CN117059894A - Electrolyte and alkali metal cell - Google Patents

Electrolyte and alkali metal cell Download PDF

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Publication number
CN117059894A
CN117059894A CN202311073242.9A CN202311073242A CN117059894A CN 117059894 A CN117059894 A CN 117059894A CN 202311073242 A CN202311073242 A CN 202311073242A CN 117059894 A CN117059894 A CN 117059894A
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compound
electrolyte
carbonate
lithium
salt
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黄秋洁
毛冲
王霹霹
王晓强
欧霜辉
吴东庆
戴晓兵
冯攀
韩晖
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Huainan Saiwei Electronic Materials Co ltd
Hefei Saiwei Electronic Materials Co ltd
Zhuhai Smoothway Electronic Materials Co Ltd
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Huainan Saiwei Electronic Materials Co ltd
Hefei Saiwei Electronic Materials Co ltd
Zhuhai Smoothway Electronic Materials Co Ltd
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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
    • 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
    • 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
    • H01M10/054—Accumulators with insertion or intercalation of metals other than lithium, e.g. with magnesium or aluminium
    • 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
    • H01M10/42—Methods or arrangements for servicing or maintenance of secondary cells or secondary half-cells
    • H01M10/4235—Safety or regulating additives or arrangements in electrodes, separators or electrolyte
    • 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
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/10—Energy storage using batteries

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Manufacturing & Machinery (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Electrochemistry (AREA)
  • General Chemical & Material Sciences (AREA)
  • Physics & Mathematics (AREA)
  • Condensed Matter Physics & Semiconductors (AREA)
  • General Physics & Mathematics (AREA)
  • Inorganic Chemistry (AREA)
  • Materials Engineering (AREA)
  • Secondary Cells (AREA)

Abstract

The invention provides an electrolyte and an alkali metal battery. The additive comprises a phosphoramide compound and a cyclic sulfate compound, wherein the structural formula of the phosphoramide compound is shown as a formula I or a formula II, and the structural formula of the cyclic sulfate compound is shown as a formula III. Wherein R is 1 Is halogen or halogenated hydrocarbon, R 2 And R is 3 Each independently selected from at least one of hydrocarbyl, ester, silicon, and halogenated hydrocarbon, R 4 、R 5 And R is 6 Each independently selected from a hydrogen atom or a C1-C6 hydrocarbon group. The invention regulates and controls the inorganic and organic components of the interfacial film through the synergistic effect of the chain phosphoramide compound and the cyclic sulfate compound,the stable SEI film can be obtained to weaken electrochemical adverse reaction caused by metal dendrites in the alkali metal battery, and further improve the rate capability, high-temperature capability and safety performance of the alkali metal battery.

Description

Electrolyte and alkali metal cell
Technical Field
The invention relates to the technical field of secondary batteries, in particular to an electrolyte and an alkali metal battery.
Background
At present, the secondary battery is widely applied to technical products such as automobiles, mobile phones and the like. The commercial secondary battery mainly uses graphite as a negative electrode material, and its capacity has already been brought close to the theoretical value of graphite (372 mAh/g), and it is difficult to increase the capacity of the secondary battery to a high extent by treating graphite.
In order to obtain a secondary battery having a high capacity, a metal material having a high storage capacity characteristic by an alloying reaction with lithium, such as silicon (4200 mAh/g) and tin (990 mAh/g), is used as the anode active material. However, when metals such as silicon and tin are used as the anode active material, the volume thereof expands to about 4 times during charge alloying with lithium, and is re-contracted during discharge. Since a large volume change of the electrode assembly repeatedly occurs during charge/discharge, the active material is gradually micronized and falls off from the electrode, and thus the capacity is rapidly reduced, so that it is difficult to secure stability and reliability, and thus commercialization fails.
Compared to the above-described anode active material, alkali metals such as: the lithium metal, sodium metal and potassium metal have higher specific capacity, especially the metal lithium, the theoretical specific capacity is up to 3860mAh/g, the electrode potential is as low as-3.04V (relative to H 2 /H + ) Therefore, the development of an alkali metal battery using an alkali metal as a negative electrode active material has again attracted attention from researchers.
