Free manganese (II) inhibited anion-rich water system electrochemical system

Abstract

The invention relates to a free manganese (II) inhibited anion-rich aqueous electrochemical system which comprises a manganese positive electrode active material, a metal-based negative electrode and an aqueous electrolyte, the metal-based negative electrode comprises an active material and a dynamic auxiliary component, wherein the active material comprises at least one of metal zinc and zinc alloy. The method has the beneficial effects that the organic functionalized anion-rich aqueous electrolyte is innovatively used, and the types and concentrations of anions and cations are reasonably blended, so that the addition of Mn (II) and an organic solvent in the electrolyte is avoided, and the stability of the positive electrode material and the corrosivity and safety of the electrolyte are greatly improved; the electrolyte does not contain additional manganese (II) cations, and is matched with an active material with inhibited manganese dissolution, so that an interface passivation type deposition path from Mn (II) to Mn (IV) is blocked from the source, disproportionation of an Mn (III) intermediate and disordered deposition of low-conductivity Mn (IV) caused by disproportionation can be relieved at the same time, and dissolution inhibition of a manganese-containing positive electrode active material is effectively realized.

Description

Technical Field

[0001] The invention belongs to the technical field of energy storage materials, and in particular relates to an anion-rich aqueous electrochemical system suppressed by free manganese (II). Background Art

[0002] Among various energy storage methods, aqueous electrochemical energy storage technology has significant advantages such as flexible site selection, high energy efficiency, simple maintenance, no precision moving parts, and relative safety. At present, aqueous electrochemical systems represented by aqueous zinc-ion batteries are mainly committed to solving scientific problems of metal / alloy-based negative electrodes, including parasitic reactions and dendrite growth at the negative electrode interface. Its means usually include cation solvation regulation at the negative electrode interface, construction of negative electrode ion / electron conduction network, and use of interface modification coatings. Nevertheless, due to the existence of thermodynamic corrosion, the capacity deployment of negative electrode active materials is usually in a large excess state compared to the positive electrode; therefore, solving the problem of the negative electrode side interface in isolation can only focus on alleviating the problem of battery short circuit caused by parasitic reactions / dendrite growth, and cannot fundamentally solve the problem of energy storage device capacity decay with cycling.

[0003] In order to ultimately achieve the development of mature and stable aqueous electrochemical energy storage products, in-depth research on the positive electrode components with limited electrochemical capacity is also needed. Among the candidate positive electrode materials, manganese-based positive electrodes are one of the most promising positive electrode materials due to their low cost, low toxicity, high redox activity and potential. The failure of aqueous electrochemical energy storage devices based on manganese-containing positive electrode materials is mainly due to the structural collapse and irreversible dissolution of the positive electrode active materials. The conventional stabilization design of positive electrode active powders is also a one-sided and isolated optimization scheme, which has limited improvement in the stability of batteries in aqueous solvents. On the other hand, the scheme with electrolyte regulation as the main idea can be mainly divided into the auxiliary addition of Mn(II) cations and the use of high-concentration organic solvents. Both can play a certain role in improving the cycle stability, but the former is more of an ion compensation method rather than a fundamental solution to the dissolution of the positive electrode; while the latter's dependence on organic solvents not only inhibits the kinetics of ion diffusion, but also significantly reduces the high-temperature safety of the electrolyte.

[0004] In view of this, a new aqueous electrochemical system is urgently needed to solve the problem caused by the irreversible dissolution of manganese-containing active materials in the positive electrode into the aqueous electrolyte in aqueous electrochemical energy storage devices. Summary of the invention

[0005] The object of the present invention is to overcome the deficiencies in the prior art and provide an anion-rich aqueous electrochemical system suppressed by free manganese (II).

[0006] The free manganese (II) suppressed anion-rich aqueous electrochemical system comprises a manganese positive electrode active material, a metal-based negative electrode and an aqueous electrolyte; the metal-based negative electrode comprises an active material and a kinetic auxiliary component, and the active material comprises at least one of metallic zinc and a zinc alloy;

[0007] The solvent of the aqueous electrolyte is pure water, the water solvent accounts for 40-80% of the electrolyte mass fraction, the anion species are less than or equal to 3, and the molar concentration of the anions in the aqueous electrolyte is at least 3 times that of the positive electrode active cations.

