Aqueous zinc metal secondary battery based on silver halide positive electrode

Abstract

The invention discloses an aqueous zinc metal secondary battery based on a silver halide positive electrode, and belongs to the technical field of electrochemical energy storage, the aqueous zinc metal secondary battery comprises an electrolyte, a positive electrode, a negative electrode and a diaphragm, the positive electrode is a silver halide material and is used for carrying out a silver halide redox reaction on an interface between the positive electrode and the electrolyte; the negative electrode is a zinc sheet and is used for carrying out zinc metal redox reaction on an interface between the negative electrode and the electrolyte; and the diaphragm is arranged between the positive electrode and the negative electrode. By adopting the aqueous zinc metal secondary battery based on the silver halide positive electrode, the core problems that a traditional zinc-silver battery positive electrode material is easy to dissolve and poor in cycle performance are fundamentally solved, and a feasible technical path is provided for large-scale energy storage application.

Description

Technical Field

[0001] This invention relates to the field of electrochemical energy storage technology, and in particular to an aqueous zinc metal secondary battery based on a silver halide cathode. Background Technology

[0002] With the accelerated global energy structure transformation and the advancement of "dual carbon" goals, the development of large-scale electrochemical energy storage technologies that are highly safe, low-cost, and environmentally friendly has become an urgent need. Aqueous zinc metal batteries are advantageous due to their use of non-flammable aqueous electrolytes, abundant zinc resources, and high theoretical capacity (820mAh g). -1 With its advantages such as low electrode potential (-0.76V vs. SHE) and simple manufacturing process, it is regarded as an important candidate for the next generation of energy storage systems.

[0003] Among various aqueous zinc-metal battery systems, traditional zinc-silver batteries have attracted considerable attention due to their high operating voltage (typically >1.5V) and high energy density. However, traditional zinc-silver batteries face a serious technical bottleneck in practical applications: their positive electrode silver oxide active material is prone to irreversible conversion and dissolution reactions during charge and discharge, especially in neutral or weakly acidic electrolyte environments. This dissolution behavior mainly stems from the limited solubility product (K0) of the silver oxide positive electrode at low pH. sp The continuous loss of cathode material not only leads to rapid capacity decay, but also significantly shortens the battery cycle life (usually less than 100 cycles), severely restricting its promotion in large-scale application scenarios such as long-term energy storage and grid peak shaving.

[0004] Therefore, traditional zinc-silver batteries often use strongly alkaline electrolytes (such as KOH solution). Although this can improve ionic conductivity and suppress the dissolution of silver oxide cathode, it will exacerbate dendrite growth and hydrogen evolution side reactions in zinc anode, reducing the coulombic efficiency and safety of the battery.

[0005] To overcome these problems, researchers have recently attempted to suppress silver oxide cathode dissolution through strategies such as cathode structure design (e.g., carbon coating, nano-confining), halide ion electrolyte additive regulation, or the development of novel salt systems. However, these methods often struggle to simultaneously achieve high reversibility, long cycle life, and high energy density, and lack systematic utilization of halide ion redox reactions. Summary of the Invention

[0006] The purpose of this invention is to provide an aqueous zinc metal secondary battery based on a silver halide cathode. It cleverly utilizes the reversible multi-valence transformation of halide ions during charge and discharge to construct a cathode reaction pathway based on a compound conversion mechanism, with silver halide as the initial active material. By introducing a certain concentration of halide ions into the electrolyte, excessive dissolution of the silver halide cathode driven by concentration gradient can be suppressed, and a highly efficient and reversible redox process can be achieved by forming stable polyhalide intermediates. Using a neutral or weakly acidic zinc salt aqueous solution as the base electrolyte avoids corrosion of the zinc anode by a strongly alkaline environment and effectively improves the electrochemical stability window and cycle durability of the entire battery system.

[0007] To achieve the above objectives, the present invention provides an aqueous zinc metal secondary battery based on a silver halide positive electrode, comprising an electrolyte, a positive electrode, a negative electrode, and a separator, wherein: The electrolyte is an aqueous solution containing zinc salts and halide ions; The positive electrode is made of silver halide material and is used for the redox reaction of silver halide at the interface between the positive electrode and the electrolyte. The negative electrode is made of zinc metal and is used for zinc metal redox reaction at the interface between the negative electrode and the electrolyte. A diaphragm is placed between the positive and negative electrodes.

[0008] Preferably, the zinc salt concentration ranges from 0.1 to 4 mol / kg, and the halide ion concentration ranges from 0.05 to 2 mol / kg.

[0009] Preferably, the silver halide material includes silver halide, binder, and carbon material, with the carbon material and binder supported on the silver halide.

