Background technology
Lithium ion battery be by Japanese Sony Corporation in nineteen ninety development and begin to realize commercial, its appearance deserves to be called the historical once leap of secondary cell.Fast development along with information industry, the consumption market of portable communication apparatus and laptop computer is increasing, lithium ion battery is as the power supply of a new generation, compare with other battery, the advantage of lithium ion battery is that (commercially available battery mostly is 3.6V to the open circuit voltage height, and the open circuit voltage of ni-mh and NI-G secondary cell is 1.2V), specific capacity is big (to be 2.5 times of NI-G secondary cell, be 1.5 times of nickel-hydrogen secondary cell), low (<8%/moon of self-discharge rate, far below 30% and Ni-MH battery of nickel-cadmium cell 40%), life-span long (can reach more than thousand times usually), not having memory effect also is the dark outstanding advantage popular to people of lithium ion battery, and this is that other secondary cell is not available.Roski11 consulting group company estimated once in the period of the 2000-2005 that the whole world comprised that the demand in the lithium ion battery market of polymerization lithium ion battery will increase by 40%.
Anode material for lithium-ion batteries is one of critical material of making lithium rechargeable battery, and that anode material for lithium-ion batteries research at present is more is the LiCoO with layer structure
2, LiNiO
2LiMn with spinel structure
2O
4, LiCoO wherein
2The simple and stable performance of preparation technology, be the positive electrode that is widely used in commercial Li-ion batteries.
In the prior art synthesizing of positive electrode adopted solid reaction process mostly, promptly adopt the oxide or the carbonate of lithium and cobalt or manganese, calcining for a long time under 800~900 ℃ high temperature, the advantage of this method is that technology is simple, but also exist significant disadvantages: the uneven components of synthetic material, particle is big and distribution is wide, calcining heat height and time are long, in general, positive electrode must possess good crystal structure, composition is even, the submicron-scale particle diameter, narrow diameter distribution, the big grade of specific surface could obtain higher chemical property, and solid phase method is difficult to satisfy these conditions obviously; Adopting the polyvinyl alcohol or the polyethylene glycol aqueous solution in the Chinese patent application 99113860.0 is solvent, through heating, the concentrated gel that forms, obtain required powder after the calcining, this method has product purity height, chemical composition advantage of uniform, but need add the thermal agitation concentrated solution for a long time, more time-consuming, and energy consumption is big; Propose a kind of citrate gel method in the Chinese patent application 02123112.5 and prepared anode material of lithium battery, this method has that synthesis temperature is low, the particle diameter advantage of uniform, but the pH value that in the process of preparation, needs strict control solution, if control bad then can form precipitation, and can not get gel; Similar to it, propose in the Chinese patent application 0112937.6 to utilize the new technology of preparing nm-class lithium cobaltate by nm reactor, need to regulate pH value and the slower problem of reaction but also exist, therefore in the process of practical application, be subjected to certain restriction; Also proposed a kind of Hydrothermal Preparation scheme of utilizing in the Chinese patent application 97112128.1, this scheme preparation process is simple, but reaction needed 5 days, obviously the overlong time of reaction also exists the low shortcoming of productive rate simultaneously.
Summary of the invention
The objective of the invention is to overcome deficiency of the prior art, propose a kind of Co-60 of utilization and make radioactive source, the high-molecular gel that obtains to contain lithium and cobalt or manganese by gamma-ray irradiation prepares the method for anode material for lithium-ion batteries.
Purpose of the present invention realizes in the following manner.
The liquid-phase synthesis process of lithium ion secondary battery anode material of the present invention, it is characterized in that, operating procedure is: (1) preparation contains the mixed aqueous solution of cobalt or manganese compound, lithium-containing compound and polymer monomer, wherein, the lithium in lithium compound and the cobalt compound and the mole ratio of cobalt are (0.9~1.1): l, the lithium in lithium compound and the manganese compound and the mole ratio of manganese are (1~1.1): 2, and the water in the mixed solution and the volume ratio of polymer monomer are (0.2~5): 1; Described lithium compound is Nitrates or hydroxide or acetic acid salt or alkyl oxide, for example LiNO of lithium
3, Li
2CO
3, LiOHH
2O, LiAC2H
2O etc.; Described cobalt or manganese compound are Nitrates or oxyhydroxide or acetic acid salt or alkyl oxide, for example Co (NO of cobalt or manganese
3)
26H
2O, Co (CH
3COO)
24H
2O, Co (OH)
2, Mn (CH
3COO)
24H
2O, Mn (NO
3)
2, MnCO
3Deng; Described polymer monomer is that structural formula is
Vinyl compound, R in the formula
1, R
2, R
3, R
4Be respectively in hydroxyl, alkyl, carboxyl, the amide groups any, for example acrylic acid, acrylamide etc.; (2) above-mentioned mixed aqueous solution is placed the gamma-ray irradiation environment, the polymer monomer polymerization that utilizes gamma-ray irradiation to cause in the solution obtains high-molecular gel, and its irradiation dose is more than 1000Gy; (3) then resulting gel is carried out conventional oven dry, thermal decomposition, sintering circuit, form the powder that can be used as anode material for lithium-ion batteries.
