Aqueous secondary ion battery

Abstract

The application provides a water-based secondary ion battery. The water-based secondary ion battery comprises a positive electrode material; the positive electrode material at least comprises a positive electrode active material, the positive electrode active material comprises a first active material and a carrier, the first active material is selected from an alkali metal halide or an alkali metal sulfite, an alkaline earth metal halide or an alkaline earth metal sulfite, an aluminum halide or an aluminum sulfite, or a zinc halide or a zinc sulfite; the carrier has a low-dimensional structure; and the carrier is selected from a template and / or a second active material. The first active material of the positive electrode material has a lower molecular weight and a higher redox potential, so that the water-based secondary ion battery has a higher specific capacity and voltage. Meanwhile, the secondary ion battery adopts a water-based electrolyte, has high safety, and has a wide application prospect.

Description

Technical Field

[0001] This invention relates to the field of battery technology, and specifically to an aqueous secondary ion battery. Background Technology

[0002] Current lithium-ion battery development meets the needs of applications ranging from 3C electronics, power tools and automobiles to grid-scale energy storage. Lithium-ion battery systems based on lithium iron phosphate, ternary lithium, lithium cobalt oxide, and lithium-rich manganese-based cathode materials satisfy most current application scenarios. However, in the foreseeable future, the abundance of lithium and the cost of existing electrode materials will significantly limit the development of lithium-ion batteries. Therefore, there is an urgent need to develop high-performance, low-cost electrode materials to meet the ever-increasing energy demands.

[0003] Although lithium / sodium-ion batteries are widely regarded as an ideal energy storage technology for the future, their large-scale application is still greatly limited due to their low safety. For example, current commercial battery systems mainly rely on organic electrolytes, which leads to significant safety hazards such as combustion or even explosion when batteries malfunction.

[0004] In comparison, aqueous metal-ion batteries offer advantages such as high safety, high rate performance, low cost, and environmental friendliness, making them promising candidates for large-scale energy storage and portable devices. However, existing aqueous cathode materials suffer from low energy density and poor cycle stability, failing to meet industrialization requirements. Therefore, there is an urgent need to develop a cathode material system for aqueous batteries. Summary of the Invention

[0005] To address the aforementioned problems, this invention provides an aqueous secondary ion battery. By incorporating a positive electrode material containing a halogen salt or sulfite with a low-dimensional structure, a stable charge-discharge secondary ion battery system is constructed, resulting in a secondary ion battery exhibiting long-term stable charge-discharge performance.

[0006] The objective of this invention is achieved through the following technical solution:

[0007] An aqueous secondary ion battery includes a positive electrode material; the positive electrode material includes at least a positive electrode active material, the positive electrode active material comprising a first active material and a carrier.

[0008] The first active substance is selected from alkali metal halide salts or alkali metal sulfites, alkaline earth metal halide salts or alkaline earth metal sulfites, aluminum halides or aluminum sulfites, or zinc halides or zinc sulfites.

[0009] and a carrier, wherein the carrier has a low-dimensional structure; the carrier is selected from a template and / or a second active substance.

[0010] According to the present invention, in the positive electrode material, the first active material can be uniformly distributed on the support or in the low-dimensional structure of the support.

[0011] According to the present invention, the low-dimensional structure includes at least one of zero-dimensional structure, one-dimensional structure, two-dimensional structure, three-dimensional structure, and multi-level structure.

[0012] According to the present invention, the low-dimensional structure may include a crystalline structure or an amorphous structure. In the present invention, the low-dimensional structure refers to a structure whose smallest structural unit has a size not greater than 1 μm in at least one dimension, for example, 1 nm to 100 nm.

[0013] According to the present invention, the template has a zero-dimensional structure, a one-dimensional structure, a two-dimensional structure, a three-dimensional structure, or a multi-level structure. The multi-level structure mentioned in the present invention refers to a structure including one of the following: a zero-dimensional structure, a one-dimensional structure, a two-dimensional structure, or a three-dimensional structure.

[0014] According to the present invention, the second active substance has a zero-dimensional structure, a one-dimensional structure, a two-dimensional structure, a three-dimensional structure, or a multi-level structure.

[0015] For example, the zero-dimensional structure template is selected from at least one of quantum dots, nanoparticles, etc.

[0016] For example, the one-dimensional structural template is selected from at least one of nanowires, nanotubes, nanoribbons, etc.

[0017] For example, the two-dimensional structure template is selected from at least one nanosheet, including but not limited to graphene, carbonitride, Mxene, TiO2 nanosheets, etc.

[0018] For example, the three-dimensional structure template is prepared by at least one of the zero-dimensional structure template, one-dimensional structure template, and two-dimensional structure template, such as by stacking formation, assembly formation, automatic coating formation, and solution self-aggregation formation.

[0019] For example, the multi-level structure template is, for instance, a material that has a low-dimensional structure itself or is composed of a material that has a low-dimensional structure, selected from, but not limited to, at least one of activated carbon, metal-organic framework materials, covalent organic framework materials, alumina templates, metal foams, and microfabrication to prepare micro- and nanostructures.

