Electrolyte for zinc ion battery with ultra-wide temperature range of minus 60 degrees to 100 degrees and preparation method thereof

Abstract

The application discloses a kind of electrolyte for zinc ion battery in 60 degrees below zero~100 degrees ultra-wide temperature range and preparation method thereof, the electrolyte is cosolvent electrolyte, the cosolvent electrolyte is formed by adding zinc salt into the mixed solvent of water and glycol ether, and the zinc salt is at least one of zinc triflate, zinc chloride, zinc bis (trifluoromethyl sulfonate) imine, zinc perchlorate or zinc tetrafluoroborate.The cosolvent electrolyte of the application is not flammable at high temperature and can promote the battery to have long cycle stability at high temperature, is resistant to freezing at ultra-low temperature-60°C and the battery has high discharge capacity and rate performance;The cosolvent electrolyte of the application has the stable performance of ultra-wide temperature range of-60°C~100°C, so the zinc ion battery based on cosolvent electrolyte has good electrochemical performance in the above ultra-wide temperature range.

Description

Technical Field

[0001] This invention relates to an electrolyte for zinc-ion batteries with an ultra-wide temperature range of -60°C to 100°C, and also to a method for preparing the above-mentioned electrolyte for zinc-ion batteries. Background Technology

[0002] As the core energy storage and supply carrier in the new energy era, the operating temperature adaptability of batteries directly determines the breadth of application scenarios and the reliability and safety of operation. Traditional lithium-ion batteries using organic electrolytes (carbonate solvents have problems with low ignition points and high freezing points) are greatly affected by temperature. At high temperatures above 25 ℃, they are not only prone to thermal runaway leading to fires and explosions, but also experience a rapid decline in battery life. At low temperatures below -20 ℃, the ionic conductivity drops sharply, resulting in a significant decrease in charge and discharge efficiency, which seriously limits the application of lithium-ion batteries in extreme environments. Summary of the Invention

[0003] Objective of this invention: The objective of this invention is to provide an electrolyte for zinc-ion batteries with an ultra-wide temperature range. Because it is both non-flammable at high temperatures and resistant to freezing at low temperatures, it enables zinc-ion batteries to maintain good electrochemical performance in a wide temperature range of -60 ℃ to 100 ℃. Another objective of this invention is to provide a method for preparing the above-mentioned electrolyte for zinc-ion batteries.

[0004] Technical solution: The electrolyte for zinc-ion batteries described in this invention is a wide-temperature-range co-solvent electrolyte. The co-solvent electrolyte is formed by adding zinc salt to a mixed solvent of water and ethylene glycol ethers. It has the characteristics of high temperature stability, non-flammability, and low temperature resistance. The zinc salt is at least one of zinc trifluoromethanesulfonate, zinc chloride, zinc bis(trifluoromethanesulfonyl)imide, zinc perchlorate, or zinc tetrafluoroborate.

[0005] The solvent of the co-solvent electrolyte is a mixture of ethylene glycol ether solvent and water, and the electrolyte is a zinc salt.

[0006] The ethylene glycol ether solvent is at least one selected from ethylene glycol methyl ether, ethylene glycol ethyl ether, ethylene glycol propyl ether, ethylene glycol butyl ether, and ethylene glycol hexyl ether. The molar concentration of the zinc salt in the electrolyte is 1-1.5 mol / kg. The mass ratio of water to the ethylene glycol ether solvent is 1:1-2, and more preferably, the volume ratio is 1:1-1.5.

[0007] The purity of the zinc trifluoromethanesulfonate, zinc chloride, bis(trifluoromethanesulfonyl)imide zinc, zinc perchlorate, or zinc tetrafluoroborate is ≥99.8%; the purity of the ethylene glycol ether solvent is ≥99.8%; and the water is deionized water.

