Lithium ion battery is with many shells of cobaltosic oxide hollow ball negative material and preparation method thereof
Technical field
The invention belongs to technical field of function materials, specifically, the present invention relates to a kind of cobaltosic oxide (Co that is applied to lithium ion battery
3O
4) many shells hollow ball negative material and preparation method thereof.
Background technology
Lithium ion battery has the operating voltage height, volume is little, quality is light, energy density is high, memory-less effect, pollution-free, advantage such as self discharge is little, have extended cycle life, and has obtained research widely and development fast.Be widely used in numerous areas such as electronic product, electric automobile, Aero-Space and national defense and military at present, and developed into one of optimal battery power of 21 century.
2000, P.Poizot etc. have reported nano-scale 3d transition metal oxide (MO, M is Co, Ni, Fe, Cu) have outstanding electrochemical properties (document: Poizot P as the negative material of lithium ion battery, Laruelle S, Grugeon S, Nature, 2000,407,496-499).Studies show that the transition metal oxide negative material has very high storage lithium capacity, its theoretical specific capacity is 2~3 times of conventional carbon negative material, is up-and-coming lithium ion battery electrode material.
The maximum transition metal oxide of research is the Co oxide at present, and this is the theoretical specific capacitance height because of the Co oxide, than being easier to the high Co oxide cathode material (document: F.Zhan of the capacity of preparing, B.Geng, Y.Guo, Chem.Eur.J.2009,15,6169-6174).The subject matter that this class material exists is: the actual specific capacitance is lower, and cycle life is short.The micron many shell metallic oxide hollow ball of receiving can obviously improve this problem, and its reason is that its internal cavities can be adjusted the embedding of lithium ion and the variation of the electrode volume deviating to cause, is conducive to the stable of electrode structure, improves the cycle life of battery.
At present, adopt hard template method or soft template method, synthesized various many shells oxide hollow balls.But these methods only are applicable to the synthetic of a certain specific oxide mostly.Recently, inventor place seminar has reported a kind of universal method (document: X.Lai, J.Li of synthetic many shells oxide hollow ball, B.A.Korgel, Z.Dong, Z.Li, F.Su, J.Du, D.Wang, Angew.Chem.Int.Ed.2011,50,2738-2741), and the concentration by control calcination condition and metal ion, can control the shell number of hollow ball.But, because the radius of hydration cobalt ions is bigger, use existing method, be difficult to prepare productive rate height, many shells Co that purity is good
3O
4Hollow ball.
Summary of the invention
Deficiency at existing lithium ion battery negative material exists the object of the present invention is to provide a kind of Co that is applied to lithium ion battery
3O
4Many shells hollow ball negative material and preparation method thereof.
Technical scheme of the present invention is as follows:
Lithium ion battery Co
3O
4The preparation method of many shells hollow ball negative material is:
The preparation of A, carbon ball template
Be aqueous sucrose solution about 130min of hydro-thermal reaction in 200 ℃ autoclave of 1.5M with concentration, cooling back suction filtration naturally, and after deionized water and ethanol repeatedly wash, product is put into the dry 12~24h of 80 ℃ of baking ovens, the about 3 μ m of gained carbon bulb diameter;
B, many shells Co
3O
4The preparation of hollow ball
The carbon ball template is dispersed in the cobalt salt solution, solvent adopts the mixture of water, ethanol or ethanol and water, cobalt salt solution concentration is 1~3M, suction filtration after stirring 4~12h under 20~50 ℃, spend deionised water 3~5 times, put into the dry 12~24h of 80 ℃ of baking ovens, place Muffle furnace to calcine the gained pressed powder, obtain many shells Co after the cooling naturally
3O
4Hollow ball;
C, many shells Co
3O
4Hollow ball is as the preparation of the lithium ion battery of negative material
With many shells Co
3O
4Hollow ball, conductive agent acetylene black, binding agent Kynoar (PVDF), be dispersed in and form slurry in the N-methyl pyrrolidone (NMP), slurry is evenly coated on the Copper Foil, putting into 80~140 ℃ of baking ovens dries, the above-mentioned electrode slice that coats active material is cut into sequin, and standby at 80 ℃ of following vacuumize 12~24h, what test battery adopted is conventional button cell, be to electrode with the lithium paper tinsel, LiPF
6Organic solution be electrolyte, in glove box, be assembled.
