CN116247188A - Core-shell structure antimony@porous carbon anode material for sodium ion battery and preparation method and application thereof - Google Patents

Abstract

The application discloses a core-shell structure antimony@porous carbon anode material for a sodium ion battery and a preparation method and application thereof, and belongs to the technical field of battery material processing. The composite material comprises nano metal antimony particles and a porous carbon material, wherein the nano metal antimony particles are wrapped in a porous carbon structure. The negative electrode composite material solves the problems that the conductivity of an antimony-based material is poor, and the volume expansion of the material is serious in the sodium intercalation process when the antimony-based material is used as a negative electrode material of a sodium ion battery, so that particles are broken and pulverized in the battery circulation process and fall off from a current collector. The negative electrode composite material has the advantages of high specific capacity, good multiplying power performance and stable cycle performance, and is low in raw material cost, simple in preparation process, low in energy consumption, safe, environment-friendly and easy to realize industrial production.

Description

Core-shell structure antimony@porous carbon anode material for sodium ion battery and preparation method and application thereof

Technical Field

The application relates to a battery anode material and preparation and application thereof, in particular to a core-shell structure nano antimony particle@porous carbon compound and preparation and application thereof, and belongs to the technical field of new energy secondary battery material processing.

Background

The lithium ion battery has the outstanding advantages of high energy density, high power density, long cycle life and the like, and is widely applied to the fields of consumer electronics markets, electric automobiles and the like, and the global lithium ion battery market scale in 2021 is nearly 4000 hundred million yuan. However, the reserve of the lithium element in the crust is only about 0.002%, the reserve of the lithium resource for exploitation is less, the resource supply is tension, and the popularization and the application of the lithium ion battery are severely limited. Sodium has a rich reserve (approximately 2.74%) in the crust of the earth, with significant resource advantages. In addition, compared with a lithium ion battery, the sodium ion battery has the advantages of lower cost, higher safety, better low-temperature performance and the like, is recognized as the first choice for replacing the lithium ion battery, and is expected to be an ideal choice for the advanced energy storage technology of a large-scale energy storage power station, a small-sized electric automobile and the like.

Graphite is the most dominant and most commercially available negative electrode material for lithium ion batteries, but sodium ions are difficult to intercalate into the graphite layer due to the larger radius of sodium ions than lithium ions. Therefore, research and development of a negative electrode material with high capacity, low cost and excellent cycle performance is a main goal and challenge of research and development of sodium ion batteries at present.

The negative electrode material of the sodium ion battery can be classified into intercalation reaction (carbonaceous material and titanium-based oxide), conversion reaction (transition metal oxide/sulfide) and alloying reaction according to the reaction mechanism; the anode material for alloying reaction generally has the characteristic of high theoretical capacity, such as tin (847 mAh/g) and antimony (660 mAh/g). However, the conductivity of the alloy anode material is generally poor, and the volume change is obvious in the sodium ion intercalation and deintercalation process, so that the structure of the electrode material is damaged, the poor rate performance and the cycling stability are caused, and the practical application of the alloy anode material is restricted.

Therefore, it is particularly important how to improve the conductivity of the alloy material and obtain a stable electrode structure, and to obtain the alloy type sodium ion battery anode material with high specific capacity, long cycle life and high rate performance.

Disclosure of Invention

The invention aims to solve the problems that the alloy type sodium ion battery cathode material in the prior art is poor in conductivity, the volume is rapidly expanded in the sodium embedding process, particles are crushed and pulverized in the circulating process, and the particles fall off from a current collector. A composite material, particularly a composite material in which nano metallic antimony particles are wrapped in a porous carbon structure, is provided.

The negative electrode material is favorable for the infiltration of electrolyte, effectively shortens the transmission distance of sodium ions and electrons in an electrode, relieves the volume expansion effect of the material in the charge and discharge process, and has the advantages of high specific capacity, good rate performance and stable cycle performance.

In order to achieve the above object, the present invention provides the following technical solutions:

a composite material comprising nano-metal particles and a porous carbon material, the nano-metal particles being encapsulated in a porous carbon material structure; the nano-metal particles are antimony particles.

