Preparation method and application of diluent-adjusted local high-concentration electrolyte

Abstract

The invention discloses a preparation method and application of a diluent-adjusted local high-concentration electrolyte, and relates to a preparation method and application of an electrolyte. The invention aims to solve the problems of high cost and high overpotential and poor cycle performance of the Li-CO2 battery caused by high viscosity, poor electrode wettability and reduced oxygen solubility of a high-concentration salt electrolyte used in the prior art and use of a large amount of expensive Li salt in the Li-CO2 battery. The method comprises the following steps: dissolving lithium bis (trifluoromethanesulfonimide) in dimethyl sulfoxide, diluting by using tetraethylene glycol dimethyl ether, stirring for a period of time to obtain a diluent for adjusting local high-concentration electrolyte, and preferentially combining DMSO with Li < + > to form a strong solvation structure through excellent solvation ability; the dilution effect of TEGDME optimizes the stability of the electrolyte without destroying the structure, and finally forms the local high-concentration electrolyte with high ionic conductivity and good electrode interface stability.

Description

Technical Field

[0001] The invention relates to a preparation method and application of an electrolyte. Background Art

[0002] With the development of the world economy, environmental problems and energy crises have further intensified, causing people's concerns. In order to achieve sustainable development, scientists are committed to finding new energy sources that are environmentally friendly and efficient, and lithium-carbon dioxide batteries are one of them. Lithium-carbon dioxide batteries discharge by reducing carbon dioxide, which has the dual effects of alleviating the greenhouse effect and the energy crisis. Due to its energy density comparable to gasoline, it is considered to have great potential to become a gasoline substitute. However, in practice, it faces shortcomings such as severe polarization and insufficient cycle stability, which limit its large-scale use.

[0003] Li-CO 2 As the core component of the battery system, the performance defects of the battery electrolyte have become the key bottleneck restricting the development of this technology. The electrolyte has poor compatibility with the highly active lithium metal anode, which can easily cause lithium dendrite growth, interface side reactions (such as the reaction between the electrolyte and lithium metal to form a solid electrolyte interface film SEI, but its instability will lead to continuous consumption), and gas byproducts (such as CO, CH 4 These side reactions not only reduce the Coulomb efficiency, but also bring serious safety hazards (such as dendrites piercing the diaphragm and causing short circuit). Secondly, the electrolyte is at high potential (such as CO 2 The chemical stability under the high voltage required for reduction / precipitation reaction is insufficient, and irreversible decomposition is prone to occur, which not only generates by-products (such as Li 2 CO 3 , C, etc.) will block the electrode pores and accelerate the consumption of the electrolyte itself, significantly shortening the battery cycle life. From the perspective of material cost, some electrolytes (such as ionic liquids and fluorinated solvents) that are attempted to improve performance are expensive and have complex synthesis processes, making it difficult to meet the needs of large-scale commercialization. These defects are interrelated and together lead to the actual energy density of the battery being far lower than the theoretical value, poor cycle stability (usually less than 100 cycles) and safety risks. It is urgent to achieve breakthroughs through strategies such as developing new electrolyte systems (such as solid electrolytes, ultra-concentrated electrolytes), optimizing solvent / lithium salt formulas, or introducing functional additives. Summary of the invention

[0004] The purpose of the present invention is to solve the problem of Li-CO 2 In batteries, the high-concentration salt electrolyte used in the prior art has the disadvantages of high viscosity, poor electrode wettability, decreased oxygen solubility, and the use of a large amount of expensive Li salt, resulting in high costs and Li-CO 2To solve the problems of high overpotential and poor cycling performance of batteries, a preparation method and application of a diluent for regulating a locally high-concentration electrolyte are provided.

[0005] A preparation method of a diluent for regulating a locally high-concentration electrolyte is specifically completed according to the following steps:

[0006] Dissolve lithium bis(trifluoromethanesulfonyl)imide in dimethyl sulfoxide, and then dilute it with tetraethylene glycol dimethyl ether and stir for a period of time to obtain a diluent for regulating a locally high-concentration electrolyte.

