Low-temperature organic electrolyte and preparation method thereof
Through the combination of low freezing point solvent and zinc salt, a stable solvated structure and solid electrolyte interface are formed, which solves the problem of freezing and corrosion of zinc ion batteries at low temperatures, and achieves the stability and life of the battery.
Patent Information
- Application Number
- CN202510570206.6
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-04-30
- Publication Date
- 2025-08-29
AI Technical Summary
Traditional aqueous zinc ion electrolytes are prone to freeze under low temperature environments, resulting in increased interface impedance and difficulty in ion migration. In addition, zinc metals have problems such as dendrite growth, hydrogen evolution reaction and corrosion, and existing strategies cannot be effectively solved.
Low-freezing point solvents such as tetrahydrofuran and triethyl phosphate and zinc salts such as zinc tetrafluoroborate are used to form a stable solvation structure rich in anions, promoting the rapid desolution of zinc ions at low temperatures, and forming a solid electrolyte interface through triethyl phosphate participating in the redox reaction on the negative electrode surface, which is coordinated to flame retardant.
Effectively avoid electrolyte solidification at low temperatures, improve the stability and service life of zinc ion batteries, inhibit corrosion of zinc negative electrodes, ensure uniform deposition of zinc ions, and extend the battery cycle life.
Smart Images
Figure CN120565844A_ABST
Abstract
Description
Technical Field
[0001] The present application belongs to the technical field of zinc ion batteries, and specifically relates to a low-temperature organic electrolyte and a preparation method thereof. Background Art
[0002] Currently, zinc-ion batteries are one of the energy storage systems with the greatest commercial potential. However, traditional aqueous electrolytes face numerous challenges in low-temperature environments. First, the thermodynamic freezing point of water is 0°C, which means that the electrolyte freezes at low temperatures, increasing interfacial impedance and hindering ion migration, leading to battery failure. Second, zinc metal presents challenges such as dendrite growth, hydrogen evolution reaction, and corrosion, which are particularly severe at low temperatures. At present, researchers have proposed many strategies, such as: (1) electrolyte additive strategy, which uses hydroxyl-rich additives to lower the freezing point of the electrolyte by destroying the hydrogen bonds between water molecules, but it cannot completely avoid the hydrogen evolution reaction related to water molecules. At the same time, with the decrease in temperature, the viscosity of the electrolyte will increase, resulting in a decrease in conductivity and slower ion transport; (2) high-concentration electrolyte strategy, by adding high-concentration zinc salts, the anions in the zinc salts will destroy the hydrogen bonds between water molecules, thereby lowering the freezing point of the electrolyte, but this strategy increases the cost due to the addition of too high a concentration of zinc salts; (3) antifreeze hydrogel strategy, hydrogels are usually composed of elastically cross-linked water-containing polymer chains, and the gaps between polymer chains are filled with a large amount of water. Free water can interact with amino, hydroxyl and amide groups on the polymer chains to form hydrogen bonds, thereby greatly lowering the freezing point, but it requires a complex preparation process, which is not conducive to industrial production.
[0003] The above strategies are all based on regulating the hydrogen bonds between water molecules and cannot solve problems such as electrolyte freezing and salt precipitation caused by low temperatures. Therefore, a new strategy is needed to solve the above problems. Summary of the Invention
[0004] The present application provides a low-temperature organic electrolyte and its preparation method and application, aiming to solve the problem of battery failure caused by solidification of aqueous electrolyte at low temperatures.
[0005] In a first aspect, the present application provides a low-temperature organic electrolyte comprising a low-freezing-point solvent and a zinc salt.
[0006] According to some embodiments of the low-temperature organic electrolyte described in the present application, the low freezing point solvent includes one or more of tetrahydrofuran, triethyl phosphate, trimethyl phosphate, methanol, N,N-dimethylformamide and ethylene glycol dimethyl ether.
[0007] According to some embodiments of the low-temperature organic electrolyte described herein, the low freezing point solvent includes tetrahydrofuran and triethyl phosphate.