[0008] Preferably, the manganese-containing positive electrode active material includes at least one of manganese oxide, lithium manganese oxide, sodium manganese oxide, potassium manganese oxide, manganese iron cyanide and manganese iron thiocyanide.

[0009] Preferably, in the metal-based negative electrode, the kinetic auxiliary component includes at least one of lithium vanadate, sodium vanadate, potassium vanadate, lithium titanium phosphate, sodium titanium phosphate, lithium titaniasilicate and sodium titaniasilicate, and the mass ratio of the kinetic auxiliary component to the metal-based active material is 1:50 to 1:2.

[0010] Preferably, in the aqueous electrolyte, the oxygen-containing acid corresponding to the anion has a functionalized organic grafted structure R, and the molecule of the oxygen-containing acid contains R(O) y X[(OH)] z The characteristic structure of R(O) y X represents R-[X=O] y The composite structural unit, X = O double bond number is the value of parameter y; X[(OH)] z represents X-[(OH)] z A single-bond structural unit, the number of single bonds is the value of the parameter z; the central atom X is selected from any one of boron, carbon, phosphorus and sulfur atoms; y∈{0,1,2}; z∈{1,2}; (y+z)∈{2,3}.

[0011] Preferably, the characteristic structure of the anion includes at least one of RB[(OH)]2, R(O)C[(OH)], R(O)P[(OH)]2 and R(O)2S[(OH)], the total concentration of the anions relative to the water solvent is 0.5-4.0 mol / kg, and the pH of the aqueous electrolyte is pH=4.0-7.0.

[0012] Preferably, the functionalized organic grafting structure R includes at least one polar functional group, and R includes at least one of an aromatic hydrocarbon group, an aromatic alcohol group, a thiol group, a hydroxyl hydrocarbon group, a carbonyl group, an amino group, an amide group, a sulfamide group, an ether group and a fluorine substituent; the oxygen-containing acid corresponding to the anion includes aminomethylboric acid, aminoacrylic acid, tyrosine, glutamic acid, lysine, aspartic acid, glutamine, cysteine, gluconic acid, ethylenediaminetetraacetic acid, tartaric acid, ethylenediaminetetramethylenephosphonic acid, diethylenetriaminepentamethylenephosphonic acid, triethylenetetraaminehexamethylenephosphonic acid, trifluoromethanesulfonic acid, benzenesulfonic acid, phenolsulfonic acid, acrylamide hydrocarbon sulfonic acid and at least one of the derivatives of the above oxygen-containing acids.

[0013] Preferably, in the aqueous electrolyte, active cations include at least one of lithium, sodium and potassium ions, and active cations also include at least one of zinc, magnesium, aluminum, ammonium and multi-stage ammonium ions.

[0014] The beneficial effects of the present invention are:

[0015] 1) The aqueous electrolyte used in the present invention has simple components and mild properties. Compared with the traditional electrolyte, the invention innovatively uses an organic functionalized anion-rich aqueous electrolyte, rationally adjusts the types and concentrations of anions and cations, avoids the addition of Mn(II) and organic solvents in the electrolyte, greatly improves the stability of the positive electrode material and the corrosiveness and safety of the electrolyte, and the electrolyte does not contain additional manganese(II) cations. In combination with the active material in which manganese dissolution is inhibited, the interfacial passivation deposition path of Mn(II)→Mn(IV) is blocked from the root, and the disproportionation of the Mn(III) intermediate and the disordered deposition of low-conductivity Mn(IV) caused by it can be alleviated at the same time, which not only improves the kinetic performance, but also reduces the corrosiveness and flammability of the organic solvent, and effectively realizes the dissolution inhibition of the manganese-containing positive electrode active material.

[0016] 3) The present invention designs a metal-based negative electrode containing a kinetic auxiliary component, extending the solution for stabilizing the electrochemical system to the negative electrode, achieving unity and compatibility, and is suitable for industrial product development. Through the synergistic inhibitory effects of the electrolyte and the negative electrode components, the inhibition of the phase change and dissolution competitive reactions of the positive electrode active material can be achieved, forming an aqueous electrochemical energy storage system in which active cations are fully and stably embedded and released on the positive electrode side; the negative electrode has a flexible formula, a simple preparation process, and a high degree of mass production feasibility, which can effectively improve the cycle stability of aqueous electrochemical energy storage devices. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 The battery cycle stability comparison between Example 3 and Comparative Example 1 and Comparative Example 2 is shown;