[0010] Preferably, the zinc salt is one of zinc sulfate, zinc chloride, zinc nitrate, zinc gluconate, zinc lactate, zinc perchlorate, zinc tetrafluoroborate, zinc trifluoromethanesulfonate, zinc acetate, and zinc carbonate.

[0011] Preferably, the halide ion is one of iodide ion, bromide ion, or chloride ion.

[0012] Preferably, the silver halide is one of silver bromide, silver chloride, and silver iodide.

[0013] Preferably, the adhesive is one of CMC, PVDF, and PTFE.

[0014] Preferably, the carbon material is one or more of graphite, graphene, carbon cloth, carbon paper, activated carbon, carbon fiber, carbon felt, graphite felt, acetylene black, and Ketjen black.

[0015] Preferably, the structure of the aqueous zinc metal secondary battery is one of the following: button cell, cylindrical cell, square cell, or irregularly shaped cell.

[0016] Therefore, the present invention employs the above-mentioned aqueous zinc metal secondary battery based on a silver halide cathode, which has the following beneficial effects: (1) By cleverly utilizing the reversible participation of halide ions in multivalent state transformation during charging and discharging, a positive electrode reaction pathway is constructed with silver halide as the initial active material and the compound conversion mechanism as the basis; (2) By introducing a certain concentration of halide ions into the electrolyte, on the one hand, the excessive dissolution of silver halide cathode caused by concentration difference can be suppressed, and on the other hand, the reversible oxidation-reduction process of halogen can be realized. (3) Using a neutral or weakly acidic zinc salt aqueous solution as the base electrolyte avoids the corrosion of the zinc anode by the strong alkaline environment and effectively improves the electrochemical stability window and cycle durability of the entire battery system.

[0017] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the reaction mechanism of Example 1 of the present invention, which is an aqueous zinc metal secondary battery based on a silver halide cathode. Figure 2 This is an external photograph of Embodiment 1 of an aqueous zinc metal secondary battery based on a silver halide cathode according to the present invention; Figure 3 This is the charge-discharge test result of Example 1 of the aqueous zinc metal secondary battery based on silver halide cathode of the present invention in a zinc salt electrolyte containing bromide ions and a voltage range of 0.4~1.2V; Figure 4 This is the charge-discharge test result of Example 1 of the aqueous zinc metal secondary battery based on silver halide cathode of the present invention in a zinc salt electrolyte containing bromide ions and a voltage range of 1.1~1.9V; Figure 5 This is the charge-discharge test result of Example 1 of the aqueous zinc metal secondary battery based on silver halide cathode of the present invention in a zinc salt electrolyte containing bromide ions and a voltage range of 0.4~1.9V; Figure 6 This is the cycle performance test curve of Example 1 of the aqueous zinc metal secondary battery based on silver halide cathode of the present invention in a zinc salt electrolyte containing bromide ions and a voltage range of 0.4~1.2V; Figure 7 This is the cycle performance test curve of Example 1 of the aqueous zinc metal secondary battery based on silver halide cathode of the present invention in a zinc salt electrolyte containing bromide ions and a voltage range of 1.1~1.9V; Figure 8This is the cycle performance test curve of Example 1 of the aqueous zinc metal secondary battery based on silver halide cathode of the present invention in a zinc salt electrolyte containing bromide ions and a voltage range of 0.4~1.9V; Figure 9 This is the rate performance test curve of Example 1 of the aqueous zinc metal secondary battery based on silver halide cathode of the present invention in a zinc salt electrolyte containing bromide ions and a voltage range of 0.4~1.9V.

[0019] Figure 10 This is the charge-discharge test result curve of Example 2 of the aqueous zinc metal secondary battery based on silver halide cathode of the present invention in an iodine-containing zinc salt electrolyte and a voltage range of 0.4~1.6V; Figure 11 This is the cycle performance test curve of Example 2 of the present invention, an aqueous zinc metal secondary battery based on a silver halide cathode, in an iodine-containing zinc salt electrolyte and a voltage range of 0.4~1.6V. Detailed Implementation

[0020] This invention provides an aqueous zinc metal secondary battery based on a silver halide positive electrode, comprising an electrolyte, a positive electrode, a negative electrode, and a separator, wherein: The electrolyte is an aqueous solution containing zinc salts and halide ions; The positive electrode is made of silver halide material and is used for the redox reaction of silver halide at the interface between the positive electrode and the electrolyte. The negative electrode is made of zinc metal and is used for zinc metal redox reaction at the interface between the negative electrode and the electrolyte. A diaphragm is placed between the positive and negative electrodes.

