CN116544513A - Wide-temperature high-pressure electrolyte for sodium ion battery and preparation method and application thereof - Google Patents

Abstract

The invention provides a wide-temperature-range high-pressure non-aqueous electrolyte, and a preparation method and application thereof, and belongs to the technical field of sodium ion batteries. The electrolyte consists of inorganic sodium salt, mixed solvent and additive. The sodium salt is sodium perchlorate 0.9-2M; the organic solvent is one or more of propylene carbonate, ethylene carbonate and ethylene glycol dimethyl ether, and the additive is one of fluoroethylene carbonate and tris (pentafluorophenyl) borane. The invention also provides application of the electrolyte in a high-temperature high-pressure sodium ion battery. The electrolyte additive tris (pentafluorophenyl) borane can be used as an anion receptor, participates in internal solvation configuration coordination through strong interaction with anions, is decomposed preferentially to generate a thin and stable anode-electrolyte interface film rich in inorganic components, and improves the electrochemical reaction stability of an electrolyte-electrode interface. The high-temperature high-pressure electrolyte is applied to a sodium ion battery taking Prussian blue, sodium vanadium phosphate and layered oxide as positive electrodes, and the cycle performance of the high-temperature high-pressure electrolyte is remarkably improved. In addition, the invention also provides the application of the sodium ion battery containing the high-voltage electrolyte additive in a wide temperature range, and compared with the traditional electrolyte, the electrolyte provided by the invention has the advantages that the ionic conductivity is kept higher in a wide temperature range, the excellent cycling stability is kept in a temperature range of minus 30 ℃ to 60 ℃, and a feasible scheme is provided for realizing the wide temperature range and high energy density of the sodium ion battery.

Description

Wide-temperature high-pressure electrolyte for sodium ion battery and preparation method and application thereof

Technical Field

The invention belongs to the technical field of sodium ion batteries, and particularly relates to a wide-temperature high-pressure non-aqueous electrolyte, and a preparation method and application thereof.

Background

In order to cope with global climate change, the duty ratio of renewable clean energy in the energy structure of China is improved, wherein the large-scale energy storage technology is an indispensable supporting technology for accessing renewable energy into a power grid. Lithium ion batteries are the electrochemical energy storage technology of the most representative at present, and occupy most of the markets of portable 3C electronic products, but with the popularization of large-scale energy storage and electric automobile technologies, lithium resources and cost are the biggest bottlenecks for future development. The sodium ion battery has the advantages of abundant resources and low price, and is considered as a power grid-level large-scale energy storage technology with the most development prospect in the later lithium era.

The resistance of sodium-ion batteries to seasonal and periodic daily temperature fluctuations greatly affects the stability and cycling of secondary batteries. The decomposition of the electrolyte at the surface of the positive electrode is accelerated at high temperatures, and the resulting positive electrode/electrolyte interface film (CEI) tends to be unstable, accompanied by continued decomposition of the electrolyte, electrode surface reconstruction, and rapid degradation of the battery capacity. Meanwhile, under the condition of high-rate discharge, the temperature inside the battery is higher, and the formed local high-temperature environment can also generate interface side reactions such as rapid decomposition of electrolyte and the like, so that the cycle stability and the safety performance of the battery are greatly damaged.

At the same time, the energy density of the sodium ion battery is lower than that of the lithium ion battery. Besides the energy density of the battery is improved by exploring a novel high-voltage positive electrode material, the improvement of the working voltage of the battery is a simple, convenient and effective method. Under the high-pressure condition, the oxidative decomposition of the electrolyte and the instability of the CEI film are aggravated, the stable CEI film construction is realized through the optimization of the electrode liquid, and the strong support can be provided for the operation of the sodium ion battery under the extreme working conditions of high temperature, high pressure and the like. Changing the target properties of the electrolyte by adding small amounts of additives is a more efficient and economical method. Fluoroethylene carbonate (FEC) is an electrolyte additive commonly used in sodium ion batteries at present, has good film forming effect and oxidation resistance, but is difficult to perfectly adapt to the application of the sodium ion batteries under high temperature and high pressure. Therefore, in order to meet the increasing demand, there is a need to develop high-pressure sodium-ion battery electrolytes having a wider temperature range of operation.

Disclosure of Invention

The invention aims to improve the capacity retention rate and the cycling stability of the existing battery electrolyte in a high-temperature and high-pressure environment, and provides a high-temperature and high-pressure sodium ion battery electrolyte, and a preparation method and application thereof.

