CN109244542A - A kind of lithium-sulfur cell electrolyte and its application - Google Patents
A kind of lithium-sulfur cell electrolyte and its application Download PDFInfo
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- CN109244542A CN109244542A CN201810925515.0A CN201810925515A CN109244542A CN 109244542 A CN109244542 A CN 109244542A CN 201810925515 A CN201810925515 A CN 201810925515A CN 109244542 A CN109244542 A CN 109244542A
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M10/00—Secondary cells; Manufacture thereof
- H01M10/05—Accumulators with non-aqueous electrolyte
- H01M10/056—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes
- H01M10/0564—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes the electrolyte being constituted of organic materials only
- H01M10/0566—Liquid materials
- H01M10/0567—Liquid materials characterised by the additives
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M10/00—Secondary cells; Manufacture thereof
- H01M10/05—Accumulators with non-aqueous electrolyte
- H01M10/052—Li-accumulators
- H01M10/0525—Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M10/00—Secondary cells; Manufacture thereof
- H01M10/05—Accumulators with non-aqueous electrolyte
- H01M10/056—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes
- H01M10/0564—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes the electrolyte being constituted of organic materials only
- H01M10/0566—Liquid materials
- H01M10/0568—Liquid materials characterised by the solutes
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M2300/00—Electrolytes
- H01M2300/0017—Non-aqueous electrolytes
- H01M2300/0025—Organic electrolyte
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- Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
- Y02E60/10—Energy storage using batteries
Abstract
The invention discloses a kind of lithium-sulfur cell electrolyte and preparation method thereof, it is characterised in that lithium-sulfur cell electrolyte includes alkyl polysulfide；The alkyl polysulfide has R1‑Sx‑R2Structure, R1、R2Total carbon number be not less than 3；The value of x is 2~500.The present invention changes traditional lithium-sulfur cell discharge mechanism, organic polysulfide replaces more lithium sulfides to become product in main discharge, greatly suppresses shuttle effect by the way that alkyl polysulfide is added in the electrolytic solution；Lithium-sulfur cell specific discharge capacity can be improved in S -- S of the alkyl polysulfide containing different number itself, the fracture in charge and discharge process；Finally significantly improve the initial capacity and cyclical stability of lithium-sulfur cell.
Description
Technical field
The present invention relates to a kind of lithium-sulfur cell fields, and in particular to a kind of lithium-sulfur cell electrolyte and has used the electricity
Solve the lithium-sulfur cell of liquid.
Background technique
In recent years, lithium-sulfur cell is because of its high-energy density (2500Wh/kg, 2800Wh/L), active material sulphur source is wide,
The advantages such as cheap and the concern by researcher, it is considered to be most potential next-generation high-energy density accumulator
One of part.But due to its complicated electrochemical reaction mechanism, some problems seriously constrain the practical application of lithium-sulfur cell.In ether
In class electrolyte, it will usually which there are two discharge platforms, first the polysulfide Li of sulphur simple substance lithiumation formation long-chain2S8, then in electricity
Pole surface is further reduced into Li2S6And Li2S4, a discharge platform in 2.3V or so is generated, this discharge platform is general
25% theoretical capacity is contributed to, and then the polysulfide of middle long-chain can further be converted into solid Li2S2And Li2S sinks
Product is in electrode surface, and discharge platform is in 2.1V or so.Due to intermediate product long-chain polysulphides Li2Sx(x=4~8) are highly soluble in
In ethers electrolyte, the practical efficiency for resulting in positive active material is not high, causes first circle actual specific capacity far below simple substance
The theoretical capacity (1675mAh/g) of sulphur；Under the action of electric field force and concentration gradient, long-chain lithium polysulphides can be to lithium an- ode
On the one hand the Li that lithium anode reaction generates short-chain lithium polysulphides and insulation is corroded in diffusion2S, the former can be diffused into anode again
Region is oxidized into long-chain lithium polysulphides, loops back and forth like this, and leading to coulombic efficiency seriously reduces and active material is irreversible
Loss, battery capacity therefore constantly decaying.
