Trioxymethylene-containing sodium ion battery two-component electrolyte as well as preparation method and application thereof

Abstract

The invention discloses trioxymethylene-containing sodium ion battery two-component electrolyte as well as a preparation method and application thereof. The two-component electrolyte consists of a component A and a component B, the component A comprises electrolyte sodium salt, an electrolyte solvent and trioxymethylene; the component B comprises Lewis acid or a Lewis acid precursor. The two-component electrolyte is divided into a component A containing trioxymethylene and a component B containing an initiator. The two components are stable after being independently placed and can be stored for a long time. And when the battery needs to be used, the component A and the component B are mixed and added into the battery for use. A new thought is provided for storage and transportation of the trioxymethylene-containing sodium ion battery electrolyte, and industrial production of the trioxymethylene-containing semi-solid sodium ion battery is facilitated.

Description

Technical Field

[0001] This invention belongs to the field of sodium-ion battery technology, specifically relating to a two-component electrolyte for sodium-ion batteries containing trioxymethylene, its preparation method, and its application. Background Technology

[0002] In recent years, human activities have led to a sharp decline in fossil fuel resources, with some energy sources nearing depletion. The resulting environmental degradation and irrational resource utilization have had a significant impact on human life and production. To meet people's growing material and cultural needs while ensuring safe and sustainable production and living, the development of a new, safe, and environmentally friendly energy system is therefore urgently needed.

[0003] Currently, lithium-ion battery technology is the most mature in electrochemical energy storage. However, with the popularization of electric vehicles and the development of large-scale energy storage applications, lithium-ion batteries have gradually revealed the bottleneck problem of lithium resource scarcity. Sodium-ion batteries, as a new type of secondary chemical power source, not only do not face resource constraints in their raw materials, but also possess safety, high and low temperature performance, and high-rate charge / discharge capabilities, exhibiting significant resource and cost advantages. In applications such as large-scale electrochemical energy storage and low-speed electric vehicles, they are expected to complement and effectively replace lithium-ion batteries. However, like lithium-ion batteries, sodium-ion batteries use organic liquid electrolytes, and still pose safety hazards such as combustion and explosion after a short circuit or a rapid increase in battery temperature.

[0004] To overcome the leakage problems of liquid electrolytes, similar to lithium-ion batteries, researchers have begun to study inorganic solid electrolytes, solid polymer electrolytes, and organic / inorganic composite electrolytes to replace liquid electrolytes and improve the safety performance of sodium-ion batteries. However, due to low ionic conductivity or high interfacial impedance, the long-term cycle performance of all-solid-state batteries still lags significantly behind that of liquid batteries. Using semi-solid-state batteries is an effective means to maintain stable long-term cycle performance and improve battery safety. Adding trioxymethylene to the electrolyte transforms the free-flowing liquid electrolyte into a non-free-flowing semi-solid electrolyte, thus converting the liquid battery into a semi-solid battery and improving its safety performance. This semi-solid electrolyte has ionic conductivity close to that of liquid electrolytes, resulting in semi-solid-state batteries with cycle performance comparable to conventional liquid batteries, while also offering superior safety. Trioxymethylene can be initiated by Lewis acids. In lithium-ion batteries, LiPF6 and LiDFOB can serve as precursors for Lewis acids to initiate trioxymethylene polymerization, but in sodium-ion batteries, this reaction cannot be initiated by sodium salts. Summary of the Invention

[0005] To address the aforementioned technical problems, the present invention provides a two-component electrolyte, which is composed of component A and component B.

[0006] Component A includes an electrolyte sodium salt, an electrolyte solvent, and trioxymethylene;

[0007] Component B includes a Lewis acid or a Lewis acid precursor.

[0008] According to an embodiment of the present invention, the volume ratio of component A to component B is 5-50:1, preferably 5-20:1.

[0009] According to an embodiment of the present invention, the ionic conductivity of component A is 3.0-12.0 mS / cm. -1 An example is 3.0 mS cm -1 4.0mS cm -1 6.0 mS cm -1 8.0mS cm -1 10.0mS cm -1 12.0mS cm -1 .

