A kind of preparation method of Nano Silver composite lithium iron phosphate cathode material
Technical field
The present invention relates to a kind of preparation method of Nano Silver modified phosphate iron lithium, the Nano Silver composite lithium iron phosphate of synthesis
Material can be used to manufacture various types of lithium ion batteries as anode material for lithium-ion batteries.
Background technology
Along with the progress and development of human society, consumption of the people to the energy constantly increases.And it is existing with fossil energy
Non-regeneration energy based on source is constantly consumed, and not only environment is had adverse effect on, and has no to doubt in the near future
That asks limits the sustainable development of economic society.Therefore, people are in the new energy that strives to find cleaning and can be recycled.With
Lithium ion battery causes the extensive concern of people for the energy energy storage device of representative.In the various of influence performance of lithium ion battery
In factor, anode material for lithium-ion batteries is influence, or even determines the key factor of performance of lithium ion battery.It is being commercialized
Anode material for lithium-ion batteries in LiFePO4 due to raw material be easy to get and it is cheap, have higher operating voltage and electric discharge
Voltage is steady, security performance is high, environmental protection and the advantages of good heat endurance, it is considered to be the lithium-ion electric with favourable prospects
One of pond positive electrode.But the characteristics of being due to LiFePO4 self structure and composition, its electronic conductivity(10~9~10~10S/
cm)With lithium ion diffusion coefficient(1.8×10~14cm2/S)It is relatively low, its specific capacity and rate charge-discharge poor-performing are directly resulted in,
Limit its application.There are many methods to improve the chemical property of lithium iron phosphate positive material at present, wherein with metal
Nano-particles reinforcement is a kind of simple effective method.Nano Silver with excellent conductive capability often elects ferric phosphate as by researcher
The complexing agent of lithium anode material, the chemical property of material is improved in the case where not changing LiFePO4 lattice structure.For example
Patent CN103531801A(In examining)Disclose using modified silver powder composite lithium iron phosphate, its first discharge specific capacity is reachable
168mAh/g, and cycle performance significantly improves.Patent CN101635349A(Effectively)Disclose and use silver compound with preparing
LiFePO4 raw material are mixed in a solvent, are added after reducing agent and are dried in vacuo, and high-temperature heat treatment obtains phosphoric acid in a vacuum
The compound positive electrode of iron lithium/silver/carbon.The iron phosphate compound anode material of lithium highest specific discharge capacity that this method is obtained is reachable
169.1mAh/g, and with good cyclical stability.Patent CN104577117A(In examining)Disclose a kind of low internal resistance lithium from
Sub- battery and preparation method thereof, using the nano silver wire that certain mass percent is added in anode and cathode slurry, not only improves lithium
The electric conductivity of ion battery, the internal resistance for reducing battery, while the high rate performance of lithium ion battery is also greatly improved.
The content of the invention
The technical problems to be solved by the invention are for LiFePO4 as present in anode material for lithium-ion batteries
Electronic conductivity and lithium ion diffusion coefficient is relatively low the problem of directly result in its specific capacity and rate charge-discharge poor-performing there is provided
A kind of simple, effective method for improving electrochemical performances of lithium iron phosphate, that is, pass through solid state reaction and last handling process
Nano Silver composite lithium iron phosphate cathode material is prepared, to meet lithium ion battery, especially electrokinetic cell to LiFePO4 material
The performance requirement of material.
In order to solve the above technical problems, the present invention uses following technical scheme:
A kind of preparation method of Nano Silver composite lithium iron phosphate cathode material, step is as follows:
(1)LiFePO4 and silver nitrate are sufficiently mixed in mortar and a small amount of ethanol are added dropwise and carries out pre-grinding;
(2)Ascorbic acid is added to step(1)In the honed mixture of beforehand research, continue to grind after sufficiently mixing, make reaction
Fully carry out obtaining reaction product;
(3)Post-processing approach A:Solvent is made using deionized water and alcohol mixed solution, by step(2)Obtained reaction product point
It is scattered in solvent and soaks, removes the ascorbic acid in product, it is soaking that solid product is isolated using supercentrifuge afterwards, wash
Wash, centrifuge after solid product is dried in vacuum drying chamber, obtain Nano Silver composite lithium iron phosphate material.
Post-processing approach B:By step(2)Obtained reaction product is placed in tube furnace, under inert gas shielding, high temperature
Processing makes ascorbic acid be carbonized, and obtains the Nano Silver composite lithium iron phosphate material of carbon coating.
