CN115347239A - Low-temperature-resistant sodium ion battery electrolyte and sodium ion battery - Google Patents
Low-temperature-resistant sodium ion battery electrolyte and sodium ion battery Download PDFInfo
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- CN115347239A CN115347239A CN202211112410.6A CN202211112410A CN115347239A CN 115347239 A CN115347239 A CN 115347239A CN 202211112410 A CN202211112410 A CN 202211112410A CN 115347239 A CN115347239 A CN 115347239A
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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
- H01M10/054—Accumulators with insertion or intercalation of metals other than lithium, e.g. with magnesium or aluminium
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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
- H01M10/42—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
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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
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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 low-temperature-resistant sodium ion battery electrolyte and a sodium ion battery, wherein the electrolyte comprises the following components: the electrolyte comprises an organic solvent, electrolyte sodium salt and a low-melting-point linear carboxylic ester additive, wherein the low-melting-point linear carboxylic ester additive is carboxylic ester containing-RCOOR-group, and the low-melting-point linear carboxylic ester accounts for 1-30% of the volume ratio of the electrolyte of the low-temperature resistant sodium ion battery. The low-temperature-resistant sodium ion battery electrolyte has the characteristics of good low-temperature conductivity, good interface stability and excellent rate capability.
Description
Technical Field
The invention relates to the technical field of sodium ion batteries, in particular to low-temperature-resistant sodium ion battery electrolyte and a sodium ion battery.
Background
The sodium ion battery has rich resource reserves and low cost, and is expected to be widely applied in the field of energy storage. However, for the sodium ion battery for energy storage, due to the difference between the application environment and the lithium ion battery, the sodium ion battery has higher requirements on high and low temperature charge and discharge capacity, rate capability and cycle stability.
At present, most of commercial sodium ion battery electrolytes are composed of ethylene carbonate with high viscosity and high freezing point (< 36.4 ℃) and linear carbonate solvents with low viscosity, wherein sodium hexafluorophosphate is used as a sodium salt. The ethylene carbonate can be reduced and decomposed on the surface of a negative electrode to generate a compact SEI film under a lower potential (2.71V vs SHE), so that the continuous decomposition of the electrolyte is weakened, and the gassing and the ballooning of the sodium ion battery are avoided, but the ethylene carbonate is separated out under a low-temperature condition (0 ℃) due to the higher freezing point, and the normal use of the sodium ion battery is influenced. In addition, ethylene carbonate is oxidized and decomposed at a relatively high potential (> 4.3V), a large amount of gas is generated, and a safety accident is caused in a serious case. In order to solve the problem, in recent years, propylene carbonate is widely applied to lithium battery/sodium electrolyte as an electrolyte component with high oxidation resistance, but the propylene carbonate is subjected to nucleophilic attack by sodium ions at a lower potential (about 2.71V vs SHE), so that nucleophilic addition ring-opening reaction occurs, and the propylene carbonate is continuously decomposed. Therefore, the reduction of the electrolyte on the negative electrode side and the oxidation side reaction on the positive electrode side can be weakened to a certain extent by reasonably adjusting the proportion of the ethylene carbonate to the propylene carbonate in the electrolyte. However, ethylene carbonate and propylene carbonate belong to the same cyclic carbonate type, and have high dielectric constant and high viscosity characteristics. At a lower temperature (minus 40 ℃), the high viscosity and high freezing point of the cyclic carbonate lead to the lower conductivity of sodium ions, which seriously affects the diffusion of sodium ions and leads to the deterioration of the rate capability and low-temperature performance of the sodium ion battery.
Disclosure of Invention
The invention aims to provide a low-temperature-resistant sodium ion battery electrolyte and a sodium ion battery, which have the characteristics of good low-temperature conductivity, good interface stability and excellent rate capability.
The invention can be realized by the following technical scheme:
the invention discloses a low-temperature-resistant sodium ion battery electrolyte, which comprises the following components: the electrolyte comprises an organic solvent, electrolyte sodium salt and a low-melting-point linear carboxylic ester additive, wherein the low-melting-point linear carboxylic ester additive is carboxylic ester containing-RCOOR-group, and the low-melting-point linear carboxylic ester accounts for 1-30% of the volume ratio of the electrolyte of the low-temperature resistant sodium ion battery. .