[0010] According to embodiments of the present invention, the electrolyte sodium salt includes, but is not limited to, one or more of the following: NaPF6, NaBF4, NaAsF6, NaClO4, NaTFSI, NaFSI, NaBOB, NaPO2F2, and NaDFOB.

[0011] Preferably, the molar concentration of the electrolyte sodium salt in component A is 0.5-2.5 mol / L (M), more preferably 0.8-2.0 M, and exemplary values ​​are 0.5 M, 0.8 M, 1.0 M, 1.2 M, 1.5 M, and 2.0 M.

[0012] According to an embodiment of the present invention, the electrolyte solvent is used to dissolve the electrolyte sodium salt. Exemplarily, the electrolyte solvent includes, but is not limited to, one or more of the following: ethylene carbonate (EC), dimethyl carbonate (DMC), diethyl carbonate (DEC), methyl ethyl carbonate (EMC), propylene carbonate (PC), 1,3-dioxane (DOL), ethylene glycol dimethyl ether (DME), γ-butyrolactone (γ-BLO), tetraethylene glycol dimethyl ether (TEGDME), diethylene glycol dimethyl ether, and triethylene glycol dimethyl ether.

[0013] According to an embodiment of the present invention, the content of paraformaldehyde in component A is 5.0-40.0 wt%, preferably 15.0-35.0 wt%.

[0014] According to an embodiment of the present invention, component A may optionally include an electrolyte additive for forming a solid electrolyte interface film on the electrode surface to improve the cycle performance of the battery.

[0015] Preferably, the electrolyte additive includes, but is not limited to, at least one of: vinylene carbonate (VC), ethylene ethylene carbonate (VEC), fluoroethylene carbonate (FEC), propane sulfonate lactone (PS), 3-fluoropropane sulfonate lactone (FPS), 1,3-propenylpropane sulfonate lactone (PES), ethylene sulfite (ES), ethylene sulfate (DTD), and polyoxymethylene (POM) stabilizers. The POM stabilizers are used to modify the main chain structure of POM, improving its thermal decomposition temperature and high-temperature stability. Exemplarily, the POM stabilizers include, but are not limited to, at least one of: dioxolane compounds, compounds with monoepoxy functional groups, and compounds with polyepoxy functional groups.

[0016] Preferably, the dioxolane compound is selected from at least one of DOL, 4-methyl-1,3-dioxolane, etc.

[0017] Preferably, the compound with the monoepoxy functional group is selected from at least one of propylene oxide (PO), epichlorohydrin (ECH), epibromopropane, 1,2-epoxyhexane, propyl ethylene oxide, phenyl glycidyl ether, methyl 2,3-epoxypropionate, ethyl 2,3-epoxypropionate, benzyl glycidyl ether, and 2-biphenyl glycidyl ether.

[0018] Preferably, the compound with the polyepoxy functional group is selected from at least one of 1,2,7,8-diepoxyoctane, dicyclopentadiene epoxide, 1,5-hexadiene diepoxide, vinylcyclohexene dioxide, neopentyl glycol diglycidyl ether, ethylene glycol glycidyl ether, bisphenol A diglycidyl ether, glycerol triglycidyl ether, pentaerythritol glycidyl ether, 3,4-epoxyhexyl-3,4-epoxycyclohexyl carbamate, etc.

[0019] Preferably, the electrolyte additive in component A is 0.5-10.0 wt%, more preferably 1.0-7.0 wt%, and exemplary values ​​are 1.0 wt%, 2.0 wt%, 3.0 wt%, 5.0 wt%, 7.0 wt%, 8.0 wt%, 9.0 wt%, and 10.0 wt%.

[0020] According to an embodiment of the present invention, in component B, the Lewis acid or Lewis acid precursor is selected from at least one of boron trifluoride diethyl ether complex, tris(pentafluorophenyl)borane, LiPF6, LiBF4, lithium difluorooxalate borate (LiDFOB), etc.