[0008] According to some embodiments of the low-temperature organic electrolyte described in the present application, the low freezing point solvent includes tetrahydrofuran and triethyl phosphate in a volume ratio of 1:(0.5-2).
[0009] According to some embodiments of the low-temperature organic electrolyte described herein, the zinc salt includes one or more of zinc tetrafluoroborate, zinc sulfate, zinc acetate, zinc perchlorate, and zinc trifluoromethanesulfonate.
[0010] According to some embodiments of the low-temperature organic electrolyte described herein, the zinc salt is zinc tetrafluoroborate.
[0011] According to some embodiments of the low-temperature organic electrolyte described in the present application, the concentration of the zinc salt in the organic electrolyte is 0.2-1 mol / L.
[0012] The second aspect of the present application provides a method for preparing the low-temperature organic electrolyte described in the first aspect of the present application, comprising the following steps: mixing a zinc salt and a low-freezing-point solvent.
[0013] The third aspect of the present application provides a use of the low-temperature organic electrolyte described in the first aspect of the present application or the low-temperature organic electrolyte obtained by the preparation method described in the second aspect of the present application in a zinc battery.
[0014] According to some embodiments of the application described in this application, the zinc battery includes a Zn||Zn symmetric battery or a zinc ion full battery.
[0015] The beneficial effects of the present application include: the low-temperature organic electrolyte described in the present application uses a mixture of a solvent with a low freezing point and a zinc salt, which solves the problem of battery failure caused by the electrolyte solidifying in a low-temperature environment. BRIEF DESCRIPTION OF THE DRAWINGS
[0016] Figure 1 This is a SEM image of the zinc negative electrode surface of the Zn||Zn symmetrical battery assembled with the low-temperature organic electrolyte described in Example 4 of the present application after 30 cycles;
[0017] Figure 2 This is a SEM image of the zinc negative electrode surface of the Zn||Zn symmetrical battery assembled with the low-temperature organic electrolyte described in Comparative Example 1 of the present application after 30 cycles;
[0018] Figure 3 This is a cycle curve diagram of an ammonium vanadate full battery assembled with the low-temperature organic electrolyte described in Example 4 and Comparative Example 1 of the present application at 25°C;
[0019] Figure 4 This is a cycle curve diagram of an ammonium vanadate full battery assembled with the low-temperature organic electrolyte described in Example 4 of the present application at -20°C;
[0020] Figure 5This is a cycle curve diagram of an ammonium vanadate full battery assembled with the low-temperature organic electrolyte described in Example 4 of the present application at -40°C;
[0021] Figure 6 It is the freezing point of the low-temperature organic electrolyte described in Comparative Example 1 and Example 4 of this application. DETAILED DESCRIPTION
[0022] The embodiments of the present invention are described in detail below. The examples of the embodiments are exemplary and intended to be used to explain the present invention, but should not be understood as limiting the present invention.
[0023] In the present invention, the terms "one embodiment", "some embodiments", "examples", "specific examples", or "some examples" mean that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic expressions of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art can combine and combine different embodiments or examples described in this specification and the features of different embodiments or examples without contradiction.
[0024] An embodiment of the present application provides a low-temperature organic electrolyte, comprising a low-freezing-point solvent and a zinc salt.
[0025] The low-temperature organic electrolyte described in the present application uses a mixture of a solvent with a low freezing point and a zinc salt, which solves the problem of battery failure caused by the electrolyte solidifying in a low-temperature environment.
[0026] In some embodiments of the present application, the low freezing point solvent includes one or more of tetrahydrofuran, triethyl phosphate, trimethyl phosphate, methanol, N,N-dimethylformamide and ethylene glycol dimethyl ether.
[0027] In some embodiments of the present application, the low freezing point solvent includes tetrahydrofuran and triethyl phosphate. Triethyl phosphate and tetrahydrofuran have a relatively low dielectric constant, which can promote the interaction between zinc ions and anions, forming a solvated structure rich in anions, which is conducive to forming a stable, ZnF2-rich solid electrolyte interface layer, promoting the rapid desolvation of zinc ions at low temperatures. In addition, triethyl phosphate also participates in the redox reaction on the negative electrode surface, forming a solid electrolyte interface containing zinc phosphate. In addition, zinc tetrafluoroborate and triethyl phosphate in the organic electrolyte described in the present application also play a synergistic flame retardant role.