In the invention, the ratio of the organic solvent, the sodium salt and the low-melting-point linear carboxylic ester additive is reasonably optimized, so that the rate performance, the low-temperature performance and the cycling stability of the sodium-ion battery are improved. The low-temperature performance, the rate capability and the cycling stability are very important for the large-scale application of the sodium-ion battery. The invention aims at the technical scheme that the market-sold electrolyte formula is difficult to simultaneously meet the defects of the above conditions. According to the invention, the organic solvent, the electrolyte sodium salt and the low-melting-point linear carboxylic ester additive are mixed according to a specific proportion, so that the electrolyte with high ionic conductivity and good stability under a low-temperature condition can be obtained, the requirements of the sodium ion battery are met, and the following problems are effectively solved:
1; the cyclic carbonates used in the electrolyte have a high melting point and a generally high viscosity of >1.9. At normal temperature, the sodium ion diffusion coefficient is low. At low temperature (minus 50 ℃), the cyclic carbonate is easy to separate out, which causes the separation of the organic solvent and the sodium salt of the electrolyte, influences the diffusion of sodium ions and causes the inactivation of the sodium ion battery.
2. Ethylene carbonate in cyclic carbonate used in the electrolyte can be oxidized and decomposed under a higher charging potential (> 4.0Vvs SHE) to generate a large amount of gases such as combustible olefin, alkane and hydrogen, and the like, so that potential safety hazards exist. And the propylene carbonate in the cyclic carbonate generates nucleophilic ring-opening reaction with sodium ions under lower discharge potential (-2.71V vs SHE) to generate linear alkyl carbonate, and then is reduced and decomposed into propylene and oxygen under the action of free radicals, thereby causing battery heave damage,
3. the dielectric constant of the weak-polarity organic solvent in the electrolyte is generally lower than 3.2, sodium salt cannot be effectively dissolved, so that the internal resistance of the electrolyte is larger, and the electrolyte is easy to generate oxidation-reduction reaction under higher charging potential (> 4.0Vvs SHE)/lower discharging potential (-2.71V vs SHE), so that the gas generation and the swelling of the sodium-ion battery are caused.
Further, the carboxylic acid ester is one or more of ethylhexyl sebacate, dioctyl phthalate, ethyl butyrate, ethyl acetate and/or butyl acetate.
Further, the protection casing includes that the body of rod that sets up bottom cup joints the hole on the round platform and along the cover body that bottom external diameter edge leaned out the extension on the round platform, and the cover body is the step form cover body more than the second grade.
Further, the organic solvent is cyclic carbonate and/or a weak polar organic solvent; the cyclic carbonate is ethylene carbonate and/or propylene carbonate; the weak polar organic solvent is one or more of dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate, methyl propyl carbonate, trimethyl borate, triethyl borate, tripropyl borate, ethylene glycol dimethyl ether, methyl ethyl ether, methyl butyl ether and/or ethyl butyl ether.
Further comprises a film forming additive, wherein the film forming additive is one or a mixture of more than two of fluoroethylene carbonate, ethylene sulfite, vinylene carbonate, propylene carbonate trifluoride and/or 1, 3-propane sultone.
Furthermore, the volume ratio of the cyclic carbonate to the electrolyte of the low-temperature resistant sodium ion battery is 10-75%; the weak-polarity organic solvent accounts for 10-50% of the volume ratio of the low-temperature-resistant sodium ion battery electrolyte; the film forming additive accounts for 1-20% of the volume ratio of the low temperature resistant sodium ion battery electrolyte.
Further, the sodium salt of the electrolyte is one or more of sodium perchlorate, sodium hexafluorophosphate, sodium bis (fluorosulfonyl) imide, sodium bis (trifluoromethylsulfonyl) imide and sodium trifluoromethanesulfonate.
Furthermore, the concentration of the electrolyte sodium salt in the electrolyte of the low-temperature-resistant sodium ion battery is 0.5-1.2 mol/L.
Furthermore, the density of the electrolyte of the low-temperature resistant sodium ion battery is 1.0-1.5 g/cm <3 >, and the conductivity is 6-12 mS/cm.
Another aspect of the present invention is to protect a sodium ion battery using the above low temperature resistant sodium ion battery electrolyte.
