A kind of preparation method and application of the porous negative electrode material for lithium ion batteryTechnical field
The invention belongs to technical field of lithium ion battery negative, and in particular to a kind of for the porous of lithium ion batteryThe preparation method and application of negative electrode material.
Background technique
Lithium ion battery is since its specific energy is big, operating voltage is high, stable circulation is good, can be quickly charged and discharged and without environment dirtThe advantages that dye, has obtained more concern.And the performance of lithium ion battery is largely determined by the electrode material of lithium ion batteryMaterial.Ion cathode material lithium can be divided into three classes according to its mechanism, lithium ion embedded category cathode, shift to new management mechanisms cathode and alloy machineCathode processed.Wherein, the theoretical capacity of the embedded cathode of the tradition such as graphite, lithium titanate only has 372mAh/g and 175mAh/g respectively.With the development of lithium ion battery, the cathode such as conventional graphite and lithium carbonate can gradually be born by other with high capacity high stabilityPole material replaces.
Currently, as the germanium and silicon for being all IVA race element being all that good lithium ion is negative compared with graphite negative electrodes materialPole material, and the capacity of this two is above graphite.In germanium and silicon alloy, the capacity (4200mAh/g) of silicon is higher than germaniumCapacity (1600mAh/g)；And germanium is lower than the forbidden bandwidth (1.12eV) of silicon due to its forbidden bandwidth (0.67eV), so germanium conductsThe ability of electronics is better than silicon.Therefore, research germanium-silicon alloy negative electrode material can be utilized respectively their advantage, both improve battery appearanceAmount improves conductivity again.However germanium silicium cathode material can have big volume expansion (about 400%) during the charging process, makeActive materials dusting falls off, to destroy the structure of material, reduce the embedding lithium ability of material, causes the stability of batteryAnd safety is unable to reach using standard, furthermore established SEI film holds in circulation volume expansion every time with during contractionIt easily ruptures, germanium-silicon alloy is made directly to generate new SEI film with electrolyte contacts.There is insulating property (properties) after being repeatedly circulated throughoutSEI film progressive additive, reduce the electro-chemical activity of material, cause capacitance loss.Therefore making for germanium silicium cathode material is improvedWith service life (cyclical stability) and safety, it is necessary to which the volume expansion for reducing germanium-silicon alloy damages performance bring.
In the prior art, it is negative to disclose a kind of compound porous silicon of the carbon nanotube for lithium ion battery by CN106058256AThe preparation method of pole material.The invention mainly includes that thermal reduction prepares porous silicon, chemical vapour deposition technique carries out porous siliconCarbon coating and composite carbon nanometer tube, acid processing removal iron catalyst.The invention is using works such as thermal reduction, chemical vapour deposition techniquesSkill keeps the material preparation process period long, low output；And the magnesium powder in experimentation is inflammable and explosive, there are security risks.CN103985836A discloses a kind of method that germanium negative electrode material is prepared on nickel nanoneedle cone array.The invention is first Ni-basedMethod on body using aqueous solution electro-deposition prepares the nickel nanoneedle cone array of certain altitude, then the environment hydrophobic in anaerobismIn, germanium negative electrode material is prepared on nickel nano needle arrays using the method for ionic liquid electrodeposition.The germanium particle of this method preparationSize is larger, material porosity is not high, and preparation process is complicated, long preparation period, low output.(the Nano Energy such as S.Liu2015,13:651-657) nanoporous germanium is prepared using de- alloying technology, by it as the cathode of high performance lithium ion batteryMaterial, compared to silicon, the capacity of germanium is lower, and Ge content is more (for 28.4at.%) in its presoma alloy use, cost compared withIt is high.
Summary of the invention
The purpose of the present invention is above-mentioned to solve the problems, such as, a kind of porous cathode material for lithium ion battery is providedThe characteristics of preparation method and application of material, this method is dissolved mutually using germanium and silicon, bimodal receive is prepared in conjunction with de- alloy approachMeter Duo Kong germanium-silicon alloy, this material show higher specific capacity and cyclical stability as the negative electrode material of lithium ion battery.