[0028] In some embodiments of the present application, the low freezing point solvent includes tetrahydrofuran and triethyl phosphate in a volume ratio of 1:(0.5-2), such as 1:0.5, 1:0.8, 1:1, 1:1.5, 1:2, etc.
[0029] In some embodiments of the present application, the zinc salt includes one or more of zinc tetrafluoroborate, zinc sulfate, zinc acetate, zinc perchlorate, and zinc trifluoromethanesulfonate. The above zinc salts have been industrialized and are conducive to industrial application.
[0030] In some embodiments of the present application, the zinc salt is zinc tetrafluoroborate.
[0031] In some embodiments of the present application, the concentration of the zinc salt in the low-temperature organic electrolyte is 0.2-1 mol / L, for example, 0.2 mol / L, 0.5 mol / L, 0.8 mol / L, 0.9 mol / L, 1.0 mol / L, etc. When the zinc salt concentration is lower than 0.2 mol / L, the low zinc ion conductivity is insufficient to support the operation of the zinc ion battery in a low-temperature environment; when the zinc salt content is higher than 1 mol / L, the solubility of the zinc salt in the organic solvent is limited, and there are also cost issues.
[0032] An embodiment of the present application also provides a method for preparing the low-temperature organic electrolyte described in the first aspect of the present application, comprising the following steps: mixing a zinc salt and a low-freezing-point solvent.
[0033] The embodiments of the present application also provide a use of the low-temperature organic electrolyte described in the first aspect of the present application or the low-temperature organic electrolyte obtained by the preparation method described in the second aspect of the present application in a zinc battery.
[0034] According to some embodiments of the application described in this application, the zinc battery includes a Zn||Zn symmetrical battery or a zinc ion full battery. The zinc battery described in this application has good stability at low temperatures and a relatively long service life.
[0035] The technical solution of this application is further described below with reference to specific embodiments.
[0036] Example 1
[0037] A method for preparing a low-temperature organic electrolyte comprises the following steps:
[0038] Zinc tetrafluoroborate (Zn(BF4)2) was dissolved in tetrahydrofuran solution to prepare a low-temperature organic electrolyte with a concentration of 0.5 mol / L.
[0039] The specific operation steps include: weighing 0.3585g of zinc tetrafluoroborate, dissolving it in 3ml of tetrahydrofuran, and stirring it thoroughly to form a uniform liquid to prepare a low-temperature organic electrolyte with a concentration of 0.5mol / L.
[0040] Example 2
[0041] The preparation method of the low-temperature organic electrolyte described in Example 2 is different from that of Example 1 only in that the low-freezing point solvent used in the preparation process of the low-temperature organic electrolyte described in Example 2 is tetrahydrofuran and triethyl phosphate in a volume ratio of 2:1.
[0042] The specific operation steps include: weighing 0.3585g of zinc tetrafluoroborate, dissolving it in a low-freezing point solvent composed of 2ml of tetrahydrofuran and 1ml of triethyl phosphate, and stirring it thoroughly to form a uniform liquid to prepare a low-temperature organic electrolyte with a concentration of 0.5mol / L.
[0043] Example 3
[0044] The only difference between the preparation method of the low-temperature organic electrolyte described in Example 3 and that in Example 1 is that the low-freezing point solvent used in the preparation process of the low-temperature organic electrolyte described in Example 3 is tetrahydrofuran and triethyl phosphate in a volume ratio of 1:1.
[0045] The specific operation steps include: weighing 0.3585g of zinc tetrafluoroborate, dissolving it in a low-freezing point solvent composed of 1.5ml of tetrahydrofuran and 1.5ml of triethyl phosphate, and stirring it thoroughly to form a uniform liquid to prepare a low-temperature organic electrolyte with a concentration of 0.5mol / L.