The invention relates to a low-temperature-resistant sodium ion battery electrolyte and a sodium ion battery, which have the following beneficial effects:
first, the low-temperature conductivity is good, the linear carboxylic ester in the low-temperature resistant organic electrolyte has the characteristics of low melting point, low viscosity and the like, and the mutual chelation between the linear carboxylic ester and the cyclic carbonate can ensure that the electrolyte is not solidified at a lower temperature (minus 50 ℃), ensure that sodium ions have good electronic conductivity at a low temperature, and further improve the low-temperature discharge performance of the sodium ion battery.
Secondly, the interface stability is good, and the ethylhexyl sebacate, the dioctyl sebacate and the dioctyl phthalate in the low-temperature resistant organic electrolyte can be subjected to a reductive decomposition reaction preferentially at the negative electrode side at low temperature to generate a compact and stable SEI film, so that the cyclic carbonate/linear carbonate can be prevented from being decomposed at the negative electrode side, and the electrode interface stability can be effectively improved. And ethyl butyrate, ethyl acetate and butyl acetate in the low-temperature-resistant organic electrolyte can be adsorbed on the side surface of the positive electrode at low temperature, and are decomposed under the catalytic action of transition metal atoms of the positive electrode material to generate a stable CEI layer, so that other side reactions are effectively avoided, and the circulation stability of the sodium-ion battery is improved.
Thirdly, the multiplying power performance is excellent, the radius of Na ions is larger, and the charge distribution outside the core is less. Therefore, the linear carboxylate in the low-temperature-resistant organic electrolyte has a low coordination number with Na + at low temperature, low desolvation energy and a high sodium removal rate on the surface of an electrode, and can effectively improve the dynamics of sodium ions at the interface of the electrode so as to improve the rate capability of a sodium ion battery; in addition, the linear carboxylic ester in the low-temperature-resistant organic electrolyte has an effective synergistic effect with an organic solvent and an electrolyte sodium salt in a proper proportion at a low temperature, and the low-temperature charge-discharge characteristics and the excellent rate performance of the sodium-ion battery can be further ensured.
Drawings
Fig. 1 is a rate performance curve (1c = 110mah/g) of a soft package battery of application example 1, iron sodium pyrophosphate/hard carbon system;
FIG. 2 is a graph of the high and low temperature performance of soft-packaged batteries of application example 2, wherein the soft-packaged batteries are made of sodium iron pyrophosphate phosphate/hard carbon systems;
fig. 3 is a cycle stability curve of the soft-package battery of application example 3, wherein the soft-package battery is made of sodium iron pyrophosphate/hard carbon system.
Detailed Description
In order to make the technical solutions of the present invention better understood by those skilled in the art, the following detailed description of the present invention is provided with reference to the accompanying drawings.
The invention discloses a low-temperature-resistant sodium ion battery electrolyte, which comprises the following components: the electrolyte comprises an organic solvent, electrolyte sodium salt and a low-melting-point linear carboxylic ester additive, wherein the low-melting-point linear carboxylic ester additive is carboxylic ester containing-RCOOR-group, and the low-melting-point linear carboxylic ester accounts for 1-30% of the volume ratio of the electrolyte of the low-temperature resistant sodium ion battery. .
Further, the carboxylic acid ester is one or more of ethylhexyl sebacate, dioctyl phthalate, ethyl butyrate, ethyl acetate and/or butyl acetate.
Further, the protection casing includes that the body of rod that sets up bottom cup joints the hole on the round platform and along the cover body that bottom external diameter edge leaned out the extension on the round platform, and the cover body is the step form cover body more than the second grade.
Further, the organic solvent is cyclic carbonate and/or a weak polar organic solvent; the cyclic carbonate is ethylene carbonate and/or propylene carbonate; the weak polar organic solvent is one or more of dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate, methyl propyl carbonate, trimethyl borate, triethyl borate, tripropyl borate, ethylene glycol dimethyl ether, methyl ethyl ether, methyl butyl ether and/or ethyl butyl ether.
Further comprises a film forming additive, wherein the film forming additive is one or a mixture of more than two of fluoroethylene carbonate, ethylene sulfite, vinylene carbonate, propylene carbonate trifluoride and/or 1, 3-propane sultone.
Furthermore, the volume ratio of the cyclic carbonate to the electrolyte of the low-temperature resistant sodium ion battery is 10-75%; the weak-polarity organic solvent accounts for 10-50% of the volume ratio of the low-temperature-resistant sodium ion battery electrolyte; the film forming additive accounts for 1-20% of the volume ratio of the low temperature resistant sodium ion battery electrolyte.