[0008] The preparation method of the electrolyte for zinc-ion batteries is as follows: at room temperature, water and ethylene glycol ether solvent are mixed in a mass ratio of 1:1~2, and then zinc salt is completely dissolved in the mixed solvent of water and ethylene glycol ether solvent to prepare a co-solvent electrolyte with an electrolyte concentration of 1~1.5 mol / kg.

[0009] The co-solvent electrolyte of this invention can greatly reduce hydrogen evolution corrosion of metal anodes and oxygen evolution of cathodes at ultra-high temperatures above 25 ℃ or even 100 ℃, and improve its rate performance at ultra-low temperatures below 25 ℃ or even -60 ℃. The strong hydrogen bonding between the co-solvent and water can inhibit the hydrogen evolution and oxygen evolution reactions of water decomposition. The mixing of zinc salt with co-solvent and water breaks the hydrogen bond network of water and prevents water from freezing. At the same time, the strong ionic dipole interaction between the co-solvent and cations helps the transport kinetics of zinc ions.

[0010] Beneficial effects: Compared with the prior art, the present invention has the following significant advantages: The co-solvent electrolyte prepared by the present invention not only has high stability (non-flammable) at high temperature, but also remains liquid at extremely low temperature, so that the zinc-ion battery still has good electrochemical performance in a wide temperature range of -60 ℃ to 100 ℃ (good cycle stability at high temperature, and high rate performance and specific capacity at low temperature). Attached Figure Description

[0011] Figure 1 This is a photograph of the glass fiber diaphragm of Example 1 after it has been ignited following being impregnated with the co-solvent electrolyte.

[0012] Figure 2 The image shows the actual product of zinc perchlorate pure water electrolyte of Comparative Example 1 after being placed at -60 °C for 24 h.

[0013] Figure 3 This is a photograph of the co-solvent electrolyte of Example 1 after being left at -60 °C for 24 hours.

[0014] Figure 4 The rate performance of the Zn / / PANI battery based on the co-solvent electrolyte of Example 1 at a low temperature of -40 °C;

[0015] Figure 5 The cycling performance of the Zn / / PANI battery based on the co-solvent electrolyte of Example 1 at an ultra-low temperature of -60 °C;

[0016] Figure 6 The cycling performance of the Zn / / PANI coin cell based on the co-solvent electrolyte of Example 1 at a high temperature of 70 °C;

[0017] Figure 7The cycling performance of the Zn / / PANI battery based on the co-solvent electrolyte of Example 1 at an ultra-high temperature of 100 °C;

[0018] Figure 8 Linear sweep voltammetric curves are obtained based on the co-solvent electrolyte of Example 1 and the pure water electrolyte of Comparative Example 1. Detailed Implementation

[0019] Example 1

[0020] The present invention discloses a method for preparing an electrolyte for zinc-ion batteries, specifically as follows: At room temperature (around 25°C), 400 g of water and 600 g of ethylene glycol methyl ether are mixed at a mass ratio of 1:1.5. Then, 1 mol of anhydrous zinc perchlorate is completely dissolved in the mixed solvent of water and ethylene glycol methyl ether to prepare a co-solvent electrolyte with an electrolyte concentration of 1 mol / kg. In the prepared co-solvent electrolyte, ethylene glycol methyl ether and water serve as solvents, and zinc perchlorate serves as the electrolyte.

[0021] The cosolvent electrolyte obtained in Example 1 was observed to be a transparent liquid, indicating that zinc perchlorate had been completely dissolved in the mixed solvent of water and ethylene glycol methyl ether, thus demonstrating that the cosolvent electrolyte had been successfully prepared.

[0022] Comparative Example 1

[0023] Using pure water as a solvent, a zinc perchlorate electrolyte with an electrolyte concentration of 1 mol / kg was prepared to obtain a zinc perchlorate pure water electrolyte. Specifically, at room temperature, 1 mol of anhydrous zinc perchlorate was added to 1 kg of pure water to obtain a zinc perchlorate pure water electrolyte with a concentration of 1 mol / kg.

