Aqueous halogen-hydrogen battery

Abstract

This disclosure provides an aqueous halogen-hydrogen battery, belonging to the field of electrochemical energy storage technology. The aqueous halogen-hydrogen battery includes: an electrolyte, a positive electrode, a negative electrode, and a separator. The electrolyte is an aqueous solution of an acid and a chloride salt. The positive electrode includes an adsorbent material, which is used to facilitate redox reactions between different valence states of iodine and chlorine at the interface with the electrolyte. The different valence states of iodine include ICl₂. ‑ or ICl4 ‑ The negative electrode carries a catalyst and is used to react with the electrolyte at the H2O or H2O interface. + The redox reaction to H2; and the membrane located between the positive and negative electrodes.

Description

Technical Field

[0001] This disclosure relates to the field of electrochemical energy storage technology, specifically to an aqueous halogen-hydrogen battery. Background Technology

[0002] With soaring energy demands and environmental degradation, the development of safe and low-cost batteries beyond lithium-ion batteries has become increasingly important. Aqueous batteries, due to their environmental friendliness and inherent safety, have become a research hotspot. Among them, aqueous hydrogen electrodes have attracted researchers' attention due to the stability and rapid kinetics of the hydrogen evolution and oxidation reactions. The advantages of hydrogen electrodes have prompted researchers to explore materials for cathodes with even better performance.

[0003] Halogens are considered promising electrode materials due to their abundant sources and rapid electrochemical reactions. An aqueous halogen-hydrogen battery has been disclosed in related technologies, where the positive electrode primarily achieves the transformation of halogens iodine and bromine from -1 to 0 oxidation states. However, the multiple oxidation states of halogens limit their theoretical specific capacity. Iodine, in particular, is more suitable as an electrode material due to its solid-state nature. To fully utilize the theoretical capacity of iodine, a series of high-valence compounds targeting iodine (IO4) have been developed. - IO3 - Research has been conducted on reversible electrochemical conversions (e.g., iodine, etc.), but the application in the field of reversible electrochemistry has yielded little success. The main reason is that the redox reaction from iodine to such substances involves the transfer of multiple electrons, and its kinetics are very slow, resulting in poor reversibility of such compounds. Summary of the Invention

[0004] In view of this, this disclosure proposes the construction of an aqueous halogen-hydrogen battery, which combines the redox reaction of chlorine (Cl- / Cl2) and the reactions of iodine in its 0, +1, and +3 oxidation states (I-). 0 / ICl2 - / ICl4 - When applied to hydrogen battery systems, it can achieve reversible electrochemical conversion, which helps to improve the output voltage and energy density of water-based hydrogen batteries.

[0005] To achieve the above objectives, as one aspect of this disclosure, an aqueous halogen-hydrogen battery is provided, comprising: an electrolyte composed of an aqueous solution of an acid and a chloride salt; and a positive electrode comprising an adsorbent material for redox reactions between different valence states of iodine and between different valence states of chlorine at its interface with the electrolyte, wherein the different valence states of iodine include ICl₂. - or ICl4 - The negative electrode is used for H2O or H2O reaction at its interface with the electrolyte. +The redox reaction to H2 is carried out with a catalyst supported on it; a membrane is placed between the positive and negative electrodes.

[0006] In embodiments of this disclosure, different valence states of iodine also include I. - I3 - At least one of I₂, and different valence states of chlorine include Cl. - At least one of Cl2 and Cl2.

[0007] In the embodiments of this disclosure, the concentration of chloride salt is 0.5-20 mol / kg, and the concentration of acid is 0.5-15 mol / L.

[0008] In the embodiments of this disclosure, the adsorbent material includes: a mixture of carbon material, porous material, metal / non-metal electrode, conductive polymer or FTO, ITO conductive glass and elemental iodine, wherein the mass fraction of elemental iodine is 20%-50%.

[0009] In embodiments of this disclosure, the acid includes at least one selected from hydrochloric acid, sulfuric acid, phosphoric acid, acetic acid, and citric acid.

[0010] In embodiments of this disclosure, the chloride salt includes at least one of choline chloride, tetramethylammonium chloride, tetraethylammonium chloride, tetrapropylammonium chloride, tetrabutylammonium chloride, ammonium chloride, potassium chloride, lithium chloride, and sodium chloride.

