阅读说明：本技术 一种软硬双层硫锂电池阳极的制备方法 (Preparation method of soft-hard double-layer sulfur lithium battery anode ) 是由 冯拉俊 卢曼 沈文宁 王芳芳 于 2020-03-30 设计创作，主要内容包括：本发明公开了一种软硬双层硫锂电池阳极的制备方法,首先由鸡蛋清制备多孔碳粉末,用聚四氟乙烯粘结剂将制备的多孔碳粉末拌为浆料,然后将浆料涂覆在多孔的聚丙烯膜的一侧,把有浆料的聚丙烯膜的涂覆层黏贴在原有的固体硫锂电池的阳极上,制备出两层硫锂电池阳极,原来的硫锂电池阳极为固体,而涂覆的膜阳极为塑性,实现软硬结合的双层硫锂电池阳极。本发明解决了现有技术中存在的电池的效率低、电池的寿命短的问题。(The invention discloses a preparation method of a soft and hard double-layer lithium sulfur battery anode, which comprises the steps of firstly preparing porous carbon powder from egg white, stirring the prepared porous carbon powder into slurry by using a polytetrafluoroethylene binder, then coating the slurry on one side of a porous polypropylene film, and adhering a coating layer of the polypropylene film with the slurry to an original solid lithium sulfur battery anode to prepare a two-layer lithium sulfur battery anode, wherein the original lithium sulfur battery anode is solid, and the coated film anode is plastic, so that the soft and hard combined double-layer lithium sulfur battery anode is realized. The invention solves the problems of low efficiency and short service life of the battery in the prior art.)

1. A preparation method of a soft and hard double-layer lithium sulfur battery anode is characterized in that porous carbon powder is prepared by egg white, the prepared porous carbon powder is mixed into slurry by polytetrafluoroethylene binder, then the slurry is coated on one side of a porous polypropylene film, a coating layer of the polypropylene film with the slurry is adhered to an original anode of a solid lithium sulfur battery, and a double-layer lithium sulfur battery anode with soft and hard combination is prepared.

2. The method for preparing the anode of the soft and hard double-layer sulfur lithium battery as claimed in claim 1 is implemented by the following steps:

step 1, preparing porous carbon powder: adding NaHCO into egg white₃，NaHCO₃The concentration in egg white is 0.2-0.25mol/l, stirring, standing to foam egg white, freezing, and adding N₂Calcining in a gas-protected environment to obtain a porous carbon material, and finally grinding the porous carbon material;

step 2, adding 1.5-2.0 wt% of polytetrafluoroethylene binder into the porous carbon powder prepared in the step 1, and uniformly stirring to obtain slurry;

step 3, brushing the slurry obtained in the step 2 on the surface of one side of the polypropylene net film, and then putting the polypropylene net film in a vacuum environment for a period of time to obtain the polypropylene net film with one conductive surface and the other insulating surface;

step 4, coating a polytetrafluoroethylene binder on the edge of the coated side of the polypropylene net film obtained in the step 3, and pasting a film on the surface of the original porous carbon sulfur anode of the sulfur lithium battery, wherein the insulating polypropylene film is arranged on the outer side of the anode of the sulfur lithium battery, so that the soft and hard double-layer sulfur lithium battery anode is obtained;

and 5, soaking the soft and hard double-layer lithium sulfur battery anode obtained in the step 4 in the lithium sulfur battery electrolyte, and installing the lithium sulfur battery on one side of the polypropylene film of the double-layer lithium sulfur battery anode facing to the cathode after the soft and hard double-layer lithium sulfur battery anode is saturated and adsorbs the electrolyte.

3. The method as claimed in claim 2, wherein the dead time of step 1 is controlled to be 1-1.5 hours.

4. The method for preparing the anode of the soft-hard double-layer lithium sulfur battery as claimed in claim 2, wherein the temperature for freezing the foamed egg white in the step 1 is controlled to be-10 ℃ to-15 ℃, and the freezing time is 1 hour to 1.5 hours.

5. According to the rightThe method for preparing a soft and hard double-layer lithium sulfur battery anode according to claim 2, wherein in the step 1, frozen egg white is added with N₂The calcining temperature in the atmosphere of gas protection is 650-700 ℃, and the calcining time is 40-45 min.

6. The method for preparing the anode of the soft-hard double-layer lithium sulfur battery as claimed in claim 2, wherein the porous carbon material obtained in step 1 is ground to 20-30 μm or less.

7. The method for preparing the anode of the soft-hard double-layer lithium sulfur battery as claimed in claim 2, wherein the slurry is coated on the surface of the polypropylene mesh film to a thickness of 0.2-0.4mm in the step 3.

8. The method for preparing the anode of the soft-hard double-layer lithium sulfur battery as claimed in claim 2, wherein the temperature of the vacuum environment in step 3 is 50-60 ℃, and the polypropylene mesh coated with the slurry is placed in the vacuum environment for 2-4 hours.

