Summary of the invention
In view of this, the present invention is directed to the disappearance of prior art existence, its main purpose is to provide a kind of nitrating carbon coated graphite negative material and preparation method thereof, which introduce ionic liquid as carbon source, make the coated with uniform of graphite material one deck nitrating material with carbon element, the method is simple to operation, is very applicable to large-scale production.
For achieving the above object, the present invention adopts following technical scheme:
A kind of nitrating carbon coated graphite negative material, is made up of the raw material of following weight proportion: graphite 80% ~ 95%; Ionic liquid 5% ~ 20%; Wherein ionic liquid is evenly coated on the outer surface of graphite, forms core shell structure.
As a kind of preferred version, described graphite is at least one in native graphite, Delanium.
A preparation method for nitrating carbon coated graphite negative material, includes following steps:
(1) coated: to take graphite and ionic liquid, join in homogenizer, use rotating speed 500 ~ 5000 r/min to carry out dispersion 1 ~ 4h, obtaining after having processed is coated with the graphite of ionic liquid;
(2) carbonization: the graphite being coated with ionic liquid is placed in atmosphere protection stove and sinters, rises to 400 ~ 1000 DEG C with the heating rate of 2 ~ 25 DEG C/min and is incubated 4 ~ 18 hours, obtains nitrating carbon coated graphite negative material.
As a kind of preferred version, described ionic liquid is at least one in the two fluoroform sulfimide salt of N-methyl butyl pyrrolidines, the two fluoroform sulfimide salt of N-methyl butyl piperidines, the two fluoroform sulfimide salt of 1-ethyl-3-methylimidazole, 1-ethyl-3-methylimidazole tetrafluoroborate, the two fluoroform sulfimide salt of trimethyl third ammonium and the two fluoroform sulfimide salt of 1-hexyl-3-methylimidazole.
As a kind of preferred version, the purity of described ionic liquid is more than or equal to 98%, and wherein the mol ratio of nitrogen and carbon is 2:9 ~ 6:9.
As a kind of preferred version, the protective atmosphere used in described atmosphere protection stove is selected from least one in helium, nitrogen, argon gas, carbon dioxide.
As a kind of preferred version, described nitrating carbon coated graphite negative material has spherical morphology, coated with uniform one deck nitrating material with carbon element.
The present invention compared with prior art has obvious advantage and beneficial effect, specifically, as shown from the above technical solution:
1, by adopting ionic liquid, compared with traditional solid-state carbon source presoma, ionic liquid more easily gos deep in graphite surface hole owing to having flowing property, be conducive to significantly reducing specific area, and under lower vapour pressure, crack temperature range wider (400 ~ 1000 DEG C), also not with solvent evaporation fast, these are all conducive to forming uniform coated thin layer on graphite granule surface, thus be conducive to significantly improving compacted density and the performance such as efficiency first, graphite cathode material of the present invention has relatively higher compacted density, specific capacity, efficiency first, solve artificial graphite material actual prepare the application of cathode of lithium battery time the irreversible capacity loss that exists large, the problem that specific capacity is lower,
2, ionic liquid is not only carbon source, also be nitrogenous source, while Graphite Coating carbon, also nitrogen element is doped with, graphite surface is coated through N doping carbon-coating, also be conducive to improving its surface stability while the electron conduction improving material, thus have excellent high rate performance and cycle performance, thus can be applied in the electrokinetic cell of high performance requirements better.
3, the viscosity of ionic liquid is comparatively large, has wetting action, makes graphite material prevented from caking in carbonisation, gone the carbonization operation of breaing up less, and made coated process simplification graphite surface, and preparation cost declines.
4, present invention process is simple, and easy to operate, production equipment is few, thus reduces costs further, easy to utilize, is suitable for large-scale production.
Embodiment
The present invention discloses a kind of nitrating carbon coated graphite negative material, and it is made up of the raw material of following weight proportion: graphite 80% ~ 95%; Ionic liquid 5% ~ 20%; Wherein ionic liquid is evenly coated on the outer surface of graphite, forms core shell structure.This graphite is at least one in native graphite, Delanium.
