Patent Application
20250118764
The present application relates to the technical field of new materials, and particularly to a complex formed by metal lithium and a network skeleton material having a highly lithiophilic modification layer, a preparation method therefor and application thereof.
Currently, the energy density of lithium ion batteries has reached the limit of the battery system thereof, and it is very urgent to seek a new battery system having a high energy density.
Metal lithium as a metal material having the smallest density has been a critical material for manufacturing lightweight alloys and metal lithium batteries. Especially in the new energy resource field, metal lithium has a potential to be an individual part, i.e., a metal lithium negative electrode, due to many advantages such as its high specific capacity (3860 mAh/g) and the most negative potential (−3.04 V vs. H/H+), and plays a decisive role in increasing the energy density of batteries. However, conventional metal lithium negative electrodes suffer from problems of volume expansion and lithium dendrites during battery cycling. One of the reasons for the breakage of lithium dendrites also resides in the breakage of dendrite roots caused by changes in electrode volume. In order to solve such problems, a general way is to prepare a metal lithium negative electrode having a three-dimensional (3D) conductive skeleton structure, so as to reduce volume expansion of the metal lithium negative electrode and reduce local current density on the electrode surface. The 3D skeleton structure can provide a reserved space for metal lithium deposition. When the metal lithium is deposited in the reserved space, the electrode will not expand. The conductivity of the 3D skeleton structure can reduce the current density on the electrode surface, and thus can effectively reduce the generation of dendrites. In this regard, the preparation of a metal lithium belt having a conductive 3D skeleton structure can effectively alleviate the expansion of the metal lithium negative electrode and reduce the dendrites.
Currently, there are two kinds of processes for combining a 3D skeleton structure with metal lithium. One of the processes is to combine the metal lithium with the 3D skeleton structure by a mechanical pressure. However, there is an obvious delamination inside the metal lithium belt prepared by such a process, and the process has some destructive effect on the skeleton structure. The other of the processes is to deposit the metal lithium onto the 3D skeleton through electro-deposition, to obtain a metal lithium belt having a 3D skeleton structure. However, such a process is inefficient, and is difficult to implement on large scale.
In conclusion, there is a need for developing a process capable of preparing on large scale a metal lithium complex having a 3D skeleton structure.
In view of the above problems, the inventors of the present application provide a complex (also referred to as a lithium carbon complex or a lithium carbon complex material) formed by metal lithium and a (3D) network skeleton material having a (highly) lithiophilic modification layer, a preparation method therefor, and application thereof. The method allows industrial production of the complex of metal lithium and (3D) network skeleton (carbon) material having a highly lithiophilic modification layer, and the metal lithium completely infiltrates into the carbon material in the complex as prepared, such that there is no delamination or void in the complex. The conductive 3D carbon skeleton structure (which itself comprises pores) in the complex can provide a reserved space for metal lithium deposition, thereby alleviating the volume expansion when used as a metal lithium negative electrode. The conductivity of the carbon skeleton structure can reduce the current density on the electrode surface, thereby reducing the generation and growth of lithium dendrites. The electrode prepared with the complex has a stable structure, facilitating the preparation of an electrode with a long cycling lifetime.
In particular, in an aspect, the present application provides a complex formed by metal lithium and a (3D) network skeleton material having a lithiophilic modification layer, the complex comprising:
In the present disclosure, the term “crystalline carbonaceous material” refers to a material in which the carbon atoms that make up this material are orderly arranged according to a certain rule (in microstructure), while the term “amorphous material” refers to a material in which the atoms are orderly arranged in a short range, but disorderly arranged in a long range (also known as a non-crystalline material).
A schematic structure of the lithium carbon complex material of the present application is shown in
In some embodiments, the porous skeleton has a porosity in a range from 15% to 85%, and a pore size in a range from 5 nanometers (nm) to 90 nm.
In some embodiments, the crystalline carbonaceous material comprises at least one selected from the group consisting of a carbon nanotube, graphene, a carbon fiber, a carbon-based metal oxide fiber, and a carbon-based covalent organic fiber.
In some embodiments, the carbon composite material is fibrous.