[0018] Figure 2The battery cycle stability comparison between Example 4 and Comparative Example 3 is shown;

[0019] Figure 3 The Mn element content in the battery electrolyte after cycles of Example 3, Comparative Example 4 and Comparative Examples 1 to 3 is compared. DETAILED DESCRIPTION

[0020] The present invention is further described below in conjunction with embodiments. The description of the following embodiments is only used to help understand the present invention. It should be noted that for ordinary persons in the art, without departing from the principle of the present invention, the present invention can also be modified in some ways, and these improvements and modifications also fall within the scope of protection of the claims of the present invention.

[0021] Embodiment 1

[0022] As an embodiment, in this embodiment 1, in view of the shortcomings of the prior art, the present invention designs a free manganese (II) suppressed anion-rich aqueous electrochemical system, and improves the stability of the manganese-containing positive electrode material through the coordinated design of the electrolyte and the negative electrode components, thereby improving the overall cycle stability of the aqueous electrochemical energy storage device, specifically, including:

[0023] Manganese-containing positive electrode active materials with active cation insertion and extraction as the target energy storage mechanism; metal-based negative electrodes containing kinetically auxiliary components; and organically functionalized anion-rich aqueous electrolytes.

[0024] Among them, the solvent of the aqueous electrolyte is pure water, and the water solvent accounts for 40-80% of the mass fraction of the electrolyte. The organic solvent-free formula reduces the corrosiveness of the electrolyte and improves its thermal safety.

[0025] In terms of electrolyte, an organic functionalized anion-rich aqueous electrolyte is used, and the types and concentrations of anions and cations are rationally adjusted to avoid the addition of Mn(II) and organic solvents to the electrolyte.

[0026] In terms of the negative electrode, by designing a metal-based negative electrode containing a kinetic auxiliary component, the kinetic performance and thermodynamic stability are optimized, which can effectively realize the aqueous electrochemical system in which the active cations are fully and stably embedded and extracted on the positive electrode side. The metal-based negative electrode comprises: at least one of metal zinc and its alloys as a metal-based active material for the negative electrode; a compound of active cation embedding and extraction type as a kinetic auxiliary component. Preferably, the kinetic auxiliary component comprises at least one of lithium vanadate, sodium vanadate, potassium vanadate, lithium titanium phosphate, sodium titanium phosphate, lithium titanosilicate, and sodium titanosilicate. The mass ratio of the kinetic auxiliary component to the metal-based active material is 1:50 to 1:2.

[0027] By adding kinetic auxiliary components, the kinetic characteristics and thermodynamic stability of the negative electrode are regulated: in terms of kinetics, by introducing auxiliary components of active cation embedding and extraction, they are matched with the electrochemical reaction kinetics of the positive electrode, avoiding battery failure caused by interfacial charge accumulation; in terms of thermodynamic stability, the introduction of auxiliary components slows down the (electro)chemical corrosion of metal-based negative electrode active materials, promoting the overall stabilization of the electrochemical system.

[0028] In the above electrochemical system, the manganese-containing positive electrode active material comprises at least one of manganese oxide, lithium manganese oxide, sodium manganese oxide, potassium manganese oxide, manganese iron cyanide, and manganese iron thiocyanide. The energy storage mechanism of the manganese-containing positive electrode active material is the insertion and extraction of active cations, and there is also a competitive reaction of proton insertion leading to phase change and dissolution.

[0029] Embodiment 2

[0030] As another embodiment, this embodiment 2 proposes, on the basis of the embodiment 1, a more specific free manganese (II) suppressed anion-rich aqueous electrochemical system, wherein the components and concentrations of the electrolyte are specifically matched as follows:

[0031] The electrolyte solvent is pure water, and the water solvent accounts for 40-80% of the electrolyte mass fraction, which plays a role of dispersion and dilution, and avoids the influence of organic solvent on the corrosion and thermal stability of the electrolyte. The types of anions in the electrolyte do not exceed 3, the total concentration of anions relative to the water solvent is 0.5-4.0 mol / kg, and the pH is pH=4.0-7.0.

