CN114824241A - Device and method for carrying out liquid-phase pre-lithiation treatment on silicon monoxide negative electrode material - Google Patents

Abstract

The invention discloses a device and a method for carrying out liquid-phase pre-lithiation treatment on a silicon monoxide negative electrode material, wherein the device comprises a solvent kettle for dissolving a lithium source in an organic solvent, a mixing kettle for mixing the silicon monoxide negative electrode material and the lithium source, and a solvent recovery kettle for recovering the organic solvent; the device is used for carrying out liquid-phase pre-lithiation treatment on the silicon oxide negative electrode material, the potential safety hazard problem caused by volatilization of the organic solvent in the liquid-phase method pretreatment process can be effectively solved, the organic solvent can be recycled, the production cost can be obviously reduced, and the device has good economic benefit and industrial application prospect. In addition, the organic solvent selected by the invention is a high-boiling point inert solvent which does not react with lithium metal, so that the lithium metal keeps 0 valence and has strong reducibility, and the high-boiling point inert solvent only plays a role in heat conduction and lithium metal dispersion, so that the lithium metal is melted and dispersed in the solvent into fine particles and can fully react with the silicon monoxide negative electrode material.

Description

A device and method for liquid-phase pre-lithiation treatment of silicon oxide negative electrode material

technical field

The invention belongs to the technical field of lithium ion batteries, and in particular relates to a device and a method for performing liquid-phase pre-lithiation treatment on a silicon oxide negative electrode material.

Background technique

Traditional graphite anodes can no longer meet the needs of higher energy density in cell design. Si oxide anodes have high specific capacity and are considered to be the most promising new-generation anode materials, but they also have some defects and cannot be applied on a large scale. . When lithium is inserted into the silicon oxide negative electrode, the expansion reaches 200%, and the material is easily pulverized and fails during the cycle. When lithium is inserted for the first time, a large amount of irreversible lithium silicate is formed, resulting in a low first effect and poor conductivity of the material itself.

In order to improve the first Coulomb efficiency, it can be pre-lithiated, and the strong reducibility of metal lithium can be combined with the active oxygen in SiO to generate more reversible silicon. However, lithium metal is more active and easily reacts with oxygen and water in the air, and the production process is strict. At present, the methods for pre-lithiation of SiO/C anode materials are mainly divided into three types: gas phase method, solid phase method and liquid phase method. , the requirements for the reaction device are very high; the reaction energy barrier between the solid-phase method lithium source and SiO/C is high, and high temperature conditions are required, which is easy to cause the Si grain size to grow too large; the liquid-phase method needs to dissolve the lithium source in an organic solvent , and then mixed with the negative electrode material. Compared with the gas phase method and the solid phase method, the processing temperature of the liquid phase method is relatively low, and it is easy to realize industrial production.

But the existing liquid phase method has the following deficiencies: (1) Lithium salt is mostly selected as the lithium source, and the lithium salt is dissolved in an organic solvent to obtain a lithium-containing solvent; Reaction to obtain a lithium-containing solvent; its shortcoming is that in the obtained lithium-containing solvent, lithium shows +1 valence and has no reducibility; (2) the organic solvents used in the prior art are volatile and mostly have certain toxicity, so in the operation process The operator has certain security risks.

SUMMARY OF THE INVENTION

The purpose of the present invention is to provide a device and method for liquid-phase pre-lithiation treatment of silicon oxide negative electrode material, so as to solve the problem that the reduction of lithium reducibility in the process of using liquid-phase method to pretreat silicon oxide material in the prior art At the same time, the device can provide a good oxygen-free and water-free environment to ensure the smooth progress of the pre-lithiation treatment.

In order to solve the deficiencies in the existing technology.