Co of the present invention
3O
4The preparation method of many shells hollow ball negative material, the cobalt salt of carbon ball absorption can adopt Co (Ac)
24H
2O, CoCl
24H
2O or Co (NO
3)
26H
2O; When solvent adopted the mixture of ethanol and water, the volume ratio of ethanol and water was 1:(0~0.333); Calcination condition is: the heating rate with 0.5~5 ℃/min rises to 500 ℃, calcining at constant temperature 1~3h.
Preparation method of the present invention, the proportioning of electrode active material slurry is: many shells Co
3O
4The weight ratio of hollow ball, acetylene black and PVDF is 1:(0.125~0.6): (0.125~0.4); Active material is spread upon on the Copper Foil, and generally after smearing 4~6 times repeatedly, about 30~80 μ m of coating layer thickness are cut into the sequin that diameter is 1.6cm then; Lithium salts in the electrolyte is LiPF
6, concentration is 1M, and solvent is the mixture of ethylene carbonate (EC) and diethyl carbonate (DEC), and the two weight ratio is 1:1.
Preparation method of the present invention, be increased to 3:1 by the volume ratio with etoh solvent in the cobalt salt solution and water, to reduce the size of hydration cobalt ions, temperature with cobalt salt solution is increased to 30 ℃ simultaneously, to increase the diffusion rate of hydration cobalt ions, make the carbon ball template can adsorb more cobalt ions, and make cobalt ions can be deep into carbon ball inside, prepared three shell Co
3O
4Hollow ball, it is of a size of 864.1nm ± 21.4nm.At three shell Co
3O
4On the basis of hollow ball synthesis condition, by the carbon ball template is carried out acidification, be about to 1g carbon ball template and be dispersed in the hydrochloric acid solution that 30ml concentration is 0.5~2M, stirred 1~2 day, to strengthen the carbon ball to the adsorption capacity of cobalt ions, prepared four shell Co
3O
4Hollow ball, it is of a size of 870.2nm ± 21.8nm.
Therefore, it is template that the present invention adopts the carbon ball of green non-pollution, and by following three kinds of enhancements: (1) increases the ratio of ethanol in the solvent, to reduce the size of hydration cobalt ions; (2) improve the cobalt salt solution temperature, to increase the diffusion rate of cobalt ions; (3) the carbon ball template is carried out acidification, to increase specific area and the porosity of carbon ball; Successfully regulate and control the adsorbance of cobalt ions on the carbon ball template, and in the diffusion depth of carbon ball template inside, finally realized the purpose of control hollow ball size, shell thickness and shell number, obtained the Co of one, two, three and four shells
3O
4Hollow ball.Easy, the good reproducibility of this preparation method, products therefrom uniform particle diameter, productive rate height, purity (content of certain shell hollow ball in certain shell hollow ball product) height.Each sample statistics surpasses 100 hollow balls, single, double, three and four shell Co
3O
4The purity of hollow ball is respectively 80%, 70%, 75%, 75%, for finally with Co
3O
4Many shells hollow ball prepares dynamical lithium ion battery and lays a good foundation as negative material.
The Co for preparing with the method for the invention
3O
4The lithium ion battery that many shells hollow ball negative material assembles is 50~2000mA/g in current density, and voltage is under the charge-discharge test condition of 0.05~3.0V, and its specific discharge capacity that circulates after 30 times is than commercial Co under the same terms
3O
4The specific discharge capacity of negative material is high 1.76~4.62 times; Wherein with Co
3O
4Three shell hollow balls are that the specific discharge capacity of lithium ion battery of negative material assembling is up to 1615.8mAh/g.