Technical solution of the present invention:
A kind of preparation method of the porous negative electrode material for lithium ion battery, steps are as follows:
1) preparation of Ge-Si-Al alloy pig
It is the germanium block of 99.99wt%, silicon grain, aluminium block as raw material using purity, according to subject alloy ingredientGexSixAl100-2xAtomic ratio stock up, wherein 8≤x≤11, when stock the standby amount of raw material respectively multiplied by a correction factor, withComposition tolerances caused by scaling loss when cutting down alloy melting, the correction factor are respectively germanium 1.01, silicon 1.02, aluminium 1.05, are incited somebody to actionLoad weighted raw material use arc melting method melting, and vacuum degree is evacuated to 9 × 10 after material shove charge-4Pa then passes to high-purity argonGas is first smelted into primary alloy ingot to -0.05MPa, by germanium and silicon, the independent melting ingot of aluminium, then by two groups of alloy pig meltings together,Melt back 4 times to guarantee material refining uniformly, material with cold-crucible it is cooling after, obtain the Ge-Si-Al alloy refinedIngot；
2) preparation of alloy presoma band is taken off
Above-mentioned alloy pig is put into quartz test tube, quartz ampoule nozzle diameter 1.1mm, quartz ampoule nozzle away from copper roll spacing from2.1mm, induction heating melt alloy pig, are then quickly blown out the alloy of melting using argon gas, blow casting pressure and are0.085MPa, quickly solidification forms alloy strip to the liquid alloy of melting on 3580 revs/min of revolving speed of copper roller, and band is madeWidth be 2.3mm, with a thickness of 26 μm, as de- alloy presoma band；
3) preparation of bimodal nanoporous germanium-silicon alloy
De- alloy presoma band obtained above is placed in the hydrogen-oxygen that concentration is 2.0~2.3M, temperature is 63~67 DEG CChange in sodium solution, freely takes off 400~420min of alloy, de- alloy product is pulled out cleaned repeatedly with deionized water after reaction2 times, the remaining sodium hydroxide of sample surfaces is removed, de- alloy product is separated with centrifuge, is then being dried in vacuo productDried under 60 DEG C, -0.1Mpa in case, finally by bimodal nanoporous negative electrode material obtained be placed in vacuum degree be -0.1Mpa,It is retained in the drying box that temperature is 25 DEG C spare.
A kind of application of the prepared porous negative electrode material for lithium ion battery, for assembling half-cell.
The preparation method of the above-mentioned porous negative electrode material for lithium ion battery, raw material used and equipment pass through public affairsThe approach known obtains, and operating procedure used is that those skilled in the art can grasp.
Beneficial effects of the present invention and substantive distinguishing features outstanding are:
The characteristics of present invention can be dissolved completely using germanium and silicon, prepares bimodal nanoporous germanium silicon in conjunction with de- alloy approachAlloy material of cathode, this material combines the electronics conduction velocity of germanium with the embedding lithium ability height of silicon fastly, as lithium-ion electricWhen the negative electrode material in pond, higher cyclical stability and specific capacitance, while the nano-porous structure porosity of the material are shownIt is higher, pitch of holes be suitable for, can buffers active substance charging when volume expansion, further enhance the circulation longevity of negative electrode materialLife.And have the characteristics that cost of material is low, preparation process is simple, process cycle is short, overcome prior art processes complexity, productionThe disadvantages of period is long, energy consumption is high, material cost is high, low output.
Compared with prior art, marked improvement of the invention is as follows:
1. operation of the present invention condition is simple, require environmental condition low (normal temperature and pressure), requires low, preparation to working equipmentPeriod is short, yield is high, material preparation cost is low；
2. the porous anode material capacity of the present invention is high, potential plateau is low, is suitably applied negative electrode of lithium ion battery；
3. negative electrode material of the invention is bimodal nano-porous structure, enough spaces are provided for the expansion of material, are droppedGenerated stress when low material expansion reduces dusting and the degree to fall off, the cycle life for improving negative electrode material；
4. the advantages of the invention comprehensively utilizes silicon and germanium improves anode material capacity with pure germanium metal phase ratio, reduceThe cost of raw material, improves the electric conductivity of negative electrode material, and then increase the cyclical stability of material compared with pure silicon material.