[0046] Example 4
[0047] The preparation method of the low-temperature organic electrolyte described in Example 4 is different from that of Example 1 only in that the low-freezing point solvent used in the preparation process of the low-temperature organic electrolyte described in Example 4 is tetrahydrofuran and triethyl phosphate in a volume ratio of 1:2.
[0048] The specific operation steps include: weighing 0.3585g of zinc tetrafluoroborate, dissolving it in a low-freezing point solvent composed of 1ml of tetrahydrofuran and 2ml of triethyl phosphate, and stirring it thoroughly to form a uniform liquid to prepare a low-temperature organic electrolyte with a concentration of 0.5mol / L.
[0049] Example 5
[0050] The only difference between the preparation method of the low-temperature organic electrolyte described in Example 5 and that of Example 1 is that triethyl phosphate, a low-freezing-point solvent, is used instead of tetrahydrofuran during the preparation process of the low-temperature organic electrolyte described in Example 5.
[0051] The specific operation steps include: weighing 0.3585g of zinc tetrafluoroborate, dissolving it in 3ml of triethyl phosphate, and stirring it thoroughly to form a uniform liquid to prepare a low-temperature organic electrolyte with a concentration of 0.5mol / L.
[0052] Example 6
[0053] The method for preparing the low-temperature electrolyte described in Example 6 is different from that in Example 4 only in that zinc sulfate is used instead of zinc tetrafluoroborate in the preparation process of the electrolyte described in Example 6.
[0054] The specific operation steps include: weighing 0.4305g ZnSO4·7H2O, dissolving it in a low freezing point solvent consisting of 1ml tetrahydrofuran and 2ml triethyl phosphate, and stirring thoroughly.
[0055] Example 7
[0056] The method for preparing the low-temperature organic electrolyte described in Example 7 is different from that in Example 4 only in that zinc perchlorate is used instead of zinc tetrafluoroborate in the preparation process of the low-temperature organic electrolyte described in Example 7.
[0057] The specific operation steps include: weighing 0.5586 g of zinc perchlorate, dissolving it in a low freezing point solvent consisting of 1 ml of tetrahydrofuran and 2 ml of triethyl phosphate, and stirring thoroughly.
[0058] Example 8
[0059] The only difference between the preparation method of the low-temperature organic electrolyte described in Example 8 and that of Example 4 is that zinc trifluoromethanesulfonate is used instead of zinc tetrafluoroborate in the preparation process of the low-temperature organic electrolyte described in Example 8.
[0060] The specific operation steps include: weighing 0.5452 g of zinc trifluoromethanesulfonate, dissolving it in a low freezing point solvent consisting of 1 ml of tetrahydrofuran and 2 ml of triethyl phosphate, and stirring thoroughly.
[0061] Example 9
[0062] The method for preparing the low-temperature organic electrolyte described in Example 9 is different from that in Example 4 only in that zinc acetate is used instead of zinc tetrafluoroborate in the preparation process of the low-temperature organic electrolyte described in Example 9.
[0063] The specific operation steps include: weighing 0.3292 g of zinc acetate, dissolving it in a low freezing point solvent consisting of 1 ml of tetrahydrofuran and 2 ml of triethyl phosphate, and stirring thoroughly.
[0064] Example 10
[0065] The only difference between the method for preparing the low-temperature organic electrolyte described in Example 10 and that in Example 4 is that during the preparation of the low-temperature organic electrolyte described in Example 10, the concentration of zinc tetrafluoroborate in the electrolyte is controlled to be 0.2 mol / L.
[0066] The specific operation steps include: weighing 0.1434g of zinc tetrafluoroborate, dissolving it in a low freezing point solvent composed of 1ml of tetrahydrofuran and 2ml of triethyl phosphate, and stirring it thoroughly to form a uniform liquid to prepare a low-temperature organic electrolyte with a concentration of 0.2mol / L.