The mass ratio of the silver nitrate and LiFePO4 is 1~10:100, it is necessary to which second is added dropwise on the basis of 1g LiFePO4s
Alcohol 0.3mL, beforehand research time consuming is 10~30min;Ginding process of the present invention is not limited to underhand polish, also including machinery
Grind such as ball milling.
The mass ratio of the ascorbic acid and silver nitrate is 1~3:1;The step(2)Middle addition ascorbic acid is fully mixed
After conjunction, continuation milling time is the min of 30min~60.
The step(3)Deionized water and the volume ratio of ethanol is 1 in the deionized water and alcohol mixed solution that use:1
~10;Reaction product soaks 10~30min in a solvent.
The step(3)10~30min separation is centrifuged under the conditions of 10000~15000 revs/min using supercentrifuge
Go out solid product, washing, centrifugal process are repeated 2~3 times.
The step(3)The solid product of acquisition is dried into 12~24h in vacuum drying chamber under the conditions of 50~60 DEG C.
The inert gas is nitrogen or argon gas;High-temperature process is 1~2h of processing under 300~700 DEG C of high temperature.
The principle of the present invention:On the basis of LiFePO4, by being ground together with silver nitrate and ascorbic acid, on the one hand
So that silver nitrate is fully reduced generation Nano Silver by ascorbic acid, on the other hand make the Nano Silver of generation in LiFePO 4 material
It is dispersed, and being combined together well with LiFePO4 crystal;Ascorbic acid is dissolved in by water alcohol by post-processing approach A molten
In liquid, while isolating Nano Silver/composite ferric lithium phosphate material using supercentrifuge;By post-processing approach B by Vitamin C
Sour high temperature cabonization, obtains being coated with Nano Silver/composite ferric lithium phosphate material of carbon material, reach raising material electronics electrical conductivity and
The purpose of lithium ion diffusion coefficient.
The present invention is compared with other method, and advantageous effects are:The present invention based on LiFePO 4 material, by with
Silver salt, ascorbic acid mixed grinding, prepare the Nano Silver for having good combination with LiFePO4.It is modified by this method
Afterwards, the electric conductivity of lithium iron phosphate positive material is significantly improved, and specific capacity, cyclical stability and high rate performance are significantly changed
It is kind.
The present invention prepares Nano Silver composite lithium iron phosphate cathode material by solid state reaction and last handling process, leads to
Electro-chemical test confirmation is crossed, the LiFePO 4 material being modified through Nano Silver, its electric conductivity is significantly improved, specific capacity, circulation are steady
Qualitative and high rate performance is significantly improved, and its first discharge specific capacity is circulated up to 163mAh/g, and by 80 circles after testing
Afterwards, capacity is undamped, and specific capacity is still up to 95mAh/g under 5C multiplying powers, with good high rate performance.In addition, institute of the present invention
The method of use is simple, easy to operate, it is easy to industrialized production, and energy consumption is relatively low, and environmental pollution is smaller.Therefore, with other
Method is compared has obvious advantage in process and improved properties effect.
Brief description of the drawings
Fig. 1 is(a)LiFePO4 and(b)The silver-colored composite positive pole of lithium iron phosphate/nanometer prepared in the embodiment of the present invention 2
SEM schemes.
Fig. 2 is(a)LiFePO4,(b)The He of the embodiment of the present invention 2(c)The lithium iron phosphate/nanometer silver prepared in embodiment 4
The XRD spectra of composite positive pole.
Fig. 3 is(a)LiFePO4,(b)The He of the embodiment of the present invention 2(c)The lithium iron phosphate/nanometer silver prepared in embodiment 4
The first discharge specific capacity curve of composite positive pole.
Fig. 4(a)For LiFePO4,(b)The He of the embodiment of the present invention 2(c)The lithium iron phosphate/nanometer silver prepared in embodiment 4
The high rate performance of composite positive pole.
Embodiment
With reference to specific embodiment, the present invention will be further described.It should be understood that following examples are merely to illustrate this
Invention can make one not for limitation the scope of the present invention, the person skilled in the art in the field according to the content of foregoing invention
A little nonessential modifications and adaptations.