However, there are two main obstacles limiting the further development of alkali metal batteries: (1) Dendrites such as lithium dendrites are easily generated in the cycling process of the alkali metal battery, and the lithium dendrites easily pierce through the isolating film of the battery, so that the battery is easily short-circuited; (2) The lithium dendrite has large surface area and high activity, is easy to react with electrolyte, causes continuous recombination of SEI film (interface film) on the surface of metal lithium, consumes electrolyte and active lithium, also causes reduction of cycle efficiency and shortens the cycle life of the battery. Therefore, how to effectively improve the surface properties of the metal electrode and inhibit the generation of metal dendrites is an important point to be solved for further development of alkali metal batteries.
Disclosure of Invention
The invention aims to provide an electrolyte and an alkali metal battery, wherein the electrolyte can form a stable SEI film, and can weaken electrochemical adverse reaction caused by metal dendrites in the alkali metal battery, so that the rate capability, high-temperature performance and safety performance of the alkali metal battery are improved.
In order to achieve the above object, the present invention provides an electrolyte comprising an electrolyte salt, a nonaqueous organic solvent and an additive. The additive comprises a phosphoramide compound and a cyclic sulfate compound, wherein the structural formula of the phosphoramide compound is shown as a formula I or a formula II, and the structural formula of the cyclic sulfate compound is shown as a formula III.
Wherein R is 1 Is halogen or halogenated hydrocarbon, R 2 And R is 3 Each independently selected from at least one of hydrocarbyl, ester, silicon, and halogenated hydrocarbon, R 4 、R 5 And R is 6 Each independently selected from a hydrogen atom or a C1-C6 hydrocarbon group.
The electrolyte of the present invention has at least the following technical effects.
(1) The phosphoramide compound can bond with alkali metal to form a stable protective film on the surface of the alkali metal anode, and the film is rich in LiF and Li 3 N、LiN x O y 、LiP x O y And the like. Wherein, the phosphorus, nitrogen, fluorine, oxygen and other hetero atoms have charged negativity and are attractive to alkali metal ions, and are rich in LiF and Li 3 N、LiN x O y 、LiP x O y SEI films formed by deposition of the decomposition products of the isocompositions onto the electrode surfaces are advantageous for alkali metal ions (e.g., L i+ ) Through the SEI film, DCR (namely resistance) of the SEI film can be effectively improved, and further the rate capability of the alkali metal battery is improved, so that electrochemical adverse reaction caused by lithium dendrite in the alkali metal battery is weakened.
(2) The phosphoramide compound contains a-P-F group, the oxidation potential of the group is higher, the oxidation resistance of the phosphoramide compound can be improved after the phosphoramide compound is introduced, and the phosphoramide compound is beneficial to inhibiting the oxidative decomposition of electrolyte under a 4.55V high-voltage system, so that the normal-temperature cycle performance of an alkali metal battery is improved.
(3) Because the phosphoramide compound belongs to a chain structure, the formed inorganic SEI film has stronger brittleness and poor toughness, and the instability of the interface film in long-term storage leads to the contact of electrolyte and an anode interface and the contact of the electrolyte and an anode interface, side reaction occurs, and further the high-temperature performance and the safety performance are poor. By introducing cyclic sulfate compounds of cyclic-N-S (=O) 2 ) The structure of-n=c (=o) -n=c-containing nitrogen-sulfur, nitrogen-carbon, sulfur-oxygen, etc. chemical bonds can react at the electrode/electrolyte interface to form SEI more rich in organic components, thereby improving toughness and stability of the interfacial film.
Therefore, through the synergistic effect of the chain phosphoramide compound and the cyclic sulfate compound, inorganic and organic components of the interfacial film are regulated and controlled, a stable SEI film can be obtained, and electrochemical adverse reactions caused by metal dendrites in the alkali metal battery can be weakened, so that the rate capability, high-temperature performance and safety performance of the alkali metal battery are improved.
