An ultra-low-temperature-resistant electrolyte for sodium-ion batteries, a preparation method thereof and a sodium-ion battery

Abstract

The application belongs to the technical field of sodium ion batteries, and particularly relates to a sodium ion battery super-low-temperature-resistant electrolyte, a preparation method thereof and a sodium ion battery. The sodium ion battery electrolyte provided in the application introduces a compound with an amide group, an epoxy butane group, a sulfur-oxygen group and a halogen group as an additive, improves the kinetic process of sodium ions and the uniform deposition of an interface layer and other performances in the sodium ion battery electrolyte, thereby improving the performance of the electrolyte in a super-low-temperature (-40 DEG C) environment, enabling the sodium ion battery containing the electrolyte to have a cycle life of more than 900 hours, and thereby solving the technical problem that there is no super-low-temperature-resistant sodium ion battery electrolyte in the prior art.

Description

Technical Field

[0001] This application belongs to the field of sodium-ion battery technology, and particularly relates to a sodium-ion battery with ultra-low temperature resistant electrolyte and preparation method, and a sodium-ion battery. Background Technology

[0002] In fields such as aerospace, deep-sea exploration, and polar scientific research, there is a need for high-performance cryogenic secondary batteries that can operate in ultra-low temperature environments (-40℃). Compared to lithium-ion batteries, sodium batteries offer advantages due to the abundance of sodium metal resources and their extremely high theoretical capacity (1165mAh g / g). -1 Sodium batteries have advantages such as a higher standard potential (-2.71V) and a smaller Stokes radius than lithium ions, which enhances ion diffusion capabilities, making them more promising for use in ultra-low temperature environments compared to lithium-ion batteries.

[0003] In ultra-low temperature environments, the liquid electrolyte in sodium-ion batteries is prone to freezing, leading to an exponential decrease in ionic conductivity. Simultaneously, the viscosity and impedance of the electrolyte increase dramatically at ultra-low temperatures, resulting in slow ion movement and ultimately causing a sharp deterioration in battery performance, even rendering the battery unusable. Furthermore, the electrolyte plays a crucial role in sodium-ion batteries, transferring sodium ions between the positive and negative electrodes. During charging and discharging, the electrolyte reacts with the negative electrode to form an interfacial film. This interfacial film plays a vital role in preventing the continuous reaction between the electrolyte and electrodes, consuming electrolyte, inhibiting sodium dendrite formation, and transporting ions. However, currently, there is a lack of ultra-low temperature resistant electrolytes. In ordinary electrolytes, sodium ions are prone to kinetic impairment and uneven deposition at the interfacial layer at ultra-low temperatures, resulting in poor performance and limiting the expansion of sodium-ion battery applications. Summary of the Invention

[0004] In view of this, this application provides a sodium-ion battery electrolyte resistant to ultra-low temperatures, a preparation method thereof, and a sodium-ion battery, to solve the technical problem of the lack of sodium-ion battery electrolytes resistant to ultra-low temperatures in the prior art.

[0005] The first aspect of this application provides a sodium-ion battery ultra-low temperature resistant electrolyte, the composition of which includes sodium salt, solvent and ultra-low temperature resistant additive; the chemical formula of the additive is shown in Formula I.

[0006]

[0007] In Equation I, R1 is a halogen element.

[0008] Preferably, in Formula I, R1 is any one of bromine, iodine, and chlorine.

[0009] Preferably, the amount of the ultra-low temperature resistant additive in the sodium-ion battery ultra-low temperature electrolyte is 1-5 wt%.

[0010] Preferably, the sodium salt is selected from at least one of sodium perchlorate, sodium hexafluorophosphate, sodium trifluoromethanesulfonate, sodium bis(trifluoromethanesulfonyl)imide, and sodium bis(trifluoromethanesulfonyl)imide.

[0011] Preferably, the concentration of sodium salt in the ultra-low temperature resistant electrolyte of the sodium-ion battery is 0.5 to 2 mol / L.

[0012] The sodium salt is selected from any two of sodium perchlorate, sodium hexafluorophosphate, sodium trifluoromethanesulfonate, sodium bis(trifluoromethanesulfonyl)imide, and sodium bis(trifluoromethanesulfonyl)imide.

[0013] The molar ratio of any two sodium salts among sodium perchlorate, sodium hexafluorophosphate, sodium trifluoromethanesulfonate, sodium bis(trifluoromethanesulfonyl)imide and sodium bis(trifluoromethanesulfonyl)imide is (5-8):(5-2).