[0011] In the embodiments of this disclosure, the carbon material includes at least one of activated carbon, graphite, graphene, carbon cloth, carbon paper, carbon micro or nanofibers, carbon felt, graphite felt, and heteroatom-treated modified products thereof; the metal / non-metal electrode includes at least one of gold electrode, platinum electrode, and glassy carbon electrode; the porous material is at least one of metal-organic framework, covalent organic framework, and Prussian blue derivative; the conductive polymer includes at least one of polyaniline, polypyrrole, and poly(3,4-ethylenedioxythiophene).

[0012] In embodiments of this disclosure, the negative electrode is a current collector, which is a carrier for the catalyst.

[0013] In the embodiments of this disclosure, the catalyst includes at least one of precious metal materials, non-precious metal materials, or carbon materials.

[0014] In embodiments of this disclosure, the battery structure includes a button cell, a cylindrical cell, or a flow cell.

[0015] As can be seen from the above technical solution, the aqueous halogen-hydrogen battery provided in this disclosure has at least one or a portion of the following beneficial effects:

[0016] According to embodiments of this disclosure, in the aqueous halogen-hydrogen battery, the positive electrode employs an adsorbent material with good electrochemical activity. Iodine on the positive electrode forms a halogen intermetallic compound with chloride ions, which have a higher electronegativity, through shared electron pairs. The formation of this iodine-chlorohalogen intermetallic compound allows iodine to overcome its reversible oxidation state from -1 to 0, thereby expanding its discharge specific capacity.

[0017] Specifically, through the stabilizing effect of chloride ions in the electrolyte and the combination of unstable trivalent iodine ions, iodine trichloride is formed, which further forms ICl4. - It combines with monovalent iodine ions to form iodine chloride, which further forms ICl2. - ICl2 is stabilized by adjusting the concentration of chloride ions and the acidic environment in the electrolyte. - ICl4 - This avoids ICl2 - ICl4 - Hydrolysis and oxidation. The reversible reaction of iodine breaks through the original reaction based on the -1 and 0 valence, realizing the reversible transformation of iodine from -1 to +3 valence, further stimulating its discharge capacity. At the same time, the adsorbent material of the positive electrode can effectively fix monovalent iodine, trivalent iodine and other compounds, improve the stability of halogen intermetallic compounds, and provide a site for the reversible redox reaction of iodine and the reversible redox reaction of chlorine.

[0018] Rapid hydrogen evolution and hydrogen oxidation reactions occur at the negative electrode. The aqueous halogen-hydrogen battery composed of the positive and negative electrodes more stably activates the +1 and +3 oxidation states of iodine, further enhancing the discharge capacity of iodine; the reaction with chlorine can effectively fix the generated chlorine gas, resulting in a higher discharge specific capacity and discharge plateau. Attached Figure Description

[0019] The present disclosure will be further described in detail below with reference to the accompanying drawings.

[0020] Figure 1 This illustration schematically shows a reaction mechanism diagram of an aqueous halogen-hydrogen battery according to an embodiment of the present disclosure;

[0021] Figure 2 The diagram illustrates the charge-discharge test results of an aqueous iodine-hydrogen battery according to Embodiment 1 of this disclosure at a current density of 2 A / g.

[0022] Figure 3 The diagram illustrates the cycle performance test results of an aqueous iodine-hydrogen battery according to Embodiment 1 of this disclosure at a current density of 2A / g.

[0023] Figure 4The diagram illustrates the rate performance test results of an aqueous iodine-hydrogen battery according to Embodiment 1 of this disclosure at current densities ranging from 0.5 A / g to 2.5 A / g.

[0024] Figure 5 The diagram illustrates the charge-discharge test results curves of an aqueous chlorine-hydrogen battery according to Embodiment 2 of this disclosure at a rate of 5C.

[0025] Figure 6 The diagram illustrates the cycle performance test results of an aqueous chlorine-hydrogen battery according to Embodiment 2 of this disclosure at a rate of 5C.

[0026] Figure 7 This illustration schematically shows an aqueous chlorine-hydrogen battery according to Embodiment 2 of this disclosure, achieving a power output of 1 mA / cm² at -40°C. 2 The curves showing the cyclic performance test results at different flow densities;

[0027] Figure 8 The diagram illustrates the charge-discharge test results curves of an aqueous iodine-hydrogen battery according to Embodiment 3 of this disclosure under the condition of a chloride salt concentration of 0.5 mol / kg.

[0028] Figure 9 The diagram schematically illustrates the charge-discharge curves of an aqueous iodine-hydrogen battery according to Embodiment 4 of this disclosure under phosphonic acid concentrations of 0.5M and 15M.