Many shells Co of the present invention's preparation
3O
4Hollow ball is as the negative material of lithium ion battery, with traditional be that the lithium ion battery of negative pole is compared with material with carbon elements such as graphite, not only specific capacity has improved 2~3 times, and cycle performance also is greatly improved.With commercial Co
3O
4The powder negative material is compared, many shells Co of the present invention's preparation
3O
4Hollow ball has bigger specific area, and the contact area of electrode and electrolyte increases, thereby effectively reduces the transmission range of lithium ion and electronics, is conducive to heavy-current discharge; And unique many shells cavity structure, have more storage lithium site on the one hand, be conducive to the raising of specific capacity, internal cavities is conducive to adjust repeatedly the electrode volume that causes in the charge and discharge process and the variation of structure on the other hand, is conducive to improve the cycle performance of battery.Therefore its specific capacitance, cycle performance and large current discharging capability all are higher than commercial Co
3O
4Powder.
Description of drawings
Fig. 1 is three shell Co of embodiment 1 preparation
3O
4The transmission electron microscope photo of hollow ball.
Fig. 2 is four shell Co of embodiment 4 preparations
3O
4The transmission electron microscope photo of hollow ball.
Fig. 3 be embodiment 1,2,3,4 the preparation with three shells, monoshell layer, bivalve layer and four shell Co
3O
4Hollow ball is the cycle performance curve (curve a, d, b, c) of the lithium ion battery of negative material, and embodiment 5 preparation with commercial Co
3O
4Cycle performance curve (curve e) comparison diagram for the lithium ion battery of negative material.Measuring current density is 50mA/g, and voltage is 0.05~3.0V, after 30 circulations, and monoshell layer, bivalve layer, three shells, four shell Co
3O
4Hollow ball and commercial Co
3O
4Specific discharge capacity be respectively 792.7mAh/g, 1303mAh/g, 1615.8mAh/g, 1011.5mAh/g and 287.5mAh/g.
Fig. 4 be embodiment 6 preparation with three shell Co
3O
4Hollow ball be the lithium ion battery of negative material under different current densities, the change curve of specific discharge capacity.
Embodiment
Below in conjunction with specific embodiment the present invention is described in more detail and illustrates, but those skilled in the art will recognize that these embodiment only are used for illustrating the present invention, it does not constitute any restriction to scope of the present invention.
Embodiment 1
Be aqueous sucrose solution about 130min of hydro-thermal reaction in 200 ℃ autoclave of 1.5M with concentration, cooling back suction filtration naturally, and after repeatedly washing through water and ethanol, product is put into 80 ℃ of dry 24h of baking oven, the about 3 μ m of gained carbon bulb diameter.
The carbon ball template is dispersed in 1M Co (Ac)
24H
2In the O solution, wherein the ratio of water and ethanol is 1:3 in the solvent.Under 30 ℃, suction filtration behind the stirring 6h spends deionised water 3 times, puts into 80 ℃ of dry 12h of baking oven, and the gained pressed powder is placed Muffle furnace, is warmed up to 500 ℃ with 2 ℃/min, and calcining at constant temperature 1h obtains three shell Co after the cooling naturally
3O
4Hollow ball, the shell size is about 864.1nm ± 21.4nm.
Be the three shell Co of 5:3:2 with weight ratio
3O
4Hollow ball, acetylene black and PVDF are dispersed in and form slurry in the nmp solvent.Slurry is evenly coated on the Copper Foil, and after smearing 4 times repeatedly, the about 30 μ m of the thickness of coating place it in after coating in 80 ℃ of baking ovens and dry.It is 1.6 centimetres sequin that the electrode slice that coats active material is cut into diameter, standby at 80 ℃ of following vacuumize 12h.
What test battery adopted is conventional button cell, is to electrode with the lithium paper tinsel, with 1M LiPF
6Organic solution be electrolyte, solvent is ethylene carbonate (EC) and the mixture of diethyl carbonate (DEC), the two weight ratio is 1:1, is assembled in glove box.Current constant mode is adopted in the cycle performance test, and current density is 50mA/g, and voltage is 0.05~3.0V.After the charge and discharge cycles 30 times, the discharge specific capacitance is 1615.8mAhg
-1
Embodiment 2
Be aqueous sucrose solution about 130min of hydro-thermal reaction in 200 ℃ autoclave of 1.5M with concentration, cooling back suction filtration naturally, and after repeatedly washing through water and ethanol, product is put into 80 ℃ of dry 12h of baking oven, the about 3 μ m of gained carbon bulb diameter.