9. The method as claimed in claim 2, wherein the step 5 of soaking the soft and hard double-layer lithium sulfur battery anode in the lithium sulfur battery electrolyte is performed for a minimum of 3 hours.

Technical Field

The invention belongs to the technical field of batteries, and particularly relates to a preparation method of a soft and hard double-layer sulfur lithium battery anode.

Background

The sulfur lithium battery has large capacity and is environment-friendly, and is a potential commercial battery. Sulfur lithium batteries use sulfur as the anode, and because sulfur is not conductive, it is difficult to transport the lost electrons out, so composite electrodes have been used. The majority of the composite electrodes areCarbon and sulfur composites such that sulfur transports lost electrons to the carbon material, carbon material transports electrons away, but solid sulfur loses electrons to become a liquid sulfide, e.g., S-S loses electrons to become liquid L i₂S₈,Li₂S₈Continuing to lose electrons to become liquid L i₂S₆And in addition, the liquid sulfide can easily flow into the cathode of the battery, so that the sulfide which is not completely reacted can not be discharged continuously, and the current efficiency of the sulfur lithium battery is greatly reduced. For this reason, further research has been conducted to prepare the anode of the lithium sulfur battery as a porous material so that the generated liquid sulfide is held inside the pores. The method well improves the efficiency of the sulfur lithium battery, but has the new problems that the volume of sulfide generated by sulfur reaction is increased by more than 2 times, the pores of the porous carbon-sulfur battery are collapsed due to volume expansion, the anode surface of the battery is reduced, the discharging speed is reduced, in addition, the volume expansion extrudes part of sulfide generated by reaction out of the pores, and the extruded sulfide partially flows to the cathode, so the shuttle effect is technically called, the efficiency of the battery is reduced, and the service life of the battery is shortened.

Disclosure of Invention

The invention aims to provide a preparation method of a soft-hard double-layer sulfur lithium battery anode, which solves the problems of low battery efficiency and short battery life in the prior art.

According to the technical scheme, the preparation method of the soft and hard double-layer lithium sulfur battery anode comprises the steps of firstly preparing porous carbon powder from egg white, stirring the prepared porous carbon powder into slurry by using a polytetrafluoroethylene binder, then coating the slurry on one side of a porous polypropylene film, and adhering a coating layer of the polypropylene film with the slurry to an original anode of a solid lithium sulfur battery to prepare the double-layer lithium sulfur battery anode, wherein the original anode of the lithium sulfur battery is solid, and the coated anode of the lithium sulfur battery is plastic, so that the soft and hard combined double-layer lithium sulfur battery anode is realized.

The present invention is also characterized in that,

the method is implemented according to the following steps:

step 1, preparing porous carbon powder: adding NaHCO into egg white₃，NaHCO₃The concentration in egg white is 0.2-0.25mol/l, stirring, standing to foam egg white, freezing, and adding N₂Calcining in a gas-protected environment to obtain a porous carbon material, and finally grinding the porous carbon material;

step 2, adding 1.5-2.0 wt% of polytetrafluoroethylene binder into the porous carbon powder prepared in the step 1, and uniformly stirring to obtain slurry;

step 3, brushing the slurry obtained in the step 2 on the surface of one side of the polypropylene net film, and then putting the polypropylene net film in a vacuum environment for a period of time to obtain the polypropylene net film with one conductive surface and the other insulating surface;

step 4, coating a polytetrafluoroethylene binder on the edge of the coated side of the polypropylene net film obtained in the step 3, and pasting a film on the surface of the original porous carbon sulfur anode of the sulfur lithium battery, wherein the insulating polypropylene film is arranged on the outer side of the anode of the sulfur lithium battery, so that the soft and hard double-layer sulfur lithium battery anode is obtained;

and 5, soaking the soft and hard double-layer lithium sulfur battery anode obtained in the step 4 in the lithium sulfur battery electrolyte, and installing the lithium sulfur battery on one side of the polypropylene film of the double-layer lithium sulfur battery anode facing to the cathode after the soft and hard double-layer lithium sulfur battery anode is saturated and adsorbs the electrolyte.

The stagnation time in step 1 is controlled to be 1-1.5 hours.

In the step 1, the temperature for freezing the foamed egg white is controlled to be-10-15 ℃, and the freezing time is 1-1.5 hours.

Step 1 freezing egg white in the presence of N₂The calcining temperature in the atmosphere of gas protection is 650-700 ℃, and the calcining time is 40-45 min.

In the step 1, the obtained porous carbon material is ground to be less than 20-30 μm.

And 3, coating the surface of the polypropylene net film with the slurry to a thickness of 0.2-0.4 mm.

In the step 3, the temperature of the vacuum environment is 50-60 ℃, and the polypropylene net film coated with the sizing agent is placed in the vacuum environment for 2-4 hours.