[0029] Figure 10 The schematic diagram shows the charge-discharge curves of an iodine-hydrogen battery according to Comparative Example 1 of this disclosure under a charging cutoff voltage of 0.7V. Detailed Implementation

[0030] Halogens are considered promising electrode materials due to their abundant sources and relatively rapid electrochemical reactions. Related techniques have explored the transformation of iodine and bromine in halogens from -1 to 0 oxidation states, but their theoretical specific capacities are not limited to these. While related techniques have involved substances with higher oxidation states of iodine, such as +3 and +5, primarily IO4-, these are also considered. - IO3 - However, their electrochemical reversibility is very poor because the redox reaction from elemental iodine to iodine oxide involves the transfer of many electrons, and its kinetics are very slow.

[0031] In view of this, this disclosure proposes the redox reaction of chlorine gas (Cl... - / Cl2) and the redox reaction of iodine (I 0 / ICl2 - / ICl4- This method is applied to a hydrogen battery system. Iodine on the positive electrode forms a halogen intermetallic compound with chloride ions, which have a stronger electronegativity, by sharing electron pairs, thereby effectively fixing iodide ions and chloride ions.

[0032] To make the objectives, technical solutions, and advantages of this disclosure clearer, the following detailed description is provided in conjunction with specific embodiments and the accompanying drawings.

[0033] Figure 1 The schematic diagram illustrates the reaction mechanism of an aqueous halogen-hydrogen battery according to an embodiment of the present disclosure.

[0034] Embodiments of this disclosure provide an aqueous halogen-hydrogen battery, such as... Figure 1 As shown, the electrolyte comprises: an aqueous solution of an acid and a chloride salt; and a positive electrode comprising an adsorbent material, which is used for redox reactions between different valence states of iodine and between different valence states of chlorine at its interface with the electrolyte. The different valence states of iodine include ICl₂. - or ICl4 - The negative electrode is used for H2O or H2O reaction at its interface with the electrolyte. + The redox reaction to H2 is carried out with a catalyst supported on it; a membrane is placed between the positive and negative electrodes.

[0035] According to embodiments of this disclosure, the positive electrode includes an adsorbent material capable of realizing redox reactions between different valence states of iodine and between different valence states of chlorine. The chlorine-hydrogen battery is achieved through a reversible conversion between chloride ions and chlorine gas at the interface between the positive electrode and the electrolyte. The iodine-hydrogen battery, on the other hand, is achieved through a reversible electrochemical conversion of elemental iodine in the adsorbent material at the interface between the positive electrode and the electrolyte. The chloride ions and acidic environment in the electrolyte stabilize the +1 and +3 valence compounds of iodine. The positive electrode uses an adsorbent material with good electrochemical activity, where iodine forms a halogen intermetallic compound with the more electronegative chloride ions through shared electron pairs. The iodine positive electrode successfully activates the iodine at 0.99V vs. SHE through the formation of the iodine-chlorine halogen intermetallic compound. 0 / I + The redox couple expands the discharge specific capacity of iodine. However, trivalent iodine itself is unstable; through the stabilizing effect of chloride ions in the electrolyte, it combines with trivalent iodine ions to form iodine trichloride, which further forms ICl₄. - It combines with monovalent iodine ions to form iodine chloride, which further forms ICl2. -The reversible reaction of iodine breaks through the original reaction based on the -1 and 0 oxidation states, realizing the reversible transformation of iodine from +3 to -1 oxidation state, further stimulating its discharge capacity, and improving the stability of interhalogen compounds. It provides a site for the reversible redox reaction of iodine and the reversible redox reaction of chlorine. The negative electrode uses hydrogen, which can undergo a fast hydrogen evolution reaction and hydrogen oxidation reaction on the catalyst surface.

[0036] The separator placed between the positive and negative electrodes separates the battery's positive and negative electrode materials, preventing short circuits caused by electrode contact and improving battery cycleability and safety. The halogen-hydrogen battery composed of positive and negative electrodes more stably activates the +3 and +1 oxidation states of iodine, further enhancing the discharge specific capacity of iodine; the reaction with chlorine effectively fixes the generated chlorine gas, while the redox reaction of chlorine provides a theoretical capacity of 756 mAh / g and a potential plateau of 1.36 V (vs. SHE), further improving the battery's energy density.