[0067] Example 11
[0068] The only difference between the method for preparing the low-temperature organic electrolyte described in Example 11 and that in Example 4 is that, during the preparation of the low-temperature organic electrolyte described in Example 11, the concentration of zinc tetrafluoroborate in the electrolyte is controlled to be 1 mol / L.
[0069] The specific operation steps include: weighing 0.7170g of zinc tetrafluoroborate, dissolving it in a low-freezing point solvent composed of 1ml of tetrahydrofuran and 2ml of triethyl phosphate, and stirring it thoroughly to form a uniform liquid to prepare a low-temperature organic electrolyte with a concentration of 1 mol / L.
[0070] Example 12
[0071] The only difference between the preparation method of the low-temperature organic electrolyte described in Example 12 and that of Example 4 is that, during the preparation process of the low-temperature organic electrolyte described in Example 12, the concentration of zinc tetrafluoroborate in the electrolyte is controlled to be 0.6 mol / L.
[0072] The specific operation steps include: weighing 0.4302g of zinc tetrafluoroborate, dissolving it in a low-freezing point solvent composed of 1ml of tetrahydrofuran and 2ml of triethyl phosphate, and stirring it thoroughly to form a uniform liquid to prepare a low-temperature organic electrolyte with a concentration of 0.6mol / L.
[0073] Example 13
[0074] The only difference between the preparation method of the low-temperature organic electrolyte described in Example 13 and that of Example 4 is that trimethyl phosphate is used instead of triethyl phosphate in the preparation process of the low-temperature organic electrolyte described in Example 13.
[0075] The specific operation steps include: weighing 0.3585g of zinc tetrafluoroborate, dissolving it in a low-freezing point solvent composed of 1ml of tetrahydrofuran and 2ml of trimethyl phosphate in a volume ratio of 1:2, and stirring it thoroughly to form a uniform liquid to prepare a low-temperature organic electrolyte with a concentration of 0.5mol / L.
[0076] Example 14
[0077] The only difference between the preparation method of the low-temperature organic electrolyte described in Example 14 and that of Example 4 is that methanol is used as the low-freezing point solvent in the preparation process of the low-temperature organic electrolyte described in Example 14.
[0078] Example 15
[0079] The only difference between the preparation method of the low-temperature organic electrolyte described in Example 15 and that of Example 4 is that N,N-dimethylformamide is used as a low-freezing point solvent in the preparation process of the low-temperature organic electrolyte described in Example 15.
[0080] Example 16
[0081] The only difference between the preparation method of the low-temperature organic electrolyte described in Example 16 and that of Example 4 is that ethylene glycol dimethyl ether is used as a low-freezing point solvent in the preparation process of the low-temperature organic electrolyte described in Example 16.
[0082] Comparative Example 1
[0083] The only difference between the preparation method of the low-temperature organic electrolyte described in Comparative Example 1 and that of Example 4 is that water is used instead of the low-freezing point solvent in the preparation process of the low-temperature organic electrolyte described in Comparative Example 1.
[0084] Study on the electrical properties of the low-temperature organic electrolytes described in Examples 1-16 and Comparative Example 1 of the present application
[0085] 1. The low-temperature organic electrolytes described in Examples 1-16 and Comparative Example 1 were combined with zinc sheets, electrolytes, glass fiber separators, and zinc sheets to form Zn||Zn symmetrical batteries. Using a Xinwei battery testing system, the Zn||Zn symmetrical batteries were subjected to long-term charge-discharge cycling tests until a short circuit occurred. The cycle time was recorded.
[0086] The current density of charge and discharge at 25°C is 1 mA cm -2 , the charge and discharge capacity is controlled to 1mAh cm -2 ;
[0087] The current density of charge and discharge at -20°C is 0.5 mA cm -2 , the charge and discharge capacity is controlled to 0.5 mAh cm -2 ;
[0088] The current density of charge and discharge at -40°C is 0.1 mA cm -2 , the charge and discharge capacity is controlled to 0.1 mAh cm -2 .
[0089] The long cycle performance of the above zinc symmetrical battery at room temperature (25°C) and at low temperature is shown in Table 1.
