Electrolyte, preparation method thereof and aqueous ammonium ion battery

Abstract

The application belongs to the field of batteries, and specifically discloses an electrolyte, a preparation method thereof and a water-based ammonium ion battery. The electrolyte comprises ammonium salt, choline chloride, sucrose and water; and the molar ratio of the choline chloride to the sucrose is (3-6):1. The electrolyte of the application adopts choline chloride, sucrose and water to construct a hydrogen bond network with a specific structure, significantly binds free water molecule activity, inhibits the hydrogen evolution reaction of a negative electrode, widens the stable working potential range of a water-based electrolyte, optimizes the ion transmission kinetics of the electrolyte, ensures high ionic conductivity while inhibiting hydrogen evolution, and matches the high-rate energy storage demand.

Description

Technical Field

[0001] This invention belongs to the field of battery technology, specifically relating to an electrolyte, its preparation method, and an aqueous ammonium ion battery. Background Technology

[0002] Large-scale electrochemical energy storage is a core support for integrating renewable energy sources such as wind and solar power. Aqueous ion batteries, which use water as an electrolyte solvent, have advantages such as being non-flammable, non-explosive, environmentally compatible, and low-cost, making them an important development direction for next-generation energy storage technology. However, the inherent bottleneck of aqueous electrolytes lies in the hydrogen evolution reaction (HER): when the battery operating voltage exceeds the theoretical decomposition potential of water (1.23 V vs. SHE), water molecules in the electrolyte are prone to undergo a reduction reaction on the negative electrode surface, releasing hydrogen gas. This results in a narrow battery operating potential window, limited energy storage performance, and even safety hazards such as device bulging and failure, seriously restricting the industrialization process of aqueous ion batteries.

[0003] Existing technologies for suppressing hydrogen evolution mainly include three categories: high-concentration electrolyte systems, gel electrolyte modification, and the introduction of functional additives. Among them, deep eutectic solvents (DES), as a novel green solvent composed of hydrogen bond donors (HBD) and hydrogen bond acceptors (HBA), have the characteristics of tunable physicochemical properties (such as viscosity, conductivity, and electrochemical window), high safety, and excellent ion conduction performance. They are considered as potential materials to replace traditional organic electrolytes and ionic liquids and have attracted widespread attention in the field of aqueous batteries.

[0004] Despite extensive exploration of existing technologies, the following key issues remain to be addressed in the field of aqueous batteries:

[0005] (1) Limited hydrogen evolution inhibition effect: High-concentration electrolytes have problems such as a surge in viscosity and a decrease in ionic conductivity; gel electrolytes face problems such as high interfacial contact resistance and high preparation cost; single additives (such as sucrose) can only partially destroy the water-water hydrogen bond network, and the widened potential window is difficult to meet the needs of high energy density batteries.

[0006] (2) Bottlenecks in the application of DES system: The interface stability between the existing DES and the highly active negative electrode is poor, and the water content balance is difficult to control, resulting in insufficient compatibility between electrolyte and electrode materials, and limiting the application scenarios.

[0007] (3) Insufficient compatibility between electrode and electrolyte: Aqueous ion battery anode materials generally have problems such as excessively high working potential and low specific capacity. Existing electrolyte systems cannot effectively stimulate the intrinsic energy storage performance of electrode materials, making it difficult to achieve synergistic optimization of high rate and long cycle. Summary of the Invention

[0008] In order to overcome at least one of the technical problems existing in the prior art, one of the objectives of the present invention is to provide an electrolyte.

[0009] A second objective of this invention is to provide a method for preparing the aforementioned electrolyte.

[0010] The third objective of this invention is to provide an ammonium ion battery.

[0011] The fourth objective of this invention is to provide an electrical device.

[0012] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0013] The first aspect of the present invention provides an electrolyte comprising an ammonium salt, choline chloride, sucrose and water; wherein the molar ratio of choline chloride to sucrose is (3~6):1; and the mass of water is 40~60% of the total mass of the electrolyte.

[0014] This invention, for the first time, constructs a multi-component hydrogen-bonded cross-linked aqueous network (MHCAN) of choline chloride, sucrose, and water. The Cl- group of choline chloride forms directional cross-linking nodes with the hydroxyl groups of sucrose, and water molecules act as hydrogen-bonding bridges, embedding themselves between the nodes to form a three-dimensional "node-bridge-node" structure. This network significantly restricts the activity of free water molecules, reduces the hydrogen evolution potential, and greatly alleviates the problem of hydrogen evolution at low potentials in aqueous electrolytes.

