrode of the battery is 1-10%.

As a preferred solution, the catalyst is one or more of carbon nanotubes, Pt, Ru, Pd, Ag, Au, RuO ₂ , MnO ₂ , Co ₃ O ₄ , and Fe ₃ O ₄ .

As a preferred solution, the conductive agent for the positive electrode is one or more of acetylene black, Super P, Ketjen black, and conductive graphite.

As a preferred solution, the adhesive is PTFE.

As a preferred solution, the negative electrode current collector is copper foil.

As a preferred solution, the silicon-based negative electrode material is selected from one or more of nano-silicon powder, micro-silicon powder, silicon/carbon composite material, silicon oxide, and silicon oxide/carbon composite material.

As a preferred solution, the electrolyte includes a lithium salt and a solvent, the lithium salt is selected from one or more of LiNO ₃ , LiPF ₆ , LiTFSI, LiFSI, LiClO ₄ , and LiCF ₃ SO ₃ , and the solvent is selected from One of ethylene glycol dimethyl ether, diethylene glycol dimethyl ether, triethylene glycol dimethyl ether, tetraethylene glycol dimethyl ether, dimethyl sulfoxide, N,N-dimethylformamide or several.

As a preferred solution, the electrolyte also contains a film-forming additive, the mass fraction of the film-forming additive in the electrolyte is 1-5%, and the film-forming additive is preferably fluoroethylene carbonate.

As a preferred solution, the capacity ratio of the positive electrode material to the negative electrode material is 1.05-1.2.

In the present invention, nitrogen and lithium ions are generated after the decomposition of lithium nitride;

Nitrogen gas is released through the air electrode, and lithium ions pass through the electrolyte to the negative electrode to react with silicon to form a lithium-silicon alloy.

In a second aspect, the present invention also provides a lithium-air battery prepared by the aforementioned method.

Lithium nitride has a theoretical specific capacity of 2300mAh/g, which can be decomposed at a lower potential (about 1V relative to metal lithium), and the decomposition products are lithium ions and nitrogen gas. Since the lithium-air battery is a semi-open system, the resulting Nitrogen is easy to remove.

Compared with the prior art, the present invention has the following beneficial effects:

1. Use silicon-based materials instead of metal lithium as the negative electrode material of lithium-air batteries. The efficiency of metal lithium in lithium-air batteries is 20% to 30%, and silicon-based materials have an efficiency of more than 90%, which avoids metal lithium. low efficiency, low safety and dendrite problems;

2. Using lithium nitride as the lithium source, one-time production of a battery to form a lithium-silicon alloy negative electrode to obtain a lithium-air battery with excellent performance.

Description of drawings

Other features, objects and advantages of the present invention will become more apparent by reading the detailed description of non-limiting embodiments with reference to the following drawings:

Fig. 1 is the charging curve of the first circle of the lithium-air battery without metal lithium prepared in Example 1 of the present invention;

Fig. 2 is the 2nd and 5th cycle charge-discharge curves of the lithium-air battery without metal lithium prepared in Example 1 of the present invention;

Fig. 3 is the charging curve of the first circle of the lithium-air battery without metal lithium prepared in Example 3 of the present invention;

FIG. 4 is the charge-discharge curves of the 2nd, 5th, and 10th cycles of the lithium-air battery without metal lithium prepared in Example 3 of the present invention.

Detailed ways

The present invention will be described in detail below with reference to specific embodiments. The following examples will help those skilled in the art to further understand the present invention, but do not limit the present invention in any form. It should be noted that, for those skilled in the art, several modifications and improvements can be made without departing from the concept of the present invention. These all belong to the protection scope of the present invention.

Example 1

Using nano-silicon material as the negative electrode and carbon nanotubes as the positive electrode catalyst, a method for manufacturing a lithium-air battery without metal lithium is as follows:

(1) mixing nano-silicon powder, conductive agent and binder to prepare slurry, coating on copper foil, and vacuum drying to obtain the negative electrode part of the battery;

(2) In an anhydrous and oxygen-free environment, fully mix lithium nitride, carbon nanotubes, conductive agent, and binder, and take the mixture and press it on the nickel foam to form a positive electrode part;

(3) In an anhydrous and oxygen-free environment, encapsulate the above-prepared positive electrode, separator and negative electrode in sequence, and drop an electrolyte solution.