Detailed description of the invention
Fig. 1 is the XRD spectrum of presoma alloy strip made from embodiment 1.
Fig. 2 is the XRD spectrum that alloy product is taken off made from embodiment 1.
Fig. 3 is the stereoscan photograph that alloy product is taken off made from embodiment 1.
Fig. 4 is the charging and discharging curve that 1 gained negative electrode material of embodiment is packaged into lithium ion battery.
Fig. 5 is the cycle performance and coulombic efficiency that 1 gained negative electrode material of embodiment is packaged into lithium ion battery.
Specific embodiment
Present invention will be further explained below with reference to the attached drawings and examples.
Embodiment 1:
A kind of preparation method of the porous negative electrode material for lithium ion battery, steps are as follows:
1) preparation of Ge-Si-Al alloy pig
It is the germanium block of 99.99wt%, silicon grain, aluminium block as raw material using purity, according to subject alloy ingredientGe10Si10Al80Atomic ratio stock up, the standby amount of raw material is respectively multiplied by a correction factor when stock, when cutting down alloy meltingScaling loss caused by composition tolerances.The scaling loss testing result obtained according to inventor's many experiments, correction factor are respectively germanium1.01, load weighted raw material are used arc melting method melting by silicon 1.02, aluminium 1.05.After material shove charge vacuum degree be evacuated to 9 ×10-4Pa then passes to high-purity argon gas and germanium and silicon is first smelted into primary alloy ingot, the independent melting ingot of aluminium to -0.05MPa, then incites somebody to actionTwo groups of alloy pig meltings together, melt back 4 times to guarantee material refining uniformly, material with cold-crucible it is cooling after, refinedThe Ge-Si-Al alloy pig made.
2) preparation of alloy presoma band is taken off
Above-mentioned alloy pig is put into quartz test tube, quartz ampoule nozzle diameter 1.1mm, quartz ampoule nozzle away from copper roll spacing from2.1mm, induction heating melt alloy pig, are then quickly blown out the alloy of melting using argon gas, blow casting pressure and are0.085MPa, quickly solidification forms alloy strip to the liquid alloy of melting on 3580 revs/min of revolving speed of copper roller, and band is madeWidth be about 2.3mm, thickness is about 26 μm, as de- alloy persursor material.The XRD spectrum of presoma alloy strip is as schemedShown in 1, it is evident that the crystal peak of Ge, Si, Al, illustrate that material is Ge-Si-Al ternary alloy three-partalloy；
3) preparation of bimodal nanoporous germanium-silicon alloy
Presoma alloy strip obtained above is placed in the sodium hydroxide solution that concentration is 2.1M, temperature is 65 DEG C,Alloy 410min is freely taken off, de- alloy product is pulled out cleaned repeatedly with deionized water 2 times after reaction, removes sample surfacesRemaining sodium hydroxide is separated de- alloy product with centrifuge, then by product in a vacuum drying oven in 60 DEG C drying after,Last nanoporous negative electrode material obtained is placed in the drying box that vacuum degree is -0.1Mpa, temperature is 25 DEG C retain it is spare.
Fig. 2 is the XRD diagram piece of de- alloy product, the peak of Ge, Si is only detected in map, and in part Ge solid solution and Si,So that its diffraction maximum is broadened, but the peak of Al is not detected, Al element all filters out after illustrating de- alloy.Fig. 3 is de- alloy productStereoscan photograph.It is clear that the bimodal porous structure that material is made of hole/ligament of fine uniform in figure, oneAbout 0.5~1.6 μm of macropore diameter of grade, second level small aperture about 40~60nm.Last nanoporous negative electrode material obtained is setIt is -0.1MPa in vacuum degree, is retained in the drying box that temperature is 25 DEG C spare.
The assembling half-cell of the nanoporous germanium silicium cathode material made from the present embodiment is simultaneously tested for the property, and method is:
1) half-cell assembles: being that 7:2:1 weighs nanoporous germanium silicium cathode material prepared by the present invention respectively with mass ratioMaterial, conductive black and binder sodium carboxymethylcellulose instill ultrapure water and paste are made, be uniformly applied to copper foil after being fully groundOn, cathode is used as after dry.Using 1M LiPF6As electrolyte, metal lithium sheet is used as to electrode, porous polypropylene(Celgard) make diaphragm, carry out cell package.