Further, the sodium salt of the electrolyte is one or more of sodium perchlorate, sodium hexafluorophosphate, sodium bis (fluorosulfonyl) imide, sodium bis (trifluoromethylsulfonyl) imide and sodium trifluoromethanesulfonate.
Furthermore, the concentration of the electrolyte sodium salt in the electrolyte of the low-temperature resistant sodium ion battery is 0.5-1.2 mol/L.
Furthermore, the density of the electrolyte of the low-temperature resistant sodium ion battery is 1.0-1.5 g/cm <3 >, and the conductivity is 6-12 mS/cm.
Another aspect of the invention is to protect a sodium ion battery using the above low temperature resistant sodium ion battery electrolyte.
According to the invention, the low-melting-point and low-viscosity linear carboxylate additive is introduced into the electrolyte, so that the average viscosity of the electrolyte is reduced, the diffusion coefficient of sodium ions in the electrolyte is increased, and the rate capability and low-temperature performance of the sodium ion battery are improved. Besides the solvents, the invention also introduces common linear organic solvents (including low-viscosity organic solvents such as linear carbonate, ethers, borate and the like) and film forming additives, further optimizes the electrolyte formula and improves the cycling stability of the sodium-ion battery.
Example 1
A low-temperature resistant organic electrolyte comprises the following components in concentration:
the volume ratio of the cyclic carbonate is 30% (propylene carbonate/ethylene carbonate is 1.5, 1.5), the volume ratio of the low-melting-point linear carboxylic ester is 40% (ethylhexyl sebacate 2.0, dioctyl sebacate 2.0), the volume ratio of the weak-polarity organic solvent is 25% (diethyl carbonate), the volume ratio of the film forming additive is 5% (fluoroethylene carbonate), and the concentration of the sodium salt of the electrolyte is 0.8mol/L (sodium hexafluorophosphate).
Example 2
A low-temperature resistant organic electrolyte comprises the following components in concentration:
the volume ratio of the cyclic carbonate was 30% (1.5 propylene carbonate/ethylene carbonate, 1.5), the volume ratio of the low melting linear carboxylic acid ester was 40% (ethyl butyrate 3.0, dioctyl phthalate 1.0), the volume ratio of the weakly polar organic solvent was 20% (diethyl carbonate/dimethyl carbonate, 1.0.
Example 3
A low-temperature resistant organic electrolyte comprises the following components in concentration:
the volume ratio of the cyclic carbonate was 40% (2.0 for propylene carbonate/ethylene carbonate), the volume ratio of the low-melting linear carboxylic acid ester was 30% (2.0 for ethylhexyl sebacate, 1.0 for ethyl acetate), the volume ratio of the weak-polar organic solvent was 15% (0.5 for diethyl carbonate/dimethyl carbonate/ethyl methyl carbonate.
Example 4
The low-temperature-resistant organic electrolyte comprises the following components in concentration:
the volume ratio of the cyclic carbonate was 40% (2.0 for propylene carbonate/ethylene carbonate), the volume ratio of the low-melting linear carboxylic acid ester was 30% (1.5 for butyl acetate, 1.5 for dioctyl phthalate), the volume ratio of the weakly polar organic solvent was 15% (0.5 for diethyl carbonate/dimethyl carbonate/ethyl methyl carbonate.
Example 5
A low-temperature resistant organic electrolyte comprises the following components in concentration:
the volume ratio of the cyclic carbonate is 50% (propylene carbonate/ethylene carbonate is 3), the volume ratio of the low-melting linear carboxylic ester is 30% (ethylhexyl sebacate 1.0, ethyl butyrate 1.0, dioctyl sebacate 1.0), the volume ratio of the weak polar organic solvent is 10% (trimethyl borate), the volume ratio of the film forming additive is 10% (fluoroethylene carbonate), and the concentration of the sodium salt of the electrolyte is 1mol/L (sodium hexafluorophosphate).
Example 6
The low-temperature-resistant organic electrolyte comprises the following components in concentration:
the volume ratio of the cyclic carbonate was 50% (propylene carbonate/ethylene carbonate 3.