[0037] In embodiments of this disclosure, the adsorbent material includes: a mixture of carbon material, porous material, metal / non-metal electrode, conductive polymer or FTO, ITO conductive glass and elemental iodine, wherein the mass fraction of elemental iodine is 20%-50%, for example, 30% or 40%.

[0038] According to embodiments of this disclosure, the adsorbent material of the positive electrode is a common electrode material, characterized by a large specific surface area and strong adsorption capacity, exhibiting good adsorption and fixation effects on interhalogen compounds and chlorine gas. Iodine is a solid, facilitating handling and quantification. Preliminary experiments according to this disclosure show that when the mass fraction of iodine is 20%-50%, the aqueous halogen-hydrogen battery formed by the iodine positive electrode exhibits better charging performance.

[0039] In the embodiments of this disclosure, the carbon material includes at least one of graphite, graphene, carbon cloth, carbon paper, activated carbon, carbon microfibers or nanofibers, carbon felt, graphite felt, and their heteroatom-treated modified products; the metal / non-metal electrode includes at least one of gold electrode, platinum electrode, and glassy carbon electrode; the porous material includes at least one of metal-organic framework, covalent organic framework, or Prussian blue derivative; and the conductive polymer includes at least one of polyaniline, polypyrrole, and poly(3,4-ethylenedioxythiophene). Carbon materials, metal / non-metal electrodes, and porous materials all have the advantages of large specific surface area and strong adsorption capacity, enabling better fixation of interhalogen compounds and chlorine gas.

[0040] In embodiments of this disclosure, different valence states of iodine also include I. - I3 - At least one of I₂, and different valence states of chlorine include Cl. - And at least one of Cl2. Similar to iodine compounds (IO4) in related technologies.- IO3 - Unlike other substances, the positive electrode reaction of iodine, due to the presence of nucleophilic chloride ions, mainly forms an iodine-chlorine interhalogen compound, thus achieving the theoretical discharge specific capacity of elemental iodine. The positive electrode reaction of chlorine, on the other hand, mainly involves the reversible transformation of chloride ions and chlorine gas.

[0041] In the embodiments of this disclosure, the concentration of chloride salt is 0.5-20 mol / kg, for example, 1 mol / kg, 4 mol / kg, 7 mol / kg, 10 mol / kg, 13 mol / kg, 16 mol / kg, or 19 mol / kg; the concentration of acid is 0.5-15 mol / L, for example, 1 mol / L, 5 mol / L, 9 mol / L, or 13 mol / L. Experiments related to this disclosure have shown that controlling the concentrations of chloride salt and acid within the corresponding ranges can better stabilize the redox reaction of halogens and reduce the occurrence of side reactions. Simultaneously, a suitable acid concentration further inhibits the corrosive effect of the acid.

[0042] In the embodiments of this disclosure, the acid includes one of hydrochloric acid, sulfuric acid, phosphoric acid, acetic acid, and citric acid. The aqueous halogen-hydrogen battery of this disclosure primarily operates in an acidic electrolyte to stabilize the interhalogen compounds generated at the positive electrode. Simultaneously, hydrogen can undergo reversible hydrogen evolution and oxidation reactions in the acidic electrolyte. For example, adding hydrochloric acid, sulfuric acid, or phosphoric acid to the aqueous solution can enable the battery to perform normal charge and discharge processes.

[0043] In the embodiments of this disclosure, the chloride salt includes at least one selected from choline chloride, tetramethylammonium chloride, tetraethylammonium chloride, tetrapropylammonium chloride, tetrabutylammonium chloride, ammonium chloride, potassium chloride, lithium chloride, and sodium chloride. The chloride salt in the electrolyte needs to have relatively high solubility to form a high-concentration electrolyte, thereby reducing the activity of free water molecules and minimizing side reactions such as oxygen evolution reaction and chlorine disproportionation reaction caused by water, thus improving the charge-discharge performance of the battery. In aqueous iodine-hydrogen batteries, chloride ions mainly play a role in generating interhalogen compounds and stabilizing iodine in its +1 and +3 valence states; in chlorine-hydrogen batteries, as a positive electrode, they can generate chlorine gas during charging.

[0044] In the embodiments of this disclosure, the negative electrode is a current collector, which serves as a catalyst support. The current collector has the advantage of enabling rapid three-phase interfacial reactions and can support catalysts for the hydrogen evolution reaction and hydrogen oxidation reaction.