For the capacity fade problem of lithium-sulfur cell, Recent study person take many strategies and achieve good
Effect.Positive aspect, it is compound using various conductive porous carbon and sulphur, sulphur is filled into the carbon pores of high-specific surface area, it is ensured that
Conductive phase and insulation sulphur come into full contact with, promote the transfer of charge and transmits, the adsorptivity of carbon pores confinement active material to a certain extent,
The rigid backbone of carbon can also restrict active material caused by the volume change in electrode charge and discharge process and fall off problem.Cathode
Aspect, the three-D space structure of novel 3D cathode of lithium accelerate electric charge transfer speed while reducing interfacial resistance；Compared to flat
The specific surface area that face cathode of lithium greatly increases reduces local current density, so that distribution of charges is uniform, to reduce lithium
The growth rate of dendrite；In addition, forming one layer of metastable artificial SEI film by negative terminal surface processing, avoid by intrinsic SEI
Electrolyte caused by film is unstable, the active material caused by the reacting of polysulfide and lithium metal lose.In terms of diaphragm, Gao Xing
Can design and the synthesis of coating material (carbon coating diaphragm, element doping carbon composite coating diaphragm, metal oxide/carbon is compound changes
Property diaphragm etc.) and new types of diaphragm material and laminated diaphragm exploitation, also block the shuttle of polysulfide to a certain extent,
The corrosion of cathode of lithium is alleviated, so as to improve the performance of lithium-sulfur cell.
Electrolyte plays key effect for the transmission of lithium ion as one of big chief component of battery four.Pass through
Various additives are added, the coulombic efficiency and cycle performance of lithium-sulfur cell are improved.But most of additive, at present most
Widely used LiNO3For, to improving the effect of specific capacity and bad while promoting coulombic efficiency.Reason is it only
It is to form SEI film on cathode of lithium surface, blocks the corrosion of polysulfide to a certain extent, more sulphur cannot be but prevented from source
Compound dissolution, to solve the part irreversible capacity loss caused by active material is lost.
Summary of the invention
It is an object of the present invention to overcome the deficiencies in the prior art, provide a kind of in the same of the high coulombic efficiency of guarantee
When take into account the lithium-sulfur cell electrolyte of height ratio capacity and cycle performance.
Another object of the present invention is to provide the lithium-sulfur cell comprising the electrolyte.
To achieve the above object, The technical solution adopted by the invention is as follows:
A kind of lithium-sulfur cell electrolyte, including alkyl polysulfide shown in organic solvent, lithium salts and formula 1:
R1-Sx-R2
Formula 1
R1、R2Be independently chosen from for alkyl, alkylene, five yuan~seven yuan of naphthenic base, five yuan~seven yuan of Heterocyclylalkyl,
The cyclic hydrocarbon radical that unsaturated five yuan~seven yuan of part, benzene, five yuan~hexa-member heterocycle aryl or by phenyl ring, five-ring heterocycles, hexa-atomic
At least two aromatic rings in heterocycle and the condensed ring group for closing formation；
The alkyl, naphthenic base, alkylene, cyclic hydrocarbon radical, Heterocyclylalkyl, benzene, heterocyclic aryl, condensed ring group ring knot
Allow on structure containing substituent group, the substituent group is the alkyl or phenyl of C1-C6；
R1、R2Total carbon number be more than or equal to 3；
The value of x is 2~500.
The present invention innovatively provides a kind of lithium-sulfur cell electrolyte comprising 1 compound of formula, addition innovatively change
Traditional lithium-sulfur cell discharge mechanism is become, organic polysulfide replaces more lithium sulfides to become product in main discharge, presses down significantly
Shuttle effect has been made, the cycle performance of lithium-sulfur cell can be obviously improved.In addition alkyl polysulfide itself contains different numbers
Lithium-sulfur cell specific discharge capacity can be improved in the S -- S of amount, the fracture in charge and discharge process.