2) battery performance test: 1) battery of assembling is tested for the property.Fig. 4 is the charge and discharge that battery is made in the present embodimentElectrical testing curve, as seen from the figure, the electric discharge of battery first circle, charging capacitor amount are respectively 2776.2mAh/g and 2447.3mAh/g, libraryHuman relations efficiency is 88.15%.Fig. 5 is cycle performance of battery and coulombic efficiency test result, and as seen from the figure, battery illustrates goodCapacity performance, circulation is after 20 weeks, and charge/discharge capacity maintains 2200mAh/g or so, and coulombic efficiency is maintained at 99.6% or more.
Embodiment 2:
A kind of preparation method of the porous negative electrode material for lithium ion battery, steps are as follows:
1) Ge-Si-Al alloy pig prepare it is substantially the same manner as Example 1, the difference is that: subject alloy ingredient isGe8Si8Al84；
2) preparation for taking off alloy presoma band is identical with embodiment 1；
3) preparation of bimodal nanoporous germanium-silicon alloy
Presoma alloy strip obtained above is placed in the sodium hydroxide solution that concentration is 2.0M, temperature is 63 DEG C,Alloy 400min is freely taken off, de- alloy product is pulled out cleaned repeatedly with deionized water 2 times after reaction, removes sample surfacesRemaining sodium hydroxide is separated de- alloy product with centrifuge, then by product in a vacuum drying oven in 60 DEG C drying after,It is -0.1MPa that last bimodal nanoporous negative electrode material obtained, which is placed in vacuum degree, is retained in the drying box that temperature is 25 DEG CIt is spare.The peak of Ge, Si are only detected in the XRD detection of de- alloy product, and Ge solid solution in part becomes its diffraction maximum with SiWidth, but the peak of Al is not detected, Al element all filters out after illustrating de- alloy.The de- alloy product is mainly by fine uniformHole/ligament composition bimodal porous structure, about 0.7~1.8 μm of level-one macropore diameter, second level small aperture about 50~80nm.It is -0.1MPa that last nanoporous negative electrode material obtained, which is placed in vacuum degree, is retained in the drying box that temperature is 25 DEG C spare.
The assembling half-cell of the nanoporous germanium silicium cathode material made from the present embodiment is simultaneously tested for the property, and method is:
1) half-cell assembles: being that 7:2:1 weighs nanoporous germanium silicium cathode material prepared by the present invention respectively with mass ratioMaterial, conductive black and binder sodium carboxymethylcellulose instill ultrapure water and paste are made, be uniformly applied to copper foil after being fully groundOn, cathode is used as after dry.Using 1M LiPF6As electrolyte, metal lithium sheet is used as to electrode, porous polypropylene(Celgard) make diaphragm, carry out cell package.
2) battery performance test: 1) battery of assembling is tested for the property.The charge-discharge test curve of battery shows electricityThe electric discharge of pond first circle, charging capacitor amount are respectively 2753.3mAh/g and 2432.7mAh/g, coulombic efficiency 88.36%.Battery followsRing performance and coulombic efficiency test result show good capacity performance, and after 20 weeks, charge/discharge capacity is kept at circulation2200mAh/g or so, coulombic efficiency are maintained at 99.7% or more.