[0045] In embodiments of this disclosure, the catalyst includes at least one of noble metal materials, non-noble metal materials, or carbon materials. Catalysts for the hydrogen evolution reaction and hydrogen oxidation reaction are of various types, promoting the reaction at the three-phase interface through active sites on the catalyst surface.

[0046] In embodiments of this disclosure, the noble metal materials include Pt, Pd, Ir, Ru, and their alloys. The alloys include PtNi, PtCo, PtMo, PtW, PtNiCo, PtNiMo, and combinations thereof; PdNi, PdCo, ​​PdMo, PdW, PdNiCo, PdNiMo, and combinations thereof; IrNi, IrCo, IrMo, IrW, IrNiCo, IrNiMo, and combinations thereof; RuNi, RuCo, RuMo, RuW, RuNiCo, RuNiMo, and combinations thereof; the noble metal materials also include PtO2, PtOH, etc. At least one of PtC, IrO2, IrC, IrN, IrS, IrP, RuO2, RuC, RuN, RuS, RuP and combinations thereof, or mixtures thereof with nano-carbon; non-noble metal materials include one or more of Ni, NiMo, NiCoMo, MoC, MoC2, MoO2, MoS2, MoP, WC, WC2, WO2, WS2, WP, NiN, NiS, NiP, and NiPS; carbon materials include one or more of microspheres, nanospheres, microparticles, nanoparticles, microsheets, nanosheets, microwires, nanowires, microtubes, and nanotubes.

[0047] According to embodiments of this disclosure, precious metal catalysts have the advantage of high catalytic activity, non-precious metal catalysts have the advantage of catalytic activity that is not much different from that of precious metals and are relatively inexpensive, and carbon catalysts have the advantage of low price, but carbon catalysts have relatively poor catalytic activity.

[0048] In the embodiments of this disclosure, the hydrogen pressure inside the negative electrode of the aqueous halogen-hydrogen battery is 1-100 atm. Preliminary experiments related to this disclosure show that a hydrogen pressure within this range is favorable for hydrogen oxidation at the negative electrode.

[0049] In the embodiments of this disclosure, the battery structure includes a button cell, a cylindrical cell, or a flow battery. Button cells are characterized by their small size and ease of operation, and are commonly used in laboratory settings; cylindrical cells are characterized by their high energy density, and are commonly used in portable energy sources such as laptops and digital cameras; flow batteries are characterized by their large capacity, and are commonly used in large-scale energy storage devices.

[0050] In the embodiments of this disclosure, the charging cutoff voltage of the battery is set to 1.2-1.5V, for example, 1.3V or 1.4V. Preliminary experiments of this disclosure have shown that when the charging cutoff voltage of the aqueous iodine-hydrogen battery of this disclosure is set to 1.2-1.5V, the three charge and discharge plateaus of iodine can be presented and the precipitation of chlorine gas at higher potentials can be avoided.

[0051] The present disclosure is further illustrated below by way of proportions, embodiments, accompanying drawings, and related test experiments and results. In the following detailed description, numerous specific details are set forth to provide a comprehensive understanding of the embodiments of the present disclosure for ease of explanation. However, it will be apparent that one or more embodiments may be practiced without these specific details. Moreover, the details in the following embodiments can be arbitrarily combined to form other feasible embodiments without conflict.

[0052] It should be noted that the specific embodiments described below are merely illustrative examples, and the scope of protection of this disclosure is not limited thereto. The chemicals and raw materials used in the following embodiments are all commercially available or prepared in-house using recognized methods.

[0053] Example 1

[0054] Aqueous iodine-hydrogen battery

[0055] In an aqueous iodine-hydrogen battery, the positive electrode features a reversible conversion between iodine ions and iodine halogen intercalation through an adsorbent material. The negative electrode is a catalytic electrode material capable of reversible oxidation and reduction of hydrogen. The possible reaction equations for the positive and negative electrodes of the assembled full cell, along with their standard electrode potentials, are as follows:

[0056] positive electrode:

[0057]

[0058]

[0059]

[0060] negative electrode:

[0061] For example, under acidic electrolyte conditions, I - The conversion between solid I₂ and elemental I₂. The overall reaction is...

[0062] In one embodiment of this disclosure, the electrolyte is a mixed aqueous solution of acid and chloride salt.