In some embodiments, the amorphous carbonaceous wrapping layer is a carbonized product of an organic material which is blended with the crystalline carbonaceous material, wherein the organic material is selected from the group consisting of an organic binder, an organic filler and a crosslinker, and the amorphous carbonaceous wrapping layer has a thickness in a range from 10 nm to 600 nm.
In some embodiments, the organic binder is selected from the group consisting of polyvinyl alcohol, polyvinylidene fluoride, polybutylene styrene, polystyrene, polycarboxycellulose, cyanoacrylates, polyacrylic acid, cyclodextrins, cyclic ether derivatives, polyurethanes, methacrylates, epoxy resins, vinyl acetate polymer, polyimides, organic fluoropolymers, organosiloxanes, polyethylene glycol, polyethylene, polyvinyl chloride, polypropylene, glycerin, ethylparaben and its derivatives, and monosaccharide or polysaccharide polymers.
In some embodiments, the organic filler is selected from the group consisting of plastic microparticles (such as polypropylene (PP), polyethylene terephthalate (PET), polystyrene (PS) and so on), benzoic acid, sodium benzoate, sorbic acid, potassium sorbate, calcium propionate, and dehydroacetates.
In some embodiments, the crosslinker is selected from the group consisting of macromolecular polymers of acrylic acid bonded with allyl sucrose or pentaerythritol allyl ether, benzoyl peroxide, diethylenetriamine, sodium borate hydrate, cellulose derivatives, and isothiazolinone.
In some embodiments, the lithium carbon complex material is in a belt form, and the lithium carbon belt has a thickness in a range from 1 micrometer (μm) to 1000 μm and a width in a range from 5 millimeters (mm) to 1 meter (m).
In some embodiments, the outer amorphous carbonaceous wrapping layer has a thickness in a range from 10 nm to 600 nm.
In some embodiments, the amorphous carbonaceous wrapping layer further comprises metal nanoparticles embedded in the amorphous carbonaceous wrapping layer or on a surface thereof.
In some embodiments, the metal nanoparticles have a size in a range from 5 nm to 800 nm, and are dispersedly embedded in the outer amorphous carbonaceous wrapping layer.
In another aspect, the present application provides a method for preparing the complex as described above, the method comprising:
In some embodiments, a mass ratio of the organic binder, the filler, the crosslinker and the solvent is (4-15 parts):(10-30 parts):(0.01-20 parts):(20-400 parts).
In some embodiments, a mass proportion of the crystalline carbonaceous material in the filler is in a range from 15% to 100%, such as from 15% to 99.5%.
In some embodiments, the organic binder is selected from the group consisting of polyvinyl alcohol, polyvinylidene fluoride, polybutylene styrene, polystyrene, polycarboxycellulose, cyanoacrylates, polyacrylic acid, cyclodextrins, cyclic ether derivatives, polyurethanes, methacrylates, epoxy resins, vinyl acetate polymer, polyimides, organic fluoropolymers, organosiloxanes, polyethylene glycol, polyethylene, polyvinyl chloride, polypropylene, glycerin, ethylparaben and its derivatives, and monosaccharide or polysaccharide polymers.
In some embodiments, the organic filler is selected from the group consisting of plastic microparticles (such as PP, PET, and PS), benzoic acid, sodium benzoate, sorbic acid, potassium sorbate, calcium propionate, and dehydroacetates.
In some embodiments, the inorganic filler is selected from the group consisting of metal nanoparticles, metal oxides, metal nitrides, calcium carbonate, hydrous magnesium silicate, mica, hydrated silica, and silica.
In some embodiments, the crosslinker is selected from the group consisting of macromolecular polymers of acrylic acid bonded with allyl sucrose or pentaerythritol allyl ether, benzoyl peroxide, diethylenetriamine, sodium borate hydrate, cellulose derivatives, and isothiazolinone.
In some embodiments, the solvent is selected from the group consisting of water, tetrachloroethylene, toluene, turpentine, acetone, methyl acetate, ethyl acetate, pentane, n-hexane, cyclohexane, octane, lemonile (lemon nitrile), alcohol, xylene, toluene, cyclohexanone, isopropyl alcohol, diethyl ether, propylene oxide, methyl butanone, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, acetonitrile, pyridine, phenol, and ethylenediamine.