[0021] In this invention, the zinc salt concentration ranges from 0.1 to 4 mol / kg, and the halide ion concentration ranges from 0.05 to 2 mol / kg.

[0022] In this invention, the silver halide material includes silver halide, binder, and carbon material, with the carbon material and binder supported on the silver halide.

[0023] In this invention, redox reactions between different valence states of silver halide occur at the interface between the positive electrode and the electrolyte. These redox reactions include one of the following: redox reactions between different valence states of iodine, redox reactions between different valence states of bromine, and redox reactions between different valence states of chlorine.

[0024] In this invention, iodine in different valence states is I. - I3 - One of I2, bromine has different oxidation states Br. - Br3 - One of Br2, chlorine has different oxidation states, Cl. - Cl2 or ClO3 -One of them.

[0025] In this invention, the zinc salt is one of zinc sulfate, zinc chloride, zinc nitrate, zinc gluconate, zinc lactate, zinc perchlorate, zinc tetrafluoroborate, zinc trifluoromethanesulfonate, zinc acetate, and zinc carbonate.

[0026] In this invention, the halide ion is one of iodide ion, bromide ion, and chloride ion.

[0027] In this invention, silver halide is one of silver bromide, silver chloride, and silver iodide.

[0028] In this invention, the adhesive is one of CMC, PVDF, and PTFE.

[0029] In this invention, the carbon material is one or more of graphite, graphene, carbon cloth, carbon paper, activated carbon, carbon fiber, carbon felt, graphite felt, acetylene black, and Ketjen black.

[0030] In this invention, the structure of the aqueous zinc metal secondary battery is one of the following: button cell, cylindrical cell, square cell, or irregularly shaped cell.

[0031] The technical solution of the present invention will be further described below with reference to the accompanying drawings and embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Any changes, modifications, substitutions, combinations, or simplifications made without departing from the spirit and principle of the present invention should be considered equivalent substitutions and are included within the protection scope of the present invention. Furthermore, it should be understood that after reading the contents of this invention, those skilled in the art can make various modifications or adjustments to the invention, and these equivalent forms also fall within the scope defined by the appended claims and are all within the protection scope of the present invention.

[0032] In this document, the term "embodiment" means that a specific feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The term "embodiment" appearing in various places throughout the specification does not necessarily refer to the same embodiment, nor does it specifically limit its independence or connection with other embodiments. In principle, in this application, as long as there are no technical contradictions or conflicts, the technical features mentioned in each embodiment can be combined in any way to form corresponding implementable technical solutions.

[0033] Unless otherwise defined, the technical terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains; the use of related terms herein is merely for the purpose of describing particular embodiments and is not intended to limit this application.

[0034] In this invention, unless otherwise specified, all other test materials and instruments are conventional test materials in the field and can be purchased through commercial channels.

[0035] Example 1 This invention provides an aqueous zinc metal secondary battery based on a silver halide positive electrode, comprising an electrolyte, a positive electrode, a negative electrode, and a separator, wherein: The electrolyte is a mixture of zinc sulfate and choline bromide; the preparation method is as follows: 0.25 mol / kg ChBr is added to a 4 mol / kg ZnSO4 solution and stirred thoroughly to dissolve, thus obtaining a mixed electrolyte containing bromide ions; The positive electrode, made of silver bromide, is used for the silver bromide redox reaction at the interface between the positive electrode and the electrolyte. The preparation method is as follows: AgBr: activated carbon (YP-50F): acetylene black: PVDF are uniformly mixed in a mass percentage ratio of 4:4:1:1. An appropriate amount of NMP is added, and the mixture is ground evenly. The mixture is then coated onto titanium foil, and the vacuum oven temperature is controlled at 60℃ for 24 hours. After baking, the product is removed and cut into 1.13cm pieces using a punching machine. 2 Small round pieces.

[0036] The negative electrode is commercial zinc foil; the preparation method is as follows: zinc foil is stamped using a stamping machine and cut into 1.13cm pieces. 2 Small round pieces.

[0037] A diaphragm is placed between the positive and negative electrodes.

[0038] Assembly of a silver bromide zinc metal secondary battery: Assemble the secondary battery in the following order: CR2032 negative electrode shell, zinc foil, separator, electrolyte, silver bromide positive electrode, gasket, spring contact, and CR2032 positive electrode shell. Figure 2 As shown.