In the mixed aqueous solution that contains cobalt or manganese compound and lithium-containing compound and polymer monomer, can also add the chemical property that some other yuan usually further improve resultant positive electrode, for example: in containing the aqueous solution of cobalt, add elements such as Mg, Al, Zr, in containing the aqueous solution of manganese, add elements such as Cr, Co; Also can increase other related in this patent doped chemical, prepare mixed aqueous solution with reference to Chinese patent application 02120651.1.
The liquid-phase synthesis process of lithium ion secondary battery anode material of the present invention can obtain uniform and stable high score at short notice in gel.Traditional gel method is to obtain gel by hydrolysis of alkoxide or adding pincers mixture after concentrating, and the reaction time is long and restive.But the approach from irradiation does not seek redress, because most of people thinks monomer in the process of irradiation polymerization, because segregation phenomena can take place solute solubility change in solvent, causes the inequality of forming.In fact, because monomer polymerization speed in the environment of irradiation is very fast, solute segregation can not occur, therefore can obtain forming uniform and stable high-molecular gel.Compared to existing technology, the present invention can reduce sintering temperature significantly and shorten sintering time, and has higher charge/discharge capacity.Therefore, the liquid-phase synthesis process of lithium ion secondary battery anode material of the present invention has advantages such as efficient height, good product quality, will have better industrial application prospects.
Embodiment
The invention will be further described below by embodiment and accompanying drawing.
Referring to Fig. 1, preparation lithium cobalt oxide of lithium-ion secondary battery cathode materials (LiCoO of the present invention
2) or LiMn2O4 (LiMn
2O
4) liquid-phase synthesis process, comprise that preparation mixed aqueous solution, irradiation make operations such as gel, oven dry, thermal decomposition, sintering.When selecting the polymer monomer that contains amido and nitrate configuration mixed aqueous solution for use, spontaneous combustion can take place in the gel that generates behind the irradiation in the process of oven dry, therefore can save the operation (thermal decomposition) in the frame of broken lines this moment, directly enters sintering circuit.
Referring to three kinds of different LiCoO among Fig. 2
2The X-ray diffraction light spectrogram of powder.LiCoO with embodiment 4 preparations
2Powder tangible LiCoO just occurred in the spectrogram when 650 ℃ of sintering temperatures
2Diffraction maximum, but still exist a small amount of Li in the spectrogram
2CO
3Dephasign peak (seeing nethermost curve among the figure).
LiCoO with embodiment 6 preparations
2The X-ray diffraction light spectrogram of powder is a curve middle among Fig. 3.Find out from this curve, in the time of 750 ℃, obtain forming single LiCoO
2There is not the dephasign peak in powder.
Fig. 3 is with embodiment 8 prepared LiMn
2O
4There is not the dephasign peak in the X-ray diffraction light spectrogram of powder among the figure.
Embodiment 1
Get the LiNO of 2.8969g respectively
3Co (NO with 11.6412g
3)
26H
2O (be Li: the Co mol ratio is 1.05: 1) stirs fully dissolving in 10mL water, add acrylic acid 10mL again, to be mixed evenly after, utilize Co-60 to make radioactive source, carry out radiation polymerization, irradiation dose is 5000Gy (radiation dose rate 55Gy/min, exposure time is 90min), finally obtain the purple high-molecular gel, this gel is dried down at 100 ℃~150 ℃, then be heated to 450 ℃ slowly, the organic substance in the gel is removed in thermal decomposition 2 hours, forms LiCoO
2The powder predecessor.This LiCoO of sintering under air atmosphere then
2Powder predecessor, sintering temperature are 800 ℃, and sintering time is 10 hours, finally obtains LiCoO
2Powder.
LiCoO with embodiment 1 preparation
2Powder is made half-cell to the lithium sheet, and used electrolyte is the LiPF of 1mol/L
6/ (EC+DEC) (wherein EC is an ethylene carbonate, and DEC is a diethyl carbonate, and both volume ratios are 1: 1), the test voltage interval is 2.7V~4.2V, current density is 0.67mA/cm
2, the battery charging and discharging platform curve that obtains is seen the solid line part of Fig. 4, and heavy line is the charging platform curve of battery, and fine line is its discharge platform curve.As seen from the figure, the LiCoO that makes of the present invention
2The powder discharge specific capacity is about 150mAh/g.