By the way that alkyl polysulfide is added, alkyl polysulfide is prior to Li+ and S in discharge process8Reaction is formed
Intermediate product R1-Sx+m-R2, greatly reduce more lithium sulfide (Li2Sn, 2 n≤8 <) generation (corresponding first discharge platform disappears
Lose, see Fig. 1), R1-Sx+m-R2Further electric discharge forms final product Li2S2/Li2S。
Preferably, R1、R2C1-C12 alkyl, C3-C12 naphthenic base, C3-C12 Heterocyclylalkyl, C2-C12 alkene are selected alone
Base, C6-C12 aryl, C7-C20 aralkyl, C7-C20 alkaryl, furfuryl group or thienyl.
Further preferably, R1、R2In, at least one substituent group includes aromatic structure.In this way, battery can be promoted surprisingly
Coulombic efficiency and cycle performance.The aromatic structure is, for example, benzene, five yuan~hexa-member heterocycle aryl or by phenyl ring, five yuan
At least two aromatic rings in heterocycle, hexa-member heterocycle and the condensed ring group for closing formation.
Most preferably, R1、R2In, at least one substituent group is C6-C12 aryl, C7-C20 aralkyl or C7-C20 alkaryl.
C6-C12 aryl is phenyl or contains the alkyl-substituted phenyl of C1-C4；The C7-C20 aralkyl is containing benzene or to take
For the alkyl of phenyl group.The plane skeleton and pi-pi bond of phenyl ring act on so that its cathode of lithium SEI film for participating in being formed has more bullet
Property, it is not easily broken, the effective growth for inhibiting Li dendrite further improves the cyclical stability and coulombic efficiency of battery.
In the present invention, R1、R2When for saturated group, R1、R2Preferably different substituents.So facilitate unexpected promotion electricity
The performances such as coulombic efficiency, the circulation in pond.In the present invention, R1、R2In, when at least one group includes aromatic structure, R1、R2For phase
Same or different groups.
R1、R2Total carbon number be greater than or equal to 3, be less than or equal to 60.
Preferably, the R1、R2Total carbon number be 5~20.Inventors have surprisingly discovered that in total carbon number, electrolyte
Electrochemical performance it is more excellent.
Further preferably, the R1、R2Total carbon number be 7~20；And phenyl ring is included at least in the substituent group.It grinds
Study carefully discovery, under the preferred carbon number and substituent group, the coulombic efficiency for the lithium-sulfur cell that can be further promoted and follows
Ring performance.
Most preferably, the R1、R2Total carbon number be 7~20；And the R1、R2In at least one substituent group be benzene or
Person's alkyl substituted benzene.The study found that R1、R2In at least one group be phenyl ring, the electricity added with the preferred polysulfide
The battery of solution liquid shows more preferably coulombic efficiency and cycle performance.
Preferably, when x is 2~100, x > 100, dissolubility of the alkyl polysulfide in current electrolyte system
It can decline, role is limited.
Further preferably, x is 2~10；It is still more preferably 2~6；Most preferably 2~4.
Preferably, alkyl polysulfide account for the lithium-sulfur cell electrolyte quality percentage composition be 0.1%~
40%；Further preferably 5~30%；Most preferably 10~30%.
Preferably, the organic solvent be polyether compound, carbonats compound, alkyl esters compound,
Sulfone, sulfoxide compound.
Preferably, the organic solvent is 1,3- dioxolane (DOL), Isosorbide-5-Nitrae-dioxane (DX), glycol dinitrate
Ether (DME), sweet glycol dimethyl ether (G2), three polyethylene glycol dimethyl ether (G3), four polyethylene glycol dimethyl ether (G4), tetrahydrofuran
(THF), ethyl-methyl sulfone (EMS), sulfolane (TMS), isopropyl methyl sulfone (MiPS), ethylene carbonate (EC), carbonic acid diformazan
One of ester (DMC), diethyl carbonate (DEC) or a variety of mixtures.
Preferably, the lithium salts is bis- (fluoroform sulphonyl) imine lithiums (LiTFSI), imidodisulfuryl fluoride lithium salt
(LiFSI), trifluoromethanesulfonic acid lithium (LiTf), difluorine oxalic acid boracic acid lithium (LiDFOB), difluoro bis- (oxalates) close lithium phosphate
(LiDFBOP), dioxalic acid lithium borate (LiBOB), lithium hexafluoro phosphate (LiPF6), LiBF4 (LiBF4), lithium nitrate
(LiNO3), lithium perchlorate (LiClO4One or more of).