[0007] The principle of the present invention:

[0008] To solve the technical problems existing in the prior art, by introducing a co-solvent dimethyl sulfoxide (DMSO) into LiTFSI and using an ether solvent tetraethylene glycol dimethyl ether (TEGDME) as a diluent, a locally high-concentration electrolyte system is successfully constructed. In this strategy, DMSO preferentially combines with Li through its excellent solvation ability + to form a strong solvation structure. At the same time, the dilution effect of TEGDME optimizes the stability of the electrolyte without destroying this structure, and finally forms a locally high-concentration electrolyte with both high ionic conductivity and good electrode interface stability.

[0009] Combining solvents with high donor numbers and low donor numbers with Li salts to produce a new locally strong solvation effect electrolyte not only has fewer free solvent molecules, reducing side reactions with Li metal, but also adding a co-solvent can effectively improve the disadvantages of high viscosity of high-concentration electrolytes, poor electrode wettability, decreased oxygen solubility, and the use of a large amount of expensive Li salts. Solvents with high donor numbers (DN) tend to strongly solvate Li + to trigger the solvation mechanism, which ultimately improves battery performance by increasing the discharge capacity and reducing the overpotential. On the contrary, solvents with low DN lead to a surface mechanism, which can hinder the discharge reaction and reduce the discharge capacity. Solvents with high DN preferentially combine with Li + to form a strong solvation structure, and the addition of solvents with low DN does not destroy this solvation structure. The optimized electrolyte provides high capacity through the combination of the solvation ability of high-DN solvents and the stability of low-DN solvents, inhibits side reactions in the battery, and helps to form a stable solid electrolyte interface film on the surface of the lithium anode for Li-CO 2 batteries, and can obtain a lower overpotential and good cycling performance.

[0010] The advantages of the present invention:

[0011] I. The present invention tested the electrochemical performance of Li-CO₂ batteries using four kinds of locally high-concentration electrolytes, namely LiTFSI:DMSO:TEGDME = 1:3:3, LiTFSI:DMSO = 1:10, LiTFSI:DMSO = 1:3, LiTFSI:DMSO:TEGDME = 1:4:4, and a commercial lithium-air electrolyte (LiTFSI:TEGDME = 1:10). 2 The constant current charge-discharge test, rate performance test, and energy efficiency test showed that the Li-CO₂ battery (LSSE) using LiTFSI:DMSO:TEGDME = 1:3:3 2 had the best electron transfer ability, the optimal CO₂ 2 reduction reaction (CO₂RR) kinetics, a smaller overpotential, and the highest energy efficiency. Compared with other electrolytes, there were fewer free DMSO molecules in LSSE, and the DMSO molecules were surrounded by TEGDME molecules in the salt-solvent cluster, effectively inhibiting the decomposition of DMSO. In addition, TEGDME contributed to the formation of a stable solid electrolyte interface (SEI) on the lithium anode surface, thus significantly improving the cycle life of the Li-CO₂ 2 battery; 2

[0012] II. The present invention provides a preparation method for adjusting locally high-concentration electrolytes with a diluent and its application to lithium-carbon dioxide batteries. The preparation method of the present invention is simple and easy to implement, and is suitable for large-scale popularization and application. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 Raman spectrum of the LSSE electrolyte prepared in Example 1;

[0014] Figure 2 Raman spectrum of the Dilute electrolyte prepared in Comparative Example 1;

[0015] Figure 3 Raman spectrum of the SSE electrolyte prepared in Comparative Example 2;

[0016] Figure 4 Structural schematic diagram of LiTFSI;

[0017] Figure 5 Structural schematic diagram of DMSO;

[0018] Figure 6 Structural schematic diagram of TEGDME;

[0019] Figure 7 ​Li-CO batteries assembled with the LSSE electrolyte prepared in Example 1, the Dilute electrolyte prepared in Comparative Example 1, and the commercial lithium-air electrolyte (LiTFSI:TEGDME = 1:10) in Comparative Example 4 2 Initial charge-discharge curves of the battery;

[0020] Figure 8 Li-CO batteries assembled with the LSSE electrolyte prepared in Example 1 and the electrolyte prepared in Comparative Example 3 (LiTFSI:DMSO:TEGDME = 1:4:4) 2 Initial charge-discharge curves of the battery;