[0014] The solvent is selected from at least one of cyclic carbonate electrolytes, chain carbonate electrolytes, and phosphate ester electrolytes.

[0015] Preferably, the solvent is selected from a mixed solution of cyclic carbonate electrolytes, chain carbonate electrolytes, and phosphate ester electrolytes;

[0016] The volume ratio of the mixed solution is 1:1:2.

[0017] Preferably, the cyclic carbonate electrolyte is selected from ethylene carbonate electrolyte and / or propylene carbonate electrolyte;

[0018] The chain carbonate electrolyte is selected from diethyl carbonate electrolyte and / or dimethyl carbonate electrolyte;

[0019] The phosphate ester electrolyte is selected from trimethyl phosphate and / or triethyl phosphate electrolytes.

[0020] The second aspect of this application provides a method for preparing a sodium-ion battery ultra-low temperature resistant electrolyte, comprising the steps of: adding sodium salt and ultra-low temperature resistant additives to a solvent in a glove box and stirring evenly to obtain a sodium-ion battery ultra-low temperature resistant electrolyte.

[0021] A third aspect of this application provides a sodium-ion battery, including a positive electrode, a negative electrode, a separator, and the aforementioned ultra-low temperature resistant electrolyte.

[0022] Preferably, the positive electrode is selected from Prussian blue compounds or Prussian white compounds;

[0023] The negative electrode is selected from sodium metal negative electrodes;

[0024] The diaphragm is selected from any one of polypropylene film (PP), polyethylene film (PE), or PP / PE composite film.

[0025] In summary, this application provides a sodium-ion battery ultra-low temperature resistant electrolyte, its preparation method, and a sodium-ion battery. The ultra-low temperature resistant electrolyte provided by this application includes sodium salt, solvent, and additives. The additives incorporate amide groups and epoxy butyl groups into their chemical structure. These amide and epoxy butyl groups can reduce the viscosity of the sodium-ion battery electrolyte and improve its wettability, enabling the electrolyte to maintain a good ion migration rate even in ultra-low temperature environments. Furthermore, the introduced sulfoxy groups and halogen groups react with the sodium anode to form an interface layer containing sodium sulfur compounds and sodium halide compounds. The sodium sulfur compounds in this interface layer can inhibit further reactions between the electrolyte and the anode, making the electrolyte more stable. This also reduces interfacial impedance and improves sodium ion migration rate. The sodium halide compounds in the interfacial layer have a low sodium ion diffusion barrier and high mechanical strength, which can promote uniform deposition of sodium ions and inhibit the formation of sodium dendrites, thereby improving the ion conduction performance of the electrolyte. The sodium-ion battery ultra-low temperature resistant electrolyte provided in this application improves the kinetic process of sodium ions and the phenomenon of sodium dendrites in the interfacial layer of sodium-ion battery electrolyte under ultra-low temperature (-40℃) environment by introducing compounds with amide groups, epoxy butyl groups, sulfoxy groups and halogen groups as additives, thereby solving the technical problem of lack of ultra-low temperature resistant sodium-ion battery electrolytes in the prior art. Attached Figure Description

[0026] To more clearly illustrate the technical solutions in the specific embodiments of this application or the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this application. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0027] Figure 1 The graph shows the performance test results of a sodium battery assembled with an ultra-low temperature electrolyte and a sodium battery assembled with a conventional electrolyte, prepared by the method provided in Example 2 of this application. Detailed Implementation

[0028] This application provides a sodium-ion battery electrolyte resistant to ultra-low temperatures, a preparation method thereof, and a sodium-ion battery, to solve the technical problem of the lack of sodium-ion battery electrolytes resistant to ultra-low temperatures in the prior art.

[0029] The technical solutions of this application will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this application. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0030] Example 1