[0024] The battery separator, after being wetted with the co-solvent electrolyte of Example 1, was ignited at high temperature. The co-solvent electrolyte obtained in Example 1 and the zinc perchlorate pure water electrolyte obtained in Comparative Example 1 were also subjected to a storage experiment at a low temperature of -60 °C.

[0025] In the high-temperature ignition experiment, the glass fiber diaphragm of Example 1, after being impregnated with the co-solvent electrolyte, was ignited for 10 seconds. (Image of the diaphragm is shown below.) Figure 1 As shown, the glass fiber diaphragm, after being impregnated with the co-solvent electrolyte, did not burn. In the low-temperature environment test, the actual image of the zinc perchlorate pure water electrolyte after being left at -60 ℃ for 24 h is shown below. Figure 2 As shown, by Figure 2 As shown, the electrolyte has been completely frozen; a physical image of the co-solvent electrolyte of Example 1 after being left at -60 ℃ for 24 h is shown below. Figure 3 As shown, by Figure 3 As shown, the co-solvent electrolyte remains liquid.

[0026] Comparative Example 2

[0027] A zinc perchlorate electrolyte with a concentration of 1 mol / kg was prepared using pure ethylene glycol methyl ether as a solvent. Specifically, 1 mol of anhydrous zinc perchlorate was added to 1 kg of ethylene glycol methyl ether to obtain a zinc perchlorate electrolyte with a concentration of 1 mol / kg.

[0028] Comparative Example 3

[0029] A method for preparing an electrolyte for zinc-ion batteries, specifically: at room temperature (around 25 ℃), first mix 400 g of water and 600 g of ethylene glycol methyl ether at a mass ratio of 1:1.5, then add 1 mol of anhydrous zinc sulfate to the mixed solvent of water and ethylene glycol methyl ether to prepare an electrolyte with an electrolyte concentration of 1 mol / kg.

[0030] Comparative Example 4

[0031] A method for preparing an electrolyte for zinc-ion batteries, specifically: at room temperature (around 25 ℃), first mix 400 g of water and 600 g of ethylene glycol methyl ether at a mass ratio of 1:1.5, then add 1 mol of anhydrous zinc acetate to the mixed solvent of water and ethylene glycol methyl ether to prepare an electrolyte with an electrolyte concentration of 1 mol / kg.

[0032] Comparative Example 5

[0033] A method for preparing an electrolyte for zinc-ion batteries, specifically: at room temperature (around 25 ℃), first mix 250 g of water and 750 g of ethylene glycol methyl ether at a mass ratio of 1:3, then add 1 mol of anhydrous zinc perchlorate to the mixed solvent of water and ethylene glycol methyl ether to prepare an electrolyte with an electrolyte concentration of 1 mol / kg.

[0034] Comparative Example 6

[0035] A method for preparing an electrolyte for zinc-ion batteries is as follows: at room temperature (around 25 ℃), 400 g of water and 600 g of ethylene glycol methyl ether are mixed at a mass ratio of 1:1.5. Then, 0.2 mol of anhydrous zinc perchlorate is added to the mixed solvent of water and ethylene glycol methyl ether to prepare an electrolyte with an electrolyte concentration of 0.2 mol / kg.

[0036] Comparative Example 7

[0037] A method for preparing an electrolyte for zinc-ion batteries is as follows: at room temperature (around 25 ℃), 400 g of water and 600 g of ethylene glycol methyl ether are mixed at a mass ratio of 1:1.5. Then, 3 mol of anhydrous zinc perchlorate is added to the mixed solvent of water and ethylene glycol methyl ether to prepare an electrolyte with an electrolyte concentration of 3 mol / kg.

[0038] Comparative Example 8

[0039] A method for preparing an electrolyte for zinc-ion batteries, specifically: at room temperature (around 25 ℃), first mix 400 g of water and 600 g of ethylene glycol at a mass ratio of 1:1.5, then add 1 mol of anhydrous zinc perchlorate to the mixed solvent of water and ethylene glycol to prepare an electrolyte with an electrolyte concentration of 1 mol / kg.