[0021] Figure 9 Li-CO batteries assembled with the LSSE electrolyte prepared in Example 1 2 Galvanostatic charge-discharge curves of the battery;

[0022] Figure 10 Li-CO batteries assembled with the Dilute electrolyte prepared in Comparative Example 1 2 Galvanostatic charge-discharge curves of the battery;

[0023] Figure 11 Li-CO batteries assembled with the SSE electrolyte prepared in Comparative Example 2 2 Galvanostatic charge-discharge curves of the battery;

[0024] Figure 12 Li-CO batteries assembled with the LSSE electrolyte prepared in Example 1, the Dilute electrolyte prepared in Comparative Example 1, and the SSE electrolyte prepared in Comparative Example 2, respectively 2 Comparison chart of the rate performance of the battery;

[0025] Figure 13 Li-CO batteries assembled with the LSSE electrolyte prepared in Example 1 2 Rate curves of the battery;

[0026] Figure 14 Li-CO batteries assembled with the Dilute electrolyte prepared in Comparative Example 1 2 Rate curves of the battery;

[0027] Figure 15 Li-CO batteries assembled with the SSE electrolyte prepared in Comparative Example 2 2 Rate curves of the battery;

[0028] Figure 16 Li-CO batteries assembled with the LSSE electrolyte prepared in Example 1, the Dilute electrolyte prepared in Comparative Example 1, and the SSE electrolyte prepared in Comparative Example 2, respectively 2 Energy efficiency curves of the battery. Specific Embodiments

[0029] Specific Embodiment 1: A method for preparing a diluent - adjusted locally high - concentration electrolyte in this embodiment is specifically completed according to the following steps:

[0030] Dissolve lithium bis(trifluoromethanesulfonyl)imide in dimethyl sulfoxide, and then dilute it with tetraethylene glycol dimethyl ether and stir for a period of time to obtain the diluent - adjusted locally high - concentration electrolyte.

[0031] Specific Embodiment 2: The difference between this embodiment and Specific Embodiment 1 is that the molar ratio of lithium bis(trifluoromethanesulfonyl)imide, dimethyl sulfoxide, and tetraethylene glycol dimethyl ether is (0.5 - 1.5):(2 - 4):(2 - 4). Other steps are the same as those in Specific Embodiment 1.

[0032] Specific Embodiment 3: The difference between this embodiment and either Specific Embodiment 1 or 2 is that the molar ratio of lithium bis(trifluoromethanesulfonyl)imide, dimethyl sulfoxide, and tetraethylene glycol dimethyl ether is (0.5 - 1.5):(2 - 3):(2 - 3). Other steps are the same as those in Specific Embodiment 1 or 2.

[0033] Specific Embodiment 4: The difference between this embodiment and any one of Specific Embodiments 1 to 3 is that the molar ratio of lithium bis(trifluoromethanesulfonyl)imide, dimethyl sulfoxide, and tetraethylene glycol dimethyl ether is (0.5 - 1.5):(3 - 4):(3 - 4). Other steps are the same as those in Specific Embodiments 1 to 3.

[0034] Specific Embodiment 5: The difference between this embodiment and any one of Specific Embodiments 1 to 4 is that the molar ratio of lithium bis(trifluoromethanesulfonyl)imide, dimethyl sulfoxide, and tetraethylene glycol dimethyl ether is (0.5 - 1.5):3:3. Other steps are the same as those in Specific Embodiments 1 to 4.

[0035] Specific Embodiment 6: The difference between this embodiment and any one of Specific Embodiments 1 to 5 is that the molar ratio of lithium bis(trifluoromethanesulfonyl)imide, dimethyl sulfoxide, and tetraethylene glycol dimethyl ether is (0.5 - 1.5):4:4.

[0036] Other steps are the same as those in Specific Embodiments 1 to 5.

[0037] Specific Embodiment 7: The difference between this embodiment and any one of Specific Embodiments 1 to 6 is that the molar ratio of lithium bis(trifluoromethanesulfonyl)imide, dimethyl sulfoxide, and tetraethylene glycol dimethyl ether is 1:3:3. Other steps are the same as those in Specific Embodiments 1 to 6.