[0032] In terms of solutes, in particular, the number of anion types does not exceed 3, and no additional manganese (II) cations are added, which can inhibit the disproportionation of Mn (III) and the disordered deposition of Mn (IV). By setting the aqueous electrolyte to have anion-rich characteristics, the dissolution of manganese-containing active positive electrode materials, the disproportionation of Mn (III) intermediates, and the disordered deposition of Mn (IV) can be inhibited at the same time. The electrolyte does not contain additionally introduced manganese (II) cations. Although the function of simple ion compensation is lost, it also greatly avoids the passivation type deposition of Mn (II) → Mn (IV) and avoids the formation of a poorly conductive deposition layer covering the surface of the positive electrode. At the same time, the design of the electrolyte further inhibits the generation and disproportionation of Mn (III), avoids the generation of free Mn (II), and further avoids the disproportionate deposition of Mn (III) → Mn (IV). At the same time, the inhibitory effects of the electrolyte and the negative electrode components work together to inhibit the phase change and dissolution competitive reactions of the positive electrode active materials, including inhibiting the disproportionation of Mn(III), the dissolution of Mn(II) ions, and the disordered deposition of Mn(IV) leading to the passivation of the positive electrode interface and other unfavorable reactions. Based on this, the target energy storage mechanism of embedding and extracting manganese-containing positive electrode active materials can be achieved.

[0033] The preferred electrolyte has a simple formula, and all solutes contain no more than three types of anions. Specifically, the oxygen-containing acid corresponding to the anion has a functionalized organic graft structure R, and a characteristic structure related to R: R(O) y X[(OH)] z . Among them R(O) y X represents a composite structural unit of R-[X=O]y, where the number of double bonds in X=O is the value of parameter y; X[(OH)] z Represents the single-bond structural unit of X-[(OH)]z, and the number of single bonds is the value of the parameter z.

[0034] Preferably, the central atom X is selected from any one of boron, carbon, phosphorus and sulfur atoms. Parameters y and z simultaneously satisfy the following conditions: 1) parameter y can be any one of 0, 1 and 2; 2) parameter z can be any one of 1 and 2; 3) the sum of parameter y+z can be any one of 2 and 3. Based on the above restrictive conditions, the above anion characteristic structure R(O) y X[(OH)] z Preferably, it is at least one of RB[(OH)]2, R(O)C[(OH)], R(O)P[(OH)]2, and R(O)2S[(OH)], and no more than three.

[0035] Based on the above-summarized preferred conditions, it should be particularly pointed out that the solute of the electrolyte does not contain traditional sulfates and halides. The former, as a typical inorganic oxygen acid salt, has defects such as limited solubility, small pH range of stabilization, and easy passivation of the positive electrode. Although the latter has high solubility, it is accompanied by strong acidity, strong hydrolysis, strong corrosion, and high cost, making it difficult to produce electrochemical energy storage devices with industrial value.

[0036] Therefore, the scheme disclosed in the present invention is an organic functionalized anion-rich solute and a combination thereof. Preferably, the functionalized organic grafting structure R contains at least one polar functional group and can optionally link one or more of the above-mentioned characteristic structures. Preferably, R can be selected from at least one of an aromatic hydrocarbon group, an aromatic alcohol group, a thiol group, a hydroxyl hydrocarbon group, a carbonyl group, an amino group, an amide group, a sulfamide group, an ether group, and a fluorine substituent group. Preferably, the R(O)-containing y X[(OH)] z The oxygen-containing acid corresponding to the anion of the characteristic structure can be selected from: aminomethylboric acid, aminoacrylic acid, tyrosine, glutamic acid, lysine, aspartic acid, glutamine, cysteine, gluconic acid, ethylenediaminetetraacetic acid, tartaric acid, ethylenediaminetetramethylenephosphonic acid, diethylenetriaminepentamethylenephosphonic acid, triethylenetetraaminehexamethylenephosphonic acid, trifluoromethanesulfonic acid, benzenesulfonic acid, phenolsulfonic acid, acrylamide hydrocarbon sulfonic acid and at least one of their derivatives.