[0040] The electrolytes of Comparative Examples 2-8 were subjected to high-temperature ignition and low-temperature storage experiments at -60 °C, and the results were as follows:

[0041] The electrolyte in Comparative Example 2 did not completely dissolve at room temperature. When the glass fiber membrane impregnated with the electrolyte from Comparative Example 2 was ignited at high temperature, the membrane immediately burned. After being placed in a -60°C environment for 24 hours, the electrolyte exhibited a partially frozen state with a solid-liquid mixture. The electrolyte in Comparative Example 3 did not completely dissolve at room temperature. When the glass fiber membrane impregnated with the electrolyte from Comparative Example 3 was ignited at high temperature, the membrane burned after more than 10 seconds. After being placed in a -60°C environment for 24 hours, the electrolyte exhibited a completely frozen solid state. The electrolyte in Comparative Example 4 did not completely dissolve at room temperature. When the glass fiber membrane impregnated with the electrolyte from Comparative Example 4 was ignited at high temperature, the membrane burned after more than 10 seconds. After being placed in a -60°C environment for 24 hours, the electrolyte exhibited a completely frozen solid state. In Comparative Example 5, the zinc salt in the electrolyte completely dissolved at room temperature. A glass fiber diaphragm impregnated with the electrolyte from Comparative Example 5 was ignited at high temperature; the diaphragm burned after more than 5 seconds. After being placed at -60 ℃ for 24 hours, the electrolyte exhibited a partially frozen state with a solid-liquid mixture. In Comparative Example 6, the zinc salt in the electrolyte completely dissolved at room temperature. A glass fiber diaphragm impregnated with the electrolyte from Comparative Example 6 was ignited at high temperature; the diaphragm burned after more than 10 seconds. After being placed at -60 ℃ for 24 hours, the electrolyte exhibited a completely frozen solid state. In Comparative Example 7, the zinc salt in the electrolyte did not completely dissolve at room temperature. A glass fiber diaphragm impregnated with the electrolyte from Comparative Example 7 was ignited at high temperature; the diaphragm burned after more than 5 seconds. After being placed at -60 ℃ for 24 hours, the electrolyte exhibited a liquid, unfrozen state. The zinc salt in the electrolyte of Comparative Example 8 was completely dissolved at room temperature. The glass fiber diaphragm, which was wetted with the electrolyte of Comparative Example 8, was ignited at high temperature. The diaphragm burned after more than 5 seconds. The electrolyte was placed in a low temperature environment of -60 ℃ for 24 h and showed an incompletely frozen state with a mixture of solid and liquid.

[0042] Example 2

[0043] The present invention discloses a method for preparing an electrolyte for zinc-ion batteries, specifically as follows: At room temperature (around 25°C), 400 g of water and 600 g of ethylene glycol methyl ether are mixed at a mass ratio of 1:1.5. Then, 1.5 mol of anhydrous zinc perchlorate is completely dissolved in the mixed solvent of water and ethylene glycol methyl ether to prepare a co-solvent electrolyte with an electrolyte concentration of 1.5 mol / kg. In the prepared co-solvent electrolyte, ethylene glycol methyl ether and water serve as solvents, and zinc perchlorate serves as the electrolyte.

[0044] The cosolvent electrolyte obtained in Example 2 was observed to be a transparent liquid, indicating that zinc perchlorate had been completely dissolved in the mixed solvent of water and ethylene glycol methyl ether, thus demonstrating that the cosolvent electrolyte had been successfully prepared.

[0045] Comparative Example 9

[0046] Using pure water as a solvent, a zinc perchlorate electrolyte with an electrolyte concentration of 1.5 mol / kg was prepared to obtain a zinc perchlorate pure water electrolyte. Specifically, at room temperature, 1.5 mol of anhydrous zinc perchlorate was added to 1 kg of pure water to obtain a zinc perchlorate pure water electrolyte with a concentration of 1.5 mol / kg.