[0020] It should be noted that the present invention reduces the dimensionality of the first active material or disrupts or changes its crystal morphology through the carrier, thereby obtaining a cathode material with high specific energy and high voltage, especially a cathode material containing halogen salts or sulfites.

[0021] According to the present invention, the cathode material is at least partially low-dimensional in structure.

[0022] In this embodiment, at least some of the halide salts or sulfites in the cathode material have a low-dimensional structure.

[0023] According to the present invention, the carrier is preferably selected from templates, and optionally includes or excludes a second active substance.

[0024] According to the present invention, the second active material is selected from at least one of the positive electrode active materials known in the art, preferably at least one of manganese oxide, Prussian blue sodium manganese oxide, Prussian blue sodium analog, polyanionic compound, conductive polymer, and organic material, such as at least one of LiMn2O4, MnO2, Li3V2(PO4)3 Prussian blue active material, LiFePO4, or ternary material.

[0025] Preferably, the second active material comprises nanoparticles, and further, the nanoparticles may form microspheres. It should be noted that, in this invention, a microsphere refers to a microsphere structure composed of multiple nanoparticles with a size reaching the micrometer scale. For example, the particle size of the microsphere is not less than 0.1 μm, such as 0.1-100 μm, 0.1-10 μm, or 0.1-1 μm.

[0026] It should be noted that the present invention does not specifically limit the form of the template. The form of the template can be selected from any form such as dispersion, foam, assembled membrane, powder, slurry, gel, etc., for example, foam. In the present invention, the template being in gel form means that a gel-shaped carrier is obtained by adding a known gelling substance (such as a polymer or small organic molecule), and then the first active substance is adsorbed and deposited therein to obtain the above-mentioned positive electrode material.

[0027] According to the present invention, the alkali metal halide salt is selected from at least one of lithium chloride, lithium bromide, lithium iodide, sodium chloride, sodium bromide, sodium iodide, potassium chloride, potassium bromide, and potassium iodide.

[0028] According to the present invention, the alkali metal sulfite is selected from at least one of lithium sulfite, sodium sulfite, and potassium sulfite.

[0029] According to the present invention, the alkaline earth metal halide salt is selected from at least one of magnesium chloride, magnesium bromide, magnesium iodide, calcium chloride, calcium bromide, and calcium iodide.

[0030] According to the present invention, the alkaline earth metal sulfite is selected from magnesium sulfite and / or calcium sulfite.

[0031] According to the present invention, the aluminum halide is selected from at least one of aluminum chloride, aluminum bromide, and aluminum iodide.

[0032] According to the present invention, the aluminum sulfite is selected from aluminum sulfite.

[0033] According to the present invention, the zinc halide is selected from at least one of zinc chloride, zinc bromide, zinc iodide, zinc sulfite, etc.

[0034] According to the present invention, the zinc sulfite is selected from zinc sulfite.

[0035] According to the present invention, in the positive electrode material, the first active material accounts for 1-99% of the total mass of the positive electrode material, preferably 5-90%, for example 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, or 90%.

[0036] According to the present invention, in the positive electrode material, the carrier accounts for 0-99% of the total mass of the positive electrode material, preferably 0.1-99%, more preferably 1-95%, and even more preferably 5-90%, for example 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, and 90%.

[0037] It should be noted that the present invention does not specifically limit the mass ratio of the template and the second active substance in the carrier. The carrier can be obtained by using a mass ratio known in the art, as long as the above-mentioned positive electrode material can be obtained. For example, in the carrier, the mass ratio of the template and the second active substance is (0.1-1):(0-10), such as (0.1-1):0.1, (0.1-1):0.2, (0.1-1):0.3, (0.1-1):0.4, (0.1-1):0.5, (0.1-1):0.6, (0.1-1):0.7, (0.1-1):0.8, (0.1-1):0.9, (0.1-1):1, (0.1-1):2, (0.1-1):3, (0.1-1):4, (0.1-1):5, (0.1-1):6, (0.1-1):7, (0.1-1):8, (0.1-1):8, (0.1-1):10.

[0038] According to the present invention, the first active material has a low-dimensional structure or a micro / nanocrystalline structure.

[0039] According to the present invention, in the positive electrode material, when the first active material is distributed in the low-dimensional structure, the first active material has a low-dimensional structure, and the low-dimensional structure has the meaning as described above.

[0040] For example, the halide salt in the cathode material is selected from KBr, wherein the KBr portion has a low-dimensional structure, such as a low-dimensional structure composed of nanoparticles with a particle size of 1-100 nm.

[0041] According to the present invention, when the first active substance is distributed on the carrier, the first active substance constitutes micro / nano crystals.

[0042] Preferably, the particle size range of the micro / nano crystals is 0.1-5μm, more preferably 0.5-5μm, for example 1μm, 2μm, 3μm, 4μm, 5μm.