[0090] Table 1
[0091]
[0092]
[0093] As can be seen from Table 1: Examples 6, 8, and 9 of the present application show that zinc sulfate, zinc trifluoromethanesulfonate, and zinc acetate exhibit extremely low solubility in tetrahydrofuran and triethyl phosphate with a volume ratio of 1:2, and cannot maintain battery operation. Therefore, the cycle life of the symmetrical battery is 0 hours.
[0094] It can be seen from Examples 10, 11, and 12 of the present application that when the concentration of zinc tetrafluoroborate is less than 0.5 mol / L, the symmetrical battery exhibits an extremely low cycle life, which is mainly due to the extremely low ionic conductivity, especially at low temperatures. When the concentration gradually increases to 1 mol / L, the increase in electrolyte viscosity makes ion transport difficult, and thus the cycle life is lower than that of 0.5 mol / L.
[0095] It can be seen from Examples 13, 14, 15, and 16 of the present application that when the low-freezing-point organic solvent is replaced with other organic solvents, the cycle life of the symmetrical battery is greatly extended both at room temperature and at low temperature compared with Comparative Example 1, indicating that side reactions such as corrosion of the zinc negative electrode are suppressed.
[0096] The zinc battery composed of the organic electrolyte described in Example 4 of the present application and the electrolyte described in Comparative Example 1 was controlled at a current density and a capacity of 1 mA cm -2 and 1mAh cm -2 The SEM images of the zinc sheets of the zinc battery after 30 cycles under the conditions are as follows: Figure 1 and Figure 2 shown.
[0097] from Figure 1 and Figure 2 It can be seen from the results that the conventional electrolyte with water as solvent has a very short symmetrical battery life. After 30 cycles, the battery was disassembled and the zinc sheet was observed through a scanning electron microscope. It was found that the zinc surface showed uneven deposition morphology and corrosion holes, which would affect the cycle life of the battery. Figure 2 On the contrary, in the organic electrolyte described in Example 4, the water-poor environment inhibits water corrosion, and the small organic solvent molecules can induce uniform deposition of zinc ions, thus showing a dendrite-free deposition morphology ( Figure 1 ).
[0098] 2. The electrolytes described in Example 4 and Comparative Example 1 of the present application were respectively assembled with an ammonium vanadate (NH4VO3) positive electrode, a zinc sheet, and a glass fiber separator to form an ammonium vanadate full battery.
[0099] The NH4VO3 positive electrode material was synthesized using a hydrothermal method. The specific synthesis method was to dissolve 0.7018g of ammonium metavanadate and 1.1346g of oxalic acid dihydrate in 30ml of deionized water and stir for 30 minutes. The mixture was then heated at 200°C and maintained for 12 hours to form a precipitate, which was then carefully collected and thoroughly washed with deionized water and ethanol to ensure purity. The resulting product NH4VO3 was dried under vacuum at 80°C for 12 hours to remove any residual moisture. Ammonium vanadate, conductive carbon black and polyvinylidene fluoride (PVDF) were mixed in a weight ratio of 7:2:1, N-methylpyrrolidone was used as a solvent, and the mixture was ground evenly and coated on a titanium foil. It was dried and set aside. The negative electrode was a zinc sheet and the separator was a glass fiber separator.
[0100] The Xinwei battery test system was used to conduct a long-term charge and discharge cycle test on the NH4VO3 full battery and record the capacity retention rate. The charging voltage range was 0.2V to 1.6V, and the discharging voltage range was 1.6V to 0.2V. The current density of charge and discharge at 25°C was 500mA g -1 The current density of charge and discharge at -20℃ and -40℃ is 100mA g -1 .
[0101] The cycle curves of the NH4VO3 full battery composed of the electrolytes described in Example 4 and Comparative Example 1 at 25°C are as follows: Figure 3 shown.