[0021] According to an embodiment of the present invention, component B further includes an electrolyte solvent used to dissolve or dilute the Lewis acid or Lewis acid precursor. Exemplarily, the electrolyte solvent in component B includes, but is not limited to, one or more of the following: ethylene carbonate (EC), dimethyl carbonate (DMC), diethyl carbonate (DEC), methyl ethyl carbonate (EMC), propylene carbonate (PC), ethyl acetate (EA), propyl acetate (EP), ethyl propionate (PA), propyl propionate (PP), 1,3-dioxane (DOL), dimethyl ethylene glycol (DME), γ-butyrolactone (γ-BLO), tetraethylene glycol dimethyl ether (TEGDME), diethylene glycol dimethyl ether, and triethylene glycol dimethyl ether.

[0022] According to an embodiment of the present invention, the Lewis acid or Lewis acid precursor is present in component B at a content of 1.0-100.0 wt%, preferably 1.0-30.0 wt%, and even more preferably 1.5-12.0 wt%, with exemplary values ​​of 2.0 wt%, 3.0 wt%, 5.0 wt%, 7.0 wt%, 10.0 wt%, or 12.0 wt%.

[0023] According to an embodiment of the present invention, in the two-component electrolyte, the concentration of the sodium electrolyte salt is 0.8-2.0M, the concentration of paraformaldehyde is 5.0-30.0wt%, and the concentration of Lewis acid or Lewis acid precursor is 0.05-5.0wt%.

[0024] According to an embodiment of the present invention, the ionic conductivity of the two-component electrolyte is 3.0-12.0 mS / cm. -1 An example is 3.0 mS cm -1 4.0mS cm -1 6.0 mS cm -1 8.0mS cm -1 10.0mS cm -1 12.0mS cm -1 .

[0025] The present invention provides a method for preparing a two-component electrolyte, comprising: preparing component A and component B separately, and mixing component A and component B before use.

[0026] According to an embodiment of the present invention, in the two-component electrolyte, the concentration of the sodium electrolyte salt is 0.8-2.0M, the concentration of paraformaldehyde is 5.0-30.0wt%, and the concentration of Lewis acid or Lewis acid precursor is 0.05-5.0wt%.

[0027] The present invention also provides a semi-solid sodium-ion battery comprising the above-mentioned two-component electrolyte.

[0028] The present invention also provides a method for preparing the above-mentioned semi-solid sodium-ion battery, the method being:

[0029] The above-mentioned two-component electrolyte is injected into the cell of a sodium-ion battery and left to stand at 20-65°C for more than 5 hours to obtain the semi-solid sodium-ion battery.

[0030] The beneficial effects of this invention are:

[0031] When trioxymethylene is added to sodium-ion battery electrolyte, the solution remains very stable and polymerization does not occur because it does not contain an initiator that can polymerize trioxymethylene. If an initiator that can polymerize trioxymethylene is added directly during preparation, the electrolyte cannot be stored for long periods. This invention separates the two-component electrolyte into component A, containing trioxymethylene, and component B, containing an initiator. Both components are stable when stored separately and can be stored for extended periods. When needed, components A and B are mixed and added to the battery. This invention provides a new approach to the storage and transportation of trioxymethylene-containing sodium-ion battery electrolytes, which is beneficial for the industrial production of semi-solid-state sodium-ion batteries containing trioxymethylene. Detailed Implementation

[0032] The technical solution of the present invention will be further described in detail below with reference to specific embodiments. It should be understood that the following embodiments are merely illustrative and explanatory of the present invention, and should not be construed as limiting the scope of protection of the present invention. All technologies implemented based on the above content of the present invention are covered within the scope of protection intended by the present invention.

[0033] Unless otherwise stated, the raw materials and reagents used in the following examples are commercially available products or can be prepared by known methods.