[0043] The inventors have discovered that the lower the content of micro / nano crystallites in the cathode material, the better the battery performance. Therefore, according to a preferred embodiment of the present invention, the content of low-dimensional structures in the first active material is higher than the content of micro / nano crystallites.

[0044] It should be noted that during battery charging and discharging, the low-dimensional structures and / or micro / nano crystals in the first active material will partially dissolve in the electrolyte, or precipitate from the electrolyte and reform low-dimensional structures and / or micro / nano crystals on the carrier. As the battery charging and discharging process continues, the micro / nano crystals will dissolve into the electrolyte as a supplement, and then deposit on the carrier surface to form low-dimensional active materials, thereby ensuring stable battery operation.

[0045] According to the present invention, the cathode material can also be processed by methods known in the art, such as carbonization, elution and other known methods, to obtain a cathode material that almost does not contain a template.

[0046] According to an exemplary embodiment of the present invention, the positive electrode material comprises a first active material and a support; the support comprises a second active material; the first active material and the second active material are composited to form the positive electrode material. For example, the first active material fills the pores of nanoparticles or microspheres of the second active material to form the positive electrode material.

[0047] According to the present invention, the aqueous secondary ion battery further includes a negative electrode material, wherein the negative electrode material is selected from carbon-based negative electrode materials.

[0048] According to the present invention, the carbon-based anode material can be a commercially available material or a material synthesized in-house. Exemplarily, the carbon-based anode material is selected from at least one of activated carbon, graphite, hard carbon, soft carbon, etc.

[0049] According to the present invention, the carbon-based anode material further includes a metallic element. Preferably, the metallic element is selected from at least one of magnesium, aluminum, and zinc.

[0050] According to the present invention, the aqueous secondary ion battery further includes an electrolyte or a gel electrolyte.

[0051] According to the present invention, the electrolyte is selected from aqueous electrolytes.

[0052] According to the present invention, the aqueous electrolyte comprises an electrolyte and an aqueous solvent.

[0053] According to the present invention, in the aqueous electrolyte, the electrolyte is selected from, but not limited to, at least one of lithium salt, sodium salt, potassium salt, magnesium salt, calcium salt, aluminum salt, and zinc salt.

[0054] For example, the lithium salt is selected from at least one of lithium sulfate, lithium nitrate, lithium acetate, lithium perchlorate, lithium chloride, lithium difluorosulfonate imine (LiFSI), lithium trifluoromethanesulfonate (LiOTf), lithium bis(trifluoromethanesulfonate)imine, and lithium bis(pentafluoroethylsulfonyl)imine.

[0055] For example, the sodium salt is selected from at least one of sodium perchlorate, sodium acetate, sodium nitrate, sodium chloride, sodium sulfate, sodium difluorosulfonate imine (NaFSI), sodium trifluoromethanesulfonate, sodium bis(trifluoromethanesulfonate)imine, and sodium bis(pentafluoroethylsulfonyl)imino.

[0056] For example, the potassium salt is selected from at least one of potassium nitrate, potassium acetate, potassium sulfate, potassium chloride, potassium difluorosulfonate imine (KFSI), potassium trifluoromethanesulfonate, potassium bis(trifluoromethanesulfonate)imine, and potassium bis(pentafluoroethylsulfonyl)imine.

[0057] For example, the zinc salt is selected from at least one of zinc trifluoromethanesulfonate, zinc sulfate, zinc chloride, zinc acetate, zinc trifluoromethanesulfonate, and zinc bis(trifluoromethanesulfonyl)imide (Zn(TFSI)2).

[0058] For example, the magnesium salt is selected from at least one of magnesium trifluoromethanesulfonate, magnesium sulfate, magnesium chloride, magnesium acetate, and magnesium bis(trifluoromethanesulfonyl)imide.

[0059] According to the present invention, the concentration of the electrolyte in the aqueous electrolyte is greater than or equal to 1-100 mol / L, preferably 5-70 mol / L, for example 5 mol / L, 10 mol / L, 20 mol / L, 30 mol / L, 40 mol / L, 50 mol / L, 60 mol / L, 70 mol / L, or 100 mol / L.

[0060] According to the present invention, the aqueous gel electrolyte comprises a first polymer host material and an electrolyte, wherein the electrolyte is selected from the aqueous electrolyte.

[0061] Preferably, the first polymer host material is selected from at least one of polyvinyl alcohol (PVA), polyacrylic acid, polyacrylamide, sodium polyacrylate, polyethylene oxide (PEO), polymethyl methacrylate, polyether ether ketone, ethylene glycol acrylonitrile block copolymer, and poly(vinylidene fluoride-hexafluoropropylene) (PVDF-HFP).

[0062] For example, the aqueous electrolyte is K(FSI). 0.55 (OTf) 0.45 • 0.9H2O aqueous electrolyte.

[0063] According to the present invention, the aqueous secondary ion battery has good cycle performance and high energy density.

[0064] For example, at 500mA g -1 At a given current density, the aqueous secondary ion battery retains more than 95% of its capacity after 100 charge-discharge cycles, for example, 95-99.9%.