So far, the lithium-air battery without metal lithium is completed.

The charge-discharge curve of the lithium-air battery without metal lithium prepared in this example is shown in Figure 1. The decomposition of lithium nitride is mainly at about 1V. After charging to 3.5V, the lithium nitride is basically completely decomposed, and lithium silicon is formed at the negative electrode. Alloy, the 2nd and 5th cycle charge-discharge curves of the lithium-air battery without metal lithium prepared in Example 1 of the present invention are shown in Figure 2, the lithium-silicon alloy is used as the negative electrode, carbon nanotubes are used as the catalyst, and the capacity is 0.9 in oxygen. The charge and discharge of mAh cm ^-2 can be cycled normally, and the charge overpotential is small.

Example 2

Using nano-silicon material as the negative electrode and carbon-supported Ru catalyst as the positive electrode catalyst, a method for manufacturing a lithium-air battery without metal lithium is as follows:

(1) mixing nano-silicon powder, conductive agent and binder to prepare slurry, coating on copper foil, and vacuum drying to obtain the negative electrode part of the battery;

(2) In an anhydrous and oxygen-free environment, fully mix lithium nitride, carbon-supported Ru catalyst, conductive agent, and binder, and take the mixture and press it on the nickel foam to form a positive electrode part;

(3) In an anhydrous and oxygen-free environment, encapsulate the above-prepared positive electrode, separator and negative electrode in sequence, and drop an electrolyte solution.

So far, the lithium-air battery without metal lithium is completed.

Example 3

Using silicon oxide material as the negative electrode and carbon nanotubes as the positive electrode catalyst, a method for manufacturing a lithium-air battery without metal lithium is as follows:

(1) prepare slurry by mixing silicon oxide, conductive agent and binder, coat on copper foil, and obtain battery negative electrode part after vacuum drying;

(2) In an anhydrous and oxygen-free environment, fully mix lithium nitride, carbon nanotubes, conductive agent, and binder, and take the mixture and press it on the nickel foam to form a positive electrode part;

(3) In an anhydrous and oxygen-free environment, encapsulate the above-prepared positive electrode, separator and negative electrode in sequence, and drop an electrolyte solution.

So far, the lithium-air battery without metal lithium is completed.

The charge-discharge curve of the lithium-air battery without metal lithium prepared in this example is shown in Figure 3. The decomposition of lithium nitride is mainly at about 1V. After charging to 3.5V, the lithium nitride is basically completely decomposed. Silicon oxide forms a lithium-silicon alloy. The 2nd, 5th, and 10th cycle charge-discharge curves of the lithium-air battery without metal lithium prepared in Example 3 of the present invention are shown in Figure 4. The lithium-silicon alloy is used as the negative electrode, and the carbon nanotubes are used as the negative electrode. The catalyst can be charged and discharged normally with a capacity of 0.18mAh cm ^-2 in oxygen, and the charge overpotential is small.

Example 4

A silicon oxide material is used as the negative electrode, and the carbon-supported Ru catalyst is used as the positive electrode catalyst. The manufacturing method of a lithium-air battery without metal lithium is as follows:

(1) prepare slurry by mixing silicon oxide, conductive agent and binder, coat on copper foil, and obtain battery negative electrode part after vacuum drying;

(2) In an anhydrous and oxygen-free environment, fully mix lithium nitride, carbon-supported Ru catalyst, conductive agent, and binder, and take the mixture and press it on the nickel foam to form a positive electrode part;

(3) In an anhydrous and oxygen-free environment, encapsulate the above-prepared positive electrode, separator and negative electrode in sequence, and drop an electrolyte solution.

So far, the lithium-air battery without metal lithium is completed.