The carbon ball template is dispersed in 3M Co (NO
3)
26H
2In the O solution, solvent is deionized water.Under 50 ℃, suction filtration behind the stirring 4h spends deionised water 5 times, puts into 80 ℃ of dry 24h of baking oven, and the gained pressed powder is placed Muffle furnace, is warmed up to 500 ℃ with 0.5 ℃/min, and calcining at constant temperature 3h obtains monoshell layer Co after the cooling naturally
3O
4Hollow ball, the shell size is about 859.1nm ± 22.4nm.
Be the monoshell layer Co of 8:1:1 with weight ratio
3O
4Hollow ball, acetylene black and PVDF are dispersed in and form slurry in the nmp solvent.Slurry is evenly coated on the Copper Foil, and after smearing 6 times repeatedly, the about 80 μ m of the thickness of coating place it in after coating in 140 ℃ of baking ovens and dry.It is 1.6 centimetres sequin that the electrode slice that coats active material is cut into diameter, standby at 80 ℃ of following vacuumize 12h.
What test battery adopted is conventional button cell, is to electrode with the lithium paper tinsel, with 1M LiPF
6Organic solution be electrolyte, solvent is the mixture of EC and DEC, the two weight ratio is 1:1, is assembled in glove box.Current constant mode is adopted in the cycle performance test, and current density is 50mA/g, and voltage is 0.05~3.0V.After the charge and discharge cycles 30 times, the discharge specific capacitance is 792.7mAh g
-1
Embodiment 3
Be aqueous sucrose solution about 130min of hydro-thermal reaction in 200 ℃ autoclave of 1.5M with concentration, cooling back suction filtration naturally, and after repeatedly washing through water and ethanol, product is put into 80 ℃ of dry 12h of baking oven, the about 3 μ m of gained carbon bulb diameter.
The carbon ball template is dispersed in 3M CoCl
24H
2In the O solution, solvent is ethanol, under 20 ℃, stirs suction filtration behind the 12h, spend deionised water 3 times, put into 80 ℃ of dry 12h of baking oven, the gained pressed powder is placed Muffle furnace, be warmed up to 500 ℃ with 5 ℃/min, calcining at constant temperature 1h obtains bivalve layer Co after the cooling naturally
3O
4Hollow ball, the shell size is about 858.6nm ± 21.3nm.
Be the bivalve layer Co of 7:2:1 with weight ratio
3O
4Hollow ball, acetylene black and PVDF are dispersed in and form slurry in the nmp solvent.Slurry is evenly coated on the Copper Foil, and after smearing 5 times repeatedly, the about 60 μ m of the thickness of coating place it in after coating in 140 ℃ of baking ovens and dry.It is 1.6 centimetres sequin that the electrode slice that coats active material is cut into diameter, standby at 80 ℃ of following vacuumize 24h.
What test battery adopted is conventional button cell, is to electrode with the lithium paper tinsel, with 1M LiPF
6Organic solution be electrolyte, solvent is the mixture of EC and DEC, the two weight ratio is 1:1, is assembled in glove box.Current constant mode is adopted in the cycle performance test, and current density is 50mA/g, and voltage is 0.05~3.0V.After the charge and discharge cycles 30 times, the discharge specific capacitance is 1303mAh g
-1
Embodiment 4
Be aqueous sucrose solution about 130min of hydro-thermal reaction in 200 ℃ autoclave of 1.5M with concentration, cooling back suction filtration naturally, and after repeatedly washing through water and ethanol, product is put into 80 ℃ of dry 24h of baking oven, the about 3 μ m of gained carbon bulb diameter.
1g carbon ball is dispersed in the hydrochloric acid solution that 30ml concentration is 0.5M, stirred two days, then centrifugal, clean up, dry 12h is standby in 80 ℃ of baking ovens.Carbon ball template after the acidification is dispersed in 1M Co (Ac)
24H
2In the O solution, wherein the ratio of water and ethanol is 1:3 in the solvent.Under 30 ℃, suction filtration behind the stirring 6h spends deionised water 3 times, puts into 80 ℃ of dry 12h of baking oven, and the gained pressed powder is placed Muffle furnace, is warmed up to 500 ℃ with 2 ℃/min, and calcining at constant temperature 1h obtains four shell Co after the cooling naturally
3O
4Hollow ball, the shell size is about 870.2nm ± 21.8nm.