[0034] Example 1

[0035] (1) NaPF6 was added to a solution with a DMC to EC volume ratio of 2:1 to achieve a concentration of 1.2 M. After complete dissolution, 15.0 wt% paraformaldehyde, 0.1 wt% epichlorohydrin, and 5.0 wt% fluoroethylene carbonate (FEC) were added (the contents of paraformaldehyde, epichlorohydrin, and FEC are based on component A), resulting in component A containing 1.2 M NaPF6. The conductivity of component A is 5.4 mS / cm. -1 The solution remains transparent after long-term storage, and no obvious changes are observed with the naked eye.

[0036] (2) LiPF6 was added to a mixed solution of DMC and EC in a volume ratio of 2:1 to obtain component B, which had a concentration of 12.0 wt%. Component B remained transparent for a long time, and no obvious changes were observed with the naked eye.

[0037] Component A and component B were mixed evenly at a volume ratio of 9:1 to obtain a sodium-ion battery electrolyte with a sodium salt concentration of approximately 1.0 M and containing 13.5 wt% paraformaldehyde, exhibiting an ionic conductivity of 6.3 mS / cm. -1 The solution is transparent in appearance. After standing at 55°C for 24 hours, a homogeneous, non-stratified white, polyoxymethylene-containing semi-solid polymer electrolyte is obtained.

[0038] The obtained sodium-ion electrolyte containing trioxymethylene was injected into the cell of a sodium-ion battery. After standing at room temperature for 24 hours to allow the electrolyte to fully wet the electrode material, it was then stood at 55°C for 24 hours to allow the trioxymethylene to polymerize, thus obtaining a semi-solid sodium-ion battery containing trioxymethylene.

[0039] Example 2

[0040] (1) NaPF6 was added to a solution containing EMC, DMC, and EC in a volume ratio of 1:1:1 to achieve a concentration of 1.0 M. Then, 20.0% trioxymethylene, 0.8 wt% dicyclopentadiene epoxide, and 4.0 wt% FEC were added to obtain component A containing 2.0 M NaPF6. The conductivity of component A was 4.3 mS / cm. -1 The solution remains transparent after long-term storage, and no obvious changes are observed with the naked eye.

[0041] (2) Boron trifluoride diethyl ether complex was added to a mixed solution of EMC, DMC and EC in a volume ratio of 1:1:1 to obtain component B containing Lewis acid. The solution of component B remained transparent for a long period, and no obvious changes were observed with the naked eye.

[0042] Component A and component B were mixed evenly at a volume ratio of 9:1 to obtain a sodium-ion battery electrolyte with a sodium salt concentration of 0.8 M and containing 18.0 wt% paraformaldehyde, exhibiting an ionic conductivity of 3.9 mS / cm. -1 The solution is transparent in appearance. After standing at 45°C for 24 hours, a homogeneous, non-stratified white, polyoxymethylene-containing semi-solid polymer electrolyte is obtained.

[0043] The obtained sodium-ion electrolyte containing trioxymethylene was injected into the cell of a sodium-ion battery. After standing at room temperature for 24 hours to allow the electrolyte to fully wet the electrode material, it was then stood at 45°C for 24 hours to allow the trioxymethylene to polymerize, thus obtaining a semi-solid sodium-ion battery containing trioxymethylene.

[0044] Example 3

[0045] (1) NaClO4 was added to a solution containing EMC, DEC, and EC in a volume ratio of 1:1:1 to achieve a concentration of 1.1 M. Then, 15.0 wt% paraformaldehyde, 0.06 wt% vinylcyclohexene dioxide, 2.0 wt% VC, and 2.0 wt% FEC were added to obtain component A containing 1.1 M NaClO4. The conductivity of component A was 5.2 mS / cm. -1 The solution remains transparent after long-term storage, and no obvious changes are observed with the naked eye.

[0046] (2) LiDFOB was added to a mixed solution of EMC, DMC and EC in a volume ratio of 1:1:1 to obtain component B with a concentration of 5.0 wt%. Component B remained transparent for a long time, and no obvious changes were observed with the naked eye.