The composite material adopts the antimony metal nano particles to wrap the porous carbon structure, the porous carbon is utilized to improve the conductivity, the electrochemical performance of the alloy sodium storage material is improved when the composite material is used as a negative electrode material of a sodium ion battery, meanwhile, the metal nano particles have good independence, and the volume change is not excessively expanded to be crushed in the sodium ion embedding process.

Further, the particle size of the nano metal particles is 2-200 nm. Preferably, the particle size of the nano-metal particles is 10 to 120nm. For example, it may be 20nm, 40nm, 60nm, 80nm, 100nm, and various particle size ranges obtained by their arrangement and combination.

Further, the mass ratio of the nano metal particles to the porous carbon is 4-2:1-3. The nano metal particles have higher quality and higher specific capacity. Preferably, the mass ratio of the nano metal particles to the porous carbon is 3.5-2.2: 1 to 3.

The invention also aims to provide a preparation method of the composite material, wherein the particle size of the nano metal particles is controlled through a proper preparation process, and the wrapping effect of the porous carbon material on the nano metal particles is achieved, so that the high-efficiency and high-quality combination of the nano metal particles is realized, and the excellent conductivity, capacity stability and high-rate characteristics are exerted.

A method of preparing a composite material comprising the steps of:

step 1), uniformly mixing a carbon source, a salt template and an active agent to form mixed powder A;

dissolving antimony salt in an anhydrous organic solvent to prepare a solution B;

step 2), adding the mixed powder A into the solution B under magnetic stirring to perform precipitation reaction, continuously stirring for 2-12 hours after feeding is completed, filtering and drying a reaction product, and collecting the reaction product to obtain solid powder C;

and 3) carrying out high-temperature heat treatment on the solid powder C in an inert atmosphere, washing with deionized water, and drying to obtain the composite material.

According to the method for preparing the composite material, a porous structure and nano metal particle loading are molded by a template method, metal salt is fully reacted into a carbon source through full stirring and precipitation reaction, and the porous structure and nano metal particle loading are uniformly mixed after subsequent high-temperature treatment under an inert atmosphere, so that the metal nano particles have good dispersing effect and high activity. The method has the advantages of simple preparation process, low energy consumption, safety, environmental protection, high product yield, easy industrial amplification, commercialization and the like.

Further, in step 1), the carbon source is a biomass carbon source. After the biomass carbon source is subjected to high-temperature heat treatment, a porous carbon structure with good structural stability can be better formed, so that the porous carbon is ensured to have good coating on the metal nano particles, and the conductive property is better. Preferably, the biomass carbon source is at least one selected from carboxymethyl cellulose, carboxymethyl starch, alginic acid, sodium carboxymethyl cellulose, sodium carboxymethyl starch and sodium alginate.

Further, in the step 1), the salt template is at least one selected from sodium chloride, sodium carbonate, sodium nitrate, sodium sulfate and sodium metasilicate. The sodium salt or potassium salt is used as a salt template to form a porous structure, and the salt can be recycled, so that the production efficiency is high and the cost is low.

Further, the active agent in the step 1) is at least one selected from potassium hydroxide, potassium chloride, potassium carbonate, potassium nitrate, potassium acetate and zinc chloride. The active agent has the effects of promoting the formation of a microporous structure and closed pores in the porous carbon material, and promoting the formation of the porous structure and improving the platform capacity of the sodium ion battery.

Further, in the step 1), the mass ratio of the biomass carbon source, the salt template and the active agent is 1-4:4-8:8-12. A plurality of experimental researches show that the porous carbon structure has high porosity and good coating effect on metal nano particles when the dosage ratio of the salt template to the active agent is controlled within the range, and the porous carbon structure has more excellent performance such as activity, capacity and the like when used as a negative electrode of a sodium ion battery.

Further, in the step 1), the method of mixing the biomass carbon source, the salt template and the active agent is one of a physical grinding method or an aqueous solution mixing and freeze drying method. Preferably, the aqueous solution is mixed and then lyophilized to obtain a more uniform mixture. The mixing uniformity of the aqueous solution is higher, the biomass carbon source forms a continuous network structure in the freeze drying process, the porous carbon structure strength is higher after high-temperature treatment, and the cycle performance of the cathode material is better.