Embodiment 1
A kind of preparation method of Nano Silver composite lithium iron phosphate cathode material, step is as follows:
(1)1g LiFePO4s and 0.01g silver nitrates are weighed, is poured into mortar, after with spoon, the two is sufficiently mixed, pre-grinding 30
Minute, and the dropwise addition 0.2ml ethanol in process of lapping;
(2)Weigh 0.03g ascorbic acid to be added in above-mentioned ground mixture, and be sufficiently mixed with spoon, then kept
Grinding 60 minutes, the progress that reacts fully obtains corresponding reaction product;
(3)It is 1 that the reaction product obtained is placed in into about 30mL volume ratios:In 1 deionized water and alcohol mixed solvent, and shake
Swing and shake up, then remains stationary 30 minutes, fully the ascorbic acid in dissolving reaction product, then use with cooling function
Supercentrifuge is centrifuged 30 minutes under 15000 revs/min, is then taken out upper solution, is isolated solid product, is washed away anti-
Bad hematic acid;This washing centrifugal process is repeated 3 times;The solid product of acquisition is placed in vacuum drying chamber, is dried under the conditions of 60 DEG C
12 hours, obtain the silver-colored composite positive pole of lithium iron phosphate/nanometer.
Using obtained lithium iron phosphate/nanometer silver composite material as positive electrode, it is assembled into half-cell and carries out electrochemistry
Test, as a result shows that the silver-colored composite positive pole first discharge specific capacity of lithium iron phosphate/nanometer reaches 140mAh/g, hence it is evident that better than institute
The commercial phosphoric acid iron lithium anode material 128mAh/g of selection.
Embodiment 2
A kind of preparation method of Nano Silver composite lithium iron phosphate cathode material, step is as follows:
(1)1g LiFePO4s and 0.02g silver nitrates are weighed, is poured into mortar, after with spoon, the two is sufficiently mixed, pre-grinding 30
Minute, and the dropwise addition 0.2ml ethanol in process of lapping;
(2)Weigh 0.06g ascorbic acid to be added in above-mentioned ground mixture, and be sufficiently mixed with spoon, then kept
Grinding 60 minutes, the progress that reacts fully obtains corresponding reaction product;
(3)It is 1 that the reaction product obtained is placed in into about 30mL volume ratios:In 1 deionized water and alcohol mixed solvent, and shake
Swing and shake up, then remains stationary 30 minutes, fully the ascorbic acid in dissolving reaction product, then use with cooling function
Supercentrifuge is centrifuged 30 minutes under 15000 revs/min, is then taken out upper solution, is isolated solid product, is washed away anti-
Bad hematic acid;This washing centrifugal process is repeated 3 times;The solid product of acquisition is placed in vacuum drying chamber, is dried under the conditions of 60 DEG C
12 hours, obtain the silver-colored composite positive pole of lithium iron phosphate/nanometer.
Fig. 1(b)Scheme for the SEM of lithium iron phosphate/nanometer silver composite manufactured in the present embodiment, it can be seen that phosphorus
After sour iron lithium is combined with silver, the original pattern of LiFePO4 is substantially maintained.
Fig. 2(b)Compose, be may determine that from collection of illustrative plates for the XRD of lithium iron phosphate/nanometer silver composite manufactured in the present embodiment,
There was only the phase of LiFePO4 and silver in compound.
Fig. 3(b)First discharge specific capacity for the silver-colored composite positive pole of lithium iron phosphate/nanometer manufactured in the present embodiment is bent
Line, collection of illustrative plates shows first discharge specific capacity up to 156mAh/g.
Fig. 4(b)For the high rate performance curve of the silver-colored composite positive pole of lithium iron phosphate/nanometer manufactured in the present embodiment, collection of illustrative plates
Composite has good high rate performance in display the present embodiment.
Embodiment 3
A kind of preparation method of Nano Silver composite lithium iron phosphate cathode material, step is as follows:
(1)1g LiFePO4s and 0.01g silver nitrates are weighed, is poured into mortar, after with spoon, the two is sufficiently mixed, pre-grinding 30
Minute, and the dropwise addition 0.2ml ethanol in process of lapping;
(2)Weigh 0.03g ascorbic acid to be added in above-mentioned ground mixture, and be sufficiently mixed with spoon, then kept
Grinding 60 minutes, the progress that reacts fully obtains corresponding reaction product;
(3)The reaction product obtained is moved in porcelain boat, is placed in tube furnace, leads to after argon gas half an hour, is warming up to 500
DEG C, 1h is kept at this temperature;Then room temperature is down to, obtains being compounded with Nano Silver/lithium iron phosphate positive material of carbon material, it is whole
Individual heat treatment process is carried out under argon gas protection.