[0038] Embodiment 8: The difference between this embodiment and any one of Embodiments 1 to 7 is that the molar ratio of lithium bis(trifluoromethanesulfonyl)imide, dimethyl sulfoxide and tetraethylene glycol dimethyl ether is 1:4:4. Other steps are the same as those in Embodiments 1 to 7.

[0039] Embodiment 9: The difference between this embodiment and any one of Embodiments 1 to 8 is that the stirring speed is 500 r / min and the stirring time is 1 h. Other steps are the same as those in Embodiments 1 to 8.

[0040] Embodiment 10: This embodiment is a method for preparing a diluent-adjusted locally high-concentration electrolyte for use as an electrolyte in a lithium-carbon dioxide battery.

[0041] The following examples are used to verify the beneficial effects of the present invention:

[0042] Example 1: A method for preparing a diluent-adjusted locally high-concentration electrolyte (LSSE) is specifically completed according to the following steps:

[0043] Dissolve lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) in dimethyl sulfoxide (DMSO) to form a homogeneous solution, and then dilute it with tetraethylene glycol dimethyl ether (TEGDME). Stir at a stirring speed of 500 r / min for 1 h to obtain a diluent-adjusted locally high-concentration electrolyte (LSSE).

[0044] The molar ratio of lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), dimethyl sulfoxide (DMSO) and tetraethylene glycol dimethyl ether (TEGDME) is 1:3:3.

[0045] Control Example 1: A method for preparing an electrolyte (Dilute) is specifically completed according to the following steps:

[0046] Add lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) to dimethyl sulfoxide (DMSO) to form a homogeneous solution, and stir at a stirring speed of 500 r / min for 1 h to obtain the electrolyte (Dilute);

[0047] The molar ratio of lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) and dimethyl sulfoxide (DMSO) is 1:10.

[0048] Control Example 2: A method for preparing an electrolyte (SSE) is specifically completed according to the following steps:

[0049] Add lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) to dimethyl sulfoxide (DMSO) to form a homogeneous solution, and stir at a stirring speed of 500 r / min for 1 h to obtain the electrolyte (SSE);

[0050] The molar ratio of the lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) and dimethyl sulfoxide (DMSO) is 1:3.

[0051] Comparative Example 3: The preparation method of the electrolyte (LiTFSI:DMSO:TEGDME = 1:4:4) is specifically completed according to the following steps: First, dissolve lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) in dimethyl sulfoxide (DMSO) to form a homogeneous solution, and then gradually add tetraethylene glycol dimethyl ether (TEGDME) and stir for 1 h at a stirring speed of 500 r / min for dilution and mixing to obtain the electrolyte (LiTFSI:DMSO:TEGDME = 1:4:4);

[0052] The molar ratio of the lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), dimethyl sulfoxide (DMSO) and tetraethylene glycol dimethyl ether (TEGDME) is 1:4:4.

[0053] Comparative Example 4: The commercial lithium-air electrolyte (LiTFSI:TEGDME = 1:10) is formed by mixing lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) and tetraethylene glycol dimethyl ether (TEGDME) according to a molar ratio of 1:10.

[0054] When assembling the Li-CO 2 O and O 2 The content of both needs to be strictly controlled within <0.1 ppm) in the glove box, all tools and materials must be ensured to be fully dried before assembling the battery. Preparation of the IrO 2 / CNT electrode sheet: Mix 10 mg of commercial iridium oxide (IrO 2 ) ( 2 ), 2 mg of carbon nanotubes (CNT), 50 μL of Nafion solution and 1 mL of isopropanol, and continuously stir on a magnetic stirrer at a speed of 500 r / min for 8 hours to form a uniform slurry; then use a micropipette to accurately coat the slurry onto the pre-cut carbon paper, and control the coating amount so that the loading of each positive active material (IrO 2 and CNT) reaches 0.25 mg / cm 2 . The coated carbon paper needs to be vacuum dried at 60 °C for 12 hours. When assembling the battery, sequentially place a waterproof and breathable membrane, the prepared IrO 2 / CNT electrode sheet (diameter 12 mm), a glass fiber separator impregnated with the LSSE electrolyte (70 μL) prepared in Example 1, a lithium metal negative electrode (diameter 14 mm) treated by scraping, a stainless steel gasket, and a spring piece in the lower shell of the CR2032 lithium-air button cell, and then seal the battery. The assembled Li-CO 2The battery was transferred to a threaded sealed bottle, the bottle mouth was strictly sealed with sealing glue, and then high-purity CO was continuously introduced into the bottle at a constant flow rate. 2 The gas is heated for 3 hours to make the battery system reach CO 2 Saturated state, and finally stand at 25℃ constant temperature for 24 hours to ensure CO 2 It fully diffuses into the electrolyte and the porous electrode to complete the gas infiltration and pre-activation process of the reaction interface.