Further, the anhydrous organic solvent in the step 1) is at least one of methanol, ethanol, propanol, isopropanol, diethyl ether and acetone. The polar organic solvent is selected to dissolve the antimony salt, so that the dispersing effect is good, the metal nano particles formed by subsequent heat treatment are more uniform, and the electrochemical performance of the composite material is better.

Further, the antimony salt in step 1) is a soluble antimony salt. Preferably, the antimony salt is at least one of antimony sulfate, antimony nitrate, antimony chloride, and antimony acetate.

Further, the mass percentage content of the antimony salt in the solution B in the step 1) is 1wt.% to 5wt.%.

Further, the drying method in the step 2) is at least one of vacuum drying and freeze drying.

Further, in the step 3), the solid powder C is heated to 400-1000 ℃ at a heating rate of 1-5 ℃/min, and is subjected to high-temperature heat treatment in an inert atmosphere and is subjected to constant-temperature treatment for 1-5 h. Preferably, the biomass carbon source is gradually carbonized to form porous carbon after heating to 500-800 ℃ for heat treatment, and the mutual combination effect of the biomass carbon source and the metal nano particles is better.

Further, in the step 3), the inert atmosphere is at least one of nitrogen and argon.

Further, the nano metal particles in the composite material obtained in step 3) are coated in porous carbon.

Preferably, the particle size of the nano metal particles is 2-200 nm. Preferably, the particle size is 10 to 120nm. For example, 20nm, 40nm, 60nm, 80nm, 100nm may be mentioned.

Further, the composite material obtained in the step 3) comprises nano metal particles and porous carbon, and the mass ratio of the nano metal particles to the porous carbon is 4-2:1-3.

According to another aspect of the application, a negative electrode plate is provided, and the negative electrode material is applied to a sodium ion battery, so that the material performance advantage of the negative electrode plate is exerted by combining the characteristics of the sodium ion battery.

The negative electrode plate contains the composite material or the composite material prepared by the method. Namely, the composite material is used for manufacturing a negative electrode material.

Further, the negative electrode plate is prepared by coating a mixed slurry containing the composite material or the negative electrode material prepared by the method, a conductive agent and a binder on a metal foil, preferably an aluminum foil, performing high-temperature treatment and slicing.

Further, in the mixed slurry, the mass ratio of the composite material, the conductive agent and the binder is 7-9: 0.5 to 1.5:0.5 to 1.5.

Specifically, a composite material (namely composite material powder of active material porous carbon coated nano metal antimony particles), a conductive agent (SuperP) and a binder (sodium carboxymethylcellulose CMC) are uniformly ground in a mass ratio of 8:1:1, a small amount of deionized water is added to prepare slurry, a film coater is used for coating the slurry on copper foil or aluminum foil, the copper foil or aluminum foil is then subjected to heat preservation for 24 hours at 100 ℃ in a vacuum drying oven, and then a dried electrode slice is cut into an electrode slice with the diameter of 12mm by a slicer.

According to still another aspect of the present application, there is provided a sodium-ion half cell or a sodium-ion cell, including the above-described negative electrode sheet.

Compared with the prior art, the invention has the beneficial effects that:

the composite material is prepared by carrying out precipitation reaction on antimony salt and biomass, adding a mixed salt template and an active agent for pore-forming, carbonizing at high temperature, and cleaning with deionized water to remove the salt template and the active agent, thereby forming the antimony@porous carbon composite material with a structure that nano antimony particles are coated by porous carbon. The advantages of high theoretical capacity of the alloy anode material and excellent conductivity and cycle stability of the hard carbon material are combined, and the problems of poor conductivity and large volume expansion effect of the alloy material such as antimony as the anode material are solved.

According to the composite material disclosed by the invention, the nano antimony metal particles are coated in the porous carbon material, so that the conductivity of the antimony particles can be increased, the transmission distance of ions and electrons in an electrode can be effectively shortened by a porous structure, and the volume expansion effect of the material in the charge and discharge process can be effectively relieved, so that the battery negative electrode composite material has the advantages of high specific capacity, good multiplying power performance and stable cycle performance.

The preparation method of the composite material can be used for generating the negative electrode composite material of the sodium ion battery in one step, and has the advantages of simple preparation process, low energy consumption, safety, high efficiency, safety, environmental protection and easy realization of industrial production.