Using obtained lithium iron phosphate/nanometer silver composite material as positive electrode, it is assembled into half-cell and carries out electrochemistry
Test, as a result shows that the silver-colored composite positive pole first discharge specific capacity of lithium iron phosphate/nanometer reaches 142mAh/g.
Embodiment 4
A kind of preparation method of Nano Silver composite lithium iron phosphate cathode material, step is as follows:
(1)1g LiFePO4s and 0.02g silver nitrates are weighed, is poured into mortar, after the two is sufficiently mixed with spoon, 30 points are ground
Clock, and the dropwise addition 0.2ml ethanol in process of lapping;
(2)Weigh 0.06g ascorbic acid to be added in above-mentioned ground mixture, and be sufficiently mixed with spoon, then kept
Grinding 60 minutes, the progress that reacts fully obtains corresponding reaction product;
(3)The reaction product obtained is moved in porcelain boat, is placed in tube furnace, leads to after argon gas half an hour, is warming up to 500
DEG C, 1h is kept at this temperature;Then room temperature is down to, obtains being compounded with Nano Silver/lithium iron phosphate positive material of carbon material, it is whole
Individual heat treatment process is carried out under argon gas protection.
Fig. 2(c)Compose, be may determine that from collection of illustrative plates for the XRD of lithium iron phosphate/nanometer silver composite manufactured in the present embodiment,
There was only the phase of LiFePO4 and silver in compound.
Fig. 3(c)First discharge specific capacity for the silver-colored composite positive pole of lithium iron phosphate/nanometer manufactured in the present embodiment is bent
Line, collection of illustrative plates shows first discharge specific capacity up to 163mAh/g.
Fig. 4(c)For the high rate performance curve of the silver-colored composite positive pole of lithium iron phosphate/nanometer manufactured in the present embodiment, collection of illustrative plates
Composite has good high rate performance in display the present embodiment.
Embodiment 5
A kind of preparation method of Nano Silver composite lithium iron phosphate cathode material, step is as follows:
(1)1g LiFePO4s and 0.1g silver nitrates are weighed, is poured into mortar, after with spoon, the two is sufficiently mixed, pre-grinding 25
Minute, and the dropwise addition 0.2ml ethanol in process of lapping;
(2)Weigh 0.1g ascorbic acid to be added in above-mentioned ground mixture, and be sufficiently mixed with spoon, then keep grinding
Mill 45 minutes, the progress that reacts fully obtains corresponding reaction product;
(3)It is 1 that the reaction product obtained is placed in into about 30mL volume ratios:In 10 deionized water and alcohol mixed solvent, and
Concussion shakes up, then remains stationary 30 minutes, fully the ascorbic acid in dissolving reaction product, then using with cooling function
Supercentrifuge centrifuged 25 minutes under 10000 revs/min, then upper solution is taken out, solid product is isolated, is washed away
Ascorbic acid;This washing centrifugal process is repeated 3 times;The solid product of acquisition is placed in vacuum drying chamber, is done under the conditions of 50 DEG C
Dry 24 hours, obtain the silver-colored composite positive pole of lithium iron phosphate/nanometer.
Using obtained lithium iron phosphate/nanometer silver composite material as positive electrode, it is assembled into half-cell and carries out electrochemistry
Test, as a result shows that the silver-colored composite positive pole first discharge specific capacity of lithium iron phosphate/nanometer reaches 130mAh/g.
Embodiment 6
A kind of preparation method of Nano Silver composite lithium iron phosphate cathode material, step is as follows:
(1)1g LiFePO4s and 0.05g silver nitrates are weighed, is poured into mortar, after with spoon, the two is sufficiently mixed, pre-grinding 10
Minute, and the dropwise addition 0.2ml ethanol in process of lapping;
(2)Weigh 0.1g ascorbic acid to be added in above-mentioned ground mixture, and be sufficiently mixed with spoon, then keep grinding
Mill 35 minutes, the progress that reacts fully obtains corresponding reaction product;
(3)It is 1 that the reaction product obtained is placed in into about 30mL volume ratios:In 5 deionized water and alcohol mixed solvent, and shake
Swing and shake up, then remains stationary 30 minutes, fully the ascorbic acid in dissolving reaction product, then use with cooling function
Supercentrifuge is centrifuged 10 minutes under 12000 revs/min, is then taken out upper solution, is isolated solid product, is washed away anti-
Bad hematic acid;This washing centrifugal process is repeated 2 times;The solid product of acquisition is placed in vacuum drying chamber, is dried under the conditions of 55 DEG C
20 hours, obtain the silver-colored composite positive pole of lithium iron phosphate/nanometer.