Embodiment 2
Get the LiNO of 1.8099g respectively
3Co (NO with 7.2758g
3)
26H
2O (be Li: the Co mol ratio is 1.05: 1), in 50mL water, stir fully dissolving, add acrylic acid 50mL again, to be mixed evenly after, utilize Co-60 to make radioactive source, carry out radiation polymerization, irradiation dose is 8000Gy (radiation dose rate 80Gy/min, exposure time is 100min), obtain high-molecular gel, this gel 100 ℃~150 ℃ oven dry down, then is heated to 450 ℃ of organic substances that decompose in the gel slowly, forms LiCoO
2The powder predecessor.This LiCoO of sintering under air atmosphere then
2Powder predecessor, sintering temperature are 800 ℃, and sintering time is 10 hours.
Embodiment 3
Get the LiNO of 1.8099g respectively
3Co (NO with 7.2758g
3)
26H
2O (be Li: the Co mol ratio is 1.05: 1), in 12.5mL water, stir fully dissolving, add acrylic acid 12.5mL again, to be mixed evenly after, utilize Co-60 to make radioactive source, carry out radiation polymerization, irradiation dose is 2000Gy (radiation dose rate is 50Gy/min, and exposure time is 40min), final high-molecular gel, this gel 100 ℃~150 ℃ oven dry down, then is heated to 450 ℃ of organic substances that decompose in the gel slowly, forms LiCoO
2The powder predecessor.This LiCoO of sintering under air atmosphere then
2The powder predecessor in 800 ℃ of sintering 10 hours, promptly obtains LiCoO
2Powder.
Embodiment 4
Get the Li of 1.8471g respectively
2CO
3Co (NO with 14.5515g
3)
26H
2O (be Li: the Co mol ratio is 1: 1), in 4.2mL water, stir fully dissolving, add acrylic acid 8.3ml again, to be mixed evenly after, utilize Co-60 to make radioactive source, carry out radiation polymerization, irradiation dose is 1000Gy (radiation dose rate is 50Gy/min, and exposure time is 20min), obtain the high-molecular gel of purple, this gel 100 ℃~150 ℃ oven dry down, then is heated to 450 ℃ of organic substances that decompose in the gel slowly, forms LiCoO
2The powder predecessor.This LiCoO of sintering under air atmosphere then
2Powder predecessor, sintering temperature are 650 ℃, and sintering time is 10 hours.
Nethermost curve among Fig. 2 is prepared LiCoO among the embodiment 4
2Tangible LiCoO has appearred in the X-ray diffraction light spectrogram of powder in the spectrogram
2Diffraction maximum.
Embodiment 5
Get the LiOHH of 0.8392g respectively
2Co (the CH of O and 4.9816g
3COO)
24H
2O (be Li: the Co mol ratio is 1: 1), in 13.3mL water, stir fully dissolving, add acrylic acid 6.7mL again, to be mixed evenly after, utilize Co-60 to make radioactive source, carry out radiation polymerization, irradiation dose is 6000Gy (radiation dose rate is 60Gy/min, and exposure time is 100min), obtain the high-molecular gel of purple, this gel 100 ℃~150 ℃ oven dry down, then is heated to 450 ℃ of organic substances that decompose in the gel slowly, forms LiCoO
2The powder predecessor.This LiCoO of sintering under air atmosphere then
2Powder predecessor, sintering temperature are 700 ℃, and sintering time is 9 hours.
Embodiment 6
Get the CH of 1.9384g respectively
3COOLi2H
2Co (the CH of O and 4.9816g
3COO)
24H
2O (be Li: the Co mol ratio is 0.95: 1), in 16mL water, stir fully dissolving, add acrylic acid 4ml again, to be mixed evenly after, utilize Co-60 to make radioactive source, carry out radiation polymerization, irradiation dose is 8000Gy (radiation dose rate is 100Gy/min, and exposure time is 80min), obtain the high-molecular gel of purple, this gel 100 ℃~150 ℃ oven dry down, then is heated to 450 ℃ of organic substances that decompose in the gel slowly, forms LiCoO
2The powder predecessor.This LiCoO of sintering under air atmosphere then
2Powder predecessor, sintering temperature are 750 ℃, and sintering time is 8 hours.
Intermediate curve among Fig. 2 is prepared LiCoO in the present embodiment 6
2There is not Li in the X-ray diffraction light spectrogram of powder in the spectrogram
2CO
3And Co
3O
4The dephasign peak, obtain forming single LiCoO
2Powder.