In order to solve the technical problems, the invention adopts the following technical scheme:

mixing sodium salt and mixed ether ester electrolyte to form a basic electrolyte, and mixing a high-voltage electrolyte additive with the basic electrolyte to form the sodium ion battery electrolyte suitable for a wide-temperature-range high-voltage environment, wherein the concentration of the sodium salt is 0.8-1.5 mol/L.

In some of these embodiments, the sodium salt is selected from at least one of sodium perchlorate (NaClO 4), sodium hexafluorophosphate (NaPF 6), sodium bis (fluorosulfonyl) imide (NaFSI), sodium bis (trifluoromethanesulfonyl) imide (naffsi), sodium trifluoromethanesulfonate (NaOTf).

In some of these embodiments, the carbonate-based solvent is a mixture of one or more of Propylene Carbonate (PC), ethylene Carbonate (EC), dimethyl carbonate (DMC), diethyl carbonate (DEC), ethyl Methyl Carbonate (EMC).

In some of these embodiments, the ether solvent is one of ethylene glycol dimethyl ether (DME), diethylene glycol dimethyl ether (G2), tetraethylene glycol dimethyl ether (G4), tetrahydrofuran (THF).

In some of these embodiments, the high-pressure electrolyte additive is at least one of fluoroethylene carbonate (FEC), tris (trimethylsilane) phosphite (TMSP), tripropylphosphate (TPP), triphenylphosphine oxide (TPPO), tris (pentafluorophenyl) phosphine (TPFPP), triisopropylborate (TIB), trimethyl borate (TMB), tris (pentafluorophenyl) boron (TPFPB), 4-aminobenzoic acid (4-ABA), benzotriazole (BzTz), and terthiophene (3 THP).

In some embodiments, the mole fraction of the sodium salt in the wide temperature range high pressure sodium ion battery electrolyte is 0.8mol/L to 1.5mol/L.

In some embodiments, in the high-pressure sodium ion battery electrolyte with wide temperature range, the mass percentage of the sodium salt is 10% -40%, the mass percentage of the mixed ether ester solvent is 10% -50%, and the mass percentage of the additive is 0.5% -5%.

The invention provides a sodium ion battery which comprises the wide-temperature-range high-voltage electrolyte, and preferably comprises a positive plate, a diaphragm, the wide-temperature-range high-voltage electrolyte and a negative plate.

Preferably, the positive electrode sheet is Prussian Blue (PB), sodium vanadium phosphate (NVP) and layered oxide Na0.44MnO2 (NMO).

Preferably, the separator is glass fiber.

Preferably, the negative electrode sheet is a sodium sheet.

The invention also provides a preparation method of the wide-temperature-range high-voltage electrolyte, which comprises the following steps:

1) Fully mixing and stirring carbonate and ether organic solvents under the condition of argon atmosphere to obtain a prepurified solution;

2) Dissolving sodium salt into the prepurified solution obtained in the step 2);

3) Adding a molecular sieve into the prepurified solution obtained in the step 2), standing for 8 hours, and finally removing the molecular sieve to obtain a purified solution;

4) And (3) dissolving an electrolyte additive into the purified solution obtained in the step (3), and uniformly mixing to obtain the wide-temperature high-pressure electrolyte.

Preferably, the molecular sieve isOr->Molecular sieves.

The beneficial effects of the invention are as follows:

according to the invention, the boron high-pressure additive is selected to replace fluoroethylene carbonate electrolyte, and the high-pressure additive is subjected to preferential oxidative decomposition before solvolysis, so that a thin and stable CEI interface layer is formed on the surface of the electrode, and the interface reaction activity is reduced, thereby improving the electrochemical performance. Compared with the novel solvent with wider electrochemical window, the scheme of introducing the high-pressure additive is simpler, the effect is more obvious, and the economic benefit is high. Compared with the traditional electrolyte, the electrolyte provided by the invention has higher ionic conductivity and electrochemical stability. When the electrolyte provided by the invention is applied to a sodium ion battery, prussian blue, sodium vanadium phosphate and layered oxide all show better high-temperature cycling stability under the high cut-off voltage of 4.2V. In addition, the excellent cycling stability is kept in the temperature range of-30 to 60 ℃, and a feasible scheme is provided for realizing the wide temperature range and high energy density of the sodium ion battery.