Using obtained lithium iron phosphate/nanometer silver composite material as positive electrode, it is assembled into half-cell and carries out electrochemistry
Test, as a result shows that the silver-colored composite positive pole first discharge specific capacity of lithium iron phosphate/nanometer reaches 136mAh/g.
Embodiment 7
A kind of preparation method of Nano Silver composite lithium iron phosphate cathode material, step is as follows:
(1)1g LiFePO4s and 0.03g silver nitrates are weighed, is poured into mortar, after with spoon, the two is sufficiently mixed, pre-grinding 15
Minute, and the dropwise addition 0.2ml ethanol in process of lapping;
(2)Weigh 0.045g ascorbic acid to be added in above-mentioned ground mixture, and be sufficiently mixed with spoon, then kept
Grinding 50 minutes, the progress that reacts fully obtains corresponding reaction product;
(3)The reaction product obtained is moved in porcelain boat, is placed in tube furnace, leads to after argon gas half an hour, is warming up to 300
DEG C, 2h is kept at this temperature;Then room temperature is down to, obtains being compounded with Nano Silver/lithium iron phosphate positive material of carbon material, it is whole
Individual heat treatment process is carried out under argon gas protection.
Using the obtained lithium iron phosphate/nanometer silver composite material for being compounded with carbon material as positive electrode, half electricity is assembled into
Pond simultaneously carries out electro-chemical test, as a result shows that the silver-colored composite positive pole first discharge specific capacity of lithium iron phosphate/nanometer reaches
143mAh/g。
Embodiment 8
A kind of preparation method of Nano Silver composite lithium iron phosphate cathode material, step is as follows:
(1)1g LiFePO4s and 0.08g silver nitrates are weighed, is poured into mortar, after with spoon, the two is sufficiently mixed, pre-grinding 20
Minute, and the dropwise addition 0.2ml ethanol in process of lapping;
(2)Weigh 0.2g ascorbic acid to be added in above-mentioned ground mixture, and be sufficiently mixed with spoon, then keep grinding
Mill 40 minutes, the progress that reacts fully obtains corresponding reaction product;
(3)The reaction product obtained is moved in porcelain boat, is placed in tube furnace, leads to after argon gas half an hour, is warming up to 700
DEG C, 1h is kept at this temperature;Then room temperature is down to, obtains being compounded with Nano Silver/lithium iron phosphate positive material of carbon material, it is whole
Individual heat treatment process is carried out under argon gas protection.
Using the obtained lithium iron phosphate/nanometer silver composite material for being compounded with carbon material as positive electrode, half electricity is assembled into
Pond simultaneously carries out electro-chemical test, as a result shows that the silver-colored composite positive pole first discharge specific capacity of lithium iron phosphate/nanometer reaches
132mAh/g。
Each raw material cited by the present invention can realize the present invention, and the bound value of each raw material, interval value can
Realizing the bound value and interval value of technological parameter (such as rotating speed, temperature, time) of the invention, of the invention can realize
The present invention, embodiment numerous to list herein.
In view of the foregoing it is apparent that, preparation method involved in the present invention can prepare high-quality LiFePO4/receive
Rice silver composite material, and prepared composite positive pole is compared with selected single lithium iron phosphate positive material, electrochemistry
Performance is significantly improved;In addition, the preparation method technique of the present invention is simple, operation is easy, and energy consumption is relatively low, it is easy to which amplification is carried out
Industrialized production.
The general principle and principal character and advantages of the present invention of the present invention has been shown and described above.The skill of the industry
Art personnel are it should be appreciated that the present invention is not limited to the above embodiments, and described in above-described embodiment and specification is explanation
The principle of the present invention, without departing from the spirit and scope of the present invention, various changes and modifications of the present invention are possible, these
Changes and improvements all fall within the protetion scope of the claimed invention.The claimed scope of the invention by appended claims and
Its equivalent thereof.