CN106784660B

CN106784660B - Se-TiO of the nickel foam as interlayer2/ NFF lithium selenium secondary cell and preparation method thereof

Info

Publication number: CN106784660B
Application number: CN201611092222.6A
Authority: CN
Inventors: 张冬; 江琳; 张彤; 邱海龙; 陈岗; 魏英进
Original assignee: Jilin University
Current assignee: Jilin University
Priority date: 2016-12-02
Filing date: 2016-12-02
Publication date: 2019-04-05
Anticipated expiration: 2036-12-02
Also published as: CN106784660A

Abstract

A kind of Se-TiO of nickel foam as interlayer₂/ NFF lithium selenium secondary cell and preparation method thereof, belongs to technical field of lithium ion.It is that vinylpyrrolidone is dissolved in ethyl alcohol, adds glacial acetic acid and butyl titanate, stirs to get spinning solution；Spinning product is pre-oxidized, obtains TiO by then spinning under high voltage₂Nanofiber；2~8h is ground with after the mixing of Se particle, 6~12h is roasted after tabletting under the conditions of argon gas, 200~260 DEG C, obtains Se-TiO₂Nanofiber；It is mixed with conductive agent, binder, gained slurry is coated on aluminium foil, obtains Se-TiO₂Positive electrode；In Se-TiO₂NFF interlayer is added between positive electrode and diaphragm, lithium piece is used as to electrode assembling half-cell, to obtain Se-TiO of the nickel foam as interlayer₂/ NFF lithium selenium secondary cell.

Description

Se-TiO of the nickel foam as interlayer2/ NFF lithium selenium secondary cell and preparation method thereof

Technical field

The invention belongs to technical field of lithium ion, and in particular to a kind of Se-TiO of nickel foam as interlayer₂/NFF Lithium selenium secondary cell and preparation method thereof.

Background technique

High-energy density, long circulation life and low cost are the developing direction of batteries of electric automobile.Lithium-sulfur cell is because having Very high Theoretical Mass specific energy (2567Wh/kg), volume and capacity ratio (3467mAh/cm³) and low cost be considered as most answering With one of the next-generation high-specific energy battery system of prospect.But the lower high rate performance for leading to battery of the electric conductivity of sulphur is not high, And more sulphions dissolve in ethers electrolyte and cause shuttle effect, cause the stable circulation performance of battery poor.For many years, People such as consolidate the modification on sulphur, electrolyte and diaphragm by various effort, improve the electrification of lithium-sulfur cell to a certain extent Performance is learned, but itself insulating properties of its essential problem such as sulphur is not resolved.

Selenium and sulphur are located at same main group in the periodic table of elements, and selenium is expected to the substitute as lithium-sulfur cell future.Although The specific discharge capacity of selenium (675mAh/g) is lower than sulphur (1672mAh/g), but on volume and capacity ratio selenium (3253mAh/cm) with Quite, due to receiving the limitation in battery pack space, volume and capacity ratio is more important with specific discharge capacity for sulphur (3467mAh/cm). The electronic conductivity (1 × 10 of selenium^-3S/m) than sulphur (5 × 10^-28S/m) much higher, it means that active material in electrode material Load capacity is expected to much higher than sulfur-based positive electrode, and selenium has a higher utilization rate than sulphur, better electro-chemical activity, quickly with lithium ion It reacts, to realize higher practical specific energy.Therefore, selenium is expected to become the anode for being specifically applied to building high-energy battery Material, including domestic electronic appliances and means of transport.

However, selenium equally can also undergo decaying and the coulombic efficiency of the capacity as caused by the dissolution of more selenides as sulphur Reduction.In order to improve the performance of battery, people take many measures, and a kind of strategy is the selenium material of synthesis different shape structure Material, such as the nanoporous or nano-fiber material of selenium.Another strategy is selenium to be fixed in porous matrix to pass through suction It receives material and chases more selenides.It is worn in addition, also increasing by a layer interlayer between electrode slice and diaphragm equally and can also play inhibition The effect of shuttle effect.

The present invention uses nickel foam (NFF) to be placed in electrode slice and diaphragm as interlayer for the first time, and uses TiO₂As The matrix of lithium selenium cell obtains cycle performance and all good lithium selenium secondary cell of high rate performance.

