A kind of high-performance anthracite/silicon monoxide/phosphorus composite negative pole material and preparation method thereof
Technical field
The present invention relates to a kind of lithium ion battery anthracite/silicon monoxide/phosphorus composite negative pole materials and preparation method thereof, belong to
In electrochemical field.
Background technique
In recent years, as lithium ion battery is widely used in various mobile electronic devices, electric car, aerospace with
And military field.High specific energy, high safety, low cost have become the developing goal of lithium ion battery industry.Therefore, research
Superior, the low-cost electrode material of energy will become the core drive for pushing lithium ion battery industry development.
Commercial lithium-ion batteries mainly use graphite carbon material as negative electrode active material at present.However, graphite-like
Carbon negative pole material makes it not be able to satisfy electronics to set because of its specific capacity not high (372 mAh/g) and lithium deposition bring safety issue
Standby miniaturization and automobile-used lithium ion battery are high-power, high capacity requires.Silicon monoxide is as a kind of new type lithium ion battery cathode
Material becomes the hot spot of cathode investigation of materials because of its theoretical specific capacity high (2400 mAh/g).But it is in charge and discharge process
Existing volume expansion can cause active particle dusting, eventually because silicon particle between and the electrical contact between particle and collector
Lose and capacity is significantly decayed, hinder its commercialization process.To solve the above-mentioned problems, people attempt carbon material and
SiO is combined with each other the composite material being had excellent performance, although the composite material performance is improved, it also occurs
Some new problems: 1. cycle efficieny is relatively low for the first time for silicon/carbon composite;2. silicon/carbon composite capacity attenuation is fast, cyclicity
It can be poor;3. the volume expansion of SiO is not effectively inhibited in silicon/carbon composite.To solve the above-mentioned problems, Ren Menyou
It attempts to coat one layer of amorphous carbon in its outer surface to alleviate the volume expansion of Si.Although using amorphous carbon method for coating one
Determine the volume expansion that SiO is alleviated in degree, but excessive introducing carbon material causes its specific capacity and first charge discharge efficiency and reduces;
In addition, this method can only alleviate the volume expansion of SiO to a certain extent when SiO content is few, and when SiO content is more than
When 20%, amorphous carbon cladding is undesirable to the buffering effect of SiO volume expansion.
In view of the above-mentioned problems, the present invention is proposed by introducing the elemental phosphorous volume expansion for improving first charge discharge efficiency and controlling SiO.
There is volume expansion when although simple substance P and SiO is as negative electrode material, anthracite/silicon monoxide/phosphorus in the present invention is negative
Pole material but shows excellent cycle performance and higher first charge discharge efficiency, therefore, anthracite is effectively combined with SiO and P, energy
Enough meet market to the performance requirement of lithium ion battery of new generation.
Summary of the invention
The present invention provides a kind of high-performance anthracite/silicon monoxide/phosphorus composite negative pole materials and preparation method thereof, with nothing
Bituminous coal
For raw material, the preparation cost of material is reduced from source, then by compound with silicon monoxide and phosphorus, make Compound Negative
Pole material is provided with excellent volumetric properties, cycle performance and high rate performance.This method is simple and easy, is suitable for industrial metaplasia
It produces.
The technical solution adopted by the present invention is that: good anthracite (phosphorus content is greater than 97%) is selected, by purification, high temperature
High-energy ball milling is carried out with certain proportion with SiO and P after heat treatment and obtains anthracite/SiO/P composite negative pole material.
A kind of specific preparation method of anthracite, SiO and P composite negative pole material:
The first step, the anthracite by phosphorus content greater than 97% carries out mechanical ball mill processing, by adjusting ball milling parameter, by nothing
Bituminous coal mean particle size is controlled at 0.5 micron or less;
Anthracite micro mist after ball milling is placed in nitration mixture, is stirred to react 3-5 h, to remove by second step
Remove the metal impurities in anthracite.After reaction, it is dried after being filtered, washed to filtrate and being in neutrality.
Anthracite of the second step after dry is placed in high-temperature atmosphere sintering furnace, carries out under nitrogen protection high by third step
4-8h(1000-1500 DEG C of temperature processing) to remove the volatile impurity in anthracite, it is spare after cooling, screening.
4th step, by 0.6 ~ 1.1 μm of anthracite after third step high-temperature process and SiO(average grain diameter) and it is elemental phosphorous in argon gas
Protection is lower to carry out high-energy ball milling, carries out 4h(900 DEG C of high temperature sintering under nitrogen protection later), nothing is obtained after cooling, screening
Bituminous coal/silicon monoxide/phosphorus composite negative pole material.