In some embodiments, the pre-drying is performed at a temperature in a range from −200° C. to 200° C., and preferably from 20° C. to 100° C., for a period ranging from 1 to 48 hours, and preferably 2 to 8 hours.
In some embodiments, the filler in Step 1 comprises metal nanoparticles, and a mass ratio of the metal nanoparticles, the organic binder, other fillers, the crosslinker and the solvent is (0.01-20 parts):(4-15 parts):(10-30 parts):(0.01-20 parts):(20-400 parts).
In some embodiments, the porous skeleton obtained in Step 3 is a lithiophilic carbon skeleton.
In some embodiments, the heating in Step 3 is performed for 2-24 hours, and preferably 2-10 hours.
In some embodiments, in the lithium carbon complex material obtained in Step 4, a mass ratio of the porous skeleton to the metal lithium is in a range from 1:0.1 to 1:6.
In some embodiments, the lithium carbon complex material obtained may be subjected to a processing, including, for example, turning, slicing, mechanical rolling, laser cutting, extruding and so on.
In another aspect, the present application provides a metal lithium negative electrode comprising the complex as described above or a complex prepared by the method as described above.
In another aspect, the present application provides a metal lithium battery comprising the metal lithium negative electrode as described above.
The present application has at least one of the following advantages:
1. The industrial preparation of a complex of metal lithium and network skeleton material having a highly lithiophilic modification layer can be realized, and the complex as prepared is completely infiltrated, such that there is no delamination or void inside the material.
2. The conductive 3D carbon skeleton structure in the complex can provide a reserved space for metal lithium deposition, thereby alleviating the volume expansion when used as a metal lithium negative electrode.
3. The conductivity of the carbon skeleton structure can reduce the current density on the electrode surface, thereby reducing the growth of lithium dendrites.
4. The electrode prepared with the complex has a stable structure, facilitating the preparation of an electrode with a long cycling lifetime.
The present application will be illustrated below with reference to particular examples.
Polyvinyl alcohol (Aladdin Scientific Corp., Shanghai), polystyrene microspheres (Suzhou Weimai Novel Material Co. Ltd.), carbon nanotubes (Shandong Dazhan), diethylenetriamine (Shanghai Yantai Industrial Co. Ltd.), isothiazolinone (Aladdin Scientific Corp., Shanghai), and deionized water were uniformly mixed in a ratio by mass part of 6:9:9:5:5:75.
The mixture prepared was pre-dried at 85° C. for 5 hours.
The pre-dried material was placed in a crucible, and subjected to a high temperature treatment at 1000° C. under an inert atmosphere for 5 hours to obtain a carbon skeleton material.
The carbon skeleton material prepared above was contacted with molten metal lithium, and the metal lithium was impregnated into (the pores of) the carbon skeleton material. After cooling, a complex formed by metal lithium and network skeleton material having a highly lithiophilic modification layer was obtained.
The complex obtained above was tested by a scanning electron microscope to determine the binding state of the metal lithium and the carbon material, and the test results are shown in
The resulting complex was punched into sheets, and assembled into a button cell, where a metal lithium sheet was used as a counter electrode. A carbonate-based electrolyte solution and a polypropylene separator were used, where the carbonate-based electrolyte solution was a solution in which the solute was 1 mol/L LiPF6 and the solvent was a mixture of EC and EMC (in a volume ratio of 1:1).
The complex was subjected to a lithium removal experiment to determine the specific capacity of the complex, and the specific capacity measurement curve of the complex is shown in
The button cell with lithium removed was disassembled to determine the condition of the residual carbon skeleton, and the optical photograph of the disassembled button cell is shown in
Polyurethane (Aladdin Scientific Corp., Shanghai), polystyrene microspheres (Suzhou Weimai Novel Material Co. Ltd.), silver nanoparticles, carbon nanotubes (Shandong Dazhan), benzoyl peroxide (Aladdin), isothiazolinone (Aladdin Scientific Corp., Shanghai), and deionized water were uniformly mixed in a ratio by mass part of 10:8:1:9:5:5:80.
The mixture prepared was pre-dried at 65° C. for 10 hours.