The composite material is applied to sodium ion batteries/sodium ion half batteries, can fully exert the high specific capacity advantage characteristic of metal negative electrode materials, has good conductivity and excellent discharge rate property, and has important significance for commercial application of sodium ion batteries.

Drawings

Fig. 1 is an XRD pattern of the antimony @ porous carbon composite material of example 1.

FIG. 2 is a scanning electron microscope image I of the antimony@porous carbon composite material of example 1.

Fig. 3 is an adsorption and desorption graph of the antimony @ porous carbon composite material of example 1.

FIG. 4 is a scanning electron microscope image two (enlarged view) of the antimony@porous carbon composite material of example 1.

FIG. 5 is a transmission electron microscopy image of the antimony@porous carbon composite material of example 1.

FIG. 6 is a graph of the cycle performance of the antimony@porous carbon composite material of example 1.

Detailed Description

The present invention will be described in further detail with reference to test examples and specific embodiments. It should not be construed that the scope of the above subject matter of the present invention is limited to the following embodiments, and all techniques realized based on the present invention are within the scope of the present invention.

Example 1

Preparation of composite sample No. 1

3g of sodium chloride, 1g of sodium carbonate and 11g of potassium carbonate are dissolved in 100mL of deionized water, stirred at room temperature, added with 2g of sodium carboxymethyl cellulose after all of the sodium chloride, continuously stirred for 1h, freeze-dried and ground after drying to form mixed powder A. 2.02g of antimony chloride was added to 100mL of absolute ethanol to prepare a solution B (2.5% strength). Adding the mixed powder A into the solution B under magnetic stirring to perform precipitation reaction, continuously stirring for 4 hours, filtering and drying a reaction product, and collecting the reaction product to obtain solid powder C; and (3) placing the solid powder C in a tube furnace, heating to 500 ℃ at a heating rate of 2 ℃/min under nitrogen atmosphere, performing heat treatment for 2 hours, cooling to room temperature, finally washing with deionized water for multiple times, performing suction filtration, and drying to obtain a final product of the antimony@porous carbon composite material, which is marked as a sample No. 1.

Examples 2 to 8

Preparation of composite sample No. 2-8

Examples 2 to 8 were conducted as in example 1 except that the types and amounts of the raw materials to be added, the heat treatment conditions and the like were changed. And the samples obtained in the corresponding examples were numbered. See in particular table 1.

Table 1 samples of antimony@porous carbon composite materials prepared under different conditions

Example 9

X-ray diffraction analysis was performed on samples 1# to 8# respectively.

Representative of sample # 1, fig. 1 is an XRD pattern of sample # 1, and it can be seen from fig. 1 that the (002) plane peaks of amorphous carbon occur at diffraction angles of 21.7 °, and that the peaks occurring at diffraction angles of 28.67 °, 40.06 °, 41.90 ° correspond to the (012), (104), and (110) planes of antimony (PDF # 85-1322), respectively, indicating successful recombination of antimony with carbon material.

The X-ray diffraction pattern of samples # 2 to #8 is similar to that of sample # 1.

Example 10

And respectively carrying out field emission scanning electron microscope analysis on the 1# to 8# samples.

With sample # 1 as a representative, fig. 2 is a Field Emission Scanning Electron Microscope (FESEM) of sample # 1, and it can be seen that the prepared composite material has a three-dimensional porous microstructure and a smoother surface. Fig. 3 is an adsorption and desorption graph of sample # 1, further demonstrating the porous structure of the composite.

Fig. 4 and 5 are a field emission scanning electron microscope image and a transmission electron microscope image of a sample # 1 which are further amplified, and it can be seen that nano particles with the particle size of 10-40nm are coated in the middle of the three-dimensional porous carbon, which indicates that the metal antimony nano particles are well coated in the carbon material.

The field emission scanning electron microscope analysis patterns of the samples # 2 to #8 are similar to those of the sample # 1.