[0015] In some embodiments of the present invention, the molar ratio of choline chloride to sucrose is any one of 3:1, 3.5:1, 3.8:1, 4:1, 4.2:1, 4.5:1, 4.8:1, 5:1, 5.2:1, 5.5:1, 5.8:1, 6:1, or a range of any two of these values.

[0016] In some embodiments of the present invention, the mass of the water is any value or a range formed by any two of the following: 40%, 42%, 44%, 45%, 46%, 48%, 50%, 52%, 54%, 55%, 56%, 58%, and 60% of the total mass of the electrolyte. By introducing 40-60% water, the present invention achieves a balance between the electrolyte viscosity and ionic conductivity, avoiding the high viscosity defect of the pure DES system; simultaneously, the hydrogen bonding network optimizes the NH4+. + The solvated sheath structure lowers the desolvation energy barrier, enabling the electrolyte's ionic conductivity and ion migration rate to meet the requirements for high-rate operation.

[0017] In some embodiments of the present invention, the molar concentration of choline chloride in the electrolyte is 1.9~3 mol / L; in some embodiments of the present invention, the molar concentration of choline chloride in the electrolyte is any value or a range formed by any two of the following: 1.9 mol / L, 2 mol / L, 2.1 mol / L, 2.2 mol / L, 2.3 mol / L, 2.4 mol / L, 2.5 mol / L, 2.6 mol / L, 2.7 mol / L, 2.8 mol / L, 2.9 mol / L, 3.0 mol / L; in some embodiments of the present invention, the molar concentration of choline chloride in the electrolyte is 2.4~2.8 mol / L.

[0018] In some embodiments of the present invention, the molar concentration of sucrose in the electrolyte is 0.4~0.8 mol / L; in some embodiments of the present invention, the molar concentration of sucrose in the electrolyte is any value of 0.4 mol / L, 0.5 mol / L, 0.6 mol / L, 0.7 mol / L, 0.8 mol / L, or a range formed by any two of these values; in some embodiments of the present invention, the molar concentration of sucrose in the electrolyte is 0.5~0.7 mol / L.

[0019] In some embodiments of the present invention, the molar concentration of the ammonium salt in the electrolyte is 0.5~3 mol / L; in some embodiments of the present invention, the molar concentration of the ammonium salt in the electrolyte is any value or a range formed by any two of the following: 0.5 mol / L, 0.6 mol / L, 0.8 mol / L, 1 mol / L, 1.2 mol / L, 1.4 mol / L, 1.5 mol / L, 1.6 mol / L, 1.8 mol / L, 2 mol / L, 2.2 mol / L, 2.4 mol / L, 2.5 mol / L, 2.6 mol / L, 2.8 mol / L, 3 mol / L; in some embodiments of the present invention, the molar concentration of the ammonium salt in the electrolyte is 0.8~1.2 mol / L.

[0020] In some embodiments of the present invention, the ammonium salt is selected from at least one of ammonium chloride, ammonium sulfate, ammonium nitrate, ammonium nitrite, ammonium acetate, ammonium phosphate, ammonium carbonate, and ammonium aminosulfonate.

[0021] A second aspect of the present invention provides a method for preparing the electrolyte described in the first aspect of the present invention, comprising the following steps:

[0022] The product is prepared by mixing raw materials including ammonium salt, choline chloride, sucrose and water.

[0023] In some embodiments of the present invention, the mixing is performed using at least one of ultrasound and stirring.

[0024] A third aspect of the present invention provides an ammonium-ion battery comprising the electrolyte described in the first aspect of the present invention.

[0025] In some embodiments of the present invention, the negative electrode of the ammonium ion battery contains layered titanate; in some embodiments of the present invention, the negative electrode of the ammonium ion battery contains 0.1~0.4 mg / cm³ of... 2 Layered titanate; in some embodiments of the present invention, the negative electrode of the ammonium ion battery contains 0.2~0.3 mg / cm³ of... 2 Layered titanate.

[0026] In some embodiments of the present invention, the layered titanate is prepared by mixing titanium dioxide and alkaline solution and then carrying out a hydrothermal reaction.

[0027] In some embodiments of the present invention, the temperature of the hydrothermal reaction is 120~150°C.

[0028] In some embodiments of the present invention, the hydrothermal reaction time is 4 to 10 hours.

[0029] In some embodiments of the present invention, the alkaline solution is selected from at least one of sodium hydroxide solution and potassium hydroxide solution.