[0065] For example, at 500mA g -1 At a given current density, the aqueous secondary ion battery retains more than 95% of its capacity after 300 charge-discharge cycles, for example, 95-99.9%.

[0066] For example, at 500mA g -1 At a given current density, the aqueous secondary ion battery retains a capacity of over 86% after 500 charge-discharge cycles, for example, 86-99.9%, or even 87-95%.

[0067] For example, at 500mA g -1 At a given current density, the aqueous secondary ion battery retains a capacity of over 87% after 600 charge-discharge cycles, for example, 87-99.9%, or even 87-95%.

[0068] For example, at 500mA g -1 At a given current density, the aqueous secondary ion battery retains a capacity of over 82% after 1000 charge-discharge cycles, for example, 82-99.9%, or even 82-95%.

[0069] In this invention, the secondary ion battery can be assembled using methods known in the art.

[0070] For example, the preparation method of the secondary ion battery includes: using the above-mentioned positive electrode sheet as the positive electrode, using activated carbon as the negative electrode, and using 62 mol / kg K(FSI) 0.55 (OTf) 0.45 • An aqueous solution of 0.9H2O is used as the electrolyte in an aqueous battery.

[0071] Beneficial effects:

[0072] The aqueous secondary ion battery prepared using the cathode material of this invention comprises a first active material consisting of a low-dimensional structure and micro / nanocrystalline particles. The low-dimensional structure primarily provides capacity. During the charge-discharge process, the low-dimensional structure and / or micro / nanocrystalline particles in the first active material partially dissolve in the electrolyte or precipitate from the electrolyte and reform onto the carrier. As the battery charges and discharges, the micro / nanocrystalline particles dissolve into the electrolyte as a supplement and then deposit on the carrier surface to form the first active material with a low-dimensional structure, thereby ensuring stable battery operation. Because the first active material of this cathode material has a low molecular weight and a high redox potential, the aqueous secondary ion battery of this invention has a high specific capacity and voltage, thus providing a high energy density. The secondary ion battery of this invention uses an aqueous electrolyte, offering high safety and broad application prospects.

[0073] The aqueous secondary battery of the present invention improves the energy density and cycle stability of the aqueous positive electrode material by controlling the high concentration of electrolyte and combining it with the positive electrode material described in the present invention, thereby meeting the industrialization requirements of aqueous secondary batteries. Attached Figure Description

[0074] Figure 1 The image shows the microstructure of the KBr / rGO / AC cathode in Example 1; where (a) is a scanning electron microscope image; and (bd) is an energy dispersive spectroscopy (EDS) analysis.

[0075] Figure 2 The charge-discharge curves of the aqueous battery in Example 1 are shown.

[0076] Figure 3 The graph shows the cycle performance of the aqueous battery in Example 1 after 500 charge-discharge cycles.

[0077] Figure 4 The graph shows the cycle performance of the aqueous gel battery of Example 3 after 100 charge-discharge cycles.

[0078] Figure 5 The graph shows the cycle performance of the aqueous battery in Comparative Example 1 after 100 charge-discharge cycles.

[0079] Figure 6 The graph shows the cycle performance of the aqueous battery in Comparative Example 2 after 20 charge-discharge cycles. Detailed Implementation

[0080] The present invention also provides a method for preparing the above-mentioned cathode material, the method comprising: mixing the carrier and the first active substance, and then compounding them to obtain the cathode material of the present invention, wherein the carrier and the first active substance have the meanings described above.

[0081] Preferably, when the carrier is selected from a template and optionally includes or excludes a second active substance, the mixing comprises:

[0082] First, mix the template and the first active substance, then add the second active substance; or,

[0083] First, mix the template and the second active substance, then add the first active substance; or,

[0084] First, mix the second active substance and the first active substance, and then add the template.

[0085] According to the present invention, the preparation method further includes, after composite, the cathode material is optionally treated by any one of the following methods: high-temperature carbonization or elution.

[0086] According to the present invention, in the preparation method, the carrier can be pretreated to obtain the desired form. Preferably, the carrier is pretreated to obtain any form such as dispersion, foam, assembled film, powder, slurry, etc., for example, foam.

[0087] According to the present invention, the high-temperature carbonization specifically includes: carbonizing the positive electrode material at a high temperature of 400-1000°C, for example, carbonizing at a high temperature of 700°C. Exemplarily, the carbonization time is 1-10 hours, for example, 4 hours.

[0088] According to an exemplary embodiment of the present invention, the method for preparing the positive electrode material includes the following steps:

[0089] (1) The carrier is ultrasonically dispersed in water to obtain a mixture, and the mixture is frozen to obtain foam;

[0090] (2) After compacting the foam from step (1), add a solution containing the first active substance to the compacted foam, and let it dry to obtain the cathode material precursor.

[0091] (3) The cathode material precursor obtained in step (2) is carbonized at high temperature to obtain the above cathode material.

[0092] According to the present invention, the carrier and the first active substance have the definitions described above.

[0093] According to the present invention, the mass concentration of the carrier in the mixture is 1-100 mg / g, for example, 10 mg / g.