And 5, soaking the anode of the soft-hard double-layer sulfur lithium battery in the electrolyte of the sulfur lithium battery for at least 3 hours.

The invention has the beneficial effects that one side of the polypropylene is coated with porous carbon powder material, the porous carbon material is prepared by egg white and contains natural elements such as N, O and the like, the addition of N improves the conductivity of the carbon material, O improves the adsorption capacity of the surface of the carbon material, so that the carbon material is easy to adsorb sulfide, the medical mask material has small filtering holes, and the pore diameter becomes smaller after the porous carbon powder is coated, so that L i can be effectively prevented₂S₈、Li₂The shuttle of S6 and other substances can only enable L i ions with smaller radius in the sulfur lithium battery to pass through, when the solid carbon sulfur battery discharges, the solid S-S discharges to produce L i in liquid phase₂S₈The volume of the solution expands, the small holes in the anode of the lithium sulfur battery are filled, part of the solution is discharged to enter the small holes, the discharged sulfide is blocked by the polypropylene film on the outer side, a crack is formed between the polypropylene film and the original porous carbon hard anode, and the discharged sulfide is still in the small holes, so that the polypropylene material has certain plasticity, and the defects that the porous material collapses, the anode interface is reduced and the discharge efficiency is lowered due to the volume expansion are effectively prevented; when sulfide flowing into the outside of the small hole is blocked by the carbon film on one side of the soft polypropylene, the carbon film has stronger adsorption capacity and adsorbs the sulfide on the surface of the film, thereby being beneficial to further discharging.

Drawings

Fig. 1 is a graph of rate performance tests performed on the soft and hard lithium sulfur battery anode of the present invention at rates of 0.05C, 0.1C, 0.2C, 0.5C, 1C, and 2C, respectively.

Detailed Description

The present invention will be described in detail below with reference to the accompanying drawings and specific embodiments.

The invention relates to a preparation method of a soft and hard double-layer lithium sulfur battery anode, which comprises the steps of firstly preparing porous carbon powder from egg white, stirring the prepared porous carbon powder into slurry by using a polytetrafluoroethylene binder, then coating the slurry on one side of a porous polypropylene film, and adhering a coating layer of the polypropylene film with the slurry to an original solid lithium sulfur battery anode to prepare a two-layer lithium sulfur battery anode.

The method is implemented according to the following steps:

step 1, preparing porous carbon powder: adding NaHCO into egg white₃，NaHCO₃The concentration in egg white is 0.2-0.25mol/l, then the mixture is stirred evenly and stagnated, the stagnation time is controlled to be 1-1.5 hours, the egg white is foamed, then the foamed egg white is frozen, the freezing temperature is controlled to be-10 to-15 ℃, the freezing time is 1-1.5 hours, and then the frozen egg white is put in the presence of N₂Calcining in a gas-protected environment at the temperature of 650-700 ℃ for 40-45min to obtain a porous carbon material, and finally grinding the porous carbon material to be less than 20-30 mu m;

step 2, adding 1.5-2.0 wt% of polytetrafluoroethylene binder into the porous carbon powder prepared in the step 1, and uniformly stirring to obtain slurry;

step 3, coating the surface of one side of the polypropylene net film with the slurry obtained in the step 2, wherein the coating thickness is 0.2-0.4mm, then placing the polypropylene net film in a vacuum environment for a period of time, the temperature of the vacuum environment is 50-60 ℃, and the polypropylene net film coated with the slurry is placed in the vacuum environment for 2-4 hours to obtain the polypropylene net film with one conductive surface and the other insulating surface;

step 4, coating a polytetrafluoroethylene binder on the edge of the coated side of the polypropylene net film obtained in the step 3, and pasting a film on the surface of the original porous carbon sulfur anode of the sulfur lithium battery, wherein the insulating polypropylene film is arranged on the outer side of the anode of the sulfur lithium battery, so that the soft and hard double-layer sulfur lithium battery anode is obtained;

and 5, soaking the soft and hard double-layer lithium sulfur battery anode obtained in the step 4 in the electrolyte of the lithium sulfur battery for at least 3 hours, and after the soft and hard double-layer lithium sulfur battery anode is saturated and adsorbs the electrolyte, installing the lithium sulfur battery on the side, facing the cathode, of the polypropylene film of the double-layer lithium sulfur battery anode.

The invention pastes a layer of polypropylene porous membrane on the surface of the original porous carbon anode, the polypropylene porous membrane is a commercially available medical mask inner side material and contains smaller gaps, one side of the membrane is coated with a layer of porous carbon, the design can lead extruded sulfide to flow between two interlayers, the medical polypropylene material is a plastic material with elasticity, thus effectively preventing the collapse of the original porous carbon material due to volume expansion, the reticular polypropylene membrane prevents sulfide from flowing to a cathode, and the shuttle process is reduced, therefore, the invention effectively improves the current efficiency of the sulfur lithium battery and the service life of the battery.