[0063] Preparation of the phosphoric acid-based electrolyte: 85% phosphoric acid was diluted to 9M phosphoric acid, and 20M choline chloride was added and stirred thoroughly to dissolve, thus obtaining the electrolyte. In this embodiment, the outer shell is a stainless steel flange-connected ball valve (purchased from Swagelok), which serves to fill and seal the hydrogen gas. Internally, the positive electrode, negative electrode, and diaphragm material are assembled in a cladding manner. The electrolyte is a mixed solution of the acid and chloride salt prepared above, which also wets the diaphragm.

[0064] The positive electrode adsorbent is a mixture of porous activated carbon and elemental iodine, with the iodine content being 30% by mass. The negative electrode is a Pt / C catalyst supported on a gas diffusion layer. The charging cutoff voltage of the aqueous iodine-hydrogen battery in Example 1 was set to 1.3V to ensure all three charge / discharge plateaus are fully represented and to prevent chlorine evolution at higher potentials. The electrochemical performance of the above-mentioned acid and chloride salt mixed electrolyte was tested. The aqueous iodine-hydrogen battery of this disclosure exhibits a coulombic conversion efficiency of 97.7% in a phosphoric acid-based electrolyte, and an average discharge voltage of 0.75V.

[0065] Figure 2 The schematic diagram shows the charge-discharge test results curves of an aqueous iodine-hydrogen battery according to Example 1 at a current density of 2A / g; Figure 3 The diagram illustrates the cycle performance test results of an aqueous iodine-hydrogen battery according to Example 1 at a current density of 2 A / g. Figure 4 The diagram schematically illustrates the rate performance test results of an aqueous iodine-hydrogen battery according to Embodiment 1 at current densities ranging from 0.5 A / g to 2.5 A / g. Figure 2 and Figure 3 As shown, at a rate of 2 A / g (1 A / g = 0.25 mA), based on the mass of the positive electrode iodine, a discharge specific capacity of 801 mAh / g and an energy density of 600 Wh / kg were achieved. Furthermore, it exhibits good cycle life, with a capacity retention of 73% after 500 cycles. Figure 4 As shown, it can also exhibit good rate performance in the range of 0.5A / g to 2.5A / g.

[0066] Example 2

[0067] Aqueous chlorine-hydrogen batteries

[0068] In an aqueous chlorine-hydrogen battery, the reversible conversion of chloride ions to chlorine gas occurs at the positive electrode, which is an adsorbent material. The negative electrode is a catalytic electrode material capable of reversible oxidation and reduction of hydrogen. The possible reaction equations for the positive and negative electrodes of the assembled full cell, along with their standard electrode potentials, are as follows:

[0069] positive electrode:

[0070] negative electrode:

[0071] For example, under acidic electrolyte conditions, Cl - The conversion between gaseous Cl2 and elemental Cl2. The overall reaction is...

[0072] Preparation of phosphoric acid-based electrolyte: 85% phosphoric acid was diluted to 9M phosphoric acid, and then 10M choline chloride was added and stirred thoroughly to dissolve, thus obtaining the electrolyte. In this Example 2, the outer shell is a stainless steel flange-connected ball valve (purchased from Swagelok), which serves to fill and seal the hydrogen gas. Internally, the positive electrode, negative electrode, and diaphragm material are assembled in a cladding manner. The electrolyte is a mixed solution of the acid and chloride salt prepared above, which also wets the diaphragm.

[0073] The positive electrode adsorbent is porous activated carbon, and the negative electrode is a Pt / C catalyst supported on a gas diffusion layer. The charging cutoff voltage of the aqueous chlorine-hydrogen battery in Example 2 is set to 1.36V. Because chlorine has only one charging plateau, it is not affected by the charging cutoff voltage, and the charging capacity is controlled based on the specific capacity of the positive electrode. The electrochemical performance of the above-mentioned acid and chloride salt mixed electrolyte was tested. The aqueous chlorine-hydrogen battery of this disclosure exhibits an 88% coulombic conversion efficiency, a discharge specific capacity of 270 mAh / g, and a discharge voltage plateau of 1.2V under the above electrolyte conditions.

[0074] Figure 5 The schematic diagram shows the charge-discharge test results curve of an aqueous chlorine-hydrogen battery according to Embodiment 2 at a rate of 5C. Figure 6 The diagram illustrates the cycle performance test results of an aqueous chlorine-hydrogen battery according to Embodiment 2 at a rate of 5C. Figure 7 This schematically illustrates an aqueous chlorine-hydrogen battery according to Embodiment 2, achieving a power output of 1 mA / cm² at -40°C. 2 The curves showing the cyclic performance test results at the current density.