Summary of the invention

Se- the purpose of the present invention is to provide a kind of simply a kind of nickel foam of novel preparation process as interlayer TiO₂/ NFF lithium selenium secondary cell and preparation method thereof, its step are as follows for the preparation method:

1) TiO is prepared₂Nanofiber

0.2~0.4g vinylpyrrolidone is dissolved in 6~8mL ethyl alcohol, adds 2~4mL glacial acetic acid and 1~5mL metatitanic acid Four butyl esters, stirring 12~obtain spinning solution for 24 hours；Then the spinning under the high voltage of 15~20KV, then by spinning product 400 6~12h is pre-oxidized under the conditions of~700 DEG C, obtains the TiO of 80~100nm of diameter₂Nanofiber；

2) Se-TiO is prepared₂Positive electrode

The TiO that step 1) is prepared₂Nanofiber and Se particle grind 2~8h, tabletting after mixing with mass ratio 1:1 6~12h is roasted under the conditions of argon gas, 200~260 DEG C afterwards, Se particle is made to enter TiO₂Nanofiber it is mesoporous in, obtain Se-TiO₂Nanofiber；By Se-TiO obtained₂Nanofiber, conductive agent (super P, conductive black), binder (SA, sea Mosanom) it is mixed according to the ratio of mass ratio 8:1:1, gained slurry is coated on aluminium foil, obtains Se-TiO₂Positive electrode；

3) Se-TiO is prepared₂/ NFF lithium selenium secondary cell

By nickel foam tabletting at 10~20 μm of thickness of disk, carried out with 2M salt acid elution, then with deionized water and ethyl alcohol It rinses, obtains NFF interlayer:

In Se-TiO₂NFF interlayer is added between positive electrode and diaphragm (Celgard 2300), lithium piece is used as to electrode group Half-cell is filled, to obtain Se-TiO of the nickel foam of the present invention as interlayer₂/ NFF lithium selenium secondary cell.

A kind of Se-TiO of the nickel foam of the present invention as interlayer₂/ NFF lithium selenium secondary cell, it is characterised in that be It is prepared by the above method.

The beneficial effects of the present invention are:

(1) Se-TiO prepared₂Nanofiber pattern is uniform, purity is high, reproducible.

(2) raw material that preparation uses are cheap and easy to get, at low cost, are not necessarily to expensive device.

(3) simple process, favorable reproducibility can be not only used for experimental implementation, and can industrially be mass produced.

(4) anode material for lithium-ion batteries Se-TiO prepared by the present invention₂/ NFF capacity with higher, stable circulation High rate performance.

Detailed description of the invention

In order to illustrate more clearly of the technical solution in the present invention and its performance of material is prepared, correlation is given below Diagram.

Fig. 1 is NFF interlayer and Se/TiO prepared by embodiment 1₂The scanning electron microscope (SEM) photograph (SEM) of nanofiber.Scheming (a) is 40 The scanning electron microscope (SEM) photograph (SEM) of NFF under μm scale, it can be seen that NFF is hole configurations.Scheming (b) is Se/TiO under 1 μm of scale₂It receives The scanning electron microscope (SEM) photograph (SEM) of rice fiber, it can be clearly seen that Se/TiO₂The diameter of nanofiber about 100~120nm, it is whole Even thickness, soilless sticking.

Fig. 2 is X-ray diffraction (XRD) map that embodiment 1 prepares material.Wherein curve 3 is the Se/TiO of preparation₂It receives The map of rice fiber, curve 1 and curve 2 are respectively Se and TiO₂XRD spectrum.Comparison show that the x- of prepared material is penetrated The map free from admixture peak line diffraction (XRD) occurs, that is, proves that the material of preparation is the Se-TiO of pure phase₂。

Fig. 3 is Se-TiO prepared by embodiment 1₂As positive electrode, NFF is placed in positive electrode and diaphragm as interlayer Between (Celgard 2300), lithium piece is used as to electrode, and the CV of the half-cell of production schemes, in first lap discharge process, Se quilt More selenides are reduced into, more selenides are further reduced into Li₂The process of Se has a wider oxidation peak at 2.3V, right Answer Li₂Transformation of the Se to more selenides and Se.There are two pairs of new redox peaks simultaneously, wherein 1.7V/2.0V is TiO₂ The peak of offer；And 1.4V/1.9V is to produce the peak of new redox reaction, that is, the Li generated₂Se has occurred reversible with nickel Redox reaction generate Ni₃Se₂, 1.9V corresponds to Li₂Se to Ni₃Se₂Transformation, 1.4V corresponds to Ni₃Se₂To Li₂Se Transformation.This new redox reaction restrained effectively the loss of capacity, improve the performance of battery.

Fig. 4 is Se-TiO prepared by embodiment 1₂As positive electrode, NFF is placed in positive electrode and diaphragm as interlayer Between (Celgard 2300), lithium piece is used as to electrode, the cycle performance figure of the half-cell of production.There are 2 curves, curve in figure 1 represents coulombic efficiency, and curve 2 represents specific discharge capacity.It is seen that under 0.5C (337.5mAh/g) current density, After 200 circulations, specific discharge capacity holding still can achieve 597mAh/g, and coulombic efficiency shows material close to 100% Material has preferable cyclical stability.