Example 5

A silicon oxide material is used as the negative electrode, and the carbon _- supported RuO catalyst is used as the positive electrode catalyst. The steps of a method for manufacturing a lithium-air battery without metal lithium are as follows:

(1) prepare slurry by mixing silicon oxide, conductive agent and binder, coat on copper foil, and obtain battery negative electrode part after vacuum drying;

(2) in an anhydrous and oxygen-free environment, fully mix lithium nitride, carbon _- supported RuO catalyst, conductive agent, and binder, and take the mixture and press it on the foamed nickel to form a positive electrode part;

(3) In an anhydrous and oxygen-free environment, encapsulate the above-prepared positive electrode, separator and negative electrode in sequence, and drop an electrolyte solution.

So far, the lithium-air battery without metal lithium is completed.

In summary, the present invention provides a method for manufacturing a lithium-air battery without metal lithium and a lithium-air battery manufactured by using the method, wherein a silicon-based material is used as the negative electrode, which avoids the low coulombic efficiency and safety of metal lithium. Low, lithium dendrite problem. The lithium-air battery uses lithium nitride as the lithium source, realizes the in-situ electrochemical lithium intercalation of the silicon-based negative electrode through one-time assembly of the lithium-air battery, and the vacancies generated by the decomposition of lithium nitride can effectively store the discharge products of the lithium-air battery. The preparation method of the metal-free lithium-air battery is simple to operate and easy to realize industrial application.

Specific embodiments of the present invention have been described above. It should be understood that the present invention is not limited to the above-mentioned specific embodiments, and those skilled in the art can make various variations or modifications within the scope of the claims, which do not affect the essential content of the present invention.

Claims (8)

1. a preparation method of lithium-air battery, is characterized in that, comprises the steps: Prepare battery negative electrode and battery positive electrode respectively; In an anhydrous and oxygen-free environment, the battery positive electrode, the separator and the battery negative electrode are sequentially packaged, and an electrolyte is added dropwise to obtain the lithium-air battery; The preparation method of the battery negative electrode is: After mixing the silicon-based negative electrode material, the conductive agent and the binder, coating on the negative electrode current collector, and drying to obtain the battery negative electrode; The preparation method of the battery positive electrode is: In an anhydrous and oxygen-free environment, the lithium nitride, the catalyst, the conductive agent and the binder are mixed uniformly, and then pressed on the positive electrode current collector to obtain the positive electrode of the battery; After the lithium nitride is decomposed, nitrogen and lithium ions are generated. The nitrogen is released through the air electrode, and the lithium ions pass through the electrolyte to the negative electrode and react with silicon to form a lithium-silicon alloy; The lithium-air battery uses lithium nitride as a lithium source, realizes the in-situ electrochemical lithium intercalation of the silicon-based negative electrode through one-time assembly of the lithium-air battery, and the vacancies generated by the decomposition of the lithium nitride are used to store the discharge products of the lithium-air battery. 2 . The method for preparing a lithium-air battery according to claim 1 , wherein the material of the positive electrode current collector is nickel foam or carbon paper. 3 . 3. The method for preparing a lithium-air battery according to claim 1, wherein the catalyst is carbon nanotubes, Pt, Ru, Pd, Ag, Au, RuO ₂ , MnO ₂ , Co ₃ O ₄ , Fe One or more of ₃ O ₄ . 4. The method for preparing a lithium-air battery according to claim 1, wherein the binder is PTFE. 5 . The method for preparing a lithium-air battery according to claim 1 , wherein the negative electrode current collector is copper foil. 6 . 6. The preparation method of a lithium-air battery according to claim 1, wherein the silicon-based negative electrode material is selected from the group consisting of nano-silicon powder, micro-silicon powder, silicon/carbon composite material, oxysilicon oxide, oxysilicon oxide/silicon oxide One or more of carbon composite materials. 7. The method for preparing a lithium-air battery according to claim 1, wherein the electrolyte comprises a lithium salt and a solvent, and the lithium salt is selected from LiNO ₃ , LiPF ₆ , LiTFSI, LiFSI, LiClO ₄ , LiCF One or more of ₃ SO ₃ , the solvent is selected from ethylene glycol dimethyl ether, diethylene glycol dimethyl ether, triethylene glycol dimethyl ether, tetraethylene glycol dimethyl ether, dimethyl ether One or more of sulfoxide and N,N-dimethylformamide. 8. A lithium-air battery prepared by the method of claim 1.

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