As a technical scheme of the invention, the phosphoramide compound accounts for 0.01-5.00% of the sum of the mass of the electrolyte salt, the mass of the non-aqueous organic solvent and the mass of the additive, and the cyclic sulfate compound accounts for 0.01-2.00% of the sum of the mass of the electrolyte salt, the mass of the non-aqueous organic solvent and the mass of the additive.
As an embodiment of the present invention, the phosphoramide compound is at least one selected from the group consisting of compounds 1 to 6.
As an embodiment of the present invention, the cyclic sulfate compound is at least one selected from the group consisting of compound 7 and compound 12.
As an aspect of the present invention, the electrolyte salt is a sodium salt, a potassium salt or a lithium salt.
As an aspect of the present invention, the nonaqueous organic solvent includes at least one of cyclic carbonate, chain carbonate, carboxylate and lactone.
As an aspect of the present invention, the non-aqueous organic solvent includes at least one of dimethyl carbonate, diethyl carbonate, dipropyl carbonate, ethylmethyl carbonate, methylpropyl carbonate, ethylpropyl carbonate, ethylene carbonate, fluoroethylene carbonate, methyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, propyl propionate, γ -butyrolactone, γ -valerolactone, γ -caprolactone, σ -valerolactone, and ε -caprolactone.
As a technical scheme of the invention, the electrolyte solution further comprises an auxiliary agent, wherein the auxiliary agent is a nitric acid compound, and the nitric acid compound accounts for 0.01-1.00% of the sum of the electrolyte salt, the non-aqueous organic solvent, the additive and the nitric acid compound.
As an aspect of the present invention, the nitric acid compound includes at least one of lithium nitrate, potassium nitrate, sodium nitrate, cesium nitrate, magnesium nitrate, barium nitrate, lithium nitrite, potassium nitrite, and cesium nitrite.
In another aspect, the invention provides an alkali metal cell comprising a positive electrode material, a negative electrode material, and an electrolyte, the electrolyte comprising the electrolyte.
Detailed Description
The electrolyte of the invention can be used for alkali metal batteries. The negative electrode material of the alkali metal cell may be lithium metal, sodium metal, potassium metal, lithium alloy, sodium alloy or potassium alloy. The positive electrode material can be cobalt composite oxide series material, ferric phosphate series material, nickel cobalt manganese composite oxide series material or nickel cobalt aluminum composite oxide series material. When the negative electrode material is lithium metal, sodium metal, potassium metal, lithium alloy, sodium alloy or potassium alloy, the positive electrode material is a composite metal oxide of corresponding metal. For example, when the negative electrode material is lithium metal or lithium alloy, the cobalt composite oxide series material is lithium cobaltate or doped and coated modified lithium cobaltate, the iron phosphate series material is lithium iron phosphate or doped and coated modified lithium iron phosphate, and the chemical formula of the nickel cobalt manganese composite oxide series material is LiNi x Co y Mn z M (1-x-y-z) O 2 The chemical formula of the nickel-cobalt-aluminum composite oxide series material is LiNi x Co y Al z N (1-x-y-z) O 2 Wherein M is at least one of Mg, cu, zn, al, sn, B, ga, cr, sr, V and Ti, N is at least one of Mn, mg, cu, zn, sn, B, ga, cr, sr, V and Ti, and 0.ltoreq.x<1，0<y<1，0<z<1，x+y+z≤1。
The electrolyte comprises electrolyte salt, nonaqueous organic solvent, additive and auxiliary agent.
The electrolyte salt is sodium salt, potassium salt or lithium salt. The electrolyte salt accounts for 6-15% of the electrolyte mass, and the content of the electrolyte salt can be, but is not limited to, 6.0%, 6.5%, 7.0%, 7.5%, 8.0%, 8.5%, 9.0%, 9.5%, 10.0%, 11.0%, 12.0%, 13.0%, 14.0%, 15.0%.