Preferably, the concentration of the lithium salts in the electrolytic solution is 0.5~4mol/L.
It also include additive in the lithium-sulfur cell electrolyte.
Preferably, the additive is lithium nitrate, more lithium sulfides, potassium nitrate, cesium nitrate, barium nitrate, ammonium nitrate, nitrous acid
Lithium, potassium nitrite, cesium nitrite, ammonium nilrite, methyl nitrate, phosphoric sulfide, lithium bromide, lithium iodide, indium iodide, diphenyl disulfide
One of parallel thiazole, iodonitrobenzene, triphenyl phosphorus are a variety of.
Preferably, mass percentage of the additive in the electrolyte is 0.1%~5%；Further preferably
It is 1~3%, most preferably 1.5~2.5%.
The present invention also provides a kind of applications of lithium-sulfur cell electrolyte, are used as electrolyte, are used to prepare lithium-sulfur cell.
Another purpose according to the present invention, provides the lithium-sulfur cell comprising the electrolyte.The lithium-sulfur cell, by
Positive plate, negative electrode tab, diaphragm and electrolyte for separating positive plate and negative electrode tab, wherein the electrolyte is this
The invention lithium-sulfur cell electrolyte.
Preferably, the positive plate includes plus plate current-collecting body and the positive electrode for being compounded in plus plate current-collecting body surface；Institute
The positive electrode stated is obtained by the slurry curing of positive electrode active materials and conductive agent, binder and solvent.
The positive active material be one of elemental sulfur, sulfur-containing polymer, lithium sulfide, more lithium sulfides or two kinds with
On.
The negative electrode tab is one of metallic lithium foil, lithium piece, lithium alloy, silicon-carbon compound.
It is a kind of to preferred to use the lithium-sulfur cell of the electrolyte assembling.It is characterized in that: include positive plate, negative electrode tab,
Diaphragm, outer cover packaging；The diaphragm is between positive plate and negative electrode tab, the positive plate, negative electrode tab, diaphragm, electrolysis
Liquid is sealed in battery case packaging.The positive plate is coated on collection by positive electrode active materials and conductive agent, binder in proportion
Combination of fluids forms, and the positive active material is one of elemental sulfur, sulfur-containing polymer, lithium sulfide, more lithium sulfides or two
Kind or more.The negative electrode tab is one of metallic lithium foil, lithium piece, lithium alloy, silicon-carbon compound.
Compared with the prior art, technical solution of the present invention bring the utility model has the advantages that
1) addition of alkyl polysulfide, changes traditional lithium-sulfur cell discharge mechanism, and organic polysulfide replaces
More lithium sulfides become product in main discharge, greatly suppress shuttle effect, hence it is evident that improve the cycle performance of lithium-sulfur cell.
2) lithium can be improved in S -- S of the alkyl polysulfide itself containing different number, the fracture in charge and discharge process
Sulphur battery discharge specific capacity.
3) alkyl polysulfide and its discharging product can also form more stable passivation layer on cathode of lithium surface, especially
For preferably containing aryl, aralkyl, alkaryl alkyl polysulfide, the plane skeleton of phenyl ring and pi-pi bond effect make
The SEI film that must be formed is more elastic, effectively inhibits the growth of Li dendrite, further promotes circulating battery stability.
3) alkyl polysulfide is used as fragrance and food additives mostly, and technology maturation is low in cost, and the present invention
It is easy to operate, it has excellent performance, therefore there is wide industrial prospect.
Detailed description of the invention
[Fig. 1] is the first charge-discharge curve of the lithium-sulfur cell for the electrolyte assembling that the embodiment of the present invention 1 provides.
[Fig. 2] is lithium-sulfur cell charging and discharging curve in comparative example 1 of the present invention.
Specific embodiment
Following embodiment is intended to be described in further details the content of present invention；And the protection scope of the claims in the present invention
It is not limited by the example.