Embodiment 7
Get the LiOHH of 0.4196g respectively
2Co (the NO of O and 2.9103g
3)
26H
2O (be Li: the Co mol ratio is 1: 1), in 5mL water, stir fully dissolving, add acrylamide 1g again, to be mixed evenly after, utilize Co-60 to make radioactive source, carry out radiation polymerization, irradiation dose is 10000Gy (radiation dose rate is 150Gy/min, and exposure time is 67min), obtain the high-molecular gel of purple, dieseling 130 ℃ of bakings down, can be taken place in this gel, directly obtain LiCoO
2The powder predecessor.This LiCoO of sintering under air atmosphere then
2Powder predecessor, sintering temperature are 850 ℃, and sintering time is 6 hours.
Embodiment 8
Get the CH of 1.0712g respectively
3COOLi2H
2Mn (the CH of O and 4.9018g
3COO)
24H
2O (be Li: the Mn mol ratio is 1.05: 2), in 20mL water, stir fully dissolving, add acrylamide 5g again, to be mixed evenly after, utilize Co-60 to make radioactive source, carry out radiation polymerization, irradiation dose is 4000Gy (radiation dose rate is 120Gy/min, and exposure time is 33min), obtain the high-molecular gel of purple, dieseling 130 ℃ of bakings down, can be taken place in this gel, directly obtain LiMn
2O
4The powder predecessor.This LiMn of sintering under air atmosphere then
2O
4Powder predecessor, sintering temperature are 850 ℃, and sintering time is 6 hours.
Fig. 3 is prepared LiMn in the present embodiment 8
2O
4There is not the dephasign peak in the X-ray diffraction light spectrogram of powder in the spectrogram, obtain to form single LiMn
2O
4Powder.
Comparative example 1 usefulness solid phase method prepares cobalt acid lithium powder
Get the LiOHH of 0.8812g respectively
2The Co of O and 1.4987g
3O
4(be Li: the Co mol ratio is 1.05: 1), after the grinding, pre-burning after 4 hours under 500 ℃ of air atmospheres 820 ℃ of following sintering 16 hours, makes LiCoO again
2Powder.
Among Fig. 2 uppermost curve representation the prepared LiCoO of this comparative example
2The X-ray diffraction light spectrogram of powder.The cobalt acid lithium powder that this comparative example makes causes uneven components because long high-temperature process can cause the volatilization of lithium ion, and as can be seen from the figure, it exists Co near 32 °
3O
4Dephasign peak (marking with * number among the figure).
Comparative example 2 usefulness spontaneous combustion legal systems are equipped with cobalt acid lithium powder
Get the LiOHH of 0.5874g respectively
2The CH of O, 0.7141g
3COOLi2H
2Co (the CH of O and 4.9816g
3COO)
24H
2O (be Li: the Co mol ratio is 1.05: 1) stirs fully dissolving in 200mL water, the heating solvent evaporated, and prepared sediment but to be heated to a certain degree be that dieseling can take place directly obtains LiCoO
2The powder predecessor 850 ℃ of following sintering 12 hours, makes LiCoO again
2Powder.
With comparative example 2 preparation LiCoO
2Powder is made half-cell to the lithium sheet, and used electrolyte is the LiPF of 1mol/L
6/ (EC+DEC) (wherein EC is an ethylene carbonate, and DEC is a diethyl carbonate, and both volume ratios are 1: 1), the test voltage interval is 2.7V~4.2V, current density is 0.67mA/cm
2The battery charging and discharging platform curve that obtains is seen the dotted portion of Fig. 4, and thick dashed line is the charging platform curve of battery, and fine dotted line is its discharge platform curve.As seen from the figure, the LiCoO that makes of this comparative example
2The powder discharge specific capacity is about 130mAh/g.
From the performance comparison of above 7 embodiment and two comparative examples as can be seen, by the synthetic LiCoO of the present invention
2Powder can reduce sintering temperature significantly and shorten sintering time, and for example according to Fig. 2, sintering temperature is (embodiment 4) in the time of 650 ℃, has just occurred tangible LiCoO in the spectrogram
2Diffraction maximum.Along with the rising of temperature, sintering 8 hours (embodiment 6) obtains forming single LiCoO in the time of 750 ℃
2Powder.If by solid phase method synthetic (comparative example 1), sintering temperature need reach 820 ℃, sintering time need extend to 16 hours, and because lithium ion volatilization phenomenon can appear in long high-temperature process, causes uneven components, Co occurred
3O
4The dephasign peak.Simultaneously according to embodiment 1 and LiCoO that comparative example 2 synthesizes
2The charge-discharge performance of powder is relatively found, the LiCoO that the present invention is prepared
2Powder has higher charge/discharge capacity.