[0047] When the battery separator, wetted with the co-solvent electrolyte of Example 2, was ignited at high temperature, the glass fiber separator wetted with the co-solvent electrolyte did not burn. In the low-temperature environment storage experiment, the zinc perchlorate pure water electrolyte of Comparative Example 2 was completely frozen after being stored at -60 ℃ for 24 h; the co-solvent electrolyte of Example 2 remained liquid after being stored at -60 ℃ for 24 h.

[0048] Example 3

[0049] The present invention discloses a method for preparing an electrolyte for zinc-ion batteries, specifically as follows: At room temperature (around 25°C), 500 grams of water and 500 grams of ethylene glycol methyl ether are mixed in a mass ratio of 1:1. Then, 1 mol of anhydrous zinc perchlorate is completely dissolved in the mixed solvent of water and ethylene glycol methyl ether to prepare a co-solvent electrolyte with an electrolyte concentration of 1 mol / kg. In the prepared co-solvent electrolyte, ethylene glycol methyl ether and water serve as solvents, and zinc perchlorate serves as the electrolyte.

[0050] When the battery separator, wetted with the co-solvent electrolyte of Example 3, was ignited at high temperature, the glass fiber separator did not burn. In the low-temperature environment storage experiment, the co-solvent electrolyte of Example 3 remained liquid after being stored at -60 ℃ for 24 h.

[0051] Zinc-ion batteries were assembled using the co-solvent electrolyte prepared in Example 1; the positive electrode material was polyaniline (PANI). In preparing the positive electrode, the active material (polyaniline), conductive agent Ketjen black, and binder polytetrafluoroethylene (PTFE) were mixed in a mass ratio of 7:2:1. N-methylpyrrolidone (NMP) was added, and the mixture was ground to obtain a uniform slurry. The slurry was then scraped onto a stainless steel mesh and dried in a 60 °C drying oven. The resulting positive electrode had an active material (polyaniline) loading (positive electrode material loading on the stainless steel mesh) of approximately 1–3 mg / cm³. 2 The negative electrode uses zinc foil with a thickness of 10~30 μm, and the separator uses glass fiber (GF / D). A zinc-ion battery based on a co-solvent electrolyte, namely a Zn / / PANI CR2032 button cell, was assembled and constant current charge-discharge tests were performed.

[0052] At -40 °C, the rate performance of the Zn / / PANI battery based on the co-solvent electrolyte of Example 1 at different current densities (0.5 A / g, 1 A / g, 2 A / g, 5 A / g) is as follows: Figure 4 As shown, it exhibits a high discharge capacity of 72.1 mAh / g even at a high current density of 5 A / g, indicating that it still possesses efficient ion transport kinetics at low temperatures. At -60 °C, the Zn / / PANI battery based on the co-solvent electrolyte of Example 1 performs as follows after 130 cycles at a current density of 30 mA / g. Figure 5 As shown, the initial discharge capacity is 131.2 mAh / g, and after 130 cycles, it still has a high discharge capacity of 102.3 mAh / g, indicating that it has good cycle stability.

[0053] At 70 °C, the Zn / / PANI battery based on the co-solvent electrolyte of Example 1 performed as follows after 3360 cycles at a current density of 10 A / g: Figure 6 As shown, the initial capacity is 147.2 mAh / g, and after 3360 cycles, it still retains a high discharge capacity of 76.8 mAh / g. At 100 °C, the Zn / / PANI battery based on the co-solvent electrolyte of Example 1 performs as follows after 360 cycles at a current density of 10 A / g. Figure 7 As shown, the initial capacity is 190.3 mAh / g, and it still has a high discharge capacity of 97.3 mAh / g after 360 cycles.