Embodiment 1
Lithium-sulfur cell is prepared with the following method:
1. electrolyte configures: (the H in the glove box of argon atmosphere2O < 0.1ppm), it is by volume second by organic solvent
Glycol dimethyl ether (DME): 1,3-dioxolane (DOL)=1: 1 is mixed with LiTFSI (1.0M), and the anhydrous of gross mass 2% is added
Lithium nitrate and 5% CH3CH2S3(CH2)2CH3, stir to get lithium-sulfur cell electrolyte of the present invention is arrived.
2. prepared by sulphur anode: sulphur/carbon composite (carrying sulfur content is 70%), acetylene black, PVDF is mixed by 90: 3: 7 proportions
It closes, the N-Methyl pyrrolidone (NMP) for adding appropriate volume, which is placed in refiner, stirs 15min, and revolving speed 15kr/min is formed
The anode sizing agent of stable uniform.This slurry is coated in carbon-coated aluminum foils using scraper, is placed in 80 DEG C of oven drying 8h, until
NMP volatilization is complete.
3. the assembling test of lithium sulphur button cell: the sulphur pole piece of preparation being punched into the round pole piece of Φ 13mm, at 55 DEG C
1h is dried in baking oven.In argon atmosphere, using metal lithium sheet as cathode, diaphragm selects the polypropylene microporous of model C elgard 2400
Film, electrolyte dosage are 15 μ L/mg S, are assembled into CR2025 lithium-sulfur cell in order.The battery prepared is placed in 25 DEG C of perseverance
After standing 12h in greenhouse, charge and discharge cycles test is carried out on blue electrical testing charge-discharge test instrument, test condition is constant current 0.5C
Charge and discharge, potential region are 1.7~2.8V, 100 circle of circulation (see Fig. 1).
Embodiment 2-4
In addition to following table parameter, other parameters and the preparation method is the same as that of Example 1.
1 embodiment 2-4 of table
Embodiment 5
Lithium-sulfur cell is prepared with the following method:
1. electrolyte configures: (the H in the glove box of argon atmosphere2O < 0.1ppm), it is by volume second by organic solvent
Glycol dimethyl ether (DME): 1,3-dioxolane (DOL)=1: 1 is mixed with LiTFSI (1.0M), and gross mass 5% is added
CH3CH2S3(CH2)2CH3, stir to get lithium-sulfur cell electrolyte of the present invention is arrived.
2. prepared by sulphur anode: sulphur/carbon composite (carrying sulfur content is 70%), acetylene black, PVDF is mixed by 90: 3: 7 proportions
It closes, the N-Methyl pyrrolidone (NMP) for adding appropriate volume, which is placed in refiner, stirs 15min, and revolving speed 15kr/min is formed
The anode sizing agent of stable uniform.This slurry is coated in carbon-coated aluminum foils using scraper, is placed in 80 DEG C of oven drying 8h, until
NMP volatilization is complete.
3. the assembling test of lithium sulphur button cell: the sulphur pole piece of preparation being punched into the round pole piece of Φ 13mm, at 55 DEG C
1h is dried in baking oven.In argon atmosphere, using metal lithium sheet as cathode, diaphragm selects the polypropylene microporous of model C elgard 2400
Film, electrolyte dosage are 15 μ L/mg S, are assembled into CR2025 lithium-sulfur cell in order.The battery prepared is placed in 25 DEG C of perseverance
After standing 12h in greenhouse, charge and discharge cycles test is carried out on blue electrical testing charge-discharge test instrument, test condition is constant current 0.5C
Charge and discharge, potential region are 1.7~2.8V, 100 circle of circulation.
Embodiment 6-8
It is compared with embodiment 5, the main distinction is, is not added with the additive；In addition to following table parameter, other parameters and
Preparation method is the same as embodiment 5.
