KR101407014B1 - Manufacturing method of active material for cathode - Google Patents

Abstract

The present invention relates to a negative electrode active material and a method for producing the same, comprising the steps of: (S10) preparing an intermediate phase aggregate (20) comprising lithium titanium oxide intermediate phase particles (11); Preparing a RF sol (Resorcinol-Formaldehyde sol) 21a (S20); When the intermediate phase aggregate 20 composed of the lithium titanium oxide intermediate particles 11 and the RF sol 21a are prepared, the RF particles 21a are mixed with the intermediate phase aggregate 20 composed of the lithium titanium oxide intermediate particles 11, Producing aggregate 30 (S30); (S40) of immersing the mixed aggregate (30) in acetone to replace the solvent with acetone when the mixed aggregate (30) is produced; (S50) of preparing a composite aggregate (40) composed of a lithium titanium oxide final phase particle (12) and a carbon aerogel (21) by heat treating the mixed aggregate (30) substituted with acetone to improve the electrical conductivity .

Description

[0001] The present invention relates to a manufacturing method of an active material for a cathode,

The present invention relates to a method for producing an anode active material, and more particularly, to a method for manufacturing an anode active material capable of improving the electrical conductivity by coating carbon aerogels on the surface of lithium titanium oxide final phase particles.

Carbon materials (activated carbon, carbon black, carbon aerogels, carbon nanotubes and carbon cloth) are used as supercapacitor electrode active materials such as electrical double layer capacitors (EDLC). Among these, carbon aerogels are porous materials including mesopores, and are electrode active materials used in various fields with excellent electrochemical characteristics and high specific surface area. Although there are various methods for producing carbon aerogels depending on the reactants used, the Resorcinol-Formaldehyde (RF) method, which is manufactured by using resorcinol and formaldehyde, is most commonly used and exhibits excellent physical properties have.

RF methods are produced through wet gel, drying and pyrolysis processes. Wet gels are prepared by hydrolysis and polymerization of resorcinol and formaldehyde in aqueous solution, and dried and pyrolysed to produce RF aerogels by drying to maintain the structure and size of the wet gel. Supercritical drying is used to minimize shrinkage of the wet gel during drying or pyrolysis.

The supercritical drying method is a method of suppressing shrinkage by drying the wet gel at a temperature and pressure higher than the critical point of the solvent contained in the pores of the wet gel, but a high temperature and high pressure are required, and atmospheric pressure drying method has been developed. In the atmospheric pressure drying method, the amount of the catalyst added to the starting material is decreased to increase the primary particle size of the wetting gel relatively, and the aqueous solution present as a solvent in the wetting gel is replaced by solvent with acetone having a surface tension of about 4 times lower, There is a problem that the manufacturing cost is increased due to a long manufacturing process time.

Korean Patent Laid-Open No. 2009-0118200 (Patent Document 1) relates to a method for producing a carbon aerogel and a carbon aerogel manufactured by the method. In the process for producing an RF sol as a starting material, So that the shape of the carbon aerogels is made spherical. The carbon aerogels prepared as disclosed in Patent Document 1 are graphite based materials that are mainly composed of carbon, and graphite based materials have a high ESR (Equivalent Series Resistance) and thus have low electric conductivity.

Korea Patent Publication No. 2009-0118200 (published on November 18, 2009)

Disclosure of Invention Technical Problem [8] Accordingly, the present invention has been made keeping in mind the above problems occurring in the prior art, and an object of the present invention is to provide a method of manufacturing a negative electrode active material which can improve the electrical conductivity by coating a carbon aerogel on the surface of lithium-

Another object of the present invention is to provide a method for manufacturing an anode active material capable of reducing the manufacturing process of a negative electrode active material by simultaneously preparing a lithium titanium oxide intermediate particle and a RF sol by heat treatment at the same time when a carbon aerogel is coated on the surface of the lithium titanium oxide final phase particle have.

It is still another object of the present invention to provide a method of manufacturing an anode active material capable of reducing a manufacturing cost by manufacturing a lithium titanium oxide intermediate particle and a RF sol simultaneously by heat treatment at the same time when a carbon aerogel is coated on the surface of a lithium titanium oxide final phase particle .

The negative electrode active material of the present invention is characterized in that carbon aerogels are coated on the surface of the lithium titanium oxide final phase particles.