Example 7
The low-temperature-resistant organic electrolyte comprises the following components in concentration:
the volume ratio of the cyclic carbonate was 60% (propylene carbonate/vinyl carbonate 4: 2), the volume ratio of the low-melting linear carboxylic ester was 20% (ethylhexyl sebacate 0.5, ethyl acetate 0.5, dioctyl sebacate 0.5, dioctyl phthalate 0.5), the volume ratio of the weakly polar organic solvent was 10% (trimethyl borate/triethyl borate/tripropyl borate 0.2.
Example 8
The low-temperature-resistant organic electrolyte comprises the following components in concentration:
the volume ratio of the cyclic carbonate is 60% (propylene carbonate/vinyl carbonate is 4, 2), the volume ratio of the low-melting linear carboxylic ester is 25% (ethylhexyl sebacate 1.0, dioctyl sebacate 0.75, dioctyl phthalate 0.75), the volume ratio of the weak polar organic solvent is 10% (ethylene glycol dimethyl ether), the volume ratio of the film forming additive is 5% (fluoroethylene carbonate), and the concentration of the sodium salt of the electrolyte is 0.8mol/L (sodium hexafluorophosphate).
Example 9
A low-temperature resistant organic electrolyte comprises the following components in concentration:
the volume ratio of the cyclic carbonate was 70% (propylene carbonate/ethylene carbonate 4: 3), the volume ratio of the low melting linear carboxylic acid ester was 20% (ethyl butyrate 1.0, ethyl acetate 0.5, butyl acetate 0.5), the volume ratio of the weakly polar organic solvent was 5% (ethylene glycol dimethyl ether/methyl ethyl ether 0.25, film forming additive was 5% (fluoroethylene carbonate/ethylene sulfite 0.2), the concentration of the sodium salt of the electrolyte was 1mol/L (sodium perchlorate was 0.5mol/L, bis (trifluoromethylsulfonyl) imide sodium was 0.5 mol/L).
Example 10
A low-temperature resistant organic electrolyte comprises the following components in concentration:
the volume ratio of the cyclic carbonate was 70% (propylene carbonate/vinyl carbonate 4: 3), the volume ratio of the low-melting linear carboxylic acid ester was 20% (ethylhexyl sebacate 0.5, dioctyl sebacate 0.25, dioctyl phthalate 0.25, ethyl butyrate 0.25, ethyl acetate 0.5, butyl acetate 0.25), the volume ratio of the weakly polar organic solvent was 5% (diethyl carbonate/ethylene glycol dimethyl ether/trimethyl borate 0.1.
Application example 1
In a glove box filled with argon, a low melting linear carboxylic ester: cyclic carbonate ester: the linear organic solvent was mixed uniformly in a ratio of 40% to 38% to 18% by volume, and then 2% fluoroethylene carbonate and 2%1, 3-propanesultone were added. And finally adding sodium hexafluorophosphate to obtain the electrolyte with the concentration of 0.8 mol/L. The electrolyte is injected into a soft package battery with capacity of 3500mAh and sodium iron pyrophosphate phosphate as a positive electrode and hard carbon as a negative electrode, and the rate capability, low-temperature performance and cycling stability of the battery are tested. As shown in fig. 1, the rate performance of the NFPP/HC pouch battery is 82.3% of 0.2C at 20C (1c = 110mah/g) ultra-high rate, and the battery shows excellent rapid charge and discharge capacity. Fig. 2 shows the high and low temperature performance of the NFPP/HC soft package battery, and the capacity utilization rate of the NFPP/HC soft package battery reaches 80.5% at the normal temperature at the low temperature of-40 ℃, so that the NFPP/HC soft package battery has extremely high environmental adaptability. Fig. 3 further tests the cycling stability of the NFPP/HC pouch cell, which still has a capacity retention rate as high as 84.2% over 1000 weeks of cycling.
Application example 2
In a glove box filled with argon, a low melting linear carboxylic acid ester: cyclic carbonate ester: the linear organic solvent is uniformly mixed according to the volume ratio of 45 percent to 40 percent to 10 percent, and then 3 percent of fluoroethylene carbonate and 2 percent of vinylene carbonate are added. And finally adding sodium hexafluorophosphate to obtain the electrolyte with the concentration of 1 mol/L. The electrolyte is injected into a soft package battery with sodium iron pyrophosphate phosphate as a positive electrode and hard carbon as a negative electrode, and the rate performance, the low-temperature performance and the cycling stability of the battery are tested. The data are shown in table 1.