[0094] According to the present invention, the freezing includes: a first freezing and a second freezing.

[0095] Preferably, the conditions for the first freezing include freezing at -70 to -100°C for at least 1 hour, preferably 1 to 10 hours, for example freezing at -80°C for 2 hours.

[0096] Preferably, the conditions for the second freezing include: freeze-drying at -40 to -70°C for at least 10 hours, preferably 10 to 100 hours, for example, freeze-drying at -60°C for 40 hours.

[0097] Preferably, step (2) may optionally include slicing the compacted foam. In this invention, slicing refers to cutting the compacted foam into arbitrary sizes to meet the application requirements of the cathode material. For example, the sizes can be circular, square, or irregular in shape. For instance, slicing the compacted foam yields circular slices with a diameter of 11 mm.

[0098] Preferably, the solution containing the first active substance comprises the first active substance and a solvent. Preferably, the solvent is selected from volatile solvents, such as methanol, ethanol, acetone, and dichloromethane. Exemplarily, the solution containing the first active substance is selected from potassium iodide methanol solution.

[0099] Preferably, in the solution containing the first active substance, the mass concentration of the first active substance is 0.01-10 g / mL, for example, 0.1 g / mL.

[0100] According to the present invention, the elution specifically includes: adding the positive electrode material to the eluent to remove all or part of the template.

[0101] Preferably, the eluent is selected from concentrated acids or concentrated bases. For example, the concentrated acid is selected from concentrated hydrochloric acid.

[0102] According to an exemplary embodiment of the present invention, the method for preparing the positive electrode material includes the following steps:

[0103] (1) The first active substance and the carrier are ultrasonically dispersed in a solvent to obtain a mixture, which is then dried to obtain a solid material;

[0104] (2) Add the solid material from step (1) to the eluent to remove all or part of the template and obtain an intermediate;

[0105] (3) After the intermediate in step (2) is dried, the cathode material is obtained.

[0106] Preferably, the drying can be carried out using methods known in the art, such as vacuum drying at 90°C for 6 hours.

[0107] The present invention will be further described in detail below with reference to specific embodiments. It should be understood that the following embodiments are merely illustrative and explanatory of the present invention and should not be construed as limiting the scope of protection of the present invention. All technologies implemented based on the above content of the present invention are covered within the scope of protection intended by the present invention.

[0108] Unless otherwise specified, the experimental methods used in the following examples are conventional methods; unless otherwise specified, the reagents and materials used in the following examples are commercially available.

[0109] Unless otherwise specified, the battery electrical performance tests in the following embodiments were all conducted at 25°C.

[0110] Example 1

[0111] 1. Preparation of positive electrode material: (1) The aqueous dispersion containing graphene oxide (GO, 3 mg / g) and activated carbon (AC, 7 mg / g) was ultrasonically dispersed for 2 hours to obtain a mixed solution. Then, 5 mL of the mixed solution was added to a petri dish with a diameter of 3.5 cm and frozen in a low temperature freezer at -80℃ for 2 hours. After that, it was freeze-dried at -60℃ for 40 hours to obtain GO / AC foam.

[0112] (2) After compacting the GO / AC foam, punch it into a circular sheet with a diameter of 11 mm using a puncher. Then, add 200 μL of potassium bromide methanol solution (25 mg / mL) to each circular sheet and place it in a fume hood for 48 hours to allow the methanol to evaporate completely.

[0113] (3) The KBr / GO / AC sample obtained in step (3) is carbonized at high temperature in a tube furnace at 700℃ for 4 hours to obtain KBr / reduced graphene oxide (rGO) / AC, which is the positive electrode.

[0114] Figure 1 The microstructure of the KBr / rGO / AC cathode in Example 3 is shown. Figure 2 The scanning electron microscope images and energy dispersive spectroscopy analysis show that KBr is relatively uniformly distributed throughout the foam, and the average particle size of the KBr micron grains is 1 μm.

[0115] 2. Preparation of an aqueous battery: Using the above-mentioned KBr / rGO / AC positive electrode as the positive electrode and activated carbon as the negative electrode, 62 mol / kg K(FSI) 0.55 (OTf) 0.45 A 0.9H₂O aqueous solution was used as the electrolyte, and a full cell was assembled using glass fiber as the separator. The positive electrode contained 2 mg of KBr and 12 mg of activated carbon.

[0116] Figure 2 The aqueous battery of Example 1 was tested at 500 mA g.-1 The charge-discharge curves at the specified current density show that the battery, when charged to 2.5V and discharged to 0.1V, has a discharge specific capacity of 150mAh g. -1 .

[0117] Figure 3 The graph shows the cycle performance of the aqueous battery of Example 1 after 500 charge-discharge cycles. The battery operates at 500 mA g. -1 After 500 charge-discharge cycles at a current density, it retains 86% of its capacity.