Example 11

Performance testing

Sample No. 1 powder prepared in example 1, a conductive agent (acetylene black) and a binder (CMC) were uniformly ground in a mass ratio of 8:1:1 (total 100 g), and then 1ml of deionized water was added to prepare a slurry, which was applied to an aluminum foil by a film coater, and then was kept at 100℃for 24 hours in a vacuum drying oven. And cutting the dried electrode slice into electrode slices with the diameter of 12mm by using a slicer, finally, taking metal sodium as a counter electrode in a glove box, and adopting a mixed solution of 1mol/L sodium perchlorate in ethylene carbonate, diethyl carbonate and dimethyl carbonate, wherein the volume ratio of the ethylene carbonate to the diethyl carbonate to the dimethyl carbonate is 1:1:1, and the membrane adopts Whatman GF/D to assemble the sodium ion button cell.

And performing performance test on the button cell.

FIG. 4 is a graph showing the cycle performance of sample # 1 at a current density of 0.05A/g, with the initial discharge capacity and charge capacity of 645mAh/g and 344mAh/g, respectively, and the capacity after 100 cycles at a current density of 0.05A/g was maintained at a reversible specific capacity of 349 mAh/g.

The samples 2-8# prepared in examples 2-8 above were prepared in the same manner to prepare sodium button cells, and were subjected to a cycle of 100 cycles of testing at a current density of 0.05A/g, as shown in the following Table, in which the capacity units were mAh/g.

Examples	First discharge capacity	Charge capacity	Cycle	100 circle capacity
					1#	645	344	349
2#	532	378	353
				3#	680	367	371
4#	576	392	368
				5#	822	411	383
6#	541	325	319
				7#	480	296	291
8#	667	354	358

Experimental results show that the composite material prepared in the examples 2-8 has good cycling stability as a negative electrode material of a sodium ion battery, and the capacity after cycling for 100 circles can be maintained at the reversible specific capacity of 291-383mAh/g, so that the composite material has good cycling characteristics.

Wherein, examples 6-7 use higher heat treatment temperature, the carbonization degree of the porous carbon is higher, the metal antimony has certain volatilization loss, and the reversible specific capacity is lower. Examples 2 and 8 had a heat treatment temperature of 500℃and a slightly longer treatment time, and the carbonization degree of the biomass carbon source was low, and the conductivity of the composite material was low.

Example 12

4g of sodium chloride, 2g of sodium carbonate and 10g of potassium carbonate are dissolved in 100mL of deionized water, stirred at room temperature, 3g of sodium alginate is added after the sodium chloride, the sodium carbonate and the potassium carbonate are completely dissolved, stirring is continued for 1h, freeze drying is carried out, and grinding is carried out after drying, so as to form mixed powder A. 2.44g of antimony chloride was added to 100mL of absolute ethanol to prepare a solution B (3% strength). Adding the mixed powder A into the solution B under magnetic stirring to perform precipitation reaction, continuously stirring for 4 hours, filtering and drying a reaction product, and collecting the reaction product to obtain solid powder C; and (3) placing the solid powder C in a tube furnace, heating to 550 ℃ at a heating rate of 2.5 ℃/min under nitrogen atmosphere, performing heat treatment for 3 hours, cooling to room temperature, finally washing with deionized water for multiple times, performing suction filtration, and drying to obtain a final product of the antimony@porous carbon composite material, which is marked as a 12# sample.

Examples 13 to 16

Examples 13-16 were conducted as in example 12 except that the types and amounts of the raw materials added were changed and the samples obtained in the respective examples were numbered. See in particular table 2.

Table 2 samples of antimony@porous carbon composite materials prepared under different conditions

Examples	Type and mass ratio of biomass carbon source, salt template and active agent	Antimony salt concentration wt%	Heat treatment conditions
				12 #	Sodium alginate: sodium chloride, sodium carbonate, potassium carbonate = 3:4:2:10	3％	2.5℃/min，500℃，3h
13 #	Sodium alginate: sodium chloride, sodium carbonate, potassium carbonate = 3:4:2:10	3％	2.5℃/min，600℃，3h
				14 #	Sodium alginate: sodium chloride, sodium carbonate, potassium carbonate = 3:4:2:10	3％	2.5℃/min，650℃，3h
15 #	SeaweedSodium acid: sodium chloride, sodium carbonate, potassium carbonate = 3:4:2:10	3％	2.5℃/min，550℃，3h
				16 #	Sodium alginate: sodium chloride, sodium carbonate, potassium carbonate = 3:4:2:10	3％	2.5℃/min，630℃，3h

Samples prepared in examples 12-16 above were prepared in the same manner as in example 11 to prepare sodium button cells, and the samples were subjected to 100 cycles of testing at a current density of 0.05A/g, and the results are shown in the following Table, in mAh/g.