[0054] At -40 °C, the Zn / / PANI battery based on the zinc perchlorate pure water electrolyte of Comparative Example 1 could not achieve rate performance due to insufficient charge / discharge at different current densities (0.5 A / g, 1 A / g, 2 A / g, 5 A / g). At -60 °C, the electrolyte was completely frozen, preventing further charge / discharge. At -60 °C, the Zn / / PANI battery based on the co-solvent electrolyte of Example 2 exhibited a high discharge capacity of 126.4 mAh / g at a current density of 30 mA / g; at 100 °C, the initial capacity at a current density of 10 A / g was 175.6 mAh / g, and after 180 cycles, it still retained a high discharge capacity of 85.5 mAh / g. At -60 °C, the Zn / / PANI battery based on the co-solvent electrolyte of Example 3 exhibits a high discharge capacity of 135.1 mAh / g at a current density of 30 mA / g; at 100 °C, the initial capacity is 213.5 mAh / g at a current density of 10 A / g, and it still has a high discharge capacity of 107.7 mAh / g after 120 cycles.

[0055] pass Figure 8 It can be seen that, compared with the pure water-based zinc perchlorate electrolyte of Comparative Example 1, the co-solvent electrolyte of Example 1 can broaden the electrochemical window and effectively reduce the reaction currents (OER) of hydrogen evolution at the anode and oxygen evolution at the cathode at high temperatures.

[0056] The co-solvent electrolyte of this invention is non-flammable at high temperatures and promotes ultra-long cycle stability of the battery at high temperatures. It is also resistant to freezing at ultra-low temperatures of -60°C and the battery has high discharge capacity and rate performance. The co-solvent electrolyte of this invention has ultra-wide temperature stability from -60°C to 100°C. Therefore, zinc-ion batteries based on the co-solvent electrolyte have good electrochemical performance in the above ultra-wide temperature range.

Claims

1. An electrolyte for zinc-ion batteries with an ultra-wide temperature range of -60°C to 100°C, characterized in that: The electrolyte is a co-solvent electrolyte, which is formed by adding a zinc salt to a mixed solvent of water and ethylene glycol ethers. The zinc salt is at least one of zinc trifluoromethanesulfonate, zinc chloride, zinc bis(trifluoromethanesulfonyl)imide, zinc perchlorate, or zinc tetrafluoroborate.

2. The electrolyte for zinc-ion batteries according to claim 1, characterized in that: The ethylene glycol ether solvent is at least one of ethylene glycol methyl ether, ethylene glycol ethyl ether, ethylene glycol propyl ether, ethylene glycol butyl ether, and ethylene glycol hexyl ether.

3. The electrolyte for zinc-ion batteries according to claim 1, characterized in that: The mass ratio of water to ethylene glycol ether solvent is 1:1~2.

4. The electrolyte for zinc-ion batteries according to claim 3, characterized in that: The mass ratio of water to ethylene glycol ether solvent is 1:1 to 1.

5.

5. The electrolyte for zinc-ion batteries according to claim 1, characterized in that: The zinc salt molar concentration in the electrolyte is 1~1.5 mol / kg.

6. The electrolyte for zinc-ion batteries according to claim 1, characterized in that: The purity of the zinc trifluoromethanesulfonate, zinc chloride, bis(trifluoromethanesulfonyl)imide zinc, zinc perchlorate, or zinc tetrafluoroborate is ≥99.8%; the purity of the ethylene glycol ether solvent is ≥99.8%; and the water is deionized water.

7. The method for preparing the electrolyte for zinc-ion batteries according to claim 1, characterized in that, Specifically, at room temperature, water and ethylene glycol ether solvents are first mixed at a mass ratio of 1:1~2, and then the zinc salt is completely dissolved in the mixed solvent of water and ethylene glycol ether solvents to prepare a co-solvent electrolyte with an electrolyte concentration of 1~1.5 mol / kg.

8. The preparation method according to claim 7, characterized in that: The water and ethylene glycol ether solvent are used in a mass ratio of 1:1 to 1.5.

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