[0047] Component A and component B were mixed uniformly at a volume ratio of 9.5:0.5 to obtain a sodium-ion battery electrolyte with a sodium salt concentration of approximately 1.05 M and containing 14.3 wt% paraformaldehyde, exhibiting an ionic conductivity of 6.2 mS / cm. -1 The solution is transparent in appearance. After standing at 45°C for 24 hours, a homogeneous, non-stratified white, polyoxymethylene-containing semi-solid polymer electrolyte is obtained.

[0048] The obtained sodium-ion electrolyte containing trioxymethylene was injected into the cell of a sodium-ion battery. After standing at room temperature for 24 hours to allow the electrolyte to fully wet the electrode material, it was then stood at 45°C for 24 hours to allow the trioxymethylene to polymerize, thus obtaining a semi-solid sodium-ion battery containing trioxymethylene.

[0049] Example 4

[0050] (1) NaPF6 was added to a solution containing EMC, EP, and EC in a volume ratio of 1:1:1 to achieve a concentration of 2.0 M. Then, 35 wt% polyoxymethylene, 1.4 wt% methyl 2,3-epoxypropionate, 2.0 wt% VC, and 1.0 wt% DTD were added to obtain component A containing 2.0 M NaPF6. The conductivity of component A was 4.5 mS / cm. -1 The solution remains transparent after long-term storage, and no obvious changes are observed with the naked eye.

[0051] (2) Add 5 wt% tris(pentafluorophenyl)borane to a mixed solution of EMC, EP, and EC in a volume ratio of 1:1:1 to obtain component B. Component B remains transparent for a long time, and no obvious changes are observed with the naked eye.

[0052] Component A and component B were mixed evenly at a volume ratio of 8:2 to obtain a sodium-ion battery electrolyte with a sodium salt concentration of 1.6 M and containing 28.0 wt% paraformaldehyde, exhibiting an ionic conductivity of 8.1 mS / cm. -1The solution is transparent in appearance. When the solution is placed at 50°C for 24 hours, a homogeneous, non-stratified white, polyoxymethylene-containing semi-solid electrolyte is obtained.

[0053] The obtained sodium-ion electrolyte containing trioxymethylene was injected into the cell of a sodium-ion battery. After standing at room temperature for 24 hours to allow the electrolyte to fully wet the electrode material, it was then stood at 50°C for 24 hours to allow the trioxymethylene to polymerize, thus obtaining a semi-solid sodium-ion battery containing trioxymethylene.

[0054] Compare with Example 1

[0055] When component A of Example 1 was placed at 50°C and left to stand for 24 hours, the electrolyte remained clear and transparent, indicating that when this electrolyte was injected into a sodium-ion battery, paraformaldehyde would not polymerize, and a semi-solid sodium-ion battery could not be obtained.

[0056] The embodiments of the present invention have been described above by way of example. However, the scope of protection of the present invention is not limited to the above embodiments. Any modifications, equivalent substitutions, improvements, etc., made by those skilled in the art within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A two-component electrolyte, characterized in that, It consists of component A and component B; Component A includes an electrolyte sodium salt, an electrolyte solvent, and trioxymethylene; Component B includes a Lewis acid or a Lewis acid precursor.

2. The two-component electrolyte according to claim 1, characterized in that, The volume ratio of component A to component B is 5-50:1; Preferably, the ionic conductivity of component A is 3.0-12.0 mS / cm. -1 ; Preferably, the electrolyte sodium salt is selected from one or more of NaPF6, NaBF4, NaAsF6, NaClO4, NaTFSI, NaFSI, NaBOB, NaPO2F2, or NaDFOB; Preferably, the molar concentration of the electrolyte sodium salt in component A is 0.5-2.5 mol / L; Preferably, the electrolyte solvent is selected from one or more of ethylene carbonate, dimethyl carbonate, diethyl carbonate, methyl ethyl carbonate, propylene carbonate, 1,3-dioxane, ethylene glycol dimethyl ether, γ-butyrolactone, tetraethylene glycol dimethyl ether, diethylene glycol dimethyl ether, or triethylene glycol dimethyl ether.