Application example 3
In a glove box filled with argon, a low melting linear carboxylic ester: cyclic carbonate ester: the linear organic solvent was mixed uniformly in a ratio of 40% by volume to 15% by volume, and then 2% fluoroethylene carbonate, 2% vinylene carbonate and 1%1, 3-propanesultone were added. Finally, sodium hexafluorophosphate and sodium bis (trifluoromethylsulfonyl) imide (molar ratio 0.4. The electrolyte is injected into a soft package battery with sodium vanadium phosphate as a positive electrode and hard carbon as a negative electrode, and the rate performance, the low-temperature performance and the cycling stability of the battery are tested. The data are shown in table 1.
Application example 4
In a glove box filled with argon, a low melting linear carboxylic ester: cyclic carbonate ester: the linear organic solvent was mixed uniformly in a ratio of 45% by volume to 35% by volume to 15% by volume, and then 2% fluoroethylene carbonate, 2% vinylene carbonate and 1%1, 3-propanesultone were added. Finally, sodium hexafluorophosphate, sodium perchlorate and sodium bis (trifluoromethylsulfonyl) imide (molar ratio 0.6. The electrolyte is injected into a soft package battery with sodium vanadium phosphate as a positive electrode and hard carbon as a negative electrode, and the rate performance, the low-temperature performance and the cycling stability of the battery are tested. The data are shown in table 1.
Application example 5
In a glove box filled with argon, a low melting linear carboxylic ester: cyclic carbonate ester: the linear organic solvent is uniformly mixed according to the volume ratio of 35 percent to 45 percent to 20 percent, and then 5 percent fluoroethylene carbonate is added. Finally, sodium hexafluorophosphate and sodium perchlorate (molar ratio 0.7. The electrolyte is injected into a soft package battery with sodium ferric sulfate as a positive electrode and hard carbon as a negative electrode, and the rate capability, the low-temperature performance and the cycling stability of the battery are tested. The data are shown in table 1.
Comparative example 1
In a glove box filled with argon, cyclic carbonate: the linear carbonate was mixed in a proportion of 78% by volume to 18% by volume and then 2% by volume of fluoroethylene carbonate and 2% by volume of 1, 3-propanesultone were added. And finally adding sodium hexafluorophosphate to obtain the electrolyte with the concentration of 0.8 mol/L. The electrolyte is injected into a soft package battery with sodium iron pyrophosphate phosphate as a positive electrode and hard carbon as a negative electrode, and the rate performance, the low-temperature performance and the cycling stability of the battery are tested. The data are shown in table 1.
Comparative example 2
In a glove box filled with argon, cyclic carbonate: the linear carbonate is uniformly mixed according to the volume ratio of 85 percent to 10 percent, and then 3 percent of fluoroethylene carbonate and 2 percent of vinylene carbonate are added. And finally adding sodium hexafluorophosphate to obtain the electrolyte with the concentration of 1 mol/L. The electrolyte is injected into a soft package battery with sodium ferric pyrophosphate phosphate as a positive electrode and hard carbon as a negative electrode, and the rate capability, the low-temperature performance and the cycling stability of the battery are tested. The data are shown in table 1.
Comparative example 3
In a glove box filled with argon, cyclic carbonate: the linear carbonate was mixed uniformly in a proportion of 80% by volume to 15% by volume, and then 2% fluoroethylene carbonate, 2% vinylene carbonate and 1%1, 3-propanesultone were added. Finally, sodium hexafluorophosphate and sodium bis (trifluoromethylsulfonyl) imide (molar ratio 0.4. The electrolyte is injected into a soft package battery with sodium vanadium phosphate as a positive electrode and hard carbon as a negative electrode, and the rate performance, the low-temperature performance and the cycling stability of the battery are tested. The data are shown in table 1.
Comparative example 4
In a glove box filled with argon, cyclic carbonate: the linear carbonate was uniformly mixed in a proportion of 80% by volume to 15% by volume, and then 2% fluoroethylene carbonate, 1% vinylene carbonate, 1% ethylene sulfite and 1%1, 3-propanesultone were added. Finally, sodium hexafluorophosphate, sodium perchlorate and sodium bis (trifluoromethylsulfonyl) imide (molar ratio 0.6. The electrolyte is injected into a soft package battery with sodium vanadium phosphate as a positive electrode and hard carbon as a negative electrode, and the rate performance, low-temperature performance and cycle stability of the battery are tested. The data are shown in table 1.