To achieve the above object, the technical scheme adopted in the present invention is:

A device for performing liquid-phase pre-lithiation treatment on a silicon oxide negative electrode material, comprising a solvent kettle for dissolving a lithium source in an organic solvent, a mixture for mixing the silicon oxide negative electrode material and a lithium source A kettle and a solvent recovery kettle for recovering organic solvents; the top of the mixing kettle has a feeding port and a solvent volatilization outlet, and the bottom of the mixing kettle has a discharging port; the discharging port of the solvent kettle and the mixing The feeding port of the material kettle is connected through the first pipeline; the solvent volatilization outlet of the mixing kettle is connected with the feeding port of the solvent recovery kettle through the second pipeline; a first heating device is installed on the outside of the solvent kettle, and the A second heating device is installed outside the mixing kettle, and a first stirring paddle is also installed in the mixing kettle. Preferably, both the first heating device and the second heating device are heating coils.

As a preferred technical solution, a second stirring paddle is installed in the solvent kettle, and the function of the second stirring paddle is to enable the lithium source in the solvent kettle to be uniformly dispersed in the organic solvent.

As a preferred technical solution, a first locking valve is installed on the first pipeline, and a second locking valve is installed on the second pipeline. The opening or closing state of the first pipeline and the second pipeline can be adjusted respectively through the first locking valve and the second locking valve, thereby adjusting the connection state between the solvent kettle, the mixing kettle and the solvent recovery kettle. Further preferably, a spray head is installed at the end of the second pipe located in the mixing kettle. Through the nozzle, the organic solvent dissolved in the lithium source can be sprayed into the mixing kettle in the form of small droplets, so that the materials in the mixing kettle can be fully contacted, so that the materials are mixed more uniformly.

As a preferred technical solution, a condenser tube is installed on the outer wall of the solvent recovery kettle. By transporting cooling water into the condenser tube, the temperature of the solvent recovery kettle can be lowered quickly, and the cooling speed of the organic solvent can be increased.

As a preferred technical solution, the upper parts of the solvent kettle and the mixing kettle are provided with air holes, and the air holes are connected with the vacuum pumping equipment or the inert gas pipeline, and the solvent kettle and the mixing kettle can be guaranteed to be in a vacuum state through the air holes. or inert gas protection state.

The present invention also provides a method for performing liquid-phase pre-lithiation treatment on the silicon oxide negative electrode material, which is completed by using the above-mentioned device, and includes the following steps:

A lithium source and an organic solvent are added into the solvent kettle, and the temperature of the organic solvent is higher than the melting point of the lithium source by heating by the first heating device, and the lithium source is dispersed in the organic solvent to obtain an organic solvent containing the lithium source;

The silicon oxide negative electrode material is added into the mixing kettle, and the organic solvent containing the lithium source is transported into the mixing kettle through the first pipeline, and under the action of the first stirring paddle, the lithium source and the silicon oxide negative electrode material are made Mix evenly to obtain the mixed material;

By heating by the second heating device, the organic solvent is volatilized into the solvent recovery kettle for recovery, and the mixture is obtained by discharging from the discharge port at the bottom of the mixing kettle;

The mixed material is placed in a protective atmosphere for calcination treatment to complete the pre-lithiation treatment to obtain the final product.

As a preferred technical solution, the organic solvent is a high-boiling inert solvent, the boiling point of the organic solvent is higher than the melting point of the lithium source, and the organic solvent does not chemically react with the lithium source; the organic solvent is a diformate (boiling point 196°C), ethyl benzoate (boiling point 212°C), 1,1,3-trimethylcyclohexenone (boiling point 213°C), N-methylpyrrolidone (boiling point 202°C), diphenyl ether (boiling point 259°C) at least one. The lithium source is a metal lithium element, which is a lithium foil, a lithium bar or a lithium ingot. Further, the temperature of the calcination treatment is 750-850°C.

Compared with the prior art, the beneficial effects of the present invention are:

The device provided by the invention firstly dissolves the lithium source in the organic solvent in the solvent kettle, then completes the mixing treatment of the lithium source and the silicon oxide negative electrode material in the mixing kettle, and finally recycles the organic solvent into the organic solvent recovery kettle , to achieve the recovery of organic solvents. The invention can effectively solve the problem of potential safety hazards caused by the volatilization of the organic solvent in the pretreatment process of the liquid phase method, can realize the recovery and reuse of the organic solvent, can significantly reduce the production cost, and has good economic benefits.