[0031] Given the shortcomings of existing sodium-ion battery electrolytes, such as poor performance due to their inability to withstand low temperatures, Embodiment 1 of this application provides a sodium-ion battery ultra-low temperature resistant electrolyte. The composition of this ultra-low temperature resistant electrolyte includes sodium salt, solvent, and ultra-low temperature resistant additives. The solvent in the electrolyte may freeze at low temperatures, leading to a decrease in performance, while the additives can improve the electrolyte's performance. Simultaneously, the additives participate in the reaction with the sodium anode to form an interfacial film. Therefore, by improving the additives in the electrolyte, the performance of both the electrolyte and the interfacial film can be improved simultaneously. This application introduces novel ultra-low temperature resistant additives. An additive is used to improve the performance of conventional sodium-ion battery electrolytes in ultra-low temperature environments. The chemical structure of the ultra-low temperature resistant additive is shown in Formula I. The ultra-low temperature resistant additive introduces amide groups, epoxy butyl groups, sulfoxy groups, and halogen groups. The amide groups, epoxy butyl groups, sulfoxy groups, and halogen groups can improve the viscosity and wettability of the electrolyte at low temperatures, and also participate in regulating the interface layer formed by the reaction between the electrolyte and the sodium metal anode, improving the performance of the interface layer on the surface of the sodium metal anode, thereby overcoming the defect of poor performance of current sodium-ion battery electrolytes in ultra-low temperature environments.

[0032] The sodium salts and solvents used in the ultra-low temperature resistant electrolyte for sodium-ion batteries provided in this application are the commonly used sodium salts and solvents for sodium-ion batteries.

[0033] Example 2

[0034] Example 2 of this application provides a method for preparing the sodium-ion battery ultra-low temperature resistant electrolyte described in Example 1. The preparation method includes the steps of preparing sodium salt, solvent and ultra-low temperature resistant additive, and mixing step.

[0035] The steps for preparing the sodium salt, solvent, and cryogenic additive include: In a glove box, using a pipette, add 1 ml of triethyl phosphate, 0.5 ml of ethylene carbonate (preheated and dissolved), and 0.5 ml of diethyl carbonate as solvents to a volumetric flask. Then, weigh 0.098 g of sodium perchlorate and 0.0344 g of sodium trifluoromethanesulfonate as sodium salts, and add 0.0705 g of cryogenic additive to the volumetric flask containing the solvent. Stir magnetically for 4 hours to prepare the cryogenic electrolyte for sodium-ion batteries. The protective gas in the glove box is argon, and the contents of oxygen and water are both less than 0.01 ppm. The sodium salt concentration in the cryogenic electrolyte is 0.5 mol / L, and the cryogenic additive content is 3 wt%.

[0036] Example 3

[0037] Example 3 of this application provides a method for preparing the sodium-ion battery ultra-low temperature resistant electrolyte described in Example 1. The preparation method includes the steps of preparing sodium salt, solvent and ultra-low temperature resistant additive, and mixing step.

[0038] The steps for preparing the sodium salt, solvent, and cryogenic additive include: In a glove box, using a pipette, add 1 ml of triethyl phosphate, 0.5 ml of ethylene carbonate (preheated and dissolved), and 0.5 ml of propylene carbonate as solvents to a volumetric flask. Then, weigh 0.0613 g of sodium perchlorate and 0.086 g of sodium trifluoromethanesulfonate as sodium salts, and add 0.0248 g of cryogenic additive to the volumetric flask containing the solvent. Stir magnetically for 4 hours to prepare the cryogenic electrolyte for sodium-ion batteries. The protective gas in the glove box is argon, and the contents of oxygen and water are both less than 0.01 ppm. The sodium salt concentration in the cryogenic electrolyte is 0.5 mol / L, and the cryogenic additive content is 1 wt%.

[0039] Example 4

[0040] Example 4 of this application provides a method for preparing the sodium-ion battery ultra-low temperature resistant electrolyte described in Example 1. The preparation method includes the steps of preparing sodium salt, solvent and ultra-low temperature resistant additive, and mixing step.

[0041] The steps for preparing the sodium salt, solvent, and cryogenic additive include: In a glove box, using a pipette, add 1 ml of triethyl phosphate, 0.5 ml of ethylene carbonate (preheated and dissolved), and 0.5 ml of propylene carbonate as solvents to a volumetric flask. Then, weigh 0.074 g of sodium perchlorate and 0.0688 g of sodium trifluoromethanesulfonate as sodium salts, and add 0.1175 g of cryogenic additive to the volumetric flask containing the solvent. Stir magnetically for 4 hours to prepare the cryogenic electrolyte for sodium-ion batteries. The protective gas in the glove box is argon, and the contents of oxygen and water are both less than 0.01 ppm. The sodium salt concentration in the cryogenic electrolyte is 0.5 mol / L, and the cryogenic additive content is 5 wt%.

[0042] Example 5

[0043] Example 5 of this application provides a method for preparing the sodium-ion battery ultra-low temperature resistant electrolyte described in Example 1. The preparation method includes the steps of preparing sodium salt, solvent and ultra-low temperature resistant additive, and mixing step.