[0118] Example 2

[0119] 1. Preparation of cathode material: The preparation method of cathode material in this embodiment is the same as in Example 1, except that: in step (2), a mixed solution of potassium sulfite and water and methanol (0.1 g / mL) is added dropwise to the circular sheet; in step (3), the K2SO3 / GO / AC sample is carbonized at high temperature in a tube furnace at 500℃ for 4 hours to prepare K2SO3 / rGO / AC cathode sheet, wherein the average particle size of K2SO3 micron grains is 3 μm. Elemental analysis shows that the mass fraction of K2SO3 in the K2SO3 / rGO / AC cathode sheet is 45%.

[0120] 2. Preparation of an aqueous battery: The preparation method in this embodiment is the same as in Example 1, except that the positive electrode is a K2SO3 / rGO / AC material, wherein the mass of the active material K2SO3 in the positive electrode is 2 mg. This battery operates at 500 mA g -1 After 1000 charge-discharge cycles at a current density, it still retains 82% of its capacity.

[0121] Example 3

[0122] 1. Preparation of cathode material: The preparation method in this embodiment is the same as in Example 1, except that in step (2), a NaI methanol solution NaI / rGO / AC cathode is dropped onto a circular sheet, wherein the average particle size of the NaI micron-sized grains is 1 μm. Elemental analysis shows that the mass fraction of NaI in the cathode is 48%.

[0123] 2. Preparation method of hydrogel electrolyte: 0.05 mol NaClO4 and 5 g polyvinyl alcohol (PVA) were added to 5 mL of deionized water and stirred at room temperature for 20 min. Then, the mixture was heated to 95 °C and stirred continuously for 2 h to obtain a homogeneous gel solution. The solution was then poured into a 6 cm diameter petri dish and placed in a -20 °C refrigerator for 4 h to allow it to solidify, resulting in a PVA-NaClO4 gel. The gel was then punched into sheets with a diameter of 16 mm for later use.

[0124] Assemble the full cell: Using the above-mentioned NaI / rGO / AC positive electrode as the positive electrode, activated carbon as the negative electrode, and PVA-NaClO4 as the gel electrolyte, the full cell is assembled.

[0125] Figure 4 The full cell of Example 3 at 500 mA g -1 The cycle performance graph after 100 charge-discharge cycles at a current density, from Figure 4 It can be seen that the capacity retention rate is as high as 95% after 100 charge-discharge cycles.

[0126] Example 4: Addition of a second active material

[0127] 1. Preparation of cathode material: (1) 0.5g of lithium iron phosphate (LiFePO4, the second active material) with micron-sized sphere microstructure was added to 2mL of 0.1g / mL NaBr (the first active material) methanol solution and stirred magnetically for 12h. Then the mixture was placed in a fume hood until the methanol was completely evaporated. After that, it was dried in a blast oven at 90℃ for 6h. Then the dried solid was ground for later use. In this way, NaBr can fill the pores of LiFePO4 microspheres to form a composite cathode material (LiFePO4 / NaBr).

[0128] (2) Take 0.5g of the above LiFePO4 / NaBr material, mix it into a slurry according to the ratio of 8:1:1 (LiFePO4 / NaBr: conductive carbon black: PVDF), then coat it on the aluminum foil current collector and dry it, and make it into a positive electrode sheet with a diameter of 11 mm for later use. The mass of the positive electrode active material NaBr is 1.0mg and the mass of LiFePO4 is 2.5mg.

[0129] 2. Preparation of an aqueous battery: An aqueous battery was assembled using the above-mentioned positive electrode as the positive electrode, metal activated carbon as the negative electrode, 17 mol / L NaClO4 aqueous solution as the electrolyte, and glass fiber as the separator. This battery achieved a 500 mA g... -1 After 300 charge-discharge cycles at a current density, the capacity retention rate is still as high as 95.4%.

[0130] Example 5: Washing off the template

[0131] 1. Preparation of cathode material: (1) 0.1g TiO2 nanosheets were added to 100mL of 0.01g / mL NaCl methanol and aqueous solution (mixed at a mass ratio of 1:1) and magnetically stirred for 12h. Then the dispersion was heated to 50℃ until the solvent was completely evaporated. Due to electrostatic interaction, NaCl was partially deposited uniformly on the surface of TiO2 nanosheets in the form of nanoparticles. Then the solid was dried in a blast oven at 90℃ for 6h to obtain a solid. Then the dried solid was added to concentrated hydrochloric acid. Since TiO2 nanosheets are soluble in concentrated hydrochloric acid while NaCl is insoluble, the template can be etched away, thus retaining only the low-dimensional structure of NaCl. This template removal process does not damage the structure of NaCl, which still partially presents a nanoparticle state, thus solving the problem that NaCl crystals themselves are difficult to release capacity. After removing the template, the obtained NaCl solid was vacuum dried at 90℃ for 6h, and then the dried solid was ground for later use.

[0132] (2) Repeat step (1) multiple times to obtain 0.5g of the above NaCl solid, mix it into a slurry according to the ratio of 8:1:1 (NaCl: conductive carbon black: PVDF), then coat it on the aluminum foil current collector and dry it, and make it into a sheet with a diameter of 11 mm for later use.