Embodiment 3:
A kind of preparation method of the porous negative electrode material for lithium ion battery, steps are as follows:
1) Ge-Si-Al alloy pig prepare it is substantially the same manner as Example 1, the difference is that: subject alloy ingredient isGe11Si11Al78；
2) preparation for taking off alloy presoma band is identical with embodiment 1；
3) preparation of bimodal nanoporous germanium-silicon alloy
Presoma alloy strip obtained above is placed in the sodium hydroxide solution that concentration is 2.3M, temperature is 67 DEG C,Alloy 420min is freely taken off, de- alloy product is pulled out cleaned repeatedly with deionized water 2 times after reaction, removes sample surfacesRemaining sodium hydroxide is separated de- alloy product with centrifuge, then by product in a vacuum drying oven in 60 DEG C drying after,It is -0.1MPa that last nanoporous negative electrode material obtained, which is placed in vacuum degree, is retained in the drying box that temperature is 25 DEG C spare.The peak of Ge, Si are only detected in the XRD detection of de- alloy product, and Ge solid solution in part makes its diffraction maximum broaden, but not with SiThe peak for detecting Al, Al element all filters out after illustrating de- alloy.The de- alloy product is mainly by the hole of fine uniform/toughBimodal porous structure with composition, about 0.4~1.5 μm of level-one macropore diameter, second level small aperture about 30~60nm.It will finally makeIt is -0.1MPa that the nanoporous negative electrode material obtained, which is placed in vacuum degree, is retained in the drying box that temperature is 25 DEG C spare.
The assembling half-cell of the nanoporous germanium silicium cathode material made from the present embodiment is simultaneously tested for the property, and method is:
1) half-cell assembles: being that 7:2:1 weighs nanoporous germanium silicium cathode material prepared by the present invention respectively with mass ratioMaterial, conductive black and binder sodium carboxymethylcellulose instill ultrapure water and paste are made, be uniformly applied to copper foil after being fully groundOn, cathode is used as after dry.Using 1M LiPF6As electrolyte, metal lithium sheet is used as to electrode, porous polypropylene(Celgard) make diaphragm, carry out cell package.
2) battery performance test: 1) battery of assembling is tested for the property.The charge-discharge test curve of battery shows electricityThe electric discharge of pond first circle, charging capacitor amount are respectively 2755.8mAh/g and 2436.9mAh/g, coulombic efficiency 88.43%.Battery followsRing performance and coulombic efficiency test result show good capacity performance, and after 20 weeks, charge/discharge capacity is kept at circulation2200mAh/g or so, coulombic efficiency are maintained at 99.6% or more.
Comparative example 1:
By Ge5Si5Al90(atomic ratio) alloy is prepared into band, and other conditions are with embodiment 1, as the result is shown: very fewAfter germanium, element silicon make de- alloy treatment, continuous ligament structure can not be formed, obtains the granular material of germanium and silicon mixing, notThe negative electrode material of nano-porous structure is obtained, on the one hand granular germanium silicium cathode material drops material electronics transfer ability significantlyIt is low, serious volume expansion can be led to the problem of when on the other hand charging, makes the reduction of circulating battery stability.Therefore the material is uncomfortablePreferably it is used as high performance lithium ionic cell cathode material.
Comparative example 2:
By Ge15Si15Al70(atomic ratio) alloy is prepared into band, and other conditions are with embodiment 1, as the result is shown: excessiveGermanium, element silicon keep de- alloy reaction insufficient, can not form the ligament structure of continuous effective, material ligament broadens, porosity dropsLow, it is even more impossible to obtain the negative electrode material of bimodal nano-porous structure, volume expansion when cannot charge for germanium silicium cathode material is mentionedFor sufficient space, make the reduction of circulating battery stability.Therefore the material is not suitable for as high performance lithium ionic cell cathode materialMaterial.
Comparative example 3:
By Ge10Si10Al80(atomic ratio) alloy is prepared into band, and band is placed in concentration is 2.5M, temperature is 60 DEG CIn sodium hydroxide solution, alloy 450min is freely taken off, it is more to be unable to get bimodal nanometer with embodiment 1 as the result is shown for other conditionsPorous materials, volume expansion when cannot charge for germanium silicium cathode material provide sufficient space, make the reduction of circulating battery stability.Therefore the material is not suitable for as high performance lithium ionic cell cathode material.
Above embodiments and comparative example illustrate that lithium ion battery with the preparation method of porous negative electrode material is by continuousThe different ratio of alloy, strict control alloy preparation condition and de- alloying technology are attempted, is repeatedly practiced, finally developing hasThe negative electrode material of bimodal nano-porous structure.
Raw material used in above-described embodiment and equipment pass through well known approach and obtain, and operating procedure used is thisWhat those skilled in the art can grasp.