[0044] The steps for preparing the sodium salt, solvent, and cryogenic additive include: In a glove box, using a pipette, add 1 ml of trimethyl phosphate, 0.5 ml of ethylene carbonate (preheated and dissolved), and 0.5 ml of propylene carbonate as solvents to a volumetric flask. Then, weigh 0.2688 g of sodium hexafluorophosphate and 0.0688 g of sodium trifluoromethanesulfonate as sodium salts, and add 0.028 g of cryogenic additive to the volumetric flask containing the solvent. Stir magnetically for 2 hours to prepare the cryogenic electrolyte for sodium-ion batteries. The protective gas in the glove box is argon, and the contents of oxygen and water are both less than 0.01 ppm. The sodium salt concentration in the cryogenic electrolyte is 1 mol / L, and the cryogenic additive content is 1 wt%.

[0045] Example 6

[0046] Example 6 of this application provides a method for preparing the sodium-ion battery ultra-low temperature resistant electrolyte described in Example 1. The preparation method includes the steps of preparing sodium salt, solvent and ultra-low temperature resistant additive, and mixing step.

[0047] The steps for preparing the sodium salt, solvent, and cryogenic additive include: adding 1 ml of trimethyl phosphate, 0.5 ml of propylene carbonate, and 0.5 ml of dimethyl carbonate as solvents to a volumetric flask using a pipette in a glove box; then weighing 0.812 g of sodium bis(fluorosulfonyl)imide as sodium salt and 0.0928 g of cryogenic additive into the volumetric flask containing the solvent; and stirring magnetically for 6 hours to prepare the cryogenic electrolyte for sodium-ion batteries. The protective gas in the glove box is argon, and the contents of oxygen and water are both less than 0.01 ppm. The sodium salt concentration in the cryogenic electrolyte is 2 mol / L, and the cryogenic additive content is 3 wt%.

[0048] Example 7

[0049] Example 7 of this application provides a method for preparing the sodium-ion battery ultra-low temperature resistant electrolyte described in Example 1. The preparation method includes the steps of preparing sodium salt, solvent and ultra-low temperature resistant additive, and mixing step.

[0050] The steps for preparing the sodium salt, solvent, and cryogenic additive include: In a glove box, using a pipette, add 1 ml of trimethyl phosphate, 0.5 ml of propylene carbonate, and 0.5 ml of dimethyl carbonate as solvents to a volumetric flask. Then, weigh 0.4872 g of sodium difluorosulfonamide and 0.074 g of sodium perchlorate as sodium salts, and add 0.0853 g of cryogenic additive to the volumetric flask containing the solvent. Stir magnetically for 6 hours to prepare the cryogenic electrolyte for sodium-ion batteries. The protective gas in the glove box is argon, and the contents of oxygen and water are both less than 0.01 ppm. The sodium salt concentration in the cryogenic electrolyte is 1.5 mol / L, and the cryogenic additive content is 3 wt%.

[0051] Example 8

[0052] Example 8 of this application provides a method for preparing the sodium-ion battery ultra-low temperature resistant electrolyte described in Example 1. The preparation method includes the steps of preparing sodium salt, solvent and ultra-low temperature resistant additive and mixing step.

[0053] The steps for preparing the sodium salt, solvent, and cryogenic additive include: In a glove box, using a pipette, add 1 ml of triethyl phosphate, 0.5 ml of propylene carbonate, and 0.5 ml of dimethyl carbonate as solvents to a volumetric flask. Then, weigh 0.4848 g of sodium bis(trifluoromethanesulfonyl)imide and 0.049 g of sodium perchlorate as sodium salts, and add 0.137 g of cryogenic additive to the volumetric flask containing the solvent. Stir magnetically for 6 hours to prepare the cryogenic electrolyte for sodium-ion batteries. The protective gas in the glove box is argon, and the contents of oxygen and water are both less than 0.01 ppm. The concentration of sodium salt in the cryogenic electrolyte is 1 mol / L, and the content of the cryogenic additive is 5 wt%.

[0054] Example 9

[0055] Example 9 of this application provides a method for preparing the sodium-ion battery ultra-low temperature resistant electrolyte described in Example 1. The preparation method includes the steps of preparing sodium salt, solvent and ultra-low temperature resistant additive, and mixing step.