The device can realize the pre-lithiation process of the silicon oxide negative electrode material under the liquid phase condition. Compared with the solid phase method and the gas phase method, the processing temperature is lower, and the required equipment is simple in structure, and can realize industrial production.

The organic solvent selected in the present invention is a high-boiling point inert solvent, which does not react with lithium metal, keeps lithium metal at 0, and has strong reducibility. It is melted and dispersed into fine particles, which can fully react with the silicon oxide negative electrode material; in addition, the ratio of lithium metal to organic solvent in the present invention can be adjusted arbitrarily, the lithium doping amount can be adjusted according to the actual process needs, and the operation is simple.

Description of drawings

1 is a schematic structural diagram of a device provided by the present invention for performing liquid-phase pre-lithiation treatment on a silicon oxide negative electrode material;

Fig. 2 is the first-week charge-discharge curve diagram of the CR2032 type button battery made of the materials obtained in Example 1 and Comparative Example 1;

Reference signs: 1-solvent kettle, 2-mixing kettle, 3-solvent recovery kettle, 4-first pipeline, 5-second pipeline, 6-first heating device, 7-second heating device, 8-th One stirring paddle, 9-second stirring paddle, 10-first locking valve, 11-second locking valve, 12-spray head, 13-condensing pipe.

Detailed ways

The present invention will be further described below with reference to the embodiments and the accompanying drawings, so that those skilled in the art can better understand the present invention and implement it, but the embodiments are not intended to limit the present invention.

It should be noted that in the present invention, "connection", "installation", etc. all mean that the two parts connected to each other are fixed together, generally by welding, screws, etc., for those of ordinary skill in the art , the specific meanings of the above terms in the present invention can be understood according to specific situations. The "first" and "second" mentioned in the present invention do not represent a specific quantity and order, but are only used for the distinction of names. It should be understood that the orientation or positional relationship indicated by the terms "top", "bottom", "inner", "outer", etc. is based on the orientation or positional relationship shown in the accompanying drawings, and is only for the convenience of describing the present invention and simplifying the description , rather than indicating or implying that the device or element referred to must have a particular orientation, be constructed and operate in a particular orientation, and therefore should not be construed as a limitation of the present invention.

Referring to Fig. 1, a device for performing liquid-phase pre-lithiation treatment on a silicon oxide negative electrode material, including a solvent kettle 1 for dissolving a lithium source in an organic solvent, a solvent kettle 1 for dissolving a silicon oxide negative electrode material and a lithium source The mixing kettle 2 for mixing and the solvent recovery kettle 3 for recovering the organic solvent; the top of the mixing kettle has a feeding port and a solvent volatilization outlet, and the bottom of the mixing kettle has a discharging port; the discharging port of the solvent kettle and the The feeding port of the mixing kettle is connected through the first pipeline 4; the solvent volatilization outlet of the mixing kettle is connected with the feeding opening of the solvent recovery kettle through the second pipeline 5; the first heating device 6 is installed outside the solvent kettle 1; A second heating device 7 is installed outside the mixing kettle 2, and a first stirring paddle 8 is also installed in the mixing kettle 2. Further, in order to enable the lithium source in the solvent kettle 1 to be uniformly dispersed in the organic solvent, a second stirring paddle 9 is installed in the solvent kettle 1 . In order to speed up the condensation speed of the organic solvent recovered in the solvent recovery kettle 3, a condenser tube 13 is installed on the outer wall of the solvent recovery kettle 3, and the temperature of the solvent recovery kettle 3 can be lowered quickly by transporting cooling water into the condensation tube 13. Further, the upper part of the kettle wall of the solvent kettle 1 and the mixing kettle 2 is provided with air holes (not shown in the figure), and the air holes are communicated with the vacuuming equipment or the inert gas pipeline, and the solvent kettle and the mixing kettle can be ensured through the air holes. In a vacuum state or an inert gas protection state; both the first heating device 6 and the second heating device 7 are heating coils.