[0055] According to the same method as above, the LSSE electrolyte prepared in Example 1 was replaced by: the Dilute electrolyte prepared in Control Example 1, the SSE electrolyte prepared in Control Example 2, the electrolyte prepared in Control Example 3 (LiTFSI: DMSO: TEGDME = 1: 4: 4) and the commercial lithium-air electrolyte (LiTFSI: TEGDME = 1: 10) in Control Example 4, and the above electrolytes were used to assemble Li-CO 2 The battery was then electrochemically tested;

[0056] Figure 1 The Raman spectrum of the LSSE electrolyte prepared in Example 1;

[0057] Figure 2 The Raman spectrum of the Dilute electrolyte prepared in Control Example 1;

[0058] Figure 3 Raman spectrum of the SSE electrolyte prepared in Comparative Example 2;

[0059] In all samples, DMSO and LiTFSI characteristic peaks appeared. -1 、335cm -1 、382cm -1 The outer curvature of the CSC corresponding to DMSO (δ op (CSC)), CSO outer bending (δ op (CSO)), CSO in-plane swing (ρ ip (CSO)) mode. 672cm -1 and 703cm -1 Corresponding to the symmetric stretching of CSC of DMSO (v s (CSC)) and CSC asymmetric stretching (v a (CSC)). At 1048cm -1 The peaks observed at 954 cm belong to the S=O stretching modes (v(SO)) of different forms of DMSO. -1 Corresponding to CH of DMSO 3 Rocking mode (ρ(CH 3 )). 279cm-1 , 533 cm -1 , 562 cm -1 correspond to the CF of LiTFSI 3 rocking mode (TFSI - ρ(CF 3 ))), SO 2 symmetric bending (TFSI - δ s (SO 2 ))), CF 3 asymmetric bending (TFSI - δ a (CF 3 ))). 739 cm -1 corresponds to the SNS symmetric stretching of LiTFSI (TFSI - v s (SNS)), and as the concentration of LiTFSI decreases, this peak gradually weakens. 1139 cm -1 , 1242 cm -1 correspond to the SO 2 symmetric stretching in LiTFSI (TFSI - v s (SO 2 )) and CF 3 symmetric stretching (TFSI - v s (CF 3 ))).

[0060] Figure 1 In -1 , 803 cm -1 , 851 cm 2 correspond to the rocking vibration of TEGDME CH 2 )) and the C-O-C stretching vibration mode (v(C-O-C)), respectively. As the salt concentration increases, the intensity of the C-O-C stretching vibration of free TEGDME (851 cm -1 ) weakens, indicating that the solvation ratio of lithium ions to TEGDME molecules increases as the salt concentration in the TEGDME-based electrolyte increases.

[0061] From the perspective of CO 2 ER kinetics, at a cut-off capacity of 0.1 mAh, the first-cycle galvanostatic charge-discharge curves of the batteries assembled with LSSE, Dilute, and commercial lithium-air electrolytes (LiTFSI:TEGDME = 1:10) were tested, as shown in Figure 7 ;

[0062] Figure 7Li-CO batteries assembled with the LSSE electrolyte prepared in Example 1, the Dilute electrolyte prepared in Comparative Example 1, and the commercial lithium-air electrolyte (LiTFSI:TEGDME = 1:10) in Comparative Example 4 2 First-cycle charge-discharge curves of the batteries;