The lithium salt is LiPF 6 Lithium hexafluorophosphate, liBF 4 Lithium tetrafluoroborate, liClO 4 (lithium perchlorate), liAsF 6 Lithium hexafluoroarsenate, liSbF 6 (lithium hexafluoroantimonate), liPF 2 O 2 (lithium difluorophosphate), liDTI (4, 5-dicyano-2-trifluoromethylimidazole lithium), liBOB (lithium bis (oxalato) borate), liDFOB (lithium difluorooxalato borate), liFSI (lithium bis (fluorosulfonyl) imide), liN (SO) 2 RF) 2 、LiN(SO 2 F)(SO 2 RF) and LiCl (lithium chloride), wherein rf=cnf 2n+1 N is an integer of 1 to 10.
Sodium salt is NaPF 6 Sodium hexafluorophosphate, naBF 4 Sodium tetrafluoroborate, naClO 4 (sodium perchlorate), naAsF 6 Sodium hexafluoroarsenate, naSbF 6 Sodium hexafluoroantimonate, naPF 2 O 2 Sodium difluorophosphate, naDTI (4, 5-dicyano-2-trifluoromethylimidazole sodium), naBOB (sodium bisoxalato borate), naDFOB (sodium difluorooxalato borate), naFSI (sodium bis (fluorosulfonyl) imide), naN (SO) 2 RF) 2 、NaN(SO 2 F)(SO 2 RF) and NaCl (sodium chloride), wherein rf=cnf 2n+1 N is an integer of 1 to 10.
The potassium salt is KPF 6 (Potassium hexafluorophosphate), KBF 4 Potassium tetrafluoroborate, KClO 4 (Potassium perchlorate), KAsF 6 (Potassium hexafluoroarsenate), KSbF 6 Potassium hexafluoroantimonate, KPF 2 O 2 (Potassium difluorophosphate), KDTI (4, 5-dicyano-2-trifluoromethylimidazole potassium), KBOB (potassium bisoxalato borate), KDGOB (potassium difluorooxalato borate), KFSI (potassium bis (fluorosulfonyl) imide), KN (SO) 2 RF) 2 、KN(SO 2 F)(SO 2 RF) and KCl (potassium chloride), wherein rf=cnf 2n+1 N is an integer of 1 to 10.
The nonaqueous organic solvent includes at least one of cyclic carbonate, chain carbonate, carboxylate and lactone. Specifically, the nonaqueous organic solvent includes at least one of dimethyl carbonate (DMC), diethyl carbonate (DEC), dipropyl carbonate (DPC), ethylmethyl carbonate (EMC), methylpropyl carbonate (PMC), ethylpropyl carbonate (PEC), ethylene Carbonate (EC), propylene Carbonate (PC), fluoroethylene carbonate (FEC), methyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, propyl propionate, γ -butyrolactone, γ -valerolactone, γ -caprolactone, σ -valerolactone, and epsilon-caprolactone.
The additive comprises a phosphoramide compound and a cyclic sulfate compound, wherein the structural formula of the phosphoramide compound is shown as a formula I or a formula II, and the structural formula of the cyclic sulfate compound is shown as a formula III. Wherein R is 1 Is halogen or halogenated hydrocarbon, R 2 And R is 3 Each independently selected from at least one of hydrocarbyl, ester, silicon, and halogenated hydrocarbon, R 4 、R 5 And R is 6 Each independently selected from a hydrogen atom or a C1-C6 hydrocarbon group.