Be the four shell Co of 5:3:2 with weight ratio
3O
4Hollow ball, acetylene black and PVDF are dispersed in and form slurry in the nmp solvent.Slurry is evenly coated on the Copper Foil, and after smearing 4 times repeatedly, the about 30 μ m of the thickness of coating place it in after coating in 80 ℃ of baking ovens and dry.It is 1.6 centimetres sequin that the electrode slice that coats active material is cut into diameter, standby at 80 ℃ of following vacuumize 12h.
What test battery adopted is conventional button cell, is to electrode with the lithium paper tinsel, with 1M LiPF
6Organic solution be electrolyte, solvent is the mixture of EC and DEC, the two weight ratio is 1:1, is assembled in glove box.Current constant mode is adopted in the cycle performance test, and current density is 50mA/g, and voltage is 0.05~3.0V.After the charge and discharge cycles 30 times, the discharge specific capacitance is 1011.5mAh g
-1
Comparative Examples 1
Be the commercial Co of 5:3:2 with weight ratio
3O
4, acetylene black and PVDF be dispersed in and form slurry in the nmp solvent.Slurry is evenly coated on the Copper Foil, and after smearing 6 times repeatedly, the about 80 μ m of the thickness of coating place it in after coating in 80 ℃ of baking ovens and dry.It is 1.6 centimetres sequin that the electrode slice that coats active material is cut into diameter, standby at 80 ℃ of following vacuumize 12h.
What test battery adopted is conventional button cell, is to electrode with the lithium paper tinsel, with 1M LiPF
6Organic solution be electrolyte, solvent is the mixture of EC and DEC, the two weight ratio is 1:1, is assembled in glove box.Current constant mode is adopted in the cycle performance test, and current density is 50mA/g, and voltage is 0.05~3.0V.After the charge and discharge cycles 30 times, the discharge specific capacitance is 287.5mAh g
-1
Embodiment 5
Be aqueous sucrose solution about 130min of hydro-thermal reaction in 200 ℃ autoclave of 1.5M with concentration, cooling back suction filtration naturally, and after repeatedly washing through water and ethanol, product is put into 80 ℃ of dry 24h of baking oven, the about 3 μ m of gained carbon bulb diameter.
The carbon ball template is dispersed in 1M Co (Ac)
24H
2In the O solution, wherein the ratio of water and ethanol is 1:3 in the solvent.Under 30 ℃, suction filtration behind the stirring 6h, spend deionised water 3 times, put into 80 ℃ of dry 12h of baking oven, the gained pressed powder is placed Muffle furnace, be warmed up to 500 ℃ with 2 ℃/min, calcining at constant temperature 1h, naturally obtain three shell Co3O4 hollow balls after the cooling, the shell size is about 864.1nm ± 21.4nm.
Be the three shell Co of 5:3:2 with weight ratio
3O
4Hollow ball, acetylene black and PVDF are dispersed in and form slurry in the nmp solvent.Slurry is evenly coated on the Copper Foil, and after smearing 4 times repeatedly, the about 30 μ m of the thickness of coating place it in after coating in 80 ℃ of baking ovens and dry.It is 1.6 centimetres sequin that the electrode slice that coats active material is cut into diameter, standby at 80 ℃ of following vacuumize 12h.
What test battery adopted is conventional button cell, is to electrode with the lithium paper tinsel, with 1M LiPF
6Organic solution be electrolyte, solvent is the mixture of EC and DEC, the two weight ratio is 1:1, is assembled in glove box.Charge-discharge test adopts the time-dependent current mode, and current density increases to 200mA/g, 1000mA/g, 2000mA/g gradually from 50mA/g, reduces to 50mA/g then again.When current density increased to 2000mA/g, specific discharge capacity was still up to 1117.3mAh g
-1, reduce to 50mA/g again when current density, specific discharge capacity increases to 1505mAh g thereupon
-1