Drawings

FIG. 1 shows the ionic conductivities of the electrolytes of example 1 and comparative examples 1, 2, 3 at different temperatures;

FIG. 2 is a graph showing the wide temperature range cycling performance at-30 to 60℃of Na||NVP batteries assembled from the electrolytes of example 1 and comparative examples 1, 2, and 3;

FIG. 3 is an electrochemical window of the electrolytes of example 1 and comparative example 1 at a high temperature of 60 ℃;

FIG. 4 is the cycle performance of the electrolyte assemblies of example 1 and comparative example 1, na||NVP at high temperature 60 ℃;

FIG. 5 is the cycle performance at 60℃of the assembled Na||NVP cells of example 1 and comparative examples 2-4, 6-9;

FIG. 6 is Na||PB showing electrolyte assembly of example 1 and the cycling performance of na||nmo cells at 60 ℃.

Detailed Description

The present invention will be described in further detail with reference to the following specific examples, but the present invention is not limited to the following examples.

Noun abbreviations

Sodium perchlorate: naClO4

Propylene carbonate: PC (personal computer)

Ethylene carbonate: EC (EC)

Diethyl carbonate: DEC (digital enhanced cordless telecommunications)

Ethylene glycol dimethyl ether: DME

Tris (pentafluorophenyl) borane: TPFPB

Fluoroethylene carbonate: FEC (forward error correction)

Example 1

The embodiment provides a wide-temperature high-pressure electrolyte, and the preparation method comprises the following steps: the EC and DME mixed solvent with the volume ratio of 1:1 is prepared, 979.52mg of NaClO4 is added into 4mL of mixed solution to make the concentration of the mixed solvent be 1mol/L, and TPFPB accounting for 3% of the total mass of the electrolyte is added to obtain the high-temperature high-pressure electrolyte.

Example 2

The electrolyte provided in this embodiment differs from that of example 1 in that TPFPB accounts for 1% of the total mass of the electrolyte.

Example 3

The electrolyte provided in this embodiment differs from that of example 1 in that TPFPB accounts for 2% of the total mass of the electrolyte.

Example 4

The electrolyte provided in this embodiment differs from that of example 1 in that TPFPB accounts for 4% of the total mass of the electrolyte.

Example 5

The electrolyte provided in this embodiment differs from that of example 1 in that TPFPB accounts for 5% of the total mass of the electrolyte.

Comparative example 1

The embodiment provides an electrolyte, and the preparation method comprises the following steps: a mixed solvent of EC and DME was prepared in a volume ratio of 1:1, and 979.52mg of NaClO4 was added to 4mL of the mixed solution so that the concentration thereof was 1mol/L.

Comparative example 2

This embodiment provides an electrolyte that differs from example 1 in that 3% fec is used instead of 3% tpfpb.

Comparative example 3

The embodiment provides an electrolyte, and the preparation method comprises the following steps: a mixed solvent of EC and PC was prepared in a volume ratio of 1:1, and 979.52mg of NaClO4 was added to 4mL of the mixed solution so that the concentration was 1mol/L.

Comparative example 4

The embodiment provides an electrolyte, and the preparation method comprises the following steps: an EC and PC mixed solvent with a volume ratio of 1:1 was prepared, 979.52mg of NaClO4 was added to a 4mL mixed solution so that the concentration was 1mol/L, and then FEC was added in an amount of 3% based on the total mass of the electrolyte.

Comparative example 5

The present embodiment provides an electrolyte which is substantially the same as the preparation method of example 1, except that DME in the mixed solvent is replaced with PC.

Comparative example 6

The preparation method of the electrolyte provided by the implementation comprises the following steps: 979.52mg NaClO4 in 4mL of PC solution was added.

Comparative example 7

The preparation method of the electrolyte provided by the implementation comprises the following steps: a volume ratio of 1:1 of EC and DEC mixed solvent was prepared, and 979.52mg of NaClO4 was added.

Comparative example 8

The preparation method of the electrolyte provided by the implementation comprises the following steps: 979.52mg of NaClO4 was added to 4mL of PC, and 3% of FEC by mass of the total electrolyte was added.

Comparative example 9

The preparation method of the electrolyte provided by the implementation comprises the following steps: a mixed solvent of EC and DEC with a volume ratio of 1:1 was prepared, 979.52mg of NaClO4 was added, and 3% of FEC by total mass of the electrolyte was added.

FIG. 1 shows ion conductivities of the electrolytes of example 1 and comparative examples 1, 2, and 3 at-10 ℃, 0 ℃, 10 ℃, 20 ℃, 30 ℃, 40 ℃, and 60 ℃; FIG. 2 shows the temperature change capacity of the electrolyte in the range of 30-60 ℃. Experimental results indicate that Experimental example 1 exhibits the highest ionic conductivity and higher capacity at each temperature, and that example 1 still retains 64% of its height Wen Rongliang in an environment of-30 ℃.