The phosphoramide compound accounts for 0.01-5.00% of the total mass of the electrolyte salt, the nonaqueous organic solvent and the additive, preferably 0.05-1%, and specifically may be, but not limited to, 0.01%, 0.03%, 0.05%, 0.07%, 0.09%, 0.1%, 0.2%, 0.5%, 0.7%, 0.9%, 1.00%, 2.00%, 3.00%, 4.00%, 5.00%. The cyclic sulfate compound accounts for 0.01 to 2.00%, preferably 0.05 to 1%, of the total mass of the electrolyte salt, the nonaqueous organic solvent and the additive, and specifically may be, but not limited to, 0.01%, 0.03%, 0.05%, 0.07%, 0.09%, 0.1%, 0.2%, 0.5%, 0.7%, 0.9%, 1.00%, 2.00%. The contents of the phosphoramide compound and the cyclic sulfate compound cannot be too low, or otherwise an SEI film cannot be uniformly formed on the surface of the alkali metal negative electrode, and thus a desired effect cannot be obtained. Conversely, the content is not too high, otherwise unnecessary reactions may occur when the alkali metal cell is driven, resulting in deterioration of the performance of the alkali metal cell.
The phosphoramide compound is at least one selected from the group consisting of compounds 1 to 6. Preferred are compound 4 and compound 5, which have a plurality of fluorine atoms, are easier to construct LiF, have a smaller skeleton and lower impedance, and therefore have better rate and cycle performance.
The cyclic sulfate compound is selected from at least one of compound 7 to compound 12. Preferably, compound 9 and compound 12 have benzene ring structures, and are more stable in structure, so that they have better high-temperature performance.
The auxiliary agent is a nitric acid compound, the nitric acid compound accounts for 0.01-1.00% of the sum of the mass of the electrolyte salt, the nonaqueous organic solvent, the additive and the nitric acid compound, and the content of the nitric acid compound can be, but is not limited to, 0.01%, 0.02%, 0.03%, 0.04%, 0.05%, 0.06%, 0.07%, 0.08%, 0.09%, 0.10%, 0.20%, 0.50%, 0.70%, 0.90% and 1.0% by way of example. The nitric acid compound comprises at least one of lithium nitrate, potassium nitrate, sodium nitrate, cesium nitrate, magnesium nitrate, barium nitrate, lithium nitrite, potassium nitrite and cesium nitrite.
For a better description of the objects, technical solutions and advantageous effects of the present invention, the present invention will be further described with reference to specific examples. It should be noted that the following implementation of the method is a further explanation of the present invention and should not be taken as limiting the present invention.
Example 1
(1) Preparation of electrolyte: in a vacuum glove box with the water content less than 1ppm under the argon atmosphere, mixing methyl ethyl carbonate (EMC) and fluoroethylene carbonate (FEC) according to the weight ratio of EMC to FEC=1:1, then adding each additive and auxiliary agent, dissolving and fully stirring, adding lithium salt, and uniformly mixing to obtain the electrolyte.
(2) Preparation of positive electrode: liCoO as lithium cobalt oxide material 2 Uniformly mixing the adhesive PVDF and the conductive agent SuperP according to the mass ratio of 95:1:4 to prepare alkali metal battery anode slurry with certain viscosity, coating the mixed slurry on two sides of an aluminum foil, and drying and rolling to obtain the anode plate.
(3) Preparation of the separator: polyethylene (PE) having a thickness of about 15 μm was used as the separator.
(4) Preparation of the negative electrode: and compounding metal lithium onto a current collector copper foil with the thickness of about 10 mu m by a physical rolling method, regulating the pressure of a roller to cover lithium on two sides of the copper current collector, and controlling the thickness of the covered lithium to be about 35 mu m to obtain the lithium-copper composite belt cathode. Then after cutting pieces and slitting, the materials are placed in a glove box with dry argon atmosphere for storage.
(5) Preparation of alkali metal cell: and stacking the anode, the isolating film and the lithium copper composite band cathode in sequence, and then stacking according to the requirement. And (3) after welding the tab, placing the tab in an aluminum plastic film of an external package of the battery, injecting the prepared electrolyte into the dried bare cell, sequentially carrying out the working procedures of vacuum packaging, standing, formation (0.05C constant current is charged to 3.6V, then 0.1C constant current is charged to 3.9V), shaping, capacity testing and the like, and finally obtaining the 1Ah soft package lithium metal battery.
The electrolyte formulations of examples 2 to 11 and comparative examples 2 to 4 are shown in table 1, and the procedure for preparing the electrolyte and preparing the battery is the same as in example 1.