[0075] like Figure 5 and Figure 6 As shown, the aqueous chlorine-hydrogen battery can stably cycle 500 times and also exhibits good rate performance. Figure 7 As shown, the battery can achieve a coulombic conversion efficiency of 92% at a low temperature of -40℃, exhibiting good cycle stability and almost no capacity decay after 350 cycles.

[0076] Example 3

[0077] Aqueous iodine-hydrogen battery

[0078] In an aqueous iodine-hydrogen battery, the positive electrode features a reversible conversion between iodine ions and iodine halogen intercalation through an adsorbent material. The negative electrode is a catalytic electrode material capable of reversible oxidation and reduction of hydrogen. The possible reaction equations for the positive and negative electrodes of the assembled full cell, along with their standard electrode potentials, are as follows:

[0079] positive electrode:

[0080]

[0081]

[0082]

[0083] negative electrode:

[0084] For example, under acidic electrolyte conditions, I - The conversion between solid I₂ and elemental I₂. The overall reaction is...

[0085]

[0086] In one embodiment of this disclosure, the electrolyte is a mixed aqueous solution of acid and chloride salt.

[0087] Preparation of the phosphoric acid-based electrolyte: 85% phosphoric acid was diluted to 9M phosphoric acid, and 0.5M choline chloride was added and stirred thoroughly to dissolve, thus obtaining the electrolyte. In Example 3, the outer shell is a stainless steel flange-connected ball valve (purchased from Swagelok), which serves to fill and seal the hydrogen gas. Internally, the positive electrode, negative electrode, and diaphragm material are assembled in a cladding manner. The electrolyte is a mixed solution of the acid and chloride salt prepared above, which also wets the diaphragm.

[0088] The positive electrode adsorbent is a mixture of porous activated carbon and elemental iodine, with the mass fraction of elemental iodine being 30%. The negative electrode is a Pt / C catalyst supported on a gas diffusion layer. The charging cutoff voltage of the aqueous iodine-hydrogen battery in Example 3 is set to 1.3V to ensure that all three charge-discharge plateaus are fully represented and to prevent chlorine evolution at higher potentials.

[0089] The electrochemical performance of the electrolyte mixture of the above-mentioned acid and chloride salt was tested. Figure 8 The schematic diagram illustrates the charge-discharge test results curves of an aqueous iodine-hydrogen battery according to Embodiment 3 at a current density of 2 A / g. Figure 8 As shown, the discharge specific capacity of the iodine-hydrogen battery using 0.5 mol / kg chloride electrolyte reaches 1030 mAh / g. Although its coulombic efficiency is relatively low at 86%, 0.5 mol / kg chloride can still successfully excite three consecutive charge-discharge plateaus of iodine.

[0090] Example 4

[0091] Aqueous iodine-hydrogen battery

[0092] In an aqueous iodine-hydrogen battery, the positive electrode features a reversible conversion between iodine ions and iodine halogen intercalation through an adsorbent material. The negative electrode is a catalytic electrode material capable of reversible oxidation and reduction of hydrogen. The possible reaction equations for the positive and negative electrodes of the assembled full cell, along with their standard electrode potentials, are as follows:

[0093] positive electrode:

[0094]

[0095]

[0096]

[0097] negative electrode:

[0098] For example, under acidic electrolyte conditions, I - The conversion between solid I₂ and elemental I₂. The overall reaction is...

[0099]

[0100] In one embodiment of this disclosure, the electrolyte is a mixed aqueous solution of acid and chloride salt.

[0101] Preparation of phosphoric acid-based electrolyte: 85% phosphoric acid was diluted to 0.5M phosphoric acid, and 20M choline chloride was added and stirred thoroughly to dissolve, resulting in an acidic electrolyte with a concentration of 0.5 mol / L. Separately, 85% phosphoric acid (15M concentration) was added to 20M choline chloride and stirred thoroughly to dissolve, resulting in an acidic electrolyte with a concentration of 15 mol / L. In Example 4, the outer shell is a stainless steel flange-connected ball valve (purchased from Swagelok), which serves to fill and seal hydrogen gas. Internally, the positive electrode, negative electrode, and diaphragm material are assembled in a clasp-like manner. The electrolyte is a mixed solution of the acid and chloride salt prepared above, which wets the diaphragm.