[0030] In some embodiments of the present invention, the negative electrode of the ammonium ion battery further contains a conductive material; the conductive material is selected from at least one of carbon fiber, conductive carbon black, graphene, carbon nanotubes, and graphite.

[0031] In some embodiments of the present invention, the mass ratio of the conductive material to the layered titanate is 1:(2~8); in some embodiments of the present invention, the mass ratio of the conductive material to the layered titanate is any value of 1:2, 1:3, 1:4, 1:5, 1:6, 1:7, 1:8 or a range formed by any two of them.

[0032] A fourth aspect of the present invention provides an electrical device comprising the electrolyte described in the first aspect of the present invention or the ammonium ion battery described in the third aspect of the present invention.

[0033] The beneficial effects of this invention are: the electrolyte of this invention uses choline chloride, sucrose and water to construct a hydrogen bond network with a specific structure, which significantly restricts the activity of free water molecules, inhibits the hydrogen evolution reaction at the negative electrode, broadens the stable working potential range of aqueous electrolytes, optimizes the ion transport kinetics of electrolytes, and ensures high ionic conductivity while inhibiting hydrogen evolution, thus matching the high-rate energy storage requirements.

[0034] The electrolyte preparation method of this invention is simple and easy to operate. The preparation process does not require high temperature and high pressure. It is simple to operate, low in cost, and easy to scale up, laying the foundation for the industrial application of water-based energy storage technology.

[0035] When the electrolyte in this invention is used in ammonium-ion batteries, it can be well matched with the layered titanate negative electrode of the battery. A stable interface is formed between the electrolyte and the negative electrode, reducing the working potential of the negative electrode, stimulating the intrinsic ammonium storage performance of the electrode material, and improving the specific capacity and cycle stability of the electrode material, thus providing a solution for the high performance of aqueous ammonium-ion batteries.

[0036] This invention optimizes the electrolyte formulation, enabling ammonium-ion batteries assembled with the electrolyte to achieve no hydrogen evolution at a low potential of -1.6 V vs. Ag / AgCl, maintain an electrode specific capacity of 172 mAh / g at an ultra-high rate of 50 A / g, and achieve stable cycling for more than 3000 cycles at a current density of 20 A / g, with a coulombic efficiency maintained at 96.5%. Attached Figure Description

[0037] Figure 1 The electrochemical window test diagrams are for the electrolytes in Example 1 and Comparative Example 1.

[0038] Figure 2 The CV test results are for the electrolytes of Example 1 and Comparative Example 1.

[0039] Figure 3 The CV test results are for the electrolytes in Examples 1-3.

[0040] Figure 4 The CV test results are for the electrolytes of Examples 1 and 4-5.

[0041] Figure 5 The image shows the cyclic voltammetry of the layered titanate nanomaterial electrode in the electrolyte of Example 1.

[0042] Figure 6 The graph shows the charge-discharge test results of the battery assembled using the electrolyte in Example 1 at different current densities.

[0043] Figure 7 This is a rate test graph of the battery assembled using the electrolyte from Example 1.

[0044] Figure 8 This is a rate test chart of the battery assembled using the electrolyte in Comparative Example 1.

[0045] Figure 9 This is a graph showing the long-cycle performance test of a battery assembled using the electrolyte from Example 1.

[0046] Figure 10The graph shows the long-cycle performance test results of the battery assembled using the electrolyte in Comparative Example 1.

[0047] Figure 11 The images show actual pictures of the electrolytes used in Example 1 and Comparative Examples 6-8.

[0048] Figure 12 The CV test results are shown for the electrolytes in Example 1 and Comparative Examples 6-7. Detailed Implementation

[0049] The specific implementation of the present invention will be further described in detail below with reference to the accompanying drawings and examples, but the implementation and protection of the present invention are not limited thereto. It should be noted that any processes not specifically described in detail below are those that can be implemented or understood by those skilled in the art by referring to the prior art. Reagents or instruments used without specified manufacturers are all conventional products that can be purchased commercially.

[0050] Example 1

[0051] This example provides an electrolyte composed of choline chloride, sucrose, ammonium acetate, and water. The molar concentration of ammonium acetate in the electrolyte is 1 mol / L, the molar concentration of choline chloride in the electrolyte is 2.4 mol / L, and the molar concentration of sucrose in the electrolyte is 0.6 mol / L.