Anthracite/silicon monoxide/phosphorus the composite negative pole material and existing lithium ion battery silicon-carbon prepared through the invention
Negative electrode material is compared, and has following outstanding feature:
1. anthracite/silicon monoxide/phosphorus composite negative pole material prepared by the present invention has been remained to when SiO content is more than 20%
Effect ground inhibits the volume expansion of SiO.
2. anthracite/silicon monoxide/phosphorus composite negative pole material prepared by the present invention has excellent volumetric properties, cyclicity
Energy and high rate performance.
Anthracite/silicon monoxide/phosphorus composite negative pole material first charge discharge efficiency with higher prepared by 3..
4. material preparation cost is low, preparation method is easy to operate, environment friendly and pollution-free.
Detailed description of the invention
Figure is first is that anthracite/silicon monoxide/phosphorus composite negative pole material X-ray diffracting spectrum in embodiment two.
Figure is second is that anthracite/silicon monoxide/phosphorus composite material prepares the charging and discharging curve of battery in embodiment two.
Figure is third is that prepare battery in 500 mA/g high currents with anthracite/silicon monoxide/phosphorus composite material in embodiment two
Under the conditions of charge-discharge performance curve.
Specific embodiment
Comparative example: the anthracite by phosphorus content greater than 97% carries out high-energy ball milling processing, by adjusting ball milling parameter, by nothing
Bituminous coal mean particle size is controlled at 0.5 micron or less;Anthracite micro mist after ball milling through high-temperature heat treatment 4-8h(1000 ~
1500 DEG C) afterwards it is cooling, sieve, the high-energy ball milling 8-12 h together with SiO later, then resulting materials are placed in tube furnace 900 DEG C
It is sintered 2-5h, presses the mass ratio of 8:1:1 in N- methyl pyrrole with acetylene black, Kynoar (PVdF) after, screening cooling after material
Slurry is made in pyrrolidone (NMP) medium, is coated on copper foil, by drying, rushes film and working electrode is made in press mold.With metal
Lithium piece is to electrode, and polypropylene is diaphragm, and 1M LiPF6 is electrolyte, is carried out constant current charge-discharge test (0.1 A/g), voltage model
It encloses for 0-3.0 V.Electric discharge (embedding lithium) specific capacity is 873.8mAh/g for the first time, and initial charge (de- lithium) specific capacity is 584.4mAh/
G, coulombic efficiency 66.89%, 50 times circulation after electric discharge (embedding lithium) specific capacity be 445.1mAh/g, initial charge (de- lithium) specific volume
Amount is 442.2mAh/g, capacity retention ratio 75.67%.Illustrate only to bear using anthracite/SiO composite material as lithium ion battery
Pole material, reversible capacity are lower.
Embodiment one
By anthracite through Mechanical Crushing, chemical subtraction, 1000 ~ 1500 DEG C of high-temperature process 4-8h, by gained after cooling, screening
Anthracite and SiO and simple substance P be put into high energy ball mill in the ratio of 7C/2SiO/1P (that is, anthracite 0.7g, SiO 0.2g,
Elemental phosphorous 0.1g), then resulting materials are put under tube furnace nitrogen atmosphere by 10 h of high-energy ball milling under argon atmosphere protection
By the electrode preparation method of resulting material, battery assembly and test condition with relatively after 900 DEG C of sintering 4h, then cooling, screening
Example.Embedding lithium capacity is 1058.1mAh/g for the first time, and taking off lithium capacity for the first time is 680.4mAh/g;Embedding lithium capacity is after 50 circulations
468.0mAh/g, taking off lithium capacity is 467.6mAh/g, capacity retention ratio 68.72%.Illustrate by adding a certain amount of P, it can
The reversible capacity of material is effectively improved, but cycle performance declines.