3. The two-component electrolyte according to claim 1 or 2, characterized in that, The content of paraformaldehyde in component A is 5.0-40.0 wt%.

4. The two-component electrolyte according to any one of claims 1-3, characterized in that, Component A further includes an electrolyte additive, which is selected from at least one of vinylene carbonate, ethylene ethylene carbonate, fluoroethylene carbonate, propane sulfonate lactone, 3-fluoropropane sulfonate lactone, 1,3-propenylpropane sulfonate lactone, ethylene sulfite, ethylene sulfate and polyoxymethylene stabilizer. Preferably, the polyoxymethylene stabilizing additive is selected from at least one of dioxolane compounds, compounds with monoepoxy functional groups, or compounds with polyepoxy functional groups. Preferably, the dioxolane compound is selected from 1,3-dioxolane or 4-methyl-1,3-dioxolane; Preferably, the compound with the monoepoxy functional group is selected from propylene oxide, epichlorohydrin, epibromopropane, 1,2-epoxyhexane, propyl ethylene oxide, phenyl glycidyl ether, methyl 2,3-epoxypropionate, ethyl 2,3-epoxypropionate, benzyl glycidyl ether, or 2-biphenyl glycidyl ether. Preferably, the compound with the polyepoxy functional group is selected from 1,2,7,8-diepoxyoctane, dicyclopentadiene epoxide, 1,5-hexadiene diepoxide, vinylcyclohexene dioxide, neopentyl glycol diglycidyl ether, ethylene glycol glycidyl ether, bisphenol A diglycidyl ether, glycerol triglycidyl ether, pentaerythritol glycidyl ether, or 3,4-epoxyhexyl-3,4-epoxycyclohexyl carboxylate. Preferably, the electrolyte additive is present in component A at a content of 0.5-10.0 wt%.

5. The two-component electrolyte according to any one of claims 1-4, characterized in that, In component B, the Lewis acid or Lewis acid precursor is selected from boron trifluoride diethyl ether complex, tris(pentafluorophenyl)borane, LiPF6, LiBF4 or lithium difluorooxalate borate. Preferably, the Lewis acid or Lewis acid precursor is present in component B at a content of 1.0-100.0 wt%.

6. The two-component electrolyte according to any one of claims 1-5, characterized in that, Component B further includes an electrolyte solvent selected from one or more of ethylene carbonate, dimethyl carbonate, diethyl carbonate, methyl ethyl carbonate, propylene carbonate, ethyl acetate, propyl acetate, ethyl propionate, propyl propionate, 1,3-dioxane, ethylene glycol dimethyl ether, γ-butyrolactone, tetraethylene glycol dimethyl ether, diethylene glycol dimethyl ether, or triethylene glycol dimethyl ether.

7. The two-component electrolyte according to any one of claims 1-6, characterized in that, In the two-component electrolyte, the concentration of the sodium salt of the electrolyte is 0.8-2.0M, the concentration of paraformaldehyde is 5.0-30.0wt%, and the concentration of Lewis acid or Lewis acid precursor is 0.05-5.0wt%. Preferably, the ionic conductivity of the two-component electrolyte is 3.0-12.0 mS / cm. -1 .

8. The method for preparing the two-component electrolyte according to any one of claims 1-7, characterized in that, It includes: Prepare component A and component B separately, and mix them together before use.

9. A semi-solid sodium-ion battery, characterized in that, It includes the two-component electrolyte as described in any one of claims 1-7.

10. The method for preparing the semi-solid sodium-ion battery according to claim 9, characterized in that, The method is as follows: The bicomponent electrolyte according to any one of claims 1-7 is injected into the cell of a sodium-ion battery and left to stand at 20-65°C for more than 5 hours to obtain the semi-solid sodium-ion battery.