[0102] The positive electrode adsorbent is a mixture of porous activated carbon and elemental iodine, with the mass fraction of elemental iodine being 30%. The negative electrode is a Pt / C catalyst supported on a gas diffusion layer. The charging cutoff voltage of the aqueous iodine-hydrogen battery in Example 4 is set to 1.3V to ensure that all three charge-discharge plateaus are fully represented and to prevent chlorine evolution at higher potentials.

[0103] Figure 9 The diagram schematically illustrates the charge-discharge curves of an aqueous iodine-hydrogen battery according to Example 4 of this invention under phosphonic acid concentrations of 0.5 mol / L and 15 mol / L. Figure 9As shown, phosphonic acid concentrations of 0.5 mol / L and 15 mol / L both exhibited good charge-discharge potential plateaus of iodine, with high coulombic efficiency and discharge specific capacity exceeding 500 mAh / g.

[0104] Comparative Example 1

[0105] Using the same electrolyte and battery assembly method as in Example 1, the charging cutoff voltage E is set during charging and discharging. 0 The possible reaction equations for the positive and negative electrodes of the assembled full cell, set to 0.7V, and their standard electrode potentials are as follows:

[0106] positive electrode:

[0107]

[0108] negative electrode:

[0109] For example, under acidic electrolyte conditions, I - The conversion between solid I₂ and elemental I₂. The overall reaction is...

[0110]

[0111] Figure 10 The schematic diagram illustrates the charge-discharge curves of an iodine-hydrogen battery according to Comparative Example 1 at a charging cutoff voltage of 0.7V. Figure 10 As shown, when the iodine-hydrogen battery is based on the reaction between iodine's -1 and -0 valence states, the aforementioned battery only exhibits a discharge plateau at 0.45V, with a discharge specific capacity of 325 mAh / g. However, in Example 1, the stabilizing effect of chloride ions forming interhalogen compounds stimulates two higher charge-discharge plateaus for iodine, achieving a discharge specific capacity of 801 mAh / g, more than doubling the discharge specific capacity of related technologies based on iodine cathodes.

[0112] The specific embodiments described above further illustrate the purpose, technical solutions, and beneficial effects of this disclosure. It should be understood that the above descriptions are merely specific embodiments of this disclosure and are not intended to limit this disclosure. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this disclosure should be included within the protection scope of this disclosure.

Claims

1. A water-based halogen-hydrogen battery, comprising: an electrolyte, which is an aqueous solution of an acid and a chloride salt; A positive electrode comprising an adsorptive material for redox reactions between different valence states of iodine, including ICI2 − or ICI4 − at its interface with said electrolyte, and redox reactions between different valence states of chlorine. The negative electrode is used for H2O or H2O reaction at its interface with the electrolyte. + The redox reaction to H2 is carried out with a catalyst on it; a separator, which is arranged between the positive electrode and the negative electrode; wherein the adsorptive material comprises a mixture of one of carbon material, metal organic framework, covalent organic framework, Prussian blue derivative, metal / non-metal electrode, conductive polymer or FTO, ITO conductive glass, and elemental iodine, and the mass fraction of the elemental iodine is 20-50%; the negative electrode is a current collector, and the current collector is a carrier that carries the catalyst, and the catalyst comprises at least one of noble metal material, non-noble metal material or carbon material.

2. The battery of claim 1, wherein, The different valence states of iodine include at least one of I − , I3 − , I2. The different valence states of chlorine include at least one of Cl − , and Cl2.

3. The battery of claim 1, wherein, The concentration of the chloride salt is 0.5-20 mol / kg, and the concentration of the acid is 0.5-15 mol / L.

4. The battery of claim 1, wherein, The acid comprises at least one of hydrochloric acid, sulfuric acid, phosphoric acid, acetic acid and citric acid.

5. The battery of claim 1, wherein, The chloride salt comprises at least one of choline chloride, tetramethylammonium chloride, tetraethylammonium chloride, tetrapropylammonium chloride, tetrabutylammonium chloride, ammonium chloride, potassium chloride, lithium chloride and sodium chloride.

6. The battery of claim 1, wherein, The carbon material comprises at least one of activated carbon, graphite, graphene, carbon cloth, carbon paper, carbon micro or nano fiber, carbon felt, graphite felt and heteroatom treatment modification thereof; the metal / non-metal electrode comprises at least one of gold electrode, platinum electrode and glassy carbon electrode; and the conductive polymer comprises at least one of polyaniline, polypyrrole and poly(3,4-ethylenedioxythiophene).

7. The battery of claim 1, wherein, The structure of the battery comprises a button cell, a cylindrical cell or a flow battery.

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