Embodiment two
Anthracite Mechanical Crushing, chemical subtraction (are cleaned into HNO with the mixed liquor of nitric acid and sulfuric acid3:H2SO4=1:1), with height
1000 ~ 1500 DEG C of high-temperature process 4-8h of wet atmosphere tube furnace (CVD furnace) sieve to obtain anthracite after cooling with 300 mesh sieve
Raw material;
The Zirconia beads (ratio of grinding media to material 15:1) for weighing SiO and 75g that 5g purity is 99.99% are put into togerther high-energy ball milling
It in tank, places into and is filled with argon gas in glove box, high-energy ball milling (1200 revs/min) 10-20h obtains partial size and is under argon atmosphere protection
0.6 ~ 1.1 μm of SiO(Ball-milling Time is too long or the too short partial size that can all influence SiO, and the particle size of SiO will have a direct impact on whole
The chemical property of a material);
The Zirconia beads (ratio of grinding media to material 15:1) for weighing the elemental phosphorous and 75g that 5g purity is 99.99% are put into togerther high energy ball
It in grinding jar, places into and is filled with argon gas in glove box, high-energy ball milling (1200 revs/min) 20-24h obtains partial size under argon atmosphere protection
For 1.1 ~ 2.0 μm elemental phosphorous, (Ball-milling Time is too long or too short can all influence elemental phosphorous partial size, elemental phosphorous particle size
It will have a direct impact on the chemical property of entire material);
After the above-mentioned SiO of strict control and elemental phosphorous partial size, above-mentioned anthracite and SiO and simple substance P are pressed into 6C/3SiO/1P
The ratio of (that is: 0.6g anthracite, 0.3gSiO and 0.1g phosphorus) is put into high-energy ball milling tank, is then placed in glove box and is filled with argon
Gas, 10 h of high-energy ball milling under argon atmosphere protection.Resulting materials are placed into the lower 900 DEG C of sintering 4h of tube furnace nitrogen atmosphere,
By the same comparative example of the electrode preparation method of resulting material, battery assembly and test condition after to be cooled, 300 meshes point.For the first time
Embedding lithium capacity is 1052.9mAh/g, and taking off lithium capacity for the first time is 763.2mAh/g, first charge discharge efficiency 72.48%;It is embedding after 50 circulations
Lithium capacity is 613.2mAh/g, and taking off lithium capacity is 610.2mAh/g, capacity retention ratio 79.95%.Illustrate by adjusting smokeless
The proportion of coal, SiO and P, can more effectively improve the reversible capacity of material, and cycle performance is also effectively improved.Figure
First is that with anthracite, SiO and the elemental phosphorous X-ray diffracting spectrum for preparing composite negative pole material in embodiment two.It can be with from figure
Find out, 1200 DEG C of anthracites there are weaker graphite peaks, and SiO, without apparent characteristic peak, determines on X-ray diffracting spectrum for nothing
Form.
Figure is second is that preparing the charging and discharging curve of battery in embodiment two with anthracite, SiO and simple substance phosphorus composite material and following
Ring performance curve.There it can be seen that the cycle performance curve of anthracite, SiO and elemental phosphorous composite negative pole material is shown: multiple
The charging/discharging voltage curve for closing negative electrode material discharges (embedding lithium) platform in 0.5 V or so for the first time, this is flat for the characteristic discharge of SiO
Platform, charging and discharging curve hereafter do not have apparent charge and discharge platform, are the charging and discharging curves of typical amorphous state material
Figure with anthracite, SiO and simple substance phosphorus composite material third is that prepare the big multiplying power of 500 mA/g of battery in embodiment two
Charge-discharge performance curve.There it can be seen that anthracite, SiO and elemental phosphorous composite negative pole material are in the big multiplying power electricity of 500 mA/g
Loop test figure is flowed down, charging curve and discharge curve are almost overlapped, which does not almost have as charge and discharge carry out capacity
Have loss, show: the composite material has excellent cyclical stability and excellent high rate performance.
Embodiment three
By anthracite through Mechanical Crushing, chemical subtraction, 1000 ~ 1500 DEG C of high-temperature process 4-8h, by institute after cooling, screening
It obtains anthracite and SiO and simple substance P is put into high energy ball mill in the ratio of 5C/4SiO/1P (that is, anthracite 0.5g, SiO are
0.4g, elemental phosphorous 0.1g), then resulting materials are put into tube furnace nitrogen gas by 10 h of high-energy ball milling under argon atmosphere protection
It is after the lower 900 DEG C of sintering 4h of atmosphere, then cooling, screening that the electrode preparation method of resulting material, battery assembly and test condition is same
Comparative example.Embedding lithium capacity is 1077.9 mAh/g for the first time, and taking off lithium capacity for the first time is 762.0 mAh/g, first charge discharge efficiency 70.70%;
Embedding lithium capacity is 594.7 mAh/g after 50 circulations, and taking off lithium capacity is 590.5 mAh/g, capacity retention ratio 77.49%.Explanation
By adjusting the proportion of anthracite, SiO and P, the reversible capacity of material can be more effectively improved, cycle performance is also had
It improves on effect ground.