[0052] The electrolyte in this example was prepared using the following method, with the specific steps as follows:

[0053] Dissolve 9.92 g of choline chloride and 6.08 g of sucrose together in 16 g of deionized water, stirring continuously until the solid is completely dissolved. After dissolution, add 2.3124 g of ammonium acetate and bring the volume to 30 mL. Sonicate the solution continuously until the solid is completely dissolved to obtain the electrolyte in this example.

[0054] Example 2

[0055] This example provides an electrolyte composed of choline chloride, sucrose, ammonium acetate, and water. The molar concentration of ammonium acetate in the electrolyte is 1 mol / L, the molar concentration of choline chloride in the electrolyte is 2.1 mol / L, and the molar concentration of sucrose in the electrolyte is 0.7 mol / L.

[0056] The electrolyte in this example was prepared using the following method, with the specific steps as follows:

[0057] Dissolve 8.8 g of choline chloride and 7.2 g of sucrose together in 16 g of deionized water, stirring continuously until the solid is completely dissolved. After dissolution, add 2.3124 g of ammonium acetate and bring the volume to 30 mL. Sonicate the solution continuously until the solid is completely dissolved to obtain the electrolyte in this example.

[0058] Example 3

[0059] This example provides an electrolyte composed of choline chloride, sucrose, ammonium acetate, and water. The molar concentration of ammonium acetate in the electrolyte is 1 mol / L, the molar concentration of choline chloride in the electrolyte is 2.6 mol / L, and the molar concentration of sucrose in the electrolyte is 0.5 mol / L.

[0060] The electrolyte in this example was prepared using the following method, with the specific steps as follows:

[0061] Dissolve 10.73 g of choline chloride and 5.27 g of sucrose together in 16 g of deionized water, stirring continuously until the solid is completely dissolved. After dissolution, add 2.6978 g of ammonium acetate and bring the volume to 30 mL. Sonicate the solution continuously until the solid is completely dissolved to obtain the electrolyte in this example.

[0062] Example 4

[0063] This example provides an electrolyte composed of choline chloride, sucrose, ammonium acetate, and water. The molar concentration of ammonium acetate in the electrolyte is 1 mol / L, the molar concentration of choline chloride in the electrolyte is 2.8 mol / L, and the molar concentration of sucrose in the electrolyte is 0.7 mol / L.

[0064] The electrolyte in this example was prepared using the following method, with the specific steps as follows:

[0065] Dissolve 9.92 g of choline chloride and 6.08 g of sucrose together in 10.64 g of deionized water, stirring continuously until the solid is completely dissolved. After dissolution, add 1.9265 g of ammonium acetate and bring the volume to 25 mL. Continue sonicating the solution until the solid is completely dissolved to obtain the electrolyte in this example.

[0066] Example 5

[0067] This example provides an electrolyte composed of choline chloride, sucrose, ammonium acetate, and water. The molar concentration of ammonium acetate in the electrolyte is 1 mol / L, the molar concentration of choline chloride in the electrolyte is 2 mol / L, and the molar concentration of sucrose in the electrolyte is 0.5 mol / L.

[0068] The electrolyte in this example was prepared using the following method, with the specific steps as follows:

[0069] Dissolve 9.92 g of choline chloride and 6.08 g of sucrose together in 24 g of deionized water, stirring continuously until the solid is completely dissolved. After dissolution, add 2.6978 g of ammonium acetate and bring the volume to 35 mL. Sonicate the solution continuously until the solid is completely dissolved to obtain the electrolyte in this example.

[0070] The electrolytes in Examples 1-5 of this invention are mainly used in ammonium-ion batteries. The negative electrode of an ammonium-ion battery is the ammonium storage material. The main bottleneck lies in the easy dissolution and structural instability of the positive electrode material, and the relatively low overall cell voltage. Therefore, the electrolyte design focuses more on stabilizing the positive electrode and widening the voltage window. NH4 + It diffuses quickly and typically has good low-temperature performance.

[0071] Comparative Example 1

[0072] This example provides an electrolyte, which is a 1 mol / L aqueous solution of ammonium acetate.

[0073] The electrolyte in this example was prepared using the following method, with the specific steps as follows:

[0074] Dissolve 1.5412 g of ammonium acetate in deionized water, bring the volume to 10 mL, and sonicate continuously until the solid is completely dissolved to obtain the electrolyte. The final electrolyte concentration is 1 mol L. -1 Ammonium acetate is denoted as 1M NH4Ac.

[0075] Comparative Example 2

[0076] This example provides an electrolyte composed of choline chloride, sucrose, ammonium acetate, and water; the molar concentration of ammonium acetate in the electrolyte is 1 mol / L, the molar concentration of choline chloride in the electrolyte is 0.9 mol / L, and the molar concentration of sucrose in the electrolyte is 2 mol / L.