[0063] From Figure 7 it can be seen that for the Li-CO batteries with LSSE as the electrolyte 2 showed the lowest overpotential of 1.468 V, and the charging plateau was 4.2 V. The results indicate that the insulating discharge products in the LSSE battery with a combination of DMSO and TEGDME as the electrolyte decomposed most effectively, with the lowest CO 2 ER overpotential and the fastest CO 2 ER kinetics. Therefore, the electrolyte is a mixed solution composed of DMSO and TEGDME, showing the most excellent performance, which is mainly attributed to the fact that the two solvents can form a locally concentrated electrolyte and play a synergistic role in the system: DMSO preferentially forms a strong solvation structure with Li + while TEGDME molecules wrap around the periphery of the salt-solvent cluster. This unique molecular arrangement effectively inhibits the decomposition of DMSO; at the same time, TEGDME also promotes the formation of a stable solid electrolyte interface (SEI) on the lithium anode surface, thereby further improving the overall performance of the solution.

[0064] After determining that the electrolyte is composed of DMSO and TEGDME, in order to optimize the electrolyte performance, the ratio of the two solvents was further adjusted. From the perspective of CO 2 ER kinetics, at a cut-off capacity of 0.1 mAh, the first-cycle constant-current charge-discharge curves of LSSE and LiTFSI:DMSO:TEGDME = 1:4:4 batteries were tested, and the results are as Figure 8 shown;

[0065] Figure 8 First-cycle charge-discharge curves of the Li-CO batteries assembled with the LSSE electrolyte prepared in Example 1 and the electrolyte (LiTFSI:DMSO:TEGDME = 1:4:4) prepared in Comparative Example 3; 2 First-cycle charge-discharge curves of the batteries;

[0066] It was experimentally found that the first-cycle overpotential of the LSSE battery was less than that of the LiTFSI:DMSO:TEGDME = 1:4:4 battery. Therefore, the optimal ratio of the electrolyte was determined to be LiTFSI:DMSO:TEGDME = 1:3:3.

[0067] To further verify the performance advantages of the locally concentrated electrolyte (LSSE), we conducted comparative experiments with a high-concentration electrolyte (SSE) and a dilute electrolyte (Dilute). First, at 200 mAg-1 Under a constant current density, charge-discharge tests were carried out on Li-CO batteries using LSSE, Dilute, and SSE electrolytes respectively (as shown in 2 ). Figures 9 - 11 Shown).

[0068] Figure 9 Figure [X] is the constant current charge-discharge curve of the Li-CO battery assembled with the LSSE electrolyte prepared in Example 1; 2

[0069] Figure 10 Figure [X] is the constant current charge-discharge curve of the Li-CO battery assembled with the Dilute electrolyte prepared in Comparative Example 1; 2

[0070] Figure 11 Figure [X] is the constant current charge-discharge curve of the Li-CO battery assembled with the SSE electrolyte prepared in Comparative Example 2; 2

[0071] The experimental results show that the battery using the LSSE electrolyte of Example 1 exhibits the best cycle stability and can still maintain an overpotential of about 1.5 V after 90 cycles. This result fully confirms that the LSSE electrolyte is superior to the SSE and Dilute electrolytes in terms of performance.

[0072] After completing the charge-discharge cycle test of the battery, in order to explore the kinetic characteristics and energy output ability of the battery at different current densities, a rate performance test was further carried out. Figure 12 Figure [X] is a comparison chart of the cut-off voltages of LSSE, Dilute, and SSE electrolytes at different current densities, and the corresponding charge-discharge curves are as shown in Figures 13 - 15 .

[0073] Figure 12 Figure [X] is a comparison chart of the rate performance of Li-CO batteries assembled with the LSSE electrolyte prepared in Example 1, the Dilute electrolyte prepared in Comparative Example 1, and the SSE electrolyte prepared in Comparative Example 2; 2

[0074] Figure 13 Figure [X] is the rate curve of the Li-CO battery assembled with the LSSE electrolyte prepared in Example 1; 2

[0075] Figure 14 Figure [X] is the rate curve of the Li-CO battery assembled with the Dilute electrolyte prepared in Comparative Example 1; 2

[0076] Figure 15 Figure [X] is the rate curve of the Li-CO battery assembled with the SSE electrolyte prepared in Comparative Example 2; 2 ​​​​​​Rate curve of the battery;

[0077] The results show that: at the current densities of 50 mA g -1 and 100 mA g -1 , the overpotential of LSSE is only slightly greater than that of the Dilute electrolyte. Starting from the current density of 200 mA g -1 , LSSE exhibits the lowest overpotential of about 1.5 V. It shows that the ratio of LiTFSI:DMSO:TEGDME = 1:3:3 can maximize the promotion of CO 2 RR and CO 2 ER reaction kinetics.