The preparation method that nitrating carbon coated graphite negative material is described in detail in detail is as follows, includes following steps:
(1) coated: to take graphite and ionic liquid, join in homogenizer, use rotating speed 500 ~ 5000 r/min to carry out dispersion 1 ~ 4h, obtaining after having processed is coated with the graphite of ionic liquid; This ionic liquid is at least one in the two fluoroform sulfimide salt of N-methyl butyl pyrrolidines, the two fluoroform sulfimide salt of N-methyl butyl piperidines, the two fluoroform sulfimide salt of 1-ethyl-3-methylimidazole, 1-ethyl-3-methylimidazole tetrafluoroborate, the two fluoroform sulfimide salt of trimethyl third ammonium and the two fluoroform sulfimide salt of 1-hexyl-3-methylimidazole, the purity of this ionic liquid is more than or equal to 98%, and wherein the mol ratio of nitrogen and carbon is 2:9 ~ 6:9.
Compared with traditional solid-state carbon source presoma, ionic liquid more easily gos deep in graphite surface hole owing to having flowing property, be conducive to significantly reducing specific area, and under lower vapour pressure, crack temperature range wider (400-1000 DEG C), also with the evaporation of solvent fast, these are all conducive to forming uniform coated thin layer on graphite granule surface, thus are conducive to significantly improving compacted density and the performance such as efficiency first; Ionic liquid is not only carbon source, also be nitrogenous source, while Graphite Coating carbon, also nitrogen element is doped with, graphite surface is coated through N doping carbon-coating, also be conducive to improving its surface stability while the electron conduction improving material, thus have excellent high rate performance and cycle performance; The viscosity of ionic liquid is comparatively large, and have wetting action to graphite surface, make graphite material prevented from caking in carbonisation, gone the carbonization operation of breaing up less, and made coated process simplification, preparation cost declines.
(2) carbonization: the graphite being coated with ionic liquid is placed in atmosphere protection stove and sinters; rise to 400 ~ 1000 DEG C with the heating rate of 2 ~ 25 DEG C/min and be incubated 4 ~ 18 hours; obtain nitrating carbon coated graphite negative material; this nitrating carbon coated graphite negative material has spherical morphology, coated with uniform one deck nitrating material with carbon element.The protective atmosphere used in this atmosphere protection stove is selected from least one in helium, nitrogen, argon gas, carbon dioxide.
The present invention will be described to use specific embodiment and comparative example below, and " part " that following examples use is based on weight.
Embodiment 1
(1) coated: to take 80 parts of graphite and 20 parts of ionic liquids, join in homogenizer, use rotating speed 500r/min to carry out dispersion 4h, obtaining after having processed is coated with the graphite of ionic liquid; This ionic liquid is the two fluoroform sulfimide salt of N-methyl butyl pyrrolidines, and the purity of this ionic liquid is 98%, and wherein the mol ratio of nitrogen and carbon is 2:9.
(2) carbonization: the graphite being coated with ionic liquid is placed in atmosphere protection stove and sinters; rise to 400 DEG C with the heating rate of 2 DEG C/min and be incubated 8 hours; obtain nitrating carbon coated graphite negative material; this nitrating carbon coated graphite negative material has spherical morphology, coated with uniform one deck nitrating material with carbon element.The protective atmosphere used in this atmosphere protection stove is selected from helium.
Embodiment 2
(1) coated: to take 82 parts of graphite and 18 parts of ionic liquids, join in homogenizer, use rotating speed 1000 r/min to carry out dispersion 2h, obtaining after having processed is coated with the graphite of ionic liquid; This ionic liquid is the two fluoroform sulfimide salt of N-methyl butyl piperidines, and the purity of this ionic liquid is 99%, and wherein the mol ratio of nitrogen and carbon is 3:9.