[0077] Comparative Example 3

[0078] This example provides an electrolyte composed of choline chloride, sucrose, ammonium acetate, and water; the molar concentration of ammonium acetate in the electrolyte is 1 mol / L, the molar concentration of choline chloride in the electrolyte is 1.1 mol / L, and the molar concentration of sucrose in the electrolyte is 1.1 mol / L.

[0079] Comparative Example 4

[0080] This example provides an electrolyte composed of choline chloride, sucrose, ammonium acetate, and water; the molar concentration of ammonium acetate in the electrolyte is 1 mol / L, the molar concentration of choline chloride in the electrolyte is 1.6 mol / L, and the molar concentration of sucrose in the electrolyte is 1.6 mol / L.

[0081] Comparative Example 5

[0082] This example provides an electrolyte composed of choline chloride, sucrose, ammonium acetate, and water; the molar concentration of ammonium acetate in the electrolyte is 1 mol / L, the molar concentration of choline chloride in the electrolyte is 4 mol / L, and the molar concentration of sucrose in the electrolyte is 1 mol / L.

[0083] Comparative Example 6

[0084] The only difference between the electrolyte in this example and that in Example 1 is that maltose is used instead of sucrose in Example 1.

[0085] Comparative Example 7

[0086] The only difference between the electrolyte in this example and that in Example 1 is that choline bromide is used instead of choline chloride in Example 1.

[0087] Comparative Example 8

[0088] The only difference between the electrolyte in this example and that in Example 1 is that choline iodide is used instead of choline chloride in Example 1, and lactose is used instead of sucrose in Example 1.

[0089] Application examples

[0090] This example provides an aqueous ammonium ion half-cell, using layered titanate nanomaterials as the negative electrode, a graphite rod as the counter electrode, and Ag / AgCl as the reference electrode. The electrolyte can be any one of the electrolytes in Examples 1-5 and Comparative Examples 1-8 of this invention.

[0091] The aqueous ammonium ion half-cell in this example was prepared using the following method, with the specific steps as follows:

[0092] Step a) Preparation of layered titanate nanomaterials as electrode materials for aqueous ammonium-ion half-cells: In step a, the layered titanate nanomaterials are prepared by hydrothermal synthesis followed by washing with hydrochloric acid: 800 mg of TiO2 is slowly added to 80 mL of 8 mol / L NaOH solution, and the mixture is placed in a 100 mL reactor. After hydrothermal reaction at 130°C for 6 hours, the mixture is washed with hydrochloric acid and dried overnight at 80°C to obtain the layered titanate nanomaterials. Next, 5 mg of the layered titanate nanomaterials are mixed with 1 mg of Ketjen Black and 500 μL of naphthol solution, and then sonicated for 30 minutes to obtain a negative electrode slurry with a concentration of 10 mg / mL. 5 μL of the negative electrode slurry is drop-coated onto a cleaned surface with an area of ​​0.2 cm². 2 The glassy carbon electrode was dried with an infrared lamp to obtain a negative electrode with a material loading of 0.05 mg.

[0093] b. Place the electrolyte in a 50 mL electrolytic cell and treat the electrolyte with nitrogen gas for half an hour;

[0094] c. Place the negative electrode, counter electrode, and reference electrode in an electrolytic cell to assemble a battery, and then perform electrochemical tests.

[0095] Performance testing:

[0096] (1) Specific capacity test

[0097] The electrolytes from Examples 1-5 and Comparative Examples 2-5 were assembled into aqueous ammonium-ion half-cells according to the method in the application examples. Then, using the Chenhua electrochemical workstation, the multi-current step (GCD) program was selected, with a potential range of -1.6V to -0.5V. Charge-discharge tests were performed at current densities of 15A / g, 20A / g, 25A / g, 30A / g, 35A / g, 40A / g, 45A / g, and 50A / g, respectively. The specific test results are shown in Table 1 below.

[0098] Table 1 Specific Capacity Test

[0099]

[0100] In Table 1, "-" indicates that the specific capacity cannot be measured.

[0101] As shown in Table 1, compared to other examples and comparative examples, the half-cell assembled with the electrolyte prepared by optimizing the amounts of choline chloride, sucrose, and water in Example 1 exhibited the best performance, with the highest specific capacity at current densities of 20 A / g and 50 A / g, namely 207 mAh / g and 172 mAh / g, respectively. In Comparative Example 4, the high viscosity of the electrolyte led to a sharp decrease in ion migration rate, making it impossible to measure the specific capacity.