The pre-dried material was placed in a crucible, and subjected to a high temperature treatment at 800° C. under an inert atmosphere for 3 hours to obtain a carbon skeleton material containing silver nanoparticles.
The carbon skeleton material prepared above was contacted with molten metal lithium, and the metal lithium was impregnated into the carbon skeleton material. After cooling, a complex formed by metal lithium and network skeleton material having a highly lithiophilic modification layer was obtained.
Polyvinyl alcohol (Aladdin Scientific Corp., Shanghai), hydrated silica (Suzhou Weimai Novel Material Co. Ltd.), carbon nanotubes (Shandong Dazhan), benzoyl peroxide (Aladdin), isothiazolinone (Aladdin Scientific Corp., Shanghai), and deionized water were uniformly mixed in a ratio by mass part of 10:12:9:5:1:55.
The mixture prepared was pre-dried at 65° C. for 10 hours.
The pre-dried material was placed in a crucible, and subjected to a high temperature treatment at 800° C. under an inert atmosphere for 6 hours to obtain a carbon skeleton material.
The carbon skeleton material prepared above was contacted with molten metal lithium, and the metal lithium was impregnated into the carbon skeleton material. After cooling, a complex formed by metal lithium and network skeleton material having a highly lithiophilic modification layer was obtained.
Polyvinyl alcohol (Aladdin Scientific Corp., Shanghai), hydrated silica (Suzhou Weimai Novel Material Co. Ltd.), carbon nanotubes (Shandong Dazhan), benzoyl peroxide (Aladdin), and p-xylene were uniformly mixed in a ratio by mass part of 10:12:9:5:55.
The mixture prepared was pre-dried at 65° C. for 10 hours.
The pre-dried material was placed in a crucible, and subjected to a high temperature treatment at 800° C. under an inert atmosphere for 6 hours to obtain a carbon skeleton material.
The carbon skeleton material prepared above was contacted with molten metal lithium, and the metal lithium was impregnated into the carbon skeleton material. After cooling, a complex formed by metal lithium and network skeleton material having a highly lithiophilic modification layer was obtained.
A carbon material having a 3D skeleton structure was placed between two layers of lithium belts with a thickness of 50 μm to form a sandwich structure, and a complex with a thickness of 180 μm formed by the carbon material and the metal lithium was prepared by rolling. The complex prepared was observed with a scanning electron microscope to determine the binding state of the 3D carbon skeleton material and the metal lithium, and the test results are shown in
The complexes in Example 1 and Comparative Example 1 above were respectively used as a working electrode for assembling a button cell, where a commercially available lithium sheet was used as a counter electrode. A carbonate-based electrolyte solution and a polypropylene separator were used, where the carbonate-based electrolyte solution was a solution in which the solute was 1 mol/L LiPF6 and the solvent was a mixture of EC and EMC (in a volume ratio of 1:1).
After the cell was assembled, a cycling performance test was carried out. The cycling performance test comprised steps of: leaving the assembled button cell stand for 12 hours, charging the cell at a constant current of 1 mA/cm2 for 1 hour, then discharging the cell at a constant current of 1 mA/cm2 for 1 hour, and recording the voltage change as a function of time during the cycling. The results for the cycling test are shown in
It can be understood that although the complex of metal lithium and network skeleton material having a highly lithiophilic modification layer and a preparation method therefor according to the present application are described in detail with particular embodiments in the examples, the above description is presented only for the purpose of satisfying legal requirements, and the present application is not limited to the particular examples. The complex of metal lithium and network skeleton material having a highly lithiophilic modification layer and the preparation method therefor can be reproduced by those skilled in the art through proper operations according to the disclosure and teaching of the specification.
Proper modifications and variations can be made on the above embodiments by those skilled in the art according to the disclosure and teaching of the specification above. Therefore, the present application is not limited to the particular embodiments as disclosed and described above, and certain modifications and variations on the present application should also fall within the protection scope of the claims of the present application. Furthermore, although some particular terms are used in the specification, those terms are only for the purpose of description, but not intended to limit the present application in any way.
| Number | Date | Country | Kind |
|---|---|---|---|
| 202111023963.X | Sep 2021 | CN | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/CN2022/114220 | 8/23/2022 | WO |