[0037] Further, considering the compatibility of salts and the multi-element synergistic effect, an anion-rich structure is proposed in the scheme of the present invention. The active cation is at least one of lithium, sodium, and potassium ions; the other cations added to ensure charge neutrality are at least one of zinc, magnesium, aluminum, ammonium, and multi-level ammonium ions. Preferably, the molar concentration of the total anion is at least 3 times that of the active cations of the positive electrode. For aqueous electrochemical systems, the use of uniform solute components, especially a single active cation component, has a contradiction in the preferred concentration: at low concentrations, not only is there not enough ion concentration to ensure high conductivity, but the number of functionalized anions is also relatively scarce, resulting in large polarization and poor stability of the aqueous electrochemical system; at high concentrations, it is easy to cause ion crowding and microscopic clusters, which also limits the conductivity of the solution and tends to affect the uniformity of the interfacial reaction. Therefore, the optimization scheme proposed by the present invention is to regulate the type and concentration distribution of cations at a moderate functionalized anion concentration to balance the physical and chemical properties of the electrolyte and the characteristics of the kinetics. The preferred electrolyte has a concentration of organic functionalized anions that is several times higher than the concentration of active cations, and is therefore an anion-rich aqueous electrolyte system.

[0038] It should be noted that the parts in this embodiment that are the same or similar to those in the first embodiment can be referenced to each other and will not be described in detail in this application.

[0039] Embodiment 3

[0040] As another embodiment, this embodiment 3 proposes a specific anion-rich aqueous electrochemical system with free manganese (II) inhibition based on embodiments 1 and 2:

[0041] In this embodiment, the manganese-containing positive electrode active material is manganese oxide rich in ion insertion and extraction pathways; the negative electrode active material is metal zinc and sodium vanadate, and the molar ratio of sodium vanadate to metal zinc is 1:20. The solvent of the aqueous electrolyte is pure water.

[0042] The preparation method of the aqueous electrolyte is as follows: take 10kg of deionized water, add 2.29kg of sodium acrylamide methyl propane sulfonate, 2.28kg of zinc gluconate, 2.07kg of magnesium gluconate, and 1.67kg of ammonium trifluoromethanesulfonate in sequence, and continue stirring for 1 hour until fully dissolved, and finally use gluconic acid or sodium hydroxide to fine-tune the pH to 4.5. During the above configuration process, heating in the range of 50 to 70°C is performed to promote the dissolution of the solute, or filtration is performed to remove a small amount of impurity components. The active cation in the above electrolyte is sodium ion, and the molar ratio to the total anion is 1:4; for sodium ions, the electrolyte belongs to the anion-rich type.

[0043] Embodiment 4

[0044] As another example, based on Example 3, Example 4 proposes another free manganese (II) suppressed anion-rich aqueous electrochemical system prepared using the same method:

[0045] In this embodiment, the preparation method of the anion-rich aqueous electrochemical system suppressed by free manganese (II) is the same as that in Example 3, but the components used are different. Specifically, the negative electrode active material is changed to metallic zinc and lithium titanium phosphate, and the molar ratio of lithium titanium phosphate to metallic zinc is 1:3. When the aqueous electrolyte is configured, the solute used is changed to, 1.52 kg of dilithium ethylenediaminetetraacetic acid, 3.27 kg of sodium gluconate, and 1.19 kg of sodium trifluoromethanesulfonate are added in sequence, and stirring is continued for 1 hour until fully dissolved, and finally ethylenediaminetetraacetic acid or sodium hydroxide is used to fine-tune the pH to 7.0. The active cations in the above electrolyte are lithium ions, and the molar ratio to the total anions is 1:3; for lithium ions, the electrolyte belongs to the anion-rich type.

[0046] In this embodiment, the components and preparation methods of the unmentioned parts are the same as those in Embodiment 3.

[0047] Comparative Example 1

[0048] As a comparative example, this comparative example 1 proposes an electrochemical system made of a traditional sulfate electrolyte that does not have the characteristics of inhibiting free manganese (II) cations, Mn (III) intermediates, and Mn (IV) deposition products:

[0049] In this comparative example, the positive and negative electrode materials are the same as those in Example 3, that is, the manganese-containing positive electrode active material is a manganese oxide rich in ion insertion and extraction pathways; the negative electrode active material is metallic zinc and sodium vanadate, and the molar ratio of sodium vanadate to metallic zinc is 1:20. The solvent of the aqueous electrolyte is pure water.