[0102] (2) Electrochemical window test

[0103] The electrolytes from Example 1 and Comparative Example 1 were placed in a 50 mL electrolytic cell and continuously purged with nitrogen for half an hour. A glassy carbon electrode was used as the working electrode, a platinum electrode as the counter electrode, and Ag / AgCl as the reference electrode. The electrolytic cells were placed under nitrogen purging. Using a Chenhua electrochemical workstation, the linear sweep voltammetry (LSV) program was selected, with a potential range of -2 V to 2 V. Specific test results are as follows: Figure 1 As shown, by Figure 1 It can be seen that the hydrogen evolution potential (i.e., E) of the pure ammonium acetate electrolyte in Comparative Example 1 is... HER The hydrogen evolution potential (E) of the mixed electrolyte in Example 1 is -1.22 V. HER The hydrogen evolution potential in Example 1 was -1.65 V, which is a negative shift compared to Comparative Example 1 (i.e., E).HER The voltage was greater than 0.4 V, which successfully suppressed hydrogen evolution, further demonstrating that the electrolyte in this invention can suppress hydrogen evolution in aqueous ammonium ion batteries, thereby improving electrochemical performance.

[0104] (3) CV curve test

[0105] The electrolytes from Examples 1-5 and Comparative Example 1 were placed in a 50 mL electrolytic cell and continuously purged with nitrogen for half an hour. 5 μL of the negative electrode slurry prepared in the application example was then drop-coated onto a surface with an area of ​​0.2 cm². 2 The glassy carbon electrode was dried with an infrared lamp at a loading of 0.05 mg. The dried glassy carbon electrode served as the working electrode, a graphite rod as the counter electrode, and Ag / AgCl as the reference electrode. The electrode was placed in a nitrogen-purged electrolytic cell, and cyclic voltammetry (CV) was performed using a Chenhua electrochemical workstation. The potential range was -1.6 V to -0.5 V, and the scan rate was 5 mV / s. The CV test results for the electrolytes of Example 1 and Comparative Example 1 are shown below. Figure 2 As shown, the CV test graphs of the electrolytes in Examples 1-3 are as follows. Figure 3 As shown, the CV test graphs of the electrolytes in Examples 1 and 4-5 are as follows. Figure 4 As shown. By Figure 2 It can be seen that the electrolyte in Example 1 brought out the original reduction peak of the material, greatly stimulating the performance of the negative electrode material, and significantly inhibiting hydrogen evolution. Figure 3 It can be seen that, compared with Examples 2-3, Example 1, by adjusting the molar ratio of choline chloride to sucrose to 4:1, has a better effect on suppressing hydrogen evolution. Compared with Comparative Example 1 and Examples 2-5, Example 1 has a larger CV peak area and obvious oxidation and reduction peaks, indicating that the half-cell assembled at this ratio has better electrochemical performance, better hydrogen evolution suppression effect, and higher specific capacity at different current densities.

[0106] Then, the cyclic voltammograms of the layered titanate nanomaterial electrode in the electrolyte of Example 1 were tested according to the above test method. The specific test results are as follows: Figure 5 As shown. By Figure 5 As can be seen, the layered titanate nanomaterials exhibit excellent comprehensive electrochemical performance in the electrolyte of Example 1: the voltammetric curves of 5 cycles almost completely overlap, and the peak shape, peak position and peak current of the oxidation peak and the reduction peak do not show significant attenuation, demonstrating excellent cycle stability. It can effectively suppress side reactions and reduce the loss of active materials, providing a solid guarantee for the long cycle life of the battery; the correspondence between the oxidation peak and the reduction peak is clear and the peak spacing is small, indicating that the ammonium ion insertion / extraction process has good electrochemical reversibility and excellent electron transfer and ion transport kinetics.