2 embodiment 6-8 of table
| Organic solvent | Addition/cosolvent | Lithium salts | |
| Embodiment 6 | DME: DOL=1: 1 | 10%CH3CH2S3(CH2)2CH3 | 1.0M LiTFSI |
| Embodiment 7 | DME: DOL=1: 1 | 20%CH3CH2S3(CH2)2CH3 | 1.0M LiTFSI |
| Embodiment 8 | DME: DOL=1: 1 | 30%CH3CH2S3(CH2)2CH3 | 1.0M LiTFSI |
Comparative example 1
It is compared with embodiment 5, the main distinction is, is not added with the additive and CH3CH2S3(CH2)2CH3, specific to grasp
Make as follows:
1. electrolyte configures: (the H in the glove box of argon atmosphere2O < 0.1ppm), it is by volume second by organic solvent
Glycol dimethyl ether (DME): 1,3-dioxolane (DOL)=1: 1 is mixed with LiTFSI (1.0M), and the anhydrous of gross mass 2% is added
Lithium nitrate stirs to arrive lithium-sulfur cell electrolyte of the present invention.
2. prepared by sulphur anode: sulphur/carbon composite (carrying sulfur content is 70%), acetylene black, PVDF is mixed by 90: 3: 7 proportions
It closes, the N-Methyl pyrrolidone (NMP) for adding appropriate volume, which is placed in refiner, stirs 15min, and revolving speed 15kr/min is formed
The anode sizing agent of stable uniform.This slurry is coated in carbon-coated aluminum foils using scraper, is placed in 80 DEG C of oven drying 8h, until
NMP volatilization is complete.
3. the assembling test of lithium sulphur button cell: the sulphur pole piece of preparation being punched into the round pole piece of Φ 13mm, at 55 DEG C
1h is dried in baking oven.In argon atmosphere, using metal lithium sheet as cathode, diaphragm selects the polypropylene microporous of model C elgard 2400
Film, electrolyte dosage are 15 μ L/mg S, are assembled into CR2025 lithium-sulfur cell in order.The battery prepared is placed in 25 DEG C of perseverance
After standing 12h in greenhouse, charge and discharge cycles test is carried out on blue electrical testing charge-discharge test instrument, test condition is constant current 0.5C
Charge and discharge, potential region are 1.7~2.8V, 100 circle of circulation (see Fig. 2).
The test result of table 3 embodiment 1-8 and comparative example 1
Embodiment 1 to 4 is compared with comparative example 1, and under the discharge-rate of 0.5C, first circle specific discharge capacity is comparative example 1
894mAh/g, the first circle specific discharge capacity in embodiment 1 to 4 increase 441~1382mAh/g, 100 circle cyclicity by comparison
63.4~81.38% also can be increased to from 49.55%, coulombic efficiency is increased to from 97.5% preferably up to 99%, and embodiment 5 to 8 shows
Alkyl polysulfide could need to improve simultaneously the specific discharge capacity of battery, cycle performance and library under the synergistic effect of lithium nitrate
Human relations efficiency.
Embodiment 9
1. electrolyte configures: (the H in the glove box of argon atmosphere2O < 0.1ppm), it is by volume second by organic solvent
Glycol dimethyl ether (DME): 1,3-dioxolane (DOL)=1: 1 is mixed with LiTFSI (1.0M), and the anhydrous of gross mass 2% is added
Lithium nitrate and 5% C6H5S2CH3, stir to get lithium-sulfur cell electrolyte of the present invention is arrived.
2. prepared by sulphur anode: sulphur/carbon composite (carrying sulfur content is 70%), acetylene black, PVDF is mixed by 90: 3: 7 proportions
It closes, the N-Methyl pyrrolidone (NMP) for adding appropriate volume, which is placed in refiner, stirs 15min, and revolving speed 15kr/min is formed
The anode sizing agent of stable uniform.This slurry is coated in carbon-coated aluminum foils using scraper, is placed in 80 DEG C of oven drying 8h, until
NMP volatilization is complete.
3. the assembling test of lithium sulphur button cell: the sulphur pole piece of preparation being punched into the round pole piece of Φ 13mm, at 55 DEG C
1h is dried in baking oven.In argon atmosphere, using metal lithium sheet as cathode, diaphragm selects the polypropylene microporous of model C e1gard 2400
Film, electrolyte dosage are 15 μ L/mg S, are assembled into CR2025 lithium-sulfur cell in order.The battery prepared is placed in 25 DEG C of perseverance
After standing 12h in greenhouse, charge and discharge cycles test is carried out on blue electrical testing charge-discharge test instrument, test condition is constant current 0.5C
Charge and discharge, potential region are 1.7~2.8V, 100 circle of circulation.