[0133] 2. Preparation of an aqueous battery: Using NaCl as the positive electrode, activated carbon as the negative electrode, and PVA-NaClO4 as the gel electrolyte from Example 3, a full battery was assembled. The mass of the positive electrode active material NaCl was 2.0 mg. This battery achieved a speed of 500 mAg. -1 After 600 charge-discharge cycles at a current density, the capacity retention rate is still as high as 87%.

[0134] Comparative Example 1

[0135] 1. Preparation of potassium bromide positive electrode: Potassium bromide (analytical grade), conductive carbon black and PVDF are mixed in a mass ratio of 8:1:1 to form a slurry, which is then coated on an aluminum foil current collector and dried in a drying oven at 100°C for 6 hours to obtain a circular positive electrode with a diameter of 11 mm (the mass of potassium bromide is 3 mg).

[0136] 2. Assemble an aqueous battery: using potassium bromide as the positive electrode, 62 mol / kg K(FSI) 0.55 (OTf) 0.45 • An aqueous solution of 0.9H2O was used as the electrolyte, and an aqueous battery was assembled with glass fiber as the separator for testing.

[0137] Figure 5 The graph shows the cycle performance of the aqueous battery in Comparative Example 1 after 50 charge-discharge cycles at 500 mA g. -1After 50 charge-discharge cycles at a current density, the capacity retention was only 42%. The discharge specific capacity of the aqueous battery in Comparative Example 1 was 50 mAh g. -1 It is only 30% of that in Example 1.

[0138] Comparative Example 2

[0139] An aqueous battery was assembled using the LiFePO4 / NaBr positive electrode sheet from Example 4 as the positive electrode, activated carbon as the negative electrode, 2 mol / L NaClO4 aqueous solution as the electrolyte, and glass fiber as the separator. The mass of NaBr in the positive electrode was 1.0 mg, and the mass of LiFePO4 was 2.5 mg. Figure 6 The graph shows the cycle performance of the aqueous battery in Comparative Example 2 after 20 charge-discharge cycles at 500 mA g. -1 After 20 charge-discharge cycles at the specified current density, the capacity retention rate was only 17%.

[0140] The embodiments of the present invention have been described above. However, the present invention is not limited to the above embodiments. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. An aqueous secondary ion battery, characterized in that, The aqueous secondary ion battery includes a positive electrode material; the positive electrode material includes at least: A positive electrode active material, wherein the positive electrode active material comprises a first active material and a carrier, and the first active material has a low-dimensional structure or a micro / nano crystal structure; The first active substance is selected from alkali metal halide salts or alkali metal sulfites, alkaline earth metal halide salts or alkaline earth metal sulfites, aluminum halides or aluminum sulfites, or zinc halides or zinc sulfites. The carrier has a low-dimensional structure; the carrier is selected from templates and / or a second active substance.

2. The aqueous secondary ion battery according to claim 1, characterized in that, In the positive electrode material, the first active material is uniformly distributed on the support or in the low-dimensional structure of the support; The low-dimensional structure includes at least one of zero-dimensional structure, one-dimensional structure, two-dimensional structure, three-dimensional structure, and multi-level structure; The low-dimensional structures mentioned include crystalline structures or amorphous structures; The template has at least one of the following: zero-dimensional structure, one-dimensional structure, two-dimensional structure, three-dimensional structure, and multi-level structure; The second active substance has zero-dimensional structure, one-dimensional structure, two-dimensional structure, three-dimensional structure, and multi-level structure; The cathode material is at least partially low-dimensional in structure; At least some of the halide salts or sulfites in the cathode material have a low-dimensional structure.

3. The aqueous secondary ion battery according to claim 1, characterized in that, The carrier is selected from templates and may or may not include a second active substance; The second active substance is selected from at least one of manganese oxide, Prussian blue sodium, polyanionic compound, conductive polymer, and organic material; The second active substance has nanoparticles, which further form microspheres.

4. The aqueous secondary ion battery according to claim 1, characterized in that, The alkali metal halide salt is selected from at least one of lithium chloride, lithium bromide, lithium iodide, sodium chloride, sodium bromide, sodium iodide, potassium chloride, potassium bromide, and potassium iodide. The alkali metal sulfite is selected from at least one of lithium sulfite, sodium sulfite, and potassium sulfite; The alkaline earth metal halide salt is selected from at least one of magnesium chloride, magnesium bromide, magnesium iodide, calcium chloride, calcium bromide, and calcium iodide. The alkaline earth metal sulfite is selected from magnesium sulfite and / or calcium sulfite; The aluminum halide is selected from at least one of aluminum chloride, aluminum bromide, and aluminum iodide; The aluminum sulfite is selected from aluminum sulfite; The zinc halide is selected from at least one of zinc chloride, zinc bromide, zinc iodide, and zinc sulfite; The zinc sulfite is selected from zinc sulfite.