[0078] Compare the energy efficiencies of LSSE, Dilute, and SSE batteries, as Figure 16 shown;

[0079] Figure 16 are the energy efficiency curves of Li-CO 2 batteries assembled using the LSSE electrolyte prepared in Example 1, the Dilute electrolyte prepared in Comparative Example 1, and the SSE electrolyte prepared in Comparative Example 2, respectively;

[0080] The results show that: the LSSE battery has an energy efficiency of 70% after 70 test cycles, which is significantly better than the energy efficiencies of the other two electrolyte batteries at the same number of cycles. The results further prove that the optimal ratio of the electrolyte is LiTFSI:DMSO:TEGDME = 1:3:3.

[0081] In summary, it can be seen that the solvents must be DMSO and TEGDME. Using any one of them alone has poor effects; the best molar ratio of LiTFSI:DMSO:TEGDME is 1:3:3. Any ratio deviating from this ratio is a comparative example and has unsatisfactory effects. The comprehensive performance of LSSE is the best, verifying the scientificity and practicality of the above invention points.

Claims

1. A method for preparing a local high-concentration electrolyte adjusted by a diluent, characterized in that The preparation method is specifically completed according to the following steps: After dissolving lithium bis(trifluoromethanesulfonyl)imide in dimethyl sulfoxide, diluting with tetraethylene glycol dimethyl ether and stirring for a period of time, a local high-concentration electrolyte adjusted by a diluent is obtained.

2. The method for preparing a diluent-adjusted local high-concentration electrolyte according to claim 1, characterized in that The molar ratio of the lithium bis(trifluoromethanesulfonyl)imide, dimethyl sulfoxide and tetraethylene glycol dimethyl ether is (0.5-1.5):(2-4):(2-4).

3. The method for preparing a diluent-adjusted local high-concentration electrolyte according to claim 2, characterized in that The molar ratio of the lithium bis(trifluoromethanesulfonyl)imide, dimethyl sulfoxide and tetraethylene glycol dimethyl ether is (0.5-1.5):(2-3):(2-3).

4. The method for preparing a diluent-adjusted local high-concentration electrolyte according to claim 2, characterized in that The molar ratio of the lithium bis(trifluoromethanesulfonyl)imide, dimethyl sulfoxide and tetraethylene glycol dimethyl ether is (0.5-1.5):(3-4):(3-4).

5. The method for preparing a diluent-adjusted local high-concentration electrolyte according to claim 2, characterized in that The molar ratio of the lithium bis(trifluoromethanesulfonyl)imide, dimethyl sulfoxide and tetraethylene glycol dimethyl ether is (0.5-1.5):3:

3.

6. The method for preparing a diluent-adjusted local high-concentration electrolyte according to claim 2, characterized in that The molar ratio of the lithium bis(trifluoromethanesulfonyl)imide, dimethyl sulfoxide and tetraethylene glycol dimethyl ether is (0.5-1.5):4:

4.

7. The method for preparing a local high-concentration electrolyte adjusted by a diluent according to claim 2, characterized in that The molar ratio of lithium bis(trifluoromethanesulfonyl)imide, dimethyl sulfoxide and tetraethylene glycol dimethyl ether is 1:3:

3.

8. The method for preparing a diluent-adjusted local high-concentration electrolyte according to claim 2, characterized in that The molar ratio of lithium bis(trifluoromethanesulfonyl)imide, dimethyl sulfoxide and tetraethylene glycol dimethyl ether is 1:4:

4.

9. The method for preparing a local high-concentration electrolyte adjusted by a diluent according to claim 2, characterized in that The stirring speed is 500r / min and the stirring time is 1h.

10. Use of the diluent prepared by the preparation method according to claim 1 to adjust a local high-concentration electrolyte, characterized in that The diluent adjusts the local high-concentration electrolyte to be used as the electrolyte in the lithium-carbon dioxide battery.

Images