A method for manufacturing a negative electrode active material according to the present invention comprises the steps of: preparing a median aggregate composed of lithium titanium oxide mesoporous particles; Preparing a RF sol (Resorcinol-Formaldehyde sol); Mixing a median aggregate composed of lithium titanium oxide mesophase particles and a median aggregate composed of lithium titanium oxide mesophase particles when the RF sol is prepared, and mixing the RF sol to prepare a mixed agglomerate; Immersing the mixed aggregate in acetone to replace the solvent with acetone when the mixed aggregate is prepared; And heat-treating the mixed agglomerates substituted with acetone to prepare a composite agglomerate composed of the lithium titanium oxide final phase particles and the carbon aerogels.

The anode active material of the present invention and its manufacturing method are advantageous in that the carbon airgel is coated on the surface of the lithium titanium oxide final phase particle to improve the electric conductivity. When the carbon airgel is coated on the surface of the lithium titanium oxide final phase particle, The oxide intermediate particles and the RF sol are heat-treated at the same time, thereby reducing the manufacturing process and reducing the manufacturing cost.

1 is a process flow diagram showing a method for producing a negative electrode active material of the present invention,
FIG. 2 is a process flow chart showing in detail the step of preparing the lithium titanium oxide intermediate particles shown in FIG. 1,
Fig. 3 is a process flow chart showing in detail the step of preparing the RF sol shown in Fig. 1,
FIGS. 4 to 8 are views showing the resultant product manufactured in the negative electrode active material manufacturing step shown in FIG. 1,
9 is a side view of a current collector to which the negative electrode active material of the present invention is applied.

Embodiments of the negative electrode active material of the present invention and a method of manufacturing the same will be described with reference to the accompanying drawings.

8, the anode active material of the present invention is coated with the carbon aerogels 21 on the surface of the lithium titanium oxide final phase particles 12 and the carbon aerogels 21 are coated on 80 to 95 wt% of the lithium titanium oxide final phase particles 12 To 5% by weight to 20% by weight, so as to improve the electrical conductivity. The lithium titanium oxide final phase particles 12 have a spinel structure, Li ₄ Ti ₅ O ₁₂ is used, and Li ₄ Ti ₅ O _{12 has} an average particle diameter of 60 to 400 nm. The average particle diameter of the carbon aerogel particles coated to surround the surface of the lithium titanium oxide final phase particle 12 is 10 to 100 nm.

A method for manufacturing a negative electrode active material by coating carbon aerogels 21 on the surface of the lithium titanium oxide final phase particle 12 of the present invention will be described with reference to the accompanying drawings.

As shown in FIGS. 1 to 3, a method for manufacturing an anode active material according to the present invention comprises first preparing an intermediate phase aggregate 20 (shown in FIG. 6) comprising lithium titanium oxide intermediate particles 11 (shown in FIG. 6) , A RF sol (Resorcinol-Formaldehyde sol) 21a (shown in FIG. 7) is prepared along with the preparation of the intermediate-phase aggregate 20 (S20). When the intermediate phase aggregate 20 composed of the lithium titanium oxide intermediate particles 11 and the RF sol 21a are prepared, the RF particles 21a are mixed with the intermediate phase aggregate 20 composed of the lithium titanium oxide intermediate particles 11, An agglomerate 30 (shown in Fig. 7) is prepared (S30). When the mixed aggregate 30 is produced, the mixed aggregate 30 is immersed in acetone to replace the solvent with acetone (S40). When the mixed agglomerate 30 is replaced with acetone, the mixed agglomerate 30 substituted with acetone is subjected to heat treatment to form the lithium titanium oxide final phase particles 12 (shown in FIG. 8) and the carbon aerogels 21 (shown in FIG. 8) A composite aggregate 40 (shown in FIG. 8) is prepared (S50).

The method for manufacturing the negative electrode active material of the present invention having the above-described structure will be described in more detail as follows.

Preparation of the intermediate-phase agglomerate 20 is performed by preparing a lithium carbonate powder 11a and a titanium oxide powder 11b, respectively, as shown in FIG. 2 (S11). In preparing the lithium carbonate powder 11a and the titanium oxide powder 11b, an average particle diameter of the titanium oxide powder 11b is 20 to 300 nm. Here, Li ₂ CO ₃ is used for the lithium carbonate powder 11 a, and TiO ₂ is used for the titanium oxide powder 11 b.

When the lithium carbonate powder 11a and the titanium oxide powder 11b are prepared, the lithium carbonate powder 11a and the titanium oxide powder 11b are mixed using a nano-set mill or a ball mill as shown in Figs. 2 and 4 (S12 ).