Embodiment 10-12
In addition to following table parameter, other parameters and preparation method are the same as embodiment 9.
4 embodiment 10-12 of table
Embodiment 13
1. electrolyte configures: (the H in the glove box of argon atmosphere2O < 0.1ppm), it is by volume second by organic solvent
Glycol dimethyl ether (DME): 1,3-dioxolane (DOL)=1: 1 is mixed with LiTFSI (1.0M), and the anhydrous of gross mass 2% is added
Lithium nitrate and 5% C6H554C6H5, stir to get lithium-sulfur cell electrolyte of the present invention is arrived.
2. prepared by sulphur anode: sulphur/carbon composite (carrying sulfur content is 70%), acetylene black, PVDF is mixed by 90:3:7 proportion
It closes, the N-Methyl pyrrolidone (NMP) for adding appropriate volume, which is placed in refiner, stirs 15min, and revolving speed 15kr/min is formed
The anode sizing agent of stable uniform.This slurry is coated in carbon-coated aluminum foils using scraper, is placed in 80 DEG C of oven drying 8h, until
NMP volatilization is complete.
3. the assembling test of lithium sulphur button cell: the sulphur pole piece of preparation being punched into the round pole piece of Φ 13mm, at 55 DEG C
1h is dried in baking oven.In argon atmosphere, using metal lithium sheet as cathode, diaphragm selects the polypropylene microporous of model C elgard 2400
Film, electrolyte dosage are 15 μ L/mg S, are assembled into CR2025 lithium-sulfur cell in order.The battery prepared is placed in 25 DEG C of perseverance
After standing 12h in greenhouse, charge and discharge cycles test is carried out on blue electrical testing charge-discharge test instrument, test condition is constant current 0.5C
Charge and discharge, potential region are 1.7~2.8V, 100 circle of circulation.
Embodiment 14-16
In addition to following table parameter, other parameters and the preparation method is the same as that of Example 13.
5 embodiment 14-16 of table
The test result of table 6 embodiment 9-16 and comparative example 1
Comparing embodiment 9-16 and embodiment 1-4 and comparative example 1 are it is found that preferably containing the C of aryl6H5S2CH3、
C6H554C6H5As additive, compared to the alkyl polysulfide that alkyl is contained at both ends show higher capacity retention ratio with
Coulombic efficiency.Mainly the plane skeleton of phenyl ring and pi-pi bond act on so that its to participate in the cathode of lithium SEI film formed more elastic,
It is not easily broken, the effective growth for inhibiting Li dendrite further improves the cyclical stability and coulombic efficiency of battery.Preferably
C containing aryl6H554C6H5It is the organic of common alkyl compared to both ends due to contributing capacity containing more S -- Ss
Polysulfide (embodiment 1-4), while showing higher capacity retention ratio and coulombic efficiency, it may have higher electric discharge
Specific capacity.
Claims (10)
1. a kind of lithium-sulfur cell electrolyte, it is characterised in that: vulcanize conjunction including alkyl shown in organic solvent, lithium salts and formula 1 more
Object:
R1-Sx-R2
Formula 1
R1、R2It is independently chosen from as alkyl, alkylene, five yuan~seven yuan of naphthenic base, five yuan~seven yuan of Heterocyclylalkyl, part
Unsaturated five yuan~seven yuan of cyclic hydrocarbon radical, benzene, five yuan~hexa-member heterocycle aryl or by phenyl ring, five-ring heterocycles, hexa-member heterocycle
In at least two aromatic rings and close the condensed ring group of formation；
The alkyl, naphthenic base, alkylene, cyclic hydrocarbon radical, Heterocyclylalkyl, benzene, heterocyclic aryl, condensed ring group ring structure on
Allow containing substituent group, the substituent group is the alkyl or phenyl of C1-C6；
R1、R2Total carbon number be greater than or equal to 3；
The value of x is 2~500.