Table 1 electrolyte components of examples and comparative examples
The lithium metal batteries manufactured in examples 1 to 11 and comparative examples 1 to 4 were respectively subjected to the rate performance, cycle performance, storage performance and safety performance test under the following specific test conditions, and the performance test results are shown in table 2.
(1) Rate capability test
The lithium metal batteries of examples 1 to 11 and comparative examples 1 to 4 were charged to 4.55V at 25℃under a constant current of 0.5C, then charged at a constant voltage to a current of 0.05C, and then discharged to 3.0V under a constant current of 0.5C, and the charge and discharge cycles were repeated 3 times, with the discharge capacity of C in the last cycle 0 . Charging to 4.55V with constant current of 0.5C, constant voltage charging to current of 0.05C, discharging to 3.0V with constant current of 3C, and discharging capacity of C 1 . Capacity retention = C1/C0 x 100%
(2) High temperature cycle performance test
The lithium metal batteries of examples 1 to 11 and comparative examples 1 to 4 were subjected to 0.5C/0.5C charge and discharge once at 45 ℃ (battery discharge capacity: C0), the upper limit voltage was 4.55V, and then subjected to 0.5C/0.5C charge and discharge for 300 weeks (battery discharge capacity: C1) under high temperature conditions, with a capacity retention = (C1/C0) ×100%
(3) High temperature storage performance test
The lithium metal batteries of examples 1 to 11 and comparative examples 1 to 4 were charged and discharged 0.5C/0.5C at normal temperature (25 ℃) once (the battery discharge capacity was recorded as C0), respectively, with an upper limit voltage of 4.55V; placing the battery in a 60 ℃ oven for 15d, taking out the battery, placing the battery in a 25 ℃ environment for 0.5C discharge, and recording the discharge capacity as C1; then, the lithium metal battery was charged and discharged once at 0.5C/0.5C (the battery discharge capacity was recorded as C2), and the capacity retention rate and the capacity recovery rate of the lithium metal battery were calculated using the following formulas.
Capacity retention = C1/C0 x 100%
Capacity recovery = C2/C0 x 100%
(4) Safety performance test
The lithium metal batteries of examples 1 to 11 and comparative examples 1 to 4 were charged at a constant current of 1C until the charge termination voltage (10V) was reached, and then turned into constant voltage charge until the charge current rate was reduced to 0.05C, and the charge was stopped and allowed to stand for 2.5 hours at normal temperature (25 ℃). The battery is put into a test box, the temperature of the test box is raised at a temperature rise rate of 5 ℃/min, and the temperature is kept for 1h after the temperature in the test box reaches 160+/-2 ℃. The battery does not smoke, fire or explode, or passes.
Table 2 results of performance testing of various embodiments
As can be seen from the results in table 2, the rate performance, high temperature cycle, high temperature storage and safety performance of the lithium metal batteries of examples 1 to 11 are all better than those of comparative examples 1 to 4, and the stable SEI film can be obtained by controlling the inorganic and organic components of the interfacial film through the synergistic effect of the chain phosphoramide compound and the cyclic sulfate compound in the main examples 1 to 11, so as to weaken the electrochemical adverse reaction caused by lithium dendrites in the lithium metal batteries, and further improve the rate performance, high temperature performance and safety performance of the lithium metal batteries.
As is clear from comparative examples 1 and 2, the addition of nitric acid compound in addition to chain phosphoramide compound and cyclic sulfate compound can improve the rate performance, high temperature performance and safety performance of lithium metal battery, which is probably due to the fact that nitrate reacts with lithium metal to form insoluble Li x NO y ，Li x NO y And then the SEI film is formed, so that the lithium metal anode can be protected and the shuttle effect of the lithium compound can be inhibited. In addition, the amide, the phosphate and the nitrate have a synergistic effect, and a fluorine-nitrogen SEI film is formed on the surface of the metal lithium, so that the interface resistance can be reduced, meanwhile, the interface evolution in the circulation process of the metal lithium can be adapted, and the structure and the property of the SEI film are maintained.