[0039] like Figure 1 As shown, the overall reaction at the positive electrode of the silver bromide-based aqueous zinc metal secondary battery is achieved through a two-step pathway with an intermediate, where bromide ions ensure the pathway's smoothness and reversibility. The reaction at the negative electrode involves the reversible deposition and dissolution of zinc. The possible reaction equations for the positive and negative electrodes of this battery system, assembled using coin cells, are as follows: positive electrode: Charging process: 3Br - →Br3 - +2e - ; Ag+Br - →AgBr+e - ; Discharge process: Br3 - +2e -→3Br - ; AgBr+e - →Ag+Br - ; Negative electrode: Zn⇋Zn 2+ +2e - ; Example 2 This invention provides an aqueous zinc metal secondary battery based on a silver iodide positive electrode, comprising an electrolyte, a positive electrode, a negative electrode, and a separator, wherein: The electrolyte is a mixture of zinc sulfate and potassium iodide; the preparation method is as follows: 0.25 mol / kg KI is added to a 4 mol / kg ZnSO4 solution and stirred thoroughly to dissolve, thus obtaining a mixed electrolyte containing iodide ions; The positive electrode, made of silver iodide, is used for the silver iodide redox reaction at the interface between the positive electrode and the electrolyte. The preparation method is as follows: AgI: activated carbon (YP-50F): acetylene black: PVDF are uniformly mixed in a mass percentage ratio of 4:4:1:1. An appropriate amount of NMP is added, and the mixture is ground evenly. The mixture is then coated onto titanium foil, and the vacuum oven temperature is controlled at 60℃ for 24 hours. After baking, the product is removed and cut into 1.13cm pieces using a die-cutting machine. 2 Small round pieces.

[0040] The negative electrode is commercial zinc foil; the preparation method is as follows: zinc foil is stamped using a stamping machine and cut into 1.13cm pieces. 2 Small round pieces.

[0041] A diaphragm is placed between the positive and negative electrodes.

[0042] Assembly of a silver iodide-zinc metal secondary battery: The secondary battery is assembled sequentially as follows: CR2032 negative electrode shell, zinc foil, separator, electrolyte, silver iodide positive electrode, gasket, spring contact, and CR2032 positive electrode shell. The possible reaction equations for the positive and negative electrodes of this secondary battery system, assembled using coin cells, are as follows: positive electrode: Charging process: 3I - → I3 - +2e - ; Ag+I - → AgI +e - ; Discharge process: I3 - + 2e - → 3I - ; AgI+e - →Ag+I - ; Negative electrode: Zn⇋Zn 2+ +2e - ; Test case The secondary battery of Example 1 was tested in different discharge plateau ranges: the low plateau voltage range (0.4~1.2V), the high plateau voltage range (1.4-1.9V), and the full voltage range (0.4~1.9V). The test results are as follows: Figures 3-9 As shown.

[0043] Depend on Figure 3 It can be seen that the secondary battery exhibits a stable discharge plateau and a coulombic efficiency of 99.96% at a low voltage of 0.81V, proving the reversibility of the reaction process (AgBr + e⁻) at low potential. - →Ag+Br - ).

[0044] Depend on Figure 4 It can be seen that the secondary battery exhibits another discharge plateau at a higher voltage of 1.7V, demonstrating a coulombic efficiency of 98.8%, confirming the existence of a second independent redox reaction (Br3). - +2e - →3Br - ).

[0045] Depend on Figure 5 It can be seen that this demonstrates the charge-discharge behavior of the secondary battery under a voltage window that simultaneously covers both low and high voltage plateaus. The curves clearly show two continuous and distinct discharge plateaus, intuitively proving that the positive electrode reaction is the Ag / AgBr conversion and Br... - / Br3 - Redox mechanism.

[0046] contrast Figures 3-5 The experimental data directly confirmed the existence of two independent electrochemical reactions at the positive electrode. Figure 5 no Figure 3 and Figure 4 It is a simple superposition, but it clearly shows that the two reactions can occur sequentially in a single cell, providing the most direct evidence for the proposed mechanism of Ag / AgBr conversion coupled with halogen redox coupling.

[0047] Depend on Figure 6 It can be seen that the secondary battery can operate stably for 4000 cycles at a low voltage platform, but the total capacity is low (60mAh / g) because only a portion of the theoretical capacity of AgBr conversion is utilized.

[0048] Depend on Figure 7 It can be seen that after 1600 cycles on a high-voltage platform, the capacity retention rate of the secondary battery is 67%.

[0049] Depend on Figure 8 It can be seen that the full-voltage cycle capacity of a secondary battery is much higher than that of a conventional battery. Figure 7 (High-end platforms only) and Figure 6 The sum of (low-platform only) verifies the hypothesis that operating on the entire platform can improve overall performance. This demonstrates the dual advantages of the common ion effect and halogen reaction.