[0056] The steps for preparing the sodium salt, solvent, and cryogenic additive include: In a glove box, using a pipette, add 1 ml of triethyl phosphate, 0.5 ml of ethylene carbonate, and 0.5 ml of diethyl carbonate as solvents to a volumetric flask. Then, weigh 0.2688 g of sodium hexafluorophosphate and 0.0688 g of sodium trifluoromethanesulfonate as sodium salts, and add 0.0766 g of cryogenic additive to the volumetric flask containing the solvent. Stir magnetically for 6 hours to prepare the cryogenic electrolyte for sodium-ion batteries. The protective gas in the glove box is argon, and the contents of oxygen and water are both less than 0.01 ppm. The sodium salt concentration in the cryogenic electrolyte is 1 mol / L, and the cryogenic additive content is 3 wt%.

[0057] Experimental Example 1

[0058] Example 1 of this application provides performance testing of the ultra-low temperature resistant electrolyte for sodium-ion batteries prepared by the method described in Example 2. The performance test involved assembling the ultra-low temperature resistant electrolyte, positive and negative electrodes, and a separator into a sodium battery and testing its performance at ultra-low temperatures (-40°C). Additionally, a conventional commercial electrolyte (NaClO4 + EC:PC (1:1)) was also assembled into a sodium battery and its ultra-low temperature (-40°C) performance was tested. The performance test results are as follows: Figure 1 As shown, from Figure 1It can be seen that after 50 hours of cycling, the overpotential of the conventional commercial electrolyte (NaClO4+EC:PC(1:1)) assembled into a sodium battery increases rapidly, indicating that its cycle life is around 50 hours. In contrast, the sodium-ion battery with ultra-low temperature resistant electrolyte provided in Example 2 of this application has a cycle life of over 900 hours after being assembled into a sodium battery. This shows that the additives containing amide groups, epoxy butyl groups, sulfoxy groups and halogen groups introduced into the electrolyte provided in this application can greatly improve the kinetic process of sodium ions and the uniform deposition of the interface layer at ultra-low temperatures, which is beneficial to expanding the application of sodium-ion batteries in polar scientific research and other fields.

[0059] The above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application.

Claims

1. A sodium-ion battery electrolyte resistant to ultra-low temperatures, characterized in that, It includes sodium salts, solvents, and ultra-low temperature resistant additives; the chemical formula of the additives is shown in Formula I; Equation I; In Equation I, R1 is a halogen element; The solvent is selected from at least one of cyclic carbonate electrolytes, chain carbonate electrolytes, and phosphate ester electrolytes; The amount of ultra-low temperature resistant additive added to the sodium-ion battery ultra-low temperature resistant electrolyte is 1~5wt%.

2. The sodium-ion battery ultra-low temperature resistant electrolyte according to claim 1, characterized in that, In Formula I, R1 is any one of bromine, iodine, and chlorine.

3. The sodium-ion battery ultra-low temperature resistant electrolyte according to claim 1, characterized in that, The sodium salt is selected from at least one of sodium perchlorate, sodium hexafluorophosphate, sodium trifluoromethanesulfonate, sodium bis(trifluoromethanesulfonyl)imide, and sodium bis(trifluoromethanesulfonyl)imide.

4. The sodium-ion battery ultra-low temperature resistant electrolyte according to claim 1, characterized in that, The sodium salt concentration in the ultra-low temperature resistant electrolyte of the sodium-ion battery is 0.5~2 mol / L.

5. The sodium-ion battery ultra-low temperature resistant electrolyte according to claim 1, characterized in that, The cyclic carbonate electrolyte is selected from ethylene carbonate electrolyte and / or propylene carbonate electrolyte; The chain carbonate electrolyte is selected from diethyl carbonate electrolyte and / or dimethyl carbonate electrolyte; The phosphate ester electrolyte is selected from trimethyl phosphate and / or triethyl phosphate electrolytes.

6. A method for preparing a sodium-ion battery ultra-low temperature resistant electrolyte according to any one of claims 1-5, characterized in that, The steps include: adding sodium salt and ultra-low temperature resistant additives to a solvent in a glove box and stirring until homogeneous to obtain an ultra-low temperature resistant electrolyte for sodium-ion batteries.

7. A sodium-ion battery, characterized in that, It includes a positive electrode, a negative electrode, a separator, and a sodium-ion battery electrolyte resistant to ultra-low temperatures as described in any one of claims 1-5.

8. A sodium-ion battery according to claim 7, characterized in that, The positive electrode is selected from Prussian blue compounds or Prussian white compounds; The negative electrode is selected from sodium metal negative electrodes; The diaphragm is selected from any one of polypropylene film (PP), polyethylene film (PE), or PP / PE composite film.

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