Examples	First discharge capacity	Charge capacity	Cycle	100 circle capacity
					12#	620	366	348
13#	532	335	317
				14#	456	293	292
15#	513	397	383
				16#	476	306	292

Experimental results show that the composite material prepared in the examples 12-16 has good cycling stability as a negative electrode material of a sodium ion battery, and the capacity can maintain higher reversible specific capacity after cycling for 100 circles, so that the composite material has good cycling stability. The temperature in the heat treatment condition is optimal in the range of 500-600 ℃, so that good reversible cycle stability can be realized, because the carbonization degree of a biomass carbon source is considered in the heat treatment process, the nanoparticle state of antimony in the heat treatment process is considered, and the volatilization loss of antimony or the aggregation growth of antimony nanoparticles is caused by too high temperature. In order to achieve good composite molding quality, the heat treatment temperature should not exceed 600 ℃. Meanwhile, the temperature rising speed is controlled to be 1-2.5 ℃/min.

The foregoing description is only a few examples of the present application and is not intended to limit the present application in any way, and although the present application is disclosed in the preferred examples, it is not intended to limit the present application, and any person skilled in the art may make some changes or modifications to the disclosed technology without departing from the scope of the technical solution of the present application, and the technical solution is equivalent to the equivalent embodiments.

Claims (10)

1. A composite material, comprising nano metal particles and a porous carbon material, wherein the nano metal particles are wrapped in the porous carbon material structure; the nano-metal particles are antimony particles.

2. A composite material according to claim 1, wherein the nano-metal particles have a particle size of 2 to 200 nm; preferably, the nano-metal particles have a particle size of 10-120 a nm a.

3. The composite material according to claim 1, wherein the mass ratio of the nano metal particles to the porous carbon is 4-2:1-3.

4. A method of preparing a composite material according to any one of claims 1 to 3, comprising the steps of:

step 1), uniformly mixing a carbon source, a salt template and an active agent to form mixed powder A;

dissolving antimony salt in an anhydrous organic solvent to prepare a solution B;

step 2), adding the mixed powder A into the solution B under magnetic stirring, performing precipitation reaction, continuously stirring for 2-12 hours after feeding is completed, filtering and drying a reaction product, and collecting the reaction product to obtain solid powder C;

and 3) carrying out high-temperature heat treatment on the solid powder C in an inert atmosphere, washing with deionized water, and drying to obtain the composite material.

5. The method of producing a composite material according to claim 4, wherein in step 1), the carbon source is a biomass carbon source;

the antimony salt is a soluble antimony salt.

6. The method for preparing a composite material according to claim 5, wherein the biomass carbon source is at least one selected from carboxymethyl cellulose, carboxymethyl starch, alginic acid, sodium carboxymethyl cellulose, sodium carboxymethyl starch, and sodium alginate;

the salt template is at least one selected from sodium chloride, sodium carbonate, sodium nitrate, sodium sulfate and sodium metasilicate;

the active agent is at least one selected from potassium hydroxide, potassium chloride, potassium carbonate, potassium acetate, potassium nitrate and zinc chloride;

the anhydrous organic solvent is at least one of methanol, ethanol, propanol, isopropanol, diethyl ether and acetone;

the antimony salt is at least one of antimony sulfate, antimony nitrate, antimony chloride and antimony acetate.

7. The method for preparing the composite material according to claim 4, wherein the mass ratio of the biomass carbon source, the salt template and the active agent in the step 1) is 1-4:4-8:8-12.

8. The method for producing a composite material according to claim 4, wherein the mass content of the antimony salt in the solution B in step 1) is 1wt.% to 5wt.%;

in the step 3), the solid powder C is heated to 400-1000 ℃ at a heating rate of 1-5 ℃/min, is subjected to high-temperature heat treatment in an inert atmosphere, and is subjected to constant-temperature treatment of 1-5 h.

9. A negative electrode sheet comprising the composite material of any one of claims 1-3.

10. A sodium ion half cell or sodium ion battery comprising the negative electrode sheet of claim 9.

Images