Fig. 5 is Se-TiO prepared by embodiment 1₂As positive electrode, NFF is placed in positive electrode and diaphragm as interlayer Between (Celgard 2300), lithium piece is used as to electrode, the big circulation performance map of the half-cell of production.There are 2 songs in figure Line, curve 1 represent coulombic efficiency, and curve 2 represents specific discharge capacity.It can be seen from the figure that in the big of 30C (20250mA/g) Under current density charge-discharge test, being recycled by 500 times, the specific discharge capacity capacity of material remains to be maintained at 178mAh/g, and And coulombic efficiency illustrates that material has preferable cyclical stability and excellent high rate during charging-discharging close to 100%.

Fig. 6 is Se-TiO prepared by embodiment 1₂As positive electrode, NFF is placed in positive electrode and diaphragm as interlayer Between (Celgard 2300), lithium piece is used as to electrode, the half-cell of production respectively 0.5C, 1C, 2C, 5C, 10C, 20C, Discharge test high rate performance figure under 30C difference current density.It can be seen from the figure that material is under the test of each current density Stable circulation, and under the high current of 30C, the specific capacity of material still can achieve 303mAh/g, it was demonstrated that material have compared with Outstanding high rate performance.

Fig. 7 is Se-TiO prepared by embodiment 2₂As positive electrode, NFF is placed in positive electrode and diaphragm as interlayer Between (Celgard 2300), lithium piece is used as to electrode, the cycle performance figure of the half-cell of production.There are two curves in figure, it is bent Line 1 is Se-TiO₂/ NFF material, curve 2 are Se-TiO₂Material.Curve 2 is as a comparison.It is seen that curve 2 Under 0.5C (337.5mAh/g) current density, after 100 circulations, specific discharge capacity is only 124mAh/g, and curve 1 It still can achieve 597mAh/g through 100 circulation specific discharge capacities.It illustrates that NFF interlayer can absorb more selenides, inhibits to hold The loss of amount.

Fig. 8 is the Se of the preparation of embodiment 3 as positive electrode, and NFF is placed in positive electrode and diaphragm as interlayer Between (Celgard 2300), lithium piece is used as to electrode, the cycle performance figure of the half-cell of production.There are two curves in figure, it is bent Line 1 is Se-TiO₂/ NFF material, curve 2 are Se/NFF material.Curve 2 is as a comparison.It is seen that curve 2 exists Under 0.5C (337.5mAh/g) current density, after 100 circulations, specific discharge capacity only remains 152mAh/g, and curve 1 It still can achieve 597mAh/g through 100 circulation specific discharge capacities.Illustrate TiO₂It can play the role of solid selenium, to inhibit Shuttle effect.

Fig. 9 is the Se of the preparation of embodiment 4 as positive electrode, and NFF is placed in positive electrode and diaphragm as interlayer Between (Celgard 2300), lithium piece is used as to electrode, the cycle performance figure of the half-cell of production.There are two curves in figure, it is bent Line 1 is Se-TiO₂/ NFF material, curve 2 are Se material.Curve 2 is as a comparison.It is seen that curve 2 is in 0.5C Under (337.5mAh/g) current density, after 100 circulations, specific discharge capacity only remains 38mAh/g, and curve 1 is through 100 Secondary circulation specific discharge capacity still can achieve 597mAh/g.Illustrate TiO₂It can play the role of solid selenium, NFF interlayer can be inhaled More selenides are received, the two is the shuttle effect in mutual collaboration inhibition lithium selenium cell, and then improves the chemical property of battery.

Specific embodiment

Embodiment 1:

1) 0.35g vinylpyrrolidone is dissolved in 6.5mL ethyl alcohol, adds 2mL glacial acetic acid and 1.5mL butyl titanate, stirs 12h is mixed as spinning solution, spinning solution is sucked and is fixed on syringe with clip upper in manifold with the syringe of 10mL End, it is to receive material that aluminium foil is placed in the underface of syringe, and the distance controlling from syringe tip to aluminium foil is in 20cm or so, so The spinning under the high voltage of about 18KV afterwards obtains white filiform and is laid in aluminium foil surface.Obtained white filiform is taken out, 10h pre-oxidation, as TiO are carried out at 550 DEG C₂Nanofiber.The TiO that will be prepared₂Nanofiber and Se particle are with mass ratio 1:1 grinds 5h, and tabletting is placed in the reaction kettle full of argon gas, and 260 DEG C of roasting 10h make Se enter TiO₂It is mesoporous in, obtain Se-TiO₂Nanofiber.The Se-TiO that will be obtained₂Material, conductive agent (super P, i.e. conductive black), binder (SA, i.e. sea Mosanom) it is mixed according to mass ratio 8:1:1, gained slurry is coated on aluminium foil (thickness of slurry is 0.02mm), is placed in 120 DEG C Vacuum drying oven 10h, obtains Se-TiO₂Electrode material.It will be cut into the disk of diameter 12mm thickness 20um after nickel foam tabletting, uses 2M Salt acid elution, then be rinsed with deionized water and ethyl alcohol.With Se-TiO₂As positive electrode, assembled battery is being full of argon gas Glove box in carry out, with Se-TiO₂For positive electrode, NFF is placed in positive electrode and diaphragm (Celgard as interlayer It 2300) is to electrode with lithium piece, electrolyte is bis- (chloroform) the sulfimide lithium salts of 1mol/L and 1,2- dimethoxy between Ethane and 1,3- dioxy are defended the mixed solution that ring is formed with volume ratio 1:1, are packaged, and nickel foam of the present invention has been obtained Se-TiO as interlayer₂/ NFF secondary cell.

The cycle performance of battery curve of preparation is respectively as shown in figure 4, charging and discharging currents density is 0.5C.Big circulation Energy curve is as shown in figure 5, charging and discharging currents density is 30C, it can be seen that the cycle performance of battery is preferable.High rate performance figure is as schemed Shown in 6, charging and discharging currents density is 0.5C, 1C, 2C, 5C, 10C, 20C, 30C, shows that battery has preferable high rate performance.

Raw material described in this example can be bought from commercial channel.

Embodiment 2:

It is not adding NFF interlayer in assembled battery in place of the difference of embodiment 2 and embodiment 1, due to not having interlayer More selenides are absorbed, electrochemical cycle stability and high rate performance are relatively low, see Fig. 7.

Embodiment 3:

It is not prepare TiO in place of the difference of embodiment 3 and embodiment 1₂Nanofiber, that is, it is directly that Se is mono- Matter and SP, SA smear are made into electrode material, and NFF interlayer is added in when assembled battery, due to not having TiO₂Gu selenium, electrochemistry circulation is steady Qualitative and high rate performance is relatively low, sees Fig. 8.

Embodiment 4:

It is to use Se simple substance direct smear in place of the difference of embodiment 4 and embodiment 1, and does not also have in assembled battery NFF interlayer is added, due to not only not consolidating selenium, but also does not have the more selenides of interlayer absorption, electrochemical cycle stability and high rate performance are minimum, See Fig. 9.

Claims

1. a kind of preparation method of the Se-TiO ₂ /NFF lithium selenium secondary battery of a foamed nickel as interlayer, its steps are as follows:

1) Preparation of _TiO2 nanofibers

Dissolve 0.2-0.4 g of vinylpyrrolidone in 6-8 mL of ethanol, add 2-4 mL of glacial acetic acid and 1-5 mL of tetrabutyl titanate, and stir for 12-24 h to obtain a spinning solution; then spin under a high voltage of 15-20KV silk, and then pre-oxidize the spinning product at 400-700 °C for 6-12 h to obtain _TiO2 nanofibers with a diameter of 80-100 nm;

2) Preparation of Se- _TiO2 cathode material

The TiO ₂ nanofibers prepared in step 1) and the Se particles are mixed in a mass ratio of 1:1, and then ground for 2-8 hours. After tableting, they are calcined for 6-12 hours under the conditions of argon gas and 200-260 ° C, so that the Se particles enter the In the mesopores of _TiO2 nanofibers, Se- _TiO2 nanofibers were obtained; the prepared Se- _TiO2 nanofibers, conductive agent and binder were mixed in a mass ratio of 8:1:1, and the obtained slurry was coated with Covered on aluminum foil to obtain Se-TiO ₂ positive electrode material;

3) Preparation of Se-TiO ₂ /NFF lithium selenium secondary battery

The foamed nickel was pressed into a disc with a thickness of 10-20 μm, washed with 2M hydrochloric acid, and then rinsed with deionized water and ethanol to obtain an NFF interlayer; an NFF interlayer was added between the Se-TiO ₂ positive electrode material and the separator, and the lithium sheet was A half-cell was assembled as a counter electrode, thereby obtaining a Se-TiO ₂ /NFF lithium selenium secondary battery with nickel foam as an interlayer.

2. The method for preparing a Se-TiO ₂ /NFF lithium selenium secondary battery with nickel foam as an interlayer according to claim 1, wherein the conductive agent is conductive carbon black, and the adhesive The agent is sodium alginate.

3 . A Se-TiO ₂ /NFF lithium selenium secondary battery with nickel foam as an interlayer, characterized in that: it is prepared by the method according to claim 1 or 2 .