When the lithium carbonate powder 11a and the titanium oxide powder 11b are mixed, the coagulation precursor 10 is prepared using the spray drying method as shown in FIGS. 2 and 5 (S13). The spray drying method is performed at 150 to 220 ° C so that the lithium carbonate powder 11a and the titanium oxide powder 11b coagulate with each other to form a granular phase when the coagulation precursor 10 is formed.

2 and 6, when the lithium carbonate powder 11a and the titanium oxide powder 11b coagulate to form the aggregation precursor 10, the coagulation precursor 10 is heat-treated at 300 ° C to 600 ° C under atmospheric conditions to form lithium Thereby producing a median aggregate 20 comprising the titanium oxide intermediate particles 11 (S13). The lithium titanium oxide intermediate particle 11 constituting the intermediate phase aggregate 20 is Li ₂ TiO ₃ and the average particle diameter of Li ₂ TiO ₃ is 20 to 100 nm.

The production of the intermediate phase aggregate (20) is carried out at 300 to 600 ° C so that the lithium titanium oxide particles do not become the final spinel phase, so that the lithium titanium oxide particles have an intermediate phase. As described above, the lithium titanium oxide particles are produced so as to have an intermediate phase, whereby the particle growth of the lithium titanium oxide particles can be suppressed. It is possible to improve the electrical conductivity according to the suppression of the grain growth of the lithium titanium oxide particles to provide a negative electrode active material capable of high-speed charge-discharge and excellent cycle characteristics.

Formaldehyde (formaldehyde) is first prepared (S21) as shown in FIG. 3 in preparation of the intermediate phase aggregate 20 and RF sol (Resorcinol-Formaldehyde sol) 21a (shown in FIG. 7). Resorcinol and sodium carbonate (Na ₂ CO ₃ ), which are basic catalysts, are prepared in addition to the preparation of formaldehyde (S 22, S 23).

Formaldehyde, basic catalyst Na ₂ CO ₃ and resorcinol are prepared, respectively. Formaldehyde and sodium carbonate (Na ₂ CO ₃ ) are mixed in a solvent and mixed with resorcinol to prepare RF sol (S24 ). The molar ratio of formaldehyde: sodium carbonate (Na ₂ CO ₃ ) to formaldehyde, the basic catalyst sodium carbonate (Na ₂ CO ₃ ) and resorcinol is 400 to 600: 1 and the molar ratio of formaldehyde: resorcinol ratio is 2: 1, and distilled water is used as the solvent.

When the intermediate phase aggregate 20 composed of the lithium titanium oxide intermediate particles 11 and the RF sol 21a are prepared, the intermediate phase aggregate 20 composed of the lithium titanium oxide intermediate phase particles 11 as shown in FIGS. 1 and 7, The mixed aggregate 30 is prepared by mixing the sol 21a (S30). The RF sol 21a is mixed so as to be 5 to 20 wt% with respect to 80 to 95 wt% of the lithium titanium oxide intermediate particles 11 and the RF sol 21a is mixed at 80 to 90 DEG C for 48 to 50 wt% Gel for 80 hours to make RF wet gel.

When the mixed aggregate 30 is produced, the mixed aggregate 30 is immersed in acetone to replace the solvent with acetone (S40). When replacing the solvent with acetone, the mixed agglomerates are immersed in acetone at 40 to 50 DEG C for 12 to 24 hours, and immersed in fresh acetone every 3 hours to replace the solvent with acetone.

When the mixed aggregate 30 is replaced with acetone, the mixed aggregate 30 substituted with acetone as shown in FIGS. 1 and 8 is heat-treated to form a composite aggregate 40 comprising the lithium titanium oxide final phase particle 12 and the carbon aerogels 21 (S50). In the production of the composite agglomerates, the heat agglomerates are prepared by calcining the mixed agglomerates under a nitrogen atmosphere at 600 to 800 ° C for 2 to 20 hours, and the composite agglomerates 40 have an average diameter of 1 to 10 μm.

FIG. 9 shows an electrode structure of a supercapacitor to which a negative electrode active material manufactured by the method of manufacturing a negative electrode active material of the present invention is applied.

As shown in FIG. 9, the electrode structure includes a negative electrode active material 110 and a current collector 120. The negative electrode active material 110 formed on the current collector 120 is composed of a plurality of complex aggregates 40 made to have an average diameter of 1 to 10 mu m. Since the anode active material 110 is composed of the composite agglomerate 40 composed of the lithium titanium oxide final phase particles 12 and the carbon aerogels 21, the carbon electrogels 21 coated on the surface of the lithium titanium oxide final phase particle 12 A pore 22 is generated in the pore 22. The ions are stored in the pore 22 and the carbon aerogels 21 function as a conductive agent to improve electrical conductivity.