[0050] The preparation method of aqueous electrolyte is as follows: take 10kg of deionized water, add 1.42kg of sodium sulfate, 0.81kg of zinc sulfate, 0.60kg of magnesium sulfate, and 1.32kg of ammonium sulfate in sequence, and continue stirring for 1 hour until fully dissolved, and finally use sulfuric acid or sodium hydroxide to fine-tune the pH to 4.5. Similarly, heating in the range of 50-70℃ is performed to promote the dissolution of the solute, or filtering is performed to remove a small amount of impurities.

[0051] Comparative Example 2

[0052] As another comparative example, this comparative example 2 proposes an electrochemical system made of an aqueous electrolyte that does not have the characteristics of rich anions:

[0053] In this comparative example, the positive and negative electrode materials are the same as those in Example 3, that is, the manganese-containing positive electrode active material is a manganese oxide rich in ion insertion and extraction pathways; the negative electrode active material is metallic zinc and sodium vanadate, and the molar ratio of sodium vanadate to metallic zinc is 1:20. The solvent of the aqueous electrolyte is pure water.

[0054] The preparation method of the aqueous electrolyte is as follows: take 10kg of deionized water, add 2.29kg of sodium acrylamide methyl propane sulfonate, 4.36kg of sodium gluconate, and 1.72kg of sodium trifluoromethanesulfonate in sequence, and continue stirring for 1 hour until fully dissolved, and finally use gluconic acid or sodium hydroxide to fine-tune the pH to 4.5. Optionally, heating in the range of 50 to 70°C can be performed to promote solute dissolution, or filtration can be performed to remove a small amount of impurity components. The active cation in the above electrolyte is sodium ion, and the molar ratio with the total anion is 1:1, and it does not have the characteristics of rich anions.

[0055] Comparative Example 3

[0056] As another comparative example, this comparative example 3 proposes another electrochemical system made of a negative electrode of a pure metal-based active material without a kinetic auxiliary component:

[0057] In this comparative example, the positive electrode material is the same as that in Example 4, namely, lithium manganese oxide rich in ion insertion and extraction pathways. In this comparative example, the negative electrode active material is different, namely, a pure metal-based active material composed of metallic zinc.

[0058] Among them, the aqueous electrolyte is the same as that in Example 4. The solvent is pure water. The preparation method of the aqueous electrolyte is as follows: take 10 kg of deionized water, add 1.52 kg of dilithium ethylenediaminetetraacetic acid, 3.27 kg of sodium gluconate, and 1.19 kg of sodium trifluoromethanesulfonate in turn, and continue stirring for 1 hour until fully dissolved, and finally use ethylenediaminetetraacetic acid or sodium hydroxide to fine-tune pH = 7.0. Optionally, heating in the range of 50 to 70°C is performed to promote solute dissolution, or filtration is performed to remove a small amount of impurity components. The active cations in the above electrolyte are lithium ions, and the molar ratio to the total anions is 1:3; for lithium ions, the electrolyte is anion-rich type.

[0059] The battery cycle stability test of the electrochemical system obtained in Example 3, Example 4, Comparative Example 1, Comparative Example 2, and Comparative Example 3 was carried out under 100 cycles, and the Mn element content in the battery electrolyte after the cycle was measured, as shown in FIG. Figures 1 to 3 As shown:

[0060] like Figure 1 As shown, the battery in Example 3 has a capacity retention rate of 97.3% after 100 cycles, the battery in Comparative Example 1 has a capacity retention rate of 60.7% after 100 cycles, and the battery in Comparative Example 2 has a capacity retention rate of 71.6% after 100 cycles. The electrochemical system proposed in the present invention has a significantly higher cycle stability than Comparative Examples 1 and 2 due to the provision of an organic functionalized anion-rich aqueous electrolyte.

[0061] like Figure 2 As shown, the capacity retention rate of the battery in Example 4 after 100 cycles is >100%, while the capacity retention rate of the battery in Comparative Example 3 after 100 cycles is 72.9%. It can be seen that the electrochemical system proposed in the present invention has a significantly higher cycle stability than that of Comparative Example 3 due to the addition of non-kinetic auxiliary components.

[0062] like Figure 3As shown, from the element test results of ICP, the manganese content in the electrolyte after circulation in Example 3 and Example 4 is less than or equal to 1ppm, and almost no free Mn element is detected. Considering the stability of manganese elements in various valence states, the Mn element measured in ICP mainly exists in the form of Mn (II) cations. However, there is obvious Mn element in Comparative Examples 1 to 3, among which the free manganese content in Comparative Example 1 is the largest, reaching 798ppm. It can be seen that the electrochemical system proposed by the present invention does have extremely high free manganese (II) inhibition performance.