2. lithium-sulfur cell electrolyte as described in claim 1, it is characterised in that: R1、R2C1-C12 alkyl, C3- are selected alone
C12 naphthenic base, C3-C12 Heterocyclylalkyl, C2-C12 alkenyl, C6-C12 aryl, C7-C20 aralkyl, C7-C20 alkaryl, furfuryl group
Or thienyl.
3. lithium-sulfur cell electrolyte as described in claim 1, it is characterised in that: R1、R2In, at least one substituent group includes virtue
Fragrant structure.
4. lithium-sulfur cell electrolyte as claimed in any one of claims 1 to 3, it is characterised in that: R1、R2In, at least one substitution
Base is C6-C12 aryl, C7-C20 aralkyl or C7-C20 alkaryl.
5. such as the described in any item lithium-sulfur cell electrolyte of Claims 1 to 4, it is characterised in that: alkyl polysulfide accounts for institute
The lithium-sulfur cell electrolyte quality percentage composition stated is 0.1%~40%；Preferably 10~30%.
6. lithium-sulfur cell electrolyte as described in claim 1, it is characterised in that: the organic solvent is polyethers chemical combination
Object, carbonats compound, alkyl esters compound, sulfone, sulfoxide compound；
Preferably, the organic solvent is 1,3- dioxolane (DOL), Isosorbide-5-Nitrae-dioxane (DX), glycol dimethyl ether
(DME), sweet glycol dimethyl ether (G2), three polyethylene glycol dimethyl ether (G3), four polyethylene glycol dimethyl ether (G4), tetrahydrofuran
(THF), ethyl-methyl sulfone (EMS), sulfolane (TMS), isopropyl methyl sulfone (MiPS), ethylene carbonate (EC), carbonic acid diformazan
One of ester (DMC), diethyl carbonate (DEC) or a variety of mixtures.
7. lithium-sulfur cell electrolyte as described in claim 1, it is characterised in that: the lithium salts is bis- (fluoroform sulphonyl)
Imine lithium (LiTFSI), imidodisulfuryl fluoride lithium salt (LiFSI), trifluoromethanesulfonic acid lithium (LiTf), difluorine oxalic acid boracic acid lithium
(LiDFOB), difluoro bis- (oxalates) closes lithium phosphate (LiDFBOP), dioxalic acid lithium borate (LiBOB), lithium hexafluoro phosphate
(LiPF6), LiBF4 (LiBF4), lithium nitrate (LiNO3), lithium perchlorate (LiClO4One or more of).
The concentration of the lithium salts in the electrolytic solution is preferably 0.5~4mol/L.
8. lithium-sulfur cell electrolyte as described in any one of claims 1 to 7, it is characterised in that: the lithium-sulfur cell electrolysis
It also include additive in liquid；
Preferably, the additive be lithium nitrate, more lithium sulfides, potassium nitrate, cesium nitrate, barium nitrate, ammonium nitrate, lithium nitrite,
Potassium nitrite, cesium nitrite, ammonium nilrite, methyl nitrate, phosphoric sulfide, lithium bromide, lithium iodide, indium iodide, diphenyl disulfide a pair of horses going side by side
One of thiazole, iodonitrobenzene, triphenyl phosphorus are a variety of；
Preferably, mass percentage of the additive in the electrolyte is preferably 0.1%~5%.
9. the application of lithium-sulfur cell electrolyte as described in any one of claims 1 to 8, it is characterised in that: be used as electrolyte, use
In preparing lithium-sulfur cell.
10. a kind of lithium-sulfur cell, by positive plate, negative electrode tab, for by the diaphragm and electrolyte of positive plate and negative electrode tab separation,
It is characterized by: it includes lithium-sulfur cell electrolyte according to any one of claims 1 to 8 that the electrolyte, which is,；
Preferably, the positive plate includes plus plate current-collecting body and the positive electrode for being compounded in plus plate current-collecting body surface；Described
Positive electrode is obtained by the slurry curing of positive electrode active materials and conductive agent, binder and solvent；
The positive active material is one of elemental sulfur, sulfur-containing polymer, lithium sulfide, more lithium sulfides or two kinds or more；
The negative electrode tab is one of metallic lithium foil, lithium piece, lithium alloy, silicon-carbon compound.
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