As is clear from comparative examples 1 and examples 3 to 4, the compounds 4 and 5 of examples 3 to 4 have a plurality of fluorine atoms, and the ratio and cycle performance are better.
As is clear from comparative examples 4 and examples 6 to 7, the cyclic sulfate compounds of examples 6 to 7 have a benzene ring structure, and have better high-temperature storage properties.
Finally, it should be noted that the above embodiments are only for illustrating the technical solution of the present invention and not for limiting the scope of the present invention, and although the present invention has been described in detail with reference to the preferred embodiments, it should be understood by those skilled in the art that modifications or equivalent substitutions can be made to the technical solution of the present invention without departing from the spirit and scope of the technical solution of the present invention.

Claims (10)

1. An electrolyte comprises electrolyte salt, a nonaqueous organic solvent and an additive, and is characterized in that the additive comprises a phosphoramide compound and a cyclic sulfate compound, the structural formula of the phosphoramide compound is shown as a formula I or a formula II, the structural formula of the cyclic sulfate compound is shown as a formula III,
wherein R is 1 Is halogen or halogenated hydrocarbon, R 2 And R is 3 Each independently selected from at least one of hydrocarbyl, ester, silicon, and halogenated hydrocarbon, R 4 、R 5 And R is 6 Each independently selected from a hydrogen atom or a C1-C6 hydrocarbon group.
2. The electrolyte according to claim 1, wherein the phosphoramide compound is 0.01 to 5.00% by mass of the sum of the electrolyte salt, the nonaqueous organic solvent and the additive, and the cyclic sulfate compound is 0.01 to 2.00% by mass of the sum of the electrolyte salt, the nonaqueous organic solvent and the additive.
3. The electrolyte according to claim 1, wherein the phosphoramide compound is at least one selected from the group consisting of compound 1 to compound 6,
4. the electrolyte according to claim 1, wherein the cyclic sulfate compound is at least one selected from the group consisting of compound 7 to compound 12,
5. the electrolyte of claim 1, wherein the electrolyte salt is a sodium salt, a potassium salt, or a lithium salt.
6. The electrolyte of claim 1 wherein the nonaqueous organic solvent comprises at least one of a cyclic carbonate, a chain carbonate, a carboxylate, and a lactone.
7. The electrolyte of claim 6 wherein the nonaqueous organic solvent comprises at least one of dimethyl carbonate, diethyl carbonate, dipropyl carbonate, methylethyl carbonate, methylpropyl carbonate, ethylpropyl carbonate, ethylene carbonate, fluoroethylene carbonate, methyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, propyl propionate, gamma-butyrolactone, gamma-valerolactone, gamma-caprolactone, sigma-valerolactone, and epsilon-caprolactone.
8. The electrolyte according to claim 1, further comprising an auxiliary agent, wherein the auxiliary agent is a nitric acid compound, and the nitric acid compound accounts for 0.01-1.00% of the total mass of the electrolyte salt, the nonaqueous organic solvent, the additive and the nitric acid compound.
9. The electrolyte of claim 8, wherein the nitric compound comprises at least one of lithium nitrate, potassium nitrate, sodium nitrate, cesium nitrate, magnesium nitrate, barium nitrate, lithium nitrite, potassium nitrite, and cesium nitrite.
10. An alkali metal battery comprising a positive electrode material, a negative electrode material and an electrolyte, wherein the electrolyte is the electrolyte according to any one of claims 1 to 9.
CN202311073242.9A 2023-08-24 2023-08-24 Electrolyte and alkali metal cell Pending CN117059894A (en)

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Publication number Priority date Publication date Assignee Title
CN117558987B (en) * 2024-01-12 2024-05-03 江苏天鹏电源有限公司 Lithium ion battery electrolyte and lithium ion battery

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN117558987B (en) * 2024-01-12 2024-05-03 江苏天鹏电源有限公司 Lithium ion battery electrolyte and lithium ion battery

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