In a preferred embodiment, a first locking valve 10 is installed on the first pipeline 4 , and a second locking valve 11 is installed on the second pipeline 5 . The opening or closing state of the first pipeline 4 and the second pipeline 5 can be adjusted respectively through the first locking valve 10 and the second locking valve 11 , thereby adjusting the distance between the solvent kettle 1 , the mixing kettle 2 and the solvent recovery kettle 3 . Connection Status. Further preferably, a nozzle 12 is installed at the end of the second pipeline 5 in the mixing kettle, and through the nozzle 12, the organic solvent dissolved with the lithium source can be sprayed into the mixing kettle in the form of small droplets, so that the mixing kettle can be sprayed. The inner materials can be fully contacted, so that the materials are mixed more uniformly.

Utilize this device to carry out liquid phase pre-lithiation treatment to silicon oxide negative electrode material, and the method is shown in the following examples:

Example 1

Get 2kg SiO (D50=6um) and add in the mixing kettle 2, open the first stirring paddle 8, open the second heating device 7 to heat, keep the temperature at 190 ° C, and store in vacuum, the first locking valve 10 and the second locking Valve 11 remains closed. Add diphenyl ether and 105g of lithium ingot to the solvent kettle 1, quickly vacuumize, turn on the first heating device 6 for heating, and turn on the second stirring paddle 9 to stir, heat to 190 ° C, keep the temperature for 3 hours, and open the first locking valve. 10. Lithium in the molten state is dispersed in diphenyl ether, and then through the first pipeline 4, under the action of the nozzle 12, the diphenyl ether dispersed with lithium is evenly touched and sprinkled on the SiO precursor in the mixing kettle 2, and the solvent is After the material in the kettle 1 is touched and sprinkled, the first locking valve 10 is closed. After the first stirring paddle stirring paddle 8 is continuously stirred at 190 ° C for 3 hours, the temperature in the mixing kettle is raised to 300 ° C, the stirring is maintained, the second locking valve 11 is opened, and the diphenyl ether is recovered through the second pipeline 5 to the solvent recovery In the kettle 3, the condensation pipe 13 keeps the temperature down. After the diphenyl ether is completely volatilized, take out the mixed material in which the lithium source and the silicon oxide negative electrode material are mixed uniformly from the mixing kettle 2. Finally, the mixture was put into a rotary furnace and calcined at 800°C under nitrogen protection for 5h to complete the pre-lithiation process.

Comparative Example 1

Compared with Example 1, in Comparative Example 1, only diphenyl ether was added in solvent kettle 1, and lithium ingot was not added, and other processes were the same as those in Example 1.

The materials prepared in Example 1 and Comparative Example 1 were made into CR2032 type button batteries, and a charge-discharge test was carried out. The test results are shown in Table 1 and FIG. 2 .

Table 1 Charge and discharge test data of CR2032 type button battery made from the materials prepared in Example 1 and Comparative Example 1

DC-0.005V(mAh/g) CC-1.5V(mAh/g) 1st.C.E(1.5V,%) Example 1 1550.79 1326.57 85.54% Comparative Example 1 2114.40 1628.07 77.00%

Remarks: In Table 1, DC-0.005 means charging to 0.005V, CC-1.5V means discharging to 1.5V, 1stC.E means the first coulomb efficiency, the calculation formula is: 1st.C.E=CC/DC

It can be seen from Table 1 and Figure 2 that the first coulombic efficiency of the CR2032 coin cell made of the material prepared in Example 1 is 85.54%, which is compared with 77.00% in Comparative Example 1. The first Coulomb efficiency of the material is effectively improved. Compared with Comparative Example 1, the capacity of the battery made of the pre-lithium-treated material is slightly reduced, but in practical application, since the silicon negative electrode is used in combination with graphite, the overall capacity can be adjusted by adjusting its addition amount. Compared with the capacity loss, the effect of improving the first coulombic efficiency is greater.