[0102] from Figure 3 It can be seen that the assembled ammonium vanadate full battery also shows obvious differences at room temperature. The initial capacity of comparative example 1 is 361.83 mAh g -1 , while the initial capacity of Example 4 is 453.33 mAh g -1 , has a higher initial capacity than that of Comparative Example 1. At 500 mAhg -1 After 300 cycles at a current density of , Comparative Example 1 shows a faster capacity decay trend, and the capacity retention rate is close to 0%, while Example 4 has a slower capacity decay, which is attributed to the serious side reaction of the electrolyte in Comparative Example 1, which will cause the positive electrode to dissolve during the cycle.
[0103] The cycle curves of the NH4VO3 full battery composed of the electrolyte described in Example 4 of the present application at -20°C and -40°C are as follows: Figure 4 and Figure 5 shown.
[0104] from Figure 4 and Figure 5 It can be seen that the full battery at -20℃ and -40℃ is 100mA g -1The initial capacity of the battery at -20 °C is 165.47 mAh g -1 , the initial capacity at -40 °C is 110.71 mAh g -1 , and after 200 cycles, there is still a capacity retention rate of 77.02%.
[0105] 3. Testing the freezing point of the electrolyte described in Example 4 and Comparative Example 1 of the present application
[0106] Equal amounts of the electrolytes described in Example 4 and Comparative Example 1 were placed in aluminum crucibles, and then the crucibles were placed in an environment of -170°C and heated to 25°C at a heating rate of 10°C / min. The freezing points of the electrolytes were tested using differential scanning calorimetry. The results are as follows: Figure 6 shown.
[0107] from Figure 6 It can be seen that the heating curve of the electrolyte described in Comparative Example 1 shows a clear enthalpy change peak and a freezing point of -11.42°C, indicating that the electrolyte will solidify at -20°C, resulting in increased interfacial impedance and difficulty in ion migration, which cannot meet the requirements of zinc ion batteries operating in low temperature environments. However, the heating curve of the electrolyte described in Example 4 does not show a clear enthalpy change peak and exhibits an extremely low glass transition temperature (-137.64°C), indicating that the electrolyte will not solidify at low temperatures.
[0108] The above description of the present invention and its embodiments is non-limiting, and the actual structure is not limited thereto. In short, if a person skilled in the art is inspired by the above and, without departing from the purpose of the present invention, designs a structure and embodiment similar to the technical solution without creatively designing, they shall fall within the scope of protection of the present invention.
Claims
1. A low-temperature organic electrolyte, characterized in that: Includes low freezing point solvents and zinc salts.
2. The low-temperature organic electrolyte according to claim 1, characterized in that The low freezing point solvent includes one or more of tetrahydrofuran, triethyl phosphate, trimethyl phosphate, methanol, N,N-dimethylformamide and ethylene glycol dimethyl ether.
3. The low-temperature organic electrolyte according to claim 1, characterized in that The low freezing point solvents include tetrahydrofuran and triethyl phosphate.
4. The low-temperature organic electrolyte according to claim 1, characterized in that The low freezing point solvent comprises tetrahydrofuran and triethyl phosphate in a volume ratio of 1:(0.5-2).
5. The low-temperature organic electrolyte according to claim 1, characterized in that The zinc salt includes one or more of zinc tetrafluoroborate, zinc sulfate, zinc acetate, zinc perchlorate and zinc trifluoromethanesulfonate.
6. The low-temperature organic electrolyte according to claim 1, characterized in that The zinc salt is zinc tetrafluoroborate.
7. The low-temperature organic electrolyte according to claim 1, characterized in that The concentration of the zinc salt in the organic electrolyte is 0.2-1 mol / L.
8. The method for preparing the low-temperature organic electrolyte according to any one of claims 1 to 7, characterized in that: The following steps are involved: Simply mix the zinc salt with a low freezing point solvent.
9. Use of the low-temperature organic electrolyte according to any one of claims 1 to 7 or the low-temperature organic electrolyte obtained by the preparation method according to claim 8 in a zinc battery.
10. The use according to claim 9, characterized in that The zinc ion battery includes a Zn||Zn symmetrical battery or a zinc ion full battery.