[0107] (4) Charge-discharge curve

[0108] The electrolyte from Example 1 was placed in a 50 mL electrolytic cell and continuously purged with nitrogen for half an hour. 5 μL of the negative electrode slurry prepared in the application example was then drop-coated onto a surface with an area of ​​0.2 cm². 2 The glassy carbon electrode was dried with an infrared lamp at a loading of 0.05 mg. The dried glassy carbon electrode served as the working electrode, a graphite rod as the counter electrode, and Ag / AgCl as the reference electrode. It was placed in a nitrogen-filled electrolytic cell. Using an Autolab workstation, charge-discharge tests were conducted at current densities of 15 A / g, 20 A / g, 25 A / g, 30 A / g, 35 A / g, 40 A / g, 45 A / g, and 50 A / g, respectively, within the potential range of -1.6 V to -0.5 V. Specific test results are shown below. Figure 6 As shown. By Figure 6 The specific capacities at current densities of 15 A / g, 20 A / g, 25 A / g, 30 A / g, 35 A / g, 40 A / g, 45 A / g, and 50 A / g are 209 mAh / g, 207 mAh / g, 202 mAh / g, 197 mAh / g, 191 mAh / g, 184 mAh / g, 178 mAh / g, and 172 mAh / g, respectively. These results indicate that the hydrogen evolution in the aqueous ammonium-ion battery is effectively suppressed under the action of this electrolyte, thereby greatly enhancing the intrinsic energy storage performance of the electrode material and achieving a high specific capacity.

[0109] (5) Ratio test

[0110] Take the electrolytes from Example 1 and Comparative Example 1 respectively and place them in a 50 mL electrolytic cell. Purge with nitrogen continuously for half an hour. Take 5 μL of the negative electrode slurry prepared in the application example and drop it onto a surface with an area of ​​0.2 cm². 2 The glassy carbon electrode was dried with an infrared lamp at a loading of 0.05 mg. The dried glassy carbon electrode served as the working electrode, a graphite rod as the counter electrode, and Ag / AgCl as the reference electrode. It was placed in a nitrogen-filled electrolytic cell. Using an Autolab workstation, charge-discharge tests were performed at current densities of 15 A / g, 20 A / g, 25 A / g, 30 A / g, 35 A / g, 40 A / g, 45 A / g, 50 A / g, and 15 A / g, with five cycles at each current density. Specific test results are shown below. Figures 7-8 As shown. By Figures 7-8It can be seen that the half-cell assembled with the electrolyte in Example 1 exhibits a high rate plateau, a gentle slope, and strong rebound, with stable charge and discharge, and an average coulombic efficiency of 98.2%. In contrast, the half-cell composed of pure ammonium acetate in Comparative Example 1 shows a significant small plateau in rate performance, with larger fluctuations, far less than that of Example 1. Therefore, under the same test conditions, the rate performance of the electrolyte in Example 1 is far superior to that of the pure ammonium acetate electrolyte in Comparative Example 1.

[0111] (6) Long-cycle performance test

[0112] Take the electrolytes from Example 1 and Comparative Example 1 respectively and place them in a 50 mL electrolytic cell. Purge with nitrogen continuously for half an hour. Take 5 μL of the negative electrode slurry prepared in the application example and drop it onto a surface with an area of ​​0.2 cm². 2 The glassy carbon electrode was dried using an infrared lamp with a loading of 0.05 mg. The dried glassy carbon electrode served as the working electrode, a graphite rod as the counter electrode, and Ag / AgCl as the reference electrode. It was placed in a nitrogen-filled electrolytic cell, and charge-discharge tests were performed using an Autolab workstation at a potential range of -1.6 V to -0.5 V and a current density of 20 A / g, for 3000 cycles. Specific test results are as follows: Figures 9-10 As shown. By Figures 9-10 It can be seen that the half-cell assembled with pure ammonium acetate in Comparative Example 1 retained less than 70% of its capacity after 99 cycles, while the half-cell assembled with the electrolyte in Example 1 retained 70% of its capacity after 3000 cycles, with a coulombic efficiency of 96.5%. The test results show that the electrolyte in Example 1 significantly improves the electrochemical performance and stability of the aqueous ammonium-ion battery. Combined with rate performance testing, it can be seen that the electrolyte in this embodiment effectively stimulates the intrinsic energy storage performance of the electrode material, successfully achieving synergistic optimization of high rate and long cycle life.

[0113] (7) Electrolyte appearance and CV curve;

[0114] During the preparation of the electrolytes in Examples 1 and Comparative Examples 6-8, it was found that the electrolyte in Comparative Example 8 did not dissolve even after stirring at 80°C for a long time. Actual images of the electrolytes in Examples 1 and Comparative Examples 6-8 are shown below. Figure 11 As shown. The electrolyte in Comparative Example 8 could not be used for electrochemical testing because it was not fully dissolved.