Comparative example 5
In a glove box filled with argon, 95% cyclic carbonate and 5% fluoroethylene carbonate were mixed homogeneously. Finally, sodium hexafluorophosphate and sodium perchlorate (molar ratio 0.7. The electrolyte is injected into a soft package battery with sodium ferric sulfate as a positive electrode and hard carbon as a negative electrode, and the rate capability, the low-temperature performance and the cycling stability of the battery are tested. The mixture ratio of the above examples is detailed in table 1, and the electrochemical performance test results are shown in table 2.
TABLE 1 example solvent ratios and corresponding material systems
TABLE 2 electrochemical Performance test results
The above embodiments are only specific embodiments of the present invention, and the description thereof is specific and detailed, but not construed as limiting the scope of the present invention. It should be noted that, for a person skilled in the art, several variations and modifications are possible without departing from the inventive concept, and such obvious alternatives fall within the scope of the invention.
Claims (10)
1. The low-temperature-resistant sodium-ion battery electrolyte is characterized by comprising the following components: the low-melting-point linear carboxylic ester additive is carboxylic ester containing-RCOOR-group, and the low-melting-point linear carboxylic ester accounts for 1-30% of the volume ratio of the electrolyte of the low-temperature resistant sodium ion battery. .
2. The low temperature resistant sodium ion battery electrolyte of claim 1, wherein: the carboxylic ester is one or more of ethylhexyl sebacate, dioctyl phthalate, ethyl butyrate, ethyl acetate and/or butyl acetate.
3. The low temperature resistant sodium ion battery electrolyte of claim 2, wherein: the protection casing cup joints the hole and follows the cover body that bottom external diameter edge leaned out and extends on the round platform including the body of rod that sets up bottom on the round platform, the cover body is the step form cover body more than the second grade.
4. The low temperature resistant sodium ion battery electrolyte of claim 3, wherein: the organic solvent is cyclic carbonate and/or a weak polar organic solvent;
the cyclic carbonate is ethylene carbonate and/or propylene carbonate;
the weak polar organic solvent is one or a mixture of more than two of dimethyl carbonate, diethyl carbonate, methyl ethyl carbonate, methyl propyl carbonate, trimethyl borate, triethyl borate, tripropyl borate, ethylene glycol dimethyl ether, methyl ethyl ether, methyl butyl ether and/or ethyl butyl ether.
5. The low temperature resistant sodium ion battery electrolyte of claim 4, wherein: the film-forming additive is one or a mixture of more than two of fluoroethylene carbonate, ethylene sulfite, vinylene carbonate, propylene carbonate trifluoride and/or 1, 3-propane sultone.
6. The low temperature resistant sodium ion battery electrolyte of claim 5, wherein: the cyclic carbonate accounts for 10-75% of the volume ratio of the low-temperature resistant sodium ion battery electrolyte; the weak-polarity organic solvent accounts for 10-50% of the volume ratio of the low-temperature-resistant sodium ion battery electrolyte; the film forming additive accounts for 1-20% of the volume ratio of the low temperature resistant sodium ion battery electrolyte.
7. The low temperature resistant sodium ion battery electrolyte of claim 6, wherein: the electrolyte sodium salt is one or more of sodium perchlorate, sodium hexafluorophosphate, sodium bis (fluorosulfonyl) imide, sodium bis (trifluoromethylsulfonyl) imide and sodium trifluoromethanesulfonate.
8. The low temperature resistant sodium ion battery electrolyte of claim 7, wherein: the concentration of the electrolyte sodium salt in the electrolyte of the low-temperature resistant sodium ion battery is 0.5-1.2 mol/L.
9. The low temperature resistant sodium ion battery electrolyte of claim 8, wherein: the density of the electrolyte of the low-temperature resistant sodium ion battery is 1.0-1.5 g/cm <3 >, and the conductivity is 6-12 mS/cm.
10. A sodium ion battery using the low temperature resistant sodium ion battery electrolyte of any one of claims 1-9.
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN115602926A (en) * | 2022-12-16 | 2023-01-13 | 河北省科学院能源研究所（Cn） | High-temperature-resistant electrolyte and preparation method and application thereof |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN115602926A (en) * | 2022-12-16 | 2023-01-13 | 河北省科学院能源研究所（Cn） | High-temperature-resistant electrolyte and preparation method and application thereof |
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