 As described above, the negative electrode active material of the present invention and the method of manufacturing the same are characterized in that the carbon airgel is coated on the surface of the lithium titanium oxide final phase particle so that the carbon airgel acts as a conductive agent and ions are stored in the pores formed between the carbon aerogels, When the carbon aerogels are coated on the surface of the lithium titanium oxide final phase particles, the lithium titanium oxide intermediate particles and the RF sol are simultaneously heat-treated to reduce the manufacturing process, thereby reducing the manufacturing cost.

The negative electrode active material of the present invention and its manufacturing method can be applied to a secondary battery or a super capacitor manufacturing industry which is applied to a large capacity energy storage device such as a notebook computer, a mobile electronic device, an electric car, and a smart grid.

10: Coagulation precursor 11: Lithium titanium oxide intermediate particle
11a: Lithium carbonate powder 11b: Titanium oxide powder
12: lithium titanium oxide final phase particle 20: intermediate phase coagulum
21a: RF sol 21: carbon aerogels
30: mixed aggregate 40: complex aggregate

Claims (13)

delete delete delete delete Preparing intermediate intermediate aggregates comprising lithium titanium oxide intermediate particles;
Preparing a RF sol (Resorcinol-Formaldehyde sol);
Mixing a median aggregate composed of lithium titanium oxide mesophase particles and a median aggregate composed of lithium titanium oxide mesophase particles when the RF sol is prepared, and mixing the RF sol to prepare a mixed agglomerate;
Immersing the mixed aggregate in acetone to replace the solvent with acetone when the mixed aggregate is prepared;
And heat-treating the mixed agglomerates substituted with acetone to produce a composite agglomerate comprising lithium titanium oxide final phase particles and carbon aerogels. 6. The method of claim 5, wherein preparing the lithium titanium oxide intermediate particles comprises: preparing a lithium carbonate powder and a titanium oxide powder, respectively;
Mixing the lithium carbonate powder and the titanium oxide powder using a nano-set mill or a ball mill;
Preparing a coagulation precursor using the spray drying method when the lithium carbonate powder and the titanium oxide powder are mixed;
And heat treating the coagulation precursor at 300 ° C to 600 ° C in an atmospheric environment to produce a median aggregate of lithium titanium oxide mesophase particles. 7. The method of claim 6, wherein the titanium oxide powder has an average particle diameter of 20 to 300 nm in the step of preparing the lithium carbonate powder and the titanium oxide powder, respectively. [7] The method of claim 6, wherein the spray drying method is performed at 150 to 220 [deg.] C in the step of preparing the coagulation precursor using the spray drying method. The method of claim 6, wherein the lithium titanium oxide particles in the intermediate step of producing the intermediate agglomerates and Li ₂ TiO _3, method of producing the cathode active material with an average particle diameter of the Li ₂ TiO ₃ is characterized in that from 20 to 100nm. 6. The method of claim 5, wherein preparing the RF sol comprises: preparing formaldehyde;
Preparing resorcinol;
Preparing sodium carbonate (Na ₂ CO ₃ ) as a basic catalyst;
Mixing the formaldehyde and sodium carbonate (Na ₂ CO ₃ ) in a solvent and mixing the resorcinol to prepare an RF sol,
In the preparation of the RF sol, the molar ratio of formaldehyde: sodium carbonate (Na ₂ CO ₃ ) is 400 to 600: 1 and the molar ratio of formaldehyde: resorcinol is 2: 1. Wherein the solvent is distilled water. 6. The method of claim 5, wherein in the step of preparing the mixed aggregate, the RF sol is mixed so as to be 5 to 20 wt% based on 80 to 95 wt% of the lithium titanium oxide intermediate particles, and the RF sol is stirred at 80 to 90 DEG C for 48 to 80 hours Wherein the gel is formed into an RF wet gel. 6. The method of claim 5, wherein the step of replacing the solvent with acetone comprises immersing the mixed agglomerate in acetone at 40 to 50 DEG C for 12 to 24 hours, and immersing it in fresh acetone every 3 hours to replace the solvent with acetone Wherein the negative electrode active material is produced by the method. 6. The method of claim 5, wherein in the step of preparing the composite aggregate, the mixed aggregate is calcined at 600 to 800 DEG C for 2 to 20 hours in a nitrogen atmosphere.

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