[0063] Based on the above results, the technical solutions disclosed in the present invention including Example 3 and Example 4, and the electrochemical system proposed in the present invention can inhibit the dissolution of manganese-containing materials and improve the cycle stability of the battery.

[0064] The various embodiments in this specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the various embodiments can be referenced to each other.

Claims

1. A free manganese (II) suppressed anion-rich aqueous electrochemical system, characterized in that: include: A manganese-containing positive electrode active material, a metal-based negative electrode and an aqueous electrolyte; the metal-based negative electrode comprises an active material and a kinetic auxiliary component, and the active material comprises at least one of metallic zinc and a zinc alloy; The solvent of the aqueous electrolyte is pure water, the water solvent accounts for 40-80% of the electrolyte mass fraction, the anion species are less than or equal to 3, and the molar concentration of the anions in the aqueous electrolyte is at least 3 times that of the positive electrode active cations.

2. The free manganese (II) suppressed anion-rich aqueous electrochemical system according to claim 1, characterized in that: The manganese-containing positive electrode active material includes at least one of manganese oxide, lithium manganese oxide, sodium manganese oxide, potassium manganese oxide, manganese iron cyanide and manganese iron thiocyanide.

3. The free manganese (II) suppressed anion-rich aqueous electrochemical system according to claim 1, characterized in that: In the metal-based negative electrode, the kinetic auxiliary component includes at least one of lithium vanadate, sodium vanadate, potassium vanadate, lithium titanium phosphate, sodium titanium phosphate, lithium titanosilicate and sodium titanosilicate, and the mass ratio of the kinetic auxiliary component to the metal-based active material is 1:50 to 1:

2.

4. The free manganese (II) suppressed anion-rich aqueous electrochemical system according to claim 1, characterized in that: In the aqueous electrolyte, the oxygen-containing acid corresponding to the anion has a functionalized organic grafted structure R, and the molecule of the oxygen-containing acid contains R(O) y X[(OH)] z The characteristic structure of R(O) y X represents R-[X=O] y The composite structural unit, X = O double bond number is the value of parameter y; X[(OH)] z represents X-[(OH)] z The single-bond structural unit is a single-bond unit, and the number of single bonds is the value of the parameter z; The central atom X is selected from any one of boron, carbon, phosphorus and sulfur atoms; y∈{0,1,2}; z∈{1,2}; (y+z)∈{2,3}.

5. The free manganese (II) suppressed anion-rich aqueous electrochemical system according to claim 4, characterized in that: The characteristic structure of the anion includes at least one of RB[(OH)]2, R(O)C[(OH)], R(O)P[(OH)]2 and R(O)2S[(OH)], the total concentration of the anion relative to the water solvent is 0.5-4.0 mol / kg, and the pH value of the aqueous electrolyte is pH=4.0-7.

0.

6. The free manganese (II) suppressed anion-rich aqueous electrochemical system according to claim 4, characterized in that: The functionalized organic grafting structure R includes at least one polar functional group, and R includes at least one of an aromatic hydrocarbon group, an aromatic alcohol group, a thiol group, a hydroxyl hydrocarbon group, a carbonyl group, an amino group, an amide group, a sulfamide group, an ether group and a fluorine substituent group; the oxygen-containing acid corresponding to the anion includes at least one of aminomethylboric acid, aminoacrylic acid, tyrosine, glutamic acid, lysine, aspartic acid, glutamine, cysteine, gluconic acid, ethylenediaminetetraacetic acid, tartaric acid, ethylenediaminetetramethylenephosphonic acid, diethylenetriaminepentamethylenephosphonic acid, triethylenetetraaminehexamethylenephosphonic acid, trifluoromethanesulfonic acid, benzenesulfonic acid, phenolsulfonic acid, acrylamide hydrocarbon sulfonic acid and derivatives of the above oxygen-containing acids.

7. The free manganese (II) suppressed anion-rich aqueous electrochemical system according to claim 1, characterized in that: In the aqueous electrolyte, the active cations include at least one of lithium, sodium and potassium ions, and the active cations also include at least one of zinc, magnesium, aluminum, ammonium and multi-stage ammonium ions.

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