(2) carbonization: the graphite being coated with ionic liquid is placed in atmosphere protection stove and sinters; rise to 800 DEG C with the heating rate of 8 DEG C/min and be incubated 7 hours; obtain nitrating carbon coated graphite negative material; this nitrating carbon coated graphite negative material has spherical morphology, coated with uniform one deck nitrating material with carbon element.The protective atmosphere used in this atmosphere protection stove is selected from nitrogen.
Embodiment 3
(1) coated: to take 85 parts of graphite and 15 parts of ionic liquids, join in homogenizer, use rotating speed 5000 r/min to carry out dispersion 1h, obtaining after having processed is coated with the graphite of ionic liquid; This ionic liquid is the two fluoroform sulfimide salt of 1-ethyl-3-methylimidazole, and the purity of this ionic liquid is 98.5%, and wherein the mol ratio of nitrogen and carbon is 4:9.
(2) carbonization: the graphite being coated with ionic liquid is placed in atmosphere protection stove and sinters; rise to 1000 DEG C with the heating rate of 25 DEG C/min and be incubated 4 hours; obtain nitrating carbon coated graphite negative material; this nitrating carbon coated graphite negative material has spherical morphology, coated with uniform one deck nitrating material with carbon element.The protective atmosphere used in this atmosphere protection stove is selected from argon gas.
Embodiment 4
(1) coated: to take 88 parts of graphite and 12 parts of ionic liquids, join in homogenizer, use rotating speed 2000 r/min to carry out dispersion 3h, obtaining after having processed is coated with the graphite of ionic liquid; This ionic liquid is 1-ethyl-3-methylimidazole tetrafluoroborate, and the purity of this ionic liquid is 98.6%, and wherein the mol ratio of nitrogen and carbon is 5:9.
(2) carbonization: the graphite being coated with ionic liquid is placed in atmosphere protection stove and sinters; rise to 900 DEG C with the heating rate of 13 DEG C/min and be incubated 9 hours; obtain nitrating carbon coated graphite negative material; this nitrating carbon coated graphite negative material has spherical morphology, coated with uniform one deck nitrating material with carbon element.The protective atmosphere used in this atmosphere protection stove is selected from carbon dioxide.
Embodiment 5
(1) coated: to take 90 parts of graphite and 10 parts of ionic liquids, join in homogenizer, use rotating speed 1500 r/min to carry out dispersion 2h, obtaining after having processed is coated with the graphite of ionic liquid; This ionic liquid is the two fluoroform sulfimide salt of trimethyl third ammonium, and the purity of this ionic liquid is 98%, and wherein the mol ratio of nitrogen and carbon is 6:9.
(2) carbonization: the graphite being coated with ionic liquid is placed in atmosphere protection stove and sinters; rise to 950 DEG C with the heating rate of 20 DEG C/min and be incubated 7 hours; obtain nitrating carbon coated graphite negative material; this nitrating carbon coated graphite negative material has spherical morphology, coated with uniform one deck nitrating material with carbon element.The protective atmosphere used in this atmosphere protection stove is selected from helium and nitrogen.
Embodiment 6
(1) coated: to take 92 parts of graphite and 8 parts of ionic liquids, join in homogenizer, use rotating speed 3200 r/min to carry out dispersion 1.5h, obtaining after having processed is coated with the graphite of ionic liquid; This ionic liquid is the two fluoroform sulfimide salt of 1-hexyl-3-methylimidazole, and the purity of this ionic liquid is 99%, and wherein the mol ratio of nitrogen and carbon is 1:2.
(2) carbonization: the graphite being coated with ionic liquid is placed in atmosphere protection stove and sinters; rise to 860 DEG C with the heating rate of 22 DEG C/min and be incubated 13 hours; obtain nitrating carbon coated graphite negative material; this nitrating carbon coated graphite negative material has spherical morphology, coated with uniform one deck nitrating material with carbon element.The protective atmosphere used in this atmosphere protection stove is selected from argon gas and carbon dioxide.