[0115] The electrolytes from Example 1 and Comparative Examples 6-7 were placed in 50 mL electrolytic cells and continuously purged with nitrogen for half an hour before use. Using the negative electrode slurry prepared in the application examples, 5 μL of the slurry was drop-coated onto a surface with an area of ​​0.2 cm². 2The glassy carbon electrode was dried using an infrared lamp with a loading of 0.05 mg. The dried glassy carbon electrode served as the working electrode, a graphite rod as the counter electrode, and Ag / AgCl as the reference electrode. The electrode was placed in a nitrogen-purged electrolytic cell, and cyclic voltammetry (CV) was performed using a Chenhua electrochemical workstation. The potential range was -1.6 V to -0.5 V, and the scan rate was 5 mV / s. Specific test results are shown below. Figure 12 As shown. By Figure 12 It can be seen that the electrolyte of the present invention has a significantly larger peak area and the smallest potential difference between the oxidation peak and the reduction peak, indicating better electrochemical performance.

[0116] The electrolytes from Examples 1-5 and Comparative Examples 6-7 were assembled into aqueous ammonium ion half-cells according to the method in the application examples. Then, using the Chenhua electrochemical workstation, the multi-current step (GCD) program was selected, with a potential range of -1.6V to -0.5V, and charge-discharge tests were performed at current densities of 20A / g and 50 A / g, respectively. The specific test results are shown in Table 2 below.

[0117] Table 2. Specific capacity test results of Example 1 and Comparative Examples 6-7

[0118]

[0119] As shown in Table 2, the specific capacity of the electrolyte in Example 1 of the present invention at 20 A / g and 50 A / g is much higher than that of the electrolyte in Comparative Examples 6-7, further indicating that sucrose and choline chloride in the present invention have a synergistic effect.

[0120] In summary, this invention solves the hydrogen evolution problem commonly found in aqueous ammonium-ion batteries by introducing choline chloride and sucrose into the electrolyte. Choline chloride and sucrose form hydrogen bond donor-acceptor units, synergistically constructing a multi-component hydrogen-bonded cross-linked aqueous network with water. This network uses water as the continuous phase, with the Cl element of choline chloride forming directional cross-linking nodes with the hydroxyl groups of sucrose. Water molecules act as hydrogen bond bridging agents, bridging the nodes and maintaining the fluidity of the electrolyte while simultaneously binding free water and optimizing NH4+ through the network. + The solvated sheath layer ultimately achieves low potential stability and high-rate ammonium storage performance.

[0121] The embodiments of the present invention have been described in detail above. However, the present invention is not limited to the above embodiments. Within the scope of knowledge possessed by those skilled in the art, various changes can be made without departing from the spirit of the present invention. Furthermore, the embodiments of the present invention and the features thereof can be combined with each other unless otherwise specified.

Claims

1. An electrolyte, characterized in that: The electrolyte comprises ammonium salt, choline chloride, sucrose, and water; the molar ratio of choline chloride to sucrose is (3~6):1; the mass of water is 40~60% of the total mass of the electrolyte. The molar concentration of choline chloride in the electrolyte is 1.9~3 mol / L; The molar concentration of sucrose in the electrolyte is 0.4~0.8 mol / L; The molar concentration of the ammonium salt in the electrolyte is 0.5~3 mol / L.

2. The electrolyte according to claim 1, characterized in that: The ammonium salt is selected from at least one of ammonium chloride, ammonium sulfate, ammonium nitrate, ammonium nitrite, ammonium acetate, ammonium phosphate, ammonium carbonate, and ammonium aminosulfonate.

3. The method for preparing the electrolyte according to any one of claims 1 to 2, characterized in that: Includes the following steps: The product is prepared by mixing raw materials including ammonium salt, choline chloride, sucrose and water.

4. An aqueous ammonium-ion battery, characterized in that: Includes the electrolyte as described in any one of claims 1 to 2.

5. The aqueous ammonium-ion battery according to claim 4, characterized in that: The negative electrode of the aqueous ammonium ion battery contains layered titanate.

6. The aqueous ammonium-ion battery according to claim 5, characterized in that: The layered titanate is prepared by mixing titanium dioxide and alkaline solution and then carrying out a hydrothermal reaction.

7. The aqueous ammonium-ion battery according to claim 5, characterized in that: The negative electrode of the aqueous ammonium ion battery also contains a conductive material; the conductive material is selected from at least one of carbon fiber, conductive carbon black, graphene, carbon nanotubes, and graphite.

8. An electrical appliance, characterized in that: The electrical equipment contains the electrolyte according to any one of claims 1 to 2 or the aqueous ammonium ion battery according to any one of claims 4 to 7.

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