FIG. 3 is an electrochemical window of the electrolyte of example 1 and comparative example 1 at a high temperature of 60 ℃; FIG. 4 is the cycle performance at 60℃of Na||NVP batteries assembled from the electrolytes of example 1 and comparative examples 1-4, 6-9; FIG. 5 is Na||PB showing electrolyte assembly of example 1 and the cycling performance of na||nmo cells at 60 ℃. As can be seen from fig. 3 to 5, under the high temperature test condition that the cut-off voltage is 4.2V and 60 ℃, the comprehensive performance of the electrolyte prepared in the embodiment of the invention is obviously superior to that of the comparative example, and the electrolyte shows excellent performance in three positive electrode materials NVP, PB, NMO, which proves that the electrolyte of the invention maintains good compatibility and universality with different positive and negative electrodes under high temperature and high pressure, and is beneficial to better promoting the market demand of batteries under extreme test conditions.

The above embodiments are only limited to further explanation and description of the technical solutions of the present invention, and are not intended to limit the scope of the present invention. Any equivalent replacement or partial modification is considered to be within the scope of the present invention under the spirit and principle of the present invention.

Claims (9)

1. A sodium ion battery wide-temperature high-pressure electrolyte is characterized by comprising sodium salt, carbonic ester/ether organic solvent and additive.

2. The high-voltage electrolyte with a wide temperature range according to claim 1, wherein the high-voltage electrolyte with a wide temperature range comprises, in mass percent: 10-50% of sodium salt, 1-5% of additive and the balance of mixed solvent.

3. The high-pressure sodium ion battery electrolyte with broad temperature range of claim 2, wherein the sodium salt is any one or a combination of at least two of sodium perchlorate (NaClO 4), sodium hexafluorophosphate (NaPF 6), sodium bis (fluorosulfonyl) imide (NaFSI), sodium bis (trifluoromethanesulfonyl) imide (naffsi), sodium trifluoromethanesulfonate (NaOTf).

4. A high pressure sodium ion battery electrolyte with broad temperature range according to claim 3, wherein the sodium salt is sodium perchlorate (NaClO 4), preferably the concentration of the sodium salt is 0.6-2.0 mol/L, further preferably 0.8-1.5 mol/L.

5. The high-pressure electrolytic solution having a wide temperature range according to claim 2, wherein the mixed solvent is two or more solvents of Propylene Carbonate (PC), ethylene Carbonate (EC), dimethyl carbonate (DMC), diethyl carbonate (DEC), ethylmethyl carbonate (EMC), ethylene glycol dimethyl ether (DME), diethylene glycol dimethyl ether (G2), tetraethylene glycol dimethyl ether (G4), and Tetrahydrofuran (THF).

6. The high-pressure electrolyte having a wide temperature range according to claim 5, wherein the mixed solvent is one or more of Ethylene Carbonate (EC), ethylene glycol dimethyl ether (DME), fluoroethylene carbonate (FEC), tris (trimethylsilane) phosphite (TMSP), tripropylphosphate (TPP), triphenylphosphine oxide (TPPO), tris (pentafluorophenyl) phosphine (TPFPP), triisopropylborate (TIB), trimethyl borate (TMB), tris (pentafluorophenyl) boron (TPFPB), 4-aminobenzoic acid (4-ABA), benzotris (BzTz), and terthiophene (3 THP).

7. The method for preparing a wide temperature range type high-voltage electrolyte according to any one of claims 1 to 6, which is characterized by comprising the following steps:

1) Fully mixing and stirring carbonate and ether organic solvents under the condition of argon atmosphere to obtain a prepurified solution;

2) Dissolving sodium salt into the prepurified solution obtained in the step 2);

3) Adding a molecular sieve into the prepurified solution obtained in the step 2), standing for 8 hours, and finally removing the molecular sieve to obtain a purified solution;

4) And (3) dissolving an electrolyte additive into the purified solution obtained in the step (3), and uniformly mixing to obtain the wide-temperature high-pressure electrolyte.

8. The method for producing a high-temperature and high-pressure electrolyte according to claim 7, wherein the molecular sieve isOr->Molecular sieves.

9. The use of the high-temperature and high-pressure electrolyte as claimed in claim 1 in a high-pressure sodium ion battery.