[0050] Depend on Figure 9 It can be seen that the secondary battery has a high charge-discharge rate, with a capacity of 131 mAh / g at a current density of 10 A / g. This good rate performance indicates that the system has fast reaction kinetics, which is attributed to the interaction of Ag / AgBr and Br. - / Br3 - Rapid mass transfer and charge transfer in redox reactions.

[0051] Combination Figure 8 and Figure 9 It can be seen that, combined with long cycle life and good rate performance, this zinc metal secondary battery system with silver halide cathode not only has high energy density, but also improved power characteristics and cycle performance, and has the potential to be applied in practice.

[0052] The discharge plateau range of the secondary battery in Example 2 was tested, with the full voltage test range being (0.4~1.9V). The test results are as follows: Figure 10 , 11 As shown.

[0053] Depend on Figure 10 It can be seen that the secondary battery exhibits a stable discharge plateau and a coulombic efficiency of 96.68% at a low voltage of 0.6V, proving the battery's reaction process and reversibility (Ag+I) at low potential. - →AgI+e - Furthermore, the secondary battery exhibited another discharge plateau at a higher voltage of 1.27V, confirming the existence of a second independent redox reaction (I3). - +2e - →3I - ).

[0054] Depend on Figure 11 It can be seen that the secondary battery, after 60 cycles at the full voltage platform, shows no significant capacity decay and can stably maintain a coulombic efficiency of 96.6%.

[0055] Therefore, this invention employs the aforementioned aqueous zinc metal secondary battery based on a silver halide cathode, cleverly utilizing the reversible participation of halide ions in multivalent state transformations during charge and discharge to construct a cathode reaction pathway based on a compound conversion mechanism with silver halide cathode as the initial active material. By introducing a certain concentration of halide ions into the electrolyte, on the one hand, excessive dissolution of the silver halide cathode driven by concentration gradient can be suppressed; on the other hand, a highly efficient and reversible redox process can be achieved by forming stable polyhalide intermediates. Using a neutral or weakly acidic zinc salt aqueous solution as the base electrolyte avoids the corrosion of the zinc anode by a strongly alkaline environment and effectively improves the electrochemical stability window and cycle durability of the entire battery system.

[0056] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the technical solutions of the present invention, and these modifications or equivalent substitutions cannot cause the modified technical solutions to deviate from the spirit and scope of the technical solutions of the present invention.

Claims

1. An aqueous zinc metal secondary battery based on a silver halide cathode, characterized in that: It includes an electrolyte, a positive electrode, a negative electrode, and a separator, wherein: The electrolyte is an aqueous solution containing zinc salts and halide ions; The positive electrode is made of silver halide material and is used for the redox reaction of silver halide at the interface between the positive electrode and the electrolyte. The negative electrode is made of zinc metal and is used for zinc metal redox reaction at the interface between the negative electrode and the electrolyte. A diaphragm is placed between the positive and negative electrodes.

2. The aqueous zinc metal secondary battery based on a silver halide cathode according to claim 1, characterized in that: The zinc salt concentration ranges from 0.1 to 4 mol / kg, and the halide ion concentration ranges from 0.05 to 2 mol / kg.

3. The aqueous zinc metal secondary battery based on a silver halide cathode according to claim 1, characterized in that: Silver halide materials consist of silver halide, binder, and carbon materials, with carbon materials and binder supported on the silver halide.

4. The aqueous zinc metal secondary battery based on a silver halide cathode according to claim 1, characterized in that: The zinc salt is one of zinc sulfate, zinc chloride, zinc nitrate, zinc gluconate, zinc lactate, zinc perchlorate, zinc tetrafluoroborate, zinc trifluoromethanesulfonate, zinc acetate, and zinc carbonate.

5. The aqueous zinc metal secondary battery based on a silver halide cathode according to claim 1, characterized in that: Halogen ions are one of the following: iodide ions, bromide ions, and chloride ions.

6. The aqueous zinc metal secondary battery based on a silver halide cathode according to claim 2, characterized in that: Silver halides are one of silver bromide, silver chloride, and silver iodide.

7. A water-based zinc metal secondary battery based on a silver halide cathode according to claim 2, characterized in that: The adhesive is one of CMC, PVDF, or PTFE.

8. A water-based zinc metal secondary battery based on a silver halide cathode according to claim 2, characterized in that: The carbon material is one or more of the following: graphite, graphene, carbon cloth, carbon paper, activated carbon, carbon fiber, carbon felt, graphite felt, acetylene black, and Ketjen black.

9. A water-based zinc metal secondary battery based on a silver halide cathode according to claim 1, characterized in that: The structure of an aqueous zinc metal secondary battery can be one of the following: button cell, cylindrical cell, square cell, or irregularly shaped cell.

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