Obviously, the described embodiments are some, but not all, embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

Claims (10)

1. An apparatus for performing liquid phase prelithiation treatment on a silicon oxide negative electrode material, characterized in that: the lithium ion battery cathode material mixing device comprises a solvent kettle for dissolving a lithium source in an organic solvent, a mixing kettle for mixing a silicon monoxide cathode material and the lithium source, and a solvent recovery kettle for recovering the organic solvent; the top of the mixing kettle is provided with a feed inlet and a solvent volatilization outlet, and the bottom of the mixing kettle is provided with a discharge outlet; the discharge hole of the solvent kettle is connected with the feed inlet of the mixing kettle; and a solvent volatilization outlet of the mixing kettle is connected with a feed inlet of the solvent recovery kettle.

2. An apparatus for liquid phase prelithiation of a silicon oxide anode material according to claim 1, wherein: the solvent kettle is provided with a first heating device; the discharge hole of the solvent kettle is connected with the feed inlet of the mixing kettle through a first pipeline; a solvent volatilization outlet of the mixing kettle is connected with a feed inlet of the solvent recovery kettle through a second pipeline; the mixing kettle is provided with a second heating device and a first stirring paddle; and a second stirring paddle is arranged in the solvent kettle.

3. An apparatus for liquid phase prelithiation of a silicon oxide anode material according to claim 2, wherein: the first heating device and the second heating device are both heating coils.

4. An apparatus for liquid phase prelithiation of a silicon oxide anode material according to claim 2, wherein: and a first locking valve is arranged on the first pipeline, and a second locking valve is arranged on the second pipeline.

5. The apparatus of claim 4, wherein the apparatus is configured to perform liquid phase prelithiation of the silicon oxide negative electrode material, and wherein: and the end part of the second pipeline positioned in the mixing kettle is provided with a spray head.

6. The apparatus of claim 4, wherein the apparatus is configured to perform liquid phase prelithiation of the silicon oxide negative electrode material, and wherein: and a condensing pipe is arranged on the outer wall of the solvent recovery kettle.

7. An apparatus for liquid phase prelithiation of a silicon oxide anode material according to claim 1, wherein: and the upper parts of the kettle walls of the solvent kettle and the mixing kettle are provided with air holes, and the air holes are communicated with vacuum-pumping equipment or an inert gas pipeline.

8. A method for liquid phase prelithiation of a silicon oxide negative electrode material, characterized by: this is accomplished with the device according to any of claims 2 to 7, comprising the steps of:

adding a lithium source and an organic solvent into a solvent kettle, heating by a first heating device to enable the temperature of the organic solvent to be higher than the melting point of the lithium source, and dispersing the lithium source in the organic solvent to obtain the organic solvent containing the lithium source;

adding a silicon monoxide negative electrode material into a mixing kettle, conveying an organic solvent containing a lithium source into the mixing kettle through a first pipeline, and uniformly mixing the lithium source and the silicon monoxide negative electrode material under the action of a first stirring paddle to obtain a mixed material;

heating by a second heating device to volatilize the organic solvent into the solvent recovery kettle for recovery, and discharging from a discharge hole at the bottom of the mixing kettle to obtain a mixed material;

and (3) placing the mixed material in a protective atmosphere environment for calcination treatment to complete the pre-lithiation treatment, thereby obtaining a final product.

9. The method for liquid phase prelithiation of a silicon oxide anode material according to claim 8, wherein: the organic solvent is a high-boiling point inert solvent, the boiling point of the high-boiling point inert solvent is higher than the melting point of the lithium source, and the organic solvent does not react with the lithium source chemically; the organic solvent is at least one of diformate, ethyl benzoate, 1, 3-trimethylcyclohexenone, N-methyl pyrrolidone and diphenyl ether; the lithium source is a simple substance of metallic lithium, and is lithium foil, a lithium strip or a lithium ingot.

10. The method for liquid phase prelithiation of a silicon oxide anode material according to claim 8, wherein: the temperature of the calcination treatment is 750-850 ℃.

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