5. The aqueous secondary ion battery according to claim 1, characterized in that, In the aforementioned cathode material, the first active material accounts for 1-99% of the total mass of the cathode material; In the aforementioned cathode material, the carrier accounts for 0-99% of the total mass of the cathode material.

6. The aqueous secondary ion battery according to claim 1, characterized in that, In the aforementioned cathode material, the first active material accounts for 5-90% of the total mass of the cathode material; The carrier accounts for 0.1-99% of the total mass of the cathode material.

7. The aqueous secondary ion battery according to claim 1, characterized in that, In the carrier, the mass ratio of the template to the second active substance is 0.1-1:0-10.

8. The aqueous secondary ion battery according to claim 1, characterized in that, In the cathode material, when the first active material is distributed in the low-dimensional structure, the first active material has a low-dimensional structure. When the first active substance is distributed on the carrier, the first active substance constitutes micro-nano crystals; The particle size range of the micro / nano crystals is 0.1-5 μm; In the cathode material, the content of low-dimensional structures in the first active material is higher than the content of micro / nano crystals.

9. The aqueous secondary ion battery according to claim 8, characterized in that, The particle size range of the micro / nano crystals is 0.5-5 μm.

10. The aqueous secondary ion battery according to claim 1, characterized in that, The cathode material is processed by carbonization and elution to obtain a cathode material that contains almost no template.

11. The aqueous secondary ion battery according to claim 1, characterized in that, The cathode material comprises a first active substance and a carrier; the carrier comprises a second active substance; the first active substance and the second active substance are combined to form the cathode material.

12. The aqueous secondary ion battery according to claim 11, characterized in that, The first active material fills the pores of the nanoparticles or microspheres of the second active material, thus forming a positive electrode material.

13. The aqueous secondary ion battery according to claim 1, characterized in that, The aqueous secondary ion battery also includes a negative electrode material, wherein the negative electrode material is selected from carbon-based negative electrode materials; The carbon-based anode material is selected from at least one of activated carbon, graphite, hard carbon, and soft carbon; The carbon-based anode material also includes a metallic element; the metallic element is selected from at least one of magnesium, aluminum, and zinc.

14. The aqueous secondary ion battery according to claim 1, characterized in that, The aqueous secondary ion battery also includes an electrolyte or a gel electrolyte.

15. The aqueous secondary ion battery according to claim 14, characterized in that, The electrolyte is selected from aqueous electrolytes; The aqueous electrolyte comprises an electrolyte and an aqueous solvent; In the aqueous electrolyte, the electrolyte is selected from at least one of lithium salt, sodium salt, potassium salt, magnesium salt, calcium salt, aluminum salt, and zinc salt.

16. The aqueous secondary ion battery according to claim 15, characterized in that, The lithium salt is selected from at least one of lithium sulfate, lithium nitrate, lithium acetate, lithium perchlorate, lithium chloride, lithium difluorosulfonate imide, lithium trifluoromethanesulfonate, lithium bis(trifluoromethanesulfonate)imide, and lithium bis(pentafluoroethylsulfonyl)imide. The sodium salt is selected from at least one of sodium perchlorate, sodium acetate, sodium nitrate, sodium chloride, sodium sulfate, sodium difluorosulfonate imide, sodium trifluoromethanesulfonate, sodium bis(trifluoromethanesulfonate)imide, and sodium bis(pentafluoroethylsulfonyl)imino. The potassium salt is selected from at least one of potassium nitrate, potassium acetate, potassium sulfate, potassium chloride, potassium difluorosulfonate, potassium trifluoromethanesulfonate, potassium bis(trifluoromethanesulfonate)imine, and potassium bis(pentafluoroethylsulfonyl)imine. The zinc salt is selected from at least one of zinc trifluoromethanesulfonate, zinc sulfate, zinc chloride, zinc acetate, zinc trifluoromethanesulfonate, and zinc bis(trifluoromethanesulfonyl)imide; The magnesium salt is selected from at least one of magnesium trifluoromethanesulfonate, magnesium sulfate, magnesium chloride, magnesium acetate, and magnesium bis(trifluoromethanesulfonyl)imide.

17. The aqueous secondary ion battery according to claim 15, characterized in that, The concentration of the electrolyte in the aqueous electrolyte is greater than 1-100 mol / L.

18. The aqueous secondary ion battery according to claim 15, characterized in that, The concentration of the electrolyte in the aqueous electrolyte is 5-70 mol / L.

19. The aqueous secondary ion battery according to claim 15, characterized in that, The gel electrolyte comprises a first polymer host material and an electrolyte, wherein the electrolyte is selected from the aqueous electrolyte. The first polymer host material is selected from at least one of polyvinyl alcohol, polyacrylic acid, polyacrylamide, sodium polyacrylate, polyethylene oxide, polymethyl methacrylate, polyether ether ketone, ethylene glycol acrylonitrile block copolymer and poly(vinylidene fluoride-hexafluoropropylene).

20. The aqueous secondary ion battery according to claim 15, characterized in that, The aqueous electrolyte is K(FSI). 0.55 (OTf) 0.45 • 0.9H2O aqueous electrolyte.

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