Embodiment 7
(1) coated: to take 94 parts of graphite and 6 parts of ionic liquids, join in homogenizer, use rotating speed 4000 r/min to carry out dispersion 1.5h, obtaining after having processed is coated with the graphite of ionic liquid; This ionic liquid is the two fluoroform sulfimide salt of N-methyl butyl pyrrolidines and the two fluoroform sulfimide salt of N-methyl butyl piperidines, and the purity of this ionic liquid is 98.8%, and wherein the mol ratio of nitrogen and carbon is 4:9.
(2) carbonization: the graphite being coated with ionic liquid is placed in atmosphere protection stove and sinters; rise to 780 DEG C with the heating rate of 15 DEG C/min and be incubated 13 hours; obtain nitrating carbon coated graphite negative material; this nitrating carbon coated graphite negative material has spherical morphology, coated with uniform one deck nitrating material with carbon element.The protective atmosphere used in this atmosphere protection stove is selected from helium, nitrogen and argon gas.
Embodiment 8
(1) coated: to take 95 parts of graphite and 5 parts of ionic liquids, join in homogenizer, use rotating speed 4500 r/min to carry out dispersion 2h, obtaining after having processed is coated with the graphite of ionic liquid; This ionic liquid is the two fluoroform sulfimide salt of 1-ethyl-3-methylimidazole and 1-ethyl-3-methylimidazole tetrafluoroborate, and the purity of this ionic liquid is 99.5%, and wherein the mol ratio of nitrogen and carbon is 5.5:9.
(2) carbonization: the graphite being coated with ionic liquid is placed in atmosphere protection stove and sinters; rise to 900 DEG C with the heating rate of 10 DEG C/min and be incubated 16 hours; obtain nitrating carbon coated graphite negative material; this nitrating carbon coated graphite negative material has spherical morphology, coated with uniform one deck nitrating material with carbon element.The protective atmosphere used in this atmosphere protection stove is selected from argon gas and carbon dioxide.
Comparative example 1
Use the graphite material that pitch obtains as clad material.
Comparative example 2
Use the graphite material that phenolic resins obtains as clad material.
Electrochemical property test is carried out to foregoing individual embodiments and comparative example below:
For detecting the performance of the lithium ion battery negative material of ionic liquid coated graphite negative material of the present invention, test by half-cell method of testing, negative material by above embodiment and comparative example: SBR (solid content 50%): CMC: Super-p=95.5: 2: 1.5: 1 (weight ratio), add appropriate amount of deionized water and reconcile into pulpous state, to coat on Copper Foil and within 12 hours, to make negative plate in vacuum drying chamber inner drying, electrolyte is 1M LiPF6/EC+DEC+DMC=1: 1: 1, microporous polypropylene membrane is barrier film, be lithium sheet to electrode, be assembled into battery.Carry out constant current charge-discharge experiment at LAND battery test system, charging/discharging voltage is limited in 0.01 ~ 3.0 V, and the discharge and recharge cabinet computerizedd control carries out collection and the control of data, and the data obtained are as shown in table 1 below.
Table 1 lists the negative material Performance comparision of different embodiment and comparative example.
As can be seen from Table 1, the graphite after the coated carbonization of ionic liquid, specific area declines, and tap density improves, and every electrical property all increases significantly.This is because introduce ionic liquid as carbon source, obtain Surface coating uniform nitrating carbon coated graphite negative material.This graphite cathode material has spherical morphology, its coated with uniform one deck nitrating material with carbon element, and not only effectively improve its electronic conductivity but also enhance the surface stability of this material, the material obtained has excellent high rate performance and cycle performance.
In addition, as shown in Figure 1, graphite material is outer has evenly coatedly gone up one deck material with carbon element, smooth surface, without obvious hole, so specific area is controllably fine, thus improves the compacted density of graphite.
The above, it is only preferred embodiment of the present invention, not technical scope of the present invention is imposed any restrictions, thus every above embodiment is done according to technical spirit of the present invention any trickle amendment, equivalent variations and modification, all still belong in the scope of technical solution of the present invention.